Glial fibrillary acid protein: Functions and involvement in disease

Bioinformatics analysis reveals multiple functional changes in astrocytes in temporal lobe epilepsy

Epilepsy is a prevalent chronic neurological disorder characterized by recurrent seizures and brain dysfunction. Existing antiepileptic drugs (AEDs) mainly act on neurons and provide symptomatic control of seizures, but they do not modify the progression of epilepsy and may cause serious adverse effects. Increasing evidence suggests that reactive astrogliosis is critical in the pathophysiology of epilepsy. However, the function of reactive astrocytes in epilepsy has not been thoroughly explored. To provide a new perspective on the role of reactive astrocytes in epileptogenesis, we identified human astrocyte-specific genes and found 131 of these genes significantly differentially expressed in human temporal lobe epilepsy (TLE) datasets. Multiple astrocytic functions, such as cell adhesion, cell morphogenesis, actin filament-based process, apoptotic cell clearance and response to oxidative stress, were found to be promoted. Moreover, multiple altered astrocyte-specific genes were enriched in phagocytosis, perisynaptic astrocyte processes (PAPs), plasticity, and synaptic functions. Nine hub genes (ERBB2, GFAP, NOTCH2, ITGAV, ABCA1, AQP4, LRP1, GJA1, and YAP1) were identified by protein-protein interaction (PPI) network analysis. The correlation between the expression of these hub genes and seizure frequency, as well as epilepsy-related factors, including inflammatory mediators, complement factors, glutamate excitotoxicity and astrocyte reactivity, were analyzed. Additionally, upstream transcription factors of the hub genes were predicted. Finally, astrogliosis and the expression of the hub genes were validated in an epileptic rat model. Our findings reveal the various changes in astrocyte function associated with epilepsy and provide candidate astrocyte-specific genes that could be potential antiepileptogenic targets.

Agent Orange Herbicidal Toxin-Initiation of Alzheimer-Type Neurodegeneration

Background

Agent Orange (AO) is a Vietnam War-era herbicide that contains a 1 : 1 ratio of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Emerging evidence suggests that AO exposures cause toxic and degenerative pathologies that may increase the risk for Alzheimer's disease (AD).

Objective

This study investigates the effects of the two main AO constituents on key molecular and biochemical indices of AD-type neurodegeneration.

Methods

Long Evans rat frontal lobe slice cultures treated with 250μg/ml of 2,4-D, 2,4,5-T, or both (D + T) were evaluated for cytotoxicity, oxidative injury, mitochondrial function, and AD biomarker expression.

Results

Treatment with the AO constituents caused histopathological changes corresponding to neuronal, white matter, and endothelial cell degeneration, and molecular/biochemical abnormalities indicative of cytotoxic injury, lipid peroxidation, DNA damage, and increased immunoreactivity to activated Caspase 3, glial fibrillary acidic protein, ubiquitin, tau, paired-helical filament phosphorylated tau, AβPP, Aβ, and choline acetyltransferase. Nearly all indices of cellular injury and degeneration were more pronounced in the D + T compared with 2,4-D or 2,4,5-T treated cultures.

Conclusions

Exposures to AO herbicidal chemicals damage frontal lobe brain tissue with molecular and biochemical abnormalities that mimic pathologies associated with early-stage AD-type neurodegeneration. Additional research is needed to evaluate the long-term effects of AO exposures in relation to aging and progressive neurodegeneration in Vietnam War Veterans.

Influence of focused ultrasound on locoregional drug delivery to the brain: Potential implications for brain tumor therapy

INTRODUCTION

Efficient delivery of therapeutics across the blood-brain barrier (BBB) for the treatment of central nervous system (CNS) tumors is a major challenge to the development of safe and efficacious therapies. Locoregional drug delivery platforms offer an improved therapeutic index by achieving high drug concentrations in the target tissue with negligible systemic exposure. Intrathecal (intraventricular) [IT] and convection-enhanced delivery [CED] are two clinically relevant methods being employed for various CNS malignancies. Both of these standalone platforms suffer from passive post-administration distribution forces, sometimes limiting the desired distribution for tumor therapy. Focused ultrasound and microbubble-mediated blood-brain barrier opening (FUS-BBBO) is a recent modality used for enhanced drug delivery. It is postulated that coupling of FUS with these alternative delivery routes may provide benefits. Multimodality FUS may provide the desired ability to increase the depth of parenchymal delivery following IT administration and provide a means for contour directionality with CED. Further, the transient enhanced permeability achieved with FUS-BBBO is well established, but drug residence and transit times, important to clinical dose scheduling, have not yet been defined. The present investigation comprises two discrete studies: 1. Conduct a comprehensive quantitative evaluation to elucidate the effect of FUS-BBBO as it relates to varying routes of administration (IT and IV) in its capacity to facilitate drug penetration within the striatal-thalamic region. 2. Investigate the impact of combining FUS-BBBO with CED on drug distribution, with a specific focus on the temporal dynamics of drug retention within the target region.

