Clinical Trial of the Pan-Caspase Inhibitor, IDN-6556, in Human Liver Preservation Injury

Graft repair during machine perfusion: a current overview of strategies

PURPOSE OF REVIEW

With changing donor characteristics (advanced age, obesity), an increase in the use of extended criteria donor (ECD) livers in liver transplantation is seen. Machine perfusion allows graft viability assessment, but still many donor livers are considered nontransplantable. Besides being used as graft viability assessment tool, ex situ machine perfusion offers a platform for therapeutic strategies to ameliorate grafts prior to transplantation. This review describes the current landscape of graft repair during machine perfusion.

RECENT FINDINGS

Explored anti-inflammatory therapies, including inflammasome inhibitors, hemoabsorption, and cellular therapies mitigate the inflammatory response and improve hepatic function. Cholangiocyte organoids show promise in repairing the damaged biliary tree. Defatting during normothermic machine perfusion shows a reduction of steatosis and improved hepatobiliary function compared to nontreated livers. Uptake of RNA interference therapies during machine perfusion paves the way for an additional treatment modality.

SUMMARY

The possibility to repair injured donor livers during ex situ machine perfusion might increase the utilization of ECD-livers. Application of defatting agents is currently explored in clinical trials, whereas other therapeutics require further research or optimization before entering clinical research.

Revitalizing oral cancer research: Crispr-Cas9 technology the promise of genetic editing

This review presents an in-depth analysis of the immense potential of CRISPR-Cas9 technology in revolutionizing oral cancer research. It underscores the inherent limitations of conventional treatments while emphasizing the pressing need for groundbreaking approaches. The unparalleled capability of CRISPR-Cas9 to precisely target and modify specific genes involved in cancer progression heralds a new era in therapeutic intervention. Employing genome-wide CRISPR screens, vulnerabilities in oral cancer cells can be identified, thereby unravelling promising targets for therapeutic interventions. In the realm of oral cancer, the disruptive power of CRISPR-Cas9 manifests through its capacity to perturb genes that are intricately associated with drug resistance, consequently augmenting the efficacy of chemotherapy. To address the challenges that arise, this review diligently examines pertinent issues such as off-target effects, efficient delivery mechanisms, and the ethical considerations surrounding germline editing. Through precise gene editing, facilitated by CRISPR/Cas9, it becomes possible to overcome drug resistance by rectifying mutations, thereby enhancing the efficacy of personalized treatment strategies. This review delves into the prospects of CRISPR-Cas9, illuminating its potential applications in the domains of medicine, agriculture, and biotechnology. It is paramount to emphasize the necessity of ongoing research endeavors and the imperative to develop targeted therapies tailored specifically for oral cancer. By embracing this comprehensive overview, we can pave the way for ground-breaking treatments that instill renewed hope for enhanced outcomes in individuals afflicted by oral cancer.

Intraoperative Anesthetic Strategies to Mitigate Early Allograft Dysfunction After Orthotopic Liver Transplantation: A Narrative Review

Orthotopic liver transplantation (OLT) is the most effective treatment for patients with end-stage liver disease (ESLD). Hepatic insufficiency within a week of OLT, termed early allograft dysfunction (EAD), occurs in 20% to 25% of deceased donor OLT recipients and is associated with morbidity and mortality. Primary nonfunction (PNF), the most severe form of EAD, leads to death or retransplantation within 7 days. The etiology of EAD is multifactorial, including donor, recipient, and surgery-related factors, and largely driven by ischemia-reperfusion injury (IRI). IRI is an immunologic phenomenon characterized by dysregulation of cellular oxygen homeostasis and innate immune defenses in the allograft after temporary cessation (ischemia) and later restoration (reperfusion) of oxygen-rich blood flow. The rising global demand for OLT may lead to the use of marginal allografts, which are more susceptible to IRI, and thus lead to an increased incidence of EAD. It is thus imperative the anesthesiologist is knowledgeable about EAD, namely its pathophysiology and intraoperative strategies to mitigate its impact. Intraoperative strategies can be classified by 3 phases, specifically donor allograft procurement, storage, and recipient reperfusion. During procurement, the anesthesiologist can use pharmacologic preconditioning with volatile anesthetics, consider preharvest hyperoxemia, and attenuate the use of norepinephrine as able. The anesthesiologist can advocate for normothermic regional perfusion (NRP) and machine perfusion during allograft storage at their institution. During recipient reperfusion, the anesthesiologist can optimize oxygen exposure, consider adjunct anesthetics with antioxidant-like properties, and administer supplemental magnesium. Unfortunately, there is either mixed, little, or no data to support the routine use of many free radical scavengers. Given the sparse, limited, or at times conflicting evidence supporting some of these strategies, there are ample opportunities for more research to find intraoperative anesthetic strategies to mitigate the impact of EAD and improve postoperative outcomes in OLT recipients.

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.

The Protective Effect of Nutraceuticals on Hepatic Ischemia-Reperfusion Injury in Wistar Rats

Nutraceuticals are bioactive compounds present in foods, utilized to ameliorate health, prevent diseases, and support the proper functioning of the human body. They have gained attention due to their ability to hit multiple targets and act as antioxidants, anti-inflammatory agents, and modulators of immune response and cell death. Therefore, nutraceuticals are being studied to prevent and treat liver ischemia-reperfusion injury (IRI). This study evaluated the effect of a nutraceutical solution formed by resveratrol, quercetin, omega-3 fatty acid, selenium, ginger, avocado, leucine, and niacin on liver IRI. IRI was performed with 60 min of ischemia and 4 h of reperfusion in male Wistar rats. Afterward, the animals were euthanized to study hepatocellular injury, cytokines, oxidative stress, gene expression of apoptosis-related genes, TNF-α and caspase-3 proteins, and histology. Our results show that the nutraceutical solution was able to decrease apoptosis and histologic injury. The suggested mechanisms of action are a reduction in gene expression and the caspase-3 protein and a reduction in the TNF-α protein in liver tissue. The nutraceutical solution was unable to decrease transaminases and cytokines. These findings suggest that the nutraceuticals used favored the protection of hepatocytes, and their combination represents a promising therapeutic proposal against liver IRI.

Mitochondria and cell death-associated inflammation

Mitochondria have recently emerged as key drivers of inflammation associated with cell death. Many of the pro-inflammatory pathways activated during cell death occur upon mitochondrial outer membrane permeabilization (MOMP), the pivotal commitment point to cell death during mitochondrial apoptosis. Permeabilised mitochondria trigger inflammation, in part, through the release of mitochondrial-derived damage-associated molecular patterns (DAMPs). Caspases, while dispensable for cell death during mitochondrial apoptosis, inhibit activation of pro-inflammatory pathways after MOMP. Some of these mitochondrial-activated inflammatory pathways can be traced back to the bacterial ancestry of mitochondria. For instance, mtDNA and bacterial DNA are highly similar thereby activating similar cell autonomous immune signalling pathways. The bacterial origin of mitochondria suggests that inflammatory pathways found in cytosol-invading bacteria may be relevant to mitochondrial-driven inflammation after MOMP. In this review, we discuss how mitochondria can initiate inflammation during cell death highlighting parallels with bacterial activation of inflammation. Moreover, we discuss the roles of mitochondrial inflammation during cell death and how these processes may potentially be harnessed therapeutically, for instance to improve cancer treatment.

