Acetazolamide protects steatotic liver grafts against cold ischemia reperfusion injury.

Ischemia reperfusion injury (IRI) is a primary concern in liver transplantation, especially when steatosis is present. Acetazolamide (AZ), a specific carbonic anhydrase (CA) inhibitor, has been suggested to protect against hypoxia. Here, we hypothesized that AZ administration could be efficient to protect fatty livers against cold IRI. Obese Zucker rat livers were preserved in Institut Georges Lopez-1 storage solution for 24 hours at 4°C and ex vivo perfused for 2 hours at 37°C. Alternatively, rats were also treated with intravenous injection of AZ (30 mg/kg) before liver recovery. Liver injury, hepatic function, and vascular resistance were determined. CA II protein levels and CA hydratase activity were assessed as well as other parameters involved in IRI (endothelial nitric oxide synthase, mitogen activated protein kinase family, hypoxic inducible factor 1 alpha, and erythropoietin). We demonstrated that AZ administration efficiently protects the steatotic liver against cold IRI. AZ protection was associated with better function, decreased vascular resistance, and activation of endothelial nitric oxide synthase. This was consistent with an effective mitogen activated protein kinase inactivation. Finally, no effect on the hypoxic inductible factor 1 alpha/erythropoietin pathway was observed. The present study demonstrated that AZ administration is a suitable pharmacological strategy for preserving fatty liver grafts against cold IRI.

Carbonic Anhydrase Protects Fatty Liver Grafts against Ischemic Reperfusion Damage.

Carbonic anhydrases (CAs) are ubiquitous metalloenzymes that catalyze the reversible hydration of carbon dioxide to bicarbonate and a proton. CAs are involved in numerous physiological and pathological processes, including acid-base homeostasis, electrolyte balance, oxygen delivery to tissues and nitric oxide generation. Given that these processes are found to be dysregulated during ischemia reperfusion injury (IRI), and taking into account the high vulnerability of steatotic livers to preservation injury, we hypothesized a new role for CA as a pharmacological agent able to protect against ischemic damage. Two different aspects of the role of CA II in fatty liver grafts preservation were evaluated: 1) the effect of its addition to Institut Georges Lopez (IGL-1) storage solution after cold ischemia; 2) and after 24h of cold storage followed by two hours of normothermic ex-vivo perfusion. In all cases, liver injury, CA II protein concentration, CA II mRNA levels and CA II activity were determined. In case of the ex-vivo perfusion, we further assessed liver function (bile production, bromosulfophthalein clearance) and Western blot analysis of phosphorylated adenosine monophosphate activated protein kinase (AMPK), mitogen activated protein kinases family (MAPKs) and endoplasmic reticulum stress (ERS) parameters (GRP78, PERK, IRE, eIF2α and ATF6). We found that CA II was downregulated after cold ischemia. The addition of bovine CA II to IGL-1 preservation solution efficiently protected steatotic liver against cold IRI. In the case of reperfusion, CA II protection was associated with better function, AMPK activation and the prevention of ERS and MAPKs activation. Interestingly, CA II supplementation was not associated with enhanced CO2 hydration. The results suggest that CA II modulation may be a promising target for fatty liver graft preservation.