Natural Killer Cells in Hepatic Ischemia-Reperfusion Injury

Sunitinib alleviates hepatic ischemia reperfusion injury by inhibiting the JAK2/STAT pathway and promoting the M2 polarization of macrophages

BACKGROUND

Hepatic ischemia reperfusion injury (IRI) is a common liver surgery complication. This study aims to explore the effect and potential mechanism of Sunitinib - a multi-target tyrosine kinase inhibitor - on hepatic IRI.

METHODS

We established a hepatic IRI model using C57BL/6 mice, and integrated 40 mg/kg of Sunitinib, solely or combined with 100 μg/kg of coumermycin A1 (C-A1), in the treatment strategy. H&E staining, TUNEL assay, and detection of serum ALT and AST activities were used to assess liver damage. Further, ELISA kits and Western Blots were utilized to determine IL-1β, TNF-α, IL-6, CXCL10, and CXCL2 levels. Primary macrophages, once isolated, were cultured in vitro with either 2 nM of Sunitinib, or Sunitinib in conjunction with 1 μM of C-A1, to gauge their influence on macrophage polarization. qPCR and Western blot were conducted to examine the level of p-STAT1/STAT1, p-STAT3/STAT3, p-JAK2/JAK2, and M1/M2 polarization markers. To quantify immune cell infiltration, we applied Immunofluorescence.

RESULTS

Sunitinib pretreatment significantly alleviated liver injury and reduced p-STAT1/STAT1, p-STAT3/STAT3, p-JAK2/JAK2 levels. In vitro, Sunitinib treatment curbed M1 polarization induced by LPS + IFN-γ and bolstered M2 polarization triggered by IL-4. C-A1 application upregulated JAK2/STAT pathway phosphorylation and promoted LPS + IFN-γ-induced M1 polarization, which was reversed by Sunitinib treatment. In IL-4-stimulated macrophages, application of C-A1 activated the JAK2/STAT pathway and decreased M2-type macrophages, which was reversed by Sunitinib treatment either.

CONCLUSION

Sunitinib is capable of guiding the polarization of macrophages toward an M2-type phenotype via the inhibition of the JAK2/STAT pathway, thereby exerting a protective effect on hepatic IRI.

Ischemia-free liver transplantation improves the prognosis of recipients using functionally marginal liver grafts

BACKGROUND/AIMS

The shortage of donor liver hinders the development of liver transplantation. This study aimed to clarify the poor outcomes of functionally marginal liver grafts (FMLs) and provide evidence for the improvement of ischemia-free liver transplantation (IFLT) after FML transplantation.

METHODS

Propensity score matching was used to control for confounding factors. The outcomes of the control group and FML group were compared to demonstrate the negative impact of FMLs on liver transplantation patients. We compared the clinical improvements of the different surgical types. To elucidate the underlying mechanism, we conducted bioinformatic analysis based on transcriptome and single-cell profiles.

RESULTS

FMLs had a significantly greater hazard ratio (HR: 1.969, P=0.018) than did other marginal livers. A worse 90-day survival (Mortality: 12.3% vs. 5.0%, P=0.007) was observed in patients who underwent FML transplantation. Patients who received FMLs had a significant improvement in overall survival after IFLT (Mortality: 10.4% vs 31.3%, P=0.006). Pyroptosis and inflammation were inhibited in patients who underwent IFLT. The infiltration of natural killer cells was lower in liver grafts from these patients. Bulk transcriptome profiles revealed a positive relationship between IL-32 and Caspase 1 (R=0.73, P=0.01) and between IL-32 and Gasdermin D (R=0.84, P=0.0012).

CONCLUSION

FML is a more important negative prognostic parameter than other marginal liver parameters. IFLT might ameliorate liver injury in FMLs by inhibiting the infiltration of NK cells, consequently leading to the abortion of IL-32, which drives pyroptosis in monocytes and macrophages.

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.

