ABSTRACT
Objective:To investigate the infiltration and polarization of macrophages in mice during Chlamydia muridarum ( Cm) respiratory infection. Methods:C57BL/6 mice were intranasally infected with 1×10 3 inclusion-forming units (IFU) of Cm to establish the mouse model of Cm respiratory tract infection. The percentages of CD45 + F4/80 + cells and the macrophages expressing CD86, major histocompatibility complex Ⅱ (MHC), inducible nitric oxide synthase (iNOS) and CD206 were detected by flow cytometry. Expression of iNOS, CD206 and CCL2 at mRNA level was detected by real-time quantitative PCR. Results:Cm respiratory tract infection induced the increase of macrophages in mouse lung tissues. Compared with uninfected group, CD45 + F4/80 + macrophages were increased significantly from day 3 and reached the peak on day 7 after Cm infection. Moreover, the expression of CD86, MHCⅡ and CCL2 was increased, and the macrophages were polarized to M1 phenotype. However, the expression of M2 macrophage marker CD206 was decreased gradually. Further studies showed that iNOS expression, the indicator of M1 macrophage activation, was increased after Cm infection and reached to the top on day 7. Conclusions:Cm respiratory infection could induce the infiltration of macrophages in lung tissues and promote the polarization of macrophages to M1 phenotype.