ARG1 and asthma: Arg1 downregulated by MSC in M2 macrophages is known to contribute to the pathogenesis of asthma by inducing cytokine secretion in asthmatic conditions45 Furthermore, the effect of MSCs might be related to the reduction of Chil3 on macrophages contributing to the development of eosinophilic lung inflammation and expression of Th2 cytokines46,47.