Bridging two worlds: Host Microbiota crosstalk in health and dysregulation

The gut microbiota plays a crucial role in various physiological functions, such as the production of microbial compounds and maintaining homeostatic equilibrium by complex host-microbial interactions. However, any shift in the constitution and diversity of the microbiota or abnormal interaction with the host can prompt the development of dysbiosis. This review thus illustrates that microbial metabolites, notably short-chain fatty acids, tryptophan metabolites, bile acids, and polyamines, exert significant regulatory effects on innate and adaptive immunological processes, immune response and intestinal barrier integrity through specific receptor activation, involving TLRs, NODs, GPCRs, nuclear receptors, and Wnt/β-catenin. It further explores the disruption of host signalling pathways, caused by dysbiosis, promoting the transcription of specific genes and activating pro-inflammatory pathways. Consequently, this suggests that microbiota acts beyond general health, eventually contributing to gastrointestinal, metabolic, and neurological disorders. Lastly, this review highlights therapeutic approaches required to restore balance and uphold physiological balance.