Changes in intestinal immunity and gut microbiota associated necrotic enteritis induced by Clostridium perfringens infection and exposure to heat stress in chicken

Background The present study investigated the effects of heat stress (HS) and Clostridium perfringens (C. perfringens) infection on the performance, jejunal morphometry, immunomodulatory responses of T cells, expression of cytokines and immune-related genes, and gut microbiota dynamics of male Qingyuan Patridge chickens. Healthy 20-day-old of male Qingyuan chicks (192) were randomly assigned to four groups of 12 replicates (n = 4 chicks/replicate). A 2 × 2 factorial arrangement experiment was performed, including two levels of oral C. perfringens dosages, without (CP0) and with 2×10 ⁸ CFU/mL (CP2) under two ambient temperatures of 25°C (L) and 35°C (H) for 30 d. Results The results showed that exposure of chicks to HS and C. perfringens infection in the H CP 2 (chicks reared under H ambient temperature with an oral dosage of CP ) group decreased ( P  < 0.05) feed intake, body weight, daily weight gain, feed conversion ratio, villus height, and villus-to-crypt depth ratio in the jejunum compared to the LCP0 group. The plasma concentrations of interleukin (IL)-6 and IL-10 were lower ( P  < 0.05) in the H CP 2 group than in the L CP 0 group (chicks reared under L ambient temperature without an oral dosage of CP). The T lymphocyte subsets of peripheral blood CD4 ⁺ T cells, CD3 ⁺ CD4 ⁺ T cells, and the CD3 ⁺ CD4 ⁺ /CD3 ⁺ CD8 ⁺ ratio decreased ( P  < 0.05) in the H CP 2 group compared with the other groups. Intestinal mRNA expression of IL-4 , IL-6 , IL-10 , IFN-γ was downregulated; however, IL-8, tumor necrosis factor-α ( TNF-α ), nuclear factor kappa B ( NF-κB ), zonula occludens-1 ( Zo-1 ), and Claudin-1 were upregulated in the H CP 2 group compared to the L CP0 group. The gut microbiota in the H CP 2 group had a higher relative abundance of Esherichia-Shigella , Staphylococcus, Clostridia, Cyanobacteria , and Listeriaceae compared to the other groups. Conclusions These results demonstrate the potentially harmful effects of exposure to HS and C. perfringens infection on necrotic enteritis-related disturbances, growth performance, jejunum morphometry, immune-modulatory responses of T cells, expression of cytokines and immune-related genes, and gut microbiota dynamics in Qingyuan Patridge chickens exposed to HS.