Hypermethylation of the galectin-3 promoter is associated with poor prognosis of acute-on-chronic hepatitis B liver failure

Galectin-3: therapeutic targeting in liver disease

INTRODUCTION

The rising incidence of liver diseases is a worldwide healthcare concern. However, the therapeutic options to manage chronic inflammation and fibrosis, the processes at the basis of morbidity and mortality of liver diseases, are very limited. Galectin 3 (Gal-3) is a protein implicated in fibrosis in multiple organs. Several Gal-3 inhibitors are currently in clinical development.

AREAS COVERED

This review describes our current understanding of the role of Gal-3 in chronic liver diseases, with special emphasis on fibrosis. Also, we review therapeutic advances based on Gal-3 inhibition, describing drug properties and their current status in clinical research.

EXPERT OPINION

Currently, the known effects of Gal-3 point to a direct activation of the NLRP3 inflammasome leading to its activation in liver macrophages and activated macrophages play a key role in tissue fibrogenesis. However, more research is needed to elucidate the role of Gal-3 in the different activation pathways, dissecting the intracellular and extracellular mechanisms of Gal-3, and its role in pathogenesis. Gal-3 could be a target for early therapy of numerous hepatic diseases and, given the lack of therapeutic options for liver fibrosis, there is a strong pharmacologic potential for Gal-3-based therapies.

Unraveling the pathophysiologic role of galectin-3 in chronically injured liver

Galectin-3 (Gal-3) previously referred to as S-type lectins, is a soluble protein that specifically binds to β-galactoside carbohydrates with high specificity. Gal-3 plays a pivotal role in a variety of pathophysiological processes such as cell proliferation, inflammation, differentiation, angiogenesis, transformation and apoptosis, pre-mRNA splicing, metabolic syndromes, fibrosis, and host defense. The role of Gal-3 has also been implicated in liver diseases. Gal-3 is activated upon a hepatotoxic insult to the liver and its level has been shown to be upregulated in fatty liver diseases, inflammation, nonalcoholic steatohepatitis, fibrosis, cholangitis, cirrhosis, and hepatocellular carcinoma (HCC). Gal-3 directly interacts with the NOD-like receptor family, pyrin domain containing 3, and activates the inflammasome in macrophages of the liver. In the chronically injured liver, Gal-3 secreted by injured hepatocytes and immune cells, activates hepatic stellate cells (HSCs) in a paracrine fashion to acquire a myofibroblast like collagen-producing phenotype. Activated HSCs in the fibrotic liver secrete Gal-3 which acts via autocrine signaling to exacerbate extracellular matrix synthesis and fibrogenesis. In the stromal microenvironment, Gal-3 activates cancer cell proliferation, migration, invasiveness, and metastasis. Clinically, increased serum levels and Gal-3 expression were observed in the liver tissue of nonalcoholic steatohepatitis, fibrotic/cirrhotic, and HCC patients. The pathological role of Gal-3 has been experimentally and clinically reported in the progression of chronic liver disease. Therefore, this review discusses the pathological role of Gal-3 in the progression of chronic liver diseases.

Research progress on short-term prognosis of acute-on-chronic liver failure

INTRODUCTION

Acute-on-chronic liver failure (ACLF) is a clinical syndrome characterized as a severe condition with rapid progression, poor therapeutic response and poor prognosis. Early and timely evaluation of the prognosis is helpful for providing appropriate clinical intervention and prolonging patient survival.

AREAS COVERED

Currently, there are no specific dynamic and comprehensive approaches to assess the prognosis of patients with ACLF. This article reviews the progress in evaluating the short-term prognosis of ACLF to provide future directions for more dynamic prospective large-scale multicenter studies and a basis for individualized and precise treatment for ACLF patients. We searched PubMed and Web of Science with the term 'acute on chronic liver failure' and 'prognosis.' There was no date or language restriction, and our final search was on 26 October 2022.

EXPERT OPINION

ACLF is a dynamic process, and the best prognostic marker is the clinical evolution of organ failure over time. New prognostic markers are developing not only in the fields of genetics and histology but also toward diversification combined with imaging. Determining which patients will benefit from continued advanced life support is a formidable challenge, and accurate short-term prognostic assessments of ACLF are a good approach to addressing this issue.

