Enhancer of zeste homolog 2-catalysed H3K27 trimethylation plays a key role in acute-on-chronic liver failure via TNF-mediated pathway

Regulation of histone H3K27 methylation in inflammation and cancer

Inflammation is a multifaceted defense mechanism of the immune system against infection. Chronic inflammation is intricately linked to all stages of tumorigenesis and is therefore associated with an elevated risk of developing serious cancers. Epigenetic mechanisms have the capacity to trigger inflammation as well as facilitate tumor development and transformation within an inflammatory context. They achieve this by dynamically modulating the expression of both pro-inflammatory and anti-inflammatory cytokines, which in turn sustains chronic inflammation. The aberrant epigenetic landscape reconfigures the transcriptional programs of inflammatory and oncogenic genes. This reconfiguration is pivotal in dictating the biological functions of both tumor cells and immune cells. Aberrant histone H3 lysine 27 site (H3K27) methylation has been shown to be involved in biological behaviors such as inflammation development, tumor progression, and immune response. The establishment and maintenance of this repressive epigenetic mark is dependent on the involvement of the responsible histone modifying enzymes enhancer of zeste homologue 2 (EZH2), jumonji domain containing 3 (JMJD3) and ubiquitously transcribed tetratricopeptide repeat gene X (UTX) as well as multiple cofactors. In addition, specific pharmacological agents have been shown to modulate H3K27 methylation levels, thereby modulating inflammation and carcinogenesis. This review comprehensively summarises the current characteristics and clinical significance of epigenetic regulation of H3K27 methylation in the context of inflammatory response and tumor progression.

Targeting histone methylation and demethylation for non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the leading chronic liver disease worldwide, facing increasing challenges in terms of prevention and treatment. The methylation of lysine and arginine residues on histone proteins is dynamically controlled by histone methyltransferases (HMTs) and histone demethylases (HDMs), regulating chromatin structure and gene transcription. Mutations, genetic translocations, and altered gene expression involving HMTs and HDMs are frequently observed in NAFLD. HMTs and HDMs are receiving increasing attention in regulating NALFD. Targeting specific HMTs and HDMs for drug development is becoming a new strategy for treating NAFLD. This review provides a comprehensive summary of the regulatory mechanism of histone methylation/demethylation in NAFLD. Additionally, we discuss the potential applications of HMTs and HDMs inhibitors in preventing NAFLD, which may provide a scientific basis for the treatment of NAFLD.

The relationship and clinical significance of lactylation modification in digestive system tumors

Lactylation, an emerging post-translational modification, plays a pivotal role in the initiation and progression of digestive system tumors. This study presents a comprehensive review of lactylation in digestive system tumors, underscoring its critical involvement in tumor development and progression. By focusing on metabolic reprogramming, modulation of the tumor microenvironment, and the molecular mechanisms regulating tumor progression, the potential of targeting lactylation as a therapeutic strategy is highlighted. The research reveals that lactylation participates in gene expression regulation and cell signaling by affecting the post-translational states of histones and non-histone proteins, thereby influencing metabolic pathways and immune evasion mechanisms in tumor cells. Furthermore, this study assesses the feasibility of lactylation as a therapeutic target, providing insights for clinical treatment of gastrointestinal cancers. Future research should concentrate on elucidating the mechanisms of lactylation, developing efficient lactylation inhibitors, and validating their therapeutic efficacy in clinical trials, which could transform current cancer treatment and immunotherapy approaches. In summary, this review emphasizes the crucial role of lactylation in tumorigenesis and progression through a detailed analysis of its molecular mechanisms and clinical significance.

Lonicerin alleviates ovalbumin-induced asthma of mice via inhibiting enhancer of zeste homolog 2/nuclear factor-kappa B signaling pathway

Asthma is the most common chronic disease in the respiratory system of children caused by abnormal immunity that responses to common antigens. Lonicerin exerts anti-inflammatory activity in other inflammatory models through targeting enhancer of zeste homolog 2 (EZH2) that is related to asthma. We sought to explore the role and mechanism of lonicerin in regulating allergic airway inflammation. Mice were intraperitoneally injected 10 µg ovalbumin (OVA) on postnatal day 5 (P5) and P10, and then inhaled 3% aerosolized OVA for 10 min every day on P18-20, to establish asthmatic mice model. Lonicerin (10 or 30 mg/kg) was given to mice by intragastric administration on P16-P20. Notably, the administration of lonicerin amended infiltration of inflammatory cells and mucus hypersecretion. OVA-specific IgE level, inflammatory cell count and inflammatory cytokines in asthmatic mice were reduced after lonicerin treatment. Moreover, it suppressed the activity of EZH2 and activation of nuclear factor-kappa B (NF-κB) as evidenced by decreasing tri-methylation of histone H3 at lysine 27 and reducing nuclear translocation of NF-κB p65. In a word, Lonicerin may attenuate asthma by inhibiting EZH2/NF-κB signaling pathway.

Exploring the clinical significance of IL-38 correlation with PD-1, CTLA-4, and FOXP3 in colorectal cancer draining lymph nodes

Introduction

Colorectal cancer (CRC) presents a substantial challenge characterized by unacceptably high mortality and morbidity, primarily attributed to delayed diagnosis and reliance on palliative care. The immune response of the host plays a pivotal role in carcinogenesis, with IL-38 emerging as a potential protective factor in CRC. However, the precise involvement of IL-38 among various leucocytes, its interactions with PD-1/PD-L1, and its impact on metastasis require further elucidation.

