MicroRNA-223 restricts liver fibrosis by inhibiting the TAZ-IHH-GLI2 and PDGF signaling pathways via the crosstalk of multiple liver cell types

Pathogenesis and interaction of neutrophils and extracellular vesicles in noncancer liver diseases

Liver disease ranks as the eleventh leading cause of mortality, leading to approximately 2 million deaths annually worldwide. Neutrophils are a type of immune cell that are abundant in peripheral blood and play a vital role in innate immunity by quickly reaching the site of liver injury. They exert their influence on liver diseases through autocrine, paracrine, and immunomodulatory mechanisms. Extracellular vesicles, phospholipid bilayer vesicles, transport a variety of substances, such as proteins, nucleic acids, lipids, and pathogenic factors, for intercellular communication. They regulate cell communication and perform their functions by delivering biological information. Current research has revealed the involvement of the interaction between neutrophils and extracellular vesicles in the pathogenesis of liver disease. Moreover, more research has focused on targeting neutrophils as a therapeutic strategy to attenuate disease progression. Therefore, this article summarizes the roles of neutrophils, extracellular vesicles, and their interactions in noncancerous liver diseases.

MicroRNA-223-3p levels in serum-derived extracellular vesicles predict regression of M2BPGi-based liver fibrosis after hepatitis C virus eradication by direct-acting antiviral agents

BACKGROUND

We retrospectively investigated microRNA (miRNA) levels in serum-derived extracellular vesicles (EVs) as predictive indicators for regression of liver fibrosis, after achievement of a sustained virological response (SVR) by direct-acting antiviral (DAA) therapy for chronic hepatitis C (CHC).

METHODS

The study subjects were recruited from a historical cohort of 108 CHC patients whose pretreatment serum Mac-2-binding protein glycosylation isomer (M2BPGi) levels were ≥ 2.0 cut-off index (COI). We classified patients with M2BPGi levels < 1.76 and ≥ 1.76 COI at 2 years after the end of treatment (EOT) into the regression and non-regression groups, respectively. Eleven of the patients were assigned to the discovery set, and we comprehensively investigated the miRNAs contained in serum-derived EVs at 24 weeks after the EOT (EOT24W), using RNA sequencing. The remaining 97 patients were assigned to the validation set, and reproducibility was verified by quantitative real-time PCR.

RESULTS

Through analysis of the discovery and validation sets, we identified miR-223-3p and miR-1290 as candidate predictors. Subsequently, we analyzed various clinical data, including these candidate miRNAs. Multivariate analyses revealed that the levels of miR-223-3p at EOT24W were significantly associated with regression of M2BPGi-based liver fibrosis (Odds ratio: 1.380; P = 0.024). Consistent results were obtained, even when the serum M2BPGi levels were aligned by propensity score matching and in patients with advanced M2BPGi-based liver fibrosis (pretreatment M2BPGi levels ≥ 3.3 COI).

CONCLUSIONS

The miR-223-3p level in serum-derived EVs at EOT24W is a feasible predictor of regression of M2BPGi-based liver fibrosis after achievement of an SVR by DAA therapy.

Abnormal metabolism in hepatic stellate cells: Pandora's box of MAFLD related hepatocellular carcinoma

Metabolic associated fatty liver disease (MAFLD) is a significant risk factor for the development of hepatocellular carcinoma (HCC). Hepatic stellate cells (HSCs), as key mediators in liver injury response, are believed to play a crucial role in the repair process of liver injury. However, in MAFLD patients, the normal metabolic and immunoregulatory mechanisms of HSCs become disrupted, leading to disturbances in the local microenvironment. Abnormally activated HSCs are heavily involved in the initiation and progression of HCC. The metabolic disorders and abnormal activation of HSCs not only initiate liver fibrosis but also contribute to carcinogenesis. In this review, we provide an overview of recent research progress on the relationship between the abnormal metabolism of HSCs and the local immune system in the liver, elucidating the mechanisms of immune imbalance caused by abnormally activated HSCs in MAFLD patients. Based on this understanding, we discuss the potential and challenges of metabolic-based and immunology-based mechanisms in the treatment of MAFLD-related HCC, with a specific focus on the role of HSCs in HCC progression and their potential as targets for anti-cancer therapy. This review aims to enhance researchers' understanding of the importance of HSCs in maintaining normal liver function and highlights the significance of HSCs in the progression of MAFLD-related HCC.

