The aim of this project is to improve our understanding of the role of IL-23 in the pathophysiology of axial SpA and peripheral SpA.~This objective is detailed in three specific aims:~Define the effects of IL-23 on gene expression and cytokine production in innate and adaptive T lymphocytes from patients with SpA, and correlate them with the patient's genotype;~Phenotypically characterize immune cell populations in peripheral blood and in synovial fluid from peripheral SpA patients and identify at the single cell level the cells expressing the IL-23 receptor and/or producing IL-17.~The study population to be included are patients affected by SpA, attended to in the Rheumatology Departments of Cochin Hospital or of Saint Antoine Hospital in Paris. Participants will be divided into two groups: Group 1 comprises patients diagnosed with axial SpA, Group 2 SpA patients with peripheral SpA
This is a research study involving humans, of the interventional type with minimal risks and constraints (RIPH2). It is a bicentric, non randomized prospective study aiming to better understand the mechanisms of the response to anti-IL-23 biologics in Spondyloarthritis patients attending the rheumatology department of hospital Cochin and Saint Antoine (APHP).