Severe anti-GAD antibody-associated encephalitis after stem cell transplantation

Glutamic acid decarboxylase antibody-spectrum disorders and type 1 diabetes mellitus in a patient following allogenic hematopoietic cell transplantation with review of literature

Glutamic acid decarboxylase (GAD) is an enzyme that catalyzes the conversion of glutamic acid into γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the central nervous system (CNS). GAD is widely expressed in the CNS and pancreatic β-cells. GABA produced by GAD plays a role in regulating insulin secretion in pancreatic islets. Anti-GAD antibody is an established marker of type 1 diabetes mellitus (T1DM) and is also associated with stiff-person syndrome (SPS) and several other neurological disorders, including ataxia, cognitive impairment, limbic encephalitis, and epilepsy, collectively referred to as GAD antibody-spectrum disorders (GAD-SD). We report the case of a 17-year-old male patient who developed GAD-SD and T1DM after allogeneic hematopoietic cell transplantation (HCT). He presented with memory disorders, including feelings of déjà vu, accompanied by vomiting and headaches, and exhibited abnormal brain magnetic resonance imaging and electroencephalogram results. In addition to elevated fasting plasma glucose and glycated hemoglobin levels, markedly elevated anti-GAD antibody levels were detected in the serum and cerebrospinal fluid. Based on these findings, the patient was diagnosed with GAD-SD and T1DM and treated with methylprednisolone, followed by multiple daily insulin injections. We also reviewed previously reported cases of GAD-SD following HCT and multiple positive islet-related antibodies.

Case report: Autoimmune encephalomyelitis following cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation

Introduction

Cytomegalovirus (CMV) can cause various end-organ diseases in immunocompromised hosts, including allogeneic hematopoietic cell transplant (allo-HSCT) recipients. Interestingly, CMV viremia has been associated with various complications and poor prognosis in allo-HSCT recipients. Complications involving the central nervous system (CNS) occur in 9-14% of patients following allo-HSCT. However, autoimmune encephalitis (AE) secondary to CMV infection after allo-HSCT has rarely been reported. Here we report a case of possible AE following CMV viremia after allo-HSCT, which was successfully treated with high-dose pulsed methylprednisolone and intravenous immunoglobulins (IVIg).

Case description

A 53-year-old female underwent allo-HSCT for T-lymphoblastic lymphoma/leukemia. The patient developed CMV viremia on day 36 after transplantation, and serum CMV-DNA remained positive after initiating ganciclovir antiviral therapy, turning negative one month later. Four months later, she started experiencing memory impairment, weakness in the left limbs, cognitive dysfunction, and hallucinations. A magnetic resonance imaging brain scan showed scattered ischemic lesions under the bilateral frontal cortex. Viral detection in cerebral spinal fluid (CSF) by next-generation gene sequencing technology showed no obvious abnormality. Antibodies specific to AE and paraneoplastic diseases in serum and CSF were absent. The oligoclonal bands in the CSF were detected using isoelectric focusing and immunofixation, and the results were negative. However, after extensive investigation regarding infections, autoimmune disorders, and recurrence of the malignancy, possible AE could not be excluded. The patient was treated with high-dose steroids combined with IVIg therapy; the patient's symptoms were significantly improved.

Conclusion

The mechanisms of AE after allo-HSCT and the relationship with CMV infection should be further studied. Therefore, reporting this and similar cases will improve our awareness and understanding of the underlying disease mechanisms.

Successfully treated anti-GAD limbic encephalitis in a 15-year-old diabetic boy with intravenous immunoglobulin: case report

Introduction and importance

Limbic encephalitides (LE) have symptoms and signs of new-onset seizures accompanied by cognitive impairment and signal changes in the MRI of the limbic system in the brain. Numerous antibodies against the neurons and synapses have been detected so far. Of those, antiglutamic acid decarboxylase antibody (Anti-GAD Ab) impairs the gamma amino butyric acid, one of the primary mediators that naturally prevents abnormal neuronal activity causing seizure.

Case presentation

The authors have reported a case of anti-GAD Ab LE in a diabetic male adolescent who responded dramatically to intravenous immunoglobulin and reviewed all similar pediatric cases for 15 years now.

Clinical discussion

The symptoms in children suffering from anti-GAD LE in three categories, systemic, psychiatric, and neurological, are heterogeneous. The most common manifestations were seizures followed by altered mental status and behavioral changes, respectively. The two main clinical scenarios described in GAD65-mediated autoimmune epilepsy are (1) an acute/subacute onset of seizures alone or seizures (including new-onset refractory status epilepticus, NORSE) accompanied by some degrees of cognitive and psychiatric manifestations, including amnesia and mesiotemporal inflammatory involvement consistent with LE and (2) epilepsy without clinical or MRI evidence of active central nervous system inflammation.

