Current Grants and Major Projects
Identifying Mechanisms of Lung Toxicity from Skin exposure to Vesicants (2026)
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.
Targeted Therapeutic Approaches to Counteract Toxicity from Phosgene Oxime Skin Exposure (2019)
During World War II, Phosgene Oxime (CX; dichloroform oxime) is a potent chemical weapon that poses a threat of exposure; both, alone and with other chemical agents. It is an urticant or nettle agent grouped with vesicating agents due to similar damaging properties; although, it causes more severe damage than other vesicants due to its highly reactive nature. Even though it is the most notorious vesicant with special military and terrorist interests, it is one of the least studied chemical warfare agents with no specific antidote available. Information on its effect on human dermal tissue and absorption is limited, and its mechanism of action is unknown. To overcome these limitations, our completed and ongoing studies are directed towards the development of a relevant cutaneous CX exposure mouse injury model to elucidate the mechanisms of skin damage by CX and examine systemic toxic effects of CX to identify novel therapeutic targets. The results from our completed studies demonstrate that mast cells could be important players in CX-induced toxicity. The toxicity response and skin urticaria from CX resembles anaphylactic reaction and urticaria from allergic reactions, which involves an inflammatory response mainly due to mast cell activation. Data from our published and completed studies in SKH-1 hairless mice show that CX cutaneous exposure causes mast cell degranulation and release of mediators including histamine and tryptase, pro-inflammatory cytokines, and an inflammatory response in the skin tissue associated with edema, erythema, necrosis, urticaria and blanching. CX cutaneous exposure in mice also caused vasculature dilation and blood congestion in multiple organs resulting in systemic toxicity, and decrease in breath and heart rate, temperature drop and mortality. These symptoms were similar to anaphylaxis (potentially lethal multisystem allergic reaction with acute respiratory and cardiovascular compromise leading to unconsciousness, shock and mortality), which is a result of sudden systemic release of mediators from mast cells. Based on our published and recently obtained data under the current R21 grant, we hypothesize that mast cell activation and associated release of mediators are the major events following CX cutaneous exposure which cause inflammatory pathway activation as well as lethal allergic reaction, and that these would be novel targets for therapeutic intervention to mitigate CX-induced skin morbidity and mortality. To test this hypothesis, the specific aims proposed are: 1. To further establish mast cells as key players and molecular targets in CX toxicity by employing mast cell deficient mice; and 2. To test the efficacy of FDA approved therapies that can counteract CX-induced morbidity and mortality from cutaneous exposure in mice, mainly by targeting mast cell activation and release of histamine. We believe that outcomes from above aims will help establish that mast cell activation and mediators like histamine are novel targets for therapeutic intervention, and identify an FDA approved targeted therapeutic strategy that can target these to counteract toxicity from CX cutaneous exposure.
