Toll like receptor 2 knock-out attenuates carbon tetrachloride (CCl4)-induced liver fibrosis by downregulating MAPK and NF-κB signaling pathways

Gut microbiota in MAFLD: therapeutic and diagnostic implications

Metabolic dysfunction-associated fatty liver disease (MAFLD), formerly known as nonalcoholic fatty liver disease, is becoming a significant contributor to chronic liver disease globally, surpassing other etiologies, such as viral hepatitis. Prevention and early treatment strategies to curb its growing prevalence are urgently required. Recent evidence suggests that targeting the gut microbiota may help treat and alleviate disease progression in patients with MAFLD. This review aims to explore the complex relationship between MAFLD and the gut microbiota in relation to disease pathogenesis. Additionally, it delves into the therapeutic strategies targeting the gut microbiota, such as diet, exercise, antibiotics, probiotics, synbiotics, glucagon-like peptide-1 receptor agonists, and fecal microbiota transplantation, and discusses novel biomarkers, such as microbiota-derived testing and liquid biopsy, for their diagnostic and staging potential. Overall, the review emphasizes the urgent need for preventive and therapeutic strategies to address the devastating consequences of MAFLD at both individual and societal levels and recognizes that further exploration of the gut microbiota may open avenues for managing MAFLD effectively in the future.

The Ameliorative Role of Lico A on Aflatoxin B1-Triggered Hepatotoxicity Partially by Activating Nrf2 Signal Pathway

Aflatoxin B1 (AFB1) is one of the most harmful and toxic mycotoxins in foods and feeds, posing a serious health risk to both humans and animals, especially its hepatotoxicity. Nuclear factor-erythroid 2-related factor 2 (Nrf2), an important nuclear transcription factor, is generally recognized as a potential target for phytochemicals to ameliorate liver injury. The current study sought to elucidate the molecular processes by which licochalcone A (Lico A), a compound derived from Xinjiang licorice Glycyrrhiza inflate, protects against AFB1 toxicity. In vivo, male wild-type (WT) and Nrf2 knockout (Nrf2-/-) C57BL/6 mice were orally administered AFB1 at 1.5 mg/kg body weight (BW) with or without Lico A at 5 mg/kg. In vitro, AML12 cells were utilized to evaluate the protective effect and mechanism of Lico A against the AFB1-induced hepatotoxicity. Our findings demonstrated that AFB1 caused severe hepatotoxicity, while Lico A treatment successfully relieved the toxicity. Meanwhile, Lico A effectively improved liver injury, inflammatory mediators, oxidative insults, apoptosis, liver fibrosis, and pyroptosis, which contributed to the inhibition of toll receptor 4 (TLR4)-NF-κB/MAPK and NOD-like receptors protein 3 (NLRP3)/caspase-1/GSDMD signaling pathway activation. Furthermore, Lico A was able to enhance the Nrf2 antioxidant signaling pathway. Intriguingly, Lico A still had a protective effect on AFB1-caused liver injury in mice via the inhibition of inflammation and pyroptosis, while apoptosis and liver fibrosis were blocked in the absence of Nrf2. To sum up, the present study first elucidated that Lico A ameliorated AFB1-induced hepatotoxic effects and its main mechanism involved the inhibitory effects on oxidative stress, apoptosis, liver fibrosis, inflammation, and pyroptosis, which might be partially dependent on the regulation of Nrf2. The work may enrich the role and mechanism of Lico A's resistance to liver injury caused by various factors, and its application is promising.

Unveiling the hub genes associated with aflatoxin B1-induced hepatotoxicity in chicken

Aflatoxin B1 (AFB1), a ubiquitous and toxic mycotoxin in human food and animal feedstuff, can impair the function and health of some organs, especially the liver. However, the knowledge about the potential mechanisms of AFB1-induced hepatotoxicity in chickens is limited. Therefore, we analyzed the gene expression data of chicken embryo primary hepatocytes (CEPHs) treated with and without AFB1 at the dose of 0.1 μg/mL which were cultured at 37 °C in Medium 199 (Life Technologies, Shanghai, China) with 5.0% CO2 for 48 h. Totally 1,711 differentially expressed genes (DEGs) were identified, in which 1,170 and 541 genes were up- and down-regulated in AFB1-administrated CEPHs compared to the control, respectively. Biological process analysis suggested that these DEGs might take part in angiogenesis, cell adhesion, immune response, cell differentiation, inflammatory response, cell migration regulation, and blood coagulation. Signaling pathways analysis revealed that these DEGs were mainly linked to metabolic pathways, MAPK, TLR2, and actin cytoskeleton regulation pathways. Moreover, the hub genes, including GYS2, NR1H4, ALDH8A1, and ANGPTL3, might participate in AFB1-induced hepatotoxicity. Taken together, our study offers a new insight into the mechanisms of the AFB1-induced hepatotoxicity.

Polysaccharides from Oudemansiella radicata residues attenuate carbon tetrachloride-induced liver injury

In addition to fruiting bodies and mycelia, the mushroom residues have also been demonstrated to be rich in polysaccharides which have attracted academic attentions owing to their extensive bioactivities. Therefore, the present work aimed to investigate the potential hepatoprotective effects of Oudemansiella radicata residues polysaccharides (RPS). Our results demonstrated that RPS showed significantly protective effects against carbon tetrachloride (CCl₄)-induced liver injury, and the possible mechanisms may be related with the predominant bioactivities of RPS containing anti-oxidation by activating the Nrf2 signal pathways, anti-inflammation by inhibiting NF-κB signal pathways and reducing the release of inflammatory cytokines, anti-apoptosis by regulating Bcl-2/Bax pathway, and anti-fibrosis by inhibiting the expressions of TGF-β1, Hyp and α-SMA, respectively. These findings suggested that RPS, a typical β-type glycosidic pyranose-polysaccharides, could be used as promising diet supplement or medication for the adjunctive treatment of hepatic diseases, and also contributed to promoting the recyclable utilization of mushroom residues.

Clonorchis sinensis aggravates biliary fibrosis through promoting IL-6 production via toll-like receptor 2-mediated AKT and p38 signal pathways

Clonorchis sinensis is an important food-borne zoonotic parasite which has been linked to biliary fibrosis and cholangiocarcinoma. However, the details of the pathogenesis of C. sinensis were unclear. To explore the role and regulatory mechanism of toll-like receptor 2 (TLR2) in C. sinensis-induced biliary fibrosis, we established the C. sinensis-infected C57BL/6 mouse model with TLR2-/- and wild type (WT) mice. The mortality rate, liver lesions, TLR2 and TGF-β1 expression, phosphorylation of Smad2/3, AKT, p38, ERK and p65, and cytokine productions were analyzed. Furthermore, similar parameters were examined in mouse biliary epithelial cells (BECs) co-cultured with C. sinensis excretory/secretory proteins (ESPs). The results showed that TLR2 expression was enhanced significantly in C. sinensis-infected WT mice and mouse BECs. C. sinensis-infected TLR2-/- mice exhibited an increased weight and a decreased mortality rate; significantly alleviated liver lesions and biliary fibrosis, reduced numbers of myofibroblasts; decreased expression of TGF-β1 and phosphorylation level of AKT, p38 and Smad2/3; significantly decreased production of IL-6, TNF-α and IL-4, while increased production of IFN-γ compared with C. sinensis-infected WT mice. Furthermore, C. sinensis ESPs could activate TLR2-mediated AKT and p38 pathways to increase the production of IL-6 in mouse BECs. In conclusion, these data indicate that C. sinensis infection activated TGF-β1-Smad2/3 through TLR2-mediated AKT and p38 pathways to promote IL-6 production, which resulted in myofibroblast activation and aggravating biliary fibrosis in mice.

