Recirculating Memory T Cells in the Pathogenesis of Psoriatic Arthritis and Cutaneous Psoriasis

The aim of the study is to investigate the link between pro-inflammatory T cells responses arising in the skin in patients with cutaneous psoriasis and those present in the joints of patients developing psoriatic arthritis. The study is based on the hypothesis that a fraction of T cells with memory phenotype can recirculate from the skin and relocalize at extracutaneous sites including enthesis or synovial tissue thus propagating the pro-inflammatory cycle. This could represent a pathogenic mechanism in the development of PsA. The main aim of the study is to define the phenotypic and functional differences of circulating T cells in patients cutaneous psoriasis, patients with psoriatic arthritis and in control group of healthy subject. To this end the investigators analyze the expression of cell surface markers of central memory (TCM), effector memory (TEM) and effector (Teff) cells, within this subsets the investigators evaluate the expression of chemokine receptors as well as skin and tissue homing molecules. There will be also an evaluation of the T cell polarization towards Th1/Tc1 or Th17/Tc17 phenotype by evaluating the cytokine expression profile. In selected patients with PsA the researchers analyze in parallel the phenotype and the cytokine profile of T cell subpopulations in peripheral blood and in synovial fluid, The results of this study could possibly allow to define distinctive features of circulating T cells in patients with PsA and to understand the link between circulating and synovial fluid T cells in patients with PsA.