Is there an immunological cross-reactivity of antibodies to the myelin oligodendrocyte glycoprotein and coronaviruses?

Recent reports indicated that myelin oligodendrocyte glycoprotein antibody-associated disease might be a rare complication after severe acute respiratory syndrome coronavirus 2 infection or vaccination. It is unclear whether this is an unspecific sequel of infection or vaccination or caused by possible immunological cross-reactivity of severe acute respiratory syndrome coronavirus 2 proteins and myelin oligodendrocyte glycoprotein. The aim of this study was therefore to elucidate whether there is an immunological cross-reactivity between severe acute respiratory syndrome coronavirus 2 spike or nucleocapsid proteins and myelin oligodendrocyte glycoprotein and to explore the relation of antibody responses against myelin oligodendrocyte glycoprotein and severe acute respiratory syndrome coronavirus 2 and other coronaviruses. We analysed serum samples from patients with severe acute respiratory syndrome coronavirus 2 infection and neurological symptoms with (myelin oligodendrocyte glycoprotein antibody-associated disease, n = 12) or without myelin oligodendrocyte glycoprotein-antibodies (n = 10); severe acute respiratory syndrome coronavirus 2 infection without neurological symptoms (n = 32); vaccinated patients with no history of severe acute respiratory syndrome coronavirus 2 infection and neurological symptoms with (myelin oligodendrocyte glycoprotein antibody-associated disease, n = 10) or without myelin oligodendrocyte glycoprotein-antibodies (n = 9); and severe acute respiratory syndrome coronavirus 2 negative/naïve unvaccinated patients with neurological symptoms with (myelin oligodendrocyte glycoprotein antibody-associated disease, n = 47) or without myelin oligodendrocyte glycoprotein-antibodies (n = 20). All samples were analysed for serum antibody responses to myelin oligodendrocyte glycoprotein, severe acute respiratory syndrome coronavirus 2, and other common coronaviruses (CoV-229E, CoV-HKU1, CoV-NL63 and CoV-OC43). Based on sample amount and antibody titres, 21 samples were selected for analysis of antibody cross-reactivity between myelin oligodendrocyte glycoprotein and severe acute respiratory syndrome coronavirus 2 spike and nucleocapsid proteins using affinity purification and pre-absorption. Whereas we found no association of immunoglobulin G and A myelin oligodendrocyte glycoprotein antibodies with coronavirus antibodies, infections with severe acute respiratory syndrome coronavirus 2 correlated with an increased immunoglobulin M myelin oligodendrocyte glycoprotein antibody response. Purified antibodies showed no cross-reactivity between severe acute respiratory syndrome coronavirus 2 spike protein and myelin oligodendrocyte glycoprotein. However, one sample of a patient with myelin oligodendrocyte glycoprotein antibody-associated disease following severe acute respiratory syndrome coronavirus 2 infection showed a clear immunoglobulin G antibody cross-reactivity to severe acute respiratory syndrome coronavirus 2 nucleocapsid protein and myelin oligodendrocyte glycoprotein. This patient was also seropositive for other coronaviruses and showed immunological cross-reactivity of severe acute respiratory syndrome coronavirus 2 and CoV-229E nucleocapsid proteins. Overall, our results indicate that an immunoglobulin G antibody cross-reactivity between myelin oligodendrocyte glycoprotein and severe acute respiratory syndrome coronavirus 2 proteins is rare. The presence of increased myelin oligodendrocyte glycoprotein-immunoglobulin M antibodies after severe acute respiratory syndrome coronavirus 2 infection may either be a consequence of a previous infection with other coronaviruses or arise as an unspecific sequel after viral infection. Furthermore, our data indicate that myelin oligodendrocyte glycoprotein-immunoglobulin A and particularly myelin oligodendrocyte glycoprotein-immunoglobulin M antibodies are a rather unspecific sequel of viral infections. Finally, our findings do not support a causative role of coronavirus infections for the presence of myelin oligodendrocyte glycoprotein-immunoglobulin G antibodies.

HLA-DQB1*05 subtypes and not DRB1*10:01 mediates risk in anti-IgLON5 disease.

