Researchers at Hadhramout University in Mukalla, Yemen, conducted a retrospective cross-sectional study of 106 patients admitted to the COVID-19 isolation centers at Ibn-Sina Hospital between 1 December 2021 and 30 October 2022. The cohort comprised 63 men and 43 women with a mean age of 58.3 years, and all participants had presented with clinical suspicion of COVID-19 and undergone SARS-CoV-2 RT-PCR testing on nasal or oropharyngeal swabs. Of these, 58 patients, or 54.72 percent, tested positive and were classified as confirmed cases, while 48 patients, or 45.28 percent, tested negative and were classified as suspected cases. To guard against false negatives, patients with initial negative results were retested within 48 to 72 hours, a precaution the authors argue strengthens the reliability of the negative classification.

The study, published in Acta Biochimica Polonica, was designed to compare a panel of routine hematological and biochemical parameters between the two groups. The investigators extracted demographic, clinical, hematological, and biochemical data from electronic medical records and analyzed complete blood counts alongside random blood glucose, alanine transaminase, aspartate transaminase, lactate dehydrogenase, gamma-glutamyl transferase, C-reactive protein, and ferritin. Patients with known liver disease, renal disease, hematological disorders, autoimmune diseases, or malignancies were excluded, since any of these conditions could independently distort the laboratory picture and confound the comparison.

The hematological findings were striking. Compared with the RT-PCR-negative group, patients with confirmed COVID-19 had significantly higher hemoglobin, hematocrit, red blood cell counts, and white blood cell counts. Their neutrophil counts were markedly elevated, while lymphocyte and eosinophil counts were significantly reduced. This pattern, combining neutrophilia with lymphopenia and eosinopenia, mirrors what has been described repeatedly in confirmed COVID-19 cases worldwide and is thought to reflect the systemic inflammatory response triggered by SARS-CoV-2. Lymphopenia in particular has emerged as one of the most consistent hematological signatures of the disease, and reduced eosinophil levels have been linked to inflammatory activity and delayed recovery in prior reports.

Not every measured parameter moved in the same direction. Mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelet counts, monocyte counts, and basophil counts showed no statistically significant differences between the two groups. This selectivity is itself informative, suggesting that the laboratory changes associated with confirmed infection are not a nonspecific derangement of the blood but a characteristic pattern concentrated in the white cell differential and in the oxygen-carrying components. The authors note that hemoglobin and hematocrit were higher in the confirmed group, consistent with some previous studies, although other investigations have reported declining hemoglobin with increasing disease severity, a discrepancy the researchers attribute to differences in disease stage, patient characteristics, and underlying comorbidities.

The biochemical results were equally revealing. Serum levels of lactate dehydrogenase, gamma-glutamyl transferase, C-reactive protein, and ferritin were all significantly higher in the RT-PCR-positive group, with P values below 0.001 for each comparison. Random blood glucose was also elevated in the confirmed cases. By contrast, the liver transaminases ALT and AST did not differ significantly between the groups, despite earlier literature documenting hepatic involvement in COVID-19, with some studies reporting elevated transaminase activity in a substantial proportion of patients during the course of illness. The authors suggest that elevated LDH likely reflects tissue injury and systemic inflammation, while increased GGT points toward hepatobiliary involvement, though they acknowledge that previous findings on GGT in COVID-19 have been inconsistent, with some studies reporting no difference between confirmed and suspected cases.

To probe the relationships among these markers more deeply, the team performed Pearson correlation analysis within the RT-PCR-positive group. C-reactive protein correlated positively with AST, ALT, LDH, and GGT, and ferritin showed similar positive correlations with all four enzymes. The strongest associations were seen between the inflammatory markers and LDH and GGT, hinting at a coupling between systemic inflammation and the tissue or hepatobiliary injury these enzymes signal. This interlocking pattern of inflammation and organ-associated enzyme release reinforces the idea that the biochemical disturbances of COVID-19 are not isolated abnormalities but components of a coordinated pathological process.

The most consequential result emerged from the multivariable logistic regression analysis. When the significant biochemical variables were entered into a single model, only two markers remained independently associated with RT-PCR positivity: LDH, with an odds ratio of 1.008 per unit increase and a 95 percent confidence interval of 1.002 to 1.013 and a P value of 0.004, and GGT, with an odds ratio of 0.949, a 95 percent confidence interval of 0.903 to 0.997, and a P value of 0.039. CRP, despite its dramatic univariate elevation in confirmed cases, did not retain independent significance in the model. The direction of the GGT association, with higher values slightly reducing the odds of RT-PCR positivity, is counterintuitive and underscores the complexity of interpreting these markers in a multivariable framework.

The authors are careful to frame these findings appropriately. Because the study was retrospective and cross-sectional, the observed associations between LDH, GGT, and RT-PCR positivity cannot be interpreted as evidence of predictive or causal relationships. The regression model was built primarily from available laboratory parameters and did not account for all potential clinical confounders such as age, comorbidities, and disease severity, meaning residual confounding cannot be excluded. Moreover, the RT-PCR-negative group, though retested to reduce false negatives, was not systematically screened for alternative respiratory pathogens or other inflammatory conditions, so some of these patients may have had other infections or inflammatory diseases that influenced their laboratory profiles. The single-hospital design and modest sample size further limit generalizability, and clinical outcomes such as oxygen requirement, intensive care admission, and mortality were not available for all patients and could not be assessed.

