PTEN-mediated Akt/β-catenin/Foxo1 signaling regulates innate immune responses in mouse liver ischemia/reperfusion injury

Exosome-related gene identification and diagnostic model construction in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) may cause severe hepatic impairment, acute hepatic insufficiency, and multiorgan system collapse. Exosomes can alleviate HIRI. Therefore, this study explored the role of exosomal-related genes (ERGs) in HIRI using bioinformatics to determine the underlying molecular mechanisms and novel diagnostic markers for HIRI. We merged the GSE12720, GSE14951, and GSE15480 datasets obtained from the Gene Expression Omnibus (GEO) database into a combined gene dataset (CGD). CGD was used to identify differentially expressed genes (DEGs) based on a comparison of the HIRI and healthy control cohorts. The impact of these DEGs on HIRI was assessed through gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA). ERGs were retrieved from the GeneCards database and prior studies, and overlapped with the identified DEGs to yield the set of exosome-related differentially expressed genes (ERDEGs). Functional annotations and enrichment pathways of these genes were determined using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Diagnostic models for HIRI were developed using least absolute shrinkage and selection operator (LASSO) regression and support vector machine (SVM) algorithms. Key genes with diagnostic value were identified from the overlap, and single-sample gene-set enrichment analysis (ssGSEA) was conducted to evaluate the immune infiltration characteristics. A molecular regulatory interaction network was established using Cytoscape software to elucidate the intricate regulatory mechanisms of key genes in HIRI. Finally, exosome score (Es) was obtained using ssGSEA and the HIRI group was divided into the Es_High and Es_Low groups based on the median Es. Gene expression was analyzed to understand the impact of all genes in the CGD on HIRI. Finally, the relative expression levels of the five key genes in the hypoxia-reoxygenation (H/R) model were determined using quantitative real-time PCR (qRT-PCR). A total of 3810 DEGs were identified through differential expression analysis of the CGD, and 61 of these ERDEGs were screened. Based on GO and KEGG enrichment analyses, the ERDEGs were mainly enriched in wound healing, MAPK, protein kinase B signaling, and other pathways. GSEA and GSVA revealed that these genes were mainly enriched in the TP53, MAPK, TGF[Formula: see text], JAK-STAT, MAPK, and NFKB pathways. Five key genes (ANXA1, HNRNPA2B1, ICAM1, PTEN, and THBS1) with diagnostic value were screened using the LASSO regression and SVM algorithms and their molecular interaction network was established using Cytoscape software. Based on ssGSEA, substantial variations were found in the expression of 18 immune cell types among the groups (p < 0.05). Finally, the Es of each HIRI patient was calculated. ERDEGs in the Es_High and Es_Low groups were enriched in the IL18, TP53, MAPK, TGF[Formula: see text], and JAK-STAT pathways. The differential expression of these five key genes in the H/R model was verified using qRT-PCR. Herein, five key genes were identified as potential diagnostic markers. Moreover, the potential impact of these genes on pathways and the regulatory mechanisms of their interaction network in HIRI were revealed. Altogether, our findings may serve as a theoretical foundation for enhancing clinical diagnosis and elucidating underlying pathogeneses.

Identification and validation of ferroptosis-related hub genes and immune infiltration in liver ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a cumulation of pathophysiological processes that involves cell and organelle damage upon blood flow constraint and subsequent restoration. However, studies on overall immune infiltration and ferroptosis in liver ischemia-reperfusion injury (LIRI) are limited. This study explored immune cell infiltration and ferroptosis in LIRI using bioinformatics and experimental validation. The GSE151648 dataset, including 40 matched pairs of pre- and post- transplant liver samples was downloaded for bioinformatic analysis. Eleven hub genes were identified by overlapping differentially expressed genes (DEGs), iron genes, and genes identified through weighted gene co-expression network analysis (WGCNA). Subsequently, the pathway enrichment, transcription factor-target, microRNA-mRNA and protein-protein interaction networks were investigated. The diagnostic model was established by logistic regression, which was validated in the GSE23649 and GSE100155 datasets and verified using cytological experiments. Moreover, several drugs targeting these genes were found in DrugBank, providing a more effective treatment for LIRI. In addition, the expression of 11 hub genes was validated using quantitative real-time polymerase chain reaction (qRT-PCR) in liver transplantation samples and animal models. The expression of the 11 hub genes increased in LIRI compared with the control. Five genes were significantly enriched in six biological process terms, six genes showed high enrichment for LIRI-related signaling pathways. There were 56 relevant transcriptional factors and two central modules in the protein-protein interaction network. Further immune infiltration analysis indicated that immune cells including neutrophils and natural killer cells were differentially accumulated in the pre- and post-transplant groups, and this was accompanied by changes in immune-related factors. Finally, 10 targeted drugs were screened. Through bioinformatics and further experimental verification, we identified hub genes related to ferroptosis that could be used as potential targets to alleviate LIRI.

CircRNA-Phf21a_0002 promotes pyroptosis to aggravate hepatic ischemia/ reperfusion injury by sponging let-7b-5p

Hepatic ischemia‒reperfusion injury is a common injury in liver surgery and liver transplantation that can lead to liver function damage, including oxidative stress, apoptosis, autophagy and inflammatory reactions. Pyroptosis is a type of inflammatory programmed cell death that has been implicated in ischemia‒reperfusion injury-associated inflammatory reactions. Although circular RNAs can regulate cell death in hepatic ischemia‒reperfusion injury, their relationship with pyroptosis remains unclear. Therefore, this study aimed to investigate the effect of circular RNA on pyroptosis in hepatic ischemia‒reperfusion injury. We constructed a mouse hepatic ischemia‒reperfusion injury model for circular RNA sequencing and obtained 40 circular RNAs with significant differential expression, of which 39 were upregulated and 1 was downregulated. Subsequently, the endogenous competitive RNA network was constructed using TarBase, miRTarBase, TargetScan, RNAhybrid, and miRanda. Gene Set Enrichment Analysis, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology functional analyses of downstream target genes revealed that circRNA-Phf21a_0002 might affect pyroptosis by regulating the mTOR signaling pathway and Bach1 by sponging let-7b-5p. The overexpression plasmid upregulated the expression of circRNA-Phf21a_0002 in a hypoxia/reoxygenation model, which aggravated pyroptosis in AML12 cells and apoptosis and necrosis of hepatocytes. Next, we investigated the underlying mechanism and found that circRNA-Phf21a_0002 enabled the expression of Bach1 through sponging of let-7b-5p. The aggravation of pyroptosis via overexpression of circRNA-Phf21a_0002 was reversed by let-7b-5p mimics in hypoxia/reoxygenation-subjected AML12 cells. Collectively, our study clarifies that circRNA-Phf21a_0002 aggravates the pyroptosis of hepatocytes related to ischemia-reperfusion by sponging let-7b-5p. These findings provide new molecular mechanisms and novel biomarkers for follow-up treatment.

Novel IL-4/HB-EGF-dependent crosstalk between eosinophils and macrophages controls liver regeneration after ischaemia and reperfusion injury

OBJECTIVE

Previous studies indicate that eosinophils are recruited into the allograft following orthotopic liver transplantation and protect from ischaemia reperfusion (IR) injury. In the current studies, we aim to explore whether their protective function could outlast during liver repair.

DESIGN

Eosinophil-deficient mice and adoptive transfer of bone marrow-derived eosinophils (bmEos) were employed to investigate the effects of eosinophils on tissue repair and regeneration after hepatic IR injury. Aside from exogenous cytokine or neutralising antibody treatments, mechanistic studies made use of a panel of mouse models of eosinophil-specific IL-4/IL-13-deletion, cell-specific IL-4rα-deletion in liver macrophages and hepatocytes and macrophage-specific deletion of heparin-binding epidermal growth factor-like growth factor (hb-egf).

RESULT

We observed that eosinophils persisted over a week following hepatic IR injury. Their peak accumulation coincided with that of hepatocyte proliferation. Functional studies showed that eosinophil deficiency was associated with a dramatic delay in liver repair, which was normalised by the adoptive transfer of bmEos. Mechanistic studies demonstrated that eosinophil-derived IL-4, but not IL-13, was critically involved in the reparative function of these cells. The data further revealed a selective role of macrophage-dependent IL-4 signalling in liver regeneration. Eosinophil-derived IL-4 stimulated macrophages to produce HB-EGF. Moreover, macrophage-specific hb-egf deletion impaired hepatocyte regeneration after IR injury.

CONCLUSION

Together, these studies uncovered an indispensable role of eosinophils in liver repair after acute injury and identified a novel crosstalk between eosinophils and macrophages through the IL-4/HB-EGF axis.

