Dihydroartemisinin alleviates bile duct ligation-induced liver fibrosis and hepatic stellate cell activation by interfering with the PDGF-βR/ERK signaling pathway

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.

m6A methylation-induced NR1D1 ablation disrupts the HSC circadian clock and promotes hepatic fibrosis

The roles of nuclear receptor subfamily 1 group d member 1 (NR1D1) and the circadian clock in liver fibrosis remain unclear. Here, we showed that liver clock genes, especially NR1D1, were dysregulated in mice with carbon tetrachloride (CCl₄)-induced liver fibrosis. In turn, disruption of the circadian clock exacerbated experimental liver fibrosis. NR1D1-deficient mice were more sensitive to CCl₄-induced liver fibrosis, supporting a critical role of NR1D1 in liver fibrosis development. Validation at the tissue and cellular levels showed that NR1D1 was primarily degraded by N6-methyladenosine (m⁶A) methylation in a CCl₄-induced liver fibrosis model, and this result was also validated in rhythm-disordered mouse models. In addition, the degradation of NR1D1 further inhibited the phosphorylation of dynein-related protein 1-serine site 616 (DRP1^S616), resulting in weakened mitochondrial fission function and increased mitochondrial DNA (mtDNA) release in hepatic stellate cell (HSC), which in turn activated the cGMP-AMP synthase (cGAS) pathway. Activation of the cGAS pathway induced a local inflammatory microenvironment that further stimulated liver fibrosis progression. Interestingly, in the NR1D1 overexpression model, we observed that DRP1^S616 phosphorylation was restored, and cGAS pathway was also inhibited in HSCs, resulting in improved liver fibrosis. Taken together, our results suggest that targeting NR1D1 may be an effective approach to liver fibrosis prevention and management.

Dihydroartemisinin Exerts Antifibrotic and Anti-Inflammatory Effects in Graves' Ophthalmopathy by Targeting Orbital Fibroblasts

Graves' ophthalmopathy (GO) is a common orbital disease that threatens visual function and appearance. Orbital fibroblasts (OFs) are considered key target and effector cells in GO. In addition, hyaluronan (HA) production, inflammation, and orbital fibrosis are intimately linked to the pathogenesis of GO. In this study, we explored the therapeutic effects of dihydroartemisinin (DHA), an antimalarial drug, on GO-derived, primary OFs. CCK8 and EdU assays were applied to evaluate the antiproliferative effect of DHA on OFs. Wound healing assays were conducted to assess OF migration capacity, while qRT-PCR, western blotting, ELISA, and immunofluorescence were used to determine the expression of fibrosis-related and pro-inflammatory markers in these cells. Moreover, RNA sequencing was conducted to identify differentially expressed genes (DEGs) in DHA-treated OFs, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs was performed to explore potential mechanisms mediating the antifibrotic effect of DHA on GO-derived OFs. Results showed that DHA dose-dependently inhibited OF proliferation and downregulated, at the mRNA and protein levels, TGF-β1-induced expression of fibrosis markers, including alpha smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF). Furthermore, DHA inhibited TGF-β1 induced phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3), which suggested that DHA exerted antifibrotic effects via suppression of the ERK and STAT3 signaling pathways. In addition, DHA suppressed the expression of pro-inflammatory cytokines and chemokines, including IL-6, IL-8, CXCL-1, MCP-1, and ICAM-1, and attenuated HA production induced by IL-1β in GO-derived OFs. In conclusion, our study provides first-time evidence that DHA may significantly alleviate pathogenic manifestations of GO by inhibiting proliferation, fibrosis- and inflammation-related gene expression, and HA production in OFs. These data suggest that DHA may be a promising candidate drug for treatment of GO.

Research progress of natural products interfering with cell signaling pathway in liver fibrosis

Liver cirrhosis and hepatocellular carcinoma are the late stage of liver fibrosis. How to early use drugs to intervene in liver fibrosis is a prerequisite for the reversal of liver fibrosis. This paper mainly introduces a cell signaling transduction pathway in liver fibrosis and the intervention of natural products in order to provide theoretical basis for the treatment of liver fibrosis.

Development of human iPSC-derived quiescent hepatic stellate cell-like cells for drug discovery and in vitro disease modeling

Hepatic stellate cells (HSCs) play a central role in the progression of liver fibrosis by producing extracellular matrices. The development of drugs to suppress liver fibrosis has been hampered by the lack of human quiescent HSCs (qHSCs) and an appropriate in vitro model that faithfully recapitulates HSC activation. In the present study, we developed a culture system to generate qHSC-like cells from human-induced pluripotent stem cells (hiPSCs) that can be converted into activated HSCs in culture. To monitor the activation process, a red fluorescent protein (RFP) gene was inserted in hiPSCs downstream of the activation marker gene actin alpha 2 smooth muscle (ACTA2). Using qHSC-like cells derived from RFP reporter iPSCs, we screened a repurposing chemical library and identified therapeutic candidates that prevent liver fibrosis. Hence, hiPSC-derived qHSC-like cells will be a useful tool to study the mechanism of HSC activation and to identify therapeutic agents.

Anti-malarial drug: the emerging role of artemisinin and its derivatives in liver disease treatment

Artemisinin and its derivatives belong to a family of drugs approved for the treatment of malaria with known clinical safety and efficacy. In addition to its anti-malarial effect, artemisinin displays anti-viral, anti-inflammatory, and anti-cancer effects in vivo and in vitro. Recently, much attention has been paid to the therapeutic role of artemisinin in liver diseases. Several studies suggest that artemisinin and its derivatives can protect the liver through different mechanisms, such as those pertaining to inflammation, proliferation, invasion, metastasis, and induction of apoptosis and autophagy. In this review, we provide a comprehensive discussion of the underlying molecular mechanisms and signaling pathways of artemisinin and its derivatives in treating liver diseases. Further pharmacological research will aid in determining whether artemisinin and its derivatives may serve as promising medicines for the treatment of liver diseases in the future.

