Characterization of the human myelin oligodendrocyte glycoprotein antibody response in demyelination

Acute disseminated encephalomyelitis in children and adults: A focused review emphasizing new developments

Acute disseminated encephalomyelitis (ADEM) was originally described in the medical literature more than 200 years ago. However, consensus clinical diagnostic criteria are less than 15 years old. Accurate diagnostic testing for myelin oligodendrocyte glycoprotein (MOG) autoantibodies has only become clinically available in the last 3-5 years and has facilitated a rapidly evolving understanding of patients with recurrent demyelination following ADEM. The field is working to optimize treatment for these patients with hopes of prospective treatment studies in the not too distant future. New imaging data suggest that even monophasic demyelination may have long-term impacts that were previously unrecognized. Recent developments in the literature are described in order to guide practice for providers who treat both adults and children with monophasic and recurrent forms of ADEM with and without MOG antibodies.

Overlapping syndrome of MOG-IgG-associated disease and autoimmune GFAP astrocytopathy

Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) have been considered to be closely relevant to an inflammatory demyelinating disease of the central nervous system (CNS). Glial fibrillary acidic protein (GFAP) immunoglobulin G (IgG) has been identified as a biomarker for a novel autoimmune astrocytopathy. However, coexistence of MOG-IgG and GFAP-IgG is extremely unusual and only one patient has been described with simultaneous presence of MOG-IgG in serum and GFAP-IgG in cerebrospinal fluid (CSF). Herein, we reported the first case of overlapping syndrome of MOG-IgG-associated disease (MOG-AD) and autoimmune GFAP astrocytopathy in whom MOG-IgG and GFAP-IgG were detected both in serum and CSF. A 20-year-old male patient was referred to our department with the presentation of decreased vision, diplopia and weakness of right limb with unknown reasons. Magnetic resonance imaging (MRI) revealed multiple intracranial lesions presenting hypointensity on T1-weighted images, hyperintensity on T2-weighted and FLAIR images and patchy contrast enhancement. MOG-IgG and GFAP-IgG were detected both in serum and CSF, and the titers of both antibodies fluctuated with the severity of disease. Treatment strategy employing intravenous methylprednisolone pulse therapy followed by oral prednisone with slow tapering resulted in an improvement of his symptoms and a sustained remission. Coexistence of MOG-IgG and GFAP-IgG with distinct underlying pathogeneses necessitates the recommendations to screen all recognized pathogenic antibodies against CNS antigens when an autoimmune disease is suspected, since it shows great significance for definite diagnosis of disease and treatment strategy options.

International multicenter examination of MOG antibody assays

OBJECTIVE

To compare the reproducibility of 11 antibody assays for immunoglobulin (Ig) G and IgM myelin oligodendrocyte glycoprotein antibodies (MOG-IgG and MOG-IgM) from 5 international centers.

METHODS

The following samples were analyzed: MOG-IgG clearly positive sera (n = 39), MOG-IgG low positive sera (n = 39), borderline negative sera (n = 13), clearly negative sera (n = 40), and healthy blood donors (n = 30). As technical controls, 18 replicates (9 MOG-IgG positive and 9 negative) were included. All samples and controls were recoded, aliquoted, and distributed to the 5 testing centers, which performed the following antibody assays: 5 live and 1 fixed immunofluorescence cell-based assays (CBA-IF, 5 MOG-IgG, and 1 MOG-IgM), 3 live flow cytometry cell-based assays (CBA-FACS, all MOG-IgG), and 2 ELISAs (both MOG-IgG).

RESULTS

We found excellent agreement (96%) between the live CBAs for MOG-IgG for samples previously identified as clearly positive or negative from 4 different national testing centers. The agreement was lower with fixed CBA-IF (90%), and the ELISA showed no concordance with CBAs for detection of human MOG-IgG. All CBAs showed excellent interassay reproducibility. The agreement of MOG-IgG CBAs for borderline negative (77%) and particularly low positive (33%) samples was less good. Finally, most samples from healthy blood donors (97%) were negative for MOG-IgG in all CBAs.

CONCLUSIONS

Live MOG-IgG CBAs showed excellent agreement for high positive and negative samples at 3 international testing centers. Low positive samples were more frequently discordant than in a similar comparison of aquaporin-4 antibody assays. Further research is needed to improve international standardization for clinical care.

Binding patterns and functional properties of human antibodies to AQP4 and MOG on murine optic nerve and retina

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune-inflammatory CNS disease affecting spinal cord and optic nerves, mediated by autoantibodies against aquaporin-4 (AQP4) and myelin-oligodendrocyte-glycoprotein (MOG). Effects of those immunoglobulins (Ig) on retina and optic nerve are incompletely understood. We investigated AQP4-IgG and MOG-IgG sera on retina and optic nerve ex vivo and in 2D2 mice, which harbor a transgenic MOG-specific T-cell receptor. Some sera reacted with murine retina and optic nerve showing distinct binding patterns, suggesting different epitopes being targeted in both subgroups. Transfer of total IgG from a MOG-IgG positive patient to 2D2 mice did neither enhance disability nor induce functional or histological alterations in the retina.

