Heme oxygenase-1 prevents liver fibrosis in rats by regulating the expression of PPARγ and NF-κB

Hemin attenuates bleomycin-induced lung fibrosis in mice by regulating the TGF-β1/MAPK and AMPK/SIRT1/PGC-1α/HO-1/NF-κB pathways

The objective of this study was to investigate the protective effect and potential mechanism of action of hemin on bleomycin-induced pulmonary fibrosis in mice. Male C57BL/6 mice were randomly divided into control, bleomycin and bleomycin + hemin groups. Mice in the bleomycin and bleomycin + hemin groups were injected intratracheally with bleomycin to establish the pulmonary fibrosis model. The bleomycin + hemin group mice were injected intraperitoneally with hemin starting 7 days before modeling until the end of Day 21 after modeling. Pathological changes in lung tissue were assessed by HE and Masson staining. Malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) levels were determined in lung tissue. Immunohistochemistry was performed to assess the expression of α-SMA and collagen I. The serum levels of IL-6 and TNF-α were measured via ELISA. Western blotting was used to determine the expression of TGF-β1, SIRT1, PGC-1α and HO-1 and the phosphorylation levels of p38, ERK1/2, JNK, AMPK and NF-κB p65 in lung tissue. Hemin significantly reduced lung indices, increased terminal body weight. It also significantly increased SOD and CAT activities; decreased MDA, IL-6 and TNF-α levels; reduced the levels of α-SMA and collagen I-positive cells; upregulated SIRT1, PGC-1α and HO-1 expression; promoted AMPK phosphorylation; and downregulated TGF-β1 expression and p38, ERK1/2, JNK and NF-κB p65 phosphorylation. Hemin might attenuate oxidative damage and inflammatory responses and reduces extracellular matrix deposition by regulating the expression and phosphorylation of proteins associated with the TGF-β1/MAPK and AMPK/SIRT1/PGC-1α/HO-1/NF-κB pathways, thereby alleviating bleomycin-induced pulmonary fibrosis.

Heme Oxygenase-1 Inhibits the Proliferation of Hepatic Stellate Cells by Activating PPARγ and Suppressing NF-κB

Background

Hepatic stellate cells (HSCs) are reported to play significant roles in the development of liver fibrosis. Heme oxygenase-1 (HO-1) is a key rate-limiting enzyme, which could decrease collagen synthesis and liver damage. Nevertheless, it was yet elusive towards the function and mechanism of HO-1.

Methods

An HO-1 inducer Hemin or an HO-1 inhibitor ZnPP-IX was used to treat the activated HSC-T6, respectively. MTT assay was adopted to detect cell proliferation. Immunocytochemical staining was employed to test the levels of alpha-smooth muscle actin (α-SMA), peroxisome proliferator-activated receptor-γ (PPARγ), and nuclear factor-kappa B (NF-kappa B) levels in HSC-T6. HO-1, PPARγ, and NF-κB expression levels were measured by qRT-PCR and Western blotting. ELISA was then used to detect the levels of transforming growth factor- (TGF-) beta 1 (TGF-β1), interleukin-6 (IL-6), serum hyaluronic acid (HA), and serum type III procollagen aminopeptide (PIIIP).

Results

HSC-T6 proliferation was inhibited in Hemin-treated HSCs. The levels of α-SMA, HA, and PIIIP and the production of ECM were lower in Hemin-treated HSCs, whereas those could be rescued by ZnPP-IX. NF-κB activation was decreased, but PPARγ expression was increased after HO-1 upregulation. Furthermore, the levels of TGF-β1 and IL-6, which were downstream of activated NF-κB in HSC-T6, were reduced. The PPAR-specific inhibitor GW9662 could block those mentioned effects.

Conclusions

Our data demonstrated that HO-1 induction could inhibit HSC proliferation and activation by regulating PPARγ expression and NF-κB activation directly or indirectly, which makes it a promising therapeutic target for liver fibrosis.

Heme Oxygenase 1 in Vertebrates: Friend and Foe

HO-1 is the inducible form of the enzyme heme-oxygenase. HO-1 catalyzes heme breakdown, reducing the levels of this important oxidant molecule and generating antioxidant, anti-inflammatory, and anti-apoptotic byproducts. Thus, HO-1 has been described as an important stress response mechanism during both physiologic and pathological processes. Interestingly, some findings are demonstrating that uncontrolled levels of HO-1 byproducts can be associated with cell death and tissue destruction as well. Furthermore, HO-1 can be located in the nucleus, influencing gene transcription, cellular proliferation, and DNA repair. Here, we will discuss several studies that approach HO-1 effects as a protective or detrimental mechanism in different pathological conditions. In this sense, as the major organs of vertebrates will deal specifically with distinct types of stresses, we discuss the HO-1 role in each of them, exposing the contradictions associated with HO-1 expression after different insults and circumstances.

Heme Oxygenase-1 Induction by Cobalt Protoporphyrin Ameliorates Cholestatic Liver Disease in a Xenobiotic-Induced Murine Model

Cholestatic liver diseases can progress to end-stage liver disease and reduce patients' quality of life. Although their underlying mechanisms are still incompletely elucidated, oxidative stress is considered to be a key contributor to these diseases. Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that displays antioxidant action. It has been found that this enzyme plays a protective role against various inflammatory diseases. However, the role of HO-1 in cholestatic liver diseases has not yet been investigated. Here, we examined whether pharmacological induction of HO-1 by cobalt protoporphyrin (CoPP) ameliorates cholestatic liver injury. To this end, a murine model of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet feeding was used. Administration of CoPP ameliorated liver damage and cholestasis with HO-1 upregulation in DDC diet-fed mice. Induction of HO-1 by CoPP suppressed the DDC diet-induced oxidative stress and hepatocyte apoptosis. In addition, CoPP attenuated cytokine production and inflammatory cell infiltration. Furthermore, deposition of the extracellular matrix and expression of fibrosis-related genes after DDC feeding were also decreased by CoPP. HO-1 induction decreased the number of myofibroblasts and inhibited the transforming growth factor-β pathway. Altogether, these data suggest that the pharmacological induction of HO-1 ameliorates cholestatic liver disease by suppressing oxidative stress, hepatocyte apoptosis, and inflammation.