Conclusion

Although rare, the neurologist should consider the potential role of anti-GAD ab-associated encephalitis in the presence of diabetes mellitus.

Hematologic malignancies and hematopoietic stem cell transplantation

Paraneoplastic neurologic syndromes are rarely associated with hematologic malignancies. In their rarity, lymphomas are the diseases with more frequent paraneoplastic neurologic syndrome. High-risk antibodies are absent in most lymphoma-associated paraneoplastic neurologic syndromes, with the exception of antibodies to Tr/DNER in paraneoplastic cerebellar degeneration, mGluR5 in limbic encephalitis, and mGluR1 in some cerebellar ataxias. Peripheral nervous system paraneoplastic neurologic syndromes are rare and heterogeneous, with a prevalence of demyelinating polyradiculoneuropathy in non-Hodgkin lymphoma. Polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes (POEMS) is a rare, paraneoplastic syndrome due to an underlying plasma cell disorder. The diagnosis is based on defined criteria, and vascular endothelial growth factor (VEGF), not an antibody, is considered a reliable diagnostic marker that also mirrors therapy response. As with the paraneoplastic neurologic syndromes in solid tumors, therapies rely on cancer treatment associated with immunomodulatory treatment with better response in PNS with antibodies to surface antigens. The best outcome is generally present in Ophelia syndrome/limbic encephalitis with anti-mGluR5 antibodies, with frequent complete recovery. Besides patients with isolated osteosclerotic lesions (where radiotherapy is indicated), hematopoietic stem-cell transplantation is the therapy of choice in patients with POEMS syndrome. In the paraneoplastic neurologic syndromes secondary to immune checkpoint inhibitors, discontinuation of the drug together with immunomodulatory treatment is recommended.

Case report: Successful autologous hematopoietic stem cell transplantation in a patient with GAD antibody-spectrum disorder with rapidly progressive dementia

The prevalence of neurological syndromes associated with antibodies to glutamic acid decarboxylase is increasing. While cognitive impairment is a common feature of this condition, it seldom emerges as the primary symptom. In this study, we discuss a case of refractory dementia associated with the glutamic acid decarboxylase spectrum disorder. Interestingly, this case showed a favorable outcome following autologous hematopoietic stem cell transplantation. We also provide an in-depth review of the current literature on the use of this therapeutic approach for the treatment of this disease.

Positive Predictive Value of Anti-GAD65 ELISA Cut-Offs for Neurological Autoimmunity

High anti-GAD65 levels associate with core manifestations of GAD65 neurological autoimmunity. ELISA cut-offs for high anti-GAD65 levels (>10,000 IU/ml in serum, >100 IU/ml in CSF) have been proposed that merit further evaluation. We reviewed patients who underwent anti-GAD65 ELISA for suspected autoimmune encephalitis and found values above these cut-offs to have a positive predictive value (PPV) for neurological autoimmunity of 88%. Anti-GAD65 values above proposed ELISA cut-offs have a reasonably high PPV for neurological autoimmunity in patients with suspected autoimmune encephalitis. Consideration of alternative diagnoses and corroboration with CSF can help flag potentially clinically irrelevant results and avoid patient misdiagnosis.

Stem Cell Therapy in Neuroimmunological Diseases and Its Potential Neuroimmunological Complications

Background: Since the 1990s, transplantations of hematopoietic and mesenchymal stem cells (HSCT and MSCT) and dendritic cell (DCT) have been investigated for the treatment of neurological autoimmune disorders (NADs). With the growing number of transplanted patients, awareness of neuroimmunolgical complications has increased. Therefore, an overview of SCT for the most common NADs and reports of secondary immunity after SCT is provided. Methods: For this narrative review, a literature search of the PubMed database was performed. A total of 86 articles reporting on different SCTs in NADs and 61 articles dealing with immune-mediated neurological complications after SCT were included. For multiple sclerosis (MS), only registered trials and phase I/II or II studies were considered, whereas all available articles on other disorders were included. The different transplantation procedures and efficacy and safety data are presented. Results: In MS patients, beneficial effects of HSCT, MSCT, and DCT with a decrease in disability and stabilization of disease activity have been reported. These effects were also shown in other NADs mainly in case reports. In seven of 132 reported patients with immune-mediated neurological complications, the outcome was fatal. Conclusions: Phase III trials are ongoing for MS, but the role of SCT in other NADs is currently limited to refractory patients due to occasional serious complications.

