The skin forms an interface between the body and the environment and provides distinct niches for microbial communities. Next-generation-sequencing used to characterize the cutaneous microbiome in psoriasis patients revealed an over-representation of Proteobacteria and a reduction of Actinobacteria in lesional skin, suggesting that the development of psoriatic plaques might be linked to specific alterations in the cutaneous microbiome and successful treatment could help to normalize the microbiome even before clinical parameters improve. Hence, we analyzed the microbiome in swabs from lesional and non-lesional skin of psoriasis patients before and at different time points after treatment with FAE or TNF, IL-17 receptor, IL-12/23 and PDE4 inhibitors. Whereas a significant reduction in the relative abundance of Proteobacteria and an increase in Actinobacteria was detectable 4-8 weeks after the start of treatment with TNF and PDE4 inhibitors or FAE, coinciding with clinical improvement, IL-12/23 blockade did not result in alterations of the cutaneous microbiome. In psoriasis patients receiving inhibitors of the IL-17 pathway a significant reduction in the relative abundance of Proteobacteria was detectable immediately after the first administration of the drug, in most patients even before a PASI-75 response was observed. Interestingly, psoriasis patients not responding to TNF blockade were characterized by a higher relative abundance of Firmicutes at baseline compared to responders, whereas patients who did not benefit from treatment with PDE4 inhibitors showed a high abundance of Staphylococci at baseline. In contrast to patients responding to PDE4 inhibitors, non-responders did not exhibit a reduction in Proteobacteria at week 4 of treatment. Thus, the composition of the microbiome or early alterations in the relative abundance of particular bacteria upon treatment might help to predict responses to a given therapy.

ESDR152 - Normalization of the microbiome in psoriatic skin after treatment with fumaric acid esters (FAE), TNF, IL-17 or PDE4-inhibitors but not IL-12/23 blockade

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.