Downregulation of hepatic cytochrome P-450 isoforms and PPAR-gamma: their role in hepatic injury and proinflammatory responses in a double-hit model of hemorrhage and sepsis.
BACKGROUND
The "double-hit" model of hemorrhage and sepsis mimics the critically ill patient admitted to the surgical intensive care unit. Although the protein expression of a cytochrome (CYP) P-450 isoform CYP1A2 is reduced in the late stage of sepsis, the effect of hemorrhage on CYP isoforms and the anti-inflammatory nuclear receptor peroxisome proliferator-activated receptor-gamma (PPAR-gamma) has not been investigated. We hypothesized that hemorrhage down-regulates CYP isoforms and PPAR-gamma in the liver, which plays an important role in producing tissue injury and proinflammatory responses after the subsequent sepsis (i.e., double-hit).


METHODS
Male Sprague Dawley rats were divided into four groups. Animals in the double-hit group underwent hemorrhage (40 +/- 2 mmHg for 90 min) followed by fluid resuscitation. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) 20 h after hemorrhage, and the animals were sacrificed 4 h after CLP. Rats in the hemorrhage-alone group were sacrificed 20 h after the insult. Rats in the CLP-alone group were sacrificed 4 h after the onset of sepsis. Animals in the sham-operated group underwent neither hemorrhage nor CLP. The gene expression of P-450 isoforms (i.e., CYP1A2 and 2C11) and PPAR-gamma in the liver was determined using RT-PCR. Serum concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate, and proinflammatory cytokines (i.e., IL-6, TNF-alpha) were also assessed.


RESULTS
In the hemorrhage-alone group, hepatic mRNA expression of CYP1A2, CYP2C11, and PPAR-gamma was significantly down-regulated 20 h after the initial stress compared with sham-operated rats. Double-hit did not appear to further decrease CYP and PPAR-gamma gene expression. In contrast, serum levels of AST, ALT, lactate, IL-6, and TNF-alpha did not change significantly in either hemorrhaged or septic animals. Those organ injury indicators and cytokines, however, were significantly elevated after the double-hit of hemorrhage and sepsis.


CONCLUSIONS
Hepatic CYP1A2, CYP2C11, and PPAR-gamma were down-regulated after the initial stress (hemorrhage). These down-regulated CYPs and PPAR-gamma seem to work as important factors contributing to the progression of organ injury and proinflammatory responses after the second stress (CLP).
Higuchi
Shinya
S
Department of Surgery, North Shore University Hospital and Long Island Jewish Medical Center, Manhasset, New York 11030, USA.
Wu
Rongqian
R
Zhou
Mian
M
Ravikumar
Thanjavur S
TS
Wang
Ping
P
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D001219:Aspartate Aminotransferases / Q000097:blood; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics*; D000072467:Cytochrome P450 Family 2; D003580:Cytochromes; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000276:immunology; D015971:Gene Expression Regulation, Enzymologic / Q000276:immunology; D015850:Interleukin-6 / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008099:Liver / Q000201:enzymology / Q000276:immunology; D008107:Liver Diseases / Q000276:immunology* / Q000503:physiopathology; D008297:Male; D047495:PPAR gamma / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000276:immunology* / Q000503:physiopathology; D012771:Shock, Hemorrhagic / Q000276:immunology* / Q000503:physiopathology; D039181:Steroid 16-alpha-Hydroxylase / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D003580:Cytochromes; D015850:Interleukin-6; D047495:PPAR gamma; D014409:Tumor Necrosis Factor-alpha; D019344:Lactic Acid; D001189:Aryl Hydrocarbon Hydroxylases; C450279:CYP2C11 protein, rat; C017170:Cyp1a2 protein, rat; D019388:Cytochrome P-450 CYP1A2; D000072467:Cytochrome P450 Family 2; D039181:Steroid 16-alpha-Hydroxylase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase