The regulatory role and mechanism of autophagy in energy metabolism-related hepatic fibrosis

Targeted inhibition of autophagy in hepatic stellate cells by hydroxychloroquine: An effective therapeutic approach for the treatment of liver fibrosis

BACKGROUND AND PURPOSE

Liver fibrosis is a wound-healing reaction which is the main cause of chronic liver diseases worldwide. The activated hepatic stellate cell (aHSC) is the main driving factor in the development of liver fibrosis. Inhibiting autophagy of aHSC can prevent the progression of liver fibrosis, but inhibiting autophagy of other liver cells has opposite effects. Hence, targeted inhibition of autophagy in aHSC is quite necessary for the treatment of liver fibrosis, which prompts us to explore the targeted delivery system of small molecule autophagy inhibitor hydroxychloroquine (HCQ) that can target aHSC and alleviate the liver fibrosis.

METHODS

The delivery system of HCQ@retinol-liposome nanoparticles (HCQ@ROL-LNPs) targeting aHSC was constructed by the film dispersion and pH-gradient method. TGF-β-induced HSC activation and thioacetamide (TAA)-induced liver fibrosis mice model were established, and the targeting ability and therapeutic effect of HCQ@ROL-LNPs in liver fibrosis were studied subsequently in vitro and in vivo.

RESULTS

HCQ@ROL-LNPs have good homogeneity and stability. They inhibited the autophagy of aHSC selectively by HCQ and reduced the deposition of extracellular matrix (ECM) and the damage to other liver cells. Compared with the free HCQ and HCQ@LNPs, HCQ@ROL-LNPs had good targeting ability, showing enhanced therapeutic effect and low toxicity to other organs.

CONCLUSION

Construction of HCQ@ROL-LNPs delivery system lays a theoretical and experimental foundation for the treatment of liver fibrosis and promotes the development of clinical therapeutic drugs for liver diseases.

Bone mesenchymal stem cells improve cholestatic liver fibrosis by targeting ULK1 to regulate autophagy through PI3K/AKT/mTOR pathway

Cholestatic liver disease (CLD) is a severe disease, which can progress to liver cirrhosis, even liver cancer. Hepatic stellate cells (HSCs) activation plays a crucial role in CLD development. Bone mesenchymal stem cells (BMSCs) treatment was demonstrated to be beneficial in liver diseases. However, the therapeutic effect and mechanism of BMSCs on CLD are poorly known. In the present study, we investigated the therapeutic effects and underlying mechanisms of BMSCs transplantation in mouse models of bile duct ligation-induced cholestatic liver fibrosis (CLF). The results revealed that BMSCs significantly improved liver function and reduced the formation of fibrosis after portal vein transplantation. Mechanistically, after coculturing BMSCs and HSCs, we identified that BMSCs alleviated starvation-induced HSCs activation. Further, BMSCs inhibited HSCs activation by decreasing autophagy, and PI3K/AKT/mTOR pathway was involved in the regulation. More importantly, ULK1 is identified as the main autophagy-related gene regulated by BMSCs in HSCs autophagy. Overexpression of ULK1 reversed the suppression of HSCs autophagy by BMSCs. Collectively, our results provide a theoretical basis for BMSCs targeting ULK1 to attenuate HSCs autophagy and activation and suggest that BMSCs or ULK1 may be an alternative therapeutic approach/target for the treatment of CLF.

Ba-Qi-Rougan formula alleviates hepatic fibrosis by suppressing hepatic stellate cell activation via the MSMP/CCR2/PI3K pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The Ba-Qi-Rougan formula (BQRGF) is a traditional and effective compound prescription from Traditional Chinese Medicine (TCM) utilized in treating hepatic fibrosis (HF).

AIM OF THE STUDY

We aimed to evaluate the therapeutic efficacy of BQRGF on HF and explore the underlying mechanisms of action.

