Fluid Glial Fibrillary Acidic Protein Research Articles

Elevated cerebrospinal fluid glial fibrillary acidic protein levels in Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS) is a rare, multiple malformation/intellectual disability disorder caused by pathogenic variants of DHCR7. DHCR7 catalyzes the reduction of 7-dehydrocholesterol (7DHC) to cholesterol in the final step of cholesterol biosynthesis. This results in accumulation of 7DHC and a cholesterol deficiency. Although the biochemical defect is well delineated and multiple mechanisms underlying developmental defects have been explored, the post developmental neuropathological consequences of altered central nervous system sterol composition have not been studied. Preclinical studies suggest that astroglial activation may occur in SLOS. To determine if astroglial activation is present in individuals with SLOS, we quantified cerebrospinal fluid (CSF) glial fibrillary acidic protein using a Quanterix Simoa® GFAP Discovery Kit for SR-X™. Relative to an age-appropriate comparison group, we found that CSF GFAP levels were elevated 3.9-fold in SLOS (3980 ± 3732 versus 1010 ± 577 pg/ml, p = 0.0184). Simvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, has previously been shown to increase expression of hypomorphic DHCR7 alleles and in a placebo-controlled trial improved serum sterol levels and decreased irritability. Using archived CSF samples from that prior study, we observed a significant decrease (p = 0.0119) in CSF GFAP levels in response to treatment with simvastatin. Although further work needs to be done to understand the potential contribution of neuroinflammation to SLOS neuropathology and cognitive dysfunction, these data confirm astroglial activation in SLOS and suggest that CSF GFAP may be a useful biomarker to monitor therapeutic responses.

Cerebrospinal fluid glial fibrillary acidic protein, in contrast to amyloid beta protein, is associated with disease symptoms in Huntington's disease

IntroductionHuntington's disease (HD) is a hereditary neurodegenerative disease, currently lacking disease-modifying treatments. Biomarkers are needed for objective assessment of disease progression. Evidence supports both complex protein aggregation and astrocyte activation in HD. This study assesses the 42 amino acid long amyloid beta (Aβ42) and glial fibrillary acidic protein (GFAP) as potential biomarkers in the cerebrospinal fluid (CSF) of HD mutation carriers. MethodsCSF from participants was obtained from three sites in Sweden. Clinical symptoms were graded with the composite Unified Huntington's disease rating scale (cUHDRS). Protein concentrations were measured using ELISA. Pearson correlations were calculated to assess disease progression association. Results were adjusted for age and collection site. ResultsThe study enrolled 28 manifest HD patients (ManHD), 13 premanifest HD gene-expansion carriers (PreHD) and 20 controls. Aβ42 levels did not differ between groups and there was no correlation with measures of disease progression.GFAP concentration was higher in ManHD (424 ng/l, SD 253) compared with both PreHD (266 ng/l, SD 92.4) and controls (208 ng/l, SD 83.7). GFAP correlated with both cUHDRS (r = −0.77, p < 0.001), and 5-year risk of disease onset (r = 0.70, p = 0.008). ConclusionWe provide evidence that indicates CSF Aβ42 has limited potential as a biomarker for HD. GFAP is a potential biomarker of progression in HD. Validation in larger cohorts measuring GFAP in blood and CSF would be of interest.

Cerebrospinal fluid GFAP is a predictive biomarker for conversion to dementia and Alzheimer’s disease-associated biomarkers alterations among de novo Parkinson’s disease patients: a prospective cohort study

