Preliminary exploration of effects of the JAK inhibitor tofacitinib on pyoderma gangrenosum: In vitro inhibition of NETs and Th17 differentiation.

BACKGROUND

Pyoderma gangrenosum (PG), a refractory inflammatory disorder, remains a condition with incompletely understood pathogenesis. Currently, no FDA-approved treatments are available. Janus kinase (JAK) inhibitors have been reported sporadically in case studies as effective treatments for PG.

OBJECTIVE

To characterize the cellular and molecular landscape associated with JAK/STAT (signal transducer and activator of transcription) pathway overactivation in PG lesions, and investigate the potential effects of tofacitinib on PG.

METHODS

Single-cell RNA sequencing (scRNA-seq) and multiplex immunohistochemistry (mIHC) were employed to characterize the cellular and molecular landscape of JAK/STAT pathway overactivation in PG. In vitro experiments (immunostaining, qPCR, western blot, flow cytometry) were performed to further validate the potential effects of tofacitinib on PG.

RESULTS

We identified significant overactivation of the JAK/STAT pathway in PG lesions-particularly in advanced stages-which, in terms of immune inflammation, is primarily driven by myeloid cells and T cells. This activation was associated with enhanced neutrophil extracellular trap (NET) formation in myeloid cells and aberrant differentiation/plasticity of Th17 and Th17.1 (IL-17/IFN-γ double-producing) cells. In vitro cell experiments further demonstrated that the JAK inhibitor tofacitinib suppresses STAT phosphorylation in myeloid and T cells, myeloid NETosis, and IL-17A production.

CONCLUSION

Our study investigated immunological profiling of PG lesions via scRNA-seq and mIHC, along with in vitro validation. These findings delineate a multi-axis cellular and molecular landscape of PG linked to aberrant JAK/STAT signaling, and provide preliminary in vitro evidence supporting potential inhibitory effects of tofacitinib on key pathological processes of PG.