METHODS

Firstly, we quantitatively assessed how FUS-BBBO coupled with IT and IV altered fluorescent dye (Dextran 2000 kDa and 70 kDa) distribution and concentration in a predetermined striatal-thalamic region in naïve mice. Secondly, we analyzed the pharmacokinetic effects of using FUS mediated BBB disruption coupled with CED by measuring the volume of distribution and time-dependent concentration of the dye.

RESULTS

Our results indicate that IV administration coupled with FUS-BBBO successfully enhances delivery of dye into the pre-defined sonication targets. Conversely, measurable dye in the sonication target was consistently less after IT administration. FUS enhances the distribution volume of dye after CED. Furthermore, a shorter time of residence was observed when CED was coupled with FUS-BBBO application when compared to CED alone.

CONCLUSION

1. Based on our findings, IV delivery coupled with FUS-BBBO is a more efficient means for delivery to deep targets (i.e. striatal-thalamic region) within a predefined spatial conformation compared to IT administration. 2. FUS-BBBO increases the volume of distribution (Vd) of dye after CED administration, but results in a shorter time of residence. Whether this finding is reproducible with other classes of agents (e.g., cytotoxic agents, antibodies, viral particles, cellular therapies) needs to be studied.

Clinical characteristics of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy in children: A case series of 16 patients

PURPOSE

To investigate the clinical characteristics of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy in children.

METHODS

We reviewed the medical records of Children's Hospital of Chongqing Medical University from January 2020 to September 2021 and retrospectively analysed the clinical features, magnetic resonance imaging (MRI) findings, laboratory findings, treatment and outcome of children with autoimmune GFAP astrocytopathy.

RESULTS

Sixteen patients were included: 6 and 10 tested positive for GFAP-IgG in cerebrospinal fluid (CSF) and both CSF and serum, respectively. The median patient age was 115 months (range: 36-180 months), and 7 patients (43.8%) were male. All patients had the clinical syndrome of encephalitis/meningoencephalitis with or without myelitis: encephalitis (8), meningoencephalitis (3), encephalomyelitis (1) and meningoencephalomyelitis (4). The most common clinical symptoms were fever (11), altered consciousness (11), headache (10) and seizure (9). Four patients developed central respiratory failure for which mechanical ventilation was needed. All patients showed hyperintense T2-weighted lesions on brain MRI in the cerebral white matter (13), brainstem (11), basal ganglia (11), thalamus (9), and cerebellum (3). Nine patients (56%) had abnormal hyperintense lesions in the bilateral basal ganglia and thalamus. Six of 12 patients who underwent gadolinium-enhanced brain MRI showed abnormal enhancement images, and five of them showed linear perivascular radial enhancement. The modified Rankin scale (mRS) score decreased significantly in most patients after immunotherapy. Two patients with coexisting neural autoantibodies relapsed; however, 15 patients who were followed up successfully had favorable outcomes at the last follow-up.

CONCLUSION

Children with autoimmune GFAP astrocytopathy usually have a clinical syndrome of encephalitis/meningoencephalitis with or without myelitis. Except for the linear perivascular radial gadolinium enhancement pattern, hyperintense lesions in the bilateral basal ganglia and thalamus might be another characteristic brain MRI finding of autoimmune GFAP astrocytopathy in children. Although a few patients with coexisting neural autoantibodies might relapse, children with autoimmune GFAP astrocytopathy usually have favorable outcomes after immunotherapy.

Are EPB41 and alpha-synuclein diagnostic biomarkers of sport-related concussion? Findings from the NCAA and Department of Defense CARE Consortium

BACKGROUND

Current protein biomarkers are only moderately predictive at identifying individuals with mild traumatic brain injury or concussion. Therefore, more accurate diagnostic markers are needed for sport-related concussion.

METHODS

This was a multicenter, prospective, case-control study of athletes who provided blood samples and were diagnosed with a concussion or were a matched non-concussed control within the National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research, and Education Consortium conducted between 2015 and 2019. The blood was collected within 48 h of injury to identify protein abnormalities at the acute and subacute timepoints. Athletes with concussion were divided into 6 h post-injury (0-6 h post-injury) and after 6 h post-injury (7-48 h post-injury) groups. We applied a highly multiplexed proteomic technique that used a DNA aptamers assay to target 1305 proteins in plasma samples from athletes with and without sport-related concussion.

RESULTS

A total of 140 athletes with concussion (79.3% males; aged 18.71 ± 1.10 years, mean ± SD) and 21 non-concussed athletes (76.2% males; 19.14 ± 1.10 years) were included in this study. We identified 338 plasma proteins that significantly differed in abundance (319 upregulated and 19 downregulated) in concussed athletes compared to non-concussed athletes. The top 20 most differentially abundant proteins discriminated concussed athletes from non-concussed athletes with an area under the curve (AUC) of 0.954 (95% confidence interval: 0.922‒0.986). Specifically, after 6 h of injury, the individual AUC of plasma erythrocyte membrane protein band 4.1 (EPB41) and alpha-synuclein (SNCA) were 0.956 and 0.875, respectively. The combination of EPB41 and SNCA provided the best AUC (1.000), which suggests this combination of candidate plasma biomarkers is the best for diagnosing concussion in athletes after 6 h of injury.