Galectin-3 critically mediates the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling

We previously documented that M2-like macrophages exert a hepatoprotective effect in acute-on-chronic liver failure (ACLF) by inhibiting necroptosis signalling. Nevertheless, the molecular mechanism behind this hepatoprotection still needs to be further dissected. Galectin-3 (GAL3) has been reported to be critically involved in the pathogenesis of multiple liver diseases, whereas the potential role of GAL3 in ACLF remains to be explored. Herein, we hypothesised that GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting necroptosis. To test this hypothesis, we first assessed the expression of GAL3 in control and fibrotic mice with or without acute insult. Second, loss- and gain-of-function experiments of GAL3 were performed. Third, the correlation between GAL3 and M2-like macrophage activation was analysed, and the potential role of GAL3 in M2-like macrophage-conferred hepatoprotection was confirmed. Finally, the molecular mechanism underlying GAL3-mediated hepatoprotection was dissected. GAL3 was found to be obviously upregulated in fibrotic mice with or without acute insult but not in acutely injured mice. Depletion of GAL3 aggravated hepatic damage in fibrotic mice upon insult. Conversely, adoptive transfer of GAL3 provided normal mice enhanced resistance against acute insult. The expression of GAL3 is closely correlated with M2-like macrophage activation. Through adoptive transfer and depletion experiments, M2-like macrophages were verified to act as a major source of GAL3. Importantly, GAL3 was confirmed to hold a pivotal place in the hepatoprotection conferred by M2-like macrophages through loss- and gain-of-function experiments. Unexpectedly, the depletion and adoptive transfer of GAL3 resulted in significant differences in the expression levels of pyroptosis but not necroptosis signalling molecules. Taken together, GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling. Our findings provide novel insights into the pathogenesis and therapy of ACLF.

Hypermethylation of thymosin β4 predicts a poor prognosis for patients with acute-on-chronic hepatitis B liver failure

BACKGROUND

It has been demonstrated that thymosin β4 (Tβ4) could inflect the severity of acute-on-chronic hepatitis B liver failure (ACHBLF), but the relationship between its methylation status and the prognosis of liver failure is not clear. This study aimed to determine Tβ4 promoter methylation status in patients with ACHBLF and to evaluate its prognostic value.

METHODS

The study recruited 115 patients with ACHBLF, 80 with acute-on-chronic hepatitis B pre-liver failure (pre-ACHBLF), and 86 with chronic hepatitis B (CHB). In addition, there were 36 healthy controls (HCs) from the Department of Hepatology, Qilu Hospital of Shandong University. The 115 patients with ACHBLF were divided into three subgroups: 33 with early stage ACHBLF (E-ACHBLF), 42 with mid-stage ACHBLF (M-ACHBLF), and 40 with advanced stage ACHBLF (A-ACHBLF). Tβ4 promoter methylation status in peripheral blood mononuclear cells (PBMCs) was measured by methylation-specific polymerase chain reaction, and mRNA was detected by quantitative real-time polymerase chain reaction.

RESULTS

Methylation frequency of Tβ4 was significantly higher in patients with ACHBLF than in those with pre-ACHBLF, CHB or HC. However, expression of Tβ4 mRNA showed the opposite trend. In patients with ACHBLF, Tβ4 promoter methylation status correlated negatively with mRNA levels. The 3-month mortality of ACHBLF in the methylated group was significantly higher than that in the unmethylated group. Also, Tβ4 promoter methylation frequency was lower in survivors than in non-survivors. When used to predict the 1-, 2-, and 3-month incidence of ACHBLF, Tβ4 methylation status was better than the model for end-stage liver disease (MELD) score. The predictive value of Tβ4 methylation was higher than that of MELD score for the mortality of patients with E-ACHBLF and M-ACHBLF, but not for A-ACHBLF.

CONCLUSIONS

Tβ4 methylation might be an important early marker for predicting disease incidence and prognosis in patients with ACHBLF.

Hypomethylation of thymosin β4 promoter is associated with glucocorticoid therapy in patients with acute-on-chronic hepatitis B-induced liver failure

BACKGROUND

We aimed to determine whether the methylation status of thymosin β4 (Tβ4) promoter reflects the severity of acute-on-chronic hepatitis B liver failure (ACHBLF) and whether glucocorticoids affect this status.

METHODS

Fifty-six patients with ACHBLF, 45 with chronic hepatitis B (CHB) and 32 healthy controls (HCs), were retrospectively enrolled. Methylation-specific PCR and real-time PCR were used to detect Tβ4 methylation frequency and mRNA level. The expression of Tβ4 was measured before and after glucocorticoid treatment in patients with ACHBLF. Clinical and laboratory parameters were obtained.

RESULTS

Tβ4 mRNA expression of patients with ACHBLF was lower than in patients with CHB or HCs, but the methylation frequency was higher. Tβ4 promoter methylation frequency was correlated with serum total bilirubin, prothrombin activity and model for end-stage liver disease score. Moreover, Tβ4 promoter methylation frequency decreased and demethylation occurred during glucocorticoid therapy. After glucocorticoid therapy, Tβ4 mRNA expression and liver function were better in patients with low levels of methylation than in those with higher levels. After 90 d, the survival of patients with low levels of methylation was significantly higher than those with high levels.

CONCLUSIONS

Patients with ACHBLF who have low levels of Tβ4 methylation may show a more favorable response to glucocorticoid treatment.

