Cross-Talk Between Sirtuin 1 and High-Mobility Box 1 in Steatotic Liver Graft Preservation.

BACKGROUND: Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide +-dependent histone deacetylase that regulates various pathways involved in ischemia-reperfusion injury (IRI). Moreover, high-mobility group box 1 protein (HMGB1) has also been involved in inflammatory processes during IRI. However, the roles of both SIRT1 and HMGB1 in liver preservation is poorly understood. In this communication, we evaluated the potential relationship between SIRT1 and HMGB1 in steatotic and non-steatotic liver grafts preserved in Institute Georges Lopez solution (IGL-1) preservation solution enriched or not enriched with trimetazidine (TMZ). METHODS: Steatotic and non-steatotic livers were preserved in IGL-1 preservation solution (24 hours, 4°C), enriched or not enriched with TMZ (10 µmol/L), and then submitted to ex vivo reperfusion (2 hours; 37°C). Liver injury (AST/ALT) and function (bile output, vascular resistance) were evaluated. SIRT1, HMGB1, autophagy parameters (beclin-1, LC3B), PPAR-γ, and heat-shock protein (HO-1, HSP70) expression were determined by means of Western blot. Also, we assessed oxidative stress, mitochondrial damage (glutamate dehydrogenase), and TNF-α levels. RESULTS: Elevated SIRT1 and enhanced autophagy were found after reperfusion in steatotic livers preserved in IGL-1+TMZ when compared with IGL-1. However, these changes were not seen in the case of non-steatotic livers. Also, HO-1 increases in the IGL-1 + TMZ group were evident only in the case of steatotic livers, whereas HSP70 and PPAR-γ protein expression were enhanced only in non-steatotic livers. All reported changes were consistent with decreased liver injury diminution, ameliorated hepatic function, and decreased TNF-α and HMGB levels. In addition, the oxidative stress and mitochondrial damage were efficiently prevented by the IGL-1 + TMZ use. CONCLUSIONS: SIRT1 is associated with HMGB1 decreases and increased autophagy in steatotic livers, contributing to increased tolerance to cold IRI.

IGL-1 solution reduces endoplasmic reticulum stress and apoptosis in rat liver transplantation.

Injury due to cold ischemia reperfusion (I/R) is a major cause of primary graft non-function following liver transplantation. We postulated that I/R-induced cellular damage during liver transplantation might affect the secretory pathway, particularly at the endoplasmic reticulum (ER). We examined the involvement of ER stress in organ preservation, and compared cold storage in University of Wisconsin (UW) solution and in Institute Georges Lopez-1 (IGL-1) solution. In one group of rats, livers were preserved in UW solution for 8 h at 4 °C, and then orthotopic liver transplantation was performed according to Kamada's cuff technique. In another group, livers were preserved in IGL-1 solution. The effect of each preservation solution on the induction of ER stress, hepatic injury, mitochondrial damage and cell death was evaluated. As expected, we found increased ER stress after liver transplantation. IGL-1 solution significantly attenuated ER damage by reducing the activation of three pathways of unfolded protein response and their effector molecules caspase-12, C/EBP homologous protein-10, X-box-binding protein 1, tumor necrosis factor-associated factor 2 and eukaryotic translation initiation factor 2. This attenuation of ER stress was associated with a reduction in hepatic injury and cell death. Our results show that IGL-1 solution may be a useful means to circumvent excessive ER stress reactions associated with liver transplantation, and may optimize graft quality.

How Institut Georges Lopez preservation solution protects nonsteatotic and steatotic livers against ischemia-reperfusion injury.

The Institut Georges Lopez preservation solution (IGL-1) is a serum-free organ preservative that has been shown to protect steatotic livers against hepatic ischemia-reperfusion injury. Although several hypotheses have been proposed to explain the graft protection mechanisms induced by IGL-1 solution, they have not been fully investigated. This review assessed possible IGL-1 mechanisms responsible for the increased liver tolerance of ischemia-reperfusion injury with special emphasis on vasodilatator mediators such as nitric oxide, on oxidative stress prevention, on protection against mitochondrial damage, and finally on induction of cytoprotective factors.

Relevance of epidermal growth factor to improve steatotic liver preservation in IGL-1 solution.

