The scale of the problem is enormous. Roughly 50 million people sustain traumatic brain injuries annually, and the global economic burden exceeds 400 billion US dollars. Surgeons can relieve pressure and clinicians can manage symptoms with osmotic agents, diuretics, and glucocorticoids, but none of these supports repair of the injured tissue. The real killers are the secondary cascades that unfold over hours to days: rising intracranial pressure, cerebral edema, breakdown of the blood-brain barrier, ischemia, redox imbalance, and a self-reinforcing wave of neuroinflammation. Edema and inflammation feed each other. A leaky barrier lets immune cells and plasma flood into brain tissue, swelling activates resident microglia, and the inflammatory signals they release further destabilize the endothelial tight junctions that hold the barrier together. Breaking that loop is a central therapeutic goal.

Cannabidiol, or CBD, has long been an attractive candidate for exactly this job. It is anti-inflammatory, antioxidant, and non-intoxicating, and the team’s earlier work showed that CBD restores blood-brain barrier integrity after brain injury through the PGE2-EP2-cAMP pathway while also damping microglial activation. The obstacle has always been delivery. Because CBD is highly lipophilic, intraperitoneal injection sends much of the drug into adipose tissue rather than the brain. Oral dosing loses more than 70 percent of the compound to first-pass metabolism in the liver. Intravenous injection achieves full bioavailability but suffers from a short half-life and demands professional administration, an awkward constraint in acute care. None of the conventional routes keeps therapeutic levels of CBD parked at a contused cortex for the critical first days.

The researchers’ solution was a sponge made of gelatin methacryloyl, or GelMA, a photocrosslinkable hydrogel already used in drug delivery, ophthalmic therapy, and cardiac repair. The team synthesized GelMA by reacting gelatin with methacrylic anhydride, confirmed the modification with proton nuclear magnetic resonance spectroscopy and infrared spectroscopy, and screened twelve candidate formulations by varying the gelatin-to-anhydride ratio and ultraviolet crosslinking time. They judged each variant on swelling behavior, mass loss in simulated body fluid, and microstructure imaged by scanning electron microscopy. The winning formulation swelled only modestly, between 13 and 25 percent, retained a porous interconnected architecture, and fully degraded within five days under the tested conditions, a profile suited to a temporary implant that releases drug and then disappears.

Loading the sponge with CBD changed none of those material properties. Infrared spectra of the finished product showed the hydroxyl and aliphatic carbon-hydrogen stretching peaks characteristic of cannabidiol, while swelling and degradation curves remained essentially identical to the blank scaffold. Ultraperformance liquid chromatography measured encapsulation efficiencies between roughly 50 and 63 percent, with batch-to-batch variation below 3 percent and, remarkably, center-to-periphery drug ratios of almost exactly one, meaning the CBD was distributed evenly through each sponge. In a release assay, about 22 percent of the payload emerged in the first two hours, followed by a steady trickle that reached roughly 58 percent at 24 hours and 80 percent by 72 hours, precisely the sustained profile the early post-injury phase demands.

Safety testing came next, and it was thorough. Extracts of the sponge were applied to hippocampal neurons, astrocytes, and brain endothelial cells; viability remained high up to 5 micrograms per milliliter, defining a safe exposure window, while hemolysis assays with rat red blood cells showed rates below 5 percent. The team then implanted the sponges into rats subjected to a standardized weight-drop cortical contusion and tracked CBD with high-resolution liquid chromatography mass spectrometry. The pharmacokinetic contrast with conventional dosing was striking. After intraperitoneal injection, CBD in the injured cortex peaked at about 91 nanograms per gram and faded quickly. With the sponge, cortical concentrations reached about 251 nanograms per gram and remained detectable for the entire 48-hour observation window, while blood levels stayed low, an inversion of exposure that concentrates the drug at the lesion and spares the rest of the body. Serum chemistry and organ histology showed no treatment-related abnormalities.

The therapeutic results followed. Forty-eight hours after injury, rats receiving the medium and high doses of the CBD sponge scored significantly better on a standardized neurological deficit scale, traveled farther in open-field tests, and explored the open arms of an elevated plus maze more readily than injured controls, with mannitol and injected CBD providing comparable but generally weaker benefits. Under the microscope, the treated cortex retained orderly neuronal architecture and intact Nissl bodies, showed fewer TUNEL-positive apoptotic cells, and released lower levels of neuron-specific enolase and S-100 calcium-binding protein beta, two canonical markers of neural damage. The blank sponge alone conferred little benefit, indicating that sustained CBD release, not the scaffold itself, drove the protection.

