Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease of the apocrine gland-rich (AGR) skin regions with a well characterized Th1/17 cytokine milieu. According to current literature data, keratinocytes are crucial drivers of the first pathogenic steps of HS. However, the possible role of permeability barrier alteration, as KC activating event, has not been studied in detailed in HS. Our main focus was to study the permeability barrier of non-lesional HS (HS NL) and lesional HS (HS L) skin and compare them to that of the healthy AGR region. We investigated the major permeability barrier elements, namely the stratum corneum (SC) and tight junctions (TJ) both at the mRNA (by RT-qPCR) and protein (by immunohistochemistry) levels. Among the SC components, molecules related to cornified envelope formation (FLG, LOR, KRT1, KRT10, LCE1F, SPRR2A, TGM5), corneocyte desquamation (KLK5, KLK7, KLK14), and (corneo)desmosome organization (DSG1, DSC1, PKP1, CDSN) were analyzed along with TJ molecules (OCLN, CLDN1, CLDN23). The function of the permeability barrier was also investigated by TEWL measurement. At the gene level, in HS NL skin only three molecules (LCE1F, SPRR2A, CLDN23), while in HS L skin most of the molecules showed significantly altered expression compared to AGR skin. However, at the protein level, in HS NL skin the expression of the investigated molecules was not different from normal skin, while HS L showed only slight and not consequent differences (KRT1 and KLK5 were decreased, KLK7, KRT6 and DSG1 were increased). Functional studies showed no significant differences in the TEWL of the three sample groups. The almost missing differences in HS NL and the detected slight barrier alterations in HS L skin suggest that permeability barrier is not significantly affected in HS skin, and that permeability barrier alterations are not the driver factors of KC’s activation in this disease. Funding: NKFIH K-128250, NKFIH PD-131689, EFOP-3.6.1-16-2016-00022

ESDR355 - Permeability barrier characteristics of hidradenitis suppurativa

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.