Glial Fibrillary Acidic Protein Research Articles

Diagnostic value of six plasma biomarkers in progressive supranuclear palsy, multiple system atrophy, and Parkinson’s disease

ObjectivesThis study aimed to evaluate the diagnostic ability of six plasma biomarkers in progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and different subtypes of Parkinson’s disease (PD). MethodsNeurofilament light chain (NfL), phosphorylated tau-181, glial fibrillary acidic protein (GFAP), amyloid-β 42 (Aβ42), and amyloid-β 40 (Aβ40) levels were measured using the single-molecule array (Simoa) technique in a cohort of patients with PSP, MSA, different subtypes of PD, and healthy controls (HCs). ResultsPlasma NfL and GFAP levels were beneficial in discriminating between the disease groups and HCs. Plasma NfL, Aβ42, and Aβ40 could distinguish atypical Parkinsonian syndrome (APS) from PD and its subtypes. GFAP could discriminate APS from tremor dominant PD but could not discriminate APS from postural instability and gait disorder dominant PD. The efficacy of differentiation improved when a combination of multiple plasma biomarkers was applied. ConclusionsIn this study, the plasma biomarkers NfL, GFAP, Aβ42, and Aβ40 exhibited high discriminatory diagnostic value in PD and APS, and could be used as clinically potential diagnostic biomarkers. Plasma biomarker combinations could improve the differential diagnostic efficacy in the comparisons of PD and APS.

Infusion of sodium DL-3-ß-hydroxybutyrate decreases cerebral injury biomarkers after resuscitation in experimental cardiac arrest

AimsCerebral complications after cardiac arrest (CA) remain a major problem worldwide. The aim was to test the effects of sodium-ß-hydroxybutyrate (SBHB) infusion on brain injury in a clinically relevant swine model of CA.ResultsCA was electrically induced in 20 adult swine. After 10 min, cardiopulmonary resuscitation was performed for 5 min. After return of spontaneous circulation (ROSC), the animals were randomly assigned to receive an infusion of balanced crystalloid (controls, n = 11) or SBHB (theoretical osmolarity 1189 mOsm/l, n = 8) for 12 h. Multimodal neurological and cardiovascular monitoring were implemented in all animals. Nineteen of the 20 animals achieved ROSC. Blood sodium concentrations, osmolarity and circulating KBs were higher in the treated animals than in the controls. SBHB infusion was associated with significantly lower plasma biomarkers of brain injury at 6 (glial fibrillary acid protein, GFAP and neuron specific enolase, NSE) and 12 h (neurofilament light chain, NFL, GFAP and NSE) compared to controls. The amplitude of the stereoelectroencephalograph (sEEG) increased in treated animals after ROSC compared to controls. Cerebral glucose uptake was lower in treated animals.ConclusionsIn this experimental model, SBHB infusion after resuscitated CA was associated with reduced circulating markers of cerebral injury and increased sEEG amplitude.

Cardiovascular and kidney diseases are positively associated with neuroinflammation and reduced brain-derived neurotrophic factor in patients with severe COVID-19

Even though respiratory dysfunctions are the primary symptom associated with SARS-CoV-2 infection, cerebrovascular events, and neurological symptoms are described in many patients. However, the connection between the neuroimmune profile and the lung's inflammatory condition during COVID-19 and its association with the neurological symptoms reported by COVID-19 patients still needs further exploration. The present study characterizes the SARS-CoV-2 infectivity profile in postmortem nervous and lung tissue samples of patients who died due to severe COVID-19, and the pro-inflammatory factors present in both nervous and lung tissue samples, via a proteomic profiling array. Additionally, Brain-Derived Neurotrophic Factor (BDNF) levels and intracellular pathways related to neuroplasticity/neuroprotection were assessed in the samples. Out of the 16 samples analyzed, all samples but 1 were positive for the viral genome (genes E or N2, but only 3.9% presented E and N2) in the olfactory brain pathway. The E or N2 gene were also detected in all lung samples, with 43.7% of the samples being positive for the E and N2 genes. In the E/N2 positive brain samples, the Spike protein of SARS-CoV-2 co-localized with TUJ-1+ (neuron-specific class III beta-tubulin) and GFAP+ (glial fibrillary acidic protein) astrocytes. IL-6, but not IL-10, expression was markedly higher in most nervous tissue samples compared to the lung specimens. While intracellular adhesion molecule-1 (ICAM-1), interleukin-8 (IL-8), macrophage migration inhibitory factor (MIF), and plasminogen activator inhibitor 1 (PAI-1) were increased in lung samples from SARS-Cov-2 patients, only MIF and IL-18 were detected in nervous tissue samples. Correlation analysis suggested that high levels of IL-6 are followed by increased levels of IL-10 in the brain, but not in lung samples. Our analysis also demonstrated that the presence of comorbidities, such as cardiovascular disease, hypertension, and hypothyroidism, is associated with neuroinflammation, while chronic kidney conditions predict the presence of neurological symptoms, which correlate with lower levels of BDNF in the brain samples. Our results corroborate the hypothesis that a pro-inflammatory state might further impair neural homeostasis and induce brain abnormalities found in COVID-19 patients.