Hematopoietic Stem Cell Transplantation for Neurological Disorders: A Focus on Inborn Errors of Metabolism

Hematopoietic stem cells have been investigated and applied for the treatment of certain neurological disorders for a long time. Currently, their therapeutic potential is harnessed in autologous and allogeneic hematopoietic stem cell transplantation (HSCT). Autologous HSCT is helpful in immune-mediated neurological diseases such as Multiple Sclerosis. However, clinical benefits derive more from the immunosuppressive conditioning regimen than the interaction between stem cells and the nervous system. Mainly used for hematologic malignancies, allogeneic HSCT explores the therapeutic potential of donor-derived hematopoietic stem cells. In the neurological setting, it has proven to be most valuable in Inborn Errors of Metabolism, a large spectrum of multisystem disorders characterized by congenital deficiencies in enzymes involved in metabolic pathways. Inborn Errors of Metabolism such as X-linked Adrenoleukodystrophy present with brain accumulation of enzymatic substrates that result in progressive inflammatory demyelination. Allogeneic HSCT can halt ongoing inflammatory neural destruction by replacing hematopoietic-originated microglia with donor-derived myeloid precursors. Microglia, the only neural cells successfully transplanted thus far, are the most valuable source of central nervous system metabolic correction and play a significant role in the crosstalk between the brain and hematopoietic stem cells. After transplantation, engrafted donor-derived myeloid cells modulate the neural microenvironment by recapitulating microglial functions and enhancing repair mechanisms such as remyelination. In some disorders, additional benefits result from the donor hematopoietic stem cell secretome that cross-corrects neighboring neural cells via mannose-6-phosphatase paracrine pathways. The limitations of allogeneic HSCT in this setting relate to the slow turnover of microglia and complications such as graft-vs.-host disease. These restraints have accelerated the development of hematopoietic stem cell gene therapy, where autologous hematopoietic stem cells are collected, manipulated ex vivo to overexpress the missing enzyme, and infused back into the patient. With this cellular drug vehicle strategy, the brain is populated by improved cells and exposed to supraphysiological levels of the flawed protein, resulting in metabolic correction. This review focuses on the mechanisms of brain repair resulting from HSCT and gene therapy in Inborn Errors of Metabolism. A brief mention will also be made on immune-mediated nervous system diseases that are treated with this approach.

Stiff Person Syndrome and Encephalitis with GAD Antibodies with Severe Anterograde Amnesia in an Adolescent: A Case Study and Literature Review

Antiglutamic acid decarboxylase (GAD65) encephalitis is rare and few pediatric cases have been reported, with variable clinical presentations. A 14-year-old female adolescent was managed in our department. She had been treated for several months for drug-resistant temporal lobe epilepsy and gradually presented major anterograde amnesia with confusion. Upon her arrival at the University Hospital Centre, she showed a classical form of stiff person syndrome. The brain magnetic resonance imaging showed bitemporal hyperintensities and hypertrophy of the amygdala. The blood and cerebrospinal fluid were positive for GAD65 antibodies. At 2 years of immunosuppressive treatment and rehabilitation, the course showed partial improvement of the memory and neuropsychiatric impairment, and epilepsy that continued to be active. GAD65 antibodies are associated with various neurological syndromes, and this presentation combining limbic encephalitis and stiff person syndrome is the first pediatric form published to date; there are also few cases described in adults.

Autoimmune Encephalitis in Tunisia: Report of a Pediatric Cohort

BACKGROUND

Autoimmune encephalitis (AE) is a rapidly progressive encephalopathy caused by antibodies targeting neurons in the central nervous system generating specific immune responses. It is increasingly recognized in children.

OBJECTIVE

To describe clinical, neuroimaging, and laboratory features, treatment, and outcome in a cohort of Tunisian children with AE.

METHODS

We conducted a retrospective review of the medical records of all children attending the Department of Child and Adolescent Neurology (Tunis) with autoimmune encephalitis between 2004 and 2020. Clinical, neuroimaging, laboratory features, therapeutic data, and outcome were analyzed.

RESULTS

Nineteen children were included in the study (12 girls and 7 boys). The median age at diagnosis was 7.68 years (range: 10 months-13 years). The most frequent manifestations were seizures and behavioral disorders. Eleven cases were diagnosed with anti-NMDA receptor encephalitis, 4 cases with anti-Ma2 encephalitis, 3 cases with anti-GAD encephalitis, and 1 case with anti-SOX1 encephalitis. Brain MRI showed increased T2 and fluid-attenuated inversion recovery (FLAIR) signal of the temporal lobe in 5 patients. Eighteen patients showed improvement following first-line immunotherapy (high-dose corticosteroids, intravenous immunoglobulin). One patient with anti-GAD encephalitis died despite escalating immunotherapy.

