Transcriptome of inflammatory myeloid DCs in psoriasis. Homo sapiens

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. Overall design: 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.