Liver ischemia/reperfusion injury: processes in inflammatory networks--a review

Sodium aescinate protects renal ischemia-reperfusion and pyroptosis through AKT/NLRP3 signaling pathway

Renal ischemia-reperfusion injury (RIRI) is a common cause of acute renal injury. Studies have shown that sodium aescinate (SA) may serve as a potential therapeutic agent, although its exact mechanism remains unclear. This study first evaluated the efficacy of SA using a mouse renal ischemia-reperfusion model. Subsequently, its mechanism was elucidated through systematic bioinformatics, and finally validated through in vitro and in vivo experiments. The results demonstrated that SA has a protective effect on renal function in mice with RIRI. Bioinformatic analysis indicated that the pyroptosis pathway is significantly activated during renal ischemia-reperfusion injury, and immunohistochemistry showed that the level of renal pyroptosis is upregulated during ischemia-reperfusion injury. Administration of SA was able to reduce the expression of pyroptosis-related proteins (GSDMD, NLRP3, IL-1β) in RIRI. In vitro and in vivo experiments further confirmed that SA exerts an anti-pyroptotic effect by inhibiting the AKT/NLRP3 signaling pathway. Ultimately, SA mitigates kidney injury in IRI mice by suppressing renal failure through inhibition of the AKT/NLRP3 signaling pathway.

Diagnostic value and immune infiltration characterization of WTAP as a critical m6A regulator in liver transplantation

BACKGROUND

RNA N6-methyladenosine (m6A) regulators are essential for numerous biological processes and are implicated in various diseases. However, the comprehensive role of m6A regulators in the context of liver transplantation (LT) remains poorly understood. This study aimed to illustrate the relationship between m6A regulators and ischemia-reperfusion injury (IRI) following LT.

METHODS

Datasets were acquired from the Gene Expression Omnibus database. Differential analysis of the merged data identified the differentially expressed m6A regulators. Random forest (RF) models and nomograms were used to forecast the incidence and assess the IRI risk following LT. m6A regulators were classified into distinct subgroups using cluster analysis. The differential gene expression was validated using immunohistochemistry, immunofluorescence, and Western blotting.

RESULTS

We found significant disparities in the gene expression levels of the three m6A regulators between patients with and without LT. Wilms' tumor 1-associating protein (WTAP) expression was upregulated following LT. The RF models exhibited a high degree of accuracy in predicting IRI risk. Immune infiltration analysis showed that WTAP was an immune-associated m6A regulator that was closely associated with T and B cells. WTAP expression in the rat LT model was upregulated after 24 h of reperfusion, which was consistent with the results of the bioinformatics analysis.

CONCLUSIONS

WTAP has a high diagnostic value for IRI in LT and influences the immune status of patients. Hence, WTAP, as a significant regulator of m6A, is a potential biomarker for the detection and implementation of immunotherapy for IRI following LT.

Lentinan enhances microbiota-derived isoursodeoxycholic acid levels to alleviate hepatic ischemia-reperfusion injury in mice

Hepatic ischemia-reperfusion injury (HIRI) is an essential clinical concern caused by liver transplantation, resection, trauma, and shock that must be addressed immediately. Although the mechanisms underlying HIRI are well-documented, effective prevention and treatment strategies are still lacking. Inflammation is a central mechanism of HIRI, with macrophages playing a crucial role in initiating and amplifying the inflammatory response. Numerous plant polysaccharides exhibit substantial anti-inflammatory and hepatoprotective properties. However, the function of Lentinan (LNT) in HIRI has not been fully explored. Thus, this study aims to investigate the preventive potential of LNT in HIRI. Here, we reveal that oral administration of LNT considerably reduces hepatic inflammation and improves liver pathology in mice with HIRI by modulating gut microbiota. Specifically, LNT considerably increased microbiota-derived isoursodeoxycholic acid (IsoUDCA). Further experiments showed that IsoUDCA alleviates hepatic injury by suppressing macrophage inflammation. Mechanistically, IsoUDCA directly binds to and activates the neuron-derived clone 77 (Nur77) transcription factor, inhibiting the NF-κB signaling pathway in macrophages. Our findings shed light on the significant role of the LNT-microbiota-IsoUDCA-Nur77 axis in attenuating macrophage inflammation during HIRI, offering novel insights into potential therapeutic targets and avenues for preventing HIRI.

A Multidrug Donor Preconditioning Improves Steatotic Rat Liver Allograft Function and Recipient Survival After Transplantation

The scarcity of donors has prompted the growing utilization of steatotic livers, which are susceptible to injuries following orthotopic liver transplantation (OLT). This study aims to assess the efficacy of multidrug donor preconditioning (MDDP) in alleviating injuries of steatotic grafts following rat OLT. Lean rats were subjected to a Western-style diet with high-fat (HF) and high-fructose (HFr) for 30 days to induce steatosis. Both lean and steatotic livers were implanted into lean recipients fed with a chow diet after OLT. The HF + HFr diet effectively elevated blood triglyceride and cholesterol levels and induced fat accumulation in rat livers. Our results demonstrated a significant decrease in alanine aminotransferase levels (p = 0.003), aspartate aminotransferase levels (p = 0.021), and hepatic Suzuki scores (p = 0.045) in the steatotic rat liver allograft group following MDDP treatment on post-operation day (POD) 7. Furthermore, the survival rates of steatotic rat liver allografts with MDDP (19/21, 90.5%) were significantly higher than those in the steatotic control (12/21, 57.1%, *p = 0.019). These findings indicate that MDDP treatment improves steatotic rat liver allograft function and recipient survival following OLT.

Von Hippel-Lindau deficiency protects the liver against ischemia/reperfusion injury through the regulation of hypoxia-inducible factor 1α and 2α

BACKGROUND

Ischemia and reperfusion (I/R)-induced liver injury contributes to morbidity and mortality during hepatic surgery or liver transplantation. As a pivotal regulator of cancer and inflammation, the role of Von Hippel-Lindau (VHL) in hepatic I/R injury remains undetermined.

METHODS

We investigated the role of VHL in hepatic I/R injury by generating VHL conditional knockout (VHL-KO) mice. The downstream mechanisms of VHL were confirmed, and the role of HIF-2α in hepatic I/R injury was further investigated.

RESULTS

In this study, we discovered that VHL upregulation was associated with hepatic I/R injury in a mouse model. VHL gene knockout (VHL-KO) and overexpression (Ad-VHL) mice demonstrated that VHL aggravated liver injury, increased inflammation, and accelerated cell death in hepatic I/R injury. The VHL protein (pVHL) regulates a crucial control mechanism by targeting HIFα subunits for ubiquitin-mediated degradation. In vitro and in vivo studies demonstrated that VHL interacted with and repressed hypoxia-inducible factor 1α (HIF-1α) and hypoxia-inducible factor 2α (HIF-2α) expression during hepatic I/R injury. Notably, the inhibition of HIF-1α or 2α, as well as the concurrent inhibition of HIF-1α and 2α, abrogated the protective effect of VHL-KO. The severe stabilization of HIF-1α or 2α, as well as the simultaneous overexpression of HIF-1α and 2α, compensated for the detrimental effect of VHL.

CONCLUSIONS

Thus, we identified the VHL-HIF-1α/HIF-2α axis as an indispensable pathway that may be a novel target for mediating hepatic I/R injury.

Portal vein arterialization in 25 liver transplant recipients: A Latin American single-center experience

BACKGROUND

Portal vein arterialization (PVA) has been used in liver transplantation (LT) to maximize oxygen delivery when arterial circulation is compromised or has been used as an alternative reperfusion technique for complex portal vein thrombosis (PVT). The effect of PVA on portal perfusion and primary graft dysfunction (PGD) has not been assessed.

AIM

To examine the outcomes of patients who required PVA in correlation with their LT procedure.

METHODS

All patients receiving PVA and LT at the Fundacion Santa Fe de Bogota between 2011 and 2022 were analyzed. To account for the time-sensitive effects of graft perfusion, patients were classified into two groups: prereperfusion (pre-PVA), if the arterioportal anastomosis was performed before graft revascularization, and postreperfusion (post-PVA), if PVA was performed afterward. The pre-PVA rationale contemplated poor portal hemodynamics, severe vascular steal, or PVT. Post-PVA was considered if graft hypoperfusion became evident. Conservative interventions were attempted before PVA.

RESULTS

A total of 25 cases were identified: 15 before and 10 after graft reperfusion. Pre-PVA patients were more affected by diabetes, decompensated cirrhosis, impaired portal vein (PV) hemodynamics, and PVT. PGD was less common after pre-PVA (20.0% vs 60.0%) (P = 0.041). Those who developed PGD had a smaller increase in PV velocity (25.00 cm/s vs 73.42 cm/s) (P = 0.036) and flow (1.31 L/min vs 3.34 L/min) (P = 0.136) after arterialization. Nine patients required PVA closure (median time: 62 d). Pre-PVA and non-PGD cases had better survival rates than their counterparts (56.09 months vs 22.77 months and 54.15 months vs 31.91 months, respectively).

CONCLUSION

This is the largest report presenting PVA in LT. Results suggest that pre-PVA provides better graft perfusion than post-PVA. Graft hyperperfusion could play a protective role against PGD.

