A Conceptual Review of Gut, Skin, and Oral Microbiota in Autoimmune Bullous Diseases: From Dysbiosis to Therapeutic Potential.

Autoimmune bullous diseases (AIBDs), including pemphigus and bullous pemphigoid, are chronic inflammatory skin disorders characterized by dysregulated immune responses mediated by autoantibodies that target adhesion molecules in the skin and mucous membranes. Emerging evidence highlights the pivotal role of host microbiota dysbiosis in AIBDs pathogenesis, offering novel insights into disease mechanisms and therapeutic strategies. This review systematically synthesizes the current findings on gut, skin, and oral microbiota alterations in AIBDs, emphasizing their contributions via the gut-skin axis, microbial metabolites, and pathogen-host interactions. Key innovations include uncovering how specific pathogenic and commensal microbiota influence disease progression through intriguing skin inflammation and direct barrier impairment. Notably, while some microbiota changes overlap with other dermatoses, AIBDs exhibit distinct microbial signatures associated with their unique autoimmune mechanisms targeting adhesion molecules. Furthermore, we explore microbiota-targeted therapies, such as antibiotics, probiotics, and fecal microbiota transplantation, and demonstrate their potential to restore microbial homeostasis and improve clinical outcomes. By integrating multi-omics evidence and clinical data, this review bridges mechanistic insights with translational applications, proposing microbiota modulation as a promising adjunctive therapy for AIBDs. Our analysis identifies critical research gaps, including the need for longitudinal studies and personalized microbial interventions, positioning this review at the forefront of microbiome-inflammation-autoimmunity research.