CONCLUSION

Diagnosis of autoimmune encephalitis is challenging in children, because of misleading presentations. An early and accurate diagnosis is important to enable proper therapeutic interventions.

Severe allo-immune antibody-associated peripheral and central nervous system diseases after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a curative treatment for hematologic malignancies. Acute and chronic graft-versus-host disease (GvHD) are the major immune-mediated complications after alloHSCT. However, there is controversy whether neurologic complications after alloHSCT might represent manifestations of GvHD. We report three patients who acquired distinct, severe immune-mediated peripheral or central nervous system diseases after alloHSCT without other, concomitant GvHD manifestations. One patient had been diagnosed with B-cell chronic lymphocytic leukemia and two patients with high risk myelodysplastic syndrome. Patient #1 presented as LGI1- and GAD-IgG positive immune-mediated encephalitis, patient #2 was diagnosed with MOG-IgG positive encephalomyelitis, and patient #3 had chronic inflammatory polyneuropathy associated with SSA(Ro)-IgG positive Sjögren's syndrome. 100% donor chimerism was detectable in the peripheral blood in all three. The specific antibodies were undetectable in donors' and patients' blood before alloHSCT suggesting that the antibodies had arisen from the transplanted donor immune system. Early intensive immunotherapy led to improvement of clinical symptoms and stability of the neurological disease, however, at the cost of losing the graft-versus-malignancy effect in one patient. In conclusion, we provide evidence of isolated, severe allo-immune diseases of the peripheral and central nervous system as complications of alloHSCT ("neuro-GvHD"). Interdisciplinary surveillance and thorough diagnostic work-up are needed for early diagnosis and treatment of neuro-immunologic complications after alloHSCT to improve the otherwise poor outcome.

Case Report: Autoimmune Encephalitis Associated With Anti-glutamic Acid Decarboxylase Antibodies: A Pediatric Case Series

Background: Antibodies against glutamic acid decarboxylase (GAD) are associated with various neurologic conditions described in patients, including stiff person syndrome, cerebellar ataxia, refractory epilepsy, and limbic and extralimbic encephalitis. There have been some case reports and investigations regarding anti-GAD65 antibody-associated encephalitis in adult populations, but pediatric cases are rare. We retrospectively analyzed the clinical data of three anti-GAD65 antibody-positive patients to explore the diversity and clinical features of anti-GAD65 antibody-associated pediatric autoimmune encephalitis.

Methods: The clinical data of a series of three patients positive for anti-GAD65 antibody were retrospectively analyzed. GAD65 antibodies were determined in serum and CSF using a cell-based assay.

Results: All three patients were female, and the onset ages were 4 years and 9 months, 6 years, and 16 years old. Their clinical phenotypes included autoimmune limbic encephalitis, extralimbic encephalitis, and encephalitis combining limbic and extralimbic encephalitis. The clinical symptoms included seizures, memory deficits, drowsiness, dysautonomia, and headache. All patients had abnormal carinal MRI and EEG. All patients received immunotherapy and had transiently good responsiveness, but one patient then experienced relapse. In follow-up, one patient with extralimbic encephalitis recovered completely, while two patients with limbic involvement had poor outcomes with refractory focal epilepsy.

Conclusion: In addition to limbic encephalitis, extralimbic encephalitis is also an important phenotype in patients who are positive for anti-GAD65 antibodies. Early diagnosis and immunotherapy can improve the symptoms. However, patients with limbic encephalitis often have refractory epilepsy in the chronic phase and have a poor long-term outcome.

Rare presentation of anti-GAD-65 antibody-positive autoimmune encephalitis and simultaneous onset of type 1 diabetes mellitus in a paediatric patient

A 16-year-old female patient presented with subacute onset of headaches, changes in acute mental status, expressive aphasia and auditory hallucinations. New oedema and enhancement of the temporal lobe were seen on brain MRI, with correlating subclinical seizures seen on electroencephalogram. Simultaneously, our patient was diagnosed with new-onset type 1 diabetes mellitus, with positive anti-glutamic acid decarboxylase (anti-GAD-65) antibodies in the serum. Cerebrospinal fluid studies remained negative, including anti-GAD-65 antibodies. Clinical remission was achieved with corticosteroids and intravenous immunoglobulins.