Mechanistically, the study points to the blood-brain barrier and the water channel aquaporin-4. Treated rats had less brain water content and far less Evans blue dye leaking across the barrier, alongside restored expression of the tight junction proteins ZO-1, occludin, and claudin-5. Molecular docking predicted that CBD binds aquaporin-4 with a binding energy of minus 6.7 kilocalories per mole, and surface plasmon resonance confirmed a measurable micromolar interaction with a dissociation constant of 56.6 micromolar. After injury, aquaporin-4 shifted away from vascular endothelial structures and toward reactive, GFAP-positive astrocytes; the sponge reversed that redistribution, reduced astrocytic overactivation, and preserved endothelial markers. On the inflammatory front, the treatment lowered interleukin-6, interleukin-1 beta, and tumor necrosis factor-alpha, raised the anti-inflammatory interleukin-10, and calmed Iba-1-stained microglia. RNA sequencing of the injured cortex identified nearly 800 differentially expressed genes and pointed to dampened NF-kappaB and TNF signaling alongside enhanced PI3K-Akt survival signaling, changes the authors confirmed by Western blot and quantitative PCR.

The authors are careful about the limits of their work. The study captured only the acute, two-day phase, leaving long-term cognitive and behavioral recovery untested, and the local and injected CBD regimens were not matched for dose or exposure, so some benefits may reflect the delivery platform rather than the drug alone. No formal power calculation was performed, and the transcriptomic analysis omitted the blank-sponge and injected-CBD groups. Even so, the concept is compelling: a cheap, photocrosslinkable gelatin sponge that turns a one-shot drug depot into a 48-hour local infusion, right where edema and inflammation are born. If future studies with exposure-matched controls and longer follow-up bear out these results, the humble gelatin sponge could become a serious contender in the long-delayed search for the first true neuroprotective therapy for traumatic brain injury.

Subject of Research: Local delivery of cannabidiol using a GelMA hydrogel sponge to treat cerebral edema and neuroinflammation after traumatic brain injury

Article Title: In situ delivery of cannabidiol-loaded GelMA sponge attenuates cerebral edema and neuroinflammation in traumatic brain injury

Article References: Li, H., Luo, X., Cao, Y., Jiang, H., Guo, Z., Zhu, Y., Zhang, L., Li, Z., Li, J., Wu, H., & Li, P. (2026). In situ delivery of cannabidiol-loaded GelMA sponge attenuates cerebral edema and neuroinflammation in traumatic brain injury. Materials Today Bio, 41, Article 103721. https://doi.org/10.1016/j.mtbio.2026.103721

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103721

Keywords: traumatic brain injury, cannabidiol, GelMA hydrogel, drug delivery, cerebral edema, blood-brain barrier, neuroinflammation, aquaporin-4, microglia, NF-kappaB signaling, biomaterials, rat model

Perivascular spaces are, in healthy brains, almost invisible. They are the cuffs of cerebrospinal fluid that accompany penetrating arteries and veins into the brain’s substance, and in a typical newborn the amount of fluid within them is too small to register on clinical imaging. When these spaces balloon and multiply, however, they show up on T2-weighted magnetic resonance images as bright, linear or round dots, and on FLAIR sequences as dark counterparts of the same shapes. In adults, a heavy burden of enlarged perivascular spaces has been linked to cerebral small vessel disease, cognitive decline, and poor glymphatic clearance of toxic proteins. Until now, almost nothing was known about what these structures mean in the earliest days of life, particularly in babies whose brains have just endured the twin assaults of oxygen deprivation and the inflammatory firestorm that follows it.

The new study, published in the World Journal of Pediatrics, enrolled 319 newborns admitted to the hospital’s neonatology department between January 2020 and September 2023, all transferred within a week of birth. Using strict diagnostic criteria based on Apgar scores and umbilical artery blood gas analysis, the researchers divided the infants into a mild asphyxia group of 229 babies and a severe group of 90. Each child underwent brain magnetic resonance imaging on a 3.0 Tesla scanner, along with amplitude-integrated electroencephalography to capture the electrical rhythms of the injured cortex, and a battery of laboratory tests ranging from inflammatory markers to coagulation profiles. Two experienced radiologists, blinded to all clinical information, counted the enlarged perivascular spaces in the basal ganglia across four to six axial sections, producing a quantitative burden score for every infant.

