The interplay of gut microbiota and intestinal motility in gastrointestinal function

Abstract

The relationship between gut microbiota and intestinal motility is crucial for maintaining gastrointestinal health. Intestinal motility refers to the coordinated movements of the digestive tract, essential for effective digestion, nutrient absorption, and timely waste elimination. Recent studies have demonstrated that microbiota play a crucial role not only in the maturation of intestinal motility but also in the ongoing maintenance of established motility patterns. Disruptions in motility can lead to various disorders, such as chronic constipation, irritable bowel syndrome, and chronic idiopathic pseudo-obstruction. Gut microbiota significantly influence intestinal motility through mechanisms like bile acid metabolism and the production of short-chain fatty acids. In patients with diarrhea-predominant irritable bowel syndrome, elevated primary-to-secondary bile acid ratios suggest a complex interaction between gut bacteria and bile acids that can enhance motility via receptors like TGR5. Additionally, the role of interstitial cells of Cajal in facilitating non-neuronal contractions has revolutionized our understanding of motility regulation, highlighting both neural and non-neural factors. Various therapeutic approaches, including prebiotics, probiotics, and fecal microbiota transplantation, have been explored to improve intestinal motility, although their effectiveness has been limited. Advancements in gene-related research and innovative diagnostic methods are vital for a deeper understanding of how the gut microbiome regulates motility. This review synthesizes current knowledge on the interplay between gut microbiota and intestinal motility, emphasizing the need for interdisciplinary research to develop effective treatments targeting gut microbiota for gastrointestinal disorders. By unraveling these complex interactions, we can pave the way for novel therapeutic strategies that enhance intestinal health and improve the quality of life for those affected by motility-related disorders.

Keywords: enteric nervous system; gut microbiota; intestinal motility; muscularis macrophages; smooth muscle.

Fig. 1.

The gut microbiota plays a critical role in modulating intestinal motility via a multifaceted network of signaling pathways. (A) Epithelial and Enteroendocrine Signaling: Dietary fiber is metabolized by gut microbiota into short-chain fatty acids (SCFAs), which activate G-protein coupled receptors (GPR41 and GPR43) on enteroendocrine cells within the epithelium, promoting the release of serotonin (5-HT). Additionally, primary bile acids (BA) undergo transformation by gut microbiota into secondary bile acids, which subsequently activate TGR5 receptors on enteroendocrine cells. These signaling mechanisms significantly impact neuronal activity and intestinal motility. (B) Neuronal Modulation: Components derived from microbes serve as ligands for Toll-like receptors (TLR2 and TLR4) located on enteric neurons, thereby modulating their function. Furthermore, microbial ligands can activate the aryl hydrocarbon receptor (AhR) found in both epithelial cells and enteric neurons, further influencing gut motility. (C) Interaction of Muscularis Macrophages and Interstitial Cells of Cajal: Muscularis macrophages (MMφ) within the muscularis propria engage with interstitial cells of Cajal (ICC), which are essential for regulating smooth muscle contractility and, consequently, intestinal motility. This figure summarizes the integrated mechanisms by which gut microbiota regulates motility in the gastrointestinal tract.