Elevated Glial Fibrillary Acidic Protein Research Articles

Elevated plasma neurofilament light and glial fibrillary acidic protein in epilepsy versus nonepileptic seizures and nonepileptic disorders.

Research suggests that recurrent seizures may lead to neuronal injury. Neurofilament light chain protein (NfL) and glial fibrillary acidic protein (GFAP) levels increase in cerebrospinal fluid and blood in response to neuroaxonal damage, and they have been hypothesized as potential biomarkers for epilepsy. We examined plasma NfL and GFAP levels and their diagnostic utility in differentiating patients with epilepsy from those with psychogenic nonepileptic seizures (PNES) and other nonepileptic disorders. We recruited consecutive adults admitted for video-electroencephalographic monitoring and formal neuropsychiatric assessment. NfL and GFAP levels were quantified and compared between different patient groups and an age-matched reference cohort (n = 1926) and correlated with clinical variables in patients with epilepsy. A total of 138 patients were included, of whom 104 were diagnosed with epilepsy, 22 with PNES, and 12 with other conditions. Plasma NfL and GFAP levels were elevated in patients with epilepsy compared to PNES, adjusted for age and sex (NfL p = .04, GFAP p = .04). A high proportion of patients with epilepsy (20%) had NfL levels above the 95th age-matched percentile compared to the reference cohort (5%). NfL levels above the 95th percentile of the reference cohort had a 95% positive predictive value for epilepsy. Patients with epilepsy who had NfL levels above the 95th percentile were younger than those with lower levels (37.5 vs. 43.8 years, p = .03). An elevated NfL or GFAP level in an individual patient may support an underlying epilepsy diagnosis, particularly in younger adults, and cautions against a diagnosis of PNES alone. Further examination of the association between NfL and GFAP levels and specific epilepsy subtypes or seizure characteristics may provide valuable insights into disease heterogeneity and contribute to the refinement of diagnosis, understanding pathophysiological mechanisms, and formulating treatment approaches.

Delivery of miR-15b-5p via magnetic nanoparticle-enhanced bone marrow mesenchymal stem cell-derived extracellular vesicles mitigates diabetic osteoporosis by targeting GFAP

Diabetic osteoporosis (DO) presents significant clinical challenges. This study aimed to investigate the potential of magnetic nanoparticle-enhanced extracellular vesicles (GMNPE-EVs) derived from bone marrow mesenchymal stem cells (BMSCs) to deliver miR-15b-5p, thereby targeting and downregulating glial fibrillary acidic protein (GFAP) expression in rat DO models. Data was sourced from DO-related RNA-seq datasets combined with GEO and GeneCards databases. Rat primary BMSCs, bone marrow-derived macrophages (BMMs), and osteoclasts were isolated and cultured. EVs were separated, and GMNPE targeting EVs were synthesized. Bioinformatic analysis revealed a high GFAP expression in DO-related RNA-seq and GSE26168 datasets for disease models. Experimental results confirmed elevated GFAP in rat DO bone tissues, promoting osteoclast differentiation. miR-15b-5p was identified as a GFAP inhibitor, but was significantly downregulated in DO and enriched in BMSC-derived EVs. In vitro experiments showed that GMNPE-EVs could transfer miR-15b-5p to osteoclasts, downregulating GFAP and inhibiting osteoclast differentiation. In vivo tests confirmed the therapeutic potential of this approach in alleviating rat DO. Collectively, GMNPE-EVs can effectively deliver miR-15b-5p to osteoclasts, downregulating GFAP expression, and hence, offering a therapeutic strategy for rat DO.

Perivascular spaces, plasma GFAP, and speeded executive function in neurodegenerative diseases.

We investigated the effect of perivascular spaces (PVS) volume on speeded executive function (sEF), as mediated by white matter hyperintensities (WMH) volume and plasma glial fibrillary acidic protein (GFAP) in neurodegenerative diseases. A mediation analysis was performed to assess the relationship between neuroimaging markers and plasma biomarkers on sEF in 333 participants clinically diagnosed with Alzheimer's disease/mild cognitive impairment, frontotemporal dementia, or cerebrovascular disease from the Ontario Neurodegenerative Disease Research Initiative. PVS was significantly associated with sEF (c=-0.125±0.054, 95% bootstrap confidence interval [CI] [-0.2309, -0.0189], p=0.021). This effect was mediated by both GFAP and WMH. In this unique clinical cohort of neurodegenerative diseases, we demonstrated that the effect of PVS on sEF was mediated by the presence of elevated plasma GFAP and white matter disease. These findings highlight the potential utility of imaging and plasma biomarkers in the current landscape of therapeutics targeting dementia. Perivascular spaces (PVS) and white matter hyperintensities (WMH) are imaging markers of small vessel disease. Plasma glial fibrillary protein acidic protein (GFAP) is a biomarker of astroglial injury. PVS, WMH, and GFAP are relevant in executive dysfunction from neurodegeneration. PVS's effect on executive function was mediated by GFAP and white matter disease.

