Toll-Like Receptor 4-Independent Carbon Tetrachloride-Induced Fibrosis and Lipopolysaccharide-Induced Acute Liver Injury in Mice: Role of Hepatic Stellate Cells

The role of 2'-5'-oligoadenylate synthase-like protein (OASL1) in biliary and hepatotoxin-induced liver injury in mice

Following an injury, the liver embarks on a process that drives the accumulation and reformation of the extracellular matrix, leading to hepatic fibrosis. Type I interferons (IFNs), including IFN-α and IFN-β, play a crucial role in averting chronic liver injury through the activation of IFN-stimulated genes (ISGs), which are instrumental in sculpting adaptive immunity. The role of 2'-5'-oligoadenylate synthase-like protein 1 (OASL1), an antiviral ISG, in the context of liver fibrosis remains to be elucidated. To elicit liver fibrosis, a diet containing 0.1% diethoxycarbonyl-1,4-dihydrocollidine (DDC) and carbon tetrachloride (CCl4) were employed to induce cholestatic- and hepatotoxin-mediated liver fibrosis, respectively. Histological analyses of both models revealed that OASL1-/- mice exhibited reduced liver damage and, consequently, expressed lower levels of fibrotic mediators, notably α-smooth muscle actin. OASL1-/- mice demonstrated significantly elevated IFN-α and IFN-β mRNA levels, regulated by the IFN regulatory factor 7 (IRF7). Additionally, OASL1-/- ameliorated chronic liver fibrosis through the modulation of nuclear factor-κB (NF-κB) signaling. The effect of OASL1 on type I IFN production in acute liver damage was further explored and OASL1-/- mice consistently showed lower alanine transaminase levels and pro-inflammatory cytokines, but IFN-α and IFN-β mRNA levels were upregulated, leading to amelioration of acute liver injury. Additionally, the study discovered that F4/80-positive cells were observed more frequently in OASL1-/- CCl4 acutely treated mice. This implies that there is a significant synergy in the function of macrophages and OASL1 deficiency. These results demonstrate that in instances of liver injury, OASL1 inhibits the production of type I IFN by modulating the NF-κB signaling pathway, thereby worsening disease.

Theabrownin from Fu Brick tea ameliorates high-fat induced insulin resistance, hepatic steatosis, and inflammation in mice by altering the composition and metabolites of gut microbiota

Fu Brick tea belongs to fermented dark tea, which is one of the six categories of tea. Fu Brick tea has been reported to reduce adiposity and has beneficial effects in the treatment of hypercholesterolemia and cardiovascular disease. Theabrownin (TB) is one of the pigments with the most abundant content in Fu Brick tea. TB has also been reported to have lipid-lowering effects, but its mechanism remains unclear. We found that TB could effectively reduce the insulin resistance and fat deposition induced by a high fat diet (HFD), decrease inflammation in the liver, improve intestinal integrity, and reduce endotoxins in circulation. Further studies showed that TB increased the abundance of Verrucomicrobiota and reduced the abundance of Firmicutes and Desulfobacterota in the intestinal tract of obese mice. The alteration of gut microbiota is closely linked to the metabolic phenotype after TB treatment through correlation analysis. Moreover, TB changed the gut microbial metabolites including L-ornithine, α-ketoglutarate, and glutamine, which have also been found to be upregulated in the liver after TB intervention. In vitro, L-ornithine, α-ketoglutarate, or glutamine significantly reduced lipopolysaccharide (LPS)-induced inflammation in macrophages. Therefore, our results suggest that TB can reduce adiposity, systemic insulin resistance, and liver inflammation induced by a HFD through altering gut microbiota and improving the intestinal tight junction integrity. The metabolites of gut microbiota might also play a role in ameliorating the HFD-induced phenotype by TB.

CD14 is not required for carbon tetrachloride-induced hepatic inflammation and fibrosis with or without lipopolysaccharide challenge

Binding of lipopolysaccharide (LPS) to CD14 is required for its cellular effects via TLR4. A role of LPS/TLR4-mediated signaling in activated hepatic stellate cells (aHSCs), the major fibrogenic cells, in liver fibrosis has been reported. We investigated effects of LPS on carbon tetrachloride (CCl4)-induced fibrosis in CD14-knockout (KO) mice in vivo, and culture-activated HSCs in vitro. CCl4 (biweekly; 4 weeks)-treated wild type (WT) and CD14-KO mice were challenged with single LPS administration for 24 h. Liver injury, inflammation and fibrosis were determined. Culture-activated HSCs from WT or CD14-KO mice were stimulated with LPS. Parameters of fibrogenic activity (expression of collagen1a1 [Col1a1], α-smooth muscle actin [αSMA] and TGFβ1) and inflammatory cytokines/chemokines were measured. CCl4 treatment caused similar liver injury and fibrosis in WT and CD14-KO mice. LPS increased liver injury and inflammation similarly in CCl4-treated WT and CD14-KO mice, but downregulated Timp1 and upregulated Mmp13. LPS elicited similar NFκB activation and inflammatory response in WT and CD14-KO aHSCs. LPS similarly downregulated Acta2 (encodes αSMA), Pdgfrb, Col1a1 and Mmp13 expression but did not affect Timp1 expression in WT and CD14-KO aHSCs. LPS did not alter Tgfb1 but increased expression of decorin (Dcn) (inhibitor of TGFβ1) expression in WT and CD14-KO aHSCs. The results indicate that the effects of LPS on HSCs are CD14-independent, and CD14 is not required for hepatic fibrosis. LPS-induced down-modulation of fibrogenic markers in aHSCs is also CD14-independent.

Stellate cell in hepatic inflammation and acute injury

The perisinusoidal hepatic stellate cells (HSCs) have been investigated extensively for their role as the major fibrogenic cells during chronic liver injury. HSCs also produce numerous cytokines, chemokines, and growth mediators, and express cell adhesion molecules constitutively and in response to stimulants such as endotoxin (lipopolysaccharide). With this property and by interacting with resident and recruited immune and inflammatory cells, HSCs regulate hepatic immune homeostasis, inflammation, and acute injury. Indeed, experiments with HSC-depleted animal models and cocultures have provided evidence for the prominent role of HSCs in the initiation and progression of inflammation and acute liver damage due to various toxic agents. Thus HSCs and/or mediators derived thereof during acute liver damage may be considered as potential therapeutic targets.

