Relation of HLA-DRB1 to IgG4 autoantibody and cytokine production in muscle-specific tyrosine kinase myasthenia gravis (MuSK-MG)

A systematic review and meta-analysis of HLA class II associations in patients with IgG4 autoimmunity

Autoimmune diseases caused by pathogenic IgG4 subclass autoantibodies (IgG4-AID) include diseases like MuSK myasthenia gravis, pemphigus vulgaris or thrombotic thrombocytopenic purpura. Their etiology is still unknown. Polymorphisms in the human leukocyte antigen (HLA) gene locus, particularly in HLA-DRB1, are known genetic susceptibility factors for autoimmune diseases. We hypothesized a similar role for HLA polymorphisms in IgG4-AID and conducted a systematic review and meta-analysis with case-control studies on IgG4-AID based on MOOSE/ HuGENet guidelines. Genotype (G) and allele (A) frequencies of HLA-DQB1*05 (G: OR 3.8; 95% CI 2.44-5.9; p < 0.00001; A: OR 2.54; 95% CI 1.82-3.55; p < 0.00001) and HLA-DRB1*14 (G: OR 4.31; 95% CI 2.82-6.59; p < 0.00001; A: OR 4.78; 95% CI 3.52-6.49; p < 0.00001) and the HLA-DRB1*14-DQB1*05 haplotype (OR 6.3; 95% CI 3.28-12.09; p < 0.00001/OR 4.98; 95% CI 3.8-6.53; p < 0.00001) were increased while HLA-DRB1*13 (G: OR 0.48; 95% CI 0.34-0.68; p < 0.0001; A: OR 0.46; 95% CI 0.34-0.62; p < 0.00001) was decreased in IgG4-AID patients. In conclusion, the HLA-DQB1*05, HLA-DRB1*14 alleles and the HLA-DQB1*05-DRB1*14 haplotype could be genetic risk factors that predispose for the production of pathogenic IgG4 autoantibodies and the HLA-DRB1*13 allele may protect from IgG4 autoimmunity.

Anti-Neuronal IgG4 Autoimmune Diseases and IgG4-Related Diseases May Not Be Part of the Same Spectrum: A Comparative Study

Background

IgG4 is associated with two emerging groups of rare diseases: 1) IgG4 autoimmune diseases (IgG4-AID) and 2) IgG4-related diseases (IgG4-RLD). Anti-neuronal IgG4-AID include MuSK myasthenia gravis, LGI1- and Caspr2-encephalitis and autoimmune nodo-/paranodopathies (CNTN1/Caspr1 or NF155 antibodies). IgG4-RLD is a multiorgan disease hallmarked by tissue-destructive fibrotic lesions with lymphocyte and IgG4 plasma cell infiltrates and increased serum IgG4 concentrations. It is unclear whether IgG4-AID and IgG4-RLD share relevant clinical and immunopathological features.

Methods

We collected and analyzed clinical, serological, and histopathological data in 50 patients with anti-neuronal IgG4-AID and 19 patients with IgG4-RLD.

Results

A significantly higher proportion of IgG4-RLD patients had serum IgG4 elevation when compared to IgG4-AID patients (52.63% vs. 16%, p = .004). Moreover, those IgG4-AID patients with elevated IgG4 did not meet the diagnostic criteria of IgG4-RLD, and their autoantibody titers did not correlate with their serum IgG4 concentrations. In addition, patients with IgG4-RLD were negative for anti-neuronal/neuromuscular autoantibodies and among these patients, men showed a significantly higher propensity for IgG4 elevation, when compared to women (p = .005). Last, a kidney biopsy from a patient with autoimmune paranodopathy due to CNTN1/Caspr1-complex IgG4 autoantibodies and concomitant nephrotic syndrome did not show fibrosis or IgG4+ plasma cells, which are diagnostic hallmarks of IgG4-RLD.

Conclusion

Our observations suggest that anti-neuronal IgG4-AID and IgG4-RLD are most likely distinct disease entities.

Clinical and Prognostic Value of Immunogenetic Characteristics in Anti-LGI1 Encephalitis

Objective

Antibodies against leucine-rich glioma-inactivated 1 (LGI1-Abs) characterize a limbic encephalitis (LE) strongly associated with HLA-DRB1*07:01, although some patients lack LGI1-Abs in CSF or do not carry this allele. Whether they represent a different subtype of disease or have different prognoses is unclear.

Methods

Retrospective analysis of clinical features, IgG isotypes, and outcome according to LGI1-Ab CSF positivity and DRB1*07:01 in a cohort of anti-LGI1 LE patients.