Insights into the Role of Glutathione Peroxidase 3 in Non-Neoplastic Diseases

Reactive oxygen species (ROSs) are byproducts of normal cellular metabolism and play pivotal roles in various physiological processes. Disruptions in the balance between ROS levels and the body's antioxidant defenses can lead to the development of numerous diseases. Glutathione peroxidase 3 (GPX3), a key component of the body's antioxidant system, is an oxidoreductase enzyme. GPX3 mitigates oxidative damage by catalyzing the conversion of hydrogen peroxide into water. Beyond its antioxidant function, GPX3 is vital in regulating metabolism, modulating cell growth, inducing apoptosis and facilitating signal transduction. It also serves as a significant tumor suppressor in various cancers. Recent studies have revealed aberrant expression of GPX3 in several non-neoplastic diseases, associating it with multiple pathological processes. This review synthesizes the current understanding of GPX3 expression and regulation, highlighting its extensive roles in noncancerous diseases. Additionally, this paper evaluates the potential of GPX3 as a diagnostic biomarker and explores emerging therapeutic strategies targeting this enzyme, offering potential avenues for future clinical treatment of non-neoplastic conditions.

A comprehensive analysis of m6A/m7G/m5C/m1A-related gene expression and immune infiltration in liver ischemia-reperfusion injury by integrating bioinformatics and machine learning algorithms

BACKGROUND

Liver ischemia-reperfusion injury (LIRI) is closely associated with immune infiltration, which commonly occurs after liver surgery, especially liver transplantation. Therefore, it is crucial to identify the genes responsible for LIRI and develop effective therapeutic strategies that target immune response. Methylation modifications in mRNA play various crucial roles in different diseases. This study aimed to identify potential methylation-related markers in patients with LIRI and evaluate the corresponding immune infiltration.

METHODS

Two Gene Expression Omnibus datasets containing human liver transplantation data (GSE12720 and GSE151648) were downloaded for integrated analysis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were conducted to investigate the functional enrichment of differentially expressed genes (DEGs). Differentially expressed methylation-related genes (DEMRGs) were identified by overlapping DEG sets and 65 genes related to N6-methyladenosine (m6A), 7-methylguanine (m7G), 5-methylcytosine (m5C), and N1-methyladenosine (m1A). To evaluate the relationship between DEMRGs, a protein-protein interaction (PPI) network was utilized. The core DEMRGs were screened using three machine learning algorithms: least absolute shrinkage and selection operator, random forest, and support vector machine-recursive feature elimination. After verifying the diagnostic efficacy using the receiver operating characteristic curve, we validated the expression of the core DEMRGs in clinical samples and performed relative cell biology experiments. Additionally, the immune status of LIRI was comprehensively assessed using the single sample gene set enrichment analysis algorithm. The upstream microRNA and transcription factors of the core DEMRGs were also predicted.

RESULTS

In total, 2165 upregulated and 3191 downregulated DEGs were identified, mainly enriched in LIRI-related pathways. The intersection of DEGs and methylation-related genes yielded 28 DEMRGs, showing high interaction in the PPI network. Additionally, the core DEMRGs YTHDC1, METTL3, WTAP, and NUDT3 demonstrated satisfactory diagnostic efficacy and significant differential expression and corresponding function based on cell biology experiments. Furthermore, immune infiltration analyses indicated that several immune cells correlated with all core DEMRGs in the LIRI process to varying extents.

CONCLUSIONS

We identified core DEMRGs (YTHDC1, METTL3, WTAP, and NUDT3) associated with immune infiltration in LIRI through bioinformatics and validated them experimentally. This study may provide potential methylation-related gene targets for LIRI immunotherapy.

Current Techniques and Indications for Machine Perfusion and Regional Perfusion in Deceased Donor Liver Transplantation

Since the advent of University of Wisconsin preservation solution in the 1980s, clinicians have learned to work within its confines. While affording improved outcomes, considerable limitations still exist and contribute to the large number of livers that go unused each year, often for fear they may never work. The last 10 years have seen the widespread availability of new perfusion modalities which provide an opportunity for assessing organ viability and prolonged organ storage. This review will discuss the role of in situ normothermic regional perfusion for livers donated after circulatory death. It will also describe the different modalities of ex situ perfusion, both normothermic and hypothermic, and discuss how they are thought to work and the opportunities afforded by them.

Effects of the exosomes of adipose-derived mesenchymal stem cells on apoptosis and pyroptosis of injured liver in miniature pigs

Hepatic ischemia-reperfusion injury (HIRI) is a complication of hepatectomy that affects the functional recovery of the remnant liver, which has been demonstrated to be associated with pyroptosis and apoptosis. Mesenchymal stem cells (MSCs) can protect against HIRI in rodents. Paracrine mechanisms of MSCs indicated that MSCs-derived exosomes (MSCs-exo) are one of the important components within the paracrine substances of MSCs. Moreover, miniature pigs are ideal experimental animals in comparative medicine compared to rodents. Accordingly, this study aimed to investigate whether hepatectomy combined with HIRI in miniature pigs would induce pyroptosis and whether adipose-derived MSCs (ADSCs) and their exosomes (ADSCs-exo) could positively mitigate apoptosis and pyroptosis. The study also compared the differences in the effects and the role of ADSCs and ADSCs-exo in pyroptosis and apoptosis. Results showed that severe ultrastructure damage occurred in liver tissues and systemic inflammatory response was induced after surgery, with TLR4/MyD88/NFκB/HMGB1 activation, NLRP3-ASC-Caspase1 complex generation, GSDMD revitalization, and IL-1β, IL-18, and LDH elevation in the serum. Furthermore, expression of Fas-Fasl-Caspase8 and CytC-APAF1-Caspase9 was increased in the liver. The ADSCs or ADSCs-exo intervention could inhibit the expression of these indicators and improve the ultrastructural pathological changes and systemic inflammatory response. There was no significant difference between the two intervention groups. In summary, ADSCs-exo could effectively inhibit pyroptosis and apoptosis similar to ADSCs and may be considered a safe and effective cell-free therapy to protect against liver injury.

Role of the immune system in liver transplantation and its implications for therapeutic interventions

Liver transplantation (LT) stands as the gold standard for treating end-stage liver disease and hepatocellular carcinoma, yet postoperative complications continue to impact survival rates. The liver's unique immune system, governed by a microenvironment of diverse immune cells, is disrupted during processes like ischemia-reperfusion injury posttransplantation, leading to immune imbalance, inflammation, and subsequent complications. In the posttransplantation period, immune cells within the liver collaboratively foster a tolerant environment, crucial for immune tolerance and liver regeneration. While clinical trials exploring cell therapy for LT complications exist, a comprehensive summary is lacking. This review provides an insight into the intricacies of the liver's immune microenvironment, with a specific focus on macrophages and T cells as primary immune players. Delving into the immunological dynamics at different stages of LT, we explore the disruptions after LT and subsequent immune responses. Focusing on immune cell targeting for treating liver transplant complications, we provide a comprehensive summary of ongoing clinical trials in this domain, especially cell therapies. Furthermore, we offer innovative treatment strategies that leverage the opportunities and prospects identified in the therapeutic landscape. This review seeks to advance our understanding of LT immunology and steer the development of precise therapies for postoperative complications.

Interplay Between Inflammatory-immune and Interleukin-17 Signalings Plays a Cardinal Role on Liver Ischemia-reperfusion Injury-Synergic Effect of IL-17Ab, Tacrolimus and ADMSCs on Rescuing the Liver Damage

BACKGROUND

This study tested the hypothesis that inflammatory and interleukin (IL)-17 signalings were essential for acute liver ischemia (1 h)-reperfusion (72 h) injury (IRI) that was effectively ameliorated by adipose-derived mesenchymal stem cells (ADMSCs) and tacrolimus.

METHODS

Adult-male SD rats (n = 50) were equally categorized into groups 1 (sham-operated-control), 2 (IRI), 3 [IRI + IL-17-monoclonic antibody (Ab)], 4 (IRI + tacrolimus), 5 (IRI + ADMSCs) and 6 (IRI + tacrolimus-ADMSCs) and liver was harvested at 72 h.

RESULTS

The main findings included: (1) circulatory levels: inflammatory cells, immune cells, and proinflammatory cytokines as well as liver-damage enzyme at the time point of 72 h were highest in group 2, lowest in group 1 and significantly lower in group 6 than in groups 3 to 5 (all p < 0.0001), but they did not differ among these three latter groups; (2) histopathology: the liver injury score, fibrosis, inflammatory and immune cell infiltration in liver immunity displayed an identical pattern of inflammatory cells among the groups (all p < 0.0001); and (3) protein levels: upstream and downstream inflammatory signalings, oxidative-stress, apoptotic and mitochondrial-damaged biomarkers exhibited an identical pattern of inflammatory cells among the groups (all p < 0.0001).

CONCLUSION

Our results obtained from circulatory, pathology and molecular-cellular levels delineated that acute IRI was an intricate syndrome that elicited complex upstream and downstream inflammatory and immune signalings to damage liver parenchyma that greatly suppressed by combined tacrolimus and ADMSCs therapy.