Myeloid TLR4 signaling promotes post-injury withdrawal resolution of murine liver fibrosis

The fate of resolution of liver fibrosis after withdrawal of liver injury is still incompletely elucidated. Toll-like receptor 4 (TLR4) in tissue fibroblasts is pro-fibrogenic. After withdrawal of liver injury, we unexpectedly observed a significant delay of fibrosis resolution as TLR4 signaling was pharmacologically inhibited in vivo in two murine models. Single-cell transcriptome analysis of hepatic CD11b⁺ cells, main producers of matrix metalloproteinases (MMPs), revealed a prominent cluster of restorative Tlr4-expressing Ly6c2-low myeloid cells. Delayed resolution after gut sterilization suggested its microbiome-dependent nature. Enrichment of a metabolic pathway linking to a significant increase of bile salt hydrolase-possessing family Erysipelotrichaceae during resolution. Farnesoid X receptor-stimulating secondary bile acids including 7-oxo-lithocholic acids upregulated MMP12 and TLR4 in myeloid cells in vitro. Fecal material transplant in germ-free mice confirmed phenotypical correlations in vivo. These findings highlight a pro-fibrolytic role of myeloid TLR4 signaling after injury withdrawal and may provide targets for anti-fibrotic therapy.

Three new feruloyl glucuronopyranosyl glycerols from Eriocaulon buergerianum with their anti-fibrotic effects on hepatic stellate cells

Three new feruloyl glucuronopyranosyl glycerols, 1-O-α-D-(2'-feruloyl) glucuronopyranosyl glycerol (1), 1-O-α-D-(3'-feruloyl) glucuronopyranosyl glycerol (2), and 1-O-α-D-(4'-feruloyl) glucuronopyranosyl glycerol (3) were isolated and purified from the capitulum of Eriocaulon buergerianum Koern. Their structures were identified by spectroscopic and chemical methods. Molecular docking study showed that 1 is a potential inhibitor of TGF-β1 receptor. Bioassay results revealed that 1 exhibited strong inhibitory activity against the TGF-β-induced expression of α-smooth muscle actin (α-SMA) and fibronectin in human hepatic stellate LX-2 cells. The results in this study indicated that the new feruloyl glucuronopyranosyl glycerol 1 has preventive and therapeutic potentials against hepatic fibrosis.

Is it possible to intervene early cirrhosis by targeting toll-like receptors to rebalance the intestinal microbiome?

Cirrhosis is a progressive chronic liver disease caused by one or more causes and characterized by diffuse fibrosis, pseudolobules, and regenerated nodules. Once progression to hepatic decompensation, the function of the liver and other organs is impaired and almost impossible to reverse and recover, which often results in hospitalization, impaired quality of life, and high mortality. However, in the early stage of cirrhosis, there seems to be a possibility of cirrhosis reversal. The development of cirrhosis is related to the intestinal microbiota and activation of toll-like receptors (TLRs) pathways, which could regulate cell proliferation, apoptosis, expression of the hepatomitogen epiregulin, and liver inflammation. Targeting regulation of intestinal microbiota and TLRs pathways could affect the occurrence and development of cirrhosis and its complications. In this paper, we first reviewed the dynamic change of intestinal microbiota and TLRs during cirrhosis progression. And further discussed the interaction between them and potential therapeutic targets to reverse early staged cirrhosis.

Candida Administration in 5/6 Nephrectomized Mice Enhanced Fibrosis in Internal Organs: An Impact of Lipopolysaccharide and (1→3)-β-D-Glucan from Leaky Gut

Uremic toxins and gut dysbiosis in advanced chronic kidney disease (CKD) can induce gut leakage, causing the translocation of gut microbial molecules into the systemic circulation. Lipopolysaccharide (LPS) and (1→3)-β-D-glucan (BG) are the major gut microbial molecules of Gram-negative bacteria and fungi, respectively, and can induce inflammation in several organs. Here, the fibrosis in the kidney, liver, and heart was investigated in oral C. albicans-administered 5/6 nephrectomized (Candida-5/6 Nx) mice. At 20 weeks post 5/6 Nx, Candida-5/6 Nx mice demonstrated increased 24 h proteinuria, liver enzymes, and serum cytokines (TNF-α, IL-6, and IL-10), but not weight loss, systolic blood pressure, hematocrit, serum creatinine, or gut-derived uremic toxins (TMAO and indoxyl sulfate), compared to in 5/6 Nx alone. The gut leakage in Candida-5/6 Nx was more severe, as indicated by FITC-dextran assay, endotoxemia, and serum BG. The areas of fibrosis from histopathology, along with the upregulated gene expression of Toll-like receptor 4 (TLR-4) and Dectin-1, the receptors for LPS and BG, respectively, were higher in the kidney, liver, and heart. In vitro, LPS combined with BG increased the supernatant IL-6 and TNF-α, upregulated the genes of pro-inflammation and pro-fibrotic processes, Dectin-1, and TLR-4 in renal tubular (HK-2) cells and hepatocytes (HepG2), when compared with LPS or BG alone. This supported the pro-inflammation-induced fibrosis and the possible LPS-BG additive effects on kidney and liver fibrosis. In conclusion, uremia-induced leaky gut causes the translocation of gut LPS and BG into circulation, which activates the pro-inflammatory and pro-fibrotic pathways, causing internal organ fibrosis. Our results support the crosstalk among several organs in CKD through a leaky gut.

Brain-gut-liver axis: Chronic psychological stress promotes liver injury and fibrosis via gut in rats

Background

The effect of chronic psychological stress on hepatitis and liver fibrosis is concerned. However, its mechanism remains unclear. We investigated the effect and mechanism of chronic psychological stress in promoting liver injury and fibrosis through gut.

Methods

Sixty male SD rats were randomly assigned to 6 groups. Rat models of chronic psychological stress (4 weeks) and liver fibrosis (8 weeks) were established. The diversity of gut microbiota in intestinal feces, permeability of intestinal mucosa, pathologies of intestinal and liver tissues, collagen fibers, protein expressions of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), nuclear factor kappa β (NF-κβ), tumor necrosis factor α (TNF-α) and interleukin 1 (IL-1) in liver tissue, liver function and coagulation function in blood and lipopolysaccharide (LPS) in portal vein blood were detected and analyzed.

Results

The diversities and abundances of gut microbiota were significant differences in rats among each group. The pathological lesions of intestinal and liver tissues, decreased expression of occludin protein in intestinal mucosa, deposition of collagen fibers and increased protein expression of TLR4, MyD88, NF-κβ, TNF-α and IL-1 in liver tissue, increased LPS level in portal vein blood, and abnormalities of liver function and coagulation function, were observed in rats exposed to chronic psychological stress or liver fibrosis. There were significant differences with normal rats. When the dual intervention factors of chronic psychological stress and liver fibrosis were superimposed, the above indicators were further aggravated.

