330 Pediatric microbiome in alopecia areata

Abstract

A cross sectional study of 41 children (11 males and 30 females) ages 4-17 years (22% 4-7 years, 27% 8-11 years, 34% 12-15, 17% 16-17 years) with alopecia areata (AA) and 41 of their sibling ages 4-17 years without AA was conducted. Fecal microbiome was analyzed from stool DNA using shotgun metagenomics. Children were excluded if antibiotics were taken in last 6 months. AA severity ranged from mild to severe (51% had severity of alopecia tool scores in 0-25% range (mild), 12% between 26-49%, 36% between 75-100% (severe). Most common co-morbidity among AA subjects was atopic disease. Diet was predominantly Western/meat eaters (83%) but a small portion were vegan (2%), vegetarian (2%), gluten free (5%) or dairy free (7%). Alpha Diversity was assessed by richness and Shannon index and did not show differences between subjects with AA and their sibling controls. Beta diversity which looks at similarity between samples was assessed by Bray-Curtis and Jaccard distances and showed statistical differences. Based on Jaccard distances, taxa were searched using McNemar’s test for differentially present or absent taxa between the study group and control subjects. 105 taxa showed statistical difference. These included families of Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes and Proteobacteria. Taxa were clustered by similarity and by p-values. When clustering by similarity a few specific bacteria were noted to be highly represented in subjects with alopecia including types of Firmicutes and Proteobacteria. Many more taxa were noted to be highly expressed in sibling controls. When taxa were sorted by P-values the differences showed more enrichment of bacteria in the sibling control group. Differences noted show that pediatric AA is a systemic disease that has effects on hair but also leads to internal changes. These differences may have impact as a diagnostic tool or as a target for therapy. To create either, larger studies will be needed.