Loss of macrophage TSC1 exacerbates sterile inflammatory liver injury through inhibiting the AKT/MST1/NRF2 signaling pathway

Tuberous sclerosis complex 1 (TSC1) plays important roles in regulating innate immunity. However, the precise role of TSC1 in macrophages in the regulation of oxidative stress response and hepatic inflammation in liver ischemia/reperfusion injury (I/R) remains unknown. In a mouse model of liver I/R injury, deletion of myeloid-specific TSC1 inhibited AKT and MST1 phosphorylation, and decreased NRF2 accumulation, whereas activated TLR4/NF-κB pathway, leading to increased hepatic inflammation. Adoptive transfer of AKT- or MST1-overexpressing macrophages, or Keap1 disruption in myeloid-specific TSC1-knockout mice promoted NRF2 activation but reduced TLR4 activity and mitigated I/R-induced liver inflammation. Mechanistically, TSC1 in macrophages promoted AKT and MST1 phosphorylation, and protected NRF2 from Keap1-mediated ubiquitination. Furthermore, overexpression AKT or MST1 in TSC1-knockout macrophages upregulated NRF2 expression, downregulated TLR4/NF-κB, resulting in reduced inflammatory factors, ROS and inflammatory cytokine-mediated hepatocyte apoptosis. Strikingly, TSC1 induction in NRF2-deficient macrophages failed to reverse the TLR4/NF-κB activity and production of pro-inflammatory factors. Conclusions: Macrophage TSC1 promoted the activation of the AKT/MST1 signaling pathway, increased NRF2 levels via reducing Keap1-mediated ubiquitination, and modulated oxidative stress-driven inflammatory responses in liver I/R injury. Our findings underscore the critical role of macrophage TSC1 as a novel regulator of innate immunity and imply the therapeutic potential for the treatment of sterile liver inflammation in transplant recipients. Schematic illustration of macrophage TSC1-mediated AKT/MST1/NRF2 signaling pathway in I/R-triggered liver inflammation. Macrophage TSC1 can be activated in I/R-stressed livers. TSC1 activation promotes phosphorylation of AKT and MST1, which in turn increases NRF2 expression and inhibits ROS production and TLR4/NF-κB activation, resulting in reduced hepatocellular apoptosis in I/R-triggered liver injury.

Interferon-tau protects bovine endometrial epithelial cells against inflammatory injury by regulating the PI3K/AKT/β-catenin/FoxO1 signaling axis

Endometritis is one of the most common causes of infertility in dairy cows, and is histopathologically characterized by inflammation and damage of endometrial epithelium. Interferon-tau (IFN-τ) is a novel type I interferon secreted by ruminant trophoblast cells with low cytotoxicity even at high doses. Previous studies suggested that IFN-τ plays an important role in inflammation. However, the mechanisms whereby IFN-τ may modulate the inflammatory responses in the bovine endometrium are unknown. In the present study, primary bovine endometrial epithelial cells (BEEC) isolated from fresh and healthy uterine horns were used for in vitro studies. The integrity of BEEC was assessed by immunofluorescence staining for cytokeratin 18 (CK-18, a known epithelial marker). For the experiments, BEEC were stimulated with different concentrations of lipopolysaccharide (LPS; 0-20 µg/mL) for different times (0-24 h). Cell viability and apoptosis were assessed via CCK-8 and flow cytometry. In a preliminary study, we observed that compared with the control group without LPS, 10 µg/mL of LPS stimulation for 24 h induced apoptosis. In a subsequent study, 20 or 40 ng/mL of IFN-τ alleviated LPS-induced apoptosis. Relative to the LPS group, western blotting further revealed that IFN-τ inhibited the protein abundance of TLR4 and phosphorylated (p-) p65 (p-p65) and Bax/Bcl-2 ratio, suggesting that IFN-τ can protect BEEC against inflammatory injury. Furthermore, the protein abundance of p-phosphoinositide 3-kinase (p-PI3K), p-protein kinase B (p-AKT), p-glycogen synthase kinase-3β (p-GSK3β), β-catenin, and p-forkhead box O1 (p-FoxO1) was lower in the LPS group, whereas IFN-τ upregulated their abundance. The use of LY294002, a specific inhibitor of PI3K/AKT, attenuated the upregulation of p-PI3K, p-AKT p-GSK3β, β-catenin, and p-FoxO1 induced by IFN-τ, and also blocked the downregulation of TLR4, p-p65, and Bax/Bcl-2 ratio. This suggested that the inhibition of TLR4 signaling by IFN-τ was mediated by the PI3K/AKT pathway. Furthermore, compared with the LPS group, the β-catenin agonist SB216763 led to greater p-FoxO1 and lower p-p65 and cell apoptosis. In contrast, knockdown of β-catenin using small interfering RNA had the opposite effects. To explore the role of FoxO1 on the inhibition of TLR4 by IFN-τ, we employed LY294002 to inhibit the PI3K/AKT while FoxO1 was knocked down. Results revealed that the knockdown of FoxO1 blocked the upregulation of TLR4 and p-p65 induced by LY294002, and enhanced the inhibition of IFN-τ on TLR4, p-p65, and cell apoptosis. Overall, these findings confirmed that IFN-τ can protect endometrial epithelial cells against inflammatory injury via suppressing TLR4 activation through the regulation of the PI3K/AKT/β-catenin/FoxO1 axis. These represent new insights into the molecular mechanisms underlying the anti-inflammatory function of IFN-τ in BEEC, and also provide a theoretical basis for further studies on the in vivo application of IFN-τ to help prevent negative effects of endometritis.

Clinical and preclinical evaluation of miR-144-5p as a key target for major depressive disorder

BACKGROUND

Neuronal abnormalities are closely associated with major depressive disorder (MDD). Available evidence suggests a role for microRNAs (miRNAs) in regulating the expression of genes involved in MDD. Hence, miRNAs that can be potential therapeutic targets need to be identified.

METHODS

A mouse model of chronic unpredictable stress (CUS) was used to evaluate the function of miRNAs in MDD. miR-144-5p was screened from the hippocampi of CUS mice based on sequencing results. Adenovirus-associated vectors were used to overexpress or knockdown miR-144-5p in mice. BpV(pic) and LY294002 were used to determine the relationship between miR-144-5p target genes PTEN and TLR4 in neuronal impairment caused by miR-144-5p deficiency. Western blotting, immunofluorescence, ELISA immunosorbent assay, and Golgi staining were used to detect neuronal abnormalities. Serum samples from healthy individuals and patients with MDD were used to detect miR-144-5p levels in the serum and serum exosomes using qRT-PCR.

RESULTS

miR-144-5p expression was significantly decreased within the hippocampal dentate gyrus (DG) of CUS mice. Upregulation of miR-144-5p in the DG ameliorated depression-like behavior in CUS mice and attenuated neuronal abnormalities by directly targeting PTEN and TLR4 expression. Furthermore, miR-144-5p knockdown in normal mice led to depression-like behavior via inducing neuronal abnormalities, including abnormal neurogenesis, neuronal apoptosis, altered synaptic plasticity, and neuroinflammation. miR-144-5p deficiency-mediated neuronal impairment was mediated by PI3K/Akt/FoxO1 signaling. Furthermore, miR-144-5p levels were downregulated in the sera of patients with MDD and associated with depressive symptoms. Consistently, serum exosome-derived miR-144-5p levels were decreased in patients with MDD.

CONCLUSION

miR-144-5p plays a vital role in regulating neuronal abnormalities in depression. Our findings provide translational evidence that miR-144-5p is a new potential therapeutic target for MDD.

Macrophage PTEN controls STING-induced inflammation and necroptosis through NICD/NRF2 signaling in APAP-induced liver injury

BACKGROUND

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) signaling has been known to play a critical role in maintaining cellular and tissue homeostasis, which also has an essential role in the inflammatory response. However, it remains unidentified whether and how the macrophage PTEN may govern the innate immune signaling stimulator of interferon genes (STING) mediated inflammation and hepatocyte necroptosis in APAP-induced liver injury (AILI).

METHODS

Myeloid-specific PTEN knockout (PTEN^M-KO) and floxed PTEN (PTEN^FL/FL) mice were treated with APAP (400 mg/kg) or PBS. In a parallel in vitro study, bone marrow-derived macrophages (BMMs) were isolated from these conditional knockout mice and transfected with CRISPR/Cas9-mediated Notch1 knockout (KO) or CRISPR/Cas9-mediated STING activation vector followed by LPS (100 ng/ml) stimulation.

RESULTS

Here, we report that myeloid-specific PTEN knockout (PTEN^M-KO) mice were resistant to oxidative stress-induced hepatocellular injury with reduced macrophage/neutrophil accumulation and proinflammatory mediators in AILI. PTEN^M-KO increased the interaction of nuclear Notch intracellular domain (NICD) and nuclear factor (erythroid-derived 2)-like 2 (NRF2) in the macrophage nucleus, reducing reactive oxygen species (ROS) generation. Mechanistically, it is worth noting that macrophage NICD and NRF2 co-localize within the nucleus under inflammatory conditions. Additionally, Notch1 promotes the interaction of immunoglobulin kappa J region (RBPjκ) with NRF2. Disruption of the Notch1 signal in PTEN deletion macrophages, reduced RBPjκ and NRF2 binding, and activated STING signaling. Moreover, PTEN^M-KO macrophages with STING activated led to ROS generation and TNF-α release, resulting in hepatocyte necroptosis upon co-culture with primary hepatocytes.

