Role of an imbalanced miRNAs axis in pathogenesis of psoriasis: novel perspectives based on review of the literature.

Background: Specific profile of microRNAs (miRNAs, miR) expressed in psoriasis has been identified in the past few years, while the studies on roles and molecular mechanisms of these miRNAs are still on the way. In our previous study, four specific miRNAs (miR-31, miR-203, hsa-miR-99a and miR-125b) were found to be specifically altered in psoriatic lesions.We therefore conducted a systematic literature review in this study to reveal the role of these miRNAs in the pathogenesis of psoriasis in order to inform future research.

Methods: The related articles indexed in PubMed (MEDLINE) database were searched and analyzed. We identified eligible studies related to the mechanism research of miR-31, miR-203, hsa-miR-99a and miR-125b in psoriasis or psoriatic lesional skin from inception up to July 2016. The experts in the field of miRNAs and Psoriasis were involved in analysis process.

Results: Both miR-31 and miR-203 are dramatically upregulated in psoriatic lesions. The former plays the pro-proliferative, pro-differentiative and pro-inflammatory roles and the latter holds the potentials for anti-proliferation, pro-inflammation and pro-differentiation in psoriatic keratinocytes. Conversely, both hsa-miR-99a and miR-125b are significantly downregulated in psoriatic skin. These two miRNAs are able to inhibit proliferation while promote differentiation of psoriatic keratinocytes, and miR-125b can also suppress inflammation in psoriatic lesions. By analyzing the contexts related to these miRNAs, we found that each of them does not act alone but rather work in concert with other miRNAs. The imbalance between miR-31/miR-203and hsa-miR-99a/miR-125b may contribute to the intense proliferation and abnormal differentiation of psoriatic keratinocytes, which is a characteristic of pathogenesis of psoriasis.

Conclusion: An imbalanced miRNAs axis was for the first time outlined. Apparently, upregulation of miR-31/miR-203 and downregulation of hsa-miR-99a/miR-125b work together in concert to facilitate the development of psoriasis pathogenesis. Further work in this field holds the potentials to open a new way to study psoriasis.