Laser capture microdissection followed by next-generation sequencing identifies disease-related microRNAs in psoriatic skin that mirror the systemic psoriatic miRNome

Psoriasis is a systemic disease with cutaneous manifestations. MicroRNAs (miRNAs) are non-coding RNA molecules that are differentially expressed in psoriatic skin, however; only few miRNAs have been localized to specific cells or regions of psoriatic lesions. We used laser capture microdissection (LCM) and next-generation sequencing to study the specific miRNA expression profiles in the epidermis (Epi) and dermal inflammatory aggregates (RD/ICs) of psoriatic skin. We identified 24 deregulated miRNAs in the Epi and 37 deregulated miRNAs in the RD/ICs of lesional psoriatic skin compared with non-lesional psoriatic skin (FCH>2, FDR<0.05). Interestingly, 9 of the 37 miRNAs, including miR-193b and miR-223 that have recently been described as deregulated in circulating peripheral blood mononuclear cells (PBMCs) from patients with psoriasis. Using flow cytometry and qRT-PCR, miR-193b and miR-223 were found to be expressed in Th17 cells. In conclusion, we demonstrate that LCM combined with small RNA sequencing provides a robust strategy to explore the global miRNA expression in the epidermal and dermal compartments of psoriatic skin. Furthermore, our results indicate that the altered local miRNA changes seen in the RD/ICs is reflected in the circulating immune cells, altogether emphasizing that miRNAs may contribute to a systemic component in the pathogenesis of psoriasis. Overall design: Examination of the global miRNA expression in epidermis (Epi) and dermis (RD/ICs) of paired (non-lesional vs. lesional) psoriatic skin using a combination of laser-capture microdissection and barcoded small RNA sequencing