Association of circulating lymphocyte subsets with response to IL17i and TNFi in axial spondyloarthritis

Objective Biologic disease-modifying anti-rheumatic drugs (b-DMARDs) have qualitatively improved the management of axial spondyloarthritis (axSpA), but up to 30-40% of patients do not respond. Although lymphocytes are clearly implicated in the pathology of SpA, circulating lymphocyte subsets (LS) dynamics has been poorly studied. The objective of this pilot study was to comprehensively analyse circulating LS abnormalities in axSpA, and to determine their potential association with response to b-DMARDs. Methods Sixty-nine patients with axSpA and 141 control subjects (HC) were included. The clinical features were measured at baseline, and additionally at 6 months in a subgroup of patients who received TNFi (n=36) or IL17i (n=26). Clinical response was defined as a 50% reduction of BASDAI or decrease in ASDAS of 1.1 point. CD4/CD8 T-cells, B-cells and NK-cells and their subsets were analysed by flow cytometry at inclusion. Results At baseline, alterations in LS were observed in axSpA with reduced/increased frequencies of 10/27 subsets (p<0.003 after correction) and trends for another 5. There was no association of response to bDMARDs with clinical data. Response to IL17i ( 61% cases) was associated with a higher frequency of NK-cells (p=0.003), trends for change in naive/memory- CD8+T-cells (p<0.055) and increased expression of KIR3DL2 on Th17-cells (p=0.052). No LS was associated with response to TNFi (69% cases) although trends were observed (CD4(+)T-cells subsets, higher IL-6R on CD4(+)/CD8(+)T-cells). Conclusion This pilot work demonstrated a dysregulation of LS in axSpA. The association observed between several LS and clinical response to IL17i (NK/CD8 subsets/Th17-KIR3DL2) was very different to that observed for TNFi (CD4/IL-6R).