Increase In Glial Fibrillary Acidic Protein Research Articles

Changes in Alzheimer Disease Blood Biomarkers and Associations With Incident All-Cause Dementia

Plasma biomarkers show promise for identifying Alzheimer disease (AD) neuropathology and neurodegeneration, but additional examination among diverse populations and throughout the life course is needed. To assess temporal plasma biomarker changes and their association with all-cause dementia, overall and among subgroups of community-dwelling adults. In 1525 participants from the US-based Atherosclerosis Risk in Communities (ARIC) study, plasma biomarkers were measured using stored specimens collected in midlife (1993-1995, mean age 58.3 years) and late life (2011-2013, mean age 76.0 years; followed up to 2016-2019, mean age 80.7 years). Midlife risk factors (hypertension, diabetes, lipids, coronary heart disease, cigarette use, and physical activity) were assessed for their associations with change in plasma biomarkers over time. The associations of biomarkers with incident all-cause dementia were evaluated in a subpopulation (n = 1339) who were dementia-free in 2011-2013 and had biomarker measurements in 1993-1995 and 2011-2013. Plasma biomarkers of amyloid-β 42 to amyloid-β 40 (Aβ42:Aβ40) ratio, phosphorylated tau at threonine 181 (p-tau181), neurofilament light (NfL), and glial fibrillary acidic protein (GFAP) were measured using the Quanterix Simoa platform. Incident all-cause dementia was ascertained from January 1, 2012, through December 31, 2019, from neuropsychological assessments, semiannual participant or informant contact, and medical record surveillance. Among 1525 participants (mean age, 58.3 [SD, 5.1] years), 914 participants (59.9%) were women, and 394 participants (25.8%) were Black. A total of 252 participants (16.5%) developed dementia. Decreasing Aβ42:Aβ40 ratio and increasing p-tau181, NfL, and GFAP were observed from midlife to late life, with more rapid biomarker changes among participants carrying the apolipoprotein E epsilon 4 (APOEε4) allele. Midlife hypertension was associated with a 0.15-SD faster NfL increase and a 0.08-SD faster GFAP increase per decade; estimates for midlife diabetes were a 0.11-SD faster for NfL and 0.15-SD faster for GFAP. Only AD-specific biomarkers in midlife demonstrated long-term associations with late-life dementia (hazard ratio per SD lower Aβ42:Aβ40 ratio, 1.11; 95% CI, 1.02-1.21; per SD higher p-tau181, 1.15; 95% CI, 1.06-1.25). All plasma biomarkers in late life had statistically significant associations with late-life dementia, with NfL demonstrating the largest association (1.92; 95% CI, 1.72-2.14). Plasma biomarkers of AD neuropathology, neuronal injury, and astrogliosis increase with age and are associated with known dementia risk factors. AD-specific biomarkers' association with dementia starts in midlife whereas late-life measures of AD, neuronal injury, and astrogliosis biomarkers are all associated with dementia.

A Pilot Study Investigating the Use of Serum Glial Fibrillary Acidic Protein to Monitor Changes in Brain White Matter Integrity After Repetitive Head Hits During a Single Collegiate Football Game.

Repetitive head hits (RHHs) in sports and military settings are increasingly recognized as a risk factor for adverse neurological outcomes, but they are not currently tracked. Blood-based biomarkers of concussion have recently been shown to increase after nonconcussive RHHs during a single sporting contest, raising the possibility that they could be used in real time to monitor the brain's early response to repeated asymptomatic head hits. To test this hypothesis, we measured GFAP in serum immediately before (T0), immediately after (T1) and 45 min (T2) after a single collegiate football game in 30 athletes. Glial fibrillary acidic protein (GFAP) changes were correlated with three measures of head impact exposure (number of hits, total linear acceleration, and total rotational acceleration captured by helmet impact sensors) and to changes in brain white matter (WM) integrity, estimated by regional changes in fractional anisotropy (FA) and mean diffusivity (MD) on diffusion tensor imaging from 24 h before (T1) to 48 h after (T3) the game. To account for the potentially confounding effects of physical exertion on GFAP, correlations were adjusted for kilocalories of energy expended during the game measured by wearable body sensors. All 30 participants were male with a mean age of 19.5 ± 1.2 years. No participant had a concussion during the index game. We observed a significant increase in GFAP from T0 to T1 (mean 79.69 vs. 91.95 pg/mL, p = 0.008) and from T0 to T2 (mean 79.69 vs. 99.21 pg/mL, p < 0.001). WM integrity decreased in multiple WM regions but was statistically significant in the right fornix (mean % FA change -1.43, 95% confidence interval [CI]: -2.20, -0.66). T0 to T2 increases in GFAP correlated with reduced FA in the left fornix, right fornix, and right medical meniscus and with increased MD in the right fornix (r-values ranged from 0.59 to 0.61). Adjustment for exertion had minimal effect on these correlations. GFAP changes did not correlate to head hit exposure, but after adjustment for exertion, T0 to T2 increases correlated with all three hit metrics (r-values ranged from 0.69 to 0.74). Thus, acute elevations in GFAP after a single collegiate football game of RHHs correlated with in-game head hit exposure and with reduced WM integrity 2 days later. These results suggest that GFAP may be a biologically relevant indicator of the brain's early response to RHHs during a single sporting event. Developing tools to measure the neurological response to RHHs on an individual level has the potential to provide insight into the heterogeneity in adverse outcomes after RHH exposure and for developing effective and personalized countermeasures. Owing to the small sample size, these findings should be considered preliminary; validation in a larger, independent cohort is necessary.