CONCLUSION

Our data suggest that proteomic profiling may provide novel diagnostic protein markers and that a combination of EPB41 and SNCA is the most predictive biomarker of concussion after 6 h of injury.

Self-assembled three-dimensional hydrogels based on graphene derivatives and cerium oxide nanoparticles: scaffolds for co-culture of oligodendrocytes and neurons derived from neural stem cells

Stem cell-based therapies have shown promising results for the regeneration of the nervous system. However, the survival and integration of the stem cells in the neural circuitry is suboptimal and might compromise the therapeutic outcomes of this approach. The development of functional scaffolds capable of actively interacting with stem cells may overcome the current limitations of stem cell-based therapies. In this study, three-dimensional hydrogels based on graphene derivatives and cerium oxide (CeO₂) nanoparticles are presented as prospective supports allowing neural stem cell adhesion, migration and differentiation. The morphological, mechanical and electrical properties of the resulting hydrogels can be finely tuned by controlling several parameters of the self-assembly of graphene oxide sheets, namely the amount of incorporated reducing agent (ascorbic acid) and CeO₂ nanoparticles. The intrinsic properties of the hydrogels, as well as the presence of CeO₂ nanoparticles, clearly influence the cell fate. Thus, stiffer adhesion substrates promote differentiation to glial cell lineages, while softer substrates enhance mature neuronal differentiation. Remarkably, CeO₂ nanoparticle-containing hydrogels support the differentiation of neural stem cells to neuronal, astroglial and oligodendroglial lineage cells, promoting the in vitro generation of nerve tissue grafts that might be employed in neuroregenerative cell therapies.

Area postrema syndrome with linear enhancement along the surface of the brainstem and fourth ventricle in autoimmune GFAP astrocytopathy

BACKGROUND

Glial fibrillary acidic protein (GFAP) astrocytopathy, a novel autoimmune disease of the nervous system, was first defined in 2016. To our knowledge, area postrema syndrome (APS) with linear enhancement along the surface of the brainstem and fourth ventricle is extremely rare in this disorder.

CASE PRESENTATION

A Chinese woman presented with intractable nausea and vomiting after onset of flu-like symptoms. Brain magnetic resonance imaging (MRI) disclosed abnormal signal intensities in the dorsal medulla oblongata including area postrema. Besides, linear enhancement surrounding the surface of the brainstem and fourth ventricle was visualized after gadolinium injection. Cerebrospinal fluid (CSF) analysis showed increased cell count and protein. A cell-based assay was positive for anti-GFAP IgG in CSF. She was diagnosed with autoimmune GFAP astrocytopathy and treated with high-dose glucocorticoid. The patient received a quick recovery with entire resolution of the initial abnormalities.

CONCLUSIONS

Isolated APS can be the initial manifestation of autoimmune GFAP astrocytopathy. Linear enhancement surrounding the surface of the brainstem and fourth ventricle is another neuroradiological hallmark.

Case 309: Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy

HISTORY

A 64-year-old man presented with a 6-month history of lightheadedness and intermittent balance and coordination difficulties. Two months before admission, symptoms became more substantial and persistent, with a worsening sense of disequilibrium and unsteady gait. He reported difficulties pronouncing words and mild word-finding difficulties. His wife noted a change in his cognition and memory over the same time. His medical history included well-controlled chronic obstructive pulmonary disease (COPD) secondary to a long history of smoking with associated unintentional 30-lb (13.6-kg) weight loss over the previous 3 years, for which chest CT scanning was performed, revealing no abnormality. On clinical examination, the patient was alert and oriented but had slurred speech. A positive Romberg sign was noted, finger-to-nose and hand rapid alternating movement tests revealed impairment on the right side, and his gait was ataxic. The motor examination revealed normal muscle tone, bulk, and power in the upper and lower extremities. Sensory testing results were normal. Initial MRI of the brain at admission revealed abnormal findings in the left supratentorial brain. Of note, this patient's presentation predated the COVID-19 pandemic. Cerebrospinal fluid (CSF) analysis revealed predominant pleocytosis (23 × 106/L; normal range, [0-5] × 106/L) (78% lymphocytes, 22% monocytes), elevated protein level (1.23 g/L; normal range, 0.19-0.64 g/L), oligoclonal bands (faint one or two), and a high immunoglobulin G (IgG) index (0.130 g/L; normal reference, ≤0.059 g/L). Despite extensive initial work-up for inflammatory, infectious, autoimmune, or neoplastic causes, a definitive diagnosis was not reached. Thus, repeat MRI of the brain was performed 2 weeks after admission.