Caregiving-Related Depression Increases Neuroinflammation in Spousal Caregivers to Individuals with Cognitive Impairment: A Longitudinal Study

Abstract Background The caregiving burden of the spousal caregivers (SCGs) to individuals with cognitive impairment poses public health challenges with adverse psychosocial and physiological effects. However, few studies have investigated the neurobiological impact of caregiving, particularly through the investigation of neuroinflammation and neurodegeneration. Methods Using data from a longitudinal cohort at Chungnam National University Hospital, the relationship between caregiving burden, neuroinflammation and neurodegeneration was examined in 38 older adult couples over a 16-month period. Caregiving burden was assessed through a multifaceted approach. For factors related to the care recipient, we assessed cognitive function and neuropsychiatric symptoms. Factors regarding the SCGs included the measurement of perceived depression. Glial fibrillary acidic protein (GFAP) was used as a plasma biomarker for neuroinflammation and neurofilament light chain (NfL) for neurodegeneration. Regression analyses were adjusted for age, sex, apolipoprotein E status, follow-up interval, vascular risk factors, and physical activity. Results Changes in depression among SCGs were significantly correlated with increased GFAP levels (p = 0.003), indicating that greater depressive symptoms during caregiving are associated with increased neuroinflammation. In contrast, no significant correlations were found between changes in cognitive function or neuropsychiatric symptoms in care recipients and the plasma biomarker levels of SCGs. Additionally, there was no significant association between changes in depression and NfL levels in SCGs. Conclusions The psychological stress experienced by SCGs while caring for partners with cognitive impairment actively contributes to neuroinflammation, a well-known risk factor for various diseases. This study emphasizes the need to address psychological stress experienced by older adult caregivers.

Investigating the influence of estrous cycle-dependent hormonal changes on neurogenesis in adult mice

ObjectiveNeurogenesis is the process of generating new neurons from neural stem cells (NSCs) in the adult brain. Sex hormones play an essential role in the development of the brain. The aim of this study was to evaluate the neurogenic changes in the brain at different phases of the estrous cycle in adult mice. Materials and methodsFemale NMRI mice were divided into four groups: 1- Estrous, 2- Proestrous, 3- Metestrous, and 4- Diestrous. Different stages of the estrous cycle were determined by staining of vaginal smears. The level of estrogen, progesterone, prolactin, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) hormones was evaluated by the enzyme-linked immunosorbent assay (ELISA) method. The expression of brain-derived neurotrophic factor) BDNF), nerve growth factor (NGF), ciliary neurotrophic factor(CNTF)) genes in hippocampal and the expression of glial fibrillary acidic protein (GFAP) in subventricular zone (SVZ) tissue were evaluated. ResultsThe serum estrogen and FSH increased significantly in Proestrous group (p < 0.001). Also, progesterone and prolactin hormones were significantly increased in the Diaestrus group (p < 0.001). The expression levels of BDNF, NGF, and CNTF significantly increased in the hippocampal tissue of Proestrous and Diaestrus groups (p < 0.001). The number of GFAP+ cells in SVZ of the Proestrous and Diestrous groups had a significant increase (p < 0.05, p < 0.01, p < 0.001). ConclusionOur data showed that Changes in sex hormones, especially estrogen in the estrous cycle, can cause the production of new neurons and astrocytes in the hippocampus and SVZ. Therefore, the increase in neurotrophic factors in the Proestrus and Diestrus leads to neurogenesis in adult mice brains.