The systemic immune-inflammation index was non-linear associated with all-cause mortality in individuals with nonalcoholic fatty liver disease

OBJECTIVE

Systemic immune-inflammation index (SII), a novel inflammatory indicator based on platelets, neutrophils and lymphocytes, has been shown to be associated with prognostic value in several solid tumors. However, its prognostic value in nonalcoholic fatty liver disease (NAFLD) has not been reported yet. Therefore, the present study aimed to investigate the prognostic value of SII in individuals with NAFLD.

METHODS

Data was collected from the 2005 to 2014 National Health and Nutrition Examination Survey (NHANES, https://www.cdc.gov/nchs/nhanes/index.htm), and vital status was derived from the National Death Index (NDI) up to 31 December 2015. NAFLD was diagnosed based on Hepatic Steatosis Index (HSI). Multivariate Cox regression and Kaplan-Meier survival curves were performed to measure the hazard ratios (HRs) and 95% confidence interval (CI). Our study investigated the relationship between SII and all-cause mortality by using two-part linear regression models with penalized splines, as well as Cox models with penalized splines.

RESULTS

A total of 10,787 NAFLD participants (44.14% men) aged ≥20 years old were enrolled. There were 776 deaths from all causes after a mean follow-up period of 5.6 years. According to the full adjusted Cox regression analysis, the low log₂-SII group (quartile 1) and the highest log₂-SII group (quartile 4) were significantly associated with increased mortality from all causes (aHR =1.86; 95% CI: 1.47-2.37; p < 0.0001). After controlling for confounders, an increase in log₂-SII was associated with an increased all-cause mortality risk of 41% for every unit raised (aHR = 1.41; 95% CI: 1.26-1.57; p < 0.0001). After adjusting for multiple potential confounders, the association between log₂-SII and all-cause mortality was nonlinear, and the threshold value was 8.8. There was no association between an increase of one unit in log₂-SII and all-cause mortality below the threshold (aHR = 0.90, 95% CI: 0.71-1.15, p = 0.419). However, a higher log₂-SII was associated with a higher risk of death from any cause when it exceeded the threshold (aHR = 1. 73, 95% CI: 1.49-2.02, p < 0.001).

Based on a study of US NAFLD patients, it was found that the baseline log₂-SII is associated with all-cause mortality. Elevated SII is associated with poor survival among NAFLD patients.KEY MESSAGESUsing a large nationally representative survey of individuals among US adults, the study demonstrated that log₂-SII was J-shaped and associated with all-cause death among individuals with NAFLD.Spline analyses demonstrated that the association between log₂-SII and all-cause mortality was non-linear after adjusting for multiple potential confounders, and the threshold value was 8.8.Higher log₂-SII associated with poor survival in NAFLD.

MicroRNA-223 attenuates hepatocarcinogenesis by blocking hypoxia-driven angiogenesis and immunosuppression

OBJECTIVE

The current treatment for hepatocellular carcinoma (HCC) to block angiogenesis and immunosuppression provides some benefits only for a subset of patients with HCC, thus optimised therapeutic regimens are unmet needs, which require a thorough understanding of the underlying mechanisms by which tumour cells orchestrate an inflamed tumour microenvironment with significant myeloid cell infiltration. MicroRNA-223 (miR-223) is highly expressed in myeloid cells but its role in regulating tumour microenvironment remains unknown.

DESIGN

Wild-type and miR-223 knockout mice were subjected to two mouse models of inflammation-associated HCC induced by injection of diethylnitrosamine (DEN) or orthotopic HCC cell implantation in chronic carbon tetrachloride (CCl4)-treated mice.

RESULTS

Genetic deletion of miR-223 markedly exacerbated tumourigenesis in inflammation-associated HCC. Compared with wild-type mice, miR-223 knockout mice had more infiltrated programmed cell death 1 (PD-1+) T cells and programmed cell death ligand 1 (PD-L1+) macrophages after DEN+CCl4 administration. Bioinformatic analyses of RNA sequencing data revealed a strong correlation between miR-223 levels and tumour hypoxia, a condition that is well-documented to regulate PD-1/PD-L1. In vivo and in vitro mechanistic studies demonstrated that miR-223 did not directly target PD-1 and PD-L1 in immune cells rather than indirectly downregulated them by modulating tumour microenvironment via the suppression of hypoxia-inducible factor 1α-driven CD39/CD73-adenosine pathway in HCC. Moreover, gene delivery of miR-223 via adenovirus inhibited angiogenesis and hypoxia-mediated PD-1/PD-L1 activation in both HCC models, thereby hindering HCC progression.