BackgroundDementia is a prevalent non-motor manifestation among individuals with advanced Parkinson’s disease (PD). Glial fibrillary acidic protein (GFAP) is an inflammatory marker derived from astrocytes. Research has demonstrated the potential of plasma GFAP to forecast the progression to dementia in PD patients with mild cognitive impairment (PD–MCI). However, the predictive role of cerebrospinal fluid (CSF) GFAP on future cognitive transformation and alterations in Alzheimer’s disease (AD)-associated CSF biomarkers in newly diagnosed PD patients has not been investigated.Methods210 de novo PD patients from the Parkinson’s Progression Markers Initiative were recruited. Cognitive progression in PD participants was evaluated using Cox regression. Cross-sectional and longitudinal associations between baseline CSF GFAP and cognitive function and AD-related CSF biomarkers were evaluated using multiple linear regression and generalized linear mixed model.ResultsAt baseline, the mean age of PD participants was 60.85 ± 9.78 years, including 142 patients with normal cognition (PD–NC) and 68 PD–MCI patients. The average follow-up time was 6.42 ± 1.69 years. A positive correlation was observed between baseline CSF GFAP and age (β = 0.918, p < 0.001). There was no statistically significant difference in baseline CSF GFAP levels between PD–NC and PD–MCI groups. Higher baseline CSF GFAP predicted greater global cognitive decline over time in early PD patients (Montreal Cognitive Assessment, β = − 0.013, p = 0.014). Furthermore, Cox regression showed that high baseline CSF GFAP levels were associated with a high risk of developing dementia over an 8-year period in the PD–NC group (adjusted HR = 3.070, 95% CI 1.119–8.418, p = 0.029). In addition, the baseline CSF GFAP was positively correlated with the longitudinal changes of not only CSF α-synuclein (β = 0.313, p < 0.001), but also CSF biomarkers associated with AD, namely, amyloid-β 42 (β = 0.147, p = 0.034), total tau (β = 0.337, p < 0.001) and phosphorylated tau (β = 0.408, p < 0.001).ConclusionsCSF GFAP may be a valuable prognostic tool that can predict the severity and progression of cognitive deterioration, accompanied with longitudinal changes in AD-associated pathological markers in early PD.

Plasma and cerebrospinal fluid glial fibrillary acidic protein levels in adults with Down syndrome: a longitudinal cohort study.

The diagnosis of symptomatic Alzheimer's disease is a clinical challenge in adults with Down syndrome. Blood biomarkers would be of particular clinical importance in this population. The astrocytic Glial Fibrillary Acidic Protein (GFAP) is a marker of astrogliosis associated with amyloid pathology, but its longitudinal changes, association with other biomarkers and cognitive performance have not been studied in individuals with Down syndrome. We performed a three-centre study of adults with Down syndrome, autosomal dominant Alzheimer's disease and euploid individuals enrolled in Hospital Sant Pau, Barcelona (Spain), Hospital Clinic, Barcelona (Spain) and Ludwig-Maximilians-Universität, Munich (Germany). Cerebrospinal fluid (CSF) and plasma GFAP concentrations were quantified using Simoa. A subset of participants had PET 18F-fluorodeoxyglucose, amyloid tracers and MRI measurements. This study included 997 individuals, 585 participants with Down syndrome, 61 Familial Alzheimer's disease mutation carriers and 351 euploid individuals along the Alzheimer's disease continuum, recruited between November 2008 and May 2022. Participants with Down syndrome were clinically classified at baseline as asymptomatic, prodromal Alzheimer's disease and Alzheimer's disease dementia. Plasma GFAP levels were significantly increased in prodromal and Alzheimer's disease dementia compared to asymptomatic individuals and increased in parallel to CSF Aβ changes, ten years prior to amyloid PET positivity. Plasma GFAP presented the highest diagnostic performance to discriminate symptomatic from asymptomatic groups (AUC=0.93, 95% CI 0.9-0.95) and its concentrations were significantly higher in progressors vs non-progressors (p<0.001), showing an increase of 19.8% (11.8-33.0) per year in participants with dementia. Finally, plasma GFAP levels were highly correlated with cortical thinning and brain amyloid pathology. Our findings support the utility of plasma GFAP as a biomarker of Alzheimer's disease in adults with Down syndrome, with possible applications in clinical practice and clinical trials. AC Immune, La Caixa Foundation, Instituto de Salud Carlos III, National Institute on Aging, Wellcome Trust, Jérôme Lejeune Foundation, Medical Research Council, Alzheimer's Association, National Institute for Health Research, EU Joint Programme-Neurodegenerative Disease Research, Alzheimer's Society, Deutsche Forschungsgemeinschaft, Stiftung für die Erforschung von Verhaltens, Fundación Tatiana Pérez de Guzmán el Bueno & European Union's Horizon 2020 und Umwelteinflüssen auf die menschliche Gesundheit.