Tandem mass tag-based proteomics analysis reveals the multitarget mechanisms of Phyllanthus emblica against liver fibrosis

Phyllanthus emblica (PE), a traditional multiethnic herbal medicine, is commonly applied to treat liver diseases. Our previous study demonstrated that aqueous extract of PE (AEPE) could alleviate carbon tetrachloride (CCl₄)-induced liver fibrosis in vivo, but the underlying molecular mechanisms are still unclear. The present study was undertaken to clarify the multitarget mechanisms of PE in treating liver fibrosis by proteomics clues. A CCl₄-induced liver fibrosis rat model was established. The anti-liver fibrosis effects of chemical fractions from AEPE were evaluated by serum biochemical indicators and pathological staining. Additionally, tandem mass tag (TMT) - based quantitative proteomics technology was used to detect the hepatic differentially expressed proteins (DEPs). The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, gene ontology (GO) enrichment and protein-protein interaction (PPI) network were used to perform bioinformatics analysis of DEPs. Western blot analysis was used to verify the key potential targets regulated by the effective fraction of AEPE. The low-molecular-weight fraction of AEPE (LWPE) was determined to be the optimal anti-liver fibrosis active fraction, that could significantly improve ALT, AST, HA, Col IV, PCIII, LN, Hyp levels and reduce the pathological fibrotic lesion of liver tissue in model rats. A total of 195 DEPs were screened after LWPE intervention. GO analysis showed that the DEPs were related mostly to extracellular matrix organization, actin binding, and extracellular exosomes. KEGG pathway analysis showed that DEPs are mainly related to ECM-receptor interactions, focal adhesion and PI3K-Akt signaling pathway. Combined with the GO, KEGG and Western blot results, COL1A2, ITGAV, TLR2, ACE, and PDGFRB may be potential targets for PE treatment of liver fibrosis. In conclusion, LWPE exerts therapeutic effects through multiple pathways and multiple targets regulation in the treatment of liver fibrosis. This study may provide proteomics clues for the continuation of research on liver fibrosis treatment with PE.

Notoginsenoside R1, An Active Compound from Panax notoginseng, Inhibits Hepatic Stellate Cell Activation and Liver Fibrosis via MAPK Signaling Pathway

Activation of the hepatic stellate cell is implicated in pathological vascularization during development of liver fibrosis. MAPK signaling is involved in the activation of hepatic stellate cell. Oxidative stress and inflammation are also involved in the pathogenesis of liver fibrosis. Notoginsenoside R1 is an effective saponin isolated from the roots of Panax notoginseng (Burk) F. H. Chen and exerts anti-oxidant, anti-inflammatory and anti-fibrotic roles in various diseases. However, the role of Notoginsenoside R1 in liver fibrosis has not been investigated yet. First, a rat model with liver fibrosis was established through oral gavage administration with carbon tetrachloride. Data from hematoxylin and eosin (H&E) and Masson's trichrome stainings showed that carbon tetrachloride induced severe hepatic damages, including inflammatory cell infiltration, lipid droplets deposition in hepatocytes and liver centrilobular necrosis. Meanwhile, the rats were also intraperitoneal injected with different concentrations of Notoginsenoside R1. Results demonstrated that Notoginsenoside R1 treatment suppressed the pathological changes in the livers with enhanced levels of ALB and TP, and reduced levels of ALP, AST and ALT. Second, Notoginsenoside R1 also significantly attenuated carbon tetrachloride-induced decrease in PPAR-[Formula: see text] and increase in Coll-a1, [Formula: see text]-SMA and TIMP1 in liver tissues ([Formula: see text][Formula: see text] 0.001). Third, the decrease in GSH, SOD and GST and increase in MDA, IL-1[Formula: see text], IL-6 and TNF-[Formula: see text] induced by carbon tetrachloride were markedly restored by Notoginsenoside R1 ([Formula: see text][Formula: see text] 0.001). Lastly, Notoginsenoside R1 counteracted with the promotive effects of carbon tetrachloride on levels of proteins involved in MAPK signaling, including phosphorylated p65 (p-p65), p-ERK, p-JNK and p-p38. In conclusion, Notoginsenoside R1 suppressed the activation of hepatic stellate cells and exerted anti- oxidant and anti-inflammatory to attenuate carbon tetrachloride-induced liver fibrosis through inactivation of NF-[Formula: see text]B and MAPK signaling.

Hura crepitans stem bark extract: A potential remedy to sub-acute liver damage

ETHNOPHARMACOLOGICAL SIGNIFICANCE AND AIM

Hura crepitans is commonly used to treat liver diseases in Nigeria and Ghana. Previous studies have supported its ethnomedicinal use in protecting the liver. The present study aimed at assessing the effect of H. crepitans stem bark on the subacute carbon tetrachloride (CCl₄)-induced liver damage in rats.

MATERIALS AND METHODS

The protective activities of ethanolic extract of H. crepitans stem bark was evaluated in CCl₄-induced subacute liver damage in rats (1:1 v/v in olive oil, intraperitoneally (i.p.), twice weekly for 8 weeks). Blood samples were obtained from the rats and used for some biochemical analysis such as liver function test (Aspartate transaminase, AST; Alanine aminotransferase, ALT; and Alkaline phosphatase, ALP), liver fibrotic indices (Aspartate platelet ratio index, APRI; AST/ALT and AST/PLT ratios) and oxidative stress markers (Malondialdehyde, MDA; Reduced glutathione, GSH; Glutathione S-transferase, GST; Glutathione peroxidase, GPx; and superoxide dismutase, SOD). Histopathological analyses were carried out to determine the expression of pro-inflammatory (NF-κB, COX-2, IL-17 and IL-23) using immunohistochemical techniques.

RESULTS

Oral administration of H. crepitans to CCl₄-induced hepatic injured rats significantly decreased oxidative stress, increased the levels of SOD, GSH, GST and GPx with reduced MDA levels. The plant also mitigated liver injury as evidenced in the significantly reduced levels of AST, ALT and ALP, while it inhibited the inflammatory process via the inhibition of NF-κB, and consequently down-regulateed the pro-inflammatory cytokines COX-2, IL-17 and IL-23, respectively. Biochemical observations were supported by improvement in liver microarchitecture.

CONCLUSION

The Hura crepitans demonstrated antioxidant, antiinflammatory and antifibrotic effect in hepatic injured rats. The study in a way justifies the traditional use of the plant for the treatment of subacute liver diseases in Nigerian Traditional medicine.

