Human Microbiome as an Immunoregulatory Axis: Mechanisms, Dysbiosis, and Therapeutic Modulation

The human microbiome plays a central role in modulating the immune system and maintaining immunophysiological homeostasis, contributing to the prevention of immune-mediated diseases. In particular, the gut microbiota is a key ecosystem for immune system maturation, especially in early life. This review aimed to analyze the molecular and cellular mechanisms linking the microbiome to immune and neuronal functions, as well as the impact of dysbiosis and emerging therapeutic strategies targeting the microbiome. The analysis was based on scientific databases, prioritizing studies published since 2000, with special emphasis on the past decade. The microbiome influences immune signaling through microorganism-associated molecular patterns (MAMPs) and pattern recognition receptors (PRRs), including Toll-like receptors (TLRs). Additionally, microbial metabolites-such as short-chain fatty acids (SCFAs), tryptophan derivatives, and secondary bile acids-exert significant immunomodulatory effects. The intestinal epithelial barrier is also described as an active immunological interface contributing to systemic regulation. The literature highlights innovative therapies, including fecal microbiota transplantation (FMT), probiotics, and microbiome editing with CRISPR-Cas technologies. These strategies aim to restore microbial balance and improve immune outcomes. The growing body of evidence positions the microbiome as a valuable clinical and diagnostic target, with significant potential for application in personalized medicine.