CONCLUSIONS

Our findings demonstrate that the macrophage PTEN-NICD/NRF2-STING axis is critical to regulating oxidative stress-induced liver inflammation and necroptosis in AILI and implies the therapeutic potential for managing sterile liver inflammation. Video Abstract.

Paritaprevir ameliorates experimental acute lung injury in vitro and in vivo

Paritaprevir is a potent inhibitor of the NS3/4A protease used to treat chronic hepatitis C virus infection. However, its therapeutic effect on acute lung injury (ALI) remains to be elucidated. In this study, we investigated the effect of paritaprevir on a lipopolysaccharide (LPS)-induced two-hit rat ALI model. The anti-ALI mechanism of paritaprevir was also studied in human pulmonary microvascular endothelial (HM) cells following LPS-induced injury in vitro. Administration of 30 mg/kg paritaprevir for 3 days protected rats from LPS-induced ALI, as reflected by the changes in the lung coefficient (from 0.75 to 0.64) and lung pathology scores (from 5.17 to 5.20). Furthermore, the levels of the protective adhesion protein VE-cadherin and tight junction protein claudin-5 increased, and the cytoplasmic p-FOX-O1 and nuclear β-catenin and FOX-O1 levels decreased. Similar effects were observed in vitro with LPS-treated HM cells, including decreased nuclear β-catenin and FOX-O1 levels and higher VE-cadherin and claudin-5 levels. Moreover, β-catenin inhibition resulted in higher p-FOX-O1 levels in the cytoplasm. These results suggested that paritaprevir could alleviate experimental ALI via the β-catenin/p-Akt/ FOX-O1 signaling pathway.

Malic Enzyme 1 as a Novel Anti-Ferroptotic Regulator in Hepatic Ischemia/Reperfusion Injury

Ferroptosis has been linked to the pathogenesis of hepatic injury induced by ischemia/reperfusion (I/R). However, the mechanistic basis remains unclear. In this study, by using a mouse model of hepatic I/R injury, it is observed that glutathione (GSH) and cysteine depletion are associated with deficiency of the reducing power of nicotinamide adenine dinucleotide phosphate (NADPH). Genes involved in maintaining NADPH homeostasis are screened, and it is identified that I/R-induced hepatic ferroptosis is significantly associated with reduced expression and activity of NADP+ -dependent malic enzyme 1 (Me1). Mice with hepatocyte-specific Me1 gene deletion exhibit aggravated ferroptosis and liver injury under I/R treatment; while supplementation with L-malate, the substrate of ME1, restores NADPH and GSH levels and eventually inhibits I/R-induced hepatic ferroptosis and injury. A mechanistic study further reveals that downregulation of hepatic Me1 expression is largely mediated by the phosphatase and tensin homologue (PTEN)-dependent suppression of the mechanistic target of rapamycin/sterol regulatory element-binding protein 1 (mTOR/SREBP1) signaling pathway in hepatic I/R model. Finally, PTEN inhibitor, mTOR activator, or SREBP1 over-expression all increase hepatic NADPH, block ferroptosis, and protect liver against I/R injury. Taken together, the findings suggest that targeting ME1 may provide new therapeutic opportunities for I/R injury and other ferroptosis-related hepatic conditions.

Aorta- and liver-generated TMAO enhances trained immunity for increased inflammation via ER stress/mitochondrial ROS/glycolysis pathways

We determined whether gut microbiota-produced trimethylamine (TMA) is oxidized into trimethylamine N-oxide (TMAO) in nonliver tissues and whether TMAO promotes inflammation via trained immunity (TI). We found that endoplasmic reticulum (ER) stress genes were coupregulated with MitoCarta genes in chronic kidney diseases (CKD); TMAO upregulated 190 genes in human aortic endothelial cells (HAECs); TMAO synthesis enzyme flavin-containing monooxygenase 3 (FMO3) was expressed in human and mouse aortas; TMAO transdifferentiated HAECs into innate immune cells; TMAO phosphorylated 12 kinases in cytosol via its receptor PERK and CREB, and integrated with PERK pathways; and PERK inhibitors suppressed TMAO-induced ICAM-1. TMAO upregulated 3 mitochondrial genes, downregulated inflammation inhibitor DARS2, and induced mitoROS, and mitoTEMPO inhibited TMAO-induced ICAM-1. β-Glucan priming, followed by TMAO restimulation, upregulated TNF-α by inducing metabolic reprogramming, and glycolysis inhibitor suppressed TMAO-induced ICAM-1. Our results have provided potentially novel insights regarding TMAO roles in inducing EC activation and innate immune transdifferentiation and inducing metabolic reprogramming and TI for enhanced vascular inflammation, and they have provided new therapeutic targets for treating cardiovascular diseases (CVD), CKD-promoted CVD, inflammation, transplantation, aging, and cancer.

Machine perfusion in liver transplantation

Although liver transplantation is a true success story, many patients still die awaiting an organ. The increasing need for liver grafts therefore remains an unsolved challenge to the transplant community. To address this, transplant donor criteria have been expanded and, for example, more liver grafts with significant steatosis or from donors with circulatory death are being used. These marginal grafts, however, carry an increased risk of graft-associated complications, such as primary nonfunction, delayed graft function, or late biliary injuries. Therefore, reliable assessment of graft viability before use is essential for further success. To achieve this, machine liver perfusion, a procedure developed more than 50 years ago but almost forgotten at the end of the last century, is again of great interest. We describe in this review the clinical most applied machine perfusion techniques, their mechanistic background, and a novel concept of combining immediate organ assessment during hypothermic oxygenated perfusion, followed by an extended phase of normothermic machine perfusion, with simultaneous ex situ treatment of the perfused liver. Such a new approach may allow the pool of usable livers to dramatically increase and improve outcomes for recipients.

The Essential Role of FoxO1 in the Regulation of Macrophage Function

Macrophages are widely distributed in various tissues and organs. They not only participate in the regulation of innate and adaptive immune response, but also play an important role in tissue homeostasis. Dysregulation of macrophage function is closely related to the initiation, development and prognosis of multiple diseases, including infection and tumorigenesis. Forkhead box transcription factor O1 (FoxO1) is an important member among the forkhead box transcription factor family. Through directly binding to the promoter regions of downstream target genes, FoxO1 is implicated in cell proliferation, apoptosis, metabolic activities and other biological processes. In this review, we summarized the regulatory role of FoxO1 in macrophage phagocytosis, migration, differentiation and inflammatory activation. We also emphasized that macrophage reciprocally modulated FoxO1 activity via a post-translational modification (PTM) dominant manner.

Abrogation of graft ischemia-reperfusion injury in ischemia-free liver transplantation

Background

Ischemia‐reperfusion injury (IRI) is considered an inherent component of organ transplantation that compromises transplant outcomes and organ availability. The ischemia‐free liver transplantation (IFLT) procedure has been developed to avoid interruption of blood supply to liver grafts. It is unknown how IFLT might change the characteristics of graft IRI.

Methods

Serum and liver biopsy samples were collected from IFLT and conventional liver transplantation (CLT) recipients. Pathological, metabolomics, transcriptomics, and proteomics analyses were performed to identify the characteristic changes in graft IRI in IFLT.

Results

Peak aspartate aminotransferase (539.59 ± 661.76 U/L versus 2622.28 ± 3291.57 U/L) and alanine aminotransferase (297.64 ± 549.50 U/L versus 1184.16 ± 1502.76 U/L) levels within the first 7 days and total bilirubin levels by day 7 (3.27 ± 2.82 mg/dl versus 8.33 ± 8.76 mg/dl) were lower in the IFLT versus CLT group (all p values < 0.001). The pathological characteristics of IRI were more obvious in CLT grafts. The antioxidant pentose phosphate pathway remained active throughout the procedure in IFLT grafts and was suppressed during preservation and overactivated postrevascularization in CLT grafts. Gene transcriptional reprogramming was almost absent during IFLT but was profound during CLT. Proteomics analysis showed that “metabolism of RNA” was the major differentially expressed process between the two groups. Several proinflammatory pathways were not activated post‐IFLT as they were post‐CLT. The activities of natural killer cells, macrophages, and neutrophils were lower in IFLT grafts than in CLT grafts. The serum levels of 14 cytokines were increased in CLT versus IFLT recipients.

Conclusions

IFLT can largely avoid the biological consequences of graft IRI, thus has the potential to improve transplant outcome while increasing organ utilization.

Enzyme Therapeutic for Ischemia and Reperfusion Injury in Organ Transplantation

Ischemia-reperfusion injury (IRI) remains as a critical challenge for organ transplantation. Herein, an enzyme therapeutic based on superoxide dismutase and catalase for effective mitigation of IRI and pathogen-induced liver injury is reported, providing a therapeutic for organ transplantation and other diseases.