The results were unambiguous. In the severe asphyxia group, lactate levels and C-reactive protein concentrations were significantly elevated compared with the mild group, and the number of enlarged perivascular spaces was also markedly higher. Across the whole cohort, the count of these spaces correlated positively with diastolic blood pressure and lactate, and negatively with Apgar scores at one, five, and ten minutes. More importantly, when the researchers built multivariable linear regression models to disentangle independent predictors, the number of enlarged perivascular spaces remained significantly associated with the severity of brain injury as graded on a simplified magnetic resonance score, with a P value of 0.0001 across all infants, 0.0248 in the mild group, and 0.0114 in the severe group. This held true even after accounting for gestational age, blood pressure, base excess, Apgar scores, and coagulation measures such as thrombin time and the international normalized ratio.

Intriguingly, the association was selective. The perivascular space count predicted the structural magnetic resonance score but not the amplitude-integrated electroencephalography grade, a measure of acute cortical electrical function. The authors interpret this dissociation as evidence that enlarged perivascular spaces capture structural, glymphatic damage rather than transient functional suppression. Electroencephalographic activity can be temporarily blunted by metabolic derangement and then recover, whereas the magnetic resonance image visualizes established injury to brain parenchyma. A marker of perivascular structural integrity, the researchers argue, aligns more naturally with the latter. This distinction matters clinically, because it suggests the marker adds a dimension of information that neither routine electrophysiology nor blood-based biomarkers of inflammation and neuronal injury can currently provide.

The mechanistic story behind the finding centers on the glymphatic system, the recently characterized network through which cerebrospinal fluid pulses along perivascular channels to flush metabolic waste from the brain, driven in part by the water channel protein aquaporin 4, which is polarized to the endfeet of astrocytes. Asphyxia triggers oxidative stress and a cytokine storm that disrupt this polarization, causing perivascular spaces to enlarge and glymphatic clearance to falter. The consequence may be self-reinforcing: as clearance fails, neurotoxic metabolites accumulate, further amplifying inflammation and astrocytic injury in a vicious cycle of progressive damage. The authors are careful to note that their observational design cannot establish causality; the enlarged spaces may actively contribute to injury or may simply be an epiphenomenon of the same upstream pathology. Either way, their count offers a non-invasive readout of a process that has been nearly impossible to monitor in living newborns.

Perhaps the most provocative result concerns sleep. Because mild asphyxial injury can damage the pineal gland, the source of melatonin, sleep disturbance has long been recognized as a sequela of perinatal asphyxia. The Suzhou team followed 258 of the 319 infants, using monthly parental questionnaires over six months, adapted from the Brief Infant Sleep Questionnaire and the Paediatric Sleep Questionnaire, to score seven sleep problems including prolonged sleep latency, insufficient sleep, irregular schedules, snoring, breathing difficulties, and frequent night wakings. After excluding age as a confounder by stratifying children into three age bands, the researchers found no relationship between perivascular space count and sleep in the full cohort or in the mild group. But in the severe asphyxia group, the correlation was significant: a higher number of enlarged perivascular spaces predicted more severe sleep disturbance, with a Spearman coefficient of 0.3365 and a P value of 0.0061.

That severity-specific pattern, the authors suggest, points to a mechanism beyond direct pineal injury. In severely asphyxiated infants, glymphatic damage may impede the clearance of toxic proteins, perpetuating brain injury and indirectly degrading sleep architecture, whereas in mild cases the perivascular spaces tend to shrink over time as the infant brain repairs itself, explaining the absence of a sleep correlation. The correlation is moderate rather than overwhelming, and the researchers acknowledge that infant sleep is multifactorial and cannot be reduced to a single biomarker. Still, the finding hints that a routine scan performed in the first week of life could flag babies at risk of sleep problems before parents notice anything wrong, opening a window for early behavioral and medical interventions during a period when sleep is critical to brain development.

The study has limitations that the authors confront directly. Ethical constraints precluded a healthy control group, though published data confirm that enlarged perivascular spaces are rare in healthy neonates, and the single-center design, moderate sample size, and reliance on parent-reported sleep questionnaires all warrant caution. The team calls for multicenter prospective cohorts incorporating diffusion tensor imaging along the perivascular space, an advanced technique that quantifies glymphatic flow directly, along with objective sleep monitoring and longitudinal follow-up. If those studies confirm the present findings, the humble perivascular space, long dismissed as an incidental dot on adult brain scans, could become a standard element of neonatal risk stratification, helping clinicians decide which asphyxiated newborns need the most aggressive neuroprotective care and which families should be counseled and monitored for the sleep disorders that may otherwise surface silently in the years after a difficult birth.