Pan-caspase inhibition during normothermic machine perfusion of discarded livers mitigates ex situ innate immune responses

Access to liver transplantation is limited by a significant organ shortage. The recent introduction of machine perfusion technology allows surgeons to monitor and assess ex situ liver function prior to transplantation. However, many donated organs are of inadequate quality for transplant, though opportunities exist to rehabilitate organ function with adjunct therapeutics during normothermic machine perfusion. In this preclinical study, we targeted the apoptosis pathway as a potential method of improving hepatocellular function. Treatment of discarded human livers during normothermic perfusion with an irreversible pan-caspase inhibitor, emricasan, resulted in significant mitigation of innate immune and pro-inflammatory responses at both the transcriptional and protein level. This was evidenced by significantly decreased circulating levels of the pro-inflammatory cytokines, interleukin-6, interleukin-8, and interferon-gamma, compared to control livers. Compared to emricasan-treated livers, untreated livers demonstrated transcriptional changes notable for enrichment in pathways involved in innate immunity, leukocyte migration, and cytokine-mediated signaling. Targeting of unregulated apoptosis may represent a viable therapeutic intervention for immunomodulation during machine perfusion.

PINK1 ameliorates acute-on-chronic liver failure by inhibiting apoptosis through mTORC2/AKT signaling

Acute-on-chronic liver failure (ACLF) is a lethal syndrome with a remarkable short-term death rate. Even worse, effective internal medicine therapies are currently lacking. Increasing evidence indicates apoptosis plays a critical role in the progression of liver failure. PINK1 has an essential function in maintaining cell survival. However, the role and underlying mechanism of PINK1 in apoptosis in ACLF are incompletely understood. Herein, our team discovered that PINK1 remarkably improved ACLF, featured by a reduction in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and an amelioration in the gross and microscopy histopathology appearance of hepatic tissues. Meanwhile, PINK1 affected cleaved caspase-3 expression via mTORC2/AKT, and this effect was eliminated after further intervention with Rictor or AKT. Overall, these findings indicate that PINK1 participates in the regulation of multiple biological functions, including hepatic cell growth and apoptosis in ACLF via the mTORC2/AKT signaling pathway. The present research offers a solid theory-wise foundation for the clinic applications of PINK1 as a valid target for ACLF treatment to reverse or postpone the development of ACLF.

Cleavage-Mediated Regulation of Myd88 Signaling by Inflammasome-Activated Caspase-1

Coordination among multiple signaling pathways ensures an appropriate immune response, where a signaling pathway may impair or augment another signaling pathway. Here, we report a negative feedback regulation of signaling through the key innate immune mediator MyD88 by inflammasome-activated caspase-1. NLRP3 inflammasome activation impaired agonist- or infection-induced TLR signaling and cytokine production through the proteolytic cleavage of MyD88 by caspase-1. Site-specific mutagenesis was used to identify caspase-1 cleavage site within MyD88 intermediary segment. Different cleavage site location within MyD88 defined the functional consequences of MyD88 cleavage between mouse and human cells. LPS/monosodium urate–induced mouse inflammation model corroborated the physiological role of this mechanism of regulation, that could be reversed by chemical inhibition of NLRP3. While Toll/interleukin-1 receptor (TIR) domain released by MyD88 cleavage additionally contributed to the inhibition of signaling, Waldenström’s macroglobulinemia associated MyD88^L265P mutation is able to evade the caspase-1-mediated inhibition of MyD88 signaling through the ability of its TIR^L265P domain to recruit full length MyD88 and facilitate signaling. The characterization of this mechanism reveals an additional layer of innate immunity regulation.

Novel Targets and Therapeutic Strategies to Protect Against Hepatic Ischemia Reperfusion Injury

Hepatic ischemia reperfusion injury (IRI), a fascinating topic that has drawn a lot of interest in the last few years, is a major complication caused by a variety of clinical situations, such as liver transplantation, severe trauma, vascular surgery, and hemorrhagic shock. The IRI process involves a series of complex events, including mitochondrial deenergization, metabolic acidosis, adenosine-5'-triphosphate depletion, Kupffer cell activation, calcium overload, oxidative stress, and the upregulation of pro-inflammatory cytokine signal transduction. A number of protective strategies have been reported to ameliorate IRI, including pharmacological therapy, ischemic pre-conditioning, ischemic post-conditioning, and machine reperfusion. However, most of these strategies are only at the stage of animal model research at present, and the potential mechanisms and exact therapeutic targets have yet to be clarified. IRI remains a main cause of postoperative liver dysfunction, often leading to postoperative morbidity or even mortality. Very recently, it was reported that the activation of peroxisome proliferator-activated receptor γ (PPARγ), a member of a superfamily of nuclear transcription factors activated by agonists, can attenuate IRI in the liver, and FAM3A has been confirmed to mediate the protective effect of PPARγ in hepatic IRI. In addition, non-coding RNAs, like LncRNAs and miRNAs, have also been reported to play a pivotal role in the liver IRI process. In this review, we presented an overview of the latest advances of treatment strategies and proposed potential mechanisms behind liver IRI. We also highlighted the role of several important molecules (PPARγ, FAM3A, and non-coding RNAs) in protecting against hepatic IRI. Only after achieving a comprehensive understanding of potential mechanisms and targets behind IRI can we effectively ameliorate IRI in the liver and achieve better therapeutic effects.

The impact of emricasan on chronic liver diseases: current data

Immoderate caspase-mediated apoptosis in chronic liver injury is a crucial driver of sustained HSC activation and worsening hepatic inflammation as well as fibrosis, with the ultimate outcome of liver cirrhosis and its consequences. Therefore, the inhibition of hepatocyte apoptosis by caspase cascade blockage may be a promising therapeutic strategy to achieve fibrosis regression in chronic liver diseases. Emricasan is a broad-spectrum, liver-targeted caspase inhibitor with a favorable pharmacokinetic profile, characterized by prolonged retention in the liver and low systemic exposure after oral administration. In animal models, emricasan had a clear intrahepatic anti-apoptotic effect with consequent elimination of circulating pro-inflammatory cytokines and favorable impact in liver fibrogenesis and portal pressure. Even though, this intrahepatic drug effect confirmed in human clinical trials, no clear linkage was emerged with portal hypertension, liver function or liver histology in both non-cirrhotic and cirrhotic patients except from a subgroup of patients with high MELD score (> 15) or severe HVPG (> 16 mmHg). As emricasan treatment appeared safe and well-tolerated, irrespective the severity of liver disease, more studies are required to clarify better these subgroups of patients who may benefit most from this drug.

Proximal Tubule p53 in Cold Storage/Transplantation-Associated Kidney Injury and Renal Graft Dysfunction

Kidney injury associated with cold storage/transplantation is a primary factor for delayed graft function and poor outcome of renal transplants. p53 contributes to both ischemic and nephrotoxic kidney injury, but its involvement in kidney cold storage/transplantation is unclear. Here, we report that p53 in kidney proximal tubules plays a critical role in cold storage/transplantation kidney injury and inhibition of p53 can effectively improve the histology and function of transplanted kidneys. In a mouse kidney cold storage/transplantation model, we detected p53 accumulation in proximal tubules in a cold storage time-dependent manner, which correlated with tubular injury and cell death. Pifithrin-α, a pharmacologic p53 inhibitor, could reduce acute tubular injury, apoptosis and inflammation at 24 h after cold storage/transplantation. Similar effects were shown by the ablation of p53 from proximal tubule cells. Notably, pifithrin-α also ameliorated kidney injury and improved the function of transplanted kidneys in 6 days when it became the sole life-supporting kidney in recipient mice. in vitro, cold storage followed by rewarming induced cell death in cultured proximal tubule cells, which was accompanied by p53 activation and suppressed by pifithrin-α and dominant-negative p53. Together, these results support a pathogenic role of p53 in cold storage/transplantation kidney injury and demonstrate the therapeutic potential of p53 inhibitors.