Results

Our investigation revealed a significant correlation between IL-38 expression and metastasis, particularly concerning survival and interactions among diverse leucocytes within draining lymph nodes. In the mesentery lymph nodes, we observed an inverse correlation between IL-38 expression and stages of lymph node invasions (TNM), invasion depth, distance, and differentiation. This aligns with an overall survival advantage associated with higher IL-38 expression in CRC patients' nodes compared to lower levels, as well as elevated IL-38 expression on CD4+ or CD8+ cells. Notably, a distinct subset of patients characterized by IL-38high/PD-1low expression exhibited superior survival outcomes compared to other combinations.

Discussion

Our findings demonstrate that IL-38 expression in colorectal regional nodes from CRC patients is inversely correlated with PD-1/PD-L1 but positively correlated with infiltrating CD4+ or CD8+ lymphocytes. The combined assessment of IL-38 and PD-1 expression in colorectal regional nodes emerges as a promising biomarker for predicting the prognosis of CRC.

EZH2-interacting lncRNAs contribute to gastric tumorigenesis; a review on the mechanisms of action

Gastric cancer (GC) remains one of the deadliest malignancies worldwide, demanding new targets to improve its diagnosis and treatment. Long non-coding RNAs (lncRNAs) are dysregulated through gastric tumorigenesis and play a significant role in GC progression and development. Recent studies have revealed that lncRNAs can interact with histone-modifying polycomb protein, enhance Zeste Homolog 2 (EZH2), and mediate its site-specific functioning. EZH2, which functions as an oncogene in GC, is the catalytic subunit of the PRC2 complex that induces H3K27 trimethylation and epigenetically represses gene expression. EZH2-interacting lncRNAs can recruit EZH2 to the promoter regions of various tumor suppressor genes and cause their transcriptional deactivation via histone methylation. The interactions between EZH2 and this lncRNA modulate different processes, such as cell cycle, cell proliferation and growth, migration, invasion, metastasis, and drug resistance, in vitro and in vivo GC models. Therefore, EZH2-interacting lncRNAs are exciting targets for developing novel targeted therapies for GC. Subsequently, this review aims to focus on the roles of these interactions in GC progression to understand the therapeutic value of EZH2-interacting lncRNAs further.

Overexpression of HMGB1 in hepatocytes accelerates PTEN inactivation-induced liver cancer

BACKGROUND

Liver cancer is increasing due to the rise in metabolic dysfunction-associated steatohepatitis (MASH). High-mobility group box-1 (HMGB1) is involved in the pathogenesis of chronic liver disease, but its role in MASH-associated liver cancer is unknown. We hypothesized that an increase in hepatocyte-derived HMGB1 in a mouse model of inactivation of PTEN that causes MASH could promote MASH-induced tumorigenesis.

METHODS

We analyzed publicly available transcriptomics datasets, and to explore the effect of overexpressing HMGB1 in cancer progression, we injected 1.5-month-old Pten∆Hep mice with adeno-associated virus serotype-8 (AAV8) vectors to overexpress HMGB1-EGFP or EGFP, and sacrificed them at 3, 9 and 11 months of age.

RESULTS

We found that HMGB1 mRNA increases in human MASH and MASH-induced hepatocellular carcinoma (MASH-HCC) compared to healthy livers. Male and female Pten∆Hep mice overexpressing HMGB1 showed accelerated liver tumor development at 9 and 11 months, respectively, with increased tumor size and volume, compared to control Pten∆Hep mice. Moreover, Pten∆Hep mice overexpressing HMGB1, had increased incidence of mixed HCC-intrahepatic cholangiocarcinoma (iCCA). All iCCAs were positive for nuclear YAP and SOX9. Male Pten∆Hep mice overexpressing HMGB1 showed increased cell proliferation and F4/80+ cells at 3 and 9 months.

CONCLUSION

Overexpression of HMGB1 in hepatocytes accelerates liver tumorigenesis in Pten∆Hep mice, enhancing cell proliferation and F4/80+ cells to drive MASH-induced liver cancer.

Unraveling the Complex Interplay between Epigenetics and Immunity in Alcohol-Associated Liver Disease: A Comprehensive Review

The mechanisms of immune dysfunction in alcohol-associated liver disease (ALD) have garnered growing research interest in recent times. Alcohol-mediated immune dysfunction has been implicated as a potential cause of ALD-associated microbial infection and inflammatory response. The immune microenvironment of an organism is essentially a complex network of interactions between immune cells, cytokines, extracellular matrix, and other immune-related molecules. This microenvironment is highly adaptive and responsive to environmental cues. Epigenetic reprogramming of the immune microenvironment has recently emerged as a key driver of ALD progression, particularly in the context of endotoxin tolerance and immune disorders. Although epigenetic modifications are known to play an important role in the regulation of the immune microenvironment in ALD, the specific mechanisms and molecular processes by which this regulation is achieved are yet to be fully understood. This paper aims to provide an overview of the current knowledge on the effects of alcohol consumption on epigenetics, with special focus on summarizing the data on the epigenetic regulatory mechanisms involved in the effects of alcohol consumption on the immune microenvironment. In addition, this paper aims to present a review of the epigenetic modifications involved in different forms of ALD. This review is expected to offer new perspectives for the diagnosis, treatment, monitoring, and prognostic assessment of ALD from an epigenetic perspective.

MALAT1-mediated EZH2 Recruitment to the GFER Promoter Region Curbs Normal Hepatocyte Proliferation in Acute Liver Injury

BACKGROUND AND AIMS

The goal of this study was to investigate the mechanism by which the long noncoding RNA MALAT1 inhibited hepatocyte proliferation in acute liver injury (ALI).

