Super enhancer regulation of cytokine-induced chemokine production in alcoholic hepatitis

Portal Fibrosis and the Ductular Reaction: Pathophysiological Role in the Progression of Liver Disease and Translational Opportunities

A consistent feature of chronic liver diseases and the hallmark of pathologic repair is the so-called "ductular reaction." This is a histologic abnormality characterized by an expansion of dysmorphic cholangiocytes inside and around portal spaces infiltrated by inflammatory, mesenchymal, and vascular cells. The ductular reaction is a highly regulated response based on the reactivation of morphogenetic signaling mechanisms and a complex crosstalk among a multitude of cell types. The nature and mechanism of these exchanges determine the difference between healthy regenerative liver repair and pathologic repair. An orchestrated signaling among cell types directs mesenchymal cells to deposit a specific extracellular matrix with distinct physical and biochemical properties defined as portal fibrosis. Progression of fibrosis leads to vast architectural and vascular changes known as "liver cirrhosis." The signals regulating the ecology of this microenvironment are just beginning to be addressed. Contrary to the tumor microenvironment, immune modulation inside this "benign" microenvironment is scarcely known. One of the reasons for this is that both the ductular reaction and portal fibrosis have been primarily considered a manifestation of cholestatic liver disease, whereas this phenomenon is also present, albeit with distinctive features, in all chronic human liver diseases. Novel human-derived cellular models and progress in "omics" technologies are increasing our knowledge at a fast pace. Most importantly, this knowledge is on the edge of generating new diagnostic and therapeutic advances. Here, we will critically review the latest advances, in terms of mechanisms, pathophysiology, and treatment prospects. In addition, we will delineate future avenues of research, including innovative translational opportunities.

The critical role of the ZBP1-NINJ1 axis and IRF1/IRF9 in ethanol-induced cell death, PANoptosis, and alcohol-associated liver disease

Innate immunity provides the critical first line of defense against infection and sterile triggers. Cell death is a key component of the innate immune response to clear pathogens, but excessive or aberrant cell death can induce inflammation, cytokine storm, and pathology, making it a central molecular mechanism in inflammatory diseases. Alcohol-associated liver disease (ALD) is one such inflammatory disease, but the specific innate immune mechanisms driving pathology in this context remain unclear. Here, by leveraging RNAseq and tissue expression in clinical samples, we identified increased expression of the innate immune sensor Z-DNA binding protein (ZBP1) in patients with ALD. We discovered that ZBP1 expression correlated with ALD progression in patients, and that ethanol induced ZBP1-dependent lytic cell death, PANoptosis, in immune (macrophages, monocytes, Kupffer cells) and non-immune cells (hepatocytes). Mechanistically, the interferon regulatory factors (IRFs) IRF9 and IRF1 upregulated ZBP1 expression, allowing ZBP1 to sense Z-NAs through its Zα2 domain and drive PANoptosis signaling, cell membrane rupture through NINJ1, and DAMP release. Furthermore, the expressions of ZBP1 and NINJ1 were upregulated in both liver and serum samples from patients with ALD. In mouse models of chronic and acute ALD, ZBP1-deficient mice were significantly protected from disease pathology and liver damage. Overall, our findings establish the critical role of the ZBP1-NINJ1 axis regulated by IRFs in driving inflammatory cell death, PANoptosis, in liver cells, suggesting that targeting these molecules will have therapeutic potential in ALD and other inflammatory conditions.

GAMG alleviates liver fibrosis through inducing ferroptosis in inflammatory macrophages via the IRF1/SLC7A11 signaling pathway

The activation of inflammatory macrophages plays a pivotal role in the development of liver fibrosis (LF). Ferroptosis contributes to the clearance of inflammatory macrophages and the release of profibrotic factors. Glycyrrhetic Acid 3-O-Mono-β-d-glucuronide (GAMG) is a natural compound, the potential role of which on LF remains uncertain. In this study, GAMG treatment significantly reduced hepatocyte steatosis, fibroplasia, inflammatory cell infiltration, and collagen fiber deposition in LF mice. In addition, GAMG remarkably decreased the content of collagen protein and improved liver function indicators. Single-cell RNA sequencing revealed that GAMG significantly affected the changes of macrophage subsets in LF, and Funrich analysis identified IRF1 as a key transcription factor regulating the macrophage genome. IRF1 was significantly increased while ferroptosis related SLC7A11 was significantly down-regulated in GAMG treated inflammatory macrophages. Mass spectrometry metabolomics analysis showed that GAMG significantly affected metabolites associated with LF. In vivo and in vitro experiments further verified that GAMG induced ferroptosis of inflammatory macrophages through the IRF1/SLC7A11 axis, and ultimately alleviated LF. Therefore, GAMG induces ferroptosis of inflammatory macrophages by activating the IRF1/SLC7A11 axis, which provides a new strategy for the treatment of LF.

Endoplasmic reticulum stress-related super enhancer promotes epithelial-mesenchymal transformation in hepatocellular carcinoma through CREB5 mediated activation of TNC

Super-enhancers (SEs) are associated with key genes that control cellular state and cell identity. Endoplasmic reticulum stress (ERS) regulates epithelial-mesenchymal transformation (EMT). However, whether SEs are involved in ERS-related activation of EMT in hepatocellular carcinoma (HCC) is unknown. In this study, we identified 17 ERS-related SEs by comparing ERS-HCC cells with untreated control cells using ChIP-seq and RNA-seq. CRISPR-Cas9 and RT-qPCR identified CAMP responsive element binding protein 5 (CREB5) as a key target of ERS-related SE. Analyses of TCGA datasets and tissue arrays showed that CREB5 mRNA and protein expression levels were higher in liver cancer tissues than in paired normal tissues. In addition, overexpression of CREB5 was associated with poor prognosis and an aggressive phenotype in patients with HCC. We also found that activation of ERS enhanced the expression of CREB5, and upregulation of CREB5 significantly increased cell proliferation, migration, and invasion, and promoted EMT, but inhibited apoptosis. More importantly, ERS activation increased the expression of several EMT markers by modulating the expression of CREB5. Mechanistically, CREB5 upregulates the transcription of tenascin-C (TNC) by directly binding to its promoter region, thereby promoting EMT in liver cancer cells. In summary, our findings suggest that ERS activation promotes EMT in liver cancer cells via SE-mediated upregulation of the CREB5/TNC pathway. This result provides a new direction for uncovering how ERS regulates EMT and a foundation for preventing the progression of EMT in HCC.

Liver diseases: epidemiology, causes, trends and predictions

As a highly complex organ with digestive, endocrine, and immune-regulatory functions, the liver is pivotal in maintaining physiological homeostasis through its roles in metabolism, detoxification, and immune response. Various factors including viruses, alcohol, metabolites, toxins, and other pathogenic agents can compromise liver function, leading to acute or chronic injury that may progress to end-stage liver diseases. While sharing common features, liver diseases exhibit distinct pathophysiological, clinical, and therapeutic profiles. Currently, liver diseases contribute to approximately 2 million deaths globally each year, imposing significant economic and social burdens worldwide. However, there is no cure for many kinds of liver diseases, partly due to a lack of thorough understanding of the development of these liver diseases. Therefore, this review provides a comprehensive examination of the epidemiology and characteristics of liver diseases, covering a spectrum from acute and chronic conditions to end-stage manifestations. We also highlight the multifaceted mechanisms underlying the initiation and progression of liver diseases, spanning molecular and cellular levels to organ networks. Additionally, this review offers updates on innovative diagnostic techniques, current treatments, and potential therapeutic targets presently under clinical evaluation. Recent advances in understanding the pathogenesis of liver diseases hold critical implications and translational value for the development of novel therapeutic strategies.