Peripheral GFAP and NfL as early biomarkers for dementia: longitudinal insights from the UK Biobank

BackgroundPeripheral glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) are sensitive markers of neuroinflammation and neuronal damage. Previous studies with highly selected participants have shown that peripheral GFAP and NfL levels are elevated in the pre-clinical phase of Alzheimer’s disease (AD) and dementia. However, the predictive value of GFAP and NfL for dementia requires more evidence from population-based cohorts.MethodsThis was a prospective cohort study to evaluate UK Biobank participants enrolled from 2006 to 2010 using plasma GFAP and NfL measurements measured by Olink Target Platform and prospectively followed up for dementia diagnosis. Primary outcome was the risk of clinical diagnosed dementia. Secondary outcomes were cognition. Linear regression was used to assess the associations between peripheral GFAP and NfL with cognition. Cox proportional hazard models with cross-validations were used to estimate associations between elevated GFAP and NfL with risk of dementia. All models were adjusted for covariates.ResultsA subsample of 48,542 participants in the UK Biobank with peripheral GFAP and NfL measurements were evaluated. With an average follow-up of 13.18 ± 2.42 years, 1312 new all-cause dementia cases were identified. Peripheral GFAP and NfL increased up to 15 years before dementia diagnosis was made. After strictly adjusting for confounders, increment in NfL was found to be associated with decreased numeric memory and prolonged reaction time. A greater annualized rate of change in GFAP was significantly associated with faster global cognitive decline. Elevation of GFAP (hazard ratio (HR) ranges from 2.25 to 3.15) and NfL (HR ranges from 1.98 to 4.23) increased the risk for several types of dementia. GFAP and NfL significantly improved the predictive values for dementia using previous models (area under the curve (AUC) ranges from 0.80 to 0.89, C-index ranges from 0.86 to 0.91). The AD genetic risk score and number of APOE*E4 alleles strongly correlated with GFAP and NfL levels.ConclusionsThese results suggest that peripheral GFAP and NfL are potential biomarkers for the early diagnosis of dementia. In addition, anti-inflammatory therapies in the initial stages of dementia may have potential benefits.

Early GFAP and UCH-L1 point-of-care biomarker measurements for the prediction of traumatic brain injury and progression in patients with polytrauma and hemorrhagic shock

OBJECTIVE Traumatic brain injury (TBI) and hemorrhage are responsible for the largest proportion of all trauma-related deaths. In polytrauma patients at risk of hemorrhage and TBI, the diagnosis, prognosis, and management of TBI remain poorly characterized. The authors sought to characterize the predictive capabilities of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) measurements in patients with hemorrhagic shock with and without concomitant TBI. METHODS The authors performed a secondary analysis on serial blood samples derived from a prospective observational cohort study that focused on comparing early whole-blood and component resuscitation. A convenience sample of patients was used in which samples were collected at three time points and the presence of TBI or no TBI via CT imaging was documented. GFAP and UCH-L1 measurements were performed on plasma samples using the i-STAT Alinity point-of-care platform. Using classification tree recursive partitioning, the authors determined the measurement cut points for each biomarker to maximize the abilities for predicting the diagnosis of TBI, Rotterdam CT imaging scores, and 6-month Glasgow Outcome Scale–Extended (GOSE) scores. RESULTS Biomarker comparisons demonstrated that GFAP and UCH-L1 measurements were associated with the presence of TBI at all time points. Classification tree analyses demonstrated that a GFAP level > 286 pg/ml for the sample taken upon the patient’s arrival had an area under the receiver operating characteristic curve of 0.77 for predicting the presence of TBI. The classification tree results demonstrated that a cut point of 3094 pg/ml for the arrival GFAP measurement was the most predictive for an elevated Rotterdam score on the initial and second CT scans and for TBI progression between scans. No significant associations between any of the most predictive cut points for UCH-L1 and Rotterdam CT scores or TBI progression were found. The predictive capabilities of UCH-L1 were limited by the range allowed by the point-of-care platform. Arrival GFAP cut points remained strong independent predictors after controlling for all potential polytrauma confounders, including injury characteristics, shock severity, and resuscitation. CONCLUSIONS Early measurements of GFAP and UCH-L1 on a point-of-care device are significantly associated with CT-diagnosed TBI in patients with polytrauma and shock. Early elevated GFAP measurements are associated with worse head CT scan Rotterdam scores, TBI progression, and worse GOSE scores, and these associations are independent of other injury attributes, shock severity, and early resuscitation characteristics.