METHODS

Lipopolysaccharide (LPS) was used to induce an ALI cellular model in HL7702 cells, in which lentivirus vectors containing MALAT1/EZH2/GFER overexpression or knockdown were introduced. A series of experiments were performed to determine their roles in liver injury, oxidative stress injury, and cell biological processes. The interaction of MALAT1 with EZH2 and enrichment of EZH2 and H3K27me3 in the GFER promoter region were identified. Rats were treated with MALAT1 knockdown or GFER overexpression before LPS induction to verify the results derived from the in vitro assay.

RESULTS

MALAT1 levels were elevated and GFER levels were reduced in ALI patients and the LPS-induced cell model. MALAT1 knockdown or GFER overexpression suppressed cell apoptosis and oxidative stress injury induced cell proliferation, and reduced ALI. Functionally, MALAT1 interacted directly with EZH2 and increased the enrichment of EZH2 and H3K27me3 in the GFER promoter region to reduce GFER expression. Moreover, MALAT1/EZH2/GFER was activated the AMPK/mTOR signaling pathway.

CONCLUSION

Our study highlighted the inhibitory role of reduced MALAT1 in ALI through the modulation of EZH2-mediated GFER.

Azithromycin attenuates wheezing after pulmonary inflammation through inhibiting histone H3K27me3 hypermethylation mediated by EZH2

BACKGROUND

Histone methylation modification plays an irreplaceable role in the wheezing diseases. The aim of this study was to explore whether azithromycin (AZM) attenuates post-inflammatory wheezing through inhibiting hypermethylation of histone H3K27me3 mediated by EZH2.

RESULTS

A randomized controlled trial was conducted on 227 children who underwent fiber-optic bronchoscopy, and bronchoalveolar lavage fluid (BALF) was collected for analyses. The expressions of IL-6, IL-2, NF-κB P65, EZH2 and H3K27me3 in the BALF of wheezing cases were significantly increased when compared with levels in non-wheezing cases (P < 0.05), while IL-10 was decreased (P < 0.05). AZM attenuated the overexpression of NF-κB P65, EZH2 and H3K27me3 in wheezing cases (P < 0.05) and shortened the time of wheezing in wheezing cases (P < 0.05). An in vitro model of inflammation was established using rat alveolar macrophages induced by lipopolysaccharide (LPS). AZM, SN50 (a NK-κB inhibitor) and GSK126 (an EZH2 inhibitor) attenuated the overexpression of EZH2, NF-κB P65 and H3K27me3 induced by LPS in rat alveolar macrophages (P < 0.05). AZM, SN50 and GSK126 normalized the decreased expression of IL-10 induced by LPS in the same samples (P < 0.05). Co-immunoprecipitation results showed that H3K27me3 interacted with EZH2 and NF-κB P65, and immunofluorescence data showed that AZM and SN50 inhibited LPS-induced NF-κB P65 nuclear translocation in rat alveolar macrophages.

CONCLUSION

Histone H3K27me3 hypermethylation mediated by EZH2 may be involved in wheezing after pulmonary inflammation. AZM attenuated wheezing after pulmonary inflammation by inhibiting NF-κB P65-related hypermethylation of H3K27me3 mediated by EZH2.

Network pharmacology-based prediction of active compounds in the Wenyang Jiedu Huayu formula acting on acute-on-chronic liver failure with experimental support in vitro and in vivo

Acute-on-chronic liver failure (ACLF) is characterized by undermined liver function, massive necrosis/apoptosis of hepatocytes, and hepatic inflammatory cell recruitment, leading to multiorgan failure. Traditional Chinese medicine (TCM) has been widely applied in clinical and experimental studies of ACLF. In this study, 23 compounds with 6,386 drug targets were obtained from Wenyang Jiedu Huayu (WYJDHY), and 8,096 genes were identified as ACLF disease targets, among which 3,132 were overlapping co-targets. Expression profile analysis identified 105 DEGs among the co-targets, which were associated with biological activities such as lymphocyte activation, immune response regulation, and pathways such as Th17 cell differentiation and NF-κB signaling. After PPI analysis and network construction, atractylenolide I (AT-1) has been identified as the hub active ingredient of the WYJDHY formula. LPS stimulation inhibited rat hepatocytes’ BRL 3A cell viability, promoted cell apoptosis, increased the levels of ALT, AST, IL-6, and VCAM-1 within the culture medium, and activated NF-κB signaling, whereas AT-1 treatment significantly attenuated LPS-induced toxicity on BRL 3A cells. Furthermore, the NF-κB signaling inhibitor PDTC exerted effects on LPS-stimulated BRL 3A cells similar to those of AT-1, and the combination of PDTC and AT-1 further attenuated LPS-induced toxicity on BRL 3A cells. In vivo, AT-1 alone or with PDTC improved the symptoms and local inflammation in ACLF model rats. In conclusion, 23 active ingredients of six herbs in the WYJDHY formula were retrieved, and 105 co-targets were differentially expressed in ACLF. AT-1 exerts protective effects on LPS-stimulated hepatocytes and ACLF rats, possibly by inhibiting the NF-κB pathway.

Regulation of CCL2 by EZH2 affects tumor-associated macrophages polarization and infiltration in breast cancer

Tumor associated macrophages (TAMs) play an important role in tumorigenesis, development and anti-cancer drug therapy. However, very few epigenetic compounds have been elucidated to affect tumor growth by educating TAMs in the tumor microenvironment (TME). Herein, we identified that EZH2 performs a crucial role in the regulation of TAMs infiltration and protumoral polarization by interacting with human breast cancer (BC) cells. We showed that EZH2 inhibitors-treated BC cells induced M2 macrophage polarization in vitro and in vivo, while EZH2 knockdown exhibited the opposite effect. Mechanistically, inhibition of EZH2 histone methyltransferase alone by EZH2 inhibitors in breast cancer cells could reduce the enrichment of H3K27me3 on CCL2 gene promoter, elevate CCL2 transcription and secretion, contributing to the induction of M2 macrophage polarization and recruitment in TME, which reveal a potential explanation behind the frustrating results of EZH2 inhibitors against breast cancer. On the contrary, EZH2 depletion led to DNA demethylation and subsequent upregulation of miR-124-3p level, which inhibited its target CCL2 expression in the tumor cells, causing arrest of TAMs M2 polarization. Taken together, these data suggested that EZH2 can exert opposite regulatory effects on TAMs polarization through its enzymatic or non-enzymatic activities. Our results also imply that the effect of antitumor drugs on TAMs may affect its therapeutic efficacy, and the combined application with TAMs modifiers should be warranted to achieve great clinical success.