Subject of Research: Enlarged perivascular spaces as imaging biomarkers of perinatal asphyxia-induced brain injury and later sleep quality

Article Title: Correlation between perinatal asphyxia-induced brain injury, number of enlarged perivascular spaces, and sleep quality in later life

Article References: Correlation between perinatal asphyxia-induced brain injury, number of enlarged perivascular spaces, and sleep quality in later life. (n.d.). https://doi.org/10.1007/s12519-026-01093-8

Image Credits: AI Generated

DOI: 10.1007/s12519-026-01093-8

Keywords: perinatal asphyxia, enlarged perivascular spaces, glymphatic system, neonatal brain injury, MRI biomarker, sleep quality, hypoxic-ischemic encephalopathy, newborns, aquaporin 4, neonatology, amplitude-integrated EEG, World Journal of Pediatrics

For most of neuroscience history, the brain was considered an immune-privileged organ with no lymphatic drainage at all. That assumption posed a puzzle: the brain consumes 20 to 25 percent of the body’s total energy, generating mountains of metabolic byproducts, yet seemed to lack the lymphatic vessels every other organ relies on for waste removal. The answer began to emerge in 2012, when researcher Jeffrey Iliff and colleagues used fluorescent tracers in mice to show that cerebrospinal fluid flows deep into brain tissue along channels surrounding blood vessels, exchanges with the fluid bathing neurons, and exits through venous pathways. Because this process depends on aquaporin-4, a water channel protein concentrated on the ends of star-shaped astrocyte processes, the pathway was named the glymphatic system — a glial-dependent cousin of the lymphatic system.

The mechanics are elegant. Cerebrospinal fluid, produced by the choroid plexus in the brain’s ventricles, pulses along perivascular spaces driven by arterial pulsations from the heartbeat. At the same time, rhythmic breathing creates pressure changes that mechanically dilate these channels, acting as a second major pump. Aquaporin-4 channels on astrocyte endfeet, which sheath up to 98 percent of cerebral blood vessels, then shuttle the fluid into brain tissue, where it mixes with interstitial fluid and collects metabolic debris including amyloid-beta, tau, alpha-synuclein, and inflammatory cytokines. The waste-laden fluid drains back out along venous pathways, eventually reaching deep cervical lymph nodes in the neck and the peripheral lymphatic system.

In 2015, a second discovery completed the picture. Jonathan Kipnis’s laboratory identified functional lymphatic vessels lining the dural sinuses of the brain’s outer membrane — vessels that had been hiding in plain sight for centuries. These meningeal lymphatic vessels express classic lymphatic endothelial markers, transport cerebrospinal fluid and immune cells to deep cervical lymph nodes, and serve as a bridge between the brain’s immune surveillance and the body’s peripheral immune system. In 2019, researchers confirmed that vessels at the skull base are the primary route for clearing large molecules from cerebrospinal fluid, and by 2022, three-dimensional MRI had visualized these structures in living humans for the first time, revealing age-related thickening of the vessels and shrinkage of the lymph nodes they feed.

The connection to Alzheimer’s disease is now supported by converging evidence from animal models and human imaging. Mice engineered to lack aquaporin-4 show roughly a 70 percent reduction in interstitial solute clearance and accelerated amyloid accumulation. In human patients, diffusion tensor imaging along perivascular spaces — a technique that quantifies water movement in these channels — reveals reduced glymphatic function not only in established Alzheimer’s dementia but in prodromal and even preclinical stages, with the decline detectable before cerebrospinal fluid amyloid markers cross pathological thresholds. Postmortem studies show that loss of aquaporin-4’s polarized localization on astrocyte endfeet correlates specifically with Alzheimer’s status, amyloid burden, and advanced disease stages, independent of age.

Sleep emerges as perhaps the most potent modulator of this system. During deep non-REM sleep, the space between brain cells expands by roughly 60 percent, dramatically lowering resistance to fluid flow and boosting waste clearance. Interstitial amyloid-beta levels rise during wakefulness and fall during sleep, while sleep deprivation elevates tau levels by more than 50 percent in humans and accelerates pathological tau spread in animal models. Neuroimaging studies have captured coherent oscillations between neural slow waves, blood flow, and cerebrospinal fluid pulses during sleep — a physiological symphony that appears to choreograph the nightly brainwash. Obstructive sleep apnea, by disrupting the respiratory pressure gradients that help drive glymphatic flow, is associated with impaired clearance and accelerated dementia progression.

