- 作者: Kou-Gi Shyu; Bao-Wei Wang; Chiu-Mei Lin; Hang Chang
- 作者服務機構: Division of Cardiology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan, R.O.C.
- 中文摘要: --
- 英文摘要:
Background: Toll-like receptor 4 (TLR4) plays an important role in innate immunity.
The role of TLR4 in stretched cardiomyocytes is not known. We sought to investigate
whether mechanical stretch could regulate TLR4 expression, as well as the possible
molecular mechanisms and signal pathways mediating the expression of TLR4 by
cyclic mechanical stretch in cardiomyocytes.
Methods: Neonatal Wistar rat cardiomyocytes grown on a flexible membrane base
were stretched by vacuum to 20% of maximum elongation at 60 cycles/min. Western
blot, real-time polymerase chain reaction, and promoter activity assay were performed.
In vitro monocyte adhesion to stretched myocyte was detected.
Results: Cyclic stretch significantly increased TLR4 protein and mRNA expression
after 2 h to 24 h of stretch. Addition of SB203580, TNF-α antibody, and p38α MAP
kinase siRNA 30 min before stretch inhibited the induction of TLR4 protein. Cyclic
stretch increased, while SB203580 abolished the phosphorylated p38 protein. Gel
shifting assay showed significant increase of DNA-protein binding activity of NF-κB
after stretch and SB203580 abolished the DNA-protein binding activity induced by
cyclic stretch. DNA-binding complexes induced by cyclic stretch could be
supershifted by p65 monoclonal antibody. Cyclic stretch increased TLR4 promoter
activity while SB203580 and NF-κB siRNA decreased TLR4 promoter activity. Cyclic stretch increased adhesion of monocyte to cardiomyocytes while SB203580,
TNF-α antibody, and TLR4 siRNA attenuated the adherence of monocyte. TNF-α and
Ang II significantly increased TLR4 protein expression. Addition of losartan, TNF-α
antibody, or p38αsiRNA 30 min before Ang II and TNF-α stimulation significantly
blocked the increase of TLR4 protein by AngII and TNF-α.
Conclusions: Cyclic mechanical stretch enhances TLR4 expression in cultured rat
neonatal cardiomyocytes. The stretch-induced TLR4 is mediated through activation of
p38 MAP kinase and NF-κB pathways. TLR4 up-regulation by cyclic stretch
increases monocyte adherence. - 中文關鍵字: --
- 英文關鍵字: --