Conclusion

Chronic psychological stress promotes liver injury and fibrosis, depending on changes in the diversity of gut microbiota and increased intestinal permeability caused by psychological stress, LPS that enters liver and acts on TLR4, and active LPS-TLR4 pathway depend on MyD88. It demonstrates the possibility of existence of brain-gut-liver axis.

Protective effects of paeonol against lipopolysaccharide-induced liver oxidative stress and inflammation in gibel carp (Carassius auratus gibelio)

Paeonol (2'-hydroxy-4'-methoxyacetophenone) is a phenol that exhibits antioxidant and anti-inflammatory capabilities. In this study, the underlying mechanism of paeonol against LPS-induced oxidative stress and inflammatory responses in gibel carp was investigated. Three hundred healthy gibel carp were divided into five groups (n = 9), intraperitoneally injected with LPS and thereafter treated with paeonol (16 mg/kg and 64 mg/kg). Fish were anesthetized with MS-222 (100 mg/L), and samples were collected at 72 h to investigate plasma biochemical indexes, liver histopathology, antioxidant enzymatic activity, and TLR receptor-related gene expression. Fish injected with LPS (20 mg/kg) exhibited significantly increased plasma aminotransferase (ALT), aminotransferase (AST), lactate dehydrogenase (LDH), glucose (GLU), diamine oxidase (DAO), and alkaline phosphatase (ALP) levels (P < 0.05). In addition, LPS challenge significantly enhanced myeloperoxidase (MPO) and malondialdehyde (MDA) contents, whereas those of catalase (CAT) and glutathione peroxidase (GSH-Px) decreased (P < 0.05). However, treatment with paeonol attenuated these LPS-induced changes (P < 0.05). The mRNA expression of TLR4, TIRAP, MyD88, TRAF6, NF-κB, TNF-α, IL-1β, and IL-8, which were activated by LPS challenge (P < 0.05), were downregulated by paeonol. Additionally, histopathological examination demonstrated that paeonol alleviates LPS-induced hepatic tissue lesions in fish. Taken together, the results suggest that paeonol mitigates LPS-induced liver oxidative stress and inflammation in gibel carp.

Molecular Immune Mechanism of Intestinal Microbiota and Their Metabolites in the Occurrence and Development of Liver Cancer

Intestinal microorganisms are closely associated with immunity, metabolism, and inflammation, and play an important role in health and diseases such as inflammatory bowel disease, diabetes, cardiovascular disease, Parkinson’s disease, and cancer. Liver cancer is one of the most fatal cancers in humans. Most of liver cancers are slowly transformed from viral hepatitis, alcoholic liver disease, and non-alcoholic fatty liver disease. However, the relationship between intestinal microbiota and their metabolites, including short-chain fatty acids, bile acids, indoles, and ethanol, and liver cancer remains unclear. Here, we summarize the molecular immune mechanism of intestinal microbiota and their metabolites in the occurrence and development of liver cancer and reveal the important role of the microbiota-gut-liver axis in liver cancer. In addition, we describe how the intestinal flora can be balanced by antibiotics, probiotics, postbiotics, and fecal bacteria transplantation to improve the treatment of liver cancer. This review describes the immunomolecular mechanism of intestinal microbiota and their metabolites in the occurrence and development of hepatic cancer and provides theoretical evidence support for future clinical practice.

Indole-3-propionic Acid-aggravated CCl4-induced Liver Fibrosis via the TGF-β1/Smads Signaling Pathway

BACKGROUND AND AIMS

The pathogenesis of liver fibrosis involves liver damage, inflammation, oxidative stress, and intestinal dysfunction. Indole-3-propionic acid (IPA) has been demonstrated to have antioxidant, anti-inflammatory and anticancer activities, and a role in maintaining gut homeostasis. The current study aimed to investigate the role of IPA in carbon tetrachloride (CCl₄)-induced liver fibrosis and explore the underlying mechanisms.

METHODS

The liver fibrosis model was established in male C57BL/6 mice by intraperitoneal injection of CCl₄ twice weekly. IPA intervention was made orally (20 mg/kg daily). The degree of liver injury and fibrosis were assessed by serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and histopathology. Enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction (qPCR) were used to detect the inflammatory cytokines. The malondialdehyde (MDA), glutathione, glutathione peroxidase, superoxide dismutase, and catalase were determined via commercial kits. Hepatocyte apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The expression of mRNA and protein was assayed by qPCR, Western blotting, or immunohistochemical staining.

RESULTS

After IPA treatment, the ALT and AST, apoptotic cells, and pro-inflammatory factor levels were enhanced significantly. Moreover, IPA intervention up-regulated the expression of collagen I, α-smooth muscle actin, tissue inhibitor of matrix metalloproteinase-1, matrix metalloproteinase-2, transforming growth factor-β1 (TGF-β1), Smad3, and phosphorylated-Smad2/3. Additionally, IPA intervention did not affect the MDA level. Attractively, the administration of IPA remodeled the gut flora structure.

CONCLUSIONS

IPA aggravated CCl₄-induced liver damage and fibrosis by activating HSCs via the TGF-β1/Smads signaling pathway.

Curdione and Schisandrin C Synergistically Reverse Hepatic Fibrosis via Modulating the TGF-β Pathway and Inhibiting Oxidative Stress

Hepatic fibrosis is the final pathway of several chronic liver diseases, which is characterized by the accumulation of extracellular matrix due to chronic hepatocyte damage. Activation of hepatic stellate cells and oxidative stress (OS) play an important role in mediating liver damage and initiating hepatic fibrosis. Hence, hepatic fibrosis can be reversed by inhibiting multiple channels such as oxidative stress, liver cell damage, or activation of hepatic stellate cells. Liuwei Wuling Tablets is a traditional Chinese medicine formula with the effect of anti- hepatic fibrosis, but the composition and mechanism of reversing hepatic fibrosis are still unclear. Our study demonstrated that one of the main active components of the Chinese medicine Schisandra chinensis, schisandrin C (Sin C), significantly inhibited oxidative stress and prevented hepatocyte injury. Meanwhile one of the main active components of the Chinese medicine Curdione inhibited hepatic stellate cell activation by targeting the TGF-β1/Smads signaling pathway. The further in vivo experiments showed that Sin C, Curdione and the combination of both have the effect of reversing liver fibrosis in mice, and the combined effect of inhibiting hepatic fibrosis is superior to treatment with Sin C or Curdione alone. Our study provides a potential candidate for multi-molecular or multi-pathway combination therapies for the treatment of hepatic fibrosis and demonstrates that combined pharmacotherapy holds great promise in the prevention and treatment of hepatic fibrosis.