Neuroinflammation adds a vicious dimension to the story. When glymphatic clearance falters, pro-inflammatory cytokines accumulate in the brain, triggering overactivation of microglia, the brain’s resident immune cells. Activated microglia then release inflammatory mediators that further disrupt fluid transport, creating a self-amplifying loop. Meanwhile, perivascular macrophages that normally clear inflammatory debris from the drainage channels become overwhelmed, and astrocyte dysfunction compounds the problem. Periodontal infection by Porphyromonas gingivalis — increasingly recognized as an Alzheimer’s risk factor — may initiate this cascade by disturbing microglial circadian rhythms and sabotaging sleep-dependent clearance.

Translating these findings into therapies is now an intense research focus. On the pharmacological front, omega-3 polyunsaturated fatty acids accelerate amyloid clearance through aquaporin-4-dependent mechanisms, while the botanical extract L-3-n-butylphthalide enhances vascular pulsation to boost perivascular drainage. Noninvasive neuromodulation has produced striking preclinical results: 40-hertz gamma sensory stimulation promotes glymphatic amyloid clearance through vasoactive intestinal peptide neurons, repetitive transcranial magnetic stimulation restores aquaporin-4 polarization in Alzheimer’s mice, and 40-hertz transcranial vibration synchronizes human brain activity with cerebrospinal fluid flow. Focused ultrasound combined with microbubbles enhances soluble amyloid removal to cerebrospinal fluid and cervical lymph nodes, potentially synergizing with anti-amyloid antibodies.

The most provocative — and controversial — intervention is surgical. Deep cervical lymphatic-venous anastomosis, pioneered by Chinese microsurgeons, creates a bypass connecting neck lymphatic vessels directly to veins, theoretically relieving pressure in the cerebral waste drainage system. Performed through two small neck incisions, the procedure has reportedly improved cognition in preliminary cases, including an 84-year-old patient whose symptoms improved postoperatively. However, the review’s authors stress that evidence remains limited to isolated case reports without large controlled trials. Critical questions persist: which Alzheimer’s subgroups benefit, whether the surgery addresses underlying amyloid pathology or merely symptoms, and how to distinguish Alzheimer’s from idiopathic normal pressure hydrocephalus, a condition with overlapping pathology that complicates diagnosis.

The standard anti-amyloid drugs tell their own cautionary tale. Lecanemab and donanemab can reduce brain amyloid but carry risks of brain swelling and bleeding, particularly in APOE ε4 carriers, and their cognitive benefits remain modest. Anti-tau antibodies have fared worse, failing across multiple phase 2 trials. Against this backdrop, glymphatic-targeted strategies offer a fundamentally different logic: rather than attacking proteins directly, they aim to restore the brain’s intrinsic capacity to clear them. The review’s authors argue that this multi-target approach — addressing microcirculation, sleep dysfunction, and waste clearance simultaneously — matches the holistic intervention philosophy that neurodegenerative disease may ultimately demand. But they caution that the field remains in its early translational stage, with the molecular details of glymphatic dysfunction incompletely mapped and most candidate agents lacking specificity. Rigorous large-cohort clinical trials, standardized imaging assessment, and careful patient stratification will determine whether the brain’s drainage system can deliver on its extraordinary promise.

Subject of Research: The role of the glymphatic system and meningeal lymphatic vessels in Alzheimer's disease pathogenesis and therapy

Article Title: Novel Therapeutic Insights Into Alzheimer's Disease: Glymphatic System and Meningeal Lymphatic Vessels

Article References: Song, B., Wang, W., Liu, S., Jin, X., Qi, Y., Li, M., Yue, D., Liu, Y., Li, X., Yin, L., & Feng, L. (2026). Novel Therapeutic Insights Into Alzheimer's Disease: Glymphatic System and Meningeal Lymphatic Vessels. Aging Cell, 25(9), Article e70699. https://doi.org/10.1111/acel.70699

Image Credits: AI Generated

DOI: 10.1111/acel.70699

Keywords: Alzheimer's disease, glymphatic system, meningeal lymphatic vessels, aquaporin-4, amyloid-beta, tau protein, sleep, neuroinflammation, cerebrospinal fluid, deep cervical lymphaticovenous anastomosis, brain waste clearance, neurodegeneration

The difficulty of diagnosing drowning is well known in the forensic community. Unlike many causes of death, drowning leaves behind no pathognomonic autopsy feature, no single sign that definitively proves a person died from liquid entering the airways. Instead, forensic pathologists arrive at the diagnosis by exclusion, combining circumstantial evidence such as witnessed submersions or suicide notes with macroscopic findings like external foam, pleural effusion, acute pulmonary emphysema, and Paltauf’s spots, alongside histological and toxicological investigations. The World Health Organization estimates that approximately 372,000 drowning deaths occur worldwide each year, making it the third-leading cause of accidental injury death, so the stakes for improving diagnostic accuracy are considerable.

