Article Shareing | Interactions Between the Porcine Host and Gut Microbiota — The impact of gut microbiota on the host immune system

Interactions Between the Porcine Host and Gut Microbiota — The impact of gut microbiota on the host immune system

Pigs are the only animal susceptible to diarrhea caused by HRV (human rotavirus). In one study, newborn gnotobiotic pigs (delivered by cesarean section and lacking a mature microbiota) were orally administered probiotics—specifically Lactobacillus rhamnosus GG strain and Bifidobacterium animalis Bb12, two major bacterial species found in the gut of breastfed infants—to investigate the effects of an attenuated (Att) HRV WA strain vaccine on B-cell responses. Compared to piglets that were not colonized with probiotics but were vaccinated with AttHRV, the probiotic-colonized and vaccinated piglets showed significantly improved fecal scores and reduced HRV shedding titers. Furthermore, HRV-associated diarrhea was reduced in probiotic-treated piglets compared to unvaccinated pigs, and this was associated with the presence of high levels of intestinal HRV IgA antibodies and intestinal HRV-specific IgA antibody-secreting cells.

In another study, germ-free pigs colonized with a healthy human infant gut microbiota (comprising approximately 98% Firmicutes and Proteobacteria) exhibited elevated expression levels of IL-6 and IL-10 in ileal mononuclear cells. In pigs vaccinated with the AttHRV strain, the development of the neonatal immune system was promoted by enhancing T-cell responses that produced abundant IFN-γ and reducing T-reg cell differentiation and the production of associated cytokines.

Wu et al. further summarized numerous additional studies in germ-free rats, mice, and humans, highlighting the importance of a healthy microbiota for the normal development and function of the acquired immune system in mammals.

Many studies have reported the colonization effects of gut microbiota on germ-free pigs. In a study conducted by Laycock et al., 24 pigs were inoculated with the Bristol microbiota, a novel simplified porcine microbiota. These pigs showed no obvious health issues, and the Bristol microbiota successfully induced upregulation of serum immunoglobulins IgA and IgM. However, the level of IgG2 was significantly lower than that in conventional colostrum-fed pigs, suggesting that the sow has an influence on IgG2 production. Therefore, the Bristol microbiota can be used to improve the formation and subsequent development of the intestinal mucosa and the general immune system in newborn pigs.