Treatment Strategies for ocular toxicity from chloropicrin (2022)
Chloropicrin (Trichloronitromethane, CP), currently used as a soil fumigant and pesticide, was employed during World War I as a tear gas and choking agent and remains a potential agent for chemical terrorism. Its exposure causes severe ocular injury, especially to the corneal tissue; however, mechanisms of its injury are not well-defined and effective targeted treatments are elusive. The major goal of this application is to identify a novel targeted therapeutic approach, which can effectively mitigate acute and long-term ocular injuries from CP exposure, with a potential to be further tested against ocular injuries from other toxic chemical exposures. Data from our studies in corneal epithelial cells and ex vivo rabbit cornea demonstrate increased levels of nuclear erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), a critical target enzyme downstream of Nrf2, suggesting that the Nrf2 pathway, a key antioxidant and cytoprotective system, could be activated following CP exposure. Under this application, we propose to further asses the role of the Nrf2 pathway under CP-induced ocular injury using Nrf2 knockout (KO) mice. Nrf2 activity triggers cellular protective mechanisms against oxidative stress and inflammatory responses and is reported as a key target of new approaches for treating various oxidative stress-related ocular diseases/injuries. Hence, employing Nrf2 activators may be a novel approach for the treatment of ocular injuries due to CP exposure. Chemical ocular injury causes hypoxia that leads to tissue damage; oxygen therapy is reported to improve tissue preservation and enhance wound healing to mitigate ocular chemical and thermal burns. Our preliminary data shows the therapeutic potential of supersaturated oxygen emulsion (SSOE) therapy in reversing CP-induced acute toxicity in HCE cells and ex vivo rabbit corneas. Our hypothesis is that the Nrf2 signaling pathway is a key mediator in protecting against CP-induced corneal injury; activation of the Nrf2 pathway can inhibit CP-induced oxidative stress and inflammation, and simultaneous treatment with SSOE can increase tissue oxygen levels to improve tissue preservation and enhance wound healing, leading to a novel and more effective treatment strategy against CP- induced acute and long-term ocular injury. To test this hypothesis, the proposed aims are: Aim 1. To develop a CP-induced ocular injury model in mice and determine if the Nrf2-ARE pathway is a key mediator in CP- induced ocular injury using wild type and Nrf2 KO mice. Aim 2. To evaluate the efficacy of Nrf2 activators and supersaturated oxygen emulsion alone, or in combination, to identify an effective therapeutic strategy against CP-induced ocular injury. We anticipate that the outcomes from the above aims will establish a useful mouse ocular injury model with CP and ascertain if the Nrf2 signaling pathway is a novel target for therapeutic intervention to counteract CP-induced ocular injury. Successful completion of this project will identify a novel therapeutic approach that can more effectively mitigate acute and chronic ocular injuries from CP and lead to a better understanding of the mechanisms of CP-induced ocular toxicity.
Mast Cell Activation as a Common Mechanism of Pulmonary Toxicity by chemical Agents (2025)
The Department of Homeland Security considers numerous chemical threat agents a concern for human health, specifically those that are acute pulmonary toxicants. In acute lung injury, inflammation is critical thus we propose that inflammation is a common mechanism of lung injury caused by chemical threat agents due to mast cell activation. We and others have shown mast cell activation to be critical in response to a wide range of xenobiotics including nitrogen mustard, ozone, diesel exhaust, insecticides/herbicides, cigarette smoke, heavy metals and nanoparticles as examples. Mast cells are a logical cell type to study in pulmonary injury from chemical threat agents due to 1) their location at interfaces with the external environment (e.g., lung); 2) their roles as sensors for initiating both innate and adaptive immune responses; and 3) their immediate response to danger signals through degranulation and release of preformed mediators. We have demonstrated that mast cell activation is a major contributor to the pulmonary toxicity and inflammation observed following nitrogen mustard (NM), chloropicrin and formaldehyde exposure. Currently there are few shared mechanisms which have been identified between these chemical threat agents, thus identification of common pathways would be beneficial for future therapeutic targets and biomarkers of exposure. Here, we propose two specific aims to provide confirmatory data on the role of mast cells in pulmonary injury resulting from exposure to chloropicrin (fumigant/pesticide) and formaldehyde (industrial chemical). Our overall hypothesis is that activation of mast cells is a common initiating step in recruitment and propagation of immune responses in the lung across several classes of chemical threat agents. In aim 1, we will Confirm the in vivo contribution of mast cells to pulmonary injury and inflammation resulting from chemical threat agents in Cpa3-Cre mast cell deficient mice. In aim 2 we will Determine role of mast cells in lung injury using a novel human lung-on-a-chip model where we have incorporated mast cells. Collectively, our goal is to establish activation of mast cells as a common mechanism across several chemical classes which are linked with pulmonary toxicity. Confirmation of these findings will allow identification and development of novel therapeutic targets for prevention and/or treatment of the effects of these potential chemical warfare agents through targeting of mast cells.
