Effect of celecoxib on experimental liver fibrosis in rat

Research progress on rat model of drug-induced liver injury established by nonsteroidal anti-inflammatory drug (celecoxib) and royal jelly ameliorative effect

OBJECTIVES

NSAIDs, like celecoxib, are widely used to treat pain, fever, and inflammation, with celecoxib being particularly effective in managing arthritis symptoms and acute or chronic pain especially with its favorable gastrointestinal tolerability. The study aimed at exploring the effect of chronic administration of celecoxib on hepatic tissues in male albino rats. It also examined the royal jelly celecoxib interplay.

METHODS

50 male albino rats in 5 equal groups; Group 1: received no drug. Group 2: received celecoxib (50 mg/kg/day, orally), for 30 successive days. Group 3: received celecoxib plus royal jelly (300 mg/kg/day, orally) for 30 successive days. Group 4: received celecoxib, for 30 days, then were left untreated for another 30 days. Group 5: received celecoxib plus royal jelly for 30 days, then were left untreated for another 30 days.

RESULTS

Chronic celecoxib administration caused hepatotoxicity in male albino rats, with ameliorative effect of royal jelly. Celecoxib discontinuation significantly diminished the celecoxib-induced toxicity, and normal liver enzymes and serum protein levels were regained in the case of dual medications (celecoxib+RJ) discontinuation.

CONCLUSIONS

Long-term celecoxib administration caused hepatotoxicity, with ameliorative effects of royal jelly against celecoxib-induced oxidative and apoptotic stress. In addition, it could be concluded that royal jelly may prove a useful adjunct in patients being prescribed celecoxib.

The Role of Pyrazolo[3,4-d]pyrimidine-Based Kinase Inhibitors in The Attenuation of CCl4-Induced Liver Fibrosis in Rats

Liver Fibrosis can be life-threatening if left untreated as it may lead to serious, incurable complications. The common therapeutic approach is to reverse the fibrosis while the intervention is still applicable. Celecoxib was shown to exhibit some antifibrotic properties in the induced fibrotic liver in rats. The present study aimed to investigate the possible antifibrotic properties in CCl4-induced liver fibrosis in male Sprague–Dawley rats compared to celecoxib of three novel methoxylated pyrazolo[3,4-d]pyrimidines. The three newly synthesized compounds were proved to be safe candidates. They showed a therapeutic effect against severe CCl4-induced fibrosis but at different degrees. The three compounds were able to partially reverse hepatic architectural distortion and reduce the fibrotic severity by showing antioxidant properties reducing MDA with increasing GSH and SOD levels, remodeling the extracellular matrix proteins and liver enzymes balance, and reducing the level of proinflammatory (TNF-α and IL-6) and profibrogenic (TGF-β) cytokines. The results revealed that the dimethoxy-analog exhibited the greatest activity in all the previously mentioned parameters compared to celecoxib and the other two analogs which could be attributed to the different methoxylation patterns of the derivatives. Collectively, the dimethoxy-derivative could be considered a safe promising antifibrotic candidate.

Improved anti-fibrotic effects by combined treatments of simvastatin and NS-398 in experimental liver fibrosis models

BACKGROUND/AIMS

Efficient anti-fibrotic therapies are required for the treatment of liver cirrhosis. Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) and cyclooxygenase-2 (COX-2) inhibitors have been reported to have anti-fibrotic effects. Here, we investigated whether combined treatment with a statin and a COX-2 inhibitor has synergistic anti-fibrotic effects.

METHODS

The effects of treatment strategies incorporating both simvastatin and a COX-2 inhibitor, NS-398, were investigated using an immortalized human hepatic stellate cell line (LX-2) and a hepatic fibrosis mouse model developed using thioacetamide (TAA) in drinking water. Cellular proliferation was investigated via 5-bromo-2-deoxyuridine uptake. Pro- and anti-apoptotic factors were investigated through Western blotting and real-time polymerase chain reaction analysis.

RESULTS

The evaluation of the anti-proliferative effects on LX-2 cells showed that the observed effects were more pronounced with combination therapy than with single-drug therapy. Moreover, hepatic fibrosis and collagen deposition decreased significantly in TAA-treated mice in response to the combined treatment strategy. The mechanisms underlying the anti-fibrotic effects of the combination therapy were investigated. The effects of the combination therapy were correlated with increased expression levels of extracellular signal-regulated kinase 1/2 signaling molecules, upregulation of the Bax/Bcl-2 signaling pathway, inhibition of the transforming growth factor-β signaling pathway, and inhibition of tissue inhibitor of matrix metalloproteinases 1 and 2.

CONCLUSION

The combination of simvastatin and NS-398 resulted in a synergistic anti-fibrotic effect through multiple pathways. These findings offer a theoretical insight into the possible clinical application of this strategy for the treatment of advanced liver diseases with hepatic fibrosis.

Celecoxib reduces hepatic vascular resistance in portal hypertension by amelioration of endothelial oxidative stress

The balance between endothelial nitric oxide (NO) synthase (eNOS) activation and production of reactive oxygen species (ROS) is very important for NO homeostasis in liver sinusoidal endothelial cells (LSECs). Overexpression of cyclooxygenase‐2 (COX‐2), a major intravascular source of ROS production, has been observed in LSECs of cirrhotic liver. However, the links between low NO bioavailability and COX‐2 overexpression in LSECs are unknown. This study has confirmed the link between low NO bioavailability and COX‐2 overexpression by COX‐2‐dependent PGE2‐EP2‐ERK1/2‐NOX1/NOX4 signalling pathway in LSECs in vivo and in vitro. In addition, the regulation of COX‐2‐independent LKB1‐AMPK‐NRF2‐HO‐1 signalling pathway on NO homeostasis in LSECs was also elucidated. The combinative effects of celecoxib on diminishment of ROS via COX‐2‐dependent and COX‐2‐independent signalling pathways greatly decreased NO scavenging. As a result, LSECs capillarisation was reduced, and endothelial dysfunction was corrected. Furthermore, portal hypertension of cirrhotic liver was ameliorated with substantial decreasing hepatic vascular resistance and great increase of portal blood flow. With the advance understanding of the mechanisms of LSECs protection, celecoxib may serve as a potential therapeutic candidate for patients with cirrhotic portal hypertension.

