Membrane Proteome-Wide Screening of Autoantibodies in CIDP Using Human Cell Microarray Technology.

BACKGROUND AND OBJECTIVES: Autoantibody discovery in complex autoimmune diseases is challenging. Diverse successful antigen identification strategies are available, but, so far, have often been unsuccessful, especially in the discovery of protein antigens in which conformational and post-translational modification are critical. Our study assesses the utility of a human membrane and secreted protein microarray technology to detect autoantibodies in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS: A cell microarray consisting of human embryonic kidney-293 cells expressing >5,000 human proteins was used. First, a validation step was performed with 4 serum samples from patients with autoimmune nodopathy (AN) to assess the ability of this technology to detect circulating known autoantibodies. The ability of the cell microarray technology to discover novel IgG autoantibodies was assessed incubating the array with 8 CIDP serum samples. Identified autoantibodies were subsequently validated using cell-based assays (CBAs), ELISA, and/or tissue immunohistochemistry and analyzed in a cohort of CIDP and AN (n = 96) and control (n = 100) samples. RESULTS: Serum anti-contactin-1 and anti-neurofascin-155 were detected by the human cell microarray technology. Nine potentially relevant antigens were found in patients with CIDP without other detectable antibodies; confirmation was possible in six of them: ephrin type-A receptor 7 (EPHA7); potassium-transporting ATPase alpha chain 1 and subunit beta (ATP4A/4B); leukemia-inhibitory factor (LIF); and interferon lambda 1, 2, and 3 (IFNL1, IFNL2, IFNL3). Anti-ATP4A/4B and anti-EPHA7 antibodies were detected in patients and controls and considered unrelated to CIDP. Both anti-LIF and anti-IFNL antibodies were found in the same 2 patients and were not detected in any control. Both patients showed the same staining pattern against myelinating fibers of peripheral nerve tissue and of myelinating neuron-Schwann cell cocultures. Clinically relevant correlations could not be established for anti-LIF and anti-IFNL3 antibodies. DISCUSSION: Our work demonstrates the utility of human cell microarray technology to detect known and discover unknown autoantibodies in human serum samples. Despite potential CIDP-associated autoantibodies (anti-LIF and anti-IFNL3) being identified, their clinical and pathogenic relevance needs to be elucidated in bigger cohorts.

Excellent response to anti-CD38 therapy with daratumumab in a patient with severe refractory CANOMAD.

BACKGROUND: Intravenous immunoglobulin (IVIG) and rituximab are considered the first-line and second-line treatments for Chronic Ataxic Neuropathy and Ophthalmoplegia with IgM-paraprotein, cold Agglutinins, and anti-Disialosyl antibodies (CANOMAD), with an overall clinical response around 50%. New anti-CD38 daratumumab, targeting long-lived plasma cells, has been reported as a promising therapy for treatment-refractory antibody-mediated disorders. We report the first case of a severe refractory CANOMAD, successfully treated with daratumumab. METHODS: A patient in their 70s with severe relapsing CANOMAD, refractory to IVIG, steroids, rituximab and ibrutinib developed severe tetraparesis and respiratory failure. Plasma exchange (PE) improved motor and ventilatory function; however, after 6 weeks, patient remained PE dependent. Intravenous daratumumab was initiated at 16 mg/kg weekly for 3 weeks, every 2 weeks for the second and third month, and monthly afterwards. RESULTS: After 3 weeks of starting daratumumab, PE was discontinued and, since then, the patient evolved to complete recovery. Antidisialosyl antibody titres decreased after PE and remained stable during daratumumab. Serum neurofilament light-chain levels were elevated in the exacerbation phase and normalised after daratumumab. The patient remains in clinical remission under monthly daratumumab, 12 months after initiation. CONCLUSIONS: The first patient with aggressive treatment-refractory CANOMAD treated with daratumumab provides proof-of-principle evidence that daratumumab may be an effective treatment in IgM-related neuropathies.

A new homozygous missense variant in LMOD3 gene causing mild nemaline myopathy with prominent facial weakness.

