Skin commensals have been suggested to have a role in the pathogenesis of atopic dermatitis (AD), and bacteriotherapy has attracted attention. Here, we investigated the bacterial dynamics of AD patients treated by bleach baths and identified 13 bacterial species as candidates for biotherapy. Skin swab samples were collected monthly from AD patients for 6 months before and after 3-month bleach baths and analyzed using 16S rRNA gene sequencing. Multiple regression analysis using objective SCORing AD (o-SCORAD) and 34 representative bacterial species revealed that two bacterial species, Staphylococcus aureus and Staphylococcus hominis, were positively correlated with o-SCORAD, while 13 species of bacteria were inversely correlated. To validate these results, we examined a cross-sectional cohort study consisting of 3128 samples from 167 AD patients treated with other therapeutic options and found that, consistent with the previous results, the bacterial abundance of the 2 “positive” species and the 13 “inverse” species showed positive and negative parallel fluctuations with disease activities, respectively. These observations suggested that at least some of 13 bacterial species possess inhibitory effects on skin inflammation through interaction with “positive” bacteria. To verify their suppressive effects on dermatitis, a mixture of 10 of the 13 bacteria was topically-applied to MC903-induced AD mice that had been applied with “positive” bacteria. Mice treated with a mixture of 10 bacteria cancelled the exacerbation by the “positive” species and showed more significant suppression of inflammation than mice treated with vancomycin alone. Thus, the 13 bacterial species identified in this study may provide a potential tool as biotherapeutic strategies for AD.

ESDR077 - The thirteen bacterial species inversely correlated with disease activities of atopic dermatitis in human showed a biotherapeutic potential based on their suppressive effects in mice

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.