Biomarkers of Neurobiologic Recovery in Adults With Sport-Related Concussion

ImportanceSport-related concussion (SRC), a form of mild traumatic brain injury, is a prevalent occurrence in collision sports. There are no well-established approaches for tracking neurobiologic recovery after SRC.ObjectiveTo examine the levels of serum glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) in Australian football athletes who experience SRC.Design, Setting, and ParticipantsA cohort study recruiting from April 10, 2021, to September 17, 2022, was conducted through the Victorian Amateur Football Association, Melbourne, Australia. Participants included adult Australian football players with or without SRC. Data analysis was performed from May 26, 2023, to March 27, 2024.ExposureSport-related concussion, defined as at least 1 observable sign and/or 2 or more symptoms.Main Outcomes and MeasuresPrimary outcomes were serum GFAP and NfL levels at 24 hours, and 1, 2, 4, 6, 8, 12, and 26 weeks. Secondary outcomes were symptoms, cognitive performance, and return to training times.ResultsEighty-one individuals with SRC (median age, 22.8 [IQR, 21.3-26.0] years; 89% male) and 56 control individuals (median age, 24.6 [IQR, 22.4-27.3] years; 96% male) completed a total of 945 of 1057 eligible testing sessions. Compared with control participants, those with SRC exhibited higher GFAP levels at 24 hours (mean difference [MD] in natural log, pg/mL, 0.66 [95% CI, 0.50-0.82]) and 4 weeks (MD, 0.17 [95% CI, 0.02-0.32]), and NfL from 1 to 12 weeks (1-week MD, 0.31 [95% CI, 0.12-0.51]; 2-week MD, 0.38 [95% CI, 0.19-0.58]; 4-week MD, 0.31 [95% CI, 0.12-0.51]; 6-week MD, 0.27 [95% CI, 0.07-0.47]; 8-week MD, 0.36 [95% CI, 0.15-0.56]; and 12-week MD, 0.25 [95% CI, 0.04-0.46]). Growth mixture modeling identified 2 GFAP subgroups: extreme prolonged (16%) and moderate transient (84%). For NfL, 3 subgroups were identified: extreme prolonged (7%), moderate prolonged (15%), and minimal or no change (78%). Individuals with SRC who reported loss of consciousness (LOC) (33% of SRC cases) had higher GFAP at 24 hours (MD, 1.01 [95% CI, 0.77-1.24]), 1 week (MD, 0.27 [95% CI, 0.06-0.49]), 2 weeks (MD, 0.21 [95% CI, 0.004-0.42]) and 4 weeks (MD, 0.34 [95% CI, 0.13-0.55]), and higher NfL from 1 week to 12 weeks (1-week MD, 0.73 [95% CI, 0.42-1.03]; 2-week MD, 0.91 [95% CI, 0.61-1.21]; 4-week MD, 0.90 [95% CI, 0.59-1.20]; 6-week MD, 0.81 [95% CI, 0.50-1.13]; 8-week MD, 0.73 [95% CI, 0.42-1.04]; and 12-week MD, 0.54 [95% CI, 0.22-0.85]) compared with SRC participants without LOC. Return to training times were longer in the GFAP extreme compared with moderate subgroup (incident rate ratio [IRR], 1.99 [95% CI, 1.69-2.34]; NfL extreme (IRR, 3.24 [95% CI, 2.63-3.97]) and moderate (IRR, 1.43 [95% CI, 1.18-1.72]) subgroups compared with the minimal subgroup, and for individuals with LOC compared with those without LOC (IRR, 1.65 [95% CI, 1.41-1.93]).Conclusions and RelevanceIn this cohort study, a subset of SRC cases, particularly those with LOC, showed heightened and prolonged increases in GFAP and NfL levels, that persisted for at least 4 weeks. These findings suggest that serial biomarker measurement could identify such cases, guiding return to play decisions based on neurobiologic recovery. While further investigation is warranted, the association between prolonged biomarker elevations and LOC may support the use of more conservative return to play timelines for athletes with this clinical feature.

Reactive gliosis in adult zebrafish telencephalon following daily nanoplastic consumption