Heme Oxygenase-1 in Gastrointestinal Tract Health and Disease

Heme oxygenase 1 (HO-1) is the rate-limiting enzyme of heme oxidative degradation, generating carbon monoxide (CO), free iron, and biliverdin. HO-1, a stress inducible enzyme, is considered as an anti-oxidative and cytoprotective agent. As many studies suggest, HO-1 is highly expressed in the gastrointestinal tract where it is involved in the response to inflammatory processes, which may lead to several diseases such as pancreatitis, diabetes, fatty liver disease, inflammatory bowel disease, and cancer. In this review, we highlight the pivotal role of HO-1 and its downstream effectors in the development of disorders and their beneficial effects on the maintenance of the gastrointestinal tract health. We also examine clinical trials involving the therapeutic targets derived from HO-1 system for the most common diseases of the digestive system.

Repeated Administration of Clinical Doses of Tramadol and Tapentadol Causes Hepato- and Nephrotoxic Effects in Wistar Rats

Tramadol and tapentadol are fully synthetic and extensively used analgesic opioids, presenting enhanced therapeutic and safety profiles as compared with their peers. However, reports of adverse reactions, intoxications and fatalities have been increasing. Information regarding the molecular, biochemical, and histological alterations underlying their toxicological potential is missing, particularly for tapentadol, owing to its more recent market authorization. Considering the paramount importance of liver and kidney for the metabolism and excretion of both opioids, these organs are especially susceptible to toxicological damage. In the present study, we aimed to characterize the putative hepatic and renal deleterious effects of repeated exposure to therapeutic doses of tramadol and tapentadol, using an in vivo animal model. Male Wistar rats were randomly divided into six experimental groups, composed of six animals each, which received daily single intraperitoneal injections of 10, 25 or 50 mg/kg tramadol or tapentadol (a low, standard analgesic dose, an intermediate dose and the maximum recommended daily dose, respectively). An additional control group was injected with normal saline. Following 14 consecutive days of administration, serum, urine and liver and kidney tissue samples were processed for biochemical, metabolic and histological analysis. Repeated administration of therapeutic doses of both opioids led to: (i) increased lipid and protein oxidation in liver and kidney, as well as to decreased total liver antioxidant capacity; (ii) decreased serum albumin, urea, butyrylcholinesterase and complement C3 and C4 levels, denoting liver synthesis impairment; (iii) elevated serum activity of liver enzymes, such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and γ-glutamyl transpeptidase, as well as lipid profile alterations, also reflecting hepatobiliary commitment; (iv) derangement of iron metabolism, as shown through increases in serum iron, ferritin, haptoglobin and heme oxygenase-1 levels. In turn, elevated serum cystatin C, decreased urine creatinine output and increased urine microalbumin levels were detected upon exposure to tapentadol only, while increased serum amylase and urine N-acetyl-β-D-glucosaminidase activities were observed for both opioids. Collectively, these results are compatible with kidney injury. Changes were also found in the expression levels of liver- and kidney-specific toxicity biomarker genes, upon exposure to tramadol and tapentadol, correlating well with alterations in lipid profile, iron metabolism and glomerular and tubular function. Histopathological analysis evidenced sinusoidal dilatation, microsteatosis, mononuclear cell infiltrates, glomerular and tubular disorganization, and increased Bowman's spaces. Although some findings are more pronounced upon tapentadol exposure, our study shows that, when compared with acute exposure, prolonged administration of both opioids smooths the differences between their toxicological effects, and that these occur at lower doses within the therapeutic range.

Sulforaphane Protects Cells against Lipopolysaccharide-Stimulated Inflammation in Murine Macrophages

Inflammation is an essential part for the general or innate immune defenses to defend against tissue damage and accelerate the curing process by providing protection against pathogens. Sulforaphane (SFN) is a natural isothiocyanate that has potential properties against inflammation, along with other protective functions. The purpose of this study was to examine the mechanism of its protective effect on lipopolysaccharide (LPS)-induced inflammation in Raw 264.7 macrophages. Here, we compared LPS-challenged macrophages with or without SFN pretreatment. Macrophages were pre-incubated for 6 h with a wide range of concentrations of SFN (0 to 50 µM), and then treated with LPS for 24 h. Nitric oxide (NO) concentration and gene expression of different inflammatory mediators, i.e., interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β, were measured. SFN neither directly reacted with cytokines, nor with NO. To understand the mechanisms, we performed analyses of the expression of regulatory enzyme inducible nitic oxide synthase (iNOS), the transcription factor NF-E2-related factor 2 (Nrf2), and its enzyme heme-oxygenase (HO)-1. Our results revealed that LPS increased significantly the expression of inflammatory cytokines and concentration of NO in non-treated cells. SFN was able to prevent the expression of NO and cytokines through regulating inflammatory enzyme iNOS and activation of Nrf2/HO-1 signal transduction pathway.

