Case report: Headache as the sole neurological symptom in autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a recently emerging autoimmune disease of the central nervous system (CNS); GFAP astrocytopathy is characterized by optic neuritis and meningoencephalomyelitis. We report the case of a 55-year-old man, otherwise healthy, who presented with isolated headaches for three months, without other features of meningoencephalitis or myelitis. His neurological examination and fundoscopy were unremarkable. Gadolinium-enhanced brain MRI demonstrated increased T2 hyperintensity within the right sub-lenticular basal ganglia, with additional leptomeningeal enhancement along the bilateral perisylvian regions and mesial temporal lobes. Cerebrospinal fluid (CSF) analysis showed lymphocytic pleocytosis, elevated protein, matching oligoclonal bands, and a negative infectious and cytological workup. Cell-based assays for anti-aquaporin-4, anti-myelin oligodendrocyte glycoprotein, autoimmune encephalitis panel, and vasculitis workup were all negative, except for CSF positivity for GFAP α antibody. Oncological screening, including CT of the chest, abdomen, pelvis, and scrotal US, was unremarkable. Immunotherapy with high-dose intravenous steroids for five days and subsequent single four-weekly doses resulted in the resolution of both clinical and radiographic features, with a maintained status 24 months after onset. This case highlights isolated headache and basal ganglia, mesial temporal lobe involvement as a rare presentation of autoimmune GFAP astrocytopathy.

Clinical characteristics and MRI features of autoimmune glial fibrillary acidic protein astrocytopathy: a case series of 34 patients

Objectives

To analyze the clinical and imaging characteristics of autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A).

Methods

Forty-three patients diagnosed with GFAP-A between March 2017 and July 2023 were retrospectively recruited. The clinical characteristics and magnetic resonance imaging (MRI) features were collected.

Results

Twenty-one patients (61.8%) had a fever and 16 (47.1%) had a headache. Five patients (14.7%) had coexisting neural autoantibodies and one patient (2.9%) had a coexisting neoplasm. The most common presentation was meningoencephalomyelitis (13/34, 38.3%), followed by meningoencephalitis (12/34, 35.3%). The other clinical manifestations included blurred visions (5/34, 14.7%) and peripheral nervous system involvement (4/34, 11.8%). Twenty-six patients (76.5%) had elevated nucleated cell count, predominantly lymphocytes (15/15, 100%), and 27 (79.4%) had elevated protein levels of cerebrospinal fluid. One-half (50%) of the patients presented with hyponatremia. A majority of the patients (30/33, 90.9%) exhibited abnormal hyperintense lesions on T2WI, which were often located in juxtacortical white matter (18/33, 54.5%), followed by periventricular white matter (16/33, 48.5%), basal ganglia (15/ 33, 45.5%), brainstem (11/33, 33.3%), and thalamic lesions (9/33, 27.3%). Twenty-four patients (72.7%) had abnormal brain enhancement, with supratentorial leptomeningeal enhancement being the most frequent enhancement pattern (15/33, 45.5%), followed by linear perivascular radial enhancement (14/33, 42.4%). Nineteen patients (70.4%) had hyperintense intramedullary spinal cord lesions, with long segments (15/27, 55.6%) and transverse lesions (14/27, 51.9%) being the most frequent lesions. Most cases were sensitive to immunotherapy, such as glucocorticoids, intravenous immunoglobulin, and tacrolimus, with three patients (8.8%) experiencing relapses. Patients with brainstem lesions had higher onset modified Rankin scale scores and were more prone to intensive care unit admissions. Linear perivascular radial enhancement was positively associated with poor prognosis (p < 0.05).

Conclusion

GFAP-A presented with meningoencephalomyelitis and meningoencephalitis. The brain lesions were often located in juxtacortical white matter, periventricular white matter, basal ganglia, brainstem, and thalamus. Long segments and transverse were the most frequent spine lesions. Leptomeningeal enhancement was the most frequent enhancement pattern, followed by linear perivascular radial enhancement, which may provide new insight into the differential diagnosis of GFAP-A.

[Clinical features and pathogenesis of Glial fibrillary acidic protein (GFAP) antibody-associated disorders]

Glial fibrillary acidic protein (GFAP) antibody-associated disorders (AD) were recently proposed to be immune-mediated neurological disorders. The pathogenesis of GFAP antibody-AD is poorly understood. Pathologically, there is a marked infiltration of large numbers of lymphocytes, including CD8+ and CD4+ T cells, into the meningeal and brain parenchyma, especially around the perivascular areas. GFAP-specific cytotoxic T cells are considered to be the effector cells of GFAP antibody-AD. The common phenotype of GFAP antibody-AD includes meningoencephalitis with or without myelitis. During the clinical disease course, patients present with consciousness disturbances, urinary dysfunction, movement disorders, meningeal irritation, and cognitive dysfunction. The detection of GFAP antibodies in the cerebrospinal fluid (CSF) by cell-based assay is essential for a diagnosis of GFAP antibody-AD. The CSF can be examined for lymphocyte-predominant pleocytosis and elevated protein levels. Brain linear perivascular radial enhancement patterns are observed in about half of GFAP antibody-AD patients. Spinal cord magnetic resonance imaging is used to detect longitudinal extensive spinal cord lesions. Although corticosteroid therapy is generally effective, some patients have a poor prognosis and relapse.