Toll-like receptor 2 signaling in liver pathophysiology

Chronic liver diseases (CLD) are among the major cause of mortality and morbidity worldwide. Despite current achievements in the area of hepatitis virus, chronic alcohol abuse and high-fat diet are still fueling an epidemic of severe liver disease, for which, an effective therapy has yet not been discovered. In particular, the therapeutic regimens that could prevent the progression of fibrosis and, in turn, aid cirrhotic liver to develop a robust regenerative capability are intensively needed. To this context, a better understanding of the signaling pathways regulating hepatic disease development may be of critical value. In general, the liver responds to various insults with an orchestrated healing process involving variety of signaling pathways. One such pathway is the TLR2 signaling pathway, which essentially regulates adult liver pathogenesis and thus has emerged as an attractive target to treat liver disease. TLR2 is expressed by different liver cells, including Kupffer cells (KCs), hepatocytes, and hepatic stellate cells (HSCs). From a pathologic perspective, the crosstalk between antigens and TLR2 may preferentially trigger a distinctive set of signaling mechanisms in these liver cells and, thereby, induce the production of inflammatory and fibrogenic cytokines that can initiate and prolong liver inflammation, ultimately leading to fibrosis. In this review, we summarize the currently available evidence regarding the role of TLR2 signaling in hepatic disease progression. We first elaborate its pathological involvement in liver-disease states, such as inflammation, fibrosis, and cirrhosis. We then discuss how therapeutic targeting of this pathway may help to alleviate its disease-related functioning.

Quercetin as a protective agent for liver diseases: A comprehensive descriptive review of the molecular mechanism

Quercetin is the major representative of the flavonoid subgroup of flavones, with good pharmacological activities for the treatment of liver diseases, including liver steatosis, fatty hepatitis, liver fibrosis, and liver cancer. It can significantly influence the development of liver diseases via multiple targets and multiple pathways via antifat accumulation, anti-inflammatory, and antioxidant activity, as well as the inhibition of cellular apoptosis and proliferation. Despite extensive research on understanding the mechanism of quercetin in the treatment of liver diseases, there are still no targeted therapies available. Thus, we have comprehensively searched and summarized the different targets of quercetin in different stages of liver diseases and concluded that quercetin inhibited inflammation of the liver mainly through NF-κB/TLR/NLRP3, reduced PI3K/Nrf2-mediated oxidative stress, mTOR activation in autophagy, and inhibited the expression of apoptotic factors associated with the development of liver diseases. In addition, quercetin showed different mechanisms of action at different stages of liver diseases, including the regulation of PPAR, UCP, and PLIN2-related factors via brown fat activation in liver steatosis. The compound inhibited stromal ECM deposition at the liver fibrosis stage, affecting TGF1β, endoplasmic reticulum stress (ERs), and apoptosis. While at the final liver cancer stage, inhibiting cancer cell proliferation and spread via the hTERT, MEK1/ERK1/2, Notch, and Wnt/β-catenin-related signaling pathways. In conclusion, quercetin is an effective liver protectant. We hope to explore the pathogenesis of quercetin in different stages of liver diseases through the review, so as to provide more accurate targets and theoretical basis for further research of quercetin in the treatment of liver diseases.

Soluble resistance-related calcium-binding protein participates in multiple diseases via protein-protein interactions

Soluble resistance-related calcium-binding protein (sorcin), a 22 kDa penta-EF-hand protein, has been intensively studied in cancers and multidrug resistance over a prolonged period. Sorcin is widely distributed in tissues and participates in the regulation of Ca²⁺ homeostasis and Ca²⁺-dependent signaling. Protein-protein interactions (PPIs) are essential for regulating protein functions in almost all biological processes. Sorcin interaction partners tend to vary in type, including Ca²⁺ receptors, Ca²⁺ transporters, endoplasmic reticulum stress markers, transcriptional regulatory elements, immunomodulation-related factors, and viral proteins. Recent studies have shown that sorcin is involved in a broad range of pathological conditions, such as cardiomyopathy, type 2 diabetes mellitus, neurodegenerative diseases, liver diseases, and viral infections. As a multifunctional cellular protein, in these diseases, sorcin has a role by interacting with or regulating the expression of other proteins, such as sarcoplasmic reticulum/endoplasmic reticulum Ca²⁺ ATPase, ryanodine receptors, presenilin 2, L-type Ca²⁺ channels, carbohydrate-responsive element-binding protein, tau, α-synuclein, signal transducer and activator of transcription 3, HCV nonstructural 5A protein, and viral capsid protein 1. This review summarizes the roles that sorcin plays in various diseases, mainly via different PPIs, and focuses principally on non-neoplastic diseases to help acquire a more comprehensive understanding of sorcin's multifunctional characteristics.

A Novel Function of TLR2 and MyD88 in the Regulation of Leukocyte Cell Migration Behavior During Wounding in Zebrafish Larvae

Toll-like receptor (TLR) signaling via myeloid differentiation factor 88 protein (MyD88) has been indicated to be involved in the response to wounding. It remains unknown whether the putative role of MyD88 in wounding responses is due to a control of leukocyte cell migration. The aim of this study was to explore in vivo whether TLR2 and MyD88 are involved in modulating neutrophil and macrophage cell migration behavior upon zebrafish larval tail wounding. Live cell imaging of tail-wounded larvae was performed in tlr2 and myd88 mutants and their corresponding wild type siblings. In order to visualize cell migration following tissue damage, we constructed double transgenic lines with fluorescent markers for macrophages and neutrophils in all mutant and sibling zebrafish lines. Three days post fertilization (dpf), tail-wounded larvae were studied using confocal laser scanning microscopy (CLSM) to quantify the number of recruited cells at the wounding area. We found that in both tlr2^-/- and myd88^-/- groups the recruited neutrophil and macrophage numbers are decreased compared to their wild type sibling controls. Through analyses of neutrophil and macrophage migration patterns, we demonstrated that both tlr2 and myd88 control the migration direction of distant neutrophils upon wounding. Furthermore, in both the tlr2 and the myd88 mutants, macrophages migrated more slowly toward the wound edge. Taken together, our findings show that tlr2 and myd88 are involved in responses to tail wounding by regulating the behavior and speed of leukocyte migration in vivo.

5-O-Demethylnobiletin Alleviates CCl4-Induced Acute Liver Injury by Equilibrating ROS-Mediated Apoptosis and Autophagy Induction

Polymethoxyflavanoids (PMFs) have exhibited a vast array of therapeutic biological properties. 5-O-Demethylnobiletin (5-DN) is one such PMF having anti-inflammatory activity, yet its role in hepatoprotection has not been studied before. Results from in vitro study revealed that 5-DN did not exert a high level of cytotoxicity on HepG2 cells at 40 μM, and it was able to rescue HepG2 cell death induced by carbon tetrachloride (CCl₄). Subsequently, we investigated acute liver injury on BALB/c mice induced by CCl₄ through the intraperitoneal injection of 1 mL/kg CCl₄ and co-administration of 5-DN at (1 and 2 mg/kg) by oral gavage for 15 days. The results illustrated that treatment with 5-DN attenuated CCl₄-induced elevated serum aminotransferase (AST)/alanine aminotransferase (ALT) ratio and significantly ameliorated severe hepatic damage such as inflammation and fibrosis evidenced through lesser aberrations in the liver histology of 5-DN dose groups. Additionally, 5-DN efficiently counteracted and equilibrated the production of ROS accelerated by CCl₄ and dramatically downregulated the expression of CYP2E1 vitally involved in converting CCl₄ to toxic free radicals and also enhanced the antioxidant enzymes. 5-DN treatment also inhibited cell proliferation and inflammatory pathway abnormally regulated by CCl₄ treatment. Furthermore, the apoptotic response induced by CCl₄ treatment was remarkably reduced by enhanced Bcl-2 expression and noticeable reduction in Bax, Bid, cleaved caspase 3, caspase 9, and apaf-1 expression. 5-DN treatment also induced the conversion of LC3 and promoted the autophagic flux. Conclusively, 5-DN exhibited hepatoprotective effects in vitro and in vivo and prevented liver fibrosis induced by CCl₄.

