Objective It aims to preliminarily reveal the effect of dietary supplementation with porcine Lactobacillus reuteri LR1 on the expression of intestinal extracellular matrix (ECM) in weaned piglets, providing references for the promotion and application of porcine LR1 in animal husbandry.

Method One hundred and forty-four Duroc-Landrace-Yorkshire crossbred weaned piglets with similar body weights at 21 days of age were selected and randomly divided into three treatment groups, which were fed a basal diet (control group, CON group), a basal diet supplemented with 75 mg/kg of aureomycin and 100 mg/kg of quinol (antibiotic group, AO group), and a basal diet supplemented with 5×10¹⁰ CFU/kg of porcine L. reuteri LR1 (porcine L. reuteri LR1 group, LR1 group), respectively, and each treatment group was divided into 8 pens for feeding, with 6 pigs in each pen. The experiment lasted for 42 days. On the 43^rd day, one piglet from each group was randomly selected for slaughter, and samples of the duodenum (proximal), jejunum (middle), and ileum (distal) were taken for the detection of extracellular matrix related indicators such as intestinal collagen, fibronectin, tenascin and related regulatory factors.

Result Masson staining observations showed that collagen fibers in the duodenum, jejunum and ileum all extended from the lower to the upper layers of the intestinal mucosa. Compared with the CON group, the collagen volume fraction of the duodenum decreased significantly in both the LR1 and AO groups (P < 0.05), and the collagen volume fraction of the ileum also decreased significantly in the LR1 group (P < 0.05). TMT high-throughput proteomics results showed that the ECM-receptor interaction pathway was one of the major differential protein-enriched pathways, and the expression of its differential proteins, COL1A2, COL4A2, COL6A1, ITGA1, and other ECM molecules, was significantly lower in the LR1 group than that in the CON group (P < 0.05). In addition, the gene expression of COL1A2, COL3A1 and ITGβ2 in jejunum and ileum of LR1 and AO groups was significantly reduced compared with the CON group (P < 0.05), and the gene expression of COL4A2, COL5A1, COL6A1, FN1, TNC, ITGα1 in jejunum, and ITGα1 in ileum was also significantly reduced in the LR1 group (P < 0.05), but there were no significant effect on COL4A2, COL5A1, COL6A1, FN1 and TNC in ileum. Compared with the CON group (P < 0.05), in the ileum of the LR1 and AO groups, the contents of Collagen Ⅰ, Collagen Ⅱ, Collagen Ⅲ, Collagen Ⅳ, Collagen Ⅴ and Collagen Ⅵ significantly decreased; the gene expression of ileal cellular regulatory factors SEC6A1 and PDE4D in LR1 group significantly decreased (P < 0.05). Compared with the AO group (P < 0.05), the gene expression of the extracellular regulator MMP2 was significantly lower in the LR1 group (P < 0.05); and the gene expression of the intracellular regulator SEC6A1 and cytokine TGF-β significantly decreased in the LR1 group.

Conclusion Addition of porcine L. reuteri LR1 to the diet could modulate ECM remodeling by reducing gene expression of ECM regulators SEC6A1, PDE4D and other genes.