Pathophysiologically, drowning is divided into two principal forms depending on the medium. When a person drowns in fresh water, the hypotonic liquid passes rapidly into the pulmonary circulation, producing haemodilution, hyperkalaemia, and hypervolaemia, and death generally ensues faster than in salt water. In saltwater drowning, by contrast, the hypertonic sea water draws fluid from the bloodstream into the lungs, causing hypokalaemia, hypovolaemia, and haemoconcentration. These opposite haemodynamic trajectories were the central hypothesis of the new study: if freshwater and saltwater drowning drive the body’s water balance in opposite directions, the proteins that regulate water movement in brain cells might respond in measurably different ways.

The research team, led by Rosario Barranco and Francesco Ventura of the University of Genova together with Tony Fracasso of the Lausanne-Geneva center, conducted a retrospective analysis of ten freshwater drowning cases drawn from Lake Geneva and saltwater drowning cases from the Mediterranean Sea, using ten deaths from acute external bleeding as a control group. The exclusion criteria were deliberately strict: cases involving people over 65 years of age, neurological or psychiatric disease, cardiopulmonary resuscitation, putrefaction, a postmortem interval exceeding 72 hours, or ethanol and drug intoxication were all removed from consideration. Tissue samples were taken from the frontal cerebral cortex, fixed in formaldehyde, embedded in paraffin, and cut into five-micrometer sections for staining with antibodies against each of the five target proteins.

Slides were evaluated under blinded conditions, with seven randomly selected microscopic fields per slide scored on a semi-quantitative scale from absent to intense. Inter-observer agreement was complete for 85 percent of the slides and intra-observer agreement reached 95 percent, giving the investigators confidence in the reproducibility of their scoring. Statistical comparisons were performed with the Kruskal-Wallis and Mann-Whitney U tests for global comparisons between the three groups, supplemented by Student’s t-test, with significance set at p less than 0.05.

The headline result concerns aquaporin 4, the most abundant water channel protein in brain parenchyma, which is localized primarily in astrocytes and the basolateral membrane of the ependyma. Freshwater drowning cases showed a particularly intense AQP4 expression, with seven of the ten cases reaching the maximum grade of 3, and the difference between freshwater drowning and both the saltwater and control groups was statistically significant. By contrast, no significant difference emerged between saltwater drowning cases and controls. The authors interpret this as activation of AQP4 in response to the osmotic stimulus and haemodilution that occur when hypotonic fresh water floods the pulmonary circulation, a terminal vital reaction that helps the brain eliminate excess water through the subarachnoid spaces in cooperation with proteins such as connexin-43 and the potassium channel Kir4.1.

Aquaporin 9 delivered a second encouraging result. This channel, expressed in astrocytes, glial cells of the pineal gland, subpial vessels, and neurons, plays a role in regulating water movement, cerebrospinal fluid production, astrocyte migration, and neuronal energy balance. Intense AQP9 expression was found in four of the freshwater cases, and the difference between freshwater drowning and the other two groups was statistically significant with the t-test, while the global tests showed a trend in the same direction. The researchers propose that the hypotonic stimulus of freshwater immersion activates both AQP4 and AQP9 to counteract haemodilution, facilitating the transport of water and small solutes and supporting neuronal metabolic adaptations during the final minutes of life.

The remaining markers proved harder to interpret. Aquaporin 5, found mainly in neurons and astrocytes of the grey matter, and vasopressin, the hormone that stimulates aquaporin activity largely through the V1a receptor, both showed significantly higher expression in freshwater drowning cases than in controls, but no significant differences separated freshwater from saltwater drowning or saltwater from controls. The authors suggest that saltwater drowning may represent an intermediate situation between freshwater drowning and the control group, with osmotic alterations activating these proteins to a lesser extent, and they caution that vasopressin is subject to endocrine and temporal fluctuations that are not consistently reflected in postmortem immunohistochemical signals. Glial fibrillary acidic protein, a marker of glial reaction associated with traumatic or chronic lesions, showed no significant differences between groups, a result the team regarded as expected given that GFAP is not specific to acute osmotic change.