Alcohol-associated liver disease: Natural history, management and novel targeted therapies

Alcohol consumption is a leading cause of preventable morbidity and mortality worldwide and the primary cause of advanced liver disease. Alcohol use disorder is a chronic, frequently relapsing condition characterized by persistent alcohol consumption despite its negative consequences. Alcohol-associated liver disease (ALD) encompasses a series of stages, from fatty liver (steatosis) to inflammation (steatohepatitis), fibrosis, and, ultimately, liver cirrhosis and its complications. The development of ALD is complex, involving both genetic and environmental factors, yet the exact mechanisms at play remain unclear. Alcohol-associated hepatitis (AH), a severe form of ALD, presents with sudden jaundice and liver failure. Currently, there are no approved targeted therapies able to interfere in the pathogenesis of ALD to stop the progression of the disease, making alcohol abstinence the most effective way to improve prognosis across all stages of ALD. For patients with advanced ALD who do not respond to medical therapy, liver transplantation is the only option that can improve prognosis. Recently, AH has become an early indication for liver transplantation in non-responders to medical treatment, showing promising results in carefully selected patients. This review provides an update on the epidemiology, natural history, pathogenesis, and current treatments for ALD. A deeper insight into novel targeted therapies investigated for AH focusing on new pathophysiologically-based agents is also discussed, including anti-inflammatory and antioxidative stress drugs, gut-liver axis modulators, and hepatocyte regenerative molecules.

Alcohol-Induced Activation of Chemokine System and Neuroinflammation Development

Chemokines are immunoregulatory proteins with pleiotropic functions involved in neuromodulation, neurogenesis, and neurotransmission. The way chemokines affect the CNS plays an important role in modulating various conditions that could have negative impact on CNS functions, including development of alcohol use disorders. In this review, we analyzed the literature data available on the problem of chemokine participation in pathogenesis, clinical presentation, and remission of alcohol use disorders both in animal models and in the study of patients with alcoholism. The presented information confirms the hypothesis that the alcohol-induced chemokine production could modulate chronic neuroinflammation. Thus, the data summarized and shown in this review are focused on the relevant direction of research in the field of psychiatry, which is in demand by both scientists and clinical specialists.

Angiocrine signaling in sinusoidal homeostasis and liver diseases

The hepatic sinusoids are composed of liver sinusoidal endothelial cells (LSECs), which are surrounded by hepatic stellate cells (HSCs) and contain liver-resident macrophages called Kupffer cells, and other patrolling immune cells. All these cells communicate with each other and with hepatocytes to maintain sinusoidal homeostasis and a spectrum of hepatic functions under healthy conditions. Sinusoidal homeostasis is disrupted by metabolites, toxins, viruses, and other pathological factors, leading to liver injury, chronic liver diseases, and cirrhosis. Alterations in hepatic sinusoids are linked to fibrosis progression and portal hypertension. LSECs are crucial regulators of cellular crosstalk within their microenvironment via angiocrine signaling. This review discusses the mechanisms by which angiocrine signaling orchestrates sinusoidal homeostasis, as well as the development of liver diseases. Here, we summarise the crosstalk between LSECs, HSCs, hepatocytes, cholangiocytes, and immune cells in health and disease and comment on potential novel therapeutic methods for treating liver diseases.

Genome Restructuring around Innate Immune Genes in Monocytes in Alcohol-associated Hepatitis

Many inflammatory genes in the immune system are clustered in the genome. The 3D genome architecture of these clustered genes likely plays a critical role in their regulation and alterations to this structure may contribute to diseases where inflammation is poorly controlled. Alcohol-associated hepatitis (AH) is a severe inflammatory disease that contributes significantly to morbidity in alcohol associated liver disease. Monocytes in AH are hyper-responsive to inflammatory stimuli and contribute significantly to inflammation. We performed high throughput chromatin conformation capture (Hi-C) technology on monocytes isolated from 4 AH patients and 4 healthy controls to better understand how genome structure is altered in AH. Most chromosomes from AH and healthy controls were significantly dissimilar from each other. Comparing AH to HC, many regions of the genome contained significant changes in contact frequency. While there were alterations throughout the genome, there were a number of hotspots containing a higher density of changes in structure. A few of these hotspots contained genes involved in innate immunity including the NK-gene receptor complex and the CXC-chemokines. Finally, we compare these results to scRNA-seq data from patients with AH challenged with LPS to predict how chromatin conformation impacts transcription of clustered immune genes. Together, these results reveal changes in the chromatin structure of monocytes from AH patients that perturb expression of highly clustered proinflammatory genes.

Super-enhancer-driven LIF promotes the mesenchymal transition in glioblastoma by activating ITGB2 signaling feedback in microglia

BACKGROUND

The mesenchymal (MES) subtype of glioblastoma (GBM) is believed to be influenced by both cancer cell-intrinsic alterations and extrinsic cellular interactions, yet the underlying mechanisms remain unexplored.

METHODS

Identification of microglial heterogeneity by bioinformatics analysis. Transwell migration, invasion assays, and tumor models were used to determine gene function and the role of small molecule inhibitors. RNA sequencing, chromatin immunoprecipitation, and dual-luciferase reporter assays were performed to explore the underlying regulatory mechanisms.

RESULTS

We identified the inflammatory microglial subtype of tumor-associated microglia (TAM) and found that its specific gene integrin beta 2 (ITGB2) was highly expressed in TAM of MES GBM tissues. Mechanistically, the activation of ITGB2 in microglia promoted the interaction between the SH2 domain of STAT3 and the cytoplasmic domain of ITGB2, thereby stimulating the JAK1/STAT3/IL-6 signaling feedback to promote the MES transition of GBM cells. Additionally, microglia communicated with GBM cells through the interaction between the receptor ITGB2 on microglia and the ligand ICAM-1 on GBM cells, while an increased secretion of ICAM-1 was induced by the proinflammatory cytokine leukemia inhibitory factor (LIF). Further studies demonstrated that inhibition of cyclin-dependent kinase 7 substantially reduced the recruitment of SNW1 to the super-enhancer of LIF, resulting in transcriptional inhibition of LIF. We identified notoginsenoside R1 as a novel LIF inhibitor that exhibited synergistic effects in combination with temozolomide.

CONCLUSIONS

Our research reveals that the epigenetic-mediated interaction of GBM cells with TAM drives the MES transition of GBM and provides a novel therapeutic avenue for patients with MES GBM.

Epigenetic regulation of key gene of PCK1 by enhancer and super-enhancer in the pathogenesis of fatty liver hemorrhagic syndrome

OBJECTIVE

Rare study of the non-coding and regulatory regions of the genome limits our ability to decode the mechanisms of fatty liver hemorrhage syndrome (FLHS) in chickens.

METHODS

Herein, we constructed the high-fat diet-induced FLHS chicken model to investigate the genome-wide active enhancers and transcriptome by H3K27ac target chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-Seq) profiles of normal and FLHS liver tissues. Concurrently, an integrative analysis combining ChIP-seq with RNA-Seq and a comparative analysis with chicken FLHS, rat non-alcoholic fatty liver disease (NAFLD) and human NAFLD at the transcriptome level revealed the enhancer and super enhancer target genes and conservative genes involved in metabolic processes.

RESULTS

In total, 56 and 199 peak-genes were identified in upregulated peak-genes positively regulated by H3K27ac (Cor (peak-gene correlation) ≥0.5 and log2(FoldChange) ≥1) (PP) and downregulated peak-genes positively regulated by H3K27ac (Cor (peak-gene correlation) ≥0.5 and log2(FoldChange)≤-1) (PN), respectively; then we screened key regulatory targets mainly distributing in lipid metabolism (PCK1, APOA4, APOA1, INHBE) and apoptosis (KIT, NTRK2) together with MAPK and PPAR signaling pathway in FLHS. Intriguingly, PCK1 was also significantly covered in up-regulated super-enhancers (SEs), which further implied the vital role of PCK1 during the development of FLHS.

CONCLUSION

Together, our studies have identified potential therapeutic biomarkers of PCK1 and elucidated novel insights into the pathogenesis of FLHS, especially for the epigenetic perspective.

