BackgroundPig diarrhea causes high mortality and large economic losses in the swine industry. Transmissible gastroenteritis virus (TGEV) causes pig diarrhea, with 100% mortality in piglets less than 2 weeks old. No investigation has yet been made of the small intestine of piglets that survived infection by TGEV.MethodsIn this study, we evaluated the impact of TGEV infection on the small intestine of recovered pigs.ResultsHistological analyses showed that TGEV infection led to villi atrophy, and reduced villous height and crypt depth. The number of SIgA positive cells, CD3+T cells, and dendritic cells (DCs) in jejunum decreased after TGEV infection in vivo. In contrast, microfold cell (M cell) numbers and cell proliferation increased in infected pigs. TGEV infection also significantly enhanced the mRNA expression levels of cytokine IL-1β, IL-6, TNF-α, IL-10, and TGF-β. Additionally, lower gene copy numbers of Lactobacillus, and higher numbers of Enterobacteriaceae, were detected in mucosal scraping samples from TGEV-infected pigs.ConclusionsTGEV infection damages the small intestine, impairs immune functions, and increases pathogenic bacterial loading, all of which may facilitate secondary infections by other pathogens. These findings help quantify the impact of TGEV infection and clarify the pathogenic mechanisms underlying its effects in pigs.

The nasal mucosa is the body's first barrier against pathogens entering through the respiratory tract. The respiratory immune system of pigs has more similarities with humans than the mouse respiratory system does, and so was selected as the animal model in the present study. To evaluate the effects of Bacillus subtilis as a potential probiotic to stimulate local immune responses, piglets were intranasally administered with Dylight 488-labeled B. subtilis (WB800-green fluorescent protein). The results revealed that B. subtilis was able to reach the lamina propria of the nasal mucosa, nasopharyngeal tonsils and soft palate tonsils. Piglets were subsequently administered intranasally with B. subtilis (WB800) at 3, 12 and 28 days. The results revealed that, following administration with B. subtilis, the number of dendritic cells, immunoglobulin A+ B cells and T cells in the nasal mucosa and tonsils significantly increased (P<0.05). No obvious differences were observed in the morphological structure following B. subtilis administration. There were no statistical differences were observed in the expression of interleukin (IL)-1β, tumor necrosis factor-α and IL-8 mRNA between the B. subtilis treated group and the control group in the nasal mucosa, nasopharyngeal tonsil or soft palate tonsil. Toll-like receptor (TLR)-2 and TLR-9 mRNA expression in the tonsils was significantly increased following B. subtilis administration compared with the control group (P<0.05). The results demonstrate that B. subtilis administration increases the number of immune cells in the nasal mucosa and tonsils of piglets and stimulates nasal mucosal and tonsillar immunity. The present study lays the foundation for further study into the intranasal administration of B. subtilis in humans to enhance the immunity of human nasal mucosa to respiratory diseases.

Inflammatory bowel disease (IBD) is a chronically relapsing inflammatory disorder of the gastrointestinal tract. Current IBD treatments have poor tolerability and insufficient therapeutic efficacy, thus, alternative therapeutic approaches are required. Recently, a number of dietary supplements have emerged as promising interventions. In the present study oral administration of a carotenoid (4,4′-diaponeurosporene)-producing Bacillus subtilis markedly ameliorated dextran sulfate sodium salt-induced mouse colitis, as demonstrated by a reduction in weight loss and the severity of bleeding, which indicated that 4,4′-diaponeurosporene may have beneficial effects on treatments for colitis. This preliminary study indicated that 4,4′-diaponeurosporene may function synergistically with probiotics to provide a novel and effective strategy to prevent colitis.

Gut mucosal immune responses are known to act as the first line of defense against invasion of pathogenic microorganisms. Piglets have an incompletely developed gut mucosal immune system, making them sensitive to intestinal infections. Promoting the development of the mucosal immune system will increase the pathogen resistance of piglets. The aim of the present study was to investigate the effect of carotenoid (4,4′‐diaponeurosporene)‐producing Bacillus subtilis (B.s‐Dia) on intestinal mucosal immunity in piglets. We showed that oral administration to piglets of B.s‐Dia remarkably improved the development of Peyer's patches (PPs) (P < 0.01), and increased villus height (P < 0.01) and colon crypt depth (P < 0.01). In addition, B.s‐Dia also increased the number of intraepithelial lymphocytes (P < 0.01), while Bacillus subtilis (B.s) had no significant influence on it (P > 0.05). Moreover, B.s‐Dia also increased the number of SIgA+ cells (P < 0.01). Oral administration of either B.s or B.s‐Dia increased the number of CD4+ and CD8+ cells in ileum lamina propria (P < 0.01). These results indicate that B.s‐Dia contributes to a higher extent to porcine mucosal immune system development than B.s, and might serve as an immunopotentiator candidate. Anat Rec, 302:1800–1807, 2019. © 2019 American Association for Anatomy

As an immune privilege site, there are various types of immune cells in the testis. Previous research has been focused on the testicular macrophages, and much less is known about the T cells in the testis. Here, we found that T cells with memory phenotypes were the most abundant leukocyte in the testis except for macrophages. Our results showed that the proportion of testicular T cells increases gradually from birth to adulthood in mice and that the primary type of T cells changed from γδTCR+ T cells to αβTCR+ T cells. In addition, under homeostatic conditions, CD8+ T cells are the dominant subgroup and have different phenotypic characteristics from CD4+ T cells. We found that cDC1, but not cDC2, is necessary for the presence of T cells in the testis under physiological state. A significant decrease of T cells does not have a deleterious effect on the development of the testis or spermatogenesis. However, cDC1-dependent T cells play an indispensable role in chronic autoimmune orchitis of the testis. Collectively, our multifaceted data provide a comprehensive picture of the accumulation, localization, and function of testicular T cells.