Anti-IgLON5 disease is a rare and likely underdiagnosed subtype of autoimmune encephalitis. The disease displays a heterogeneous phenotype that includes sleep, movement, and bulbar-associated dysfunction. Presence of IgLON5-antibodies in CSF/serum, together with a strong association with HLA-DRB1*10:01∼DQB1*05:01, support an autoimmune basis. In this study, a multicentric HLA study of 87 anti-IgLON5 patients revealed a stronger association with HLA-DQ than HLA-DR. Specifically, we identified a predisposing rank-wise association with HLA-DQA1*01:05∼DQB1*05:01, HLA-DQA1*01:01∼DQB1*05:01 and HLA-DQA1*01:04∼DQB1*05:03 in 85% of patients. HLA sequences and binding cores for these three DQ heterodimers were similar, unlike those of linked DRB1 alleles, supporting a causal link to HLA-DQ. This association was further reflected in an increasingly later age of onset across each genotype group, with a delay of up to 11 years, while HLA-DQ-dosage dependent effects were also suggested by reduced risk in the presence of non-predisposing DQ1 alleles. The functional relevance of the observed HLA-DQ molecules was studied with competition binding assays. These proof-of-concept experiments revealed preferential binding of IgLON5 in a post-translationally modified, but not native, state to all three risk-associated HLA-DQ receptors. Further, a deamidated peptide from the Ig2-domain of IgLON5 activated T cells in two patients, compared to one control carrying HLA-DQA1*01:05∼DQB1*05:01. Taken together, these data support a HLA-DQ-mediated T cell response to IgLON5 as a potentially key step in the initiation of autoimmunity in this disease.

Autoimmune Movement Disorders Complicating Treatment with Immune Checkpoint Inhibitors.

BACKGROUND: Immune checkpoint inhibitors (ICI) may trigger autoimmune neurological conditions, including movement disorders (MD). OBJECTIVES: The aim of this study was to characterize MDs occurring as immune-related adverse events (irAEs) of ICIs. METHODS: A systematic literature review of case reports/series of MDs as irAEs of ICIs was performed. RESULTS: Of 5682 eligible papers, 26 articles with 28 patients were included. MDs occur as a rare complication of cancer immunotherapy with heterogeneous clinical presentations and in most cases in association with other irAEs. Inflammatory basal ganglia T2/fluid attenuated inversion recovery abnormalities are rarely observed, but brain imaging is frequently unrevealing. Cerebrospinal fluid findings are frequently suggestive of inflammation. Half of cases are associated with a wide range of autoantibodies. Steroids and ICI withdrawal usually lead to improvement, even though some patients experienced relapses or a severe clinical course. CONCLUSION: MDs are a rare complication of ICIs that should be promptly recognized to offer patients a correct diagnosis and treatment.

Serum Biomarker Profiles Discriminate AQP4 Seropositive and Double Seronegative Neuromyelitis Optica Spectrum Disorder.

BACKGROUND AND OBJECTIVES: Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) serum levels are useful to define disease activity in different neurologic conditions. These biomarkers are increased in patients with aquaporin-4 antibody-positive NMOSD (AQP4+NMOSD) during clinical attacks suggesting a concomitant axonal and glial damage. However, there are contradictory results in double seronegative NMOSD (DS-NMOSD). The aim of this study was to characterize the neuronal, axonal, and glial damage of DS-NMOSD in comparison with AQP4+NMOSD. METHODS: Patients with DS-NMOSD (i.e., for AQP4 and myelin oligodendrocyte glycoprotein antibodies-MOG-Abs) and age-matched AQP4+NMOSD diagnosed according to the latest diagnostic criteria and with available serum samples obtained within 3 months from onset/relapse were retrospectively enrolled from 14 international centers. Clinical and radiologic data were collected. Serum NfL, GFAP, tau, and UCH-L1 levels were determined using an ultrasensitive paramagnetic bead-based ELISA (SIMOA). Statistical analysis was performed using nonparametric tests and receiver-operating characteristic (ROC) curve analysis. RESULTS: We included 25 patients with AQP4+NMOSD and 26 with DS-NMOSD. The median age at disease onset (p = 0.611) and female sex predominance (p = 0.072) were similar in the 2 groups. The most common syndromes at sampling in both AQP4+NMOSD and DS-NMOSD were myelitis (56% vs 38.5%) and optic neuritis (34.6% vs 32%), with no statistical differences (p = 0.716). Median EDSS at sampling was 3.2 (interquartile range [IQR] 2-7.7) in the AQP4+NMOSD group and 4 (IQR [3-6]) in the DS-NMOSD group (p = 0.974). Serum GFAP, tau, and UCH-L1 levels were higher in patients with AQP4+NMOSD compared with those with DS-NMOSD (median 308.3 vs 103.4 pg/mL p = 0.001; median 1.2 vs 0.5 pg/mL, p = 0.001; and median 61.4 vs 35 pg/mL, p = 0.006, respectively). The ROC curve analysis showed that GFAP, tau, and UCH-L1, but not NfL, values were able to discriminate between AQP4+ and DS-NMOSD (area under the curve (AUC) tau: 0.782, p = 0.001, AUC GFAP: 0.762, p = 0.001, AUC UCH-L1: 0.723, p = 0.006). NfL levels were associated with EDSS at nadir only in patients with AQP4+NMOSD. DISCUSSION: Serum GFAP, tau, and UCH-L1 levels discriminate between AQP4+NMOSD and DS-NMOSD. The different biomarker profile of AQP4+NMOSD vs DS-NMOSD suggests heterogeneity of diseases within the latter category and provides useful data to improve our understanding of this disease.

