Regulation and Molecular Mechanism of TLR5 on Resistance to Escherichia coli F18 in Weaned Piglets

Abstract

Simple SummaryPiglet diarrhea is the most common type of disease on many large-scale pig farms, where it causes serious economic losses. Abuses of vaccines and veterinary medicine are very common, which not only lead to the emergence and prevalence of drug-resistant bacteria, but also to a decline in the quality of livestock products and economic benefits. Therefore, improving the resistance of piglets to diarrhea by genetic means is a common goal of modern breeding scientists. This study aims to reveal the molecular mechanism of regulating piglet diarrhea via the important candidate gene TLR5 from the perspective of epigenetic factors.AbstractToll-like receptor 5 (TLR5) plays an important role in immune system. In this study, we performed transcriptome analysis of the duodenum in E. coli F18-resistant and -sensitive Sutai weaned piglets and analyzed the differential expression of TLR5. The cellular localization of TLR5 was investigated, and the effect of TLR5 expression on E. coli invasion was evaluated after pig small intestinal epithelial cell lines (IPEC-J2) were stimulated by E. coli. The results showed that TLR5 expression level in duodenum and jejunum were significantly higher in E. coli F18-sensitive than in E. coli F18-resistant piglets. TLR5 protein was mainly expressed in the cytoplasm and cell membrane. The expression of genes associated with the TLR5 signaling pathway were significantly higher in TLR5-overexpressed cells than in control cells. Bacterial adhesion was higher in TLR5-overexpressed cells than in blank cells and lower in TLR5 interference than in blank cells. The core promoter region of TLR5 included two CpG islands and 16 acting elements. The methylation of the mC-6 site in the second CpG island of the promoter region had a regulatory effect on TLR5 expression. Therefore, TLR5 plays an important regulatory role on E. coli invasion. Low expression of TLR5 inhibited the immune response and decreased cell damage, which was conducive to the resistance to E. coli stimulation. In conclusion, this study preliminarily revealed the molecular mechanism of TLR5 gene regulating the resistance of piglets to Escherichia coli, and provided a new candidate gene for screening Escherichia coli resistance markers in pigs.

DNA Methylation of Pig FUT3 Promoter Alters mRNA Expression to Regulate E. coli F18 Susceptibility

“…To date, no study has assessed the E. coli F18 resistance in Chinese local weaned piglets and their molecular mechanism is still remaining elusive. In previous studies, the TLR genes, i.e., TLR5 and CD14 play important roles in the pig intestine inflammatory response against invading E. coli F18 pathogens [22,23]. In addition to intestinal immunity, resistance to E. coli F18 is most commonly correlated with the expression of the level of its receptor in the intestinal epithelial cells in piglets [24].…”

Toward a porcine in vivo model to analyze the pathogenesis of TLR5-dependent enteropathies

“…28 Consistently, the impaired flagellin recognition in the pig may confer an increased susceptibility to flagellated bacteria, such as Salmonella Typhimurium and (entero-)pathogenic E. coli. [29][30][31] The latter observation opens the possibility for further investigations of the functional role of TLR5-signaling in mucosal inflammation in a model that mimics the human situation more closely and may additionally allow the evaluation of potential preventive measures and therapeutic strategies. Pigs share key similarities with humans, such as body size, anatomical features, (patho-)physiological responses and diet.…”

miR-215 Targeting Novel Genes EREG, NIPAL1 and PTPRU Regulates the Resistance to E.coli F18 in Piglets

“…The PCR amplification products were detected by electrophoresis and verified by sequencing. The confirmed PCR products were recovered and purified, then the pCpGL-basic vector was used to construct recombinant vectors according to the method described in our previous study [30]. 293T cells were cultured in 12-well plates with DMEM containing 10% FBS in a 37 • C incubator with 5% CO 2 .…”