CONCLUSION

The miR-223 plays a critical role in modulating hypoxia-induced tumour immunosuppression and angiogenesis, which may serve as a novel therapeutic target for HCC.

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.

Role of noncoding RNAs in liver fibrosis

Liver fibrosis is a wound-healing response following chronic liver injury caused by hepatitis virus infection, obesity, or excessive alcohol. It is a dynamic and reversible process characterized by the activation of hepatic stellate cells and excess accumulation of extracellular matrix. Advanced fibrosis could lead to cirrhosis and even liver cancer, which has become a significant health burden worldwide. Many studies have revealed that noncoding RNAs (ncRNAs), including microRNAs, long noncoding RNAs and circular RNAs, are involved in the pathogenesis and development of liver fibrosis by regulating signaling pathways including transforming growth factor-β pathway, phosphatidylinositol 3-kinase/protein kinase B pathway, and Wnt/β-catenin pathway. NcRNAs in serum or exosomes have been reported to tentatively applied in the diagnosis and staging of liver fibrosis and combined with elastography to improve the accuracy of diagnosis. NcRNAs mimics, ncRNAs in mesenchymal stem cell-derived exosomes, and lipid nanoparticles-encapsulated ncRNAs have become promising therapeutic approaches for the treatment of liver fibrosis. In this review, we update the latest knowledge on ncRNAs in the pathogenesis and progression of liver fibrosis, and discuss the potentials and challenges to use these ncRNAs for diagnosis, staging and treatment of liver fibrosis. All these will help us to develop a comprehensive understanding of the role of ncRNAs in liver fibrosis.

Insights on drug and gene delivery systems in liver fibrosis

Complications of the liver are amongst the world's worst diseases. Liver fibrosis is the first stage of liver problems, while cirrhosis is the last stage, which can lead to death. The creation of effective anti-fibrotic drug delivery methods appears critical due to the liver's metabolic capacity for drugs and the presence of insurmountable physiological impediments in the way of targeting. Recent breakthroughs in anti-fibrotic agents have substantially assisted in fibrosis; nevertheless, the working mechanism of anti-fibrotic medications is not fully understood, and there is a need to design delivery systems that are well-understood and can aid in cirrhosis. Nanotechnology-based delivery systems are regarded to be effective but they have not been adequately researched for liver delivery. As a result, the capability of nanoparticles in hepatic delivery was explored. Another approach is targeted drug delivery, which can considerably improve efficacy if delivery systems are designed to target hepatic stellate cells (HSCs). We have addressed numerous delivery strategies that target HSCs, which can eventually aid in fibrosis. Recently genetics have proved to be useful, and methods for delivering genetic material to the target place have also been investigated where different techniques are depicted. To summarize, this review paper sheds light on the most recent breakthroughs in drug and gene-based nano and targeted delivery systems that have lately shown useful for the treatment of liver fibrosis and cirrhosis.

Immune cells and their derived microRNA-enriched extracellular vesicles in nonalcoholic fatty liver diseases: Novel therapeutic targets

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide. Despite extensive research and multiple clinical trials, there are still no FDA-approved therapies to treat the most severe forms of NAFLD. This is largely due to its complicated etiology and pathogenesis, which involves visceral obesity, insulin resistance, gut dysbiosis, etc. Although inflammation is generally believed to be one of the critical factors that drive the progression of simple steatosis to nonalcoholic steatohepatitis (NASH), the exact type of inflammation and how it contributes to NASH pathogenesis remain largely unknown. Liver inflammation is accompanied by the elevation of inflammatory mediators, including cytokines and chemokines and consequently intrahepatic infiltration of multiple types of immune cells. Recent studies revealed that extracellular vesicles (EVs) derived from inflammatory cells and hepatocytes play an important role in controlling liver inflammation during NASH. In this review, we highlight the roles of innate and adaptive immune cells and their microRNA-enriched EVs during NAFLD development and discuss potential drugs that target inflammatory pathways for the treatment of NAFLD.

