Identifying mechanisms of lung toxicity from skin exposure to vesicants

Mustard vesicating agents sulfur mustard (SM) and nitrogen mustard (NM) are alkylating vesicants that cause severe skin, eye, systemic and lung toxicity. Phosgene oxime (CX), an urticant or nettle agent, is the least studied but most potent vesicant with instantaneous toxic effects and penetration that poses a threat of mortality and long-term morbidity. The secondary lung toxicity and its mechanism from dermal route of exposure to these vesicants due to their systemic effects have not been explored and there are no approved and effective therapies to treat such injuries that can lead to mortality and long-term effects. Recent novel findings from our laboratory demonstrate that acute dermal exposure of mice to mustard vesicant NM or nettle vesicant CX leads to the development of not only acute skin but also lung injury with qualitatively similar pulmonary lesions characterized by acute, diffuse intramural edema and hemorrhage. These pulmonary toxic lesions were accompanied by an increase in mast cell degranulation and inflammatory cytokines like Interleukin (IL) 33 indicating that mast cell activation and immune cell recruitment could be a mutual mechanism of vesicant lung injury from their skin exposure. Overall, our studies have implied a role of mast cells in vesicant NM inhalation-related lung injury (published) and CX dermal exposure related skin injury; however, mast cell activation and related signaling in lung injury from their dermal exposure is not explored. Also, there are no reported studies on CX lung toxicity and, hence, these studies are novel and critical area of research. This proposal aims to further establish the role of mast cells and delineate related mechanism(s) of acute and long-term lung toxicity from both mustard and nettle vesicating agents following their dermal exposure in mice. We hypothesize that dermal NM or CX exposure causes systemic toxicity induced lung injury, and mast cells significantly contribute to the mechanism of toxicity. To test this hypothesis, the proposed specific aims are: SPECIFIC AIM 1: Establish the role of mast cells in lung toxicity from acute dermal exposure to vesicating agents. We will use mast cell deficient (B6.Cg-KitW-sh/HNihrJaeBsmJ; MCD) and wild-type C57BL/6 (WT) mice to examine the role for mast cells in vesicant related lung injury following their dermal exposure. Following acute CX or NM cutaneous exposures, we will conduct time-response studies from 2h up to 3 months to characterize the acute and long-term lung toxicity in both the WT and MCD mice. SPECIFIC AIM 2: Determine and compare the mast cell associated mechanisms of lung injury from acute dermal exposure to vesicating agents. We will utilize the BALF, blood plasma samples and lung tissues from Aim 1 studies, for both NM and CX exposures, to determine the a) bioactive lipid profiles and b) differential transcriptome profiling and changes in immune cells (Visium Spatial Gene Expression) with adverse pulmonary morphology in WT and MCD mice. These studies will establish if mast cell activation and related signaling parallel in skin, systemic and lung injury from mustard and nettle vesicating agents’ dermal exposure with a goal to identify novel broad-spectrum treatment strategies. Project Number: 1R01ES036491-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Environmental Health Sciences (NIEHS) | Principal Investigator: Neera Tewari-Singh (+1 co-PI) | Institution: HENRY FORD HEALTH + MICHIGAN STATE UNIVERSITY HEALTH SCIENCES, EAST LANSING, MI | Award Amount: $1,403,056 | Activity Code: R01 | Study Section: Special Emphasis Panel[ZES1 LWJ-W (CR)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11197265