Stimulatory effects of derived extracellular vesicles on toll-like receptor 9 gene expression and cytokine profile in human intestinal epithelial cells.

BACKGROUND

A complex community of microorganisms in the gastrointestinal (GI) tract, known as the gut microbiota, exerts major effects on gene expression and cytokine profile. Extracellular vesicles (EVs) which are produced by bacteria could be sensed by Toll like receptors (TLRs). The interaction between gut microbiota and TLRs affects homeostasis and immune responses. In this study, we evaluated TLR9 gene expression and cytokines level in Caco-2 cell line treated with as one of the gut microbiota and its EVs.

METHODS

In the present study, derived EVs was extracted via ultracentrifugation. The quality control assessment included the evaluation of physicochemical characteristics of EVs. For the treatment of Caco-2 cell line, and its EVs (100 and 150 μg/mL) were used. In addition, qRT-PCR assay was carried out to evaluate the mRNA expression of gene. ELISA assay was also performed to determine the levels of IFN, TNF-α, GM-CSF, IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-12, IL-17A, and IL-10 cytokines.

RESULTS

The results showed that slightly increased gene expression in the Caco-2 cell line. It was also found that EVs at concentrations of 100 and 150 μg/mL could significantly decrease gene expression. Furthermore, significantly increased IL-10 and IFN levels Based on the findings, the level of IL-17A, as a proinflammatory cytokine, decreased by . Both concentrations of EVs decreased the level of IFN, while increasing the concentrations of IL-4 and IL-10. EVs from could modulate immune responses in the Caco-2 cell line. Both EVs and activated the expression and secretion of several cytokines.

CONCLUSIONS

and its EVs have pivotal role in the cross talk between gut microbiota and the host especially in the modulation of the immune system. This study shows for the first time the increasing level of anti-inflammatory cytokines by EVs released by . Based on the last studies on immunomodulatory effect of EVs on immune cells and our results in cell line level, we postulate that derived EVs could be possible candidates for the reduction of immune responses.