Elucidate Mechanisms to Identify Therapeutic Targets and Targeted Therapeutic Approaches to Counteract Toxicity from Phosgene Oxime Skin Exposure
Vesicating chemical agents cause severe respiratory, skin, and ocular injuries. Phosgene Oxime (CX; dichloroform oxime), is an urticant or nettle agent grouped with vesicating agents; although, it causes more severe damage than other vesicants, owing to its highly reactive nature. Stockpiled during World War II, CX is a potent chemical weapon that poses a threat of exposure; both, alone and with other chemical agents. In March 2019, the FBI entered an Oklahoma City apartment and found massive amounts of manufactured CX, which could cause serious health hazard and chemical emergency. It is rapidly absorbed through the skin leading to an immediate skin irritation, erythema, blanching (whitening), itching hives, necrosis, and severe systemic toxicity and mortality. Even though it is one of the most notorious chemical toxicants, it is one of the least studied chemical warfare agents with no specific antidote available. To overcome these limitations, our completed and ongoing studies are directed towards the development of a relevant cutaneous CX exposure mouse injury model to elucidate the mechanisms of CX toxicity. We are studying if mast cell activation and mediators like histamine are novel targets for therapeutic intervention to counteract toxicity from CX cutaneous exposure. We will further investigate whether blocking these targets with antihistamines and/or epinephrine in established mouse toxicity models, will assist to mitigate CX-induced skin morbidity and mortality.
Mast Cells in Sulfur Mustard Exposure: Novel targets for modulation to develop therapies against the long-term health effects in Gulf War Veterans
It is reported that during the Gulf War (GW; 1990-1991) exposure of veterans to chemicals like pyridostigmine bromide, pesticides, oil well fires, sarin and mustard gas or their combinations are most likely associated with Gulf War Illness (GWI). Our research is focused on identifying a novel immune mechanism of sulfur mustard [mustard gas; bis(2-chloroethyl) sulfide); SM] pathophysiological effects that could contribute to GWI. Mast cells are well known to contribute to allergic inflammatory diseases and also have wide ranging effects on many physiological systems that are affected in Gulf War veterans illness. Importantly, there are clinical therapeutics targeted towards mast cells and their products that could be beneficial in GWI patients, therefore, we aim to uncover a novel mechanism of SM toxicity (using its surrogate nitrogen mustard) that is mediated by mast cells and which could also be applicable to other chemical exposures in GWI.
Elucidating the role of aryl hydrocarbon receptor in polycyclic aromatic hydrocarbons-induced skin inflammatory diseases for targeted treatment strategies
The prevalence of skin inflammatory diseases such as atopic dermatitis (AD) and psoriasis is increasing worldwide affecting lives of millions of individuals. Exposure to environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs; major environmental pollutant in automobile exhaust, cigarette smoke, many foods and industrial waste) are reported to contribute to the prevalence and exacerbation of these skin inflammatory diseases. Although dysregulated immune responses appear to be the root cause of disease, the mechanisms by which PAHs initiate skin inflammatory diseases remain unclear. Emerging evidence suggests that the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, is an important player in skin integrity and skin immunity and its activation can modulate inflammatory skin lesions. The objective of this study is to investigate the pathophysiology and metabolic signature (metabolomics) in mouse skin following polycyclic aromatic hydrocarbon (PAH) exposure and explore Aryl hydrocarbon receptor (AhR)-related signaling pathways in skin inflammatory disease psoriasis and which can exacerbate from PAH exposure.
Toxicity mechanisms in the cornea from ocular exposure to toxic chemicals and treatment strategies
- Elucidate cornea toxicity due to nitrogen mustard (NM) and chloropicrin (CP) and other toxic chemicals’-induced oxidative stress and inflammation, which would help identify specific biomarkers and pathways in vesicating agent/pesticide and potential warfare agents’ -induced ocular injury.
- Utilize supersaturated oxygen emulsion treatment and /or anti-inflammatory agents in conjunction with an eye cup/wound chamber to preserve tissue and improve outcomes following ocular trauma.