Non-demyelinating disorders mimicking and misdiagnosed as NMOSD: a literature review.

BACKGROUND: Differentiating neuromyelitis optica spectrum disorder (NMOSD) from its mimics is crucial to avoid misdiagnosis, especially in the absence of aquaporin-4-IgG. While multiple sclerosis (MS) and myelin oligodendrocyte glycoprotein-IgG associated disease (MOGAD) represent major and well-defined differential diagnoses, non-demyelinating NMOSD mimics remain poorly characterized. METHODS: We conducted a systematic review on PubMed/MEDLINE to identify reports of patients with non-demyelinating disorders that mimicked or were misdiagnosed as NMOSD. Three novel cases seen at the authors' institutions were also included. The characteristics of NMOSD mimics were analyzed and red flags associated with misdiagnosis identified. RESULTS: A total of 68 patients were included; 35 (52%) were female. Median age at symptoms onset was 44 (range, 1-78) years. Fifty-six (82%) patients did not fulfil the 2015 NMOSD diagnostic criteria. The clinical syndromes misinterpreted for NMOSD were myelopathy (41%), myelopathy + optic neuropathy (41%), optic neuropathy (6%), or other (12%). Alternative etiologies included genetic/metabolic disorders, neoplasms, infections, vascular disorders, spondylosis, and other immune-mediated disorders. Common red flags associated with misdiagnosis were lack of cerebrospinal fluid (CSF) pleocytosis (57%), lack of response to immunotherapy (55%), progressive disease course (54%), and lack of magnetic resonance imaging gadolinium enhancement (31%). Aquaporin-4-IgG positivity was detected in five patients by enzyme-linked immunosorbent assay (n = 2), cell-based assay (n = 2: serum, 1; CSF, 1), and non-specified assay (n = 1). CONCLUSIONS: The spectrum of NMOSD mimics is broad. Misdiagnosis frequently results from incorrect application of diagnostic criteria, in patients with multiple identifiable red flags. False aquaporin-4-IgG positivity, generally from nonspecific testing assays, may rarely contribute to misdiagnosis.

Investigating the association between neoplasms and MOG antibody-associated disease.

Introduction: The association of myelin oligodendrocyte glycoprotein (MOG) antibody associated disease (MOGAD) and tumors has seldom been reported. We aim to investigate the occurrence of tumors in a cohort of patients with MOGAD and to describe their clinical features, in addition to previously reported cases. Methods: We retrospectively identified patients with MOGAD (i.e., compatible clinical phenotype and positive MOG antibodies analysed with a live cell-based assay) from 1/1/2015 to 1/1/2023 who had a neoplasm diagnosed within 2 years from MOGAD onset. Furthermore, we performed systematic review of literature to identify previously reported cases. Clinical, paraclinical and oncological findings were collected and reported as median (range) or number (percentage). Results: Two of 150 MOGAD patients (1%) had a concomitant neoplasm in our cohort. Fifteen additional cases were retrieved from literature. Median age was 39 (16-73) years-old, 12 patients were female. ADEM (n = 4;23.5%), encephalomyelitis (n = 3;17.6%), and monolateral optic neuritis (n = 2;11.8%) were the most frequent phenotypes. Median number of treatments was 1 (range 1-4), improvement was reported in 14/17 cases (82.4%). Oncological accompaniments were teratoma (n = 4), CNS (n = 3), melanoma (n = 2), lung (n = 2), hematological (n = 2), ovary (n = 1), breast (n = 1), gastrointestinal (n = 1), and thymic (n = 1) neoplasms. Median time from tumor diagnosis to MOGAD onset was 0 (range - 60 to 20) months. MOG expression in neoplastic tissue was reported in 2/4 patients. Median PNS-CARE score was 3 (range 0-7): 11 patients were classified as "non-PNS," 5 as "possible PNS," and 1 as "probable PNS." Discussion: Our study confirms that MOG is a low-risk antibody for paraneoplastic neurological syndromes and that the clinical presentation and oncological accompaniments are extremely variable. Most of these patients were classified as non-PNS, whereas only a minority was diagnosed with possible/probable PNS, frequently in association with ovarian teratoma. These findings support the notion that MOGAD is not a paraneoplastic disease.