Dihydroartemisinin regulates lipid droplet metabolism in hepatic stellate cells by inhibiting lncRNA-H19-induced AMPK signal

Activation of hepatic stellate cells (HSCs) is a central event in the pathogenesis of liver fibrosis and is often accompanied by the disappearance of lipid droplets (LDs). Although interference with LD metabolism can effectively reverse the activation of HSCs, there is currently no effective therapy for liver fibrosis. Our previous evidence indicates that long non-coding RNA (lncRNA)-H19 plays an essential role in LD metabolism of HSC. In this study, we investigated the potential molecular mechanism of dihydroartemisinin (DHA) inhibits LD metabolism and liver fibrosis by regulating H19-AMPK pathway. We found that DHA restores LDs content in activated HSCs via reducing the transcription of H19 driven by hypoxia inducible factor 1 subunit alpha (HIF1α) and inhibiting the lipid oxidation signal mediated by AMP-activated protein kinase (AMPK) phosphorylation. In vivo experiments, we have proved that DHA reduced the deposition of extracellular matrix (ECM) and reduce the level of liver fibrosis in CCl₄-induced liver fibrosis of mice. In summary, our results emphasize the importance of H19 in liver fibrosis and the potential of DHA to regulate H19 to treat liver fibrosis, providing a new direction for the prevention and treatment of liver fibrosis.

Therapeutic challenges at the preclinical level for targeted drug development for Opisthorchis viverrini-associated cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma (CCA) is a malignant tumor of bile duct epithelium with the highest incidence found in Thailand. Some patients are considered suitable for adjuvant therapy and surgical resection is currently the curative treatment for CCA patients. Tumor recurrence is still a hurdle after treatment; hence, finding novel therapeutic strategies to combat CCA is necessary for improving outcome for patients.

AREAS COVERED

We discuss targeted therapies and other novel treatment approaches which include protein kinase inhibitors, natural products, amino acid transporter-based inhibitors, immunotherapy, and drug repurposing. We also examine the challenges of tumor heterogeneity, cancer stem cells (CSCs), the tumor microenvironment, exosomes, multiomics studies, and the potential of precision medicine.

EXPERT OPINION

Because CCA is difficult to diagnose at the early stage, the traditional treatment approaches are not effective for many patients and most tumors recur. Consequently, researchers are exploring multi-aspect molecular carcinogenesis to uncover molecular targets for further development of novel targeted drugs.

The Apelin-Apelin Receptor Axis Triggers Cholangiocyte Proliferation and Liver Fibrosis During Mouse Models of Cholestasis

BACKGROUND AND AIMS

Apelin (APLN) is the endogenous ligand of its G protein-coupled receptor, apelin receptor (APJ). APLN serum levels are increased in human liver diseases. We evaluated whether the APLN-APJ axis regulates ductular reaction and liver fibrosis during cholestasis.

APPROACH AND RESULTS

We measured the expression of APLN and APJ and serum APLN levels in human primary sclerosing cholangitis (PSC) samples. Following bile duct ligation (BDL) or sham surgery, male wild-type (WT) mice were treated with ML221 (APJ antagonist) or saline for 1 week. WT and APLN^-/- mice underwent BDL or sham surgery for 1 week. Multidrug resistance gene 2 knockout (Mdr2^-/- ) mice were treated with ML221 for 1 week. APLN levels were measured in serum and cholangiocyte supernatants, and cholangiocyte proliferation/senescence and liver inflammation, fibrosis, and angiogenesis were measured in liver tissues. The regulatory mechanisms of APLN-APJ in (1) biliary damage and liver fibrosis were examined in human intrahepatic biliary epithelial cells (HIBEpiCs) treated with APLN and (2) hepatic stellate cell (HSC) activation in APLN-treated human HSC lines (HHSteCs). APLN serum levels and biliary expression of APLN and APJ increased in PSC samples. APLN levels were higher in serum and cholangiocyte supernatants from BDL and Mdr2^-/- mice. ML221 treatment or APLN^-/- reduced BDL-induced and Mdr2^-/- -induced cholangiocyte proliferation/senescence, liver inflammation, fibrosis, and angiogenesis. In vitro, APLN induced HIBEpiC proliferation, increased nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) expression, reactive oxygen species (ROS) generation, and extracellular signal-regulated kinase (ERK) phosphorylation. Pretreatment of HIBEpiCs with ML221, diphenyleneiodonium chloride (Nox4 inhibitor), N-acetyl-cysteine (NAC, ROS inhibitor), or PD98059 (ERK inhibitor) reduced APLN-induced cholangiocyte proliferation. Activation of HHSteCs was induced by APLN but reduced by NAC.

CONCLUSIONS

The APLN-APJ axis induces cholangiocyte proliferation through Nox4/ROS/ERK-dependent signaling and HSC activation through intracellular ROS. Modulation of the APLN-APJ axis may be important for managing cholangiopathies.

Inhibition of 5-Lipoxygenase in Hepatic Stellate Cells Alleviates Liver Fibrosis

Background and Purpose: Activation of hepatic stellate cells (HSC) is a central driver of liver fibrosis. 5-lipoxygenase (5-LO) is the key enzyme that catalyzes arachidonic acid into leukotrienes. In this study, we examined the role of 5-LO in HSC activation and liver fibrosis.

Main Methods: Culture medium was collected from quiescent and activated HSC for target metabolomics analysis. Exogenous leukotrienes were added to culture medium to explore their effect in activating HSC. Genetic ablation of 5-LO in mice was used to study its role in liver fibrosis induced by CCl₄ and a methionine-choline-deficient (MCD) diet. Pharmacological inhibition of 5-LO in HSC was used to explore the effect of this enzyme in HSC activation and liver fibrosis.

Key Results: The secretion of LTB₄ and LTC₄ was increased in activated vs. quiescent HSC. LTB₄ and LTC₄ contributed to HSC activation by activating the extracellular signal-regulated protein kinase pathway. The expression of 5-LO was increased in activated HSC and fibrotic livers of mice. Ablation of 5-LO in primary HSC inhibited both mRNA and protein expression of fibrotic genes. In vivo, ablation of 5-LO markedly ameliorated the CCl₄- and MCD diet-induced liver fibrosis and liver injury. Pharmacological inhibition of 5-LO in HSC by targeted delivery of the 5-LO inhibitor zileuton suppressed HSC activation and improved CCl₄- and MCD diet-induced hepatic fibrosis and liver injury. Finally, we found increased 5-LO expression in patients with non-alcoholic steatohepatitis and liver fibrosis.

