Treatment of granuloma annulare and suppression of pro-inflammatory cytokine activity with tofacitinib [scRNA-Seq]

Granuloma annulare (GA) is a common inflammatory cutaneous disorder characterized by macrophage accumulation and activation in the skin. Its pathogenesis is poorly understood and there are no reliably effective treatments. Its potential health implications, if any, are unknown. Using single cell RNA sequencing (scRNAseq) we show that in GA, CD4+ T cells over-produce interferon (IFN)-g resulting in inflammatory polarization of macrophages and in altered extracellular matrix (ECM) production induced by the activity of oncostatin M, an interleukin (IL)-6 family cytokine, on fibroblasts. This mechanism identifies Janus kinase (JAK) inhibition as a potential therapeutic strategy, as both IFN-g and OSM signal via the JAK-STAT pathway. Indeed, treatment of five patients with severe, longstanding GA with tofacitinib (a JAK1/3 inhibitor) resulted in clinical and histologic disease remission in three patients and marked improvement in the other two. Treatment was associated with suppression of pathogenic cytokine activity in the skin and dissolution of macrophages. We also found that severe GA was associated with hypercytokinemia in plasma of patients, and JAK inhibition normalized this hypercytokiemia. Together, our results highlight the constitutive activity of the JAK-STAT pathway in GA as a result of IFN-g and OSM and identify JAK inhibitors as a potential molecularly targeted treatment for this disorder.

4 mm punch biopsies of skin were obtained on separate days from 3 patients with GA and 3 healthy volunteers. Biopsies were immediately dissociated using dispase (10 mg/mL) followed by liberase. Live single cells were purified by FACS and single cell libraries were prepared using a 10X chromium controller according to the manufacturer’s instructions and sequenced using an Illumina Hiseq 4000.