Effects Of Lactobacillus Reuteri From Pigs On Intestinal Barrier Function And Extracellular Matrix Of Weaned Piglets

Weaning of piglets can cause a series of stresses such as intestinal damage,diarrhoea and slow growth due to their imperfectly developed intestinal tract.Therefore,nutritional control during weaning is particularly important during the growth and development of piglets.The extracellular matrix is an important component of intestinal tissues and its main components include collagen,fibronectin,laminin and proteoglycans,which provide the structural organisational framework and transmit tissue-specific signals to nearby enterocytes.Recent studies have revealed that extracellular matrix remodeling is essential for the homeostasis of intestinal tissues and that its specific network structure impedes contact between host cells and pathogens.Previously,our team successfully screened a new strain of Lactobacillus reuteri LR1 in the faeces of healthy piglets and found that it has good probiotic properties and has great potential for development in replacement of resistance.The aim of this research paper is to investigate the effects of Lactobacillus reuteri LR1 of porcine origin on the growth performance,intestinal barrier function and extracellular matrix of piglets from 0 to 42 days post-weaning,with the following main findings:1.Study of the effect of Lactobacillus reuteri from pigs on the growth performance and intestinal barrier function of weaned pigletsA total of 144 piglets weaned at 21 days of age were randomly divided into3 groups and fed the basal diet（control group,CON group）,basal diet supplemented with 75 mg/kg aureomycin and 100 mg/kg quinol（antibiotics group,AO group）and basal diet supplemented with 5×10¹⁰CFU/kg Lactobacillus reuteri LR1 of porcine origin（Lactobacillus group,LR1 group）,each group 8 replicates,6 piglets per replicate.The trial period was 42 days.The results of the trial showed that:（1）Compared to the CON group,piglets in the LR1 and AO groups showed a significant increase in final body weight and average daily gain,and a trend towards a decrease in diarrhoea rate,but the difference was not significant.（2）The addition of Lactobacillus reuteri LR1 to the diet significantly increased the villi height in the duodenum,jejunum and ileum of piglets and increased the villi ratio in the ileum.In addition,Lactobacillus reuteri LR1 significantly increased the expression of genes related to the intestinal barrier in piglets,such as mucin-2（MUC-2）in the jejunum,porcineβ-defensin 3（p BD3）in the ileum,zonula occludin-1（ZO-1）and Occludin,mucin（MUC-1 and MUC-2）,porcineβ-defensin（p BD2 and p BD3）and Toll-like receptor-2（TLR2）genes in the colon.The Lactobacillus reuteri LR1 group showed no significant effect on the alpha diversity and beta diversity of the cecum contents microbiota and the cecum-associated metabolite short-chain fatty acids,but the number of Lactobacillus and the Lactobacillus/Escherichia coli ratio in the cecum were significantly higher.2.Exploring the effect of Lactobacillus reuteri from pigs on the intestinal extracellular matrix of weaned pigletsThe test results showed that the distribution of intestinal collagen fibres extended from the lower to the upper layers of the intestinal mucosa in all three groups,but the LR1 group had a significantly lower intestinal collagen volume fraction and reduced deposition of collagen fibres.Meanwhile,intestinal extracellular matrix gene expression was significantly reduced in the LR1 group,such as type I collagenα2 chain（COL1A2）,COL3A1,COL4A2,COL5A1,COL6A1,fibronectin（FN1）,tendonin（TNC）,and integrin（ITG）.In addition,the addition of Lactobacillus reuteri LR1 to the diet significantly reduced gene expression of the ileal extracellular matrix regulatory factors endoplasmic reticulum channel protein（SEC6A1）,phosphodiesterase 4D（PDE4D）and matrix metalloproteinase-2（MMP-2）;compared to the AO group,gene expression of SEC6A1 and transforming growth factor-β（TGF-β）was significantly lower in the LR1 group.These results suggest that Lactobacillus LR1 dynamically regulates intestinal extracellular matrix expression by affecting SEC6A1,PDE4D and MMP2.In summary,the addition of 5×10¹⁰CFU/kg Lactobacillus reuteri LR1 from pigs to the diet can improve the growth performance of piglets from 0 to 42 days after weaning and maintain the intestinal homeostasis of weaned piglets by improving the function of the intestinal epithelial barrier and alleviating the deposition of extracellular matrix in the lower intestinal layer,and can be widely used as an effective alternative to antibiotics in the production of weaned piglets.