Predicting mitophagy-related genes and unveiling liver endothelial cell heterogeneity in hepatic ischemia-reperfusion injury

Background

Hepatic Ischemia-Reperfusion Injury (HIRI) is a major complication in liver transplants and surgeries, significantly affecting postoperative outcomes. The role of mitophagy, essential for removing dysfunctional mitochondria and maintaining cellular balance, remains unclear in HIRI.

Methods

To unravel the role of mitophagy-related genes (MRGs) in HIRI, we assembled a comprehensive dataset comprising 44 HIRI samples alongside 44 normal control samples from the Gene Expression Omnibus (GEO) database for this analysis. Using Random Forests and Support Vector Machines - Recursive Feature Elimination (SVM-RFE), we pinpointed eight pivotal genes and developed a logistic regression model based on these findings. Further, we employed consensus cluster analysis for classifying HIRI patients according to their MRG expression profiles and conducted weighted gene co-expression network analysis (WGCNA) to identify clusters of genes that exhibit high correlation within different modules. Additionally, we conducted single-cell RNA sequencing data analysis to explore insights into the behavior of MRGs within the HIRI.

Results

We identified eight key genes (FUNDC1, VDAC1, MFN2, PINK1, CSNK2A2, ULK1, UBC, MAP1LC3B) with distinct expressions between HIRI and controls, confirmed by PCR validation. Our diagnostic model, based on these genes, accurately predicted HIRI outcomes. Analysis revealed a strong positive correlation of these genes with monocytic lineage and a negative correlation with B and T cells. HIRI patients were divided into three subclusters based on MRG profiles, with WGCNA uncovering highly correlated gene modules. Single-cell analysis identified two types of endothelial cells with different MRG scores, indicating their varied roles in HIRI.

Conclusions

Our study highlights the critical role of MRGs in HIRI and the heterogeneity of endothelial cells. We identified the macrophage migration inhibitory factor (MIF) and cGAS-STING (GAS) pathways as regulators of mitophagy's impact on HIRI. These findings advance our understanding of mitophagy in HIRI and set the stage for future research and therapeutic developments.

Analysis and experimental validation of IL-17 pathway and key genes as central roles associated with inflammation in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) elicits an immune-inflammatory response that may result in hepatocyte necrosis and apoptosis, ultimately culminating in postoperative hepatic dysfunction and hepatic failure. The precise mechanisms governing the pathophysiology of HIRI remain incompletely understood, necessitating further investigation into key molecules and pathways implicated in disease progression to guide drug discovery and potential therapeutic interventions. Gene microarray data was downloaded from the GEO expression profile database. Integrated bioinformatic analyses were performed to identify HIRI signature genes, which were subsequently validated for expression levels and diagnostic efficacy. Finally, the gene expression was verified in an experimental HIRI model and the effect of anti-IL17A antibody intervention in three time points (including pre-ischemic, post-ischemic, and at 1 h of reperfusion) on HIRI and the expression of these genes was investigated. Bioinformatic analyses of the screened characterized genes revealed that inflammation, immune response, and cell death modulation were significantly associated with HIRI pathophysiology. CCL2, BTG2, GADD45A, FOS, CXCL10, TNFRSF12A, and IL-17 pathway were identified as key components involved in the HIRI. Serum and liver IL-17A expression were significantly upregulated during the initial phase of HIRI. Pretreatment with anti-IL-17A antibody effectively alleviated the damage of liver tissue, suppressed inflammatory factors, and serum transaminase levels, and downregulated the mRNA expression of CCL2, GADD45A, FOS, CXCL10, and TNFRSF12A. Injection of anti-IL17A antibody after ischemia and at 1 h of reperfusion failed to demonstrate anti-inflammatory and attenuating HIRI benefits relative to earlier intervention. Our study reveals that the IL-17 pathway and related genes may be involved in the proinflammatory mechanism of HIRI, which may provide a new perspective and theoretical basis for the prevention and treatment of HIRI.