A specific super-enhancer actuated by berberine regulates EGFR-mediated RAS-RAF1-MEK1/2-ERK1/2 pathway to induce nasopharyngeal carcinoma autophagy

Nasopharyngeal carcinoma (NPC), primarily found in the southern region of China, is a malignant tumor known for its highly metastatic characteristics. The high mortality rates caused by the distant metastasis and disease recurrence remain unsolved clinical problems. In clinic, the berberine (BBR) compound has widely been in NPC therapy to decrease metastasis and disease recurrence, and BBR was documented as a main component with multiple anti-NPC effects. However, the mechanism by which BBR inhibits the growth and metastasis of nasopharyngeal carcinoma remains elusive. Herein, we show that BBR effectively inhibits the growth, metastasis, and invasion of NPC via inducing a specific super enhancer (SE). From a mechanistic perspective, the RNA sequencing (RNA-seq) results suggest that the RAS-RAF1-MEK1/2-ERK1/2 signaling pathway, activated by the epidermal growth factor receptor (EGFR), plays a significant role in BBR-induced autophagy in NPC. Blockading of autophagy markedly attenuated the effect of BBR-mediated NPC cell growth and metastasis inhibition. Notably, BBR increased the expression of EGFR by transcription, and knockout of EGFR significantly inhibited BBR-induced microtubule associated protein 1 light chain 3 (LC3)-II increase and p62 inhibition, proposing that EGFR plays a pivotal role in BBR-induced autophagy in NPC. Chromatin immunoprecipitation sequencing (ChIP-seq) results found that a specific SE existed only in NPC cells treated with BBR. This SE knockdown markedly repressed the expression of EGFR and phosphorylated EGFR (EGFR-p) and reversed the inhibition of BBR on NPC proliferation, metastasis, and invasion. Furthermore, BBR-specific SE may trigger autophagy by enhancing EGFR gene transcription, thereby upregulating the RAS-RAF1-MEK1/2-ERK1/2 signaling pathway. In addition, in vivo BBR effectively inhibited NPC cells growth and metastasis, following an increase LC3 and EGFR and a decrease p62. Collectively, this study identifies a novel BBR-special SE and established a new epigenetic paradigm, by which BBR regulates autophagy, inhibits proliferation, metastasis, and invasion. It provides a rationale for BBR application as the treatment regime in NPC therapy in future.

Neutrophil and macrophage crosstalk might be a potential target for liver regeneration

The regenerative capability of the liver is remarkable, but further research is required to understand the role that neutrophils play in this process. In the present study, we reanalyzed single-cell RNA sequencing data from a mouse partial hepatectomy (PH) model to track the transcriptional changes in hepatocytes and non-parenchymal cells. Notably, we unraveled the regenerative capacity of hepatocytes at diverse temporal points after PH, unveiling the contributions of three distinct zones in the liver regeneration process. In addition, we observed that the depletion of neutrophils reduced the survival and liver volume after PH, confirming the important role of neutrophils in liver regeneration. CellChat analysis revealed an intricate crosstalk between neutrophils and macrophages promoting liver regeneration and, using weighted gene correlation network analysis, we identified the most significant genetic module associated with liver regeneration. Our study found that hepatocytes in the periportal zone of the liver are more active than in other zones, suggesting that the crosstalk between neutrophils and macrophages might be a potential target for liver regeneration treatment.

Liver sinusoidal endothelial cells contribute to portal hypertension through collagen type IV-driven sinusoidal remodeling

Portal hypertension (PHTN) is a severe complication of liver cirrhosis and is associated with intrahepatic sinusoidal remodeling induced by sinusoidal resistance and angiogenesis. Collagen type IV (COL4), a major component of basement membrane, forms in liver sinusoids upon chronic liver injury. However, the role, cellular source, and expression regulation of COL4 in liver diseases are unknown. Here, we examined how COL4 is produced and how it regulates sinusoidal remodeling in fibrosis and PHTN. Human cirrhotic liver sample RNA sequencing showed increased COL4 expression, which was further verified via immunofluorescence staining. Single-cell RNA sequencing identified liver sinusoidal endothelial cells (LSECs) as the predominant source of COL4 upregulation in mouse fibrotic liver. In addition, COL4 was upregulated in a TNF-α/NF-κB-dependent manner through an epigenetic mechanism in LSECs in vitro. Indeed, by utilizing a CRISPRi-dCas9-KRAB epigenome-editing approach, epigenetic repression of the enhancer-promoter interaction showed silencing of COL4 gene expression. LSEC-specific COL4 gene mutation or repression in vivo abrogated sinusoidal resistance and angiogenesis, which thereby alleviated sinusoidal remodeling and PHTN. Our findings reveal that LSECs promote sinusoidal remodeling and PHTN during liver fibrosis through COL4 deposition.

Super enhancer-associated circRNA-circLrch3 regulates hypoxia-induced pulmonary arterial smooth muscle cells pyroptosis by formation of R-loop with host gene

BACKGROUND

Pulmonary hypertension (PH) is a complex vascular disorder, characterized by pulmonary vessel remodeling and perivascular inflammation. Pulmonary arterial smooth muscle cells (PASMCs) pyroptosis is a novel pathological mechanism implicated of pulmonary vessel remodeling. However, the involvement of circRNAs in the process of pyroptosis and the underlying regulatory mechanisms remain inadequately understood.

METHODS

Western blotting, PI staining and LDH release were used to explore the role of circLrch3 in PASMCs pyroptosis. Moreover, S9.6 dot blot and DRIP-PCR were used to assess the formation of R-loop between circLrch3 and its host gene Lrch3. Chip-qPCR were used to evaluate the mechanism of super enhancer-associated circLrh3, which is transcriptionally activated by the transcription factor Tbx2.

RESULTS

CircLrch3 was markedly upregulated in hypoxic PASMCs. CircLrch3 knockdown inhibited hypoxia induced PASMCs pyroptosis in vivo and in vitro. Mechanistically, circLrch3 can form R-loop with host gene to upregulate the protein and mRNA expression of Lrch3. Furthermore, super enhancer interacted with the Tbx2 at the Lrch3 promoter locus, mediating the augmented transcription of circLrch3.

CONCLUSION

Our findings clarify the role of a super enhancer-associated circLrch3 in the formation of R-loop with the host gene Lrch3 to modulate pyroptosis in PASMCs, ultimately promoting the development of PH.

Inflammation in Alcohol-Associated Hepatitis: Pathogenesis and Therapeutic Targets

Alcohol-associated hepatitis (AH) is an acute-on-chronic liver injury that occurs in patients with chronic alcohol-associated liver disease (ALD). Patients with severe AH have high short-term mortality and lack effective pharmacologic therapies. Inflammation is believed to be one of the key factors promoting AH progression and has been actively investigated as therapeutic targets over the last several decades, but no effective inflammatory targets have been identified so far. In this review, we discuss how inflammatory cells and the inflammatory mediators produced by these cells contribute to the development and progression of AH, with focus on neutrophils and macrophages. The crosstalk between inflammatory cells and liver nonparenchymal cells in the pathogenesis of AH is elaborated. We also deliberate the application of recent cutting-edge technologies in characterizing liver inflammation in AH. Finally, the potential therapeutic targets of inflammatory mediators for AH are briefly summarized.

Super enhancer lncRNAs: a novel hallmark in cancer

Super enhancers (SEs) consist of clusters of enhancers, harboring an unusually high density of transcription factors, mediator coactivators and epigenetic modifications. SEs play a crucial role in the maintenance of cancer cell identity and promoting oncogenic transcription. Super enhancer lncRNAs (SE-lncRNAs) refer to either transcript from SEs locus or interact with SEs, whose transcriptional activity is highly dependent on SEs. Moreover, these SE-lncRNAs can interact with their associated enhancer regions in cis and modulate the expression of oncogenes or key signal pathways in cancers. Inhibition of SEs would be a promising therapy for cancer. In this review, we summarize the research of SE-lncRNAs in different kinds of cancers so far and decode the mechanism of SE-lncRNAs in carcinogenesis to provide novel ideas for the cancer therapy.

The "Domino effect" in MASLD: The inflammatory cascade of steatohepatitis

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an increasingly common complication of obesity, affecting over a quarter of the global adult population. A key event in the pathophysiology of MASLD is the development of metabolic-associated steatohepatitis (MASH), which greatly increases the chances of developing cirrhosis and hepatocellular carcinoma. The underlying cause of MASH is multifactorial, but accumulating evidence indicates that the inflammatory process in the hepatic microenvironment typically follows a pattern that can be roughly divided into three stages: (1) Detection of hepatocyte stress by tissue-resident immune cells including γδ T cells and CD4-CD8- double-negative T cells, followed by their secretion of pro-inflammatory mediators, most notably IL-17A. (2) Recruitment of pro-inflammatory cells, mostly of the myeloid lineage, and initiation of inflammation through secretion of effector-type cytokines such as TNF, TGF-β, and IL-1β. (3) Escalation of the inflammatory response by recruitment of lymphocytes including Th17, CD8 T, and B cells leading to chronic inflammation, hepatic stellate cell activation, and fibrosis. Here we will discuss these three stages and how they are consecutively linked like falling domino tiles to the pathophysiology of MASH. Moreover, we will highlight the clinical potential of inflammation as a biomarker and therapeutic target for the treatment of MASLD.

