SIRPa agonist antibody treatment ameliorates experimental arthritis and colitis [sequencing]
The innate immune system is finely tuned to enable rapid response to pathogenic stimuli but keep quiescent during tissue homeostasis.Balance of activating and inhibitory signaling sets a threshold for immune activation. Signal regulatory protein (SIRPa) is an immune inhibitory receptor expressed by myeloid cells and interacts with CD47 to inhibit immune cell phagocytosis, migration, and activation. Despite the progress of SIRPa and CD47 antagonist antibodies to promote anti-cancer immunity, it is not yet known whether therapeutic SIRPa receptor agonism could restrain excessive autoimmune inflammation in the context of autoimmunity. Here, we reported that increased neutrophil- and monocyte-associated genes including SIRPA in inflamed tissues biopsies of rheumatoid arthritis and inflammatory bowel diseases, and elevated SIRPA in colonic biopsies is associated with treatment refractory ulcerative colitis patients. We next identified a novel agonistic anti-SIRPa antibody that exhibited potent anti-inflammatory effects in reducing neutrophil and monocytes chemotaxis and tissue infiltration. In preclinical models of arthritis and colitis, anti-SIRPa agonistic antibody ameliorates autoimmune joint inflammation and inflammatory colitis through reducing neutrophils and monocytes in tissues. Our work provides a proof-of-concept for SIRPa receptor agonism for suppressing excessive innate immune activation and autoimmune inflammatory therapeutic treatment Overall design: Comparison of non-disease control, disease mice with a negative control antibody, and disease mice treated with anti-SIRPa antibody. Total paw tissues (each from 4 individual mice) of naïve, isotype control, agonistic anti-SIRPa treated mice 7 days post K/BxN serum transfer. Joint samples were isolated for RNA sequencing and each sample is from one individual animal.