Deletion of protein kinase C θ attenuates hepatic ischemia/reperfusion injury and further elucidates its mechanism in pathophysiology

Objectives

Hepatic ischemia-reperfusion (HIR) is a severe process in pathophysiology that occurs clinically in hepatectomy, and hepatic transplantations. The present study aimed to investigate the effect of PKC θ deletion against HIR injury and elucidate its mechanism in pathophysiology.

Materials and Methods

HIR injury was induced in wild-type and PKC θ deletion mice treated with or without heme. The ALT and AST levels were determined to evaluate liver function. HIR injury was observed via histological examination. Oxidative stress and inflammatory response markers, and their signaling pathways were detected.

Results

The study found that PKC θ knockout decreased serum AST and ALT levels when compared to the WT mice. Furthermore, heme treatment significantly reduced the ALT and AST levels of the PKC θ deletion mice compared with the untreated PKC θ deletion mice. PKC θ deletion markedly elevated superoxide dismutase activity in the liver tissue, reduced malondialdehyde content in the tissue, and the serum TNF-α and IL-6 levels compared with the WT mice. Heme treatment was observed to elevate the activity of SOD and reduced MDA content and serum of TNF-α and IL 6 in the PKC θ deletion animals. Meanwhile, heme treatment increased HO-1 and Nrf 2 protein expression, and reduced the levels of TLR4, phosphorylated NF-κB, and IKB-α.

Conclusion

These findings suggested that PKC θ deletion ameliorates HIR, and heme treatment further improves HIR, which is related to regulation of PKC θ deletion on Nrf 2/HO-1 and TLR4/NF-κB/IKB α pathway.

Hepatocellular SETDB1 Regulates Hepatic Ischemia-Reperfusion Injury through Targeting Lysine Methylation of ASK1 Signal

Background: Hepatic ischemia-reperfusion injury (HIRI) stands as an unavoidable complication arising from liver surgery, profoundly intertwined with its prognosis. The role of lysine methyltransferase SET domain bifurcated 1 (SETDB1) in HIRI remains elusive, despite its confirmation as a potential therapeutic target for diverse diseases. Here, we investigated the mechanism by which SETDB1 regulated HIRI. Methods: RNA sequencing data were used to identify the expression and potential targets of SETDB1 through bioinformatics analysis. To elucidate the impact of SETDB1 on HIRI, both an in vivo model of HIRI in mice and an in vitro model of hepatocyte hypoxia/reoxygenation were established. Biochemical and histological analyses were used to investigate the influence of SETDB1 on liver damage mediated by HIRI. Chromatin immunoprecipitation and coimmunoprecipitation were implemented to explore the in-depth mechanism of SETDB1 regulating HIRI. Results: We confirmed that hepatocellular SETDB1 was up-regulated during HIRI and had a close correlation with HIRI-related inflammation and apoptosis. Moreover, inhibition of SETDB1 could mitigate HIRI-induced liver damage, inflammation, and apoptosis. Through our comprehensive mechanistic investigation, we revealed that SETDB1 interacts with apoptosis-signal-regulating kinase 1 (ASK1) and facilitates the methylation of its lysine residues. Inhibition of SETDB1 resulted in reduced phosphorylation of ASK1, leading to a marked suppression of downstream c-Jun N-terminal kinase (JNK)/p38 signaling pathway activation. The therapeutic effect on inflammation and apoptosis achieved through SETDB1 inhibition was nullified by the restoration of JNK/p38 signaling activation through ASK1 overexpression. Conclusions: The findings from our study indicate that SETDB1 mediates lysine methylation of ASK1 and modulates the activation of the ASK1-JNK/p38 pathway, thus involved in HIRI-induced inflammation and apoptosis. These results suggest that SETDB1 holds promise as a potential therapeutic target for mitigating HIRI.

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.