Anti-inflammation treatment for protection of hepatocytes and amelioration of hepatic fibrosis in rats

Chronic inflammation is considered as an important pathophysiologic mechanism of hepatic cirrhosis, which induces hepatocyte injury and activates hepatic stellate cells (HSCs), thus resulting in hepatic fibrosis. Previous studies have reported that cyclooxygenase-2 (COX-2) inhibitor can effectively treat liver fibrosis, while somatostatin (SST) analogues inhibit the activation of HSCs. The present study aimed to investigate the effects of a COX-2 inhibitor, celecoxib, combined with a SST analogue, octreotide, for protection of hepatocytes and prevention of fibrosis in a rat model of hepatic fibrosis. Therefore, a hepatic fibrosis rat model was established following peritoneal injection of thioacetamide (TAA), and the rats were then treated with a combination of celecoxib and octreotide (TAA + C). Immunohistochemistry and western blotting assays were used to assess the expression levels of proteins associated with inflammation, epithelial-mesenchymal transition (EMT), proliferation, apoptosis and autophagy. H&E staining, transmission electron microscopy and scanning electron microscopy were used to evaluate the destruction of hepatocytes. Masson's Trichrome and Sirius Red were used to measure the degree of liver fibrosis. The results demonstrated that, compared with those of the control group, the degree of liver fibrosis and the expression of the intrahepatic inflammation factors were aggravated in the TAA group. Furthermore, the apoptosis rate, EMT and autophagy of hepatocytes were also increased in the TAA group. However, treatment with TAA + C restored the aforementioned increased levels compared with the TAA group. In conclusion, treatment of rats with the combination of celecoxib and octreotide could attenuate the progress of hepatic fibrosis via protection of hepatocytes by reducing apoptosis, EMT and autophagy in hepatocytes.

Role of eicosanoids in liver repair, regeneration and cancer

Eicosanoids are lipid signaling molecules derived from the oxidation of ω-6 fatty acids, usually arachidonic acid. There are three major pathways, including the cyclooxygenase (COX), lipoxygenase (LOX), and P450 cytochrome epoxygenase (CYP) pathway. Prostanoids, which include prostaglandins (PG) and thromboxanes (Tx), are formed via the COX pathway, leukotrienes (LT) and lipoxins (LX) by the action of 5-LOX, and hydroxyeicosatetraenoic acids (HETEs) and epoxyeicosatrienoic acids (EETs) by CYP. Although eicosanoids are usually associated with pro-inflammatory responses, non-classic eicosanoids, as LX, have anti-inflammatory and pro-resolving properties. Eicosanoids like PGE₂, LTB₄ and EETs have been involved in promoting liver regeneration after partial hepatectomy. PGE₂ and LTB₄ have also been reported to participate in the regenerative phase after ischemia and reperfusion (I/R), while cysteinyl leukotrienes (Cys-LT) contribute to the inflammatory process associated with I/R and are also involved in liver fibrosis and cirrhosis. However, LX, another product of 5-LOX, have the opposite effect, acting as pro-resolving mediators in these pathologies. In liver cancer, most studies show that eicosanoids, with the exception of LX, promote the proliferation of hepatocellular carcinoma cells and favor metastasis. This review summarizes the synthesis of different eicosanoids in the liver and discusses key findings from basic research linking eicosanoids to liver repair, regeneration and cancer and the impact of targeting eicosanoid cascade. In addition, studies in patients are presented that explore the potential use of eicosanoids as biomarkers and show correlations between eicosanoid production and the course and prognosis of liver disease.

Role of 2‑series prostaglandins in the pathogenesis of type 2 diabetes mellitus and non‑alcoholic fatty liver disease (Review)

Nowadays, metabolic syndromes are emerging as global epidemics, whose incidence are increasing annually. However, the efficacy of therapy does not increase proportionately with the increased morbidity. Type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) are two common metabolic syndromes that are closely associated. The pathogenic mechanisms of T2DM and NAFLD have been studied, and it was revealed that insulin resistance, hyperglycemia, hepatic lipid accumulation and inflammation markedly contribute to the development of these two diseases. The 2-series prostaglandins (PGs), a subgroup of eicosanoids, including PGD₂, PGE₂, PGF_2α and PGI₂, are converted from arachidonic acid catalyzed by the rate-limiting enzymes cyclooxygenases (COXs). Considering their wide distribution in almost every tissue, 2-series PG pathways exert complex and interlinked effects in mediating pancreatic β-cell function and proliferation, insulin sensitivity, fat accumulation and lipolysis, as well as inflammatory processes. Previous studies have revealed that metabolic disturbances, such as hyperglycemia and hyperlipidemia, can be improved by treatment with COX inhibitors. At present, an accumulating number of studies have focused on the roles of 2-series PGs and their metabolites in the pathogenesis of metabolic syndromes, particularly T2DM and NAFLD. In the present review, the role of 2-series PGs in the highly intertwined pathogenic mechanisms of T2DM and NAFLD was discussed, and important therapeutic strategies based on targeting 2-series PG pathways in T2DM and NAFLD treatment were provided.

Fibrotic expression profile analysis reveals repurposed drugs with potential anti-fibrotic mode of action

Fibrotic diseases cover a spectrum of systemic and organ-specific maladies that affect a large portion of the population, currently without cure. The shared characteristic these diseases feature is their uncontrollable fibrogenesis deemed responsible for the accumulated damage in the susceptible tissues. Idiopathic Pulmonary Fibrosis, an interstitial lung disease, is one of the most common and studied fibrotic diseases and still remains an active research target. In this study we highlight unique and common (i) genes, (ii) biological pathways and (iii) candidate repurposed drugs among 9 fibrotic diseases. We identify 7 biological pathways involved in all 9 fibrotic diseases as well as pathways unique to some of these diseases. Based on our Drug Repurposing results, we suggest captopril and ibuprofen that both appear to slow the progression of fibrotic diseases according to existing bibliography. We also recommend nafcillin and memantine, which haven't been studied against fibrosis yet, for further wet-lab experimentation. We also observe a group of cardiomyopathy-related pathways that are exclusively highlighted for Oral Submucous Fibrosis. We suggest digoxin to be tested against Oral Submucous Fibrosis, since we observe cardiomyopathy-related pathways implicated in Oral Submucous Fibrosis and there is bibliographic evidence that digoxin may potentially clear myocardial fibrosis. Finally, we establish that Idiopathic Pulmonary Fibrosis shares several involved genes, biological pathways and candidate inhibiting-drugs with Dupuytren's Disease, IgG4-related Disease, Systemic Sclerosis and Cystic Fibrosis. We propose that treatments for these fibrotic diseases should be jointly pursued.