Alcohol-Associated Liver Disease Outcomes: Critical Mechanisms of Liver Injury Progression

Alcohol-associated liver disease (ALD) is a substantial cause of morbidity and mortality worldwide and represents a spectrum of liver injury beginning with hepatic steatosis (fatty liver) progressing to inflammation and culminating in cirrhosis. Multiple factors contribute to ALD progression and disease severity. Here, we overview several crucial mechanisms related to ALD end-stage outcome development, such as epigenetic changes, cell death, hemolysis, hepatic stellate cells activation, and hepatic fatty acid binding protein 4. Additionally, in this review, we also present two clinically relevant models using human precision-cut liver slices and hepatic organoids to examine ALD pathogenesis and progression.

Circulating cytokines and alcoholic liver disease: a two-sample bidirectional Mendelian randomization study

BACKGROUND

Increased inflammation in the liver during ethanol exposure is a major feature of alcoholic liver disease (ALD). An important contributing component to the development of ALD is the inflammatory response brought on by immunological response, however the connection between individual circulating cytokines and ALD is still unclear. To ascertain the causation, we conducted a two-sample bidirectional Mendelian randomization research.

METHODS

We extracted 41 cytokines and growth factors of 8293 Europeans and ALD cases of the same ethnicity (1416 cases and 217,376 controls) from the Genome-Wide Association Studies (GWAS) database for two-sample bidirectional MR analysis.

RESULTS

Our analyses suggest that higher interleukin-7 (IL-7) levels are associated with an increased risk of ALD (p = 0.028, OR = 1.191,95% CI = 1.019-1.392), while tumor necrosis factor related apoptosis inducing ligand (TRAIL) is a protective factor for ALD (p = 0.032, OR = 0.863, 95% CI = 0.754-0.988) which can reduce the risk of disease occurrence. In addition, genetically predicted ALD does not affect the expression of circulating cytokines regulators.

CONCLUSIONS

Our study supports that cytokines play a pivotal role in the pathogenesis of ALD. To determine the mechanisms and pathways of action of these biomarkers, further basic research is required to ensure their clinical suitability for preventing and treating ALD.

Alcohol-associated liver disease

Alcohol-associated liver disease (ALD) is a major cause of chronic liver disease worldwide, and comprises a spectrum of several different disorders, including simple steatosis, steatohepatitis, cirrhosis, and superimposed hepatocellular carcinoma. Although tremendous progress has been made in the field of ALD over the last 20 years, the pathogenesis of ALD remains obscure, and there are currently no FDA-approved drugs for the treatment of ALD. In this Review, we discuss new insights into the pathogenesis and therapeutic targets of ALD, utilizing the study of multiomics and other cutting-edge approaches. The potential translation of these studies into clinical practice and therapy is deliberated. We also discuss preclinical models of ALD, interplay of ALD and metabolic dysfunction, alcohol-associated liver cancer, the heterogeneity of ALD, and some potential translational research prospects for ALD.

The intersection between alcohol-related liver disease and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD) are the leading causes of chronic liver disease worldwide. NAFLD and ALD share pathophysiological, histological and genetic features and both alcohol and metabolic dysfunction coexist as aetiological factors in many patients with hepatic steatosis. A diagnosis of NAFLD requires the exclusion of significant alcohol consumption and other causes of liver disease. However, data suggest that significant alcohol consumption is often under-reported in patients classified as having NAFLD and that alcohol and metabolic factors interact to exacerbate the progression of liver disease. In this Review, we analyse existing data on the interaction between alcohol consumption and metabolic syndrome as well as the overlapping features and differences in the pathogenesis of ALD and NAFLD. We also discuss the clinical implications of the coexistence of alcohol consumption, of any degree, in patients with evidence of metabolic derangement as well as the use of alcohol biomarkers to detect alcohol intake. Finally, we summarize the evolving nomenclature of fatty liver disease and describe a recent proposal to classify patients at the intersection of NAFLD and ALD. We propose that, regardless of the presumed aetiology, patients with fatty liver disease should be evaluated for both metabolic syndrome and alcohol consumption to enable better prognostication and a personalized medicine approach.

CXCL6: A potential therapeutic target for inflammation and cancer

Chemokines were originally defined as cytokines that affect the movement of immune cells. In recent years, due to the increasing importance of immune cells in the tumor microenvironment (TME), the role of chemokines has changed from a single "chemotactic agent" to a key factor that can regulate TME and affect the tumor phenotype. CXCL6, also known as granulocyte chemoattractant protein-2 (GCP-2), can recruit neutrophils to complete non-specific immunity in the process of inflammation. Cancer-related genes and interleukin family can promote the abnormal secretion of CXCL6, which promotes tumor growth, metastasis, epithelial mesenchymal transformation (EMT) and angiogenesis in the TME. CXCL6 also has a role in promoting fibrosis and tissue damage repair. In this review, we focus on the regulatory network affecting CXCL6 expression, its role in the progress of inflammation and how it affects tumorigenesis and progression based on the TME, in an attempt to provide a potential target for the treatment of diseases such as inflammation and cancer.

Cell-Specific Regulation of Inflammatory Cytokines and Acute-Phase Proteins by the Glucocorticoid Receptor

BACKGROUND

Literature and data mining found abnormal induction of chemokine (C-X-C motif) ligand 1 (CXCL1) and CXCL8 and down-regulation of CXCL2 in inflammatory liver diseases. This study was performed to understand the glucocorticoid receptor's (GR's) effects on chemokine and acute-phase protein expression in human liver, in settings of bacterial infection (modeled using LPS) or inflammation (modeled using TNFα).

METHODS

Primary human hepatocytes (PHH) were treated with combinations of tumor necrosis factor alpha (TNFα), lipopolysaccharide (LPS), and dexamethasone (DEX) for 24 h, following which chemokine mRNA and protein expression were analyzed using qPCR and enzyme-linked immunosorbent assay assays. Dual luciferase assays were performed on transfected cell lines. Mutant CXCL2 promoters were used in dual luciferase assays to identify specific regions of the CXCL2 promoter affected by GR, TNFα, or hepatocyte nuclear factor 4α (HNF4α, a liver-enriched transcription factor).

RESULTS

In PHH from donor 1, GR strongly inhibited LPS-induced CXCL1 and CXCL8 translation and transcription, whereas CXCL2 transcription tended to increase with DEX treatment. In PHH from donor 2, DEX treatment inhibited protein expression and secretion of CXCL1 and CXCL8 induced by TNFα and/or LPS, whereas CXCL2 upregulation was largely unaffected by DEX treatment. In nonliver HEK293T cells GR activity inhibited CXCL2 promoter activity. However, in liver-derived HEPG2 cells, GR induced CXCL2 promoter activity. A 407-base pair region upstream of CXCL2 promoter is necessary for full GR functionality in HEPG2 cells. TNFα synergized with HNF4α in inducing CXCL2 promoter activity in HEPG2 cells.

CONCLUSIONS

GR's effects on chemokine expression are cell-type specific and chemokine specific. GR down-regulated CXCL1 and CXCL8 in different cell types, whereas the specific activation of CXCL2 in hepatocytes and down-regulation of CXCL2 in nonhepatocytes by GR appears due to cell-specific utilization of CXCL2 promoter. By specifically increasing GR activity in the liver, we may normalize chemokine imbalances and prevent sepsis in inflammatory liver diseases.

