Methylation of IFN-γ in sulfur mustard-exposed patients

Introduction: IFN-γ is one of the most important cytokines in the development of chronic inflammatory diseases such as asthma and COPD. The IFN-γ promoter methylation at CpG islands could be altered by various chemical and toxic substances which may have a role in the incidence of chronic pulmonary diseases and its severity. Thereby, the present study was aimed to evaluate the effect of sulfur mustard gas on the methylation status of IFN-γ gene promoter and its correlation with the severity of pulmonary disease in chemical veterans with delayed pulmonary complications.   Methods: 46 sulfur mustard-exposed individuals with mild-moderate pulmonary complications, 45 with severe pulmonary complicationsand 41 unexposed individuals as a control group participated. The quality and quantity of extracted DNA were assessed by the nanodrop machine. After treatment with bisulfite, the methylation of IFN-γ gene promoter was evaluated by methylation-specific PCR.   Results: The methylation of IFN-γ gene promoter showed a significant increase in exposed-patients with mild to moderate pulmonary complications and a significant reduction in exposed-patients with severe pulmonary complications compared to the control groups. The levels of spirometric parameters were significantly higher in individuals with Methylated DNA compared with those with unmethylated DNA.   Conclusion: It could be suggested that hyper-methylation of IFN-γ gene promoter and probable changes in IFN-γ gene expressionhave a positive effect on lung function in SM-exposed individuals.