MOG encephalomyelitis: distinct clinical, MRI and CSF features in patients with longitudinal extensive transverse myelitis as first clinical presentation

Background

Based on clinical, immunological and histopathological evidence, MOG-IgG-associated encephalomyelitis (MOG-EM) has emerged as a distinct disease entity different from multiple sclerosis (MS) and aquaporin-4-antibody-positive neuromyelitis optica spectrum disorder (NMOSD). MOG-EM is associated with a broader clinical phenotype including optic neuritis, myelitis, brainstem lesions and acute disseminated encephalomyelitis with a substantial clinical and radiological overlap to other demyelinating CNS disorders.

Objective

To evaluate common clinical, MRI and CSF findings, as well as therapy responses in patients with longitudinal extensive transverse myelitis (LETM) as initial clinical presentation of MOG-EM.

Methods

After excluding patients with a known diagnosis of MS, we identified 153 patients with myelitis of which 7 fulfilled the inclusion criteria and were investigated for MRI, CSF and clinical parameters.

Results

Patients with LETM as first clinical presentation of MOG-EM display similar characteristics, namely a lack of gadolinium-enhancement in spinal cord MRI, marked pleocytosis, negative oligoclonal bands, a previous history of infections/vaccinations and response to antibody-depleting treatments for acute attacks and long-term treatment.

Conclusions

We identify common pathological findings in patients with LETM as first clinical presentation of MOG-EM which distinguishes it from other forms of LETM and should lead to testing for MOG-IgG in these cases.

Effects of the Positive Threshold and Data Analysis on Human MOG Antibody Detection by Live Flow Cytometry

Human autoantibodies targeting myelin oligodendrocyte glycoprotein (MOG Ab) have become a useful clinical biomarker for the diagnosis of a spectrum of inflammatory demyelinating disorders. Live cell-based assays that detect MOG Ab against conformational MOG are currently the gold standard. Flow cytometry, in which serum binding to MOG-expressing cells and control cells are quantitively evaluated, is a widely used observer-independent, precise, and reliable detection method. However, there is currently no consensus on data analysis; for example, seropositive thresholds have been reported using varying standard deviations above a control cohort. Herein, we used a large cohort of 482 sera including samples from patients with monophasic or relapsing demyelination phenotypes consistent with MOG antibody-associated demyelination and other neurological diseases, as well as healthy controls, and applied a series of published analyses involving a background subtraction (delta) or a division (ratio). Loss of seropositivity and reduced detection sensitivity were observed when MOG ratio analyses or when 10 standard deviation (SD) or an arbitrary number was used to establish the threshold. Background binding and MOG ratio value were negatively correlated, in which patients seronegative by MOG ratio had high non-specific binding, a characteristic of serum that must be acknowledged. Most MOG Ab serostatuses were similar across analyses when optimal thresholds obtained by ROC analyses were used, demonstrating the robust nature and high discriminatory power of flow cytometry cell-based assays. With increased demand to identify MOG Ab-positive patients, a consensus on analysis is vital to improve patient diagnosis and for cross-study comparisons to ultimately define MOG Ab-associated disorders.

Proposing BCG Vaccination for Mycobacterium avium ss. paratuberculosis (MAP) Associated Autoimmune Diseases

Bacille Calmette-Guerin (BCG) vaccination is widely practiced around the world to protect against the mycobacterial infection tuberculosis. BCG is also effective against the pathogenic mycobacteria that cause leprosy and Buruli's ulcer. BCG is part of the standard of care for bladder cancer where, when given as an intravesicular irrigant, BCG acts as an immunomodulating agent and lessens the risk of recurrence. Mycobacterium avium ss. paratuberculosis (MAP) causes a fatal enteritis of ruminant animals and is the putative cause of Crohn's disease of humans. MAP has been associated with an increasingly long list of inflammatory/autoimmune diseases: Crohn's, sarcoidosis, Blau syndrome, Hashimoto's thyroiditis, autoimmune diabetes (T1D), multiple sclerosis (MS), rheumatoid arthritis, lupus and Parkinson's disease. Epidemiologic evidence points to BCG providing a "heterologous" protective effect on assorted autoimmune diseases; studies using BCG vaccination for T1D and MS have shown benefit in these diseases. This article proposes that the positive response to BCG in T1D and MS is due to a mitigating action of BCG upon MAP. Other autoimmune diseases, having a concomitant genetic risk for mycobacterial infection as well as cross-reacting antibodies against mycobacterial heat shock protein 65 (HSP65), could reasonably be considered to respond to BCG vaccination. The rare autoimmune disease, relapsing polychondritis, is one such disease and is offered as an example. Recent studies suggesting a protective role for BCG in Alzheimer's disease are also explored. BCG-induced energy shift from oxidative phosphorylation to aerobic glycolysis provides the immunomodulating boost to the immune response and also mitigates mycobacterial infection-this cellular mechanism unifies the impact of BCG on the disparate diseases of this article.

