Nitrogen Mustard-Induced Ex Vivo Human Cornea Injury Model and Therapeutic Intervention by Dexamethasone

Abstract

Sulfur mustard (SM), a vesicating agent first used during World War I, remains a potent threat as a chemical weapon to cause intentional/accidental chemical emergencies. Eyes are extremely susceptible to SM toxicity. Nitrogen mustard (NM), a bifunctional alkylating agent and potent analog of SM, is used in laboratories to study mustard vesicant-induced ocular toxicity.Previously, we showed that SM-/NM-induced injuries (in vivo and ex vivo rabbit corneas) are reversed upon dexamethasone (DEX) treatment, an FDA approved, steroidal anti-inflammatory drug. Here, we optimized NM injuries in ex vivo human corneas and assessed DEX efficacy. For injury optimization, one cornea (randomly selected from paired eyes) was exposed to NM: 100 nmoles for 2 h or 4 h, and 200 nmoles for 2 h, and the other cornea served as a control. Injuries were assessed 24 h post NM-exposure. NM 100 nmoles exposure for 2 h was found to cause optimal corneal injury (epithelial thinning [~69%]; epithelial-stromal separation [6-fold increase]). In protein arrays studies, 24 proteins displayed ≥40% change in their expression in NM exposed corneas compared to controls. DEX administration initiated 2 h post NM exposure and every 8 h thereafter until 24 h post-exposure reversed NM-induced corneal epithelial-stromal separation [2-fold decrease]). Of the 24 proteins dysregulated upon NM exposure, 6 proteins (DLL1, FGFbasic, CD54, CCL7, endostatin, ERBB4) associated with angiogenesis, immune/inflammatory responses, and cell differentiation/proliferation, showed significant reversal upon DEX treatment (Student's t-test; p≤0.05). Complementing our animal model studies, DEX was shown to mitigate vesicant-induced toxicities in ex vivo human corneas.

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“…FGFs are widely present in various organisms and have crucial roles in cellular processes through paracrine, autocrine, or endocrine functions. They are involved in embryonic development, angiogenesis, tissue homeostasis, wound repair, and cancer genesis and development [ 38 ]. During embryonic development, FGF regulates cell proliferation, differentiation, and migration, contributing to morphogenesis.…”

“…During embryonic development, FGF regulates cell proliferation, differentiation, and migration, contributing to morphogenesis. In adults, FGF serves as a homeostatic factor, regulating tissue repair, wound healing, nervous system control, and tumor angiogenesis [ 38 ]. IL-2, a growth factor related to T cells, has the ability to enhance the killing activity of NK cells and stimulate the production of immunoglobulins by B cells [ 39 ].…”

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“…While dynasore shows superior cytoprotection, mdivi-1 emerged as a potential countermeasure against NM-induced epitheliopathy, offering insights into distinct pathways of corneal epitheliopathy for novel therapeutic strategies for dry eye and chemical exposure. In another study on mustard’s ocular toxicity, Agarwal and team mitigated injuries induced by NM in an ex vivo human cornea model and evaluated the efficacy of dexamethasone in reversing these injuries ( Mishra et al, 2024a ). Dexamethasone, administered 2 hours post NM exposure, successfully mitigated NM-induced corneal injuries, suggesting its potential as a therapeutic intervention to counter vesicant-induced ocular toxicities in chemical emergencies.…”