[Spleen-derived CD4+ T cells of asthmatic mice promote M2 polarization of macrophages in vitro].

: Objective To investigate the effect of asthmatic mouse spleen-derived CD4+ T cells on the polarization of bone marrow-derived macrophages (BMDMs) in vitro and its mechanism. Methods An animal model of allergic asthma induced by Dermatophagoides farinae allergen was established in mice. After the last challenge lasting 24 hours, the middle lobe of mouse lung was taken and HE staining was used to observe its inflammatory changes. The levels of miR-155-5p in the lung and spleen as well as spleen CD4+ T cells were detected by real-time quantitative PCR (qRT-PCR). The proportions of CD4+IFN-γ+ Th1 cells and CD4+IL-4+ Th2 cells in the spleen of asthmatic mice were detected by flow cytometry. The mRNA expression levels of M2 macrophage marker genes arginase 1 (Arg1), chitinase-like molecule 3 (YM1/Chi3l3) and resistance-like α (Retnlα/FIZZ1) in the lung were examined by qRT-PCR. Spleen-derived CD4+ T cells from the asthmatic mice were co-cultured in vitro with BMDMs for 48 hours, and then the mRNA expression levels of Arg1, YM1, and FIZZ1 in the BMDMs were detected by qRT-PCR. The spleen CD4+ T cells of the asthmatic mice were transfected with miR-155-5p inhibitor or the negative control, and then co-cultured with BMDM for 48 hours. The qRT-PCR was used to further determine the expression levels of Arg1, YM1, FIZZ1 in BMDMs. Results Compared with the control group, the levels of miR-155-5p in the lung, spleen and spleen CD4+ T cells of asthmatic mice increased, and the proportion of Th2 cells in asthmatic mouse spleen also increased. The expression levels of the M2 macrophage marker genes Arg1, YM1 and FIZZ1 were up-regulated in the lung of asthmatic mice compared to the control group. After co-culture of spleen CD4+ T cells from asthmatic mice with BMDMs in vitro, the mRNA expression levels of M2 marker genes Arg1, YM1 and FIZZ1 of BMDMs were up-regulated. While transfected with miR-155-5p-inhibitor, the spleen CD4+ T cells of asthmatic mice did not significantly affect the M2 marker gene expression of the BMDMs. Conclusion The spleen-derived CD4+ T cells of asthmatic mice can promote the polarization of co-cultured macrophages towards M2 phenotype in vitro.