Development, External Validation, and Biomolecular Corroboration of Interoperable Models for Identifying Critically Ill Children at Risk of Neurologic Morbidity.

Declining mortality in the field of pediatric critical care medicine has shifted practicing clinicians' attention to preserving patients' neurodevelopmental potential as a main objective. Earlier identification of critically ill children at risk for incurring neurologic morbidity would facilitate heightened surveillance that could lead to timelier clinical detection, earlier interventions, and preserved neurodevelopmental trajectory. Develop machine-learning models for identifying acquired neurologic morbidity while hospitalized with critical illness and assess correlation with contemporary serum-based, brain injury-derived biomarkers. Retrospective cohort study. Two large, quaternary children's hospitals. Critical illness. The outcome was neurologic morbidity, defined according to a computable, composite definition at the development site or an order for neurocritical care consultation at the validation site. Models were developed using varying time windows for temporal feature engineering and varying censored time horizons prior to identified neurologic morbidity. Optimal models were selected based on F1 scores, cohort sizes, calibration, and data availability for eventual deployment. A generalizable created at the development site was assessed at an external validation site and optimized with spline recalibration. Correlation was assessed between development site model predictions and measurements of brain biomarkers from a convenience cohort. After exclusions there were 14,222-25,171 encounters from 2010-2022 in the development site cohorts and 6,280-6,373 from 2018-2021 in the validation site cohort. At the development site, an extreme gradient boosted model (XGBoost) with a 12-hour time horizon and 48-hour feature engineering window had an F1-score of 0.54, area under the receiver operating characteristics curve (AUROC) of 0.82, and a number needed to alert (NNA) of 2. A generalizable XGBoost model with a 24-hour time horizon and 48-hour feature engineering window demonstrated an F1-score of 0.37, AUROC of 0.81, AUPRC of 0.51, and NNA of 4 at the validation site. After recalibration at the validation site, the Brier score was 0.04. Serum levels of the brain injury biomarker glial fibrillary acidic protein measurements significantly correlated with model output (r s =0.34; P =0.007). We demonstrate a well-performing ensemble of models for predicting neurologic morbidity in children with biomolecular corroboration. Prospective assessment and refinement of biomarker-coupled risk models in pediatric critical illness is warranted. Question Can interoperable models for predicting neurological deterioration in critically ill children be developed, correlated with serum-based brain-derived biomarkers, and validated at an external site? Findings A development site model demonstrated an area under the receiver operating characteristics curve (AUROC) of 0.82 and a number needed to alert (NNA) of 2. Predictions correlated with levels of glial fibrillary acidic protein in a subset of children. A generalizable model demonstrated an AUROC of 0.81 and NNA of 4 at the validation site. Meaning Well performing prediction models coupled with brain biomarkers may help to identify critically ill children at risk for acquired neurological morbidity.

Extract from Nasco pomace loaded in nutriosomes exerts anti-inflammatory effects in the MPTP mouse model of Parkinson's disease

Neuroinflammation has recently emerged as a key event in Parkinson's disease (PD) pathophysiology and as a potential target for disease-modifying therapies. Plant-derived extracts, rich in bioactive phytochemicals with antioxidant properties, have shown potential in this regard. Yet their clinical utility is hampered by poor systemic availability and rapid metabolism. Recently, our group demonstrated that intragastric delivery of Nasco pomace extract via nutriosomes (NN), a novel nanoliposome formulation, contrasts the degeneration of nigrostriatal dopaminergic neurons in a subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. In the present study, we investigated the impact of intragastric NN treatment on the reactivity of glial cells in the substantia nigra pars compacta (SNc) and caudate-putamen (CPu) of MPTP-treated mice. To this scope, in mice exposed to MPTP (20 mg/kg/day, × 4 days), we conducted immunohistochemistry analyses of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (IBA1) to assess the responsiveness of astrocytes and microglial cells, respectively. Additionally, we studied the co-localization of the pro-inflammatory interleukin (IL)-1β and tumor necrosis factor (TNF)-α with IBA1 to obtain insights into microglial phenotype. Immunohistochemical results showed that NN administration significantly mitigated astrogliosis and microgliosis in the CPu and SNc of mice receiving subacute MPTP treatment, with region-specific variations in anti-inflammatory efficacy. Remarkably, the CPu showed a heightened response to NN treatment, including a pronounced decrease in microglial IL-1β and TNF-α production. Altogether, these findings underscore the anti-inflammatory effects of NN treatment and provide a potential mechanism underlying the neuroprotective effects previously observed in a subacute MPTP mouse model of PD.