Background: Polystyrene nanoplastics are one of the most pervasive plastic contaminates and have been shown to infiltrate multiple mediums that are ingested by humans including air, food and water. Additionally, polystyrene nanoparticles have been shown to cross the blood brain barrier (BBB), the brain's first defense against pathogens and toxins. Following insult, the neuronal immune network enters a pro-inflammatory state referred to as reactive gliosis. Reactive gliosis is characterized by the recruitment of microglia and astroglia, the resident immune cells of the central nervous system (CNS), into a pro-inflammatory state that leads to the release of cytokines and the creation of a glial scar. This cascade of morphological and chemical changes in the CNS following prolonged insult can induce significant damage to the brain. Experiments in rodent models and cell culture indicate that exposure to plastic nanoparticles can induce inflammatory processes in the brain. This has been relatively underexplored in the zebrafish model system. In the current study we investigate the hypothesis that daily exposure to nanoplastics via the food chain can induce a chronic inflammatory state in the brain that may lead to permanent brain damage. The purpose of the current study is to investigate reactive gliosis in the telencephalon of adult zebrafish following the consumption of polystyrene-contaminated food. Methods: One thousand brine shrimp ( Artemia) per zebrafish were collected and incubated in artificial sea water (ASW) containing 44 nanometer (nm) fluorescent polystyrene (nPS) at a concentration of 0.15 milligrams (mg) nPS/50 milliliters (mL) ASW for 24 hours. Zebrafish were fed polystyrene-enriched brine shrimp once per day for fourteen consecutive days. On day fifteen, the telencephalon was removed and homogenized for western blot analysis. Reactive microglia were measured using the monoclonal 4C4 antibody which has been found to label reactive microglia. Reactive astrogliosis was quantified by measuring glial fibrillary acidic protein (GFAP), a marker for reactive astrocytes. Results: Confocal fluorescent imaging and spectrophotometry showed that Artemia were enriched with red-fluorescently tagged polystyrene nanoplastics. Additionally, the quantity of nanoplastic within one thousand shrimp was estimated to be 5 +/- 1.9 micrograms. There was an observed increase in 4C4 normalized to actin. Increases in GFAP were also detected. These data indicate that reactive gliosis by microglia and astroglia was enhanced in the zebrafish telencephalon after consuming polystyrene-contaminated food for fourteen consecutive days. Funding is supported by the Georgia Southern Department of Biology and Mercer University College of Medicine. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Retinoic acid attenuates ischemic injury-induced activation of glial cells and inflammatory factors in a rat stroke model.

Stroke is a leading cause of death and long-term disability which can cause oxidative damage and inflammation of the neuronal cells. Retinoic acid is an active metabolite of vitamin A that has various beneficial effects including antioxidant and anti-inflammatory effects. In this study, we investigated whether retinoic acid modulates oxidative stress and inflammatory factors in a stroke animal model. A middle cerebral artery occlusion (MCAO) was performed on adult male rats to induce focal cerebral ischemia. Retinoic acid (5 mg/kg) or vehicle was injected into the peritoneal cavity for four days before MCAO surgery. The neurobehavioral tests were carried out 24 h after MCAO and cerebral cortex tissues were collected. The cortical damage was assessed by hematoxylin-eosin staining and reactive oxygen species assay. In addition, Western blot and immunohistochemical staining were performed to investigate the activation of glial cells and inflammatory cytokines in MCAO animals. Ionized calcium-binding adapter molecule-1 (Iba-1) and glial fibrillary acidic protein (GFAP) were used as markers of microglial and astrocyte activation, respectively. Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were used as representative pro-inflammatory cytokines. Results showed that MCAO damage caused neurobehavioral defects and histopathological changes in the ischemic region and increased oxidative stress. Retinoic acid treatment reduced these changes caused by MCAO damage. We detected increases in Iba-1 and GFAP in MCAO animals treated with vehicle. However, retinoic acid alleviated increases in Iba-1 and GFAP caused by MCAO damage. Moreover, MCAO increased levels of nuclear factor-κB and pro-inflammatory cytokines, including TNF-α and IL-1β. Retinoic acid alleviated the expression of these inflammatory proteins. These findings elucidate that retinoic acid regulates microglia and astrocyte activation and modulates pro-inflammatory cytokines. Therefore, this study suggests that retinoic acid exhibits strong antioxidant and anti-inflammatory properties by reducing oxidative stress, inhibiting neuroglia cell activation, and preventing the increase of pro-inflammatory cytokines in a cerebral ischemia.

Cognitive decline in post-COVID-19 syndrome does not correspond with persisting neuronal or astrocytic damage

Cognitive impairment is the most frequent symptom reported in post-COVID-19 syndrome (PCS). Aetiology of cognitive impairment in PCS is still to be determined. Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) are increased in acute COVID-19. Their role as biomarkers in other neurological disorders is under debate. We analysed serum levels of NfL and GFAP as markers for neuronal and astrocytic damage in 53 patients presenting to a PCS Neurology outpatient clinic. Only individuals with self-reported cognitive complaints were included. In these individuals, cognitive complaints were further assessed by comprehensive neuropsychological assessment (NPA). Patients were categorized into subgroups of subjective cognitive decline, single domain impairment, or multi-domain impairment. Serum NfL was in normal range, however an increase of serum GFAP was detected in 4% of patients. Serum NfL and GFAP levels correlated with each other, even when adjusting for patient age (r = 0.347, p = 0.012). NPA showed deficits in 70%; 40% showing impairment in several tested domains. No significant differences were found between serum NfL- and GFAP-levels comparing patients with subjective cognitive decline, single domain impairment, or multi-domain impairment. Persistent neuronal or astrocytic damage did not correlate with cognitive impairment in PCS.

