The review, published in the journal Physiological Reports, frames mitochondrial dysfunction as a central mechanism in cardiovascular disease. Mitochondria are the organelles that generate most of a cell’s ATP through oxidative phosphorylation, and when they fail to meet cellular energy demands, several problems follow: ATP synthesis declines, reactive oxygen species accumulate, and the resulting oxidative burden damages cellular components. Within blood vessels, excess reactive oxygen species react with and deplete nitric oxide, the molecule that endothelial cells release to relax arteries. Less nitric oxide means impaired vasodilation, reduced blood flow, and greater cardiovascular strain—a pathological cycle that compounds over years and elevates long-term disease risk.

At the center of the proposed mechanism sits PGC-1α, widely regarded as the master regulator of mitochondrial biogenesis, alongside its relatives PGC-1β and PGC-1-related coactivator. These coactivators regulate the mitochondrial quality of skeletal muscle, cardiac muscle, and the vascular wall, coordinating programs of gene expression that build and maintain mitochondria in these tissues. Experimental work shows that when PGC-1α or PGC-1β expression falls, mitochondrial function deteriorates, oxidative stress resilience drops, and adaptive responses blunt. Conversely, forcing PGC-1α expression in cardiac muscle increases mitochondrial biogenesis, oxidative phosphorylation gene expression, fatty acid oxidation, and coupled respiration, while losing PGC-1α produces the opposite phenotype and impairs cardiac and metabolic responses.

Estradiol has long been described as cardioprotective: it increases endothelial nitric oxide synthase activity and nitric oxide–mediated vasodilation, enhances antioxidant and anti-inflammatory defenses, and promotes angiogenesis and anti-atherogenic signaling. The review’s key contribution is to connect these well-known effects to PGC-1 regulation through several distinct signaling routes. In the classical genomic pathway, estradiol diffuses across the cell membrane and binds intracellular estrogen receptors ERα or ERβ, which dimerize and bind estrogen response elements in the regulatory regions of target genes. PGC-1α and PGC-1β act as coactivators of these receptors—their LXXLL motifs engage the receptors’ activation function-2 domain—helping assemble transcriptional complexes that switch on genes for mitochondrial biogenesis such as NRF-1 and TFAM, mitochondrial DNA–encoded respiratory genes, nuclear-encoded oxidative phosphorylation genes, and antioxidant defenses like SOD2.

Beyond this direct route, the review details a tethered genomic mechanism in which ligand-bound estrogen receptors interact with transcription factors already bound to DNA—activator protein-1, NF-κB, and Sp1—thereby modulating stress-response, inflammatory, and tissue-specific gene programs without directly binding estrogen response elements. There is also rapid, non-genomic signaling: membrane-associated estrogen receptors, including palmitoylated ERα targeted to caveolae, trigger kinase cascades within seconds to minutes. These include p38 MAPK, a positive regulator of PGC-1α expression and activity, and PI3K/Akt signaling, which promotes eNOS phosphorylation and nitric oxide production while regulating glucose and lipid metabolism and intracellular calcium handling—elevated calcium activating CaMK and calcineurin pathways that can further promote PGC-1α expression.

A third route runs through GPER, the G protein–coupled estrogen receptor, which is largely intracellular but remains accessible to estrogen. Upon ligand binding, GPER activates Src family kinases, which trigger matrix metalloproteinase–mediated release of heparin-binding epidermal growth factor, transactivating the epidermal growth factor receptor and downstream cascades including p38 MAPK, PI3K/Akt, ERK1/2, AMPK, and cAMP/PKA. Two of these are especially relevant to mitochondrial regulation: AMPK can activate PGC-1α through phosphorylation, and SIRT1-mediated deacetylation further increases PGC-1α activity. In ovariectomized mice treated with 17β-estradiol, estradiol engaged an ERα–SIRT1 pathway that deacetylated and activated PGC-1α in liver, preserving mitochondrial function after ovarian hormone loss.

Human evidence, though more limited, is consistent with these mechanisms. Women within six years of menopause who received short-term, high-dose transdermal 17β-estradiol showed increased nuclear skeletal muscle PGC-1α abundance—about 22 percent—and greater AMPK phosphorylation. Notably, this responsiveness appeared in early but not late postmenopausal women, suggesting a window of timing dependence. Separately, long-term users of combined estradiol–progestin therapy exhibited greater skeletal muscle mitochondrial content and respiratory capacity, along with lower visceral and total fat mass, compared with matched nonusers. In young adult men, estradiol supplementation increased PGC-1α mRNA by 29 percent, hinting that the pathway is not exclusive to females. In rodents, chronic selective ERα activation in aged, high-fat-fed ovariectomized mice increased cardiac PGC-1α and NRF-1 expression, improved mitochondrial respiration, and enhanced insulin sensitivity and adiposity measures.

The review is careful to note that physiological estradiol fluctuations in healthy women produce more modest and context-dependent effects than the dramatic changes seen in experimental models. Studies comparing menstrual cycle phases have yielded mixed results: one reported reduced phosphocreatine recovery and ATP generation during the low-hormone early follicular phase compared with the high-estradiol late follicular phase, while another found no differences in maximal mitochondrial oxidative capacity or citrate synthase activity between phases, detecting only subtle changes in proton leak respiration and reactive oxygen species emission. Findings on substrate use during exercise across hormone phases are similarly contested. The clearest signal emerges with the menopause transition itself, when estradiol fluctuations become erratic—beginning on average four to seven years before the final menstrual period—and progesterone becomes variable, contributing to anovulatory cycles. Some data suggest progesterone increases mitochondrial reactive oxygen species emission regardless of estradiol availability and reduces respiration when estradiol is low, potentially compounding oxidative stress as cycles falter.

Cell-specific details add texture to the picture. Cardiomyocytes predominantly express full-length ERα66, while human endothelial cells are rich in the truncated ERα46, which efficiently mediates rapid, membrane-initiated vascular signaling through PI3K/Akt and MAPK to activate eNOS and nitric oxide production. Endothelial ERα expression is approximately 33 percent lower in postmenopausal women than in premenopausal women during the late follicular phase, and this reduction is associated with diminished vasodilatory capacity and greater susceptibility to atherosclerotic vascular dysfunction. In mouse models of heart failure, the PGC-1α promoter contains an ERα-binding site within its first 600 base pairs, and estradiol significantly increased PGC-1α promoter activity only in the presence of ERα—underscoring that sufficient receptor expression, not merely higher estradiol, is required for the genomic signaling that maintains mitochondrial gene programs. Female cardiomyocytes also show greater mitochondrial resilience than male cells, with more efficient respiratory chain organization, lower reactive oxygen species, and better calcium handling.

The review’s authors conclude that declining estradiol during the menopause transition may impair mitochondrial function by reducing pathways that support PGC-1 signaling, and that late perimenopause through early postmenopause represents a critical window of low estradiol availability that may raise cardiovascular risk in part through this mechanism. They also address the contested history of hormone therapy: after the 2002 Women’s Health Initiative trial linked hormone use to increased risks of breast cancer, stroke, coronary heart disease, and venous thromboembolism, US menopausal hormone therapy use dropped by 80 percent. More recently, a longitudinal cohort study of 876,805 women reported no increased risk of all-cause mortality with menopausal hormone therapy use, a discrepancy likely explained by the WHI participants being ten or more years postmenopause with an average age of 63 and many existing cardiometabolic diagnoses. The authors call for future studies to determine whether estradiol loss alters PGC-1–mediated cardiovascular pathways in an isoform-specific manner, and whether hormonal or non-hormonal strategies—such as exercise, which restored skeletal muscle PGC-1α in ovariectomized mice through AMPK/SIRT1 signaling independent of estradiol—can preserve mitochondrial function despite declining ovarian hormones. Direct measurements of estradiol–ERα signaling in human cardiomyocytes and endothelial cells across perimenopause remain limited, and the review’s proposals are framed as mechanisms to be tested rather than established clinical benefits.

Subject of Research: Estradiol regulation of PGC-1 coactivator signaling and cardiovascular mitochondrial health across the menopause transition

Article Title: Estradiol—PGC‐1 signaling in mitochondrial health: Implications for perimenopause and cardiovascular disease

Article References: Parten, A. L., & Rowe, G. C. (2026). Estradiol— PGC ‐1 signaling in mitochondrial health: Implications for perimenopause and cardiovascular disease. Physiological Reports, 14(20), Article e71155. https://doi.org/10.14814/phy2.71155

Image Credits: AI Generated

DOI: 10.14814/phy2.71155

Keywords: estradiol, PGC-1alpha, mitochondria, menopause, cardiovascular disease, estrogen receptors, perimenopause, hormone therapy, endothelial function, oxidative phosphorylation, GPER, women's health

The hospital-based study analyzed routinely collected records from 109 adults with type 2 diabetes who completed a multidisciplinary assessment pathway at the First Affiliated Hospital of Sun Yat-sen University in Guangzhou between June 2015 and December 2019. Forty-six participants had no diabetic retinopathy, 36 had non-proliferative retinopathy and 27 had proliferative retinopathy. All received dilated fundus examinations and standardized fundus photography, and vascular ultrasound was performed irrespective of retinopathy status or cardiovascular risk profile. Because the data were collected during standard inpatient care rather than under a prospective research protocol, the analysis was cross-sectional and retrospective.