Glial Fibrillary Acidic Protein (GFAP) Astrocytopathy: An Emerging Cause of Meningoencephalomyelitis in Children and Adolescents

Introduction: We describe 5 children with GFAP astrocytopathy with the goal of further characterizing this rare form of meningoencephalomyelitis. Methods: Retrospective chart review of patients diagnosed with GFAP astrocytopathy between 2019 and 2021. Results: Patients were 8-17 years old, and all were male. Fever, headache, and vomiting were common presenting symptoms, and weakness, tremor, and ataxia were common initial examination findings. Initial magnetic resonance imaging (MRI) showed spinal cord abnormalities in 2 patients and leptomeningeal enhancement in 1. Most patients had cerebral spinal fluid pleocytosis, and all screened negative for malignancy. Three patients progressed to coma, and all were treated with immunosuppressant therapy. By discharge, all patients had improved over their clinical nadir, although none had returned to baseline. Discussion: GFAP astrocytopathy is a recently recognized cause of meningoencephalomyelitis in children. Here, we expand our understanding of this entity with the goal of aiding those treating children with GFAP astrocytopathy.

A case report of autoimmune glial fibrillary acidic protein astrocytopathy presenting as an isolated spinal cord lesion

INTRODUCTION

Autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A) is a group of neurological syndromes involving the meninges, brain, spinal cord, and optic nerves and is characterized by sensitivity to steroid therapy. Due to the diverse clinical presentation and lack of uniform diagnostic criteria, GFAP-A can easily be overlooked or diagnosed as another disease. It is even rarer when presenting as an isolated spinal cord lesion.

CASE REPORT

We report the case of a 70-year-old man with initial symptoms of numbness and weakness in both lower limbs, followed by difficulty in urination and defecation, and progression of numbness upward to the hands. Magnetic resonance imaging (MRI) showed a lesion in the spinal cord from cervical level 2 to thoracic 7 in a T2-weighted image. T1-weighted image showed a punctate, lamellar strengthening lesion with significant spinal strengthening. GFAP immunoglobulin G (IgG) was detected in the cerebrospinal fluid and blood. After treatment with intravenous gamma globulin (IVIG), the patient symptoms improved and spinal cord enhancement was reduced.

CONCLUSION

Long segment cases with punctate and patchy enhancement of the spinal cord are difficult to distinguish from CLAPPERS, so GFAP-A antibody detection is very important. This atypical case also increases neurologists' understanding of GFAP-A.

Magnetic Resonance Imaging Characteristics of Autoimmune Glial Fibrillary Acidic Protein (GFAP) Astrocytopathy: A Pediatric Series in Southwest China

Objective

To investigate and summarize the magnetic resonance imaging (MRI) manifestations of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy in children.

Methods

We retrospectively analyzed data from 17 pediatric patients with autoimmune GFAP astrocytopathy confirmed by the detection of GFAP autoantibodies in cerebrospinal fluid in our single-center. Furthermore, we reviewed current literature and summarized previous findings on the MRI characteristics of this disease in children.

Results

In these 17 patients, the clinical manifestations and results of CSF analysis were suggestive of autoimmune disorder, with a good improvement. The lesions on MRI were most commonly located in the bilateral basal ganglia (70.6%), thalamus (64.7%), cerebral white matter (29.4%). 93.3% of the cerebral lesions were relatively scattered and small, 80% of the spinal lesions presented as longitudinally extensive ones. Both periventricular radial linear (PVRL) (53.8%) and punctate or linear enhancement in basal ganglia and thalamus (53.8%) were commonly observed, followed by the leptomeningeal enhancement (46.2% in the brain and 62.5% in the spinal cord). We then included 55 pediatric patients with MRI data from current literature in our analysis (n = 72, 44 males). Our results revealed similar MRI findings but the enhancement pattern between our series and previously published cases, that is, leptomeningeal enhancement in the brain 46.2% vs 31.4%, in spinal cord 62.5% vs 18.4%, and PVRL enhancement 53.8% vs 11.2%. There were no detailed reports on punctate or linear enhancement.

Conclusion

The MRI characteristics of autoimmune GFAP astrocytopathy in children could be suggestive. Scattered and small lesions (especially punctate or linear) in the bilateral thalamus, basal ganglia, and white matter, as well as longitudinally extensive spinal cord lesions (if present), with punctate, PVRL and leptomeningeal enhancement might be a distinct indication for the early diagnosis of this disorder.

Autoimmune Glial Fibrillary Acidic Protein (Gfap) Astrocytopa-Thy Accompanied with Reversible Splenial Lesion Syndrome (RESLES): A Case Report and Literature Review

BACKGROUND

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy usually presents as meningoencephalomyelitis. Many patients developed flu-like symptoms preceding the neurologic symptoms. Reversible lesion in the splenium of the corpus callosum (SCC) is a clinical and radiological syndrome secondary to many kinds of etiologies, including infections, which is termed RESLES.

