Hesperetin derivative 2a inhibits lipopolysaccharide-induced acute liver injury in mice via downregulation of circDcbld2.

Acute liver injury (ALI) is a complex, life-threatening inflammatory liver disease, and persistent liver damage leads to rapid decline and even failure of liver function. However, the pathogenesis of ALI is still not fully understood, and no effective treatment has been discovered. Recent evidence shows that many circular RNAs (circRNAs) are associated with the occurrence of liver diseases. In this study we investigated the mechanisms of occurrence and development of ALI in lipopolysaccharide (LPS)-induced ALI mice. We found that expression of the circular RNA circDcbld2 was significantly elevated in the liver tissues of ALI mice and LPS-treated RAW264.7 cells. Knockdown of circDcbld2 markedly alleviates LPS-induced inflammatory responses in ALI mice and RAW264.7 cells. We designed and synthesized a series of hesperidin derivatives for circDcbld2, and found that hesperetin derivative 2a (HD-2a) at the concentrations of 2, 4, 8 µM effectively inhibited circDcbld2 expression in RAW264.7 cells. Administration of HD-2a (50, 100, 200 mg/kg. i.g., once 24 h in advance) effectively relieved LPS-induced liver dysfunction and inflammatory responses. RNA sequencing analysis revealed that the anti-inflammatory and hepatoprotective effects of HD-2a were mediated through downregulating circDcbld2 and suppressing the JAK2/STAT3 pathway. We conclude that HD-2a downregulates circDcbld2 to inhibit the JAK2/STAT3 pathway, thereby inhibiting the inflammatory responses in ALI. The results suggest that circDcbld2 may be a potential target for the prevention and treatment of ALI, and HD-2a may have potential as a drug for the treatment of ALI.

Berberine Ameliorates Abnormal Lipid Metabolism via the Adenosine Monophosphate-Activated Protein Kinase/Sirtuin 1 Pathway in Alcohol-Related Liver Disease.

Alcoholic fatty liver disease (AFLD) is an early stage of alcohol-related liver disease characterized by abnormal lipid metabolism in hepatocytes. To date, to our knowledge, there have been no effective strategies for preventing or treating alcohol-related liver disease besides alcohol abstinence. Berberine (BBR) is the main bioactive ingredient extracted from traditional Chinese medicines, such as Coptis and Scutellaria, which protect liver function and relieve liver steatosis. However, the potential role of BBR in AFLD remains unclear. Therefore, this study investigated the protective effects of BBR against Gao-binge model-induced AFLD in 6- to 8-week-old C57BL/6J male mice in vivo and ethyl alcohol (EtOH)-induced alpha mouse liver 12 (AML-12) cells in vitro. The results showed that BBR (200 mg/kg) attenuated alcoholic liver injury and suppressed lipid accumulation and metabolism disorders in vivo. Consistently, BBR effectively inhibited the expression of sterol regulatory element-binding transcription factor 1C, sterol regulatory element-binding transcription factor 2, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-CoenzymeA reductase in EtOH-stimulated AML-12 cells in vitro and promoted the expression of sirtuin 1 (SIRT1) in EtOH-fed mice and EtOH-treated AML-12 cells. Furthermore, SIRT1 silencing attenuated the hepatic steatosis alleviation potential of BBR treatment. Mechanistically, molecular docking revealed the binding effect of BBR and adenosine monophosphate-activated protein kinase (AMPK). The results of further studies showed that a decrease in AMPK activity was accompanied by a significant inhibition of SIRT1 expression. SIRT1 silencing attenuated the protective effect of BBR, whereas the inhibition of its expression had no apparent effect on AMPK phosphorylation, suggesting that SIRT1 acts downstream of AMPK in AFLD. Collectively, BBR ameliorated abnormal lipid metabolism and alleviated EtOH-induced liver injury via the AMPK/SIRT1 pathway in AFLD mice.

NADPH oxidase 4 promotes cisplatin-induced acute kidney injury via ROS-mediated programmed cell death and inflammation.

