Accelerating Inflammation Resolution to Counteract Chemical Cutaneous Injury

Chemical exposure to vesicants such as sulfur mustard (SM), and electrophilic riot control agents such as 2-chlorobenzalmalononitrile (CS) tear gas agent, cause strong cutaneous inflammation. Classical anti-inflammatory treatments have focused on interference with target initiation and maintenance of inflammation, with mixed outcomes. Inflammation is broadly classified into three temporal phases, initiation, amplification and maintenance, and resolution. Resolution of inflammation was thought to be a passive process but the recent body of literature shows that resolution is an active process and is mediated by fatty acid-derived mediators (specialized pro-resolving mediators, SPMs). We hypothesized that accelerating resolution phase of inflammation may attenuate the exaggerated inflammatory response following chemical threat exposure, leading to decreased morbidity and improved recovery. In this study, SPMs, such as Resolvin D1 (RvD1) and Resolvin D2 (RvD2), were administered to mice at nanogram doses post-exposure to an SM analog, 2-chloroethyl-ethyl-sulfide (CEES) or CS tear gas agent. SPMs decreased edema (ear thickness and punch biopsy weights), pro-inflammatory cytokines (IL-1β, CXCL1/KC, MIP2) and protease marker (MMP-9), and vascular leakage (determined by IRDye 800 CW PEG) while improving histopathology in cutaneous chemical injury mouse models. These results support our hypothesis and pave the way for SPMs for further development as potential medical countermeasures for chemical threat agents-induced skin injuries.