Lactobacillus plantarum and Lactobacillus brevis alleviate enterotoxigenic Escherichia coli-induced intestinal inflammation and stabilize intestinal microorganisms and serum metabolites in piglets

Enterotoxigenic <i>Escherichia coli</i> (ETEC) is a major pathogen causing diarrhea in weaned piglets, and oral administration of probiotics has become an important strategy for preventing and treating ETEC-induced diarrhea. The aim of this study was to investigate the protective effect of two probiotics, <i>Lactobacillus plantarum</i> and <i>Lactobacillus brevis</i>, on ETEC-induced injury in piglets. Twenty-four piglets were randomly divided into control (CON) group (fed with a basal diet and treated with sterile saline), ETEC group (fed with the basal diet and treated with ETEC), LP-ETEC group (fed with the basal diet and treated with ETEC and <i>L</i>. <i>plantarum</i>) and LB-ETEC group (fed with the basal diet and treated with ETEC and <i>L. brevis</i>), with 6 piglets in each group. The experiment lasted for 21 days. The results indicated that both probiotics were able to inhibit the ETEC-induced reduction in daily weight gain of piglets and prevent the damage to jejunum. <i>L</i>. <i>brevis</i> significantly increased daily weight gain (<i>P</i> = 0.012), while <i>L</i>. <i>plantarum</i> showed a similar trend (<i>P</i> = 0.063). Serum metabolomic analysis showed that both probiotics significantly increased some beneficial metabolites including phosphatidylethanolamine, monoacylglyceride, cholic acid and rhodoxanthin (<i>P</i> < 0.05). Transcriptome sequencing indicated that <i>L. plantarum</i> and <i>L. brevis</i> may alleviate piglet diarrhea by regulating genes including <i>LBH</i> and <i>RNASE1</i>. According to 16s rRNA sequencing, both probiotics were able to maintain the normal microbial community of the gut. In summary, <i>L. plantarum</i> and <i>L. brevis</i> can protect piglets from ETEC-induced damage and promote healthy growth of piglets by regulating metabolites and gene expression.