DPP4 Valorphin Activate NR4As Pathway and OPA1 That Protect from CoQ10 Deficiency, OPA1 Dysfunctions and WMH

Deficiencies in Threonine (Thr), Tryptophan hydroxylase (Tph), Glutamate (Glu), Glutamine (Gln), and Leucine can result from increased polarizability in mTORC1 and its subunits. These deficiencies may lead to disorders in OPA1 repair, which can be a primary cause of Coenzyme Q10 (CoQ10) deficiency disease. CoQ10 is crucial for maintaining the inner mitochondrial membrane and is necessary for the synthesis of the glucocorticoid receptor (GCR). Mitochondrial damage or dysfunction can lead to the accumulation of pro-inflammatory molecules, which may cause mutations in subunits and proteins. Reduced levels of Tryptophan, Glycine (Gly), and Arginine (Arg) can result in decreased Proline synthesis, subsequently reducing tRNA levels. This, in turn, can impair mitochondrial OPA1 repair and function due to decreased GTPase activity. The reduced function of GTPase can lead to decreased IL-17 synthesis and the accumulation of pro-inflammatory molecules, resulting in a reduction in serotonin production, as well as decreased production of GCbeta, oxytocin, and Nrf2. These changes can lead to a decrease in the proliferation of megakaryocytes and, consequently, reduced hematopoiesis, which is associated with white matter hyperintensity. Opioid receptors play a role in producing powerful analgesia, contributing to the function of immune cells, and modulating acquired immune responses, including the function of lymphocytes. Tryptophan, Leucine, and Tyrosine kinases are crucial for activating mitochondrial OPA1 repairs, which are essential for CoQ10 synthesis. Tryptophan (TGG) is necessary for activating Proline, which is essential for both OPA1 function and tRNA production. Additionally, it plays a role in IL17 synthesis and the activation of the NR4As pathway, which includes the activation of GCs-beta, oxytocin, and Nrf2 production, respectively. Cytotoxic edema can result from uncontrolled or uncompensated cation influx, primarily sodium (Na+). This edema occurs due to high levels of potassium (K) and sodium (Na) binding toxicity, leading to coagulation and reduced ATPase and GTPase activity. It starts with a decrease in CoQ10 synthesis and an increase in Plasma Glial Fibrillary Acidic Protein (GFAP), resulting in decreased mineralocorticoid. Increased sodium and potassium binding, associated with decreased anions binding in biological molecules, can be due to reduced GTPase and OPA1 function. This reduction in anions function is the result of a primary Coenzyme Q10 (CoQ10) deficiency, leading to elevated GFAP levels in cognitively normal older adults at risk of Alzheimer's disease. Primary Coenzyme Q10 (CoQ10) deficiency is typically associated with multisystem involvement, including neurologic manifestations such as fatal neonatal encephalopathy with hypoxia, late-onset multiple-system atrophy-like symptoms, dystonia, spasticity, seizures, and intellectual disability. Autoimmune diseases and skin inflammatory disorders can start due to increased cation binding toxicity, which reduces ATPase and GTPase function, characterized by a deficiency in proper GTPase production, leading to a reduction in mitochondrial OPA1 function and a deficiency in GCs-beta synthesis via the NR4As pathway. GFAP is an important neuroinflammation biomarker, and an increase in its levels may indicate OPA1 dysfunction, a decrease in CoQ10, neuroinflammation, and a reduction in the NR4As pathway. The increase in GFAP during acute ischemic stroke can be initiated by increased cation binding to anions, leading to enhanced energy stability and decreased tRNA production, which is proline-dependent. This decrease in tRNAs and GTPase activity can result in a decrease in IL17 production, increased inflammation, decreased blood flow to the brain, and reduced oxygen supply to the brain, ultimately contributing to neuronal damage. A decrease in hemorphin (valorphin) reflects reduced lymphocyte function and a loss of cholinecontaining phospholipids (CCPLs). Valorphin contains Tyrosine, which is essential for kinases production, required for choline kinases synthesis, and crucial for activating tRNAs, serotonin, oxytocin, and Nrf2 via the NR4As pathway, all of which are essential for lymphocyte function and antiinflammatory growth. Nrf2 dysfunction, connected to NR4As and oxytocin dysfunction, plays a significant role in the pathogenesis of vascular cognitive impairment and dementia (VCID).

Longitudinal blood biomarker trajectories in preclinical Alzheimer's disease.

Plasma biomarkers are altered years prior to Alzheimer's disease (AD) clinical onset. We measured longitudinal changes in plasma amyloid-beta (Aβ)42/40 ratio, pTau181, pTau231, neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) in a cohort of older adults at risk of AD (n=373 total, n=229 with Aβ and tau positron emission tomography [PET] scans) considering genetic and demographic factors as possible modifiers of these markers' progression. Aβ42/40 ratio concentrations decreased, while NfL and GFAP values increased over the 4-year follow-up. Apolipoprotein E (APOE) ε4 carriers showed faster increase in plasma pTau181 than non-carriers. Older individuals showed a faster increase in plasma NfL, and females showed a faster increase in plasma GFAP values. In the PET subsample, individuals both Aβ-PET and tau-PET positive showed faster plasma pTau181 and GFAP increase compared to PET-negative individuals. Plasma markers can track biological change over time, with plasma pTau181 and GFAP markers showing longitudinal change in individuals with preclinical AD. Longitudinal increase of plasma pTau181 and glial fibrillary acidic protein (GFAP) can be measured in the preclinical phase of AD. Apolipoprotein Eε4 carriers experience faster increase in plasma pTau181 over time than non-carriers. Female sex showed accelerated increase in plasma GFAP over time compared to males. Aβ42/40 and pTau231 values are already abnormal at baseline in individuals with both amyloid and tau PET burden.

