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ANCA-associated vasculitis (AAV) is a life-threatening disease characterized by small vessel inflammation and pathogenic self-directed antibodies. Programmed death-ligand 1 receptor (PD-1) and programmed cell death ligand-1 (PD-L1) are immune checkpoint molecules crucial for maintaining tolerance and immune homeostasis. After checkpoint inhibition therapy, development of various autoimmune diseases and immune-related adverse events (irAEs) have been observed. Here, we investigated the immunomodulatory roles of neutrophils through the expression of immune checkpoint molecule (PD-L1), migratory molecules (CXCR2), chemotactic chemokines (CXCL5) and other important molecules (BAFF and HMGB1) in development of AAV. We also scrutinized the immune mechanism responsible for development of pauci-immune crescentic GN (PICGN). We demonstrate for the first time that the frequency of PD-L1 expressing neutrophils was significantly reduced in AAV patients compared to healthy controls and correlated negatively with disease severity (BVASv3). Further, in renal biopsy, reduced PD-L1 immune checkpoint expression provides a microenvironment that unleashes uncontrolled activated CD4 + T cells, B cells, neutrophils and macrophages and ultimately causes engulfment of immune complexes leading to PICGN. Furthermore, during remission, reduced neutrophils PD-L1 and CXCR2 expression, increased neutrophils CXCL5 expression and increased peripheral effector memory T cells and increased HMGB1 and BAFF levels in serum, demonstrate the propensity for the persistence of sub-clinical inflammation, which could explain relapse, in this group of diseases. [ABSTRACT FROM AUTHOR]

For the foreseeable future, vaccines are the cornerstone in the global campaign against the Coronavirus Disease-19 (COVID-19) pandemic. As the number and fatalities due to COVID-19 decline and the lockdown anywise rescinded, we recognize an increase in the incidence of autoimmune disease post-COVID-19 vaccination. However, the causality of the most vaccine-induced side effects is debatable and, at best, limited to a temporal correlation. We herein report a case of a 51-year-old gentleman who developed Anti-Neutrophil Cytoplasmic Antibody (ANCA)-associated vasculitis (AAV) 2 week post-COVID-19 vaccination. The patient responded favorably to oral steroids and rituximab. Additionally, we conducted a case-based review of vaccine-associated AAV describing their clinical manifestations and treatment response of this emerging entity. [ABSTRACT FROM AUTHOR]