CASE PRESENTATION

we reported a case developing irregularly high fever, both temporal pain, low limbs fatigue with frequent urination admitted to our neurology department. CSF test showed GFAP-IgG positive, elevated WBC counts and protein, with low glucose and chlorine, while MRI showed a reversible lesion on SCC, leading us to diagnose autoimmune GFAP autocytopathy accompanied with RESLES. The boy had significantly improved after anti-virus and steroids therapy.

DISCUSSION

Autoimmune GFAP autocytopathy accompanied with RESLES is rarely seen, and pathogenesis for the co-existence has not been clarified. Autoimmune GFAP autocytopathy and RESLES are both related to viral infection. Our case covered infectious symptoms and improved after antiviral treatment, suggesting virus infection may perform a key role in pathogenesis.

Delayed Appearance of Brain Magnetic Resonance Imaging Abnormalities in a Patient with Glial Fibrillary Acidic Protein Astrocytopathy

Recent studies have reported that autoantibodies against glial fibrillary acidic protein (GFAP), a major cytoskeletal protein expressed in astrocytes, can lead to GFAP astrocytopathy, an autoimmune central nervous system inflammatory disease. We herein report the unique case of a 59-year-old Japanese woman with GFAP astrocytopathy who presented with characteristic symptoms, including signs of meningeal irritation, cerebellar ataxia, and bladder/rectal dysfunction, in the absence of specific findings on initial brain magnetic resonance imaging (MRI). The patient exhibited new abnormal changes mainly in the brainstem on follow-up MRI, illustrating the need to recognize that MRI abnormalities may appear later in GFAP astrocytopathy.

Clinical and electrophysiological characteristics of peripheral neuropathy in autoimmune glial fibrillary acidic protein astrocytopathy: an observational study and literature review

Background

The phenotype of peripheral neuropathy (PN) associated with glial fibrillary acidic protein-immunoglobulin G (GFAP-IgG) has not been well described.

Objectives

The aim of this study was to report the frequency, clinical, and electrophysiological characteristics of PN in GFAP-IgG-positive patients.

Design

This study is a single-center retrospective observational study.

Data Sources and methods

GFAP-IgG-positive patients with PN were retrospectively identified from the Huashan Hospital Autoimmune Encephalitis Cohort between 2017 and 2021. Eight patients who presented with PN from other published studies were also included in the analysis. The clinical and electrophysiological characteristics of GFAP-IgG-related PN were described.

Results

A total of 21 (31%) patients (7 females, 14 males; M _age: 42 ± 16 years) from a cohort of 68 GFAP-IgG-positive patients presented with PN. Twenty of 21 patients had symmetrical weakness. Sensory and autonomic symptoms were present in 16 and 15 patients, respectively. Lower extremities were the most frequently involved regions for both motor (20/21) and sensory (15/21) symptoms. Moreover, 13 patients (4 females, 9 males; M _age: 43 ± 13 years) had electrodiagnostic study data, and 12 of 13 patients had abnormal findings. Regarding clinical features, motor nerve fibers were predominantly involved (12/13), and symmetric lower extremities (12/13) were the most commonly affected regions. Axonal neuropathy is the typical underlying pathophysiologic process of PN. All 21 patients responded to immunotherapy. However, four patients with tetraplegia had poor outcomes, and PN was the major determinant of their long-term disability. Most cases (6/8) from the literature presented with similar clinical and electrophysiological features to those from our cohort.

Conclusion

Peripheral nerves could be involved in autoimmune GFAP astrocytopathy. Predominant motor axonal neuropathy mainly involving the lower extremities is the most common PN phenotype in this disorder. GFAP-IgG-related PN is responsive to immunotherapy.

Registration

Chinese Clinical Trial Registry: ChiCTR2000029115 (http://www.chictr.org).

Cortical Pathology in Vanishing White Matter

Vanishing white matter (VWM) is classified as a leukodystrophy with astrocytes as primary drivers in its pathogenesis. Magnetic resonance imaging has documented the progressive thinning of cortices in long-surviving patients. Routine histopathological analyses, however, have not yet pointed to cortical involvement in VWM. Here, we provide a comprehensive analysis of the VWM cortex. We employed high-resolution-mass-spectrometry-based proteomics and immunohistochemistry to gain insight into possible molecular disease mechanisms in the cortices of VWM patients. The proteome analysis revealed 268 differentially expressed proteins in the VWM cortices compared to the controls. A majority of these proteins formed a major protein interaction network. A subsequent gene ontology analysis identified enrichment for terms such as cellular metabolism, particularly mitochondrial activity. Importantly, some of the proteins with the most prominent changes in expression were found in astrocytes, indicating cortical astrocytic involvement. Indeed, we confirmed that VWM cortical astrocytes exhibit morphological changes and are less complex in structure than control cells. Our findings also suggest that these astrocytes are immature and not reactive. Taken together, we provide insights into cortical involvement in VWM, which has to be taken into account when developing therapeutic strategies.