The association between Alzheimer’s disease blood‐based biomarkers and cognitive impairment and probable dementia in Look AHEAD MIND

AbstractBackgroundThe effect of an intensive lifestyle intervention (ILI) on Alzheimer’s disease (AD) blood‐based biomarker levels and cognitive outcomes among individuals with type 2 diabetes (T2D) is unknown. We examined AD biomarkers and cognitive outcomes in the Look AHEAD Study.MethodParticipants aged 45‐76 years were randomized at baseline to a 10‐year ILI or a diabetes support and education (DSE) condition. Cognitive assessments at years 8‐18 included measures of attention, executive function, global function, and memory. Mild cognitive impairment (MCI) and probable dementia were adjudicated by an expert panel. Stored baseline and end‐of‐intervention plasma samples were analyzed with the Quanterix Simoa HD‐X Analyzer. Changes in Aβ42/Aβ40, ptau181, neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) were evaluated in relation to randomization status, demographic characteristics, and cognitive outcomes. Cognitive scores and biomarker levels were converted to z‐scores. Cognitive trajectories were evaluated using mixed models to account for repeated measures; logistic regression was used for a composite outcome of MCI/dementia. Models were adjusted for baseline characteristics (age, sex, education, race/ethnicity, body mass index (BMI), CVD history, hypertension, diabetes duration, eGFR), APOE‐ε4, randomization arm, time from randomization, and time between blood draw and cognitive testing.ResultThe mean age of 779 participants was 61.4 years; 56% = female, 22.8% = APOE ε4+, mean BMI = 34.8, baseline diabetes duration &gt;5 years = 57%, 16.7% Black, 12.5% Hispanic, 66.2% White, and 4.7% other racial and ethnic groups. There were no associations between the intervention and biomarker levels at baseline or biomarker change over time. Increases in NfL levels significantly predicted lower memory (‐0.04 ±0.01; p = 0.002), global cognition scores (‐0.05 ±0.02; p = 0.011), executive function (‐0.04 ±0.01; p = 0.01), as well as increased risk of MCI/probable dementia (odds ratio [OR] 1.10, 95% CI 1.02‐1.19). Increases in GFAP predicted lower memory (‐0.10 ±0.03; p = 0.0001), global cognition (‐0.09 ±0.03; p = 0.009), executive function scores (‐0.12 ±0.03; p&lt;0.0001), and increased risk of MCI/probable dementia (OR 1.24, 95% CI 1.09‐1.41).ConclusionThere was no association between the intervention and changes in biomarker levels. Increasing levels of NfL and GFAP over the ∼10 year period were associated with reduced cognitive performance and increased risk of MCI/probable dementia.

Longitudinal changes in Alzheimer's-related plasma biomarkers and brain amyloid.

Understanding longitudinal plasma biomarker trajectories relative to brain amyloid changes can help devise Alzheimer's progression assessment strategies. We examined the temporal order of changes in plasma amyloid-β ratio ( ), glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), and phosphorylated tau ratios ( , ) relative to 11 C-Pittsburgh compound B (PiB) positron emission tomography (PET) cortical amyloid burden (PiB-/+). Participants (n=199) were cognitively normal at index visit with a median 6.1-year follow-up. PiB groups exhibited different rates of longitudinal change in . Change in brain amyloid correlated with change in GFAP (r=0.5, 95% CI=[0.26, 0.68]). The greatest relative decline in (-1%/year) preceded brain amyloid positivity by 41 years (95% CI=[32, 53]). Plasma may begin declining decades prior to brain amyloid accumulation, whereas p-tau ratios, GFAP, and NfL increase closer in time. HIGHLIGHTS Plasma declines over time among PiB- but does not change among PiB+. Phosphorylated-tau to Aβ42 ratios increase over time among PiB+ but do not change among PiB-. Rate of change in brain amyloid is correlated with change in GFAP and neurofilament light chain. The greatest decline in may precede brain amyloid positivity by decades.

Retinotectal plasticity induced by monocular enucleation during the critical period is dependent of A2a adenosine receptor: A possible role of astrocytes

The retinotectal topography of rats develops within the first three postnatal weeks during the critical period. Previous studies have shown that monocular enucleation results in plasticity of the intact retinotectal pathway in a time-dependent manner. Glial fibrillary acidic protein (GFAP), an astrocyte marker, is up-regulated after central nervous system injury. Adenosine is a neuromodulator involved in the development and plasticity of the visual system acting through the inhibitory A1 and excitatory A2a receptor activities. Herein, we examined whether adenosine receptors and astrocytes are crucial for monocular enucleation (ME)-induced plasticity. We also investigate whether A2a blockade alters retinotectal plasticity in an astrocyte-dependent manner. Lister Hooded rats were submitted to monocular enucleation at postnatal day 10 (PND10) or PND21 and, after different survival times, were processed for immunohistochemistry or western blotting assays. Another group underwent subpial implantation of ELVAX containing vehicle (DMSO) or SCH58261 (1 μM - an A2a receptor antagonist), simultaneously with ME at PND10. After a 72 h survival, GFAP content and the retinotectal plasticity were evaluated. Our data show that monocular enucleation leads to an upregulation in GFAP expression in the contralateral superior colliculus. At PND10, a slight increase in GFAP labeling was observed at 72 h post-enucleation, while at PND21 GFAP increase was detected in the deafferented superior colliculus after 1 to 3 weeks of survival. The content of adenosine receptors also varies in the contralateral target after ME. A transient increase in A1 receptors is observed in the early periods of plasticity, while A2a receptors are upregulated later. Interestingly, the local blockade of A2a receptors abolished the increase in GFAP and the retinotectal reorganization induced by monocular enucleation during the critical period. Taken together these results suggest a correlation between astrocytes and A2a adenosine receptors in the subcortical visual plasticity.