Upregulation of Heme Oxygenase-1 by Hemin Alleviates Sepsis-Induced Muscle Wasting in Mice

Hemin, an inducer of heme oxygenase-1 (HO-1), can enhance the activation of HO-1. HO-1 exhibits a variety of activities, such as anti-inflammatory, antioxidative, and antiapoptotic functions. The objective of this study was to investigate the effects of hemin on sepsis-induced skeletal muscle wasting and to explore the mechanisms by which hemin exerts its effects. Cecal ligation and perforation (CLP) was performed to create a sepsis mouse model. Mice were randomly divided into four groups: control, CLP, CLP plus group, and CLP-hemin-ZnPP (a HO-1 inhibitor). The weight of the solei from the mice was measured, and histopathology was examined. Cytokines were measured by enzyme-linked immunosorbent assay (ELISA). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting were used to assess the expression levels of HO-1 and atrogin-1. Furthermore, we investigated the antioxidative effects of HO-1 by detecting malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity. CLP led to dramatic skeletal muscle weakness and atrophy, but pretreatment with hemin protected mice against CLP-mediated muscle atrophy. Hemin also induced high HO-1 expression, which resulted in suppressed proinflammatory cytokine and reactive oxygen species (ROS) production. The expression of MuRF1 and atrogin-1, two ubiquitin ligases of the ubiquitin-proteasome system- (UPS-) mediated proteolysis, was also inhibited by increased HO-1 levels. Hemin-mediated increases in HO-1 expression exert protective effects on sepsis-induced skeletal muscle atrophy at least partly by inhibiting the expression of proinflammatory cytokines, UPS-mediated proteolysis, and ROS activation. Therefore, hemin might be a new treatment target against sepsis-induced skeletal muscle atrophy.

Heme oxygenase-1 exerts pro-apoptotic effects on hepatic stellate cells in vitro through regulation of nuclear factor-κB

Heme oxygenase-1 (HO-1) is an antioxidant and cytoprotective protein, which has been proven to alleviate the proliferation of hepatic stellate cells (HSCs) and the development of liver fibrosis. However, the role of HO-1 in HSC apoptosis remains unclear. The aim of the present study was to investigate the effect of HO-1 on HSC apoptosis and its possible underlying mechanisms. HSCs-T6 were incubated with different concentrations of hemin (HO-1 chemical inducer) and Znpp-IX (HO-1 chemical inhibitor) for 12, 24 and 48 h. Cell viability was determined using an MTT assay. HSCs were classified into 4 groups as follows: Control, hemin, Znpp-IX and hemin+Znpp-IX co-treatment groups. Apoptosis was quantitatively measured by Annexin V/propidium iodide double staining and a terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. The mRNA and protein expression of HO-1, α-smooth muscle actin, B-cell lymphoma (Bcl)-2, caspase-3 and nuclear factor (NF)-κB p65 were measured using quantitative polymerase chain reaction and western blotting. The levels of tumor growth factor (TGF)-β and interleukin (IL)-6 in HSC supernatants were examined by ELISA. The results demonstrated that HO-1 exerted antiproliferative effects on HSCs in a time- and concentration-dependent manner. Increasing HO-1 expression induced HSC apoptosis in vitro as demonstrated by a significant decrease in Bcl-2 and an increase in caspase-3 expression. Additionally, the expression of NF-κB p65 and its downstream inflammatory factors TGF-β and IL-6 in the HO-1 overexpression group was significantly decreased compared with the control group. Therefore, the present study provided evidence that HO-1 serves an anti-fibrosis role in the liver by enhancing HSC apoptosis, which was partially associated with the regulation of NF-κB and its downstream effectors.

Thermodynamic Aspects and Reprogramming Cellular Energy Metabolism during the Fibrosis Process

Fibrosis is characterized by fibroblast proliferation and fibroblast differentiation into myofibroblasts, which generate a relaxation-free contraction mechanism associated with excessive collagen synthesis in the extracellular matrix, which promotes irreversible tissue retraction evolving towards fibrosis. From a thermodynamic point of view, the mechanisms leading to fibrosis are irreversible processes that can occur through changing the entropy production rate. The thermodynamic behaviors of metabolic enzymes involved in fibrosis are modified by the dysregulation of both transforming growth factor β (TGF-β) signaling and the canonical WNT/β-catenin pathway, leading to aerobic glycolysis, called the Warburg effect. Molecular signaling pathways leading to fibrosis are considered dissipative structures that exchange energy or matter with their environment far from the thermodynamic equilibrium. The myofibroblastic cells arise from exergonic processes by switching the core metabolism from oxidative phosphorylation to glycolysis, which generates energy and reprograms cellular energy metabolism to induce the process of myofibroblast differentiation. Circadian rhythms are far-from-equilibrium thermodynamic processes. They directly participate in regulating the TGF-β and WNT/β-catenin pathways involved in energetic dysregulation and enabling fibrosis. The present review focusses on the thermodynamic implications of the reprogramming of cellular energy metabolism, leading to fibroblast differentiation into myofibroblasts through the positive interplay between TGF-β and WNT/β-catenin pathways underlying in fibrosis.

Interactions between TGF-β1, canonical WNT/β-catenin pathway and PPAR γ in radiation-induced fibrosis

Radiation therapy induces DNA damage and inflammation leading to fibrosis. Fibrosis can occur 4 to 12 months after radiation therapy. This process worsens with time and years. Radiation-induced fibrosis is characterized by fibroblasts proliferation, myofibroblast differentiation, and synthesis of collagen, proteoglycans and extracellular matrix. Myofibroblasts are non-muscle cells that can contract and relax. Myofibroblasts evolve towards irreversible retraction during fibrosis process. In this review, we discussed the interplays between transforming growth factor-β1 (TGF-β1), canonical WNT/β-catenin pathway and peroxisome proliferator-activated receptor gamma (PPAR γ) in regulating the molecular mechanisms underlying the radiation-induced fibrosis, and the potential role of PPAR γ agonists. Overexpression of TGF-β and canonical WNT/β-catenin pathway stimulate fibroblasts accumulation and myofibroblast differentiation whereas PPAR γ expression decreases due to the opposite interplay of canonical WNT/β-catenin pathway. Both TGF-β1 and canonical WNT/β-catenin pathway stimulate each other through the Smad pathway and non-Smad pathways such as phosphatidylinositol 3-kinase/serine/threonine kinase (PI3K/Akt) signaling. WNT/β-catenin pathway and PPAR γ interact in an opposite manner. PPAR γ agonists decrease β-catenin levels through activation of inhibitors of the WNT pathway such as Smad7, glycogen synthase kinase-3 (GSK-3 β) and dickkopf-related protein 1 (DKK1). PPAR γ agonists also stimulate phosphatase and tensin homolog (PTEN) expression, which decreases both TGF-β1 and PI3K/Akt pathways. PPAR γ agonists by activating Smad7 decrease Smads pathway and then TGF-β signaling leading to decrease radiation-induced fibrosis. TGF-β1 and canonical WNT/β-catenin pathway promote radiation-induced fibrosis whereas PPAR γ agonists can prevent radiation-induced fibrosis.

