Analysis of the gut microbiota in alopecia areata: identification of bacterial biomarkers

Abstract

Background Alopecia areata is a T‐cell‐mediated autoimmune disease with an unknown etiopathogenesis. Gut microbiota has been revealed as a key modulator of systemic immunity. Objective To determine whether patients affected by alopecia universalis present differences in gut bacteria composition compared with healthy controls and investigate possible bacterial biomarkers of the disease. Methods We conducted a cross‐sectional study that involved 15 patients affected by alopecia universalis and 15 controls. Gut microbiome of the study subjects was analysed by sequencing the 16SrRNA of stool samples. We searched for bacterial biomarkers of alopecia universalis using the linear discriminant analysis effect size (LEFse) tool. Results In total, 30 study subjects (46.6% female; mean [SD] age, 40.1 [9.8] years) were enrolled. Neither alpha (Shannon diversity index 5.31 ± 0.43 vs. 5.03 ± 0.43, P 0.1) or beta diversity (ADONIS P value: 0.35) of gut microbiota showed statistically significant differences between cases and controls. In patients affected with alopecia, we found an enriched presence (LDA SCORE > 2) of Holdemania filiformis, Erysipelotrichacea, Lachnospiraceae, Parabacteroides johnsonii, Clostridiales vadin BB60 group, Bacteroides eggerthii and Parabacteroides distasonis. A predictive model based on the number of bacterial counts of Parabacteroides distasonis and Clostridiales vadin BB60 group correctly predicted disease status in 80% of patients (AUC 0.804 (0.633–0.976), P 0.004). Conclusion Alopecia universalis does not seem to affect broadly gut microbiota structure. Bacterial biomarkers found associated with the disease (Holdemania filiformis, Erysipelotrichacea, Lachnospiraceae, Parabacteroides johnsonii, Eggerthellaceae, Clostridiales vadin BB60 group, Bacteroides eggerthii and Parabacteroides distasonis) should be further studied as they could be involved in its pathophysiology or be used as diagnostic tools.

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

“…This also supports the hypothesis of the potential role of the gut microbiome in the pathophysiology of alopecia areata. Some gut bacterial differences were identified in alopecia areata patients, without major differences [127]. Based on the limited studies found in literature, a clear association between gut dysbiosis and alopecia areata has not yet been determined.…”

Parabacteroides distasonis: intriguing aerotolerant gut anaerobe with emerging antimicrobial resistance and pathogenic and probiotic roles in human health

“…Notably, Moreno-Arrones et al 117 found that patients with alopecia areata -an autoimmune disease mediated by T cells -had higher abundances of P. distasonis in their gut microbiota (LDA score > 2). In conjunction with Clostridiales vadin BB60 group, P. distasonis could correctly predict alopecia areata status in 80% of patients, indicating that P. distasonis could be involved in the pathophysiology of alopecia areata.…”

“…In conjunction with Clostridiales vadin BB60 group, P. distasonis could correctly predict alopecia areata status in 80% of patients, indicating that P. distasonis could be involved in the pathophysiology of alopecia areata. 117 However, whether these findings indicate a causative relationship between the abundance of P. distasonis in the gut and alopecia areata and if the bacterium presence serves as a biomarker for the disease remains to be elucidated. At the genus level, elevated systemic antibodies toward commensal gut P. distasonis and P. merdae have been reported to be consistently increased in Familial Mediterranean fever (FMF, which is an autoinflammatory condition characterized by acute, self-limiting episodes of fever and serositis and chronic subclinical inflammation in remission), irrespective of disease activity (remission, 2180 ± 1150 and 2508 ± 1241; vs. flare, 2383 ± 1207 and 2393 ± 1069) compared to controls (658 ± 161 and 995 ± 363, for P. distasonis and P. merdae , respectively).…”

Exploring the human hair follicle microbiome*

“…[8][9][10][11] However, compared with the extensively researched skin surface microbiome, [12][13][14][15][16] the specific microbiome of human hair follicles (HFs) has been relatively under-investigated, beyond pathogen-induced bacterial or fungal folliculitis, 17 hidradenitis suppurativa (HS), [18][19][20][21] folliculitis decalvans 22 and acne vulgaris. [23][24][25][26][27][28] Yet, a microbiome-centred perspective on translational human hair research is becoming ever more important, as hair growth disorders that had not previously been viewed from this perspective, such as alopecia areata (AA) 29,30 and androgenic alopecia, 31 have come under microbiological scrutiny. Also, mouse in vivo studies have shown that ingestion of certain Lactobacillus species may reduce perifollicular neurogenic inflammation 32 and impact on the overall hair phenotype, 33 and that intestinal dysbiosis can correlate with alopecia.…”