Advances in cell death - related signaling pathways in acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) has been a hot spot in the field of liver disease research in recent years, with high morbidity, rapid course change and high mortality. Currently, there is the absence of specific treatment in clinical practice. Liver transplantation has the best therapeutic effect, but it is prone to have internal environment disorder and liver cell death after transplantation, which leads to the failure of transplantation.In recent years, with the development of molecular biology, scholars have explored the treatment of ACLF at the molecular level, and more and more molecular signaling pathways related to the treatment of ACLF have been discovered. Modulating the relevant signaling pathways to reduce the mortality of liver cells after transplantation may effectively improve the success rate of transplantation. In this review, we introduce some signaling pathways related to cell death and their research progress in acute-on-chronic liver failure.

Transcriptional and Epigenetic Regulation of Monocyte and Macrophage Dysfunction by Chronic Alcohol Consumption

Drinking alcohol, even in moderation, can affect the immune system. Studies have shown disproportionate effects of alcohol on circulating and tissue-resident myeloid cells (granulocytes, monocytes, macrophages, dendritic cells). These cells orchestrate the body's first line of defense against microbial challenges as well as maintain tissue homeostasis and repair. Alcohol's effects on these cells are dependent on exposure pattern, with acute drinking dampening but chronic drinking enhancing production of inflammatory mediators. Although chronic drinking is associated with heightened systemic inflammation, studies on tissue resident macrophage populations in several organs including the spleen, liver, brain, and lung have also shown compromised functional and metabolic capacities of these cells. Many of these effects are thought to be mediated by oxidative stress caused by alcohol and its metabolites which can directly impact the cellular epigenetic landscapes. In addition, since myeloid cells are relatively short-lived in circulation and are under constant repopulation from the bone marrow compartment, alcohol's effects on bone marrow progenitors and hematopoiesis are important for understanding the impact of alcohol systemically on these myeloid populations. Alcohol-induced disruption of progenitor, circulating, and tissue resident myeloid populations contribute to the increased susceptibility of patients with alcohol use disorders to viral and bacterial infections. In this review, we provide an overview of the impact of chronic alcohol consumption on the function of monocytes and macrophages in host defense, tissue repair and inflammation. We then summarize our current understanding of the mechanisms underlying alcohol-induced disruption and examine changes in transcriptome and epigenome of monocytes and mcrophages. Overall, chronic alcohol consumption leads to hyper-inflammation concomitant with decreased microbial and wound healing responses by monocytes/macrophages due to a rewiring of the epigentic and transcriptional landscape. However, in advanced alcoholic liver disease, myeloid cells become immunosuppressed as a response to the surrounding hyper-inflammatory milieu. Therefore, the effect of chronic alcohol on the inflammatory response depends on disease state and the immune cell population.

Epigenetic Regulation of Hepatic Stellate Cell Activation and Macrophage in Chronic Liver Inflammation

Chronic liver inflammation is a complex pathological process under different stress conditions, and the roles of stellate cells and macrophages in chronic liver inflammation have been widely reported. Moderate liver inflammation can protect the liver from damage and facilitate the recovery of liver injury. However, an inflammatory response that is too intense can result in massive death of hepatocytes, which leads to irreversible damage to the liver parenchyma. Epigenetic regulation plays a key part in liver inflammation. This study reviews the regulation of epigenetics on stellate cells and macrophages to explore the new mechanisms of epigenetics on liver inflammation and provide new ideas for the treatment of liver disease.

Silencing long noncoding RNA NEAT1 alleviates acute liver failure via the EZH2-mediated microRNA-139/PUMA axis

This study aimed to investigate the role of long noncoding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) in the development of ALF. We collected blood samples from patients with acute liver failure (ALF) and established an ALF mouse model induced by D-galactosamine/Lipopolysaccharide (D-GalN/LPS) for in vivo studies. Peripheral blood mononuclear cells (PMBCs) induced with LPS were isolated for in vitro experiments. Survival tests, histological analysis, and biochemical indicator assays were conducted. Luciferase assay was performed to determine the binding affinity between microRNA-139 (miR-139) and p53-upregulated modulator of apoptosis (PUMA). Expression of lncRNA NEAT1, enhancer of zeste homolog 2 (EZH2), and PUMA was upregulated, while the expression of miR-139 was downregulated in clinical samples and D-GalN/LPS induced ALF mouse model. LncRNA NEAT1 promoted the enrichment of H3K27me3 on the promoter region of miR-139 via EZH2, which led to suppression of miR-139. The inhibition of miR-139 resulted in the upregulation of its downstream target PUMA. The NEAT1/miR-139/PUMA pathway upregulated the production of pro-inflammatory cytokines, tumor necrosis factor alpha, interleukin (IL)-6, and IL-1β, thereby mediating the progression of ALF. In conclusion, silencing lncRNA NEAT1 upregulated the expression of miR-139 through EZH2, leading to the downregulation of PUMA, which alleviated the development of ALF.

