Lewisite has been identified as a potential threat chemical which could be used in chemical warfare. Topical exposure to lewisite results in cutaneous blistering and inflammation, which may be severe and painful. In this application, we will test the hypothesis that lewisite, by penetrating skin, ruptures the cutaneous barrier functions as a consequence of disruption of proteins associated with tight junctions and water/glycerin transport. These effects are mediated via activation of hippo signaling pathway, FAK kinases, ubiquitin ligases, proteases such as Cathepsin, and other lysozymal proteases. The acute inflammation is mediated through the activation of unfolded protein response (UPR) signaling triggered by arsenic-dependent reactive oxygen species (ROS) production and activation of DNA damage response signaling. Crosstalk between these intricate signaling pathways results in the pathogenesis of painful blisters and inflammation. Blocking these molecular targets by small molecules may intercept these effects. Aim 1 will investigate the effects of lewisite on disruption of skin barrier function and blistering by studying its effects o tight junction proteins such as claudins, occludin, zonula occludens (ZO), etc. in epidermis. In addition, proteins involved in the regulation of water/glycerin transport, the aquaporins, will be studied. The effects of lewisite on acute cutaneous inflammatory response will also be investigated by determining the kinetics of inflammatory responses and, at their peak, assessing hyperplasia and inflammatory cell infiltration. Then, we will assay the pro-inflammatory mediators, IL-6, interferon-?, prostaglandin E2, ROS, RNS (including NO) etc. using skin biopsies from lewisite- treated Ptch1+/-/SKH-1 hairless mice. We will determine whether lewisite-modulated UPR signaling regulates these pro-inflammatory effects. In Aim 2, we will screen the effectiveness of dietary and synthetic test agents on biomarkers depicting barrier function, blistering, and inflammation. The two most efficacious agents chosen from a series of dietary and synthetic chemicals based on their known potential to block molecular targets involved in barrier function/blistering/inflammation will be evaluated further in this aim. After defining the therapeutic window, kinetics of action, ability to reverse lewisite-induced molecular changes and underlying cutaneous inflammation/blistering by these select agents will be assessed. Thus, this proposal will employ a novel murine model to unravel the molecular mechanism of lewisite in order to develop mechanism-based antidotes/therapy. Small molecule candidate lead-compounds can easily be taken to further murine studies by submitting a prospective application (R01 or U01) and finally to clinical trials based on their known toxicity profile and use for other conditions. The outcome of the proposed research is likely to have a significant impact on human health protection in the event of mass population exposure to war threat chemicals. PUBLIC HEALTH RELEVANCE: This proposal unravels the molecular mechanisms involved in the pathogenesis of lewisite- induced painful cutaneous blistering/inflammation and develops small molecules that can attenuate these effects. In this regard, the focus of this research is on the amelioration of disrupted tight and coherens junction and water/glycerin transport proteins which may be involved in blistering/inflammation. The outcome of the proposed research is likely to have a significant impact on human health protection in the event of mass population exposure to war threat chemicals.