Post-translational modifications of histone and non-histone proteins in epigenetic regulation and translational applications in alcohol-associated liver disease: Challenges and research opportunities

Epigenetic regulation is a process that takes place through adaptive cellular pathways influenced by environmental factors and metabolic changes to modulate gene activity with heritable phenotypic variations without altering the DNA sequences of many target genes. Epigenetic regulation can be facilitated by diverse mechanisms: many different types of post-translational modifications (PTMs) of histone and non-histone nuclear proteins, DNA methylation, altered levels of noncoding RNAs, incorporation of histone variants, nucleosomal positioning, chromatin remodeling, etc. These factors modulate chromatin structure and stability with or without the involvement of metabolic products, depending on the cellular context of target cells or environmental stimuli, such as intake of alcohol (ethanol) or Western-style high-fat diets. Alterations of epigenetics have been actively studied, since they are frequently associated with multiple disease states. Consequently, explorations of epigenetic regulation have recently shed light on the pathogenesis and progression of alcohol-associated disorders. In this review, we highlight the roles of various types of PTMs, including less-characterized modifications of nuclear histone and non-histone proteins, in the epigenetic regulation of alcohol-associated liver disease (ALD) and other disorders. We also describe challenges in characterizing specific PTMs and suggest future opportunities for basic and translational research to prevent or treat ALD and many other disease states.

A body map of super-enhancers and their function in pig

Introduction

Super-enhancers (SEs) are clusters of enhancers that act synergistically to drive the high-level expression of genes involved in cell identity and function. Although SEs have been extensively investigated in humans and mice, they have not been well characterized in pigs.

Methods

Here, we identified 42,380 SEs in 14 pig tissues using chromatin immunoprecipitation sequencing, and statistics of its overall situation, studied the composition and characteristics of SE, and explored the influence of SEs characteristics on gene expression.

Results

We observed that approximately 40% of normal enhancers (NEs) form SEs. Compared to NEs, we found that SEs were more likely to be enriched with an activated enhancer and show activated functions. Interestingly, SEs showed X chromosome depletion and short interspersed nuclear element enrichment, implying that SEs play an important role in sex traits and repeat evolution. Additionally, SE-associated genes exhibited higher expression levels and stronger conservation than NE-associated genes. However, genes with the largest SEs had higher expression levels than those with the smallest SEs, indicating that SE size may influence gene expression. Moreover, we observed a negative correlation between SE gene distance and gene expression, indicating that the proximity of SEs can affect gene activity. Gene ontology enrichment and motif analysis revealed that SEs have strong tissue-specific activity. For example, the CORO2B gene with a brain-specific SE shows strong brain-specific expression, and the phenylalanine hydroxylase gene with liver-specific SEs shows strong liver-specific expression.

Discussion

In this study, we illustrated a body map of SEs and explored their functions in pigs, providing information on the composition and tissue-specific patterns of SEs. This study can serve as a valuable resource of gene regulatory and comparative analyses to the scientific community and provides a theoretical reference for genetic control mechanisms of important traits in pigs.

CRISPR/dCas9 Tools: Epigenetic Mechanism and Application in Gene Transcriptional Regulation

CRISPR/Cas9-mediated cleavage of DNA, which depends on the endonuclease activity of Cas9, has been widely used for gene editing due to its excellent programmability and specificity. However, the changes to the DNA sequence that are mediated by CRISPR/Cas9 affect the structures and stability of the genome, which may affect the accuracy of results. Mutations in the RuvC and HNH regions of the Cas9 protein lead to the inactivation of Cas9 into dCas9 with no endonuclease activity. Despite the loss of endonuclease activity, dCas9 can still bind the DNA strand using guide RNA. Recently, proteins with active/inhibitory effects have been linked to the end of the dCas9 protein to form fusion proteins with transcriptional active/inhibitory effects, named CRISPRa and CRISPRi, respectively. These CRISPR tools mediate the transcription activity of protein-coding and non-coding genes by regulating the chromosomal modification states of target gene promoters, enhancers, and other functional elements. Here, we highlight the epigenetic mechanisms and applications of the common CRISPR/dCas9 tools, by which we hope to provide a reference for future related gene regulation, gene function, high-throughput target gene screening, and disease treatment.

The role of neutrophils in alcohol-related hepatitis

Alcohol-related liver disease is a major cause of liver disease-associated mortality, with inpatient care being a major contributor to its clinical and economic burden. Alcohol-related hepatitis (AH) is an acute inflammatory form of alcohol-related liver disease. Severe AH is associated with high short-term mortality, with infection being a common cause of death. The presence of AH is associated with increased numbers of circulating and hepatic neutrophils. We review the literature on the role of neutrophils in AH. In particular, we explain how neutrophils are recruited to the inflamed liver and how their antimicrobial functions (chemotaxis, phagocytosis, oxidative burst, NETosis) may be altered in AH. We highlight evidence for the existence of 'high-density' and 'low-density' neutrophil subsets. We also describe the potentially beneficial roles of neutrophils in the resolution of injury in AH through their effects on macrophage polarisation and hepatic regeneration. Finally, we discuss how manipulation of neutrophil recruitment/function may be used as a therapeutic strategy in AH. For example, correction of gut dysbiosis in AH could help to prevent excess neutrophil activation, or treatments could aim to enhance miR-223 function in AH. The development of markers that can reliably distinguish neutrophil subsets and of animal models that accurately reproduce human disease will be crucial for facilitating translational research in this important field.

Management of alcoholic hepatitis: A clinical perspective

Alcohol-associated liver disease is the primary cause of liver-related mortality worldwide and one of the most common indications for liver transplantation. Alcoholic hepatitis represents the most acute and severe manifestation of alcohol-associated liver disease and is characterized by a rapid onset of jaundice with progressive inflammatory liver injury, worsening of portal hypertension, and an increased risk for multiorgan failure in patients with excessive alcohol consumption. Severe alcoholic hepatitis is associated with a poor prognosis and high short-term mortality. During the COVID-19 pandemic, rates of alcohol-associated hepatitis have increased significantly, underscoring that it is a serious and growing health problem. However, adequate management of alcohol-associated hepatitis and its complications in everyday clinical practice remains a major challenge. Currently, pharmacotherapy is limited to corticosteroids, although these have only a moderate effect on reducing short-term mortality. In recent years, translational studies deciphering key mechanisms of disease development and progression have led to important advances in the understanding of the pathogenesis of alcoholic hepatitis. Emerging pathophysiology-based therapeutic approaches include anti-inflammatory agents, modifications of the gut-liver axis and intestinal dysbiosis, epigenetic modulation, antioxidants, and drugs targeting liver regeneration. Concurrently, evidence is increasing that early liver transplantation is a safe treatment option with important survival benefits in selected patients with severe alcoholic hepatitis not responding to medical treatment. This narrative review describes current pathophysiology and management concepts of alcoholic hepatitis, provides an update on emerging treatment options, and focuses on the need for holistic and patient-centred treatment approaches to improve prognosis.

Intestinal Microbiotas and Alcoholic Hepatitis: Pathogenesis and Therapeutic Value

Alcoholic hepatitis (AH) is a rapidly progressing and severe stage of alcoholic liver disease, presenting a grim prognosis. Extensive research has elucidated several underlying mechanisms that contribute to the development of AH, including metabolic alterations, immune stimulation, and intestinal dysbiosis. These pathological changes intricately intertwine during the progression of AH. Notably, recent studies have increasingly highlighted the pivotal role of alterations in the intestinal microbiota in the pathogenesis of AH. Consequently, future investigations should place significant emphasis on exploring the dynamics of intestinal microbiota. In this comprehensive review, we consolidate the primary causes of AH while underscoring the influence of gut microbes. Furthermore, by examining AH treatment strategies, we delineate the potential therapeutic value of interventions targeting the gut microbiota. Given the existing limitations in AH treatment options, we anticipate that this review will contribute to forthcoming research endeavors aimed at advancing AH treatment modalities.