The Protective Effect of Heme Oxygenase-1 against Intestinal Barrier Dysfunction in Cholestatic Liver Injury Is Associated with NF-κB Inhibition

Heme oxygenase-1 (HO-1) is reported to protect against liver injury, but little is known about its effect on the intestinal barrier in cholestatic liver injury. In this study, we investigated the effects of HO-1 and its enzymatic by-product on intestinal barrier dysfunction in bile duct ligation (BDL) rats and explored the possible mechanism. The HO-1 inducer cobalt protoporphyrin (CoPP) and carbon monoxide-releasing molecule-2 (CORM-2) were used; the expression levels of tight junction (TJ) proteins, intestinal inflammation and NF-κB p65 were measured. For an in vitro experiment, stable Caco-2 cell lines were constructed, one overexpressed the HO-1 gene and another with that gene knocked down, and the specific NF-κB inhibitor JSH-23 was used. CoPP and CORM-2 treatment alleviated liver and intestinal mucosa injury in BDL rats; improved ZO-1, claudin-1 and PCNA expression; and reduced cell apoptosis and intestinal interleukin-6 (IL-6) expression. In vitro studies confirmed that HO-1, ZO-1 and occludin were overexpressed in HO-1-transfected Caco-2 cells, while decreased in the sh-HO-1 group. JSH-23 significantly increased occludin expression in both the HO-1 overexpression and sh-HO-1 groups, compared with their respective controls. HO-1 overexpression also inhibited the nuclear translocation of NF-κB p65 after lipopolysaccharide (LPS) treatment. Additionally, phospho-p65 expression in sh-HO-1 cells was significantly increased compared with that of the HO-1 overexpression group. In conclusion, HO-1 and CORM-2 improved intestinal epithelial barrier function in BDL-induced cholestatic liver injury mainly by restoring TJ, reducing cell apoptosis and intestinal inflammation. HO-1 exerts a protective effect, which is partially correlated with the regulation of NF-κB.

The antifibrotic and fibrolytic properties of date fruit extract via modulation of genotoxicity, tissue-inhibitor of metalloproteinases and nuclear factor- kappa B pathway in a rat model of hepatotoxicity

BACKGROUND

Hepatic fibrosis and its end point; cirrhosis, are the major cause of liver failure and death in patients with chronic liver disease. Therefore, the need for an effective treatment is evident. This study was designed to assess the potential effects of aqueous extract of date fruits, either flesh (DFE) or pits (DPE), on oxidative DNA damage and liver inflammation induced by carbon tetrachloride (CCl4) and whether they are related to inhibition of nuclear factor-κB pathway. In addition, the fibrolytic potential was evaluated via measuring matrix metalloproteinase-9 and tissue inhibitor of metalloproteinases -1 and -2.

METHODS

Rats were divided into the following groups: normal control, model control (CCl4 only), CCl4 + DFE, CCl4 + DPE and CCl4 + coffee. Coffee was used as a positive control. Fibrosis was induced by chronic administration of CCl4 (0.4 ml/kg) 3× a week for 8 weeks, and rats were treated with 6 ml/kg/day of DFE or DPE for 8 weeks. Liver homogenate was prepared for evaluation of oxidative stress, DNA damage, inflammatory and fibrolytic markers. Data are analyzed using one-way analysis of variance followed by a Tukey-Kramer post hoc test.

RESULTS

Both DFE and DPE significantly attenuated CCl4-induced oxidative damage as indicated by reducing lipid, protein and DNA oxidation in addition to increasing the levels of hepatic catalase activity. Both extracts blocked the accumulation of collagen I in the liver and ameliorated the increased expression of collagen III and α-smooth muscle actin suggesting suppression of profibrotic response induced by CCl4. DFE and DPE also upregulated the expression of heme oxygenase-1 and attenuated the nuclear factor-κB activation and cycloxygenase-2 expression reflecting their anti-inflammatory potential. Additionally, both flesh and pits extracts attenuated the increase in the tissue inhibitor of metalloproteinases -1 and -2 suggesting their fibrolytic activity.

CONCLUSION

Our data suggest that DFE or DPE can prevent liver fibrosis by suppressing genotoxicity and nuclear factor-κB inflammatory pathway and by promoting collagen degradation.

Comparative study of antifibrotic activity of some magnesium-containing supplements on experimental liver toxicity. Molecular study

INTRODUCTION

Liver fibrosis is the excessive accumulation of extracellular matrix (ECM) proteins including collagen that occurs in most types of chronic liver diseases. This study aimed to investigate and compare the therapeutic efficacy of different magnesium (Mg)-containing supplements (formulations A, B, and C) on carbon tetrachloride (CCl₄)-induced liver fibrosis in rats.

METHODS

Liver fibrosis was induced by intraperitoneal injection of rats with CCl₄ (1:1 in olive oil, 2 mL/kg, three times/week) for 4 weeks, and then rats were orally treated with different Mg-containing supplements (formulations A, B, and C) once daily for another one month. Liver fibrosis was quantified by evaluation of expressions of Collagen I, transforming growth factor β-1 (TGFβ1), platelet-derived growth factor-C (PDGF-C), nuclear factor kappa-β (NF-κβ), and measurement of hepatic collagen (hydroxyproline) level. Also, malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH) level, superoxide dismutase (SOD), and glutathione-S-transferase (GST) activities were estimated.