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.

Plasma glial fibrillary acidic protein in autosomal dominant Alzheimer's disease: Associations with Aβ-PET, neurodegeneration, and cognition.

Glial fibrillary acidic protein (GFAP) is a promising candidate blood-based biomarker for Alzheimer's disease (AD) diagnosis and prognostication. The timing of its disease-associated changes, its clinical correlates, and biofluid-type dependency will influence its clinical utility. We evaluated plasma, serum, and cerebrospinal fluid (CSF) GFAP in families with autosomal dominant AD (ADAD), leveraging the predictable age at symptom onset to determine changes by stage of disease. Plasma GFAP elevations appear a decade before expected symptom onset, after amyloid beta (Aβ) accumulation and prior to neurodegeneration and cognitive decline. Plasma GFAP distinguished Aβ-positive from Aβ-negative ADAD participants and showed a stronger relationship with Aβ load in asymptomatic than symptomatic ADAD. Higher plasma GFAP was associated with the degree and rate of neurodegeneration and cognitive impairment. Serum GFAP showed similar relationships, but these were less pronounced for CSF GFAP. Our findings support a role for plasma GFAP as a clinical biomarker of Aβ-related astrocyte reactivity that is associated with cognitive decline and neurodegeneration. Plasma glial fibrillary acidic protein (GFAP) elevations appear a decade before expected symptom onset in autosomal dominant Alzheimer's disease (ADAD). Plasma GFAP was associated to amyloid positivity in asymptomatic ADAD. Plasma GFAP increased with clinical severity and predicted disease progression. Plasma and serum GFAP carried similar information in ADAD, while cerebrospinal fluid GFAP did not.

Comparison between plasma, serum and cerebrospinal fluid glial fibrillary acidic protein in Alzheimer’s Disease and Dementia with Lewy bodies and the effect of age and sex on diagnostic performance

AbstractBackgroundGlial fibrillary acidic protein (GFAP) is a novel Alzheimer’s Disease (AD) biomarker that associates with amyloid pathology and pathology‐related changes can be detected in different biofluids. We studied how the performance of GFAP to distinguish between controls, AD and dementia with Lewy bodies (DLB), depends on the studied biofluid (cerebrospinal fluid (CSF), serum or plasma) and the confounding effects of age or sex.MethodFrom the Amsterdam Dementia Cohort and a local repository of healthy controls we included 372 cognitively normal individuals (CN), 255 patients with AD and 120 patients with DLB (Table 1) and GFAP levels were measured in one (n=322), two (n=416) or three (n=9) biofluids. GFAP was measured using Simoa in CSF (n=473), plasma (n=257) and serum (n=451) samples. For individuals with DLB, GFAP was measured in CSF and serum only. Effects of clinical diagnosis, age and sex on GFAP levels in each body fluid were estimated with linear models. Estimated differences between diagnostic groups were corrected for age and sex, age effects were corrected for sex and diagnostic group, and sex effects were corrected for age and diagnostic group.ResultGFAP levels were increased in AD relative to controls in all biofluids (fold change (FC): 1.6(CSF), 1.9(plasma) and 1.4(serum), p‐values&lt;0.001) and increased in AD relative to DLB (FC: 1.7(CSF) and 1.3(serum), p‐values&lt;0.001, Figure 1). No difference was found between DLB and controls. CSF GFAP levels increased with age in all clinical groups (range of standard deviation protein level increase per year (SD/year): 0.020‐0.024), while plasma GFAP levels increased with age only in CN (SD/year: 0.032). Serum GFAP levels increased with age in CN and DLB (SD/year: 0.058(CN) and 0.074(DLB), Figure 2). CSF GFAP showed sex effects in AD only (FC in males compared to females: 1.1), whereas serum GFAP showed sex effects in all clinical groups (FC in males: 0.83(AD), 0.85(NC) and 0.72(DLB)), and plasma GFAP showed no sex effects (Figure 3A‐C).ConclusionDifferences in GFAP levels between clinical diagnoses showed the same trend for all three matrices. With older age, differences in GFAP levels between controls and AD become harder to detect.