AIM: Static preservation solution is critical for liver graft outcomes, especially when steatosis is present. Institut Georges Lopez (IGL)-1 solution protects fatty livers effectively against cold ischemia reperfusion injury. Its benefits are mediated by nitric oxide and prevention of oxidative stress. The supplementation of IGL-1 with epidermal growth factor (EGF) enhances steatotic graft preservation by increasing adenosine triphosphate content, thereby mitigating oxidative stress and mitochondrial damage. METHODS: After steatotic livers were preserved for 24 hours in IGL-1 solution with or without EGF supplements, they were perfused ex vivo for 2 hours at 37°C. The benefits of EGF were assessed by evidences of hepatic damage and function--transaminases, bile production, and flow rate--as well as by other factors presumably associated with the poor tolerance of fatty livers toward cold ischemia-reperfusion injury (IRI)--energy metabolism, mitochondrial damage, oxidative stress, eNOS activity and proinflammatory interleukin (IL) beta content. RESULTS: Steatotic livers preserved in IGL-1 solutions supplemented with EGF (10 µg/L) showed lower transaminase levels, greater bile production, and ameliorated flow rates when compared to IGL-1 alone. In addition, energy metabolism deterioration, mitochondrial damage, oxidative stress, and cytokine IL-1 beta release were prevented. CONCLUSION: EGF addition to IGL-1 increased fatty liver graft preservation, thereby reducing steatotic liver damage against cold IRI.

Matrix metalloproteinase 2 in reduced-size liver transplantation: beyond the matrix.

We studied the contribution of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9) to the beneficial effects of preconditioning (PC) in reduced-size orthotopic liver transplantation (ROLT). We also examined the role of c-Jun N-terminal kinase (JNK) and whether it regulates MMP2 in these conditions. Animals were subjected to ROLT with or without PC and pharmacological modulation, and liver tissue samples were then analyzed. We found that MMP2, but notMMP9, is involved in the beneficial effects of PC in ROLT. MMP2 reduced hepatic injury and enhanced liver regeneration. Moreover, inhibition of MMP2 in PC reduced animal survival after transplantation. JNK inhibition in the PC group decreased hepatic injury and enhanced liver regeneration. Furthermore, JNK upregulated MMP2 in PC. In addition, we showed that Tissue inhibitors of matrix metalloproteinases 2 (TIMP2) was also upregulated in PC and that JNK modulation also altered its levels in ROLT and PC. Our results open up new possibilities for therapeutic treatments to reduce I/R injury and increase liver regeneration after ROLT, which are the main limitations in living-donor transplantation.

New insights into fatty liver preservation using Institute Georges Lopez preservation solution.

Institute Georges Lopez preservation solution (IGL-1) has been demonstrated to be useful for fatty liver preservation. The mechanisms responsible for this effective graft protection against ischemia-reperfusion injury are pivotal actions on generation of nitric oxide a diffusible molecule with vasodilator properties, that facilitates the up-regulation of other well-known cytoprotective genes, such as hypoxia-inducible factor-1 alpha (HIF-1alpha) and heme-oxygenase 1 (HO-1). During normoxic reperfusion, the presence of nitric oxide permits HIF-1alpha accumulation to inhibit prolyl-hydoxylases, thus promoting an additional overexpression of the HO-1 in steatotic and nonsteatotic graft livers preserved in IGL-1.

Endoplasmic reticulum stress inhibition protects steatotic and non-steatotic livers in partial hepatectomy under ischemia-reperfusion.

During partial hepatectomy, ischemia-reperfusion (I/R) is commonly applied in clinical practice to reduce blood flow. Steatotic livers show impaired regenerative response and reduced tolerance to hepatic injury. We examined the effects of tauroursodeoxycholic acid (TUDCA) and 4-phenyl butyric acid (PBA) in steatotic and non-steatotic livers during partial hepatectomy under I/R (PH+I/R). Their effects on the induction of unfolded protein response (UPR) and endoplasmic reticulum (ER) stress were also evaluated. We report that PBA, and especially TUDCA, reduced inflammation, apoptosis and necrosis, and improved liver regeneration in both liver types. Both compounds, especially TUDCA, protected both liver types against ER damage, as they reduced the activation of two of the three pathways of UPR (namely inositol-requiring enzyme and PKR-like ER kinase) and their target molecules caspase 12, c-Jun N-terminal kinase and C/EBP homologous protein-10. Only TUDCA, possibly mediated by extracellular signal-regulated kinase upregulation, inactivated glycogen synthase kinase-3ß. This is turn, inactivated mitochondrial voltage-dependent anion channel, reduced cytochrome c release from the mitochondria and caspase 9 activation and protected both liver types against mitochondrial damage. These findings indicate that chemical chaperones, especially TUDCA, could protect steatotic and non-steatotic livers against injury and regeneration failure after PH+I/R.