GFAP and NfL increase during neurotoxicity from high baseline levels in pediatric CD19-CAR T-cell patients.

There is a need for biomarkers to predict and measure the severity of immune effector cell-associated neurotoxicity syndrome (ICANS). Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) are well-validated biomarkers of astroglial and neuronal injury, respectively. We hypothesized that pretreatment GFAP and NfL levels can predict the risk of subsequent ICANS and that increases in GFAP and NfL levels during treatment reflect ICANS severity. We measured cerebrospinal fluid GFAP (cGFAP) and NfL (cNfL) along with serum NfL (sNfL) levels at pretreatment and day 7 to 10 after chimeric antigen receptor (CAR) T-cell infusion in 3 pediatric cohorts treated with CD19- or CD19/CD22-directed CAR T cells. cGFAP and cNfL levels increased during grade ≥1 ICANS in patients treated with CD19-directed CAR T cells but not in those who received CD19/CD22-directed CAR T cells. The sNfL levels did not increase during ICANS. Prelymphodepletion cGFAP, cNfL, and sNfL levels were not predictive of subsequent ICANS. Elevated baseline cGFAP levels were associated with a history of transplantation. Patients with prior central nervous system (CNS) radiation had higher cNfL levels, and elevated baseline sNfL levels were associated with a history of peripheral neuropathy. Thus, cGFAP and cNfL may be useful biomarkers for measuring the severity of CNS injury during ICANS in children. Elevated baseline levels of cGFAP, cNfL, and sNfL likely reflect the cumulative injury to the central and peripheral nervous systems from prior treatment. However, levels of any of the 3 biomarkers before CAR T-cell infusion did not predict the risk of ICANS.

Circulating Brain-Injury Markers After Surgery for Craniosynostosis

Historically, there have been few quantitative methods for effectively evaluating outcomes after surgery for craniosynostosis. In this prospective study, we assessed a novel approach for detecting possible postsurgery brain injury in patients with craniosynostosis. We included consecutive patients operated on for sagittal (pi-plasty or craniotomy combined with springs) or metopic (frontal remodeling) synostosis at the Craniofacial Unit at Sahlgrenska University Hospital, Gothenburg, Sweden, from January 2019 to September 2020. Plasma concentrations of the brain-injury biomarkers neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and tau were measured immediately before induction of anesthesia, immediately before and after surgery, and on the first and the third postoperative days using single-molecule array assays. Of the 74 patients included, 44 underwent craniotomy combined with springs for sagittal synostosis, 10 underwent pi-plasty for sagittal synostosis, and 20 underwent frontal remodeling for metopic synostosis. Compared with baseline, GFAP level showed a maximal significant increase at day 1 after frontal remodeling for metopic synostosis and pi-plasty (P= 0.0004 and P= 0.003, respectively). By contrast, craniotomy combined with springs for sagittal synostosis showed no increase in GFAP. For neurofilament light, we found a maximal significant increase at day 3 after surgery for all procedures, with significantly higher levels observed after frontal remodeling and pi-plasty compared with craniotomy combined with springs (P < 0.001). These represent the first results showing significantly increased plasma levels of brain-injury biomarkers after surgery for craniosynostosis. Furthermore, we found that more extensive cranial vault procedures resulted in higher levels of these biomarkers relative to less extensive procedures.

Lipopolysaccharide induced neuroprotective effects of bacterial protease against Alzheimer's disease in male Wistar albino rats

Alzheimer's disease (AD) is a highly severe neurodegenerative condition that affects the hippocampus and is characterized by memory loss and dementia. This investigation aims to determine the potential of a bacterial protease enzyme produced by a new mutant strain of bacteria (Bacillus cereus S6-3/UM90) to influence the rat behavioural, biochemical, histological, and immuno-histochemical functions induced by lipopolysaccharides (LPS) experimentally. The administration of LPS exhibited a decline in memory performance via Morris' Water Maze test along with an elevation of IL-6, IL-17, amino acid neurotransmitters, Adenosine monophosphate (AMP), and 8-OHdG, whereas a decrease in ATP (Adenosine Triphosphate), monoamine transmitters, AChE (acetylcholinesterase) and PC (phosphatidylcholine). Additionally, there was a notable increase in GFAP (glial fibrillary acidic protein) and p-Tau protein immuno-expression levels along with obvious histological lesions in the hippocampal CA3 region. Moreover, the administration of protease or Donepezil restored the measured parameters to nearly normal levels and improved the histological architecture of the hippocampus and ameliorated memory impairments. In conclusion, the study provides evidence that the treatment with Bacterial protease can improve the memory and learning impairments of LPS–induced AD and may be used as a promising therapeutic agent to manage AD since it has anti-inflammatory and antioxidant effects.

Plasma biomarker profiles in autosomal dominant Alzheimer's disease.

