Investigating the effect of B. thetaiotaomicron and its derivatives on the expression of tlr2 and tlr4 genes in STC-1 cell line

Background: B. thetaiotaomicron is introduced as a candidate for the next generation of probiotics. TLR2, 4 play an important and necessary role in activating and modulating the innate immune system after exposure to bacteria in the intestine. This study aimed to investigate the effect of B. thetaiotaomicron and its derivatives on the alteration of the tlr2 and tlr4 gene expression. Materials and methods: The effects of B. thetaiotaomicron, OMVs, inactive bacteria and supernatant treatments on the tlr2 and tlr4 gene expression in the STC-1 cell line were investigated using the qRT-PCR method.    Results: The treatment of the STC-1 cell line with live and active B. thetaiotaomicron did not have significant effect on transcription of  tlr2, 4. The OMVs of this bacterium at 50 µg/ml significantly increased the gene expression of tlr2 (p=0.01) and tlr4 (p=0.02), but at a concentration of 100 µg/ml, its effect was not significant. Inactive bacteria at MOI 10 (p=0.03) and MOI 50(p=0.003) significantly induce the transcription of both two genes. Supernatant 25% significantly increased tlr2 (p=0.038) and tlr4 (p=0.034) gene expression at the transcription level. Conclusion: Our results showed that OMVs at a concentration of 50 μg/ml, inactive bacteria, and supernatant B. thetaiotaomicron play an important role in modulating immune response and can be used as a next generation postbiotics and paraprobiotic candidates for further studies to be used.