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

Abstract

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.

Gut–Skin Axis: Current Knowledge of the Interrelationship between Microbial Dysbiosis and Skin Conditions

“…Induction of this pathway can cause abnormal growth of hair follicle cells and can even progress into hair loss. Furthermore, dysbiosis of the gut microbiome provokes other diseases through manipulation of the T cell activity near and distant to the site of induction [ 296 ]. A case report revealed hair growth in two patients with alopecia areata who were treated with a fecal microbiota transplant (FMT) [ 128 ].…”

Current controversies in trichology: a European expert consensus statement

“…In seborrhoeic dermatitis, some studies show that decreasing specific microorganisms of our skin might be beneficial for the course of the disease, 58 while other papers have found healthy bacteria that might protect against disease development. 59 In alopecia areata, the role of the skin microbiome is still unclear 60,61 and, even though some bacterial biomarkers are associated with the disease, further studies are necessary to prove their involvement in the pathophysiology of the disease and to test its potential as a diagnostic tool.…”

Influência da Disbiose na Patologia do Couro Cabeludo

“…A composição da microbiota cutânea varia nas diferentes regiões do tegumento, dependendo da idade e sexo do indivíduo, da predisposição genética e de fatores externos como a exposição solar, estilo de vida e uso de cosméticos. [5][6][7][8] Estes microorganismos são relevantes na manutenção de funções da fisiologia da pele e mucosas, tais como a barreira cutânea, imunidade, regulação e produção de citocinas e limitação da proliferação de patógenos.…”