Evaluation of EcN and Its OMVs in Human TLR Signaling Pathway: Introducing a Novel Component for Inflammatory Disease

Abstract

Background: Microorganisms colonizing the gastrointestinal tract interact with the host through epithelial cells. More than 60% of the immune cells in the intestine are located in the intestinal mucosa, making it the bodys major defensive barrier. Commensal bacteria, their metabolites, and toll-like receptors interact with the epithelial cells in the intestine to maintain homeostasis and promote immunity. HT-29 is a human colorectal adenocarcinoma cell line with epithelial morphology. Materials and Methods: In this study, Escherichia coli strain Nissle 1917 (EcN) bacteria and their outer membrane vesicles (OMVs) exerted influence on the expression of toll-like receptors (TLRs) pathway genes in HT-29 cells. Real-Time PCR was used to measure the expression of TLRs signalling pathway genes after RNA extraction and cDNA synthesis. A real-time quantitative reverse transcription PCR array using SYBR Green method was conducted to determine the mRNA expression of 84 genes involved in the TLR signalling pathway. Results: EcN induced the down-regulation of pro-inflammatory genes such as IRAK4, MAP2K4, CCL2, NFRKB, and IRAK1. Further, OMVs derived from EcN stimulated the HT-29 cells by downregulating several genes involved in the inflammatory responses such as IRAK1, IRAK4, CD14, MYD88, and MAP4K4 and up-regulating the anti-inflammatory interleukin-10. However, EcN OMVs caused mild inflammation and anti-inflammatory responses that influenced intestinal homeostasis. Conclusions: Postbiotics are non-replicate, so they are unable to cause probiotic-associated risks like bacteraemia fungaemia, etc.