Alterations in Gene Expression of Interferon and Tumor Necrosis Factor‐α in Human Blood Macrophage-Like Monocytes Induced by Clinical and Standard Salmonella typhi Strains in vitro

Background and Objective: Salmonella typhi as a human pathogen stimulates the human immune system and triggers gene expression changing its pathogenesis. Therefore, we aimed to investigate the expression levels of ifn-γ and tnf-α cytokines in human blood macrophage-like monocytes in dealing with clinical and standard samples of Salmonella typhi in vivo. Materials and Methods: In this cross-sectional descriptive study, a total of 60 stool samples from patients with gastroenteritis were cultured and biochemical tests were used to diagnose Salmonella. Also, venous blood samples were taken for peripheral blood mononuclear cell (PBMC) isolation, and PBMCs were cultured in a culture medium containing 4×103cfu/mL treatments of Salmonella typhi pathogen and standard. Cytotoxicity tests were also performed to determine the concentrations. Finally, quantitative expression levels of ifn-γ and tnf-α were measured and the results were analyzed by statistical tests. Results: The results of the cytotoxicity test showed the use of Salmonella typhi concentrations for treatment in an authorized culture medium at a concentration of 4×103 cfu / mL. In comparison to control samples, a significant increased expression levels of tnf-α gene have been detected in pathogen strain and ATCC strain (P<0.05) (P=0.0198). Furthermore, significantly increased expression levels of IFN-γ gene have been detected in the pathogen strain and ATCC strain (P<0.05) in comparison to the control sample (P=0.0001). Conclusion: Increased and significant expression of ifn-γ and tnf-α cytokines in the sample group treated with pathogen strain and ATCC strain indicates polarization of macrophages stimulated by Salmonella typhi in vitro.