Caspase-3-dependent peritubular capillary dysfunction is pivotal for the transition from acute to chronic kidney disease after acute ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a major risk factor for chronic renal failure. Caspase-3, an effector responsible for apoptosis execution, is activated within the peritubular capillary (PTC) in the early stage of IRI-induced acute kidney injury (AKI). Recently, we showed that caspase-3-dependent microvascular rarefaction plays a key role in fibrosis development after mild renal IRI. Here, we further characterized the role of caspase-3 in microvascular dysfunction and progressive renal failure in both mild and severe AKI, by performing unilateral renal artery clamping for 30/60 min with contralateral nephrectomy in wild-type (C57BL/6) or caspase-3-/- mice. In both forms of AKI, caspase-3-/- mice showed better long-term outcomes despite worse initial tubular injury. After 3 wk, they showed reduced PTC injury, decreased PTC collagen deposition and α-smooth muscle actin expression, and lower tubular injury scores compared with wild-type animals. Caspase-3-/- mice with severe IRI also showed better preservation of long-term renal function. Intravital imaging and microcomputed tomography revealed preserved PTC permeability and better terminal capillary density in caspase-3-/- mice. Collectively, these results demonstrate the pivotal importance of caspase-3 in regulating long-term renal function after IRI and establish the predominant role of PTC dysfunction as a major contributor to progressive renal dysfunction.NEW & NOTEWORTHY Our findings demonstrate the pivotal importance of caspase-3 in regulating renal microvascular dysfunction, fibrogenesis, and long-term renal impairment after acute kidney injury induced by ischemia-reperfusion injury. Furthermore, this study establishes the predominant role of peritubular capillary integrity as a major contributor to progressive renal dysfunction after ischemia-reperfusion injury.

Ursolic acid reduces hepatocellular apoptosis and alleviates alcohol-induced liver injury via irreversible inhibition of CASP3 in vivo

Alcoholic liver disease (ALD) is one of the pathogenic factors of chronic liver disease with the highest clinical morbidity worldwide. Ursolic acid (UA), a pentacyclic terpenoid carboxylic acid, has shown many health benefits including antioxidative, anti-inflammatory, anticancer, and hepatoprotective activities. We previously found that UA was metabolized in vivo into epoxy-modified UA containing an epoxy electrophilic group and had the potential to react with nucleophilic groups. In this study we prepared an alkynyl-modified UA (AM-UA) probe for tracing and capturing the target protein of UA from liver in mice, then investigated the mode by which UA bound to its target in vivo. By conducting proteome identification and bioinformatics analysis, we identified caspase-3 (CASP3) as the primary target protein of UA associated with liver protection. Molecule docking analysis showed that the epoxy group of the UA metabolite reacted with Cys-163 of CASP3, forming a covalent bond with CASP3. The binding mode of the UA metabolites (UA, CM-UA, and EM-UA) was verified by biochemical evaluation, demonstrating that the epoxy group produced by metabolism played an important role in the inhibition of CASP3. In alcohol-treated HepG2 cells, pretreatment with the UA metabolite (10 μM) irreversibly inhibited CASP3 activities, and subsequently decreased the cleavage of PARP and cell apoptosis. Finally, pre-administration of UA (20-80 mg· kg-1 per day, ig, for 1 week) dose-dependently alleviated alcohol-induced liver injury in mice mainly via the inhibition of CASP3. In conclusion, this study demonstrates that UA is a valuable lead compound for the treatment of ALD.

Cell death pathways: intricate connections and disease implications

Various forms of cell death have been identified over the last decades with each relying on a different subset of proteins for the activation and execution of their respective pathway(s). In addition to the three best characterized pathways-apoptosis, necroptosis, and pyroptosis-other forms of regulated cell death including autophagy-dependent cell death (ADCD), mitochondrial permeability transition pore (MPTP)-mediated necrosis, parthanatos, NETosis and ferroptosis, and their relevance for organismal homeostasis are becoming better understood. Importantly, it is increasingly clear that none of these pathways operate alone. Instead, a more complex picture is emerging with many pathways sharing components and signaling principles. Finally, a number of cell death regulators are implicated in human diseases and represent attractive therapeutic targets. Therefore, better understanding of physiological and mechanistic aspects of cell death signaling should yield improved reagents for addressing unmet medical needs.

Hepatic CEACAM1 expression indicates donor liver quality and prevents early transplantation injury

Although CEACAM1 (CC1) glycoprotein resides at the interface of immune liver injury and metabolic homeostasis, its role in orthotopic liver transplantation (OLT) remains elusive. We aimed to determine whether/how CEACAM1 signaling may affect hepatic ischemia-reperfusion injury (IRI) and OLT outcomes. In the mouse, donor liver CC1 null mutation augmented IRI-OLT (CC1-KO→WT) by enhancing ROS expression and HMGB1 translocation during cold storage, data supported by in vitro studies where hepatic flush from CC1-deficient livers enhanced macrophage activation in bone marrow-derived macrophage cultures. Although hepatic CC1 deficiency augmented cold stress-triggered ASK1/p-p38 upregulation, adjunctive ASK1 inhibition alleviated IRI and improved OLT survival by suppressing p-p38 upregulation, ROS induction, and HMGB1 translocation (CC1-KO→WT), whereas ASK1 silencing (siRNA) promoted cytoprotection in cold-stressed and damage-prone CC1-deficient hepatocyte cultures. Consistent with mouse data, CEACAM1 expression in 60 human donor liver biopsies correlated negatively with activation of the ASK1/p-p38 axis, whereas low CC1 levels associated with increased ROS and HMGB1 translocation, enhanced innate and adaptive immune responses, and inferior early OLT function. Notably, reduced donor liver CEACAM1 expression was identified as one of the independent predictors for early allograft dysfunction (EAD) in human OLT patients. Thus, as a checkpoint regulator of IR stress and sterile inflammation, CEACAM1 may be considered as a denominator of donor hepatic tissue quality, and a target for therapeutic modulation in OLT recipients.

LPS Preconditioning Attenuates Apoptosis Mechanism by Inhibiting NF-κB and Caspase-3 Activity: TLR4 Pre-activation in the Signaling Pathway of LPS-Induced Neuroprotection

Neuroinflammation, an inflammatory response within the nervous system, has been shown to be implicated in the progression of various neurodegenerative diseases. Recent in vivo studies showed that lipopolysaccharide (LPS) preconditioning provides neuroprotection by activating Toll-like receptor 4 (TLR4), one of the members for pattern recognition receptor (PRR) family that play critical role in host response to tissue injury, infection, and inflammation. Pre-exposure to low dose of LPS could confer a protective state against cellular apoptosis following subsequent stimulation with LPS at higher concentration, suggesting a role for TLR4 pre-activation in the signaling pathway of LPS-induced neuroprotection. However, the precise molecular mechanism associated with this protective effect is not well understood. In this article, we provide an overall review of the current state of our knowledge about LPS preconditioning in attenuating apoptosis mechanism and conferring neuroprotection via TLR4 signaling pathway.

Liver Ischemia Reperfusion Injury, Enhanced by Trained Immunity, Is Attenuated in Caspase 1/Caspase 11 Double Gene Knockout Mice

Ischemia reperfusion injury (IRI) during liver transplantation increases morbidity and contributes to allograft dysfunction. There are no therapeutic strategies to mitigate IRI. We examined a novel hypothesis: caspase 1 and caspase 11 serve as danger-associated molecular pattern (DAMPs) sensors in IRI. By performing microarray analysis and using caspase 1/caspase 11 double-knockout (Casp DKO) mice, we show that the canonical and non-canonical inflammasome regulators are upregulated in mouse liver IRI. Ischemic pre (IPC)- and post-conditioning (IPO) induce upregulation of the canonical and non-canonical inflammasome regulators. Trained immunity (TI) regulators are upregulated in IPC and IPO. Furthermore, caspase 1 is activated during liver IRI, and Casp DKO attenuates liver IRI. Casp DKO maintained normal liver histology via decreased DNA damage. Finally, the decreased TUNEL assay-detected DNA damage is the underlying histopathological and molecular mechanisms of attenuated liver pyroptosis and IRI. In summary, liver IRI induces the upregulation of canonical and non-canonical inflammasomes and TI enzyme pathways. Casp DKO attenuate liver IRI. Development of novel therapeutics targeting caspase 1/caspase 11 and TI may help mitigate injury secondary to IRI. Our findings have provided novel insights on the roles of caspase 1, caspase 11, and inflammasome in sensing IRI derived DAMPs and TI-promoted IRI-induced liver injury.