RESULTS

CCl₄ administration significantly elevated expressions of the studied genes, hepatic hydroxyproline, MDA, and NO levels and caused depletion of GSH level, decreased SOD, and GST activities when compared with those of their corresponding control, p < 0.05. All magnesium supplements significantly inhibited expressions of the studied genes and attenuated the hepatic hydroxyproline level as compared with those of CCl₄-treated group_; p < 0.05; for NF-κβ, the highest inhibition was by formulations B and C. Regarding Collagen I, TGFβ1, and hepatic hydroxyproline content, the highest inhibition was by Formulation C, and Formulation A revealed highest inhibition for PDGF-C. All magnesium supplements revealed normalization of oxidant and antioxidants parameters. Histopathological examination supports the biochemical and molecular findings.

CONCLUSION

Mg supplements were effective in the treatment of hepatic CCl₄-induced fibrosis-rat model.

Liguzinediol protects against cardiac fibrosis in rats in vivo and in vitro

Cardiac fibrosis plays a causal role in the development of heart failure, and anti-fibrotic therapy represents a promising strategy to mitigate heart failure. The purpose of this study was to investigate the effect of a new drug-liguzinediol on cardiac fibrosis of heart failure Male Sprague-Dawley rats (SD) rats and the underlying mechanisms. Liguzinediol was administered to rats that were injected with doxorubicin (Dox) for four weeks. Two weeks later, its effects on cardiac fibrosis were assessed by haematoxylin and eosin (HE) staining and Masson staining. The collagen content was determined by Elisa, and protein expression was detected by western blot in vitro and in vivo. Liguzinediol decreased cardiac muscle fiber break evidenced by HE staining and it significantly reduced cardiac fibrosis evidenced by Masson staining in DOX-treated rats. In addition, the hydroxyproline level and the ratio of type I/III collagens were also significantly decreased, and western blot assays showed that liguzinediol regulated the balance between matrix matalloproteinases (MMPs) and tissue inhibitor of metalloproteinase (TIMPs) to protect cardiac remodeling in vivo and in vitro. These data collectively indicated that liguzinediol could protect against cardiac fibrosis in rats. Liguzinediol could be exploited to be a promising candidate for cardiac fibrosis.

Therapeutic value of melatonin post-treatment on CCl4-induced fibrotic rat liver

Melatonin is known for being beneficial in targeting liver diseases. This study aimed to investigate whether melatonin post-treatment is capable of rat carbon tetrachloride (CCl4)-induced liver fibrosis reduction. Thirty-two male Sprague-Dawley rats were divided into 4 groups: normal; fibrosis with CCl4 injection (1 mL/kg) twice weekly for 8 weeks; phosphate-buffered saline (PBS); and melatonin (20 mg/kg) for a further 4 weeks on cessation of CCl4. At the beginning of week 13, liver tissue samples were used for hematoxylin-eosin (H&E), periodic acid-Schiff (PAS), Masson’s trichrome (MT), and Oil Red O staining, quantitative real-time PCR (qRT-PCR) analysis of the matrix metalloproteinase-9 (MMP-9), MMP-13, transforming growth factor-β1 (TGF-β1), Bcl-2, and Bax genes as well as immunofluorescence (IF) of the first 3, and sera for measurement of aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin, and hydroxyproline. Chronic administration of CCl4 followed by considerable increase in tissue disruption, macro- and micro-vesicles, collagen, lipid droplets (LDs), AST, ALT, hydroxyproline, TGF-β1, and Bax, and decrease in glycogen depository, albumin, Bcl-2, MMP-9, and MMP-13; however, the pattern was reverse when it comes to melatonin treatment (for all p < 0.05). Our results reveal the beneficial aspects of melatonin in treatment of liver fibrosis probably via inhibition of TGF-β1expression.

Inflammation and Edema in the Lung and Kidney of Hemorrhagic Shock Rats Are Alleviated by Biliary Tract External Drainage via the Heme Oxygenase-1 Pathway

The lung and kidney are two organs that are easily affected by hemorrhagic shock (HS). We investigated roles of biliary tract external drainage (BTED) in inflammation and edema of the lung and kidney in HS and its relationship with the heme oxygenase-1 (HO-1) pathway. Rat models of HS were induced by drawing blood from the femoral artery until a mean arterial pressure (MAP) of 40 ± 5 mmHg was achieved. A MAP of 40 ± 5 mmHg was maintained for 60 min. Thirty-six Sprague-Dawley rats were randomized to the following groups: sham group; HS group; HS + zinc protoporphyrin IX (ZnPP), a specific HO-1 inhibitor, group; HS + BTED group; HS + BTED + ZnPP group; and HS + BTED + bile infusion (BI) group. HO-1 levels, aquaporin-1 levels, and ratios of dry/wet in the lung and kidney increased markedly after BTED, but tumor necrosis factor-α and myeloperoxidase levels in the lung and kidney decreased significantly after BTED under HS conditions. Under the condition that HO-1 was inhibited by ZnPP, all these effects induced by BTED disappeared in the lung and kidney. These results demonstrated that inflammation and edema of the lung and kidney of HS rats are alleviated by BTED via the HO-1 pathway.