Goji berry (Lycium spp.) extracts exhibit antiproliferative activity via modulating cell cycle arrest, cell apoptosis, and the p53 signaling pathway

The phytochemical profiles, antioxidant activity and antiproliferative mechanism of two goji berry varieties were investigated in the present study. In contrast to Lycium barbarum L. (LB), Lycium ruthenicum Murr. (LRM) showed stronger antioxidant activity evaluated by ORAC, PSC and CAA assays, which might be attributed to its higher total phenolics and total flavonoids. However, LB contains greater contents of VE and carotenoids compared to LRM, which may endow LB with other unique functions instead of antioxidant activity. Additionally, high dose LRM showed a stronger capability in terms of cell cycle arrest and cell apoptosis induction of MDA cells with increments of 17.85% cells blocked at the G1 phase and 50.49% cells achieving early apoptosis compared with the control group. Although supplementation with LB increased the number of cells in the G1 phase by 10%, its effect on inducing cell apoptosis was not ideal. Furthermore, both LRM and LB activated the proliferation-related p53 signaling pathway including p53, p21, CDK4, Cyclin E, Bax and Caspase3, but LB failed to downregulate bcl-2 and CDK2 levels, indicating the weaker antiproliferative effect of LB. The present findings indicated LRM and LB as potential candidates for managing the proliferation of cancer cells and improving human health.

Metabolic inflammation as an instigator of fibrosis during non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive storage of fatty acids in the form of triglycerides in hepatocytes. It is most prevalent in western countries and includes a wide range of clinical and histopathological findings, namely from simple steatosis to steatohepatitis and fibrosis, which may lead to cirrhosis and hepatocellular cancer. The key event for the transition from steatosis to fibrosis is the activation of quiescent hepatic stellate cells (qHSC) and their differentiation to myofibroblasts. Pattern recognition receptors (PRRs), expressed by a plethora of immune cells, serve as essential components of the innate immune system whose function is to stimulate phagocytosis and mediate inflammation upon binding to them of various molecules released from damaged, apoptotic and necrotic cells. The activation of PRRs on hepatocytes, Kupffer cells, the resident macrophages of the liver, and other immune cells results in the production of proinflammatory cytokines and chemokines, as well as profibrotic factors in the liver microenvironment leading to qHSC activation and subsequent fibrogenesis. Thus, elucidation of the inflammatory pathways associated with the pathogenesis and progression of NAFLD may lead to a better understanding of its pathophysiology and new therapeutic approaches.

Anti-toll-like receptor 2 antibody ameliorates hepatic injury, inflammation, fibrosis and steatosis in obesity-related metabolic disorder rats via regulating MAPK and NF-κB pathways

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide, which includes a spectrum of histological liver changes. Non-alcoholic steatohepatitis (NASH) is considered to be the progressive subtype of NAFLD, which is characterized by lobular inflammation and cellular ballooning on the basis of steatosis. There is a critical need to develop novel and effective therapeutic approaches for NAFLD/NASH. The activation of toll-like receptor 2 (TLR2) signaling pathway plays a key role in high-fat-related inflammation, triggering the occurrence and development of NASH. Herein, the anti-TLR2 monoclonal antibody (TLR2 mAb) was prepared and investigated for its ability to ameliorate the inflammatory response in vivo and in vitro. The anti-inflammatory role of TLR2 mAb in vitro was examined in NR8383 macrophage cells and THP-1 derived macrophage cells. For confirmation in vivo, three groups of SD rats were treated for 20 weeks: rats in the control were fed with a standard diet; rates in the IgG and TLR2 mAb groups were fed with a high-fat diet and with IgG or TLR2 mAb, respectively. Liver tissue and serum were collected for further analysis. Results showed that after 4-week treatment with TLR2 mAb, metabolic parameters in rats were improved markedly (body weight, fasting blood glucose level, liver steatosis, inflammatory response and fibrosis). Moreover, western blotting demonstrated that the TLR2 mAb blocked MAPKs and NF-κB activation, and inhibited the expression of inflammatory factors in rat liver tissue. These effects suggested that TLR2 mAb could improve HFD-induced hepatic injury, inflammation, fibrosis and steatosis by suppressing inflammatory response and regulating the hepatic MAPKs and NF-κB signaling pathways. This suggests that TLR2 may be a novel therapeutic target for metabolic diseases especially NASH.

The Role of Gut-Derived Microbial Antigens on Liver Fibrosis Initiation and Progression

Intestinal dysbiosis has recently become known as an important driver of gastrointestinal and liver disease. It remains poorly understood, however, how gastrointestinal microbes bypass the intestinal mucosa and enter systemic circulation to enact an inflammatory immune response. In the context of chronic liver disease (CLD), insults that drive hepatic inflammation and fibrogenesis (alcohol, fat) can drastically increase intestinal permeability, hence flooding the liver with gut-derived microbiota. Consequently, this may result in exacerbated liver inflammation and fibrosis through activation of liver-resident Kupffer and stellate cells by bacterial, viral, and fungal antigens transported to the liver via the portal vein. This review summarizes the current understanding of microbial translocation in CLD, the cell-specific hepatic response to intestinal antigens, and how this drives the development and progression of hepatic inflammation and fibrosis. Further, we reviewed current and future therapies targeting intestinal permeability and the associated, potentially harmful anti-microbial immune response with respect to their potential in terms of limiting the development and progression of liver fibrosis and end-stage cirrhosis.

The ameliorations of Ganoderma applanatum residue polysaccharides against CCl4 induced liver injury

This work investigated the protective effects of Ganoderma applanatum residue polysaccharides (GRP) on the CCl₄-induced hepatotoxicity. The results indicated that GRP showed significantly effects on preventing the increase of AST, ALT and ALP levels in serum, elevating the activities of SOD, GSH-Px and CAT, decreasing the contents of MDA and LPO, and reducing the CYP2E1 and TGF-β concentrations in CCl₄-induced mice, respectively. Meanwhile, the levels of TNF-α and IL-6 were significantly decreased, while the value of IL-10 was increased by GRP treatment. Besides, the western blot assay showed the IκBα expressions were significantly increased and the p-p65 was decreased by the treatment with GRP. The characterizations indicated that the GRP was heteropolysaccharide with lower molecular weights and α-furanoside residues. These results demonstrated that GRP might be a potential material for drug and functional food development against chemical hepatic injury.