The GFAP proteoform puzzle: How to advance GFAP as a fluid biomarker in neurological diseases.

Glial fibrillary acidic protein (GFAP) is a well-established biomarker of reactive astrogliosis in the central nervous system because of its elevated levels following brain injury and various neurological disorders. The advent of ultra-sensitive methods for measuring low-abundant proteins has significantly enhanced our understanding of GFAP levels in the serum or plasma of patients with diverse neurological diseases. Clinical studies have demonstrated that GFAP holds promise both as a diagnostic and prognostic biomarker, including but not limited to individuals with Alzheimer's disease. GFAP exhibits diverse forms and structures, herein referred to as its proteoform complexity, encompassing conformational dynamics, isoforms and post-translational modifications (PTMs). In this review, we explore how the proteoform complexity of GFAP influences its detection, which may affect the differential diagnostic performance of GFAP in different biological fluids and can provide valuable insights into underlying biological processes. Additionally, proteoforms are often disease-specific, and our review provides suggestions and highlights areas to focus on for the development of new assays for measuring GFAP, including isoforms, PTMs, discharge mechanisms, breakdown products, higher-order species and interacting partners. By addressing the knowledge gaps highlighted in this review, we aim to support the clinical translation and interpretation of GFAP in both CSF and blood and the development of reliable, reproducible and specific prognostic and diagnostic tests. To enhance disease pathology comprehension and optimise GFAP as a biomarker, a thorough understanding of detected proteoforms in biofluids is essential.

Plasma markers of neurodegeneration, latent cognitive abilities and physical activity in healthy aging

Blood-based biomarkers of neurodegeneration demonstrate great promise for the diagnosis and prognosis of Alzheimer’s disease. Ultra-sensitive plasma assays now allow for quantification of the lower concentrations in cognitively unimpaired older adults, making it possible to investigate whether these markers can provide insight also into the early neurodegenerative processes that affect cognitive function and whether the markers are influenced by modifiable risk factors. Adopting an exploratory approach in 93 healthy older adults (65–75 years), we used structural equation modelling to investigate cross-sectional associations between multiple latent cognitive abilities (working memory, episodic memory, spatial and verbal reasoning) and plasma amyloid beta (Aβ42/Aβ40 ratio), phosphorylated-tau 181 (ptau-181), glial fibrillary acidic protein (GFAP), and neurofilament light (NfL), as well as the influence of device-measured habitual physical activity on these associations. The results showed that NfL was negatively associated with working memory, and that NfL interacted with moderate-to-vigorous physical activity in its association with episodic memory. The study has thereby demonstrated the potential of neurodegenerative plasma markers for improving understanding of normative cognitive aging and encourages future research to test the hypothesis that high levels of NfL, indicative of white matter pathology, limit the beneficial effect of physical activity on episodic memory in healthy aging.

Multifaceted neuroprotective approach of Trolox in Alzheimer's disease mouse model: targeting Aβ pathology, neuroinflammation, oxidative stress, and synaptic dysfunction.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder pathologically characterized by the deposition of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain. The accumulation of these aggregated proteins causes memory and synaptic dysfunction, neuroinflammation, and oxidative stress. This research study is significant as it aims to assess the neuroprotective properties of vitamin E (VE) analog Trolox in an Aβ1 - 42-induced AD mouse model. Aβ1 - 42 5μL/5min/mouse was injected intracerebroventricularly (i.c.v.) into wild-type adult mice brain to induce AD-like neurotoxicity. For biochemical analysis, Western blotting and confocal microscopy were performed. Remarkably, intraperitoneal (i.p.) treatment of Trolox (30 mg/kg/mouse for 2 weeks) reduced the AD pathology by reducing the expression of Aβ, phosphorylated tau (p-tau), and β-site amyloid precursor protein cleaving enzyme1 (BACE1) in both cortex and hippocampus regions of mice brain. Furthermore, Trolox-treatment decreased neuroinflammation by inhibiting Toll-like receptor 4 (TLR4), phosphorylated nuclear factor-κB (pNF-κB) and interleukin-1β (IL-1β), and other inflammatory biomarkers of glial cells [ionized calcium-binding adaptor molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP)]. Moreover, Trolox reduced oxidative stress by enhancing the expression of nuclear factor erythroid-related factor 2 (NRF2) and heme oxygenase 1 (HO1). Similarly, Trolox-induced synaptic markers, including synaptosomal associated protein 23 (SNAP23), synaptophysin (SYN), and post-synaptic density protein 95 (PSD-95), and memory functions in AD mice. Our findings could provide a useful and novel strategy for investigating new medications to treat AD-associated neurodegenerative diseases.

