The mitochondrion has a substantial role in innate immunity and inflammasome signaling pathways. Sulfur mustard (SM) induces toxicity in cytoplasmic organelles. We aimed to evaluate the potential therapeutic effect of curcumin on the toxicity of SM analog through measuring gene expression levels of mitochondrial dynamics followed by induction of the inflammasome signaling pathway. After the treatment of pulmonary epithelial cell line (A549) by 2-chloroethyl ethyl sulfide (CEES) (2500 mM) for 48h, the transcriptional activity of mitochondrial fission and fusion genes such as dynamin-related protein 1 (Drp1), mitochondrial fission 1 protein (Fis1), mitofusin-1 (Mfn1), mitofusin-2 (Mfn2), and Dominant optic atrophy (Opa1) and inflammasome pathway genes including absent in melanoma 2 (AIM2), NLR family containing protein 3 (NLRP3), and Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) was measured. Furthermore, the inhibitory effect of curcumin (160 mM) concurrent with SM analog on the expression level of mitochondria and inflammasome genes was investigated. CEES was able to over-express the fission, fusion (Drp1 ~ 8, Fis1 4.5, Mfn2 15, and Opa1 16-fold) and inflammasome genes (AIM2, NLRP3,  8 and 6-fold, respectively), whereas Mfn1 was significantly decreased (0.5-fold) and a not statistically significant decrease was observed in the ASC gene. Curcumin could modulate the effect of CEES, mitigate the expression of fission, fusion, and inflammasome genes exceedingly. However, a major increase in the repairer fusion gene (Mfn1, 6-fold) and complete suppression of the ASC gene were the outcomes of using the curcumin. In conclusion, we suggest curcumin alleviates the disturbance of mitochondrial dynamics and downregulates the inflammasome genes exposed to the CEES.

Sulfur Mustard (SM) induces cell injury via exerting oxidative stress, protease-anti protease imbalance, and inflammation. Inflammasome as one part of innate immunity has a critical role in the recognition of cell injuries and the initiation of the inflammation process by releasing IL-1β. Hence, the present study investigated the effects of the sub-lethal doses of 2-chloroethyl ethyl sulfide (CEES) as SM analog on the gene expression level of inflammasome-related genes as well as the potential protective effects of curcumin on this process. The effects of sub-lethal doses (500, 1000, and 2500 mM) of CEES on pulmonary epithelial cell line (A549) were determined at various time points (12, 24, and 48 h). Following the treatment of cells with CEES, the kinetic alterations of the expression levels of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB1), NLR family pyrin domain containing 1 (NLRP1), Caspase-1 (Casp1), and Interleukin-1β (IL-1β)  genes were analyzed; using real-time PCR. In addition, the concurrent protective effects of different doses of curcumin (20, 40, 80, and 160 mM) on modulating the effects of CEES were studied. Although it was found that the lowest sub-lethal dose of CEES (500 mM) was able to up-regulate the inflammasome-related genes, the maximum alterations occurred 48 h after the treatment with the higher sub-lethal dose (2500 mM) of CEES. The maximum alteration occurred in Casp1 (38 fold), IL-1β (19 fold), and NLRP1 (~4 fold) genes (p<0.0001). However, the NF-ĸB gene expression level did not alter following CEES exposure. Even though low doses of curcumin (20, 40, and 80 mM) were able to down-regulate the studied genes, it was found that the treatment of cells with 160 mM of curcumin for 48 h was able to normalize the expression level of all genes. The present study concludes that curcumin as an anti-inflammatory agent may have beneficial immunomodulatory effects following CEES exposure.