Cerebrospinal fluid glial fibrillary acidic protein (GFAP) and soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in Alzheimer’s Disease and Related Dementias (ADRD)

AbstractBackgroundDiscerning Dementia with Lewy Bodies (DLB) from Alzheimer's disease (AD) can be a challenge for the clinician and represents a critical unmet medical need. Diagnosis of DLB is especially challenging in early stages due to variable core features and coexistent pathologies such as AD. A variable immune response has been implicated in AD/ADRD. Soluble triggering receptor expressed on myeloid cells 2 (sTREM2), a myeloid cell activity marker, has been genetically linked to AD risk and glial fibrillary acidic protein (GFAP), an astrocyte activity marker, is liked to astrogliosis in a number of neurologic disorders. Our objective was to explore differences in cerebrospinal fluid (CSF) values of both sTREM2 and GFAP in AD/ADRD. This included individuals clinically diagnosed with AD, DLB, mild‐cognitive impairment (MCI), Parkinson’s Disease (PD), and cognitively normal controls (CN).MethodCohorts included participants from the Cleveland Clinic‐based Dementia with Lewy Body Consortium (DLBC), the Lou Ruvo Center for Brain Health Aging and Neurodegenerative Disease biobank (LRCBH‐biobank) and the Cleveland Alzheimer's Disease Research Center (CADRC). Patients were clinically characterized based on CSF biomarkers, clinical symptoms, and consensus review. Analytes measured included: CSF GFAP, CSF sTREM2, CSF a‐synuclein (aSyn) and plasma neurofilament light chain (NfL) using multiple platforms such as the Luminex/Millipore and Meso Scale Discovery systems.ResultIn this AD/ADRD cohort, CSF aSyn was higher in MCI than both PD and DLB, while lower in DLB than CN and AD. CSF sTREM2 was higher in MCI, AD and DLB than CN. GFAP was higher in MCI than either CN or DLB, while AD was higher than DLB. sTREM2/GFAP ratio was higher in DLB than CN, MCI, AD and PD.ConclusionThese findings suggest that inflammatory factors, CSF sTREM2 and GFAP are altered in both AD and DLB. Future study of the relationship between CSF amyloid or tau and the immune response will help tease apart the potential influence of co‐existent AD‐related pathology on inflammatory factors in DLB. The findings will help inform possible immunotherapeutic strategies that seek to target the immune response in AD/ADRD.

Differences between blood and cerebrospinal fluid glial fibrillary Acidic protein levels: The effect of sample stability.

Recent evidence has shown that the marker of reactive astrogliosis, glial fibrillary acidic protein (GFAP), has a stronger relationship with cerebral amyloid beta (Aβ) pathology in blood than in cerebrospinal fluid (CSF). This study investigates if pre-analytical treatment of blood and CSF contribute to these unexpected findings. Paired CSF and serum samples from 49 individuals (Aβ-negative = 28; Aβ-positive = 21) underwent a series of seven freeze-thaw cycles (FTCs). All samples were analyzed for GFAP and neurofilament light (NfL) using single molecule array technology including a fresh unfrozen sample from each patient. FTC significantly affected CSF GFAP concentration (-188.12 pg/ml per FTC) but not serum GFAP. In the same samples, NfL remained stable. Serum GFAP had a higher discrimination of Aβ burden than CSF GFAP, irrespective of FTC, which also included unfrozen samples. This study demonstrates large stability differences of GFAP in CSF and serum. However, this disparity does not seem to fully explain the stronger association of serum GFAP with Aβ pathology. Further work should investigate mechanisms of GFAP release into the bloodstream under pathological conditions.

The value of glial fibrillary acidic protein levels in the diagnosis and prognosis of subarachnoid hemorrhage

