TGF- Targeted by miR-27a Modulates Anti-Parasite Responses of Immune System

Background: Immune cells and their secreted cytokines are known as the first barrier against patho-gens. Leishmania major as an intracellular protozoan produces anti-inflammatory cytokines that lead to proliferation and survival of the parasite in the macrophages. miRNAs are small non-coding RNA molecules that regulate mRNAs expression. We aimed to investigate the relationship between the expression of TGF-beta and a bioinformatically candidate miRNA, in leishmaniasis as a model of TGF-beta overexpression.Methods: The miRNAs that target TGF-beta-3 ' UTR were predicted and scored by bioinformatic tools. After cloning of TGF-beta-3'UTR in psi-CHECK TM- 2 vector, targeting validation was confirmed using Luciferase assay. After miRNA mimic transfection, the expression of miR-27a, TGF-beta, as well as Nitric Oxide concentration was evaluated.Results: miR-27a received the highest score for targeting TGF-beta in bioinformatic predictions. Lucif-erase assay confirmed that miR-27a is targeting TGF-beta-3'UTR, since miR-27a transfection decreased the luciferase activity. After miRNA transfection, TGF-beta expression and Nitric Oxide concentration were declined in L. major infected macrophages.Conclusion: Bioinformatic prediction, luciferase assay, and miRNA transfection results showed that miR-27a targets TGF-beta. Since miRNA and cytokine-base therapies are developing in infectious dis-eases, finding and validating miRNAs targeting regulatory cytokines can be a novel strategy for con-trolling and treating leishmaniasis.