(1) Background: Given the autoimmune nature of Alopecia Areata (AA) and the immunomodulatory properties of probiotics, this trial was conducted to evaluate the efficacy of a probiotic mixture, consisting of Lactobacillus rhamnosus and Bifidobacterium longum strains, as an adjuvant treatment in a group of AA patients. (2) Method: This study was a 24-week, randomized, double-blind, placebo-controlled clinical trial. Twenty-six patients with AA were included in this study, and their clinical progression, along with changes in gut and skin microbiota, were analyzed. (3) Results: A higher proportion of AA patients treated with the probiotic formula showed improvement compared to the placebo group, based on both the reduction in the number of AA plaques (56% vs. 30%) and the affected scalp surface area (45% vs. 20%). For “activity”, “inactivity”, and “regrowth”, an improvement in 55%, 67%, and 55% of patients was, respectively, observed in the probiotic group, compared to 50%, 40%, and 30% in the placebo group. No changes were observed in the gut microbiota during the intervention period. Regarding skin microbiota, changes were detected in the probiotic group, with reductions in characteristic genera during the study. (4) Conclusions: To our knowledge, this is the first clinical trial assessing the efficacy of a probiotic product in patients with AA. This probiotic mixture in a routine clinical practice setting appears to improve the course of patients. In addition, the skin microbiota of scalp lesions was modified using the probiotic treatment.

(1) Background: Considering the autoimmune nature with genetic predisposition of alopecia areata, and the immunomodulatory properties of some probiotics, the present study was conducted in patients with alopecia areata. (2) Method: A 24-weeks randomized, double-blind, placebo-controlled clinical trial to evaluate the efficacy of an oral probiotic intake in severity of alopecia areata and the effect on skin and gut microbiota. 3) Results: The number of alopecia areata plaques decresed in 56% of patients in the probiotic group vs. 30% in the placebo group. Patients with improvement on the affected skin surface area, showed a results of 45% and 20% in probiotic and placebo groups, respectively. For "activity", "inactivity” and "regrowth", an improvement in 55%, 67% and 55% of patients was respectively observed in the probiotic group, compared to 50%, 40% and 30% in the placebo group. No changes were observed in the gut microbiota during the intervention period. Regarding skin microbiota, changes were detected in the probiotic group, with reductions in characteristic genera during the study. (4) Conclusions: To our knowledge, this is the first clinical trial assessing the efficacy of a probiotic in patients with alopecia areata. This probiotic mixture improves the course and modify the skin microbiota of these patients.

Alopecia areata (AA) is a chronic autoimmune disease characterized by non-scarring hair loss, where pathogenesis is closely linked to the collapse of hair follicle immune privilege and dysregulated T-cell responses. Increasing evidence suggests that gut dysbiosis may contribute to systemic immune alterations relevant to autoimmune disorders, yet its role in AA remains largely unexplored. In this study, we aimed to characterize the gut microbiota composition of AA patients and evaluate its potential as a biomarker for disease discrimination. Fecal samples from patients with AA and healthy controls were analyzed by 16S rRNA sequencing and processed through QIIME2 and MicrobiomeAnalyst platforms. Diversity metrics, differential abundance, and microbial network correlations were assessed, and supervised machine learning models were developed to classify AA versus control profiles. Our results revealed distinct microbial signatures in AA, with enrichment of pro-inflammatory genera such as Methanobrevibacter, Collinsella, and Ruminococcus gnavus, and depletion of immunoregulatory commensals, including Faecalibacterium and Eubacterium eligens group. Network analyses showed more complex microbial interactions in AA, and Random Forest models achieved 92% accuracy in discriminating AA from controls. These findings indicate that gut dysbiosis may play a role in AA pathogenesis, providing potential diagnostic biomarkers and supporting microbiota-targeted interventions as future therapeutic strategies.