Naringenin: A Promising Therapeutic Agent against Organ Fibrosis

Fibrosis is the final common pathology of most chronic diseases as seen in the heart, liver, lung, kidney, and skin and contributes to nearly half of death in the developed countries. Fibrosis, or scarring, is mainly characterized by the transdifferentiation of fibroblasts into myofibroblasts and the excessive accumulation of extracellular matrix (ECM) secreted by myofibroblasts. Despite immense efforts made in the field of organ fibrosis over the past decades and considerable understanding of the occurrence and development of fibrosis gained, there is still lack of an effective treatment for fibrotic diseases. Therefore, identifying a new therapeutic strategy against organ fibrosis is an unmet clinical need. Naringenin, a flavonoid that occurs naturally in citrus fruits, has been found to confer a wide range of pharmacological effects including antioxidant, anti-inflammatory, and anticancer benefits and thus potentially exerting preventive and curative effects on numerous diseases. In addition, emerging evidence has revealed that naringenin can prevent the pathogenesis of fibrosis in vivo and in vitro via the regulation of various pathways that involved signaling molecules such as transforming growth factor-β1/small mother against decapentaplegic protein 3 (TGF-β1/Smad3), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt), sirtuin1 (SIRT1), nuclear factor-kappa B (NF-κB), or reactive oxygen species (ROS). Targeting these profibrotic pathways by naringenin could potentially become a novel therapeutic approach for the management of fibrotic disorders. In this review, we present a comprehensive summary of the antifibrotic roles of naringenin in vivo and in vitro and their underlying mechanisms of action. As a food derived compound, naringenin may serve as a promising drug candidate for the treatment of fibrotic disorders.

Toll-Like Receptors Recognize Intestinal Microbes in Liver Cirrhosis

Liver cirrhosis is one major cause of mortality in the clinic, and treatment of this disease is an arduous task. The scenario will be even getting worse with increasing alcohol consumption and obesity in the current lifestyle. To date, we have no medicines to cure cirrhosis. Although many etiologies are associated with cirrhosis, abnormal intestinal microbe flora (termed dysbiosis) is a common feature in cirrhosis regardless of the causes. Toll-like receptors (TLRs), one evolutional conserved family of pattern recognition receptors in the innate immune systems, play a central role in maintaining the homeostasis of intestinal microbiota and inducing immune responses by recognizing both commensal and pathogenic microbes. Remarkably, recent studies found that correction of intestinal flora imbalance could change the progress of liver cirrhosis. Therefore, correction of intestinal dysbiosis and targeting TLRs can provide novel and promising strategies in the treatment of liver cirrhosis. Here we summarize the recent advances in the related topics. Investigating the relationship among innate immunity TLRs, intestinal flora disorders, and liver cirrhosis and exploring the underlying regulatory mechanisms will assuredly have a bright future for both basic and clinical research.

Hepatic stellate cells specific liposomes with the Toll-like receptor 4 shRNA attenuates liver fibrosis

The hepatic stellate cells (HSCs) play a significant role in the onset of liver fibrosis, which can be treated by the inhibition and reversal of HSC activation. The RNA interference-mediated TLR4 gene silencing might be a potential therapeutic approach for liver fibrosis. The crucial challenge in this method is the absence of an efficient delivery system for the RNAi introduction in the target cells. HSCs have an enhanced capacity of vitamin A intake as they contain retinoic acid receptors (RARs). In the current study, we developed cationic liposomes modified with vitamin A to improve the specificity of delivery vehicles for HSCs. The outcome of this study revealed that the VitA-coupled cationic liposomes delivered the TLR4 shRNA to aHSCs more efficiently, as compared to the uncoupled cationic liposomes, both in the in vitro and in vivo conditions. Besides, as evident from the outcome of this study, the TLR4 gene silencing inhibited the HSCs activation and attenuated the liver fibrosis via the NF-κB transcriptional inactivation, pro-inflammatory cytokines secretion and reactive oxygen species (ROS) synthesis. Thus, the VitA-coupled liposomes encapsulated with the TLR4-shRNA might prove as an efficient therapeutic agent for liver fibrosis.

Extracellular histones stimulate collagen expression in vitro and promote liver fibrogenesis in a mouse model via the TLR4-MyD88 signaling pathway

BACKGROUND

Liver fibrosis progressing to liver cirrhosis and hepatic carcinoma is very common and causes more than one million deaths annually. Fibrosis develops from recurrent liver injury but the molecular mechanisms are not fully understood. Recently, the TLR4-MyD88 signaling pathway has been reported to contribute to fibrosis. Extracellular histones are ligands of TLR4 but their roles in liver fibrosis have not been investigated.

AIM

To investigate the roles and potential mechanisms of extracellular histones in liver fibrosis.

METHODS

In vitro, LX2 human hepatic stellate cells (HSCs) were treated with histones in the presence or absence of non-anticoagulant heparin (NAHP) for neutralizing histones or TLR4-blocking antibody. The resultant cellular expression of collagen I was detected using western blotting and immunofluorescent staining. In vivo, the CCl4-induced liver fibrosis model was generated in male 6-week-old ICR mice and in TLR4 or MyD88 knockout and parental mice. Circulating histones were detected and the effect of NAHP was evaluated.

RESULTS

Extracellular histones strongly stimulated LX2 cells to produce collagen I. Histone-enhanced collagen expression was significantly reduced by NAHP and TLR4-blocking antibody. In CCl4-treated wild type mice, circulating histones were dramatically increased and maintained high levels during the duration of fibrosis-induction. Injection of NAHP not only reduced alanine aminotransferase and liver injury scores, but also significantly reduced fibrogenesis. Since the TLR4-blocking antibody reduced histone-enhanced collagen I production in HSC, the CCl4 model with TLR4 and MyD88 knockout mice was used to demonstrate the roles of the TLR4-MyD88 signaling pathway in CCl4-induced liver fibrosis. The levels of liver fibrosis were indeed significantly reduced in knockout mice compared to wild type parental mice.

CONCLUSION

Extracellular histones potentially enhance fibrogenesis via the TLR4-MyD88 signaling pathway and NAHP has therapeutic potential by detoxifying extracellular histones.