Pan-caspase inhibitor F573 mitigates liver ischemia reperfusion injury in a murine model

Background

Liver ischemia reperfusion injury (IRI) remains a challenge in liver transplantation. A number of compounds have previously demonstrated efficacy in mitigating IRI. Herein, we applied three specific additive strategies to a mouse IRI screening model to determine their relative potencies in reducing such injury, with a view to future testing in a large animal and clinical ex situ normothermic perfusion setting: 1) F573, a pan-caspase inhibitor, 2) anti-inflammatory anakinra and etanrecept and 3) BMX-001, a mimetic of superoxide dismutase.

Methods

A non-lethal liver ischemia model in mice was used. Additives in the treatment groups were given at fixed time points before induction of injury, compared to a vehicle group that received no therapeutic treatment. Mice were recovered for 6 hours following the ischemic insult, at which point blood and tissue samples were obtained. Plasma was processed for transaminase levels. Whole liver tissue samples were processed for histology, markers of apoptosis, oxidative stress, and cytokine levels.

Results

In an in vivo murine IRI model, the F573 treatment group demonstrated statistically lower alanine aminotransferase (ALT) levels (p = 0.01), less evidence of apoptosis (p = 0.03), and lower cytokine levels compared to vehicle. The etanercept with anakinra treatment group demonstrated significantly lower cytokine levels. The BMX-001 group demonstrated significantly decreased apoptosis (p = 0.01) evident on TUNEL staining.

Conclusions

The administration of pan-caspase inhibitor F573 in a murine in vivo model likely mitigates liver IRI based on decreased markers of cellular injury, decreased evidence of apoptosis, and improved cytokine profiles. Anakinra with etanercept, and BMX-001 did not demonstrate convincing efficacy at reducing IRI in this model, and likely need further optimization. The positive findings set rational groundwork for future translational studies of applying F573 during normothermic ex situ liver perfusion, with the aim of improving the quality of marginal grafts.

Combined obeticholic acid and apoptosis inhibitor treatment alleviates liver fibrosis

Obeticholic acid (OCA), the first FXR-targeting drug, has been claimed effective in the therapy of liver fibrosis. However, recent clinical trials indicated that OCA might not be effective against liver fibrosis, possibly due to the lower dosage to reduce the incidence of the side-effect of pruritus. Here we propose a combinatory therapeutic strategy of OCA and apoptosis inhibitor for combating against liver fibrosis. CCl4-injured mice, d-galactosamine/LPS (GalN/LPS)-treated mice and cycloheximide/TNFα (CHX/TNFα)-treated HepG2 cells were employed to assess the effects of OCA, or together with IDN-6556, an apoptosis inhibitor. OCA treatment significantly inhibited hepatic stellate cell (HSC) activation/proliferation and prevented fibrosis. Elevated bile acid (BA) levels and hepatocyte apoptosis triggered the activation and proliferation of HSCs. OCA treatment reduced BA levels but could not inhibit hepatocellular apoptosis. An enhanced anti-fibrotic effect was observed when OCA was co-administrated with IDN-6556. Our study demonstrated that OCA inhibits HSCs activation/proliferation partially by regulating BA homeostasis and thereby inhibiting activation of HSCs. The findings in this study suggest that combined use of apoptosis inhibitor and OCA at lower dosage represents a novel therapeutic strategy for liver fibrosis.

Liver graft preservation methods during cold ischemia phase and normothermic machine perfusion

The growing demand for donor organs requires measures to expand donor pool. Those include extended criteria donors, such as elderly people, steatotic livers, donation after cardiac death, etc. Static cold storage to reduce metabolic requirements developed by Collins in late 1960s is the mainstay and the golden standard for donated organ protection. Hypothermic machine perfusion provides dynamic organ preservation at 4°C with protracted infusion of metabolic substrates to the graft during the ex vivo period. It has been used instead of static cold storage or after it as short perfusion in transplant center. Normothermic machine perfusion (NMP) delivers oxygen, and nutrition at physiological temperature mimicking regular environment in order to support cellular function. This would minimize effects of ischemia/reperfusion injury. Potentially, NMP may help to estimate graft functionality before implantation into a recipient. Clinical studies demonstrated at least its non-inferiority or better outcomes vs static cold storage. Regular grafts donated after brain death could be safely preserved with convenient static cold storage. Except for prolonged ischemia time where hypothermic machine perfusion started in transplant center could be estimated to provide possible positive reconditioning effect. Use of hypothermic machine perfusion in regular donation instead of static cold storage or in extended criteria donors requires further investigation. Multicenter randomized clinical trial supposed to be completed in December 2021. Extended criteria donors need additional measures for graft storage and assessment until its implantation. NMP is actively evaluating promising method for this purpose. Future studies are necessary for precise estimation and confirmation to issue clinical practice recommendations.

Measuring Apoptosis and Necrosis in Cholestatic Liver Injury

Cholestasis can be induced by obstruction of bile ducts or intrahepatic toxicity of drugs and chemicals. However, the mode of cell death during cholestasis, i.e., apoptosis or necrosis, has been controversial. There are fundamental reasons for the controversies, both of which are discussed here, namely the design of experiments and the use of parameters with limited specificity for a certain mode of cell death. Based on the assumption that cholestatic liver injury is caused by accumulation of bile acids, rodent (mainly rat) hepatocytes have been exposed to hydrophobic, glycine-conjugated bile acids, which resulted in apoptotic cell death. The problems with this experimental design are that in rodents bile acids are predominantly taurine conjugated and rodent hepatocytes are never exposed to these levels of glycine-conjugated bile acids. In contrast, taurine-conjugated bile acids trigger inflammatory gene activation in rodent hepatocytes and a necro-inflammatory injury in vivo. On the other hand, human hepatocytes are more resistant to glycine-conjugated bile acids and die by necrosis when exposed to high biliary levels of these bile acids. In this chapter, we describe multiple assays including the caspase activity assay, which is specific for apoptosis, and the general cell death assays alanine aminotransferase or lactate dehydrogenase activities in cell culture medium or plasma. An increase in these enzyme activities without caspase activity indicates necrotic cell death. Thus, both the experimental design and the selection of cell death parameters are critical for the relevance of the experiments for the human pathophysiology.

Hepatic ischemia-reperfusion injury in liver transplant setting: mechanisms and protective strategies

Hepatic ischemia-reperfusion injury is a major cause of liver transplant failure, and is of increasing significance due to increased use of expanded criteria livers for transplantation. This review summarizes the mechanisms and protective strategies for hepatic ischemia-reperfusion injury in the context of liver transplantation. Pharmacological therapies, the use of pre-and post-conditioning and machine perfusion are discussed as protective strategies. The use of machine perfusion offers significant potential in the reconditioning of liver grafts and the prevention of hepatic ischemia-reperfusion injury, and is an exciting and active area of research, which needs more study clinically.

Apoptosis and necroptosis in the liver: a matter of life and death

Cell death represents a basic biological paradigm that governs outcomes and long-term sequelae in almost every hepatic disease condition. Acute liver failure is characterized by massive loss of parenchymal cells but is usually followed by restitution ad integrum. By contrast, cell death in chronic liver diseases often occurs at a lesser extent but leads to long-term alterations in organ architecture and function, contributing to chronic hepatocyte turnover, the recruitment of immune cells and activation of hepatic stellate cells. These chronic cell death responses contribute to the development of liver fibrosis, cirrhosis and cancer. It has become evident that, besides apoptosis, necroptosis is a highly relevant form of programmed cell death in the liver. Differential activation of specific forms of programmed cell death might not only affect outcomes in liver diseases but also offer novel opportunities for therapeutic intervention. Here, we summarize the underlying molecular mechanisms and open questions about disease-specific activation and roles of programmed cell death forms, their contribution to response signatures and their detection. We focus on the role of apoptosis and necroptosis in acute liver injury, nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH) and liver cancer, and possible translations into clinical applications.

