Chlamydia pneumoniae infection promotes vascular smooth muscle

22 The migration of vascular smooth muscle cells (VSMCs) from the media to the intima is 23 proposed to be a key event in the development of atherosclerosis. Recently, we reported 24 that Chlamydia pneumoniae infection is involved in VSMC migration. However, the 25 exact mechanisms for C. pneumoniae infection-induced VSMC migration are not yet well 26 elucidated. In this study we examined the role of the Toll-like receptor 2 (TLR2) 27 activation-related signaling pathway in VSMC migration induced by C. pneumoniae 28 infection. An Affymetrix based gene expression array was conducted to identify the 29 changes of gene expression in rat primary VSMCs (rVSMCs) infected with C. 30 pneumoniae. Both the microarray analysis and quantitative real-time RT-PCR revealed 31 that TLR2 mRNA expression was strongly upregulated 12 h after C. pneumoniae 32 infection. RT-PCR and western blot analysis further showed that the expression levels of 33 TLR2 mRNA and protein significant increased at the different time points after infection. 34 Immunocytochemical analysis suggested a TLR2 recruitment to the vicinity of C. 35 pneumoniae inclusions. Cell migration assays showed that the TLR2 neutralizing 36 antibody could significantly inhibit C. pneumoniae infection-induced rVSMC migration. 37 In addition, C. pneumoniae infection stimulated Akt phosphorylation at Ser 473, which 38 was obviously suppressed by the PI3K inhibitor LY294002, thereby inhibiting rVSMC 39 migration caused by C. pneumoniae infection. Furthermore, both the infection-induced 40 Akt phosphorylation and rVSMC migration were suppressed by the TLR2 neutralizing 41 antibody. Taken together, these data suggest that C. pneumoniae infection can promote 42 on S etem er 3, 2017 by gest http/iai.asm .rg/ D ow nladed fom VSMC migration possibly through TLR2-related signaling pathway. 43