Early prognostic factors in acute inflammatory demyelinating polyneuropathy: Role of neurofilaments

IntroductionGuillain-Barré syndrome (GBS) is an autoimmune disease that results in demyelination and axonal damage. Although the recovery is good in most patients, 20% remain significantly disabled.Neurofilament light chain (NfL) has been established as a biomarker of axonal damage in many diseases. MethodsWe measured NfL, S100B, and glial fibrillary acidic protein (GFAP) concentrations from blood and cerebrospinal fluid (CSF) taken upon admission from 19 patients with a history of GBS between January 2009 and December 2019 and investigated a correlation between them and clinical outcomes. ResultsAll patients fulfilled levels 1 or 2 of the Brighton diagnostic.Preceding infection was reported in 11 cases (58%).We classified 15 patients as acute inflammatory demyelinating polyneuropathy, 2 as AMAN, 1 as AMSAN, and 2 cases as Miller–Fisher syndrome.Five patients were transferred to an ICU, with a mean stay of 13 days. Functional outcome at 6 months after discharge was good in 12 patients (70.6%).We evaluated disease prognosis using the modified Erasmus GBS outcome score. The correlation was significant (p<.05) in the case of NfL in serum and CSF and GFAP in CSF (r=0.472 for serum NfL, 0.576 for CSF NfL, and 0.544 for CSF GFAP). ConclusionsWe confirm the finding of elevated levels of NfL, GFAP, and S100B in CSF and plasma in the acute phase of GBS.We can point out that their value has a certain relationship with the severity of the disease and prognosis, and that in some way, they have an influence, but we would lack more information to make good predictions.

In vivo evidence of increased vascular endothelial growth factor in patients with major depressive disorder

BackgroundVascular endothelial growth factor (VEGF) is a candidate mediator of blood-brain barrier (BBB) disruption in depression. However, previous studies have mainly focused on peripheral blood VEGF levels, and the results are heterogeneous. Here we use astrocyte-derived extracellular vesicles (ADEVs) isolated from plasma to explore the in vivo changes of VEGF levels in patients with major depressive disorder (MDD). MethodsThirty-five unmedicated patients with MDD and 35 healthy controls (HCs) were enrolled, and plasma ADEVs were isolated from each participant. VEGF levels in ADEVs and glial fibrillary acidic protein (GFAP) in plasma were measured. Additionally, Alix and CD81, two established extracellular vesicle markers, were quantified in ADEVs. ResultsAt baseline, MDD patients exhibited significantly increased levels of VEGF in ADEVs and GFAP in plasma. Following four weeks of selective serotonin reuptake inhibitor treatment, these target protein levels did not significantly change. ROC curve analysis revealed an AUC of 0.711 for VEGF in ADEVs. In exploratory analysis, VEGF levels in ADEVs were positively correlated with Alix and CD81. LimitationsMultiple factors regulate BBB permeability. This study focused solely on VEGF and the sample size for longitudinal analysis was relatively small. ConclusionOur study is the first to confirm increased ADEV-derived VEGF levels in patients with MDD, thereby providing preliminary evidence supporting the hypothesis that the BBB is disrupted in depression.

