Interferon γ -induced chemokines in psoriatic arthritis.

Interferon γ-inducible protein (IP-10) chemokine is implicated in the pathogenesis of psoriatic arthritis (PsA). It was shown that chemokine (C-X-C motif) receptor (CXCR) 3 and CXCR4 were expressed by both blood-derived plasmacytoid dendritic cells (pDCs) and pDCs isolated from rheumatoid arthritis (RA) and PsA synovial fluid (SF) and that IP-10, chemokine (C-X-C motif) ligand (CXCL)-11, and CXCL-12 present in RA and PA SF stimulated chemotaxis of blood-derived pDCs. High circulating levels of IP-10 and chemokine (C-C motif) ligand (CCL) 2 have been found in PsA patients, with a T helper cells (Th) 1 immune predominance in the early phase of the disease. Moreover a decline of IP-10 levels has been observed in long lasting PsA, with a significant increase of the CCL2/IP-10 ratio, suggesting a shift from Th1 to Th2 immune response in long duration PsA. IP-10 levels in PsA patients are significantly higher in presence of autoimmune thyroiditis. IP-10 has been suggested to be a good marker to monitor the activity or progression of PsA. Attempts have been made to modulate or inhibit the production of IP-10 in PsA in order to modify the course of the disease.