Two retinal specialists, blinded to clinical and ultrasound findings, graded each participant using the International Clinical Diabetic Retinopathy Disease Severity Scale. When the eyes differed, the participant was assigned the more severe grade. Because the numbers with mild, moderate and severe non-proliferative disease were too small for the intended statistical model, those categories were combined after the fact, reducing the ability to resolve differences within that stage. The investigators also examined carotid artery diameter, intima–media thickness and plaque presence as secondary outcomes. These comparisons were exploratory, and the group-wide statistical tests were not designed to test an ordered trend.

FMD is a noninvasive measure of endothelium-dependent vasodilation. During the examination, participants fasted and avoided caffeine, alcohol, smoking, vigorous exercise and vasoactive medication before resting supine for 15 minutes in a temperature-controlled room. An ultrasound operator measured the right brachial artery at rest, inflated a forearm cuff to 250 mm Hg for five minutes and recorded the artery after cuff release. FMD was calculated from the change between baseline and maximum post-deflation diameter relative to baseline. All examinations used the same equipment, protocol and experienced sonographer, but formal intraobserver repeatability was not assessed and post-deflation Doppler flow velocity was unavailable.

The main statistical model was a proportional-odds analysis treating retinopathy severity as an ordered outcome: no retinopathy, non-proliferative disease and proliferative disease. It simultaneously included FMD, MPV, age, sex, diabetes duration, glycated hemoglobin and systolic blood pressure. Of the 109 participants, 86 had complete data for this model—36 without retinopathy, 30 with non-proliferative disease and 20 with proliferative disease. The remaining 23 lacked MPV, glycated hemoglobin or both, and excluded participants had higher blood urea nitrogen and creatinine, raising the possibility of complete-case selection bias. The model was selected on clinical grounds rather than prospectively prespecified, and all estimates were treated as exploratory.

In that 86-person model, each one-percentage-point increase in FMD was associated with an adjusted odds ratio of 0.831 for greater retinopathy severity, with a 95% confidence interval of 0.713 to 0.968 and a P value of .018. In the opposite direction, each 1-femtoliter increase in MPV was associated with an adjusted odds ratio of 1.898, with a 95% confidence interval of 1.238 to 2.912 and a P value of .003. Diagnostic checks did not detect a violation of the proportional-odds assumption or a detectable nonlinear relationship among the continuous predictors, and leave-one-out refits retained the direction of both associations. Nevertheless, the modest sample, multiple analyses and lack of multiplicity adjustment make these results hypothesis-generating rather than confirmatory.

The associations changed when potential confounding and model stability were examined. Adding recorded diabetic nephropathy attenuated the FMD estimate to an odds ratio of 0.855, with a 95% confidence interval of 0.732 to 0.998, while the MPV estimate was preserved at 2.166, with a 95% confidence interval of 1.356 to 3.458. Renal status appeared more common as retinopathy advanced: recorded nephropathy affected 2.2% of participants without retinopathy, 16.7% with non-proliferative disease and 29.6% with proliferative disease. However, the analysis lacked participant-level estimated glomerular filtration rate and albuminuria, so the chart-based nephropathy variable may have misclassified renal disease and did not fully resolve confounding by kidney disease.

A ridge-penalized model offered a second warning about effect magnitude. At a penalty selected by repeated stratified cross-validation, the FMD odds ratio moved closer to the null, from 0.831 to 0.899 at the minimum-loss penalty and 0.919 at the one-standard-error penalty. The corresponding MPV estimates declined more sharply, from 1.898 to 1.388 and 1.289. Because penalized coefficients are shrunk toward zero by design, these figures are not corrected effect estimates; their attenuation nevertheless indicates that the unpenalized estimates may overstate the strength of the relationships in this small sample. Additional one-at-a-time adjustments for medication classes, carotid plaque, baseline brachial diameter and exclusion of the two participants with heart failure did not materially change the main estimates.

Secondary carotid findings were consistent with greater vascular abnormality among participants with more advanced eye disease, but they do not demonstrate that macrovascular changes caused retinopathy. Right carotid intima–media thickness had medians of 0.70, 0.80 and 0.89 millimeters across the three retinopathy categories, while any carotid plaque was present in 43.5%, 62.9% and 70.4%. Blood urea nitrogen and the triglyceride-to-HDL cholesterol ratio also differed across groups, while most major demographic, glycemic and blood-pressure comparisons did not show clear differences. These unadjusted group comparisons cannot establish temporal sequence and were vulnerable to confounding.

Several design features sharply limit interpretation. The hospital sample may not represent people with type 2 diabetes in the wider community, and indications for admission were not systematically recorded. The cross-sectional measurements cannot show whether lower FMD and larger platelets preceded retinal disease or instead reflected other complications, hospitalization-related changes or treatment. Eye imaging used one macula-centered 45-degree photograph per eye rather than widefield or multifield imaging, so peripheral lesions could have been missed. MPV was measured with one analyzer, making comparison within the study appropriate but limiting transfer of absolute values to other platforms. Because diabetic macular edema was documented for only 51 participants with highly uneven missingness, it could not be compared reliably.

The clearest conclusion is therefore narrow: in this selected group of hospitalized adults with type 2 diabetes, lower brachial FMD and higher MPV accompanied more severe diabetic retinopathy. The FMD relationship was sensitive to adjustment for recorded nephropathy, while both estimates weakened under penalization, especially the MPV association. The results do not establish causality, temporal sequence, predictive performance, diagnostic cutoffs or clinical utility. They instead provide a rationale for larger, prospective, multicenter cohorts to test whether endothelial function and platelet characteristics can help explain or anticipate the progression of diabetic eye disease.

Subject of Research: Cross-sectional associations of brachial FMD and mean platelet volume with diabetic retinopathy severity in adults with type 2 diabetes.

Article Title: Brachial artery flow-mediated dilation and mean platelet volume in relation to diabetic retinopathy severity in type 2 diabetes: a retrospective cross-sectional study

Article References: Zeng, Y., Wang, C., Huang, Z., Chen, T., Yao, F., & Zhu, W. (2026). Brachial artery flow-mediated dilation and mean platelet volume in relation to diabetic retinopathy severity in type 2 diabetes: a retrospective cross-sectional study. Frontiers in Endocrinology, 17, Article 1911136. https://doi.org/10.3389/fendo.2026.1911136

Image Credits: AI Generated

DOI: 10.3389/fendo.2026.1911136

Keywords: diabetic retinopathy, type 2 diabetes, flow-mediated dilation, mean platelet volume, endothelial function, platelet size, vascular ultrasound, retinopathy severity, cross-sectional study, Brachial, artery, flow-mediated

The study provides preliminary stroke-specific error estimates for determining when a repeated measurement differs by more than ordinary measurement variation. Participants were eligible if they were 50 to 80 years old, had experienced their stroke at least 12 months earlier and could walk at least 10 meters independently, with or without an assistive device. The analyzed group had a mean age of 63.9 years, a mean body mass index of 31.2 kilograms per square meter and a mean time since stroke of 4.5 years.

Four participants were female. Median scores indicated mild stroke severity, mild cognitive impairment and reduced arm spasticity. Participants had mild neurological impairment and were generally able to follow the standardized procedures, so the results describe a relatively narrow chronic-stroke population rather than people in acute recovery or with severe disability.

Investigators measured pulse-wave velocity in the carotid-femoral, carotid-radial and femoral-dorsalis pedis arterial segments. The carotid-femoral segment was treated as the measure of central arterial stiffness, while the other two represented peripheral arterial sites. Noninvasive applanation tonometers recorded pressure waveforms at the proximal and distal sites, and pulse-wave velocity was calculated as the distance between those sites divided by the time delay between waveform arrival.

Each measurement was collected twice on both the paretic and non-paretic sides and averaged over 30 consecutive cardiac cycles. The surface-distance estimates used in the calculations were consistent across repeated measurements and between limbs, although the study did not establish that these distances caused or contributed to the observed reliability estimates. Carotid-femoral pulse-wave velocity had a standard error of measurement of 0.80 meters per second in paretic limbs and 0.61 meters per second in non-paretic limbs.

Its minimal detectable change at 95% confidence was 2.23 meters per second and 1.68 meters per second, respectively. By comparison, carotid-radial pulse-wave velocity had poor relative reliability, with intraclass correlation coefficients of 0.33 in paretic limbs and 0.24 in non-paretic limbs. Its 95% minimal detectable changes were 2.82 and 3.23 meters per second.

Femoral-dorsalis pedis pulse-wave velocity also performed poorly, with coefficients of 0.12 and 0.28 and minimal detectable changes of 4.71 and 4.09 meters per second. Confidence intervals for these estimates were wide, reflecting the small numbers of participants with usable site-specific data. Brachial artery flow-mediated dilation was evaluated with duplex ultrasound through a 30-second baseline recording, a five-minute ischemic-occlusion phase and three minutes of reactive hyperemia after rapid cuff deflation.

The cuff was inflated to 200 mmHg distal to the cubital fossa. Absolute dilation, expressed as the difference between peak and baseline artery diameter in millimeters, showed poor reliability: the intraclass correlation coefficient was 0.11 in paretic limbs and 0.44 in non-paretic limbs. Its 95% minimal detectable changes were 0.29 and 0.34 millimeters.

Relative dilation, calculated with allometric scaling, had moderate reliability, with coefficients of 0.50 in paretic limbs and 0.59 in non-paretic limbs. The corresponding 95% minimal detectable changes were 6.88% and 7.65%. The central finding was not a pronounced difference between paretic and non-paretic limbs.