P-tau217 and other blood biomarkers of dementia: variation with time of day

Plasma biomarkers of dementia, including phosphorylated tau (p-tau217), offer promise as tools for diagnosis, stratification for clinical trials, monitoring disease progression, and assessing the success of interventions in those living with Alzheimer’s disease. However, currently, it is unknown whether these dementia biomarker levels vary with the time of day, which could have implications for their clinical value. In two protocols, we studied 38 participants (70.8 ± 7.6 years; mean ± SD) in a 27-h laboratory protocol with either two samples taken 12 h apart or 3-hourly blood sampling for 24 h in the presence of a sleep–wake cycle. The study population comprised people living with mild Alzheimer’s disease (PLWA, n = 8), partners/caregivers of PLWA (n = 6) and cognitively intact older adults (n = 24). Single-molecule array technology was used to measure phosphorylated tau (p-tau217) (ALZpath), amyloid-beta 40 (Aβ40), amyloid-beta 42 (Aβ42), glial fibrillary acidic protein, and neurofilament light (NfL) (Neuro 4-Plex E). Analysis with a linear mixed model (SAS, PROC MIXED) revealed a significant effect of time of day for p-tau217, Aβ40, Aβ42, and NfL, and a significant effect of participant group for p-tau217. For p-tau217, the lowest levels were observed in the morning upon waking and the highest values in the afternoon/early evening. The magnitude of the diurnal variation for p-tau217 was similar to the reported increase in p-tau217 over one year in amyloid-β-positive mild cognitively impaired people. Currently, the factors driving this diurnal variation are unknown and could be related to sleep, circadian mechanisms, activity, posture, or meals. Overall, this work implies that the time of day of sample collection may be relevant in the implementation and interpretation of plasma biomarkers in dementia research and care.

Elevated cerebrospinal fluid neuronal injury biomarkers within 24 hours of onset in infection-triggered acute encephalopathy compared to complex febrile seizures

ObjectiveThis study aimed to measure and compare cerebrospinal fluid neuronal injury biomarkers in the acute phase of complex febrile seizure (CFS) and infection-triggered acute encephalopathy (AE). Furthermore, we determined the pathogenesis of AE with biphasic seizures and late reduced diffusion (AESD). MethodsPediatric patients with febrile status epilepticus who visited Hyogo Prefectural Kobe Children's Hospital from November 1, 2016, to December 31, 2022, and whose cerebrospinal fluid samples were collected within 24 h of neurological symptom onset were included. Patients were classified as having CFS or infection-triggered AE according to their definitions. Patients with AE were further categorized into AESD or unclassified AE. Cerebrospinal fluid biomarkers (neuron-specific enolase, growth differentiation factor 15 [GDF-15], S100 calcium-binding protein B [S100B], glial fibrillary acidic protein, and tau protein were measured and compared among the groups. ResultsTotal of 63 patients (45 with CFS and 18 with AE) were included. Among the AE patients, nine were classified as having AESD and nine as having unclassified AE. S100B levels were significantly higher in patients with AESD than in patients with CFS (485 pg/ml vs. 175.3 pg/ml) and were even higher in patients with AESD and neurological sequelae (702.4 pg/ml). GDF-15 levels were significantly elevated in patients with AE compared to patients with CFS (85.8 pg/ml vs. 23.6 pg/ml). ConclusionsThe elevation of S100B suggests that activated astrocytes may be closely associated with the early pathology of AESD. Elevated GDF-15 levels in infection-triggered AE suggest the activation of defense mechanisms caused by stronger neurological injury.

Effects of Sildenafil on Cognitive Function Recovery and Neuronal Cell Death Protection after Transient Global Cerebral Ischemia in Gerbils.

Cerebral ischemic stroke is a major cause of death worldwide due to brain cell death resulting from ischemia-reperfusion injury. However, effective treatment approaches for patients with ischemic stroke are still lacking in clinical practice. This study investigated the potential neuroprotective effects of sildenafil, a phosphodiesterase-5 inhibitor, in a gerbil model of global brain ischemia. We investigated the effects of sildenafil on the expression of glial fibrillary acidic protein and aquaporin-4, which are markers related to astrocyte activation and water homeostasis, respectively. Immunofluorescence analysis showed that the number of cells co-expressing these markers, which was elevated in the ischemia-induced group, was significantly reduced in the sildenafil-treated groups. This suggests that sildenafil may have a potential mitigating effect on astrocyte activation induced by ischemia. Additionally, we performed various behavioral tests, including the open-field test, novel object recognition, Barnes maze, Y-maze, and passive avoidance tests, to evaluate sildenafil's effect on cognitive function impaired by ischemia. Overall, the results suggest that sildenafil may serve as a neuroprotective agent, potentially alleviating delayed neuronal cell death and improving cognitive function impaired by ischemia.