Topiramate potential neurotoxicity and mitigating role of ginger oil in mice brain

Topiramate has multiple pharmacological mechanisms that are efficient in treating epilepsy and migraine. Ginger has been established to have gingerols and shogaols that cause migraine relief. Moreover, Topiramate has many off-label uses. Thus, it was necessary to explore the possible neurotoxicity of Topiramate and the role of ginger oil in attenuating the Topiramate neurotoxicity. Male albino mice were orally gavaged with Topiramate, ginger oil (400 mg/kg), and Topiramate plus ginger oil with the same pattern for 28 days. Oxidative stress markers, acetylcholinesterase (AchE), gamma-aminobutyric acid (GABA), and tumor necrosis factor-alpha (TNF-α) were examined. Histopathological examination, immunohistochemical glial fibrillary acidic protein (GFAP), and Bax expression analysis were detected. The GABAAR subunits, Gabra1, Gabra3, and Gabra5 expression, were assessed by RT-qPCR. The investigation showed that Topiramate raised oxidative stress markers levels, neurotransmitters, TNF-α, and diminished glutathione (GSH). In addition, Topiramate exhibited various neuropathological alterations, strong Bax, and GFAP immune-reactivity in the cerebral cortex. At the same time, the results indicated that ginger oil had no neurotoxicity. The effect of Topiramate plus ginger oil alleviated the changes induced by Topiramate in the tested parameters. Both Topiramate and ginger oil upregulated the mRNA expression of gabra1 and gabra3, while their interaction markedly downregulated them. Therefore, it could be concluded that the Topiramate overdose could cause neurotoxicity, but the interaction with ginger oil may reduce Topiramate-induced neurotoxicity and should be taken in parallel.

Area Postrema Syndrome in Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy

Background and Objectives

To report the frequency of area postrema syndrome (APS) in glial fibrillary acidic protein-immunoglobulin G (GFAP-IgG)–positive patients and emphasize the importance of APS among the phenotypes in autoimmune GFAP astrocytopathy.

Methods

Eight GFAP-IgG–positive cases with APS were retrospectively identified during 2015–2021. The APS phenotypes were described. A literature review of 8 previously reported cases was also included in analysis.

Results

A total of 8 patients (11%) (1 woman, 7 men; mean age: 52.4 ± 18.4 years) presented with APS in a cohort of 74 GFAP-IgG–positive patients, 3 of whom (4%) had disease onset with APS. All patients had hiccups, and hiccups was the unique symptom of APS in 5 patients. The median time from disease onset to APS occurrence was 2 days (range 0–20), and the mean duration of APS episodes was 23.6 ± 11.4 days. No patient had isolated APS attack. All episodes were completely resolved with a mean duration of 9.3 ± 5.4 days after immunotherapy. APS manifestations of 8 cases in previous studies showed similar features with our cases. In total, coexisting aquaporin-4-IgG was only detected in one of the 16 cases.

Discussion

APS could be an early, but not isolated clinical manifestation of autoimmune GFAP astrocytopathy. Hiccups was the predominant symptom of APS in this disorder. APS attacks of autoimmune GFAP astrocytopathy have good response to immunotherapy.

MicroRNA: A Linking between Astrocyte Dysfunction, Mild Cognitive Impairment, and Neurodegenerative Diseases

Simple Summary

Neurodegenerative diseases are complex neurological disorders with a high incidence worldwide in older people, increasing hospital visits and requiring expensive treatments. As a precursor phase of neurodegenerative diseases, cognitive impairment needs to be studied to understand the factors that influence its development and improve patients’ quality of life. The present review compiles possible factors and biomarkers for diagnosing mild cognitive impairment based on the most recent studies involving miRNAs. These molecules can direct the gene expression in multiple cells, affecting their behavior under certain conditions, such as stressing factors. This review encourages further research into biomarkers that identify cognitive impairment in cellular models such as astrocytes, which are brain cells capable of maintaining the optimal conditions for the central nervous system functioning.

Abstract

The importance of miRNAs in cellular processes and their dysregulation has taken significant importance in understanding different pathologies. Due to the constant increase in the prevalence of neurodegenerative diseases (ND) worldwide and their economic impact, mild cognitive impairment (MCI), considered a prodromal phase, is a logical starting point to study this public health problem. Multiple studies have established the importance of miRNAs in MCI, including astrocyte regulation during stressful conditions. Additionally, the protection mechanisms exerted by astrocytes against some damage in the central nervous system (CNS) lead to astrocytic reactivation, in which a differential expression of miRNAs has been shown. Nevertheless, excessive reactivation can cause neurodegeneration, and a clear pattern defining the equilibrium point between a neuroprotective or detrimental astrocytic phenotype is unknown. Therefore, the miRNA expression has gained significant attention to understand the maintenance of brain balance and improve the diagnosis and treatment at earlier stages in the ND. Here, we provide a comprehensive review of the emerging role of miRNAs in cellular processes that contribute to the loss of cognitive function, including lipotoxicity, which can induce chronic inflammation, also considering the fundamental role of astrocytes in brain homeostasis.