Role of G Protein-Coupled Receptors in Hepatic Stellate Cells and Approaches to Anti-Fibrotic Treatment of Non-Alcoholic Fatty Liver Disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) is globally increasing. Gaining control over disease-related events in non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, is currently an unmet medical need. Hepatic fibrosis is a critical prognostic factor in NAFLD/NASH. Therefore, a better understanding of the pathophysiology of hepatic fibrosis and the development of related therapies are of great importance. G protein-coupled receptors (GPCRs) are cell surface receptors that mediate the function of a great variety of extracellular ligands. GPCRs represent major drug targets, as indicated by the fact that about 40% of all drugs currently used in clinical practice mediate their therapeutic effects by acting on GPCRs. Like many other organs, various GPCRs play a role in regulating liver function. It is predicted that more than 50 GPCRs are expressed in the liver. However, our knowledge of how GPCRs regulate liver metabolism and fibrosis in the different cell types of the liver is very limited. In particular, a better understanding of the role of GPCRs in hepatic stellate cells (HSCs), the primary cells that regulate liver fibrosis, may lead to the development of drugs that can improve hepatic fibrosis in NAFLD/NASH. In this review, we describe the functions of multiple GPCRs expressed in HSCs, their roles in liver fibrogenesis, and finally speculate on the development of novel treatments for NAFLD/NASH.

Celecoxib A Selective COX-2 Inhibitor Mitigates Fibrosis but not Pneumonitis Following Lung Irradiation: A Histopathological Study

Background:

Lung is one of the radiosensitive and late responding organs, and is an important target for ionizing radiation. Radiation-induced pneumonitis and fibrosis are major consequences of lung exposure to a high dose of radiation and pose threats to the lives of exposed people. Mitigation of lung injury following an accidental radiation event or for patients with lung cancer is one of the most interesting issues in radiobiology. In the current study, we aimed to determine whether celecoxib, the most common cyclooxygenase-2 (COX-2) inhibitor, is able to mitigate pneumonitis and fibrosis following lung irradiation or not.

Materials and methods:

20 male mice were assigned to 4 groups: control, celecoxib treatment, radiation, and radiation plus celecoxib. Irradiation was performed with a dose of 18 Gy cobalt-60 (60Co) gamma rays. Celecoxib treatment (50 mg/kg) started 24 h after irradiation and continued four times per week for 4 weeks.

Results:

Irradiation of lung led to remarkable infiltration of macrophages, lymphocytes, mast cells and neutrophils. Also, a mild increase in fibrosis markers including accumulation of collagen, and alveolar and vascular thickening, was observed. Post-exposure treatment with celecoxib was able to mitigate fibrosis as well as alveolar and vascular changes, however, it was unable to mitigate pneumonitis markers.

Conclusion:

Celecoxib showed that it may have an anti-fibrosis effect following exposure of mice lung to radiation, although it was unable to prevent pneumonitis.

Nicorandil and atorvastatin attenuate carbon tetrachloride - induced liver fibrosis in rats

PURPOSE

The present study aimed to evaluate the possible hepatoprotective effects of nicorandil and atorvastatin against experimentally induced liver fibrosis.

MATERIALS AND METHODS

Wistar male rats wereassigned tofivegroups; control group, fibrosis group, the remaining three groups received in addition to CCl₄, N-acetyl cysteine (300 mg/kg), nicorandil(15 mg/kg) and atorvastatin (20 mg/kg), respectively. Liver fibrosis was induced by intraperitoneal injection of rats with CCl₄ (2 ml/kg), twice weekly for five consecutive weeks. All treatments were administered daily starting from the first day of fibrosis induction for five consecutive weeks. By the end of the experiment, fibrosis biomarkers [hepatic transforming growth factor β1 (TGF-β₁) and hydroxyproline (HYP)], liver function [serum alanine transaminase (ALT), aspartate transaminase (AST), albumin and total bilirubin] were assessed. Moreover, lipid profile [total cholesterol, serum triglycerides, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C)], inflammatory biomarkers [hepatic myeloperoxidase (MPO), serum tumor necrosis factor alpha (TNF-α)], relative liver weight] and oxidative stress biomarkers [malondialdehyde (MDA), glutathione (GSH) and catalase (CAT)] were evaluated. In support, histopathological and immunohistochemical examination of liver alpha smooth muscle actin (α-SMA) were performed.

RESULTS

Nicorandil and atorvastatin effectively reduced fibrosis and liver function biomarkers. They both restored serum lipid profile, TNF-α, MPO, relative liver weight, and hepatic MDA content. Alternatively, they markedly elevated albumin, HDL-C and hepatic content of GSH and CAT. Additionally, a marked histopathological and immunohistochemical improvement of α-SMA was observed.

CONCLUSION

Nicorandil and atorvastatin might be promising protective agents against liver fibrosis through amelioration of liver function, modulation of fibrous formation, anti-inflammatory and antioxidant potentials.

Hepatoprotective effects of melatonin and celecoxib against ethanol-induced hepatotoxicity in rats

Objectives: Several studies demonstrated the antioxidant and anti-inflammatory role of melatonin and celecoxib. This study is designed to explore the underlying mechanism of hepatoprotective effects of melatonin and celecoxib against ethanol-induced hepatotoxicity by morphological, and biochemical approaches.Materials and methods: Adult male rats were divided into five groups: saline, ethanol, melatonin, and celecoxib were administered for 11 consecutive days after ethanol injection. Biochemical analyses were performed for the determination of glutathione (GSH), glutathione S-transferase (GST), and inducible nitric oxide (iNOS). Immunohistochemistry was performed to determine the level of different inflammatory markers.Results: Histopathological results showed that ethanol-induced marked hepatic injury leads to cloudy swelling, hydropic degeneration, apoptosis, and focal necrosis in all hepatic zones. Biochemical analysis revealed significant increases in serum transaminases and alkaline phosphatase in the ethanol group. Oxidative stress associated with attenuated antioxidant enzymes was also spotted in the ethanol group, as ethanol down-regulated GSH, GST, and upregulated NO. Additionally, ethanol increased the activation and the expression of tumor necrotic factor (TNF-α), p-NF_KB, and COX2. Finally, hepatic cellular apoptosis was clearly obvious in ethanol intoxicated animals using activated JNK staining.Conclusion: These results provided pieces of evidence that the hepatoprotective effect of melatonin and celecoxib is possibly mediated through the modulation of JNK and TNF-α signaling pathways with subsequent suppression of inflammatory and apoptotic processes.