Normothermic ex-vivo liver perfusion: where do we stand and where to reach?

Nowadays liver transplantation is considered as the treatment of choice, however, the scarcity of suitable donor organs limits the delivery of care to the end-stage liver disease patients leading to the death while on the waiting list. The advent of ex-situ normothermic machine perfusion (NMP) has emerged as an alternative to the standard organ preservation technique, static cold storage (SCS). The newer technique promises to not only restore the normal metabolic activity but also attempt to recondition the marginal livers back to the pristine state, which are otherwise more susceptible to ischemic injury and foster the poor post-transplant outcomes. Areas covered: An extensive search of all the published literature describing the role of NMP based device in liver transplantation as an alternative to SCS was made on MEDLINE, EMBASE, Cochrane, BIOSIS, Crossref, Scopus databases and clinical trial registry on 10 May 2018. Expert commentary: The main tenet of NMP is the establishment of the physiological milieu, which permits aerobic metabolism to continue through out the period of preservation and limits the effects of ischemia-reperfusion (I/R) injury. In addition, by assessing the various metabolic and synthetic parameters the viability and suitability of donor livers for transplantation can be determined. This important technological advancement has scored satisfactorily on the safety and efficacy parameters in preliminary clinical studies. The present review suggests that NMP can offer the opportunity to assess and safely utilize the marginal donor livers if deemed appropriate for the transplantation. However, ongoing trials will determine its full potential and further adoption.

Recombinant relaxin protects liver transplants from ischemia damage by hepatocyte glucocorticoid receptor: From bench-to-bedside

Hepatic ischemia-reperfusion injury (IRI) represents a major risk factor of early graft dysfunction and acute/chronic rejection as well as a key obstacle to expanding the donor pool in orthotopic liver transplantation (OLT). Although glucocorticoid receptor (GR) signaling may enhance cytoprotective programs, clinical use of glucocorticoid is limited because of adverse effects, whereas clinical relevance of GR-facilitated cytoprotection in OLT remains unknown. We aimed to evaluate the significance of hepatic GR in clinical OLT and verify the impact of recombinant human relaxin (rhRLX), which may function as a GR agonist in a tissue/disease-specific manner. Fifty-one OLT patients were recruited under an institutional research board (IRB) protocol. Liver biopsies were collected after cold storage (presurgery) and 2 hours postreperfusion (before abdominal closure), followed by western blotting-assisted hepatic analyses. Forty-three percent of OLTs failed to increase GR perioperatively under surgical stress. Post-/pre-GR ratios at postoperative day 1 correlated negatively with serum aspartate aminotransferase (AST)/cleaved caspase-3 and positively with B-cell lymphoma-extra large (Bcl-xL)/B-cell lymphoma 2 (Bcl-2) levels. In a murine OLT model with extended (18-hour) cold storage, treatment with rhRLX ameliorated ischemia-reperfusion (IR) damage and improved survival while up-regulating hepatocyte GR and Bcl-xL/Bcl-2 expression in OLT. rhRLX-induced GR suppressed hepatocyte high-mobility group box 1 (HMGB1) translocation/release, accompanied by decreased Toll-like receptor 4 (TLR4)/receptor for advanced glycation end products (RAGE), suppressed interleukin 1 beta (IL1β), chemokine (C-C motif) ligand 2 (CCL2), C-X-C motif chemokine (CXCL)10, tumor necrosis factor alpha (TNFα), CXCL1, and CXCL2 levels, and attenuated neutrophil/macrophage accumulation in OLT. Inhibition of GR in hepatocyte culture and in OLT diminished rhRLX-mediated cytoprotection.

CONCLUSION

This translational study underscores the role of rhRLX-GR signaling as a regulator of hepatocellular protection against IR stress in OLT. In the context of a recent phase III clinical trial demonstrating positive outcomes of rhRLX in patients with acute heart failure, studies on rhRLX for the management of IRI in OLT recipients are warranted. (Hepatology 2018;68:258-273).

The Role of Normothermic Perfusion in Liver Transplantation (TRaNsIT Study): A Systematic Review of Preliminary Studies

INTRODUCTION

The success of liver transplantation has been limited by the unavailability of suitable donor livers. The current organ preservation technique, i.e., static cold storage (SCS), is not suitable for marginal organs. Alternatively, normothermic machine perfusion (NMP) promises to recreate the physiological environment and hence holds promise for the better organ preservation. The objective of this systematic review is to provide an overview of the safety, benefits, and insight into the other potential useful parameters of NMP in the liver preservation.

MATERIAL AND METHODS

We searched the current literature following registration in the International Prospective Register of Systematic Reviews (PROSPERO) with registration number CRD42018086034 for prospective trials comparing the role of NMP device to SCS in liver transplant by searching the PubMed, EMBASE, Cochrane, BIOSIS, Crossref, and Scopus databases and clinical trial registry.

RESULTS

The literature search identified five prospective clinical trials (four being early phase single institutional and single randomized multi-institutional) comparing 187 donor livers on NMP device to 273 donor livers on SCS. The primary outcome of interest was to assess the safety and graft survival at day 30 after transplant following NMP of the donor liver. Secondary outcomes included were early allograft dysfunction (EAD) in the first seven days; serum measures of liver functions as bilirubin, aspartate aminotransferase (AST), alanine amino transferase (ALT), alkaline phosphatase (ALP), and international normalized ratio (INR) on days 1-7; major complications as defined by a Clavien-Dindo score ≥ 3; and patient and graft survival and biliary complications at six months. The peaked median AST level between days 1 and 7 in the five trials was 417-1252 U/L (range 84-15009 U/L) while on NMP and 839-1474 U/L (range 153-8786 U/L) in SCS group. The median bilirubin level on day 7 ranged within 25-79 µmol/L (range 8-344 µmol/l) and 30-47.53 µmol/l (range 9-340 µmol/l) in NMP and SCS groups, respectively. A single case of PNF was reported in NMP group in the randomized trial while none of the other preliminary studies reported any in either group. There was intertrial variability in EAD which ranged within 15-56% in NMP group while being within 23-37% in SCS group. Biliary complications observed in NMP group ranged from 0 to 20%. Single device malfunction was reported in randomized controlled trial leading to renouncement of transplant while none of the other trials reported any machine failure, although two user related device errors inadvertent were reported.

CONCLUSION

This review outlines that NMP not only demonstrated safety and efficacy but also provided the favourable environment of organ preservation, repair, and viability assessment to donor liver prior to the transplantation with low rate of posttransplantation complication as PNF, EAD, and biliary complication; however further studies are needed to broaden our horizon.

Emricasan, a pan-caspase inhibitor, improves survival and portal hypertension in a murine model of common bile-duct ligation

Development of portal hypertension (PHT) is a central prognostic factor in patients with cirrhosis. Circulating microparticles (MPs) are released by hepatocytes in a caspase-dependent manner, are increased in circulation of patients with cirrhosis, and contribute to PHT via induction of impaired vasoconstrictor responses. Here, we tested the hypothesis that emricasan, a pan-caspase inhibitor, ameliorates PHT and reduction in release of MPs. We used a short-term and long-term protocol following common bile-duct ligation (BDL) in C57BL/6 mice (10 and 20 days, respectively). Mice were treated daily via intraperitoneal injection with 10 mg/kg/day of emricasan or placebo. Circulating MP levels were analyzed using flow cytometry and function via ex vivo angiogenesis assays. In contrast to BDL-placebo group, nearly all BDL-emricasan-treated mice survived after long-term BDL. Assessment of portal pressure showed a significant increase in BDL-placebo mice compared to sham-placebo mice. In contrast, BDL-emricasan mice had significantly lower levels of portal pressure compared to BDL-placebo mice. Although emricasan treatment resulted in a decrease in fibrosis, the changes did not reach statistical significance, suggesting that the effects on PHT are at least in part independent of the anti-fibrotic effects of the drug. Following short-term BDL, hepatocellular cell death as well as liver fibrosis had improved and circulating MPs were significantly reduced in BDL-emricasan mice compared to BDL-placebo. Circulating MPs from BDL-placebo mice induced endothelial cell activation, and this was significantly reduced in MPs from BDL-emricasan mice. Our results indicate that emricasan treatment improves survival and PHT in a murine model of long-term BDL. Emricasan is a promising agent for the treatment of PHT.