Endogenous carbon monoxide downregulates hepatic cystathionine-γ-lyase in rats with liver cirrhosis

The aim of the present study was to investigate the effect of endogenous carbon monoxide (CO) on the hydrogen sulfide/cystathionine-γ-lyase (H₂S/CSE) pathway in cirrhotic rat livers. The rats were allocated at random into four groups: Sham, cirrhosis, cobalt protoporphyrin (CoPP) and zinc protoporphyrin IX (ZnPP). The expression of hepatic CSE mRNA was evaluated using a quantitative polymerase chain reaction, while CSE protein expression was determined using immunohistochemical analysis. Hematoxylin and eosin staining was performed for the histological evaluation of liver fibrosis. The levels of H₂S, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL) and carboxyhemoglobin (COHb) in the arterial blood were determined, in addition to the portal vein pressure. The mRNA and protein expression levels of hepatic CSE and the serum levels of H₂S were significantly decreased in the cirrhosis group compared with those in the sham group (P<0.05). Compared with the cirrhosis group, rats in the ZnPP group had significantly lower levels of serum ALT, AST and TBIL, arterial COHb and hepatic fibrosis, while hepatic CSE expression and the production of H₂S were significantly increased (P<0.05). The CoPP group exhibited decreased hepatic CSE expression and H₂S production, but aggravated hepatic function and fibrosis (P<0.05). In conclusion, the H₂S/CSE pathway is involved in the formation of liver cirrhosis and serves a crucial function in protecting liver cells against the progression of liver fibrosis. Endogenous CO downregulates hepatic CSE mRNA and protein expression and the production of H₂S in rats with liver cirrhosis.

Fructose Mediated Non-Alcoholic Fatty Liver Is Attenuated by HO-1-SIRT1 Module in Murine Hepatocytes and Mice Fed a High Fructose Diet

Background

Oxidative stress underlies the etiopathogenesis of nonalcoholic fatty liver disease (NAFLD), obesity and cardiovascular disease (CVD). Heme Oxygenase-1 (HO-1) is a potent endogenous antioxidant gene that plays a key role in decreasing oxidative stress. Sirtuin1 (SIRT1) belongs to the family of NAD-dependent de-acyetylases and is modulated by cellular redox.

Hypothesis

We hypothesize that fructose-induced obesity creates an inflammatory and oxidative environment conducive to the development of NAFLD and metabolic syndrome. The aim of this study is to determine whether HO-1 acts through SIRT1 to form a functional module within hepatocytes to attenuate steatohepatitis, hepatic fibrosis and cardiovascular dysfunction.

Methods and Results

We examined the effect of fructose, on hepatocyte lipid accumulation and fibrosis in murine hepatocytes and in mice fed a high fructose diet in the presence and absence of CoPP, an inducer of HO-1, and SnMP, an inhibitor of HO activity. Fructose increased oxidative stress markers and decreased HO-1 and SIRT1 levels in hepatocytes (p<0.05). Further fructose supplementation increased FAS, PPARα, pAMPK and triglycerides levels; CoPP negated this increase. Concurrent treatment with CoPP and SIRT1 siRNA in hepatocytes increased FAS, PPARα, pAMPK and triglycerides levels suggesting that HO-1 is upstream of SIRT1 and suppression of SIRT1 attenuates the beneficial effects of HO-1. A high fructose diet increased insulin resistance, blood pressure, markers of oxidative stress and lipogenesis along with fibrotic markers in mice (p<0.05). Increased levels of HO-1 increased SIRT1 levels and ameliorated fructose-mediated lipid accumulation and fibrosis in liver along with decreasing vascular dysfunction (p<0.05 vs. fructose). These beneficial effects of CoPP were reversed by SnMP.

Conclusion

Taken together, our study demonstrates, for the first time, that HO-1 induction attenuates fructose-induced hepatic lipid deposition, prevents the development of hepatic fibrosis and abates NAFLD-associated vascular dysfunction; effects that are mediated by activation of SIRT1 gene expression.

Blockade of CCN4 attenuates CCl4-induced liver fibrosis

INTRODUCTION

CCN4, also termed WNT-inducible signaling pathway protein-1 (WISP-1), has important roles in inflammation and tissue injury. This study aimed to investigate the effect of CCN4 inhibition using monoclonal anti-CCN4 antibody (CCN4mAb) on the liver injury and fibrosis in a mouse model of liver fibrosis.

MATERIAL AND METHODS

The mouse liver fibrosis model was induced by carbon tetrachloride (CCl4). Mice received vehicle (saline/olive oil) by subcutaneous injection, CCl4 by subcutaneous injection or CCl4 (subcutaneous) plus CCN4mAb by subcutaneous injection. The pro-inflammatory and pro-fibrotic factors were determined by Western blot. The biochemistry and histopathology, collagen deposition and nuclear factor (NF)-κB activity were also assessed.

RESULTS

Chronic CCl4 treatment caused liver injury and collagen accumulation. The expression levels of CCN4, pro-inflammatory and pro-fibrotic mediators as well as the activity of NF-κB were markedly increased. Treatment with CCN4mAb significantly inhibited CCl4-induced CCN4 expression, leading to attenuated CCl4-induced liver injury and the inflammatory response. CCN4 blockade also significantly reduced the formation of collagen in the liver and the expression of α-smooth muscle actin and transforming growth factor β1.

CONCLUSIONS

CCN4 inhibition by CCN4mAb in vivo significantly attenuated the CCl4-induced liver injury and the progression of liver fibrosis. CCN4 may represent a novel therapeutic target for liver injury and fibrosis.

Spontaneous liver fibrosis induced by long term dietary vitamin D deficiency in adult mice is related to chronic inflammation and enhanced apoptosis

Epidemiological studies have revealed an association between vitamin D deficiency and various chronic liver diseases. However, it is not known whether lack of vitamin D can induce spontaneous liver fibrosis in an animal model. To study this, mice were fed either a control diet or a vitamin D deficient diet (VDD diet). For the positive control, liver fibrosis was induced with carbon tetrachloride. Here we show, for the first time, that liver fibrosis spontaneously developed in mice fed the VDD diet. Long-term administration of a VDD diet resulted in necro-inflammation and liver fibrosis. Inflammatory mediators including tumor necrosis factor-α, interleulin-1, interleukin-6, Toll-like-receptor 4, and monocyte chemotactic protein-1 were up-regulated in the livers of the mice fed the VDD diet. Conversely, the expression of Th2/M2 markers such as IL-10, IL-13, arginase 1, and heme oxygenase-1 were down-regulated in the livers of mice fed the VDD diet. Transforming growth factor-β1 and matrix metalloproteinase 13, which are important for fibrosis, were induced in the livers of mice fed the VDD diet. Moreover, the VDD diet triggered apoptosis in the parenchymal cells, in agreement with the increased levels of Fas and FasL, and decreased Bcl2 and Bclx. Thus, long-term vitamin D deficiency can provoke chronic inflammation that can induce liver apoptosis, which consequently activates hepatic stellate cells to initiate liver fibrosis.

