LACTIPLANTIBACILLUS PLANTARUM STRENGTHENS THE INTESTINAL BARRIER: INVOLVEMENT OF THE ENDOCANNABINOIDOME

Probiotics have been suggested to ameliorate the function of the intestinal epithelial barrier and so have several mediators and receptors of the expanded endocannabinoid system, the endocannabinoidome (eCBome). Here we cocultured three live strains of Lactiplantibacillus plantarum with intestinal epithelial organoids to study their effects on the gut barrier function and the possible involvement of the eCBome in this effect. All three L.plantarum strains variously reduced the trans-epithelial permeability of intestinal organoids and promoted increased mRNA expression of several tight junction proteins and intestinal barrier proteins. Concomitantly, the three strains upregulated the expression of genes encoding biosynthetic enzymes (i.e., NapePLD, Abdh4, Gde1, Daglb) and receptors (i.e., Cnr1, Cnr2, Gpr55, and Ppara), while concurrently downregulating the expression of two essential catabolic enzymes (i.e. Faah and Naaa), involved in the signaling of several eCBome mediators known for their role in regulating the intestinal epithelial barrier. Selective inhibitors of eCBome mediator degrading enzymes FAAH and MAGL, i.e., URB597 and JZL184, increased N-acyl-ethanolamine (NAE) and 2-monoacylglycerol (2-MAG) levels, respectively, enhanced the expression of intestinal epithelial barrier genes and reduced the trans-epithelial permeability of organoids, as for L. plantarum strains. Interestingly, inflammation-induced trans-epithelial permeability in organoids was also reversed by both FAAH and MAGL inhibitors. We surmise that elevated endogenous levels of either NAEs or 2-MAGs promote improvement in small intestine trans-epithelial permeability and that L. plantarum strains may exploit this mechanism to promote these beneficial effects. Intestinal organoids exposed to inhibitors of enzymes part of the endocannabinoid system

已有研究表明，益生菌可改善肠上皮屏障功能，而扩展型内源性大麻素系统（expanded endocannabinoid system）的多种介质与受体——即内源性大麻素组（endocannabinoidome，eCBome）——亦具备此类功效。本研究将三株活性植物乳杆菌（Lactiplantibacillus plantarum）与肠上皮类器官共培养，以探究其对肠道屏障功能的影响，以及eCBome是否参与介导该过程。三株植物乳杆菌均不同程度降低了肠类器官的跨上皮通透性，并上调了多种紧密连接蛋白与肠屏障蛋白的mRNA表达水平。与此同时，三株菌株均可上调编码生物合成酶（NapePLD、Abdh4、Gde1、Daglb）与受体（Cnr1、Cnr2、Gpr55、Ppara）的基因表达，同时下调两种关键分解代谢酶（Faah、Naaa）的表达——这两种酶参与多种已知可调控肠上皮屏障功能的eCBome介质的信号传导。靶向eCBome介质降解酶FAAH与MAGL的选择性抑制剂URB597和JZL184，可分别升高N-酰基乙醇胺（N-acyl-ethanolamine，NAE）与2-单酰甘油（2-monoacylglycerol，2-MAG）的水平，且与植物乳杆菌菌株作用一致，可增强肠上皮屏障基因的表达并降低类器官的跨上皮通透性。值得注意的是，FAAH与MAGL抑制剂同样可逆转炎症诱导的肠类器官跨上皮通透性升高。我们推测，内源性NAEs或2-MAGs水平升高可改善小肠跨上皮通透性，而植物乳杆菌菌株或可通过该机制发挥上述有益作用。暴露于内源性大麻素系统相关酶抑制剂的肠类器官