Regulatory Functions and Mechanisms of Circular RNAs in Hepatic Stellate Cell Activation and Liver Fibrosis

Chronic liver injury induces the activation of hepatic stellate cells (HSCs) into myofibroblasts, which produce excessive amounts of extracellular matrix (ECM), resulting in tissue fibrosis. If the injury persists, these fibrous scars could be permanent and disrupt liver architecture and function. Currently, effective anti-fibrotic therapies are lacking; hence, understanding molecular mechanisms that control HSC activation could hold a key to the development of new treatments. Recently, emerging studies have revealed roles of circular RNAs (circRNAs), a class of non-coding RNAs that was initially assumed to be the result of splicing errors, as new regulators in HSC activation. These circRNAs can modulate the activity of microRNAs (miRNAs) and their interacting protein partners involved in regulating fibrogenic signaling cascades. In this review, we will summarize the current knowledge of this class of non-coding RNAs for their molecular function in HSC activation and liver fibrosis progression.

MicroRNA-223 downregulation promotes HBx-induced podocyte pyroptosis by targeting the NLRP3 inflammasome

Hepatitis B virus (HBV) and its related protein, HBV X (HBx), play an important role in podocyte injury in HBV-associated glomerulonephritis (HBV-GN). The microRNA MiR-223 is expressed in several diseases, including HBV-associated disease, while the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome plays a major role in pyroptosis. In this study, we investigated the function and mechanism of action of miR-223 in HBx-induced podocyte pyroptosis. A quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) assay showed that miR-223 was downregulated in HBx-transfected podocytes. Transfection with an miR-223 mimic abolished the expression of the NLRP3 inflammasome and the cytokines that are released as a result of NLRP3 overexpression. Moreover, transfection with HBx and NLRP3 overexpression plasmids increased the expression of pyroptosis-related proteins, especially in the presence of miR-223 inhibitors. Thus, miR-223 downregulation plays an important role in HBx-induced podocyte pyroptosis by targeting the NLRP3 inflammasome, suggesting that miR-223 is a potential therapeutic target for alleviating HBV-GN inflammation.

MicroRNA-223 Suppresses Human Hepatic Stellate Cell Activation Partly via Regulating the Actin Cytoskeleton and Alleviates Fibrosis in Organoid Models of Liver Injury

MicroRNAs (miRNAs) are small, non-coding RNAs that negatively regulate target mRNA expression, and altered expression of miRNAs is associated with liver pathological conditions. Recent studies in animal models have shown neutrophil/myeloid-specific microRNA-223 (miR-223) as a key regulator in the development of various liver diseases including fibrosis, where hepatic stellate cells (HSCs) are the key player in pathogenesis. However, the precise roles of miR-223 in human HSCs and its therapeutic potential to control fibrosis remain largely unexplored. Using primary human HSCs, we demonstrated that miR-223 suppressed the fibrogenic program and cellular proliferation while promoting features of quiescent HSCs including lipid re-accumulation and retinol storage. Furthermore, induction of miR-223 in HSCs decreased cellular motility and contraction. Mechanistically, miR-223 negatively regulated expression of smooth muscle α-actin (α-SMA) and thus reduced cytoskeletal activity, which is known to promote amplification of fibrogenic signals. Restoration of α-SMA in miR-223-overexpressing HSCs alleviated the antifibrotic effects of miR-223. Finally, to explore the therapeutic potential of miR-233 in liver fibrosis, we generated co-cultured organoids of HSCs with Huh7 hepatoma cells and challenged them with acetaminophen (APAP) or palmitic acid (PA) to induce hepatotoxicity. We showed that ectopic expression of miR-223 in HSCs attenuated fibrogenesis in the two human organoid models of liver injury, suggesting its potential application in antifibrotic therapy.

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 (Neu^hi), 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 Neu^hi 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.