Updates on the Immune Cell Basis of Hepatic Ischemia-Reperfusion Injury

Liver ischemia-reperfusion injury (IRI) is the main cause of organ dysfunction and failure after liver surgeries including organ transplantation. The mechanism of liver IRI is complex and numerous signals are involved but cellular metabolic disturbances, oxidative stress, and inflammation are considered the major contributors to liver IRI. In addition, the activation of inflammatory signals exacerbates liver IRI by recruiting macrophages, dendritic cells, and neutrophils, and activating NK cells, NKT cells, and cytotoxic T cells. Technological advances enable us to understand the role of specific immune cells during liver IRI. Accordingly, therapeutic strategies to prevent or treat liver IRI have been proposed but no definitive and effective therapies exist yet. This review summarizes the current update on the immune cell functions and discusses therapeutic potentials in liver IRI. A better understanding of this complex and highly dynamic process may allow for the development of innovative therapeutic approaches and optimize patient outcomes.

Effect of valproic acid upon skeletal muscle subjected to prolonged tourniquet application

Background

Valproic acid (VPA), a histone deacetylase inhibitor, has shown improved outcomes when used as a pharmaceutical intervention in animal studies of hemorrhage, septic shock, and combined injuries. This study was designed to investigate the ability of VPA to mitigate ischemia-reperfusion injury produced by prolonged tourniquet application to an extremity.

Methods

The ischemia-reperfusion model in anesthetized rats was established using hemorrhage and a 3-hour tourniquet application. VPA was administered intravenously prior to tourniquet wear and removal. Ischemia-reperfusion injury was evaluated by investigating pathway signaling, immune modulation of cytokine release, remote organ injury, and skeletal muscle function during convalescence.

Results

We found that VPA sustained Protein kinase B (Akt) phosphorylation and Insulin-like growth factor signaling and modulated the systemic release of interleukin (IL)-1β, tumor necrosis factor alpha, and IL-6 after 2 hours of limb reperfusion. Additionally, VPA attenuated a loss in glomerular filtration rate at 3 days after injury. Histological and functional evaluation of extremity skeletal muscle at 3, 7, and 21 days after injury, however, demonstrated no significant differences in myocytic degeneration, necrotic formation, and maximal isometric tetanic torque.

Conclusions

Our results demonstrate that VPA sustains early prosurvival cell signaling, reduces the inflammatory response, and improves renal function in a hemorrhage with prolonged ischemia and reperfusion model. However, these do not translate into meaningful preservation in limb function when applied as a pharmaceutical augmentation to tourniquet wear.

Level of evidence

IV.

Protective effects of cordycepin pretreatment against liver ischemia/reperfusion injury in mice

INTRODUCTION

Cordycepin has been reported to exhibit hepatic protective and anti-inflammatory properties. Here, we investigated the role of cordycepin in ischemia/reperfusion (IR)-induced liver injury in a mouse model.

METHODS

Mice were pretreated with cordycepin by gavage for 3 weeks, followed by the establishment of the IR modeling. Liver injury, Suzuki's histological grading, hepatic apoptosis, and inflammatory responses were evaluated by biochemical and pathological analysis.

RESULTS

It was found that Cordycepin pretreatment at 50 mg/kg for 3 weeks attenuated IR-induced liver injury, as reflected by the significant decrease of the levels of aspartate aminotransferase, alanine transaminase, lactate dehydrogenase, and low-density lipoprotein. Cordycepin pretreatment also reduced histopathological changes, attenuated hepatocyte apoptosis, inflammatory responses in the livers of IR mice. Mechanically, toll-like receptor 4/nuclear factor kappa-B signaling in liver tissues was inhibited by Cordycepin pretreatment.

CONCLUSIONS

In conclusion, Cordycepin pretreatment protects IR-induced liver injury, which demonstrates its potential for the treatment of IR in the liver.

Inhibition of γδ-TcR or IL17a Reduces T-Cell and Neutrophil Infiltration after Ischemia/Reperfusion Injury in Mouse Liver

Neutrophil and T-cell recruitment contribute to hepatic ischemia/reperfusion injury. The initial inflammatory response is orchestrated by Kupffer cells and liver sinusoid endothelial cells. However, other cell types, including γδ-Τ cells, seem to be key mediators in further inflammatory cell recruitment and proinflammatory cytokine release, including IL17a. In this study, we used an in vivo model of partial hepatic ischemia/reperfusion injury (IRI) to investigate the role of the γδ-Τ-cell receptor (γδTcR) and the role of IL17a in the pathogenesis of liver injury. Forty C57BL6 mice were subjected to 60 min of ischemia followed by 6 h of reperfusion (RN 6339/2/2016). Pretreatment with either anti-γδΤcR antibodies or anti-IL17a antibodies resulted in a reduction in histological and biochemical markers of liver injury as well as neutrophil and T-cell infiltration, inflammatory cytokine production and the downregulation of c-Jun and NF-κΒ. Overall, neutralizing either γδTcR or IL17a seems to have a protective role in liver IRI.

Single-cell RNA-seq revealing the immune features of donor liver during liver transplantation

Immune cells, including T and B cells, are key factors in the success of liver transplantation. And the repertoire of T cells and B cells plays an essential function in mechanism of the immune response associated with organ transplantation. An exploration of their expression and distribution in donor organs could contribute to a better understanding of the altered immune microenvironment in grafts. In this study, using single-cell 5' RNA sequence and single-cell T cell receptor (TCR)/B cell receptor (BCR) repertoire sequence, we profiled immune cells and TCR/BCR repertoire in three pairs of donor livers pre- and post-transplantation. By annotating different immune cell types, we investigated the functional properties of monocytes/Kupffer cells, T cells and B cells in grafts. Bioinformatic characterization of differentially expressed genes (DEGs) between the transcriptomes of these cell subclusters were performed to explore the role of immune cells in inflammatory response or rejection. In addition, we also observed shifts in TCR/BCR repertoire after transplantation. In conclusion, we profiled the immune cell transcriptomics and TCR/BCR immune repertoire of liver grafts during transplantation, which may offer novel strategies for monitoring recipient immune function and treatment of rejection after liver transplantation.

Risk factors for acute rejection in liver transplantation and its impact on the outcomes of recipients

OBJECTIVE

To determine the risk factors for acute rejection in liver transplantation and its impact on the outcomes of the recipients.

METHODS

Clinicopathological data of 290 patients who underwent liver transplantation from January 2012 to December 2021 at our center were retrospectively evaluated. Patients were grouped into an acute rejection (AR) group and a normal (NM) group based on the confirmed histopathological diagnosis of acute rejection. Univariate and multivariate logistic regression were used to determine the risk factors for acute rejection.

RESULTS

244 patients were included in the study. Acute rejection occurred in 27 (11.1%) of the patients. Warm ischemia time (P = 0.137), cold ischemia time (P = 0.064) and chronic liver failure (P = 0.001) were potential risk factors for acute rejection. Chronic liver failure (P < 0.001, OR = 8.22, 95% CI = 2.47-27.32) was the independent risk factor. There was no significant difference in overall survival between recipients with acute rejection and those without it (P = 0.985). The 1-, 3- and 5-year overall survival in the NM group was 98.1%, 85.7% and 78.6% respectively vs 88.9%, 82.5% and 82.5% respectively in the AR group.

CONCLUSION

Acute rejection does not appear to affect the long-term survival of the recipients. Only chronic liver failure was an independent risk factor for acute rejection. Our findings further illustrate that contradictions still exist on which factors influence acute rejection in liver transplant recipients.

SUMMARY

Clinicopathological data of 290 liver transplant recipients at our center between January 2012 and December 2021 were retrospectively evaluated to determine the risk factors for acute rejection and its impact on the outcomes of the recipients. 244 patients were included in the analysis. 27 of the 244 experienced acute rejection. Propensity score matching was performed to reduce the confounding effect. Patients were assigned to an acute rejection group (n = 27) and a normal group (n = 54). Chronic liver failure (P < 0.001, OR = 8.22, 95% CI = 2.47-27.32) was the determined to be independent risk factor for acute rejection. Acute rejection did not appear to affect the long-term survival of the recipients and there was no significant difference in overall survival between the patients with acute rejection and those without it.

Apolipoprotein A-1 protected hepatic ischaemia-reperfusion injury through suppressing macrophage pyroptosis via TLR4-NF-κB pathway

BACKGROUND AND AIMS

Apolipoprotein A-1 (ApoA-1), the major apolipoprotein of high-density lipoprotein, plays anti-atherogenic role in cardiovascular diseases and exerts anti-inflammation effect in various inflammatory and infectious diseases. However, the role and mechanism of ApoA-1 in hepatic ischaemia-reperfusion (I/R) injury is unknown.

METHODS

In this study, we measured ApoA-1 expression in human liver grafts after transplantation. Mice partial hepatic I/R injury model was made in ApoA-1 knockout mice, ApoA-1 mimetic peptide D-4F treatment mice and corresponding control mice to examine the effect of ApoA-1 on liver damage, inflammation response and cell death. Primary hepatocytes and macrophages were isolated for in vitro study.

