The Gut–Skin Axis in Autoimmune Dermatology: Role of Microbiome and Immune Pathways

The gut-skin axis has become an important conceptual framework to identify a relationship between gut microbiota and skin immunity, particularly in autoimmune dermatologic diseases. This narrative review aims to summarize recent data examining how gut dysbiosis, characterized by low microbial diversity and disruption of each of the gut's microbial communities, plays a role in the pathogenesis and pathophysiology of psoriasis, systemic lupus erythematosus (SLE), alopecia areata, and scleroderma. We consider different pathways, including but not limited to increased intestinal permeability ("leaky gut"), Th17/Treg balance, the presence of and/or development of pro-inflammatory cytokines, and molecular mimicry, for how gut dysbiosis drives immune dysregulation in the skin. Clinical and translational evidence of microbiome-based therapies with probiotics, prebiotics, and fecal microbiota transplantation (FMT) has been shown not only to improve disease severity but also reduce systemic inflammation and restore gut microbiome diversity and community structure. Specific AMR therapies have indicated differences in PASI, SLEDAI, and inflammatory markers such as IL-6 and TNF-α. This narrative review strongly affirms that ambient need for more precision-based solutions to prevent and treat autoimmunity using a combination of multi- omics, gut microbiome profiling, as well as artificial intelligence (AI)-driven individualized solutions. Ultimately, the gut–skin axis depicts autoimmune skin diseases from single dermatologic disease classifications to systemic immune diseases grounded in gut health, offering new possibilities for diagnosis, intervention, and disease modulation.