The study only partially confirms the influential earlier work of An and colleagues, who in 2011 demonstrated increased intracerebral aquaporin 4 expression in freshwater drowning but also reported reduced expression in saltwater drowning. The Genoa and Geneva team did not reproduce that decrease, finding no statistically significant difference between their saltwater group and controls, and they hypothesize that the discrepancy may relate to the different chemical and salinity characteristics of the Mediterranean Sea compared with the ocean. To their knowledge, the new study is the first to analyze the immunohistochemical expression of the major brain aquaporins alongside vasopressin in drowning cases, extending a line of research that the same group has previously pursued in lung and kidney tissue with markers including aquaporin 2, aquaporin 5, vasopressin receptor 2, and renin.

The practical implications reach beyond the laboratory. In maritime cities crossed by rivers, a drowning may occur in fresh water before currents drag the body out to sea, and establishing where the fatal immersion actually took place can matter for reconstructing the circumstances of death. The authors are careful to frame AQP4 and AQP9 as promising complementary markers for the differentiation of freshwater and saltwater drowning rather than as independent diagnostic markers, and they acknowledge that their strict exclusion criteria, while minimizing confounding variables, restricted the number of cases in each group. Validation on larger samples, they conclude, will be essential before these molecular signatures can enter routine forensic practice, but the study marks a significant step toward an objective, protein-level diagnosis of one of forensic medicine’s most stubborn diagnostic challenges.

Subject of Research: Immunohistochemical cerebral cortex expression of aquaporins, vasopressin, and GFAP in freshwater and saltwater drowning for forensic diagnosis.

Article Title: Immunohistochemical cerebral cortex expression of aquaporin 4, aquaporin 5, aquaporin 9 Vasopressin and GFAP in saltwater drowning and freshwater drowning

Article References: Barranco, R., Ventura, F., & Fracasso, T. (2026). Immunohistochemical cerebral cortex expression of aquaporin 4, aquaporin 5, aquaporin 9 Vasopressin and GFAP in saltwater drowning and freshwater drowning. International Journal of Legal Medicine. https://doi.org/10.1007/s00414-026-04021-7

Image Credits: AI Generated

DOI: 10.1007/s00414-026-04021-7

Keywords: drowning, freshwater drowning, saltwater drowning, aquaporin 4, aquaporin 9, vasopressin, GFAP, forensic pathology, immunohistochemistry, cerebral cortex, osmotic stimulus, forensic histopathology

NMOSD is a rare, autoimmune inflammatory disorder of the central nervous system that predominantly targets the optic nerves and spinal cord. In most patients, the disease is driven by pathogenic immunoglobulin G antibodies directed against aquaporin-4 (AQP4), a water channel protein abundantly expressed on astrocytes. Each relapse can leave permanent neurological damage, ranging from irreversible vision loss to paralysis, which is why suppressing the underlying B-cell–driven immune attack is the central goal of long-term management. Before targeted therapies earned regulatory approval, clinicians commonly prescribed oral immunosuppressants (ISTs) such as azathioprine, mycophenolate mofetil, and methotrexate off-label to keep the disease at bay.

Those older drugs have well-recognized shortcomings. Comparative studies have associated oral ISTs with a greater frequency of relapses and a shorter time to relapse after treatment initiation compared with approved monoclonal antibodies. They are also linked to gastrointestinal and hematologic side effects and a high frequency of infections, problems that accumulate over years of continuous use. Inebilizumab, by contrast, is a humanized, affinity-optimized, glycoengineered monoclonal antibody that targets CD19, a marker expressed broadly across the B-cell lineage, depleting the cells responsible for producing the pathogenic AQP4 antibodies. The randomized, placebo-controlled N-MOmentum trial demonstrated its efficacy in AQP4-seropositive NMOSD and led to regulatory approval.

A key question remained, however. Many participants entering N-MOmentum had years of prior IST exposure, and it was unclear whether that treatment history might blunt or otherwise alter the drug’s long-term efficacy and safety. To investigate, researchers analyzed 202 of the 213 AQP4-seropositive participants from the randomized controlled period (RCP) and 197 of the 201 from the open-label period (OLP), splitting them roughly evenly between those with prior IST treatment and those who were IST-naïve. Only ISTs taken before day 1 of the trial were considered; ISTs were prohibited once the trial began.