Despite these caveats, the study offers a practical message for resource-constrained settings. The constellation of higher white cell and neutrophil counts, lower lymphocyte and eosinophil counts, and elevated LDH, GGT, CRP, and ferritin provides a recognizable laboratory fingerprint of confirmed COVID-19 that can be generated with standard hospital analyzers. In places where RT-PCR capacity is limited or turnaround times are long, such patterns may support clinical judgment while definitive testing is pending. The researchers call for prospective multicenter studies with larger cohorts, comprehensive clinical characterization, appropriate adjustment for confounding factors, and evaluation of patient outcomes to confirm these findings and determine whether LDH and GGT can ultimately earn a place alongside RT-PCR in the diagnostic toolkit for COVID-19 and beyond.

Subject of Research: Hematological and biochemical differences between RT-PCR-positive and RT-PCR-negative patients with suspected COVID-19 in Yemen

Article Title: Hematological and biochemical alterations in patients with suspected COVID-19 infection with negative and positive RT-PCR swabs

Article References: Bin Dahman, L. S., Bakarman, A. A., Al-Nakhbi, N. A., Al-Haddad, A. M., Bin-Talib, A. H., Al-Saadi, H. A., Bashatah, S. T., Al-Yazidi, N. S., Al-Houti, M. S., & Bin-Dheyab, M. O. (2026). Hematological and biochemical alterations in patients with suspected COVID-19 infection with negative and positive RT-PCR swabs. Acta Biochimica Polonica, 73, Article 16764. https://doi.org/10.3389/abp.2026.16764

Image Credits: AI Generated

DOI: 10.3389/abp.2026.16764

Keywords: COVID-19, SARS-CoV-2, RT-PCR, lactate dehydrogenase, gamma-glutamyl transferase, CRP, ferritin, lymphopenia, neutrophilia, Yemen, biomarkers, retrospective study

The protein in question is claudin-3, a member of the claudin family of transmembrane proteins that zip together the tight junctions sealing the intestinal epithelium. Tight junctions are the molecular gatekeepers of the gut, forming a complex network of epithelial cells interlinked by strands of claudins and other junctional proteins anchored to the actin cytoskeleton. When these seals are intact, the gut selectively absorbs nutrients while excluding luminal antigens, bacterial products, and microbial metabolites. When they fail, the intestine becomes permeable in the colloquial sense of a leaky gut, allowing potentially inflammatory cargo to cross into the underlying mucosal immune system. Claudin-3 is among the most abundantly expressed claudins in the gut and is considered a barrier-forming protein, and circulating claudin-3 in the blood is increasingly regarded as a surrogate readout of intestinal barrier integrity, since disruption of tight junctions can release these proteins into the circulation.

Previous attempts to interrogate the gut barrier in FGIDs have relied almost exclusively on intestinal biopsies, an invasive and impractical approach, particularly in adolescents. The Egyptian team, led by Azza Abd El-Shaheed and colleagues, set out to test whether a simple venous blood draw could accomplish what endoscopy has done in research settings. They enrolled 70 adolescents aged 10 to 18 years who fulfilled the Rome IV diagnostic criteria for FGIDs, confirmed using the Rome IV Diagnostic Questionnaire after detailed history taking and comprehensive clinical evaluation, along with 65 apparently healthy adolescents of comparable age and sex distribution. The researchers deliberately excluded anyone with organic gastrointestinal disease, including celiac disease, inflammatory bowel disease, lactose intolerance, structural anomalies, gastrointestinal infections, chronic hepatic or renal disease, or any acute or chronic inflammatory condition, ensuring that the measured signals could be attributed to functional rather than overt inflammatory pathology.

Using enzyme-linked immunosorbent assays, the team quantified serum claudin-3 alongside four established inflammatory markers: C-reactive protein, interleukin-6, tumor necrosis factor alpha, and haptoglobin. The results were strikingly consistent. Serum claudin-3 concentrations were significantly higher in the FGIDs group than in controls, with a p-value of 0.02. All four inflammatory markers were likewise elevated in the patients: CRP at p = 0.039, interleukin-6 at p = 0.04, tumor necrosis factor alpha at p = 0.021, and haptoglobin at p = 0.001. Taken together, these findings paint a picture of adolescents whose gut barriers are measurably compromised and whose systemic circulation carries the fingerprints of low-grade immune activation, despite the absence of any diagnosable organic disease.

The most conceptually important finding, however, lay in the correlations. Among the FGIDs patients, serum claudin-3 showed significant positive correlations with CRP (r = 0.45, p < 0.001), interleukin-6 (r = 0.30, p = 0.011), and haptoglobin (r = 0.53, p < 0.001). The correlation with tumor necrosis factor alpha, by contrast, did not reach statistical significance (r = 0.19, p = 0.117). This pattern suggests that intestinal barrier dysfunction and systemic low-grade inflammation are not independent phenomena in FGIDs but tightly coupled processes along what the authors describe as a gut-barrier-immune axis. Mechanistically, the hypothesis is coherent: a disrupted epithelial barrier permits translocation of luminal antigens and microbial products across the intestinal wall, activating mucosal and systemic immune responses and driving the release of pro-inflammatory cytokines, which in turn sustain the chronic, subtle inflammation increasingly recognized as a core pathophysiological feature of these disorders.

