Interleukin 27 is a novel cytokine with anti-inflammatory effects against spondyloarthritis through the suppression of Th17 responses.

Introduction: Spondylarthritis (SpA) development in HLA-B27/human β2-microglobulin transgenic rat (B27-rat) is correlated with altered conventional dendritic cell (cDC) function that promotes an inflammatory pattern of CD4+T cells, including a biased expansion of pro-inflammatory Th population and imbalance of regulatory T cells cytokine profile. Transcriptomic analysis revealed that cDCs from B27-rats under express IL-27, an anti-inflammatory cytokine which induces the differentiation of IL-10 regulatory T cells and inhibits Th cells.

Methods: Here, we first investigated whether addition of exogenous IL-27 could reverse the inflammatory pattern observed in CD4 T cells. Next, we performed preclinical assay using IL-27 to investigate whether treatment could prevent SpA development in B27-rats.

Results: addition of IL-27 to cocultures of cDCs and CD4 T cell subsets from B27-rats reduced IL-17 and enhanced IL-10 production by T cells. Likewise, IL-27 inhibited the production of IL-17 by CD4 T cells from SpA patients. Interestingly, treatment with recombinant IL-27 starting before SpA onset, inhibited SpA development in B27-rats through the suppression of IL-17/TNF producing CD4 T cells.

Discussion: Overall, our results reveal a potent inhibitory effect of IL-27 and highlight this cytokine as a promising new therapeutic target in SpA, especially for SpA patients non responders to currently approved biotherapies.