Celecoxib Does Not Protect against Fibrosis and Inflammation in a Carbon Tetrachloride-Induced Model of Liver Injury

The cyclooxygenase-2 (COX-2) selective inhibitor celecoxib is widely used in the treatment of pain and inflammation. Celecoxib has been explored as a possible treatment of liver fibrosis with contradictory results, depending on the model. The present study reports the effect of celecoxib in a 5-week carbon tetrachloride (CCl₄)-induced liver fibrosis mouse model. Celecoxib alone and in combination with inhibitors of the enzyme-soluble epoxide hydrolase (sEH), as well as a dual inhibitor that targets both COX-2 and sEH, were administered via osmotic minipump to mice receiving intraperitoneal injections of CCl₄ Collagen deposition was elevated in the mice treated with both celecoxib and CCl₄ compared with the control or CCl₄-only groups, as assessed by trichrome staining. Histopathology revealed more extensive fibrosis and cell death in the animals treated with both celecoxib and CCl₄ compared with all other experimental groups. Although some markers of fibrosis, such as matrix metalloprotease, were unchanged or lowered in the animals treated with both celecoxib and CCl₄, overall, hepatic fibrosis was more severe in this group. Cotreatment with celecoxib and an inhibitor of sEH or treatment with a dual inhibitor of COX-2 and sEH decreased the elevated levels of fibrotic markers observed in the group that received both celecoxib and CCl₄ Oxylipid analysis revealed that celecoxib reduced the level of prostaglandin E₂ relative to the CCl₄ only group. Overall, celecoxib treatment did not decrease liver fibrosis in CCl₄-treated mice.

PGE2 induces apoptosis of hepatic stellate cells and attenuates liver fibrosis in mice by downregulating miR-23a-5p and miR-28a-5p

MicroRNAs (miRNAs), small noncoding RNAs modulating messenger RNA (mRNA) and protein expression, have emerged as key regulatory molecules in chronic liver diseases, whose end stage is hepatic fibrosis, a major global health burden. Pharmacological strategies for prevention or treatment of hepatic fibrosis are still limited, what makes it necessary to establish a better understanding of the molecular mechanisms underlying its pathogenesis. In this context, we have recently shown that cyclooxygenase-2 (COX-2) expression in hepatocytes restricts activation of hepatic stellate cells (HSCs), a pivotal event in the initiation and progression of hepatic fibrosis. Here, we evaluated the role of COX-2 in the regulation of a specific set of miRNAs on a mouse model of CCl₄ and bile duct ligation (BDL)-induced liver fibrosis. Our results provide evidence that COX-2 represses miR-23a-5p and miR-28-5p expression in HSC. The decrease of miR-23a-5p and miR-28-5p expression promotes protection against fibrosis by decreasing the levels of pro-fibrogenic markers α-SMA and COL1A1 and increasing apoptosis of HSC. Moreover, we demonstrate that serum levels of miR-28-5p are decreased in patients with chronic liver disease. These results suggest a protective effect exerted by COX-2-derived prostanoids in the process of hepatofibrogenesis.

Cyclooxygenase 2 in liver dysfunction and carcinogenesis: Facts and perspectives

The biosynthesis of prostaglandins and thromboxanes has been a focus of interest in the management of many liver diseases. Cyclooxygenases are the enzymes involved in the first step of the biosynthesis of these lipid mediators and selective inhibitors for these isoenzymes as well as pharmacological analogues of prostaglandins have been developed and are currently applied therapeutically. Here we discuss the implications of these enzymes in the onset of metabolic and lipid disorders in the liver and their potential role in the progression of the diseases towards fibrosis and hepatocellular carcinogenesis.

Cyclooxygenase-2 expression in hepatocytes attenuates non-alcoholic steatohepatitis and liver fibrosis in mice

Cyclooxygenase-2 (COX-2) is involved in different liver diseases but little is known about the significance of COX-2 in the development and progression of non-alcoholic steatohepatitis (NASH). This study was designed to elucidate the role of COX-2 expression in hepatocytes in the pathogenesis of steatohepatitis and hepatic fibrosis. In the present work, hepatocyte-specific COX-2 transgenic mice (hCOX-2-Tg) and their wild-type (Wt) littermates were either fed methionine-and-choline deficient (MCD) diet to establish an experimental non-alcoholic steatohepatitis (NASH) model or injected with carbon tetrachloride (CCl4) to induce liver fibrosis. In our animal model, hCOX-2-Tg mice fed MCD diet showed lower grades of steatosis, ballooning and inflammation than Wt mice, in part by reduced recruitment and infiltration of hepatic macrophages, with a corresponding decrease in serum levels of pro-inflammatory cytokines. Furthermore, hCOX-2-Tg mice showed a significant attenuation of the MCD diet-induced increase in oxidative stress and hepatic apoptosis observed in Wt mice. Even more, hCOX-2-Tg mice treated with CCl4 had significantly lower stages of fibrosis and less hepatic content of collagen, hydroxyproline and pro-fibrogenic markers than Wt controls. Collectively, our data indicates that constitutive hepatocyte COX-2 expression ameliorates NASH and liver fibrosis development in mice by reducing inflammation, oxidative stress and apoptosis and by modulating activation of hepatic stellate cells, respectively, suggesting a possible protective role for COX-2 induction in NASH/NAFLD progression.

Celecoxib attenuates depressive-like behavior associated with immunological liver injury in C57BL/6 mice through TNF-α and NF-κb dependent mechanisms

AIM

Depression associating patients with chronic liver diseases is a major treatment goal. This study aimed to evaluate the potential hepatoprotective and antidepressant effects of celecoxib in a model of experimental autoimmune hepatitis (EAH) and depressive-like behavior in C57BL/6 mice.

