Role of Kupffer cells in cold/warm ischemia-reperfusion injury of rat liver

New therapeutic concepts against ischemia-reperfusion injury in organ transplantation

INTRODUCTION

Ischemia-reperfusion injury (IRI) involves a positive amplification feedback loop that stimulates innate immune-driven tissue damage associated with organ procurement from deceased donors and during transplantation surgery. As our appreciation of its basic immune mechanisms has improved in recent years, translating putative biomarkers into therapeutic interventions in clinical transplantation remains challenging.

AREAS COVERED

This review presents advances in translational/clinical studies targeting immune responses to reactive oxygen species in IRI-stressed solid organ transplants, especially livers. Here we focus on novel concepts to rejuvenate suboptimal donor organs and improve transplant function using pharmacologic and machine perfusion (MP) strategies. Cellular damage induced by cold ischemia/warm reperfusion and the latest mechanistic insights into the microenvironment's role that leads to reperfusion-induced sterile inflammation is critically discussed.

EXPERT OPINION

Efforts to improve clinical outcomes and increase the donor organ pool will depend on improving donor management and our better appreciation of the complex mechanisms encompassing organ IRI that govern the innate-adaptive immune interface triggered in the peritransplant period and subsequent allo-Ag challenge. Computational techniques and deep machine learning incorporating the vast cellular and molecular mechanisms will predict which peri-transplant signals and immune interactions are essential for improving access to the long-term function of life-saving transplants.

Extracellular vesicles from bone marrow-derived mesenchymal stem cells protect against murine hepatic ischemia/reperfusion injury

Hepatic ischemia/reperfusion injury (IRI) and associated inflammation contributes to liver dysfunction and complications after liver surgery and transplantation. Mesenchymal stem cells (MSCs) have been reported to reduce hepatic IRI because of their reparative immunomodulatory effects in injured tissues. Recent studies have highlighted beneficial effects of extracellular vesicles from mesenchymal stem cells (MSC-EV) on tissue injury. The effects of systemically administered mouse bone marrow-derived MSC-EV were evaluated in an experimental murine model of hepatic IRI induced by cross-clamping the hepatic artery and portal vein for 90 minutes followed by reperfusion for periods of up to 6 hours. Compared with controls, intravenous administration of MSC-EV 30 minutes prior to IRI dramatically reduced the extent of tissue necrosis, decreased caspase 3-positive and apoptotic cells, and reduced serum aminotransferase levels. MSC-EV increased hepatic messenger RNA (mRNA) expression of NACHT, LRR, and PYD domains-containing protein 12, and the chemokine (C-X-C motif) ligand 1, and reduced mRNA expression of several inflammatory cytokines such as interleukin 6 during IRI. MSC-EV increased cell viability and suppressed both oxidative injury and nuclear factor kappa B activity in murine hepatocytes in vitro. In conclusion, the administration of extracellular vesicles derived from bone marrow-derived MSCs may ameliorate hepatic IRI by reducing hepatic injury through modulation of the inflammatory response.Liver Transplantation 23 791-803 2017 AASLD.

Prevention of primary nonfunction after canine liver allotransplantation: the effect of gadolinium chloride

PURPOSE

Effective suppression of Kupffer cell function is believed to contribute to the prevention of preservation/reperfusion injury. In this study, effect of gadolinium, a synthetic Kupffer cell suppressant, on the reperfusion injury was examined using a canine partial liver transplantation model.

METHODS

About a 70% partial liver segment was harvested and reimplanted in a mongrel recipient dog weighing 20 to 25 kg. Gadolinium chloride (10 mg/kg) was infused via the cephalic vein 24 hours before harvest of the partial liver (gadolinium group, n = 5). Serum aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and morphologic grading of graft were compared with those of a control group (n = 5). Statistical analysis was done with an independent t-test.

RESULTS

Average total ischemic time was 4 hours and 27 minutes. At 1 hour after reperfusion, there were no significant differences in AST, ALP, or LDH levels, or pathologic scores. At 48 hours after reperfusion, AST (P = .03) and LDH (P = .05) levels were significantly lower in the gadolinium group.

CONCLUSION

Kupffer cell blockade using gadolinium chloride may be effective to reduce ischemia reperfusion injury, but the effect is not evident at an early stage of reperfusion.

Ischemic preconditioning protects from hepatic ischemia/reperfusion-injury by preservation of microcirculation and mitochondrial redox-state

BACKGROUND/AIMS

Ischemic preconditioning (IP) is known to protect hepatic tissue from ischemia-reperfusion injury. However, the mechanisms involved are not fully understood yet.

METHODS

Using intravital multifluorescence microscopy in the rat liver, we studied whether IP exerts its beneficial effect by modulating postischemic Kupffer cell activation, leukocyte-endothelial cell interaction, microvascular no-reflow, mitochondrial redox state, and, thus, tissue oxygenation.

RESULTS

Portal triad cross-clamping (45 min) followed by reperfusion induced Kupffer cell activation, microvascular leukocyte adherence, sinusoidal perfusion failure (no-reflow) and alteration of mitochondrial redox state (tissue hypoxia) (P<0.05). This resulted in liver dysfunction and parenchymal injury, as indicated by decreased bile flow and increased serum glutamate dehydrogenase (GLDH) levels (P<0.05). IP (5 min ischemia and 30 min intermittent reperfusion) was capable to significantly reduce Kupffer cell activation (P<0.05), which was associated with a slight attenuation of leukocyte adherence. Further, IP markedly ameliorated sinusoidal perfusion failure (P<0.05), and, thereby, preserved adequate mitochondrial redox state (P<0.05). As a consequence, IP prevented the decrease of bile flow (P<0.05) and the increase in serum GLDH levels (P<0.05).

CONCLUSIONS

IP may exert its beneficial effects on hepatic ischemia-reperfusion injury by preserving mitochondrial redox state, which is guaranteed by the prevention of reperfusion-associated Kupffer cell activation and sinusoidal perfusion failure.

Serum mannan binding protein inhibits mannosylated liposome-mediated transfection to macrophages

The effects of serum mannan binding proteins (MBP) in the transfection of plasmid DNA/Man-liposome complex via mannose receptor-mediated endocytosis was studied in vitro using cultured mouse peritoneal macrophages. Plasmid DNA encoding luciferase gene was complexed with cationic mannosylated liposomes (Man-liposomes), composed of cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and dioleoyl phosphatidylethanolamine (DOPE). The transfection efficiency, as well as the binding and uptake of the plasmid DNA/Man-liposome complex, was investigated with or without serum MBP. The in vitro transfection efficiency of the complex was significantly reduced on increasing the amount of serum MBP. In addition, the cellular association of the complex was also reduced. These results indicate that serum MBP specifically binds to the mannose moieties on the complex and suppresses its cellular uptake, resulting in inhibition of the gene transfection in macrophages. Such an interaction is an obstacle to mannose receptor-mediated in vivo gene transfer to mannose receptor-positive cells using mannosylated gene carriers.