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Biotech / Medical : Indications -- Psoriasis/Chronic Inflammation -- Ignore unavailable to you. Want to Upgrade?

To: nigel bates who wrote (622)	8/20/2013 1:39:37 PM
From: scaram(o)uche	Respond to of 631

Niiiiiiiiiiiiiiiiice! Need to watch the various jak inhibitors. This was interesting..... Biochem Biophys Res Commun. 2012 Feb 10;418(2):234-40. doi: 10.1016/j.bbrc.2011.12.156. Epub 2012 Jan 9. Low dose CP-690,550 (tofacitinib), a pan-JAK inhibitor, accelerates the onset of experimental autoimmune encephalomyelitis by potentiating Th17 differentiation. Yoshida H, Kimura A, Fukaya T, Sekiya T, Morita R, Shichita T, Inoue H, Yoshimura A. Department of Microbiology and Immunology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan. Th17 cells, which have been implicated in autoimmune diseases, require STAT3 signaling activated by IL-6 or IL-23 for their development. Other Th1 and Th2 cytokines such as IL-2, IFN-? and IL-4 strongly suppress Th17 development. Recently, CP-690,550 (tofacitinib), originally developed as a JAK3 inhibitor, has been shown to be effective in phase III clinical trials of rheumatoid arthritis and collagen-induced arthritis (CIA) models, but the precise mechanism of the effect, especially with respect to Th17 cells, is poorly understood. To our surprise, a low dose CP-690,550 was found to accelerate the onset of experimental autoimmune encephalomyelitis (EAE) at a concentration that suppressed CIA. At an early stage after immunization, more IL-17 production was observed in 15mg/kg body weight CP-690,550-treated mice than in untreated mice. In vitro, CP-690,550 inhibited both Th1 and Th2 development, while promoting Th17 differentiation at 10-50nM concentrations. Enhancement of Th17 by CP-690,550 is probably due to suppression of IL-2 signaling, because anti-IL-2 antibodies cancel the Th17-promoting effect of CP-690,550. CP-690,550 selectively inhibited IFN--induced STAT1, IL-4-induced STAT6 and IL-2-induced STAT5 at 3-30nM, while suppression of IL-6-induced STAT3 phosphorylation required a concentration greater than 100nM. In HEK293T cells, CP-690,550 less effectively suppressed JAK1-mediated STAT3 phosphorylation compared with JAK3. These results suggest that CP-690,550 has a different effects among JAKs and STATs, thereby affecting helper T cell differentiation, and murine autoimmune disease models.