RESULTS

The results showed that ApoA-1 expression was down-regulated in human liver grafts after transplantation and mice livers subjected to hepatic I/R injury. ApoA-1 deficiency aggravated liver damage and inflammation response induced by hepatic I/R injury. Interestingly, we found that ApoA-1 deficiency increased pyroptosis instead of apoptosis during acute phase of hepatic I/R injury, which mainly occurred in macrophages rather than hepatocytes. The inhibition of pyroptosis compensated for the adverse impact of ApoA-1 deficiency. Furthermore, the up-regulated pyroptosis process was testified to be mediated by ApoA-1 through TLR4-NF-κB pathway and TLR4 inhibition significantly improved hepatic I/R injury. In addition, we confirmed that D-4F ameliorated hepatic I/R injury.

CONCLUSIONS

Our study has identified the protective role of ApoA-1 in hepatic I/R injury through inhibiting pyroptosis in macrophages via TLR4-NF-κB pathway. The effect of ApoA-1 may provide a novel therapeutic approach for hepatic I/R injury.

The application of optical technology in the diagnosis and therapy of oxidative stress-mediated hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) is defined as liver tissue damage and cell death caused by reperfusion during liver transplantation or hepatectomy. Oxidative stress is one of the important mechanisms of HIRI. Studies have shown that the incidence of HIRI is very high, however, the number of patients who can get timely and efficient treatment is small. The reason is not hard to explain that invasive ways of detection and lack of timely of diagnostic methods. Hence, a new detection method is urgently needed in clinic application. Reactive oxygen species (ROS), which are markers of oxidative stress in the liver, could be detected by optical imaging and offer timely and effective non-invasive diagnosis and monitoring. Optical imaging could become the most potential tool of diagnosis of HIRI in the future. In addition, optical technology can also be used in disease treatment. It found that optical therapy has the function of anti-oxidative stress. Consequently, it has possibility to treat HIRI caused by oxidative stress. In this review, we mainly summarized the application and prospect of optical techniques in oxidative stress-induced by HIRI.

Targeted Mitochondrial Drugs for Treatment of Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is a complex hemodynamic pathology that is a leading cause of death worldwide and occurs in many body organs. Numerous studies have shown that mitochondria play an important role in the occurrence mechanism of ischemia-reperfusion injury and that mitochondrial structural abnormalities and dysfunction lead to the disruption of the homeostasis of the whole mitochondria. At this time, mitochondria are not just sub-organelles to produce ATP but also important targets for regulating ischemia-reperfusion injury; therefore, drugs targeting mitochondria can serve as a new strategy to treat ischemia-reperfusion injury. Based on this view, in this review, we discuss potential therapeutic agents for both mitochondrial structural abnormalities and mitochondrial dysfunction, highlighting the application and prospects of targeted mitochondrial drugs in the treatment of ischemia-reperfusion injury, and try to provide new ideas for the clinical treatment of the ischemia-reperfusion injury.

LncRNA Hnf4αos exacerbates liver ischemia/reperfusion injury in mice via Hnf4αos/Hnf4α duplex-mediated PGC1α suppression

LncRNAs are involved in the pathophysiologic processes of multiple diseases, but little is known about their functions in hepatic ischemia/reperfusion injury (HIRI). As a novel lncRNA, the pathogenetic significance of hepatic nuclear factor 4 alpha, opposite strand (Hnf4αos) in hepatic I/R injury remains unclear. Here, differentially expressed Hnf4αos and Hnf4α antisense RNA 1 (Hnf4α-as1) were identified in liver tissues from mouse ischemia/reperfusion models and patients who underwent liver resection surgery. Hnf4αos deficiency in Hnf4αos-KO mice led to improved liver function, alleviated the inflammatory response and reduced cell death. Mechanistically, we found a regulatory role of Hnf4αos-KO in ROS metabolism through PGC1α upregulation. Hnf4αos also promoted the stability of Hnf4α mRNA through an RNA/RNA duplex, leading to the transcriptional activation of miR-23a and miR-23a depletion was required for PGC1α function in hepatoprotective effects on HIRI. Together, our findings reveal that Hnf4αos elevation in HIRI leads to severe liver damage via Hnf4αos/Hnf4α/miR-23a axis-mediated PGC1α inhibition.

Neuroprotective Effects of Dexpanthenol on Rabbit Spinal Cord Ischemia/Reperfusion Injury Model

OBJECTIVE

Dexpanthenol (DXP) reportedly protects tissues against oxidative damage in various inflammation models. This study aimed to evaluate its effects on oxidative stress, inflammation, apoptosis, and neurological recovery in an experimental rabbit spinal cord ischemia/reperfusion injury (SCIRI) model.

METHODS

Rabbits were randomized into 5 groups of 8 animals each: group 1 (control), group 2 (ischemia), group 3 (vehicle), group 4 (methylprednisolone, 30 mg/kg), and group 5 (DXP, 500 mg/kg). The control group underwent laparotomy only, whereas other groups were subjected to spinal cord ischemia by aortic occlusion (just caudal to the 2 renal arteries) for 20 min. After 24 h, a modified Tarlov scale was employed to record neurological examination results. Malondialdehyde and caspase-3 levels and catalase and myeloperoxidase activities were analyzed in tissue and serum samples. Xanthine oxidase activity was measured in the serum. Histopathological and ultrastructural evaluations were also performed in the spinal cord.

RESULTS

After SCIRI, serum and tissue malondialdehyde and caspase-3 levels and myeloperoxidase and serum xanthine oxidase activities were increased (P < 0.05-0.001). However, serum and tissue catalase activity decreased significantly (P < 0.001). DXP treatment was associated with lower malondialdehyde and caspase-3 levels and reduced myeloperoxidase and xanthine oxidase activities but increased catalase activity (P < 0.05-0.001). Furthermore, DXP was associated with better histopathological, ultrastructural, and neurological outcome scores.

CONCLUSIONS

This study was the first to evaluate antioxidant, anti-inflammatory, antiapoptotic, and neuroprotective effects of DXP on SCIRI. Further experimental and clinical investigations are warranted to confirm that DXP can be administered to treat SCIRI.

Resveratrol therapy improves liver function via estrogen-receptors after hemorrhagic shock in rats

Background

Resveratrol may improve organ dysfunction after experimental hemorrhagic or septic shock, and some of these effects appear to be mediated by estrogen receptors. However, the influence of resveratrol on liver function and hepatic microcirculation after hemorrhagic shock is unknown, and a presumed mediation via estrogen receptors has not been investigated in this context.

Methods

Male Sprague-Dawley rats (200-300g, n = 14/group) underwent hemorrhagic shock for 90 min (MAP 35±5 mmHg) and were resuscitated with shed blood and Ringer’s solution. Animals were treated intravenously with vehicle (1% EtOH), resveratrol (0.2 mg/kg), the unselective estrogen receptor antagonist ICI 182,780 (0.05 mg/kg) or resveratrol + ICI 182,780 prior to retransfusion. Sham-operated animals did not undergo hemorrhage but were treated likewise. After 2 hours of reperfusion, liver function was assessed either by plasma disappearance rate of indocyanine green (PDR_ICG) or evaluation of hepatic perfusion and hepatic integrity by intravital microscopy, serum enzyme as well as cytokine levels.

Results

Compared to vehicle controls, administration of resveratrol significantly improved PDR_ICG, hepatic perfusion index and hepatic integrity after hemorrhagic shock. The co-administration of ICI 182,780 completely abolished the protective effect only with regard to liver function.

Conclusions

This study shows that resveratrol may improve liver function and hepatocellular integrity after hemorrhagic shock in rats; estrogen receptors mediate these effects at least partially.

Inhibition of macrophage migration inhibitory factor (MIF) suppresses apoptosis signal-regulating kinase 1 to protect against liver ischemia/reperfusion injury

Background: Hepatic ischemia–reperfusion (I/R) injury is a major complication leading to surgical failures in liver resection, transplantation, and hemorrhagic shock. The role of cytokine macrophage migration inhibitory factor (MIF) in hepatic I/R injury is unclear.

Methods: We examined changes of MIF expression in mice after hepatic I/R surgery and hepatocytes challenged with hypoxia–reoxygenation (H/R) insult. Subsequently, MIF global knock-out mice and mice with adeno-associated-virus (AAV)-delivered MIF overexpression were subjected to hepatic I/R injury. Hepatic histology, the inflammatory response, apoptosis and oxidative stress were monitored to assess liver damage. The molecular mechanisms of MIF function were explored in vivo and in vitro.

Results: MIF was significantly upregulated in the serum whereas decreased in liver tissues of mice after hepatic I/R injury. MIF knock-out effectively attenuated I/R -induced liver inflammation, apoptosis and oxidative stress in vivo and in vitro, whereas MIF overexpression significantly aggravated liver injury. Via RNA-seq analysis, we found a significant decreased trend of MAPK pathway in MIF knock-out mice subjected hepatic I/R surgery. Using the apoptosis signal-regulating kinase 1 (ASK1) inhibitor NQDI-1 we determined that, mechanistically, the protective effect of MIF deficiency on hepatic I/R injury was dependent on the suppressing of the ASK1-JNK/P38 signaling pathway. Moreover, we found MIF inhibitor ISO-1 alleviate hepatic I/R injury in mice.