Conclusion: 5-LO may play a critical role in activating HSC; genetic ablation or pharmacological inhibition of 5-LO improved CCl₄-and MCD diet-induced liver fibrosis.

Artemisinin and artemisinin derivatives as anti-fibrotic therapeutics

Fibrosis is a pathological reparative process that can occur in most organs and is responsible for nearly half of deaths in the developed world. Despite considerable research, few therapies have proven effective and been approved clinically for treatment of fibrosis. Artemisinin compounds are best known as antimalarial therapeutics, but they also demonstrate antiparasitic, antibacterial, anticancer, and anti-fibrotic effects. Here we summarize literature describing anti-fibrotic effects of artemisinin compounds in in vivo and in vitro models of tissue fibrosis, and we describe the likely mechanisms by which artemisinin compounds appear to inhibit cellular and tissue processes that lead to fibrosis. To consider alternative routes of administration of artemisinin for treatment of internal organ fibrosis, we also discuss the potential for more direct oral delivery of Artemisia plant material to enhance bioavailability and efficacy of artemisinin compared to administration of purified artemisinin drugs at comparable doses. It is our hope that greater understanding of the broad anti-fibrotic effects of artemisinin drugs will enable and promote their use as therapeutics for treatment of fibrotic diseases.

A comprehensive review of natural products to fight liver fibrosis: Alkaloids, terpenoids, glycosides, coumarins and other compounds

The discovery of drugs to treat liver fibrosis has long been a challenge over the past decades due to its complicated pathogenesis. As a primary approach for drug development, natural products account for 30% of clinical drugs used for disease treatment. Therefore, natural products are increasingly important for their medicinal value in liver fibrosis therapy. In this part of the review, special focus is placed on the effect and mechanism of natural compounds, including alkaloids, terpenoids, glycosides, coumarins and others. A total of 36 kinds of natural compounds demonstrate significant antifibrotic effects in various liver fibrosis models in vivo and in hepatic stellate cells (HSCs) in vitro. Revealing the mechanism will provide further basis for clinical conversion, as well as accelerate drug discovery. The mechanism was further summarized with the finding of network regulation by several natural products, such as oxymatrine, paeoniflorin, ginsenoside Rg1 and taurine. Moreover, there are still improvements needed in investigating clinical efficacy, determining mechanisms, and combining applications, as well as semisynthesis and modification. Therefore, natural products area promising resource for agents that protect against liver fibrosis.

Sesquiterpenes and their derivatives-natural anticancer compounds: An update

Sesquiterpenes belong to the largest group of plant secondary metabolites, which consist of three isoprene building units. These compounds are widely distributed in various angiosperms, a few gymnosperms and bryophytes. Sesquiterpenes and their allied derivatives are bio-synthesized in various plant parts including leaves, fruits and roots. These plant-based metabolites are predominantly identified in the Asteraceae family, wherein up to 5000 complexes have been documented to date. Sesquiterpenes and their derivatives are characteristically associated with plant defence mechanisms owing to their antifungal, antibacterial and antiviral activities. Over the last two decades, these compounds have been reportedly demonstrated health promoting perspectives against a wide range of metabolic syndromes i.e. hyperglycemia, hyperlipidemia, cardiovascular complications, neural disorders, diabetes, and cancer. The high potential of sesquiterpenes and their derivatives against various cancers like breast, colon, bladder, pancreatic, prostate, cervical, brain, liver, blood, ovarium, bone, endometrial, oral, lung, eye, stomach and kidney are the object of this review. Predominantly, it recapitulates the literature elucidating sesquiterpenes and their derivatives while highlighting the mechanistic approaches associated with their potent anticancer activities such as modulating nuclear factor kappa (NF-kB) activity, inhibitory action against lipid peroxidation and retarding the production of reactive oxygen & nitrogen species (ROS&RNS).

Dihydroartemisinin ameliorates psoriatic skin inflammation and its relapse by diminishing CD8+ T-cell memory in wild-type and humanized mice

Conventional immunosuppressants cause side effects and do not prevent the recurrence of autoimmune diseases. Moreover, they may not inhibit autoimmunity mediated by pathogenic memory T-cells. Dihydroartemisinin (DHA) has been shown to regulate autoimmunity. However, it remains unknown whether DHA impacts psoriasis and its recurrence. The objective of this study was to determine therapeutic effects of DHA on psoriasis and its relapse as well as its underlying mechanisms.

Methods: We established animal models of imiquimod (IMQ)-induced psoriasis-like wild-type mice and humanized NSG mice receiving lesional human skin from patients with psoriasis. Many immunoassays, including immunohistochemistry, flow cytometry, quantitative RT-PCR and Western blotting, were performed.

Results: We found that DHA not only ameliorated acute skin lesion of psoriatic mice, but also alleviated its recurrence by diminishing CD8⁺ central memory T (T_CM) and CD8⁺ resident memory T (T_RM) cells. It attenuated epidermal pathology and T-cell infiltration in the skin of IMQ-induced psoriatic mice while suppressing expression of IL-15, IL-17 and other proinflammatory cytokines in the skin. Surprisingly, DHA reduced the frequency and number of CD8⁺, but not CD4⁺, subset of CD44^highCD62L^high T_CM in psoriatic mice, whereas methotrexate (MTX) lowered CD4⁺, but not CD8⁺, T_CM frequency and number. Indeed, DHA, but not MTX, downregulated eomesodermin (EOMES) and BCL-6 expression in CD8⁺ T-cells. Furthermore, DHA, but not MTX, reduced the presence of CD8⁺CLA⁺, CD8⁺CD69⁺ or CD8⁺CD103⁺ T_RM cells in mouse skin. Interestingly, treatment with DHA, but not MTX, during the first onset of psoriasis largely prevented psoriasis relapse induced by low doses of IMQ two weeks later. Administration of recombinant IL-15 or CD8⁺, but not CD4⁺, T_CM cells resulted in complete recurrence of psoriasis in mice previously treated with DHA. Finally, we demonstrated that DHA alleviated psoriatic human skin lesions in humanized NSG mice grafted with lesional skin from psoriatic patients while reducing human CD8⁺ T_CM and CD103⁺ T_RM cells in humanized mice.

