ABSTRACT

Diarrheal disease is a common health problem with complex causality. Although diarrhea is accompanied by disturbances in microbial diversity, how gut microbes are involved in the occurrence of diarrhea remains largely unknown. Here, using a pig model of post-weaning stress-induced diarrhea, we aim to elucidate and enrich the mechanistic basis of diarrhea. We found significant alterations in fecal microbiome, their metabolites, and microRNAs levels in piglets with diarrhea. Specifically, loss of ssc-miRNA-425-5p and ssc-miRNA-423-3p, which inhibit the gene expression of fumarate reductase (frd) in Prevotella genus, caused succinate accumulation in piglets, which resulted in diarrhea. Single-cell RNA sequencing indicated impaired epithelial function and increased immune response in the colon of piglet with diarrhea. Notably, the accumulated succinate increased colonic fluid secretion by regulating transepithelial Cl-secretion in the epithelial cells. Meanwhile, succinate promoted colonic inflammatory responses by activating MyD88-dependent TLR4 signaling in the macrophages. Overall, our findings expand the mechanistic basis of diarrhea and suggest that colonic accumulation of microbiota-produced succinate caused by loss of miRNAs leads to diarrhea in weanling piglets.

摘要

腹泻病是一种常见的健康问题，具有复杂的因果关系。尽管腹泻伴随着微生物多样性的紊乱，但肠道微生物如何参与腹泻的发生仍然很大程度上未知。在这里，我们使用断奶后应激性腹泻的猪模型，旨在阐明和丰富腹泻的机制基础。我们发现腹泻仔猪的粪便微生物组、它们的代谢物和 microRNA 水平发生了显着变化。具体来说，ssc-miRNA-425-5p 和 ssc-miRNA-423-3p 的缺失会抑制 Prevotella 中延胡索酸还原酶 ( frd​​ )的基因表达属，引起仔猪体内琥珀酸积累，从而导致腹泻。单细胞 RNA 测序表明腹泻仔猪结肠上皮功能受损和免疫反应增加。值得注意的是，积累的琥珀酸通过调节上皮细胞中的跨上皮 Cl 分泌增加了结肠液的分泌。同时，琥珀酸盐通过激活巨噬细胞中 MyD88 依赖性 TLR4 信号传导来促进结肠炎症反应。总体而言，我们的研究结果扩展了腹泻的机制基础，并表明由 miRNA 缺失引起的微生物群产生的琥珀酸盐的结肠积累会导致断奶仔猪腹泻。