Conclusion: Our results confirm that MIF deficiency suppresses the ASK1-JNK/P38 pathway and protects the liver from I/R -induced injury. Our findings suggest MIF as a novel biomarker and therapeutic target for the diagnosis and treatment of hepatic I/R injury.

Mitochondria and Cancer Recurrence after Liver Transplantation-What Is the Benefit of Machine Perfusion?

Tumor recurrence after liver transplantation has been linked to multiple factors, including the recipient's tumor burden, donor factors, and ischemia-reperfusion injury (IRI). The increasing number of livers accepted from extended criteria donors has forced the transplant community to push the development of dynamic perfusion strategies. The reason behind this progress is the urgent need to reduce the clinical consequences of IRI. Two concepts appear most beneficial and include either the avoidance of ischemia, e.g., the replacement of cold storage by machine perfusion, or secondly, an endischemic organ improvement through perfusion in the recipient center prior to implantation. While several concepts, including normothermic perfusion, were found to reduce recipient transaminase levels and early allograft dysfunction, hypothermic oxygenated perfusion also reduced IRI-associated post-transplant complications and costs. With the impact on mitochondrial injury and subsequent less IRI-inflammation, this endischemic perfusion was also found to reduce the recurrence of hepatocellular carcinoma after liver transplantation. Firstly, this article highlights the contributing factors to tumor recurrence, including the surgical and medical tissue trauma and underlying mechanisms of IRI-associated inflammation. Secondly, it focuses on the role of mitochondria and associated interventions to reduce cancer recurrence. Finally, the role of machine perfusion technology as a delivery tool and as an individual treatment is discussed together with the currently available clinical studies.

SIRT5 alleviates hepatic ischemia and reperfusion injury by diminishing oxidative stress and inflammation via elevating SOD1 and IDH2 expression

Hepatic ischemia/reperfusion (I/R) injury, a common and unavoidable pathophysiological process during liver transplantation or resection operation, may impede postoperative liver function recovery, and its mechanism and targeted therapy remain largely unknown. SIRT5 is a well-known deacetylase and participates in the regulation of many physiological and pathological processes, including I/R. The role of SIRT5 in I/R is controversial or tissue-specific, restricting I/R progression in the heart while deteriorating injury in the kidney and brain, while its effect on hepatic I/R remains unclear. In this study, we investigated the function of SIRT5 in hepatic I/R using AAV8 and lentivirus to overexpress SIRT5 in vivo and in vitro. The data showed that SIRT5 overexpression alleviated liver I/R injury in mice and hypoxia/reoxygenation treated AML-12 cells. Moreover, gain- and loss-of-function of SIRT5, SOD1 and IDH2 experiments in AML-12 were performed. Our results demonstrated that SOD1 and IDH2 knockdown abolished the effect of SIRT5 on restraining oxidative stress and inflammation. Therefore, our work revealed that SIRT5 may alleviates hepatic I/R injury by diminishing oxidative stress and inflammation via up-regulating the SOD1 and IDH2 expression, which enriches the theory and therapeutic strategies of hepatic I/R injury.

Luteolin Pretreatment Attenuates Hepatic Ischemia-Reperfusion Injury in Mice by Inhibiting Inflammation, Autophagy, and Apoptosis via the ERK/PPARα Pathway

Hepatic ischemia-reperfusion (IR) injury is a clinically significant process that frequently occurs in liver transplantation, partial hepatectomy, and hemorrhagic shock. The aim of this study was to explore the effectiveness of luteolin in hepatic IR injury and the underlying mechanism. BALB/c mice were randomly divided into six groups, including normal controls (NC), luteolin (50 mg/kg), sham procedure, IR+25 mg/kg luteolin, and IR+50 mg/kg luteolin group. Serum and tissue samples were collected at 6 and 24 h after reperfusion to assay liver enzymes, inflammatory factors, expression of proteins associated with apoptosis and autophagy, and factors associated with the extracellular signal-regulated kinase/peroxisome proliferator-activated receptor alpha (ERK/PPARα) pathway. Luteolin preconditioning decreased hepatocyte injury caused by ischemia-reperfusion, downregulated inflammatory factors, and inhibited apoptosis and autophagy. Luteolin also inhibited ERK phosphorylation and activated PPARα.

Role of hepatic stellate cells in liver ischemia-reperfusion injury

Liver ischemia-reperfusion injury (IRI) is a major complication of liver trauma, resection, and transplantation. IRI may lead to liver dysfunction and failure, but effective approach to address it is still lacking. To better understand the cellular and molecular mechanisms of liver IRI, functional roles of numerous cell types, including hepatocytes, Kupffer cells, neutrophils, and sinusoidal endothelial cells, have been intensively studied. In contrast, hepatic stellate cells (HSCs), which are well recognized by their essential functions in facilitating liver protection and repair, have gained less attention in their role in IRI. This review provides a comprehensive summary of the effects of HSCs on the injury stage of liver IRI and their associated molecular mechanisms. In addition, we discuss the regulation of liver repair and regeneration after IRI by HSCs. Finally, we highlight unanswered questions and future avenues of research regarding contributions of HSCs to IRI in the liver.

Study on the Mechanism of Mesaconitine-Induced Hepatotoxicity in Rats Based on Metabonomics and Toxicology Network

Mesaconitine (MA), one of the main diterpenoid alkaloids in Aconitum, has a variety of pharmacological effects, such as analgesia, anti-inflammation and relaxation of rat aorta. However, MA is a highly toxic ingredient. At present, studies on its toxicity are mainly focused on the heart and central nervous system, and there are few reports on the hepatotoxic mechanism of MA. Therefore, we evaluated the effects of MA administration on liver. SD rats were randomly divided into a normal saline (NS) group, a low-dose MA group (0.8 mg/kg/day) and a high-dose MA group (1.2 mg/kg/day). After 6 days of administration, the toxicity of MA on the liver was observed. Metabolomic and network toxicology methods were combined to explore the effect of MA on the liver of SD rats and the mechanism of hepatotoxicity in this study. Through metabonomics study, the differential metabolites of MA, such as L-phenylalanine, retinyl ester, L-proline and 5-hydroxyindole acetaldehyde, were obtained, which involved amino acid metabolism, vitamin metabolism, glucose metabolism and lipid metabolism. Based on network toxicological analysis, MA can affect HIF-1 signal pathway, MAPK signal pathway, PI3K-Akt signal pathway and FoxO signal pathway by regulating ALB, AKT1, CASP3, IL2 and other targets. Western blot results showed that protein expression of HMOX1, IL2 and caspase-3 in liver significantly increased after MA administration (p < 0.05). Combined with the results of metabonomics and network toxicology, it is suggested that MA may induce hepatotoxicity by activating oxidative stress, initiating inflammatory reaction and inducing apoptosis.

Inflammatory response to the ischaemia-reperfusion insult in the liver after major tissue trauma

BACKGROUND

Polytrauma is often accompanied by ischaemia-reperfusion injury to tissues and organs, and the resulting series of immune inflammatory reactions are a major cause of death in patients. The liver is one of the largest organs in the body, a characteristic that makes it the most vulnerable organ after multiple injuries. In addition, the liver is an important digestive organ that secretes a variety of inflammatory mediators involved in local as well as systemic immune inflammatory responses. Therefore, this review considers the main features of post-traumatic liver injury, focusing on the immuno-pathophysiological changes, the interactions between liver organs, and the principles of treatment deduced.

METHODS

We focus on the local as well as systemic immune response involving the liver after multiple injuries, with emphasis on the pathophysiological mechanisms.

RESULTS

An overview of the mechanisms underlying the pathophysiology of local as well as systemic immune responses involving the liver after multiple injuries, the latest research findings, and the current mainstream therapeutic approaches.

CONCLUSION

Cross-reactivity between various organs and cascade amplification effects are among the main causes of systemic immune inflammatory responses after multiple injuries. For the time being, the pathophysiological mechanisms underlying this interaction remain unclear. Future work will continue to focus on identifying potential signalling pathways as well as target genes and intervening at the right time points to prevent more severe immune inflammatory responses and promote better and faster recovery of the patient.

Targeting the Hepatic Microenvironment to Improve Ischemia/Reperfusion Injury: New Insights into the Immune and Metabolic Compartments

Hepatic ischemia/reperfusion injury (IRI) is mainly characterized by high activation of immune inflammatory responses and metabolic responses. Understanding the molecular and metabolic mechanisms underlying development of hepatic IRI is critical for developing effective therapies for hepatic IRI. Recent advances in research have improved our understanding of the pathogenesis of IRI. During IRI, hepatocyte injury and inflammatory responses are mediated by crosstalk between the immune cells and metabolic components. This crosstalk can be targeted to treat or reverse hepatic IRI. Thus, a deep understanding of hepatic microenvironment, especially the immune and metabolic responses, can reveal new therapeutic opportunities for hepatic IRI. In this review, we describe important cells in the liver microenvironment (especially non-parenchymal cells) that regulate immune inflammatory responses. The role of metabolic components in the diagnosis and prevention of hepatic IRI are discussed. Furthermore, recent updated therapeutic strategies based on the hepatic microenvironment, including immune cells and metabolic components, are highlighted.