MATERIALS AND METHODS

UPLC-Q-TOF-MS technology was employed to identify the material basis of BQRGF. Mice with carbon tetrachloride (CCl4)-induced HF received BQRGF at three doses (3.87, 7.74, and 15.48 g/kg per day). We examined serum and liver biochemical indicators and liver histology to assess the therapeutic impact. Primary mouse cells were isolated and utilized for experimental analysis. MSMP expression levels were examined in vitro and in vivo experimental models, including human and mouse tissue. Furthermore, lentivirus and small interfering RNA (siRNA) transfections were employed to manipulate microseminoprotein (MSMP) expression in LO2 cells (human normal liver cells). These manipulated LO2 cells were then co-cultured with LX2 human hepatic stellate cells (HSCs). Through the modulation of MSMP expression in co-cultured cells, administering recombinant MSMP (rMSMP) with or without BQRGF-medicated serum, and using specific pathway inhibitors or agonists in LX2 cells, we elucidated the underlying mechanisms.

RESULTS

A total of 48 compounds were identified from BQRGF, with 12 compounds being absorbed into the bloodstream and 9 compounds being absorbed into the liver. Four weeks of BQRGF treatment in the HF mouse model led to significant improvements in biochemical and molecular assays and histopathology, particularly in the medium and high-dose groups. These improvements included a reduction in the level of liver injury and fibrosis-related factors. MSMP levels were elevated in human and mouse fibrotic liver tissues, and this increase was mitigated in HF mice treated with BQRGF. Moreover, primary cells and co-culture studies revealed that BQRGF reduced MSMP expression, decreased the expression of the hepatic stellate cell (HSC) activation markers, and suppressed critical phosphorylated protein levels in the CCR2/PI3K/AKT pathway. These findings were further validated using CCR2/PI3K/AKT signaling inhibitors and agonists in MSMP-activated LX2 cells.

CONCLUSIONS

Collectively, our results suggest that BQRGF combats HF by diminishing MSMP levels and inhibiting MSMP-induced HSC activation through the CCR2/PI3K/AKT pathway.

Roles and therapeutic targeting of dendritic cells in liver fibrosis

Liver fibrosis is a common pathological condition marked by excessive accumulation of extracellular matrix proteins, resulting in irreversible cirrhosis and cancer. Dendritic cells (DCs) act as the crucial component of hepatic immunity and are believed to affect fibrosis by regulating the proliferation and differentiation of hepatic stellate cells (HSCs), a key mediator of fibrogenesis, and by interplaying with immune cells in the liver. This review concisely describes the process of fibrogenesis, and the phenotypic and functional characteristics of DCs in the liver. Besides, it focuses on the interaction between DCs and HSCs, T cells, and natural killer (NK) cells, as well as the dual roles of DCs in liver fibrosis, for the sake of exploring the potential of targeting DCs as a therapeutic strategy for the disease.

Copper toxicity in the liver of broiler chicken: insights from metabolomics and AMPK-mTOR mediated autophagy perspective

Exposure to copper (Cu) has been associated with metabolic disorders in animals and humans, but the underlying mechanism remains unclear. One-day-old broiler chickens, numbering a total of 192, were nourished with dietary intakes that contained varying concentrations of Cu, specifically 11, 110, 220, and 330 mg/kg of Cu, for a period extending over a duration of 7 wk. As a result of the study, Cu exposure resulted in vacuolization, fragmentation of mitochondria cristae, and the increase of autophagosomes in hepatocytes. Metabolomics analysis illustrated that Cu caused a total of 59 different metabolites in liver, predominantly associated with the glycerophospholipid metabolic pathway, leading to metabolic disruption. Moreover, high-Cu diet markedly reduced the levels of AMPKα1, p-AMPKα1, mTOR, and p-mTOR and enhanced the expression levels of the autophagy-related factors (Atg5, Dynein, Beclin1, and LC3-II). Overall, Cu exposure caused chicken liver injury and resulted in disturbed metabolic processes and mediated autophagy primarily through the AMPK-mTOR axis.