MAIN METHODS

EAH was induced by immunization with S-100 liver antigen emulsified in complete Freund's adjuvant (CFA). Mice were randomly allocated to 5 groups; control phosphate buffered saline group; control CFA group; EAH group, and 2 groups of EAH plus celecoxib (7.5 or 15mg/kg/d respectively). Mice were assessed behaviorally by novelty-suppressed test, tail suspension test, locomotor assessment and forced swimming tests. Serum liver enzymes and hepatic hydroxyproline content were biochemically analyzed. Histopathological analysis for liver and brain sections and immunohistochemical studies for hepatic and hippocampal tumor necrosis factor (TNF-α), nuclear factor Kappa-B (NF-κB) and caspase-3 were performed.

KEY FINDINGS

EAH group exhibited significant depressive-like changes, increase in liver enzymes and hepatic hydroxyproline content. Signs of autoimmune hepatitis and structural changes in hippocampus were confirmed by histopathological studies. Immunohistochemical examination revealed overexpression of hepatic and hippocampal TNF-α, NF-κB and caspase-3 positive cells. Celecoxib (7.5mg/kg/d) significantly ameliorated hepatic biochemical changes, hepatic and hippocampal histopathological and immunohistochemical changes induced in EAH group. Celecoxib (15mg/kg/d) significantly ameliorated the behavioral changes, histopathological and immunohistochemical changes in hippocampus, with non-significant change in hepatic biochemical profile, histopathological and immunohistochemical changes induced in EAH group.

SIGNIFICANCE

The celecoxib (7.5mg/kg/d) through its anti-inflammatory effect may represent a new therapeutic approach to treat autoimmune hepatitis associated with depressive symptoms.

Rebamipide retards CCl4-induced hepatic fibrosis in rats: Possible role for PGE2

Prostaglandin E2 (PGE2) is a potent physiological suppressor of liver fibrosis. Because the anti-ulcer drug rebamipide can induce the formation of endogenous PGE2, this study investigated the potential effects of rebamipide on development of a hepatic fibrosis that was inducible by carbon tetrachloride (CCl4). Groups of Wistar rats received intraperitoneal (IP) injections of CCl4 (0.45 ml/kg [0.72 g CCl4/kg]) over the course of for 4 weeks. Sub-sets of CCl4-treated rats were also treated concurrently with rebamipide at 60 or 100 mg/kg. At 24 h after the final treatments, liver function and oxidative stress were indirectly assessed. The extent of hepatic fibrosis was evaluated using two fibrotic markers, hyaluronic acid (HA) and pro-collagen-III (Procol-III); isolated liver tissues underwent histology and were evaluated for interleukin (IL)-10 and PGE2 content. The results indicated that treatment with rebamipide significantly inhibited CCl4-induced increases in serum ALT and AST and also reduced oxidative stress induced by CCl4. Fibrotic marker assays revealed that either dose of rebamipide decreased the host levels of Procol-III and HA that had become elevated due to the CCl4. At the higher dose tested, rebamipide appeared to be able to permit the hosts to have a normal liver histology and to minimize any CCl4-induced collagen precipitation in the liver. Lastly, the use of rebamipide was seen to be associated with significant increases in liver levels of both PGE2 and the anti-inflammatory cytokine IL-10. Based on these findings, it is concluded that rebamipide can retard hepatic fibrosis induced by CCl4 and that this effect may, in part, be mediated by an induction of PGE2 and IL-10 in the liver itself.

Inhibition of soluble epoxide hydrolase attenuates hepatic fibrosis and endoplasmic reticulum stress induced by carbon tetrachloride in mice

Liver fibrosis is a pathological condition in which chronic inflammation and changes to the extracellular matrix lead to alterations in hepatic tissue architecture and functional degradation of the liver. Inhibitors of the enzyme soluble epoxide hydrolase (sEH) reduce fibrosis in the heart, pancreas and kidney in several disease models. In this study, we assess the effect of sEH inhibition on the development of fibrosis in a carbon tetrachloride (CCl4)-induced mouse model by monitoring changes in the inflammatory response, matrix remolding and endoplasmic reticulum stress. The sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) was administered in drinking water. Collagen deposition in the liver was increased five-fold in the CCl4-treated group, and this was returned to control levels by TPPU treatment. Hepatic expression of Col1a2 and 3a1 mRNA was increased over fifteen-fold in the CCl4-treated group relative to the Control group, and this increase was reduced by 50% by TPPU treatment. Endoplasmic reticulum (ER) stress observed in the livers of CCl4-treated animals was attenuated by TPPU treatment. In order to support the hypothesis that TPPU is acting to reduce the hepatic fibrosis and ER stress through its action as a sEH inhibitor we used a second sEH inhibitor, trans-4-{4-[3-(4-trifluoromethoxy-phenyl)-ureido]-cyclohexyloxy}-benzoic acid (t-TUCB), and sEH null mice. Taken together, these data indicate that the sEH may play an important role in the development of hepatic fibrosis induced by CCl4, presumably by reducing endogenous fatty acid epoxide chemical mediators acting to reduce ER stress.

Celecoxib attenuates hepatic cirrhosis through inhibition of epithelial-to-mesenchymal transition of hepatocytes

BACKGROUND AND AIM

The epithelial-mesenchymal transition (EMT) of hepatocytes is a key step for hepatic fibrosis and cirrhosis. Long-term administration of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, can ameliorate hepatic fibrosis. This research aimed to examine the effect of celecoxib on the EMT of hepatocytes during the development of liver cirrhosis.

METHODS

Cirrhotic liver model of rat was established by peritoneal injection of thiacetamide (TAA). Thirty-six rats were randomly assigned to control, TAA, and TAA + celecoxib groups. Hepatic expressions of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), COX-2, prostaglandin E2 (PGE2 ), matrix metalloproteinase (MMP)-2 and -9, transforming growth factor-β1 (TGF-β1), Phospho-Smad2/3, Snail1, α-smooth muscle actin (α-SMA), vimentin, collagen I, fibroblast-specific protein (FSP-1), E-cadherin and N-cadherin were quantitated. Hepatic fibrosis was assessed by the visible hepatic fibrotic areas and Ishak's scoring system.