TNFα increases the degradation of pyruvate dehydrogenase kinase 4 by the Lon protease to support proinflammatory genes

The endothelium is a major target of the proinflammatory cytokine, tumor necrosis factor alpha (TNFα). Exposure of endothelial cells (EC) to proinflammatory stimuli leads to an increase in mitochondrial metabolism; however, the function and regulation of elevated mitochondrial metabolism in EC in response to proinflammatory cytokines remain unclear. Studies using high-resolution metabolomics and 13C-glucose and 13C-glutamine labeling flux techniques showed that pyruvate dehydrogenase activity (PDH) and oxidative tricarboxylic acid cycle (TCA) flux are elevated in human umbilical vein ECs in response to overnight (16 h) treatment with TNFα (10 ng/mL). Mechanistic studies indicated that TNFα mediated these metabolic changes via mitochondrial-specific protein degradation of pyruvate dehydrogenase kinase 4 (PDK4, inhibitor of PDH) by the Lon protease via an NF-κB-dependent mechanism. Using RNA sequencing following siRNA-mediated knockdown of the catalytically active subunit of PDH, PDHE1α (PDHA1 gene), we show that PDH flux controls the transcription of approximately one-third of the genes that are up-regulated by TNFα stimulation. Notably, TNFα-induced PDH flux regulates a unique signature of proinflammatory mediators (cytokines and chemokines) but not inducible adhesion molecules. Metabolomics and ChIP sequencing for acetylated modification on lysine 27 of histone 3 (H3K27ac) showed that TNFα-induced PDH flux promotes histone acetylation of specific gene loci via citrate accumulation and ATP-citrate lyase-mediated generation of acetyl CoA. Together, these results uncover a mechanism by which TNFα signaling increases oxidative TCA flux of glucose to support TNFα-induced gene transcription through extramitochondrial acetyl CoA generation and histone acetylation.

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.

MacroH2A restricts inflammatory gene expression in melanoma cancer-associated fibroblasts by coordinating chromatin looping

MacroH2A has established tumour suppressive functions in melanoma and other cancers, but an unappreciated role in the tumour microenvironment. Using an autochthonous, immunocompetent mouse model of melanoma, we demonstrate that mice devoid of macroH2A variants exhibit increased tumour burden compared with wild-type counterparts. MacroH2A-deficient tumours accumulate immunosuppressive monocytes and are depleted of functional cytotoxic T cells, characteristics consistent with a compromised anti-tumour response. Single cell and spatial transcriptomics identify increased dedifferentiation along the neural crest lineage of the tumour compartment and increased frequency and activation of cancer-associated fibroblasts following macroH2A loss. Mechanistically, macroH2A-deficient cancer-associated fibroblasts display increased myeloid chemoattractant activity as a consequence of hyperinducible expression of inflammatory genes, which is enforced by increased chromatin looping of their promoters to enhancers that gain H3K27ac. In summary, we reveal a tumour suppressive role for macroH2A variants through the regulation of chromatin architecture in the tumour stroma with potential implications for human melanoma.

[Alcoholic hepatitis - current and future treatment approaches]

Acute severe alcoholic hepatitis is a serious disease with poor prognosis. As a result of an improved understanding of the underlying pathomechanisms, a variety of new, innovative therapeutic modalities are currently being investigated that may help to improve prognosis. New approaches include the application of anti-inflammatory agents (e.g., interleukin-1 inhibitors), modifications of the gut-liver axis via fecal microbiome transfer or the administration of non-absorbable antibiotics (e.g., rifaximin), and drugs to enhance hepatocellular regeneration (e.g., interleukin-22 agonists). This article describes current management concepts of alcoholic hepatitis and provides an overview of new potential treatment approaches.

Neutrophil subsets in noncancer liver diseases: Cellular crosstalk and therapeutic targets

Neutrophils are the most abundant circulating granulocytes, linking innate and adaptive immunity. Neutrophils can regulate inflammatory and immune responses through degranulation, reactive oxygen species generation, the production of cytokines and chemokines, and NETosis. Emerging evidence has indicated that neutrophils contribute to the pathogenesis of various noncancer liver diseases, including nonalcoholic fatty liver disease, alcohol-associated liver disease, hepatic ischemia-reperfusion injury, and liver fibrosis. Cellular interactions among neutrophils, other immune cells, and nonimmune cells constitute a complex network that regulates the immune microenvironment of the liver. This review summarizes novel neutrophil subtypes, including CD177+ neutrophils and low-density neutrophils. Moreover, we provide an overview of the cellular cros stalk of neutrophils in noncancer liver diseases, aiming to shed new light on mechanistic studies of novel neutrophil subtypes. In addition, we discuss the potential of neutrophils as therapeutic targets in noncancer liver diseases, including inhibitors targeting NETosis, granule proteins, and chemokines.

The evolving role of liver sinusoidal endothelial cells in liver health and disease

LSECs are a unique population of endothelial cells within the liver and are recognized as key regulators of liver homeostasis. LSECs also play a key role in liver disease, as dysregulation of their quiescent phenotype promotes pathological processes within the liver including inflammation, microvascular thrombosis, fibrosis, and portal hypertension. Recent technical advances in single-cell analysis have characterized distinct subpopulations of the LSECs themselves with a high resolution and defined their gene expression profile and phenotype, broadening our understanding of their mechanistic role in liver biology. This article will review 4 broad advances in our understanding of LSEC biology in general: (1) LSEC heterogeneity, (2) LSEC aging and senescence, (3) LSEC role in liver regeneration, and (4) LSEC role in liver inflammation and will then review the role of LSECs in various liver pathologies including fibrosis, DILI, alcohol-associated liver disease, NASH, viral hepatitis, liver transplant rejection, and ischemia reperfusion injury. The review will conclude with a discussion of gaps in knowledge and areas for future research.

Angiocrine Signaling in Sinusoidal Health and Disease

Liver sinusoidal endothelial cells (LSECs) are key players in maintaining hepatic homeostasis. They also play crucial roles during liver injury by communicating with liver cell types as well as immune cells and promoting portal hypertension, fibrosis, and inflammation. Cutting-edge technology, such as single cell and spatial transcriptomics, have revealed the existence of distinct LSEC subpopulations with a clear zonation in the liver. The signals released by LSECs are commonly called "angiocrine signaling." In this review, we summarize the role of angiocrine signaling in health and disease, including zonation in healthy liver, regeneration, fibrosis, portal hypertension, nonalcoholic fatty liver disease, alcohol-associated liver disease, aging, drug-induced liver injury, and ischemia/reperfusion, as well as potential therapeutic advances. In conclusion, sinusoidal endotheliopathy is recognized in liver disease and promising preclinical studies are paving the path toward LSEC-specific pharmacotherapies.

New genetic and epigenetic insights into the chemokine system: the latest discoveries aiding progression toward precision medicine

Over the past thirty years, the importance of chemokines and their seven-transmembrane G protein-coupled receptors (GPCRs) has been increasingly recognized. Chemokine interactions with receptors trigger signaling pathway activity to form a network fundamental to diverse immune processes, including host homeostasis and responses to disease. Genetic and nongenetic regulation of both the expression and structure of chemokines and receptors conveys chemokine functional heterogeneity. Imbalances and defects in the system contribute to the pathogenesis of a variety of diseases, including cancer, immune and inflammatory diseases, and metabolic and neurological disorders, which render the system a focus of studies aiming to discover therapies and important biomarkers. The integrated view of chemokine biology underpinning divergence and plasticity has provided insights into immune dysfunction in disease states, including, among others, coronavirus disease 2019 (COVID-19). In this review, by reporting the latest advances in chemokine biology and results from analyses of a plethora of sequencing-based datasets, we outline recent advances in the understanding of the genetic variations and nongenetic heterogeneity of chemokines and receptors and provide an updated view of their contribution to the pathophysiological network, focusing on chemokine-mediated inflammation and cancer. Clarification of the molecular basis of dynamic chemokine-receptor interactions will help advance the understanding of chemokine biology to achieve precision medicine application in the clinic.

C-C motif chemokine receptor 2 inhibition reduces liver fibrosis by restoring the immune cell landscape

The accumulation of extracellular matrix (ECM) proteins in the liver leads to liver fibrosis and end-stage liver cirrhosis. C-C motif chemokine receptor 2 (CCR2) is an attractive target for treating liver fibrosis. However, limited investigations have been conducted to explore the mechanism by which CCR2 inhibition reduces ECM accumulation and liver fibrosis, which is the focus of this study. Liver injury and liver fibrosis were induced by carbon tetrachloride (CCl₄) in wild-type mice and Ccr2 knockout (Ccr2^-/-) mice. CCR2 was upregulated in murine and human fibrotic livers. Pharmacological CCR2 inhibition with cenicriviroc (CVC) reduced ECM accumulation and liver fibrosis in prevention and treatment administration. In single-cell RNA sequencing (scRNA-seq), CVC was demonstrated to alleviate liver fibrosis by restoring the macrophage and neutrophil landscape. CVC administration and CCR2 deletion can also inhibit the hepatic accumulation of inflammatory FSCN1⁺ macrophages and HERC6⁺ neutrophils. Pathway analysis indicated that the STAT1, NFκB, and ERK signaling pathways might be involved in the antifibrotic effects of CVC. Consistently, Ccr2 knockout decreased phosphorylated STAT1, NFκB, and ERK in the liver. In vitro, CVC could transcriptionally suppress crucial profibrotic genes (Xaf1, Slfn4, Slfn8, Ifi213, and Il1β) in macrophages by inactivating the STAT1/NFκB/ERK signaling pathways. In conclusion, this study depicts a novel mechanism by which CVC alleviates ECM accumulation in liver fibrosis by restoring the immune cell landscape. CVC can inhibit profibrotic gene transcription via inactivating the CCR2-STAT1/NFκB/ERK signaling pathways.

