Disease-specific expansion of CD29+IL-17RA+ T effector cells possessing multiple signalling pathways in spondyloarthritis

Objectives T cells adhere to enthesis fibrocartilage via integrins and intrinsically require IL-17RA-mediated signals to maintain their effector function. We analysed CD29(+)IL-17RA(+) T cells in inflamed lesions and peripheral blood in patients with SpA and investigated their association with disease activity and therapeutic response. Methods Transcriptome analysis of synovial fluid T cells from PsA was performed using publicly available bulk cell RNA sequencing data. Blood samples were obtained from healthy controls (n = 37), RA (n = 12), IgG4-related disease (IgG4-RD; n = 12), large vessel vasculitis (LVV; n = 12) and SpA (n = 28) and were analysed by flow cytometry. Results T cells in the inflamed joints of PsA showed CD29 and IL-17RA expression. CD29(+)IL-17RA(+) T cells showed enriched CXCR3(+)CD45RA(+) effector cells and activation of spleen tyrosine kinase (Syk), nuclear factor kappa B (NF-kappa B) and Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathways. The proportion of peripheral blood CD29(+)IL-17RA(+) T cells was significantly increased in patients with SpA compared with patients with RA, IgG4-RD or LVV and in healthy controls. Based on the ASDAS-CRP scores, the proportion of CD29(+)IL-17RA(+) T cells was positively correlated with disease activity in treatment-naive patients with active SpA. Anti-IL-17 but not anti-TNF monoclonal antibodies reduced CD29(+)IL-17RA(+) T cells. Conclusions CD29(+)IL-17RA(+) T effector cells with enhanced Syk, NF-kappa B and JAK-STAT pathways were specifically increased in SpA and were correlated with disease activity, implicating a role of this newly identified T cell population in the pathogenesis. Anti-IL-17 monoclonal antibodies may be effective for patients by reducing this pathogenic T cell population.

Automated summary

CD29(+)IL-17RA(+) T effector cells are increased in SpA and correlated with disease activity. Anti-IL-17 monoclonal antibodies may be effective by reducing this pathogenic T cell population.