Non-coding RNAs: The potential biomarker or therapeutic target in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) is the major complication of liver surgery and liver transplantation, that may increase the postoperative morbidity, mortality, tumor progression, and metastasis. The underlying mechanisms have been extensively investigated in recent years. Among these, oxidative stress, inflammatory responses, immunoreactions, and cell death are the most studied. Non-coding RNAs (ncRNAs) are defined as the RNAs that do not encode proteins, but can regulate gene expressions. In recent years, ncRNAs have emerged as research hotspots for various diseases. During the progression of HIRI, ncRNAs are differentially expressed, while these dysregulations of ncRNAs, in turn, have been verified to be related to the above pathological processes involved in HIRI. ncRNAs mainly contain microRNAs, long ncRNAs, and circular RNAs, some of which have been reported as biomarkers for early diagnosis or assessment of liver damage severity, and as therapeutic targets to attenuate HIRI. Here, we briefly summarize the common pathophysiology of HIRI, describe the current knowledge of ncRNAs involved in HIRI in animal and human studies, and discuss the potential of ncRNA-targeted therapeutic strategies. Given the scarcity of clinical trials, there is still a long way to go from pre-clinical to clinical application, and further studies are needed to uncover their potential as therapeutic targets.

Hepatocyte-specific Sox9 knockout ameliorates acute liver injury by suppressing SHP signaling and improving mitochondrial function

BACKGROUND AND AIMS

Sex determining region Y related high-mobility group box protein 9 (Sox9) is expressed in a subset of hepatocytes, and it is important for chronic liver injury. However, the roles of Sox9+ hepatocytes in response to the acute liver injury and repair are poorly understood.

METHODS

In this study, we developed the mature hepatocyte-specific Sox9 knockout mouse line and applied three acute liver injury models including PHx, CCl4 and hepatic ischemia reperfusion (IR). Huh-7 cells were subjected to treatment with hydrogen peroxide (H2O2) in order to induce cellular damage in an in vitro setting.

RESULTS

We found the positive effect of Sox9 deletion on acute liver injury repair. Small heterodimer partner (SHP) expression was highly suppressed in hepatocyte-specific Sox9 deletion mouse liver, accompanied by less cell death and more cell proliferation. However, in mice with hepatocyte-specific Sox9 deletion and SHP overexpression, we observed an opposite phenotype. In addition, the overexpression of SOX9 in H2O2-treated Huh-7 cells resulted in an increase in cytoplasmic SHP accumulation, accompanied by a reduction of SHP in the nucleus. This led to impaired mitochondrial function and subsequent cell death. Notably, both the mitochondrial dysfunction and cell damage were reversed when SHP siRNA was employed, indicating the crucial role of SHP in mediating these effects. Furthermore, we found that Sox9, as a vital transcription factor, directly bound to SHP promoter to regulate SHP transcription.

CONCLUSIONS

Overall, our findings unravel the mechanism by which hepatocyte-specific Sox9 knockout ameliorates acute liver injury via suppressing SHP signaling and improving mitochondrial function. This study may provide a new treatment strategy for acute liver injury in future.

NO-IL-6/10-IL-1β axis: a new pathway in steatotic and non-steatotic liver grafts from brain-dead donor rats

INTRODUCTION

Brain death (BD) and steatosis are both risk factors for organ dysfunction or failure in liver transplantation (LT).

MATERIAL AND METHODS

Here, we examine the role of interleukin 6 (IL- 6) and IL-10 in LT of both non-steatotic and steatotic liver recovered from donors after brain death (DBDs), as well as the molecular signaling pathways underlying the effects of such cytokines.

