Abstract
Cardiovascular collapse is the major factor contributing to the mortality of trauma-hemorrhage (T-H) patients. Toll-like receptors (TLRs) play a critical role in T-H-induced cardiac dysfunction. This study evaluated the role of TLR9 agonist, CpG-oligodeoxynucleotide (ODN) 1826, in cardiac functional recovery after T-H. Trauma-hemorrhage was induced in a murine model by soft tissue injury and blood withdrawals from the jugular vein to a mean arterial pressure of 35 ± 5 mmHg. Mice were treated with CpG-ODN 1826 (10 μg/30 g body weight) by intraperitoneal injection 1 h before T-H (n = 5-8/group). Hemodynamic parameters were measured before, during hemorrhage, and at 60 min after T-H. Trauma-hemorrhage significantly decreased the mean arterial pressure and left ventricular pressure compared with sham controls. In contrast, CpG-ODN administration significantly attenuated the decrease in arterial pressure and left ventricular pressure due to T-H. Trauma-hemorrhage markedly decreased myocardial levels of phosphorylated Akt by 57.9%. However, CpG-ODN treatment significantly blunted the decrement in phospho-Akt by activating the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. The PI3K inhibitor LY294002 partially abolished CpG-induced cardioprotection, indicating that additional signaling pathways are involved in the protective effect of CpG-ODN after T-H. We observed that CpG-ODN treatment also significantly attenuated the decrease in myocardial phospho-ERK levels after T-H. Inhibition of ERK by U0126 also partially abolished the cardioprotective effect of CpG-ODN after T-H. Our data suggest that CpG-ODN significantly attenuates T-H-induced cardiac dysfunction. The mechanisms involve activation of both PI3K/Akt and ERK signaling pathways. The TLR9 agonist, CpG-ODN 1826, may provide a novel treatment strategy for preventing or managing cardiac dysfunction and enhancing recovery in T-H patients.