Targeted treatment of alcoholic liver disease based on inflammatory signalling pathways

Targeted therapy is an emerging treatment strategy for alcoholic liver disease (ALD). Inflammation plays an important role in the occurrence and development of ALD, and is a key choice for its targeted treatment, and anti-inflammatory treatment has been considered beneficial for liver disease. Surprisingly, immune checkpoint inhibitors have become important therapeutic agents for hepatocellular carcinoma (HCC). Moreover, studies have shown that the combination of inflammatory molecule inhibitors and immune checkpoint inhibitors can exert better effects than either alone in mouse models of HCC. This review discusses the mechanism of hepatic ethanol metabolism and the conditions under which inflammation occurs. In addition, we focus on the potential molecular targets in inflammatory signalling pathways and summarize the potential targeted inhibitors and immune checkpoint inhibitors, providing a theoretical basis for the targeted treatment of ALD and the development of new combination therapy strategies for HCC.

Lipopolysaccharide Reverses Hepatic Stellate Cell Activation Through Modulation of cMyb, Small Mothers Against Decapentaplegic, and CCAAT/Enhancer-Binding Protein C/EBP Transcription Factors

BACKGROUND AND AIMS

During liver injury, quiescent hepatic stellate cells (qHSCs) transdifferentiate into proliferative and fibrogenic activated myofibroblastic phenotype (activated hepatic stellate cell; aHSCs) expressing smooth muscle α-actin (αSMA) and platelet-derived growth factor beta receptor (PDGFβR). Their interactions with gut-derived bacterial lipopolysaccharide (LPS) are implicated in hepatic fibrogenesis. However, LPS can also attenuate fibrogenic characteristics of aHSCs.

APPROACH AND RESULTS

We examined molecular mechanisms of antifibrogenic effects of LPS on aHSCs in vitro and in vivo. Culture-activated rat HSCs were exposed to 0-100 ng/mL of LPS or its active component, diphosphoryl-lipid A (DPLA), and parameters of fibrosis and inflammatory cytokines/chemokines were determined by qRT-PCR, western, and immunohistochemical analyses. In vivo, HSCs were activated by repeated CCl4 administration to rats every 3 days for 3 or 8 weeks, then challenged with LPS (5 mg/kg; IP). HSCs were isolated 24 hours later, and fibrogenic/inflammatory parameters were analyzed. LPS induced phenotypic changes in aHSCs (rounding, size reduction) and loss of proliferation. LPS down-regulated expression of αSMA, PDGFβR, transforming growth factor beta receptor 1 (TGFβR1), collagen 1α1 (Col1α1), and fibronectin while up-regulating tumor necrosis factor alpha, interleukin-6, and C-X-C motif chemokine ligand 1 expression. LPS did not increase peroxisome proliferation-activated receptor gamma expression or lipid accumulation typical of qHSCs. DPLA elicited the same effects as LPS on aHSCs, indicating specificity, and monophosphoryl lipid A down-regulated fibrogenic markers, but elicited very weak inflammatory response. LPS down-regulated the expression of cMyb, a transcription factor for αSMA, and up-regulated small mother against decapentaplegic (SMAD)7 and CCAAT/enhancer-binding protein (C/EBP)δ, the transcriptional inhibitors of Col1α1 expression. In vivo LPS treatment of aHSCs inhibited their proliferation, down-regulated PDGFβR, αSMA, TGFβR1, Col1α1, and cMyb expression, and increased expression of SMAD7, C/EBPα, and C/EBPδ.

CONCLUSIONS

In conclusion, LPS induces a unique phenotype in aHSCs associated with down-regulation of key fibrogenic mechanisms and thus may have an important role in limiting fibrosis.

Abscisic acid ameliorates oxidative stress, inflammation, and apoptosis in thioacetamide-induced hepatic fibrosis by regulating the NF-кB signaling pathway in mice

The purpose of this study was to determine whether abscisic acid (ABA) can protect against liver fibrosis induced by thioacetamide (TAA) in vivo by inhibiting apoptosis and inflammatory responses. To this end, three times per week, mice were injected intraperitoneally with TAA (200 mg/kg) for 8 weeks to induce liver fibrosis. After the fourth week of treatment, histological changes, the serum biochemical index, inflammation, and hepatocyte apoptosis factors (e.g., caspase-3, B-cell lymphoma 2 [Bcl-2], Bcl-2-associated X [Bax]) were detected to clarify its underlying mechanism. The results clearly indicated that ABA improves TAA-induced hepatic injury and collagen accumulation in mice. Otherwise, ABA significantly reduced liver fibrosis by regulating caspase-3 and Bcl-2, α-smooth muscle actin, and collagen I. ABA inhibited the nuclear factor kappa B pathway, significantly alleviating oxidative stress and inflammatory cytokines. Therefore, ABA may be a potential therapeutic agent for preventing liver damage.

miR-16 integrates signal pathways in myofibroblasts: determinant of cell fate necessary for fibrosis resolution

Liver fibrosis is characterized by the transdifferentiation of hepatic stellate cells (HSCs) to myofibroblasts and poor response to treatment. This can be attributed to the myofibroblast-specific resistance to phenotype reversal. In this study, we complemented miR-16 into miR-16-deficient myofibroblasts and analyzed the global role of miR-16 using transcriptome profiling and generating a pathway-based action model underlying transcriptomic regulation. Phenotypic analysis of myofibroblasts and fibrogenic characterization were used to understand the effect of miR-16 on phenotypic remodeling of myofibroblasts. miR-16 expression altered the transcriptome of myofibroblasts to resemble that of HSCs. Simultaneous targeting of Smad2 and Wnt3a, etc. by miR-16 integrated signaling pathways of TGF-β and Wnt, etc., which underlay the comprehensive regulation of transcriptome. The synergistic effect of miR-16 on the signaling pathways abolished the phenotypic characteristics of myofibroblasts, including collagen production and inhibition of adipogenesis. In vivo, myofibroblast-specific expression of miR-16 not only eliminated mesenchymal cells with myofibroblast characteristics but also restored the phenotype of HSCs in perisinusoidal space. This phenotypic remodeling resolved liver fibrosis induced by chronic wound healing. Therefore, miR-16 may integrate signaling pathways crucial for the fate determination of myofibroblasts. Its global effect induces the reversal of HSC-to-myofibroblast transdifferentiation and, subsequently, the resolution of fibrogenesis. Taken together, these findings highlight the potential of miR-16 as a promising therapeutic target for liver fibrosis.