KEY MESSAGE

Emricasan, a pan-caspase inhibitor, improves survival and portal hypertension induced by long-term bile-duct ligation (BDL) in mice Emricasan reduces liver damage, hepatocyte death, and fibrosis, following short-term BDL in mice, and these changes are associated with a decrease in circulating microparticle (MPs) Circulating MPs from BDL-placebo but not from BDL-emiricasan-treated mice activate endothelial cells ex vivo.

Ex situ liver perfusion: Organ preservation into the future

In recent years, remarkable progress has occurred in the development of technologies to support ex situ liver perfusion. Building upon extensive preclinical studies in large animal models, pilot and randomized clinical trials have been initiated, and preliminary outcomes suggest more optimal protection of both standard and extended criteria liver grafts. There currently exists an incredible opportunity and need to further refine this technology, determine appropriate viability measures to predict usable liver grafts, and to explore potent protective additive strategies to further optimize the quality of extended criteria organs. These findings will have major bearing in expanding the limited liver donor pool, and may save lives where up to a quarter of listed patients die on wait-lists. Herein we offer a brief overview of the history and current status of ex situ liver perfusion, and discuss future directions that will likely have major impact on the practice of clinical liver transplantation.

Kupffer cell depletion by gadolinium chloride aggravates liver injury after brain death in rats

Brain death (BD) impairs liver function in potential donors, and is associated with hormonal and metabolic changes or molecular effects with pro‑inflammatory activation. Resident macrophages in the liver named Kupffer cells (KCs) undergo pro‑ or anti‑inflammatory pathway activation, which affects liver function. However, the role of the KCs in liver dysfunction following BD has not been fully elucidated. The aim of the present study was to investigate the role of KCs in liver dysfunction in the context of BD and the effects of their inhibition by gadolinium chloride (GdCl3). Rats were randomly divided into the following groups: Control, BD with GdCl3 pretreatment and BD with normal saline pretreatment. Liver function, hepatic pathological histology and cytokine levels in the liver were assessed. Apoptosis and apoptosis‑related proteins [cleaved caspase‑3, caspase‑3 and apoptosis regulator Bcl‑2 (Bcl‑2)] were evaluated. GdCl3 significantly aggravated liver injury by elevating alanine aminotransferase and aspartate aminotransferase levels (P<0.05) by inhibiting KCs. Interleukin (IL)‑1β and tumor necrosis factor α levels in the GdCl3 group were significantly increased compared with those in the control and saline groups (P<0.01). However, IL‑10 levels in the GdCl3 group were significantly reduced compared with those in the saline group (P<0.05). Caspase‑3 and cleaved caspase‑3 activation, and apoptosis induction in the context of BD were also significantly aggravated by the depletion of KCs, whereas Bcl‑2 was significantly suppressed by the administration of GdCl3. The present study indicated that GdCl3 efficiently inhibits the activity of KCs, and is involved in the onset of liver injury through its effects on pro‑inflammatory and anti‑inflammatory activation. KCs are protective in the liver in the context of BD. This protection appears to be due to KCs secretion of the potent anti‑inflammatory cytokine IL‑10, suggesting that KCs are an attractive target for the prevention and treatment of liver injury in the context of BD in rats.

Neutralization of CD95 ligand protects the liver against ischemia-reperfusion injury and prevents acute liver failure

Ischemia-reperfusion injury is a common pathological process in liver surgery and transplantation, and has considerable impact on the patient outcome and survival. Death receptors are important mediators of ischemia-reperfusion injury, notably the signaling pathways of the death receptor CD95 (Apo-1/Fas) and its corresponding ligand CD95L. This study investigates, for the first time, whether the inhibition of CD95L protects the liver against ischemia-reperfusion injury. Warm ischemia was induced in the median and left liver lobes of C57BL/6 mice for 45 min. CD95Fc, a specific inhibitor of CD95L, was applied prior to ischemia. Hepatic injury was assessed via consecutive measurements of liver serum enzymes, histopathological assessment of apoptosis and necrosis and caspase assays at 3, 6, 12, 18 and 24 h after reperfusion. Serum levels of liver enzymes, as well as characteristic histopathological changes and caspase assays indicated pronounced features of apoptotic and necrotic liver damage 12 and 24 h after ischemia-reperfusion injury. Animals treated with the CD95L-blocker CD95Fc, exhibited a significant reduction in the level of serum liver enzymes and showed both decreased histopathological signs of parenchymal damage and decreased caspase activation. This study demonstrates that inhibition of CD95L with the CD95L-blocker CD95Fc, is effective in protecting mice from liver failure due to ischemia-reperfusion injury of the liver. CD95Fc could therefore emerge as a new pharmacological therapy for liver resection, transplantation surgery and acute liver failure.

Combination of Emricasan with Ponatinib Synergistically Reduces Ischemia/Reperfusion Injury in Rat Brain Through Simultaneous Prevention of Apoptosis and Necroptosis

Apoptosis and receptor-interacting protein kinase 1/3(RIPK1/3)-mediated necroptosis contribute to the cerebral ischemia/reperfusion (I/R) injury. Emricasan is an inhibitor of caspases in clinical trials for liver diseases while ponatinib could be a potential inhibitor for RIPK1/3. This study aims to investigate the effect of emricasan and/or ponatinib on cerebral I/R injury and the underlying mechanisms. Firstly, we evaluated the status of apoptosis and necroposis in a rat model of cerebral I/R under different conditions, which showed noticeable apoptosis and necroptosis under condition of 2-h ischemia and 24-h reperfusion; next, the preventive or therapeutic effect of emricasan or ponatinib on cerebral I/R injury was tested. Administration of emricasan or ponatinib either before or after ischemia could decrease the neurological deficit score and infarct volume; finally, the combined therapeutic effect of emricasan with ponatinib on I/R injury was examined. Combined application of emricasan and ponatinib could further decrease the I/R injury compared to single application. Emricasan decreased the activities of capase-8/-3 in the I/R-treated brain but not the protein levels of necroptosis-relevant proteins: RIPK1, RIPK3, and mixed lineage kinase domain-like (MLKL), whereas ponatinib suppressed the expressions of these proteins but not the activities of capase-8/-3. Combination of emricasan with ponatinib could suppress both capase-8/-3 and necroptosis-relevant proteins. Based on these observations, we conclude that combination of emricasan with ponatinib could synergistically reduce I/R injury in rat brain through simultaneous prevention of apoptosis and necroptosis. Our findings might lay a basis on extension of the clinical indications for emricasan and ponatinib in treating ischemic stroke.

Berberine inhibits the chemotherapy-induced repopulation by suppressing the arachidonic acid metabolic pathway and phosphorylation of FAK in ovarian cancer

OBJECTIVES

Cytotoxic chemotherapy is an effective and traditional treatment of ovarian cancer. However, chemotherapy-induced apoptosis may also trigger and ultimately accelerate the repopulation of the small number of adjacent surviving cells. This study mainly focused on the tumour cell repopulation caused by chemotherapy in ovarian cancer and the adjunctive/synergistic effect of Berberine on the prevention of tumour repopulation.

MATERIALS AND METHODS

The transwell system was used to mimic the co-culture of surviving ovarian cancer cells in the microenvironment of cytotoxic chemotherapy-treated dying cells. Tumour cell proliferation was observed by crystal violet staining. AA and PGE₂ levels were measured by ELISA, and changes of protein expression were analysed by Western blot.