The goal of this study was to elucidate the functional role of Nox4 during acute kidney injury (AKI). NADPH oxidases are a major source of reactive oxygen species (ROS) in the kidney in normal and pathological conditions. Among NADPH oxidase isoforms, NADPH oxidase4 (Nox4) is highly expressed in the kidney and has an important role in kidney diseases, such as diabetic nephropathy and renal carcinoma. We previously found that Nox4 expression significantly increased in the toxic AKI model. However, its functional role and mechanism of action in AKI are still unknown. We scavenged ROS with apocynin in vitro and in vivo and found it attenuated cisplatin-triggered renal function decline. It also alleviated programmed cell death and renal inflammation, indicating a critical role for ROS in mediating AKI. Nox4 protein and mRNA levels were substantially upregulated by cisplatin in vivo and in vitro. Nox4 knockdown alleviated cisplatin-induced cell death and inflammatory response, while Nox4 overexpression aggravated them. Moreover, N-acetyl-L-cysteine (NAC)-mediated inhibition of ROS suppressed cell injury led by Nox4 overexpression, indicating Nox4-mediated ROS generation may be the key mediator in cisplatin-induced nephrotoxicity. Mechanistically, excessive expression of Nox4 induced programmed cell death, especially RIP-mediated necroptosis. Finally, we tested whether Nox4 is a potential therapeutic target using an AKI mouse model by injecting a lentivirus-packaged Nox4 shRNA plasmid through tail vein. Disruption of Nox4 led to renal function recovery, kidney damage relief and reduced inflammation. We conclude that Nox4 aggravates cisplatin-induced nephrotoxicity by promoting ROS-mediated programmed cell death and inflammation. Thus Nox4 may serve as a potential therapeutic target in the treatment of AKI.

Wogonin protects against cisplatin-induced acute kidney injury by targeting RIPK1-mediated necroptosis.

Acute kidney injury (AKI), characterized by aggressive inflammatory responses and destruction of renal resident cells, can cause abrupt kidney dysfunction. To date, effective therapy for AKI is lacking. In this study, we evaluated the renoprotective effect of wogonin, an herbal active compound, using a cisplatin-induced AKI mouse model. In vivo results show that wogonin substantially suppressed the increased levels of serum creatinine and blood urea nitrogen (BUN) almost to the normal level. Wogonin also attenuated tubular damage, shown by PAS staining, electron microscopy and molecular analysis of KIM-1. In addition, wogonin suppressed kidney inflammation as indicated by a >60% decrease in macrophage infiltration, a >50% reduction in inflammatory cytokine production and inhibited NF-κB activation in the injured kidney. Mechanistically, molecular docking results show that wogonin effectively inhibited RIPK1 by occupying the ATP-binding pocket of the enzyme, which is a key regulator of necroptosis. Moreover, inhibition of RIPK1, or RIPK3, reversed the protective effects of wogonin in cisplatin-treated HK2 cells, indicating wogonin works in a RIPK1/RIPK3-dependent manner. Surprisingly, wogonin enhanced the anti-proliferative effect of cisplatin on human hepatoma HepG2 cells. Thus, our findings suggest wogonin may be a renoprotective adjuvant for cisplatin-based anticancer therapy.

Hotair facilitates hepatic stellate cells activation and fibrogenesis in the liver.

Long non-coding RNAs (lncRNAs) are increasingly recognized as major players in regulating various biological processes. LncRNA HOX transcript antisense RNA (Hotair) has been extensively studied in cancer. However, the role of Hotair in liver fibrosis remains unknown. Here we observed that Hotair expression was significantly increased in CCl4-induced mouse liver fibrosis models, human fibrotic livers and activated hepatic stellate cells (HSCs) by TGF-ß1 stimulation. Enforced expression of Hotair in LX-2 cells promoted cell proliferation and activation while inhibition of its expression had an opposite effect. Furthermore, we found that Hotair may act as an endogenous 'sponge' of miR-148b, which regulates expression of the DNMT1/MEG3/p53 pathways in HSCs. Intriguingly, Hotair enhanced polycomb repressive complex 2 (PRC2) occupancy and histone H3K27me3 repressive marks, specifically at the MEG3 promoter region. Finally, we found that Hotair forms an RNA/DNA hybrid and recruits PRC2 to MEG3 promoter. These data suggest that Hotair inhibition may represent a promising therapeutic option for suppressing liver fibrosis.