Pro- and Anti-fibrogenic Functions of Gram-Negative Bacterial Lipopolysaccharide in the Liver

Extensive research performed over several decades has identified cells participating in the initiation and progression of fibrosis, and the numerous underlying inter- and intra-cellular signaling pathways. However, liver fibrosis continues to be a major clinical challenge as the precise targets of treatment are still elusive. Activation of physiologically quiescent perisinusoidal hepatic stellate cells (HSCs) to a myofibroblastic proliferating, contractile and fibrogenic phenotype is a critical event in the pathogenesis of chronic liver disease. Thus, elucidation of the mechanisms of the reversal to quiescence or inhibition of activated HSCs, and/or their elimination via apoptosis has been the focus of intense investigation. Lipopolysaccharide (LPS), a gut-resident Gram-negative bacterial endotoxin, is a powerful pro-inflammatory molecule implicated in hepatic injury, inflammation and fibrosis. In both acute and chronic liver injury, portal venous levels of LPS are elevated due to increased intestinal permeability. LPS, via CD14 and Toll-like receptor 4 (TLR4) and its adapter molecules, stimulates macrophages, neutrophils and several other cell types to produce inflammatory mediators as well as factors that can activate HSCs and stimulate their fibrogenic activity. LPS also stimulates synthesis of pro- and anti-inflammatory cytokines/chemokines, growth mediators and molecules of immune regulation by HSCs. However, LPS was found to arrest proliferation of activated HSCs and to convert them into non-fibrogenic phenotype. Interestingly, LPS can elicit responses in HSCs independent of CD14 and TLR4. Identifying and/or developing non-inflammatory but anti-fibrogenic mimetics of LPS could be relevant for treating liver fibrosis.

Hepatic injury and inflammation alter ethanol metabolism and drinking behavior

While liver injury is commonly associated with excessive alcohol consumption, how liver injury affects alcohol metabolism and drinking preference remains unclear. To answer these questions, we measured the expression and activity of alcohol dehydrogenase 1 (ADH1) and acetaldehyde dehydrogenase 2 (ALDH2) enzymes, ethanol and acetaldehyde levels in vivo, and binge-like and preferential drinking behaviors with drinking in the dark and two-bottle choice in animal models with liver injury. Acute and chronic carbon tetrachloride (CCl4), and acute LPS-induced liver injury repressed hepatic ALDH2 activity and expression and consequently, blood and liver acetaldehyde concentrations were increased in these models. In addition, chronic CCl4 and acute LPS treatment inhibited hepatic ADH1 expression and activity, leading to increases in blood and liver ethanol concentrations. Consistent with the increase in acetaldehyde levels, alcohol drinking behaviors were reduced in mice with acute or chronic liver injury. Furthermore, oxidative stress induced by hydrogen peroxide attenuated ADH1 and ALDH2 activity post-transcriptionally, while proinflammatory cytokines led to transcriptional repression of ADH1 and ALDH2 in cultured hepatocytes, which correlated with the repression of transcription factor HNF4α. Collectively, our data suggest that alcohol metabolism is suppressed by inflammation and oxidative stress, which is correlated with decreased drinking behavior.

TGF-β- and lipopolysaccharide-induced upregulation of circular RNA PWWP2A promotes hepatic fibrosis via sponging miR-203 and miR-223

Both transforming growth factor-beta (TGF-β) and lipopolysaccharide (LPS) can activate hepatic stellate cells (HSCs), thus increasing expressions of alpha smooth muscle actin (α-SMA) and type I collagen alpha 1 (Col1α1) and promoting liver fibrosis. However, whether TGF-β and LPS have a common downstream reactor remains unclear. Recently, a strong relationship of circular RNAs (circRNAs) and fibrogenesis has been elucidated. In this study, we compared the expressions of several circRNAs in TGF-β- and LPS-activated HSCs, and found that circ-PWWP2A was upregulated in both TGF-β- and LPS-activated HSCs and in mouse fibrotic liver tissues. Meanwhile, circ-PWWP2A was positively correlated with HSC activation and proliferation. Two microRNAs, miR-203 and miR-223, were identified to be the downstream targets of circ-PWWP2A using luciferase reporter assay and pull-down interaction assay. Circ-PWWP2A was suggested to promote HSC activation and proliferation via sponging miR-203 and miR-223, and subsequently increasing Fstl1 and TLR4, respectively. Furthermore, downregulating circ-PWWP2A was indicated to alleviate hepatic fibrosis in vivo. In conclusion, our findings indicated that circ-PWWP2A is the common downstream reactor of TGF-β and LPS in HSC activation, and that circ-PWWP2A plays a critical role in hepatic fibrogenesis via sponging miR-203 and miR-223.

Synthesis of radioiodinated carnosine for hepatotoxicity imaging induced by carbon tetrachloride and its biological assessment in rats

The imaging of organs is very important in the field of diagnosis especially in case of liver diseases. In the present work, carnosine was successfully labeled with iodine-131 at room temperature in acidic medium using chloramine-T (Ch-T) as moderate oxidizing agent. The parameters affecting labeling of carnosine such as amount of oxidizing agent, amount of substrate, pH value of the reaction mixture, reaction temperature and reaction time, were investigated. The best conditions for formation of 131I-carnosine (131I-CAR) complex were 40 μg of chloramine-T (Ch-T), 75 μg of carnosine, pH 4 and 45 min reaction time at room temperature. The radiochemical yield for 131I-CAR complex was (91 ± 0.11) % at optimum conditions and the labeled complex was stable for 2 h after labeling process. Biodistribution study was achieved using three groups of rats (normal, treated by inactive carnosine and hepatotoxicity rats induced by CCl4). Hepatotoxicity of liver was evaluated using different biochemical markers such as ALT, AST and ALK.P. The 131I-CAR complex showed selective bio-localization in stomach and liver and its selectivity increases in acquired hepatotoxicity. The biological distribution indicates that the suitability of 131I-CAR as a potential hepatotoxicity imaging to detect hepatitis and medical prognosis.

Intestinally derived bacterial products stimulate development of nonalcoholic steatohepatitis

Fatty livers are susceptible to factors that cause inflammation and fibrosis, but fat deposition and the inflammatory response can be dissociated. While nonalcoholic fatty liver disease (NAFLD), caused by pathologic fat accumulation inside the liver, can remain stable for several years, in other cases NAFLD progresses to nonalcoholic steatohepatitis (NASH), which is characterized by fat accumulation and inflammation and is not a benign condition. In this review, we discuss the NASH host cells and microbial mechanisms that stimulate inflammation and predispose the liver to hepatocyte injury and fibrotic stages via increased lipid deposition. We highlight the interactions between intestine-derived bacterial products, such as lipopolysaccharide, and nutritional models of NAFLD and/or obese individuals. The results of modulating enteric microbiota suggest that gut-derived endotoxins may be essential determinants of fibrotic progression and regression in NASH.