Conclusion: We have provided the first evidence that DHA is advantageous over MTX in preventing psoriasis relapse by reducing memory CD8⁺ T-cells.

PDGFA gene rs9690350 polymorphism increases biliary atresia risk in Chinese children

Biliary atresia (BA) is a genetic and severe fibro-inflammatory obliterative cholangiopathy of neonates. Platelet-derived growth factor subunit A (PDGFA), as one of participants in liver fibrosis, the overexpression of PDGFA through DNA hypomethylation may lead to the development of BA, but the pathogenesis is still unclear. We conducted a large case-control cohort to investigate the association of genetic variants in PDGFA with BA susceptibility in the Southern Chinese population (506 cases and 1473 controls). We observed that the G allele of rs9690350(G>C) in PDGFA was significantly associated with an increased risk of BA (OR = 1.24, 95% CI = 1.04-1.49, P=0.02). Additionally, the rs9690350 G allele increased the risk of non-cystic biliary atresia (OR = 1.26, 95% CI = 1.04-1.52, P=0.02) and was a genetic biomarker of severe manifestations after surgery. These findings indicate that the rs9690350 G allele is a PDGFA polymorphism associated with the risk of BA that may confer increased disease susceptibility.

LncRNA-H19 induces hepatic stellate cell activation via upregulating alcohol dehydrogenase III-mediated retinoic acid signals

Activation of hepatic stellate cells (HSCs) is a pivotal event in liver fibrosis, characterized by enhanced retinoic acid signals. Although up-regulated retinoic acid signal responds further to maintain HSC activation, the underlying molecular mechanisms are largely unknown. In this study, we sought to investigate the role of lncRNA-H19 in regulation of retinoic acid signals, and to further examine the underlying mechanism in this molecular context. We found that lncRNA-H19 upregulation could enhance retinoic acid signals to induce HSC activation, whereas lncRNA-H19 knockdown completely disturbed retinoic acid signals. Moreover, the activation of retinoic acid signals impaired the lncRNA-H19 knockdown mediated HSC inactivation. Interestingly, we also found that enhanced retinoic acid signals by lncRNA-H19 was associated with a coordinate increase in retinol metabolism during HSC activation. Increased retinol metabolism contributed to obvious lipid droplet consumption. Importantly, we identified that alcohol dehydrogenase III (ADH3) was essential for lncRNA-H19 to enhance retinoic acid signals. The inhibition of ADH3 completely abrogated the lncRNA-H19 mediated retinoic acid signals and HSC activation. Of note, we identified dihydroartemisinin (DHA) as a natural inhibitor for lncRNA-H19. Treatment with DHA significantly decreased the expression of lncRNA-H19, reduced the expression of ADH3, blocked retinoic acid signals, and in turn, inhibited HSC activation. Overall, these results provided novel implications to reveal the molecular mechanism of increased retinoic acid signals during HSC activation, and identify lncRNA-H19/ADH3 pathway as a potential target for the treatment of liver fibrosis.

Dihydroartemisinin Protects against Dextran Sulfate Sodium-Induced Colitis in Mice through Inhibiting the PI3K/AKT and NF-κB Signaling Pathways

Ulcerative colitis is a common inflammatory bowel disease, and the activation of thePI3K/AKT and NF-κB signaling pathways plays a pivotal role in its pathogenesis. Dihydroartemisinin (DHA) is a widely used antimalarial drug and has shown anticancer effect partially through inhibiting the activation of PI3K/AKT and NF-κB. This study aimed to investigate the effect of dihydroartemisinin on ulcerative colitis and its mechanism. Adult male C57 mice were subjected to 3.0% dextran sulfate sodium (DSS) for seven days; simultaneously, dihydroartemisinin or control saline was administered by oral gavage once a day. In vitro, the intestinal epithelial cell-6 was treated with LPS for 24 hours with or without dihydroartemisinin combined with PI3K/Akt activator 740 Y-P or NF-κB activator phorbol myristate acetate. Western blotting was used to test the activation of PI3K/AKT and NF-κB. Dihydroartemisinin significantly ameliorated body weight loss, shortened colon length, and increased DAI in DSS-induced colitis. Meanwhile, histological damage was improved and was accompanied by decreased expression and secretion of proinflammatory cytokines. Moreover, DSS-induced elevation of phosphorylation of PI3K, AKT, IKKα, IκBα, and NF-κB (p65) was remarkably blunted by dihydroartemisinin both in vivo and in vitro, indicating an inhibitive property on the PI3K/AKT and NF-κB signaling pathways. Furthermore, administration of 740 Y-P or PMA significantly blocked protective activity of dihydroartemisinin against colitis in vitro. In conclusion, dihydroartemisinin can attenuate DSS-induced colitis, and its anticolitis effect might be mediated via the PI3K/AKT and NF-κB signaling pathways. DHA might serve as a promising drug for patients with ulcerative colitis.

TMEM100 mediates inflammatory cytokines secretion in hepatic stellate cells and its mechanism research

Recent studies have shown that Transmembrane protein 100 (TMEM100) is a gene at locus 17q32 encoding a 134-amino acid protein with two hypothetical transmembrane domainsa, and first identified as a transcript from the mouse genome. As a downstream target gene of bone morphogenetic protein (BMP)-activin receptor-like kinase 1 (ALK1) signaling, it was activated to participate in inducing arterial endothelium differentiation, maintaining vascular integrity, promoting cell apoptosis, inhibiting metastasis and proliferation of cancer cells. However, evidence for the function of TMEM100 in inflammation is still limited. In this study, we explore the role of TMEM100 in inflammatory cytokine secretion and the role of MAPK signaling pathways in tumor necrosis factor-alpha (TNF-α)-induced TMEM100 expression in LX-2 cells. We found that the expression of TMEM100 was decreased markedly in human liver fibrosis tissues, and its expression was also inhibited in LX-2 cells induced by TNF-α, suggesting that it might be associated with the development of inflammation. Therefore, we demonstrated that overexpression of TMEM100 by transfecting pEGFP-C2-TMEM100 could lead to the down-regulation of IL-1β and IL-6 secretion. Moreover, we found that expression changes of TMEM100 could be involved in inhibition or activation of MAPK signaling pathways accompanied with regulating phosphorylation levels of ERK and JNK protein in response to TNF-α. These results suggested that TMEM100 might play an important role in the secretion of inflammatory cytokines (IL-1β and IL-6) of LX-2 cells induced by TNF-α, and MAPK (ERK and JNK) signaling pathways might participate in its induction of expression.

