Cellular changes in eculizumab early responders with generalized myasthenia gravis.

Eculizumab (ECU), a C5 complement inhibitor, is approved to treat acetylcholine receptor autoantibody positive generalized myasthenia gravis (AChR MG). The clinical effect of ECU relies on inhibition of the terminal complement complex; however, the effect of ECU on lymphocytes is largely unknown. We evaluated innate and adaptive immunity among AChR MG patients (N = 3) before ECU and ≥3 months later while on stable therapy, and found reduced activation markers in memory CD4+ T cell subsets, increased regulatory T cell populations, and reduced frequencies of CXCR5+HLA-DR+CCR7+ Tfh subsets and CD11b+ migratory memory B cells. We observed increases within CD8+ T cell subsets that were terminally differentiated and senescent. Our data suggest complement inhibition with ECU modulates the adaptive immunity in patients with MG, consistent with preclinical data showing changes in complement-mediated signaling by T- and antigen-presenting cells. These findings extend our understanding of ECU's mechanism of action when treating patients with MG.

Reduced plasmablast frequency is associated with seronegative myasthenia gravis.

BACKGROUND: The immunopathology of autoimmune seronegative myasthenia gravis (SN MG) is poorly understood. Our objective was to determine immune profiles associated with a diagnosis of SN MG. METHODS: We performed high-dimensional flow cytometry on blood samples from SN MG patients (N = 68), healthy controls (N = 46), and acetylcholine receptor antibody (AChR+) MG patients (N = 27). We compared 12 immune cell subsets in SN MG to controls using logistic modeling via a discovery-replication design. An exploratory analysis fit a multinomial model comparing AChR+ MG and controls to SN MG. RESULTS: An increase in CD19+ CD20- CD38hi plasmablast frequencies was associated with lower odds of being a SN MG case in both the discovery and replication analyses (discovery P-value = .0003, replication P-value = .0021). Interleukin (IL) -21 producing helper T cell frequencies were associated with a diagnosis of AChR+ MG (P = .004). CONCLUSIONS: Reduced plasmablast frequencies are strongly associated with a SN MG diagnosis and may be a useful diagnostic biomarker in the future.

Epidemiological evidence for a hereditary contribution to myasthenia gravis: a retrospective cohort study of patients from North America.

OBJECTIVES: To approximate the rate of familial myasthenia gravis and the coexistence of other autoimmune disorders in the patients and their families. DESIGN: Retrospective cohort study. SETTING: Clinics across North America. PARTICIPANTS: The study included 1032 patients diagnosed with acetylcholine receptor antibody (AChR)-positive myasthenia gravis. METHODS: Phenotype information of 1032 patients diagnosed with AChR-positive myasthenia gravis was obtained from clinics at 14 centres across North America between January 2010 and January 2011. A critical review of the epidemiological literature on the familial rate of myasthenia gravis was also performed. RESULTS: Among 1032 patients, 58 (5.6%) reported a family history of myasthenia gravis. A history of autoimmune diseases was present in 26.6% of patients and in 28.4% of their family members. DISCUSSION: The familial rate of myasthenia gravis was higher than would be expected for a sporadic disease. Furthermore, a high proportion of patients had a personal or family history of autoimmune disease. Taken together, these findings suggest a genetic contribution to the pathogenesis of myasthenia gravis.

Imbalance in T follicular helper cells producing IL-17 promotes pro-inflammatory responses in MuSK antibody positive myasthenia gravis.

A detailed understanding of the role of Tfh cells in MuSK-antibody positive myasthenia gravis (MuSK-MG) is lacking. We characterized phenotype and function of Tfh cells in MuSK-MG patients and controls. We found similar overall Tfh and follicular regulatory (Tfr) T cell frequencies in MuSK-MG and healthy controls, but MuSK-MG patients exhibited higher frequencies of Tfh17 cells and a higher ratio of Tfh:Tfr cells. These results suggest imbalanced Tfh cell regulation, further supported by increased frequencies of CD4 T cells co-producing IL-21/IL-17 and IL-17/IFN-γ, and increased Tfh-supported IgG production. These results support a role for Tfh cell dysregulation in MuSK-MG immunopathology.

