The proinflammatory cytokine tumor necrosis factor (TNF) has been described as one of the main mediators of intestinal inflammatory diseases, affecting the composition of tight junction (TJ) proteins and leading to a disruption of the epithelial barrier. An intact intestinal barrier is mandatory, because the follicle-associated epithelium of Peyer's patches represents the first defense line of the intestinal immune system and ensures a controlled uptake of antigens from the gut lumen. In the current study, we have analyzed the detailed effects of TNF on the follicle-associated epithelium of porcine Peyer's patches by applying the Ussing chamber technique. Epithelial tissue specimens of Peyer's patches and the surrounding villus epithelium were mounted into conventional Ussing chambers and incubated with TNF for 10 h. The transepithelial resistance, representing epithelial barrier function of the tissue, was recorded. A reduction of transepithelial resistance was detected after 8 h in Peyer's patch tissue specimens, whereas the villus epithelium was not significantly affected by TNF. Subsequent molecular analysis of TJ protein expression revealed a marked decrease of claudin-1 and -4, and an increase of claudin-2. In neighboring villus epithelium, no significant changes in the expression of TJ proteins could be shown. A strong increase of TNF receptor-2 (TNFR-2) could also be detected in Peyer's patches, in agreement with the major role of this receptor in Peyer's patches. Our findings were in accordance with changes detected by confocal laser scanning immunofluorescence microscopy. The regulation of TNF effects via myosin light chain kinase (MLCK) was analyzed in blocking experiments. Our detailed analysis is the first to show that TNF affects the barrier function of the follicle-associated epithelium of porcine Peyer's patches but has no effects on the villus epithelium. These findings reveal not only the basic differences of epithelial barrier function between the two structures, but also the significance of Peyer's patches as a primary mucosal immune defense.

Antibiotic resistance is a major issue in animal industries and antibiotic-free alternatives are needed to treat infectious diseases and improve performance of pigs. Plant extracts have been suggested as a potential solution. The present study was conducted to investigate the effects of Astragalus polysaccharides (Aps) and ginseng polysaccharide (Gps) on growth performance, intestinal morphology, immune function, volatile fatty acids (VFAs), and microfloral community in weaned piglets. A total of 180 weaned piglets were randomly divided into three treatment groups during a 28-days feeding experiment, including a basal diet (Con), basal diet supplemented with 800 mg/kg Aps (Aps), and basal diet supplemented with 800 mg/kg Gps (Gps). Results showed that both Aps and Gps increased body weight, average daily gain and feed conversion rate, and reduced the rate of diarrhea. Gps also decreased aspartate aminotransferase compared to the Con piglets after 14 days. No significant effects on alanine aminotransferase were observed. Both Aps and Gps piglets exhibited higher serum immunoglobulin M levels after 14 and 28 days, and also decreased jejunal crypt depth, increased jejunal villus length and villus height/crypt depth ratio, and increased expression of toll-like receptor 4, myeloid differentiation primary response 88, nuclear factor-kappa B proteins in the jejunum. Aps and Gps piglets also had higher concentrations of acetic acid, isobutyric acid, and butyrate in their colon. Data of high-throughput sequencing revealed that Aps and Gps affected bacterial quantity and diversity in the colon. Species richness and evenness were higher in both Aps and Gps piglets than the control piglets. Aps and Gps piglets also had a higher relative abundance of Lachnospiraceae and Anaerostipes, and the Aps piglets had a higher relative abundance of Lactobacillus gasseri and L. amylovorus. Therefore, dietary supplementation with Aps and Gps could be beneficial for optimizing the performance of industry pigs and reducing dependence on antibiotics. Furthermore, Plant polysaccharides play a great role in promoting the sustainable development of animal husbandry.