RESULTS

BD reduced IL-6 levels only in nonsteatotic grafts, and diminished IL-10 levels only in steatotic ones. In both graft types, BD increased IL-1β, which was associated with hepatic inflammation and damage. IL-6 administration reduced IL-1β only in non-steatotic grafts and protected them against damage and inflammation. Concordantly, IL-1β inhibition via treatment with an IL-1 receptor antagonist caused the same benefits in non-steatotic grafts. Treatment with IL-10 decreased IL-1β only in steatotic grafts and reduced injury and inflammation specifically in this graft type. Blockading the IL-1β effects also reduced damage and inflammation in steatotic grafts. Also, blockade of IL-1β action diminished hepatic cAMP in both types of livers, and this was associated with a reduction in liver injury and inflammation, then pointing to IL-1β regulating cAMP generation under LT and BD conditions. Additionally, the involvement of nitric oxide (NO) in the effects of interleukins was evaluated. Pharmacological inhibition of NO in LT from DBDs prompted even more evident reductions of IL-6 or IL-10 in non-steatotic and steatotic grafts, respectively. This exacerbated the already high levels of IL-1β seen in LT from DBDs, causing worse damage and inflammation in both graft types. The administration of NO donors to non-steatotic grafts potentiated the beneficial effects of endogenous NO, since it increased IL-6 levels, and reduced IL-1β, inflammation, and damage. However, treatment with NO donors in steatotic grafts did not modify IL-10 or IL-1β levels, but induced more injurious effects tan the induction of BD alone, characterized by increased nitrotyrosine, lipid peroxidation, inflammation, and hepatic damage.

CONCLUSION

Our study thus highlights the specificity of new signaling pathways in LT from DBDs: NO-IL-6-IL-1β in non-steatotic livers and NO-IL-10-IL-1β in steatotic ones. This opens up new therapeutic targets that could be useful in clinical LT.

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.

Non-Classical HLA Class 1b and Hepatocellular Carcinoma

A number of studies are underway to gain a better understanding of the role of immunity in the pathogenesis of hepatocellular carcinoma and to identify subgroups of individuals who may benefit the most from systemic therapy according to the etiology of their tumor. Human leukocyte antigens play a key role in antigen presentation to T cells. This is fundamental to the host's defense against pathogens and tumor cells. In addition, HLA-specific interactions with innate lymphoid cell receptors, such those present on natural killer cells and innate lymphoid cell type 2, have been shown to be important activators of immune function in the context of several liver diseases. More recent studies have highlighted the key role of members of the non-classical HLA-Ib and the transcript adjacent to the HLA-F locus, FAT10, in hepatocarcinoma. The present review analyzes the major contribution of these molecules to hepatic viral infection and hepatocellular prognosis. Particular attention has been paid to the association of natural killer and Vδ2 T-cell activation, mediated by specific HLA class Ib molecules, with risk assessment and novel treatment strategies to improve immunotherapy in HCC.

The Role of the NLRP3 Inflammasome and Programmed Cell Death in Acute Liver Injury

Acute liver injury (ALI) is a globally important public health issue that, when severe, rapidly progresses to acute liver failure, seriously compromising the life safety of patients. The pathogenesis of ALI is defined by massive cell death in the liver, which triggers a cascade of immune responses. Studies have shown that the aberrant activation of the nod-like receptor protein 3 (NLRP3) inflammasome plays an important role in various types of ALI and that the activation of the NLRP3 inflammasome causes various types of programmed cell death (PCD), and these cell death effectors can in turn regulate NLRP3 inflammasome activation. This indicates that NLRP3 inflammasome activation is inextricably linked to PCD. In this review, we summarize the role of NLRP3 inflammasome activation and PCD in various types of ALI (APAP, liver ischemia reperfusion, CCl4, alcohol, Con A, and LPS/D-GalN induced ALI) and analyze the underlying mechanisms to provide references for future relevant studies.

Innate Immune Cells during Machine Perfusion of Liver Grafts-The Janus Face of Hepatic Macrophages

Machine perfusion is an emerging technology in the field of liver transplantation. While machine perfusion has now been implemented in clinical routine throughout transplant centers around the world, a debate has arisen regarding its concurrent effect on the complex hepatic immune system during perfusion. Currently, our understanding of the perfusion-elicited processes involving innate immune cells remains incomplete. Hepatic macrophages (Kupffer cells) represent a special subset of hepatic immune cells with a dual pro-inflammatory, as well as a pro-resolving and anti-inflammatory, role in the sequence of ischemia-reperfusion injury. The purpose of this review is to provide an overview of the current data regarding the immunomodulatory role of machine perfusion and to emphasize the importance of macrophages for hepatic ischemia-reperfusion injury.