Background: Subarachnoid hemorrhages is an important emergency condition due to its high morbidity and mortality. Early diagnosis and rapid intervention are very important to prevent poor clinical outcome of this disease. Objective: The aim of this study was to determine the value of glial fibrillary acidic protein in the diagnosis and prognosis of subarachnoid hemorrhage. Methods: Patients presenting to the emergency department and undergoing computerized tomography and/or lumbar puncture due to suspicion of subarachnoid hemorrhage were included in this prospective study. Based on the computerized tomography–lumbar puncture results, cases were divided into subarachnoid hemorrhage group and non–subarachnoid hemorrhage control group. Subarachnoid hemorrhage patients were classified on the basis of severity of subarachnoid hemorrhage and were classified as good or poor clinical outcome groups based on Glasgow Outcome Scores. Glial fibrillary acidic protein levels were then compared. Results: A total of 111 patients were evaluated due to suspicion of subarachnoid hemorrhage and diagnosed with subarachnoid hemorrhage (n = 73) or without subarachnoid hemorrhage (n = 38). Cerebrospinal fluid glial fibrillary acidic protein levels were significantly higher in the subarachnoid hemorrhage group than in the non–subarachnoid hemorrhage group (p &lt; 0.001) (median (25%–75%): 11.62 (2.64–68.04) and 2.26 (1.5–4.83), respectively). Serum glial fibrillary acidic protein levels of the subarachnoid hemorrhage patients with poor clinical outcomes were higher than those of subarachnoid hemorrhage patients with good clinical outcomes (p = 0.003) and cerebrospinal fluid glial fibrillary acidic protein levels were similar (p = 0.379). Glial fibrillary acidic protein levels at the time of presentation exhibited a low level of correlation with Glasgow coma score, World Federation of Neurological Surgeons scale, Hunter–Hess Scale, Ogilvy–Carter Scale, Glasgow Outcome Score, and modified Rankin score. Conclusion: Cerebrospinal fluid glial fibrillary acidic protein levels may be a valuable diagnostic parameter at the time of presentation for diagnosis of subarachnoid hemorrhage. And also serum glial fibrillary acidic protein levels may be useful in predicting subarachnoid hemorrhage patients with poor clinical outcomes.

Searching for neurodegeneration in multiple sclerosis at clinical onset: Diagnostic value of biomarkers.

BackgroundNeurodegeneration occurs during the early stages of multiple sclerosis. It is an essential, devastating part of the pathophysiology. Tools for measuring the degree of neurodegeneration could improve diagnostics and patient characterization.ObjectiveThis study aimed to determine the diagnostic value of biomarkers of degeneration in patients with recent clinical onset of suspected multiple sclerosis, and to evaluate these biomarkers for characterizing disease course.MethodsThis cross-sectional study included 271 patients with clinical features of suspected multiple sclerosis onset and was the baseline of a prospective study. After diagnostic investigations, the patients were classified into the following disease groups: patients with clinically isolated syndrome (n = 4) or early relapsing remitting multiple sclerosis (early RRMS; n = 93); patients with relapsing remitting multiple sclerosis with disease durations ≥2 years (established RRMS; n = 39); patients without multiple sclerosis, but showing symptoms (symptomatic controls; n = 89); and patients diagnosed with other diseases (n = 46). In addition, we included healthy controls (n = 51) and patients with progressive multiple sclerosis (n = 23). We analyzed six biomarkers of neurodegeneration: cerebrospinal fluid neurofilament light chain levels; cerebral spinal fluid glial fibrillary acidic protein; cerebral spinal fluid tau; retinal nerve fiber layer thickness; macula volume; and the brain parenchymal fraction.ResultsExcept for increased cerebral spinal fluid neurofilament light chain levels, median 670 ng/L (IQR 400–2110), we could not find signs of early degeneration in the early disease group with recent clinical onset. However, the intrathecal immunoglobin G production and cerebral spinal fluid neurofilament light chain levels showed diagnostic value. Moreover, elevated levels of cerebral spinal fluid glial fibrillary acidic protein, thin retinal nerve fiber layers, and low brain parenchymal fractions were associated with progressive disease, but not with the other phenotypes. Thin retinal nerve fiber layers and low brain parenchymal fractions, which indicated neurodegeneration, were associated with longer disease duration.ConclusionsIn clinically suspected multiple sclerosis, intrathecal immunoglobin G production and neurofilament light chain levels had diagnostic value. Therefore, these biomarkers could be included in diagnostic work-ups for multiple sclerosis. We found that the thickness of the retinal nerve fiber layer and the brain parenchymal fraction were not different between individuals that were healthy, symptomatic, or newly diagnosed with multiple sclerosis. This finding suggested that neurodegeneration had not reached a significant magnitude in patients with a recent clinical onset of multiple sclerosis.