The role and function of CD4+ T cells in hepatic ischemia-reperfusion injury

INTRODUCTION

Hepatic ischemia-reperfusion injury (IRI) is a severe complication frequently encountered in liver surgery, seriously affecting the therapeutic effects, tissue function. Various immune cells are involved in hepatic IRI, including macrophages, NKT cells, DCs, CD4 + T cells, and CD8 + T cells, among which CD4 + T cells play a critical role in this process. This article aims to summarize the functions and changes in various CD4 + T cell type counts and related cytokine levels in hepatic IRI and to review the possible mechanisms of mutual conversion between T cell types.

AREAS COVERED

We have covered the functions and changes that occur in Th1, Th17, and Treg cells in liver IRI, as well as the pathways and factors associated with them. We also discuss the prospects of clinical application and future directions for therapeutic advances.

EXPERT OPINION

This section explores the current clinical trials involving CD4 + T cells, especially Tregs, explains the limitations of their application, and summarizes the future development trends of cell engineering and their combination with the CAT technology. We also provide new ideas and therapeutic targets for alleviating liver IRI or other liver inflammatory diseases.

Activation of Transcription Factor 4 in Dendritic Cells Controls Th1/Th17 Responses and Autoimmune Neuroinflammation

Dendritic cells (DCs) are professional APCs that play a crucial role in initiating robust immune responses against invading pathogens while inducing regulatory responses to the body's tissues and commensal microorganisms. A breakdown of DC-mediated immunological tolerance leads to chronic inflammation and autoimmune disorders. However, cell-intrinsic molecular regulators that are critical for programming DCs to a regulatory state rather than to an inflammatory state are not known. In this study, we show that the activation of the TCF4 transcription factor in DCs is critical for controlling the magnitude of inflammatory responses and limiting neuroinflammation. DC-specific deletion of TCF4 in mice increased Th1/Th17 responses and exacerbated experimental autoimmune encephalomyelitis pathology. Mechanistically, loss of TCF4 in DCs led to heightened activation of p38 MAPK and increased levels of proinflammatory cytokines IL-6, IL-23, IL-1β, TNF-α, and IL-12p40. Consistent with these findings, pharmacological blocking of p38 MAPK activation delayed experimental autoimmune encephalomyelitis onset and diminished CNS pathology in TCF4^ΔDC mice. Thus, manipulation of the TCF4 pathway in DCs could provide novel opportunities for regulating chronic inflammation and represents a potential therapeutic approach to control autoimmune neuroinflammation.

Ischemia reperfusion injury induces pyroptosis and mediates injury in steatotic liver thorough Caspase 1 activation

A steatotic liver is increasingly vulnerable to ischemia reperfusion injury (IRI), and the underlying mechanisms are incompletely defined. Caspases are endo-proteases, which provide critical regulatory connections between cell death and inflammation. Caspase 1 is driven by inflammasomes which are key signaling platforms, that detect sterile stressors (DAMPs), releasing the highly pro-inflammatory cytokine interleukin IL-8 and IL-1β. To delineate the involvement of Caspase 1 and 11 in hepatocellular injury in steatotic liver undergoing IRI. Male C57BL6/Wild Type and Caspase 1^Null, Caspase 11^-/- and Caspase 1^-/-/11^-/- mice were fed a high fat diet (HFD) for 12 weeks. These mice were subjected to 40 min of ischemia followed by 2-24 h of reperfusion. Hepatocellular injury was assessed by histopathologic injury scoring, serum ALT and propidium iodide (PI) uptake, mRNA levels of Caspase 1, IL-1β by RT PCR, Caspase 1 activity assay and Caspase 1. Specific Caspase 1, inhibitor experiments were carried out. All groups gained similar body weight after a 12-week HFD. Cleaved Caspase 1 protein levels, Caspase 1 mRNA levels were significantly higher in steatotic liver undergoing IRI. Executor of pyroptosis cleaved GSDMD levels were higher in HFD fed mouse compared to lean. In addition, genetic deletion of Caspase 1, Casp1^Null mouse expressing Caspase-11 and Caspase 1/11 double knock out demonstrated significant reduction in serum ALT (p < 0.01), Injury Score, (p < 0.0002) but not in Caspase 11 alone. Caspase 1 is the driver of hepatocellular injury in a steatotic liver undergoing IRI, inhibition of which leads to hepatoprotection, thus providing a therapeutic target for clinical use.

PTEN-mediated AKT/β-catenin signaling enhances the proliferation and expansion of Lgr5+ hepatocytes

Rationale: Compelling evidence suggests that Lgr5+ hepatocytes repair liver damage by promoting the regeneration of hepatocytes and ductal cells in the case of liver injury. The PTEN-mediated AKT/β-catenin signaling plays a key role in the regulation of innate immune regulation in the liver. However, the signaling pathways that control Lgr5+ hepatocyte proliferation in the liver remain unclear.

Methods: In order to assess the involvement of PTEN-mediated AKT/β-catenin signaling in the expansion of Lgr5+ hepatocytes upon liver injuries, the Lgr5-CreER; Rosa-mTmG lineage tracing system was used to target Lgr5+ hepatocytes.

Results: The tracing of Lgr5+ hepatocytes showed that PTEN deletion and β-catenin activation significantly promoted the proliferation of Lgr5+ hepatocytes. In converse, the simultaneous inhibition of PTEN and β-catenin limited Lgr5+ hepatocyte proliferation in the liver. Our findings provide an insight into understanding how PTEN-mediated AKT/β-catenin signaling regulates the proliferation of Lgr5+ hepatocytes.

Conclusion: The outcomes can improve the application potential of Lgr5+ hepatocytes in the treatment of liver injury diseases and provide a new treatment option for liver cancer.

Decitabine Induces Change of Biological Traits in Myelodysplastic Syndromes via FOXO1 Activation

Decitabine (DAC) is considered to be a profound global DNA demethylation, which can induce the re-expression of silenced tumor suppressor genes. Little is known about the function of tumor suppressor gene FOXO1 in myelodysplastic syndromes (MDS). To address this issue, the study firstly investigated differentially expressed genes (DEGs) for DAC treatment in MDS cell lines, then explored the role of FOXO1 through silencing its expression before DAC treatment in MDS. The results showed that FOXO1 exists in a hyperphosphorylated, inactive form in MDS-L cells. DAC treatment both induces FOXO1 expression and reactivates the protein in its low phosphorylation level. Additionally, the results also demonstrated that this FOXO1 activation is responsible for the DAC-induced apoptosis, cell cycle arrest, antigen differentiation, and immunoregulation in MDS-L cells. We also demonstrated DAC-induced FOXO1 activation upregulates anti-tumor immune response in higher-risk MDS specimens. Collectively, these results suggest that DAC induces FOXO1 activation, which plays an important role in anti-MDS tumors.

Functional crosstalk between myeloid Foxo1-β-catenin axis and Hedgehog/Gli1 signaling in oxidative stress response

Foxo1 transcription factor is an evolutionarily conserved regulator of cell metabolism, oxidative stress, inflammation, and apoptosis. Activation of Hedgehog/Gli signaling is known to regulate cell growth, differentiation, and immune function. However, the molecular mechanisms by which interactive cell signaling networks restrain oxidative stress response and necroptosis are still poorly understood. Here, we report that myeloid-specific Foxo1 knockout (Foxo1^M-KO) mice were resistant to oxidative stress-induced hepatocellular damage with reduced macrophage/neutrophil infiltration, and proinflammatory mediators in liver ischemia/reperfusion injury (IRI). Foxo1^M-KO enhanced β-catenin-mediated Gli1/Snail activity, and reduced receptor-interacting protein kinase 3 (RIPK3) and NIMA-related kinase 7 (NEK7)/NLRP3 expression in IR-stressed livers. Disruption of Gli1 in Foxo1^M-KO livers deteriorated liver function, diminished Snail, and augmented RIPK3 and NEK7/NLRP3. Mechanistically, macrophage Foxo1 and β-catenin colocalized in the nucleus, whereby the Foxo1 competed with T-cell factor (TCF) for interaction with β-catenin under inflammatory conditions. Disruption of the Foxo1–β-catenin axis by Foxo1 deletion enhanced β-catenin/TCF binding, activated Gli1/Snail signaling, leading to inhibited RIPK3 and NEK7/NLRP3. Furthermore, macrophage Gli1 or Snail knockout activated RIPK3 and increased hepatocyte necroptosis, while macrophage RIPK3 ablation diminished NEK7/NLRP3-driven inflammatory response. Our findings underscore a novel molecular mechanism of the myeloid Foxo1–β-catenin axis in regulating Hedgehog/Gli1 function that is key in oxidative stress-induced liver inflammation and necroptosis.