Development of Tissue-Engineered Model of Fibrotic Scarring after Spinal Cord Injury to Study Astrocyte Activation and Neurite Outgrowth In Vitro.

Traumatic spinal cord injuries (SCI) are debilitating injuries affecting twenty-seven million people worldwide and cause functional impairments. Despite decades of research and medical advancements, current treatment options for SCI remain limited, in part due to the complex pathophysiology of spinal cord lesions including cellular transformation and extracellular matrix (ECM) remodeling. Recent studies have increased focus on fibrotic scarring after SCI, and yet much remains unclear about the impact of fibrotic scarring on SCI lesion progression. Here, using collagen and decellularized spinal cord-based composite hydrogels, a three-dimensional (3D) cell culture model mimicking the fibrous core of spinal cord lesions was implemented to investigate its influence on the surrounding astrocytes. To mimic the fibrotic milieu, collagen fibril thickness was tuned using previously established temperature-controlled casting methods. In our platforms, astrocytes in fibro-mimetic hydrogels exhibited increased levels of activation markers such as glial fibrillary acidic protein and N-cadherin. Furthermore, astrocytes in fibro-mimetic hydrogels deposited more fibronectin and laminin, further hinting that astrocytes may also contribute to fibrotic scarring. These markers were decreased when Rho-ROCK and integrin β1 were inhibited via pharmacological inhibitors. Mechanistic analysis of Yes-associated protein reveals that blocking integrin β1 prevents mechanosensing of astrocytes, contributing to altered phenotypes in variable culture conditions. In the presence of these inhibitors, astrocytes increased the secretion of brain-derived neurotrophic factor, and a greater degree of dorsal root ganglia neurite infiltration into the underlying hydrogels was observed. Altogether, this study presents a novel tissue-engineered platform to study fibrotic scarring after SCI and may be a useful platform to advance our understanding of SCI lesion aggravation.

Gap junction protein connexin 43 and its distribution in damaged nerve cells

BACKGROUND: Connexins, particularly connexin 43, form gap junctions that mediate neuron-glial communication. To date, the expression of connexin 43 in phenotypically distinct neurolemmocytes, in particular non-myelinating (Remak cells) and repair Schwann cells, has not been studied. AIM: To determine the presence of connexin 43 in Schwann cells of the rat sciatic nerve under normal conditions and after mechanical damage by applying a ligature. MATERIALS AND METHODS: The study was carried out on Wistar rats (n = 10). In experimental rats, the sciatic nerve was damaged by applying a ligature (40 s). 7 days after surgery, sciatic nerve segments were isolated for subsequent immunohistochemical study using antibodies to connexin 43 and glial fibrillary acidic protein (GFAP). In the control group rats, segments of intact sciatic nerves were isolated in a similar way. RESULTS: It has been shown that in the endoneurium of the intact rat sciatic nerve there are no cells expressing connexin 43. It was found that 7 days after injury, a large number of connexin-43-immunopositive cells of irregular shape with several processes were identified in the endoneurium of the damaged nerve. There was a lack of expression of connexin 43 in GFAP-containing Schwann cells. CONCLUSIONS: It can be stated that nerve damage leads to active synthesis of the studied protein by endoneurium cells; however, the origin of the cells expressing connexin 43 remains to be elucidated.

From Nature to Treatment: The Impact of Pterostilbene on Mitigating Retinal Ischemia-Reperfusion Damage by Reducing Oxidative Stress, Inflammation, and Apoptosis.

Retinal ischemia-reperfusion (I/R) injury is a critical pathogenic mechanism in various eye diseases, and an effective therapeutic strategy remains unresolved. Natural derivatives have recently reemerged; therefore, in our present study, we examined the potential therapeutic effects of a stilbenoid that is chemically related to resveratrol. Pterostilbene, recognized for its anti-inflammatory, anti-carcinogenic, anti-diabetic, and neuroprotective properties, counteracts oxidative stress during I/R injury through various mechanisms. This study explored pterostilbene as a retinoprotective agent. Male Sprague Dawley rats underwent retinal I/R injury and one-week reperfusion and were treated with either vehicle or pterostilbene. After this functional electroretinographical (ERG) measurement, Western blot and histological analyses were performed. Pterostilbene treatment significantly improved retinal function, as evidenced by increased b-wave amplitude on ERG. Histological studies showed reduced retinal thinning and preserved the retinal structure in the pterostilbene-treated groups. Moreover, Western blot analysis revealed a decreased expression of glial fibrillary acidic protein (GFAP) and heat shock protein 70 (HSP70), indicating reduced glial activation and cellular stress. Additionally, the expression of pro-apoptotic and inflammatory markers, poly(ADP-ribose) polymerase 1 (PARP1) and nuclear factor kappa B (NFκB) was significantly reduced in the pterostilbene-treated group. These findings suggest that pterostilbene offers protective effects on the retina by diminishing oxidative stress, inflammation, and apoptosis, thus preserving retinal function and structure following I/R injury. This study underscores pterostilbene's potential as a neuroprotective therapeutic agent for treating retinal ischemic injury and related disorders.