Metabolomic modelling and neuroprotective effects of carvacrol against acrylamide toxicity in rat's brain and sciatic nerve.

The study aimed to investigate the harmful effects of acrylamide (AA), which forms in carbohydrate-rich foods at temperatures above 120°C, on the central and peripheral nervous systems and to evaluate the potential neuroprotective effects of carvacrol (CRV). Male Wistar Albino rats were subjected to AA (40 mg/kg/bw/day) and CRV (50 mg/kg/bw/day) for 15 days. Following the last administration, evaluations revealed disrupted gait, heightened thermal sensitivity and altered paw withdrawal thresholds in AA-exposed rats. Notably, AA reduced glutathione (GSH) and raised malondialdehyde (MDA) levels in both brain and sciatic nerve tissues. AA raised nuclear factor erythroid 2-related factor 2 (Nrf2), caspase 3 and nuclear factor κB (NF-κB) gene expressions while decreasing NR4A2. CRV co-administration mitigated gait abnormalities, elevated GSH levels and lowered MDA levels in both tissues. CRV also modulated gene expression, reducing Nrf2 and NF-κB while increasing NR4A2. Histopathological signs of AA-induced neurodegeneration and elevated glial fibrillary acidic protein levels observed in brain and sciatic nerve tissues were rectified with simultaneous administration of CRV, thereby demonstrating neuroprotective efficacy in both regions. This study is pioneering in demonstrating CRV's neuroprotective potential against AA-induced neurotoxicity in both central and peripheral nervous systems, effectively addressing limitations in the literature. In conclusion, the study revealed AA-induced neurodegeneration in the brain and sciatic nerve, with CRV significantly mitigating this neurotoxicity. This novel research underscores CRV's promise as a neuroprotective agent against AA-induced adverse effects in both the central and peripheral nervous systems.

Phase-specific differential regulation of mechanical allodynia in a murine model of neuropathic pain by progesterone.

Progesterone has been shown to have neuroprotective capabilities against a wide range of nervous system injuries, however there are negative clinical studies that have failed to demonstrate positive effects of progesterone therapy. Specifically, we looked into whether progesterone receptors or its metabolizing enzymes, cytochrome P450c17 and 5α-reductase, are involved in the effects of progesterone on neuropathic pain after chronic constriction injury (CCI) of the sciatic nerve in mice. Intrathecal progesterone administration during the induction phase of chronic pain enhanced mechanical allodynia development and spinal glial fibrillary acidic protein (GFAP) expression, and this enhancement was inhibited by administration of ketoconazole, a P450c17 inhibitor, but not finasteride, a 5α-reductase inhibitor. Furthermore, phospho-serine levels of P450c17 in the spinal cord were elevated on day 1 after CCI operation, but not on day 17. In contrast, intrathecal progesterone administration during the maintenance phase of chronic pain decreased the acquired pain and elevated GFAP expression; this inhibition was restored by finasteride administration, but not by ketoconazole. The modification of mechanical allodynia brought on by progesterone in CCI mice was unaffected by the administration of mifepristone, a progesterone receptor antagonist. Collectively, these findings imply that progesterone suppresses spinal astrocyte activation via 5α-reductase activity during the maintenance phase of chronic pain and has an analgesic impact on the mechanical allodynia associated with the growing neuropathy. Progesterone, however, stimulates spinal astrocytes during the induction stage of peripheral neuropathy and boosts the allodynic impact caused by CCI through early spinal P450c17 activation.

High risk of obstructive sleep apnoea is associated with higher baseline plasma glial fibrillary acidic protein and predicts decline in levels over time in cognitively unimpaired older adults

AbstractBackgroundFindings from animal studies report links between obstructive sleep apnoea (OSA) models and elevated glial fibrillary acidic protein (GFAP). In humans, elevated plasma GFAP, reflecting reactive astrogliosis, is considered an early event in the Alzheimer’s disease (AD) continuum. The current study investigated whether OSA risk predicts the slope of plasma GFAP in cognitively unimpaired older adults.MethodLinear mixed effect model analyses were conducted on 70 cognitively unimpaired older adult (M = 73.1, SD = 5.2, 57.1% female) participants of the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Ageing. Individuals completed the well‐validated STOP‐Bang questionnaire to assess OSA risk (Low; Intermediate; High), and underwent positron emission tomography (PET) to quantify brain Aβ burden. Plasma GFAP was measured using the Simoa® platform over three timepoints (range 30.06 ‐ 99.45 months). The model included, a random intercept, a three‐way interaction between OSA risk, baseline brain Aβ status and time, adjusting for Apolipoprotein E (APOE) ε4 status, sex, baseline age, and baseline body mass index.ResultHigh risk of OSA and high brain Aβ (>25 Centiloids) were independently associated with higher baseline plasma GFAP and forecast a negative longitudinal plasma GFAP trajectory.ConclusionThese novel findings suggest that OSA mechanisms, independent of prior brain Aβ accumulation, may contribute to early reactive astrogliosis in cognitively unimpaired older adults. Additionally, a decline in plasma GFAP was observed during the preclinical period, both in those at high risk of OSA and those at greater risk of AD due to high brain Aβ.

