Investigating the role of mast cell activation by nitrogen mustard in lung toxicity

Abstract

Abstract Chemical warfare agents (CWA) were widely used during the Gulf War (1990–1991) and as a result left ~30% of veterans suffering from Gulf War Illness (GWI). The vesicating agent, sulfur mustard (SM) is one of the most noteworthy CWA used during this time. Prior research has demonstrated that SM targets the bone marrow and has the potential to influence immune cells. In the skin, SM is reported to induce mast cell degranulation. Therefore, the aim of this study was to determine if nitrogen mustard (NM) (a surrogate for SM) promotes activation of mast cells. Using murine bone marrow derived mast cells (BMMCs) we assessed activation through degranulation, eicosanoid expression, and pro-inflammatory cytokine production. While NM exposure (1μM–50μM) did not result in mast cell degranulation, we observed a 30-fold increase of cyclooxygenase-2 (COX-2) mRNA production at 10μM at 6h. In addition, IL-6 production by BMMCs post 24h exposure to NM demonstrated a dose dependent increase indicative of late phase activation. To further demonstrate a pivotal role for mast cells in NM exposure, we compared the effects of NM exposure on lung pathology between C57BL/6 and B6.Cg-KitW-sh/ HNihrJaeBsmJ (mast cell deficient) mice. Significant lung injury was observed in C57BL/6J following NM exposure at 72 hrs as indicated by H&E staining. In contrast, significantly less injury was observed in mast cell deficient mice. Similarly, increases in total protein and IL-6 was observed in C57BL/6 mice but not mast cell deficient mice. These results suggest that mast cells play a prominent role in the injury induced by NM and may contribute to symptoms observed in GWI.