In contrast, an OVA-induced asthma model in miR-21 knockout (KO) mice showed that the lack of miR-21 led to a decrease in airway hyperresponsiveness and eosinophilic inflammation and a reduction in Th2 cell cytokines (IL-4, IL-5, and IL-13) in the bronchoalveolar lavage fluid (BALF), along with an increase in the levels of IL-12 and IFN-γ due to the suppression of the polarization of M2 macrophages (Figure 1c) [35]. This evidence concerns the gene IL13 and airway hyperresponsiveness.