PRES-like presentation in MOG antibody-related demyelination (MARD)

A 33-year-old male presented with a progressive four-week history of frontal headache and left visual field impairment. MRI brain confirmed bilateral, asymmetric, occipital vasogenic oedema, suggestive of posterior reversible encephalopathy syndrome (PRES). Serum testing for MOG antibodies was positive, confirming a diagnosis of MOG antibody-related demyelination (MARD). A similar PRES-like pattern of white matter inflammation has been reported previously in neuromyelitis optica spectrum disorder but has not previously been reported in MARD.

Autoantibody Diagnostics in Neuroimmunology: Experience From the 2018 Italian Neuroimmunology Association External Quality Assessment Program

Background: Neuroimmunology has impressively expanded in the past decade. Novel assays, especially cell-based assays (CBAs) can detect conformational antibodies (Abs) recognizing antigens in their native conformation. Generally, the availability of in-house and of commercial tests has improved the diagnostics, but introduced demanding laboratory tasks. Hence, standardization and quality controls represent a key step to promote accuracy. We report on the results of the 2018 external quality assessment program (EQAP) organized by the Italian Neuroimmunology Association.

Methods: EQAP regarded 10 schemes, including oligoclonal bands (OCBs), intracellular-neuronal (ICN)-Abs, neuronal-surface (NS)-Abs, aquaporin-4 (AQP4)-Abs, myelin oligodendrocyte glycoprotein (MOG)-Abs, myelin-associated glycoprotein (MAG)-Abs, ganglioside-Abs, acetylcholine-receptor (AChR)-Abs, and muscle-specific-kinase (MuSK)-Abs, and 34 laboratories. Assays were classified as tissue-based assays (TBAs), solid-phase assays (SPAs), liquid-phase assays (LPAs), and CBAs. Thirty-three samples were provided.

Results: Three-quarter of the tests were commercial. Median accuracy for the laboratories was 75% (range 50–100). In 8/10 schemes, at least one sample provided discrepant results. Inter-laboratory “substantial agreement” was found in 6/10 schemes (AChR, MuSK, MAG, AQP4, MOG, and NS-Abs), whereas the worst agreements regarded OCBs and ganglioside-Abs. Both commercial and in-house assays performed better in experienced laboratories.

Conclusions: Assays could be divided in (a) robust commercial tests with substantial inter-laboratory agreement (MAG-Abs; AChR- and MuSK-Abs); commercial/“in-house” tests with (b) partial inter-laboratory agreement (AQP4-Abs, MOG-Abs, NS-Abs, ICN-Abs), and (c) with large inter-laboratory disagreement (OCBs, ganglioside-Abs). This real-life snapshot of the neuroimmunology test performances highlights shortcomings attributable to technician-dependent performances, assay structural limitations, and errors in test interpretations.

Refining cell-based assay to detect MOG-IgG in patients with central nervous system inflammatory diseases

BACKGROUND

Given that the spectrum of myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG) associated disease is yet to be fully defined, development of sensitive and highly specific assays to identify MOG-IgG is crucial to precisely define the clinical phenotypes, disease courses and prognosis to describe the full spectrum of MOG-IgG associated diseases. Here, we aim to validate a new in-house live cell-based assay (CBA) for screening MOG-IgG in patients with central nervous system inflammatory diseases.

METHODS

We generated a full length MOG transfected HEK293 stable cell line using pIRES2-eGFP vector. Sera from 355 patients with central nervous system inflammatory diseases and 25 healthy individuals were evaluated for MOG-IgG seropositivity using in-house cell-based immunofluorescence assay (CBA-IF). The specificity of IgG (H + L) and IgG1-Fc secondary antibodies as well as IgM binding were determined by cell-based flow cytometry (CBA-FACS). The optimal cut-offs for determining seropositivity in CBA-FACS were calculated and the concordance of CBA-IF score and CBA-FACS was studied. The results of our CBA-IF were compared with the Oxford CBA-IF.