Inhibitory effects of long noncoding RNA MEG3 on hepatic stellate cells activation and liver fibrogenesis.

Long noncoding RNAs (lncRNAs) are being increasingly recognized as major players in governing fundamental biological processes through diverse mechanisms. Maternally expressed gene 3 (MEG3) is an imprinted gene located at 14q32 that encodes a lncRNA correlated with several human cancers. Recently, the methylation-dependent downregulation of MEG3 has been described in liver cancers. However, its biological functional role in liver fibrosis remains unknown. In our study, MEG3 levels were remarkably decreased in CCl4-induced mouse liver fibrosis models and human fibrotic livers as demonstrated by real-time quantitative PCR. Moreover, the expression of MEG3 was downregulated in human hepatic stellate cell lines LX-2 cells in response to transforming growth factor-ß1 (TGF-ß1) stimulation in dose and time-dependent manner. Enforced expression of MEG3 in LX-2 cells inhibited TGF-ß1-induced cell proliferation, while promoting cell apoptosis. In addition, hypermethylation of MEG3 promoter was identified by methylation-specific PCR and MEG3 expression was robustly increased by the inhibition of methylation with either 5-aza-2-deoxycytidine (5-azadC), or siRNA to DNA methyltransferase 1 (DNMT1) in TGF-ß1-induced LX-2 cells. More importantly, overexpression of MEG3 could activate p53 and mediate cytochrome c release, subsequently leading to caspase-3-dependent apoptosis in TGF-ß1-treated LX-2 cells. These findings suggested that MEG3 may play an important role in stellate cell activation and liver fibrosis progression and act as a novel potential therapeutic target for liver fibrosis.

Studies on mitogen-activated protein kinase signaling pathway in the alveolar macrophages of chronic bronchitis rats.

Lipopolysaccharide (LPS), a potent stimulator of inflammatory responses in alveolar macrophages (AMs), activates several intracellular signaling pathways, including mitogen-activated protein kinases (MAPK). In the present study, we investigated the MAPK pathway in AMs of chronic bronchitis (CB) rats. CB was induced by endotracheal instillation of LPS followed by Bacillus Calmette Guerin injection through the caudal vein 1 week later. Specific inhibitors were used and protein phosphorylations were detected by Western blot. We found that Genistein (PTK inhibitor) could inhibit protein kinase C (PKC), phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt or PKB) MAPK signaling pathway with different degrees, LY294002 (PI3K inhibitor) could not only inhibit phospho-PI3K/Akt expression, but also inhibit p38 and c-Jun NH2-terminal kinases (JNK) phosphorylation. Calphostin C (PKC inhibitor) could inhibit phospho-PKC expression and exerted significant effects on extracellular signal-regulated kinases (ERK) phosphorylation, however, it had no impact on p38 and JNK phosphorylation. These results demonstrated that the LPS mediated signaling pathway of MAPK in AMs of CB rats could be described as follows: PTK-PI3K-Akt-JNK/p38 or PTK-PI3K-PKC-ERK, and PI3K may have a negative regulation on the activation of downstream proteins.

The significance of YKL-40 protein in liver fibrosis.

OBJECTIVE: The aims of this review are to describe the present knowledge about YKL-40 protein, discuss its relation to liver fibrosis, and to look ahead at future perspectives of YKL-40 research. INTRODUCTION: Liver fibrosis is characterized by excess collagen deposition, decreased extracellular matrix degradation and activation of hepatic stellate cells. Therefore, advancement in the identification of liver fibrosis biomarkers with diagnostic and prognostic values becomes an important tool for future molecular therapy. The molecular basis of YKL-40 in liver fibrosis is unknown. METHODS: A PubMed database search was performed for studies of YKL-40 in liver injury and fibrosis. RESULTS AND CONCLUSIONS: YKL-40 is an inflammatory glycoprotein involved in endothelial dysfunction by promoting chemotaxis, cell attachment and migration, reorganization, and tissue remodeling as a response to endothelial damage. Several studies demonstrate that elevated serum YKL-levels are independently associated with the presence of endothelial damage and even higher YKL-40 levels are documented in liver fibrosis. YKL-40 may play a key role in liver injury and fibrosis.