Octreotide attenuates liver fibrosis by inhibiting hepatic heme oxygenase-1 expression

The aim of the present study was to investigate the effects of octreotide treatment on hepatic heme oxygenase-1 (HO-1) expression, together with the influence of altered hepatic HO-1 expression levels on hepatic function and fibrosis in bile duct-ligated rats. The rats were divided randomly into sham, cirrhotic, cobalt protoporphyrin and octreotide treatment groups. The expression levels of hepatic HO-1 mRNA were measured by reverse-transcription polymerase chain reaction, while the protein expression was determined by western blotting and immunohistochemical analysis. Hematoxylin and eosin, and Van Gieson's staining, along with determination of the hydroxyproline content in the liver, were performed to determine the degree of liver fibrosis. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL) and carboxyhemoglobin (COHb) in arterial blood, and the mean arterial pressure and portal vein pressure were also measured. As compared with the sham group, hepatic HO-1 mRNA and protein expression levels, serum levels of ALT, AST and TBIL, COHb in arterial blood, hydroxyproline and collagen type I content were all significantly increased in the cirrhotic group. As compared with the cirrhotic group, the octreotide-treated group exhibited significantly reduced hepatic HO-1 expression levels, serum levels of ALT, AST and TBIL, COHb in arterial blood and the extent of hepatic fibrosis, whereas the cobalt protoporphyrin group exhibited significantly increased hepatic HO-1 expression levels, as well as aggravated hepatic function and fibrosis (P<0.05). In conclusion, octreotide inhibited hepatic HO-1 overexpression in cirrhotic rats, reduced hepatic HO-1 expression levels to relieve liver injury and attenuated liver fibrosis.

Modulatory effect of celastrol on Th1/Th2 cytokines profile, TLR2 and CD3+ T-lymphocyte expression in a relapsing-remitting model of multiple sclerosis in rats

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease of brain and spinal cord that has an increasing incidence worldwide and classically presents in a relapsing-remitting form. This study was designed to induce a relapsing-remitting model of experimental autoimmune encephalomyelitis (EAE) to investigate the possible modulatory effect of celastrol on Th1/Th2 cytokines profile, immunohistochemical expression of TLR2, and CD3+T-lymphocytic count. Eighteen female Sprague Dawley rats were divided into 3 groups; where group I served as normal control, group II as EAE+vehicle, and group III as EAE treated by celastrol (1mg/kg/day, i.p.) started at 10th day till 42nd day post-immunization. The clinical score of rats in group II (EAE+vehicle) was relapsed after the re-challenge at the 35th day post-immunization and exhibited significant positive association with serum TNF-α, NF-κB expression and nitrites levels in brain and spinal cord, and CD3+ T-lymphocytic count in brain tissues while serum IL-10 showed significant negative association. Treatment of EAE by celastrol caused amelioration of the clinical score and inhibited the relapse. It caused significant shift in cytokines profile from Th1 by decrease in TNF-α towards Th2 pattern by increase in IL-10. Moreover, celastrol treatment resulted in significant reduction in NF-κB expression, nitrites levels, as well as immunohistochemical expression of TLR2 and CD3+ T-lymphocytic count. The beneficial effect of celastrol was further confirmed histopathologically by reduction in H&E score. Collectively, these results provide a promising pre-clinical evidence and conclusion about use of celastrol in treatment of multiple sclerosis that must be accessed in further clinical studies.

P2X7 blockade attenuates mouse liver fibrosis

P2X7 is important in inflammation and tissue injury. The aim of the present study was to investigate the effect of P2X7 inhibition, using a specific inhibitor (A438079) to prevent the development of liver injury and fibrosis in a mouse model of liver fibrosis. The mouse liver fibrosis model was induced by carbon tetrachloride (CCl4). Mice received subcutaneous administration of vehicle (saline/olive oil), CCl4 or subcutaneous CCl4 and A438079. The pro‑inflammatory and pro‑fibrotic factors were determined by western blot analysis. The biochemistry, histopathology, collagen deposition and nuclear factor‑κB (NF‑κB) activity were also analyzed. Chronic CCl4 treatment resulted in liver injury and collagen accumulation. The expression levels of P2X7, pro‑inflammatory and pro‑fibrotic mediators, and the activity of NF‑κB were markedly increased. Treatment with A438079 significantly inhibited CCl4‑induced P2X7 expression, and attenuated CCl4‑induced liver injury and the inflammatory response. P2X7 blockade also significantly reduced the formation of collagen in the liver and the expression of α-smooth muscle actin and transforming growth factor‑β1. This study demonstrated that P2X7 inhibition attenuated liver injury and fibrosis in a mouse model. Thus, P2X7 is a potential novel therapeutic target for liver injury and fibrosis.

Inhibiting heme oxygenase-1 attenuates rat liver fibrosis by removing iron accumulation

AIM: To investigate the effects of the heme oxygenase (HO)-1/carbon monoxide system on iron deposition and portal pressure in rats with hepatic fibrosis induced by bile duct ligation (BDL).

METHODS: Male Sprague-Dawley rats were divided randomly into a Sham group, BDL group, Fe group, deferoxamine (DFX) group, zinc protoporphyrin (ZnPP) group and cobalt protoporphyrin (CoPP) group. The levels of HO-1 were detected using different methods. The serum carboxyhemoglobin (COHb), iron, and portal vein pressure (PVP) were also quantified. The plasma and mRNA levels of hepcidin were measured. Hepatic fibrosis and its main pathway were assessed using Van Gieson’s stain, hydroxyproline, transforming growth factor-β1 (TGF-β1), nuclear factor-E2-related factor 2 (Nrf2), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1).