A new form of axonal pathology in a spinal model of neuromyelitis optica

Neuromyelitis optica is a chronic neuroinflammatory disease, which primarily targets astrocytes and often results in severe axon injury of unknown mechanism. Neuromyelitis optica patients harbour autoantibodies against the astrocytic water channel protein, aquaporin-4 (AQP4-IgG), which induce complement-mediated astrocyte lysis and subsequent axon damage. Using spinal in vivo imaging in a mouse model of such astrocytopathic lesions, we explored the mechanism underlying neuromyelitis optica-related axon injury. Many axons showed a swift and morphologically distinct 'pearls-on-string' transformation also readily detectable in human neuromyelitis optica lesions, which especially affected small calibre axons independently of myelination. Functional imaging revealed that calcium homeostasis was initially preserved in this 'acute axonal beading' state, ruling out disruption of the axonal membrane, which sets this form of axon injury apart from previously described forms of traumatic and inflammatory axon damage. Morphological, pharmacological and genetic analyses showed that AQP4-IgG-induced axon injury involved osmotic stress and ionic overload, but does not appear to use canonical pathways of Wallerian-like degeneration. Subcellular analysis demonstrated remodelling of the axonal cytoskeleton in beaded axons, especially local loss of microtubules. Treatment with the microtubule stabilizer epothilone, a putative therapy approach for traumatic and degenerative axonopathies, prevented axonal beading, while destabilizing microtubules sensitized axons for beading. Our results reveal a distinct form of immune-mediated axon pathology in neuromyelitis optica that mechanistically differs from known cascades of post-traumatic and inflammatory axon loss, and suggest a new strategy for neuroprotection in neuromyelitis optica and related diseases.

MR T2-relaxation time as an indirect measure of brain water content and disease activity in NMOSD

OBJECTIVE

Since astrocytes at the blood-brain barrier are targeted by neuromyelitis optica spectrum disorder (NMOSD), this study aims to assess whether patients with NMOSD have a subclinical accumulation of brain water and if it differs according to disease activity.

METHODS

Seventy-seven aquaporin-4-positive patients with NMOSD and 105 healthy controls were enrolled at two European centres. Brain dual-echo turbo spin-echo MR images were evaluated and maps of T2 relaxation time (T2rt) in the normal-appearing white matter (NAWM), grey matter and basal ganglia were obtained. Patients with a clinical relapse within 1 month before or after MRI acquisition were defined 'active'. Differences between patients and controls were assessed using z-scores of T2rt obtained with age-adjusted and sex-adjusted linear models from each site. A stepwise binary logistic regression was run on clinical and MRI variables to identify independent predictors of disease activity.

RESULTS

Patients had increased T2rt in both white and grey matter structures (p range: 0.014 to <0.0001). Twenty patients with NMOSD were defined active. Despite similar clinical and MRI features, active patients had a significantly increased T2rt in the NAWM and grey matter compared with those clinically stable (p range: 0.010-0.002). The stepwise binary logistic regression selected the NAWM as independently associated with disease activity (beta=2.06, SE=0.58, Nagelkerke R2=0.46, p<0.001).

CONCLUSIONS

In line with the research hypothesis, patients with NMOSD have increased brain T2rt. The magnitude of this alteration might be useful for identifying those patients with active disease.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy: To Identify Its Diagnosis, Management and Prognosis (GFAP-AID) Registry: Study Protocol for an Ambispective, Multicenter Registry in China

PURPOSE

Currently, no uniform diagnostic criteria or treatment consensus is available for patients with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A). The aim of this registry is to develop diagnostic and therapeutic recommendations for GFAP-A based on clinical features, neuroimaging, neuroelectrophysiological examinations, laboratory tests, specific antibody tests, immunotherapy, and prognosis.

PATIENTS AND METHODS

This multicenter, nationwide ambispective registry includes twenty-seven hospitals in China. From January 2020 to December 2022, consecutive hospitalized patients with symptoms of meningoencephalitis, as well as GFAP-IgG positive cerebrospinal fluid (CSF) or serum will be invited to join this study. It is conservatively estimated that over 300 patients will join the study. Data on demographics, medical history, treatment details and imaging features will be collected after discharge. Outcome events of interest will include modified Rankin Scale (mRS) and Expanded Disability Status Scale (EDSS), readmission with relapsed meningoencephalomyelitis, all-cause mortality, and mortality resulting from complications of GFAP-A. The follow-up will be conducted at six months and twelve months after discharge. Univariate and multivariate regression models will be used to calculate identify independent predictors of outcomes. Stratification analysis will be used to test whether results are similar between key subgroups.

DISCUSSION

This study will describe the risk factors, disease course, response to immunotherapy, and long-term prognosis of a large cohort of GFAP-A patients. By using these data, a relatively rational recommendation process for the diagnosis and treatment of GFAP-A will be developed.

TRIAL REGISTRATION NUMBER

ChiCTR2000041291.