The effect of hepatic stellate cell derived-IL-11 on hepatocyte injury in hepatic fibrosis.

AIMS: This study aimed to elucidate the role of Interleukin-11 (IL-11) in hepatic fibrosis (HF) and its potential as a therapeutic target for HF treatment. MATERIALS AND METHODS: We investigated IL-11 expression in patients with varying degrees of liver injury through ELISA and immunohistochemistry. A CCl4-induced HF mouse model was constructed to study IL-11 expression and cell apoptosis using Western blotting (WB) and other techniques. The expression of IL-11 was silenced using rAAV8 in the mouse model. In vitro stimulation of hepatic stellate cells (LX-2) with TGF-ß1, and of LO-2 cells with exogenous IL-11, were performed. Cell supernatants of TGF-ß1-stimulated LX-2 were used to culture LO-2 cells, with apoptosis monitored via flow cytometry and WB. KEY FINDINGS: Increased IL-11 levels were observed in patients and the HF mouse model, with silencing reducing IL-11 expression. In vitro experiments revealed increased endogenous IL-11 in TGF-ß1-stimulated LX-2 cells and an increase in apoptotic index, IL11RA, and gp130 in IL-11-stimulated LO-2 cells. Cell apoptosis was reduced in the siRNA/IL11, siRNA/IL11RA, and anti-IL11 groups. WB and immunohistochemistry results showed upregulated p-JNK, p-ERK, and p-P53 expressions in the CCl4-induced HF mouse model and IL-11-treated LO-2 cells. SIGNIFICANCE: Our findings suggest IL-11 enhances LX-2 cell activation and proliferation, and promotes LO-2 cell apoptosis through JNK/ERK signaling pathways. This suggests that targeting IL-11 secretion may serve as a potential therapeutic strategy for HF, providing a foundation for its clinical application in HF treatment.

Blocking ATP-P1Rs axis attenuate alcohol-related liver fibrosis.

AIMS: The aim of this study was to explore the fibrogenic effects of ATP-P1Rs axis and ATP-P2Rs axis on alcohol-related liver fibrosis (ALF). MATERIALS AND METHODS: C57BL/6J CD73 knock out (KO) mice were used in our study. 8-12 weeks male mice were used as an ALF model in vivo. In conclusion, after one week of adaptive feeding, 5 % alcohol liquid diet was given for 8 weeks. High-concentration alcohol (31.5 %, 5 g/kg) was administered by gavage twice weekly, and 10 % CCl4 intraperitoneal injections (1 ml/kg) were administered twice weekly for the last two weeks. The mice in the control group were injected intraperitoneally with an equivalent volume of normal saline. Fasting for 9 h after the last injection, blood samples were collected, and related indicators were tested. In vitro, rat hepatic stellate cells (HSCs) were treated with 200 µM acetaldehyde to establish an alcoholic liver fibrosis for 48 h, then tested related indicators. KEY FINDINGS: We found that both adenosine receptors including adenosine A1, A2A, A2B, A3 receptors (A1R, A2AR, A2BR, A3R) and ATP receptors including P2X7, P2Y2 receptors (P2X7R, P2Y2R) were expressed increased in ALF. After CD73 was knocked out, we found that adenosine receptors expression decreased, ATP expression increased, and fibrosis degree decreased. SIGNIFICANCE: Based on the research, we discovered that adenosine plays a more important role in ALF. Therefore, blocking the ATP-P1Rs axis represented a potential treatment for ALF, and CD73 will become a potential therapeutic target.

BRD4 promotes hepatic stellate cells activation and hepatic fibrosis via mediating P300/H3K27ac/PLK1 axis.