RESULTS

Chemotherapy drug VP16 treatment triggered AA pathway, leading to the elevated PGE₂ level, and ultimately enhanced the repopulation of ovarian cancer cells. Berberine can block the caspase 3-iPLA₂ -AA-COX-2-PGE₂ pathway by inhibiting the expression of iPLA₂ and COX-2. Berberine can also reverse the increased phosphorylation of FAK caused by abnormal PGE₂ level and thus reverse the repopulation of ovarian cancer cells after VP16 treatment.

CONCLUSIONS

Our observation suggested that Berberine could inhibit the chemotherapy-induced repopulation of ovarian cancer cells by suppressing the AA pathway and phosphorylation of FAK. And these findings implicated a novel combined use of Berberine and chemotherapeutics, which might prevent ovarian cancer recurrence by abrogating early tumour repopulation.

Sirtuin 1 attenuates inflammation and hepatocellular damage in liver transplant ischemia/Reperfusion: From mouse to human

Hepatic ischemia/reperfusion injury (IRI), an inevitable antigen-independent inflammation response in cadaveric liver transplantation, correlates with poor early graft function, rejection episodes, and contributes to donor organ shortage. Sirtuin 1 (SIRT1) is a histone deacetylase that may regulate inflammatory cell activity and manage liver function in IRI, though its functional role and clinical relevance remains to be elucidated. We investigated the efficacy of SIRT1 activation in a murine liver IRI model and verified the concept of putative SIRT1-mediated hepatoprotection in clinical liver transplantation. In the experimental arm, mice were subjected to 90 minutes of liver partial warm ischemia followed by 6 hours of reperfusion with or without adjunctive SIRT1 activation in vivo (resveratrol [Res]). In parallel, bone marrow-derived macrophage (BMDM) or spleen lymphocyte cultures were treated with Res. In the clinical arm, liver biopsies from 21 adult primary liver transplant patients (2 hours after reperfusion) were divided into "low" (n = 11) versus "high" (n = 10) SIRT1 expression groups, assessed by Western blots. Treatment with Res attenuated murine liver IRI while up-regulating SIRT1, suppressing leukocyte infiltration, and decreasing proinflammatory cytokine programs. SIRT1 silencing (small interfering RNA) in BMDM cultures enhanced inflammatory cytokine programs, whereas addition of Res decreased proinflammatory response in a SIRT1-dependent manner. In addition, Res decreased interferon γ production in liver-infiltrating and spleen lymphocyte cultures. Human liver transplants with high SIRT1 levels showed improved hepatocellular function and superior survival (P = 0.04), accompanied by lower proinflammatory cytokine profile. In conclusion, our translational study is the first to identify SIRT1 as a regulator of hepatocellular function in human liver transplant recipients under ischemia/reperfusion stress. By targeting innate and adaptive immune activation, manipulation of SIRT1 signaling should be considered as a novel means to combat inflammation in liver transplantation. Liver Transplantation 23 1282-1293 2017 AASLD.

Practical Recommendations for Long-term Management of Modifiable Risks in Kidney and Liver Transplant Recipients: A Guidance Report and Clinical Checklist by the Consensus on Managing Modifiable Risk in Transplantation (COMMIT) Group

Short-term patient and graft outcomes continue to improve after kidney and liver transplantation, with 1-year survival rates over 80%; however, improving longer-term outcomes remains a challenge. Improving the function of grafts and health of recipients would not only enhance quality and length of life, but would also reduce the need for retransplantation, and thus increase the number of organs available for transplant. The clinical transplant community needs to identify and manage those patient modifiable factors, to decrease the risk of graft failure, and improve longer-term outcomes.COMMIT was formed in 2015 and is composed of 20 leading kidney and liver transplant specialists from 9 countries across Europe. The group's remit is to provide expert guidance for the long-term management of kidney and liver transplant patients, with the aim of improving outcomes by minimizing modifiable risks associated with poor graft and patient survival posttransplant.The objective of this supplement is to provide specific, practical recommendations, through the discussion of current evidence and best practice, for the management of modifiable risks in those kidney and liver transplant patients who have survived the first postoperative year. In addition, the provision of a checklist increases the clinical utility and accessibility of these recommendations, by offering a systematic and efficient way to implement screening and monitoring of modifiable risks in the clinical setting.

Pre-conditions for eliminating mitochondrial dysfunction and maintaining liver function after hepatic ischaemia reperfusion

The liver, the largest organ with multiple synthesis and secretion functions in mammals, consists of hepatocytes and Kupffer, stem, endothelial, stellate and other parenchymal cells. Because of early and extensive contact with the external environment, hepatic ischaemia reperfusion (IR) may result in mitochondrial dysfunction, autophagy and apoptosis of cells and tissues under various pathological conditions. Because the liver requires a high oxygen supply to maintain normal detoxification and synthesis functions, it is extremely susceptible to ischaemia and subsequent reperfusion with blood. Consequently, hepatic IR leads to acute or chronic liver failure and significantly increases the total rate of morbidity and mortality through multiple regulatory mechanisms. An increasing number of studies indicate that mitochondrial structure and function are impaired after hepatic IR, but that the health of liver tissues or liver grafts can be effectively rescued by attenuation of mitochondrial dysfunction. In this review, we mainly focus on the subsequent therapeutic interventions related to the conservation of mitochondrial function involved in mitigating hepatic IR injury and the potential mechanisms of protection. Because mitochondria are abundant in liver tissue, clarification of the regulatory mechanisms between mitochondrial dysfunction and hepatic IR should shed light on clinical therapies for alleviating hepatic IR‐induced injury.

Microcystin-LR induced liver injury in mice and in primary human hepatocytes is caused by oncotic necrosis

Microcystins are a group of toxins produced by freshwater cyanobacteria. Uptake of microcystin-leucine arginine (MC-LR) by organic anion transporting polypeptide 1B2 in hepatocytes results in inhibition of protein phosphatase 1A and 2A, and subsequent cell death. Studies performed in primary rat hepatocytes demonstrate prototypical apoptosis after MC-LR exposure; however, no study has directly tested whether apoptosis is critically involved in vivo in the mouse, or in human hepatocytes. MC-LR (120 μg/kg) was administered to C57BL/6J mice and cell death was evaluated by alanine aminotransferase (ALT) release, caspase-3 activity in the liver, and histology. Mice exposed to MC-LR had increases in plasma ALT values, and hemorrhage in the liver, but no increase in capase-3 activity in the liver. Pre-treatment with the pan-caspase inhibitor z-VAD-fmk failed to protect against cell death measured by ALT, glutathione depletion, or hemorrhage. Administration of MC-LR to primary human hepatocytes resulted in significant toxicity at concentrations between 5 nM and 1 μM. There were no elevated caspase-3 activities and pretreatment with z-VAD-fmk failed to protect against cell death in human hepatocytes. MC-LR treated human hepatocytes stained positive for propidium iodide, indicating membrane instability, a marker of necrosis. Of note, both increases in PI positive cells, and increases in lactate dehydrogenase release, occurred before the onset of complete actin filament collapse. In conclusion, apoptosis does not contribute to MC-LR-induced cell death in the in vivo mouse model or in primary human hepatocytes in vitro. Thus, targeting necrotic cell death mechanisms will be critical for preventing microcystin-induced liver injury.