Instead, the arterial site appeared more consequential: carotid-femoral pulse-wave velocity was much more reproducible than either peripheral pulse-wave measurement, while relative and absolute flow-mediated dilation showed similar broad patterns on the two sides. The investigators noted that peripheral arteries are smaller, more muscular and more responsive to vasodilatory stimuli than larger central arteries. They also considered post-stroke changes in sympathetic activity, muscle tone and spasticity, along with cardiovascular risk factors, as possible contributors to peripheral measurement variability.

Flow-mediated dilation displayed a different reliability pattern from central stiffness. Baseline and peak artery diameters were broadly similar between the two visits, yet the derived change score was not stable, especially when expressed in millimeters. The investigators suggested that variability in baseline measurements may have affected absolute dilation more than the scaled percentage measure, although this mechanism was not directly examined.

They also emphasized the use of experienced sonographers, stable probe positioning and automated edge-detection software when seeking greater precision. The sample’s relative dilation values of roughly 4% to 7% were consistent with the pooled estimate from a meta-analysis of post-stroke studies, but that broader literature showed extremely high heterogeneity and included values ranging from negative 4% to 13%. Minimal detectable change estimates provide a statistical way to distinguish measured physiological change from the error expected when an assessment is repeated.

They are not equivalent to minimally clinically important differences. A change can exceed measurement error without necessarily mattering to a patient, and this study did not establish stroke-specific clinical thresholds. The authors noted that epidemiological associations in non-stroke cohorts have linked each 1-meter-per-second increase in central pulse-wave velocity with an approximately 15% increase in cardiovascular-event risk, while a 1-percentage-point increase in brachial flow-mediated dilation has been associated with about 13% lower cardiovascular-event risk.

Those associations come from non-stroke populations and do not turn the study’s error estimates into clinical cutoffs for people after stroke. The principal limitations were the sample size and the narrowly defined cohort. Participants were mostly men, generally had mild strokes and were more than a year beyond onset, limiting generalization to acute stroke, more severe neurological impairment and more gender-balanced populations.

Site-specific analyses included only 10 to 14 participants, producing wide confidence intervals and imprecise reliability estimates, particularly for flow-mediated dilation. Measurement error was unavoidable, and operator skill may have contributed to variability between assessment protocols. Inter-rater reliability was not examined, so the results do not establish whether the same performance would hold when more than one assessor collects the measurements.

Overall, the preliminary findings identify carotid-femoral pulse-wave velocity as the most reproducible stiffness measurement examined in this group of adults with chronic stroke and provide error bounds for interpreting repeated central stiffness and flow-mediated dilation measurements, while the poorer performance of peripheral pulse-wave velocity and absolute flow-mediated dilation argues for caution in their use as precise outcome measures.

Subject of Research: Test–retest reliability and minimal detectable change of vascular measurements in paretic and non-paretic limbs of adults with chronic stroke

Article Title: Test–retest reliability and minimal detectable change of pulse wave velocity and flow‐mediated dilation in paretic and non‐paretic limbs of older adults post‐stroke

Article References: Abreu, J. A., D'Isabella, N., Stouth, D. W., MacDonald, M. J., Tang, A., & Moncion, K. (2026). Test–retest reliability and minimal detectable change of pulse wave velocity and flow‐mediated dilation in paretic and non‐paretic limbs of older adults post‐stroke. Physiological Reports, 14(20), Article e71138. https://doi.org/10.14814/phy2.71138

Image Credits: AI Generated

DOI: 10.14814/phy2.71138

Keywords: stroke, pulse-wave velocity, flow-mediated dilation, arterial stiffness, endothelial function, test–retest reliability, minimal detectable change, chronic stroke, older adults, vascular measurement, Test, retest

The trial was conducted at Peking Union Medical College Hospital in Beijing between 2020 and 2021. After a two-week run-in, participants were randomly assigned in a 1:1 ratio to berberine plus standard coronary disease therapy or standard therapy alone. The berberine dose was increased in three stages: 100 mg taken orally three times daily for approximately four weeks, then 200 mg three times daily for approximately four weeks, and finally 300 mg three times daily for approximately four weeks. Investigators monitored adherence with pill counts at three follow-up visits, and no participant fell below the prespecified 80% adherence threshold. One participant in the berberine group voluntarily withdrew before the final visit, leaving 11 participants with final clinical measurements in that group and 11 in the standard-therapy group.

Investigators assessed endothelial function using brachial flow-mediated dilation, with image analysts blinded to treatment assignment. Flow-mediated dilation increased numerically in the berberine group, from 6.7% to 9.7%, and the reported comparison did not meet the threshold for statistical significance at p = 0.07. The authors described the vascular result as a directional improvement rather than a demonstrated effect. The strongest lipid signal involved LDL cholesterol, which declined from 1.74 to 1.55 mmol/L with berberine plus standard therapy and from 2.33 to 2.01 mmol/L with standard therapy alone. A significant group-by-time interaction indicated a greater relative reduction in the berberine group, with a between-group difference at follow-up of p = 0.028. Total cholesterol showed only a marginal group-by-time interaction, so the LDL result was not accompanied by equally clear changes across the full lipid profile.

Triglycerides fell in the berberine group, while apolipoprotein B showed a similar direction of change that did not reach statistical significance. Several inflammatory mediators also decreased between baseline and week 12 in participants receiving berberine: interleukin-1α, interleukin-17, monocyte chemoattractant protein-1, macrophage inflammatory protein-1β and vascular endothelial growth factor. These were within-group observations, so the study does not establish that every decline was caused by berberine. High-sensitivity C-reactive protein declined in both groups, and the paper did not establish a significant between-group difference in that measure. Self-reported constipation assessment scale scores improved in the berberine group, whereas Bristol stool form scores showed no significant difference.

Shotgun metagenomic sequencing showed that berberine was associated with a broad restructuring of the fecal microbiome. The researchers sequenced 68 stool samples and assembled a catalog of 3,094,494 non-redundant microbial genes. Community diversity increased in the berberine group, while microbial community structure differed between baseline and follow-up within that group and between the groups at week 12. Forty-three species changed in relative abundance after treatment, and 17 were classified as berberine-responsive taxa after correction for multiple comparisons. Several organisms declined, including Megasphaera micronuciformis, Megasphaera elsdenii, a Clostridiales bacterium and an Azospirillum species, while Ruminococcus, Roseburia and Anaerostipes hadrus increased. The abundance of M. micronuciformis was negatively correlated with total cholesterol, lipoprotein(a) and C-reactive protein, although these correlations do not demonstrate that the bacterium caused the lipid differences.

The microbial response also involved organisms associated with fermentation and short-chain fatty acid production. Roseburia and Ruminococcus are capable of converting dietary polysaccharides or oligosaccharides into short-chain fatty acids, while Flavonifractor plautii and Eubacterium ventriosum, also associated with short-chain fatty acid production, increased in the combined berberine and standard-therapy group but declined in the standard-therapy group. Targeted fecal metabolomics detected a significant rise in butyric acid, from a median of 11.5 at baseline to 21.3 at week 12, with p = 0.04, and a smaller increase in isobutyric acid, from a median of 1.1 to 1.4, with p = 0.037. Acetic acid showed an upward trend during the middle of treatment before declining to a level only marginally above baseline. Gene profiles were consistent with this shift: pathways for acetate formation became progressively enriched, and the abundance of the but gene, which encodes an enzyme involved in terminal butyrate production, increased significantly after berberine treatment.

Berberine was particularly associated with changes in microbial aromatic amino acid catabolism rather than a simple increase in the amino acid precursors phenylalanine and tyrosine. Fecal L-dopa rose to 3.67 in the berberine group at follow-up, compared with 1.05 in the standard-therapy group, in a significant group-by-time interaction. L-arginine, 3-hydroxyphenylacetic acid and phenylpropionic acid followed a similar berberine-enriched pattern, with the reported follow-up L-arginine values being 22.6 and 9.8 in the berberine and standard-therapy groups, respectively. By contrast, tyrosine and L-tryptophan increased over time regardless of berberine exposure. The investigators interpreted those shared changes as a trajectory associated with standard therapy rather than a berberine-specific response.

A gene-level analysis offered a possible explanation for the metabolite shifts. The abundance of the microbial dopamine β-monooxygenase gene correlated with fecal L-dopa, the porA gene correlated with phenylacetic acid and the acdA gene correlated with phenylpropionic acid, with reported correlation coefficients of 0.6 to 0.7. Seventeen KEGG modules changed appreciably after berberine treatment, including pathways associated with tyrosine, phenylacetate, phenylalanine and tryptophan metabolism. The intervention increased several downstream products without a comparably clear rise in their upstream substrates. This pattern is consistent with the authors’ interpretation that berberine remodels microbial metabolic capacity, but the trial did not directly test whether those changes mediated the clinical outcomes.

Some fecal metabolites were statistically associated with circulating lipids, including L-dopa, hydroxyphenyl lactic acid, L-phenylalanine and imidazole propionic acid. These are associations within a small cohort, not evidence that any metabolite caused a lipid change. The authors noted that previous research had linked phenylpropionic acid to intestinal epithelial barrier function and aryl hydrocarbon receptor signaling, while L-dopa has a context-dependent relationship with cardiovascular biology. They also proposed that the observed fecal L-dopa enrichment might reflect a local gut–vascular axis, but acknowledged that dedicated tracer studies would be needed to determine whether the compound reaches the circulation or acts directly on host tissues. Berberine’s low oral bioavailability makes interactions with the gut microbiota plausible, yet direct effects on host tissues remain possible as well.