Comparison of clinical and radiological characteristics in autoimmune GFAP astrocytopathy, MOGAD and AQP4-IgG+ NMOSD mimicking intracranial infection as the initial manifestation

OBJECTIVE

Several autoimmune CNS inflammatory diseases, including autoimmune glial fibrillary acidic protein astrocytopathy (A-GFAP-A), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and aquaporin-4-immunoglobulin-G-positive neuromyelitis optica spectrum disorders (AQP4-IgG⁺NMOSD) often presented initially with similar symptoms mimicking intracranial infection, are not easy to be differentiated during early-onset lacking the detection of autoantibody.

METHODS

In our single-center cohorts, those patients mimicking intracranial infection as initial symptoms, including 9 with A-GFAP-A, 17 with MOGAD and 11 with AQP4-IgG⁺NMOSD, were retrospectively included. The autoantibodies were detected by cell-based assays. The clinical, immunological and radiological characteristics were summarized.

RESULTS

In the cohort, tremor and positive Kernig's sign were predominated in A-GFAP-A (44.4% and 77.8%, respectively) over MOGAD (5.9%, p = 0.034; 29.4%, p = 0.038) and AQP4-IgG⁺NMOSD (0, p = 0.026; 18.2%, p = 0.022). Ten patients (A-GFAP-A, 4; MOGAD, 5; AQP4-IgG⁺NMOSD, 1) were initially misdiagnosed as tubercular or viral meningoencephalitis, however, resistant to empiric anti-tuberculosis or anti-viral treatment, and finally were in partial or complete remission with the immunotherapy when adjusted treatments. On cerebrospinal fluid (CSF) examination, white blood cell counts in CSF was higher in A-GFAP-A cohort (median, 90×10⁶/L [IQR, 41-209]) compared to AQP4-IgG⁺ NMOSD (median, 6 × 10⁶/L [IQR, 1-10], p = 0.018). Importantly, the higher increase in CSF protein (1319 mg/L [IQR, 1035-1519]), lactate dehydrogenase (LDH, 53.9 ± 37.2 U/L), lactic acid (3.50 ± 0.88 mmol/L), IgG (130.9 ± 60.4 mg/L), IgM (8.6 ± 6.1 mg/L) and IgA (23.0 ± 11.4 mg/L) levels in A-GFAP-A was found compared to MOGAD (CSF protein: 441 mg/L [IQR, 330-776], p = 0.004; LDH: 53.9  ±  37.2 U/L, p = 0.005; lactic acid: 2.15 ± 0.62 mmol/L, p = 0.001; IgG: 77.9 ± 71.3 mg/L, p = 0.018; IgM, 2.7 ± 2.9 mg/L, p = 0.015) and AQP4-IgG⁺ NMOSD (CSF protein: 386 mg/L [IQR, 369-453], p = 0.002; LDH: 23.7 ± 11.0 U/L, p = 0.048; lactic acid: 2.40  ±  0.66 mmol/L, p = 0.040; IgG, 53.2 ± 30.3 mg/L, p = 0.015; IgM, 2.1 ± 3.9 mg/L, p = 0.004; IgA, 5.2 ± 5.0 mg/L, p < 0.001). Of Note, smaller (< 2 cm), symmetrical lesions in ganglia and thalamus (5/8, 62.5%) were showed in over half of the A-GFAP-A patients (5/8, 62.5%), but never in MOGAD (0%, p = 0.001) and AQP4-IgG⁺NMOSD (0%, p = 0.026). In addition, diffuse meningeal enhancement was more common in A-GFAP-A (8, 88.9%) compared to MOGAD (5, 29.4%, p = 0.011) and AQP4-IgG⁺NMOSD (1/6, 16.7%, p = 0.011), respectively. Acute disseminated encephalomyelitis (ADEM) -like lesions occurred more frequently in MOGAD (6/16, 37.5%) but never in A-GFAP-A and AQP4-IgG⁺NMOSD (p = 0.02).

CONCLUSION

Our study demonstrates that several distinct features including the symptom of tremor, higher CSF immunological profiles, bilateral symmetrical lesions in ganglia, and diffuse meningeal enhancement are frequent in A-GFAP-A, whereas ADEM-like lesions seem to occur mainly in MOGAD. These signs provide crucial clinical implications in differential diagnosis for those mimicking intracranial infection as initial symptoms. Clinicians should consider the possibility of these autoimmune CNS inflammatory diseases masquerading as intracranial infection.

Biofluid markers of blood-brain barrier disruption and neurodegeneration in Lewy body spectrum diseases: A systematic review and meta-analysis

BACKGROUND

Mixed evidence supports blood-brain barrier (BBB) dysfunction in Lewy body spectrum diseases.