RESULTS: Serum COHb and protein and mRNA expression levels of HO-1 and Nrf2 were increased in the BDL group compared with the Sham group and were much higher in the CoPP group. The ZnPP group showed lower expression of HO-1 and Nrf2 and lower COHb. The levels of iron and PVP were enhanced in the BDL group but were lower in the ZnPP and DFX groups and were higher in the CoPP and Fe groups. Hepcidin levels were higher, whereas superoxide dismutase levels were increased and malonaldehyde levels were decreased in the ZnPP and DFX groups. The ZnPP group also showed inhibited TGF-β1 expression and regulated TIMP-1/MMP-2 expression, as well as obviously attenuated liver fibrosis.

CONCLUSION: Reducing hepatic iron deposition and CO levels by inhibiting HO-1 activity though the Nrf2/Keap pathway could be helpful in improving hepatic fibrosis and regulating PVP.

Ankaflavin: a natural novel PPARγ agonist upregulates Nrf2 to attenuate methylglyoxal-induced diabetes in vivo

Ankaflavin (AK) is an active compound having anti-inflammatory, anti-cancer, antiatherosclerotic, and hypolipidemic effects. We have previously reported that AK acts as an antioxidant and antidiabetic drug; however, the mechanism by which AK prevents diabetes remains unknown. Hyperglycemia is associated with protein glycation, which produces advanced glycation end-products (AGEs). Methylglyoxal (MG)-a metabolite of carbohydrates-is believed to cause insulin resistance by inducing inflammation and pancreas damage. In this work, diabetes was induced in Wistar rats (4 weeks of age) by treating them with MG (600 mg/kg bw) for 4 weeks. We observed that AK (10mg/kg bw) exerted peroxisome proliferator-activated receptor-γ (PPARγ) agonist activity, thereby enhancing insulin sensitivity (as indicated by hepatic GLUT2 translocation, PTP1B suppression, and glucose uptake) by downregulating blood glucose and upregulating pancreatic and duodenal homeobox-1 and Maf-A expression and increasing insulin production in MG-induced rats. However, these effects were abolished by the administration of GW9662 (PPARγ antagonist), but the expression of hepatic heme oxygenase-1 (HO-1) and glutamate-cysteine ligase (GCL) was not suppressed in MG-induced rats. Therefore, the nuclear factor erythroid-related factor-2 (Nrf2) activation was investigated. AK did not affect hepatic Nrf2 mRNA or protein expression but significantly increased Nrf2 phosphorylation (serine 40), which was accompanied by increased transcriptional activation of hepatic HO-1 and GCL. These data indicated that AK protected rats from oxidative stress resulting from MG-induced insulin resistance. In contrast, these effects were not detected when the rats were treated with the antidiabetic drug rosiglitazone (10mg/kg bw). Moreover, we found that AK did not inhibit the generation of AGEs in vitro; however, the glutathione (GSH) levels in liver and pancreas of MG-induced rats were elevated in rats administered AK. Therefore, we believe that GSH may lower the MG level, which attenuates the formation of AGEs in the serum, kidney, liver, and pancreas of MG-induced rats. We also found that AK treatment reduced the production of inflammatory factors, such as tumor necrosis factor-α and interleukin-1β. Taken together, the results of our mechanistic study of MG-induced rats suggest that the protective effects of AK against diabetes are mediated by the upregulation of the signaling pathway of Nrf2, which enhances antioxidant activity and serves as a PPARγ agonist to enhance insulin sensitivity.

Silymarin decreases connective tissue growth factor to improve liver fibrosis in rats treated with carbon tetrachloride

Silymarin is an herbal product showing potential as protection against hepatic disorders. In an attempt to develop the agent for the treatment of hepatic fibrosis, we screened the effects of silymarin on a rat model of hepatic fibrosis induced by carbon tetrachloride (CCl₄). Intraperitoneal administration of CCl₄ to rats for 8 weeks not only increased the plasma levels of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) but also induced a marked increase in the formation of hepatic fibrosis. Moreover, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were also reduced in the liver of rats treated with CCl₄. Oral administration of silymarin (200 mg/kg, three times daily), in parallel, decreased the plasma levels of GOT and GPT. Furthermore, in addition to the improvement of hepatic fibrosis, the hepatic levels of hydroxyproline and connective tissue growth factor (CTGF) were both markedly decreased by silymarin. Silymarin also elevated the activities of SOD and GPx in liver isolated from CCl₄-treated rats. The results suggest that oral administration of silymarin protects against CCl₄-induced hepatic fibrosis in rats, likely due to the decrease in fibrotic parameters such as CTGF.

Correlation of nuclear factor κB expression with α-SMA and collagen Ⅲ expression in hepatic fibrosis in rats

AIM: To investigate the correlation of expression of nuclear factor κB with that of α-smooth muscle actin (α-SMA) and collagen Ⅲ in hepatic fibrosis in rats.

METHODS: Thirty-two male SD rats of SPF grade were divided randomly into control group and model group. Hepatic fibrosis was induced in rats by injecting carbon tetrachloride. The mRNA and protein expression of NF-κB, α-SMA, and collagen Ⅲ was examined using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. The correlation of NF-κB expression with α-SMA and collagen Ⅲ expression was then analyzed.

RESULTS: NF-κB, α-SMA and collagen Ⅲ were lowly expressed in normal liver tissue. After injection of carbon tetrachloride, the expression of NF-κB, α-SMA and collagen Ⅲ mRNAs and proteins began to increase at week 2 and was significantly higher at weeks 4 and 6 (both P < 0.05), showing a gradually rising trend. There was a positive correlation between the expression of NF-κB and that of α-SMA and collagen Ⅲ (both P < 0.05).

CONCLUSION: NF-κB plays an important role in the pathogenesis of hepatic fibrosis.