Antimalarial Dihydroartemisinin triggers autophagy within HeLa cells of human cervical cancer through Bcl-2 phosphorylation at Ser70

BACKGROUND

As an effective antimalarial medicine, Dihydroartemisinin (DHA) has therapeutic potential on human cervical cancer. However, its working mechanism has not been elucidated.

PURPOSE

This study aimed to investigate the reversal effect of DHA on human cervical cancer HeLa cells, and explored its mechanism of action in vitro and in vivo.

STUDY DESIGN/METHODS

The effect and mechanism of DHA on HeLa cells was examined by using CCK-8 assay, flow cytometry, transmission electron microscopy, immunofluorescence, and Western blot analysis in human hepatocellular carcinoma cells.

RESULTS

In this study, it was confirmed that DHA had statistically equivalent anti-tumor efficiency in HeLa cells with a clinical chemotherapeutic agent of cisplatin. Meanwhile, DHA triggered autophagy, where LC3B-II expression was dose-dependently increased. Further, it was revealed that DHA promotes reactive oxygen species (ROS) generation, with DNA double-strand breaks (DSB) damage, as up-regulation of γH2AX protein and foci formation. Interestingly, we firstly demonstrated that DHA induced autophagy through promotion of the phosphorylation of Bcl-2 (Ser70), independent of the phosphorylated JNK1/2 (Thr183/Tyr185). Moreover, DHA-treated HeLa cells displayed an increase in the pro-autophagic protein Beclin-1 with downregulated the phospho-mTOR (Ser2448). Furthermore, upregulated pro-apoptotic protein Bak-1, but not Bax, suggesting Bak-1 is included in DHA-induced autophagy.

CONCLUSION

Therefore, DHA upregulates the phosphorylation of Bcl-2 (Ser70) and mTOR (Ser2448) and induces autophagic cell death in Hela cells. This study provided a mechanism to support DHA, an autophagy inducer, as a potential therapeutic agent for human cervical cancer.

Preventive effect of artemisinin extract against cholestasis induced via lithocholic acid exposure

Obstructive cholestasis characterized by biliary pressure increase leading to leakage of bile back that causes liver injury. The present study aims to evaluate the effects of artemisinin in obstructive cholestasis in mice. The present study was carried out on 40 adult healthy mice that were divided into 4 groups, 10 mice each; the negative control group didn’t receive any medication. The normal group was fed normally with 100 mg/kg of artemisinin extract orally. The cholestatic group fed on 1% lithocholic acid (LCA) mixed into control diet and cholestatic group co-treated with 100 mg/kg of artemisinin extract orally. Mice were treated for 1 month then killed at end of the experiment. A significant increase in alanine aminotransferase, aspartate aminotransferase, and total and direct bilirubin was detected in mice exposed to LCA toxicity. That increase was significantly reduced to normal values in mice co-treated with artemisinin. LCA toxicity causes multiple areas of necrosis of irregular distribution. However, artemisinin co-treatment showed normal hepatic architecture. Moreover, LCA causes down-regulation of hepatic mRNA expressions of a set of genes that are responsible for ATP binding cassette and anions permeability as ATP-binding cassette sub-family G member 8, organic anion-transporting polypeptide, and multidrug resistance-associated protein 2 genes that were ameliorated by artemisinin administration. Similarly, LCA toxicity significantly down-regulated hepatic mRNA expression of constitutive androstane receptor, OATP4, and farnesoid x receptor genes. However, artemisinin treatment showed a reasonable prevention. In conclusion, the current study strikingly revealed that artemisinin treatment can prevent severe hepatotoxicity and cholestasis that led via LCA exposure.

Dihydroartemisinin induces apoptosis and autophagy-dependent cell death in cholangiocarcinoma through a DAPK1-BECLIN1 pathway

Cholangiocarcinoma (CCA) is a very aggressive cancer arising from the malignant transformation of cholangiocytes. Intrahepatic CCA is associated with reactive inflammation and intense fibrosis of the hepatobiliary tract. Dihydroartemisinin (DHA), the active compound found in Artemisia annua, has been shown to possess anti-tumor activity in a variety of human cancers, including hepatoma. Here, we tested the ability of DHA to specifically kill CCA cells and have investigated the underlying mechanisms. DHA induced both apoptosis and autophagy-dependent caspase-independent cell death in many CCA cell lines, while being slightly toxic to immortalized cholangiocytes. DHA induced the expression of many apoptosis- and autophagy-related genes in CCA cells. In particular, it greatly induced the expression of DAPK1, and reduced the interaction of BECLIN1 with BCL-2 while promoting its interaction with PI3KC3. Genetic silencing of DAPK1 prevented DHA-induced autophagy. Pharmacologic and genetic inhibition of BECLIN1 function prevented autophagy and cell death induced by DHA in CCA cells. These data unravel a novel pathway of DHA cancer toxicity and open the possibility to introduce DHA in the therapeutic regimen for the treatment of CCA.

