Rapidly progressive IgA nephropathy with membranoproliferative glomerulonephritis-like lesions in an elderly man following the third dose of an mRNA COVID-19 vaccine: a case report.

BACKGROUND: As messenger RNA (mRNA)-based vaccines for coronavirus disease 2019 (COVID-19) have been administered to millions of individuals worldwide, cases of de novo and relapsing glomerulonephritis after mRNA COVID-19 vaccination are increasing in the literature. While most previous publications reported glomerulonephritis after the first or second dose of an mRNA vaccine, few reports of glomerulonephritis occurring after the third dose of an mRNA vaccine currently exist. CASE PRESENTATION: We report a case of rapidly progressive glomerulonephritis in a patient following the third dose of an mRNA COVID-19 vaccine. A 77-year-old Japanese man with a history of hypertension and atrial fibrillation was referred to our hospital for evaluation of anorexia, pruritus, and lower extremity edema. One year before referral, he received two mRNA vaccines (BNT162b2) for COVID-19. Three months before the visit, he received a third mRNA vaccine (mRNA-1273) for COVID-19. On admission, the patient presented severe renal failure with a serum creatinine level of 16.29 mg/dL, which had increased from 1.67 mg/dL one month earlier, prompting us to initiate hemodialysis. Urinalysis showed nephrotic-range proteinuria and hematuria. Renal biopsy revealed mild mesangial proliferation and expansion, a lobular appearance, and double contours of the glomerular basement membrane. Renal tubules had severe atrophy. Immunofluorescence microscopy showed strong mesangial staining for IgA, IgM, and C3c. Electron microscopy exhibited mesangial and subendothelial electron-dense deposits, leading to a diagnosis of IgA nephropathy with membranoproliferative glomerulonephritis-like changes. The kidney function remained unchanged after steroid therapy. CONCLUSIONS: Although the link between renal lesions and mRNA vaccines remains unclear, a robust immune response induced by mRNA vaccines may play a role in the pathogenesis of glomerulonephritis. Further studies of the immunological effects of mRNA vaccines on the kidney are warranted.

Thrombocytopenia during avacopan administration: A case report.

Avacopan is a novel C5a receptor antagonist recently approved for the treatment of microscopic polyangiitis and granulomatosis with polyangiitis. To our knowledge, thrombocytopenia induced by avacopan has not been reported. We report a case of a 78-year-old man with microscopic polyangiitis who developed rapidly progressive glomerulonephritis (RPGN) and vasculitis neuropathy. After developing RPGN, he was treated with prednisolone, which was ineffective. As the dosage of corticosteroids was decreased, he developed impaired dorsiflexion of the left ankle, tingling and numbness in his feet, consistent with vasculitis neuropathy. After a 3-day administration of methylprednisolone, we started avacopan and prednisolone 20 mg/d to reduce the corticosteroid dosage. One week after starting avacopan, platelet counts began to decrease, eventually leading to the cessation of the drug. The possibility of thrombotic microangiopathy and heparin-induced thrombocytopenia was considered unlikely given the clinical course and laboratory studies. After 3 weeks of avacopan cessation, platelet counts began to increase, suggesting avacopan as the most probable cause of thrombocytopenia. Our case highlights the importance of postmarketing surveillance of avacopan to identify its adverse events that were not reported in clinical trials to ensure its safe use. Clinicians should carefully monitor platelet counts when using avacopan.

Lymphoma Driver Mutations in the Pathogenic Evolution of an Iconic Human Autoantibody.

Pathogenic autoantibodies arise in many autoimmune diseases, but it is not understood how the cells making them evade immune checkpoints. Here, single-cell multi-omics analysis demonstrates a shared mechanism with lymphoid malignancy in the formation of public rheumatoid factor autoantibodies responsible for mixed cryoglobulinemic vasculitis. By combining single-cell DNA and RNA sequencing with serum antibody peptide sequencing and antibody synthesis, rare circulating B lymphocytes making pathogenic autoantibodies were found to comprise clonal trees accumulating mutations. Lymphoma driver mutations in genes regulating B cell proliferation and V(D)J mutation (CARD11, TNFAIP3, CCND3, ID3, BTG2, and KLHL6) were present in rogue B cells producing the pathogenic autoantibody. Antibody V(D)J mutations conferred pathogenicity by causing the antigen-bound autoantibodies to undergo phase transition to insoluble aggregates at lower temperatures. These results reveal a pre-neoplastic stage in human lymphomagenesis and a cascade of somatic mutations leading to an iconic pathogenic autoantibody.