Neurologic sequelae of COVID-19 are determined by immunologic imprinting from previous coronaviruses.

Coronavirus disease 2019 (COVID-19), which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global public health emergency. Although SARS-CoV-2 is primarily a respiratory pathogen, extra-respiratory organs, including the CNS, can also be affected. Neurologic symptoms have been observed not only during acute SARS-CoV-2 infection, but also at distance from respiratory disease, also known as long-COVID or neurological post-acute sequelae of COVID-19 (neuroPASC). The pathogenesis of neuroPASC is not well understood, but hypotheses include SARS-CoV-2-induced immune dysfunctions, hormonal dysregulations and persistence of SARS-CoV-2 reservoirs. In this prospective cohort study, we used a high throughput systems serology approach to dissect the humoral response to SARS-CoV-2 (and other common coronaviruses: 229E, HKU1, NL63 and OC43) in the serum and CSF from 112 infected individuals who developed (n = 18) or did not develop (n = 94) neuroPASC. Unique SARS-CoV-2 humoral profiles were observed in the CSF of neuroPASC compared with serum responses. All antibody isotypes (IgG, IgM, IgA) and subclasses (IgA1-2, IgG1-4) were detected in serum, whereas CSF was characterized by focused IgG1 (and absence of IgM). These data argue in favour of compartmentalized brain-specific responses against SARS-CoV-2 through selective transfer of antibodies from the serum to the CSF across the blood-brain barrier, rather than intrathecal synthesis, where more diversity in antibody classes/subclasses would be expected. Compared to individuals who did not develop post-acute complications following infection, individuals with neuroPASC had similar demographic features (median age 65 versus 66.5 years, respectively, P = 0.55; females 33% versus 44%, P = 0.52) but exhibited attenuated systemic antibody responses against SARS-CoV-2, characterized by decreased capacity to activate antibody-dependent complement deposition (ADCD), NK cell activation (ADNKA) and to bind Fcγ receptors. However, surprisingly, neuroPASC individuals showed significantly expanded antibody responses to other common coronaviruses, including 229E, HKU1, NL63 and OC43. This biased humoral activation across coronaviruses was particularly enriched in neuroPASC individuals with poor outcome, suggesting an 'original antigenic sin' (or immunologic imprinting), where pre-existing immune responses against related viruses shape the response to the current infection, as a key prognostic marker of neuroPASC disease. Overall, these findings point to a pathogenic role for compromised anti-SARS-CoV-2 responses in the CSF, likely resulting in incomplete virus clearance from the brain and persistent neuroinflammation, in the development of post-acute neurologic complications of SARS-CoV-2 infection.

SARS-CoV-2 antibodies in inflammatory neurological conditions: a multicentre retrospective comparative study.

It is well established that neurological and non-neurological autoimmune disorders can be triggered by viral infections. It remains unclear whether SARS-CoV-2 infection induces similar conditions and whether they show a distinctive phenotype. We retrospectively identified patients with acute inflammatory CNS conditions referred to our laboratory for antibody testing during the pandemic (March 1 to August 31, 2020). We screened SARS-COV-2 IgA/IgG in all sera by ELISA and confirmed the positivity with additional assays. Clinical and paraclinical data of SARS-COV-2-IgG seropositive patients were compared to those of seronegative cases matched for clinical phenotype, geographical zone, and timeframe. SARS-CoV-2-IgG positivity was detected in 16/339 (4%) sera, with paired CSF positivity in 3/16. 5 of these patients had atypical demyelinating disorders and 11 autoimmune encephalitis syndromes. 9/16 patients had a previous history of SARS-CoV-2 infection and 6 of them were symptomatic. In comparison with 32 consecutive seronegative controls, SARS-CoV-2-IgG-positive patients were older, frequently presented with encephalopathy, had lower rates of CSF pleocytosis and other neurological autoantibodies, and were less likely to receive immunotherapy. When SARS-CoV-2 seropositive versus seronegative cases with demyelinating disorders were compared no differences were seen. Whereas seropositive encephalitis patients less commonly showed increased CSF cells and protein, our data suggest that an antecedent symptomatic or asymptomatic SARS-CoV-2 infection can be detected in patients with autoimmune neurological conditions. These cases are rare, usually do not have specific neuroglial antibodies.

