Abstract
Diarrhoea causing bacteria is a common cause of inflammation and damage to theintestine. Propolis is a natural substance of bee origin that contains bioactivecomponents with anti-inflammatory and antioxidant activities, but its role in thefunction of the intestinal barrier and the gut microbiota is still insufficiently understood.This study aimed to investigate the protective effect of propolis against intestinal injuryinduced by lipopolysaccharide (LPS) in Institute of Cancer Research (ICR) mice. Eachof the 30 mice were randomly grouped into a control (NC), an LPS-treated (NM), anda propolis-treated (NT) group. Propolis (75 mg/kg) and LPS (10 mg/kg) were injectedinto the peritoneal cavity of mice in the NT group and the NM group, respectively. Micein the NT group were treated with propolis (75 mg/kg), and in the NM group weretreated with LPS (10 mg/kg) by intraperitoneal injection. Jejunum (the middle sectionof the small intestine) morphology was found to be improved by propolis because ofthe enhancement in villus height and the ratio of villus height/crypt depth. Body weightloss caused by LPS was significantly reduced by propolis. It also lowered the proinflammatory cytokine levels of IL-1β, TNF-α, and IL-6, while simultaneously raisingthe level of anti-inflammatory cytokine IL-10, antioxidant ability with an increase inSOD, T-AOC, and GSH-Px, and a decrease in the level of MDA. In addition, propolissignificantly up-regulated the gene expression and protein levels of the intestinal barriermarkers (Claudin-1, ZO-1, and Occludin) both on the gene and protein level, suggestingimproved intestinal barrier integrity. High throughput 16S rRNA sequencing yieldedTitle Page24,131,146 raw reads and 3,934,474 filtered reads indicating that propolis increased thediversity of gut microbes, altered the abundance of beneficial bacterial taxa, enhancedthe network of relationships among microbes and restored metabolic functionspredicted by MetaCyc and KEGG analysis. In summary, propolis was effective atpreventing intestinal damage caused by LPS, through anti-inflammatory, antioxidant,intestinal barrier maintenance, and maintenance of intestinal microbiota balance. Basedon these findings, propolis can be considered as a promising natural therapeutic agentto prevent and treat intestinal inflammation and injury.