Role of Galectins in the Liver Diseases: A Systematic Review and Meta-Analysis

Background: Galectins, a family of β-galactoside-binding proteins, are related to the development and progression of various human diseases such as cancer, heart failure, and chronic kidney disease. However, its role in liver diseases is unclear. Methods: The PubMed, Embase, and Cochrane Library databases were searched. Hazard ratios (HRs), odds ratios (ORs), and mean differences (MDs) with 95% CIs were pooled to evaluate the association of the galectins with the outcomes and risk of liver diseases by a random effects model. Results: Thirty three studies involving 43 cohorts and 4,168 patients with liver diseases were included. In the patients with hepatocellular carcinoma (HCC), high expression of galectin-1 and -3 in the tissues was significantly associated with worse overall survival (galectin-1: HR = 1.94, 95% CI = 1.61-2.34, p < 0.001; galectin-3: HR = 3.29, 95% CI = 1.62-6.68, p < 0.001) and positive vascular invasion (galectin-1: OR = 1.74, 95% CI = 1.18-2.58, p = 0.005; galectin-3: OR = 2.98, 95% CI = 1.58-5.60, p = 0.001); but, high expression of galectin-4 and -9 in the tissues was significantly associated with better overall survival (galectin-4: HR = 0.53, 95% CI = 0.36-0.79, p = 0.002; galectin-9: HR = 0.56, 95% CI = 0.44-0.71, p < 0.001) and negative vascular invasion (galectin-4: OR = 0.36, 95% CI = 0.19-0.72, p = 0.003; galectin-9: OR = 0.60, 95% CI = 0.37-0.97, p = 0.037). Serum galectin-3 level was significantly higher in HCC (MD = 3.06, 95% CI = 1.79-4.32, p < 0.001), liver failure (MD = 0.44, 95% CI = 0.23-0.66, p < 0.001), liver cirrhosis (MD = 1.83, 95% CI = 1.15-2.51, p < 0.001), and chronic active hepatitis B (MD = 18.95, 95% CI = 10.91-27.00, p < 0.001); serum galectin-9 level was significantly higher in HCC (MD = 3.74, 95% CI = 2.57-4.91, p < 0.001) and autoimmune hepatitis (MD = 8.80, 95% CI = 7.61-9.99, p < 0.001). Conclusion: High galectin-1 and -3 and low galectin-4 and -9 expression indicate worse outcomes of patients with HCC. Serum galectin-3 and -9 levels are positively associated with the risk of chronic liver diseases.

The roles of galectins in hepatic diseases

Hepatic diseases include all diseases that occur in the liver, including hepatitis, cirrhosis, hepatocellular carcinoma, etc. Hepatic diseases worldwide are characterized by high incidences of digestive system diseases, which present with subtle symptoms, are difficult to treat and have high mortality. Galectins are β-galactoside-binding proteins that have been found to be aberrantly expressed during hepatic disease progression. An increasing number of studies have shown that abnormal expression of galectins is extensively involved in hepatic diseases, such as hepatocellular carcinoma (HCC), liver cirrhosis, hepatitis and liver fibrosis. Galectins function as intracellular and extracellular hepatic disease regulators mainly through the binding of their carbohydrate recognition domain to glycoconjugates expressed in hepatocytes. In this review, we summarize current research on the various roles of galectins in cirrhosis, hepatitis, liver fibrosis and HCC, which may provide a preliminary theoretical basis for the exploration of new targets for the treatment of hepatic diseases.

Methylation status of the stimulator of interferon genes promoter in patients with chronic hepatitis B

The stimulator of interferon genes (STING) plays a crucial role in the recognition of a viral infection and subsequent stimulation of an immune response. However, it is unclear whether methylation of the STING promoter affects STING transcription and response to antiviral therapy. The present study determined the methylation status of the STING promoter in patients with chronic hepatitis B (CHB).This study included 198 participants, of which 159 participants had CHB and 39 were healthy controls (HCs). Methylation-specific polymerase chain reaction was performed to detect the methylation status of the STING promoter. Reverse transcription-quantitative polymerase chain reaction was performed to determine STING mRNA level in peripheral blood mononuclear cells.The methylation frequency of the STING promoter was significantly higher and STING mRNA level was lower in the patients with CHB than in the HCs. Presence of hepatitis B virus (HBV) DNA was independently correlated with an increased risk of STING promoter methylation. Virological response frequency was higher in the patients with CHB receiving entecavir (ETV) than in those receiving adefovir (ADV). In the ETV group, the virological response frequency was evidently lower in the patients with CHB having methylated STING promoters than in those having unmethylated STING promoters. However, there was no significant difference in the virological response frequency between ADV-treated patients having methylated and unmethylated STING promoters.These results indicate that the hypermethylation of the STING promoter and thus the transcriptional repression of STING weaken the effect of STING in inhibiting HBV replication and decreases the effectiveness of antiviral therapy.