Activation of ferritinophagy is required for the RNA-binding protein ELAVL1/HuR to regulate ferroptosis in hepatic stellate cells

Ferroptosis is a recently recognized form of regulated cell death that is characterized by lipid peroxidation. However, the molecular mechanisms regulating ferroptosis are largely unknown. In this study, we report that the RNA-binding protein ELAVL1/HuR plays a crucial role in regulating ferroptosis in liver fibrosis. Upon exposure to ferroptosis-inducing compounds, ELAVL1 protein expression was remarkably increased through the inhibition of the ubiquitin-proteasome pathway. ELAVL1 siRNA led to ferroptosis resistance, whereas ELAVL1 plasmid contributed to classical ferroptotic events. Interestingly, upregulated ELAVL1 expression also appeared to increase autophagosome generation and macroautophagic/autophagic flux, which was the underlying mechanism for ELAVL1-enhanced ferroptosis. Autophagy depletion completely impaired ELAVL1-mediated ferroptotic events, whereas autophagy induction showed a synergistic effect with ELAVL1. Importantly, ELAVL1 promoted autophagy activation via binding to the AU-rich elements within the F3 of the 3'-untranslated region of BECN1/Beclin1 mRNA. The internal deletion of the F3 region abrogated the ELAVL1-mediated BECN1 mRNA stability, and, in turn, prevented ELAVL1-enhanced ferroptosis. In mice, treatment with sorafenib alleviated murine liver fibrosis by inducing hepatic stellate cell (HSC) ferroptosis. HSC-specific knockdown of ELAVL1 impaired sorafenib-induced HSC ferroptosis in murine liver fibrosis. Noteworthy, we retrospectively analyzed the effect of sorafenib on HSC ferroptosis in advanced fibrotic patients with hepatocellular carcinoma receiving sorafenib monotherapy. Attractively, ELAVL1 upregulation, ferritinophagy activation, and ferroptosis induction occurred in primary human HSCs from the collected human liver tissue. Overall, these results reveal novel molecular mechanisms and signaling pathways of ferroptosis, and also identify ELAVL1-autophagy-dependent ferroptosis as a potential target for the treatment of liver fibrosis. Abbreviations: ACTA2/alpha-SMA: actin, alpha 2, smooth muscle, aorta; ACTB/beta-actin: actin beta; ARE: AU-rich element; ATG: autophagy related; BDL: bile duct ligation; BECN1: beclin 1; BSO: buthionine sulfoximine; COL1A1: collagen type I alpha 1 chain; ELAVL1/HuR: ELAV like RNA binding protein 1; FDA: fluorescein diacetate; FTH1: ferritin heavy chain 1; GOT1/AST: glutamic-oxaloacetic transaminase 1; GPT/ALT: glutamic-pyruvic transaminase; GPX4: glutathione peroxidase 4; GSH: glutathione; HCC: hepatocellular carcinoma; HSC: hepatic stellate cell; LCM: laser capture microdissection; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MDA: malondialdehydep; NCOA4: nuclear receptor coactivator 4; PTGS2: prostaglandin-endoperoxide synthase 2; ROS: reactive oxygen species; SQSTM1/p62: sequestosome 1; TBIL: total bilirubin; TEM: transmission electron microscopy; TGFB1: trasforming growth factor beta 1; UTR: untranslated region; VA-Lip-ELAVL1-siRNA: vitamin A-coupled liposomes carrying ELAVL1-siRNA.

Dihydroartemisinin alleviates oxidative stress in bleomycin-induced pulmonary fibrosis

AIMS

Dihydroartemisinin has been shown to inhibit the development of pulmonary fibrosis in rats, but its mechanism has yet to be elucidated. This study aimed to determine the mechanisms of dihydroartemisinin in bleomycin-induced pulmonary fibrosis in a rat model.

MAIN METHODS

Morphological changes and collagen deposition were analyzed via hematoxylin-eosin staining and Masson staining and the expression of biotic-factor-related oxidative stress in lung tissues was assayed with standard assay kits. The expressions of α-SMA, E-cadherin, and Nrf2/HO-1 were detected by Western blot and RT-PCR, and the cell morphology and proliferation of cultured type II alveolar epithelial cells (AECs) were assessed via microscopy and immunocytochemical assay.

KEY FINDINGS

Dihydroartemisinin treatment significantly decreased the level of oxidative stress and collagen synthesis and inhibited AECs differentiation in bleomycin-induced pulmonary fibrosis compared to the control group (P < 0.001).

SIGNIFICANCE

Our results indicated that dihydroartemisinin might decrease oxidative damage to attenuate lung injury and fibrosis.

Dihydroartemisinin induces autophagy-dependent death in human tongue squamous cell carcinoma cells through DNA double-strand break-mediated oxidative stress

Dihydroartemisinin is an effective antimalarial agent with multiple biological activities. In the present investigation, we elucidated its therapeutic potential and working mechanism on human tongue squamous cell carcinoma (TSCC). It was demonstrated that dihydroartemisinin could significantly inhibit cell growth in a dose- and time-dependent manner by the Cell Counting Kit-8 and colony formation assay in vitro. Meanwhile, autophagy was promoted in the Cal-27 cells treated by dihydroartemisinin, evidenced by increased LC3B-II level, increased autophagosome formation, and increased Beclin-1 level compared to dihydroartemisinin-untreated cells. Importantly, dihydroartemisinin caused DNA double-strand break with simultaneously increased γH2AX foci and oxidative stress; this inhibited the nuclear localization of phosphorylated signal transducer and activator of transcription 3 (p-STAT3), finally leading to autophagic cell death. Furthermore, the antitumor effect of dihydroartemisinin-monotherapy was confirmed with a mouse xenograft model, and no kidney injury associated with toxic effect was observed after intraperitoneal injection with dihydroartemisinin for 3 weeks in vivo. In the present study, it was revealed that dihydroartemisinin-induced DNA double-strand break promoted oxidative stress, which decreased p-STAT3 (Tyr705) nuclear localization, and successively increased autophagic cell death in the Cal-27 cells. Thus, dihydroartemisinin alone may represent an effective and safe therapeutic agent for human TSCC.