Precision Navigation of Hepatic Ischemia-Reperfusion Injury Guided by Lysosomal Viscosity-Activatable NIR-II Fluorescence

Hepatic ischemia-reperfusion injury (HIRI) is responsible for postoperative liver dysfunction and liver failure. Precise and rapid navigation of HIRI lesions is critical for early warning and timely development of pretreatment plans. Available methods for assaying liver injury fail to provide the exact location of lesions in real time intraoperatively. HIRI is intimately associated with oxidative stress which impairs lysosomal degradative function, leading to significant changes in lysosomal viscosity. Therefore, lysosomal viscosity is a potential biomarker for the precise targeting of HIRI. Hence, we developed a viscosity-activatable second near-infrared window fluorescent probe (NP-V) for the detection of lysosomal viscosity in hepatocytes and mice during HIRI. A reactive oxygen species-malondialdehyde-cathepsin B signaling pathway during HIRI was established. We further conducted high signal-to-background ratio NIR-II fluorescence imaging of HIRI mice. The contour and boundary of liver lesions were delineated, and as such the precise intraoperative resection of the lesion area was implemented. This research demonstrates the potential of NP-V as a dual-functional probe for the elucidation of HIRI pathogenesis and the direct navigation of HIRI lesions in clinical applications.

E3 ubiquitin ligase ring finger protein 5 protects against hepatic ischemia reperfusion injury by mediating phosphoglycerate mutase family member 5 ubiquitination

BACKGROUND AND AIMS

Hepatic ischemia-reperfusion (HIR) injury, a common clinical complication of liver transplantation and resection, affects patient prognosis. Ring finger protein 5 (RNF5) is an E3 ubiquitin ligase that plays important roles in endoplasmic reticulum stress, unfolded protein reactions, and inflammatory responses; however, its role in HIR is unclear.

APPROACH AND RESULTS

RNF5 expression was significantly down-regulated during HIR in mice and hepatocytes. Subsequently, RNF5 knockdown and overexpression of cell lines were subjected to hypoxia-reoxygenation challenge. Results showed that RNF5 knockdown significantly increased hepatocyte inflammation and apoptosis, whereas RNF5 overexpression had the opposite effect. Furthermore, hepatocyte-specific RNF5 knockout and transgenic mice were established and subjected to HIR, and RNF5 deficiency markedly aggravated liver damage and cell apoptosis and activated hepatic inflammatory responses, whereas hepatic RNF5 transgenic mice had the opposite effect compared with RNF5 knockout mice. Mechanistically, RNF5 interacted with phosphoglycerate mutase family member 5 (PGAM5) and mediated the degradation of PGAM5 through K48-linked ubiquitination, thereby inhibiting the activation of apoptosis-regulating kinase 1 (ASK1) and its downstream c-Jun N-terminal kinase (JNK)/p38. This eventually suppresses the inflammatory response and cell apoptosis in HIR.

CONCLUSIONS

We revealed that RNF5 protected against HIR through its interaction with PGAM5 to inhibit the activation of ASK1 and the downstream JNK/p38 signaling cascade. Our findings indicate that the RNF5-PGAM5 axis may be a promising therapeutic target for HIR.

Prevalence of fatty liver disease after liver transplantation and risk factors for recipients and donors

INTRODUCTION AND OBJECTIVES

Fatty liver disease (FLD) may develop in liver transplant recipients. We investigated the recipient and donor risk factors for FLD development after liver transplantation (LT).

METHODS

A total of 108 liver transplant recipients (54 men [50.0%]; median age, 52 [20-68] years) treated from 2011-2020 was enrolled. Three recipients died at < 3 months as a result of infection or blood flow impairment, and were excluded from the long-term FLD study. On evaluation of 88 prospective living donors, fatty liver was observed in 21. The prevalence and risk factors for FLD and survival were evaluated.

RESULTS

After LT, 28 of 105 recipients (26.7%) developed FLD. FLD was more common in patients with a high body mass index (BMI) and dyslipidemia (both p < 0.01), primary nonalcoholic steatohepatitis (p = 0.02), after living-donor LT (p = 0.03) and everolimus (EVL) use (p = 0.08). Factors predictive of FLD included EVL use and a high BMI (hazard ratios = 3.00 and 1.34; p = 0.05 and p < 0.01, respectively). Sixteen donors lost 6.5 kg (range: 2.0-16.0 kg) of body weight prior to LT. However, there were no cases of primary non-function, which did not affect the FLD prevalence. Development of FLD did not have a negative impact on LT outcome; the 5-year survival rate was 92.6%.

CONCLUSIONS

Recipient factors were more important than donor factors for FLD onset after LT.

Intraoperative High Fraction of Inspiratory Oxygen is Independently Associated with Worse Outcome After Living-Donor Liver Transplantation: A Retrospective Study

Background

Ischemia and reperfusion injury is an important factor that determines graft function after liver transplantation, and oxygen plays a crucial role in this process. However, the relationship between the intraoperative high fraction of inspiratory oxygen (FiO₂) and living-donor-liver-transplantation (LDLT) outcome remains unclear.

Patients and Methods

A total of 199 primary adult-to-adult LDLT cases in Kyoto University Hospital between January 2010 and December 2017 were enrolled in this study. The intraoperative FiO₂ was averaged using the total amount of intraoperative oxygen and air and defined as the calculated FiO₂ (cFiO₂). The cutoff value of cFiO₂ was set at 0.5.

Results

Between the cFiO₂ <0.5 (n = 156) and ≥0.5 group (n = 43), preoperative recipients’ background, donor factors, and intraoperative parameters were almost comparable. Postoperatively, the cFiO₂ ≥0.5 group showed a higher early allograft dysfunction (EAD) rate (P = 0.049) and worse overall graft survival (P = 0.036) than the cFiO₂ <0.5 group. Although the cFiO₂ ≥0.5 was not an independent risk factor for EAD in multivariable analysis (OR 2.038, 95%CI 0.992–4.186, P = 0.053), it was an independent risk factor for overall graft survival after LDLT (HR 1.897, 95%CI 1.007–3.432, P = 0.048).

Conclusion

The results of this study suggest that intraoperative high FiO₂ may be associated with worse graft survival after LDLT. Avoiding higher intraoperative FiO₂ may be beneficial for LDLT recipients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00268-022-06544-7.

Kaempferol From Penthorum chinense Pursh Attenuates Hepatic Ischemia/Reperfusion Injury by Suppressing Oxidative Stress and Inflammation Through Activation of the Nrf2/HO-1 Signaling Pathway

The purpose of this study is to investigate the protective effect of kaempferol (KAE), the main active monomer from Penthorum chinense Pursh, on hepatic ischemia/reperfusion injury (HI/RI) and its specific mechanism. HI/RI is a common complication closely related to the prognosis of liver surgery, and effective prevention and treatment methods are still unavailable. Ischemia/reperfusion (I/R) injury is caused by tissue damage during ischemia and sustained oxidative stress and inflammation during reperfusion. Penthorum chinense Pursh is a traditional Chinese medicine widely used to treat liver disease since ancient times. Kaempferol (KAE), a highly purified flavonoid active monomer isolated and extracted from Penthorum chinense Pursh, was investigated for its protective effect on HI/RI. Our study indicates that KAE pretreatment alleviated I/R-induced transaminase elevation and pathological changes. Further analysis revealed that KAE pretreatment attenuates I/R-induced oxidative stress (as measured by the content of MDA, SOD and GSH) in vivo and reduces hypoxia/reoxygenation (H/R) -induced reactive oxygen species (ROS) generation in vitro. Meanwhile, KAE inhibits activation of NF-κB/p65 and reduces the release of pro-inflammatory factors (TNF-α and IL-6) to protect the liver from I/R-induced inflammation. Nuclear erythroid 2-related factor 2 (Nrf2) is a crucial cytoprotection regulator because it induces anti-inflammatory, antioxidant, and cytoprotective genes. Therefore, we analyzed the protein levels of Nrf2 and its downstream heme oxygenase-1 (HO-1) in the liver of mice and hepatocytes of humankind, respectively, and discovered that KAE pretreatment activates the Nrf2/HO-1 signaling pathway. In summary, this study confirmed the hepatoprotective effect of KAE on HI/RI, which inhibits oxidative stress and inflammation by activating the Nrf2/HO-1 signaling pathway.

