Countermeasure protocols of mustard decontamination and neutralization may protect exposed surfaces of the skin, eyes, and lungs when administered immediately after exposure. However, this may not be adequate to address the delayed onset of myelosuppression and disrupted hematopoiesis associated with mustard exposure. The impact of the current proposal is to provide a comprehensive countermeasure regimen that addresses both the acute and delayed detrimental effects of mustard exposure mediated by acute skin inflammation and the innate immune system, specifically macrophage hyper-activation. NM-mediated tissue injury of the skin results in rapid epidermal disruption and vascular leakage resulting edema and painful inflammation. Following the initial injury is an influx of activated inflammatory monocytes and macrophages. Release of macrophage-mediated soluble signaling molecules promotes a pro- inflammatory state which amplifies other cytotoxic activities including release of reactive nitrogen species iNOS, reactive oxygen species, and induction of proteolytic enzymes. Furthermore, these activated iNOS- producing macrophages are critically involved in mediating and exacerbating systemic toxicities. We propose to use a multidisciplinary translational approach to modulate skin inflammation and macrophage activity using in vivo techniques in mouse and human studies. We will study the effect of spironolactone and bisphosphonates (BPs) in combination with vitamin D to inhibit the production of pro- inflammatory factors including; TNFα, and iNOS in the skin and in activated macrophages. These drugs have been in clinical use for many years with known safety and toxicity profiles. Spironolactone is a potassium- sparing diuretic (water pill) that has been safely used for five decades to treat essential hypertension, fluid overload and edema in patients with congestive heart failure and other kidney pathologies. While much information has been accumulated on the physiopathology of spironolactone on the mineralocorticoid receptor (MR) and the adrenal glands, the effect of MR ligands on non-classical targets such as the skin has found new and exciting potential applications. We hereby propose that spironolactone being a weak diuretic has sufficient capacity to reduce water content of edematous skin lesions as a way to accelerate wound healing. The use of spironolactone may have benefits in limiting edema and painful skin inflammation. BPs are medications that has been used for over 40 years. In addition to the skeletal bones, these drugs deposit in the skin, liver, spleen, and bone marrow which aligns with our research interest as they represent organs and tissues that may be reservoirs and/or targets for activated macrophages. Furthermore, BPs deposit and have long-lasting effects in the tissue. We propose to use BPs in conjunction with high dose vitamin D3 as countermeasures to NM exposure. Lastly, as a systemic treatment for the most toxic exposure, we p...