Plasma glial fibrillary acidic protein is associated with concomitant brain β‐amyloid in Lewy body disease

AbstractBackgroundWhile α‐synuclein (αSyn) is the primary pathology associated with Lewy body spectrum disorders (LBSD), concomitant Alzheimer’s disease (AD) pathology is common and is predictive of clinical outcomes, including worse cognitive impairment and shorter survival. Thus, AD plasma biomarkers may help identify clinically relevant co‐pathology in LBSD to improve prognosis and clinical management. Plasma phosphorylated tau 181 (p‐tau181) and glial fibrillary acidic protein (GFAP) are two biomarkers that have been well‐studied in canonical AD, showing reliable increases with AD neuropathological change (ADNC). However, their utility in autopsy‐confirmed LBSD is relatively untested.MethodIn autopsy‐confirmed LBSD with a neuropathological diagnosis of αSyn, we tested how plasma p‐tau181 and GFAP differed across αSyn with concomitant ADNC (αSyn+AD; n = 19) and αSyn without AD (αSyn; n = 30). αSyn+AD was defined by intermediate/high ADNC and αSyn had no/low ADNC; cognitively normal controls and AD without αSyn were included as reference groups (Table 1). Severity of burden was scored on a semi‐quantitative scale for β‐amyloid and tau, and scores were averaged across sampled brainstem, limbic, and neocortical regions. Plasma analytes were log‐transformed in linear models, and models covaried for plasma‐to‐death, age at plasma, and sex. Receiver operating characteristic (ROC) analyses and area under the curve (AUC) tested diagnostic utility of plasma analytes.ResultPlasma GFAP was significantly higher in αSyn+AD compared to αSyn (Figure 1), confirmed by linear models (β = 0.31, 95%CI = 0.065 – 0.56, p = 0.015); plasma p‐tau181 was not (p = 0.37). Next, linear models tested associations of AD pathological hallmarks with both plasma analytes. GFAP was significantly associated with brain β‐amyloid (β = 15, 95%CI = 6.1 – 25, p = 0.0018) and tau burden (β = 12, 95%CI = 2.5 – 22, p = 0.015); in the same model plasma p‐tau181 was not associated with either (both p>0.34). ROC analyses showed that neither analyte had an AUC>0.80 (Figure 2); GFAP had somewhat higher AUC of ADNC in LBSD (0.71; 90%CI = 0.58 – 0.83) than plasma p‐tau181 (AUC = 0.64; 90%CI = 0.50 – 0.77).ConclusionResults demonstrate elevated plasma GFAP in LBSD with concomitant AD pathology, in association with accumulation of β‐amyloid plaques. Findings highlight the importance of validating utility of AD biomarkers in LBSD, and the need for plasma biomarker strategies to detect concomitant AD in LBSD.

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).

Clinical and biological relevance of glial fibrillary acidic protein in Alzheimer’s disease

IntroductionThere is a tremendous need for identifying reliable blood-based biomarkers for Alzheimer’s disease (AD) that are tied to the biological ATN (amyloid, tau and neurodegeneration) framework as well as clinical assessment and progression.MethodsOne hundred forty-four elderly participants underwent 18F-AV45 positron emission tomography (PET) scan, structural magnetic resonance imaging (MRI) scan, and blood sample collection. The composite standardized uptake value ratio (SUVR) was derived from 18F-AV45 PET to assess brain amyloid burden, and the hippocampal volume was determined from structural MRI scans. Plasma glial fibrillary acidic protein (GFAP), phosphorylated tau-181 (ptau-181), and neurofilament light (NfL) measured by single molecular array (SIMOA) technology were assessed with respect to ATN framework, genetic risk factor, age, clinical assessment, and future functional decline among the participants.ResultsAmong the three plasma markers, GFAP best discriminated participants stratified by clinical diagnosis and brain amyloid status. Age was strongly associated with NfL, followed by GFAP and ptau-181 at much weaker extent. Brain amyloid was strongly associated with plasma GFAP and ptau-181 and to a lesser extent with plasma NfL. Moderate association was observed between plasma markers. Hippocampal volume was weakly associated with all three markers. Elevated GFAP and ptau-181 were associated with worse cognition, and plasma GFAP was the most predictive of future functional decline. Combining GFAP and ptau-181 together was the best model to predict brain amyloid status across all participants (AUC = 0.86) or within cognitively impaired participants (AUC = 0.93); adding NfL as an additional predictor only had a marginal improvement.ConclusionOur findings indicate that GFAP is of potential clinical utility in screening amyloid pathology and predicting future cognitive decline. GFAP, NfL, and ptau-181 were moderately associated with each other, with discrepant relevance to age, sex, and AD genetic risk, suggesting their relevant but differential roles for AD assessment. The combination of GFAP with ptau-181 provides an accurate model to predict brain amyloid status, with the superior performance of GFAP over ptau-181 when the prediction is limited to cognitively impaired participants.

