The roles of Kupffer cells in hepatocellular dysfunction after femur fracture trauma in rats

Differential regulation of cytochrome P450 isozyme mRNAs and proteins by femur fracture trauma

The aim of this study was to investigate the effect of trauma on cytochrome P450 (CYP) gene expression and to determine the role of Kupffer cells in trauma-induced alteration of CYP isozymes. Rats underwent closed femur fracture (FFx) with associated soft-tissue injury under anesthesia. To deplete Kupffer cells in vivo, gadolinium chloride (GdCl3) was intravenously injected at 7.5 mg/kg body wt., 1 and 2 days prior to FFx surgery. At 72 h of FFx, liver tissues were isolated to determine the mRNA and protein expression of CYP isozymes and NADPH-P450 reductase by reverse transcription-polymerase chain reaction and Western immunoblotting, respectively. In addition, the mRNA levels of tumor necrosis factor-alpha (TNF-alpha), inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) were evaluated. FFx increased the mRNA level of CYP1A1; an increase that was not prevented by GdCl3. There were no significant differences in the mRNA expression of CYP1A2, 2B1 and 2E1 among any of the experimental groups. The protein levels of CYP2B1 and 2E1 were significantly decreased by FFx; a decrease that was not prevented by GdCl3 treatment. The gene expression of NADPH-P450 reductase was unchanged by FFx. FFx significantly increased the expression of TNF-alpha mRNA; an increase that was attenuated by GdCl3. The mRNA expression of HO-1 was increased by FFx, but not by GdCl3. Our findings suggest that FFx differentially regulates the expression of CYP isozyme through Kupffer cell-independent mechanisms.