Clinical Effects of the Self-administered Subcutaneous Complement Inhibitor Zilucoplan in Patients With Moderate to Severe Generalized Myasthenia Gravis: Results of a Phase 2 Randomized, Double-Blind, Placebo-Controlled, Multicenter Clinical Trial.

Importance: Many patients with generalized myasthenia gravis (gMG) have substantial clinical disability, persistent disease burden, and adverse effects attributable to chronic immunosuppression. Therefore, there is a significant need for targeted, well-tolerated therapies with the potential to improve disease control and enhance quality of life. Objective: To evaluate the clinical effects of zilucoplan, a subcutaneously (SC) self-administered macrocyclic peptide inhibitor of complement component 5, in a broad population of patients with moderate to severe gMG. Design, Setting, and Participants: This randomized, double-blind, placebo-controlled phase 2 clinical trial at 25 study sites across North America recruited participants between December 2017 and August 2018. Fifty-seven patients were screened, of whom 12 did not meet inclusion criteria and 1 was lost to follow-up after randomization but before receiving study drug, resulting in a total of 44 acetylcholine receptor autoantibody (AChR-Ab)-positive patients with gMG with baseline Quantitative Myasthenia Gravis (QMG) scores of at least 12, regardless of treatment history. Interventions: Patients were randomized 1:1:1 to a daily SC self-injection of placebo, 0.1-mg/kg zilucoplan, or 0.3-mg/kg zilucoplan for 12 weeks. Main Outcomes and Measures: The primary and key secondary end points were the change from baseline to week 12 in QMG and MG Activities of Daily Living scores, respectively. Significance testing was prespecified at a 1-sided α of .10. Safety and tolerability were also assessed. Results: The study of 44 patients was well balanced across the 3 treatment arms with respect to key demographic and disease-specific variables. The mean age of patients across all 3 treatment groups ranged from 45.5 to 54.6 years and most patients were white (average proportions across 3 treatment groups: 78.6%-86.7%). Clinically meaningful and statistically significant improvements in primary and key secondary efficacy end points were observed. Zilucoplan at a dose of 0.3 mg/kg SC daily resulted in a mean reduction from baseline of 6.0 points in the QMG score (placebo-corrected change, -2.8; P = .05) and 3.4 points in the MG Activities of Daily Living score (placebo-corrected change, -2.3; P = .04). Clinically meaningful and statistically significant improvements were also observed in other secondary end points, the MG Composite and MG Quality-of-Life scores. Outcomes for the 0.1-mg/kg SC daily dose were also statistically significant but slower in onset and less pronounced than with the 0.3-mg/kg dose. Rescue therapy (intravenous immunoglobulin or plasma exchange) was required in 3 of 15, 1 of 15, and 0 of 14 participants in the placebo, 0.1-mg/kg zilucoplan, and 0.3-mg/kg zilucoplan arms, respectively. Zilucoplan was observed to have a favorable safety and tolerability profile. Conclusions and Relevance: Zilucoplan yielded rapid, meaningful, and sustained improvements over 12 weeks in a broad population of patients with moderate to severe AChR-Ab-positive gMG. Near-complete complement inhibition appeared superior to submaximal inhibition. The observed safety and tolerability profile of zilucoplan was favorable. Trial Registration: ClinicalTrials.gov Identifier: NCT03315130.

Clinical outcome measures following plasma exchange for MG exacerbation.

Our objective is to report longitudinal results of the MG-ADL, MG-Composite, MG-MMT, and MG-QoL15 in an open-label trial of therapeutic plasma exchange in myasthenia gravis. Ten MG patients experiencing exacerbation had assessments prior to, immediately following, and at selected time points post-TPE. Changes from baseline to 2 weeks post-TPE were: MG-ADL median -5.0, P < 0.0033, MG-QoL15 median -13.0, P < 0.001, MG-MMT median -10.0, P < 0.0001, and MG-Composite median -10.0, P < 0.005. TPE produced a rapid, clinically significant change in all instruments, indicating these outcome measures are robust endpoints for clinical trials of rapidly efficacious MG therapies.

