IBV QX affects the antigen presentation function of BMDCs through nonstructural protein16.

The gamma-coronavirus infectious bronchitis virus (IBV) has a high mutation rate and mainly invades the respiratory mucosa, making it difficult to prevent and causing great economic losses. Nonstructural protein 16 (NSP16) of IBV QX also not only plays an indispensable role in virus invading but also might hugely influence the antigen's recognition and presentation ability of host BMDCs. Hence, our study tries to illustrate the underline mechanism of how NSP16 influences the immune function of BMDCs. Initially, we found that NSP16 of the QX strain significantly inhibited the antigen presentation ability and immune response of mouse BMDCs, which was stimulated by Poly (I:C) or AIV RNA. Besides mouse BMDCs, we also found that NSP16 of the QX strain also significantly stimulated the chicken BMDCs to activate the interferon signaling pathway. Furthermore, we preliminarily demonstrated that IBV QX NSP16 inhibits the antiviral system by affecting the antigen-presenting function of BMDCs.

Bacillus subtilis programs the differentiation of intestinal secretory lineages to inhibit Salmonella infection.

The role of intestinal microbiota on fate determination of intestinal epithelial cells has not been extensively examined. In this study, we explore the effect of Bacillus subtilis on programmed intestinal epithelial differentiation. We find that B. subtilis stimulates the differentiation of intestinal secretory cells. Moreover, B. subtilis inhibits the Notch pathway to reduce the expression of hairy and enhancer of split 1, thereby shifting intestinal stem cell differentiation toward a secretory cell fate. Moreover, we demonstrate that the programming effect of B. subtilis on intestinal differentiation is Toll-like receptor 2 pathway dependent. B. subtilis is associated with increased numbers of Paneth and goblet cells in the intestine. This results in the production of antimicrobial peptides to protect the intestinal mucosal barrier against Salmonella typhimurium. This study demonstrates that B. subtilis contributes to the differentiation of secretory cells by affecting Notch pathway signaling to maintain the intestinal barrier.

Effect of Bacillus coagulans on maintaining the integrity intestinal mucosal barrier in broilers.

Bacillus coagulans (B. coagulans), a spore-forming bacteria, has been further studied for its high tolerance to extreme environmental stressors and probiotic characteristics. But the modulatory effect of B. coagulans on the intestinal mucosal barrier remains unclear. To investigate the effects of B. coagulans on intestinal mucosal barrier, 1-day-old broiler chickens were orally administrated with 108 CFU/mL B. coagulans for consecutive 42 days. In this study, the body weight, jejunum villus height and crypt depth of broiler chickens were significantly increased after B. coagulans treatment. B. coagulans also increased the contents of total protein (TP) and albumin (ALB) in serum, and reduced the contents of low-density lipoprotein (LDL-C), blood urea nitrogen (BUN) and triglyceride (TG). In addition, B. coagulans improved the intestinal flora, significantly increasing the relative abundance of beneficial bacteria in the intestine. The ability of B. coagulans to enhance innate immunity is observed by the increased number of goblet cells and the decreased mRNA expression of IL-1ß, IL-6, TNF-α, and sIgA content. Moreover, B. coagulans promoted intestinal epithelial proliferation through the Wnt/ß-catenin signaling pathway. This study demonstrated that B. coagulans could maintain the intestinal mucosal barrier by improving the intestinal flora, enhancing innate immunity and promoting intestinal epithelial proliferation.

The Protective Effect of E. faecium on S. typhimurium Infection Induced Damage to Intestinal Mucosa.

Intensive farming is prone to induce large-scale outbreaks of infectious diseases, with increasing use of antibiotics, which deviate from the demand of organic farming. The high mortality rate of chickens infected with Salmonella caused huge economic losses; therefore, the promising safe prevention and treatment measures of Salmonella are in urgent need, such as probiotics. Probiotics are becoming an ideal alternative treatment option besides antibiotics, but the effective chicken probiotic strains with clear protective mechanism against Salmonella remain unclear. In this study, we found Enterococcus faecium YQH2 was effective in preventing Salmonella typhimurium infection in chickens. Salmonella typhimurium induced the loss of body weight, and liver and intestinal morphology damage. The inflammatory factor levels increased and intestinal proliferation inhibited. However, after treatment with Enterococcus faecium YQH2, broilers grew normally, the pathological changes of liver and intestine were reduced, and the colonization of Salmonella in the intestine was improved. Not only that, the length of villi and the depth of crypts were relatively normal, and the levels of inflammatory factors such as IL-1ß, TNF-α, and IL-8 were reduced. The number of PCNA cells of Enterococcus faecium YQH2 returned to normal under the action of Salmonella typhimurium infection, which was conducive to the normal proliferation of intestinal epithelial cells. The protective effect of Enterococcus faecium YQH2 may be due to the attribution to the activation of hypoxia and then induced the proliferation of intestinal stem cells to repair the damage of intestinal mucosa under Salmonella typhimurium infection. This study demonstrated that Enterococcus faecium YQH2 was effective in preventing Salmonella typhimurium infection, which could be further used in the chicken health breeding.