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 4

Gene expression changes in spleen after cyclophosphamide treatment or blockade of Btk, Syk, or BAFF in IFNα-precipitated LN in NZB/W_F1 mice.

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Gene expression changes in spleen after cyclophosphamide treatment or bl...
LN was IFNα-accelerated in female NZB/W_F1 mice as described in Figure 3. Mice were treated for 4 weeks starting 3 weeks after AdIFNα induction with vehicle, 100 mg/kg G-744, 60 mg/kg P505-15, 7.5mg/kg Ig control, 7.5 mg/kg BR3-Fc, or Cyclophosphamide (Cytoxan/CTX) (n = 10/group), followed by RNA sequencing analysis of splenic RNA. Two groups of 17-week-old NZB/W_F1 animals were also included (see Supplemental Figure 7) that were either not injected with AdIFNα (naive group) or treated for 3 weeks with AdIFNα (AdIFNα group). (A) Gene set enrichment analysis was performed using predefined immune gene modules (n = 5/group). 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–D) G-744 reduces transcripts associated with ASC generation. (B) Calculated fold-changes in spleen from vehicle-treated versus naive animals (x-axis), or G-744-treated versus vehicle-treated animals (y-axis), are shown for all transcripts (gray) or ASC-specific transcripts (black). Dotted lines indicate a 2-fold change in expression. (C) Heatmap visualization of select ASC-specific transcripts that were induced (log2-fold change > 2, P < 0.05) in spleens of vehicle-treated animals compared with naive animals. Each column in the heatmap represents 1 animal within each treatment group. Genes marked in blue were reduced after G-744 treatment compared with vehicle-treated animals (fold change > 1.5, P < 0.05). (D and E) Box plot of reads per kilobase of transcript per million mapped reads (RPKM) expression of (D) select individual genes from C significantly affected by G-744 treatment and (E) select B cell genes affected by BR3-Fc treatment. Gene expression data were plotted using box plots overlaid with all observed data points. The box corresponds to the 1st quartile, median (black line), and 3rd quartile. The whiskers extend to the most extreme data point that is no more than 1.5 times the interquartile range from the box; *P < 0.05, **P < 0.005, ***P < 0.0005, using DESeq2 to fit a negative binomial model, as described above.