CircUTRN24/miR-483-3p/IGF-1 Regulates Autophagy Mediated Liver Fibrosis in Biliary Atresia

Biliary atresia (BA) is a rare neonatal cholestatic disease that presents with a marked bile duct reaction and rapid fibrotic development. Our earlier research has shown that circUTRN24 is highly elevated in BA, but the exact molecular mechanism is still unknown. This study attempted to investigate whether circUTRN24 induces BA liver fibrosis through regulation of autophagy and to elucidate its molecular mechanism. Using TGF-β-treated hepatic stellate cells (HSC) LX-2, we created a liver fibrosis model. qRT-PCR was used to analyze the expression of circUTRN24, miR-483-3p, and IGF-1. Western blot analysis was used to assess the expression of IGF-1, HSC activation-related proteins, and autophagy-related proteins. The TGF-β-induced LX-2 cell fibrosis model was then supplemented with circUTRN24 siRNA, miR-483-3p mimics, and the autophagy activator Rapamycin, and functional rescue tests were carried out to investigate the role of circUTRN24, miR-483-3p, and autophagy in BA liver fibrosis. Using a luciferase reporter assay, a direct interaction between miR-483-3p and circUTRN24 or IGF-1 was discovered. With the increase of TGF-β treatment concentration, circUTRN24 expression also gradually increased, as did HSC activation and autophagy-related protein. si-circUTRN24 significantly decreased circUTRN24 expression and inhibited HSC activation and autophagy, which was reversed by Rapamycin. Through bioinformatics prediction and validation, we found circUTRN24 might act through miR-483-3p targeting IGF-1 in the autophagy-related mTOR pathway. Furthermore, miR-483-3p mimics significantly increased miR-483-3p expression and inhibited HSC activation and autophagy, which were reversed by Rapamycin. Functional rescue experiments showed that si-circUTRN24 inhibited circUTRN24 and IGF-1 expressions and promoted miR-483-3p expression, while the miR-483-3p inhibitor abolished these effects. These findings imply that circUTRN24/miR-483-3p/IGF-1 axis mediated LX-2 cell fibrosis by regulating autophagy.

Loureirin B ameliorates cholestatic liver fibrosis via AKT/mTOR/ATG7-mediated autophagy of hepatic stellate cells

AIM OF THE STUDY

Chronic cholestasis leads to liver fibrosis, which lacks effective treatment. In this study, we investigated the role and mechanisms of action of loureirin B (LB) in cholestatic liver fibrosis.

MATERIALS AND METHODS

Bile duct ligation (BDL)-induced hepatic fibrosis mice were used as in vivo models. Transforming growth factor-β1 (TGF-β1)-pretreated HSC-T6 cells were used to explore the mechanism by which LB attenuates liver fibrosis in vitro. RNA sequencing, quantitative PCR (qPCR), western blotting, immunohistochemistry and immunofluorescence were performed to detect the fibrosis markers and measure autophagy levels. Flow cytometry, cell counting kit-8 (CCK-8) assay, and 5'-ethynyl-2'-deoxyuridine (EdU) assay were conducted to detect cell proliferation and viability. GFP-RFP-LC3 adenovirus, autophagy-related protein 7 (ATG7) siRNA, and bafilomycin A1 (BafA1) were used to verify autophagic flux.

RESULTS

Our results showed that LB ameliorates liver injury, inhibits collagen deposition, and decreases the expressions of fibrosis-related markers in BDL-induced mouse livers. In vitro, we found that LB inhibited proliferation and migration, promoted apoptosis, and inhibited the activation of HSC-T6 cells pretreated with TGF-β1. RNA sequencing analysis of HSC-T6 cells showed that LB treatment predominantly targeted autophagy-related pathways. Further protein analysis indicated that LB downregulated the expression of phosphorylated AKT (p-AKT) and phosphorylated mTOR (p-mTOR), and upregulated LC3-II, p62, and ATG7 both in vivo and in vitro. Intriguingly, ATG7 inactivation reversed the antifibrotic effects of LB on HSC-T6 cells.