Elevated biomarkers of neural injury in older adults following head-down bed rest: links to cardio-postural deconditioning with spaceflight and aging.

Prolonged physical inactivity with bed rest or spaceflight is associated with cardiovascular and neuromuscular deconditioning; however, its impact on neural integrity of cardio-postural reflexes and possible mitigation with exercise has not been examined. We assessed the association between the physiological deconditioning of bed rest immobilization with neural injury markers and the effects of 60-75 min of daily exercise. Data were collected as part of a randomized clinical trial (clinicaltrials.gov identifier: NCT04964999) at the McGill University Medical Centre. Twenty-two 55- to 65-year-old healthy volunteers gave informed consent and took part. Within sex, participants were randomly assigned to exercise (60- to 75-min daily) or control (inactive) groups and spent 14 days in continuous 6° head-down tilt. Neural injury [neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), total tau (t-Tau), myelin basic protein (MBP), brain-derived neurotrophic factor (BDNF), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1)], as well as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and insulin-like growth factor 1 (IGF-1) biomarkers were measured before, during, and after bed rest. The false discovery rate with Huber M-estimation was used to correlate changes in biomarkers with cardiovascular and muscular function changes over bed rest. Bed rest elevated NfL, GFAP, TNF-α, and IL-6 in all participants and reduced IGF-1 in females only. With standing, changes in heart rate, blood pressure, and lower limb muscle motoneuron activity correlated with changes in TNF-α and BDNF. Baroreflex control, leg muscle maximal voluntary contraction, and postural sway are correlated with GFAP and NfL. Exercise participants had fewer interactions than control participants, but significant correlations still existed, with both groups exhibiting similar reductions in orthostatic tolerance. An hour of daily exercise in older persons otherwise immobilized for 2 weeks did not abate bed rest-induced increases in serum signatures of neural injury or pro-inflammatory markers. Exercise reduced the number of physiological interactions of biomarkers, but significant cardio-postural correlations remained with no protection against post-bed rest orthostatic intolerance. The identification of associations of inflammatory and neural injury biomarkers with changes in cardio-postural physiology and exercise points to biotherapeutic opportunities and improved exercise interventions for astronauts and individuals in bed rest. https://www.clinicaltrials.gov/search?cond=NCT04964999, identifier: NCT04964999.

Central nervous system biomarkers GFAp and NfL associate with post-acute cognitive impairment and fatigue following critical COVID-19

A high proportion of patients with coronavirus disease 2019 (COVID-19) experience post-acute COVID-19, including neuropsychiatric symptoms. Objective signs of central nervous system (CNS) damage can be investigated using CNS biomarkers such as glial fibrillary acidic protein (GFAp), neurofilament light chain (NfL) and total tau (t-tau). We have examined whether CNS biomarkers can predict fatigue and cognitive impairment 3–6 months after discharge from the intensive care unit (ICU) in critically ill COVID-19 patients. Fifty-seven COVID-19 patients admitted to the ICU were included with analysis of CNS biomarkers in blood at the ICU and at follow up. Cognitive dysfunction and fatigue were assessed with the Montreal Cognitive Assessment (MoCA) and the Multidimensional Fatigue inventory (MFI-20). Elevated GFAp at follow-up 3–6 months after ICU discharge was associated to the development of mild cognitive dysfunction (p = 0.01), especially in women (p = 0.005). Patients who experienced different dimensions of fatigue at follow-up had significantly lower GFAp in both the ICU and at follow-up, specifically in general fatigue (p = 0.009), physical fatigue (p = 0.004), mental fatigue (p = 0.001), and reduced motivation (p = 0.001). Women showed a more pronounced decrease in GFAp compared to men, except for in mental fatigue where men showed a more pronounced GFAp decrease compared to women. NfL concentration at follow-up was lower in patients who experienced reduced motivation (p = 0.004). Our findings suggest that GFAp and NfL are associated with neuropsychiatric outcome after critical COVID-19.Trial registration The study was registered à priori (clinicaltrials.gov: NCT04316884 registered on 2020-03-13 and NCT04474249 registered on 2020-06-29).

Plasma biomarkers of neurodegeneration in mild cognitive impairment with Lewy bodies.