RESULTS

Exposed to TAA treatment, hepatocytes underwent the process of EMT during hepatic fibrosis. Compared with those in TAA group, celecoxib significantly downregulated the hepatic expressions of TNF-α, IL-6, COX-2, PGE2 , MMP-2, MMP-9, TGF-β1, Phospho-Smad2/3, Snail1, α-SMA, FSP-1, and vimentin while greatly restoring the levels of E-cadherin. The fibrotic areas and collagen I levels of TAA + celecoxib group were much lower than those in TAA group.

CONCLUSIONS

Celecoxib could ameliorate hepatic fibrosis and cirrhosis in TAA-rat model through suppression of the mesenchymal biomarkers in the hepatocytes while restoring the levels of their epithelial biomarkers. The inhibitory effect of celecoxib on the EMT of hepatocytes is associated with reduction of intrahepatic inflammation, preservation of normal basement matrix, and inhibition of TGF-β1/Smad pathway.

Celecoxib ameliorates portal hypertension of the cirrhotic rats through the dual inhibitory effects on the intrahepatic fibrosis and angiogenesis

BACKGROUND

Increased intra-hepatic resistance to portal blood flow is the primary factor leading to portal hypertension in cirrhosis. Up-regulated expression of cyclooxygenase-2 (COX-2) in the cirrhotic liver might be a potential target to ameliorate portal hypertension.

OBJECTIVE

To verify the effect of celecoxib, a selective inhibitor of COX-2, on portal hypertension and the mechanisms behind it.

METHODS

Cirrhotic liver model of rat was established by peritoneal injection of thiacetamide (TAA). 36 rats were randomly assigned to control, TAA and TAA+celecoxib groups. Portal pressures were measured by introduction of catheters into portal vein. Hepatic fibrosis was assessed by the visible hepatic fibrotic areas and mRNAs for collagen III and α-SMA. The neovasculature was determined by hepatic vascular areas, vascular casts and CD31 expression. Expressions of COX-2, vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2) and related signal molecules were quantitated.

RESULTS

Compared with TAA group, the portal pressure in TAA+celecoxib group was significantly decreased by 17.8%, p<0.01. Celecoxib treatment greatly reduced the tortuous hepatic portal venules. The data of fibrotic areas, CD31expression, mRNA levels of α-SMA and collagen III in TAA+celecoxib group were much lower than those in TAA group, p<0.01. Furthermore, the up-regulation of hepatic mRNA and protein levels of VEGF, VEGFR-2 and COX-2 induced by TAA was significantly inhibited after celecoxib treatment. The expressions of prostaglandin E2 (PGE2), phosphorylated extracellular signal-regulated kinase (p-ERK), hypoxia-inducible factor-1α (HIF-1α), and c-fos were also down-regulated after celecoxib treatment.

CONCLUSIONS

Long term administration of celecoxib can efficiently ameliorate portal hypertension in TAA rat model by its dual inhibitory effects on the intrahepatic fibrosis and angiogenesis. The anti-angiogenesis effect afforded by celecoxib may attribute to its modulation on VEGF/VEGFR-2 through the down-regulation of integrated signal pathways involving PGE2- HIF-1α- VEGF and p-ERK- c-fos- VEGFR-2.

Celecoxib, a selective cyclooxygenase-2 inhibitor, lowers plasma cholesterol and attenuates hepatic lipid peroxidation during carbon-tetrachloride-associated hepatotoxicity in rats

Cyclooxygenase-2 (COX-2) expression and prostaglandin production are suggested to play important, complex roles in the pathogenesis of various liver diseases. Studies on the effects of COX-2 inhibitors on the progression of liver fibrosis present controversial results, and the proposed therapeutic potential of these agents in chronic liver disease is predicated largely on their effectiveness in modulating hepatic stellate cell activation in vitro. This study investigated the modulatory effect of celecoxib, a selective COX-2 inhibitor, in CCl(4)-mediated hepatotoxicity in rats. Thirty Wistar albino rats, weighing 120-180 g, were assigned into five groups of 6 rats/group. Groups 1 and 2 received saline (10 mL/kg) and CCl(4) (80 mg/kg), respectively. Group 3 was given celecoxib (5.7 mg/kg), whereas groups 4 and 5 were pretreated with 2.9 and 5.7 mg/kg/day of celecoxib, respectively, 1 hour before CCl(4) treatment. Plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities increased significantly by 118.5, 150.0, and 51.3%, respectively, with an accompanying decrease (P < 0.05) in total protein and albumin after CCl(4) treatment. Hepatotoxicity was associated with a significant increase in plasma cholesterol, hepatic lipid peroxidation (LPO), and severe hepatic necrosis with marked fatty and cellular (i.e., mononuclear cells) infiltration. Although celecoxib neither reduced CCl(4)-induced increases in marker enzymes of hepatotoxicity nor significantly attenuated hepatic necrosis, it, however, was effective in reducing elevated cholesterol by 16.5 and 20.8% and LPO by 12.9 and 35.5% at 2.9 and 5.7 mg/kg, respectively. Data suggest that COX-2 inhibitors may be effective in controlling hypercholesterolemia and peroxidative changes associated with liver injury.

Involvement of cytosolic phospholipase A2 alpha signalling pathway in spontaneous and transforming growth factor-beta-induced activation of rat hepatic stellate cells

BACKGROUND

Hepatic stellate cells (HSCs) are extracellular matrix-producing cells that play a pivotal role in liver fibrogenesis. During liver injury and when cells are placed in vitro, HSCs undergo phenotypic transition from quiescent retinoid-storing cells to activated retinoid-deficient myofibroblast-like cells. Although several mediators including reactive oxygen species, platelet derived growth factor, transforming growth factor-beta (TGF-β) and tumour necrosis factor-alpha (TNF-α) were implicated in HSC activation, the cellular signalling pathways that regulate this process remain incompletely defined.

AIMS

The objectives of this study were to evaluate the role of cytosolic phospholipase A(2) alpha (cPLA(2)α) and peroxisome proliferator-activated receptor-beta/delta (PPAR-β/δ) in HSC activation.