The selective correlation pattern also carries mechanistic information. Interleukin-6 is the most potent inducer of hepatic acute-phase protein synthesis, including both CRP and haptoglobin, so its tight relationship with claudin-3 may reflect persistent systemic inflammation secondary to barrier impairment. Tumor necrosis factor alpha, on the other hand, is characterized by transient production, a short circulating half-life, and substantial biological variability, any of which could weaken its statistical association with claudin-3 even though patients’ levels were significantly elevated. The authors also acknowledge that the heterogeneous nature of FGIDs and the limited sample size may have contributed to the absence of a significant TNF-alpha correlation, a caveat that applies broadly to biomarker studies in this clinically diverse population.

The new findings dovetail with a growing body of tissue-based research. Kong and colleagues reported altered intestinal expression of claudin proteins in patients with irritable bowel syndrome, while Taki and colleagues demonstrated significantly increased claudin-3 mRNA expression in the duodenal mucosa of patients with functional dyspepsia. Vanheel’s group further showed that disruption of epithelial barrier proteins was associated with increased intestinal permeability and low-grade inflammation in functional dyspepsia. Not all prior studies agree, however: Awad and colleagues detected no significant alterations in claudin-3 expression in colonic biopsies from patients with mixed-type irritable bowel syndrome, and Nojkov and colleagues found no statistically significant difference in claudin-3 gene expression in functional dyspepsia versus controls. The discrepancies likely reflect differences in age groups, specimen types, analytical techniques, FGID subtypes, and disease heterogeneity. What distinguishes the present work is its demonstration that a non-invasive serum assay can capture barrier dysfunction that previously required biopsy.

The clinical implications are considerable. FGIDs are diagnosed today using the Rome IV criteria, which improved characterization and clinical practice but remain insufficient to enable individualized therapy, and no adequate biomarkers exist for precise diagnosis. A validated blood test based on claudin-3 could help stratify patients, track disease activity, and identify those most likely to benefit from therapies aimed at restoring barrier integrity. The authors argue that their findings support the idea that impaired intestinal barrier function may promote the development of FGIDs by inducing inflammation, which in turn positions restoration of intestinal barrier integrity as a potential therapeutic target. If confirmed, interventions ranging from dietary modification to barrier-protective agents could one day be guided by serial claudin-3 measurements rather than symptom reports alone.

Caution is warranted before the laboratory becomes the clinic. This was a cross-sectional case-control study of 135 adolescents from a single outpatient clinic in Cairo, and correlation does not establish causation: elevated claudin-3 could be a cause, a consequence, or merely a correlate of the inflammatory state in FGIDs. The authors themselves recommend further longitudinal studies involving larger cohorts to clarify the role of specific claudin proteins in promoting FGIDs and to evaluate serum claudin-3 as a diagnostic, prognostic, and therapeutic monitoring biomarker. Interventional studies aimed at restoring barrier function are needed to determine whether modulating the barrier actually improves clinical outcomes. Still, the study represents a genuine first: the first assessment of serum claudin-3 as a non-invasive biomarker of intestinal permeability in adolescents with FGIDs. For a disorder group long defined by what it is not, no inflammation, no structural damage, no abnormal tests, the prospect of a measurable molecular signature of a leaky barrier and its inflammatory consequences is a step toward making the invisible visible, and toward treating teenage gut disorders with the biological precision they have long lacked.

Subject of Research: Serum claudin-3 as a non-invasive biomarker of intestinal permeability and low-grade inflammation in adolescents with functional gastrointestinal disorders

Article Title: Claudin-3 as a marker of intestinal permeability and its relation to inflammatory status in adolescents with functional gastrointestinal disorders

Article References: Abd El-Shaheed, A., Mahfouz, N. N., Metwaly, H. H., Sibaii, H., & Abd El-Fattah, S. N. (2026). Claudin-3 as a marker of intestinal permeability and its relation to inflammatory status in adolescents with functional gastrointestinal disorders. Pediatric Research. https://doi.org/10.1038/s41390-026-05497-0

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05497-0

Keywords: claudin-3, intestinal permeability, functional gastrointestinal disorders, leaky gut, tight junctions, adolescents, inflammation, CRP, interleukin-6, TNF-alpha, biomarker, Pediatric Research

The research team, led by Qinghua Guo, Yong Wang, Chuan Shi, and Shaomei Shang, followed 136 adults undergoing an acute course of ECT in a real-world clinical setting. Each participant completed the ECT-CI and the Montreal Cognitive Assessment, better known as the MoCA, at three time points: before treatment began, within 48 hours after the acute course ended, and again at a three-month follow-up. Crucially, the study did not rely on test scores alone to define impairment. Blinded psychiatrists adjudicated whether each patient met criteria for cognitive impairment using a framework based on the DSM-5-TR, the current edition of the American Psychiatric Association’s diagnostic manual, and those clinician judgments served as the reference standard against which both instruments were judged.