Attenuating ischemia-reperfusion injury with polymerized albumin

Ischemia-reperfusion injury increased vascular permeability, resulting in fluid extravasation from the intravascular compartment into the tissue space. Fluid and small protein extravasation lead to increased interstitial fluid pressure and capillary collapse, impairing capillary exchange. Polymerized human serum albumin (PolyHSA) has an increased molecular weight (MW) compared with unpolymerized human serum albumin (HSA) and can improve intravascular fluid retention and recovery from ischemia-reperfusion injury. To test the hypothesis that polymerization of HSA can improve recovery from ischemia-reperfusion injury, we studied how exchange transfusion of 20% of the blood volume with HSA or PolyHSA immediately before reperfusion can affect local ischemic tissue microhemodynamics, vascular integrity, and tissue viability in a hamster dorsal window chamber model. Microvascular flow and functional capillary density were maintained in animals exchanged with PolyHSA compared with HSA. Likewise, exchange transfusion with PolyHSA preserved vascular permeability measured with extravasation of fluorescently labeled dextran. The intravascular retention time of the exchanged PolyHSA was significantly longer compared with the intravascular retention time of HSA. Lastly, the viability of tissue subjected to ischemia-reperfusion injury increased in animals exchanged with PolyHSA compared with HSA. Therefore maintenance of microvascular perfusion, improvement in vascular integrity, and reduction in tissue damage resulting from reperfusion with PolyHSA suggest that PolyHSA is a promising fluid therapy to improve outcomes of ischemia-reperfusion injury.NEW & NOTEWORTHY Polymerized human serum albumin reduced reperfusion injury and preservers microvascular hemodynamics. Polymerized human serum albumin reduces fluid extravasation and prevents fluid extravasation. Consequently, the tissue viability of ischemic tissue is preserved by polymerized human serum.

Human Dermcidin Protects Mice Against Hepatic Ischemia-Reperfusion-Induced Local and Remote Inflammatory Injury

Background

Hepatic ischemia and reperfusion (I/R) injury is commonly associated with surgical liver resection or transplantation, and represents a major cause of liver damage and graft failure. Currently, there are no effective therapies to prevent hepatic I/R injury other than ischemic preconditioning and some preventative strategies. Previously, we have revealed the anti-inflammatory activity of a sweat gland-derived peptide, dermcidin (DCD), in macrophage/monocyte cultures. Here, we sought to explore its therapeutic potential and protective mechanisms in a murine model of hepatic I/R.

Methods

Male C57BL/6 mice were subjected to hepatic ischemia by clamping the hepatic artery and portal vein for 60 min, which was then removed to initiate reperfusion. At the beginning of reperfusion, 0.2 ml saline control or solution of DCD (0.5 mg/kg BW) or DCD-C34S analog (0.25 or 0.5 mg/kg BW) containing a Cys (C)→Ser (S) substitution at residue 34 was injected via the internal jugular vein. For survival experiments, mice were subjected to additional resection to remove non-ischemic liver lobes, and animal survival was monitored for 10 days. For mechanistic studies, blood and tissue samples were collected at 24 h after the onset of reperfusion, and subjected to measurements of various markers of inflammation and tissue injury by real-time RT-PCR, immunoassays, and histological analysis.

Results

Recombinant DCD or DCD-C34S analog conferred a significant protection against lethal hepatic I/R when given intravenously at the beginning of reperfusion. This protection was associated with a significant reduction in hepatic injury, neutrophilic CXC chemokine (Mip-2) expression, neutrophil infiltration, and associated inflammation. Furthermore, the administration of DCD also resulted in a significant attenuation of remote lung inflammatory injury. Mechanistically, DCD interacted with epidermal growth factor receptor (EGFR), a key regulator of liver inflammation, and significantly inhibited hepatic I/R-induced phosphorylation of EGFR as well as a downstream signaling molecule, protein kinase B (AKT). The suppression of EGFR expression by transducing Egfr-specific shRNA plasmid into macrophages abrogated the DCD-mediated inhibition of nitric oxide (NO) production induced by a damage-associated molecular pattern (DAMP), cold-inducible RNA-binding protein, CIRP.

Conclusions

The present study suggests that human DCD and its analog may be developed as novel therapeutics to attenuate hepatic I/R-induced inflammatory injury possibly by impairing EGFR signaling.

Pro-inflammatory cytokines/chemokines, TNF-α, IL-6 and MCP-1, as biomarkers for the nephro- and pneumoprotective effect of silibinin after hepatic ischemia/reperfusion: confirmation by immunihistochemistry and qRT-PCR

The present study investigated the potential nephro- and pneumoprotective effect of silibinin (Si) after hepatic ischemia-reperfusion (I/R) injury, by measuring pro-inflammatory factors. Sixty-three rats were randomly assigned into three groups, as follows: (a) the sham group (n=7 rats), subjected to opening and closing the abdomen; (b) the control group (n = 28 rats), subjected to 45-min hepatic ischemia followed by reperfusion; and (c) the silibinin group (n=28), subjected to 45-min hepatic ischemia followed by intravenous administration of lyophilized SLB-HP-β-CD before reperfusion. Control and silibinin groups were further subdivided into time-point groups, according to the duration of reperfusion. TNF-α, IL-6 and MCP-1 expressions were determined immunihistochemically and by qrT-PCR at each time-point. Kidney TNF-α expression was significantly lower at 180 and 240 min, while lung TNF-α expression was significantly lower at 240 min. Comparison between the control and Si group at the same time-points, showed very strong evidence of difference at 240 min, with the levels of IL-6 shifting towards lower values in the Si group. Finally, we found a high MCP-1 expression after 120 min. We conclude that hepatic I/R injury remotely increases proinflammatory mediators in the kidney and lung, whereas silibinin shows a time-dependent nephro- and pneumoprotective effect.

Intravenous immunoglobulin is effective in alleviating hepatic ischemia-reperfusion injury: a rat model study

BACKGROUND

Hepatic ischemia-reperfusion injury (I/R) is an important factor affecting the prognosis of patients undergoing liver surgery. This study aimed to explore the value of intravenous immunoglobulin (IVIG) in hepatic I/R and its mechanism in a rat model.

MATERIALS AND METHODS

Forty eight adult male Sprague-Dawley (SD) rats were divided into six groups randomly: (1-2) treated with normal saline (NS) without ischemia or reperfusion; (3-4) treated with NS + 30 min ischemia; (5-6) treated with IVIG + 30 min ischemia. Rats of group 1/3/5 were euthanized at 12 h after operation (sham + NS + 12 h, I/R + NS + 12 h, I/R + IVIG + 12 h group) while group 2/4/6 were euthanized at 24 h (sham + NS + 24 h, I/R + NS + 24 h, I/R + IVIG + 24 h group). Interleukin 10 (IL-10), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) were quantified as well as serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Hepatic pathological changes were observed while nuclear factor kappa B p65 (NF-κB p65), Inhibitory Subunit of NF Kappa B Alpha (IKB-alpha) and cleaved caspase-3 were detected.

CONCLUSION

ALT, AST, IL-6, TNF-alpha, NF-κB p65 and cleaved caspase-3 were increased by I/R whereas IL-10 and IKB-alpha were decreased. However, IVIG pretreatment reduced ALT, AST, IL-6, TNF-alpha, NF-κB p65 and cleaved caspase-3, but increased IL-10 and IKB-alpha. IVIG treatment attenuates the infiltration of inflammatory cell and cell apoptosis which were observed in I/R groups. IVIG may alleviate hepatic I/R in rats by inhibiting the classical NF-κB signaling pathway, reducing IL-6, TNF-alpha, promoting IL-10, and inhibiting cell apoptosis.

A H2O2-activatable nanoprobe for diagnosing interstitial cystitis and liver ischemia-reperfusion injury via multispectral optoacoustic tomography and NIR-II fluorescent imaging

Developing high-quality NIR-II fluorophores (emission in 1000-1700 nm) for in vivo imaging is of great significance. Benzothiadiazole-core fluorophores are an important class of NIR-II dyes, yet ongoing limitations such as aggregation-caused quenching in aqueous milieu and non-activatable response are still major obstacles for their biological applications. Here, we devise an activatable nanoprobe to address these limitations. A molecular probe named BTPE-NO2 is synthesized by linking a benzothiadiazole core with two tetraphenylene groups serving as hydrophobic molecular rotors, followed by incorporating two nitrophenyloxoacetamide units at both ends of the core as recognition moieties and fluorescence quenchers. An FDA-approved amphiphilic polymer Pluronic F127 is then employed to encapsulate the molecular BTPE-NO2 to render the nanoprobe BTPE-NO2@F127. The pathological levels of H2O2 in the disease sites cleave the nitrophenyloxoacetamide groups and activate the probe, thereby generating strong fluorescent emission (950~1200 nm) and ultrasound signal for multi-mode imaging of inflammatory diseases. The nanoprobe can therefore function as a robust tool for detecting and imaging the disease sites with NIR-II fluorescent and multispectral optoacoustic tomography (MSOT) imaging. Moreover, the three-dimensional MSOT images can be obtained for visualizing and locating the disease foci.

Mitochondrial respiratory chain and Krebs cycle enzyme function in human donor livers subjected to end-ischaemic hypothermic machine perfusion

INTRODUCTION

Marginal human donor livers are highly susceptible to ischaemia reperfusion injury and mitochondrial dysfunction. Oxygenation during hypothermic machine perfusion (HMP) was proposed to protect the mitochondria but the mechanism is unclear. Additionally, the distribution and uptake of perfusate oxygen during HMP are unknown. This study aimed to examine the feasibility of mitochondrial function analysis during end-ischaemic HMP, assess potential mitochondrial viability biomarkers, and record oxygenation kinetics.

