Partial Inhibition of HO-1 Attenuates HMP-Induced Hepatic Regeneration against Liver Injury in Rats

Haeme Oxygenas-1-Induced Liver Regeneration Protects Graft Against Small-for-Size Syndrome in Rats

BACKGROUND

Haeme oxygenase (HO-1) affords protection against ischemia/reperfusion (I/R) injury; however, its effects on liver regeneration remain poorly explored. Our previous studies have shown that HO-1 is probably involved in liver regeneration, but its role in small-for-size syndrome (SFSS) is still unclear. Therefore, this study aims to investigate the effects of HO-1 on small-for-size graft (SFSG) and the underlying mechanism.

METHODS

Knockout of HO-1 rats by TALEN technique. Immunohistochemistry was used to detect HO-1 nuclear translocation. Haeme oxygenase activity was measured by detecting the amount of carbon monoxide (CO) generated from cell lysates. Flow cytometry was used to detect cell apoptosis and cell cycle. Western blot were performed to measure the expression level of HO-1 protein.

RESULTS

We identified that HO-1 was involved in SFSG regeneration; HO-1-knockout rats demonstrated significantly decreased liver proliferation and recovery. Interestingly, our results showed HO-1-induced SFSG regeneration was more likely to be the primary protector against SFSS than IRI. Furthermore, we verified the nuclear translocation of HO-1 and its protective effect on hypoxia/reoxygenation (H/R) damage in clone9 cells. Our results indicated that the HO-1 protein itself rather than heme breakdown metabolites might play a key role in liver regeneration.

CONCLUSIONS

The HO-1 protein itself rather than its metabolites possess a protective effect on small-for-size graft (SFSG) against SFSS via nuclear translocation.

HO-1 attenuates testicular ischaemia/reperfusion injury by activating the phosphorylated C-jun-miR-221/222-TOX pathway

Aims

Heme oxygenase (HO-1) affords protection against ischaemia/reperfusion (I/R) injury; however, its effects on testicular I/R injury remain poorly explored. Herein, we aimed to examine the effects of HO-1 on testicular I/R injury and elucidate the underlying mechanism.

Methods

Using the TALEN technique, we knocked out the HO-1 gene from rats. In vivo: Thirty hmox+/+ and 30 hmox-/- rats were randomly assigned to six groups: sham-operated (sham), I/R (the left testicle torsion/detorsion) 0 d,I/R 1d, I/R 3d, I/R 7d and I/R 28d. In vitro: GC-1 were suffered from: control,H/R (oxygen-deprivation/reoxygenation),H/R + HO-1 siRNA,H/R + c-Jun siRNA or H/R + HO-1 siRNA + c-jun.We performed immunofluorescence and immunohistochemistry experiments to detect HO-1 nuclear translocation. Flow cytometry was used to detect cell apoptosis and analyse the cell cycle. High-resolution miRNA, mRNA sequencing, reverse transcription-quantitative PCR, and western blotting were performed to identify testicular I/R injury-related genes strongly conserved in HO-1 knockout rats. A double luciferase reporter assay was performed to verify the relationship between C-jun and miR-221/222.

Main findings

In vivo, HO-1 improved the pathological damage induced by testicular I/R. In GC-1 cells, we confirmed the nuclear translocation of HO-1 and its protective effect against hypoxia/reoxygenation (H/R) damage. Accordingly, HO-1 protein itself, rather than heme metabolites, might play a key role in testicular I/R. Gene sequencing was performed to screen for miR221/222 and its downstream gene, thymocyte selection-associated high mobility group box (TOX). HO-1 increased c-Jun phosphorylation in the H/R group, knocked down c-Jun in GC-1 cells, and decreased miR-221/222 expression. Inhibition of HO-1 expression decreased the expression of c-Jun and miR-221/222, which was rescued by adding c-Jun. Dual-luciferase reporter assay confirmed the interaction between c-Jun and miR-221/222.

Conclusions

HO-1 could exert a protective effect against testicular I/R via the phosphorylated c-Jun-miR-221/222-TOX pathway.

The role of ischaemia-reperfusion injury and liver regeneration in hepatic tumour recurrence

The risk of cancer recurrence after liver surgery mainly depends on tumour biology, but preclinical and clinical evidence suggests that the degree of perioperative liver injury plays a role in creating a favourable microenvironment for tumour cell engraftment or proliferation of dormant micro-metastases. Understanding the contribution of perioperative liver injury to tumour recurrence is imperative, as these pathways are potentially actionable. In this review, we examine the key mechanisms of perioperative liver injury, which comprise mechanical handling and surgical stress, ischaemia-reperfusion injury, and parenchymal loss leading to liver regeneration. We explore how these processes can trigger downstream cascades leading to the activation of the immune system and the pro-inflammatory response, cellular proliferation, angiogenesis, anti-apoptotic signals, and release of circulating tumour cells. Finally, we discuss the novel therapies under investigation to decrease ischaemia-reperfusion injury and increase regeneration after liver surgery, including pharmaceutical agents, inflow modulation, and machine perfusion.