Increased Circulating T Follicular Helper Cells Induced via IL-12/21 in Patients With Acute on Chronic Hepatitis B Liver Failure

Objectives

T Follicular helper (Tfh) cells, recognized as a distinct CD4⁺ T cell subset, mediate the development of long-lived humoral immunity via B cell activation/differentiation. Tfh cells play an important role during hepatic viral infection, but its role in hepatitis B virus-related acute on chronic liver failure (HBV-ACLF) remains to be explored.

Materials and Methods

The frequency of Tfh cells, serum pro-inflammatory cytokine (IL-12, IL-21, IL-17 and TNF) levels and IgG/M levels were investigated in HBV-ACLF (n = 36), serious chronic hepatitis B (n = 21), moderate chronic hepatitis B patients (n = 32) and healthy control (HC) subjects (n = 10).

Results

Circulating Tfh cells were significantly increased in HBV-ACLF patients compared to other groups, correlating well with MELD score. However, the frequency of Tfh cells decreased in ameliorated HBV-ACLF patients. Furthermore, serum IL-12 and IL-21 levels were higher in HBV-ACLF patients, compared to other groups. Naïve CD4⁺ T cells from HC subjects differentiate into Tfh cells following treatment with HBV-ACLF patients’ serum, a process that can be blocked by IL-12/21 neutralizing antibodies. Tfh cells induced by HBV-ACLF patient’s serum promoted the proliferation and IgG production of B cells in vitro. Moreover, circulating CD19⁺ B cells, serum and liver IgG/M levels were significantly higher in HBV-ACLF patients, compared to other groups.

Conclusions

Our data demonstrated that there was a high frequency of Tfh cells and high levels of serum IL-12/21 in HBV-ACLF patients. Naïve CD4⁺ T cells differentiate into Tfh cells in the presence of HBV-ACLF patients’ serum rich in IL-12/21, which can be blocked by neutralizing IL-12/21 antibodies. These data may provide useful insights for both clinical and basic research in the treatment of HBV-ACLF.

Epigenetic Regulation of Kupffer Cell Function in Health and Disease

Kupffer cells, the resident macrophages of the liver, comprise the largest pool of tissue macrophages in the body. Within the liver sinusoids Kupffer cells perform functions common across many tissue macrophages including response to tissue damage and antigen presentation. They also engage in specialized activities including iron scavenging and the uptake of opsonized particles from the portal blood. Here, we review recent studies of the epigenetic pathways that establish Kupffer cell identity and function. We describe a model by which liver-environment specific signals induce lineage determining transcription factors necessary for differentiation of Kupffer cells from bone-marrow derived monocytes. We conclude by discussing how these lineage determining transcription factors (LDTFs) drive Kupffer cell behavior during both homeostasis and disease, with particular focus on the relevance of Kupffer cell LDTF pathways in the setting of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis.

Inhibition of Dot1L Alleviates Fulminant Hepatitis Through Myeloid-Derived Suppressor Cells

BACKGROUND & AIMS

Fulminant hepatitis (FH) is a clinical syndrome characterized by sudden and severe liver dysfunction. Dot1L, a histone methyltransferase, is implicated in various physiologic and pathologic processes, including transcription regulation and leukemia. However, the role of Dot1L in regulating inflammatory responses during FH remains elusive.

METHODS

Propionibacterium acnes (P. acnes)-primed, lipopolysaccharides (LPS)-induced FH was established in C57BL/6 mice and was treated with the Dot1L inhibitor EPZ-5676. Myeloid derived suppressor cells (MDSCs) were depleted by anti-Gr-1 antibody to evaluate their therapeutic roles in Dot1L treatment of FH. Moreover, peripheral blood of patients suffered with FH and healthy controls was collected to determine the expression profile of Dot1L-SOCS1-iNOS axis in their MDSCs.

RESULTS

Here we identified that EPZ-5676, pharmacological inhibitor of Dot1L, attenuated the liver injury of mice subjected to FH. Dot1L inhibition led to decreased T helper 1 cell response and expansion of regulatory T cells (Tregs) during FH. Interestingly, Dot1L inhibition didn't directly target T cells, but dramatically enhanced the immunosuppressive function of MDSCs. Mechanistically, Dot1L inhibition epigenetically suppressed SOCS1 expression, thus inducing inducible nitric oxide synthase (iNOS) expression in a STAT1-dependent manner. Moreover, in human samples, the levels of Dot1L and SOCS1 expression were upregulated in MDSCs, accompanied by decreased expression of iNOS in patients with FH, compared with healthy controls.

CONCLUSIONS

Altogether, our findings established Dot1L as a critical regulator of MDSC immunosuppressive function for the first time, and highlighted the therapeutic potential of Dot1L inhibitor for FH treatment.

Network Pharmacology Approach to Explore the Potential Mechanisms of Jieduan-Niwan Formula Treating Acute-on-Chronic Liver Failure

Background

Acute-on-chronic liver failure (ACLF) is a clinical syndrome with acute jaundice and coagulation dysfunction caused by various inducements on the basis of chronic liver disease. Western medical treatment is limited. Previous studies have confirmed that Jieduan-Niwan Formula (JDNW Formula), an empirical prescription for the treatment of ACLF, can inhibit inflammation and resist hepatocyte apoptosis. However, potential targets and mechanisms still need to be explored.

Methods

In this study, network pharmacological analysis was performed to investigate the key components and potential mechanisms of JDNW Formula treating ACLF. Firstly, we predicted the potential active ingredients of JDNW Formula and the corresponding potential targets through TCMSP, BATMAN-TCM platform, and literature supplement. Then, the ACLF targets database was built using OMIM, DisGeNET, and GeneCard database. Based on the matching targets between JDNW Formula and ACLF, the PPI network was constructed for MCODE analysis and common targets were enriched by Metascape. Furthermore, the ACLF rat model was used to verify the potential mechanism of JDNW Formula in treating ACLF.