Mmu-miR-92a-2-5p targets TLR2 to relieve Schistosoma japonicum-induced liver fibrosis

According to conservative estimates, >230 million people are infected with schistosomiasis,which becomes one of the most common parasitic diseases. This study focuses on investigating in vivo and in vitro effects of mmu-miR-92a-2-5p in Schistosoma japonicum-induced liver fibrosis by targeting TLR2. Through bioinformatic analysis, the overexpression of TLR2 and the down-regulation of mmu-miR-92a-2-5p were revealed in the progression of S. japonicum-induced liver fibrosis. BALB/C mice were taken advantage to construct normal control and schistosomiasis liver fibrosis (SLF) model. The mice in model groups were transfected recombinant lentivirus (Lenti-mmu-miR-92a-2-5p or Lenti-NC) to alter the expression of mmu-miR-92a-2-5p in vivo. HE and Masson staining were employed to observe the pathological changes and collagenous fibrosis. QRT-PCR showed that mmu-miR-92a-2-5p was decreased while TLR2 was elevated in the infected groups. However, lenti-mmu-miR-92a-2-5p group could inhibit liver fibrosis. Then the effect of mmu-miR-92a-2-5p on S. japonicum-induced liver fibrosis including cell apoptosis rates, proliferation and proteins related to liver fibrosis was examined in NIH-3T3 mouse embryonic fibroblasts. Moreover, the association between mmu-miR-92a-2-5p and TLR2 was detected by dual-luciferase reporter gene assay and the expression of cytokines IL-4, IFN-γ and TNF-α in SLF model was detected by ELISA. Further, the knockout of TLR2 in C57BL/6J mice was used to confirm the association between mmu-miR-92a-2-5p and TLR2. Thus, these findings demonstrated that mmu-miR-92a-2-5p inhibited S. japonicum-induced liver fibrosis by targeting TLR2 in vitro and in vivo.

AICAR-Induced AMPK Activation Inhibits the Noncanonical NF-κB Pathway to Attenuate Liver Injury and Fibrosis in BDL Rats

BACKGROUND

To evaluate the AMP-activated protein kinase- (AMPK-) mediated signaling and NF-κB-related inflammatory pathways that contribute to cholestatic diseases in the bile duct ligation (BDL) rat model of chronic cholestasis and verify the protective role of 5-Aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR) against hepatic injury and fibrosis triggered by cholestasis-related inflammation.

METHODS

Animals were randomly divided into three groups: sham-operated group, BDL group, and BDL+ AICAR group. Cholestatic liver injury was induced by common BDL. Two weeks later, rats in BDL+AICAR group started receiving AICAR treatment. Hepatic pathology was examined by haematoxylin and eosin (H&E) and sirius red staining and hydroxyproline assay was performed in evaluating the severity of hepatic cirrhosis. Real-time PCR and Western blot were performed for RNA gene expression of RNA and protein levels, respectively.

RESULTS

The BDL group showed liver injury as evidenced by histological changes and elevation in serum biochemicals, ductular reaction, fibrosis, and inflammation. The mRNA expression of canonical NF-κB inflammatory cytokines such as TNF-α, IL-1β, TGF-β, and the protein of noncanonical NF-κB, P100, and P52 was upregulated in the livers of BDL rats. The BDL rats with the administration of AICAR could induce AMPK activation inhibiting the noncanonical NF-κB pathway to attenuate liver injury and fibrosis in BDL rats.

CONCLUSION

The BDL model of hepatic cholestatic injury resulting in activation of Kupffer cells and recruitment of immune cells might initiate an inflammatory response through activation of the NF-κB pathway. The AMPK activator AICAR significantly alleviated BDL-induced inflammation in rats by mainly inhibiting the noncanonical NF-κB pathway and thus protecting against hepatic injury and fibrosis triggered by BDL.

The Role of miR-29a in the Regulation, Function, and Signaling of Liver Fibrosis

Both fibrosis and cirrhosis of the liver are the end results of most kinds of chronic liver damage and represent a common but difficult clinical challenge throughout the world. The inhibition of the fibrogenic, proliferative, and migratory effects of hepatic stellate cells (HSCs) has become an experimental therapy for preventing and even reversing hepatic fibrosis. Furthermore, a complete understanding of the function of non-coding RNA-mediated epigenetic mechanisms in HSC activation may improve our perception of liver fibrosis pathogenesis. This review focuses on the evolving view of the molecular mechanisms by which HSC activation by miR-29a signaling may moderate the profibrogenic phenotype of these cells, thus supporting the use of miR-29a agonists as a potential therapy for treating liver fibrosis in the future.

Fisetin-treatment alleviates airway inflammation through inhbition of MyD88/NF-κB signaling pathway

Asthma is a common chronic airway inflammation disease and is considered as a major public health problem. Fisetin (3,3′,4′,7-tetrahydroxyflavone) is a naturally occurring flavonoid abundantly found in different vegetables and fruits. Fisetin has been reported to exhibit various positive biological effects, including anti-proliferative, anticancer, anti-oxidative and neuroprotective effects. We evaluated the effects of fisetin on allergic asthma regulation in mice. Mice were first sensi-tized, then airway-challenged with ovalbumin (OVA). Whether fisetin treatment attenuated OVA-induced airway inflammation was examined via inflammation inhibition through MyD88-related NF-κB (p65) signaling pathway. Mice were divided into the control (Con), OVA-induced asthma (Mod), 40 (FL) and 50 (FH) mg/kg fisetin-treated OVA-induced asthma groups. Our results found that OVA-induced airway inflammation in mice caused a significant inflammatory response via the activation of MyD88 and NF-κB signaling pathways, leading to release of pro-inflammatory cytokines. In contrast, fisetin-treated mice after OVA induction inhibited activation of MyD88 and NF-κB signaling pathways, resulting in downregulation of pro-inflammatory cytokine secretion. Further, fisetin significantly ameliorated the airway hyperresponsiveness (AHR) towards methacholine (Mch). In addition, fisetin reduced the number of eosinophil, monocyte, neutrophil and total white blood cell in the bronchoalveolar lavage fluid (BALF) of OVA-induced mice. The serum and BALF samples obtained from the OVA-induced mice with fisetin showed lower levels of pro-inflammatory cytokines. The results of our study illustrated that fisetin may be a new promising candidate to inhibit airway inflammation response induced by OVA.

MicroRNA-29a mitigation of toll-like receptor 2 and 4 signaling and alleviation of obstructive jaundice-induced fibrosis in mice

Cholestasis and hepatitis can cause continuous liver damage that may ultimately result in liver fibrosis. In a previous study, we demonstrated that microRNA-29a (miR-29a) protects against liver fibrosis. Toll-like receptor 2 (TLR2) and TLR4 are pattern recognition receptors of bacterial lipoprotein and lipopolysaccharide, both of which participate in activating hepatic stellate cells and liver fibrosis. The purpose of this study is to characterize the biological influence of miR-29a on TLR2 and TLR4 signaling in livers injured with bile duct ligation (BDL). We performed BDL on both miR-29a transgenic mice (miR-29aTg) and wild-type mice to induce cholestatic liver injury. Primary HSCs were transfected with a miR-29a mimic and inhibitor. In the wild-type mice, the BDL demonstrated significant α-smooth muscle actin fibrotic matrix formation and hepatic high mobility group box-1 expression. However, in the miR-29aTg mice, these factors were significantly reduced. Furthermore, miR-29a overexpression reduced the BDL exaggeration of TLR2, TLR4, MyD88, bromodomain-containing protein 4 (BRD4), phospho-p65 as well as proinflammatory cytokines, IL-1β, MCP-1, TGF-β, and TNF-α. In vitro, miR-29a mimic transfection reduced α-SMA, BRD4,TLR2, and TLR4 expressions in HSCs. This study provides new molecular insight into the ability of miR-29a to inhibit TLR2 and TLR4 signaling, which thus slows the progression of cholestatic liver deterioration.