Insights Into the Role of Platelet-Derived Growth Factors: Implications for Parkinson’s Disease Pathogenesis and Treatment

Parkinson’s disease (PD), the second most common neurodegenerative disease after Alzheimer’s disease, commonly occurs in the elderly population, causing a significant medical and economic burden to the aging society worldwide. At present, there are few effective methods that achieve satisfactory clinical results in the treatment of PD. Platelet-derived growth factors (PDGFs) and platelet-derived growth factor receptors (PDGFRs) are important neurotrophic factors that are expressed in various cell types. Their unique structures allow for specific binding that can effectively regulate vital functions in the nervous system. In this review, we summarized the possible mechanisms by which PDGFs/PDGFRs regulate the occurrence and development of PD by affecting oxidative stress, mitochondrial function, protein folding and aggregation, Ca2+ homeostasis, and cell neuroinflammation. These modes of action mainly depend on the type and distribution of PDGFs in different nerve cells. We also summarized the possible clinical applications and prospects for PDGF in the treatment of PD, especially in genetic treatment. Recent advances have shown that PDGFs have contradictory roles within the central nervous system (CNS). Although they exert neuroprotective effects through multiple pathways, they are also associated with the disruption of the blood–brain barrier (BBB). Our recommendations based on our findings include further investigation of the contradictory neurotrophic and neurotoxic effects of the PDGFs acting on the CNS.

Recent Advancements in Antifibrotic Therapies for Regression of Liver Fibrosis

Cirrhosis is a severe form of liver fibrosis that results in the irreversible replacement of liver tissue with scar tissue in the liver. Environmental toxicity, infections, metabolic causes, or other genetic factors including autoimmune hepatitis can lead to chronic liver injury and can result in inflammation and fibrosis. This activates myofibroblasts to secrete ECM proteins, resulting in the formation of fibrous scars on the liver. Fibrosis regression is possible through the removal of pathophysiological causes as well as the elimination of activated myofibroblasts, resulting in the reabsorption of the scar tissue. To date, a wide range of antifibrotic therapies has been tried and tested, with varying degrees of success. These therapies include the use of growth factors, cytokines, miRNAs, monoclonal antibodies, stem-cell-based approaches, and other approaches that target the ECM. The positive results of preclinical and clinical studies raise the prospect of a viable alternative to liver transplantation in the near future. The present review provides a synopsis of recent antifibrotic treatment modalities for the treatment of liver cirrhosis, as well as a brief summary of clinical trials that have been conducted to date.

Pathogenic and Potential Therapeutic Roles of Exosomes Derived From Immune Cells in Liver Diseases

Liver diseases, such as viral hepatitis, alcoholic hepatitis and cirrhosis, nonalcoholic steatohepatitis, and hepatocellular carcinoma place a heavy burden on many patients worldwide. However, the treatment of many liver diseases is currently insufficient, and the treatment may be associated with strong side effects. Therapies for liver diseases targeting the molecular and cellular levels that minimize adverse reactions and maximize therapeutic effects are in high demand. Immune cells are intimately involved in the occurrence, development, and prognosis of liver diseases. The immune response in the liver can be suppressed, leading to tolerance in homeostasis. When infection or tissue damage occurs, immunity in the liver is activated rapidly. As small membrane vesicles derived from diverse cells, exosomes carry multiple cargoes to exert their regulatory effects on recipient cells under physiological or pathological conditions. Exosomes from different immune cells exert different effects on liver diseases. This review describes the biology of exosomes and focuses on the effects of exosomes from different immune cells on pathogenesis, diagnosis, and prognosis and their therapeutic potential in liver diseases.

Role of Neutrophils in the Pathogenesis of Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) includes a spectrum of liver disorders, from fatty liver to nonalcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma. Compared with fatty liver, NASH is characterized by increased liver injury and inflammation, in which liver-infiltrating immune cells, with neutrophil infiltration as a hallmark of NASH, play a critical role in promoting the progression of fatty liver to NASH. Neutrophils are the first responders to injury and infection in various tissues, establishing the first line of defense through multiple mechanisms such as phagocytosis, cytokine secretion, reactive oxygen species production, and neutrophil extracellular trap formation; however, their roles in the pathogenesis of NASH remain obscure. The current review summarizes the roles of neutrophils that facilitate the progression of fatty liver to NASH and their involvement in inflammation resolution during NASH pathogenesis. The notion that neutrophils are potential therapeutic targets for the treatment of NASH is also discussed.