What's New in the Pathophysiology of Alopecia Areata? The Possible Contribution of Skin and Gut Microbiome in the Pathogenesis of Alopecia – Big Opportunities, Big Challenges, and Novel Perspectives

The term “microbiome” defines the collective genome of all commensal, symbiotic, and pathogenic microbes living in the human body. The composition of microbiota in the gut and skin is influenced by many factors such as the stage of life, nutrition, lifestyle, and gender. In the past few years, several scientific papers have demonstrated an implication of microbiota in many immune-mediated diseases, for example, diabetes, ulcerative colitis, and multiple sclerosis. The alterations in the proportion of gut microbiota have emerged as potential immunomodulators with the capacity to induce physiologic as well as pathologic immune responses against the human body, causing inflammation and destruction of tissues or organs. The microbiota influences the differentiation of adaptive immune cells not only in the gut but also in the skin. Alopecia areata (AA) is a dermatologic disorder which causes hair loss in most cases resistant to treatment. There are some clinical and experimental evidences indicating that AA is the demonstration of autoimmune attack against hair follicles. The factors that may implicate such an autoimmunity in AA still remain unknown. Despite more and more evidences demonstrate that human microbiome plays a key role in human health and diseases, to the best of our knowledge, no study has been conducted to analyze an implication of microbiome in the pathogenesis of AA. Undoubtedly, there is a need to performing a study which might explain the involvement of gut and skin microbiota in the unclear pathogenesis of AA and lead to alternative treatment options for numerous patients suffering from current treatment limitations.