The trial is best understood as exploratory rather than definitive. Its two groups differed substantially in age and sex distribution, and potential residual confounding from smoking, alcohol consumption, diet and physical activity could not be fully excluded despite clinical annotation. Missing observations for some clinical parameters also prevented robust between-group comparisons of certain outcomes, while the limited cohort restricted analysis of downstream metabolites. The parallel design helped account for shared coronary disease secondary-prevention therapies, but the findings do not establish that berberine prevents heart attacks, improves survival or should replace established secondary prevention. The results instead identify measurable changes in LDL cholesterol, vascular function, inflammation and the gut ecosystem in a specific group of stable coronary artery disease patients after percutaneous coronary intervention, while leaving their clinical meaning for further investigation.

Subject of Research: Pilot randomized trial of berberine, vascular function, lipids, gut microbiota and fecal metabolites in stable coronary artery disease after percutaneous coronary intervention.

Article Title: Berberine improves lipid levels, vascular function, and gut microbial-dependent metabolites in stable coronary artery disease patients

Article References: Liu, H., Feng, S., Tang, M., Sun, J., Tian, R., & Zhang, S. (2026). Berberine improves lipid levels, vascular function, and gut microbial-dependent metabolites in stable coronary artery disease patients. Frontiers in Nutrition, 13, Article 1945710. https://doi.org/10.3389/fnut.2026.1945710

Image Credits: AI Generated

DOI: 10.3389/fnut.2026.1945710

Keywords: Berberine, Coronary artery disease, Gut microbiome, Short-chain fatty acids, LDL cholesterol, Endothelial function, Metabolomics, Metagenomics, Inflammation, Clinical trial, improves, lipid

The trial, published in Pharmacology Research & Perspectives, addressed a stubborn clinical problem. Hypertension remains the most prevalent modifiable risk factor for cardiovascular disease, and bringing blood pressure under control with medication dramatically reduces that risk. Yet studies consistently show that 20 to 40 percent of cardiovascular risk persists in well-controlled hypertensive patients, a phenomenon researchers call residual risk. Scientists attribute this stubborn remainder to chronic inflammation, oxidative stress, endothelial dysfunction, arterial stiffness and genetic and epigenetic factors, including microRNA-21, a small regulatory RNA implicated in hypertensive vascular remodeling. Standard antihypertensive drugs do not fully neutralize these pathways, which is why nutraceuticals with antioxidant and anti-inflammatory properties have attracted attention as potential adjuncts.

Chios mastic was a plausible candidate. The resin contains characteristic triterpenes, notably masticadienonic acid and isomasticadienonic acid, and preclinical work has documented antioxidant, anti-inflammatory and cardioprotective effects. An earlier human study by Kontogiannis and colleagues reported an acute antihypertensive effect and hinted at mechanisms involving proteostasis, the cellular system that degrades oxidized and misfolded proteins, and the control of reactive oxygen species. The HYPER-MASTIC team hypothesized that sustained mastic supplementation might chip away at residual cardiovascular risk in treated hypertensive patients, and designed a double-blind, placebo-controlled, parallel-group trial to find out.

Between April 2022 and February 2024, the researchers enrolled 105 participants aged 40 to 80 with stable, well-controlled hypertension confirmed by 24-hour ambulatory monitoring. Volunteers were randomized to receive 1500 milligrams per day of mastic, 2800 milligrams per day, or matching placebo for three months. Blinding was unusually thorough: placebo tablets were identical in size and shape and were sprayed with mastic scent to preserve the illusion. Participants attended four study visits, during which the team measured 24-hour ambulatory peripheral and central blood pressure, pulse wave velocity as a gold-standard index of arterial stiffness, endothelial function via flow-mediated dilatation, carotid and femoral artery ultrasound, and echocardiographic cardiac function. Blood sampling tracked reactive oxygen species and proteasome activity in immune cells and red blood cells, and RNA sequencing captured transcriptomic changes in a predefined high-risk subgroup of 59 participants.

The primary result was unambiguous. Changes in 24-hour systolic and diastolic blood pressure, the trial’s primary endpoints, did not differ significantly between the mastic and placebo groups. The low-dose group showed some statistically significant within-group increases in pulse wave velocity and central blood pressure parameters, but these did not translate into significant time-by-group interactions, with the single exception of 24-hour central systolic pressure, where a trend toward an increase in the low-dose group emerged. Office diastolic pressure rose slightly in the high-dose group, and flow-mediated dilatation barely changed anywhere. In short, mastic conferred no additional short-term antihypertensive benefit in these patients.

Crucially, the researchers could rule out poor adherence as an explanation. Participants kept daily diaries, received biweekly follow-up calls, and, most persuasively, plasma levels of the mastic triterpenes masticadienonic and isomasticadienonic acid were measured objectively. These metabolites rose in the low-dose group and climbed roughly three-fold further in the high-dose group while remaining flat under placebo, confirming that participants were genuinely taking their supplements. The supplement was also well tolerated, with no serious adverse events reported across the three arms.

The molecular assays told a similar story of neutrality. Reactive oxygen species and proteasome activity in peripheral blood mononuclear cells and red blood cells showed no significant differences between groups at baseline or at three months, contrasting with the effects seen in earlier acute and experimental studies. The authors suggest this likely reflects a ceiling effect: participants whose blood pressure and metabolic risk factors were already well controlled simply carried a low inflammatory and oxidative burden, leaving little room for mastic to improve. This pattern echoes findings from other nutraceutical trials, including studies of quercetin and resveratrol, where blood pressure effects shrink or vanish in lower-risk populations, and from the earlier MAST4HEALTH trial, in which mastic improved metabolic and inflammatory markers most clearly in people with greater baseline cardiometabolic burden.

Where the trial did find something intriguing was at the level of gene expression. In the high-risk subgroup, defined by criteria such as elevated C-reactive protein, advanced age, chronic renal failure or residual blood pressure elevation, RNA sequencing of whole blood revealed a distinct set of differentially expressed genes after mastic supplementation compared with placebo. Only about one percent of altered genes overlapped between the mastic and placebo arms, with 141 genes uniquely changed by mastic. Functional enrichment analysis showed that the upregulated genes clustered in pathways governing tight junction organization and cellular adhesion, processes central to endothelial barrier integrity and vascular permeability that are disrupted in hypertension. The authors interpret this as evidence that mastic may support endothelial stability and vascular homeostasis even when it does not move the blood pressure needle, a mastic-specific biological effect supported by the absence of comparable transcriptomic changes under placebo. Complementary analyses from the same project also found modulation of microRNA-21, an epigenetic marker of vascular remodeling, particularly in relation to night-time blood pressure.

The investigators are careful about the caveats. The low-dose group was significantly younger than the placebo group and reported family history of hypertension more often, imbalances that were adjusted for statistically but that may have contributed to vascular variability. A three-month intervention may be too brief for gradual nutraceutical effects to emerge, and the well-controlled baseline state of the cohort itself limited the opportunity to detect additive benefits. The authors also emphasize that mastic was studied as a nutraceutical supplement and is not approved by regulators for treating hypertension or reducing cardiovascular risk, so patients should not view the resin as a substitute for prescribed therapy.

The takeaway from HYPER-MASTIC is a nuanced one that resists the simple narrative of a miracle supplement. Chios mastic, at 1500 or 2800 milligrams daily for three months, does not lower blood pressure in people whose hypertension is already well managed, and the trial’s rigorous design, objective adherence verification and comprehensive vascular phenotyping make that null result difficult to dismiss. Yet the resin’s ability to shift expression of genes involved in endothelial integrity in higher-risk patients suggests that its biological activity is real and may be most relevant where inflammatory and metabolic burden is greatest. The authors call for longer trials in higher-risk populations with integrated molecular and clinical endpoints to determine whether mastic’s transcriptomic fingerprints translate into fewer heart attacks and strokes. For now, the ancient resin of Chios remains what it has long been: a fascinating natural product with genuine biological activity, still awaiting proof that it can protect the cardiovascular system in the patients who need it most.

Subject of Research: Effects of Chios mastic gum supplementation on blood pressure and vascular biology in well-controlled hypertension

Article Title: Chios Mastic in Well‐Controlled Hypertension: Findings From the HYPER‐MASTIC Randomized Controlled Trial

Article References: Kalafati, I. P., Kyriazopoulou‐Korovesi, A.-A., Mentsiou‐Nikolaou, E., Papaioannou, M., Konstantaki, C., Angelidakis, L., Gianniou, D. D., Mikropoulou, E. V., Giardoglou, P., Valakos, D., Vatsellas, G., HYPER‐MASTIC Consortium, Andreadou, I., Manios, E., Halabalaki, M., Trougakos, I. P., Dedoussis, G. V., & Stamatelopoulos, K. (2026). Chios Mastic in Well‐Controlled Hypertension: Findings From the HYPER ‐ MASTIC Randomized Controlled Trial. Pharmacology Research & Perspectives, 14(6), Article e70322. https://doi.org/10.1002/prp2.70322

Image Credits: AI Generated

DOI: 10.1002/prp2.70322

Keywords: Chios mastic, hypertension, randomized controlled trial, cardiovascular risk, blood pressure, endothelial function, oxidative stress, nutraceutical, Pistacia lentiscus, RNA sequencing, arterial stiffness, residual cardiovascular risk

The left internal mammary artery is the gold-standard conduit in CABG surgery, prized for its exceptional long-term patency and natural resistance to atherosclerosis. Yet despite its clinical importance, the bioenergetic profile of this vessel has remained largely uncharted. The reason is technical: assessing mitochondrial function in intact human vascular tissue is notoriously difficult. Most of what science knows about vascular mitochondria comes from simplified models that cannot fully reproduce the structural and cellular complexity of a living human arterial wall — the layered interplay of endothelium, smooth muscle and connective matrix that determines how a graft actually behaves inside a patient.

