Psoriasis is a common chronic inflammatory skin disease, affecting 2-4% of the world population. MicroRNAs (miRNAs) are short non-coding RNAs that regulate expression of the majority of protein-coding genes. We and others have previously identified deregulation in miRNA expression in psoriasis skin. Most of these studies utilized full-depth skin biopsies and thus may have missed the cell-specific miRNA signatures. Here, we analyzed the miRNome of keratinocytes, obtained by sorting of CD45neg cells from the epidermis, from psoriasis patients and healthy skin by next-generation sequencing. We detected differential expression of 104 miRNAs in the psoriatic epidermal cells, including several known and novel miRNAs. MiR-1307-3p, a miRNA previously not associated with psoriasis, was identified as one of the significantly upregulated miRNAs in psoriatic keratinocytes. qRT-PCR analysis on a larger number of samples confirmed its upregulation in psoriatic keratinocytes as compared to keratinocytes from non-lesional skin of psoriasis patients or healthy skin. In primary human keratinocytes and in 3D epidermal equivalents, expression of miR-1307-3p was significantly induced by IL-17A, IL-22 and IL-1β. Overexpression of miR-1307-3p in keratinocytes significantly induced the inflammatory mediators IL-8, IL-6 and CCL20. These results suggest that miR-1307-3p is an amplifier of skin inflammation in psoriasis epidermis. Taken together, we have characterized the miRNome of keratinocytes in psoriasis skin and identified epidermal miRNAs previously not associated with psoriasis. Our results provide a basis for further functional studies of miRNAs in keratinocytes and may lead to
the identification of potential targets for therapy in psoriasis.

MiR-1307 is upregulated in psoriasis keratinocytes and promotes keratinocyte inflammatory response