Proteins of neural tube defects

Neural tube defects(NTD)are a common congenital malformations in humans leading to infant mortality or severe disability.The etiology of NTD is complicated, with both environmentaland genetic contributions.It has been found that the protein markers associated with NTD are mainly maternal serum alpha fetoprotein, amniotic fluid alpha fetoprotein and amniotic fluid glial fibrillary acidic protein.This article reviews the protein biomarks related with NTD. Key words: Neural tube defects; Maternal serum alpha fetoprotein; Amniotic fluid alpha fetoprotein; Amniotic fluid glial fibrillary acidic protein; S100 protein

Amniotic fluid glial fibrillary acidic protein (AF‐GFAP), a biomarker of open neural tube defects

Neural tube defects (NTDs) are usually identified by ultrasonography and confirmed by alpha-fetoprotein (AFP) assay and acetylcholinesterase (AchE) electrophoresis in amniotic fluid. Yet, both of these biomarkers can be found positive in other etiologies. Here, amniotic fluid glial fibrillary acidic protein (AF-GFAP), which was identified by a proteomic study, is shown to be a useful biomarker for NTD diagnosis. Amniotic fluid glial fibrillary acidic protein was measured by an ELISA assay in 138 cases of NTDs. Seventy samples from normal pregnancies used as controls and 27 samples giving false positive or false negative results either for AchE or AFP and corresponding to fetal death (n = 8), gastroschisis (n = 8), and unexplained etiologies (n = 11) were also tested. Whatever the gestational age, GFAP was below 0.2 ng/mL in control samples, whereas 99.1% of open NTDs (29/29 in the anterior NTD group and 80/81 in the spina bifida group) were above this threshold. Closed NTDs were all negative (28/28). None of the other samples tested were positive, except in case of fetal death (8/8). Amniotic fluid glial fibrillary acidic protein is a sensitive biomarker for open NTD diagnosis with a good negative predictive value for closed NTD. Compared with AFP and AchE, our results indicate that AF-GFAP alone is more efficient than this classical association.

Severe traumatic brain injury in children elevates glial fibrillary acidic protein in cerebrospinal fluid and serum*

1) To determine the levels of glial fibrillary acidic protein (GFAP) in both cerebrospinal fluid and serum; 2) to determine whether serum GFAP levels correlate with functional outcome; and 3) to determine whether therapeutic hypothermia, as compared with normothermia, alters serum GFAP levels in children with severe traumatic brain injury (TBI). Laboratory-based analyses; postrandomized, controlled trial. Four Canadian pediatric intensive care units and a university-affiliated laboratory. Twenty-seven children, aged 2-17 yrs, with severe TBI (Glasgow Coma Scale score of ≤ 8). Hypothermia therapy (32.5°C) for 24 hrs with cooling started within 8 hrs of injury and rewarming at a rate of 0.5°C every 2 hrs or normothermia (37.0°C). GFAP was measured in cerebrospinal fluid and serum, using enzyme-linked immunosorbent assay. Levels of GFAP were maximal on day 1 post-TBI, with cerebrospinal fluid GFAP (15.5 ± 6.1 ng/mL) 25-fold higher than serum GFAP (0.6 ± 0.2 ng/mL). Cerebrospinal fluid GFAP normalized by day 7, whereas serum GFAP decreased gradually to reach a steady state by day 10. Serum GFAP measured on day 1 correlated with Pediatric Cerebral Performance Category scores determined at 6 months post-TBI (ρ = 0.527; p = .008) but failed to correlate with the injury scoring on admission, physiologic variables, or indices of injury measured on computerized tomography imaging. The areas under the receiver operating characteristic curves for pediatric intensive care unit day 1 serum GFAP in determining good outcome were 0.80 (pediatric cerebral performance category, 1-2; normal-mild disability) and 0.91 (pediatric cerebral performance category, 1-3; normal-moderate disability). For a serum GFAP cutoff level of 0.6 ng/mL, sensitivity and specificity were 88% to 90% and 43% to 71%, respectively. Serum GFAP levels were similar among children randomized to either therapeutic hypothermia or normothermia. GFAP was markedly elevated in cerebrospinal fluid and serum in children after severe TBI and serum GFAP measured on pediatric intensive care unit day 1 correlated with functional outcome at 6 months. Hypothermia therapy did not alter serum GFAP levels compared with normothermia after severe TBI in children. Serum GFAP concentration, together with other biomarkers, may have prognostic value after TBI in children.