Retrospective Analysis of Blood Biomarkers of Neurological Injury in Human Cases of Viral Infection and Bacterial Sepsis.

Blood biomarkers of neurological injury could provide a rapid diagnosis of central nervous system (CNS) injury caused by infections. An FDA-approved assay for mild traumatic brain injury (TBI) measures glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), which signal astrocyte and neuronal injury, respectively. Here, we assessed the applicability of this biomarker assay for determining infection-induced brain injury. We measured serum levels of GFAP and UCH-L1 retrospectively in serum samples from three study populations: 1) human cases infected with Venezuelan equine encephalitis virus (VEEV) and Madariaga virus (MADV) (n = 73), 2) human sepsis patients who were severely ill or diagnosed with encephalitis (n = 66), and 3) sepsis cases that were subsequently evaluated for cognitive impairment (n = 64). In the virus infection group, we found elevated GFAP for VEEV (p = 0.014) and MADV (p = 0.011) infections, which correlated with seizures (p = 0.006). In the bacterial sepsis group, GFAP was elevated in cases diagnosed with encephalitis (p = 0.0007) and correlated with headaches (p = 0.0002). In the bacterial sepsis cases with a later cognitive assessment, elevated GFAP (p = 0.0057) at study enrollment was associated with cognitive impairment six months later with a positive prognostic capacity of 79% (CI: 66-95%; p = 0.0068). GFAP and UCH-L1 levels measured using an FDA-approved assay for TBI may indicate brain injury resulting from viral or bacterial infections and could predict the development of neurological sequelae.

Genetic spectrum features and diagnostic accuracy of four plasma biomarkers in 248 Chinese patients with frontotemporal dementia.

Frontotemporal dementia (FTD) is characterized by phenotypic and genetic heterogeneities. However, reports on the large Chinese FTD cohort are lacking. Two hundred forty-eight patients with FTD were enrolled. All patients and 2010 healthy controls underwent next generation sequencing. Plasma samples were analyzed for glial fibrillary acidic protein (GFAP), α-synuclein (α-syn), neurofilament light chain (NfL), and phosphorylated tau protein 181 (p-tau181). Gene sequencing identified 48 pathogenic or likely pathogenic mutations in a total of 19.4% of patients with FTD (48/248). The most common mutation was the C9orf72 dynamic mutation (5.2%, 13/248). Significantly increased levels of GFAP, α-syn, NfL, and p-tau181 were detected in patients compared to controls (all p<0.05). GFAP and α-syn presented better performance for diagnosing FTD. We investigated the characteristics of phenotypic and genetic spectrum in a large Chinese FTD cohort, and highlighted the utility of plasma biomarkers for diagnosing FTD. This study used a frontotemporal dementia (FTD) cohort with a large sample size in Asia to update and reveal the clinical and genetic spectrum, and explore the relationship between multiple plasma biomarkers and FTD phenotypes as well as genotypes. We found for the first time that the C9orf72 dynamic mutation frequency ranks first among all mutations, which broke the previous impression that it was rare in Asian patients. Notably, it was the first time the C9orf72 G4C2 repeat expansion had been identified via whole-genome sequencing data, and this was verified using triplet repeat primed polymerase chain reaction (TP-PCR). We analyzed the diagnostic accuracy of four plasma biomarkers (glial fibrillary acidic protein [GFAP], α-synuclein [α-syn], neurofilament light chain [NfL], and phosphorylated tau protein 181 [p-tau181]) at the same time, especially for α-syn being included in the FTD cohort for the first time, and found GFAP and α-syn had the highest diagnostic accuracy for FTD and its varied subtypes.