The clinical picture that emerged was sobering. Clinician-adjudicated cognitive impairment rose from 12.5 percent of patients at baseline to 33.1 percent immediately after the acute treatment course, and then climbed further to 50.7 percent at the three-month follow-up. That trajectory, in which the proportion of patients judged cognitively impaired continues to rise well after the last seizure has been induced, underscores how incomplete our understanding of post-ECT cognition remains. Many patients do not simply recover in a straight line after treatment ends, and some appear to experience worsening difficulties that only become apparent weeks later, a pattern that brief in-hospital testing at discharge would entirely miss.

Against this backdrop, the performance of the two cognitive instruments diverged in ways that matter for everyday practice. ECT-CI scores fell from baseline to the post-course assessment and then partially rebounded at follow-up, and the magnitude of those observed score changes was larger than what the MoCA captured over the same period. The ECT-CI also took less time to administer, a nontrivial advantage at the bedside of acutely ill psychiatric inpatients. At the domain level, the inventory registered changes in memory, executive function, and caregiver-rated cognition, offering a multidimensional view of how patients were actually functioning rather than a single composite number. In statistical comparisons of discrimination, essentially the ability of a test score to separate patients who have impairment from those who do not, the ECT-CI outperformed the MoCA against the clinician-adjudicated reference standard at every assessment point.

Perhaps the most clinically consequential finding concerned prediction. Baseline ECT-CI scores showed greater prognostic discrimination than baseline MoCA scores for identifying which patients would meet the clinician-adjudicated criteria for cognitive impairment three months later. In practical terms, this means a brief test administered before the first seizure could help clinicians flag patients at elevated risk of lasting cognitive difficulty, opening a window for interventions that do not currently exist in routine care: closer monitoring, adjusted treatment parameters, or earlier supportive measures. The MoCA, designed as a general screen for dementia and delirium across clinical populations, simply was not built to detect the specific, often subtle cognitive signature that ECT produces.

To move beyond averages and capture the diversity of individual recovery patterns, the researchers turned to growth mixture modelling, a statistical technique that identifies hidden subgroups within a population based on how their scores change over time. The analysis revealed three distinct ECT-CI trajectories. One group maintained high, stable scores throughout, suggesting resilience to the cognitive effects of treatment. A second group experienced an acute decline in scores immediately after the treatment course followed by a partial rebound at follow-up, a pattern consistent with transient, treatment-related effects that fade with time. The third and most concerning group started from a low baseline and suffered a marked acute decline, entering treatment already cognitively vulnerable and deteriorating further.

Who ended up in that worst trajectory was not random. Lower baseline MoCA scores and a diagnosis of schizophrenia were associated with membership in the low-baseline, marked-decline group. This finding carries real weight for treatment planning. Patients with schizophrenia who undergo ECT, often for refractory symptoms, may represent a population in whom cognitive reserve is already diminished and in whom the additional burden of a treatment course pushes function below a critical threshold. The results support a model of risk-stratified cognitive monitoring, in which patients are assessed before treatment and assigned to different intensities of follow-up based on their baseline profile and diagnostic background, rather than receiving a uniform, one-size-fits-all check.

The study also ventured into territory that has attracted growing interest across neuropsychiatry: the role of inflammation. In exploratory analyses, the researchers examined systemic immune-inflammatory markers, including the systemic immune-inflammation index and related indices derived from routine blood counts, along with C-reactive protein, a well-known marker of systemic inflammation. Their analyses suggested that systemic immune-inflammatory burden characterized the unfavourable cognitive trajectories, and, intriguingly, that baseline CRP levels interacted with the cumulative ECT charge, the total amount of electrical stimulation a patient received over the course. In other words, the relationship between how much stimulation a patient’s brain absorbed and whether that patient developed clinician-adjudicated cognitive impairment appeared to depend on the inflammatory state of the body before treatment began.

These inflammatory findings must be read with appropriate caution, as the authors themselves frame them as exploratory, and a single cohort study cannot establish mechanism. But the underlying hypothesis is biologically plausible and resonates with a broader literature linking neuroinflammation to vulnerability of the hippocampus and other memory-critical structures. If confirmed in independent samples, the idea that inflammatory status modifies the cognitive cost of cumulative electrical stimulation could reshape how clinicians think about dosing strategies. It might eventually support the use of inexpensive blood tests, already drawn routinely in pre-ECT workups, as part of a personalized risk assessment, and it could motivate trials of anti-inflammatory or lifestyle interventions aimed at lowering inflammatory burden before an elective treatment course.

What the study delivers most concretely is a validation case for disease-specific measurement. The ECT-CI tracked score changes that the MoCA missed, discriminated better against a rigorous clinical reference standard, predicted three-month outcomes from baseline, and lent itself to trajectory-based risk stratification, all while requiring less administration time. For a procedure administered to hundreds of thousands of patients worldwide each year, the absence of a dedicated cognitive monitoring standard has been a conspicuous gap. This prospective real-world cohort, registered with the Chinese Clinical Trial Registry and conducted under ethics approval at Peking University Sixth Hospital, provides the strongest longitudinal evidence to date that filling that gap is both feasible and clinically worthwhile. The next steps, replication in larger and more diverse populations, external validation of the three-trajectory model, and prospective testing of whether risk-stratified monitoring actually improves patient outcomes, will determine whether the ECT-CI moves from promising research instrument to standard of care. For now, the message for clinicians is clear: when it comes to the cognitive price of electroconvulsive therapy, the right questions, asked with the right tool, reveal risks that general screening has been quietly missing.