METHODS

This was a randomised pilot study using human livers retrieved for transplant but not utilised. Livers (n = 38) were randomised at stage 1 into static cold storage (n = 6), hepatic artery HMP (n = 7), and non-oxygen supplemented portal vein HMP (n = 7) and at stage 2 into oxygen supplemented and non-oxygen supplemented portal vein HMP (n = 11 and 7, respectively). Mitochondrial parameters were compared between the groups and between low- and high-risk marginal livers based on donor history, organ steatosis and preservation period. The oxygen delivery efficiency was assessed in additional 6 livers using real-time measurements of perfusate and parenchymal oxygen.

RESULTS

The change in mitochondrial respiratory chain (complex I, II, III, IV) and Krebs cycle enzyme activity (aconitase, citrate synthase) before and after 4-hour preservation was not different between groups in both study stages (p > 0.05). Low-risk livers that could have been used clinically (n = 8) had lower complex II-III activities after 4-hour perfusion, compared with high-risk livers (73 nmol/mg/min vs. 113 nmol/mg/min, p = 0.01). Parenchymal pO2 was consistently lower than perfusate pO2 (p ≤ 0.001), stabilised in 28 minutes compared to 3 minutes in perfusate (p = 0.003), and decreased faster upon oxygen cessation (75 vs. 36 minutes, p = 0.003).

CONCLUSIONS

Actively oxygenated and air-equilibrated end-ischaemic HMP did not induce oxidative damage of aconitase, and respiratory chain complexes remained intact. Mitochondria likely respond to variable perfusate oxygen levels by adapting their respiratory function during end-ischaemic HMP. Complex II-III activities should be further investigated as viability biomarkers.

Bracteanolide A abrogates oxidative stress-induced cellular damage and protects against hepatic ischemia and reperfusion injury in rats

Liver diseases, including viral hepatitis, liver cirrhosis, and liver cancer, mostly remain silent until the late stages and pose a continuing threat to millions of people worldwide. Liver transplantation is the most appropriate solution in the case of liver failure, but it is associated with hepatic ischemia and reperfusion (I/R) injury which severely reduces the prognosis of the patients. In order to ameliorate I/R injury, we investigated the potential of bracteanolide A, from the herb Tradescantia albiflora Kunth in protecting the liver from I/R injury. We first determined the protective effect of bracteanolide A against oxidative stress and DNA damage using HepG2 hepatocyte cell line and then assessed the levels of inflammatory cytokines and antioxidant proteins in response to hepatic insult using an animal model of hepatic I/R injury. The results showed bracteanolide A greatly enhanced cell survival and decreased reactive oxygen species (ROS) production under H2O2 induction. It also upregulated the expression of nuclear factor (erythroid-derived 2)-like2 (Nrf2) and its downstream cytoprotective proteins NAD(P)H quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1). Bracteanolide A effectively reduced the severity of liver lesions in I/R-injured rats revealed by histological analysis and significantly decreased the levels of alanine transaminase (ALT), aspartate transaminase (AST), cyclooxygenase-2, and inflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Bracteanolide A preconditioning effectively protected the liver from I/R damage in the animal model, and this easily applied procedure may provide a new means to ameliorate hepatic I/R injury during liver surgeries.

Hepatic interferon regulatory factor 8 expression mediates liver ischemia/reperfusion injury in mice

Hepatic ischemia/reperfusion (I/R) injury is an inevitable complication of hepatic surgery occasioned by liver transplantation and resection. The progression from liver ischemia to reperfusion injury is accompanied by abnormal metabolism, Kupffer cell activation, neutrophil recruitment and the release of cytokines. Activation of several interferon regulatory factors (IRFs) has been reported to either enhance or restrict I/R progression, but the role of IRF8 in the regulation of I/R injury progression is still unknown. In this study, we explore the IRF8 function in the I/R-mediated liver injury using overexpressed hepatic IRF8 and knockout mice. According to our results, IRF8 knockout mice had significantly lower inflammatory cells infiltration, inflammatory cytokines release and serum aspartate aminotransferase/alanine aminotransferase levels that improved the necrotic injury after I/R, unlike the control mice. Conversely, the overexpression of IRF8 in WT mice markedly aggravated the liver structure damage and its abnormal function. We further showed that IRF8-mediated inflammatory cells infiltration were partly dependent on early autophagy and NF-κΒ signal pathway during I/R. AAV8-IRF8-I/R mice pretreated with autophagy inhibitor hydroxychloroquine and NF-κΒ signal pathway inhibitor secukinumab could drastically reverse the IRF8-mediated increase of neutrophil infiltration and chemokine release at different degrees. This work uncovered a critical role of IRF8 in the modulation of the hepatic microenvironment and as a potential target in the initial treatment of I/R injury.

Resolving the graft ischemia-reperfusion injury during liver transplantation at the single cell resolution

Ischemia–reperfusion injury (IRI) remains the major reason for impaired donor graft function and increased mortality post-liver transplantation. The mechanism of IRI involves multiple pathophysiological processes and numerous types of cells. However, a systematic and comprehensive single-cell transcriptional profile of intrahepatic cells during liver transplantation is still unclear. We performed a single-cell transcriptome analysis of 14,313 cells from liver tissues collected from pre-procurement, at the end of preservation and 2 h post-reperfusion. We made detailed annotations of mononuclear phagocyte, endothelial cell, NK/T, B and plasma cell clusters, and we described the dynamic changes of the transcriptome of these clusters during IRI and the interaction between mononuclear phagocyte clusters and other cell clusters. In addition, we found that TNFAIP3 interacting protein 3 (TNIP3), specifically and highly expressed in Kupffer cell clusters post-reperfusion, may have a protective effect on IRI. In summary, our study provides the first dynamic transcriptome map of intrahepatic cell clusters during liver transplantation at single-cell resolution.

Selective Imaging of HClO in the Liver Tissue In Vivo Using a Near-infrared Hepatocyte-specific Fluorescent Probe

Liver injury is typified by an inflammatory response. Hypochlorous acid (HClO), an important endogenous reactive oxygen species, is regarded as a biomarker associated with liver injury. Near-infrared (NIR) fluorescent probes with the advantage of deep tissue penetrating and low auto-fluorescence interference are more suitable for bioimaging in vivo. Thus, in this work, we designed and synthesized a novel NIR hepatocyte-specific fluorescent probe named NHF. The probe NHF showed fast response (<3 s), large spectral variation, and good selectivity to trace HClO in buffer solution. By employing N-acetylgalactosamine (GalNAc) as the targeting ligand, probe NHF can be actively delivered to the liver tissue of zebrafish and mice. It is important that probe NHF is the first NIR hepatocyte-specific fluorescent probe, which successfully visualized the up-regulation of endogenous HClO in the oxygen-glucose deprivation/reperfusion (OGD/R) model HepG2 cells and dynamically monitored APAP-induced endogenous HClO in the liver tissue of zebrafish and mice.

Heme oxygenase-1: Equally important in allogeneic hematopoietic stem cell transplantation and organ transplantation?

The intracellular enzyme heme oxygenase-1 (HO-1) is responsible for the degradation of cell-free (cf) heme. Cfheme, released upon cell damage and cell death from hemoglobin, mitochondria and myoglobin, functions as a powerful damage-associated molecular pattern (DAMP). Indeed, cfheme plays a role in a myriad of diseases characterized by (systemic) inflammation, and its rapid degradation by HO-1 is pivotal to maintain homeostasis. In the past decade, HO-1 has been extensively studied for its potential protective role in different transplantation settings, including allogeneic hematopoietic stem cell transplantation (HSCT), solid organ transplantation and pancreatic islet transplantation. These studies have shown that HO-1 can be induced by a wide range of molecules, and that induction of HO-1 has the potential to significantly reduce the incidence and severity of transplantation-related complications such as graft-versus-host disease (GvHD) and ischemia/reperfusion injury (IRI). As such, further investigation into the use of HO-1-inducing agents in human transplantation settings to facilitate the potential use of these agents in the clinic is warranted. In this review, we summarize the literature of the past 10 years on the role of HO-1 in allogeneic HSCT, solid organ transplantation (focusing on kidney and liver) and pancreatic islet transplantation. Furthermore, we provide a hypothesis about the way that HO-1 is able to provide protection against acute GvHD after allogeneic HSCT. A total of 48 research articles and 17 review articles were included in this review.

Inflammatory processes in the liver: divergent roles in homeostasis and pathology

The hepatic immune system is designed to tolerate diverse harmless foreign moieties to maintain homeostasis in the healthy liver. Constant priming and regulation ensure that appropriate immune activation occurs when challenged by pathogens and tissue damage. Failure to accurately discriminate, regulate, or effectively resolve inflammation offsets this balance, jeopardizing overall tissue health resulting from an either  overly tolerant or an overactive inflammatory response. Compelling scientific and clinical evidence links dysregulated hepatic immune and inflammatory responses upon sterile injury to several pathological conditions in the liver, particularly nonalcoholic steatohepatitis and ischemia-reperfusion injury. Murine and human studies have described interactions between diverse immune repertoires and nonhematopoietic cell populations in both physiological and pathological activities in the liver, although the molecular mechanisms driving these associations are not clearly understood. Here, we review the dynamic roles of inflammatory mediators in responses to sterile injury in the context of homeostasis and disease, the clinical implications of dysregulated hepatic immune activity and therapeutic developments to regulate liver-specific immunity.