Toll-like receptor 4 signaling in dysfunction of cardiac microvascular endothelial cells under hypoxia/reoxygenation.
OBJECTIVE
This study was designed to detect the role of Toll-like receptor 4 (TLR4) signaling in the dysfunction of cardiac microvascular endothelial cells (CMECs) after hypoxia/reoxygenation (H/R).


METHODS
The cell viability of CMECs was measured by MTT assay. The migration of CMECs was detected by cell scratch wound assay. The expressions of TLR4, nuclear factor-kappa B (NF-κB) and eNOS were analyzed by Western blot. Secretions of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were determined by NO detection kit and ELISA.


RESULTS
Lipopolysaccharide (LPS) incubation increased the expressions of TLR4, NF-κB, IL-6 and TNF-α in CMECs (P < 0.05 vs. control). The CMECs after H/R injury had impaired cell viability (P < 0.01 vs. control) and migration ability (P < 0.05 vs. control). Moreover, the expressions of TLR4, NF-κB, IL-6 and TNF-α were elevated after H/R in CMECs (P < 0.01 vs. control), while NO and the eNOS expression were significantly decreased. In contrast, administration of the TLR4-neutralizing antibody MTS510 prior to H/R injury down-regulated the expressions of IL-6 and TNF-α and attenuated the dysfunction of CMECs.


CONCLUSIONS
TLR4 and its signaling components can be activated by LPS and H/R in CMECs. Blocking the TLR4 signal pathway before H/R injury attenuates CMEC dysfunction.
Zhang
Zheng
Z
Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032 Shaanxi, China.
Li
Weijie
W
Sun
Dongdong
D
Zhao
Li
L
Zhang
Rongqing
R
Wang
Yabin
Y
Zhou
Xuan
X
Wang
Haichang
H
Cao
Feng
F
D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000503:physiopathology*; D006321:Heart / Q000033:anatomy & histology*; D000860:Hypoxia / Q000503:physiopathology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008833:Microcirculation; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015424:Reperfusion; D015398:Signal Transduction / Q000502:physiology*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*
D008070:Lipopolysaccharides; D051197:Toll-Like Receptor 4; D052250:Nitric Oxide Synthase Type III