Subject of Research: Longitudinal validation of the ECT-CI for monitoring cognitive impairment after electroconvulsive therapy

Article Title: Longitudinal evaluation of the ECT-CI after electroconvulsive therapy: score changes, clinical discrimination, and latent score trajectories in a prospective real-world cohort

Article References: Guo, Q., Wang, Y., Guo, L., He, X., Pu, C., Shi, C., & Shang, S. (2026). Longitudinal evaluation of the ECT-CI after electroconvulsive therapy: score changes, clinical discrimination, and latent score trajectories in a prospective real-world cohort. BMC Psychiatry. https://doi.org/10.1186/s12888-026-08718-2

Image Credits: AI Generated

DOI: 10.1186/s12888-026-08718-2

Keywords: electroconvulsive therapy, ECT-CI, cognitive impairment, MoCA, growth mixture modelling, prognostic discrimination, inflammation, CRP, psychiatry, neuropsychological assessment, schizophrenia, longitudinal cohort

Persistent organic pollutants, or POPs, are a diverse class of chemicals defined by three troubling properties: they resist degradation in the environment, they accumulate in the fatty tissues of living organisms, and they can be toxic to humans. Because they travel through food chains and persist for decades, compounds that were banned or restricted years ago still circulate in the blood of people who never directly handled them. The study focused on four major families: organochlorine pesticides such as dieldrin and heptachlor epoxide, polychlorinated biphenyls known as PCBs, polybrominated diphenyl ethers or PBDEs used as flame retardants, and per- and polyfluoroalkyl substances, the widely discussed PFAS.

The research team, led by Francesca Romana Mancini of Université Paris-Saclay, Inserm and Gustave Roussy, together with colleagues including German Cano-Sancho and Jean-Philippe Antignac of the LABERCA laboratory in Nantes and Gianluca Severi, drew on a cross-sectional sample of 468 women from the E3N-Generations cohort, a long-running French epidemiological project built on data from Inserm and supported by the Mutuelle Générale de l’Education Nationale, the Gustave Roussy Institute and the French League against Cancer. Blood samples were collected between 1994 and 1999, a period that gives researchers a window into body burdens accumulated during decades when many of these chemicals were still in active use.

What makes the study technically ambitious is its sheer analytical breadth. The researchers measured concentrations of 45 different POPs in each blood sample, alongside four circulating biomarkers of systemic inflammation: C-reactive protein, or CRP, interleukin-8, known as IL-8, monocyte chemoattractant protein-1, or MCP-1, and tumor necrosis factor-alpha, or TNF-alpha. These markers are the immune system’s chemical messengers and alarm bells. CRP, produced by the liver in response to inflammatory signals, is one of the most widely used clinical gauges of systemic inflammation, while IL-8, MCP-1 and TNF-alpha are signaling molecules involved in recruiting and activating immune cells. Chronically elevated levels of such markers have been linked in earlier research to a range of conditions, from cardiovascular disease to metabolic disorders, which is why toxicologists are keen to understand what drives them upward or downward.

The analytical strategy unfolded in two stages. First, the team applied logistic regression models to test whether individual POPs were associated with the inflammatory biomarkers, which were dichotomized, meaning participants were classified as having levels above or below a threshold. This compound-by-compound approach is the traditional way to scan for signals, but it has a well-known weakness: people are never exposed to one chemical at a time. POPs tend to travel together through food, water and the environment, so a person with high dieldrin likely carries elevated levels of related compounds too, making it hard to disentangle which agent is doing what.

To address that complexity, the researchers turned to principal component analysis, a statistical technique that compresses dozens of correlated pollutant measurements into a smaller number of composite exposure profiles. Each component represents a shared pattern of co-occurring chemicals, reflecting real-world exposure mixtures rather than isolated compounds. These derived profiles were then fed back into regression models to see whether the mixtures themselves, rather than any single pollutant, tracked with inflammation. This dual approach, examining both individual compounds and mixture-based components, is increasingly seen as the gold standard in modern exposure science, where the concept of the exposome demands that researchers grapple with chemical cocktails rather than single agents.

The results split along chemical family lines in a striking way. Several organochlorine pesticides were positively associated with CRP levels, meaning women with higher blood concentrations of these legacy insecticides tended to show more of the inflammation marker. The finding held up when the mixture-based analysis was applied, lending it weight. After the researchers applied false discovery rate correction, a statistical safeguard that accounts for the many comparisons made when dozens of chemicals are tested simultaneously, two pesticides stood out as robust: cis-heptachlor epoxide, a breakdown product of the banned insecticide heptachlor, and dieldrin, another long-restricted pesticide. That these associations survived such stringent correction suggests they are unlikely to be statistical flukes, although the cross-sectional design of the study means it cannot prove that the pollutants caused the elevated inflammation.

Just as intriguing was the pattern on the other side of the ledger. Multiple PFAS compounds were inversely associated with IL-8 concentrations, both when tested individually and as part of a shared exposure component identified by the principal component analysis. Among them, PFDA, PFNA and PFOS showed the most robust associations after false discovery rate correction. In plain terms, women with higher blood levels of these fluorinated chemicals tended to have lower levels of the IL-8 inflammatory signal. The direction of this association is notable because PFAS, often called forever chemicals due to their extreme persistence, have been implicated in a wide range of health concerns in prior research, and an inverse link with an inflammatory marker does not necessarily indicate a protective effect. Biological relationships of this kind can reflect complex interactions, including the possibility that PFAS displace other compounds, alter immune signaling in unexpected ways, or correlate with other characteristics of the study participants that the models do not fully capture.