Emerging plasma biomarkers of Alzheimer's disease might be non-invasive tools to trace early Alzheimer's disease-related abnormalities such as the accumulation of amyloid-beta peptides, neurofibrillary tau tangles, glial activation and neurodegeneration. It is, however, unclear which pathological processes in the CNS can be adequately detected by peripheral measurements and whether plasma biomarkers are equally applicable in both clinical and preclinical phases. Here we aimed to explore the timing and performance of plasma biomarkers in mutation carriers compared to non-carriers in autosomal dominant Alzheimer's disease. Samples (n = 164) from mutation carriers (n = 33) and non-carriers (n = 42) in a Swedish cohort of autosomal dominant Alzheimer's disease (APP p.KM670/671NL, APP p.E693G and PSEN1 p.H163Y) were included in explorative longitudinal analyses. Plasma phosphorylated tau (P-tau181), total tau (T-tau), neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) concentrations were measured with a single-molecule array method as previously described. Plasma biomarkers were additionally correlated to Alzheimer's disease core biomarkers in the CSF. Results from the longitudinal analyses confirmed that plasma P-tau181, NfL and GFAP concentrations were higher in mutation carriers compared to non-carriers. This change was observed in the presymptomatic phase and detectable first as an increase in GFAP approximately 10 years before estimated symptom onset, followed by increased levels of P-tau181 and NfL closer to expected onset. Plasma P-tau181 levels were correlated to levels of P-tau181 and T-tau in the CSF. Altogether, plasma P-tau181, GFAP and NfL seem to be feasible biomarkers to detect different Alzheimer's disease-related pathologies already in presymptomatic individuals. Interestingly, changes in plasma GFAP concentrations were detected prior to P-tau181 and NfL. Our results suggest that plasma GFAP might reflect Alzheimer's disease pathology upstream to accumulation of tangles and neurodegeneration. The implications of these findings need additional validation, in particular because of the limited sample size.

No increase in GFAP and S-100B in very preterm infants with mild periventricular leukomalacia or intraventricular hemorrhage: a pilot study

To determine the serum levels of glial fibrillary acidic protein (GFAP) and S-100B in very preterm infants with and without periventricular leukomalacia (PVL) and/or intraventricular hemorrhage (IVH). The study enrolled preterm infants born between 23 and 32 weeks of gestation admitted to the Neonatal Intensive Care Unit, University Medical Center Ljubljana. PVL and IVH were determined with cranial ultrasound. Peripheral blood was collected in the first 24 hours after delivery and once between days 4 to 7. GFAP and S-100B concentrations were measured in serum samples. Infants with PVL or IVH were compared with infants without PVL or IVH. Of 40 patients (mean gestational age 29.4 weeks), 7 had IVH and/or PVL. S-100B was detectable in peripheral blood in all patients at every measurement. In the group with IVH or PVL, the median S-100B at the first sampling was 0.43 (IQR 0.29-0.60) ng/mL, and 0.40 (IQR 0.33-1.01) ng/mL at the second sampling. In the group without PVL or IVH, it was 0.40 (IQR 0.29-0.6) ng/mL at the first sampling and 0.43 (IQR 0.34-0.62) ng/mL at the second sampling. The median GFAP was 0 regardless of the group and sampling time. The groups did not significantly differ in serum GFAP or S-100B levels. Peripheral blood levels of GFAP and S-100B were not significantly increased in very preterm infants that developed PVL or IVH. The predictive value of GFAP and S-100B as biomarkers of neonatal brain injury should be further explored in a larger cohort of neonates with more extensive IVH or PVL.

Characterization of NLRP3 Inflammasome Activation in the Onset of Diabetic Retinopathy.

The aim of this study was to characterize the role of nucleotide-binding oligomerization domain- (NOD-) like receptor (NLR) protein 3 (NLRP3) inflammasome activation in the onset of diabetic retinopathy (DR) using retina and vitreous from donors without diabetes mellitus (CTL), with diabetes mellitus alone (DM), and with DR. Retinal expression of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba-1), the key markers of retinal inflammation, connexin43 (Cx43) which is involved in upstream inflammasome regulation, as well as NLRP3 and cleaved caspase-1, the main markers of inflammasome activation, were evaluated using immunohistochemistry and Western blotting. Vitreous interleukin (IL)-1β and IL-18, biomarkers of the activated inflammasome, were measured using a Luminex multiplex assay. Results showed a significant increase in the number and size of Iba-1+ cells and NLRP3 expression in DM, while a significant increase in GFAP, Cx43, cleaved caspase-1 and vitreous IL-18, as well as a further increase in Iba-1 and NLRP3 was found in DR. This suggests that the inflammasome is already primed in DM before its activation in DR. Furthermore, IL-18 may act as the major effector of inflammasome activation in DR while nuclear translocation of cleaved caspase-1 may play a role in gene transcription contributing to DR onset.