Functional genetics-directed identification of novel pharmacological inhibitors of FAS- and TNF-dependent apoptosis that protect mice from acute liver failure

shRNA-mediated gene-silencing technology paired with cell-based functional readouts reveals potential targets directly, providing an opportunity to identify drugs against the target without knowing the precise role of the target in the pathophysiological processes of interest. By screening a lentiviral shRNA library targeting for major components of human signaling pathways and known drug targets, we identified and validated both canonical as well as 52 novel mediators of FAS and TNF ligand-induced apoptosis. Presence of potential therapeutic targets among these mediators was confirmed by demonstration of in vivo activity of siRNAs against four identified target candidates that protected mice from acute liver failure (ALF), a life-threatening disease with known involvement of death receptor (DR)-mediated apoptosis. Network-based modeling was used to predict small-molecule inhibitors for several candidate apoptosis mediators, including somatostatin receptor 5 (SSTR5) and a regulatory subunit of PP2A phosphatase, PPP2R5A. Remarkably, pharmacological inhibition of either SSTR5 or PPP2R5A reduced apoptosis induced by either FASL or TNF in cultured cells and dramatically improved survival in several mouse models of ALF. These results demonstrate the utility of loss-of-function genetic screens and network-based drug-repositioning methods for expedited identification of targeted drug candidates and revealed pharmacological agents potentially suitable for treatment of DR-mediated pathologies.

Advances in treatment strategies for ischemia reperfusion injury

INTRODUCTION

Ischemia-reperfusion injury (IRI) involves a complex sequence of events and limits the outcome of various surgical interventions. Clinical trials, based on the data of experimental models, aim to prove whether a pharmacological or technical approach could be suitable to provide a beneficial effect in humans. Due to the complexity of IRI, few pharmacological treatments have been investigated in clinical Phase III.

AREAS COVERED

In this review we report clinical trials that test specific drugs in clinical trials of organ transplantation. These studies form part of Phase II trials and examine the administration of caspase inhibitors, P-selectin antagonist or an antioxidant component in order to attenuate cold IRI during transplantation. Moreover, we provide a brief description of drugs tested on trials of different clinical situations associated to IRI, such as the coronary artery bypass graft surgery and percutaneous coronary intervention.

EXPERT OPINION

Future clinical trials could be centered on the application of techniques suitable for organs with increased vulnerability toward IRI. Furthermore, the standardization of reliable biomarkers and a careful estimation of the impact of high risk factors may be the key in order to achieve a more critical evaluation of the obtained results.

Conditioning With Sevoflurane in Liver Transplantation: Results of a Multicenter Randomized Controlled Trial

BACKGROUND

During times of organ scarcity and extended use of liver grafts, protective strategies in transplantation are gaining importance. We demonstrated in the past that volatile anesthetics such as sevoflurane attenuate ischemia-reperfusion injury during liver resection. In this randomized study, we examined if volatile anesthetics have an effect on acute graft injury and clinical outcomes after liver transplantation.

METHODS

Cadaveric liver transplant recipients were enrolled from January 2009 to September 2012 at 3 University Centers (Zurich/Sao Paulo/Ghent). Recipients were randomly assigned to propofol (control group) or sevoflurane anesthesia. Postoperative peak of aspartate transaminase was defined as primary endpoint, secondary endpoints were early allograft dysfunction, in-hospital complications, intensive care unit, and hospital stay.

RESULTS

Ninety-eight recipients were randomized to propofol (n = 48) or sevoflurane (n = 50). Median peak aspartate transaminase after transplantation was 925 (interquartile range, 512-3274) in the propofol and 1097 (interquartile range, 540-2633) in the sevoflurane group. In the propofol arm, 11 patients (23%) experienced early allograft dysfunction, 7 (14%) in the sevoflurane one (odds ratio, 0.64 (0.20 to 2.02, P = 0.45). There were 4 mortalities (8.3%) in the propofol and 2 (4.0%) in the sevoflurane group. Overall and major complication rates were not different. An effect on clinical outcomes was observed favoring the sevoflurane group (less severe complications), but without significance.

CONCLUSIONS

This first multicenter trial comparing propofol with sevoflurane anesthesia in liver transplantation shows no difference in biochemical markers of acute organ injury and clinical outcomes between the 2 regimens. Sevoflurane has no significant added beneficial effect on ischemia-reperfusion injury compared to propofol.

TIFA, an inflammatory signaling adaptor, is tumor suppressive for liver cancer

TIFA (TNF receptor associated factor (TRAF)-interacting protein with a Forkhead-associated (FHA) domain), also called T2BP, was first identified using a yeast two-hybrid screening. TIFA contains a FHA domain, which directly binds phosphothreonine and phosphoserine, and a consensus TRAF6-binding motif. TIFA-mediated oligomerization and poly-ubiquitinylation of TRAF6 mediates signaling downstream of the Tumor necrosis factor alpha receptor 1 (TNFaR-I) and interleukin-1/Toll-like receptor 4 (TLR4) pathways. Examining TIFA expression in hepatocellular carcinoma (HCC) tissues microarrays, we noted marked decreases TIFA reactivity in tumor versus control samples. In agreement, we found that HCC cell lines show reduced TIFA expression levels versus normal liver controls. Reconstituting TIFA expression in HCC cell lines promoted two independent apoptosis signaling pathways: the induction of p53 and cell cycle arrest, and the activation of caspase-8 and caspase-3. In contrast, the expression of a non-oligomerizing mutant of TIFA impacted cells minimally, and suppression of TIFA expression protected cells from apoptosis. Mice bearing TIFA overexpression hepatocellular xenografts develop smaller tumors versus TIFA mutant tumors; terminal deoxynucleotidyl transferase dUTP nick end labeling staining demonstrates increased cell apoptosis, and decreased proliferation, reflecting cell cycle arrest. Interestingly, p53 has a greater role in decreased proliferation than cell death, as it appeared dispensable for TIFA-induced cell killing. The findings demonstrate a novel suppressive role of TIFA in HCC progression via promotion of cell death independent of p53.

Exploring principles of hibernation for organ preservation

Interest in mimicking hibernating states has led investigators to explore the biological mechanisms that permit hibernating mammals to survive for months at extremely low ambient temperatures, with no food or water, and awaken from their hibernation without apparent organ injury. Hibernators have evolved mechanisms to adapt to dramatic reductions in core body temperature and metabolic rate, accompanied by prolonged periods without nutritional intake and at the same time tolerate the metabolic demands of arousal. This review discusses the inherent resilience of hibernators to kidney injury and provides a potential framework for new therapies targeting ex vivo preservation of kidneys for transplantation.

Degradation of βII-Spectrin Protein by Calpain-2 and Caspase-3 Under Neurotoxic and Traumatic Brain Injury Conditions

A major consequence of traumatic brain injury (TBI) is the rapid proteolytic degradation of structural cytoskeletal proteins. This process is largely reflected by the interruption of axonal transport as a result of extensive axonal injury leading to neuronal cell injury. Previous work from our group has described the extensive degradation of the axonally enriched cytoskeletal αII-spectrin protein which results in molecular signature breakdown products (BDPs) indicative of injury mechanisms and to specific protease activation both in vitro and in vivo. In the current study, we investigated the integrity of βII-spectrin protein and its proteolytic profile both in primary rat cerebrocortical cell culture under apoptotic, necrotic, and excitotoxic challenge and extended to in vivo rat model of experimental TBI (controlled cortical impact model). Interestingly, our results revealed that the intact 260-kDa βII-spectrin is degraded into major fragments (βII-spectrin breakdown products (βsBDPs)) of 110, 108, 85, and 80 kDa in rat brain (hippocampus and cortex) 48 h post-injury. These βsBDP profiles were further characterized and compared to an in vitro βII-spectrin fragmentation pattern of naive rat cortex lysate digested by calpain-2 and caspase-3. Results revealed that βII-spectrin was degraded into major fragments of 110/85 kDa by calpain-2 activation and 108/80 kDa by caspase-3 activation. These data strongly support the hypothesis that in vivo activation of multiple protease system induces structural protein proteolysis involving βII-spectrin proteolysis via a specific calpain and/or caspase-mediated pathway resulting in a signature, protease-specific βsBDPs that are dependent upon the type of neural injury mechanism. This work extends on previous published work that discusses the interplay spectrin family (αII-spectrin and βII-spectrin) and their susceptibility to protease proteolysis and their implication to neuronal cell death mechanisms.