Hepatic fibrosis (HF) is a reversible wound-healing response characterized by excessive extracellular matrix (ECM) deposition and secondary to persistent chronic injury. Bromodomain protein 4 (BRD4) commonly functions as a "reader" to regulate epigenetic modifications involved in various biological and pathological events, but the mechanism of HF remains unclear. In this study, we established a CCl4-induced HF model and spontaneous recovery model in mice and found aberrant BRD4 expression, which was consistent with the results in human hepatic stellate cells (HSCs)- LX2 cells in vitro. Subsequently, we found that distriction and inhibition of BRD4 restrained TGFß-induced trans-differentiation of LX2 cells into activated, proliferative myofibroblasts and accelerated apoptosis, and BRD4 overexpression blocked MDI-induced LX2 cells inactivation and promoted the proliferation and inhibited apoptosis of inactivated cells. Additionally, adeno-associated virus serotype 8-loaded short hairpin RNA-mediated BRD4 knockdown in mice significantly attenuated CCl4-induced fibrotic responses including HSCs activation and collagen deposition. Mechanistically, BRD4 deficiency inhibited PLK1 expression in activated LX2 cells, and ChIP and Co-IP assays revealed that BRD4 regulation of PLK1 was dependent on P300-mediated acetylation modification for H3K27 on the PLK1 promoter. In conclusion, BRD4 deficiency in the liver alleviates CCl4-induced HF in mice, and BRD4 participates in the activation and reversal of HSCs through positively regulating the P300/H3K27ac/PLK1 axis, providing a potential insight for HF therapy.

N6-methyladenosine-modified circIRF2, identified by YTHDF2, suppresses liver fibrosis via facilitating FOXO3 nuclear translocation.

Circular RNA (circRNA) has been implicated in liver fibrosis and modulated by multiple elusive molecular mechanisms, while the effects of N6-methyladenosine (m6A) modification on circRNA are still elusive. Herein, we identify circIRF2 from our circRNA sequencing data, which decreased in liver fibrogenesis stage and restored in resolution stage, indicating that dysregulated circIRF2 may be closely associated with liver fibrosis. Gain/loss-of-function analysis was performed to evaluate the effects of circIRF2 on liver fibrosis at both the fibrogenesis and resolution in vivo. Ectopic expression of circIRF2 attenuated liver fibrogenesis and HSCs activation at the fibrogenesis stage, whereas downregulation of circIRF2 impaired mouse liver injury repair and inflammation resolution. Mechanistically, YTHDF2 recognized m6A-modified circIRF2 and diminished circIRF2 stability, partly accounting for the decreased circIRF2 in liver fibrosis. Microarray was applied to investigate miRNAs regulated by circIRF2, our data elucidate cytoplasmic circIRF2 may directly harbor miR-29b-1-5p and competitively relieve its inhibitory effect on FOXO3, inducing FOXO3 nuclear translocation and accumulation. Clinically, circIRF2 downregulation was prevalent in liver fibrosis patients compared with healthy individuals. In summary, our findings offer a novel insight into m6A modification-mediated regulation of circRNA and suggest that circIRF2 may be an exploitable prognostic marker and/or therapeutic target for liver fibrosis.

DNMT1-mediated PTEN hypermethylation confers hepatic stellate cell activation and liver fibrogenesis in rats.

Hepatic stellate cell (HSC) activation is an essential event during liver fibrogenesis. Phosphatase and tension homolog deleted on chromosome 10 (PTEN), a tumor suppressor, is a negative regulator of this process. PTEN promoter hypermethylation is a major epigenetic silencing mechanism in tumors. The present study aimed to investigate whether PTEN promoter methylation was involved in HSC activation and liver fibrosis. Treatment of activated HSCs with the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-azadC) decreased aberrant hypermethylation of the PTEN gene promoter and prevented the loss of PTEN expression that occurred during HSC activation. Silencing DNA methyltransferase 1 (DNMT1) gene also decreased the PTEN gene promoter methylation and upregulated the PTEN gene expression in activated HSC-T6 cells. In addition, knockdown of DNMT1 inhibited the activation of both ERK and AKT pathways in HSC-T6 cells. These results suggest that DNMT1-mediated PTEN hypermethylation caused the loss of PTEN expression, followed by the activation of the PI3K/AKT and ERK pathways, resulting in HSC activation.