METHODS

We compare biofluid markers in people with idiopathic Parkinson's disease (PD) and people with PD dementia (PDD) and/or dementia with Lewy bodies (DLB), compared with healthy controls (HC). Seven databases were searched up to May 10, 2021. Outcomes included cerebrospinal fluid to blood albumin ratio (Q_alb), and concentrations of 7 blood protein markers that also reflect BBB disruption and/or neurodegenerative co-pathology. We further explore differences between PD patients with and without evidence of dementia. Random-effects models were used to obtain standardized mean differences (SMD) with 95% confidence interval.

RESULTS

Of 13,949 unique records, 51 studies were meta-analyzed. Compared to HC, Q_alb was higher in PD (N_PD/N_HC = 224/563; SMD = 0.960 [0.227-1.694], p = 0.010; I² = 92.2%) and in PDD/DLB (N_PDD/DLB/N_HC = 265/670; SMD = 1.126 [0.358-1.893], p < 0.001; I² = 78.2%). Blood neurofilament light chain (NfL) was higher in PD (N_PD/N_HC = 1848/1130; SMD = 0.747 [0.442-1.052], p < 0.001; I² = 91.9%) and PDD/DLB (N_PDD/DLB/N_HC = 183/469; SMD = 1.051 [0.678-1.423], p = 0.004; I² = 92.7%) than in HC. p-tau 181 (N_PD/N_HC = 276/164; SMD = 0.698 [0.149-1.247], p = 0.013; I² = 82.7%) was also higher in PD compared to HC. In exploratory analyses, blood NfL was higher in PD without dementia (N_PDND/N_HC = 1005/740; SMD = 0.252 [0.042-0.462], p = 0.018; I² = 71.8%) and higher in PDD (N_PDD/N_HC = 100/111; SMD = 0.780 [0.347-1.214], p < 0.001; I² = 46.7%) compared to HC. Q_alb (N_PDD/N_PDND = 63/191; SMD = 0.482 [0.189-0.774], p = 0.010; I²<0.001%) and NfL (N_PDD/N_PDND = 100/223; SMD = 0.595 [0.346-0.844], p < 0.001; I² = 3.4%) were higher in PDD than in PD without dementia.

CONCLUSIONS

Biofluid markers suggest BBB disruption and neurodegenerative co-pathology involvement in common Lewy body diseases. Greater evidence of BBB breakdown was seen in Lewy body disease with cognitive impairment.

Extracellular vesicle neurofilament light is elevated within the first 12-months following traumatic brain injury in a U.S military population

Traumatic brain injury (TBI) can be associated with long-term neurobehavioral symptoms. Here, we examined levels of neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) in extracellular vesicles isolated from blood, and their relationship with TBI severity and neurobehavioral symptom reporting. Participants were 218 service members and veterans who sustained uncomplicated mild TBIs (mTBI, n = 107); complicated mild, moderate, or severe TBIs (smcTBI, n = 66); or Injured controls (IC, orthopedic injury without TBI, n = 45). Within one year after injury, but not after, NfL was higher in the smcTBI group than mTBI (p = 0.001, d = 0.66) and IC (p = 0.001, d = 0.35) groups, which remained after controlling for demographics and injury characteristics. NfL also discriminated the smcTBI group from IC (AUC:77.5%, p < 0.001) and mTBI (AUC:76.1%, p < 0.001) groups. No other group differences were observed for NfL or GFAP at either timepoint. NfL correlated with post-concussion symptoms (rs = - 0.38, p = 0.04) in the mTBI group, and with PTSD symptoms in mTBI (rs = - 0.43, p = 0.021) and smcTBI groups (rs = - 0.40, p = 0.024) within one year after injury, which was not confirmed in regression models. Our results suggest the potential of NfL, a protein previously linked to axonal damage, as a diagnostic biomarker that distinguishes TBI severity within the first year after injury.

Neurotoxic Potential of Deoxynivalenol in Murine Brain Cell Lines and Primary Hippocampal Cultures

Chronic exposure to the mycotoxin deoxynivalenol (DON) from grain-based food and feed affects human and animal health. Known consequences include entereopathogenic and immunotoxic defects; however, the neurotoxic potential of DON has only come into focus more recently due to the observation of behavioural disorders in exposed farm animals. DON can cross the blood-brain barrier and interfere with the homeostasis/functioning of the nervous system, but the underlying mechanisms of action remain elusive. Here, we have investigated the impact of DON on mouse astrocyte and microglia cell lines, as well as on primary hippocampal cultures by analysing different toxicological endpoints. We found that DON has an impact on the viability of both glial cell types, as shown by a significant decrease of metabolic activity, and a notable cytotoxic effect, which was stronger in the microglia. In astrocytes, DON caused a G1 phase arrest in the cell cycle and a decrease of cyclic-adenosine monophosphate (cAMP) levels. The pro-inflammatory cytokine tumour necrosis factor (TNF)-α was secreted in the microglia in response to DON exposure. Furthermore, the intermediate filaments of the astrocytic cytoskeleton were disturbed in primary hippocampal cultures, and the dendrite lengths of neurons were shortened. The combined results indicated DON's considerable potential to interfere with the brain cell physiology, which helps explain the observed in vivo neurotoxicological effects.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy Presenting with Area Postrema Syndrome-Like Symptoms without Medulla Oblongata Lesions

