Abstract:

Objective   To investigate the effects of cyclic mechanical stretch on the expression of Toll-like receptor 4(TLR4) in alveolar macrophages(AM) of rats. Methods   Rats’ AM were cyclicly stretched in vitro by using FX4000TTM Cell Stretching Unit produced in Flexercell company of the United States. The AM cells were divided into mechanical stretch of 6h and 8h groups(cyclic mechanical stretch at 30%, frequency of 0.3 Hz and square wave) and static control group. TLR4 mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR); the concentration of macrophage inflammatory protein 2(MIP-2) was detected by ELISA, while TLR4 protein was determined by immunohistochemistry. Results   Expressions of TLR4 mRNA, MIP-2 and TLR4 protein increased significantly in mechanical stretch of 6h and 8h groups compared with those in static control group(P<0.01). Conclusion   Cyclic mechanical stretch upregulates the expressions of TLR4 and MIP-2 in alveolar macrophages of rats.

Key words: Cyclic mechanical stretch; Lung injury; Alveolar macrophages; Toll-like receptor 4; Immunocytochemistry; RT-PCR