Lycium barbarum polysaccharides improve CCl4-induced liver fibrosis, inflammatory response and TLRs/NF-kB signaling pathway expression in wistar rats

Lycium barbarum polysaccharides (LBPs) have multiple biological and pharmacological functions, including antioxidant, anti-inflammatory and anticancer activities. This research was conducted to evaluate whether LBPs could alleviate carbon tetrachloride (CCl₄)-induced liver fibrosis and the underlying signaling pathway mechanism. Fifty male wistar rats were randomly allocated to five groups (n=10): control, CCl₄ and CCl₄ with 400, 800 or 1600mg/kg LBPs, respectively. Each wistar rat from each group was used for blood and tissue collections at the end of experiment. The results showed that CCl₄ induced liver fibrosis as demonstrated by increasing histopathological damage, α-smooth muscle actin expression, aspartate transaminase activities, alkaline phosphatase activities and alanine aminotransferase activities. LBPs supplementation alleviated CCl₄-induced liver fibrosis as demonstrated by reversing the above parameters. In addition, CCl₄ treatment induced the oxidative injury, increased the mRNA levels of tumor necrosis factor-α, monocyte chemoattractant protein-1 and interleukin-1β, and up-regulated the protein expressions of toll-like receptor 4 (TLR4), TLR2, myeloid differentiation factor 88, nuclear factor-kappa B (NF-kB) and p-p65. LBPs supplementation alleviated CCl₄-induced oxidative injury, inflammatory response and TLRs/NF-kB signaling pathway expression by reversing the above some parameters. These results suggest that the alleviating effects of LBPs on CCl₄-induced liver fibrosis in wistar rats may be through inhibiting the TLRs/NF-kB signaling pathway expression.

Smurf2, an E3 ubiquitin ligase, interacts with PDE4B and attenuates liver fibrosis through miR-132 mediated CTGF inhibition

We previously reported that Smad ubiquitin regulatory factor 2 (Smurf2) activity was decreased in human fibrotic livers. Here, we overexpressed Smurf2 in livers of transgenic mice and observed inhibited collagen deposition and hepatic stellate cell activation in fibrotic model induced by carbon tetrachloride treatment or bile duct ligation. Hepatic Smurf2 overexpression also inhibited the production of connective tissue growth factor (CTGF), a central mediator of liver fibrosis. Using miRNA array and bioinformatics analyses, we identified miR-132 as a mediator of this inhibitory effect. miR-132 directly targets the 3'-untranslated region of CTGF and was transcriptionally upregulated by cAMP-PKA-CREB signaling. In addition, Smurf2 activated cAMP-PKA-CREB pathway by interacting with phosphodiesterase 4B (PDE4B) and facilitating its degradation. Thus, we have demonstrated a previously unrecognized anti-fibrotic pathway controlled by Smurf2.

Toll-like receptors in pathophysiology of liver diseases

Toll-like receptors (TLRs) are pattern recognition receptors that participate in host defense by recognizing pathogen-associated molecular patterns alongside inflammatory processes by recognizing damage associated molecular patterns. Given constant exposure to pathogens from gut, strict control of TLR-associated signaling pathways is essential in the liver, which otherwise may lead to inappropriate production of pro-inflammatory cytokines and interferons and may generate a predisposition to several autoimmune and chronic inflammatory diseases. The liver is considered to be a site of tolerance induction rather than immunity induction, with specificity in hepatic cell functions and distribution of TLR. Recent data emphasize significant contribution of TLR signaling in chronic liver diseases via complex immune responses mediating hepatocyte (i.e., hepatocellular injury and regeneration) or hepatic stellate cell (i.e., fibrosis and cirrhosis) inflammatory or immune pathologies. Herein, we review the available data on TLR signaling, hepatic expression of TLRs and associated ligands, as well as the contribution of TLRs to the pathophysiology of hepatic diseases.

MicroRNA Expression Profiling in CCl₄-Induced Liver Fibrosis of Mus musculus

Liver fibrosis is a major pathological feature of chronic liver diseases, including liver cancer. MicroRNAs (miRNAs), small noncoding RNAs, regulate gene expression posttranscriptionally and play important roles in various kinds of diseases; however, miRNA-associated hepatic fibrogenesis and its acting mechanisms are poorly investigated. Therefore, we performed an miRNA microarray in the fibrotic livers of Mus musculus treated with carbon-tetrachloride (CCl₄) and analyzed the biological functions engaged by the target genes of differentially-expressed miRNAs through gene ontology (GO) and in-depth pathway enrichment analysis. Herein, we found that four miRNAs were upregulated and four miRNAs were downregulated more than two-fold in CCl₄-treated livers compared to a control liver. Eight miRNAs were predicted to target a total of 4079 genes. GO analysis revealed that those target genes were located in various cellular compartments, including cytoplasm, nucleolus and cell surface, and they were involved in protein-protein or protein-DNA bindings, which influence the signal transductions and gene transcription. Furthermore, pathway enrichment analysis demonstrated that the 72 subspecialized signaling pathways were associated with CCl₄-induced liver fibrosis and were mostly classified into metabolic function-related pathways. These results suggest that CCl₄ induces liver fibrosis by disrupting the metabolic pathways. In conclusion, we presented several miRNAs and their biological processes that might be important in the progression of liver fibrosis; these findings help increase the understanding of liver fibrogenesis and provide novel ideas for further studies of the role of miRNAs in liver fibrosis.

Carnosic acid nanoparticles suppress liver ischemia/reperfusion injury by inhibition of ROS, Caspases and NF-κB signaling pathway in mice

Living donor liver transplantation (LDLT) requires ischemia/reperfusion (I/R), which can lead to early graft injury. However, the detailed molecular mechanism of I/R injury remains unclear. Carnosic acid, as a phenolic diterpene with function of anti-inflammation, anti-cancer, anti-bacterial, anti-diabetic, as well as neuroprotective properties, is produced by many species from Lamiaceae family. Nanoparticulate drug delivery systems have been known to better the bioavailability of drugs on intranasal administration compared with only drug solutions. Administration of carnosic acid nanoparticles was thought to be sufficient to lead to considerable inhibition of liver injury progression induced by ischemia/reperfusion. In our study, liver ischemia/reperfusion injury was established successfully with C57BL/6 animal model. 10 and 20mg/kg carnosic acid nanoparticles were injected to mice for five days prior to ischemia. After liver ischemia/reperfusion, the levels of serum AST, ALT and APL were increased, which was attenuated by pre-treatment with carnosic acid nanoparticles. In addition, carnosic acid nanoparticles inhibited ROS production via its related signals regulation. And carnosic acid nanoparticles also suppressed the ischemia/reperfusion-induced up-regulation in the pro-apoptotic protein and mRNA levels of Bax, Cyto-c, Apaf-1 and Caspase-9/3 while increased ischemia/reperfusion-induced decrease of anti-apoptotic factor of Bcl-2. Further, ischemia/reperfusion-induced inflammation was also inhibited for carnosic acid nanoparticles administration via inactivating NF-κB signaling pathway, leading to down-regulation of pro-inflammatory cytokines releasing. In conclusion, our study suggested that carnosic acid nanoparticles protected against liver ischemia/reperfusion injury via its role of anti-oxidative, anti-apoptotic and anti-inflammatory bioactivity.

