Plasmid encoding a TLR3 and Fc fusion protein

Loss of B cell tolerance and generation of autoreactive anti-nuclear antibodies are hallmarks of systemic lupus erythematosus (SLE) and lupus nephritis. Lupus nephritis is characterized by glomerular and tubulointerstitial inflammation often initiated by the renal glomerular deposition of anti-nuclear immune complexes which trigger subsequent activation of complement, macrophages/monocytes and other innate inflammatory cells. The mechanism of anti-nuclear immunoglobulin accumulation and clearance in lupus nephritis pathogenesis remains largely uncharacterized. Here, we show that innate immune activation in the NZB/W F1 mouse model and in human lupus nephritis biopsies rapidly reduces DNase1 expression in renal cortex proximal tubular cells. To overcome the loss of endogenous DNase1, we treated lupus-prone mice with a hyperactive actin resistant variant of DNase1 with improved catalytic activity against nucleic acid-IgG immune complexes and acceptable in vivo pharmacokinetics. Hyperactive DNase1-Fc fusion protein ameliorates nephritis in a murine model of lupus nephritis and reduces immune complex deposition/complement fixation. Taken together, our data suggest that the loss of renal DNase1 through TLR signaling or other innate immune activation impairs clearance of autoreactive anti-nuclear immune complex deposits in the kidney to promote nephritis progression. Our findings provide a therapeutic rationale for using an engineered DNase1-Fc as a potential therapeutic approach in lupus nephritis.