Microbial Metabolites as Systemic Signaling Molecules: Integrating Metabolism, Immunity, and Organ Crosstalk in Health and Disease

The gut microbiota produces a wide variety of metabolites that are essential for host-microbe communication and play a critical role in regulating host physiology, metabolism, and immunity. Among the most important of these metabolites are Short-Chain Fatty Acids (SCFAs), bile acid derivatives, tryptophan metabolites, polyamines, vitamins, and polyphenol-derived compounds. These bioactive metabolites regulate energy homeostasis, glucose and lipid metabolism, intestinal barrier integrity, immune signaling, and gene expression. Moreover, they influence systemic physiological processes, including cardiovascular and neuroendocrine functions, while playing a pivotal role in regulating hepatic and adipose tissue metabolism and maintaining intestinal homeostasis. Dysbiosis-induced alterations in microbial metabolic activity have been associated with the development of several chronic diseases, including obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease, cardiovascular diseases, cancer, autoimmune disorders, and neurological conditions. Consequently, therapeutic strategies aimed at modulating microbial metabolism, such as probiotics, prebiotics, postbiotics, dietary interventions, faecal microbiota transplantation, and synthetic biology-based approaches, are being extensively investigated, with microbial metabolites emerging as promising pharmacological targets. Despite these advances, significant challenges remain regarding their mechanistic understanding, standardisation, safety, and successful translation into clinical practice. The integration of multi-omics technologies, artificial intelligence, and precision microbiome-based interventions is expected to accelerate the development of personalized therapeutic strategies and enhance the clinical applicability of microbial metabolite research.