INTRODUCTION

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a recently described steroid-responsive meningoencephalomyelitis positive for cerebrospinal fluid (CSF) anti-GFAP antibody. Area postrema syndrome (APS) involves intractable hiccups, nausea, and vomiting, which is caused by medulla oblongata (MO) impairment. APS is a characteristic symptom of aquaporin-4 (AQP4) autoimmunity, and it helps to differentiate between AQP4 and GFAP autoimmunity. Conversely, although 6 cases of autoimmune GFAP astrocytopathy with APS and MO lesions have been reported, the association between GFAP autoimmunity and APS is unclear. We report the case of a patient with autoimmune GFAP astrocytopathy presenting with APS-like symptoms without MO lesions and discuss the mechanisms underlying the symptoms.

METHODS

CSF anti-GFAP antibody was detected using cell-based assays and immunohistochemical assays.

RESULTS

A 54-year-old Japanese man developed persistent hiccups, intermittent vomiting, fever, anorexia, and inattention. Brain magnetic resonance imaging (MRI) showed periventricular lesions with radial linear periventricular enhancement, suggesting autoimmune GFAP astrocytopathy. However, no obvious MO lesions were identified on thin-slice images. Spinal cord MRI revealed hazy lesions with patchy enhancement along the cervical and thoracic cord. CSF analysis demonstrated inflammation, with positive results for anti-GFAP antibodies. Anti-AQP4 antibodies in the serum and CSF were negative. Esophagogastroduodenoscopy revealed gastroparesis and gastroesophageal reflux disease, and vonoprazan, mosapride, and rikkunshito were effective only against persistent hiccups. Steroid therapy was initiated, allowing clinical and radiological improvements. Repeated MRIs demonstrated no obvious MO lesions.

CONCLUSION

This report suggests that autoimmune GFAP astrocytopathy presents with APS-like symptoms without obvious MO lesions. The possible causes of hiccups were gastroparesis and cervical cord lesions. Gastroesophageal reflux disease was not considered a major cause of the hiccups. Intermittent vomiting appeared to be associated with gastroparesis, cervical cord lesions, and viral-like symptoms. Testing for anti-GFAP antibodies should be considered in patients with APS-like symptoms in the context of typical clinical-MRI features of autoimmune GFAP astrocytopathy.

Clinical, neuroradiological, diagnostic and prognostic profile of autoimmune glial fibrillary acidic protein astrocytopathy: A pooled analysis of 324 cases from published data and a single-center retrospective study

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a recently defined autoimmune meningoencephalomyelitis, associated with GFAP-IgG antibody. A pooled analysis of 324 cases from published literature and a retrospective single-center study were performed, firstly reveals the possibility that patients with myelitic lesions respond better to initial immunotherapy, but are prone to relapse, suggesting a more aggressive and long-term immunosuppressive medication for them. Moreover, our results showed using tacrolimus at maintenance stage exhibited a less tendency to relapse, providing a possibly new choice to future clinical treatments.

Neuron-specific mitochondrial oxidative stress results in epilepsy, glucose dysregulation and a striking astrocyte response

Mitochondrial superoxide (O₂^-) production is implicated in aging, neurodegenerative disease, and most recently epilepsy. Yet the specific contribution of neuronal O₂^- to these phenomena is unclear. Here, we selectively deleted superoxide dismutase-2 (SOD2) in neuronal basic helix-loop-helix transcription factor (NEX)-expressing cells restricting deletion to a subset of excitatory principle neurons primarily in the forebrain (cortex and hippocampus). This resulted in nSOD2 KO mice that lived into adulthood (2-3 months) with epilepsy, selective loss of neurons, metabolic rewiring and a marked mitohormetic gene response. Surprisingly, expression of an astrocytic gene, glial fibrillary acidic protein (GFAP) was significantly increased relative to WT. Further studies in rat primary neuron-glial cultures showed that increased mitochondrial O₂^-, specifically in neurons, was sufficient to upregulate GFAP. These results suggest that neuron-specific mitochondrial O₂^- is sufficient to drive a complex and catastrophic epileptic phenotype and highlights the ability of SOD2 to act in a cell-nonautonomous manner to influence an astrocytic response.