Crocin prevents platelet‑derived growth factor BB‑induced vascular smooth muscle cells proliferation and phenotypic switch

The phenotypic switch of vascular smooth muscle cells (VSMCs) is a major initiating factor for atherosclerotic cardiovascular diseases. Platelet-derived growth factor-BB (PDGF-BB) initiates a number of biological processes that contribute to VSMC proliferation and phenotypic switch. Crocin, a component of saffron, has been reported to inhibit atheromatous plaque formation. However, the effects of crocin on PDGF-BB-induced VSMC proliferation and phenotypic switch remain unclear. The aim of the present study was to investigate the role of crocin on PDGF-BB-induced VSMCs proliferation and phenotypic switch and its underlying mechanisms. Cell proliferation and markers of VSMCs phenotypic switch were measured using a Cell Counting Kit-8 assay and western blot analysis, respectively. The signaling pathways involved in the effects of crocin on VSMCs were validated by western blot analysis with or without the use of specific pathway inhibitors. Crocin significantly inhibited PDGF-BB-induced VSMCs proliferation compared with the PDGF-BB only group (P<0.05). In addition, crocin significantly abrogated the PDGF-BB-induced increase in contractile protein α-smooth muscle actin, calponin and decrease in synthetic proteins osteopontin (OPN) in a concentration dependent manner (P<0.05). In addition, crocin slowed PDGF-BB-induced Janus kinase (JAK)-signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK)/Kruppel-like factor 4 (KLF4) signaling activation in VSMCs. By applying the JAK inhibitor (AG490) and ERK1/2 inhibitor (U0126), the results suggested that the crocin inhibited PDGF-BB-induced VSMCs phenotypic switch through the JAK/STAT3 and ERK/KLF4 signaling pathways. These results suggested that crocin may effectively prevent PDGF-BB-induced VSMCs proliferation and phenotypic switch and may be a promising candidate for the therapy of atherosclerotic cardiovascular diseases.

pPB Peptide-Mediated siRNA-Loaded Stable Nucleic Acid Lipid Nanoparticles on Targeting Therapy of Hepatic Fibrosis

Hepatic fibrosis is a necessary process in the development of liver diseases such as hepatic cirrhosis and its complications, which has become a serious threat to human health. Currently, antifibrotic drug treatment is ineffective, and one reason should be the lack of liver targeting ability. In this report, polypeptide pPB-modified stable nucleic acid lipid nanoparticles (pPB-SNALPs) were prepared to selectively deliver siRNAs against heat shock protein 47 to the liver for targeted therapy of hepatic fibrosis. First, siRNA sequences with high silencing efficiency were screened based on siRNA transfection efficacy. Then, pPB-SNALPs were prepared, which showed a narrow size distribution with a diameter in the range of 110-130 nm and a neutral z-potential of 0 mV. As evidenced by the in vitro and in vivo targeting study, compared with unmodified SNALP, pPB-SNALP showed increased uptake by LX-2 cells and primary hepatic stellate cells (HSC) of mice in vitro and showed increased liver distribution and HSC uptake in vivo. In addition, pPB-SNALP also exhibited an enhanced inhibitory effect on TAA-induced hepatic fibrosis mice with high gp46 mRNA expression in vivo. In summary, our results demonstrated that pPB-SNALP is an effective liver-targeted delivery system. This study could lay a good foundation for the targeted gene therapy of hepatic fibrosis.

Dihydroartemisinin increases apoptosis of colon cancer cells through targeting Janus kinase 2/signal transducer and activator of transcription 3 signaling

As a derivative of artemisinin, dihydroartemisinin is effective in the treatment of malaria. Dihydroartemisinin has been identified to possess inhibitory effects in numerous types of animal model with tumors, indicating that it has an antineoplastic effect. The aim of the present study was to analyze the potential anticancer effects of dihydroartemisinin, particularly its effect on apoptosis of colon cancer cells. In the present study, it was identified that dihydroartemisinin inhibited cell viability, promoted cell apoptosis, increased B-cell lymphoma-2-associated X-protein expression, increased caspase-3/9 activities, decreased poly(ADP-ribose) polymerase levels, decreased phosphorylation of extracellular-signal-regulated kinase, and increased phosphorylation of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase in colon cancer cells. Conversely, the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) was suppressed by dihydroartemisinin in colon cancer cells. These results demonstrate that the potential anticancer effects of dihydroartemisinin may increase apoptosis of colon cancer cells through targeting JAK2/STAT3 signaling.

PDGF in organ fibrosis

Fibrosis is part of a tissue repair response to injury, defined as increased deposition of extracellular matrix. In some instances, fibrosis is beneficial; however, in the majority of diseases fibrosis is detrimental. Virtually all chronic progressive diseases are associated with fibrosis, representing a huge number of patients worldwide. Fibrosis occurs in all organs and tissues, becomes irreversible with time and further drives loss of tissue function. Various cells types initiate and perpetuate pathological fibrosis by paracrine activation of the principal cellular executors of fibrosis, i.e. stromal mesenchymal cells like fibroblasts, pericytes and myofibroblasts. Multiple pathways are involved in fibrosis, platelet-derived growth factor (PDGF)-signaling being one of the central mediators. Stromal mesenchymal cells express both PDGF receptors (PDGFR) α and β, activation of which drives proliferation, migration and production of extracellular matrix, i.e. the principal processes of fibrosis. Here, we review the role of PDGF signaling in organ fibrosis, with particular focus on the more recently described ligands PDGF-C and -D. We discuss the potential challenges, opportunities and open questions in using PDGF as a potential target for anti-fibrotic therapies.

Interaction between autophagy and senescence is required for dihydroartemisinin to alleviate liver fibrosis

Autophagy and cellular senescence are stress responses essential for homeostasis. Therefore, they may represent new pharmacologic targets for drug development to treat diseases. In this study, we sought to evaluate the effect of dihydroartemisinin (DHA) on senescence of activated hepatic stellate cells (HSCs), and to further elucidate the underlying mechanisms. We found that DHA treatment induced the accumulation of senescent activated HSCs in rat fibrotic liver, and promoted the expression of senescence markers p53, p16, p21 and Hmga1 in cell model. Importantly, our study identified the transcription factor GATA6 as an upstream molecule in the facilitation of DHA-induced HSC senescence. GATA6 accumulation promoted DHA-induced p53 and p16 upregulation, and contributed to HSC senescence. By contrast, siRNA-mediated knockdown of GATA6 dramatically abolished DHA-induced upregulation of p53 and p16, and in turn inhibited HSC senescence. Interestingly, DHA also appeared to increase autophagosome generation and autophagic flux in activated HSCs, which was underlying mechanism for DHA-induced GATA6 accumulation. Autophagy depletion impaired GATA6 accumulation, while autophagy induction showed a synergistic effect with DHA. Attractively, p62 was found to act as a negative regulator of GATA6 accumulation. Treatment of cultured HSCs with various autophagy inhibitors, led to an inhibition of DHA-induced p62 degradation, and in turn, prevented DHA-induced GATA6 accumulation and HSC senescence. Overall, these results provide novel implications to reveal the molecular mechanism of DHA-induced senescence, by which points to the possibility of using DHA based proautophagic drugs for the treatment of liver fibrosis.