Adenosine receptor A2B mediates alcoholic hepatitis by regulating cAMP levels and the NF-KB pathway.

Alcoholic hepatitis is a serious form of liver damage. Inflammation is a key factor in alcoholic hepatitis and plays a key role in the progression of alcoholic liver disease. Adenosine receptor A2B (A2BAR) is a member of the adenosine receptor family and generally considered to be a negative regulator of the inflammatory response. We found that A2BAR was the most highly expressed adenosine receptor in ETOH-fed mouse liver tissue and was also highly expressed in primary Kupffer cells and ETOH-induced RAW264.7 cells. In addition, injection of BAY 60-6583 stimulated A2BAR, induced upregulation of the expression levels of cAMP, and reduced ETOH-induced steatosis and inflammation in mice. At the same time, knockdown of A2BAR in vitro increased the inflammatory response in RAW264.7 cells triggered by ETOH. After knockdown of A2BAR in vitro, the release of the inflammatory cytokines IL-6, IL-1ß and TNF-α was increased. After overexpression of A2BAR in vitro, the cAMP level was significantly increased, PKA expression was increased, the expression of phosphorylated proteins in the NF-kB signal transduction pathway was significantly affected, and the expression of the key phosphorylated protein p-P65 was decreased. However, after the simultaneous overexpression of A2BAR and inhibition of PKA, the expression of the key phosphorylated protein p-P65 was still significantly decreased. In addition, after the expression of A2BAR increased or decreased in RAW264.7 cells, AML-12 cells were cultured in the supernatant of RAW264.7 cells stimulated by ETOH, and the apoptosis rate was significantly changed by flow cytometry. These results suggest that A2BAR can reduce alcoholic steatohepatitis by upregulating cAMP levels and negatively regulating the NF-kB pathway. Overall, these findings suggest the significance of A2BAR-mediated inflammation in alcoholic liver disease.

Blockade of the P2Y2 Receptor Attenuates Alcoholic Liver Inflammation by Targeting the EGFR-ERK1/2 Signaling Pathway.

Purpose: It is well known that inflammation plays a key role in complex pathological progressions of alcohol-associated liver disease (ALD). To date, effective therapy for ALD is lacking. P2Y2 receptor (P2Y2R), a G protein-coupled P2Y purinergic receptor, represents a novel pharmacological target in many inflammations. Methods: The alcohol-associated liver injury and inflammation mouse model was established. The effect of P2Y2R on alcohol-induced liver injury and inflammation was evaluated using quantitative real-time PCR, Western blot and immunohistochemical assay. An alcohol-stimulated (100 mmol/L, for 24 h) AML-12 cell model was established. Different agonists, antagonists and P2Y2R siRNA were used to explore the possible mechanisms of P2Y2R. Results: In vivo, results showed that the hepatoprotective effect of P2Y2R blockade by significantly suppressed liver structural abnormalities and lipid infiltration, and decreased levels of ALT/AST and TNF-α/IL-1ß in the high dosage group of suramin (20 mg/kg) compared to control diet (CD)-fed mice. At the same time, we found that alcohol feeding promoted the phosphorylation of EGFR and ERK1/2, both of which were effectively inhibited by suramin (20 mg/kg). In vitro, suramin or P2Y2R silencing effectively inhibited the phosphorylation of EGFR and ERK1/2, similar to the down-regulated effects of their corresponding inhibitors (EGFR inhibitor AG1478 and ERK1/2 inhibitor U0126) accompanied by reduced levels of TNF-α and IL-1ß compared to alcohol-induced AML-12 cell. In addition, we found that silencing P2Y2R attenuated the apoptosis of hepatocyte. Conclusion: Our findings suggest that P2Y2R regulates alcoholic liver inflammation by targeting the EGFR-ERK1/2 signaling pathway and plays an important role in hepatocyte apoptosis, which may provide new ideas for the development of methods to treat ALD.