Mitochondria in blood vessels are far more than tiny power plants. In endothelial cells, they act primarily as signalling organelles rather than major energy producers, modulating vascular tone, inflammation and adaptation to metabolic stress. When mitochondrial function falters, the consequences cascade: excessive reactive oxygen species (ROS) production, endothelial activation and reduced nitric oxide bioavailability, all of which promote vascular stiffness, inflammation and atherosclerosis. These processes are especially relevant for patients undergoing bypass surgery, where the functional integrity of the vascular graft is essential for long-term outcomes. Impaired mitochondrial respiration has even been linked directly to atherosclerotic plaque progression, promoting necrotic core formation and thinning of the protective fibrous cap.

The Gdańsk team, led by Barbara Kutryb-Zając of the Department of Biochemistry, designed a workflow that turns routine surgery into a laboratory opportunity. A 67-year-old male patient with stable two-vessel coronary disease, arterial hypertension and orally treated diabetes mellitus underwent elective CABG. During the standard sternotomy procedure, the LIMA was harvested for grafting to the left anterior descending artery, and a residual segment of the vessel — tissue that would normally be discarded — was collected for ex vivo analysis with written informed consent and approval from the local bioethics committee.

The handling protocol was engineered to preserve the vessel’s living architecture. Immediately after harvesting, the artery was placed in Agilent Seahorse XF DMEM Medium at pH 7.4 and transported to the laboratory, where it was cleaned of surrounding tissue and sectioned into small fragments. The vascular rings were cut longitudinally and gently flattened into planar segments, then immobilized on Seahorse XF capture microplates fitted with islet capture screens — with the luminal surface facing upwards, so that the delicate endothelial layer was directly exposed to the measurement chamber. Histological staining with hematoxylin and eosin on parallel sections confirmed that the vascular structure and endothelial lining remained preserved throughout preparation.

The functional core of the study is the mitochondrial stress test, a sequential pharmacological interrogation of the respiratory chain. Vessel segments of two to three millimetres were loaded into the wells of a Seahorse XF Flex 3D Capture Microplate, and the sensor cartridge — hydrated overnight with calibrant solution at 37 degrees Celsius — recorded the oxygen consumption rate (OCR) in real time. Oligomycin A at 20 micromolar was injected first to inhibit ATP synthase and reveal ATP-linked respiration; FCCP at 15 micromolar followed, uncoupling the proton gradient to expose maximal respiratory capacity; finally, a mixture of rotenone and antimycin A, each at 10 micromolar, shut down complexes I and III to isolate non-mitochondrial oxygen consumption. From these measurements the team derived basal respiration, ATP-linked respiration, maximal respiration, proton leak and non-mitochondrial respiration, normalizing all values to total protein content determined by the Bradford assay and expressing them as picomoles of oxygen per minute per milligram of protein.

In parallel, the researchers quantified the tissue’s chemical energy currency using high-performance liquid chromatography (HPLC). Snap-frozen LIMA sections were homogenized in ice-cold perchloric acid to extract nucleotides, which were then separated and quantified against external standards. The panel covered adenosine triphosphate (ATP), diphosphate (ADP) and monophosphate (AMP), the guanosine analogues GTP and GDP, and the redox cofactors NAD+ and NADH. Because adenosine 5′-diphosphoribose (ADPR) is the major product formed by acidic cleavage of NADH during extraction, the measured ADPR level served as a readout of NADH concentration — a clever analytical shortcut that links the nucleotide profile directly to the tissue’s redox balance.

The results demonstrated that both approaches work in human arterial tissue. Real-time OCR measurements showed that mitochondrial respiration can be reliably assessed in intact human arteries on the Seahorse XF Flex 3D platform, with reproducible capture of basal respiration, ATP-linked respiration and maximal respiratory capacity. HPLC analysis confirmed measurable nucleotide pools in the same tissue, and the profile indicated preserved energy status — evidence that the vascular segments remained functionally intact under ex vivo conditions. By combining the dynamic, functional picture from oxygen flux with the static, metabolic snapshot from nucleotide levels, the workflow delivers an integrated assessment of vascular bioenergetics at both functional and metabolic levels, something neither method achieves alone.

The methodological significance extends beyond the operating room. According to the authors, this is the first application of the Seahorse XF Flex 3D platform to intact human vascular tissue, closing a gap between cell culture and animal models on one side and clinical reality on the other. Because the LIMA is harvested in every CABG operation, the approach creates a renewable pipeline of clinically relevant human vascular tissue for metabolic research — a platform for investigating how diabetes, oxidative stress, ageing and other comorbidities reshape the energy metabolism of the vessel wall itself.

The clinical horizon is equally compelling. Current intraoperative assessment of graft quality relies largely on anatomical and flow-based measurements, which reveal nothing about the metabolic condition of the vessel. Ex vivo bioenergetic profiling could offer a complementary functional readout reflecting mitochondrial integrity and cellular viability within the vascular wall, potentially helping to identify subtle metabolic alterations linked to patient comorbidities such as diabetes. In the longer term, the researchers envision this methodology contributing to biomarkers of graft quality and personalized strategies in coronary artery bypass grafting. The team is careful about scope: this proof-of-concept rests on a single human LIMA, and variability in tissue handling, preparation and positioning within the Seahorse platform will require standardization. Larger patient cohorts will be needed to validate robustness, reproducibility and clinical relevance. But the conceptual barrier has fallen — the respiratory heartbeat of a human artery can now be watched in real time, opening a new window onto vascular metabolism in cardiovascular and metabolic disease.

Subject of Research: Real-time ex vivo measurement of mitochondrial respiration and nucleotide levels in intact human left internal mammary artery grafts from coronary artery bypass surgery

Article Title: Mitochondrial respiration and nucleotide profiling in human left internal mammary artery from CABG: a novel real-time ex vivo approach

Article References: Braczko, A., Łoś, A., Piotrowska, M., Kawecka, A., Walczak, I., Krysiak, M., Hellmann, M., Brzeziński, M., Smoleński, R. T., & Kutryb-Zając, B. (2026). Mitochondrial respiration and nucleotide profiling in human left internal mammary artery from CABG: a novel real-time ex vivo approach. Acta Biochimica Polonica, 73, Article 16877. https://doi.org/10.3389/abp.2026.16877

Image Credits: AI Generated

DOI: 10.3389/abp.2026.16877

Keywords: mitochondrial respiration, left internal mammary artery, coronary artery bypass grafting, Seahorse XF Flex 3D, oxygen consumption rate, HPLC nucleotide profiling, vascular bioenergetics, endothelial function, ex vivo analysis, ATP-linked respiration, graft quality, cardiovascular metabolism

The research, published in Frontiers in Transplantation, tackled a well-known weak point in the standard Toronto protocol for ex vivo lung perfusion, or EVLP. In clinical practice, EVLP is typically limited to four to six hours, during which a donor lung is warmed to body temperature, ventilated, and perfused with a nutrient-rich solution so transplant teams can judge whether a marginal organ is usable. During prolonged perfusion, however, the perfusate degrades: pH falls as lactate accumulates, glucose is consumed by metabolically active tissue, and electrolyte concentrations wander out of physiological range. Glucose depletion has previously been linked to edema and impaired cellular function, making the biochemical environment itself a candidate target for extending safe perfusion times.

The team, led by Justin Issard and colleagues at Marie Lannelongue Hospital and Université Paris-Saclay, harvested twelve heart-lung blocks from donor pigs and cold-preserved them before subjecting each to twelve hours of normothermic EVLP following the Toronto protocol. All lungs were perfused with Steen solution, the albumin- and dextran-containing perfusate used in most clinical EVLP programs, with mean priming volumes of roughly 1.3 to 1.5 liters. Every two hours, the researchers exchanged 100 milliliters of perfusate — about five to nine percent of the total volume. In the standard group, that exchange was fresh Steen solution. In the corrected group, it was a custom mixture of one-third Steen solution, one-third 2.5 percent glucose solution, and one-third 1.4 percent sodium bicarbonate, formulated to hold sodium, potassium, calcium, chloride, pH, and glucose within physiological limits.

The corrective strategy worked as designed. Throughout the twelve-hour perfusion, the corrected group maintained pH between 7.3 and 7.5, potassium between 3.8 and 4.2 millimoles per liter, chloride below 120 millimoles per liter, and glucose above 10 millimoles per liter. Statistical analysis of the time-course data, using two-way repeated-measures ANOVA, showed significant group effects and group-by-time interactions for pH measured in both the pulmonary artery and the left atrium, as well as for lactate, sodium, potassium, and chloride concentrations. Pulmonary vascular resistance, a key safety indicator, did not differ between groups or change over time, suggesting the correction strategy did not stress the pulmonary circulation.

