Proinflammatory Soluble Interleukin-15 Receptor Alpha Is Increased in Rheumatoid Arthritis

Abstract EN

Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease in which many cytokines have been implicated.

In particular, IL-15 is a cytokine involved in the inflammatory processes and bone loss.

The aim of this study was to investigate the existence in synovial fluid of soluble IL-15Rα, a private receptor subunit for IL-15 which may act as an enhancer of IL-15-induced proinflammatory cytokines.

Soluble IL-15Rα was quantified by a newly developed enzyme-linked immunosorbent assay (ELISA) in samples of synovial fluid from patients with RA and osteoarthritis (OA).

The levels of IL-15Rα were significantly increased in RA patients compared to OA patients.

Also, we studied the presence of membrane-bound IL-15 in cells from synovial fluids, another element necessary to induce pro-inflammatory cytokines through reverse signaling.

Interestingly, we found high levels of IL-6 related to high levels of IL-15Rα in RA but not in OA.

Thus, our results evidenced presence of IL-15Rα in synovial fluids and suggested that its pro-inflammatory effect could be related to induction of IL-6.