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. Author manuscript; available in PMC: 2014 Jul 1.
Published in final edited form as: J Allergy Clin Immunol. 2013 Jun 2;132(1):3–13. doi: 10.1016/j.jaci.2013.04.039

Figure 3. Schematic showing the known roles of a commonly regulated set of miRNAs and their targets in allergic inflammation.

Figure 3

The Th1 and Th2 cells exist in a balanced state and inhibit each other’s differentiation. MiR-21 inhibits IL-12 and in turn inhibits Th1 differentiation. MiR-146 promotes Treg-mediated suppression of Th1 cells, likely by targeting STAT-1. The suppression of Th1 response promotes a Th2-dominant response with Th2 cytokine IL-13 production. Let-7 inhibits IL-13 production, and downregulation of let-7 likely further amplifies the Th2 response. In T cells, miR-155 promotes both the Th1 and Th2 response by inhibiting the inhibitor CTLA-4. In macrophages, miR-155 attenuates IL-1-mediated responses by downregulating IL-13 receptor alpha 1 (IL-13Rα1). IL-13 inhibits miR-375 expression in epithelial cells, and miR-375 may both potentiate and inhibit IL-13-mediated responses in epithelial cells. IL-13 inhibits miR-133a in smooth muscle cells, and this increases the expression of the small GTPase RhoA that mediates smooth muscle contraction. The miRNAs and their direct targets are shown in red. DC, dendritic cell.