Results

Patients with LGI1-Abs detected in both CSF and serum (105/134, 78%) were compared with those who were CSF negative (29/134, 22%). Both groups had similar clinical features and serum levels, but CSF-positive patients had shorter diagnostic delay, more frequently hyponatremia, inflammatory CSF, and abnormal MRI (p < 0.05). Human leukocyte antigen (HLA) genotyping was performed in 72/134 (54%) patients and 63/72 (88%) carried DRB1*07:01. Noncarriers (9/72, 12%) were younger, more commonly women, and had less frequently psychiatric and frontal symptoms (p < 0.05). No difference in IgG isotypes according to CSF positivity or HLA was found (p > 0.05). HLA and IgG isotypes were not associated with poor outcome (mRS >2 at last follow-up) in univariate analyses; CSF positivity was only identified as a poor outcome predictor in the multivariate analysis including the complete follow-up, whereas age and female sex also remained when just the first year was considered.

Conclusions

LE without CSF LGI1-Abs is clinically indistinguishable and likely reflects just a lesser LGI1-Ab production. HLA association is sex and age biased and presents clinical particularities, suggesting subtle differences in the immune response. Long-term outcome depends mostly on demographic characteristics and the intensity of the intrathecal synthesis.

Common Denominators in the Immunobiology of IgG4 Autoimmune Diseases: What Do Glomerulonephritis, Pemphigus Vulgaris, Myasthenia Gravis, Thrombotic Thrombocytopenic Purpura and Autoimmune Encephalitis Have in Common?

IgG4 autoimmune diseases (IgG4-AID) are an emerging group of autoimmune diseases that are caused by pathogenic autoantibodies of the IgG4 subclass. It has only recently been appreciated, that members of this group share relevant immunobiological and therapeutic aspects even though different antigens, tissues and organs are affected: glomerulonephritis (kidney), pemphigus vulgaris (skin), thrombotic thrombocytopenic purpura (hematologic system) muscle-specific kinase (MuSK) in myasthenia gravis (peripheral nervous system) and autoimmune encephalitis (central nervous system) to give some examples. In all these diseases, patients’ IgG4 subclass autoantibodies block protein-protein interactions instead of causing complement mediated tissue injury, patients respond favorably to rituximab and share a genetic predisposition: at least five HLA class II genes have been reported in individual studies to be associated with several different IgG4-AID. This suggests a role for the HLA class II region and specifically the DRβ1 chain for aberrant priming of autoreactive T-cells toward a chronic immune response skewed toward the production of IgG4 subclass autoantibodies. The aim of this review is to provide an update on findings arguing for a common pathogenic mechanism in IgG4-AID in general and to provide hypotheses about the role of distinct HLA haplotypes, T-cells and cytokines in IgG4-AID.

Myasthenia gravis, atypical polyneuropathy and multiple autoimmune phenomena in the same patient, with HLA-immunogenetic profile expectable for Greek chronic inflammatory demyelinating polyneuropathy: a case report

PURPOSE

The comorbidity of myasthenia gravis (MG), with other autoimmune disorders like systemic lupus erythematosus (SLE), is relatively frequent but the co-occurrence with chronic inflammatory demyelinating polyneuropathy (CIDP) along with various autoimmune manifestations in the absence of thymoma is of extreme rarity. Our aim is to report a case of a woman who presented the concomitant appearance of MG, axonal sensory-motor polyneuropathy and hepatitis that may indicate an underlying pathogenetic link among the different autoimmune disorders.

MATERIALS AND METHODS/RESULTS

We present a case of a 54-year-old woman, with a generalized MG and a chronic sensory-motor polyneuropathy, hypothyroidism, anaemia, hepatitis, livedo reticularis and facial flush, of assumed autoimmune background, like SLE, although with persistent negative ANA antibodies, from the beginning and through the whole following years. The Human Leukocyte Antigen (HLA)-DRB1 genotyping showed a profile of alleles (DRB1*11:01/11:04) compatible with CIDP of mainly female gender in Greece and frequencies close to those of Sjogren's syndrome and scleroderma's in the Greek population. The diagnostic problems, the atypical clinical, electrophysiological and immunological features are discussed, along with the rarity of the case, with this exceptional combination of autoimmune manifestations, which could be truly associated under the clinical umbrella of a systemic disease, like SLE. However, our patient did not ever fulfil the SLE criteria.

CONCLUSIONS

To raise awareness among clinicians about the exceptional combination of autoimmune manifestations driven by a specific HLA background.

Gender issues of antibody-mediated diseases in neurology: (NMOSD/autoimmune encephalitis/MG)

Neuromyelitis optica spectrum disorder (NMOSD), autoimmune encephalitis (AE), myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) are antibody-mediated neurological diseases. They have mostly female predominance, affecting many women during childbearing age. Interactions between the underlying disease (or necessary treatment) and pregnancy can occur in every of these illnesses. Herein, we present the characteristics of NMOSD, AE, MG and LEMS in general, and review published data regarding the influence of the different diseases on fertility, pregnancy, puerperium, treatment strategy during pregnancy and post-partum period, and menopause but also male factors. We summarise key elements that should be borne in mind when confronted with such cases.