Autoimmune encephalitis misdiagnosis and mimics.

The diagnosis of autoimmune encephalitis (AE) requires reasonable exclusion of other conditions. The aim of this study is to characterize mimickers and misdiagnoses of AE, thus we performed an independent PubMed search for mimickers of AEs or patients with alternative neurological disorders misdiagnosed as AE. Fifty-eight studies with 66 patients were included. Neoplastic (n = 17), infectious (n = 15), genetic (n = 13), neurodegenerative (n = 8), and other neurological (n = 8) or systemic autoimmune (n = 5) disorders were misdiagnosed as AE. The lack of fulfillment of diagnostic criteria for AE, atypical neuroimaging findings, non-inflammatory CSF findings, non-specific autoantibody specificities and partial response to immunotherapy were major confounding factors.

Microstates in multiple sclerosis: an electrophysiological signature of altered large-scale networks functioning?

Multiple sclerosis has a highly variable course and disabling symptoms even in absence of associated imaging data. This clinical-radiological paradox has motivated functional studies with particular attention to the resting-state networks by functional MRI. The EEG microstates analysis might offer advantages to study the spontaneous fluctuations of brain activity. This analysis investigates configurations of voltage maps that remain stable for 80-120 ms, termed microstates. The aim of our study was to investigate the temporal dynamic of microstates in patients with multiple sclerosis, without reported cognitive difficulties, and their possible correlations with clinical and neuropsychological parameters. We enrolled fifty relapsing-remitting multiple sclerosis patients and 24 healthy subjects, matched for age and sex. Demographic and clinical data were collected. All participants underwent to high-density EEG in resting-state and analyzed 15 min free artefact segments. Microstates analysis consisted in two processes: segmentation, to identify specific templates, and back-fitting, to quantify their temporal dynamic. A neuropsychological assessment was performed by the Brief International Cognitive Assessment for Multiple Sclerosis. Repeated measures two-way ANOVA was run to compare microstates parameters of patients versus controls. To evaluate association between clinical, neuropsychological and microstates data, we performed Pearsons' correlation and stepwise multiple linear regression to estimate possible predictions. The alpha value was set to 0.05. We found six templates computed across all subjects. Significant differences were found in most of the parameters (global explained variance, time coverage, occurrence) for the microstate Class A (P < 0.001), B (P < 0.001), D (P < 0.001), E (P < 0.001) and F (P < 0.001). In particular, an increase of temporal dynamic of Class A, B and E and a decrease of Class D and F were observed. A significant positive association of disease duration with the mean duration of Class A was found. Eight percent of patients with multiple sclerosis were found cognitive impaired, and the multiple linear regression analysis showed a strong prediction of Symbol Digit Modalities Test score by global explained variance of Class A. The EEG microstate analysis in patients with multiple sclerosis, without overt cognitive impairment, showed an increased temporal dynamic of the sensory-related microstates (Class A and B), a reduced presence of the cognitive-related microstates (Class D and F), and a higher activation of a microstate (Class E) associated to the default mode network. These findings might represent an electrophysiological signature of brain reorganization in multiple sclerosis. Moreover, the association between Symbol Digit Modalities Test and Class A may suggest a possible marker of overt cognitive dysfunctions.

More Efficient Complement Activation by Anti-Aquaporin-4 Compared With Anti-Myelin Oligodendrocyte Glycoprotein Antibodies.