CONCLUSIONS

LB can improve BDL-induced liver fibrosis by inhibiting the activation and proliferation of HSCs and is expected to be a promising antifibrotic drug.

Ganoderma lucidum ethanol extracts ameliorate hepatic fibrosis and promote the communication between metabolites and gut microbiota g_Ruminococcus through the NF-κB and TGF-β1/Smads pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum, a traditional edible medicinal mushroom, has been widely reported to improve liver diseases as a dietary intervention for people. Ganoderma lucidum extracts, primarily total triterpenoids (GLTTs), are one of the bioactive ingredients that have excellent beneficial effects on hepatic fibrosis. Therefore, its prevention and reversal are particularly critical due to the increasing number of patients with chronic liver diseases worldwide.

AIM OF THE STUDY

The study aimed to evaluate whether GLTTs had a hepatoprotective effect against hepatic fibrosis through metabolic perturbations and gut microbiota changes and its underlying mechanisms.

MATERIALS AND METHODS

The compound compositions of GLTTs were quantified, and carbon tetrachloride (CCl4)-induced hepatic fibrosis rats were used to investigate the cause of the improvement in various physiological states with GLTTs treatment, and to determine whether its consequent effect was associated with endogenous metabolites and gut microbiota using UPLC-Q-TOF-MSE metabolomics and 16S rRNA gene sequencing technology.

RESULTS

GLTTs alleviated physical status, reduced liver pathological indicators, proinflammatory cytokines, and deposition of hepatic collagen fibers via regulating the NF-κB and TGF-β1/Smads pathways. The untargeted metabolomics analysis identified 16 potential metabolites that may be the most relevant metabolites for gut microbiota dysbiosis and the therapeutic effects of GLTTs in hepatic fibrosis. Besides, although GLTTs did not significantly affect the α-diversity indexes, significant changes were observed in the composition of microflora structure. In addition, Spearman analysis revealed strong correlations between endogenous metabolites and gut microbiota g_Ruminococcus with hepatic fibrosis.

CONCLUSION

GLTTs could provide a potential target for the practical design and application of novel functional food ingredients or drugs in the therapy of hepatic fibrosis.

Discovery of LH10, a novel fexaramine-based FXR agonist for the treatment of liver disease

Farnesoid X receptor (FXR) was considered as a promising drug target in the treatment of cholestasis, drug-induced liver injury, and non-alcoholic steatohepatitis (NASH). However, the existing FXR agonists have shown different degrees of side effects in clinical trials without clear interpretation. MET-409 in clinical phase Ⅲ, has been proven significantly fewer side effects than that of other FXR agonists. This may be due to the completely different structure of FEX and other non-steroidal FXR agonists. Herein, the structure-based drug design was carried out based on FEX, and the more active FXR agonist LH10 (FEX EC50 = 0,3 μM; LH10 EC50 = 0.14 μM)) was screened out by the comprehensive SAR studies. Furthermore, LH10 exhibited robust hepatoprotective activity on the ANIT-induced cholestatic model and APAP-induced acute liver injury model, which was even better than positive control OCA. In the nonalcoholic steatohepatitis (NASH) model, LH10 significantly improved the pathological characteristics of NASH by regulating several major pathways including lipid metabolism, inflammation, oxidative stress, and fibrosis. With the above attractive results, LH10 is worthy of further evaluation as a novel agent for the treatment of liver disorders.