Cigarette smoke extract induces airway epithelial cell death via repressing PRMT6/AKT signaling

Chronic obstructive pulmonary disease (COPD) is a severe public health threat world-wide. Cigarette smoke (CS)-induced airway epithelial cell death is a major pathway of pathogenesis in emphysema, a subtype of COPD. Protein arginine methyltransferase 6 (PRMT6) is a type I PRMT that catalyzes mono- and di-methylation on arginine residues within histone and non-histone proteins to modulate a variety of life processes, such as apoptosis. However, its role in CS-induced lung epithelial death has not been fully elucidated. Here we report that PRMT6 was decreased in mouse lung tissues from a cigarette smoke extract (CSE)-mediated experimental emphysematous model and in CSE treated or cigarette smoke exposed lung epithelial cells. Depletion of PRMT6 increased the protein levels of phosphatase PTEN and PI3K regulatory subunit p85 but decreased a downstream kinase PDK1, resulting in AKT dephosphorylation and thereafter, lung epithelial cell death. Knockout of PRMT6 inhibited epithelial survival and promoted CSE-mediated epithelial cell death, while ectopic expression of PRMT6 protein partially reversed epithelial cell death via PI3K/AKT-mediated cell survival signaling in CSE cellular models. These findings demonstrate that PRMT6 plays a crucial role in CS-induced bronchial epithelial cell death that may be a potential therapeutic target against the airway cell death in CS-induced COPD.

WNT/β-catenin signaling in the development of liver cancers

The WNT/β-catenin signaling pathway is a highly conserved and tightly controlled molecular mechanism that regulates embryonic development, cellular proliferation and differentiation. Of note, accumulating evidence has shown that the aberrant of WNT/β-catenin signaling promotes the development and/or progression of liver cancer, including hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), the two most prevalent primary liver tumours in adults. There are two different WNT signaling pathways have been identified, which were termed non-canonical and canonical pathways, the latter involving the activation of β-catenin. β-catenin, acting as an intracellular signal transducer in the WNT signaling pathway, is encoded by CTNNB1 and plays a critical role in tumorigenesis. In the past research, most liver tumors have mutations in genes encoding key components of the WNT/β-catenin signaling pathway. In addition, several of other signaling pathways also can crosswalk with β-catenin. In this review, we discuss the most relevant molecular mechanisms of action and regulation of WNT/β-catenin signaling in the development and pathophysiology of liver cancers, as well as in the development of therapeutics.

Agmatine Attenuates Liver Ischemia Reperfusion Injury by Activating Wnt/β-catenin Signaling in Mice

BACKGROUND

Liver ischemia reperfusion injury (LIRI) is a common problem during surgical procedures of the liver. It causes severe inflammatory responses and cell death, eventually leading to serious liver damage. Agmatine (AGM) is an endogenous polyamine with analgesic, anti-inflammatory, and antiapoptotic effects. However, it is still unknown whether AGM can protect the liver from damage caused by LIRI.

METHODS

For the in vivo experiments, a mouse model of partial warm hepatic ischemia reperfusion was established using C57BL/6J mice and then serum transaminase concentrations were analyzed. Histopathology was used to evaluate the degree of liver injury and quantitative real-time PCR was used to measure the amount of inflammatory cytokines. For the in vitro experiments, a cellular model of cobalt chloride (CoCl2)-induced hypoxia was established using AML12 cells. Flow cytometry was performed to measure the apoptosis levels. Western blotting analysis was conducted to measure the levels of proteins involved in apoptosis and Wnt/β-catenin signaling. We also chose 2 inhibitors of the Wnt/β-catenin signaling to elucidate the relationship between AGM and the Wnt/β-catenin signaling.

RESULTS

AGM showed protective effects against LIRI-induced liver damage, inflammatory responses, and cell apoptosis along with alleviation of CoCl2-induced hepatocyte injury. AGM activated the Wnt/β-catenin signaling pathway during LIRI and CoCl2-induced hepatocyte injury; however, when the Wnt/β-catenin pathway was inhibited, the protective effects of AGM declined.

CONCLUSIONS

AGM showed protective effects against LIRI by activating the Wnt/β-catenin signaling pathway.

MiR-17-5p inhibits cerebral hypoxia/reoxygenationinjury by targeting PTEN through regulation of PI3K/AKT/mTOR signaling pathway

OBJECTIVE

To investigate the role and mechanism of miR-17-5p in cerebral hypoxia/reoxygenation (H/R)-induced apoptosis.

METHODS

The present study used human brain microvascular endothelial cells (HBMVECs) to establish cerebral H/R model. MTT was used to measure the cell viability. Flow cytometry was used to detect the cell apoptosis. The interaction between miR-17-5p and PTEN was determined using dual luciferase reporter assay. RT-qPCR and Western blotting were used for determination of the expression of miR-17-5p, PTEN, apoptosis- and PI3K/AKT/mTOR signalling-related proteins.

RESULTS

The cell viability and the expression of miR-17-5p were obviously down-regulated while the expression of PTEN was obviously up-regulated in H/R cells. The cell viability was remarkably enhanced, and the cell apoptosis induced by H/R injury was dramatically reduced when miR-17-5p was overexpressed in HBMVECs under H/R condition, which was reversed by overexpression of PTEN. Dual luciferase reporter assay showed PTEN was a direct target of miR-17-5p. Treatment of PI3K inhibitor LY294002 significantly increased the apoptosis rate of HBMVECs, and this effect was significantly reversed by transfection of miR-17-5p mimics, while further dramatically enhanced by overexpression of PTEN.

CONCLUSION

MiR-17-5p could ameliorate cerebral I/R injury-induced cell apoptosis by directly targeting PTEN and regulation of PI3K/AKT/mTOR signalling.

β-catenin regulates myocardial ischemia/reperfusion injury following heterotopic heart transplantation in mice by modulating PTEN pathways

Ischemia reperfusion (I/R) injury, an inevitable event accompanying heart transplantation, is the primary factor leading to organ failure and graft rejection. In order to prevent I/R injury, we established murine heart transplantation model with I/R and cell culture system to determine whether β-catenin is a mediate factor in preventing I/R injury in heart transplantation. After successfully established heterotopic heart transplantation mice model, the I/R injury was induced, and two dynamic temporal were studied during different I/R phases. With the increase of ischemia and reperfusion time, heart damage was more severe. In the initial study, we observed that β-catenin was significantly decreased, while ROCK1 and PTEN increased during the perfusion phase from day 0 to day 1, and remain the same level until 3 days later. The similar pattern that β-catenin was down-regulated while ROCK1 and PTEN were up-regulated was also observed in the dynamic temporal ischemia study. To further investigate the role of β-catenin signaling in I/R injury in vitro, β-catenin over-expressing plasmid was transfected into HL-1 cells, a cardiac cell line. We noted that β-catenin over-expressing cardiomyocytes showed decreased ROCK1/PTEN expression both at mRNA and protein levels. In addition, cobalt dichloride (CoCl₂) -induced oxidative stress model was further established to mimic cardiac I/R injury. We observed that CoCl₂-induced activation of ROCK1/PTEN signaling pathway were attenuated by transient transfection of a β-catenin over-expressing plasmid. Taken together, our results suggest that cardiac transplant induced IR injury is closely associated with the down-regulation of β-catenin and up-regulation of ROCK1 and PTEN expression.

Protective Properties of FOXO1 Inhibition in a Murine Model of Non-alcoholic Fatty Liver Disease Are Associated With Attenuation of ER Stress and Necroptosis

Aim

The pathogenesis of non-alcoholic fatty liver disease is currently unclear, however, lipid accumulation leading to endoplasmic reticulum stress appears to be pivotal in the process. At present, FOXO1 is known to be involved in NAFLD progression. The relationship between necroptosis and non-alcoholic steatohepatitis has been of great research interest more recently. However, whether FOXO1 regulates ER stress and necroptosis in mice fed with a high fat diet is not clear. Therefore, in this study we analyzed the relationship between non-alcoholic steatohepatitis, ER stress, and necroptosis.

Main Methods

Male C57BL/6J mice were fed with an HFD for 14 weeks to induce non-alcoholic steatohepatitis. ER stress and activation of necroptosis in AML12 cells were evaluated after inhibition of FOXO1 in AML12 cells. In addition, mice were fed with AS1842856 for 14 weeks. Liver function and lipid accumulation were measured, and further, ER stress and necroptosis were evaluated by Western Blot and Transmission Electron Microscopy.

Key Findings

Mice fed with a high fat diet showed high levels of FOXO1, accompanying activation of endoplasmic reticulum stress and necroptosis. Further, sustained PA stimulation caused ER stress and necroptosis in AML12 cells. At the same time, protein levels of FOXO1 increased significantly. Inhibition of FOXO1 with AS1842856 alleviated ER stress and necroptosis. Additionally, treatment of mice with a FOXO1 inhibitor ameliorated liver function after they were fed with a high fat diet, displaying better liver condition and lighter necroptosis.

Significance

Inhibition of FOXO1 attenuates ER stress and necroptosis in a mouse model of non-alcoholic steatohepatitis.