BACKGROUND AND OBJECTIVES: The objective was to study complement-mediated cytotoxicity induced by immunoglobulin G (IgG) anti-aquaporin-4 antibodies (AQP4-IgG) and anti-myelin oligodendrocyte glycoprotein antibodies (MOG-IgG) in human serum samples from patients suffering from the rare demyelinating diseases of the CNS neuromyelitis optica spectrum disorder (NMOSD) and MOG-IgG-associated disease (MOGAD). METHODS: A cell-based assay with HEK293A cells expressing different MOG isoforms (MOGα1-3ß1-3) or AQP4-M23 was used. Cells were incubated with human MOG-IgG or AQP4-IgG-positive serum samples together with active or heat-inactivated human complement, and complement-dependent cytotoxicity (CDC) was measured with a lactate dehydrogenase assay. To further quantify antibody-mediated cell damage, formation of the terminal complement complex (TCC) was analyzed by flow cytometry. In addition, immunocytochemistry of the TCC and complement component 3 (C3) was performed. RESULTS: AQP4-IgG-positive serum samples induced higher CDC and TCC levels than MOG-IgG-positive sera. Notably, both showed a correlation between antibody titers and CDC and also between titers and TCC levels. In addition, all 6 MOG isoforms tested (MOGα1-3ß1-3) could induce at least some CDC; however, the strongest MOG-IgG-induced CDC levels were found on MOGα1, MOGα3, and MOGß1. Different MOG-IgG binding patterns regarding recognition of different MOG isoforms were investigated, and it was found that MOG-IgG recognizing all 6 isoforms again induced highest CDC levels on MOGα1 and MOGß1. Furthermore, surface staining of TCC and C3 revealed positive staining on all 6 MOG isoforms tested, as well as on AQP4-M23. DISCUSSION: Both MOG-IgG and AQP4-IgG are able to induce CDC in a titer-dependent manner. However, AQP4-IgG showed markedly higher levels of CDC compared with MOG in vitro on target cells. This further highlights the role of complement in AQP4-IgG-mediated disease and diminishes the importance of complement activation in MOG-IgG-mediated autoimmune disease.

Neurofilament light chain: a promising diagnostic biomarker for functional motor disorders.

OBJECTIVE: Functional motor disorders (FMDs) are disabling neurological conditions characterized by abnormal movements which are inconsistent and incongruent with recognized neurological diseases. Aim of this study is to investigate whether FMDs are related to structural axonal damage. METHODS: Consecutive patients with a definite diagnosis of FMD with no other neurological/psychiatric comorbidities (pure FMDs) and age-matched healthy controls (HCs) were recruited in a tertiary center and demographic/clinical data were collected. Serum neurofilament light chain (NfL) assessment was performed with ultrasensitive paramagnetic bead-based enzyme-linked immunosorbent assay. RESULTS: 34 patients with FMDs and 34 HCs were included. NfL levels were similar (p = 0.135) in FMDs (median 8.3 pg/mL, range 2-33.7) and HCs (median 6.1 pg/mL, range 2.7-15.6). The area under curve (0.606, 95% CI 0.468-0.743) confirmed that NfL concentration was not different in the two groups. NfL values were similar in patients with paroxysmal vs persistent disease course (p = 0.301), and isolated vs combined symptoms (p = 0.537). NfL levels were associated with age (p < 0.0001), but not with disease duration (p = 0.425), number of CNS acting drugs (p = 0.850), or clinical features (p = 0.983). DISCUSSION: Our preliminary data show that NfL levels are similar in patients with FMDs and HCs, indicating the lack of neuroaxonal damage. These results have relevant pathogenic and clinical implications and suggest that serum NfL may be a promising diagnostic biomarker, potentially useful to differentiate functional vs structural neurological disorders.

Cerebellar involvement associated with immune checkpoint inhibitors: A systematic review.

BACKGROUND AND PURPOSE: Immune checkpoint inhibitors (ICIs) targeting programmed death receptor 1 (PD-1), cytotoxic T-lymphocyte-associated-4 (CTLA-4) and programmed cell death ligand 1 can be associated with immune-related adverse events (iRAEs). Amongst neurological iRAEs, cerebellar involvement seems to be rare and currently lacks a proper characterization. The aim of this study was to phenotype cerebellar iRAEs. METHODS: A systematic review was performed according to PRISMA guidelines including reported patients with cerebellar involvement related to ICIs and with available individual data. RESULTS: After screening 2765 records, 32 studies with 46 patients were included. Median age was 63 years (20-82), and most patients were male (63.0%). Isolated cerebellitis was observed in 32.6% of cases, whilst the remaining cases had "cerebellitis plus", mostly associated with encephalitis/encephalopathy. Associated tumors included most frequently lung cancer, melanoma and Merkel cell carcinoma. PD-1 inhibitor was the most administered treatment (n = 29, 64.4%), whilst exposure to CTLA-4 inhibitor was rare (n = 2, 4.5%). Magnetic resonance imaging was abnormal in 43.2% of patients and inflammatory cerebrospinal fluid findings were frequently observed. Autoantibodies were detected in 61.9% of patients and included novel reactivities. Amongst treatment strategies, the most common were steroids (n = 36) and ICI discontinuation (n = 28, 90.3%). Relapses were reported in 10% of patients. Most patients showed improvement/remission (n = 31) but, at last follow-up, 12 had died. Isolated cerebellitis versus cerebellitis-plus differed in terms of outcomes, whilst seropositive versus seronegative patients had distinct tumor associations. DISCUSSION: Cerebellar iRAEs are usually multifocal, have heterogeneous tumor associations, are most associated with PD-1 inhibitor exposure and are related to autoantibodies, including novel reactivities.