METHODS

Rat HSCs were isolated, purified, cultured and stimulated with TGF-β1 in the presence or absence of the selective cPLA(2)α inhibitor, arachidonyltrifluoromethyl ketone (AACOCF(3)). The activation status of HSC was evaluated by immunofluorescent staining of alpha-smooth muscle actin (α-SMA) and by measuring the expression of cPLA(2)α, cyclooxygenase 2 (COX-2) and PPAR-β/δ using western blot analysis.

RESULTS

Rapid and significant increase in cPLA(2)α expression was observed during activation of HSCs. These events preceded the elevation of PPAR-β/δ and the expression of α-SMA. Elevated expression of cPLA(2)α, but not COX-2, was also observed during TGF-β-induced HSC activation. The TGF-β-induced α-SMA expression was blocked by AACOCF(3). Furthermore, transfection of a cPLA(2)α expression vector enhanced the transcription activity of PPAR-β/δ and the expression of α-SMA in HSCs.

CONCLUSION

cPLA(2)α-mediated induction of PPAR-β/δ is a novel intracellular signalling pathway in spontaneous and TGF-β induced activation of HSCs and could be a potential therapeutic target for the treatment of liver fibrosis.

Selective COX-2 inhibitor celecoxib inhibits liver fibrogenesis in rats

AIM: To investigate whether celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, protects from carbon tetrachloride (CCl4)-induced liver fibrosis in rats.

METHODS: Fifty male SD rats were randomly divided into six groups. Group A (n = 10) was subcutaneously injected with 50% 1 mL/kg CCl4 olive oil solution, twice per week, to induce hepatic fibrosis and intragastrically given saline. Groups B (n = 10), C (n = 10) and D (n = 10) were also subjected to induction of hepatic fibrosis and intragastrically given celecoxib 15 mg/kg once daily from day 1, week 3, and week 5 after CCl4 injection. Group E (n = 5) was subcutaneously injected with equal volume of olive oil and intragastrically given the same dose of celecoxib, while group F (n = 5) was subcutaneously injected with equal volume of olive oil and intragastrically given saline. The treatment lasted for 8 weeks. At the end of the experiment, blood samples were collected to measure serum ALT, HA and LN levels, while hepatic tissue samples were taken to evaluate the degree of liver fibrosis by HE staining and to detect the expression of type I collagen, alpha SMA, COX-1, and COX-2 by immunohistochemistry.

RESULTS: Compared to group F, significant hepatic fibrosis was observed in group A (P < 0.01). Compared to group A, liver fibrosis was significantly reduced (P < 0.01), serum ALT, HA and LN levels significantly decreased (100.4 U/L ± 8.7 U/L vs 287.8 U/L ± 9.6 U/L, 189.6 μg/L ± 83.0 μg/L vs 382.6 μg/L ± 136.0 μg/L, 71.4 μg/L ± 4.6 μg/L vs 108.7 μg/L ± 9.8 μg/L, all P < 0.01), and the areas positive for type I collagen, alpha SMA, and COX-2 were reduced (all P < 0.01). The above parameters showed significant differences among groups B, C and D (all P < 0.05). No significant differences were observed in the above parameters between groups E and F. COX-1-positive area showed no significant difference among each group.

CONCLUSION: COX-2 plays an important role in liver fibrogenesis. Celecoxib can reduce or prevent liver fibrosis in a time-dependent manner probably by inhibiting hepatic stellate cell activation and inflammation.

Early and late postnatal myocardial and vascular changes in a protein restriction rat model of intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a risk factor for cardiovascular disease in later life. Early structural and functional changes in the cardiovascular system after IUGR may contribute to its pathogenesis. We tested the hypothesis that IUGR leads to primary myocardial and vascular alterations before the onset of hypertension. A rat IUGR model of maternal protein restriction during gestation was used. Dams were fed low protein (LP; casein 8.4%) or isocaloric normal protein diet (NP; casein 17.2%). The offspring was reduced to six males per litter. Immunohistochemical and real-time PCR analyses were performed in myocardial and vascular tissue of neonates and animals at day 70 of life. In the aortas of newborn IUGR rats expression of connective tissue growth factor (CTGF) was induced 3.2-fold. At day 70 of life, the expression of collagen I was increased 5.6-fold in aortas of IUGR rats. In the hearts of neonate IUGR rats, cell proliferation was more prominent compared to controls. At day 70 the expression of osteopontin was induced 7.2-fold. A 3- to 7-fold increase in the expression of the profibrotic cytokines TGF-β and CTGF as well as of microfibrillar matrix molecules was observed. The myocardial expression and deposition of collagens was more prominent in IUGR animals compared to controls at day 70. In the low-protein diet model, IUGR leads to changes in the expression patterns of profibrotic genes and discrete structural abnormalities of vessels and hearts in adolescence, but, with the exception of CTGF, not as early as at the time of birth. Invasive and non-invasive blood pressure measurements confirmed that IUGR rats were normotensive at the time point investigated and that the changes observed occurred independently of an increased blood pressure. Hence, altered matrix composition of the vascular wall and the myocardium may predispose IUGR animals to cardiovascular disease later in life.

Transgenic mice expressing cyclooxygenase-2 in hepatocytes reveal a minor contribution of this enzyme to chemical hepatocarcinogenesis

Cyclooxygenase-2 (COX-2) has been associated with cell growth regulation, tissue remodeling, and carcinogenesis. Ectopic expression of COX-2 in hepatocytes constitutes a nonphysiological condition ideal for evaluating the role of prostaglandins (PGs) in liver pathogenesis. The effect of COX-2-dependent PGs in chronic liver disease, hepatitis, fibrosis, and chemical hepatocarcinogenesis, has been investigated in transgenic (Tg) mice that express human COX-2 in hepatocytes and in Tg hepatic human cell lines. We have used three different complementary approaches: i) diethylnitrosamine (DEN)-induced chemical hepatocarcinogenesis in COX-2 Tg mice, ii) DEN/phenobarbital treatment of human COX-2 Tg hepatocyte-like cells, and iii) COX-2 Tg hepatocyte-like cells implants in nude mice. The data suggest that PGs produced by COX-2 in hepatocytes promoted mild hepatitis in 60-week-old mice, as assessed by histological examination, but failed to contribute to the development of liver fibrogenesis after methionine- and choline-deficient diet treatment. Moreover, liver injury, collagen content, and hepatic stellate cell activation were equally severe in wild-type and COX-2 Tg mice. The contribution of COX-2-dependent PGs to the development of DEN-induced hepatocarcinogenesis was evaluated in Tg mice, Tg hepatocyte-like cells, and nude mice and the analysis revealed that COX-2 expression favors the development of preneoplastic foci without affecting malignant transformation. Endogenous COX-2 expression in wild-type mice is a late event in the development of hepatocellular carcinoma.

