Multi-plex assay based quantification of anti-microbial peptides as potential biomarkers for atopic dermatitis patient stratification

Treatment of patients, diagnosed with moderate-to-severe atopic dermatitis, include biologics and JAK inhibitors. However, treatment response varies in patients resulting in treatment failures. Therefore, biomarkers to predict therapy response are required. Since up to 20% of children are affected by atopic dermatitis it is wanted to use non-invasive sampling techniques for biomarker identification. Tape stripping provides a non-invasive technique to collect such samples.The pathophysiology of atopic dermatitis is characterized by Th2 polarization. Key cytokines, i.e. IL-4, IL-13, and IL-31, in the skin impact protein expression of keratinocytes, including anti-microbial peptides, linking them directly to the underlying immune profile, which is targeted by afore mentioned biologics and JAK inhibitors. Therefore, we hypothesized that anti-microbial peptides can be used as potential biomarkers to predict treatment outcome. We collected anti-microbial peptides using tape strips from atopic dermatitis patients, as well as healthy controls at different body positions. Sampling was performed at two different research institutions. For analysis we developed a multiplex assay, which allows for parallel quantification of hBD2, hBD3, S100A7, S100A8/9, RNAse7, LL-37, dermicidin, and GAPDH. After validation of the assay, we found marked alterations in hBD2, hBD3, RNAse7, and S100A8/9 levels in skin of patients with atopic dermatitis as compared to healthy controls. Further, we correlated concentrations with severity of disease, as measured by EASI and SCORAD. In summary, we show that anti-microbial peptides can be sampled using non-invasive tape stripping technique and quantification using our novel developed multi-plex assay provides robust results, allowing usage of anti-microbial peptides as potential biomarkers in the future.