Functionally, the corrected lungs performed better while on the circuit. Dynamic compliance — the ease with which the lungs inflate with each breath — was significantly higher in the corrected group throughout EVLP. Oxygenation, measured as the PaO2/FiO2 ratio, also increased over time in both groups but remained significantly higher overall in the corrected group. These are exactly the parameters transplant clinicians watch when deciding whether a marginal graft is safe to implant, so the finding suggests that biochemical homeostasis translates into measurable organ quality during prolonged perfusion.

Structural analysis told a more nuanced story. Histological scoring of the right lungs after EVLP showed that alveolar edema was substantially lower in the corrected group, a finding consistent with better fluid balance and preserved barrier function. Yet the same lungs showed more hyaline membranes — protein-rich deposits within alveoli that typically signal injury or repair — and electron microscopy revealed endothelial hypertrophy, subendothelial edema, and disrupted intercellular junctions in the corrected group that were absent in the standard group. The authors propose that hyaline membranes may reflect a reparative or inflammatory response to alveolar injury rather than ongoing edema, possibly driven by the increased glucose availability creating a pro-inflammatory alveolar microenvironment, or by altered perfusate protein composition favoring fibrin deposition.

One of the most intriguing structural findings involved the pores of Kohn, the microscopic channels that allow air to move laterally between adjacent alveoli. Scanning electron microscopy showed a significantly higher alveolar pore density in the corrected group — 711 plus or minus 307 pores per cubic millimeter compared with 529 plus or minus 210 in the standard group. Greater pore density may enhance collateral ventilation and contribute to the improved compliance and oxygenation observed, though the researchers caution that increased pore density has also been described in emphysematous remodeling, so the change could reflect a mixture of alveolar recruitment and tissue stress after twelve hours of normothermic perfusion.

Molecular and vascular analyses added further complexity. Western blotting showed decreased expression of endothelial nitric oxide synthase and its activated phosphorylated form in both perfused groups compared with control lungs, with further reductions in Twist and vascular endothelial cadherin, particularly in the standard group. Mitochondrial proteins MTERF and COX15 were upregulated in perfused lungs, significantly so in the corrected group, hinting at metabolic adaptation or stress. Vascular myography revealed that acetylcholine-induced, endothelium-dependent relaxation was impaired in all perfused lungs compared with controls, and more so in the corrected group, while smooth muscle-dependent relaxation with sildenafil was similar across groups. Cytokine levels in the perfusate, including IL-6, IL-18, TNF-alpha, and IL-1beta, were largely unaffected by the correction strategy.

The critical test — transplantation — produced a sobering result. Ten left lungs, five from each group, were deemed suitable and transplanted into donor-related pigs for four hours of observation. Post-transplant oxygenation, measured as the delta PO2 between pulmonary artery and left atrial blood and as the PaO2/FiO2 ratio, showed no significant difference between the corrected and standard groups. The authors attribute this partly to the presence of the recipients’ native right lung, which dilutes any graft-specific signal in the ventilatory and gas-exchange measurements, and partly to the short follow-up period. Selective ventilation or bilateral transplantation would be needed to isolate the transplanted lung’s contribution.

The study’s implications reach beyond the twelve-hour mark. Extending EVLP duration could unlock reconditioning interventions that are impractical within a few hours — antibiotic therapy for infected donor lungs, adenoviral gene transfer, immunomodulation, or mesenchymal stem cell administration — potentially expanding the pool of usable grafts at a time when demand far outstrips supply. The authors suggest that combining corrected perfusate composition with intermittent EVLP strategies, which alternate normothermic perfusion with cold storage phases to limit cumulative endothelial stress, could eventually enable lung preservation for several days. They also flag the key unresolved problems: the bicarbonate buffer caused hypernatremia that was difficult to control, endothelial protection remains an unmet need, and glucose delivery must be tuned to avoid hyperglycemic endothelial stress. Future work, they write, should move beyond simple biochemical correction toward targeted strategies that maintain endothelial integrity and capillary barrier function, evaluate 24-hour protocols, and explore adjuncts such as hemofiltration, adsorbent membrane filtration, and oncotic pressure management.

Subject of Research: Perfusate biochemical correction during prolonged ex vivo lung perfusion of donor lungs in a porcine transplantation model

Article Title: Prolonged ex vivo lung perfusion with corrected perfusate: functional and structural benefits in swine

Article References: Issard, J., Mercier, J., Ménager, J.-B., Fadel, G., Nobori, Y., Izem, M., Ghigna, M.-R., Fadel, E., Antigny, F., Mordant, P., & Mercier, O. (2026). Prolonged ex vivo lung perfusion with corrected perfusate: functional and structural benefits in swine. Frontiers in Transplantation, 5, Article 1899960. https://doi.org/10.3389/frtra.2026.1899960

Image Credits: AI Generated

DOI: 10.3389/frtra.2026.1899960

Keywords: ex vivo lung perfusion, lung transplantation, EVLP, perfusate correction, donor lungs, porcine model, Steen solution, lung edema, endothelial function, pores of Kohn, Toronto protocol, graft preservation

The endothelium, the delicate single layer of cells lining the interior of every blood vessel, is far more than passive plumbing. It actively regulates vascular tone by releasing vasodilating and vasoconstricting compounds, controls oxidative processes, modulates cell adhesion, and influences arterial stiffness. When the endothelium falters, vessels stiffen, their dilatory responses weaken, and the earliest silent stages of cardiovascular disease take hold. Flow-mediated dilation of the brachial artery, measured with high-resolution ultrasound after a temporary ischemic stimulus, captures this dysfunction early and tracks closely with coronary artery function, which is why the research team led by Simon Iskra and Armin Paravlić of the University of Ljubljana centered their analysis on it.

To assemble the evidence, the researchers searched six major databases from inception through multiple updated searches in 2023, 2025 and 2026, screening nearly 1,900 records against strict PICOS criteria. Only randomized controlled trials in adults that reported brachial artery flow-mediated dilation alongside at least one secondary outcome made the cut. The final pool spanned healthy volunteers and patients with cardiovascular disease, metabolic syndrome, diabetes, kidney disease, cancer, and even mental and neurological disorders. Participants ranged from about 20 to 78 years old, 43 percent were women, and interventions lasted from four to 26 weeks, with roughly two-thirds of study arms using continuous training and one-third using interval formats.

The headline result survived every robustness check the team threw at it. A random-effects model yielded a mean difference of 2.35 percent in flow-mediated dilation, a fixed-effects model produced 1.90 percent, and a trim-and-fill adjustment for publication bias still left a significant adjusted estimate of 1.74 percent. Sensitivity analysis removing the single largest study did not change the conclusion. Heterogeneity was high, as expected when pooling trials across such diverse populations and protocols, but the direction and clinical relevance of the effect were consistent. By the classification scheme the authors applied, the pooled gain qualifies as small but clinically meaningful, sitting above the 1 percent threshold considered the minimal clinically important difference.

The most novel contribution, however, lies in the meta-regression, which asked which physiological changes actually drive the vascular improvements. Four clusters emerged as significant moderators. Greater reductions in body weight and body fat were associated with larger gains in endothelial function, with regression coefficients of -4.021 and -1.721 respectively. Drops in systolic and diastolic blood pressure also tracked with better flow-mediated dilation, at coefficients of -0.525 and -0.484. On the positive side, improvements in maximal oxygen uptake, the classic index of cardiorespiratory fitness, showed a strong association with endothelial gains at a coefficient of 0.656, and changes in insulin levels moderated the effect as well. Notably, blood lipids, fasting glucose, HbA1c, and insulin resistance measured by HOMA-IR did not significantly moderate the vascular response, suggesting lipid and glucose improvements run on partly independent tracks.

Beneath these statistical associations lies a coherent mechanistic story. During aerobic exercise, blood flow to working muscles surges, subjecting the vessel walls to elevated shear stress. This mechanical signal activates endothelial nitric oxide synthase, boosting production of nitric oxide, the principal vasodilator of healthy arteries. The meta-analysis confirmed this biochemistry in blood: nitric oxide and its metabolites rose substantially, with standardized mean differences of 1.23 for both, while endothelin-1, the vessels’ chief constricting agent, fell moderately. Enhanced nitric oxide bioavailability combined with reduced endothelin-1 shifts vascular tone toward dilation, plausibly explaining much of the measured improvement in flow-mediated dilation, even though the biomarkers themselves did not reach statistical significance as moderators, likely because relatively few studies measured them.

The hemodynamic findings add another layer. Aerobic training produced small but significant reductions in systolic pressure, diastolic pressure, and mean arterial pressure, and the meta-regression tied these blood pressure drops directly to endothelial gains. The authors interpret this as evidence of a feedback loop: healthier endothelia dilate more readily, lowering vascular resistance and pressure, which in turn protects the vessel wall. Arterial stiffness told a subtler tale. Peripheral stiffness, measured at the brachial-ankle segment, decreased significantly, but central stiffness, measured at the carotid-femoral segment, and the augmentation index did not change. The researchers attribute this to the time course of vascular remodeling, since peripheral arteries adapt faster than the stiffer central vessels, and to the small number of trials that measured central outcomes alongside flow-mediated dilation.

