Retinoic Acid Eases Arthritic Swelling

LOS ANGELES—A collaboration between scientists from China and the United States, including the University of Southern California (USC), have discovered all-trans-retinoic acid may help a certain kind of regulatory T cell better control inflammation in autoimmune diseases. Published in the Sept. 1 issue of the journal of Immunology (2010 Sep 1;185(5):2675-9), their in vitro investigation involved treating CD4+Foxp3+ regulatory T cells (nTregs) with all-trans retinoic acid(atRA). The nTregs treated with atRA appeared to better resist certain T-helper (Th) cells, which secrete certain cytokines that trigger inflammation. Treatment with atRA also appeared to help nTregs control Th cells even in the presence of interleukin-6 (IL6), which can contribute to disease pathogenesis in chronic inflammatory conditions; in fact, atRA decreased the expression and signaling of IL6 by nTregs. Researchers also transferred nTregs from arthritic mice treated with atRA, and the transplanted NTregs continued to suppress progression of collagen-induced arthritis. The researchers concluded nTregs treated with atRA show promise as “a novel treatment strategy to control established chronic immune-mediated inflammatory diseases.”