Association between Hepatocellular Carcinoma Recurrence and Graft Size in Living Donor Liver Transplantation: A Systematic Review

The aim of this work was to assess the association between graft-to-recipient weight ratio (GRWR) in adult-to-adult living donor liver transplantation (LDLT) and hepatocellular carcinoma (HCC) recurrence. A search of the MEDLINE and EMBASE databases was performed until December 2022 for studies comparing different GRWRs in the prognosis of HCC recipients in LDLT. Data were pooled to evaluate 1- and 3-year survival rates. We identified three studies, including a total of 782 patients (168 GRWR < 0.8 vs. 614 GRWR ≥ 0.8%). The pooled overall survival was 85% and 77% at one year and 90% and 83% at three years for GRWR < 0.8 and GRWR ≥ 0.8, respectively. The largest series found that, in patients within Milan criteria, the GRWR was not associated with lower oncological outcomes. However, patients with HCC outside the Milan criteria with a GRWR < 0.8% had lower survival and higher tumor recurrence rates. The GRWR < 0.8% appears to be associated with lower survival rates in HCC recipients, particularly for candidates with tumors outside established HCC criteria. Although the data are scarce, the results of this study suggest that considering the individual GRWR not only as risk factor for small-for-size-syndrome but also as contributor to HCC recurrence in patients undergoing LDLT would be beneficial. Novel perfusion technologies and pharmacological interventions may contribute to improving outcomes.

Hypothermic Oxygenated Machine Perfusion Promotes Mitophagy Flux against Hypoxia-Ischemic Injury in Rat DCD Liver

Hypothermic oxygenated machine perfusion (HOPE) can enhance organ preservation and protect mitochondria from hypoxia-ischemic injury; however, an understanding of the underlying HOPE mechanism that protects mitochondria is somewhat lacking. We hypothesized that mitophagy may play an important role in HOPE mitochondria protection. Experimental rat liver grafts were exposed to 30 min of in situ warm ischemia. Then, grafts were procured, followed by cold storage for 3 or 4 h to mimic the conventional preservation and transportation time in donation after circulatory death (DCD) in clinical contexts. Next, the grafts underwent hypothermic machine perfusion (HMP) or HOPE for 1 h through portal vein only perfusion. The HOPE-treated group showed a better preservation capacity compared with cold storage and HMP, preventing hepatocyte damage, nuclear injury, and cell death. HOPE can increase mitophagy marker expression, promote mitophagy flux via the PINK1/Parkin pathway to maintain mitochondrial function, and reduce oxygen free radical generation, while the inhibition of autophagy by 3-methyladenine and chloroquine could reverse the protective effect. HOPE-treated DCD liver also demonstrated more changes in the expression of genes responsible for bile metabolism, mitochondrial dynamics, cell survival, and oxidative stress. Overall, HOPE attenuates hypoxia-ischemic injury in DCD liver by promoting mitophagy flux to maintain mitochondrial function and protect hepatocytes. Mitophagy could pave the way for a protective approach against hypoxia-ischemic injury in DCD liver.

Specnuezhenide reduces carbon tetrachloride-induced liver injury in mice through inhibition of oxidative stress and hepatocyte apoptosis

OBJECTIVES

This study aimed to investigate the hepatoprotective effects of specnuezhenide against carbon tetrachloride (CCl4)-induced liver injury in mice.

METHODS

Male C57BL/6 mice were intraperitoneally injected with 10 ml/kg body weight of CCl4 (0.5% diluted in arachis oil) for acute liver injury after oral administration of specnuezhenide for 7 days. Twenty-four hours after the final CCl4 injection, mice were euthanized and plasma and liver samples were collected.

KEY FINDINGS

The results showed that specnuezhenide markedly and dose-dependently reduced serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) activity and relative liver weight, as well as ameliorated histopathological damage caused by CCl4 and decreased malondialdehyde (MDA) levels, and increased the activity of antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Moreover, specnuezhenide promoted the expression and nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2) and increased the mRNA and protein expression of Nrf2 signalling-related genes heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC) and NAD(P)H:quinone oxidoreductase 1 (NQO1). Finally, TUNEL staining and immunohistochemistry indicated that specnuezhenide prevented CCl4-induced hepatocytic apoptosis by up-regulating B-cell lymphoma 2 (Bcl-2) expression and downregulating Bcl-2-associated X (Bax) expression.