Natural Compound Oridonin Inhibits Endotoxin-Induced Inflammatory Response of Activated Hepatic Stellate Cells

Hepatic stellate cells (HSCs) play an important role in hepatic fibrogenesis and inflammatory modulation. Endotoxin is dramatically increased in portal venous blood after serious injury and can contribute to liver damage. However, the mechanism underlying endotoxin's effects on HSCs remains largely unknown. Oridonin is a bioactive diterpenoid isolated from Rabdosia rubescens that exhibits anti-inflammatory properties in different tissues. In the present study, we determined the effects of oridonin on endotoxin-induced inflammatory response and signaling pathways in vitro. The production of proinflammatory cytokines in activated human HSCs line LX-2 was measured by ELISA and Western blots. Immunofluorescence and nuclear fractionation assay were used to determine NF-κB activity. Oridonin treatment significantly inhibited LPS-induced proinflammatory cytokines IL-1β, IL-6, and MCP-1 production as well as cell adhesion molecules ICAM-1 and VCAM-1. Additionally, oridonin blocked LPS-induced NF-κB p65 nuclear translocation and DNA binding activity. Oridonin prevented LPS-stimulated NF-κB regulator IKKα/β and IκBα phosphorylation and IκBα degradation. Combined treatment of oridonin and an Hsp70 substrate binding inhibitor synergistically suppressed LPS-stimulated proinflammatory cytokines and NF-κB pathway activation. Therefore, oridonin inhibits LPS-stimulated proinflammatory mediators through IKK/IκBα/NF-κB pathway. Oridonin could be a promising agent for a hepatic anti-inflammatory.

Methyl ferulic acid attenuates liver fibrosis and hepatic stellate cell activation through the TGF-β1/Smad and NOX4/ROS pathways

Liver fibrosis is a pathological wound-healing response caused by chronic liver damage due to a virus, autoimmune disorder, or drugs. Hepatic stellate cells (HSCs) play an essential role in the pathogenesis of liver fibrosis. Methyl ferulic acid (MFA), a biologically active monomer, has a protective effect on liver injury. However, the effects and roles of MFA in liver fibrosis remain unknown. The purpose of the current study was to investigate the effect of MFA on hepatic fibrosis and the underlying mechanisms. Human hepatic stellate LX-2 cells were exposed to 5 μg/L TGF-β1 for 48 h to stimulate liver fibrosis in vitro. Using MTT, RT-PCR and Western blot analysis, we revealed that MFA significantly inhibited the proliferation of LX-2 cells as well as decreased the expressions of α-SMA and type I collagen in LX-2 cells. SD rats were fed with ethanol, and this combined with the intraperitoneal injection of CCl₄ induced liver fibrosis in vivo. We found that the administration of MFA markedly decreased the levels of hyaluronic acid (HA), procollagen type III (PC-III), type IV collagen (CIV) and laminin (LN) in the serum, inhibited the expression of α-smooth muscle actin (α-SMA) as well as type I and type III collagen, and up-regulated the ratio of MMP-2/TIMP-1 in rats. The antifibrotic effects of MFA were also evaluated by H&E staining and Masson's trichrome staining. In addition, further studies suggested that this protection by MFA from liver fibrosis was possibly related to the inhibition of TGF-β1/Smad and NOX4/ROS signalling. In conclusion, our results demonstrate that MFA attenuated liver fibrosis and hepatic stellate cell activation by inhibiting the TGF-β1/Smad and NOX4/ROS signalling pathways.

Mechanisms of concanavalin A-induced cytokine synthesis by hepatic stellate cells: Distinct roles of interferon regulatory factor-1 in liver injury

Mice depleted of hepatic stellate cells (HSCs) are protected from concanavalin A (ConA)-induced liver injury that is mediated by the activation of interferon regulatory factor 1 (IRF1). The aim of this study was to determine the mechanisms of ConA-mediated signaling and synthesis/release of mediators by HSCs that damage hepatocytes. Primary cultures of wildtype (WT) and IRF1-knockout (KO) HSCs and hepatocytes were used, and ConA-induced liver damage in interferon (IFN)αβ receptor-deficient (IFNαβR-KO) mice was determined. Specific binding of ConA to HSCs induced rapid activation of JAK2 and STAT1. ConA-induced expression of IRF1, IFNβ, tumor necrosis factor α, and CXCL1 was abrogated by selective inhibition of JAK2 and STAT1. Despite activating JAK2/STAT1, ConA failed to stimulate expression of inflammatory cytokines in HSCs from IRF1-KO mice. ConA-conditioned WT-HSC medium caused activation of JNK and caspase 3, and apoptosis of hepatocytes from WT but not from IRF1-KO or IFNαβR-KO mice. Conversely, ConA-conditioned medium of IRF1-KO HSCs failed to cause apoptosis of WT or IRF1-KO hepatocytes. IFNαβR-KO mice were protected from ConA-induced liver damage, and ConA-induced hepatic expression of IRF1 and pro-inflammatory cytokines and chemokines, and infiltration of neutrophils were significantly lower in IFNαβR-KO than in WT mice. These results demonstrate distinct roles of IRF1 in hepatic inflammation (HSCs) and injury (hepatocytes) and can be an important target for intervention in acute liver injury.

Triptriolide Alleviates Lipopolysaccharide-Induced Liver Injury by Nrf2 and NF-κB Signaling Pathways