Tacrolimus inhibits Th1 and Th17 responses in MuSK-antibody positive myasthenia gravis patients.

Muscle specific tyrosine kinase antibody positive myasthenia gravis (MuSK- MG) is characterized by autoantibodies against the MuSK protein of the neuromuscular junction resulting in weakness of bulbar and proximal muscles. We previously demonstrated that patients with MuSK-MG have increased pro-inflammatory Th1 and Th17 responses. Tacrolimus, an immunosuppressant used in AChR-MG and transplantation patients, inhibits T cell responses through interference with IL-2 transcription. The therapeutic efficacy and immunological effect of tacrolimus in MuSK-MG is unclear. In the current study we examined the proliferation, phenotype and cytokine production of CD4+ and CD8+ T cells in peripheral blood mononuclear cells of MuSK-MG following a 3-day in vitro culture with or without tacrolimus. We determined that tacrolimus profoundly suppressed CD4 and CD8 T cell proliferation and significantly suppressed Th1 and Th17 responses, as demonstrated by a reduced frequency of IFN-γ, IL-2, and IL-17 producing CD4 T cells and reduced frequencies of IFN-γ and IL-2 producing CD8 T cells. Tacrolimus also inhibits pathogenic Th17 cells coproducing IL-17 and IFN-γ. In addition, tacrolimus suppressed follicular T helper cell (Tfh) and regulatory T helper cell (Treg) subsets. These findings provide preliminary support for tacrolimus as a potential alternative immunosuppressive therapy for MuSK-MG.

Effect of therapeutic plasma exchange on immunoglobulins in myasthenia gravis.

An integrated understanding of therapeutic plasma exchange (TPE) effects on immunoglobulins, autoantibodies, and natural or acquired (vaccine) protective antibodies in patients with autoimmune myasthenia gravis (MG) is lacking. Prior studies measured TPE effects in healthy volunteers or heterogeneous autoimmune disease populations. We prospectively profiled plasma IgA, IgM, IgG, IgG subclasses (IgG1-4), acetylcholine receptor autoantibodies (AChR+), and protective antibodies in patients with AChR + MG receiving TPE for an exacerbation. TPE was performed according to institutional practice and patients were profiled for up to 12 weeks. Ten patients were enrolled (median age = 72.9 years; baseline MG-Composite = 21; median TPE treatments = 6 during their first course) and all improved. The maximum decrease in all immunoglobulins, including AChR autoantibodies, was achieved on the final day of the first TPE course (∼60-70% reduction). Three weeks post-TPE, mean AChR autoantibody, total IgG, IgG1, and IgG2 titers were below the reference range and had not recovered within 20% of baseline, whereas other measured immunoglobulins approached baseline values. We did not generally observe an "overshoot" of immunoglobulins above pre-TPE levels or accelerated recovery of pathologic AChR autoantibodies. Protective antibody profiles showed similar patterns as other IgGs and were detectable at levels associated with protection from infection. A slow return to baseline for IgGs (except IgG3) was observed, and we did not observe any obvious effect of concomitant medications on this recovery. Collectively, these findings enhance our understanding of the immunological effects of TPE and further support the concept of rapid immunoglobulin depletion for the treatment of patients with MG.

IL-11 Induces Th17 Cell Responses in Patients with Early Relapsing-Remitting Multiple Sclerosis.

Clinically isolated syndrome (CIS) suggestive of multiple sclerosis (MS) is the earliest clinically evident phase of the disease, which may provide valuable insight into the molecular mechanisms of the initiation of the autoimmune response in MS. Our results introduce IL-11 as a new cytokine that plays a role in the autoimmune response in the early phase of the disease. IL-11 is the highest upregulated cytokine in the sera and cerebrospinal fluid from CIS patients, which is also increased in patients with clinically definitive relapsing-remitting MS in comparison with healthy control subjects. Serum IL-11 levels are significantly increased during clinical exacerbations in comparison with remissions in the same patients. CD4(+) cells represent a predominant cell source of IL-11 in the peripheral circulation, and the percentage of IL-11(+)CD4(+) cells is significantly increased in CIS patients in comparison with healthy control subjects. Furthermore, we have identified IL-11 as a new Th17-promoting cytokine, because it induces a differentiation of naive CD4(+) T cells into Th17 cells, as well as expansion of Th17 memory cells. Because the Th17 cytokines IL-17F, IL-21 and TNF-α, and TGF-ß induce differentiation of naive cells in the IL-11-secreting CD4(+) cells, we propose that cross-talk between IL-11(+)CD4(+) and Th17 cells may play a role in the inflammatory response in relapsing-remitting MS.