Alexander disease evolution over time: data from an Italian cohort of pediatric-onset patients

Alexander disease (AxD) is a leukodystrophy that primarily affects astrocytes and is caused by dominant variants in the Glial Fibrillary Acidic Protein gene. Three main classifications are currently used, the traditional one defined by the age of onset, and two more recent ones based on both clinical features at onset and brain MRI findings. In this study, we retrospectively included patients with genetically confirmed pediatric-onset AxD. Twenty-one Italian patients were enrolled, and we revised all their clinical and radiological data. Participants were divided according to the current classification systems. We qualitatively analyzed data on neurodevelopment and neurologic decline in order to identify the possible trajectories of the evolution of the disease over time. One patient suffered from a Neonatal presentation and showed a rapidly evolving course which led to death within the second year of life (Type Ia). 16 patients suffered from the Infantile presentation: 5 of them (here defined Type Ib) presented developmental delay and began to deteriorate by the age of 5. A second group (Type Ic) included patients who presented a delay in neuromotor development and started deteriorating after 6 years of age. A third group (Type Id) included patients who presented developmental delay and remained clinically stable beyond adolescence. In 4 patients, the age at last evaluation made it not possible to ascertain whether they belonged to Type Ic or Id, as they were too young to evaluate their neurologic decline. 4 patients suffered from the Juvenile presentation: they had normal neuromotor development with no or only mild cognitive impairment; the subsequent clinical evolution was similar to Type Ic AxD in 2 patients, to Id group in the other 2. In conclusion, our results confirm previously described findings about clinical features at onset; based on follow-up data we might classify patients with Type I AxD into four subgroups (Ia, Ib, Ic, Id). Further studies will be needed to confirm our results and to better highlight the existence of clinical and neuroradiological prognostic factors able to predict disease progression.

[A case of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy]

A 46-year-old man developed acute meningo-encephalitis with confusion, headache, fever, intractable hiccups, dysuria, myoclonus/tremor, and ataxia. Analysis of cerebrospinal fluid (CSF) showed elevated levels of cell counts and protein. Brain MRI demonstrated multiple linear increased FLAIR signals in bilateral basal ganglia and corona radiata. Repeated MRI showed T₂ hyperintensity areas in the lower brainstem, sparing the area postrema. Immunotherapy with intravenous high-dose steroid and subsequent oral steroid was successful, and the symptoms improved completely. Later MRI study showed a striking resolution. Glial fibrillary acidic protein (GFAP) α antibody was positive in the CSF, while anti-aquaporin-4 antibody, anti-myelin oligodendrocyte glycoprotein antibody, and N-methyl-D-aspartate receptor antibody were all negative. There were no relapses at final follow-up of 6 months after onset. Autoimmune GFAP astrocytopathy is not an uncommon immune-mediated inflammatory disorder in the central nervous system.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy Presenting with Slowly Progressive Myelitis and Longitudinally Extensive Spinal Cord Lesions

We report a 65-year-old man with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A) who presented with gait disturbance that he had experienced for approximately half a year. On neurological examination, he displayed spastic paraplegia and autonomic dysfunctions including dysuria and constipation. Spinal cord magnetic resonance imaging showed longitudinally extensive spinal cord lesions (LESCLs) extending from the cervical to the thoracic cords. The patient was negative for anti-myelin oligodendrocyte glycoprotein and anti-aquaporin 4 antibodies. Treatment with corticosteroids and intravenous immunoglobulin resulted in a clinical improvement. It is important to distinguish GFAP-A from slowly progressive myelitis with LESCLs.

Autoimmune glial fibrillary acidic protein astrocytopathy with lesions distributed predominantly in the entire spinal cord

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy has been considered a novel central nervous system autoimmune disease characterized by relapse and responsiveness to corticosteroid with a specific GFAP-Immunoglobulin G (IgG) being noted in cerebrospinal fluid. We report the case of a 21-year-old girl presenting with dysuria and weariness, who subsequently developed blurry vision, slight dysphagia, slurred speech, and sensory abnormality. GFAP-IgG was detected in her cerebrospinal fluid. Magnetic resonance imaging using both T2-weighted and contrast-enhanced T1-weighted images revealed a rare finding of lesions distributed mainly in the entire spinal cord rather than typical brain lesions. After treating with corticosteroids, her clinical symptoms were alleviated, and the spinal cord lesion enhancement was reduced. Our observations extend the clinical spectrum of autoimmune GFAP astrocytopathy. We suggest that rare distributed lesions in the entire spinal cord in patients with autoimmune GFAP astrocytopathy cannot be ignored by neurologists. The identification of potential atypical lesions broadens the understanding of autoimmune GFAP astrocytopathy.