Inhibition of MAPK and NF-κB signaling pathways alleviate carbon tetrachloride (CCl4)-induced liver fibrosis in Toll-like receptor 5 (TLR5) deficiency mice

Current researches showed that TLR family plays an important role in liver fibrosis, yet the molecular mechanism by which this occurs is not fully explained. In this study, we investigated the role of TLR5 in carbon tetrachloride-induced liver fibrosis, and further examined wether TLR5 knockout attenuated tetrachloride-induced liver fibrosis by inhibiting hepatic stellate cells activation via modulating NF-κB and MAPK signaling pathways. Our results found that carbon tetrachloride induced liver function injury in WT mice with a inflammatory responses through the activation of NF-κB and MAPK signaling pathways, resulting in hepatic stellate cells activation. In contrast, TLR5 deficiency mice after carbon tetrachloride administration reduced NF-κB and MAPK signaling pathways activation, which down regulated hepatic stellate cells activation. In addition, alpha smooth muscle-actin as marker of hepatic stellate cells further indicated that TLR5 knockout mice have a lower collagen accumulation in liver tissue than WT mice after carbon tetrachloride administration, resulting in inhibition of NF-κB and MAPK signaling pathways activation. Moreover, in vitro experiment of hepatic stellate cells challenged with LPS or TGF-β, further indicated that NF-κB and MAPK were involved in liver fibrosis development, leading to α-SMA expression and inflammation infiltration. However, cells from TLR5(-)(/-) may weaken phosphorylation levels of signal pathways, finally suppress progress of collagen accumulation and inflammatory responses. These results suggest a new therapeutic approach or target to protect against fibrosis caused by chronic liver diseases.

Combination of sorafenib and gadolinium chloride (GdCl3) attenuates dimethylnitrosamine(DMN)-induced liver fibrosis in rats

BACKGROUND/AIMS

Liver sinusoidal endothelial cells (SECs), hepatic stellate cells (HSCs) and Kupffer cells (KCs) are involved in the development of liver fibrosis and represent a potential therapeutic target. The therapeutic effects on liver fibrosis of sorafenib, a multiple tyrosine kinase inhibitor, and gadolinium chloride (GdCl3), which depletes KCs, were evaluated in rats.

METHODS

Liver fibrosis was induced in rats with dimethylnitrosamine, and the effects of sorafenib and/or GdCl3 in these rats were monitored. Interactions among ECs, HSCs and KCs were assessed by laser confocal microscopy.

RESULTS

The combination of sorafenib and GdCl3, but not each agent alone, attenuated liver fibrosis and significantly reduced liver function and hydroxyproline (Hyp). Sorafenib significantly inhibited the expression of angiogenesis-associated cell markers and cytokines, including CD31, von Willebrand factor (vWF), and vascular endothelial growth factor, whereas GdCl3 suppressed macrophage-related cell markers and cytokines, including CD68, tumor necrosis factor-α, interleukin-1β, and CCL2. Laser confocal microscopy showed that sorafenib inhibited vWF expression and GdCl3 reduced CD68 staining. Sorafenib plus GdCl3 suppressed the interactions of HSCs, ECs and KCs.

CONCLUSION

Sorafenib plus GdCl3 can suppress collagen accumulation, suggesting that this combination may be a potential therapeutic strategy in the treatment of liver fibrosis.

Melatonin attenuates carbon tetrachloride-induced liver fibrosis via inhibition of necroptosis

We investigated the protective mechanisms of melatonin (MLT) associated with necroptosis signaling and damage-associated molecular patterns, which are mediated by the activation of pattern recognition receptors in liver fibrosis. Rats were given an intraperitoneal injection of carbon tetrachloride (CCl4) dissolved in olive oil (1:3, vol/vol) twice a week (0.5 mL/kg) for 8 weeks. During this period, MLT was administered orally at 2.5, 5, and 10 mg/kg once a day. Chronic CCl4 administration increased hepatic hydroxyproline content and hepatocellular damage. MLT attenuated these increases. The expression levels of transforming growth factor β1 and α-smooth muscle actin that were increased by chronic CCl4 exposure were attenuated by MLT. CCl4 significantly increased receptor-interacting protein 1 (RIP1) expression, the formation of the RIP1 and RIP3 necrosome complex, and the level of mixed lineage kinase domain-like protein in liver tissue, which were attenuated by MLT. MLT also attenuated CCl4-induced increases in serum high-mobility group box 1 (HMGB1) and interleukin 1α, as well as the interaction between HMGB1 receptors for advanced glycation end products (RAGE). The increases in toll-like receptor 4 expression, p38, c-Jun N-terminal kinases phosphorylation, and nuclear factor κB translocation were suppressed by MLT. MLT attenuated the overexpression of RAGE, increased level of early growth response protein 1, and increased messenger RNA level of macrophage inflammatory protein 2. Our findings suggest MLT may prevent liver fibrosis by inhibiting necroptosis-associated inflammatory signaling.

Givinostat inhibition of hepatic stellate cell proliferation and protein acetylation

AIM: To explore the effect of the histone deacetylase inhibitor givinostat on proteins related to regulation of hepatic stellate cell proliferation.

METHODS: The cell counting kit-8 assay and flow cytometry were used to observe changes in proliferation, apoptosis, and cell cycle in hepatic stellate cells treated with givinostat. Western blot was used to observe expression changes in p21, p57, CDK4, CDK6, cyclinD1, caspase-3, and caspase-9 in hepatic stellate cells exposed to givinostat. The scratch assay was used to analyze the effect of givinostat on cell migration. Effects of givinostat on the reactive oxygen species profile, mitochondrial membrane potential, and mitochondrial permeability transition pore opening in JS-1 cells were observed by laser confocal microscopy.

RESULTS: Givinostat significantly inhibited JS-1 cell proliferation and promoted cell apoptosis, leading to cell cycle arrest in G0/G1 phases. Treatment with givinostat downregulated protein expression of CDK4, CDK6, and cyclin D1, whereas expression of p21 and p57 was significantly increased. The givinostat-induced apoptosis of hepatic stellate cells was mainly mediated through p38 and extracellular signal-regulated kinase 1/2. Givinostat treatment increased intracellular reactive oxygen species production, decreased mitochondrial membrane potential, and promoted mitochondrial permeability transition pore opening. Acetylation of superoxide dismutase (acetyl K68) and nuclear factor-κB p65 (acetyl K310) was upregulated, while there was no change in protein expression. Moreover, the notable beneficial effect of givinostat on liver fibrosis was also confirmed in the mouse models.

CONCLUSION: Givinostat has antifibrotic activities via regulating the acetylation of nuclear factor-κB and superoxide dismutase 2, thus inhibiting hepatic stellate cell proliferation and inducing apoptosis.

