Gut Microbiota and Inflammatory Diseases: Emerging Insights and Therapeutic Perspectives. A Report From the Spanish Inflammatory Diseases Network.

The gut microbiota constitutes a highly complex ecosystem that plays a pivotal role in maintaining human health and modulating the immune response. Dysbiosis, an imbalance in the composition of gut microbiota, has been linked to the development and progression of multiple immune-mediated inflammatory diseases (IMIDs) and allergic disorders. Advances in sequencing and bioinformatics have enabled a deeper understanding of microbial diversity and function, revealing the crucial role of metabolites such as short-chain fatty acids (SCFAs) and secondary bile acids in sustaining epithelial integrity and immune tolerance. Altered microbiota profiles are associated with increased intestinal permeability, systemic inflammation, and autoimmune conditions including multiple sclerosis, rheumatoid arthritis, and inflammatory eye disease. Early-life establishment of microbiota is also critical, influencing susceptibility to asthma, food allergy, and other atopic conditions, such as drug hypersensitivity. Emerging therapeutic strategies aim to restore microbial balance through interventions such as the administration of probiotics, prebiotics, symbiotics, or postbiotics and fecal microbiota transplantation. Preliminary clinical evidence suggests these interventions may enhance barrier function, modulate inflammation, and improve clinical outcomes, although methodological heterogeneity and limited sample sizes constrain their application. Specific findings highlight that modulation of SCFAs and targeted bacterial taxa may influence disease activity and response to treatment. Future research should focus on identifying disease-specific microbial signatures, optimizing therapeutic formulations, and standardizing protocols for microbiota-based interventions. Integrating multiomics analyses and artificial intelligence will be essential if we are to develop predictive biomarkers and personalized therapies. Modulation of the microbiota is therefore positioned as a promising avenue in the prevention and management of IMIDs and allergic diseases.