Serum Levels of miR-146a in Patients with Psoriasis

Background Psoriasis is an immune-mediated disease with interactions between genetic and environmental factors. An increasing number of studies are demonstrating the importance of microRNAs (miRNAs) in the pathogenesis of psoriasis. miR-146a, a dominant negative regulator of inflammation, has been consistently reported as overexpressed in the skin and peripheral blood mononuclear cells (PBMCs) of patients with psoriasis. Expression and/or function of this miRNA is highly influenced by genetic variations, some of which have already been associated with susceptibility to psoriasis. Objective We sought to study the importance of miR-146a in patients with moderate-to-severe psoriasis and to understand the impact of rs57095329 and rs2910164 polymorphisms in a psoriatic Portuguese population. Methods miR-146a circulating levels were quantified using molecular biology techniques in 99 patients with moderate-to-severe psoriasis (35 female, 64 male; age 47.4 ± 10.9 years) and 78 healthy individuals (52 female, 26 male; age 42.4 ± 10.1 years). miRNA expression was correlated with clinicopathological features as well as with genetic data such as the presence of human leukocyte antigen (HLA)-C*0602 allele and two miR-146a polymorphisms (rs2910164 and rs57095329). Results miR-146a serum levels were 3.7-fold higher in patients with psoriasis than in controls ( p < 0.0001, area under the curve [AUC] 0.75; 95% confidence interval [CI] 0.66–0.83). Of note, miR-146a circulating levels positively correlated with Psoriasis Area and Severity Index ( p < 0.05) and body surface area ( p < 0.05) indexes. No variations in miR-146a levels were observed with rs2910164 and rs57095329 genotypes. Conclusion Circulating miR-146a levels were upregulated in patients with psoriasis, especially in those with active disease. To the best of our knowledge, this is the largest study with a homogenous psoriasis population, and our data could shed light on the pathogenesis of psoriasis, paving the way for new avenues for disease treatment.