Cigarette smoking affects microRNAs and inflammatory biomarkers in healthy individuals and an association to single nucleotide polymorphisms is indicated

Background: Cigarette smoke induces inflammation and remodels immune response. Genetic and epigenetic alterations might be involved in the pathogenesis of smoking related diseases. In this study, we investigated the effect of smoking on systemic inflammation biomarkers and epigenetic changes at microRNA (miRNA) expression level. We also examined if the levels of inflammatory biomarkers were associated with selected single nucleotide polymorphisms (SNPs).

Method: From 39 smokers and 101 non-smokers, levels of total white blood cells (WBCs) and its subpopulations, plasma cytokines/chemokines/proteins and miRNAs were analysed. For three biomarkers, C-reactive protein (CRP), MCP-1 and IFN-γ that were affected by smoking, the influence of SNPs was analyzed.

Result: Elevated levels of total WBCs, neutrophils, monocytes, lymphocytes, CRP, MCP-1, IFN-γ and lower levels of miR-21 were detected in smokers. The elevated levels of IFN-γ in smokers was only statistically significantly associated with rs2069705 AG/GG SNP-genotype.

Conclusions: A lower level of oncomir miRNA-21 and a higher level of immune modelling cytokine IFN-γ detected in smokers could be a protective immune response to cigarette smoke. The higher level of IFN-γ in smokers with a specific SNP genotype also suggests that a genetic interaction with smoking might predict the pathobiology of smoking related disease.