Transcriptomic Analysis of Cellular Pathways in Healing Flexor Tendons of Plasminogen Activator Inhibitor 1 (PAI-1/Serpine1) Null Mice

Injuries to flexor tendons can be complicated by fibrotic adhesions, which severely impair the function of the hand. Plasminogen activator inhibitor 1 (PAI-1/SERPINE1), a master suppressor of fibrinolysis and protease activity, is associated with adhesions. Here, we used next-generation RNA sequencing (RNA-Seq) to assess genome-wide differences in messenger RNA expression due to PAI-1 deficiency after zone II flexor tendon injury. We used the ingenuity pathway analysis to characterize molecular pathways and biological drivers associated with differentially expressed genes (DEG). Analysis of hundreds of overlapping and DEG in PAI-1 knockout (KO) and wild-type mice (C57Bl/6J) during tendon healing revealed common and distinct biological processes. Pathway analysis identified cell proliferation, survival, and senescence, as well as chronic inflammation as potential drivers of fibrotic healing and adhesions in injured tendons. Importantly, we identified the activation of PTEN signaling and the inhibition of FOXO1-associated biological processes as unique transcriptional signatures of the healing tendon in the PAI-1/Serpine1 KO mice. Further, transcriptomic differences due to the genetic deletion of PAI-1 were mechanistically linked to PI3K/Akt/mTOR, PKC, and MAPK signaling cascades. These transcriptional observations provide novel insights into the biological roles of PAI-1 in tendon healing and could identify therapeutic targets to achieve scar-free regenerative healing of tendons. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:43-58, 2020.

Hepatitis B virus-triggered PTEN/β-catenin/c-Myc signaling enhances PD-L1 expression to promote immune evasion

Hepatitis B virus (HBV) exploits multiple strategies to evade host immune surveillance. Programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) signaling plays a critical role in regulating T cell homeostasis. However, it remains largely unknown as to how HBV infection elevates PD-L1 expression in hepatocytes. A mouse model of HBV infection was established by hydrodynamic injection with a vector containing 1.3-fold overlength HBV genome (pHBV1.3) via the tail vein. Coculture experiments with HBV-expressing hepatoma cells and Jurkat T cells were established in vitro. We observed significant decrease in the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and increase in β-catenin/PD-L1 expression in liver tissues from patients with chronic hepatitis B and mice subjected to pHBV1.3 hydrodynamic injection. Mechanistically, decrease in PTEN enhanced β-catenin/c-Myc signaling and PD-L1 expression in HBV-expressing hepatoma cells, which in turn augmented PD-1 expression, lowered IL-2 secretion, and induced T cell apoptosis. However, β-catenin disruption inhibited PTEN-mediated PD-L1 expression, which was accompanied by decreased PD-1 expression, and increased IL-2 production in T cells. Luciferase reporter assays revealed that c-Myc stimulated transcriptional activity of PD-L1. In addition, HBV X protein (HBx) and HBV polymerase (HBp) contributed to PTEN downregulation and β-catenin/PD-L1 upregulation. Strikingly, PTEN overexpression in hepatocytes inhibited β-catenin/PD-L1 signaling and promoted HBV clearance in vivo. Our findings suggest that HBV-triggered PTEN/β-catenin/c-Myc signaling via HBx and HBp enhances PD-L1 expression, leading to inhibition of T cell response, and promotes HBV immune evasion.NEW & NOTEWORTHY This study demonstrates that during HBV infection, HBV can increase PD-L1 expression via PTEN/β-catenin/c-Myc signaling pathway, which in turn inhibits T cell response and ultimately promotes HBV immune evasion. Targeting this signaling pathway is a potential strategy for immunotherapy of chronic hepatitis B.

Protective Role of mTOR in Liver Ischemia/Reperfusion Injury: Involvement of Inflammation and Autophagy

Liver ischemia/reperfusion (IR) injury is a common phenomenon after liver resection and transplantation, which often results in liver graft dysfunction such as delayed graft function and primary nonfunction. The mammalian target of rapamycin (mTOR) is an evolutionarily highly conserved serine/threonine protein kinase, which coordinates cell growth and metabolism through sensing environmental inputs under physiological or pathological conditions, involved in the pathophysiological process of IR injury. In this review, we mainly present current evidence of the beneficial role of mTOR in modulating inflammation and autophagy under liver IR to provide some evidence for the potential therapies for liver IR injury.

Acetyl-3-Aminoethyl Salicylate Ameliorates Hepatic Ischemia/Reperfusion Injury and Liver Graft Survival Through a High-Mobility Group Box 1/Toll-Like Receptor 4-Dependent Mechanism

In liver transplant cases, severe hepatic ischemia/reperfusion injury (HIRI) is a strong predictor of adverse liver graft and overall outcomes. During HIRI, high-mobility group box 1 (HMGB1) promotes hepatocellular death and proinflammatory cytokine secretion by toll-like receptor 4 (TLR4). Because salicylates inhibit HMGB1/TLR4 interaction, we hypothesized that salicylates may ameliorate HIRI-induced liver damage by inhibiting HMGB1/TLR4 axis activation. Using a murine model of HIRI, we found that the salicylate acetyl-3-aminoethyl salicylic acid (ac3AESA) reduced serum alanine aminotransferase and aspartate aminotransferase as well as Suzuki scores and apoptotic cell counts after HIRI. Ac3AESA also down-regulated hepatocellular HMGB1 and TLR4 expression, phosphorylated inhibitor of κBα, extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, cleaved caspase 3, and cleaved caspase 1 levels after HIRI. Ac3AESA reduced liver Kupffer cell transcription of proinflammatory mediators tumor necrosis factor α (TNF-α), interleukin (IL) 6, IL1β, chemokine (C-X-C motif) ligand (CXCL) 1, CXCL2, and CXCL8 after HIRI. Ac3AESA also dose-dependently reduced in vitro release of Kupffer cell TNF-α. Employing a murine orthotopic liver transplantation model, we found daily ac3AESA administration up to day 10 after transplant improved liver graft survival, suppressed allograft damage, and down-regulated HMGB1/TLR4 signaling. These benefits to survival and allograft health were maintained for cold ischemia times of 12 and 18 hours. Notably, TLR4 knockout eliminated all foregoing ac3AESA-induced effects. In conclusion, ac3AESA partially rescues the negative effects of HIRI and prolongs liver graft survival in a TLR4-dependent manner.

The Modulation of Regulatory T Cells via HMGB1/PTEN/β-Catenin Axis in LPS Induced Acute Lung Injury

Sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) remains the leading complication for mortality caused by bacterial infection. The regulatory T (Treg) cells appear to be an important modulator in resolving lung injury. Despite the extensive studies, little is known about the role of macrophage HMGB1/PTEN/β-catenin signaling in Treg development during ALI.

Objectives: This study was designed to determine the roles and molecular mechanisms of HMGB1/PTEN/β-catenin signaling in mediating CD4⁺CD25⁺Foxp3⁺ Treg development in sepsis-induced lung injury in mice.

Setting: University laboratory research of First Affiliated Hospital of Anhui Medical University.

Subjects: PTEN/β-catenin Loxp and myeloid-specific knockout mice.

Interventions: Groups of PTEN^loxp/β-catenin^loxp and myeloid-specific PTEN/β-catenin knockout (PTEN^M−KO/β-catenin^M−KO) mice were treated with LPS or recombinant HMGB1 (rHMGB1) to induce ALI. The effects of HMGB1-PTEN axis were further analyzed by in vitro co-cultures.

Measures and Main Results: In a mouse model of ALI, blocking HMGB1 or myeloid-specific PTEN knockout (PTEN^M−KO) increased animal survival/body weight, reduced lung damage, increased TGF-β production, inhibited the expression of RORγt and IL-17, while promoting β-catenin signaling and increasing CD4⁺CD25⁺Foxp3⁺ Tregs in LPS- or rHMGB-induced lung injury. Notably, myeloid-specific β-catenin ablation (β-catenin^M−KO) resulted in reduced animal survival and increased lung injury, accompanied by reduced CD4⁺CD25⁺Foxp3⁺ Tregs in rHMGB-induced ALI. Furthermore, disruption of macrophage HMGB1/PTEN or activation of β-catenin significantly increased CD4⁺CD25⁺Foxp3⁺ Tregs in vitro.

Conclusions: HMGB1/PTEN/β-catenin signaling is a novel pathway that regulates Treg development and provides a potential therapeutic target in sepsis-induced lung injury.