Discriminative value of glial fibrillar acidic protein (GFAP) as a diagnostic tool in acute stroke. Individual patient data meta-analysis

Glial fibrillar acidic protein (GFAP) in serum has been evaluated as a promising biomarker to differentiate between intracerebral hemorrhage (ICH) and acute ischemic stroke (AIS). We assessed its value as diagnostic and prognostic tool for ICH through a literature systematic review and individual patient data (IPD) meta-analysis.We performed a systematic search in PubMed database until November 2018 for publications that evaluated GFAP to differentiate AIS and ICH within 4.5 hours after symptoms onset. Thereafter, we invited authors of selected studies to participate in this work by providing IPD from their cohorts. We used standardized individual subject's data to evaluate the association of GFAP concentrations with stroke subtype, demographics, stroke characteristics and factors related with GFAP measurement.From 4 selected studies, we collected data of 340 patients (236 AIS and 104 ICH). Standardized GFAP blood levels were significantly elevated in ICH compared with those with AIS (median and IQR: 0.84 (0.781-1.24), 0.79 (0.74-0.81); p<0.0001). In both stroke types, GFAP concentrations correlated with baseline stroke severity (r=0.27, p<0.0001; r=0.36, p<0.001; for AIS and ICH, respectively) but no correlation was found regarding time to sampling. Limited data precluded the evaluation of GFAP levels and functional outcome.These findings demonstrate substantially different levels of GFAP in the blood of patients with ICH compared with patients with AIS soon after the event, while no association was found with outcome. In summary, GFAP could be a valuable diagnostic tool to assist in medical decision-making and to optimize management of stroke in the acute setting.

Autoimmune glial fibrillary acidic protein astrocytopathy mimics infectious meningitis: Two case reports

BACKGROUND

Autoimmune glial fibrillary acidic protein astrocytopathy (A-GFAP-A) has been recently characterized as a novel autoimmune central nervous system (CNS) disorder with GFAP antibody as the biomarker. However, nonspecific symptoms of A-GFAP-A contribute to misdiagnosis.

CASE PRESENTATION

The patients presented with initial symptoms of fever, headache, and nuchal rigidity. Case 1 exhibited mild signs of irritability, active tendon reflexes, and dysuria; case 2 had transient loss of consciousness. Cerebrospinal fluid (CSF) revealed lymphocytosis, elevated protein level, and decreased glucose level. Magnetic resonance imaging (MRI) revealed radial gadolinium enhancement perpendicular to the lateral ventricle. Viral meningitis or tubercular meningitis was suspected. However, their inflammatory and pathogenic indicators showed no abnormal changes, and empirical antibiotic and antiviral drugs did not result in remarkable recovery. Subsequently, cases were detected with a strongly positive expression of GFAP antibody in CSF and the symptoms improved dramatically after high-dose methylprednisolone pulse treatment.

CONCLUSION

A-GFAP-A with meningitis-like symptoms could initially masquerade as intracranial infection, and prompt detection of GFAP antibody is essential for differentiation.

Autoimmune glial fibrillary acidic protein astrocytopathy

Purpose of review

To describe a recently characterized autoimmune, inflammatory central nervous system (CNS) disorder known as autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy.

Recent findings

Affected patients present with symptoms of one or more of meningitis (headache and neck ache), encephalitis (delirium, tremor, seizures, or psychiatric symptoms), and myelitis (sensory symptoms and weakness). Optic disc papillitis (blurred vision) is common. CNS inflammation is evident in characteristic T1 postgadolinium enhancement of GFAP-enriched CNS regions, and lymphocytic cerebrospinal fluid (CSF) white cell count elevation. CSF is more reliable than serum for GFAP-immunoglobulin G (IgG) testing. Ovarian teratoma commonly coexists, particularly among patients with accompanying N-methyl-D-aspartate receptor or aquaporin-4 autoimmunity. Parainfectious autoimmunity is suspected in some other patients, though the culprit organism is rarely verified. Pathophysiologic relevance of T cells is underscored by neuropathology and cases of dysregulated T-cell function (HIV or checkpoint inhibitor cancer therapy). Corticosteroid-responsiveness is a hallmark of the disease. Relapses occur in approximately 20% of patients, necessitating transition to a steroid-sparing drug. Reported outcomes vary, though in the authors’ experience, early and sustained intervention usually portends recovery.

Summary

Autoimmune GFAP astrocytopathy is a treatable autoimmune CNS disease diagnosable by GFAP-IgG testing in CSF. This disease presents opportunities to explore novel mechanisms of CNS autoimmunity and inflammation.

Neuromyelitis optic with positive Anti-AQP4 and Anti-SSA/Ro antibody

Neuromyelitis Optic (NMO) is an inflammatory disorder involving central nervous system which often co-exists with other autoimmune diseases such as Sjögren’s syndrome (SS). NMO manifestation could precede or follow SS, but the role of anti-SSA in the pathogenesis of NMO remains unclear. We present a case of NMO with anti-AQP4 anti-SSA antibody positive. A-44-year-old female presented with right side weakness. The symptoms began with numbness that improved spontaneously. She also complained pain and dry sensations on her eyes. Schirmer test on her left eye, antinuclear antibody (ANA) and anti-SSA antibody were positive. Cervical MRI revealed intramedullary lesion on T2-weighted-image at C2-C5 level. She was diagnosed as NMO with positive anti-AQP4 and probable SS. She received 1g methylprednisolone for 5 days proceeded with mycophenolic acid. One-year observation showed clinical improvement. Systemic autoantibodies must substansially be evaluated in NMO. Comprehensive diagnosis and providing appropriate immuno-suppressant might prevent further disability and relapse.