Exaggerated up-regulation of tumor necrosis factor α-dependent apoptosis in the older mouse liver following reperfusion injury: Targeting liver protective strategies to patient age

Abstract

Although it is becoming increasingly common to accept livers from older donors for transplantation, old livers are more damaged by hepatic ischemia and reperfusion injury (HIRI) than young livers. We hypothesized that this age-related susceptibility to HIRI is due to increased hepatocellular apoptosis driven by tumor necrosis factor ␣ (TNF␣). Young (6-weekold) and old (60-week-old) mice underwent 60 minutes of hepatic ischemia and increasing periods of reperfusion. TNF␣ was determined by enzyme-linked immunosorbent assay. Liver injury (enzyme release), apoptosis (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling staining, cytochrome C release, and caspase activation), and necrosis (hematoxylin and eosin staining) were assessed. We assessed the impact of apoptosis by blocking TNF␣ production or effect (pentoxifylline and TNF␣ receptor knockout), inhibiting apoptotic pathways (caspase inhibition), or imposing a hepatic protective strategy [glucose infusion with ischemic preconditioning (Glc/PC)]. In comparison with young livers, old livers subjected to HIRI had more pronounced liver aspartate aminotransferase release (6200 versus 3900 U/L, P ϭ 0.02), necrosis (45% versus 25%, P ϭ 0.03), and apoptosis with increased 30-minute TNF␣ release (19.02 versus 10.62 pg/mg, P ϭ 0.03). Eliminating TNF␣ production reversed the effect of age, as did inhibition of apoptotic pathways with caspase inhibition. Glc/PC of old mice attenuated TNF␣ release (9.56 versus 19.02 pg/mg, P ϭ 0.001) and age-related exaggerated HIRI and improved survival (60% versus 0%). In conclusion, the age-related susceptibility to HIRI is driven by an exaggerated induction of TNF␣-dependent hepatocellular apoptosis. Targeting the apoptotic cascade has implications for the older donor liver population. Liver Transpl 15:1594-1604, 2009. © 2009 AASLD. Received September 22, 2008 accepted May 25, 2009. Until recently, it was thought that the liver is relatively unaffected by aging, 1 but it is now clear that the older liver does not tolerate pathological insults as well as the younger liver.2-9 Clinical and animal studies provide strong evidence for an age-related susceptibility to hepatic ischemia and reperfusion injury (HIRI). 10 A prospective randomized study in humans investigated ischemic preconditioning as a strategy of protection Abbreviations: AST, aspartate aminotransferase; ATP, adenosine triphosphate; Casp Inh, pancapase inhibitor N-benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl ketone; D-Glc, D-glucose; Glc/PC, glucose infusion with ischemic preconditioning; Gluc-PC, glucose/preconditioning pretreatment; H 2 O 2 , hydrogen peroxide; HIRI, hepatic ischemia and reperfusion injury; I/Rp, ischemia and reperfusion; KO, knockout; PC/Gluc, preconditioning and glucose treatment; PTx, pentoxifylline; TNF, tumor necrosis factor; TNFR1, tumor necrosis factor receptor 1; TUNEL, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin

Lack of Grafted Liver Rejuvenation in Adult-to-Pediatric Liver Transplantation

“…However, it has been revealed that fibrosis, bile duct proliferation, and pigment deposition are more observed in aged grafts than in young rats, implying that the liver function of aged liver grafts could be bearable but that the aging process is indeed advancing. Recently, Selzner et al have reported that in the rat model with ischemia reperfusion injury, apoptosis induced by TNF-α is increased in aged rats compared with young rats 21) . This mechanism might be one of the causes of poor graft function in an aged liver graft.…”

Pentoxifylline in Liver Ischemia and Reperfusion

“…The activation of apoptosis is an important mechanism of damage after hepatic I/R [47]. Therefore, its inhibition exerts a strong protective effect against this injury.…”

“…The apoptotic pathway starts during the ischemic phase; other routes like anaerobic glycolisis and ATP hydrolysis are involved in the decrease of tissue pH and ATP reserves. Decreased ATP availability and the degree of acidosis are important factors for the activation of the apoptotic death cascade [47]. Apart from these pathways, TNF-α seems to be a key mediator in this route [47,48].…”

“…Decreased ATP availability and the degree of acidosis are important factors for the activation of the apoptotic death cascade [47]. Apart from these pathways, TNF-α seems to be a key mediator in this route [47,48]. TNF-Receptor 1 (TNF-R1), present in hepatocytes, is activated by TNF-α.…”

“…[58] 2009 Mouse L IR PTX PTX treatment resulted in strong protection against reperfusion injury in old mice, in contrast, no protective effect was observed in young mice with or without PTX treatment. [47] 2009 Pig L IR PTX + stobadine The study showed that intravenous administration of PTX and Stobadine protects the liver from warm ischemia injury. [64] 2010 Rat Intestine, lungs and L IR PTX + thalidomide Both drugs protected the intestine, lungs and liver against I/R injury, probably by inhibition of TNF-alpha and lipid peroxidation.…”