Mirror-Image Lesions in Sequential Relapses of AQP4-Positive Neuromyelitis Optica Spectrum Disorder

A 25 year-old Nigerian woman with aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (NMOSD) presented with a 6 week history of nausea, vomiting, and refractory hiccups; as well as progressive lower extremity sensory loss, weakness, saddle anesthesia, and urinary incontinence. She had experienced her first NMOSD relapse seven years prior with bilateral lower extremity weakness and area postrema syndrome. After pulse steroids and plasma exchange she made a complete neurologic recovery and was started on azathioprine. An initial aquaporin-4 (AQP4) antibody ELISA test was positive, but three subsequent tests were negative and repeat MRI brain showed resolution of T2/FLAIR signal abnormalities with the exception of a right thalamic lesion and a left medullary lesion. Azathioprine was discontinued after 1 year and she was lost to follow-up. With her second relapse, she had new lesions in her left thalamus and right medulla—a mirror image of the thalamic and medullary lesions associated with her first relapse. In addition, an MRI spine demonstrated a new longitudinally extensive transverse myelitis from T7 to L1 with edematous expansion of the cord. Her serum AQP4 antibody test using a cell-based assay was strongly positive. NMOSD lesions are typically associated with brain regions with high density of the AQP4 channel. These areas include optic nerves, hypothalamus, and the diencephalic and brainstem tissues that surround the cerebral aqueduct and third and fourth ventricles. Previous studies have demonstrated that those with relapsing NMOSD have a predilection for recurrence in the same neuroanatomical region as their first episode. We hypothesize, using data from prior pathologic and epidemiologic studies, that mirror image lesions, where the same anatomic sites are affected on the contralateral side of the brain or spinal cord, may appear in subsequent attacks due to (i) areas of high remaining AQP4 density and/or (ii) local compromise of astrocyte or blood-brain barrier (BBB) function that persists after the initial inciting attack.

Black holes and high levels of neurofilaments in glial fibrillary acidic protein - astrocytopathy: a case report

BACKGROUND AND PURPOSE

Glial fibrillary acidic protein (GFAP) is an intracellular protein of the astrocytic cytoskeleton. Recently, autoantibodies to GFAP detected by cell-based assay in cerebrospinal fluid (CSF) or serum have been implicated in cerebral astrocytopathy, presenting predominantly with autoimmune meningoencephalomyelitis. However, the phenotypic spectrum, prognosis and therapeutics of this new entity remain to be elucidated.

METHODS

Herein, we report radiological, CSF and serological findings during disease exacerbation and remission, from a patient with autoimmune GFAP astrocytopathy, presenting as an immunotherapy responsive GFAP IgG-associated meningoencephalomyelitis.

RESULTS

Brain and spine magnetic resonance imaging revealed meningeal enhancement, T2 hyperintensities, black holes, significant sulci widening and spinal atrophy. In addition, high levels of neurofilaments (NfL) and GFAP were also identified during disease exacerbation, consistent with the appearance of the black holes.

CONCLUSIONS

To date, black holes and atrophy have never been reported before in autoimmune GFAP astrocytopathy. These findings, combined with the high levels of GFAP and NfL, suggest the existence of an underlying neurodegenerative mechanism in addition to the known inflammatory response. Further studies are needed to elucidate the pathomechanism of GFAP-astrocytopathies.

AQP4 Antibody Assay Sensitivity Comparison in the Era of the 2015 Diagnostic Criteria for NMOSD

We have compared five different assays for antibodies to aquaporin-4 in 181 cases of suspected Neuromyelitis optica spectrum disorders (NMOSD) and 253 controls to assess their relative utility. As part of a clinically-based survey of NMOSD in Australia and New Zealand, cases of suspected NMOSD were referred from 23 centers. Clinical details and magnetic imaging were reviewed and used to apply the 2015 IPND diagnostic criteria. In addition, 101 age- and sex-matched patients with multiple sclerosis were referred. Other inflammatory disease (n = 49) and healthy controls (n = 103) were also recruited. Samples from all participants were tested using tissue-based indirect immunofluorescence assays and a subset were tested using four additional ELISA and cell-based assays. Antibodies to myelin oligodendrocyte glycoprotein (MOG) were also assayed. All aquaporin-4 antibody assays proved to be highly specific. Sensitivities ranged from 60 to 94%, with cell-based assays having the highest sensitivity. Antibodies to MOG were detected in 8/79 (10%) of the residual suspected cases of NMOSD. Under the 2015 IPND diagnostic criteria for NMOSD, cell-based assays for aquaporin-4 are sensitive and highly specific, performing better than tissue-based and ELISA assays. A fixed cell-based assay showed near-identical results to a live-cell based assay. Antibodies to MOG account for only a small number of suspected cases.

Patients with suspected benign tumors and glial fibrillary acidic protein autoantibody: an analysis of five cases

Aim: To investigate the clinical features of five glial fibrillary acidic protein (GFAP) antibody positive patients with suspected benign tumors and explore its underlying pathogenesis. Materials and methods: Overall, 1018 serum and cerebrospinal fluid (CSF) samples were tested by indirect immunofluorescence assay and data from five patients with suspected tumors and positive for GFAP autoantibody in the CSF were analyzed retrospectively. Results: The positive rate of GFAP antibody in the serum and CSF was 3.93% by indirect immunofluorescence assay. Tumors were diagnosed before or after neurologic onset in 5 of 40 patients (12.5%) and no deterioration of the tumors was found during the long-term follow-up. Of the five patients, one patient suffered a thyroid nodule, one patient had a small nodule in the left lung, two patients suffered meningiomas, and one patient had a suspicious eosinophilic granuloma. Conclusion: GFAP autoimmunity may be a paraneoplastic immune response with a low frequency of tumor in Chinese patients with GFAP astrocytopathy.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy: A Review of the Literature

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is an autoimmune disease of the nervous system first defined in 2016. GFAP autoantibody, especially IgG that binds to GFAPα, has been reported in the cerebrospinal fluid (CSF) and serum of patients with GFAP astrocytopathy. The positive predictive value of GFAP antibody in the CSF is higher than in the serum. Tissue-based assay (TBA) and cell-based assay (CBA) are both recommended methods for the detection of GFAP antibody. GFAP astrocytopathy is accompanied by neoplasms, but the relationship between virus infection and GFAP astrocytopathy is unclear. GFAP antibody itself does not induce pathological changes; it is only a biomarker for the process of immune inflammation. The pathology of GFAP astrocytopathy in humans is heterogeneous. GFAP astrocytopathy is commonly diagnosed in individuals over 40 years old and most patients have an acute or subacute onset. Clinical manifestations include fever, headache, encephalopathy, involuntary movement, myelitis, and abnormal vision. Lesions involve the subcortical white matter, basal ganglia, hypothalamus, brainstem, cerebellum, and spinal cord. The characteristic MRI feature is brain linear perivascular radial gadolinium enhancement in the white matter perpendicular to the ventricle. Currently, there are no uniform diagnostic criteria or consensus for GFAP astrocytopathy and coexisting neural autoantibodies detected in the same patient make the diagnosis difficult. A standard treatment regimen is yet to be developed. Most GFAP astrocytopathy patients respond well to steroid therapy although some patients are prone to relapse or even die.

Overlapping Autoimmune Syndromes in Patients With Glial Fibrillary Acidic Protein Antibodies

Background

Glial fibrillary acidic protein (GFAP) astrocytopathy, an autoimmune central nervous system disorder with a specific GFAP-IgG, often coexists with other antibodies.

Objective

The aim of this article was to study overlapping syndromes in autoimmune GFAP astrocytopathy.

Methods

Antibody was detected by indirect immunofluorescence assay. Patient data were analyzed retrospectively.

Results

Thirty patients with positive GFAP-IgG were included, of whom 10 were defined as overlapping syndrome. Four patients with positive aquaporin-4 (AQP4)-IgG, two with N-methyl-d-aspartate receptor-IgG, three with unknown neuronal antibodies, and one with double AQP4 and myelin oligodendrocyte glycoprotein-IgG were identified. GFAP-IgG and other specific antibodies occurred simultaneously at the initial attack in eight patients. The main symptoms included fever, headache, ataxia, psychosis, hypersomnia, dyskinesia, dementia, seizure, myelitis, and optical symptoms. Brain magnetic resonance imaging in four patients revealed characteristic radial enhancing patterns in the white matter. Cortical abnormalities were found in four patients. Other brain abnormalities occurred in the hypothalamus, midbrain, pons, medulla, cerebellum, and meninges. Six patients exhibited lesions in the spinal cord. In a subgroup study, patients with overlapping syndrome were younger at onset than those with non-overlapping syndrome.

Conclusion

Overlapping antibodies are common in GFAP astrocytopathy.

Defining distinct features of anti-MOG antibody associated central nervous system demyelination

Extensive research over the last decades basically failed to identify a common cause of noninfectious inflammatory central nervous system (CNS) demyelinating disease. To a great extent, this may reflect that the group of inflammatory CNS demyelinating disorders likely contains multiple pathogenetically distinct disease entities. Indeed, the greatest success so far in deciphering the pathogenesis of a CNS demyelinating disorder resulted from the discovery of anti-aquaporin (AQP)-4 antibodies (ab), which allowed progressive delineation of neuromyelitis optica (NMO), formerly considered a variant of the most common CNS demyelinating disorder, multiple sclerosis (MS), as a distinct disease. Nowadays, AQP-4⁺ NMO is considered an autoimmune astrocytopathy, in which CNS demyelination occurs only as a consequence of a primary destruction of astrocytes. Delineating these patients concomitantly revealed that not all patients presenting with clinically NMO-suggestive disease phenotype express AQP-4 ab, which created the pathogenetically undefined category of NMO spectrum disorders (NMOSD). Recent investigations discovered that a subgroup of these AQP-4^– NMOSD patients produce an ab response against myelin oligodendrocyte glycoprotein (MOG), a molecule expressed on the outer lamella of the myelin sheath. Using pathophysiologically meaningful cell-based assays, this humoral response is extremely rare in adult MS and absent in classical AQP-4⁺ NMO, sharply differentiating the evolving group from both established disorders. In this review, we summarize available clinical, immunological and histopathological data on patients with MOG⁺ CNS demyelinating disease. By comparing this clearly distinct cohort to AQP-4⁺ NMO as well as MS, we propose that MOG⁺ CNS demyelinating disease represents a distinct novel disease entity. In addition to its diagnostic value, we furthermore provide mechanistic insight on how this peripheral anti-MOG ab response may be of pathogenetic relevance in triggering acute flares of inflammatory CNS demyelination.

