Btk-specific inhibition blocks pathogenic plasma cell signatures and myeloid cell–associated damage in IFNα-driven lupus nephritis
Arna Katewa, … , Michael J. Townsend, Karin Reif
Arna Katewa, … , Michael J. Townsend, Karin Reif
Published April 6, 2017
Citation Information: JCI Insight. 2017;2(7):e90111. https://doi.org/10.1172/jci.insight.90111.
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Research Article Immunology

Btk-specific inhibition blocks pathogenic plasma cell signatures and myeloid cell–associated damage in IFNα-driven lupus nephritis

Abstract

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.

Authors

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

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Figure 6

Gene expression changes in kidney in IFNα-accelerated LN in NZB/W_F1 mice after treatment with G-744, P505-15, BR3-Fc, or cyclophosphamide (Cytoxan).

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Gene expression changes in kidney in IFNα-accelerated LN in NZB/W_F1 mic...
RNA sequencing analysis was performed on kidney RNA (n = 5/group) derived from the experiment described in Figure 4. (A) Gene set enrichment analysis of predefined immune (see Figure 4A) and human LN ortholog gene modules (as defined in D and E); gene sets that showed significant enrichment (permutation P < 0.01) are shown as a heatmap indicating the magnitude of the gene set enrichment statistic. (B and C) Analyses of overlapping effects on renal gene transcription by drug treatments. (B) Renal transcripts that were significantly upregulated in diseased kidneys versus naive animals (2-fold elevated with FDR of 0.05) were assessed for their downregulation (≥1.5-fold with FDR of 0.05) by cyclophosphamide (CTX) versus G-744 treatment. Blue dots indicate genes significantly reduced by G-744, black dots indicate genes significantly reduced by CTX, and orange dots indicate genes significantly downregulated by both treatments. (C) Venn diagram showing the degree of overlap of genes upregulated in the kidneys of diseased animals that were subsequently decreased by CTX, G-744, or P505-15 treatment using the same statistical cutoffs as stated for B. The number of genes affected by each treatment is indicated within each intersection, and the number of genes unaffected by any of these treatments is indicated outside of the circles. (D and E) Effect of drug treatment on human LN ortholog genes previously identified to be upregulated in the (D) glomerulus or (E) tubulointerstitium of nephritic kidneys from human LN patients (see Methods). Genes that showed individual significant changes with any treatment versus their controls are indicated (≥1.5-fold difference between groups with an adjusted P < 0.01 as determined using a negative binomial generalized linear model). Each column in the heatmap represents 1 animal within each treatment group.