Analysis of Cerebrospinal Fluid Glial Fibrillary Acidic Protein after Seizures in Children

To evaluate pediatric seizure patients for astrocytic injury by measuring cerebrospinal fluid (CSF) glial fibrillary acidic protein (GFAP), determine risk factors for GFAP elevation after seizures, and compare seizure-induced astrocyte injury with neuronal injury by concurrent measurement of CSF neuron-specific enolase (NSE). CSF obtained from pediatric patients (n = 52) within 24 h of seizure was assayed for GFAP and NSE. Retrospective chart review was performed for seizure type, duration, and etiology. Overall, children with seizures had elevated CSF GFAP compared with controls (p = 0.0075), but no elevation of NSE (p = 0.1437). No effect of seizure type or etiology was found, but a significant positive effect of seizure duration (p = 0.0010) and status epilepticus (p = 0.0296) was seen on CSF GFAP. Individually, seven children (13%) had elevated GFAP (>440 pg/ml); in five children, the increased GFAP was not accompanied by elevations in NSE (<12 ng/ml). Five children with elevated GFAP had symptomatic etiologies for their seizures, but the etiology of one child with elevated GFAP was cryptogenic, and one had febrile seizures. Elevation of CSF GFAP after seizures suggests that astrocytic injury may occur in a subgroup of children, primarily in the context of prolonged seizures and symptomatic etiologies. Increased GFAP levels may occur in patients with normal NSE, suggesting that GFAP may be a more sensitive marker of brain injury in some cases.

Glial Fibrillary Acidic Protein in the Cerebrospinal Fluid: A Possible Indicator of Prognosis in Full-Term Asphyxiated Newborn Infants?

Glial fibrillary acidic protein (GFAP) is the structural protein of intermediate filaments in astroglia. GFAP has extensively been used as a marker of gliosis in neuropathology. It also appears in excessive amounts in the cerebrospinal fluid in various acute brain disorders. Hypoxic-ischemic encephalopathy after perinatal asphyxia is a condition in which levels of GFAP could be expected to be elevated if brain cell damage occurs. We examined levels of GFAP by a sensitive ELISA in the cerebrospinal fluid of full-term infants between 12 and 48 h after birth. Cerebrospinal fluid-GFAP increased 5-fold in infants after perinatal asphyxia compared with a reference group (675 versus 137 ng/L, p < 0.001). The levels of GFAP also increased gradually in accordance with the severity of the neurologic symptoms ranked as degree of hypoxic-ischemic encephalopathy. We conclude that the cerebrospinal fluid levels of GFAP might be an important adjunct in the neonatal assessment of infants subject to perinatal asphyxia, and together with other neuronal or glial proteins, it might also help in defining temporal relationships in asphyxia.

Glial fibrillary acidic protein in amniotic fluids from pregnancies with fetal neural tube defects

The glial fibrillary acidic protein (GFAP) is the subunit protein of intermediate filaments in astrocytes and closely related cell types. By means of an enzyme immunoassay we have determined the concentration of GFAP in amniotic fluids from normal pregnancies and from pregnancies complicated by various fetal malformations. The group of 20 cases of fetal anencephaly had a significantly higher mean amniotic fluid GFAP concentration (115 micrograms/l +/- 133.6 (S.D.), range 6-378 micrograms/l) than the control group of 117 normal pregnancies (13 micrograms/l +/- 5.5 (S.D.), range 0-31 micrograms/l), (P less than 0.001). Two cases of fetal encephalocele likewise had very high amniotic fluid GFAP concentrations. None of the other cases of fetal malformations investigated, including 12 cases of spina bifida, had increased amniotic fluid GFAP concentrations. We conclude that determination of the amniotic fluid GFAP concentration may give additional information in the prenatal diagnosis of fetal nervous system malformations.