A novel cell-based immunofluorescence assay for the detection of autoantibodies to myelin-associated glycoprotein.

Peripheral neuropathy with antibodies to myelin-associated glycoprotein (MAG) is an autoimmune demyelinating disorder of the peripheral nervous system caused by pathogenic IgM recognizing the human natural killer-1 glycoepitope expressed on MAG. This study aimed to analyze the performance of a new indirect immunofluorescence cell-based assay (CBA, EUROIMMUN) for the detection of anti-MAG IgM. Antibody reactivity was determined in sera from 95 patients with clinical and neurophysiological evidence of anti-MAG-associated neuropathy and in control samples from 55 patients with other forms of peripheral neuropathy. Compared to the results of the gold standard method (ELISA, Bühlmann) and using samples at a dilution of 1:100, the CBA had a sensitivity of 98.9% and a specificity of 100% (PPV 100%, NPV 98.2%). In conclusion, the CBA allows the detection of antibodies to MAG using an easy and standardized technique, and it presents a sensitive and specific alternative to the more time-consuming ELISA. Larger studies are needed to address anti-MAG titer monitoring in parallel with clinical activity.

Increased peripheral inflammatory responses in myelin oligodendrocyte glycoprotein associated disease and aquaporin-4 antibody positive neuromyelitis optica spectrum disorder.

Autoantibody-associated demyelinating diseases of the central nervous system such as myelin oligodendrocyte glycoprotein-antibody associated disease (MOGAD) and aquaporin 4-antibody positive neuromyelitis optica spectrum disorders (AQP4+ NMOSD) are rare diseases but can cause severe disability. In both diseases, associated neuroinflammation is accompanied by blood and cerebrospinal fluid cytokine and chemokine signatures, which were shown to be distinct from those observed in patients with multiple sclerosis (MS). In this study, we aimed to confirm and extend these findings by analyzing a larger number of serum cytokines, chemokines and related molecules in patients with MOGAD or AQP4+ NMOSD in comparison to MS, to better understand the pathophysiology and to identify biomarkers potentially useful in clinical practice for diagnostic and treatment purposes. A total of 65 serum cytokines, chemokines and related molecules like growth factors and soluble receptors were measured by Procartaplex multiplex immunoassays in 40 MOGAD, 40 AQP4+ NMOSD and 54 MS patients at baseline. Furthermore, follow-up samples of 25 AQP4+ NMOSD and 40 MOGAD patients were measured after 6-12 months. Selected analytes were validated in a subgroup of samples using other bead-based assays and ELISA. At baseline, 36 analytes in MOGAD and 30 in AQP4+ NMOSD were significantly increased compared to MS. K-means cluster analysis of all significantly altered molecules revealed three distinct groups: Cluster I, including 12 MOGAD, 2 AQP4+ NMOSD and 3 MS patients, had a specific association with 11 IL-6/IL-17A associated cytokines. In this cluster, 9/17 (53%) patients were children. Cluster II with 13 MOGAD, 24 AQP4+ NMOSD and 1 MS patient was associated with 31 upregulated analytes. Cluster III contained 15 MOGAD, 14 AQP4+ NMOSD and 50 MS patients. In cluster II and III the majority were adults (82% and 92%). Most measured analytes remained stable over time. Validation of selected cytokines and chemokines using other analytical methods revealed moderate to high correlation coefficients, but absolute values differed between assays. In conclusion, these results obtained by bead-based multiplex assays highlight a significant association of biomarkers of peripheral inflammation in patients with antibody-associated demyelinating diseases in comparison with MS.

Peripheral neuropathy and MOG-IgG: A clinical and neuropathological retrospective study.