Results

132 potential bioactive components of JDNW Formula and 168 common targets were obtained in this study. The enrichment analysis shows that the AMPK signaling pathway was associated with the treating effects of JDNW Formula. Quercetin was hypothesized to be the key bioactive ingredient in JDNW Formula and has a good binding affinity to AMPK based on molecular docking verification. JDNW Formula and quercetin were verified to treat ACLF by regulating the AMPK/PGC-1α signaling pathway as a prediction.

Conclusion

The study predicted potential mechanisms of JDNW Formula in the treatment of ACLF, involving downregulation of inflammatory factor expression, antioxidant stress, and inhibition of hepatocyte apoptosis. JDNW Formula may improve mitochondrial quality in ACLF via the AMPK signaling pathway, which serves as a guide for further study.

Inhibition of EZH2 ameliorates bacteria-induced liver injury by repressing RUNX1 in dendritic cells

Fulminant hepatic failure (FHF) is a clinical syndrome characterized by a sudden and severe impairment in liver function. However, the precise mechanism of immune dysregulation that is significant to FHF pathogenesis remains unclear. Enhancer of zeste homolog 2 (EZH2) has been implicated in inflammation as a regulator of immune cell function. In this study, we investigated the role of EZH2 in an animal model of human FHF induced by Propionibacterium acnes (P. acnes) and lipopolysaccharide (LPS). We demonstrated that EZH2 depletion in dendritic cells (DCs) and pharmacological inhibition of EZH2 using GSK126 both significantly ameliorated liver injury and improved the survival rates of mice with P. acnes plus LPS-induced FHF, which could be attributed to the decreased infiltration and activation of CD4⁺ T cells in the liver, inhibition of T helper 1 cells and induction of regulatory T cells. The expression of EZH2 in DCs was increased after P. acnes administration, and EZH2 deficiency in DCs suppressed DC maturation and prevented DCs from efficiently stimulating CD4⁺ T-cell proliferation. Further mechanistic analyses indicated that EZH2 deficiency directly increased the expression of the transcription factor RUNX1 and thereby suppressed the immune functions of DCs. The functional dependence of EZH2 on RUNX1 was further illustrated in DC-specific Ezh2-deficient mice. Taken together, our findings establish that EZH2 exhibits anti-inflammatory effects through inhibition of RUNX1 to regulate DC functions and that inhibition of EZH2 alleviates P. acnes plus LPS-induced FHF, probably by inhibiting DC-induced adaptive immune responses. These results highlight the effect of EZH2 on DCs, serving as a guide for the development of a promising immunotherapeutic strategy for FHF.

EZH2 as a Potential Target for NAFLD Therapy

Non-alcoholic fatty liver disease (NAFLD) is a complex disease that is affected by genetic predisposition and epigenetic modification. Deregulation of epigenetic pathways is now recognized as a frequent event in NAFLD, and understanding the mechanistic roles of these epigenetic factors may lead to new strategies for NAFLD treatment. Enhancer of zeste homolog 2 (EZH2) catalyzes methylation on Lys 27 of histone H3, which leads to chromatin compaction and gene silencing. EZH2 regulates embryonic development and cell lineage determination and is related to many human diseases. Recent studies show that EZH2 has critical roles in liver development, homeostasis, and regeneration. Moreover, aberrant activation of EZH2 promotes NAFLD progression. Several EZH2 inhibitors have been developed and studied both in vitro and in clinical trials. In this review, we summarize our current understanding of the role of EZH2 in NAFLD and highlight its potential as a novel therapeutic target for NAFLD treatment.

IL-36 s in the colorectal cancer: is interleukin 36 good or bad for the development of colorectal cancer?

Background and aims

Colorectal cancer (CRC) is a major killer. Host immunity is important in tumorigenesis. Direct comparison among IL-36α, IL-36β and IL-36γ in the prognosis of CRC is unclear.

Methods

CRC tissue arrays were generated from colorectostomy samples with TNM stage, invasion depth and the demography of these patients (n = 185). Using immunohistochemistry/histopathology, IL-36α, IL-36β and IL-36γ were determined, in comparison to non-cancer tissues.

Results

A significant association was observed between colonic IL-36α, IL-36β or IL-36γ and the presence of cancer (with all P < 0.0001). Using ROC curve analysis, specificity and sensitivity of IL-36α, IL-36β or IL-36γ were confirmed, with area under the curve (AUC) values of 0.68, 0.73 and 0.65, respectively. Significant differences in survival were observed between IL-36α^high and IL-36α^low (P = 0.003) or IL-36γ^high and IL-36γ^low (P = 0.03). Survival curves varied significantly when further stratification into sub-groups, on the basis of combined levels of expression of two isotypes of IL-36 was undertaken. A significant difference was observed when levels of IL-36α and IL-36β were combined (P = 0.01), or a combination of IL-36α plus IL-36γ (P = 0.002). The sub-groups with a combination of IL-36α^high plus IL-36β^high, or IL-36α^high plus IL-36γ^low exhibited the longest survival time among CRC patients. In contrast, the sub-groups of IL-36α^low plus IL-36β^high or IL-36α^low plus IL-36γ^high had the shortest overall survival. Using the log-rank test, IL-36α^high expression significantly improved survival in patients with an invasion depth of T4 (P < 0.0001), lymph node metastasis (P = 0.04), TNM III-IV (P = 0.03) or with a right-sided colon tumour (P = 0.02). Similarly, IL-36γ^low expression was significantly associated with improved survival in patients with no lymph node metastasis (P = 0.008), TNM I-II (P = 0.03) or with a left-sided colon tumour (P = 0.05). Multivariate analysis demonstrated that among IL-36α, IL-36β and IL-36γ, only IL-36α (HR, 0.37; 95% CI, 0.16–0.87; P = 0.02) was an independent factor in survival, using Cox proportional hazards regression analysis.