A genome-wide association study of myasthenia gravis.

IMPORTANCE: Myasthenia gravis is a chronic, autoimmune, neuromuscular disease characterized by fluctuating weakness of voluntary muscle groups. Although genetic factors are known to play a role in this neuroimmunological condition, the genetic etiology underlying myasthenia gravis is not well understood. OBJECTIVE: To identify genetic variants that alter susceptibility to myasthenia gravis, we performed a genome-wide association study. DESIGN, SETTING, AND PARTICIPANTS: DNA was obtained from 1032 white individuals from North America diagnosed as having acetylcholine receptor antibody-positive myasthenia gravis and 1998 race/ethnicity-matched control individuals from January 2010 to January 2011. These samples were genotyped on Illumina OmniExpress single-nucleotide polymorphism arrays. An independent cohort of 423 Italian cases and 467 Italian control individuals were used for replication. MAIN OUTCOMES AND MEASURES: We calculated P values for association between 8,114,394 genotyped and imputed variants across the genome and risk for developing myasthenia gravis using logistic regression modeling. A threshold P value of 5.0×10(-8) was set for genome-wide significance after Bonferroni correction for multiple testing. RESULTS: In the overall case-control cohort, we identified association signals at CTLA4 (rs231770; P=3.98×10(-8); odds ratio, 1.37; 95% CI, 1.25-1.49), HLA-DQA1 (rs9271871; P=1.08×10(-8); odds ratio, 2.31; 95% CI, 2.02-2.60), and TNFRSF11A (rs4263037; P=1.60×10(-9); odds ratio, 1.41; 95% CI, 1.29-1.53). These findings replicated for CTLA4 and HLA-DQA1 in an independent cohort of Italian cases and control individuals. Further analysis revealed distinct, but overlapping, disease-associated loci for early- and late-onset forms of myasthenia gravis. In the late-onset cases, we identified 2 association peaks: one was located in TNFRSF11A (rs4263037; P=1.32×10(-12); odds ratio, 1.56; 95% CI, 1.44-1.68) and the other was detected in the major histocompatibility complex on chromosome 6p21 (HLA-DQA1; rs9271871; P=7.02×10(-18); odds ratio, 4.27; 95% CI, 3.92-4.62). Association within the major histocompatibility complex region was also observed in early-onset cases (HLA-DQA1; rs601006; P=2.52×10(-11); odds ratio, 4.0; 95% CI, 3.57-4.43), although the set of single-nucleotide polymorphisms was different from that implicated among late-onset cases. CONCLUSIONS AND RELEVANCE: Our genetic data provide insights into aberrant cellular mechanisms responsible for this prototypical autoimmune disorder. They also suggest that clinical trials of immunomodulatory drugs related to CTLA4 and that are already Food and Drug Administration approved as therapies for other autoimmune diseases could be considered for patients with refractory disease.

The role of fractalkine (CX3CL1) in regulation of CD4(+) cell migration to the central nervous system in patients with relapsing-remitting multiple sclerosis.

Fractalkine (CX3CL1) levels are increased in the cerebrospinal fluid (CSF) of patients with clinically isolated syndrome (CIS), as well as in the CSF and serum samples from patients with relapsing-remitting multiple sclerosis (RRMS). A higher percentage of circulating CD4(+) T-cells expressed its surface receptor (CX3CR1) and intracellular adhesion molecule (ICAM-1) in RRMS patients in comparison to healthy controls (HCs). The CX3CR1(+)ICAM-1(+)CD4(+) T-cells are enriched in the CSF of the RRMS patients. In vitro migration studies revealed that CD4(+) T-cells, which migrated toward a CX3CL1 gradient, expressed higher levels of ICAM-1 than non-migrating cells. CX3CL1 significantly increased IFN-γ and TNF-α gene expression and IFN-γ secretion by CD4(+) T-cells derived from the RRMS patients. CX3CL1 upregulated ICAM-1 expression on the surface of RRMS patient-derived but not HC-derived CD4(+) T-cells. Thus, CX3CL1 induces recruitment of CX3CR1(+)ICAM-1(+)CD4(+) T-cells into the central nervous system (CNS) during the early inflammatory response in MS.