The mechanism by which ATP regulates alcoholic steatohepatitis through P2X4 and CD39.

Alcoholic liver disease caused by chronic excessive drinking has become one of the most common types of liver disease. Alcohol-induced inflammatory immune responses play a central role in the development of alcohol-associated steatohepatitis. The content and expression of ATP and P2X4 in the livers of alcoholic steatohepatitis mice are significantly increased. The content of ATP increased by 20 percent and the expression of P2X4 receptor protein was 1.3 times higher than that in the livers of normal mice. Treatment with 5-BDBD, a P2X4 receptor-specific inhibitor, significantly reduced alcohol-induced liver inflammation and lipid deposition. In RAW264.7 cell experiments, 5-BDBD inhibited the expression of P2X4 and alleviated alcohol-induced inflammation, while the CD39-specific inhibitor POM-1 reduced extracellular ATP degradation and promoted the expression of P2X4, thereby exacerbating inflammation. After treatment with 5-BDBD, P2X4 receptor protein expression decreased by 0.2 times and after treatment with POM-1, P2X4 receptor protein expression increased by 0.1 times compared to the alcohol-stimulated group. In addition, inhibition of P2X4 expression in RAW264.7 cells reduced calcium influx in RAW264.7 cells. P2X4 may induce the activation of NLRP3 inflammasomes by mediating calcium influx, thus exacerbating the inflammatory response, and inhibition of P2X4 expression can effectively block this process. Conclusion: These results suggest that the ATP-P2X4 signaling pathway promotes the inflammatory response in alcoholic steatohepatitis and that CD39 may play a protective role in regulating P2X4 expression by hydrolyzing ATP. In conclusion, the CD39 and ATP-P2X4 signaling pathways may be potential therapeutic targets for alcoholic steatohepatitis.

Blocking P2X4 purinergic receptor attenuates alcohol-related liver fibrosis by inhibiting hepatic stellate cell activation through PI3K/AKT signaling pathway.

Alcoholic liver fibrosis（ALF）, as a liver disease caused by long-term alcoholism, attracts international attention. Activation of hepatic stellate cells is a key step in the development of alcoholic-associated liver fibrosis. Increasing studies have shown that P2X4 receptor, as a component of purinoceptor family in adenosine pathway, plays an important role in numerous liver diseases. In this study, it was found that the expression of P2X4 receptor was significantly increased in the mouse liver fibrosis model fed with ethanol plus CCL4 and in the HSC-T6 cell model stimulated by acetaldehyde. In vivo, C57BL/6J mice were used to establish ALF models, and 5-BDBD, a specific inhibitor of P2X4 receptor, was injected intraperitoneally at 6-8 weeks of ALF development. The results indicated that 5-BDBD could reduce the expression of fibrotic markers and attenuate the pathological features of fibrosis, thus demonstrating the alleviation of ALF.In vitro, PI3K/AKT pathway was activated in HSC-T6 cells stimulated by acetaldehyde. Silencing P2X4 receptor or administration of 5-BDBD could inhibit the phosphorylation of PI3K and AKT, thereby inhibiting the activation of HSC-T6 cells. In addition, 5-BDBD was administered to RAW264.7 cells activated by acetaldehyde, and then part of the supernatant was added to HSC-T6 cells culture medium. The results showed that 5-BDBD could reduce the expression of classical inflammatory pathways such as TGF-ß pathway in RAW267.4 cells, thus inhibiting the activation of HSC-T6 cells. Taken together, these results suggest that P2X4 receptors may influence the progression of alcohol-related liver fibrosis by directly mediating the PI3K/AKT pathway, or indirectly by influencing RAW264.7 cells to regulate hepatic stellate cell activation.

CD73 Attenuates Alcohol-Induced Liver Injury and Inflammation via Blocking TLR4/MyD88/NF-κB Signaling Pathway.