The authors are careful about what the study can and cannot say. As a cross-sectional analysis, it captures a snapshot of pollutant levels and inflammation markers at a single point in time, so reverse causation and confounding remain possibilities. Inflammation itself can change how chemicals are distributed and stored in the body, and the researchers note that immune and inflammatory dysregulation has been proposed as a key pathway underlying the adverse health effects of POPs, a hypothesis this study helps to refine rather than definitively confirm. Still, the convergence of individual-compound and mixture-based analyses on the same signals, reinforced by false discovery rate correction, gives the findings more credibility than a simple one-off association would carry.

The broader significance lies in the study’s demonstration that mixed exposures matter. By highlighting the importance of considering both individual compounds and exposure mixtures, the work aligns with a shift in environmental health research away from single-chemical risk assessment and toward methods that reflect the reality of simultaneous, low-dose, lifelong exposure. The E3N-Generations cohort, approved by the French National Commission for Data Protection and Privacy and by the Bicêtre ethics committee, with all participants giving written informed consent including for novel biomarker testing, provided the biological foundation, while the HBM platform of LABERCA, part of the France-Exposome and EIRENE research infrastructures, delivered the analytical muscle needed to quantify 45 pollutants with the precision such comparisons demand. As regulators worldwide confront mounting pressure to address PFAS contamination and as legacy pesticides continue to persist in soils and food chains, studies like this one offer a template for understanding not just whether these chemicals are present, but what they may be doing inside us. The open-access study, published on 28 September 2026, invites both replication in other populations and longitudinal follow-up to determine whether the inflammatory signatures observed here translate into tangible health outcomes over time.

Subject of Research: Associations between blood levels of persistent organic pollutants and systemic inflammation biomarkers in French women

Article Title: Blood levels of persistent organic pollutants and circulating biomarkers of systemic inflammation in French women: evidence from the E3N-generations cohort

Article References: Mancini, F. R., Frénoy, P., Cano-Sancho, G., Marques, C., Ren, X., Perrin, C., Perduca, V., Marchand, P., Le Bizec, B., Antignac, J.-P., & Severi, G. (2026). Blood levels of persistent organic pollutants and circulating biomarkers of systemic inflammation in French women: evidence from the E3N-generations cohort. Environmental Health. https://doi.org/10.1186/s12940-026-01340-5

Image Credits: AI Generated

DOI: 10.1186/s12940-026-01340-5

Keywords: persistent organic pollutants, PFAS, organochlorine pesticides, systemic inflammation, CRP, IL-8, E3N-Generations cohort, biomarkers, chemical mixtures, dieldrin, PCBs, environmental health

The new assay targets three biologically interconnected classes of circulating proteins that together paint a detailed portrait of metabolic health: adipokines, the signaling molecules secreted by fat tissue that regulate appetite, insulin sensitivity, and inflammation; apolipoproteins, the protein scaffolds of lipoprotein particles that govern cholesterol and triglyceride transport; and inflammatory proteins, whose chronic elevation in obesity contributes to tissue damage and metabolic dysfunction. Rather than measuring these proteins one at a time with traditional immunoassays, which can suffer from antibody cross-reactivity and poor standardization across laboratories, the team harnessed targeted mass spectrometry, a technique that identifies and quantifies proteins by detecting characteristic peptide fragments with exquisite molecular specificity. The approach, often described as selected reaction monitoring when performed on triple quadrupole instruments, essentially gives each target protein a unique molecular fingerprint that can be counted with high precision.

Developing a robust assay for 42 proteins at once is no small technical undertaking, and the researchers invested considerable effort in optimization at every step of the workflow. They carefully selected surrogate peptides, short amino acid sequences released when plasma proteins are enzymatically digested, choosing fragments that are unique to each target protein, chemically stable, and reproducibly generated by the digestion enzyme trypsin. Digestion incubation time was systematically tuned to ensure complete and consistent protein breakdown, and the liquid chromatography gradient used to separate peptides before mass analysis was refined to resolve all targets within a single analytical run. The assay was then rigorously evaluated for linearity across a wide concentration range, for its lower limit of quantification, for imprecision between runs, and for the stability of measurements over time, all critical parameters for any assay that might eventually leave the research laboratory and enter clinical use.

A key innovation of the study is the semi-automated sample preparation workflow built around standard 96-well plates, the same format used in high-throughput clinical chemistry laboratories. Plasma samples are subjected to protein denaturation, reduction with dithiothreitol, alkylation with iodoacetamide, and enzymatic digestion, all in a plate-based format that minimizes manual handling and reduces variability between samples. Stable-isotope labeled versions of the surrogate peptides are spiked into each sample as internal standards, allowing the light-to-heavy peak area ratios measured by the mass spectrometer to be converted into absolute protein concentrations. This isotope dilution strategy is one of the hallmarks of targeted mass spectrometry, providing a level of quantitative accuracy and inter-laboratory reproducibility that antibody-based methods have historically struggled to achieve.

