Aim TLR-4 has been proved to take part in MIRI of heart. But the researches mostly focused on the relationship between TLR-4 and global heart dysfunction or cadiocyte apoptosis. The effect of TLR-4 on CMECs which are the most important component in MIRI is not clear. To explore the change of TLR-4 signal pathoway during hypoxia–reoxygenation (H-R) of cardiac microvascular endothelial cells (CMECs) injury.
Methods The CMECs were isolated from the hearts of adult rats. The obtained CMECs were exposed to hypoxia (940 ml/l N2, 50 ml/l CO2 and 10 ml/l O2) for 6 h, following by reoxygenation (950 ml/l air, 50 ml/l CO2) for 2 h, 12 h or 24 h. The proliferation of CMECs was assessed by MTT colourimetry. TLR-4 and NF-κB expressions were analysed by Western blot. The levels of IL-6 and TNF-α were detected by ELISA.
Results The proliferation ability of CMECs was significantly inhibited by H-R injury (p<0.01). H-R injury increased TLR-4 expression after 2 h or 12 h reoxygenation (p<0.05). The level of NF-κB increased after 2 h and 24 h reoxygenation (p<0.05). H-R injury enhanced IL-6 and TNF-α secretion as compared with the control group (p<0.05).
Conclusion H-R injury increases TLR-4 and NF-κB expressions in CMECs and enhances the secretions of IL-6 and TNF-α. The activation of TLR-4 signal pathway on CMECs may participate in the H-R induced of CMECs injury.