Blood biomarkers of Alzheimer's disease (AD) may allow for the early detection of AD pathology in mild cognitive impairment (MCI) due to AD (MCI-AD) and as a co-pathology in MCI with Lewy bodies (MCI-LB). However not all cases of MCI-LB will feature AD pathology. Disease-general biomarkers of neurodegeneration, such as glial fibrillary acidic protein (GFAP) or neurofilament light (NfL), may therefore provide a useful supplement to AD biomarkers. We aimed to compare the relative utility of plasma Aβ42/40, p-tau181, GFAP and NfL in differentiating MCI-AD and MCI-LB from cognitively healthy older adults, and from one another. Plasma samples were analysed for 172 participants (31 healthy controls, 48 MCI-AD, 28 possible MCI-LB and 65 probable MCI-LB) at baseline, and a subset (n = 55) who provided repeated samples after ≥1 year. Samples were analysed with a Simoa 4-plex assay for Aβ42, Aβ40, GFAP and NfL, and incorporated previously-collected p-tau181 from this same cohort. Probable MCI-LB had elevated GFAP (p < 0.001) and NfL (p = 0.012) relative to controls, but not significantly lower Aβ42/40 (p = 0.06). GFAP and p-tau181 were higher in MCI-AD than MCI-LB. GFAP discriminated all MCI subgroups, from controls (AUC of 0.75), but no plasma-based marker effectively differentiated MCI-AD from MCI-LB. NfL correlated with disease severity and increased with MCI progression over time (p = 0.011). Markers of AD and astrocytosis/neurodegeneration are elevated in MCI-LB. GFAP offered similar utility to p-tau181 in distinguishing MCI overall, and its subgroups, from healthy controls.

Development of an ultrasensitive microfluidic assay for the analysis of Glial fibrillary acidic protein (GFAP) in blood.

Introduction: A rapid and reliable detection of glial fibrillary acidic protein (GFAP) in biological samples could assist in the diagnostic evaluation of neurodegenerative disorders. Sensitive assays applicable in the routine setting are needed to validate the existing GFAP tests. This study aimed to develop a highly sensitive and clinically applicable microfluidic immunoassay for the measurement of GFAP in blood. Methods: A microfluidic GFAP assay was developed and validated regarding its performance. Subsequently, serum and cerebrospinal fluid (CSF) of Alzheimer's disease (AD), Multiple Sclerosis (MS) and control patients were analyzed with the established assay, and levels were compared to the commercial GFAP Simoa discovery kit. Results: The developed GFAP assay showed a good performance with a recovery of 85% of spiked GFAP in serum and assay variations below 15%. The established assay was highly sensitive with a calculated lower limit of quantification and detection of 7.21pg/mL and 2.37pg/mL, respectively. GFAP levels were significantly increased in AD compared to control patients with advanced age (p = 0.002). However, GFAP levels revealed no significant increase in MS compared to control patients in the same age range (p = 0.140). Furthermore, serum GFAP levels evaluated with the novel microfluidic assay strongly correlated with Simoa concentrations (r = 0.88 (95% CI: 0.81-0.93), p < 0.0001). Conclusion: We successfully developed a sensitive and easy-to-use microfluidic assay to measure GFAP in blood. Furthermore, we could confirm previous findings of elevated GFAP levels in AD by applying the assay in a cohort of clinically characterized patients.

Nanoporous Carbon Immunosensor for Highly Accurate and Sensitive Clinical Detection of Glial Fibrillary Acidic Protein in Traumatic Brain Injury, Stroke, and Spinal Cord Injury.

Elevated glial fibrillary acidic protein (GFAP) in the blood serum is one of the promising bodily fluid markers for the diagnosis of central nervous system (CNS) injuries, including traumatic brain injury (TBI), stroke, and spinal cord injury (SCI). However, accurate and point-of-care (POC) quantification of GFAP in clinical blood samples has been challenging and yet to be clinically validated against gold-standard assays and outcome practices. This work engineered and characterized a novel nanoporous carbon screen-printed electrode with significantly increased surface area and conductivity, as well as preserved stability and anti-fouling properties. This nano-decorated electrode was immobilized with the target GFAP antibody to create an ultrasensitive GFAP immunosensor and quantify GFAP levels in spiked samples and the serum of CNS injury patients. The immunosensor presented a dynamic detection range of 100 fg/mL to 10 ng/mL, a limit of detection of 86.6 fg/mL, and a sensitivity of 20.3 Ω mL/pg mm2 for detecting GFAP in the serum. Its clinical utility was demonstrated by the consistent and selective quantification of GFAP comparable to the ultrasensitive single-molecule array technology in 107 serum samples collected from TBI, stroke, and SCI patients. Comparing the diagnostic and prognostic performance of the immunosensor with the existing clinical paradigms confirms the immunosensor's accuracy as a potential complement to the existing imaging diagnostic modalities and presents a potential for rapid, accurate, cost-effective, and near real-time POC diagnosis and prognosis of CNS injuries.

