Analysis of miRNA Expression Profiling of RIP2 Knockdown in Chicken HD11 Cells When Infected with Avian Pathogenic E. coli (APEC)

Intestinal differential metabolite tryptophan from avian pathogenic Escherichia coli (APEC)-resistant and susceptible chickens alleviates APEC symptoms in chickens

To identify an effective antibiotic to combat avian pathogenic Escherichia coli (APEC), differential metabolites in the intestines of APEC-resistant and susceptible chickens were investigates. The effect of supplementing the diet of APEC-challenged chickens with the differential metabolite tryptophan was investigated. Tryptophan was identified as an important differential gut metabolite (APEC-resistant and susceptible chickens) using tryptophan-targeted metabolism detection. A total of 120 one-day-old chickens were divided into four groups: with and without 0.1 % tryptophan supplementation in the basal diet with and without APEC challenge. The APEC challenge test was conducted after an adaptation period of 8 days. The infection lasted 7 days, during which dead chickens were subjected to pathological autopsy, and the mortality rate was recorded. All chickens were slaughtered at the end of the infection test to calculate morbidity. Dietary supplementation with tryptophan did not significantly affect mortality in APEC-challenged chickens (P > 0.05) but significantly reduced their morbidity (P < 0.05). Dietary tryptophan supplementation reversed the elevated splenic gene expression of IL-6, TLR4, and NF-κB induced by the APEC challenge in chickens (P < 0.05). Tryptophan supplementation also alleviated the APEC-induced upregulation of the pro-inflammatory factors IL-6, IFN-γ, and IL-1β in the blood (P < 0.05). Simultaneously, dietary supplementation with tryptophan significantly increased glutathione peroxidase activity and total antioxidant capacity level in the blood of APEC-challenged chickens (P < 0.05). Thus, APEC challenging in chickens induced organ damage, up-regulated inflammation-related gene expression in the spleen, and increased the levels of inflammatory factors in the blood. Dietary supplementation with tryptophan inhibited the production of inflammatory factors, possibly through the TLR4/NF-κB signaling pathway and attenuated the morbidity and the inflammatory response caused by the APEC challenge.

Differential responses to avian pathogenic E. coli and the regulatory role of splenic miRNAs in APEC infection in Silkie chickens

Avian pathogenic Escherichia coli (APEC) is a bacterial disease that harms the poultry industry worldwide, but its effect on Chinese Silkie has not been reported. Studies on whether there are differences in Silkie individual resistance to APEC and the regulatory role of spleen miRNAs lay the foundation for strategies against APEC. Therefore, 270 Silkie chickens were infected with the median lethal dose of an E. coli O1, O2, and O78 mixture. These chickens were divided into a susceptible group (Group S) and a recovery group (Group R) according to whether they survived 15 days postinfection (dpi). Moreover, 90 uninfected APEC Silkie served as controls (Group C). The splenic miRNA expression profile was examined to evaluate the role of miRNAs in the APEC infection response. Of the 270 Silkies infected with APEC, 144 were alive at 15 dpi. Cluster analysis and principal component analysis (PCA) of splenic miRNAs revealed that the four Group R replicates were clustered with the three Group C replicates and were far from the three Group S replicates. Differentially expressed (DE) miRNAs, especially gga-miR-146b-5p, play essential roles in immune and inflammatory responses to APEC. Functional enrichment analyses of DEmiRNAs suggested that suppression of immune system processes (biological processes) might contribute to susceptibility to APEC and that FoxO signaling pathways might be closely associated with the APEC infection response and postinfection repair. This study paves the way for screening anti-APEC Silkies and provides novel insights into the regulatory role of miRNAs in APEC infection.