CONCLUSIONS

Specnuezhenide reduced CCl4-induced liver injury in mice by inhibiting oxidative stress via activation of Nrf2 signalling and decreasing hepatocyte apoptosis.

HO-1 Protects Remnant Liver against Dysfunction after Major Hepatectomy in Humans

OBJECTIVE

During major resection of liver carcinoma, liver regeneration (LR) is induced by various clinical and biological factors. Heme oxygenase (HO)-1 has been found as a key inducer of LR in preclinical trial. The clinical evidence for the role of HO-1 in liver dysfunction (LD) including LR is still unknown and has been included in this study.

METHODS

Therefore, plasma HO-1 were monitored during perioperative period in 65 patients with hepatectomy, with 35 training and 30 validation cohorts. LD were evaluated by liver function serum markers and calculation of regeneration indices, respectively.

RESULTS

In the training setting, HO-1 levels were remarkably reduced after liver resection (P < 0.001) and gradually recovered within 7 days after surgery. Preoperative HO-1 specifically predicted LD during the first week after surgery (AUC: 0.757; P = 0.01). In patients with LD and complications after surgery, HO-1 levels decreased throughout the perioperative period. In addition, we had also confirmed that low levels of HO-1 (<169 ng/ml) before surgery were associated with an increase in the incidence of postoperative LD and morbidity (P = 0.007, P = 0.045), and decrease of liver regeneration (P = 0.005). And HO-1 was an independent predictor for poor clinical outcome.

CONCLUSIONS

We had provided the first clinical data verifying that human HO-1 was related to LD. Consequently, HO-1 levels can be used as effective clinical indicators to predict LD and clinical outcome, and can be used as intervention target before liver resection.

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

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

Heme oxygenase-1(HO-1) regulates Golgi stress and attenuates endotoxin-induced acute lung injury through hypoxia inducible factor-1α (HIF-1α)/HO-1 signaling pathway

Sepsis caused acute lung injury (ALI) is a kind of serious disease in critically ill patients with very high morbidity and mortality. Recently, it has been demonstrated that Golgi is involved in the process of oxidative stress. However, whether Golgi stress is associated with oxidative stress in septic induced acute lung injury has not been elucidated. In this research, we found that lipopolysaccharide (LPS) induced oxidative stress, apoptosis, inflammation and Golgi morphology changes in acute lung injury both in vivo and in vitro. The knockout of heme oxygenase-1(HO-1) aggravated oxidative stress, inflammation, apoptosis and reduced the expression of Golgi matrix protein 130 (GM130), mannosidase Ⅱ, Golgi-associated protein golgin A1 (Golgin 97), and increased the expression of Golgi phosphoprotein 3 (GOLPH3), which caused the fragmentation of Golgi. Furtherly, the activation of hypoxia inducible factor-1α (HIF-1α)/HO-1 pathway, attenuates Golgi stress and oxidative stress by increasing the levels of GM130, mannosidase Ⅱ, Golgin 97, and decreasing the expression of GOLPH3 both in vivo and in vitro. Therefore, the activation of HO-1 plays a crucial role in alleviating sepsis-induced acute lung injury by regulating Golgi stress, oxidative stress, which may provide a therapeutic target for the treatment of acute lung injury.

Effects of Cold-inducible RNA-binding Protein (CIRP) on Liver Glycolysis during Acute Cold Exposure in C57BL/6 Mice

Cold-inducible RNA-binding protein (CIRP) is a stress-responsive protein involved in several signal transduction pathways required for cellular function, which are associated with apoptosis and proliferation. The present study aimed to investigate the possible effects of CIRP-mediated regulation of glucose metabolism in the liver following acute cold exposure. The livers and serum of male C57BL/6 mice were collected following cold exposure at 4 °C for 0 h, 2 h, 4 h, and 6 h. Glucose metabolic markers and the expression of glucose metabolic-related proteins were detected in the liver. Acute cold exposure was found to increase the consumption of glycogen in the liver. Fructose-1,6-diphosphate (FDP) and pyruvic acid (PA) were found to show a brief increase followed by a sharp decrease during cold exposure. Anti-apoptotic protein (Bcl-2) expression was upregulated. CIRP protein expression displayed a sequential increase with prolonged acute cold exposure time. Acute cold exposure also increased the level of protein kinase B (AKT) phosphorylation, and activated the AKT-signaling pathway. Taken together, these findings indicate that acute cold exposure increased the expression of CIRP protein, which regulates mouse hepatic glucose metabolism and maintains hepatocyte energy balance through the AKT signaling pathway, thereby slowing the liver cell apoptosis caused by cold exposure.