Autophagy suppression facilitates macrophage M2 polarization via increased instability of NF-κB pathway in hepatocellular carcinoma

The tumor microenvironment is a highly heterogeneous circumstance composed of multiple components, while tumor-associated macrophages (TAMs) are major innate immune cells with highly plastic and are always educated by tumor cells to structure an advantageous pro-tumor immune microenvironment. Despite emerging evidence focalizing the role of autophagy in other immune cells, the regulatory mechanism of autophagy in macrophage polarization remains poorly understood. Herein, we demonstrated that hepatocellular carcinoma (HCC) cells educated macrophages toward M2-like phenotype polarization under the condition of coculture. Moreover, we observed that inhibition of macrophage autophagy promoted M2-like macrophage polarization, while the tendency was impeded when autophagy was motivated. Mechanistically, macrophage autophagy inhibition inactivates the NF-κB pathway by increasing the instability of TAB3 via ubiquitination degradation, which leads to the M2-like phenotype polarization of macrophages. Both immunohistochemistry staining using human HCC tissues and experiment in vivo verified autophagy inhibition is correlated with M2 macrophage polarization. Altogether, we illustrated that macrophage autophagy was involved in the process of HCC cells domesticating M2 macrophage polarization via the NF-κB pathway. These results provide a new target to interfere with the polarization of macrophages to M2-like phenotype during HCC progression.

Autophagy in peritoneal fibrosis

Peritoneal dialysis (PD) is a widely accepted renal replacement therapy for patients with end-stage renal disease (ESRD). Morphological and functional changes occur in the peritoneal membranes (PMs) of patients undergoing long-term PD. Peritoneal fibrosis (PF) is a common PD-related complication that ultimately leads to PM injury and peritoneal ultrafiltration failure. Autophagy is a cellular process of "self-eating" wherein damaged organelles, protein aggregates, and pathogenic microbes are degraded to maintain intracellular environment homeostasis and cell survival. Growing evidence shows that autophagy is involved in fibrosis progression, including renal fibrosis and hepatic fibrosis, in various organs. Multiple risk factors, including high-glucose peritoneal dialysis solution (HGPDS), stimulate the activation of autophagy, which participates in PF progression, in human peritoneal mesothelial cells (HPMCs). Nevertheless, the underlying roles and mechanisms of autophagy in PF progression remain unclear. In this review, we discuss the key roles and potential mechanisms of autophagy in PF to offer novel perspectives on future therapy strategies for PF and their limitations.

A bibliometric and visualized analysis of liver fibrosis from 2002 to 2022

Fibrosis of the liver is a degenerative alteration that occurs in the majority of chronic liver disorders. Further progression can lead to cirrhosis, liver failure, and hepatocellular carcinoma, which can seriously affect the health and lives of patients. The field of liver fibrosis research has flourished in the last 20 years, with approximately 9000 articles retrieved from the Web of Science Core Collection database alone. In order to identify future research hotspots and potential paths in a thorough and scientifically reliable manner, it is important to organize and visualize the research on this topic from a holistic and very general perspective. This study used bibliometric analysis with CiteSpace and VOSviewer software to provide a quantitative analysis, hotspot mining, and commentary of articles published in the field of liver fibrosis over the last 20 years. This bibliometric analysis contains a total of 8994 articles with 45667 authors from 6872 institutions in 97 countries, published in 1371 journals and citing 156 309 references. The literature volume has steadily increased over the last 20 years. Research has focused on gastroenterology and hepatology, pharmacology and pharmacy, and medicine, research, and experimental areas. We found that the pathological mechanisms, diagnostic and quantitative methods, etiology, and antifibrotic strategies constitute the knowledge structure of liver fibrosis. Finding mechanisms for liver fibrosis regression, identifying precise noninvasive diagnostic and prognostic biomarkers, and creating efficient liver fibrosis patient treatments are the main goals of current research.