BACKGROUND: Myelin oligodendrocyte glycoprotein antibodies (MOG-Abs) may rarely be associated with peripheral nervous system involvement. We aimed to test MOG-Abs in patients with undetermined peripheral neuropathy (PN). METHODS: Consecutive patients with available sural nerve biopsy and paired serum sample were retrospectively identified (January, 1st 2016-November, 1st 2021) and tested for MOG-Abs with live cell-based assay (CBA). Patients with antibody titre ≥1:160 (secondary H + L antibody) and selective MOG-IgG presence (IgG-Fc predominance) were considered MOG-IgG positive. All positive samples were analysed with immunohistochemistry and CBAs for antibodies against Neurofascin-155 and Contactin-1. Clinical and neuropathological data were collected through clinical reports. RESULTS: Among 163 patients, 5 (3%) resulted positive for predominantly IgG MOG-Abs (median titer 1:320, range 1:160-1:5120), none showed other concomitant antibodies. Median age was 74 years-old (range 55-81), median disease duration was 60 months (range 1-167), 60% of patients were female. Of these, 4/5 cases had clinical features suggestive of acute (n = 1) or chronic (n = 3) inflammatory demyelinating neuropathy, 2/5 fulfilled the criteria of combined central and peripheral demyelination (CCPD) whilst 3/5 had isolated PNS involvement. Neuropathological findings showed mixed axonal-demyelinating features in 2/5, predominant demyelination in 3/5 cases. Other neuropathological hallmarks included paranodal demyelination (n = 3), myelin outfoldings (n = 4), slight inflammatory infiltrates (n = 3), onion bulbs (n = 3), and clusters of regeneration (n = 4). DISCUSSION: MOG-IgG can be detected in patients with isolated PN or CCPD. Clinical and neuropathological features are suggestive for demyelination and slight inflammation. Further studies should include larger cohorts of patients to elucidate the utility of MOG-Abs testing in PN.

Neutropenia complicating anti-CD20 treatment in patients with multiple sclerosis: A retrospective case series and a systematic review of reported cases.

BACKGROUND: Neutropenia is an infrequent complication of treatment with CD20 depleting agents and may require the administration of granulocyte-colony stimulating factors (G-CSF), which have been associated with an increased relapse risk in patients with multiple sclerosis (PwMS). The management of this side effect is still matter of debate. METHODS: Aim of this study is to evaluate the clinical features and the management of neutropenia occurring in anti-CD20 treated PwMS through a single-center case series and a systematic review of the literature, performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: A total of 19 patients were included (3 from our clinical experience, 16 from the systematic review). Median age was 38 years-old (25-69) and nearly 70% were female, most of these patients had already received a median of 3 (0-4) previous treatments. Neutropenia occurred in 11 patients treated with ocrelizumab and 8 with rituximab, after a median of 2 (1-7) infusions and 9.5 (1-42) months from the first infusion. Most of these patients had late-onset neutropenia, that occurred after a median time of 90 days (2-156). About 70% of patients were symptomatic and most were treated with G-CSF or antibiotics. No relapses after G-CSF were reported. In those who did not suspend anti-CD20 (68.8%), neutropenia reoccurred in 18.2% of cases. Finally, switching between rituximab and ocrelizumab seem not to affect the occurrence of neutropenia. CONCLUSION: Our data provides practical evidence regarding the occurrence and the management of neutropenia during treatment with anti-CD20 in PwMS.

Treatment Options in Refractory Autoimmune Encephalitis.

Autoimmune encephalitis represents a potentially treatable immune-mediated condition that is being more frequently recognized. Prompt immunotherapy is a key factor for the management of autoimmune encephalitis. First-line treatments include intravenous steroids, plasma exchange, and intravenous immunoglobulins, which can be combined in most severe cases. Rituximab and cyclophosphamide are administered as second-line agents in unresponsive cases. A minority of patients may still remain refractory, thus representing a major clinical challenge. In these cases, treatment strategies are controversial, and no guidelines exist. Treatments proposed for refractory autoimmune encephalitis include (1) cytokine-based drugs (such as tocilizumab, interleukin-2/basiliximab, anakinra, and tofacitinib); (2) plasma cell-depleting agents (such as bortezomib and daratumumab); and (3) treatments targeting intrathecal immune cells or their trafficking through the blood-brain barrier (such as intrathecal methotrexate and natalizumab). The efficacy evidence of these drugs is mostly based on case reports or small case series, with few reported controlled studies or systematic reviews. The aim of the present review is to summarize the current evidence and related methodological issues in the use of these drugs for the treatment of refractory autoimmune encephalitis.