cis-Urocanic Acid Attenuates Acute Dextran Sodium Sulphate-Induced Intestinal Inflammation

Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
PLoS ONE (Impact Factor: 3.23). 10/2010; 5(10):e13676. DOI: 10.1371/journal.pone.0013676
Source: PubMed


On exposure to sunlight, urocanic acid (UCA) in the skin is converted from trans to the cis form and distributed systemically where it confers systemic immunosuppression. The aim of this study was to determine if administration of cis-UCA would be effective in attenuating colitis and the possible role of IL-10. Colitis was induced in 129/SvEv mice by administering 5% dextran sodium sulfate (DSS) for 7 days in drinking water. During this period mice received daily subcutaneously injections of cis-UCA or vehicle. To examine a role for IL-10, 129/SvEv IL-10(-/-) mice were injected for 24 days with cis-UCA or vehicle. Clinical disease was assessed by measurement of body weight, stool consistency, and presence of blood. At sacrifice, colonic tissue was collected for histology and measurement of myeloperoxidase and cytokines. Splenocytes were analyzed for CD4+CD25+FoxP3+ T-regulatory cells via flow cytometry. Murine bone-marrow derived antigen-presenting cells were treated with lipopolysaccharide (LPS) ± UCA and cytokine secretion measured. Our results demonstrated that cis-UCA at a dose of 50 µg was effective in ameliorating DSS-induced colitis as evidenced by reduced weight loss and attenuated changes in colon weight/length. This protection was associated with reduced colonic expression of CXCL1, an increased expression of IL-17A and a significant preservation of splenic CD4+CD25+FoxP3+ T-regulatory cells. cis-UCA decreased LPS induced CXCL1, but not TNFα secretion, from antigen-presenting cells in vitro. UCA reduced colonic levels of IFNγ in IL-10(-/-) mice but did not attenuate colitis. In conclusion, this study demonstrates that cis-urocanic acid is effective in reducing the severity of colitis in a chemically-induced mouse model, indicating that pathways induced by ultraviolet radiation to the skin can influence distal sites of inflammation. This provides further evidence for a possible role for sunlight exposure in modulating inflammatory disorders.

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    • "Both have shown to have anti-inflammatory effects both in vivo and in vitro [14] [15] [16]. In the case of cis-UCA, attenuation of experimental colonic epithelial damage, induced by dextran sodium sulfate (DSS), has recently been obtained in vivo [17]. Urocanic acid (UCA) derivatives, studied here, are natural and synthetic derivatives of UCA. "
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    • "Interestingly, cis‐urocanic acid (produced after UV radiation) is well known to be an immune‐ suppressor (Gibbs et al., 2008) and it has been considered for the topical treatment of inflammatory and autoimmune diseases of skin (Ong, 2009). A recent publication showed how cis‐urocanic acid can also influence distal sites of inflammation, reducing the severity of colitis in a mouse model (Albert et al., 2010). These considerations can provide a scientific explanation to many old anecdotes on the benefits of sun exposure in asthma treatment (Gorman et al., 2010). "
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