Psoriasis is a common heterogeneous inflammatory skin disease with a complex pathophysiology and limited treatment options. Here we performed proteomic analyses of human psoriatic epidermis and found S100A8-S100A9, also called calprotectin, as the most upregulated proteins, followed by the complement component C3. Both S100A8-S100A9 and C3 are specifically expressed in lesional psoriatic skin. S100A9 is shown here to function as a chromatin component modulating C3 expression in mouse and human cells by binding to a region upstream of the C3 start site. When S100A9 was genetically deleted in mouse models of skin inflammation, the psoriasis-like skin disease and inflammation were strongly attenuated, with a mild immune infiltrate and decreased amounts of C3. In addition, inhibition of C3 in the mouse model strongly reduced the inflammatory skin disease. Thus, S100A8-S100A9 can regulate C3 at the nuclear level and present potential new therapeutic targets for psoriasis.

Psoriasis is a common inflammatory skin disease with limited treatment options that is characterized by a complex interplay between keratinocytes, immune cells, and inflammatory mediators. MicroRNAs (miRNAs) are regulators of gene expression and play critical roles in many human diseases. A number of miRNAs have been described to be up-regulated in psoriasis, but their causal contribution to disease development has not been demonstrated. We confirm that miR-21 expression is increased in epidermal lesions of patients with psoriasis and that this leads to reduced epidermal TIMP-3 (tissue inhibitor of matrix metalloproteinase 3) expression and activation of TACE (tumor necrosis factor-α-converting enzyme)/ADAM17 (a disintegrin and metalloproteinase 17). Using patient-derived skin samples and mouse models of psoriasis, we demonstrate that increased miR-21 may be a consequence of impaired transcriptional activity of Jun/activating protein 1 (AP-1), leading to activation of the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (Stat3) pathway. Inhibition of miR-21 by locked nucleic acid (LNA)-modified anti-miR-21 compounds ameliorated disease pathology in patient-derived psoriatic skin xenotransplants in mice and in a psoriasis-like mouse model. Targeting miR-21 may represent a potential therapeutic option for the treatment of psoriasis.

Biologic therapy was effective and safe for the majority of our patients with HCV and HBV infection, although there may be a risk of reactivation or aggravation. We describe the first cases to receive ustekinumab. The use of biologics should be limited to those cases in which the risk-benefit ratio is justified.

Paradoxical psoriasiform reactions to anti-tumor necrosis factor α (TNFα) agents have been described. We aimed to study the association between these reactions and polymorphisms in genes previously associated with psoriasis or other autoimmune diseases. A total of 161 patients with plaque-type psoriasis treated with anti-TNFα drugs were genotyped for 173 single-nucleotide polymorphisms (SNPs) using the Illumina Veracode genotyping platform. Among the 161 patients, 25 patients developed a paradoxical psoriasiform reaction consisting of a change in morphology, mostly to guttate psoriasis (88%). These lesions developed 9.20±13.52 months after initiating treatment, mainly with etanercept (72%). Psoriasis type and a Psoriasis Area and Severity Index (PASI) 75 response to treatment were not associated with lesions. Multivariate logistic regression revealed that five SNPs (rs11209026 in IL23R, rs10782001 in FBXL19, rs3087243 in CTLA4, rs651630 in SLC12A8 and rs1800453 in TAP1) were associated with paradoxical reactions. This is the first study to show an association between genetic polymorphisms and paradoxical reactions in patients with psoriasis treated with anti-TNFα drugs.The Pharmacogenomics Journal advance online publication, 21 July 2015; doi:10.1038/tpj.2015.53.

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