1095 Evaluating IKK 16 and ACHP as anti-inflammatory agents for treatment of skin inflammation: In vitro and in vivo

Abstract

The skin faces the greatest exposure to environmental agents which contribute to the skin’s susceptibility to developing acute and chronic inflammation. NFκB and its upstream modulators, regulate many inflammatory mediators that contribute to inflammation. In the present study, we examined the anti-inflammatory properties of two P-gp substrates that are inhibitors of IêB kinase (IKK), ACHP and IKK 16, and evaluated their potential as topical anti-inflammatory drugs through inhibition of NFκB signaling. P-gp, or MDR1, is expressed in human and mouse skin, and we hypothesized that P-gp substrates would make good candidates for transdermal delivery of topically-applied drugs because P-gp can facilitate their absorptive transport into the systemic circulation. An Pgp-mediated efflux assay revealed both IKK 16 and ACHP were high affinity P-gp substrates/inhibitors, and IKK 16 and ACHP completely blocked nuclear translocation of NFκB in human and murine keratinocytes challenged with IL-1a. Pretreating primary keratinocytes with IKK 16 or ACHP blocked cytokine gene expression induced by IL-1a, TNFa, and PMA in a dose-dependent manner. This indicated that both drugs block the inflammatory signaling pathway downstream of NFκB activation in vitro. However, in vivo studies showed topical ACHP treatment, but not IKK 16, blocked PMA induced cytokine expression in K5-PKCa mice, a mouse skin inflammation model. Further studies revealed that the topical application of ACHP reduced both skin inflammation induced by Imiquimod and tumor formation in DMBA initiated and PMA promoted K5-PKCa mice. In this model ACHP application was not effective at eliminating established tumors. Pretreatment of ACHP also attenuated cytokine expression induced by UV irradiation of FVB mice. These data indicate that ACHP is a potential candidate for a topical drug used for treating skin inflammation that is mediated by NFκB signaling.