Transcriptome of inflammatory myeloid DCs in psoriasis

Background: Previous work has identified CD11c+CD1c- dendritic cells (DCs) as the major ”inflammatory” dermal DC population in psoriasis vulgaris and CD1c+ DCs as the “resident” cutaneous DC population. Objective: To further define molecular differences between these two myeloid dermal DC populations. Methods: Inflammatory and resident DCs were single-cell sorted from psoriasis lesional skin biopsies, and gene array expression profiling was performed. Results were confirmed with RT-PCR, flow cytometry, immunohistochemistry, and double label immunofluorescence. Pooled human keratinocytes were cultured for functional studies. Results: TNF-related apoptosis-inducing ligand (TRAIL), Toll-like receptors (TLRs) 1 and 2, S100A12/EN-RAGE, CD32, and many other inflammatory products were selectively expressed in inflammatory DCs than in resident DCs. Flow cytometry and immunofluorescence confirmed higher protein expression on CD1c- versus CD1c+ DCs. TRAIL receptor, death receptor 4 (DR4), was expressed on basal keratinocytes and blood vessels, and in vitro culture of keratinocytes with rh-TRAIL induced CCL20 leukocyte chemokine. Conclusion: CD11c+CD1c- inflammatory DCs in psoriatic lesional skin express a wide range of inflammatory molecules compared to skin resident CD1c+ DCs. Some molecules made by inflammatory DCs, including TRAIL, could have direct effects on keratinocytes or other skin cell types to promote disease pathogenesis. Shave biopsies were cultured overnight in dispase to remove the epidermis. Dermis was cultured for 36-48 hours to obtain dermal single cell suspensions. These cells were stained with HLA-DR, CD11c, BDCA-1 (DCs) and FACS-sorted into HLA-DR+11c+BDCA-1+, HLA-DR+11c+BDCA-1- populations into Trizol. RNA was extracted and processed for microarray. 2 dependent groups.