Lupus-like phenotypes emerge from loss of macrophage derived Dnase1L3

Abstract

One leading cause of death in women is autoimmunity. One prominent autoimmune disease is Systemic Lupus Erythematosus (lupus). During lupus, inflammation is driven by autoantibodies that target cell-free DNA. Cell-free DNA is degraded by two serum endonucleases, Dnase1 and Dnase1L3. The loss of Dnase1L3 causes lupus in humans and mice, but the amount of Dnase1L3 necessary to prevent lupus onset is unknown. Since DnaselL3 is secreted by macrophages and dendritic cells, we hypothesized that loss of macrophage-derived DnaselL3 is sufficient to cause lupus-like phenotypes in mice. We generated conditional knockout (cKO) mice lacking DnaselL3 expression in macrophages. Sera was collected weekly from these mice until 50 weeks of age. To measure autoantibody induction, total IgG, total IgM, anti-dsDNA and anti-nuclear antibody levels were analyzed at 4, 20, 30 and 50 weeks. Sandwich ELISA was used to quantitate antibody levels in control and cKO mice. Homogeneous and peripheral anti-nuclear antibodies were detected by immunofluorescence, consistent with anti-dsDNA antibodies. Total IgG, anti-ds DNA antibody levels increased in cKO mice. We conclude that SLE-like phenotypes arise in mice due to the loss of macrophage Dnase1L3. This suggest that macrophage derived DnaselL3 is critical to controlling lupus. Plains Bridges to the Baccalaureate Program (PBB) (NIH 2R25GM83730-B)