RESULTS

11.5% (41/355) of patients were seropositive for MOG-IgG and had clinical phenotypes that were within the known clinical spectrum of MOG-IgG associated diseases. No typical multiple sclerosis patients, aquaporin-4-IgG positive neuromyelitis optica spectrum disorder or healthy individuals were MOG-IgG seropositive. Using CBA-FACS, the anti-human IgG (H + L) was found to be comparable to IgG1-Fc antibody. No IgM binding was observed in all the samples tested. CBA-IF score and CBA-FACS yielded high correlation. The concordance of the NCC CBA-IF with the Oxford CBA-IF was 98%.

CONCLUSION

We have developed MOG-IgG CBAs that have different characteristics and benefits but with high specificity and concordance. The complementary use of two methods and follow-up study with larger cohort will increase the clinical usefulness of MOG-IgG CBAs.

Deciphering anti-MOG IgG antibodies: Clinical and radiological spectrum, and comparison of antibody detection assays

IgG antibodies to myelin oligodendrocyte glycoprotein (MOG) detected by cell based assays (CBA) have been identified in a constantly expanding spectrum of CNS demyelinating disorders. However, a universally accepted CBA has not been adopted yet. We aimed to analyze the clinical and radiological features of patients with anti-MOG IgG1-antibodies detected with a live-cell CBA and to compare the three most popular MOG-CBAs. We screened sera from 1300 Greek patients (including 426 patients referred by our 8 clinics) suspected for anti-MOG syndrome, and 120 controls with the live-cell MOG-CBA for IgG1-antibodies. 41 patients, versus 0 controls were seropositive. Clinical, serological and radiological data were available and analyzed for the 21 seropositive patients out of the 426 patients of our clinics. Their phenotypes were: 8 optic neuritis, 3 myelitis, 3 neuromyelitis optica, 2 encephalomyelitis, 2 autoimmune encephalitis and 3 atypical MS. We then retested all sera of our 426 patients with the other two most popular MOG-CBAs for total IgG (a live-cell and a commercial fixed-cell CBAs). Seven IgG1-seropositive patients were seronegative for one or both IgG-CBAs. Yet, all 21 patients had clinical and radiological findings previously described in MOG-antibody associated demyelination disease supporting the high specificity of the IgG1-CBA. In addition, all IgG1-CBA-negative sera were also negative by the IgG-CBAs. Also, all controls were negative by all three assays, except one serum found positive by the live IgG-CBA. Overall, our findings support the wide spectrum of anti-MOG associated demyelinating disorders and the superiority of the MOG-IgG1 CBA over other MOG-CBAs.

Co-occurrence of Anti-N-Methyl-D-Aspartate Receptor Encephalitis and Anti-myelin Oligodendrocyte Glycoprotein Inflammatory Demyelinating Diseases: A Clinical Phenomenon to Be Taken Seriously

Background: Anti-N-methyl-D-aspartate receptor (NMDAR) immunoglobulin G antibodies which exist on myelin sheaths, composed of oligodendrocytes, especially target GluN1 subunits and are highly characteristic of anti-NMDAR encephalitis which is a newly recognized autoimmune encephalitis (AE) characterized by psychiatric symptoms, behavioral abnormalities, seizures, cognitive impairment and other clinical symptoms. Myelin oligodendrocyte glycoprotein (MOG) is a type of protein which is expressed on the surface of oligodendrocytes and myelin in the central nervous system. Anti-MOG antibodies cause demyelination. In some rare reported cases, these two types of antibodies have been found to co-exist, but the underlying mechanisms remain unknown.

Case presentation: Here we report cases of 4 inpatients (median age 31.5 years, age range 27–43 years) from The Second Xiangya Hospital of Central South University between March 2018 and April 2019. Two of the cases were first diagnosed as anti-NMDAR encephalitis and had developed visual impairments in the course of the dosage reduction during corticosteroid therapy. They were found at the time, to have anti-MOG antibody-positive CSF and/or serum. Another patient was diagnosed with anti-MOG inflammatory demyelinating diseases (IDDs) when he tested double positive for both anti-NMDAR and anti-MOG antibodies early in the course of his illness. Over the course of the dosage reduction during corticosteroid therapy, his symptoms deteriorated; however, anti-MOG antibody levels elevated while anti-NDMAR antibody levels remained low. The other patient had initially developed psychiatric symptoms and limb weakness. She was also double positive for anti-NMDAR and anti-MOG antibodies early in the course of her illness. However, over the course of the dosage reduction during corticosteroid therapy, her symptoms worsened and levels of both antibodies elevated.

Conclusion: Anti-NMDAR and anti-MOG antibodies may coexist in rare cases. In addition, anti-NMDAR encephalitis and anti-MOG inflammatory demyelinating diseases may occur either simultaneously or in succession. Thus, when a patient is diagnosed with either of these two diseases, but exhibits symptoms of the other disease, the possibility of co-occurrence with both these diseases should be considered and the appropriate antibodies should be accurately detected to enable prompt selection of appropriate treatments by the physicians.