Differential reconstitution of T cell subsets following immunodepleting treatment with alemtuzumab (anti-CD52 monoclonal antibody) in patients with relapsing-remitting multiple sclerosis.

Alemtuzumab (anti-CD52 mAb) provides long-lasting disease activity suppression in relapsing-remitting multiple sclerosis (RRMS). The objective of this study was to characterize the immunological reconstitution of T cell subsets and its contribution to the prolonged RRMS suppression following alemtuzumab-induced lymphocyte depletion. The study was performed on blood samples from RRMS patients enrolled in the CARE-MS II clinical trial, which was recently completed and led to the submission of alemtuzumab for U.S. Food and Drug Administration approval as a treatment for RRMS. Alemtuzumab-treated patients exhibited a nearly complete depletion of circulating CD4(+) lymphocytes at day 7. During the immunological reconstitution, CD4(+)CD25(+)CD127(low) regulatory T cells preferentially expanded within the CD4(+) lymphocytes, reaching their peak expansion at month 1. The increase in the percentage of TGF-ß1-, IL-10-, and IL-4-producing CD4(+) cells reached a maximum at month 3, whereas a significant decrease in the percentages of Th1 and Th17 cells was detected at months 12 and 24 in comparison with the baseline. A gradual increase in serum IL-7 and IL-4 and a decrease in IL-17A, IL-17F, IL-21, IL-22, and IFN-γ levels were detected following treatment. In vitro studies have demonstrated that IL-7 induced an expansion of CD4(+)CD25(+)CD127(low) regulatory T cells and a decrease in the percentages of Th17 and Th1 cells. In conclusion, our results indicate that differential reconstitution of T cell subsets and selectively delayed CD4(+) T cell repopulation following alemtuzumab-induced lymphopenia may contribute to its long-lasting suppression of disease activity.

B cells as a therapeutic target for IFN-ß in relapsing-remitting multiple sclerosis.

IFN-ß-1b is a first-line immunomodulatory therapy for relapsing-remitting multiple sclerosis (RR MS). However, its effects on B cells have not been characterized. In vitro studies of B cells derived from RR MS patients revealed that IFN-ß-1b decreases B cells' stimulatory capacity, as detected by inhibition of the Ag-specific T cell proliferative response upon Ag presentation by IFN-ß-1b-treated B cells. Our study has identified that IFN-ß-1b inhibited B cells' stimulatory capacity in RR MS patients and healthy controls through the suppression of CD40 and CD80 expression, whereas the MHC class I and II expression was not changed. IFN-ß-1b in vitro treatment inhibited B cell secretion of IL-1ß and IL-23 and induced IL-12 and IL-27. Supernatants transferred from IFN-ß-1b-treated B cells inhibited Th17 cell differentiation, as they suppressed gene expression of the retinoic acid-related orphan nuclear hormone receptor C and IL-17A and secretion of IL-17A. In addition, IFN-ß-1b induced B cells' IL-10 secretion, which may mediate their regulatory effect. Studies of B cells derived from RR MS patients treated with recombinant s.c. injected IFN-ß-1b revealed that they induced a significantly lower proliferative response in allogenic MLR than the B cells from untreated patients. Further confirming the IFN-ß-1b in vitro-induced changes in B cell cytokine secretion, B cells derived from the IFN-ß-1b-treated patients secreted significantly lower levels of IL-1ß and IL-23 and higher levels of IL-12 and IL-27 in comparison with the B cells derived from untreated patients. We conclude that IFN-ß-1b exerts its therapeutic effects in part by targeting B cells' functions that contribute to the autoimmune pathogenesis of RR MS.