The randomized portion of the trial delivered an unambiguous message. Participants on inebilizumab experienced far fewer adjudicated NMOSD attacks than those on placebo, and the magnitude of benefit was essentially identical in both subgroups. Among participants with prior IST use, the hazard ratio for attack was 0.21 (95% confidence interval 0.09–0.48), while among IST-naïve participants it was 0.23 (0.09–0.59). NMOSD-related inpatient hospitalizations were also less frequent with inebilizumab in the prior-IST group. Worsening on the Expanded Disability Status Scale (EDSS) was significantly less common with inebilizumab versus placebo in both groups: 19.2% versus 43.5% among those with prior IST exposure, and 13.6% versus 28.0% among those who were IST-naïve, both comparisons reaching nominal statistical significance.

Because the randomized controlled period lasted only about 28 weeks, the research team turned to modeling to assess long-term outcomes over years rather than months. In the any-INEB population, the adjusted annualized attack rate was 0.11 (0.07–0.17) for participants with prior IST use and 0.08 (0.05–0.14) for those without, a difference so small it is unlikely to matter clinically. A high probability of remaining attack-free persisted through week 286 of treatment in both groups, and EDSS scores actually improved during the open-label extension regardless of treatment history. NMOSD-related hospitalizations were equal in number across the two subgroups during long-term follow-up.

The most striking results emerged when inebilizumab was compared against synthetic historical comparator groups built from published Kaplan–Meier survival curves of patients treated with azathioprine or other broad-spectrum ISTs, or with placebo. Using a time-varying spline model with two internal knots, selected through formal information-criterion testing and visual fit assessment, the researchers found the time to NMOSD attack was significantly longer with inebilizumab than with azathioprine or other ISTs (hazard ratio 0.29; p < 0.001) and than with placebo (hazard ratio 0.15; p < 0.001). The modeled four-year attack-free probability was 77% for inebilizumab, 36% for azathioprine or other ISTs, and just 12% for placebo. Notably, the widening gap over time suggests inebilizumab’s relative advantage may grow the longer patients stay on treatment.

Safety outcomes were reassuringly similar across subgroups. Through the open-label period, roughly 92% of participants in both groups experienced at least one treatment-emergent adverse event, but drug-related events were somewhat more common among IST-naïve participants, 46.6% versus 30.9%. Infections, the adverse event category of greatest concern for a B-cell–depleting therapy, occurred at nearly identical rates in both groups, affecting 72.3% of those with prior IST use and 76.7% of those without, and were not increased by prior immunosuppressant exposure. Opportunistic infections were rare, one case in each group, no anaphylactic reactions were reported, and deaths were similarly uncommon.

The authors caution that this was a post hoc, exploratory analysis with limitations. Subgroup sample sizes were modest, randomization was not stratified by duration of IST history, and p values were not adjusted for multiple comparisons, so all statistical results are nominal. The synthetic historical comparators, reconstructed by digitizing published survival curves, introduce approximation error and cannot fully control for differences in study populations and designs across the source studies. These constraints mean the long-term comparative estimates should be interpreted as suggestive rather than definitive evidence from head-to-head trials, which have never been conducted.

Even so, the practical implications for patients and clinicians are substantial. Switching from off-label immunosuppressants to immunotherapies generally requires an overlapping treatment period to avoid triggering an attack upon discontinuation of the old drug, and many providers overlap ISTs for up to six months, although concurrent inebilizumab and IST use is not recommended as a routine regimen. The new analysis supports inebilizumab treatment for patients with AQP4-seropositive NMOSD regardless of whether they previously received first-line immunosuppressants, with sustained reductions in attack risk, stabilized or improved disability scores, and a safety profile consistent with the overall trial population. For the many patients still managed with older oral agents, the data offer a quantitative basis for a confident transition to targeted B-cell depletion.

Subject of Research: Long-term efficacy and safety of inebilizumab in AQP4-seropositive NMOSD patients with or without prior immunosuppressant use

Article Title: Efficacy of Inebilizumab in N‐MOmentum Trial Participants With or Without Prior Immunosuppressants

Article References: Cree, B. A. C., Suero, B., Walsh, S., Marignier, R., Lindsey, J. W., Kim, H. J., She, D., Cimbora, D., Cavida, D., & Paul, F. (2026). Efficacy of Inebilizumab in N‐ MOmentum Trial Participants With or Without Prior Immunosuppressants. Annals of Clinical and Translational Neurology, 13(9), 1930-1936. https://doi.org/10.1002/acn3.70426

Image Credits: AI Generated

DOI: 10.1002/acn3.70426

Keywords: inebilizumab, NMOSD, N-MOmentum trial, aquaporin-4, CD19 B-cell depletion, azathioprine, mycophenolate mofetil, immunosuppressants, clinical trial, neuroimmunology, EDSS, autoimmune disease