Somatic Mosaic Pathogenic Variant Gradient Detected in Trace Brain Tissue From Stereo-EEG Depth Electrodes.

Mosaic pathogenic variants restricted to the brain are increasingly recognized as a cause of focal epilepsies. We aimed to identify a mosaic pathogenic variant and its anatomical gradient in brain DNA derived from trace tissue on explanted stereoelectroencephalography (SEEG) electrodes. We studied a patient with nonlesional multifocal epilepsy undergoing presurgical evaluation with SEEG. After explantation, the electrodes were divided into 3 pools based on their brain location (right posterior quadrant, left posterior quadrant, hippocampus/temporal neocortex). Tissue from each pool was processed for trace DNA that was whole genome amplified prior to high-depth exome sequencing. Droplet digital PCR was performed to quantify mosaicism. A brain-specific glial fibrillary acidic protein (GFAP) assay enabled cell-of-origin analysis. We demonstrated a mosaic gradient for a novel pathogenic KCNT1 loss-of-function variant (c.530G>A, p.W177X) predicted to lead to nonsense-mediated decay. Strikingly, the mosaic gradient correlated strongly with the SEEG findings because the highest variant allele frequency was in the right posterior quadrant, reflecting the most epileptogenic region on EEG studies. An elevated GFAP level indicated enrichment of brain-derived cells in SEEG cell suspension. This study demonstrates a proof of concept that mosaic gradients of pathogenic variants can be established using trace tissue from explanted SEEG electrodes.

Serum glial fibrillary acidic protein (GFAP) predicts outcome after intracerebral and subarachnoid hemorrhage.

Intracerebral and subarachnoid hemorrhage are critical conditions with a high mortality, and the outcome for the individual patient is notoriously difficult to predict. Biomarkers that reflect disease severity and predict outcome are therefore warranted. Blood samples from 40 patients with intracerebral, 46 patients with subarachnoid hemorrhage, and 70 healthy individuals were collected. Levels of glial fibrillary acidic protein (GFAP) and neuroglobin were measured by ultra-sensitive single molecule array and enzyme-linked immunosorbent assay, respectively. Clinical information including mortality and functional outcome was recorded. Blood levels of GFAP and neuroglobin in intracerebral and subarachnoid hemorrhage patients were significantly elevated when compared to healthy individuals (all p < 0.0001). GFAP levels were significantly higher in patients dying or with poor functional outcome than in healthy individuals (all p ≤ 0.01). GFAP levels separated survivors from non-survivors with an area under receiver operating characteristics (AUROC) = 0.78 (confidence interval (CI) 0.59-0.98) for intracerebral hemorrhage and 0.82 (CI 0.69-0.94) for subarachnoid hemorrhage patients. The Akaike and Bayesian information criteria (AIC/BIC) for mortality/poor outcome prediction improved when combining GFAP levels with hematoma volume (p = 0.04/p < 0.01), National Institutes of Health Stroke Scale (NIHSS) (p = 0.09/p < 0.01), Hunt-Hess (p < 0.05/p = 0.21), or Fischer score (p < 0.05/p = 0.02). Elevated GFAP levels at admission to hospital predicted mortality and poor outcome in our cohort of intracerebral and subarachnoid hemorrhage patients. Neuroglobin levels did not provide additional information. Combining GFAP measurements with clinical disease severity scores increased outcome prediction precision. This may suggest that GFAP measurement could improve prognostication in patients with intracerebral or subarachnoid hemorrhage. This sub-trial was not registered.

Plasma Aβ42/40 ratio, p-tau181, GFAP, and NfL across the Alzheimer's disease continuum: A cross-sectional and longitudinal study in the AIBL cohort.