Diversity of astroglial responses across human neurodegenerative disorders and brain aging

Astrogliopathy refers to alterations of astrocytes occurring in diseases of the nervous system, and it implies the involvement of astrocytes as key elements in the pathogenesis and pathology of diseases and injuries of the central nervous system. Reactive astrocytosis refers to the response of astrocytes to different insults to the nervous system, whereas astrocytopathy indicates hypertrophy, atrophy/degeneration and loss of function and pathological remodeling occurring as a primary cause of a disease or as a factor contributing to the development and progression of a particular disease. Reactive astrocytosis secondary to neuron loss and astrocytopathy due to intrinsic alterations of astrocytes occur in neurodegenerative diseases, overlap each other, and, together with astrocyte senescence, contribute to disease-specific astrogliopathy in aging and neurodegenerative diseases with abnormal protein aggregates in old age. In addition to the well-known increase in glial fibrillary acidic protein and other proteins in reactive astrocytes, astrocytopathy is evidenced by deposition of abnormal proteins such as β-amyloid, hyper-phosphorylated tau, abnormal α-synuclein, mutated huntingtin, phosphorylated TDP-43 and mutated SOD1, and PrPres , in Alzheimer's disease, tauopathies, Lewy body diseases, Huntington's disease, amyotrophic lateral sclerosis and Creutzfeldt-Jakob disease, respectively. Astrocytopathy in these diseases can also be manifested by impaired glutamate transport; abnormal metabolism and release of neurotransmitters; altered potassium, calcium and water channels resulting in abnormal ion and water homeostasis; abnormal glucose metabolism; abnormal lipid and, particularly, cholesterol metabolism; increased oxidative damage and altered oxidative stress responses; increased production of cytokines and mediators of the inflammatory response; altered expression of connexins with deterioration of cell-to-cell networks and transfer of gliotransmitters; and worsening function of the blood brain barrier, among others. Increased knowledge of these aspects will permit a better understanding of brain aging and neurodegenerative diseases in old age as complex disorders in which neurons are not the only players.

The pathology of an autoimmune astrocytopathy: lessons learned from neuromyelitis optica

Neuromyelitis optica (NMO) is a disabling autoimmune astrocytopathy characterized by typically severe and recurrent attacks of optic neuritis and longitudinally extensive myelitis. Until recently, NMO was considered an acute aggressive variant of multiple sclerosis (MS), despite the fact that early studies postulated that NMO and MS may be two distinct diseases with a common clinical picture. With the discovery of a highly specific serum autoantibody (NMO-IgG), Lennon and colleagues provided the first unequivocal evidence distinguishing NMO from MS and other central nervous system (CNS) inflammatory demyelinating disorders. The target antigen of NMO-IgG was confirmed to be aquaporin-4 (AQP4), the most abundant water channel protein in the CNS, mainly expressed on astrocytic foot processes at the blood-brain barrier, subpial and subependymal regions. Pathological studies demonstrated that astrocytes were selectively targeted in NMO as evidenced by the extensive loss of immunoreactivities for the astrocytic proteins, AQP4 and glial fibrillary acidic protein (GFAP), as well as perivascular deposition of immunoglobulins and activation of complement even within lesions with a relative preservation of myelin. In support of these pathological findings, GFAP levels in the cerebrospinal fluid (CSF) during acute NMO exacerbations were found to be remarkably elevated in contrast to MS where CSF-GFAP levels did not substantially differ from controls. Additionally, recent experimental studies showed that AQP4 antibody is pathogenic, resulting in selective astrocyte destruction and dysfunction in vitro, ex vivo and in vivo. These findings strongly suggest that NMO is an autoimmune astrocytopathy where damage to astrocytes exceeds both myelin and neuronal damage. This chapter will review recent neuropathological studies that have provided novel insights into the pathogenic mechanisms, cellular targets, as well as the spectrum of tissue damage in NMO.

Molecular pathogenesis of neuromyelitis optica

Neuromyelitis optica (NMO) is a rare autoimmune disorder, distinct from multiple sclerosis, causing inflammatory lesions in the optic nerves and spinal cord. An autoantibody (NMO IgG) against aquaporin-4 (AQP4), a water channel expressed on astrocytes is thought to be causative. Peripheral production of the antibody is triggered by an unknown process in genetically susceptible individuals. Anti-AQP4 antibody enters the central nervous system (CNS) when the blood brain barrier is made permeable and has high affinity for orthogonal array particles of AQP4. Like other autoimmune diseases, Th17 cells and their effector cytokines (such as interleukin 6) have been implicated in pathogenesis. AQP4 expressing peripheral organs are not affected by NMO IgG, but the antibody causes extensive astrocytic loss in specific regions of the CNS through complement mediated cytotoxicity. Demyelination occurs during the inflammatory process and is probably secondary to oligodendrocyte apoptosis subsequent to loss of trophic support from astrocytes. Ultimately, extensive axonal injury leads to severe disability. Despite rapid advances in the understanding of NMO pathogenesis, unanswered questions remain, particularly with regards to disease mechanisms in NMO IgG seronegative cases. Increasing knowledge of the molecular pathology is leading to improved treatment strategies.