Portal Hypertension in Alcohol-Associated Hepatitis

Purpose of Review

This review article will examine portal hypertension in alcoholic hepatitis (AH) from both a basic mechanistic and a clinical perspective.

Recent Findings

Alcoholic hepatitis is a major public health problem in the USA, accounting for over 300,000 hospital admissions in a recent year of data (Jinjuvadia et al. J Clin Gastroenterol. 60;49:506–511). Portal hypertension is a key consequence of AH and a driver of liver-related morbidity and mortality. Alcohol may directly mediate portal hypertension via multiple possible mechanisms, including increased portal inflow, increased intrahepatic vasoconstriction, inflammation, and changes in the liver vasculature such as perisinusoidal fibrosis and phlebosclerosis.

Summary

Portal hypertension is a key consequence of AH and a critical area for future research.

Liver-Targeted Delivery of Small Interfering RNA of C-C Chemokine Receptor 2 with Tetrahedral Framework Nucleic Acid Attenuates Liver Cirrhosis

Liver cirrhosis is the end stage of chronic liver diseases without approved clinical drugs. In this study, a new strategy that uses a C-C chemokine receptor 2 (CCR2) small interfering RNA silencing (siCcr2)-based therapy by loading multivalent siCcr2 with tetrahedron framework DNA nanostructure (tFNA) vehicle (tFNA-siCcr2) was established to attenuate liver fibrosis. tFNA-siCcr2 was successfully synthesized without changing the physiochemical properties of tFNA. Compared to the naked siCcr2 molecule, the tFNA-siCcr2 complex altered the accumulation from the kidney to the liver after the intraperitoneal injection. The tFNA-siCcr2 complex also prolonged hepatic retention and mainly colocalized within macrophages and endothelial cells. tFNA-siCcr2 efficiently silenced CCR2 and significantly ameliorated liver fibrosis in prevention and treatment interventions. Single-cell RNA sequencing followed by experimental validation suggested that tFNA-siCcr2 can restore the immune cell landscape and construct an antifibrotic niche by inhibiting profibrotic macrophage and neutrophil accumulation in the murine fibrotic liver. Molecularly, the tFNA-siCcr2 complex reduced inflammatory mediator production by inactivating the NF-κB signaling pathway. In conclusion, the tFNA-based liver-targeted tFNA-siCcr2 delivery complex efficiently ameliorated liver fibrosis by restoring the immune cell landscape and constructing an antifibrotic niche, which makes the tFNA-siCcr2 complex a potential therapeutic candidate for the clinical treatment of liver cirrhosis.

Proangiogenic role of circRNA-007371 in liver fibrosis

Circular RNAs (circRNAs) are crucially involved in cancers as competing endogenous RNA (ceRNA) or microRNA (miRNA) sponges. However, the function and mechanism of circRNAs in liver fibrosis remain unknown and are the focus of this study. Murine fibrotic models were induced by thioacetamide (TAA) or carbon tetrachloride (CCl₄ ). Increased angiogenesis is accompanied by liver fibrosis in TAA- and CCl₄ -induced murine fibrotic livers. circRNA microarray and argonaute 2 (AGO2)-RNA immunoprecipitation (RIP) sequencing (AGO2-RIP sequencing) were performed in murine livers to screen for functional circRNAs. Compared to control livers, 86 differentially expressed circRNAs were obtained in TAA-induced murine fibrotic livers using circRNA microarray. In addition, 551 circRNAs were explored by AGO2-RIP sequencing of murine fibrotic livers. The circRNA-007371 was then selected and verified for back-spliced junction, resistance to RNase R, and loop formation. In vitro, murine hemangioendothelioma endothelial (EOMA) cells were transfected with circRNA-007371 overexpressing plasmid or empty plasmid. circRNA-007371 overexpression promoted tube formation, migration, and cell proliferation of EOMA cells. RNA sequencing and miRNA sequencing were then performed to explore the mechanism of the proangiogenic effects of circRNA-007371. circRNA-007371 promotes liver fibrosis via miRNA sponges or ceRNA mechanisms. Stag1, the parent gene of circRNA-007371, may play a significant role in proangiogenic progression. In conclusion, circRNA-007371 enhances angiogenesis via a miRNA sponge mechanism in liver fibrosis. The antiangiogenic effect of circRNA-007371 inhibition may provide a new strategy for treating patients with liver cirrhosis.

Deficiency of NLR family member NLRC5 alleviates alcohol induced hepatic injury and steatosis by enhancing autophagy of hepatocytes

Steatosis is regarded as an early response of the liver to excessive alcohol consumption, which ultimately results in alcoholic liver disease (ALD). Hepatocytes are the primary drivers of the pathological process known as hepatic damage and steatosis, which is characterized by significant fat accumulation and an abundance of fat vacuoles. NLRs, a family member of pattern recognition receptors, have recently been found to be crucial in liver disorders. In this study, we examined the possible impact of NLRC5, the largest NLR family member, on alcohol-induced fatty liver development using a gene knock-out mouse model. The mouse liver was severely damaged and developed steatosis as a result of chronic and excessive ethanol use, and this damage was prevented by the lack of NLRC5. Additionally, NLRC5 deletion reversed ethanol's ability to increase the serum concentrations of TG, T-CHO, ALT, and AST. Absence of NLRC5 reduced ethanol-stimulated aberrant expression of the vital regulators of lipid synthesis and metabolism, SREBP-1c, FAS and PPAR-α. Furthermore, loss- and gain-of-function research indicated that NLRC5 might affect the autophagy pathway in alcohol-induced hepatic steatosis progression. The functional role of NLRC5 in ALD is obviously impacted by the autophagy inducer rapamycin as well as the autophagy inhibitor 3-MA. Our research showed that NLRC5 was involved in ethanol-induced injury and steatosis of the liver, and may be considered a suitable therapeutic target for treating ALD.

Targeting super enhancers for liver disease: a review

Background

Super enhancers (SEs) refer to the ultralong regions of a gene accompanied by multiple transcription factors and cofactors and strongly drive the expression of cell-type-related genes. Recent studies have demonstrated that SEs play crucial roles in regulating gene expression related to cell cycle progression and transcription. Aberrant activation of SEs is closely related to the occurrence and development of liver disease. Liver disease, especially liver failure and hepatocellular carcinoma (HCC), constitutes a major class of diseases that seriously endanger human health. Currently, therapeutic strategies targeting SEs can dramatically prevent disease progression and improve the prognosis of animal models. The associated new approaches to the treatment of related liver disease are relatively new and need systematic elaboration.

Objectives

In this review, we elaborate on the features of SEs and discuss their function in liver disease. Additionally, we review their application prospects in clinical practice in the future. The article would be of interest to hepatologists, molecular biologists, clinicians, and all those concerned with targeted therapy and prognosis of liver disease.

Methodology

We searched three bibliographic databases (Web of Science Core Collection, Embase, PubMed) from 01/1981 to 06/2022 for peer-reviewed scientific publications focused on (1) gene treatment of liver disease; (2) current status of SE research; and (3) targeting SEs for liver disease. We included English language original studies only.

Results

The number of published studies considering the role of enhancers in liver disease is considerable. Since SEs were just defined in 2013, the corresponding data on SEs are scarce: approximately 50 papers found in bibliographic databases on the correlation between enhancers (or SEs) and liver disease. Remarkably, half of these papers were published in the past three years, indicating the growing interest of the scientific community in this issue. Studies have shown that treatments targeting components of SEs can improve outcomes in liver disease in animal and clinical trials.

