Electrophilic nitro-fatty acids suppress allergic contact dermatitis in mice.

BACKGROUND: Reactions between nitric oxide (NO), nitrite (NO2-), and unsaturated fatty acids give rise to electrophilic nitro-fatty acids (NO2 -FAs), such as nitro oleic acid (OA-NO2 ) and nitro linoleic acid (LNO2 ). Endogenous electrophilic fatty acids (EFAs) mediate anti-inflammatory responses by modulating metabolic and inflammatory signal transduction reactions. Hence, there is considerable interest in employing NO2 -FAs and other EFAs for the prevention and treatment of inflammatory disorders. Thus, we sought to determine whether OA-NO2 , an exemplary nitro-fatty acid, has the capacity to inhibit cutaneous inflammation.

METHODS: We evaluated the effect of OA-NO2 on allergic contact dermatitis (ACD) using an established model of contact hypersensitivity in C57Bl/6 mice utilizing 2,4-dinitrofluorobenzene as the hapten.

RESULTS: We found that subcutaneous (SC) OA-NO2 injections administered 18 h prior to sensitization and elicitation suppresses ACD in both preventative and therapeutic models. In vivo SC OA-NO2 significantly inhibits pathways that lead to inflammatory cell infiltration and the production of inflammatory cytokines in the skin. Moreover, OA-NO2 is capable of enhancing regulatory T-cell activity. Thus, OA-NO2 treatment results in anti-inflammatory effects capable of inhibiting ACD by inducing immunosuppressive responses.

CONCLUSION: Overall, these results support the development of OA-NO2 as a promising therapeutic for ACD and provides new insights into the role of electrophilic fatty acids in the control of cutaneous immune responses potentially relevant to a broad range of allergic and inflammatory skin diseases.