Abstract 10581: Sustained Increase of Serum Glial Fibrillary Acidic Protein After First St-Elevation Myocardial Infarction

Introduction: Acute ischemic cardiac injury predisposes for cognitive impairment, dementia and depression. Beyond altered cerebral blood flow and neurohumoral activation, recent positron emission tomography data pathophysiologically suggest acute and chronic neuroinflammation, which is accompanied by astroglial activation, after acute experimental myocardial infarction (MI). Hypothesis: Peripheral serum biomarkers indicating neuronal and glial involvement are altered in the year after first acute MI. Methods: Within the investigator-initiated, prospective, multicenter diagnostic ETiCS study, we quantified serum levels of neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) using ultra-sensitive molecular immunoassays serially in the year after first ST-elevation MI (STEMI). Cardiac magnetic resonance imaging enabled precise detection of infarction volume and ejection fraction. Results: Sufficient biomaterial was available from 45 STEMI patients (aged 28 to 78 years, median 56 years, 11% female). Median serum NfL (quartiles) at hospital admission was 10.6 (7.2, 14.8 pg/ml) and median GFAP 63.8 (47.0, 89.9 pg/ml). Absolute levels of NfL (ρ=0.78; p&lt;0.001) and GFAP (ρ=0.56; p&lt;0.001) correlated to patient age at all time-points. While NfL remained unaltered in the course of one year, GFAP after STEMI increased in the first 3 months after MI with a mean change of +10.6±25.0 pg/ml (p=0.007), and remained elevated after 6 months (+12.4±32.9 pg/ml; p=0.015) and 12 months (+12.6±31.2 pg/ml; p=0.010) compared to baseline. Larger relative infarction volume (ρ=0.41; p=0.009) and higher peak creatine kinase levels (ρ=0.39; p&lt;0.001), but not ejection fraction, correlated to increases of GFAP and NfL, respectively. Conclusions: Our findings suggest subtle glial damage after STEMI which correlates to infarction volume. Further studies need to evaluate the valence of serum GFAP as a peripheral biomarker of cognitive decline after MI.

Serum neurofilament-light and glial fibrillary acidic protein levels in hydroxychloroquine-treated primary progressive multiple sclerosis.

In a recent trial, hydroxychloroquine (HCQ) treatment reduced the expected rate of disability worsening at 18 months in primary progressive multiple sclerosis (PPMS). Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) are emerging biomarkers in multiple sclerosis. We measured NfL and GFAP levels in serum samples from 39 patients with inactive PPMS included in a phase II clinical trial of HCQ treatment in PPMS at multiple time points over 18 months, and investigated the association of these biomarkers with clinical disability at screening and during follow-up. Screening and 12-month retinal nerve fiber layer (RNFL) thickness was also recorded and analyzed. NfL and GFAP levels increased over time, but only significantly from screening to month 6. NfL and GFAP levels did not significantly increase from month 6 up to month 18. At screening, NfL and GFAP levels did not correlate with the Expanded Disability Status Scale(EDSS), and GFAP but not NfL modestly correlated with Timed 25-Foot Walk test (T25FW). Screening NfL and GFAP levels did not predict disability worsening (≥20% worsening on the T25FW) at month 18. RNFL thickness decreased significantly from screening to month 12 and independently predicted disability worsening. In this cohort of people with inactive PPMS, HCQ treatment attenuated the increase of NfL and GFAP after 6 months of treatment and up to 18 months of follow-up, suggesting a treatment effect of HCQ over these biomarkers. RNFL thickness, a marker of neuroaxonal atrophy, was associated with disability worsening, and should be explored further as a prognostic marker in this population.

Dynamics of Inflammatory and Neurodegenerative Biomarkers after Autologous Hematopoietic Stem Cell Transplantation in Multiple Sclerosis.

Autologous hematopoietic stem cell transplantation (aHSCT) is a highly efficient treatment of multiple sclerosis (MS), and hence it likely normalizes pathological and/or enhances beneficial processes in MS. The disease pathomechanisms include neuroinflammation, glial cell activation and neuronal damage. We studied biomarkers that in part reflect these, like markers for neuroinflammation (C-X-C motif chemokine ligand (CXCL) 9, CXCL10, CXCL13, and chitinase 3-like 1 (CHI3L1)), glial perturbations (glial fibrillary acidic protein (GFAP) and in part CHI3L1), and neurodegeneration (neurofilament light chain (NfL)) by enzyme-linked immunosorbent assays (ELISA) and single-molecule array assay (SIMOA) in the serum and cerebrospinal fluid (CSF) of 32 MS patients that underwent aHSCT. We sampled before and at 1, 3, 6, 12, 24 and 36 months after aHSCT for serum, as well as before and 24 months after aHSCT for CSF. We found a strong increase of serum CXCL10, NfL and GFAP one month after the transplantation, which normalized one and two years post-aHSCT. CXCL10 was particularly increased in patients that experienced reactivation of cytomegalovirus (CMV) infection, but not those with Epstein-Barr virus (EBV) reactivation. Furthermore, patients with CMV reactivation showed increased Th1 phenotype in effector memory CD4+ T cells. Changes of the other serum markers were more subtle with a trend for an increase in serum CXCL9 early post-aHSCT. In CSF, GFAP levels were increased 24 months after aHSCT, which may indicate sustained astroglia activation 24 months post-aHSCT. Other CSF markers remained largely stable. We conclude that MS-related biomarkers indicate neurotoxicity early after aHSCT that normalizes after one year while astrocyte activation appears increased beyond that, and increased serum CXCL10 likely does not reflect inflammation within the central nervous system (CNS) but rather occurs in the context of CMV reactivation or other infections post-aHSCT.