BACKGROUND: Alcoholic liver disease (ALD) is liver damage caused by long-term drinking. Inflammation plays a central role in the progression of ALD. CD73 is a ubiquitously expressed glycosylphosphatidylinositol-anchored glycoprotein that is a key enzyme that converts ATP into adenosine. Evidence has shown that CD73 plays an important role in many diseases, but the role and mechanism of CD73 in alcohol-induced liver injury and inflammation is still unclear. METHODS: The alcohol-induced liver injury and inflammation mouse model was established. The rAAV9-CD73 was used to overexpress CD73. Isolation of primary macrophages (MΦ) from the liver was conducted. The effects of CD73 on alcohol-induced liver injury and inflammation were evaluated by quantitative real­time PCR, Western blotting, ELISA, and immunohistochemical assay. Flow cytometry was used to detect the cell cycle and apoptosis. RESULTS: Our results showed that overexpression of CD73 can reduce alcohol-induced liver damage, lipid accumulation, and the secretion of inflammatory cytokines. pEX3-CD73 can promote RAW264.7 cells proliferation and inhibit apoptosis via suppressing the activation of TLR4/MyD88/NF-κB signaling pathway. Inhibition of TLR4 further enhanced the anti-inflammatory effect of overexpression of CD73. CONCLUSION: Overexpression of CD73 can reduce alcohol-induced liver injury and inflammation. CD73 may serve as a potential therapeutic target for ALD.

P2X7 Receptor in Alcoholic Steatohepatitis and Alcoholic Liver Fibrosis.

Alcoholic liver disease is one of the most common chronic liver diseases in the world. It is a liver disease caused by prolonged heavy drinking and its main clinical features are nausea, vomiting, enlargement of the liver, and jaundice. Recent studies suggest that Kupffer cell-mediated inflammatory response is a core driver in the development of alcoholic steatohepatitis and alcoholic liver fibrosis. As a danger signal, extracellular ATP activates the assembly of NLPR3 inflammasome by acting on purine P2X7 receptor, the activated NLRP3 inflammasome prompts ASC to cleave pro-cCaspase-1 into active caspase-1in KCs. Active caspase-1 promotes the conversion of pro-IL-1ß to IL-1ß, which further enhances the inflammatory response. Here, we briefly review the role of the P2X7R-NLRP3 inflammasome axis in the pathogenesis of alcoholic liver disease and the evolution of alcoholic steatohepatitis and alcoholic liver fibrosis. Regulation of the inflammasome axis of P2X7R-NLRP3 may be a new approach for the treatment of alcoholic liver disease.

CD73 aggravates alcohol-related liver fibrosis by promoting autophagy mediated activation of hepatic stellate cells through AMPK/AKT/mTOR signaling pathway.

CD73 is a membrane-bound glycoprotein that can dephosphorylate AMP to adenosine. Increasing evidence has shown that CD73 is involved in the occurrence and development of liver fibrosis. However, the potential mechanism by which CD73 affects the progression of alcohol-related liver fibrosis (ALF) remains unknown. This study aimed to examine the role and mechanism of CD73 in autophagy in HSC-T6 cells and its role in ALF in mice that treated with alcohol plus CCl4. We found that CD73 knockout reduced serum alanine aminotransferase and aspartate aminotransferase levels and decreased liver injury and collagen deposition. Furthermore, autophagy-related indicators were downregulated in the liver fibrosis tissues of CD73-/- (EtOH + CCl4) mice. In vitro, the expression of CD73 and autophagy increased in activated HSC-T6 cells. Autophagy inhibitor, 3-methyladenine, reduced autophagy and activation of acetaldehyde-induced HSC-T6 cells. When using CD73-siRNA, autophagy in HSC-T6 cells was found to be downregulated. However, the CD73 plasmid increased the activation and autophagy of hepatic stellate cells (HSCs). In addition, CD73 induced autophagy through the AMPK/AKT/mTOR pathway, which is characterized by an increase in the ratio of P-AMPKα/AMPKα and a decrease in the ratio of P-AKT/AKT and P-mTOR/mTOR. Our study found that CD73 promotes HSCs activation by regulating autophagy through the AMPK/AKT/mTOR signaling pathway.