To demonstrate that the assay could travel between laboratories, the team conducted an inter-laboratory validation using plasma samples from 70 healthy individuals analyzed according to a finalized standard operating procedure. The results from the two sites showed strong correlation, providing convincing evidence that the assay’s performance is not an artifact of a single instrument or operator but a transferable, standardized measurement. This kind of reproducibility testing is essential if protein biomarkers are ever to be used consistently in multi-center clinical trials or, ultimately, in routine patient care, where results generated in different hospitals must be directly comparable.

With the analytical platform validated, the researchers applied it to a clinical cohort of individuals enrolled in a weight loss intervention study, comparing protein abundance across obese, overweight, and healthy control groups. The multiplexed measurements revealed significant differences in the levels of six proteins across the three groups, and when obese individuals were compared with all non-obese participants combined, sixteen proteins emerged as differentially abundant. These findings underscore the value of measuring many biomarkers in parallel: rather than relying on a single protein signal, the assay captures a coordinated molecular pattern that reflects the systemic physiology of obesity, from altered lipid transport to chronic low-grade inflammation and changes in adipose tissue signaling.

Perhaps the most clinically intriguing result came from tracking biomarker changes over the course of the weight loss intervention. Among participants, the researchers identified four proteins whose plasma concentrations changed significantly in individuals who achieved more than five percent body weight loss: C-reactive protein, a well-known marker of systemic inflammation; proteoglycan 4, or PRG4, a lubricating glycoprotein more famous for its role in joint health; pigment epithelium-derived factor, known as SERPINF1, which has been implicated in metabolic regulation; and sex hormone-binding globulin, or SHBG, a liver-derived protein whose levels typically rise as insulin sensitivity improves. The fact that these molecular shifts were detectable specifically in responders suggests the assay could serve as an objective, quantitative readout of whether a weight loss intervention is genuinely altering a patient’s metabolic biology, not merely the number on a scale.

The implications extend beyond obesity itself. Because the panel includes apolipoproteins and inflammatory markers with established ties to cardiovascular disease and type 2 diabetes, the same assay could support risk stratification studies aimed at identifying which individuals with obesity are most likely to develop downstream complications. It could also accelerate pharmaceutical research, where candidate anti-obesity drugs must be evaluated for their effects on circulating protein biomarkers in early-phase trials. The high-throughput plate-based format means hundreds of samples can be processed efficiently, making the platform well suited to the large longitudinal cohorts that such studies demand, and the open publication of the standard operating procedure lowers the barrier for other laboratories to adopt and extend the method.

It is worth emphasizing what this study does and does not claim. The assay is a research tool today, not a diagnostic test cleared for clinical use, and the biomarker findings in the intervention cohort, while statistically significant, will require confirmation in larger and more diverse populations. Nevertheless, the work represents a meaningful demonstration that targeted mass spectrometry can deliver precise, multiplexed, and reproducible protein measurements from a small volume of plasma, addressing long-standing limitations of antibody-based biomarker assays. As the cost of high-resolution mass spectrometers continues to fall and standardized protocols like this one proliferate, the vision of a molecularly detailed blood test that quantifies dozens of health-relevant proteins in a single run is moving steadily closer to reality, and obesity medicine may be one of the first fields to benefit.

Subject of Research: Multiplexed targeted mass spectrometry quantification of obesity-associated plasma protein biomarkers

Article Title: A multiplexed targeted mass spectrometric assay for quantifying obesity-associated biomarkers in human plasma

Article References: Lin, T.-T., Dakup, P. P., Schepmoes, A. A., Fillmore, T. L., Swensen, A. C., Kelly, S. S., Zhang, T., Pu, J., Jacobs, J. M., DeLany, J. P., Goodpaster, B. H., Shi, T., Qu, J., & Qian, W.-J. (2026). A multiplexed targeted mass spectrometric assay for quantifying obesity-associated biomarkers in human plasma. Clinical Proteomics. https://doi.org/10.1186/s12014-026-09625-0

Image Credits: AI Generated

DOI: 10.1186/s12014-026-09625-0

Keywords: obesity, biomarkers, mass spectrometry, human plasma, adipokines, apolipoproteins, inflammatory proteins, weight loss, proteomics, CRP, SHBG, clinical assay

The research, led by Cassidy A. Guida of Wake Forest University School of Medicine, pooled individual participant data from seven randomized caloric restriction trials involving 829 older adults. The trials, drawn from Wake Forest’s Integrated Aging Studies Databank and Repository, ranged in duration from six to eighteen months and enrolled participants with overweight or obesity, many with coexisting conditions such as cardiovascular disease, knee osteoarthritis, or low physical function. Participants averaged 67.5 years of age, roughly two-thirds were women, and mean body mass index values ranged from about 30 to 36 kilograms per square meter across the contributing studies.

The biomarker index at the heart of the study was constructed following the framework of the TAME, or Targeting Aging with Metformin, Biomarkers Workgroup, which identified blood-based measures that best capture core hallmarks of aging while remaining practical for large clinical trials. Six biomarkers made the cut: C-reactive protein, interleukin-6, cystatin C, insulin, growth differentiation factor-15, and tumor necrosis factor-receptor 1. Together, these markers span inflammation, insulin signaling, metabolic stress, and renal function, domains that animal research has consistently tied to the biology of dietary restriction. Each participant’s change in each biomarker was converted to a quintile score, and the scores were summed into a single composite index, an approach intended to smooth out the inter-individual variability that plagues single-biomarker measures.