Conclusion

IL-36α or IL-36γ are reliable biomarkers in predicting the prognosis of CRC during the later or early stages of the disease, respectively. Combining IL-36α plus IL-36γ appears to more accurately predict the postoperative prognosis of CRC patients. Our data may be useful in the management of CRC.

Interleukin-38 in colorectal cancer: a potential role in precision medicine

Colorectal cancer (CRC) is a leading cause of cancer-related death, partly due to a lack of reliable biomarkers for early diagnosis. To improve the outcome of CRC, it is critical to provide diagnosis at an early stage using promising sensitive/specific marker(s). Using immunohistochemistry and histopathology, IL-38 expression was determined in tissue arrays of CRC with different TNM status and depth of tumour invasion. Data were compared to IL-38 in adjacent non-cancer tissue and correlated with demographic information, including survival. A substantial reduction of IL-38 was detected in the CRC tissue compared to adjacent non-cancer colonic tissue. IL-38 correlated with the extent of tumour differentiation (P < 0.0001); CRC location in the left side of the colon (P < 0.05), and smaller tumour size (≤ 5 cm; P < 0.05). Receiver operating characteristic (ROC) curve analysis demonstrated both high specificity and high sensitivity of IL-38 for the diagnosis of CRC [area under the curve (AUC) = 0.89)]. By sub-group analysis, AUC of IL-38 for the diagnosis of CRC was higher in poorly differentiated, right-sided CRC or tumour size > 5 cm (all AUC > 0.9). Significantly, longer survival was observed for the IL-38^high versus the IL-38^low groups in CRC patients (P = 0.04). Survival was also longer for IL-38^high patients with lymph node metastasis (P = 0.01) and TNM stage III-IV (P = 0.02). Multivariate analysis demonstrated that IL-38 (P = 0.05) and tumour invasion depth (P = 0.04) were independent factors for survival. High IL38 in CRC is an independent prognostic factor for the longer survival of CRC patients. IL-38 signalling may constitute a therapeutic target in CRC.

Drugs Repurposed as Antiferroptosis Agents Suppress Organ Damage, Including AKI, by Functioning as Lipid Peroxyl Radical Scavengers

BACKGROUND

Ferroptosis, nonapoptotic cell death mediated by free radical reactions and driven by the oxidative degradation of lipids, is a therapeutic target because of its role in organ damage, including AKI. Ferroptosis-causing radicals that are targeted by ferroptosis suppressors have not been unequivocally identified. Because certain cytochrome P450 substrate drugs can prevent lipid peroxidation via obscure mechanisms, we evaluated their antiferroptotic potential and used them to identify ferroptosis-causing radicals.

METHODS

Using a cell-based assay, we screened cytochrome P450 substrate compounds to identify drugs with antiferroptotic activity and investigated the underlying mechanism. To evaluate radical-scavenging activity, we used electron paramagnetic resonance-spin trapping methods and a fluorescence probe for lipid radicals, NBD-Pen, that we had developed. We then assessed the therapeutic potency of these drugs in mouse models of cisplatin-induced AKI and LPS/galactosamine-induced liver injury.

RESULTS

We identified various US Food and Drug Administration-approved drugs and hormones that have antiferroptotic properties, including rifampicin, promethazine, omeprazole, indole-3-carbinol, carvedilol, propranolol, estradiol, and thyroid hormones. The antiferroptotic drug effects were closely associated with the scavenging of lipid peroxyl radicals but not significantly related to interactions with other radicals. The elevated lipid peroxyl radical levels were associated with ferroptosis onset, and known ferroptosis suppressors, such as ferrostatin-1, also functioned as lipid peroxyl radical scavengers. The drugs exerted antiferroptotic activities in various cell types, including tubules, podocytes, and renal fibroblasts. Moreover, in mice, the drugs ameliorated AKI and liver injury, with suppression of tissue lipid peroxidation and decreased cell death.

CONCLUSIONS

Although elevated lipid peroxyl radical levels can trigger ferroptosis onset, some drugs that scavenge lipid peroxyl radicals can help control ferroptosis-related disorders, including AKI.

Crosstalk between histone modification and DNA methylation orchestrates the epigenetic regulation of the costimulatory factors, Tim‑3 and galectin‑9, in cervical cancer

Persistent infection with high-risk human papillomavirus is known to cause cervical cancer. The binding of the costimulatory factors, Tim-3 and galectin-9, can cause immune tolerance and lead to immune escape during carcinogenesis. Epigenetic regulation is essential for Tim-3/galectin-9 expression, which affects the outcome of local cervical cancer infection. Hence, exploring the epigenetic regulatory mechanisms of costimulatory signaling by Tim-3/galectin-9 is of great interest for investigating the mechanisms through which these proteins are regulated in cervical cancer tumorigenesis. In this study, we report that E2F-1 and FOXM1 mediated by HPV18 E6 and E7 can enhance the transcriptional activity of Enhancer of zeste homolog 2 (EZH2) by binding to its promoter region, resulting in the induced expression of the EZH2-specific target protein, H3K27me3, which consequently reduces the expression of the downstream target gene, DNA (cytosine-5)-methyltransferase 3A (DNMT3A). EZH2 and H3K27me3 directly interact with the DNMT3A promoter region to negatively regulate its expression in HeLa cells. Moreover, the downregulated DNMT3A and the decreased methylation levels in HAVCR2/LGALS9 promoter regions in HeLa cells promoted the expression of Tim-3/galectin-9. Furthermore, the high expression of Tim-3/galectin-9 was associated with HPV positivity among patients with cervical cancer. Moreover, HAVCR2/LGALS9 promoter regions were hypermethylated in normal cervical tissues, and this hypermethylated status inhibited gene expression. On the whole, these findings suggest that EZH2, H3K27me3 and DNMT3A mediate the epigenetic regulation of the negative stimulatory molecules, Tim-3 and galectin-9 in cervical cancer which is associated with HPV18 infection.

