miR-371, miR-138, miR-544, miR-145, and miR-214 could modulate Th1/Th2 balance in asthma through the combinatorial regulation of Runx3.

Asthma is tightly related to the imbalance of Th1/Th2 cells, and Runx3 plays a pivotal role in the differentiation of T helper cells. The present study aimed to investigate dysregulated microRNAs that may target Runx3 in CD4+ T cells from asthmatic patients and reveal Runx3 function in Th1/Th2 balance regulation. We detected the levels of Th1- and Th2-related cytokines by ELISA and analyzed the differentiation marker gene of T helper cells by qRT-PCR. Results indicated that an imbalance of Th1/Th2 cells was present in our asthmatic subject. Runx3 expression was reduced in the CD4+ T cells from asthmatic patients. Overexpression of Runx3 could restore the Th1/Th2 balance. After performing microRNA microarray assay, we found a series of microRNAs that were considerably altered in the CD4+ T cells from asthmatic patients. Among these upregulated microRNAs, eight microRNAs that may target Runx3 were selected by bioinformatics prediction. Five microRNAs, namely miR-371, miR-138, miR-544, miR-145, and miR-214, were confirmed by qRT-PCR and selected as candidate microRNAs. Luciferase reporter assay showed that these five microRNAs could directly target the 3'-UTR of Runx3. However, only simultaneous inhibition of these five microRNAs could alter the expression of Runx3. Most importantly, only simultaneous inhibition could improve the Th1/Th2 balance. Thus, we suggest that miR-371, miR-138, miR-544, miR-145, and miR-214 can modulate the Th1/Th2 balance in asthma by regulating Runx3 in a combinatorial manner.