Systemic lupus erythematosus (SLE) is often associated with exaggerated B cell activation promoting plasma cell generation, immune-complex deposition in the kidney, renal infiltration of myeloid cells, and glomerular nephritis. Type-I IFNs amplify these autoimmune processes and promote severe disease. Bruton’s tyrosine kinase (Btk) inhibitors are considered novel therapies for SLE. We describe the characterization of a highly selective reversible Btk inhibitor, G-744. G-744 is efficacious, and superior to blocking BAFF and Syk, in ameliorating severe lupus nephritis in both spontaneous and IFNα-accelerated lupus in NZB/W_F1 mice in therapeutic regimens. Selective Btk inhibition ablated plasmablast generation, reduced autoantibodies, and — similar to cyclophosphamide — improved renal pathology in IFNα-accelerated lupus. Employing global transcriptional profiling of spleen and kidney coupled with cross-species human modular repertoire analyses, we identify similarities in the inflammatory process between mice and humans, and we demonstrate that G-744 reduced gene expression signatures essential for splenic B cell terminal differentiation, particularly the secretory pathway, as well as renal transcriptional profiles coupled with myeloid cell–mediated pathology and glomerular plus tubulointerstitial disease in human glomerulonephritis patients. These findings reveal the mechanism through which a selective Btk inhibitor blocks murine autoimmune kidney disease, highlighting pathway activity that may translate to human SLE.
Arna Katewa, Yugang Wang, Jason A. Hackney, Tao Huang, Eric Suto, Nandhini Ramamoorthi, Cary D. Austin, Meire Bremer, Jacob Zhi Chen, James J. Crawford, Kevin S. Currie, Peter Blomgren, Jason DeVoss, Julie A. DiPaolo, Jonathan Hau, Adam Johnson, Justin Lesch, Laura E. DeForge, Zhonghua Lin, Marya Liimatta, Joseph W. Lubach, Sami McVay, Zora Modrusan, Allen Nguyen, Chungkee Poon, Jianyong Wang, Lichuan Liu, Wyne P. Lee, Harvey Wong, Wendy B. Young, Michael J. Townsend, Karin Reif
Btk blockade reduces differentiation of human memory B cells into plasmablasts in the presence of IFNα.