Plasma amyloid beta (Aβ)1-42/Aβ1-40 ratio, phosphorylated-tau181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) are putative blood biomarkers for Alzheimer's disease (AD). However, head-to-head cross-sectional and longitudinal comparisons of the aforementioned biomarkers across the AD continuum are lacking. Plasma Aβ1-42, Aβ1-40, p-tau181, GFAP, and NfL were measured utilizing the Single Molecule Array (Simoa) platform and compared cross-sectionally across the AD continuum, wherein Aβ-PET (positron emission tomography)-negative cognitively unimpaired (CU Aβ-, n = 81) and mild cognitive impairment (MCI Aβ-, n = 26) participants were compared with Aβ-PET-positive participants across the AD continuum (CU Aβ+, n = 39; MCI Aβ+, n = 33; AD Aβ+, n = 46) from the Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing (AIBL) cohort. Longitudinal plasma biomarker changes were also assessed in MCI (n = 27) and AD (n = 29) participants compared with CU (n = 120) participants. In addition, associations between baseline plasma biomarker levels and prospective cognitive decline and Aβ-PET load were assessed over a 7 to 10-year duration. Lower plasma Aβ1-42/Aβ1-40 ratio and elevated p-tau181 and GFAP were observed in CU Aβ+, MCI Aβ+, and AD Aβ+, whereas elevated plasma NfL was observed in MCI Aβ+ and AD Aβ+, compared with CU Aβ- and MCI Aβ-. Among the aforementioned plasma biomarkers, for models with and without AD risk factors (age, sex, and apolipoprotein E (APOE) ε4 carrier status), p-tau181 performed equivalent to or better than other biomarkers in predicting a brain Aβ-/+ status across the AD continuum. However, for models with and without the AD risk factors, a biomarker panel of Aβ1-42/Aβ1-40, p-tau181, and GFAP performed equivalent to or better than any of the biomarkers alone in predicting brain Aβ-/+ status across the AD continuum. Longitudinally, plasma Aβ1-42/Aβ1-40, p-tau181, and GFAP were altered in MCI compared with CU, and plasma GFAP and NfL were altered in AD compared with CU. In addition, lower plasma Aβ1-42/Aβ1-40 and higher p-tau181, GFAP, and NfL were associated with prospective cognitive decline and lower plasma Aβ1-42/Aβ1-40, and higher p-tau181 and GFAP were associated with increased Aβ-PET load prospectively. These findings suggest that plasma biomarkers are altered cross-sectionally and longitudinally, along the AD continuum, and are prospectively associated with cognitive decline and brain Aβ-PET load. In addition, although p-tau181 performed equivalent to or better than other biomarkers in predicting an Aβ-/+ status across the AD continuum, a panel of biomarkers may have superior Aβ-/+ status predictive capability across the AD continuum. Area under the curve (AUC) of p-tau181 ≥ AUC of Aβ42/40, GFAP, NfL in predicting PET Aβ-/+ status (Aβ-/+). AUC of Aβ42/40+p-tau181+GFAP panel ≥ AUC of Aβ42/40/p-tau181/GFAP/NfL for Aβ-/+. Longitudinally, Aβ42/40, p-tau181, and GFAP were altered in MCI versus CU. Longitudinally, GFAP and NfL were altered in AD versus CU. Aβ42/40, p-tau181, GFAP, and NfL are associated with prospective cognitive decline. Aβ42/40, p-tau181, and GFAP are associated with increased PET Aβ load prospectively.

Small Fiber Pathology in CADASIL: Clinical Correlation With Cognitive Impairment.

This study investigated the cutaneous small fiber pathology of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and its clinical significance, that is, the NOTCH3 deposition in cutaneous vasculatures and CNS neurodegeneration focusing on cognitive impairment. Thirty-seven patients with CADASIL and 59 age-matched healthy controls were enrolled to evaluate cutaneous small fiber pathology by quantitative measures of intraepidermal nerve fiber density (IENFD), sweat gland innervation, and vascular innervation. Cognitive performance of patients with CADASIL was evaluated by a comprehensive neuropsychological assessment, and its association with small fiber pathology was tested using multivariable linear regression analysis adjusted for age and diabetes mellitus. We further assessed the relationships of IENFD with cutaneous vascular NOTCH3 ectodomain (NOTCH3ECD) deposition and biomarkers of neurodegeneration including structural brain MRI measures, serum neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), tau, and ubiquitin carboxy-terminal hydrolase L1. Patients with CADASIL showed reduced IENFD (5.22 ± 2.42 vs 7.88 ± 2.89 fibers/mm, p = 0.0001) and reduced sweat gland (p < 0.0001) and vascular (p < 0.0001) innervations compared with age-matched controls. Reduced IENFD was associated with impaired global cognition measured by Mini-Mental State Examination (B = 1.062, 95% CI = 0.370-1.753, p = 0.004), and this association remained after adjustment for age and diabetes mellitus (p = 0.043). In addition, IENFD in patients with CADASIL was associated with mean cortical thickness (Pearson r = 0.565, p = 0.0023) but not white matter hyperintensity volume, total lacune count, or total microbleed count. Reduced IENFD was associated with cutaneous vascular NOTCH3ECD deposition amount among patients harboring pathogenic variants in exon 11 (mainly p.R544C) (B = -0.092, 95% CI = -0.175 to -0.009, p = 0.031). Compared with those with normal cognition, patients with CADASIL with cognitive impairment had an elevated plasma NfL level regardless of concurrent small fiber denervation, whereas only patients with both cognitive impairment and small fiber denervation showed an elevated plasma GFAP level. Cutaneous small fiber pathology correlates with cognitive impairment and CNS neurodegeneration in patients with CADASIL, indicating a peripheral neurodegenerative process related to NOTCH3ECD aggregation.