Clinical characteristics and outcomes of autoimmune encephalitis patients associated with anti-glutamate decarboxylase antibody 65

OBJECTIVE

This study was to investigate the clinical characteristics and prognosis of autoimmune encephalitis (AE) associated with anti-Glutamic Acid Decarboxylase 65 (GAD65).

PATIENTS AND METHODS

From Jan 2016 to Aug 2018, three patients diagnosed as anti-GAD65 AE in our hospital were retrospectively analyzed for their general demographic characteristics, clinical presentation, cerebrospinal fluid (CSF) cytology, brain imaging, EEG, treatment and prognosis.

RESULTS

We found that Anti-GAD65 AE may be more common in young and middle-aged women, with initial presentations of refractory status epilepticus or cognitive decline following the disease progresses, but with less psychiatric symptoms than other types of AEs. The abnormal signals of MRI may be obvious in bilateral frontal, temporal lobe and hippocampus.

CONCLUSION

The production of anti-GAD65 may have a certain latency period, and it is usually negative at the onset stage. More studies need to be performed on larger populations and further understand the potential mechanisms underlying the above clinical features of anti-GAD65 AE.

Intravenous methylprednisolone or immunoglobulin for anti-glutamic acid decarboxylase 65 antibody autoimmune encephalitis: which is better?

BACKGROUND

Patients positive for anti-glutamic acid decarboxylase 65 (GAD65) antibodies have attracted increasing attention. Their clinical manifestations are highly heterogeneous and can be comorbid with tumors. Currently, there is no consensus on the therapeutic regimen for anti-GAD65-associated neurological diseases due to the clinical complexity, rarity and sporadic distribution. We reported six anti-GAD65 autoimmune encephalitis (AE) patients who received intravenous methylprednisolone (IVMP) or immunoglobulin (IVIG) or both. Then, we evaluated the therapeutic effect of both by summarizing results in previous anti-GAD65 AE patients from 70 published references.

RESULTS

Our six patients all achieved clinical improvements in the short term. Unfortunately, there was no significant difference between IVMP and IVIG in terms of therapeutic response according to the previous references, and the effectiveness of IVMP and IVIG was 45.56% and 36.71%, respectively. We further divided the patients into different subgroups according to their prominent clinical manifestations. The response rates of IVMP and IVIG were 42.65% and 32.69%, respectively, in epilepsy patients; 60.00% and 77.78%, respectively, in patients with stiff-person syndrome; and 28.57% and 55.56%, respectively, in cerebellar ataxia patients. Among 29 anti-GAD65 AE patients with tumors, the response rates of IVMP and IVIG were 29.41% and 42.11%, respectively. There was no significant difference in effectiveness between the two regimens among the different subgroups.

CONCLUSION

Except for stiff-person syndrome, we found that this kind of AE generally has a poor response to IVMP or IVIG. Larger prospective studies enrolling large numbers of patients are required to identify the optimal therapeutic strategy in the future.

Clinical Characterization of Definite Autoimmune Limbic Encephalitis: A 30-case Series

Objective Limbic encephalitis (LE) is an inflammatory condition of the limbic system that has an acute or subacute onset. Several types of antibodies are related to the onset of LE, including anti-N-methyl D-aspartate receptor (NMDAR) antibodies and voltage-gated potassium channel (VGKC)-complex antibodies. However, the characteristics and prevalence of LE remain unclear, especially in Asian cohorts, due to the rarity. We aimed to survey their characteristics. Materials and Methods Data of 30 cases clinically defined as "definite autoimmune LE" (based on the standard criteria) were retrospectively collected. These patients were categorized into four subtypes: NMDAR (+) (n=8), VGKC (+) (n=2), antibodies related to paraneoplastic syndrome (n=2), and an antibody-negative group (uncategorized) (n=18). Results LE is rare in Japan, and affected only 30 of 16,759 hospital patients (0.2%) over a ten-year period. The NMDAR (+) group showed distinctive symptoms, while the other three groups had similar indications. Brain MRI indicated significant medial temporal lobe atrophy at one year follow up after discharge. The prevalence of cognitive dysfunction as a complication was 64% (9/14). First-line immunotherapy resulted in a good outcome. A drastic improvement was seen from 4.0±1.1 to 1.1+ on the modified Rankin Scale. A good treatment outcome was observed in all groups (NMDAR, VGKC, and uncategorized), suggesting the importance of an early clinical diagnosis and the early initiation of treatment. Furthermore, we reviewed 26 cases that were clinically diagnosed as definitive autoimmune LE in previous case reports. Conclusion Our findings show that the establishment of a clinical diagnosis based on the clinical criteria of definitive autoimmune LE is important for the initiation of immunotherapy.