Traditional Chinese medicine: An important source for discovering candidate agents against hepatic fibrosis

Hepatic fibrosis (HF) refers to the pathophysiological process of connective tissue dysplasia in the liver caused by various pathogenic factors. Nowadays, HF is becoming a severe threat to the health of human being. However, the drugs available for treating HF are limited. Currently, increasing natural agents derived from traditional Chinese medicines (TCMs) have been found to be beneficial for HF. A systemic literature search was conducted from PubMed, GeenMedical, Sci-Hub, CNKI, Google Scholar and Baidu Scholar, with the keywords of “traditional Chinese medicine,” “herbal medicine,” “natural agents,” “liver diseases,” and “hepatic fibrosis.” So far, more than 76 natural monomers have been isolated and identified from the TCMs with inhibitory effect on HF, including alkaloids, flavones, quinones, terpenoids, saponins, phenylpropanoids, and polysaccharides, etc. The anti-hepatic fibrosis effects of these compounds include hepatoprotection, inhibition of hepatic stellate cells (HSC) activation, regulation of extracellular matrix (ECM) synthesis & secretion, regulation of autophagy, and antioxidant & anti-inflammation, etc. Natural compounds and extracts from TCMs are promising agents for the prevention and treatment of HF, and this review would be of great significance to development of novel drugs for treating HF.

Targeted activation of HNF4α/HGF1/FOXA2 reverses hepatic fibrosis via exosome-mediated delivery of CRISPR/dCas9-SAM system

Aim: Hepatic fibrosis is one of the most common conditions worldwide, and yet no effective antifibrotic therapy is available. This study aimed to reverse hepatic fibrosis via exosome-mediated delivery of the CRISPR/dCas9-SAM system. Materials & methods: The authors constructed a modified-exosome delivery system targeting hepatic stellate cells (HSCs), and constructed the CRISPR/dCas9-SAM system inducing HSCs convert into hepatocyte-like cells in vitro and in vivo. Results: RBP4-modified exosomes could efficiently load and deliver the CRISPR/dCas9 system to HSCs. The in vitro CRISPR/dCas9 system induced the conversion from HSCs to hepatocyte-like cells via targeted activation of HNF4α/HGF1/FOXA2 genes. Importantly, in vivo targeted delivery of this system significantly attenuated CCl₄-induced hepatic fibrosis. Conclusion: Targeted activation of HNF4α/HGF1/FOXA2 reverses hepatic fibrosis via exosome-mediated delivery of the CRISPR/dCas9-SAM system, which provides a feasible antifibrotic strategy.

Crosstalk Between Autophagy and Innate Immunity: A Pivotal Role in Hepatic Fibrosis

Liver fibrosis is a repair process of chronic liver injuries induced by toxic substances, pathogens, and inflammation, which exhibits a feature such as deposition of the extracellular matrix. The initiation and progression of liver fibrosis heavily relies on excessive activation of hepatic stellate cells (HSCs). The activated HSCs express different kinds of chemokine receptors to further promote matrix remodulation. The long-term progression of liver fibrosis will contribute to dysfunction of the liver and ultimately cause hepatocellular carcinoma. The liver also has abundant innate immune cells, including DCs, NK cells, NKT cells, neutrophils, and Kupffer cells, which conduct complicated functions to activation and expansion of HSCs and liver fibrosis. Autophagy is one specific type of cell death, by which the aberrantly expressed protein and damaged organelles are transferred to lysosomes for further degradation, playing a crucial role in cellular homeostasis. Autophagy is also important to innate immune cells in various aspects. The previous studies have shown that dysfunction of autophagy in hepatic immune cells can result in the initiation and progression of inflammation in the liver, directly or indirectly causing activation of HSCs, which ultimately accelerate liver fibrosis. Given the crosstalk between innate immune cells, autophagy, and fibrosis progression is complicated, and the therapeutic options for liver fibrosis are quite limited, the exploration is essential. Herein, we review the previous studies about the influence of autophagy and innate immunity on liver fibrosis and the molecular mechanism to provide novel insight into the prevention and treatment of liver fibrosis.