Xia-yu-xue decoction (XYXD) reduces carbon tetrachloride (CCl4)-induced liver fibrosis through inhibition hepatic stellate cell activation by targeting NF-κB and TGF-β1 signaling pathways

Background

Hepatic stellate cell (HSC) activation is activated mainly by endotoxin and transforming growth factor (TGF-β1) in chronic liver injury, consequently, can be important therapeutic targets. Xia-yu-xue decoction (XYXD), a classical recipe used in China to treat liver fibrosis, and has been revealed to inhibit hepatic fibrosis in animal models, the mechanism of action of XYXD remains elusive. In the present study, we evaluated whether XYXD reduced endotoxin and pro-fibrogenic pathways induced by lipopolysaccharide (LPS) and TGF-β1 in HSCs.

Methods

The in vivo effect of XYXD on fibrosis progression was assessed in mice model induced by carbon tetrachloride (CCl₄), The in vitro effect of XYXD on mice GFP-Col-HSC cells was evaluated using LPS and TGF-β1 stimulation.

Results

XYXD treatment reduced CCl₄-induced liver fibrosis and decreased hepatic hydroxyproline (Hyp) content, the mRNA levels of smooth muscle actin (α-SMA) and Col 1(α1) in fibrotic liver. XYXD suppressed nuclear factor-κB (NF-κB) activation induced by LPS and TGF-β1 assessed by using NF-κB-luciferase reporter. The expression of NF-κB target genes, chemokine (C-C motif) ligand 2 (CCL2) and chemokine (C-X-C motif) ligand 2 (CXCL2) induced by LPS was suppressed after XYXD treatment. The expression of TGF-β1 targets genes, Col1(α1) and tissue inhibitor of metalloproteinases (TIMP1) induced by TGF-β1 was inhibit after XYXD treatment.

Conclusion

XYXD treatment attenuates liver fibrosis by inhibiting HSC activation via inhibition of NF-κB and TGF-β1 signaling pathway, thereby blocking the synthesis of Col1 (α1) and TIMP-1. These findings from present study suggest that XYXD may be a therapeutic decoction for liver fibrosis in which NF-κB and TGF-β1 are thought to take part.

A Novel Matrine Derivative WM130 Inhibits Activation of Hepatic Stellate Cells and Attenuates Dimethylnitrosamine-Induced Liver Fibrosis in Rats

Activation of hepatic stellate cells (HSCs) is a critical event in process of hepatic fibrogenesis and cirrhosis. Matrine, the active ingredient of Sophora, had been used for clinical treatment of acute/chronic liver disease. However, its potency was low. We prepared a high potency and low toxicity matrine derivate, WM130 (C30N4H40SO5F), which exhibited better pharmacological activities on antihepatic fibrosis. This study demonstrated that WM130 results in a decreased proliferative activity of HSC-T6 cells, with the half inhibitory concentration (IC50) of 68 μM. WM130 can inhibit the migration and induce apoptosis in HSC-T6 cells at both concentrations of 68 μM (IC50) and 34 μM (half IC50). The expression of α-SMA, Collagen I, Collagen III, and TGF-β1 could be downregulated, and the protein phosphorylation levels of EGFR, AKT, ERK, Smad, and Raf (p-EGFR, p-AKT, p-ERK, p-Smad, and p-Raf) were also decreased by WM130. On the DMN-induced rat liver fibrosis model, WM130 can effectively reduce the TGF-β1, AKT, α-SMA, and p-ERK levels, decrease the extracellular matrix (ECM) formation, and inhibit rat liver fibrosis progression. In conclusion, this study demonstrated that WM130 can significantly inhibit the activation of HSC-T6 cells and block the rat liver fibrosis progression by inducing apoptosis, suppressing the deposition of ECM, and inhibiting TGF-β/Smad and Ras/ERK pathways.

Reversibility and heritability of liver fibrosis: Implications for research and therapy

Liver fibrosis continues to be a major health problem worldwide due to lack of effective therapy. If the etiology cannot be eliminated, liver fibrosis progresses to cirrhosis and eventually to liver failure or malignancy; both are associated with a fatal outcome. Liver transplantation, the only curative therapy, is still mostly unavailable. Liver fibrosis was shown to be a reversible process; however, complete reversibility remains debatable. Recently, the molecular markers of liver fibrosis were shown to be transmitted across generations. Epigenetic mechanisms including DNA methylation, histone posttranslational modifications and noncoding RNA have emerged as major determinants of gene expression during liver fibrogenesis and carcinogenesis. Furthermore, epigenetic mechanisms have been shown to be transmitted through mitosis and meiosis to daughter cells and subsequent generations. However, the exact epigenetic regulation of complete liver fibrosis resolution and inheritance has not been fully elucidated. This communication will highlight the recent advances in the search for delineating the mechanisms governing resolution of liver fibrosis and the potential for multigenerational and transgenerational transmission of fibrosis markers. The fact that epigenetic changes, unlike genetic mutations, are reversible and can be modulated pharmacologically underscores the unique opportunity to develop effective therapy to completely reverse liver fibrosis, to prevent the development of malignancy and to regulate heritability of fibrosis phenotype.

Cellular and molecular functions of hepatic stellate cells in inflammatory responses and liver immunology

The liver is a central immunological organ. Liver resident macrophages, Kupffer cells (KC), but also sinusoidal endothelial cells, dendritic cells (DC) and other immune cells are involved in balancing immunity and tolerance against pathogens, commensals or food antigens. Hepatic stellate cells (HSCs) have been primarily characterized as the main effector cells in liver fibrosis, due to their capacity to transdifferentiate into collagen-producing myofibroblasts (MFB). More recent studies elucidated the fundamental role of HSC in liver immunology. HSC are not only the major storage site for dietary vitamin A (Vit A) (retinol, retinoic acid), which is essential for proper function of the immune system. This pericyte further represents a versatile source of many soluble immunological active factors including cytokines [e.g., interleukin 17 (IL-17)] and chemokines [C-C motif chemokine (ligand) 2 (CCL2)], may act as an antigen presenting cell (APC), and has autophagy activity. Additionally, it responds to many immunological triggers via toll-like receptors (TLR) (e.g., TLR4, TLR9) and transduces signals through pathways and mediators traditionally found in immune cells, including the Hedgehog (Hh) pathway or inflammasome activation. Overall, HSC promote rather immune-suppressive responses in homeostasis, like induction of regulatory T cells (Treg), T cell apoptosis (via B7-H1, PDL-1) or inhibition of cytotoxic CD8 T cells. In conditions of liver injury, HSC are important sensors of altered tissue integrity and initiators of innate immune cell activation. Vice versa, several immune cell subtypes interact directly or via soluble mediators with HSC. Such interactions include the mutual activation of HSC (towards MFB) and macrophages or pro-apoptotic signals from natural killer (NK), natural killer T (NKT) and gamma-delta T cells (γδ T-cells) on activated HSC. Current directions of research investigate the immune-modulating functions of HSC in the environment of liver tumors, cellular heterogeneity or interactions promoting HSC deactivation during resolution of liver fibrosis. Understanding the role of HSC as central regulators of liver immunology may lead to novel therapeutic strategies for chronic liver diseases.