PTEN expression by an oncolytic herpesvirus directs T-cell mediated tumor clearance

Engineered oncolytic viruses are used clinically to destroy cancer cells and have the ability to boost anticancer immunity. Phosphatase and tensin homolog deleted on chromosome 10 loss is common across a broad range of malignancies, and is implicated in immune escape. The N-terminally extended isoform, phosphatase and tensin homolog deleted on chromosome 10 alpha (PTENα), regulates cellular functions including protein kinase B signaling and mitochondrial adenosine triphosphate production. Here we constructed HSV-P10, a replicating, PTENα expressing oncolytic herpesvirus, and demonstrate that it inhibits PI3K/AKT signaling, increases cellular adenosine triphosphate secretion, and reduces programmed death-ligand 1 expression in infected tumor cells, thus priming an adaptive immune response and overcoming tumor immune escape. A single dose of HSV-P10 resulted in long term survivors in mice bearing intracranial tumors, priming anticancer T-cell immunity leading to tumor rejection. This implicates HSV-P10 as an oncolytic and immune stimulating therapeutic for anticancer therapy.

Oncolytic viruses are a promising therapeutic approach for cancer treatment. The authors demonstrate the efficacy of an engineered HSV-1 expressing PTENα as an oncolytic and immune stimulating therapy against brain cancer metastases.

Artesunate may inhibit liver fibrosis via the FAK/Akt/β-catenin pathway in LX-2 cells

BACKGROUND

An increasing number of studies are investigating the effects of Chinese medicine on hepatic fibrosis, but only few studies have examined the anti-fibrogenic properties of Artesunate (ART). The aim of the present study was to explore the anti-fibrotic effects of ART on LX-2 cells, the human HSC cell line, and to determine potential molecular mechanisms via the focal adhesion kinase (FAK)/ protein kinase B (Akt)/ β-catenin pathway.

METHODS

LX-2 cells were stimulated with different concentration of ART (0, 12.5, 25 and 50 μg/ml) for 12, 24, 48 or 72 h, their proliferation was analyzed using the Cell Counting Kit-8 (CCK-8) assay. LX-2 cells were treated with different doses of ART (0, 12.5, 25 and 50 μg/ml) for 24 h, their apoptosis was measured using flow cytometry, the levels of mRNAs encoding collagen I or α-smooth muscle actin (α-SMA) were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and the levels of key proteins in the FAK/Akt/β-catenin signaling pathway were assessed by western blotting. Specific inhibitors of FAK were added to the LX-2 cells cultures to explore the potential signaling.

RESULTS

Exposing LX-2 cells to ART efficiently inhibited their proliferation, significantly promoted early apoptosis in a dose-dependent manner, and markedly downregulated the mRNA expression of α-SMA and collagen I. In addition, ART, similar to FAK inhibitor PF562271 significantly inhibited the FAK/Akt/β-catenin signaling pathway by reducing the levels of phosphorylated FAK, Akt and GSK-3β.

CONCLUSIONS

Our present study shows that ART could regulate the proliferation, apoptosis and activation of LX-2. Meanwhile, the anti-fibrogenic mechanisms of ART was correlated with FAK/Akt/β-catenin pathway. Future research should verify and extend these findings, as well as explore other molecules and therefore serve as useful therapeutic targets.

ATRA Regulates Innate Immunity in Liver Ischemia/Reperfusion Injury via RARα/Akt/Foxo1 Signaling

All-trans retinoic acid (ATRA) has been proved to protect liver from ischemia/reperfusion (IR) injury, however, its mechanism is still unclear. This study is to investigate the mechanism of effect of ATRA on innate immunity in mice liver IR injury. Before operation, mice were gavaged by ATRA at 15 mg/kg/d for two weeks, and then the liver was underwent 70% ischemia (90 min) and reperfusion (6 h). Liver function was assessed by serum alanine aminotransferase (sALT), serum aspartate aminotransferase (sAST). Real-time PCR and Western blot were to detect the level of mRNA and protein. In vitro, RAW264.7 macrophages were treatment with ATRA (1 µM) or LE540 (5 µM, a retinoic acid receptor α (RARα) receptor antagonist) before lipopolysaccharide (100 ng/mL) stimulation. In vivo, ATRA protected the liver from IR injury by improving hepatocellular function (sALT and sAST), decreasing cell apoptosis and inhibiting inflammatory response (i.e., the level of toll-like receptor 4, transcription factor nuclear factor-κBp65, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α). When RARα was blocked by LE540 in RAW264.7 macrophages, the inflammatory cytokines were enhancing, along with a decline of Akt phosphorylation but Forkhead box o (Foxo) 1, compared with the ATRA group. In summary, ATRA regulates in part the innate immunity to protect liver from IR injury by RARα/Akt/Foxo1 pathway.

p47phox-Dependent Reactive Oxygen Species Stimulate Nuclear Translocation of the FoxO1 Transcription Factor During Metabolic Inhibition in Cardiomyoblasts

Reactive oxygen species (ROS) control forkhead box O (FOXO) transcription factor activity by influencing their nuclear translocation. However, knowledge of the ROS cellular source(s) involved herein remains scarce. Recently, we have shown p47^phox-dependent activation of ROS-producing NADPH oxidase (NOX) at the nuclear pore in H9c2 rat cardiomyoblasts in response to ischemia. This localizes NOX perfectly to affect protein nuclear translocation, including that of transcription factors. In the current study, involvement of p47^phox-dependent production of ROS in the nuclear translocation of FOXO1 was analyzed in H9c2 cells following 4 h of metabolic inhibition (MI), which mimics the effects of ischemia. Nuclear translocation of FOXO1 was determined by quantitative digital-imaging fluorescence and western blot analysis. Subsequently, the effect of inhibiting p47^phox-dependent ROS production by short hairpin RNA (shRNA) transfection on FOXO1 translocation was analyzed by digital-imaging microscopy. MI induced a significant translocation of FOXO1 into the nucleus. Transfection with p47^phox-shRNA successfully knocked-down p47^phox expression, reduced nuclear nitrotyrosine production, an indirect marker for ROS production, and inhibited the nuclear translocation of FOXO1 following MI. With these results, we show for the first time that nuclear import of FOXO1 induced by MI in H9c2 depends critically on p47^phox-mediated ROS production.

Nuclear PTEN enhances the maturation of a microRNA regulon to limit MyD88-dependent susceptibility to sepsis

Sepsis-induced organ damage is caused by systemic inflammatory response syndrome (SIRS), which results in substantial comorbidities. Therefore, it is of medical importance to identify molecular brakes that can be exploited to dampen inflammation and prevent the development of SIRS. We investigated the role of phosphatase and tensin homolog (PTEN) in suppressing SIRS, increasing microbial clearance, and preventing lung damage. Septic patients and mice with sepsis exhibited increased PTEN expression in leukocytes. Myeloid-specific Pten deletion in an animal model of sepsis increased bacterial loads and cytokine production, which depended on enhanced myeloid differentiation primary response gene 88 (MyD88) abundance and resulted in mortality. PTEN-mediated induction of the microRNAs (miRNAs) miR125b and miR203b reduced the abundance of MyD88. Loss- and gain-of-function assays demonstrated that PTEN induced miRNA production by associating with and facilitating the nuclear localization of Drosha-Dgcr8, part of the miRNA-processing complex. Reconstitution of PTEN-deficient mouse embryonic fibroblasts with a mutant form of PTEN that does not localize to the nucleus resulted in retention of Drosha-Dgcr8 in the cytoplasm and impaired production of mature miRNAs. Thus, we identified a regulatory pathway involving nuclear PTEN-mediated miRNA generation that limits the production of MyD88 and thereby limits sepsis-associated mortality.

Novel Targets for Treating Ischemia-Reperfusion Injury in the Liver

Liver ischemia-reperfusion injury (IRI) is a major complication of hemorrhagic shock, liver transplantation, and other liver surgeries. It is one of the leading causes for post-surgery hepatic dysfunction, always leading to morbidity and mortality. Several strategies, such as low-temperature reperfusion and ischemic preconditioning, are useful for ameliorating liver IRI in animal models. However, these methods are difficult to perform in clinical surgeries. It has been reported that the activation of peroxisome proliferator activated receptor gamma (PPARγ) protects the liver against IRI, but with unidentified direct target gene(s) and unclear mechanism(s). Recently, FAM3A, a direct target gene of PPARγ, had been shown to mediate PPARγ’s protective effects in liver IRI. Moreover, noncoding RNAs, including LncRNAs and miRNAs, had also been reported to play important roles in the process of hepatic IRI. This review briefly discussed the roles and mechanisms of several classes of important molecules, including PPARγ, FAM3A, miRNAs, and LncRNAs, in liver IRI. In particular, oral administration of PPARγ agonists before liver surgery or liver transplantation to activate hepatic FAM3A pathways holds great promise for attenuating human liver IRI.