The results were strikingly consistent. Across the pooled trials, randomization to caloric restriction produced an average weight loss of 7.9 kilograms, compared with 1.2 kilograms in control groups, and was associated with a 2.2-point improvement in the composite biomarker quintile score, a statistically robust effect with every contributing study showing a benefit. Reductions were most pronounced in C-reactive protein, interleukin-6, insulin, and TNF-receptor 1, while cystatin C and GDF-15 showed more heterogeneity across studies. The consistency of the direction of effect, even in trials with different designs, intervention intensities, and follow-up periods, strengthens the case that the index is genuinely responsive to caloric restriction rather than an artifact of any single trial.

The most consequential question, however, was not whether caloric restriction improved the index, but how. Critics have long argued that the benefits of dietary restriction simply reflect weight loss itself rather than any special biology of eating less. To address this, the researchers performed a formal mediation analysis exploiting the randomization design: because assignment to caloric restriction was random, any relationship between the intervention and downstream outcomes could be decomposed into a portion mediated by weight loss and a residual, weight-independent effect.

The answer was nuanced. Roughly 48.5 percent of the effect of caloric restriction on the composite biomarker index was explained by the amount of weight participants lost. When change in body weight was added to the statistical model, the effect of caloric restriction shrank from minus 2.2 to minus 1.2 points, but it did not disappear. Conversely, the effect of weight loss itself dropped from 0.22 to 0.16 points per kilogram when caloric restriction assignment was accounted for. Both pathways, in other words, contribute independently. The residual direct effect of caloric restriction, at minus 1.34 points for the composite score, remained statistically significant, indicating that something beyond the number on the scale is driving the improvement.

That something may involve the nutrient-sensing pathways that decades of animal research have implicated in dietary restriction’s life-extending effects. Caloric restriction is known to activate AMP-activated protein kinase and sirtuin 1 while suppressing mechanistic target of rapamycin signaling, a trio of molecular switches that promotes autophagy, the cellular housekeeping that clears damaged proteins and organelles. These same pathways temper oxidative stress and chronic low-grade inflammation, providing a plausible biological bridge to the observed reductions in C-reactive protein and interleukin-6 that occurred independent of weight loss. Mitochondrial adaptations and shifts in innate immune cell metabolism may similarly underlie the insulin improvements seen in the trials, though the authors caution that these mechanisms were not directly measured and remain inferential.

The findings resonate with a broader pattern emerging across geroscience. In the landmark CALERIE trial, two years of roughly 12 percent caloric restriction in younger, normal-weight adults improved cardiometabolic risk factors and slowed the pace of aging as measured by the DunedinPACE epigenetic algorithm, yet did not change static estimates of biological age. Meanwhile, secondary analyses of the SELECT trial of semaglutide found that cardiovascular benefits persisted across weight categories and were driven in part by reductions in waist circumference rather than body weight alone. Together with the new pooled analysis, these results suggest that interventions targeting energy balance act through weight-dependent and weight-independent routes, and that responsive biomarker indices may capture these effects more faithfully than fixed biological age estimates.

The study has limitations worth noting. All seven trials came from a single research network with overlapping investigators and similar protocols, which may limit generalizability to more diverse populations. The intervention durations were relatively short, so the results demonstrate that caloric restriction favorably modifies aging-related biomarkers rather than proving reductions in disease or mortality. Individual components of the index, particularly GDF-15 and cystatin C, behaved inconsistently across studies, and whether the composite index correlates with epigenetic clocks or validated frailty measures remains an open question for future work.

Still, the implications are considerable. With roughly 40 percent of American adults aged 65 and older now living with obesity, and obesity a major driver of multimorbidity, frailty, and late-life disability, interventions that target the biology of aging hold enormous public health promise. The demonstration that a practical, six-marker blood index can detect intervention effects across heterogeneous trials positions such indices as potential surrogate endpoints for geroscience trials, potentially accelerating the testing of strategies to extend healthspan. And the finding that about half of caloric restriction’s benefit operates through pathways that weight loss alone cannot explain reinforces a message that biologists have been echoing from animal studies for decades: eating less does something to the machinery of aging that goes far beyond slimming down.

Subject of Research: The effect of caloric restriction on biological aging measured by a composite blood biomarker index in older adults

Article Title: Impact of caloric restriction on biological aging: insights from a composite biomarker index in older adults

Article References: Guida, C. A., Hsu, F.-C., Neiberg, R., Semelka, C., Chen, H., Kramer, P., Houston, D. K., Nicklas, B., Kritchevsky, S. B., & Miller, M. E. (2026). Impact of caloric restriction on biological aging: insights from a composite biomarker index in older adults. GeroScience. https://doi.org/10.1007/s11357-026-02529-9

Image Credits: AI Generated

DOI: 10.1007/s11357-026-02529-9

Keywords: caloric restriction, biological aging, biomarkers, geroscience, older adults, inflammation, insulin, weight loss, mediation analysis, CRP, IL-6, Impact