Abstract
Neutrophil extracellular trap (NET) formation contributes to immune defense and is a distinct form of cell death. Excessive NET formation is found in patients with anti–neutrophil cytoplasmic antibody–associated (ANCA-associated) vasculitis (AAV), contributing to disease progression. The clearance of dead cells by macrophages, a process known as efferocytosis, is regulated by the CD47-mediated “don’t eat me” signal. Hence, we hypothesized that pathogenic NETs in AAV escape from efferocytosis via the CD47 signaling pathway, resulting in the development of necrotizing vasculitis. Immunostaining for CD47 in human renal tissues revealed high CD47 expression in crescentic glomerular lesions of patients with AAV. In ex vivo studies, ANCA-induced netting neutrophils increased the expression of CD47 with the reduction of efferocytosis. After efferocytosis, macrophages displayed proinflammatory phenotypes. The blockade of CD47 in spontaneous crescentic glomerulonephritis-forming/Kinjoh (SCG/Kj) mice ameliorated renal disease and reduced myeloperoxidase-ANCA (MPO-ANCA) titers with a reduction in NET formation. Thus, CD47 blockade would protect against developing glomerulonephritis in AAV via restored efferocytosis of ANCA-induced NETs.
Authors
Satoka Shiratori-Aso, Daigo Nakazawa, Takashi Kudo, Masatoshi Kanda, Yusho Ueda, Kanako Watanabe-Kusunoki, Saori Nishio, Sari Iwasaki, Takahiro Tsuji, Sakiko Masuda, Utano Tomaru, Akihiro Ishizu, Tatsuya Atsumi
Figure 4
Blockade of CD47 protected mice from spontaneous development of vasculitis.
