Inhibition of Janus Kinase pathway corrects IFN-driven inflammation and epithelial dysfunction in Sjogren’s disease

Abstract

Abstract Background/Purpose: A systematic investigation of the role of interferons (IFNs) and Janus kinases (JAK) - signal transducer and activator of transcription (STAT) pathway at the cellular and tissue level in humans is lacking. Methods: PBMC and minor salivary gland (MSG) biopsies were obtained from healthy volunteers (HVs) and SjD patients that met the 2016 American College of Rheumatology classification criteria on IRB approved protocols. Results: RNA sequencing (RNAseq) on MSGs found enrichment of JAK-STAT pathway genes in SjD (n=36) compared to HV (n=13). A composite score of 21-IFN stimulated genes (ISGs) was elevated in SjD and positively correlated with clinical variables of SjD (focus scores). Immunofluorescence showed increased expression of JAK3 in infiltrating lymphocytes. Single cell RNAseq (scRNAseq) of MSGs from SjD (n=12) and HVs (n=17) showed upregulated JAK-STAT pathway genes in infiltrating T and B lymphocytes; antigen presenting cells; and endothelial cells. Ex-vivo studies showed baseline elevation of intracellular phosphorylated STAT1 and STAT3 levels in PBMCs in SjD (n=21) vs HVs (n=11). Stimulation with IFNb further increased the pSTAT1 signaling and JAK inhibition with tofacitinib led to normalization of JAK-STAT signaling. HV and SjD-derived primary salivary gland epithelial cells (pSGEC) showed elevated basal CXCL10in patients with SjD (n=5) vs HV (n=5); and JAK inhibitors (tofacitinib, baricitinib) blocked IFNb driven ISG expression. Conclusion: Our findings pinpoint cells responsive to JAK inhibition and illustrate in patient tissues that JAK inhibitors may be beneficial in SjD. These data will serve as biological endpoints for clinical trials [NCT04496960]. This research was supported by the Intramural Research Programs of the National Institute of Arthritis and Musculoskeletal and Skin Disease and National Institute of Dental and Craniofacial Research