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Macrophages are professional phagocytic cells that play a critical role in initiating immune responses by presenting antigen and phagocytic clearance. The macrophages can be targeted for immunomodulation by beneficial microbes, such as probiotics. The aim of this study is to investigate the protective effect of Saccharomyces boulardiiagainst Clostridium perfringensinfection in avian macrophage cell line HD11. In this study, HD11 macrophages were prestimulated with S. boulardiifor 6 h and then infected with C. perfringensfor 3 h. Results showed that S. boulardiienhanced phagocytosis and bactericidal capacity against C. perfringensby HD11 cells. The S. boulardiieffectively promoted the mRNA expression of CD80, CD83, and CD197 cell-surface molecules in C. perfringens-infected HD11 cells. Moreover, we found that prestimulation with S. boulardiireduced the mRNA expression of CD40, toll-like receptor [TLR] 4, and TLR15 induced by C. perfringensand thereby downregulated the mRNA expression of myeloid differentiation primary response 88, TNF receptor associated factor 6, nuclear factor kappa-B p65 subunit, and c-Jun N-terminal kinase genes in HD11 cells. The upregulation of cytokines (interleukin [IL]-6, tumor necrosis factor alpha, and IL-10) and inducible nitric oxide synthase mRNA expression in C. perfringens-infected HD11 cells were noticeably inhibited by S. boulardiipretreatment. Conclusively, these results might provide a new insight into the role of S. boulardiiin regulating avian immune defense against C. perfringensinvasion and immune escape.

This study aimed to investigate the effects of Lactobacillus plantarum16 (Lac16) and Paenibacillus polymyxa10 (BSC10) on intestinal barrier function, antioxidative capacity, apoptosis, immune response, and biochemical parameters in broilers. A total of 540 one-day-old broiler chicks (Cobb500) were randomly allocated to three groups of 180 birds, and fed either a basal diet or a basal diet supplemented with 108colony-forming units Lac16 or BSC10 per kilogram feed for 21 D. The results revealed that both Lac16 and BSC10 maintained ileal mucosal morphology, and BSC10 regulated the expression of barrier function-related genes. Birds fed with probiotics decreased malondialdehyde level in jejunal mucosa and serum, and the increased activities of hepatic GSH-Px and jejunal CAT were observed in BSC10 group (P< 0.05). Immunohistochemistry of Bax, Bcl-2 and proliferating cell nuclear antigen and TUNEL-immunofluorescence assay demonstrated that Lac16 and BSC10 exerted beneficial effects on cell apoptosis and proliferation, as indicated by the gene expression of down-regulated Bax and p53 as well as a significant upregulation of Bcl-2 (P< 0.05). In addition, Lac16 and BSC10 significantly increased NO production and iNOS activity in liver and jejunal mucosa, and gene expression of IFN-γ(P< 0.01), IL-6(P< 0.05), and IL-10(P< 0.05 and P< 0.01, respectively) in ileum mucosa, whereas markedly decreased the expression of Cox2(P< 0.05). Furthermore, it was found that Lac16 and BSC10 significantly reduced levels of alkaline phosphatase (P< 0.05 and P< 0.01, respectively) and creatine kinase (P< 0.05). Moreover, BSC10 significantly reduced uric acid (P< 0.05) and low-density lipoprotein levels (P< 0.01). Taken together, Lac16 and BSC10 could improve intestinal and body health status of broilers by increasing intestinal barrier function, anti-oxidative capacity and immunity, and decreasing cell apoptosis with strain-specificity.