Conclusions

The treatment of liver disease is facing a bottleneck, and new treatments are needed. Therapeutic regimens targeting SEs have an important role in the treatment of liver disease. However, given the off-target effect of gene therapy and the lack of clinical trials, the available experimental data are still fragmented and controversial.

Identification of biomarkers co-associated with M1 macrophages, ferroptosis and cuproptosis in alcoholic hepatitis by bioinformatics and experimental verification

Backgrounds

Alcoholic hepatitis (AH) is a major health problem worldwide. There is increasing evidence that immune cells, iron metabolism and copper metabolism play important roles in the development of AH. We aimed to explore biomarkers that are co-associated with M1 macrophages, ferroptosis and cuproptosis in AH patients.

Methods

GSE28619 and GSE103580 datasets were integrated, CIBERSORT algorithm was used to analyze the infiltration of 22 types of immune cells and GSVA algorithm was used to calculate ferroptosis and cuproptosis scores. Using the "WGCNA" R package, we established a gene co-expression network and analyzed the correlation between M1 macrophages, ferroptosis and cuproptosis scores and module characteristic genes. Subsequently, candidate genes were screened by WGCNA and differential expression gene analysis. The LASSO-SVM analysis was used to identify biomarkers co-associated with M1 macrophages, ferroptosis and cuproptosis. Finally, we validated these potential biomarkers using GEO datasets (GSE155907, GSE142530 and GSE97234) and a mouse model of AH.

Results

The infiltration level of M1 macrophages was significantly increased in AH patients. Ferroptosis and cuproptosis scores were also increased in AH patients. In addition, M1 macrophages, ferroptosis and cuproptosis were positively correlated with each other. Combining bioinformatics analysis with a mouse model of AH, we found that ALDOA, COL3A1, LUM, THBS2 and TIMP1 may be potential biomarkers co-associated with M1 macrophages, ferroptosis and cuproptosis in AH patients.

Conclusion

We identified 5 potential biomarkers that are promising new targets for the treatment and diagnosis of AH patients.

Narrative Review: Glucocorticoids in Alcoholic Hepatitis—Benefits, Side Effects, and Mechanisms

Alcoholic hepatitis is a major health and economic burden worldwide. Glucocorticoids (GCs) are the only first-line drugs recommended to treat severe alcoholic hepatitis (sAH), with limited short-term efficacy and significant side effects. In this review, I summarize the major benefits and side effects of GC therapy in sAH and the potential underlying mechanisms. The review of the literature and data mining clearly indicate that the hepatic signaling of glucocorticoid receptor (GR) is markedly impaired in sAH patients. The impaired GR signaling causes hepatic down-regulation of genes essential for gluconeogenesis, lipid catabolism, cytoprotection, and anti-inflammation in sAH patients. The efficacy of GCs in sAH may be compromised by GC resistance and/or GC’s extrahepatic side effects, particularly the side effects of intestinal epithelial GR on gut permeability and inflammation in AH. Prednisolone, a major GC used for sAH, activates both the GR and mineralocorticoid receptor (MR). When GC non-responsiveness occurs in sAH patients, the activation of MR by prednisolone might increase the risk of alcohol abuse, liver fibrosis, and acute kidney injury. To improve the GC therapy of sAH, the effort should be focused on developing the biomarker(s) for GC responsiveness, liver-targeting GR agonists, and strategies to overcome GC non-responsiveness and prevent alcohol relapse in sAH patients.

Mechanotransduction-induced glycolysis epigenetically regulates a CXCL1-dominant angiocrine signaling program in liver sinusoidal endothelial cells in vitro and in vivo

BACKGROUND & AIMS

Liver sinusoidal endothelial cells (LSECs) are ideally situated to sense stiffness and generate angiocrine programs that potentially regulate liver fibrosis and portal hypertension. We explored how specific focal adhesion (FA) proteins parlay LSEC mechanotransduction into stiffness-induced angiocrine signaling in vitro and in vivo.

METHODS

Primary human and murine LSECs were placed on gels with incremental stiffness (0.2 kPa vs. 32 kPa). Cell response was studied by FA isolation, actin polymerization assay, RNA-sequencing and electron microscopy. Glycolysis was assessed using radioactive tracers. Epigenetic regulation of stiffness-induced genes was analyzed by chromatin-immunoprecipitation (ChIP) analysis of histone activation marks, ChIP sequencing and circularized chromosome conformation capture (4C). Mice with LSEC-selective deletion of glycolytic enzymes (Hk2fl/fl/Cdh5cre-ERT2) or treatment with the glycolysis inhibitor 3PO were studied in portal hypertension (partial ligation of the inferior vena cava, pIVCL) and early liver fibrosis (CCl4) models.

RESULTS

Glycolytic enzymes, particularly phosphofructokinase 1 isoform P (PFKP), are enriched in isolated FAs from LSECs on gels with incremental stiffness. Stiffness resulted in PFKP recruitment to FAs, which paralleled an increase in glycolysis. Glycolysis was associated with expansion of actin dynamics and was attenuated by inhibition of integrin β1. Inhibition of glycolysis attenuated a stiffness-induced CXCL1-dominant angiocrine program. Mechanistically, glycolysis promoted CXCL1 expression through nuclear pore changes and increases in NF-kB translocation. Biochemically, this CXCL1 expression was mediated through spatial re-organization of nuclear chromatin resulting in formation of super-enhancers, histone acetylation and NF-kB interaction with the CXCL1 promoter. Hk2fl/fl/Cdh5cre-ERT2 mice showed attenuated neutrophil infiltration and portal hypertension after pIVCL. 3PO treatment attenuated liver fibrosis in a CCl4 model.

CONCLUSION

Glycolytic enzymes are involved in stiffness-induced angiocrine signaling in LSECs and represent druggable targets in early liver disease.

LAY SUMMARY

Treatment options for liver fibrosis and portal hypertension still represent an unmet need. Herein, we uncovered a novel role for glycolytic enzymes in promoting stiffness-induced angiocrine signaling, which resulted in inflammation, fibrosis and portal hypertension. This work has revealed new targets that could be used in the prevention and treatment of liver fibrosis and portal hypertension.

Distinct histopathological phenotypes of severe alcoholic hepatitis suggest different mechanisms driving liver injury and failure

Intrahepatic neutrophil infiltration has been implicated in severe alcoholic hepatitis (SAH) pathogenesis; however, the mechanism underlying neutrophil-induced injury in SAH remains obscure. This translational study aims to describe the patterns of intrahepatic neutrophil infiltration and its involvement in SAH pathogenesis. Immunohistochemistry analyses of explanted livers identified two SAH phenotypes despite a similar clinical presentation, one with high intrahepatic neutrophils (Neuhi), but low levels of CD8+ T cells, and vice versa. RNA-Seq analyses demonstrated that neutrophil cytosolic factor 1 (NCF1), a key factor in controlling neutrophilic ROS production, was upregulated and correlated with hepatic inflammation and disease progression. To study specifically the mechanisms related to Neuhi in AH patients and liver injury, we used the mouse model of chronic-plus-binge ethanol feeding and found that myeloid-specific deletion of the Ncf1 gene abolished ethanol-induced hepatic inflammation and steatosis. RNA-Seq analysis and the data from experimental models revealed that neutrophilic NCF1-dependent ROS promoted alcoholic hepatitis (AH) by inhibiting AMP-activated protein kinase (a key regulator of lipid metabolism) and microRNA-223 (a key antiinflammatory and antifibrotic microRNA). In conclusion, two distinct histopathological phenotypes based on liver immune phenotyping are observed in SAH patients, suggesting a separate mechanism driving liver injury and/or failure in these patients.

Therapeutic advances in alcohol-associated hepatitis

In recent years, there have been important advances in our understanding of alcohol-associated hepatitis (AH), which have occurred in parallel with a surge in clinical trial activity. Meanwhile, the broader medical field has seen a transformation in care paradigms based on emerging digital technologies. This review focuses on breakthroughs in our understanding of AH and how these breakthroughs are leading to new paradigms for biomarker discovery, clinical trial activity, and care models for patients. It portends a future in which multimodal data from genetic, radiomic, histologic, and environmental sources can be integrated and synthesised to generate personalised biomarkers and therapies for patients with AH.