N-myc and STAT interactor correlates with severity and prognosis in acute-on-chronic liver failure of hepatitis B virus

BACKGROUND AND AIM

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is characterized by acute deterioration of chronic liver disease with excessive inflammation. N-myc and STAT interactor (NMI), an inflammation-mediated protein, involves in various inflammatory-related diseases, but the role of NMI in development and prognosis in HBV-ACLF remains to be elucidated.

METHODS

Serum NMI from healthy controls (HCs, n = 20), chronic hepatitis B (CHB, n = 50) patients, and HBV-ACLF patients (n = 50) was determined using ELISA. NMI from peripheral blood mononuclear cells and liver was confirmed using quantitative real-time polymerase chain reaction, Western blot, and immunofluorescence.

RESULTS

Serum NMI was increased 1.9-fold or 2.2-fold from HBV-ACLF patients compared with that from HCs (P < 0.01) or CHB patients (P < 0.01). Consistently, NMI from peripheral blood mononuclear cells was upregulated significantly from HBV-ACLF patients compared with that from HCs and CHB patients at mRNA and protein levels. Hepatic NMI from HBV-ACLF patients was 2.8-fold higher than that from HCs. Serum NMI was correlated with Model for End-stage Liver Disease, Chronic Liver Failure Consortium ACLF score, and ACLF grades. In contrast, serum NMI was significantly decreased in HBV-ACLF ameliorated patients during follow-up, whereas serum NMI was sustained at high levels in non-ameliorated patients. Elevated serum NMI (≥ 198.5 pg/mL) was correlated with poor survival rate of HBV-ACLF patients. Using receiver operating characteristics curves, it was suggested that serum NMI was a potential biomarker in predicting 3-month mortality of HBV-ACLF patients.

CONCLUSIONS

Our study highlights the potential role of NMI in assessing the development and prognosis of HBV-ACLF.

Epigenetic Regulation of Endothelial-to-Mesenchymal Transition in Chronic Heart Disease

Endothelial-to-mesenchymal transition (EndMT) is a process in which endothelial cells lose their properties and transform into fibroblast-like cells. This transition process contributes to cardiac fibrosis, a common feature of patients with chronic heart failure. To date, no specific therapies to halt or reverse cardiac fibrosis are available, so knowledge of the underlying mechanisms of cardiac fibrosis is urgently needed. In addition, EndMT contributes to other cardiovascular pathologies such as atherosclerosis and pulmonary hypertension, but also to cancer and organ fibrosis. Remarkably, the molecular mechanisms driving EndMT are largely unknown. Epigenetics play an important role in regulating gene transcription and translation and have been implicated in the EndMT process. Therefore, epigenetics might be the missing link in unraveling the underlying mechanisms of EndMT. Here, we review the involvement of epigenetic regulators during EndMT in the context of cardiac fibrosis. The role of DNA methylation, histone modifications (acetylation and methylation), and noncoding RNAs (microRNAs, long noncoding RNAs, and circular RNAs) in the facilitation and inhibition of EndMT are discussed, and potential therapeutic epigenetic targets will be highlighted.

Enhancer of Zeste Homologue 2 Inhibition Attenuates TGF-β Dependent Hepatic Stellate Cell Activation and Liver Fibrosis

BACKGROUND & AIMS

Transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts is a key event in the pathogenesis of liver fibrosis. Transforming growth factor β (TGF-β) and platelet-derived growth factor (PDGF) are canonical HSC activators after liver injury. The aim of this study was to analyze the epigenetic modulators that differentially control TGF-β and PDGF signaling pathways.

METHODS

We performed a transcriptomic comparison of HSCs treated with TGF-β or PDGF-BB using RNA sequencing. Among the targets that distinguish these 2 pathways, we focused on the histone methyltransferase class of epigenetic modulators.

RESULTS

Enhancer of zeste homolog 2 (EZH2) was expressed differentially, showing significant up-regulation in HSCs activated with TGF-β but not with PDGF-BB. Indeed, EZH2 inhibition using either a pharmacologic (GSK-503) or a genetic (small interfering RNA) approach caused a significant attenuation of TGF-β-induced fibronectin, collagen 1α1, and α-smooth muscle actin, both at messenger RNA and protein levels. Conversely, adenoviral overexpression of EZH2 in HSCs resulted in a significant stimulation of fibronectin protein and messenger RNA levels in TGF-β-treated cells. Finally, we conducted in vivo experiments with mice chronically treated with carbon tetrachloride or bile duct ligation. Administration of GSK-503 to mice receiving either carbon tetrachloride or bile duct ligation led to attenuated fibrosis as assessed by Trichrome and Sirius red stains, hydroxyproline, and α-smooth muscle actin/collagen protein assays.

CONCLUSIONS

TGF-β and PDGF share redundant and distinct transcriptomic targets, with the former predominating in HSC activation. The EZH2 histone methyltransferase is preferentially involved in the TGF-β as opposed to the PDGF signaling pathway. Inhibition of EZH2 attenuates fibrogenic gene transcription in TGF-β-treated HSCs and reduces liver fibrosis in vivo. The data discussed in this publication have been deposited in NCBI's Gene Expression Omnibus and are accessible through GEO Series accession number GSE119606 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE119606).