FAM3A mediates PPARγ's protection in liver ischemia-reperfusion injury by activating Akt survival pathway and repressing inflammation and oxidative stress

FAM3A is a novel mitochondrial protein, and its biological function remains largely unknown. This study determined the role and mechanism of FAM3A in liver ischemia-reperfusion injury (IRI). In mouse liver after IRI, FAM3A expression was increased. FAM3A-deficient mice exhibited exaggerated liver damage with increased serum levels of AST, ALT, MPO, MDA and oxidative stress when compared with WT mice after liver IRI. FAM3A-deficient mouse livers had a decrease in ATP content, Akt activity and anti-apoptotic protein expression with an increase in apoptotic protein expression, inflammation and oxidative stress when compared WT mouse livers after IRI. Rosiglitazone pretreatment protected against liver IRI in wild type mice but not in FAM3A-deficient mice. In cultured hepatocytes, FAM3A overexpression protected against, whereas FAM3A deficiency exaggerated oxidative stress-induced cell death. FAM3A upregulation or FAM3A overexpression inhibited hypoxia/reoxygenation-induced activation of apoptotic gene and hepatocyte death in P2 receptor-dependent manner. FAM3A deficiency blunted rosiglitazone's beneficial effects on Akt activation and cell survival in cultured hepatocytes. Collectively, FAM3A protects against liver IRI by activating Akt survival pathways, repressing inflammation and attenuating oxidative stress. Moreover, the protective effects of PPARγ agonist(s) on liver IRI are dependent on FAM3A-ATP-Akt pathway.

The first case of ischemia-free organ transplantation in humans: A proof of concept

Ischemia and reperfusion injury (IRI) is an inevitable event in conventional organ transplant procedure and is associated with significant mortality and morbidity post-transplantation. We hypothesize that IRI is avoidable if the blood supply for the organ is not stopped, thus resulting in optimal transplant outcomes. Here we described the first case of a novel procedure called ischemia-free organ transplantation (IFOT) for patients with end-stage liver disease. The liver graft with severe macrovesicular steatosis was donated from a 25-year-old man. The recipient was a 51-year-old man with decompensated liver cirrhosis and hepatocellular carcinoma. The graft was procured, preserved, and implanted under continuous normothermic machine perfusion. The recipient did not suffer post-reperfusion syndrome or vasoplegia after revascularization of the allograft. The liver function test and histological study revealed minimal hepatocyte, biliary epithelium and vascular endothelium injury during preservation and post-transplantation. The inflammatory cytokine levels were much lower in IFOT than those in conventional procedure. Key pathways involved in IRI were not activated after allograft revascularization. No rejection, or vascular or biliary complications occurred. The patient was discharged on day 18 post-transplantation. This marks the first case of IFOT in humans, offering opportunities to optimize transplant outcomes and maximize donor organ utilization.

Macrophage heme oxygenase-1-SIRT1-p53 axis regulates sterile inflammation in liver ischemia-reperfusion injury

BACKGROUND & AIMS

Hepatic ischemia-reperfusion injury (IRI), characterized by exogenous antigen-independent local inflammation and hepatocellular death, represents a risk factor for acute and chronic rejection in liver transplantation. We aimed to investigate the molecular communication involved in the mechanism of liver IRI.

METHODS

We analyzed human liver transplants, primary murine macrophage cell cultures and IR-stressed livers in myeloid-specific heme oxygenase-1 (HO-1) gene mutant mice, for anti-inflammatory and cytoprotective functions of macrophage-specific HO-1/SIRT1 (sirtuin 1)/p53 (tumor suppressor protein) signaling.

RESULTS

Decreased HO-1 expression in human post-reperfusion liver transplant biopsies correlated with a deterioration in hepatocellular function (serum ALT; p<0.05) and inferior patient survival (p<0.05). In the low HO-1 liver transplant biopsy group, SIRT1/Arf (alternative reading frame)/p53/MDM2 (murine double minute 2) expression levels decreased (p<0.05) while cleaved caspase 3 and frequency of TUNEL+cells simultaneously increased (p<0.05). Immunofluorescence showed macrophages were the principal source of HO-1 in human and mouse IR-stressed livers. In vitro macrophage cultures revealed that HO-1 induction positively regulated SIRT1 signaling, whereas SIRT1-induced Arf inhibited ubiquitinating activity of MDM2 against p53, which in turn attenuated macrophage activation. In a murine model of hepatic warm IRI, myeloid-specific HO-1 deletion lacked SIRT1/p53, exacerbated liver inflammation and IR-hepatocellular death, whereas adjunctive SIRT1 activation restored p53 signaling and rescued livers from IR-damage.

CONCLUSION

This bench-to-bedside study identifies a new class of macrophages activated via the HO-1-SIRT1-p53 signaling axis in the mechanism of hepatic sterile inflammation. This mechanism could be a target for novel therapeutic strategies in liver transplant recipients.

LAY SUMMARY

Post-transplant low macrophage HO-1 expression in human liver transplants correlates with reduced hepatocellular function and survival. HO-1 regulates macrophage activation via the SIRT1-p53 signaling network and regulates hepatocellular death in liver ischemia-reperfusion injury. Thus targeting this pathway in liver transplant recipients could be of therapeutic benefit.

Proinflammatory cytokines correlate with early exercise attenuating anxiety-like behavior after cerebral ischemia

Background and Objective

Stroke may cause neuropsychiatric problems, which have negative effects on cognitive functions and behavior. Exercise plays an important role in reducing the occurrence and development of stroke, the concrete mechanism is not fully clarified. In this study, we attempted to determine whether early treadmill exercise attenuates anxiety-like behavior by regulation of inflammation after brain ischemia.

Method

We subjected adult male rats to middle cerebral artery occlusion (MCAO) for 90 min and trained rats started to run on a treadmill from postoperative day 1 to day 14. The effects of treadmill on cognitive functions, anxiety-like behavior, and immune activation were analyzed by Morris water maze test, open field test, elevated plus maze test, and enzyme-linked immunosorbent assay.

Results

Early treadmill exercise significantly improved cognitive function, alleviated anxiety-like behavior in ischemic rats model; this improvement was associated with significantly decreased activation of astrocytes and microglia cells and proinflammatory markers (platelet-activating factor [PAF], interleukin-6 [IL-6], tumor necrosis factor-alpha [TNF-α], intercellular adhesion molecule-1 [ICAM-1], and vascular cell adhesion molecule-1 [VCAM-1]).

Conclusion

Our results indicated that early treadmill exercise attenuated anxiety-like behavior by decreasing inflammation response, exercise conferred a great benefit of attenuating anxiety-like behavior via anti-inflammatory treatment may prove to be a novel neuroprotective strategy for stroke.

PTEN Down-Regulation Promotes β-Oxidation to Fuel Hypertrophic Liver Growth After Hepatectomy in Mice

In regenerating liver, hepatocytes accumulate lipids before the major wave of parenchymal growth. This transient, regeneration-associated steatosis (TRAS) is required for liver recovery, but its purpose is unclear. The tumor suppressor phosphatase and tensin homolog (PTEN) is a key inhibitor of the protein kinase B/mammalian target of rapamycin axis that regulates growth and metabolic adaptations after hepatectomy. In quiescent liver, PTEN causes pathological steatosis when lost, whereas its role in regenerating liver remains unknown. Here, we show that PTEN down-regulation promotes liver growth in a TRAS-dependent way. In wild-type mice, PTEN reduction occurred after TRAS formation, persisted during its disappearance, and correlated with up-regulated β-oxidation at the expense of lipogenesis. Pharmacological modulation revealed an association of PTEN with TRAS turnover and hypertrophic liver growth. In liver-specific Pten^-/- mice shortly after induction of knockout, hypertrophic regeneration was accelerated and led to hepatomegaly. The resulting surplus liver mass was functional, as demonstrated by raised survival in a lethal model of resection-induced liver failure. Indirect calorimetry revealed lipid oxidation as the primary energy source early after hepatectomy. The shift from glucose to lipid usage was pronounced in Pten^-/- mice and correlated with the disappearance of TRAS. Partial inhibition of β-oxidation led to persisting TRAS in Pten^-/- mice and abrogated hypertrophic liver growth. PTEN down-regulation may promote β-oxidation through β-catenin, whereas hypertrophy was dependent on mammalian target of rapamycin complex 1.

CONCLUSION

PTEN down-regulation after hepatectomy promotes the burning of TRAS-derived lipids to fuel hypertrophic liver regeneration. Therefore, the anabolic function of PTEN deficiency in resting liver is transformed into catabolic activities upon tissue loss. These findings portray PTEN as a node coordinating liver growth with its energy demands and emphasize the need of lipids for regeneration. (Hepatology 2017;66:908-921).

The functions of tumor suppressor PTEN in innate and adaptive immunity

The tumor suppressor phosphatase and tensin homolog (PTEN) is a lipid and protein phosphatase that is able to antagonize the PI3K/AKT pathway and inhibit tumor growth. PTEN also possesses phosphatase-independent functions. Genetic alterations of PTEN may lead to the deregulation of cell proliferation, survival, differentiation, energy metabolism and cellular architecture and mobility. Although the role of PTEN in tumor suppression is extensively documented and well established, the evidence for its roles in immunity did not start to accumulate until recently. In this review, we will focus on the newly discovered functions of PTEN in the regulation of innate and adaptive immunity, including antiviral responses.