Cardiorespiratory fitness emerged as perhaps the most intriguing partner in the adaptation. Maximal oxygen uptake rose moderately across trials, and the stronger the fitness gains, the stronger the endothelial improvements. The relationship is likely bidirectional. Repeated shear stress from training enhances nitric oxide signaling and vascular homeostasis, while preserved endothelial function optimizes skeletal muscle perfusion and oxygen delivery, supporting further fitness gains. The authors caution that because the meta-regression works at the study level, causality cannot be established; the pattern reflects interconnected adaptations rather than a simple cause-and-effect chain. Still, the convergence of fitness, body composition, blood pressure, and insulin changes as moderators paints exercise as a multi-front intervention rather than a single-target drug.

Body composition results carried their own surprise. Even though the analysis excluded trials that combined exercise with dieting, aerobic training alone significantly reduced body weight, body mass index, and body fat percentage, with no change in skeletal muscle mass. The regression confirmed that fat loss amplified the vascular benefit, and the authors suggest that shrinking adipose tissue dampens chronic low-grade inflammation, a process tightly linked to endothelial health. Inflammation markers moved in the expected direction, with a small significant fall in C-reactive protein and a moderate, near-significant decrease in TNF-alpha. Lipid changes were real but modest, with small rises in HDL cholesterol and small falls in LDL and triglycerides, while glucose metabolism improved through fasting glucose, HbA1c, and insulin resistance, even without significant changes in insulin itself.

The authors are candid about limitations. The restriction to trials reporting brachial artery flow-mediated dilation means conclusions may not generalize to other endothelial assessments. Flow-mediated dilation tends to normalize over longer interventions as structural remodeling proceeds, so pooled changes may understate peak functional adaptation. Pooling healthy and clinical populations yields general tendencies rather than disease-specific prescriptions, and the use of standardized mean differences for secondary outcomes, while necessary given heterogeneous measurement methods, obscures absolute changes. Publication bias was detected for the primary outcome and several secondary markers, though corrections preserved the core finding. Even so, the message is hard to dismiss: aerobic exercise acts simultaneously on fat mass, fitness, blood pressure, insulin regulation, nitric oxide signaling, and inflammation, and these converging pathways collectively rebuild endothelial function. For clinicians and the public alike, the analysis reinforces aerobic training as one of the most powerful non-pharmacological tools available for protecting the vascular system, with benefits that compound across nearly every measurable dimension of cardiovascular health.

Subject of Research: Effects of aerobic exercise on endothelial function and cardiovascular disease markers

Article Title: Impact of Aerobic Exercise on Endothelial Function and Other Cardiovascular Disease Markers in Health and Disease: A Systematic Review and Meta-analysis with Meta-regression of Randomized Controlled Trials

Article References: Iskra, S., Turnšek, G., Drole, K., & Paravlić, A. (2026). Impact of Aerobic Exercise on Endothelial Function and Other Cardiovascular Disease Markers in Health and Disease: A Systematic Review and Meta-analysis with Meta-regression of Randomized Controlled Trials. Sports Medicine – Open, 12(1), Article 150. https://doi.org/10.1186/s40798-026-01110-0

Image Credits: AI Generated

DOI: 10.1186/s40798-026-01110-0

Keywords: aerobic exercise, endothelial function, flow-mediated dilation, cardiovascular disease, meta-analysis, nitric oxide, blood pressure, cardiorespiratory fitness, body composition, insulin, arterial stiffness, vascular health

To understand how a diabetes drug touches the vascular system, it helps to start with the hormone it mimics. GLP-1 is an incretin hormone released by enteroendocrine L-cells in the distal ileum and colon after a meal. When glucose or other nutrients arrive in the gut, these cells close ATP-dependent potassium channels, depolarize the membrane, open L-type calcium channels and secrete GLP-1 into the bloodstream. The hormone then amplifies insulin secretion from pancreatic beta cells by two- to three-fold compared with intravenous glucose, a phenomenon known as the incretin effect. It also delays gastric emptying and suppresses glucagon release. In type 2 diabetes, this incretin effect is blunted, partly through impaired GLP-1 function and reduced receptor expression, which is precisely why pharmacological boosting of the pathway has proven so effective.

Native GLP-1, however, is a fleeting molecule. The enzyme dipeptidyl peptidase-4 cleaves it within minutes, leaving a circulating half-life of roughly ninety seconds, so a substantial fraction of the hormone is inactivated before it ever reaches its targets. Therapeutic agonists were engineered to escape this fate. Exenatide, derived from a peptide found in the saliva of the Gila monster, survives for about 2.4 hours and was approved in 2005 for twice-daily injection. Liraglutide carries a fatty-acid side chain that binds reversibly to serum albumin, extending its half-life to 13 to 15 hours after subcutaneous injection. Semaglutide, dulaglutide and albiglutide push persistence further still, with half-lives long enough to permit once-weekly dosing. Tirzepatide adds a second layer of sophistication by engaging the receptor for the other incretin hormone, GIP, as well as GLP-1.

All of these molecules converge on a single target: the GLP-1 receptor, a class B G protein-coupled receptor of 463 amino acids found in the pancreas, gastrointestinal tract, lungs, kidneys, central nervous system and, in mice, monkeys and humans, the heart. When activated, the receptor can couple to the Gs protein to raise cyclic AMP, to Gq/11 to elevate intracellular calcium, and to beta-arrestin to trigger ERK1/2 signaling. Crucially, different ligands bias the receptor toward different downstream cascades, a property known as biased agonism. The review highlights this as one plausible explanation for why structurally distinct agonists do not lower blood pressure to the same degree: they are not simply switching the receptor on, they are steering it toward different intracellular programs.

The vascular story begins in the endothelium. In human umbilical vein endothelial cells exposed to GLP-1, receptor activation recruits the phosphatidylinositol 3-kinase/Akt pathway, which phosphorylates and activates endothelial nitric oxide synthase, raising the bioavailability of nitric oxide, the principal relaxing factor of the vessel wall. A parallel protein kinase A-dependent route to nitric oxide production operates alongside it. Together these converging pathways relax vascular smooth muscle and reduce peripheral resistance. Downstream, activation of AMP-activated protein kinase and suppression of nuclear factor-kappa B signaling cut vascular oxidative stress, adhesion molecule expression and inflammatory cytokine release, linking the acute vasoactive effects of the receptor to the slower, anti-atherosclerotic remodeling of the vessel wall.

The heart and kidneys contribute their own mechanisms. In atrial cardiomyocytes, GLP-1 receptor activation couples to Epac2, triggering the secretion of atrial natriuretic peptide, which raises cyclic GMP and promotes both vasodilation and renal sodium excretion. Direct natriuresis has been documented in healthy, obese and type 2 diabetic individuals, offering a plausible route by which plasma volume, and with it blood pressure, is reduced. Evidence from mouse studies further suggests that exendin-4 can dampen angiotensin II signaling in the kidney, inhibiting the transforming growth factor beta1 and Smad3 pathway that drives fibrosis. Yet here the literature fractures: a clinical study of dulaglutide found no significant changes in plasma renin activity, serum aldosterone or related neurohormonal markers, leaving the role of the renin-angiotensin-aldosterone system unresolved and flagged by the review as a priority for further investigation.

The clinical data, drawn from cardiovascular outcome trials and pooled analyses, paint a picture of modest but persistent effect. Exenatide at 10 micrograms twice daily reduced systolic pressure by a least-squares mean of 2.8 mmHg across 2,171 patients, with the largest difference, 8.2 mmHg versus placebo, seen in people whose baseline systolic pressure exceeded 150 mmHg. Once-weekly exenatide lowered systolic pressure by 1.6 mmHg in the EXSCEL trial of nearly 14,752 patients. Dulaglutide at 1.5 milligrams produced a 2 to 3 mmHg reduction evident within four weeks and sustained through 26 weeks, accompanied by a fall in 24-hour pulse pressure. Semaglutide at 1.0 milligram weekly lowered systolic pressure by 2.6 mmHg in SUSTAIN-6, and oral semaglutide matched that figure at week 83 in PIONEER-6. Liraglutide managed 1.2 mmHg over 36 months in LEADER, while lixisenatide achieved only 0.8 mmHg in ELIXA. Diastolic pressure, by contrast, was largely untouched.

Two patterns emerge from those numbers. First, the effect is drug-specific: agents differ by more than threefold in the magnitude of systolic reduction they deliver, consistent with the biased agonism observed at the receptor. Second, the benefit is conditional. People with normal blood pressure at baseline showed no between-group differences in the trials, suggesting that GLP-1 receptor agonists act as regulators of an elevated system rather than as blanket antihypertensives. The review also draws a careful temporal distinction that has muddied the literature. Acutely, GLP-1 receptor stimulation of sinoatrial node pacemaker cells and brainstem autonomic neurons raises heart rate and can transiently nudge mean arterial pressure upward, particularly after dose escalation. Chronically, sustained therapy produces a net systolic reduction as weight loss, improved glycemic control and the vascular, renal and anti-inflammatory mechanisms accumulate and outweigh the initial pressor response. The two effects operate on different timescales and are not contradictory, but conflating them has fueled apparent inconsistencies across studies.

What the mechanisms cannot yet claim is firm human validation. Aside from the natriuresis and endothelial function data, most of the mechanistic evidence comes from animal models and in vitro systems, and blood pressure was rarely a pre-specified primary endpoint in the major cardiovascular outcome trials from which the clinical numbers are extracted. That makes it difficult to determine whether the observed 1 to 3 mmHg reductions translate into meaningful antihypertensive benefit independent of glycemic control or weight loss, and head-to-head comparisons between agents are lacking. The review calls for trials that place blood pressure at the center of the design, translational studies in human subjects to confirm the proposed nitric oxide, atrial natriuretic peptide and renin-angiotensin pathways, and stratified analyses to identify which patients, most plausibly those with elevated baseline pressure and coexisting type 2 diabetes, stand to gain the most.