Nrf2 (Nuclear Factor Erythroid 2 Related Factor 2) transcription factor not only regulates oxidative stress response, but also represses inflammation by regulating cytokines production and cross-talking with NF-κB signaling pathways. Nrf2 plays an essential role in liver injury induced by oxidative stress and inflammation. Triptriolide (T11) is a minor component of Tripterygium wilfordii Hook F. (TwHF), which can be obtained by hydrolysis reaction of triptolide (T9). The major purpose of this study is to clarify the regulating effects of T11 on oxidative stress and inflammation in vivo and in vitro. LPS-stimulated RAW 264.7 cells were used to verify the regulating effects of T11 on oxidative stress (ROS and Nrf2 signaling pathway) and inflammatory cytokines production (TNF-α, IL-6 and IL-1β). The antioxidant responsive element (ARE) luciferase assay was employed to evaluate Nrf2 activation effect of T11 in HEK-293T cells. Lipopolysaccharides (LPS) induced acute liver injury (ALI) in BALB/c mice were used to study the protective effects (ALT, AST, MDA, SOD, histopathology and neutrophils/macrophages filtration) and the underlying protection mechanisms of ALI amelioration (Nrf2 and NF-κB signaling pathway) of T11. Firstly, the results showed that T11 can not only effectively decrease the productions of inflammatory cytokines (TNF-α, IL-6 and IL-1β), ROS and NO in LPS-stimulated RAW 264.7 cells, but also further significantly increase the activity of Nrf2 in HEK-293T cells. Secondly, the results suggested that T11 could dramatically decrease the oxidative stress responses (SOD and MDA) and inflammation (histopathology, neutrophils/macrophages filtration, TNF-α, IL-6 and IL-1β production) in LPS-induced ALI in BALB/c mice. Finally, the results implied that T11 could dramatically increase Nrf2 protein expression and decrease p-TAK1, p-IκBα and NF-κB protein expression both in vivo and in vitro. In conclusion, our findings indicated that T11 could alleviate LPS induced oxidative stress and inflammation by regulating Nrf2 and NF-κB signaling pathways in vitro and in vivo, which offers a novel insights for the application of TwHF in clinical.

Emodin Attenuates Lipopolysaccharide-Induced Acute Liver Injury via Inhibiting the TLR4 Signaling Pathway in vitro and in vivo

Aims: Emodin is an anthraquinone with potential anti-inflammatory properties. However, the possible molecular mechanisms and protective effects of emodin are not clear. The objective of this study was to investigate the possible molecular mechanisms and protective effects of emodin on lipopolysaccharide (LPS)-induced acute liver injury (ALI) via the Toll-like receptor 4 (TLR4) signaling pathway in the Raw264.7 cell line and in Balb/c mice. Methods: This study established an inflammatory cellular model and induced an ALI animal model. TLR4 was overexpressed by lentivirus and downregulated by small interfering RNA (siRNA) technology. The mRNA and protein levels of TLR4 and downstream molecules were detected in cells and liver tissue. The tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 levels in supernatant and serum were determined by ELISA. The distribution and expression of mannose receptor C type 1 (CD206) and arginase 1 (ARG1) in the liver were tested by immunofluorescence. Mouse liver function and histopathological observations were assessed. Results: Administration of emodin reduced the protein and/or mRNA levels of TLR4 and its downstream molecules following LPS challenge in Raw264.7 cells and in an animal model. Additionally, emodin suppressed the expression of TNF-α and IL-6 in cell culture supernatant and serum. The inhibitory effect of emodin was also confirmed in RAW264.7 cells, in which TLR4 was overexpressed or knocked down. Additionally, ARG1 and CD206 were elevated in the emodin groups. Emodin also decreased serum ALT and AST levels and alleviated the liver histopathological damage induced by LPS. Conclusion: Emodin showed excellent hepatoprotective effects against LPS-induced ALI, possibly by inhibiting TLR4 signaling pathways.

Emodin alleviates CCl4‑induced liver fibrosis by suppressing epithelial‑mesenchymal transition and transforming growth factor‑β1 in rats

Liver fibrosis is a chronic disease that exhibits a complicated pathophysiology. It is characterized by the deposition of the extracellular matrix. Emodin, an active constituent isolated from rhubarb, has antibacterial, immunosuppressive and anti-inflammatory effects. In the present study, the mechanism through which emodin alleviates liver fibrosis in rats was investigated. A rat model of liver fibrosis was generated by administering CCl₄ via subcutaneous injection twice a week for 12 weeks. Emodin or sodium carboxymethylcellulose (CMC), as the vehicle, were intragastrically administered daily. After 12 weeks, the liver function index was examined by blood analysis, histopathological scores of fibrosis was determined by hematoxylin and eosin staining and level of collagen deposition was examined by Masson staining. In addition, protein and RNA samples were collected for further analysis. The results of the present study revealed that emodin significantly reduced the liver function index and level of collagen deposition in a dose-dependent manner. Furthermore, emodin reduced the expression of transforming growth factor-β1 (TGF-β1) and the phosphorylation levels of mothers against decapentaplegic homolog 2/3, and inhibited the CCl₄-induced downregulation of E-cadherin and upregulation of the mesenchymal markers, fibronectin and vimentin. The expression levels of TGF-β1, Snail family transcriptional repressor (Snail) 2, Snail, twist-related protein 1 and zinc finger E-box-binding homeobox (ZEB)1 and 2 mRNA were significantly decreased in emodin-treated groups compared with the untreated control. Collectively, the results of the present study suggested that emodin may exert antifibrotic effects via the suppression of TGF-β1 signaling and epithelial-mesenchymal transition.

Evodiamine ameliorates liver fibrosis in rats via TGF-β1/Smad signaling pathway

Liver fibrosis is considered to be a result of chronic liver pathological changes, and hepatic stellate cells (HSCs) play an important role during this process. Evodiamine, an indole alkaloid derived from Evodia rutaecarpa, exhibits pharmacological activities. This study focused on the effects of evodiamine on carbon tetrachloride (CCl₄)-induced liver fibrosis in rats and HSCs in vitro via the TGF-β1/Smad signaling pathway. A liver fibrosis rat model was established by the intraperitoneal injection of CCl₄ (3 ml/kg, 30% in olive oil). Evodiamine (15 and 25 mg/kg) was administered orally for 8 weeks. HSCs were treated with different evodiamine concentrations. The results indicated that evodiamine could improve the histopathological abnormalities in liver tissues and decrease the level of aspartate aminotransferase (AST), alanine aminotransferase (ALT), hydroxyproline, and total bilirubin (TBIL). Concentrations of IL-6, tumor necrosis factor-α (TNF-α), collagen-I (COL-I), and collagen-III (COL-III) were reduced by evodiamine. Western blotting and real-time PCR showed that protein expression of transforming growth factor-β (TGF-β1), p-Smad 2/3 (phosphorylation of Smad 2/3), and smooth muscle alpha-actin (α-SMA) as well as mRNA expression of TGF-β1 and α-SMA in liver tissues were downregulated by evodiamine. The cell proliferation, production of hydroxyproline, and the protein expression of TGF-β1, p-Smad 2/3, and α-SMA in HSCs were dose-dependently reduced by evodiamine. Collectively, evodiamine had an antifibrosis effect in CCl₄-induced liver fibrosis, and reduced HSCs proliferation and collagen metabolism in vitro. The major mechanism was downregulation of relative expression of TGF-β1, p-Smad 2/3, and α-SMA.