Dihydroartemisinin protects against alcoholic liver injury through alleviating hepatocyte steatosis in a farnesoid X receptor-dependent manner

Alcoholic liver disease (ALD) is a common etiology of liver diseases, characterized by hepatic steatosis. We previously identified farnesoid X receptor (FXR) as a potential therapeutic target for ALD. Dihydroartemisinin (DHA) has been recently identified to possess potent pharmacological activities on liver diseases. This study was aimed to explore the impact of DHA on ALD and further elaborate the underlying mechanisms. Gain- or loss-of-function analyses of FXR were applied in both in vivo and in vitro studies. Results demonstrated that DHA rescued FXR expression and activity in alcoholic rat livers. DHA also reduced serodiagnostic markers of liver injury, including aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and lactate dehydrogenase. DHA improved alcohol-induced liver histological lesions, expression of inflammation genes, and inflammatory cell infiltration. In addition, DHA not only attenuated hyperlipidemia but also reduced hepatic steatosis through regulating lipogenesis and lipolysis genes. In vitro experiments further consolidated the concept that DHA ameliorated ethanol-caused hepatocyte injury and steatosis. Noteworthily, DHA effects were reinforced by FXR agonist obeticholic acid or FXR expression plasmids but abrogated by FXR antagonist Z-guggulsterone or FXR siRNA. In summary, DHA significantly improved alcoholic liver injury by inhibiting hepatic steatosis, which was dependent on its activation of FXR in hepatocytes.

ROS-JNK1/2-dependent activation of autophagy is required for the induction of anti-inflammatory effect of dihydroartemisinin in liver fibrosis

Accumulating evidence identifies autophagy as an inflammation-related defensive mechanism against diseases including liver fibrosis. Therefore, autophagy may represent a new pharmacologic target for drug development to treat liver fibrosis. In this study, we sought to investigate the effect of dihydroartemisinin (DHA) on autophagy, and to further examine the molecular mechanisms of DHA-induced anti-inflammatory effects. We found that DHA appeared to play an essential role in controlling excessive inflammation. DHA suppressed inflammation in rat liver fibrosis model and inhibited the expression of proinflammatory cytokines in activated hepatic stellate cells (HSCs). Interestingly, DHA increased the autophagosome generation and autophagic flux in activated HSCs, which is underlying mechanism for the anti-inflammatory activity of DHA. Autophagy depletion impaired the induction of anti-inflammatory effect of DHA, while autophagy induction showed a synergistic effect with DHA. Importantly, our study also identified a crucial role for reactive oxygen species (ROS) in the facilitation of DHA-induced autophagy. Antioxidants, such as glutathione and N-acetyl cysteine, significantly abrogated ROS production, and in turn, prevented DHA-induced autophagosome generation and autophagic flux. Besides, we found that c-Jun N-terminal kinase1/2 (JNK1/2) was a downstream signaling molecule of ROS that mediated the induction of autophagy by DHA. Down-regulation of JNK1/2 activity, using selective JNK1/2 inhibitor (SP600125) or siJNK1/2, led to an inhibition of DHA-induced autophagy. Overall, these results provide novel implications to reveal the molecular mechanism of DHA-induced anti-inflammatory effects, by which points to the possibility of using DHA based proautophagic drugs for the treatment of inflammatory diseases.

Dihydroartemisinin counteracts fibrotic portal hypertension via farnesoid X receptor-dependent inhibition of hepatic stellate cell contraction

Portal hypertension is a frequent pathological symptom occurring especially in hepatic fibrosis and cirrhosis. Current paradigms indicate that inhibition of hepatic stellate cell (HSC) activation and contraction is anticipated to be an attractive therapeutic strategy, because activated HSC dominantly facilitates an increase in intrahepatic vein pressure through secreting extracellular matrix and contracting. Our previous in vitro study indicated that dihydroartemisinin (DHA) inhibited contractility of cultured HSC by activating intracellular farnesoid X receptor (FXR). However, the effect of DHA on fibrosis-related portal hypertension still requires clarification. In this study, gain- and loss-of-function models of FXR in HSC were established to investigate the mechanisms underlying DHA protection against chronic CCl₄ -caused hepatic fibrosis and portal hypertension. Immunofluorescence staining visually showed a decrease in FXR expression in CCl₄ -administrated rat HSC but an increase in that in DHA-treated rat HSC. Serum diagnostics and morphological analyses consistently indicated that DHA exhibited hepatoprotective effects on CCl₄ -induced liver injury. DHA also reduced CCl₄ -caused inflammatory mediator expression and inflammatory cell infiltration. These improvements were further enhanced by INT-747 but weakened by Z-guggulsterone. Noteworthily, DHA, analogous to INT-747, significantly lowered portal vein pressure and suppressed fibrogenesis. Experiments on mice using FXR shRNA lentivirus consolidated the results above. Mechanistically, inhibition of HSC activation and contraction was found as a cellular basis for DHA to relieve portal hypertension. These findings demonstrated that DHA attenuated portal hypertension in fibrotic rodents possibly by targeting HSC contraction via a FXR activation-dependent mechanism. FXR could be a target molecule for reducing portal hypertension during hepatic fibrosis.

Protective effect of liver fibrosis against acute liver injury

Liver fibrosis is the excessive accumulation of extracellular matrix proteins in liver tissue. Liver fibrosis as the characteristic change of chronic liver injury has the potential to develop into liver cirrhosis, liver failure and hepatic carcinoma, and is considered a devastating pathologic process. However, recent studies demonstrate that liver fibrosis is not only reversible, but also can protect the liver from acute injury. Currently, the mechanisms of hepatoprotective effect of liver fibrosis have become a hot research area, which include promoted regeneration of the remaining normal liver cells and apoptotic resistance. In the present article, we will review the hepatoprotective effect of liver fibrosis and the underlying molecular mechanisms, aiming to provide a theoretical basis for understanding the pathogenesis of acute-on-chronic liver failure and provide new therapeutic targets for this disease.