Nemaline myopathy (NEM) type 10, caused by biallelic mutations in LMOD3, is a severe congenital myopathy clinically characterized by generalized hypotonia and muscle weakness, respiratory insufficiency, joint contractures, and bulbar weakness. Here, we describe a family with two adult patients presenting mild nemaline myopathy due to a novel homozygous missense variant in LMOD3. Both patients presented mild delayed motor milestones, frequent falls during infancy, prominent facial weakness and mild muscle weakness in the four limbs. Muscle biopsy showed mild myopathic changes and small nemaline bodies in a few fibers. A neuromuscular gene panel revealed a homozygous missense variant in LMOD3 that co-segregated with the disease in the family (NM_198271.4: c.1030C>T; p.Arg344Trp). The patients described here provide evidence of the phenotype-genotype correlation, suggesting that non-truncating variants in LMOD3 lead to milder phenotypes of NEM type 10.

Rituximab in myasthenia gravis: efficacy, associated infections and risk of induced hypogammaglobulinemia.

The aim of this study is to evaluate the long-term efficacy, safety, and impact on immunoglobulin G (IgG) levels of rituximab in patients with myasthenia gravis (MG). A retrospective, observational study of drug-refractory MG patients treated with rituximab was done. The MG Foundation of America postintervention status (MGFA-PIS) was used to evaluate clinical response. Serum IgG levels were determined at baseline and post-treatment. Hypogammaglobulinemia was defined as IgG<7g/L. Thirty patients were included, 12 with anti-MuSK and 18 with anti-AChR antibodies. Mean (SD) follow-up was 85.5 (48) months. All 12 MuSK+ patients but only six (33%) AChR+ patients achieved minimal manifestations or remission (p<0.01). Nine severe infections were observed in five patients (17%). One patient was diagnosed with progressive multifocal leukoencephalopathy. At baseline, two patients (2/24; 8%) had hypogammaglobulinemia. During follow-up, hypogammaglobulinemia was observed in 60% (3/5) of patients who developed an infection and in 33% (7/21) who did not. Two of these patients died of infection-related complications. This study supports the effectiveness of rituximab in patients with MG, especially those with anti-MuSK antibodies. Severe infections may appear after rituximab treatment and hypogammaglobulinemia might play a role on it. A standard protocol would be needed to closely monitor IgG levels in MG patients treated with rituximab.

Immune Response and Safety of SARS-CoV-2 mRNA-1273 Vaccine in Patients With Myasthenia Gravis.

BACKGROUND AND OBJECTIVES: Evidence regarding the safety and efficacy of messenger RNA (mRNA) vaccines in patients with myasthenia gravis (MG) after immunosuppressive therapies is scarce. Our aim is to determine whether the mRNA-1273 vaccine is safe and able to induce humoral and cellular responses in patients with MG. METHODS: We performed an observational, longitudinal, prospective study including 100 patients with MG of a referral center for MG in our country, conducted from April 2021 to November 2021 during the vaccination campaign. The mRNA-1273 vaccine was scheduled for all participants. Blood samples were collected before vaccination and 3 months after a second dose. Clinical changes in MG were measured using the MG activities of daily life score at baseline and 1 week after the first and second doses. A surveillance of all symptoms of coronavirus disease 2019 (COVID-19) was conducted throughout the study. Humoral and cellular immune responses after vaccination were assessed using a spike-antibody ELISA and interferon gamma release assay in plasma. The primary outcomes were clinically significant changes in MG symptoms after vaccination, adverse events (AEs), and seroconversion and T-cell immune response rates. RESULTS: Ninety-nine patients completed the full vaccination schedule, and 98 had 2 blood samples taken. A statistically significant worsening of symptoms was identified after the first and second doses of the mRNA-1273 vaccine, but this was not clinically relevant. Mild AEs occurred in 14 patients after the first dose and in 21 patients after the second dose. Eighty-seven patients developed a humoral response and 72 patients showed a T-cell response after vaccination. A combined therapy with prednisone and other immunosuppressive drugs correlated with a lower seroconversion ratio (OR = 5.97, 95% CI 1.46-24.09, p = 0.015) and a lower T-cell response ratio (OR = 2.83, 95% CI 1.13-7.13, p = 0.024). DISCUSSION: Our findings indicate that the mRNA vaccination against COVID-19 is safe in patients with MG and show no negative impact on the disease course. Patients achieved high humoral and cellular immune response levels. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that patients with MG receiving the mRNA-1273 vaccine did not show clinical worsening after vaccination and that most of the patients achieved high cellular or immune response levels.