Moderate hypothermia during cardiac surgery provides hepatic protection by modifying the balance between gene expression of TNFα and IL10

Aims

To investigate the effect of moderate hypothermia during CPB on intrahepatic gene expression of TNFα, IL10, apoptosis regulatory proteins (Fas, Bak and Bcl-xL) and hepatic cell death during and after cardiac surgery.

Methods

Pigs were assigned to a temperature (T°) group during standardized cardiopulmonary bypass (CPB): normothermia (T°, 37°C; n = 8) and moderate hypothermia (T°, 28°C; n = 8). Liver probes were taken before and 6 hours after CPB for standard-and immunohistological examinations. Apoptotic cells were detected by TUNEL-staining. Intrahepatic gene expression of TNFα, IL10 and of apoptosis regulating proteins were examined by competitive RT-PCR.

Results

Gene expression of cytokine and apoptosis regulating proteins was not detected before but 6 hours after CPB. Pigs operated on under 28°C showed lower TNFα-mRNA and higher IL10-mRNA than those operated on under 37°C (P < 0.05). While expression of apoptosis regulatory proteins and percentage of apoptotic hepatocytes were similar in both groups, percentage of necrotic hepatocytes was lower in 28°C than in 37°C group (P < 0.05). TNFα-mRNA after CPB was correlated with the percentage of necrotic hepatocytes (P < 0.05).

Conclusions

Moderate hypothermia during CPB provides hepatic protection by increasing IL10- and decreasing intrahepatic TNFα-gene expression without affecting gene expression of apptosis regulatory proteins.