Even within those limits, the synthesis carries a striking implication. A drug class developed to restore a gut hormone signal has turned out to engage nearly every major axis of cardiovascular regulation: endothelial nitric oxide signaling, natriuretic peptide release, renal sodium handling, vascular inflammation and atherosclerotic plaque biology. Liraglutide has been shown to suppress angiotensin II-induced inflammatory cascades in vessel walls, preventing the expression of ICAM-1, VCAM-1 and P-selectin on endothelial cells and restoring nitric oxide levels. Exenatide modulates matrix metalloproteinases in human coronary artery cells and shifts macrophages from a pro-inflammatory M1 state toward a reparative M2 phenotype, stabilizing atherosclerotic lesions. Semaglutide and liraglutide reduce plaque development in mice through AMPK activation and lowered proinflammatory cytokines. The blood pressure effect, small as it is, may be the visible surface of a much deeper vascular reprogramming, and understanding it fully could determine how these blockbuster drugs are positioned in the broader campaign against cardiovascular disease.

Subject of Research: Blood pressure regulation by glucagon-like peptide-1 receptor agonists and its cardiovascular mechanisms

Article Title: Glucagon‐Like Peptide‐1 Agonists and Blood Pressure Regulation: Molecular Mechanisms and Cardiovascular Implications

Article References: Alharbi, N. H. J. (2026). Glucagon‐Like Peptide‐1 Agonists and Blood Pressure Regulation: Molecular Mechanisms and Cardiovascular Implications. Pharmacology Research & Perspectives, 14(5), Article e70329. https://doi.org/10.1002/prp2.70329

Image Credits: AI Generated

DOI: 10.1002/prp2.70329

Keywords: GLP-1 receptor agonists, blood pressure, hypertension, type 2 diabetes, nitric oxide, endothelial function, natriuresis, atrial natriuretic peptide, cardiovascular outcomes, semaglutide, liraglutide, incretin effect

The rationale for the study rests on a well-documented but poorly understood phenomenon. As people age, total cerebral blood flow and the brain vessels’ ability to respond to metabolic demands both decline, and these declines independently predict higher dementia risk even after accounting for other cardiovascular factors. At the same time, aging vasculature accumulates oxidative stress, an imbalance between reactive oxygen species and the body’s antioxidant defenses. Excess reactive oxygen species degrade nitric oxide, the signaling molecule that blood vessel linings use to relax and widen. If oxidative stress is indeed strangling the aging brain’s arteries, then flooding the system with a potent antioxidant should, in principle, loosen the grip.

To test that idea, the team recruited generally healthy young adults aged 18 to 29 and middle-aged and older adults aged 55 to 79 from the Newark, Delaware area, excluding smokers, pregnant or breastfeeding women, and anyone with cardiovascular, neurological, autoimmune, or major psychiatric conditions. Each participant completed two laboratory visits separated by at least four days, receiving an intravenous ascorbic acid infusion on one occasion and a saline placebo on the other, in a randomly assigned order. The dosing protocol, adapted from earlier vascular aging studies, delivered a priming bolus of 0.06 grams of vitamin C per kilogram of fat-free mass over 20 minutes, followed by a continuous drip of 0.02 grams per kilogram maintained until all post-infusion measurements were complete. In a small subset where blood samples survived analysis, serum vitamin C levels rose roughly sevenfold, from about 1.2 to 8.6 milligrams per deciliter, confirming the infusion pushed concentrations well above physiological norms.

The study’s centerpiece was a clever probe of cerebrovascular endothelial function. When carbon dioxide in the blood rises abruptly, vessels downstream of the internal carotid artery dilate, increasing turbulent flow and shear stress along the carotid wall. That shear stress triggers the endothelium to release nitric oxide, which widens the artery further. By using a dynamically controlled gas delivery system to raise participants’ end-tidal carbon dioxide by 9 millimeters of mercury for just 30 seconds, and imaging the internal carotid artery with high-resolution duplex ultrasound, the researchers could quantify how well the extracranial vessel lining responded to a nitric oxide–dependent stimulus. Before infusion, this response was significantly blunted in the older group: relative internal carotid artery reactivity averaged about 3.4 percent in young adults versus roughly 3.0 percent or lower in the middle-aged and older group, with the deficit most pronounced in the vitamin C visit’s baseline measurements.

After the vitamin C infusion, the picture changed markedly for the older participants. Their relative internal carotid artery reactivity rose significantly, and the absolute diameter change climbed from a mean of about 0.056 millimeters to 0.32 millimeters, effectively erasing the age gap with the young group. In striking contrast, the same participants showed no such improvement after saline, and the young adults’ responses were essentially flat regardless of which infusion they received. This pattern, improvement only where function was impaired, is exactly what the pharmaco-dissection approach predicts if oxidative stress is suppressing nitric oxide–mediated dilation in aged vessels. Notably, the carbon dioxide stimulus itself was matched across conditions, with end-tidal changes of roughly 8 to 9 millimeters of mercury in every group and time point, so the differences could not be attributed to unequal challenges.

The researchers also examined the middle cerebral artery, an intracranial vessel whose response to sustained, three-minute hypercapnia is far less dependent on nitric oxide. Using transcranial Doppler ultrasound, they measured blood velocity and, by normalizing to beat-by-beat mean arterial pressure, calculated cerebrovascular conductance. At baseline, older adults showed significantly lower conductance-based reactivity than young adults. Vitamin C infusion again improved middle cerebral artery reactivity in the older group, whether expressed as velocity change or conductance change, while saline did not. The authors suggest this intracranial effect likely operates through different pathways than the carotid response, potentially involving pH regulation, red blood cell ATP release, potassium and calcium channels, prostaglandins, or reactive oxygen species acting directly as vasodilators. The precise mechanism, they caution, remains unresolved.

Not every measurement cooperated with the tidy narrative. Total cerebral blood flow, estimated from internal carotid and vertebral artery flows, was unexpectedly higher in the older group than the young group before infusion, contradicting the large body of literature showing age-related declines. The authors note that women in their sample, who tend to have higher cerebral blood flow, made up 71 percent of the older subgroup with usable data versus 44 percent of the young subgroup, and that global flow estimates cannot capture regional perfusion differences. Vitamin C did not significantly alter total cerebral blood flow in either age group. Meanwhile, brachial artery flow-mediated dilation, the standard test of peripheral endothelial function, was lower in older adults at baseline but showed only a non-significant trend toward improvement after vitamin C. In a small subset with paired data, peripheral and cerebral endothelial responses were uncorrelated, suggesting the two beds reflect distinct endothelial physiology and should not be treated as interchangeable windows on vascular health.

The study’s limitations are considerable and the authors are candid about them. Sample sizes were small and varied across outcomes, with complete internal carotid data available for only 10 to 11 participants per infusion visit and middle cerebral artery data for 17 to 20. A freezer malfunction destroyed most serum samples, preventing direct measurement of oxidative stress markers or nitric oxide metabolites in the full cohort, which means the proposed mechanism remains inferential. The transcranial Doppler technique assumes the middle cerebral artery does not itself dilate during hypercapnia, an assumption challenged by MRI studies. No comparable vasodilatory control condition was included, so the effect cannot be definitively pinned to nitric oxide–dependent pathways. And the analysis relied on pre-specified contrasts without multiple-testing correction, appropriate for hypothesis-driven designs but demanding cautious interpretation.

Even with those caveats, the central result stands out for its clarity: antioxidant-responsive mechanisms appear to be implicated in age-related impairments of both extracranial and intracranial cerebrovascular reactivity. The authors are careful to stress that this was a mechanistic experiment, not a therapy trial, and that nothing in the data supports self-treatment with high-dose vitamin C. Oral supplementation cannot reproduce the serum concentrations achieved intravenously, and whether repeated infusions would produce lasting benefit, or whether improved reactivity translates into preserved cognition, are questions for future studies with larger and more diverse cohorts. What the trial does establish is a model: a safe, reversible intervention that selectively restores cerebrovascular function in older adults, giving researchers a tool to dissect the redox pathways that may one day be targeted to keep aging brains well perfused.

Subject of Research: Effects of intravenous ascorbic acid infusion on age-related cerebrovascular dysfunction in adults

Article Title: Supraphysiological ascorbic acid infusion attenuates cerebrovascular dysfunction in middle‐aged and older adults

Article References: DeConne, T. M., Sanjana, F., Habash, E. M., Decker, K. P., Nichols, W., Hobson, J. C., Rizzi, N. A., & Martens, C. R. (2026). Supraphysiological ascorbic acid infusion attenuates cerebrovascular dysfunction in middle‐aged and older adults. Physiological Reports, 14(19), Article e71120. https://doi.org/10.14814/phy2.71120

Image Credits: AI Generated

DOI: 10.14814/phy2.71120

Keywords: ascorbic acid, cerebrovascular reactivity, vascular aging, oxidative stress, nitric oxide, cerebral blood flow, internal carotid artery, middle cerebral artery, hypercapnia, endothelial function, dementia risk, randomized crossover trial