Carbonic Anhydrase Protects Fatty Liver Grafts against Ischemic Reperfusion Damage

Abstract

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.

Acetazolamide Protects Steatotic Liver Grafts against Cold Ischemia Reperfusion Injury

“…This is in line with our previous observation showing that CA II addition to the IGL-1 solution prevented IRI in steatotic livers, which was associated with an enhanced CA II expression (Bejaoui et al, 2015). Thus, the AZ protective mechanism may be related to enhanced CA II protein expression rather than CA hydratase activity inhibition.…”

“…Our results confirm that AZ pretreatment at the dose of 30 mg/kg was efficient to inhibit CA hydratase activity (0.103 6 0.034 in the IGL-1 group versus 0.020 6 0.007 WAU/mg protein in the AZ group). Moreover, we examined the potential effect of AZ in the regulation of CA II expression, as we have previously shown that CA II addition to the IGL-1 solution protects steatotic livers against IRI (Bejaoui et al, 2015). Surprisingly, we observed that AZ induced a significant induction of CA II protein levels (Fig.…”

Liver Graft Hypothermic Static and Oxygenated Perfusion (HOPE) Strategies: A Mitochondrial Crossroads

“…Other natural AMPK activators, such as 3,5,4′-trihydroxy- trans -stilbene (resveratrol) [ 63 ], could be good candidates as additives for preservation solutions in future approaches. This principle also applies to PEG35 solutions, in which there has been an increase in activated AMPK under hypoxic conditions [ 64 , 65 , 66 ]. The mechanisms by which PEG35 activates AMPK in IGL-1 and rinse solutions remain to be investigated in depth.…”

Tip60 might be a candidate for the acetylation of hepatic carbonic anhydrase I and III in mice

“…It is also metabolizing many drugs, medications, chemicals, and natural substances. Although several CA isoforms, including CA I, CA II, CA III, CAVII and CA IX, have been described in liver, there is very limited information about regulation of CAs at the gene and protein levels, especially their transcriptional regulation [4,[42][43][44].…”