The Role of the Human Microbiome from Symbiosis to Dysbiosis

Abstract

Background: The Human microbiome is a complex symbiotic ecosystem, which is crucial to human health, and which plays vital roles in metabolism and immunity. Its disturbance, which is called dysbiosis, is progressively involved in a variety of chronic diseases.

Objective: This review synthesizes evidence on the microbiome's dual role in health and disease, examining the mechanisms of homeostasis maintenance by a balanced microbiota and the contribution of dysbiosis to several disorders.

Methods: A scientific literature narrative review was carried out, which incorporated results of human cohort studies, animal models, and mechanistic in vitro research to explain the most important microbial functions, host-microbe interactions, and inter-organ communication pathways.

Results: Commensal microbes play an important role in the production of metabolites, training of the immune system, and colonization resistance. Diversity loss, pathobiont growth, and metabolite shift are caused by dysbiosis as a result of antibiotics and diet. This disturbance is associated with disorders such as IBD, diabetes, and neurodegenerative diseases. Microbial metabolites and components are two sided swords, mediating their systemic effects via gut-brain, gut-lung and gut-skin axes through immune, neural and metabolic pathways.

Conclusion: Microbial harmony is essential in health, and its imbalance is the cause of chronic illness, so the microbiome is an ideal candidate of new diagnostics, therapeutics, and personal approaches to its recovery.