N-methyl-4-isoleucine cyclosporine attenuates CCl -induced liver fibrosis in rats by interacting with cyclophilin B and D

BACKGROUND AND AIM

N-methyl-4-isoleucine cyclosporine (NIM811), a new analogue of cyclosporine A, can inhibit collagen deposition in vitro and reduce liver necrosis in a bile-duct-ligation animal model. However, whether NIM811 effects on CCl(4) -induced rat liver fibrosis, and the related mechanism has not been determined.

METHODS

A liver fibrosis model was induced in Wistar rats using CCl(4) for 6 weeks. Meanwhile, two different doses of NIM811 (low-dose 10 mg/kg and high-dose 20 mg/kg) were given to the CCl(4) -treated rats. Liver fibrosis was then evaluated according to histopathological scoring and liver hydroxyproline content. Serum alanine aminotransferase, aspartate aminotransferase and albumin levels, expression of matrix metalloproteinase-13, tissue inhibitor of metalloproteinase-1, α-smooth muscle actin and cyclophilin B and D in liver tissue were determined. Cyclophilin B and D were also studied in an hepatic stellate cell line.

RESULTS

Hydroxyproline content was decreased in both NIM811 groups compared with the model (P < 0.05). Liver necrosis and fibrosis were also attenuated in the NIM811 groups. NIM811 suppressed the expression of tissue inhibitor of metalloproteinase-1, transforming growth factor beta mRNA and α-smooth muscle actin protein in liver tissue. Expression of cyclophilin B in the fibrosis model was increased compared with the normal group (P < 0.05), and was decreased significantly in the low-dose NIM811 treatment group (P < 0.05), which indicated that cyclophilin B might have a profibrotic effect. In vitro studies revealed that cyclophilin B and/or D knockout were associated with collagen inhibition.

CONCLUSIONS

NIM811 attenuates liver fibrosis in a CCl(4)-induced rat liver fibrosis model, which may be related to binding with cyclophilin B and D.

High-dose enalapril treatment reverses myocardial fibrosis in experimental uremic cardiomyopathy

AIMS

Patients with renal failure develop cardiovascular alterations which contribute to the higher rate of cardiac death. Blockade of the renin angiotensin system ameliorates the development of such changes. It is unclear, however, to what extent ACE-inhibitors can also reverse existing cardiovascular alterations. Therefore, we investigated the effect of high dose enalapril treatment on these alterations.

METHODS

Male Sprague Dawley rats underwent subtotal nephrectomy (SNX, n = 34) or sham operation (sham, n = 39). Eight weeks after surgery, rats were sacrificed or allocated to treatment with either high-dose enalapril, combination of furosemide/dihydralazine or solvent for 4 weeks. Heart and aorta were evaluated using morphometry, stereological techniques and TaqMan PCR.

RESULTS

After 8 and 12 weeks systolic blood pressure, albumin excretion, and left ventricular weight were significantly higher in untreated SNX compared to sham. Twelve weeks after SNX a significantly higher volume density of cardiac interstitial tissue (2.57±0.43% in SNX vs 1.50±0.43% in sham, p<0.05) and a significantly lower capillary length density (4532±355 mm/mm(3) in SNX vs 5023±624 mm/mm(3) in sham, p<0.05) were found. Treatment of SNX with enalapril from week 8-12 significantly improved myocardial fibrosis (1.63±0.25%, p<0.05), but not capillary reduction (3908±486 mm/mm(3)) or increased intercapillary distance. In contrast, alternative antihypertensive treatment showed no such effect. Significantly increased media thickness together with decreased vascular smooth muscles cell number and a disarray of elastic fibres were found in the aorta of SNX animals compared to sham. Both antihypertensive treatments failed to cause complete regression of these alterations.

CONCLUSIONS

The study indicates that high dose ACE-I treatment causes partial, but not complete, reversal of cardiovascular changes in SNX.

Increased expression of cyclooxygenase-2 is associated with the progression to cirrhosis

BACKGROUND/AIMS

To investigate the degree of cyclooxygenase-2 (COX-2) protein expression in chronic hepatitis and cirrhosis.

METHODS

COX-2 protein expression was evaluated in 43 cases of chronic hepatitis and 24 cases of cirrhosis using immunohistochemical techniques. The COX-2 immunohistochemical staining score was assessed using the scoring systems of Pazirandeh et al and Qiu et al. and each scoring system was based on a sum of the parameters of staining intensity and distribution.

RESULTS

The mean COX-2 expression scores in chronic hepatitis and cirrhosis were 2.5 ± 1.3 vs. 3.3 ± 1.1 (p = 0.008), and 3.2 ± 2.0 vs. 4.5 ± 1.7 (p = 0.006), respectively, based on the Pazirandeh et al. and Qiu et al. scoring systems. The percentage samples of high COX-2 expression score (4 to 5) in chronic hepatitis and cirrhosis were 16.3% vs. 45.8% (p = 0.022), and 23.3% vs. 50% (p = 0.021), respectively, based on the two scoring systems. The mean COX-2 expression scores based on the severity of hepatic fibrosis scored using Ishak's modified staging system (fibrosis score 0 to 3 vs. 4 to 6) were 2.4 ± 1.3 vs. 3.2 ± 1.1 (p = 0.009), and 3.1 ± 2.0 vs. 4.3 ± 1.8 (p = 0.009), respectively, based on the two scoring systems.

CONCLUSIONS

COX-2 expression was significantly higher in liver cirrhosis group than in chronic hepatitis. COX-2 expression scores according to Ishak's staging was significantly higher in the advanced fibrosis group. COX-2 may play a role in the progression of hepatic fibrosis.

Feedback amplification of fibrosis through matrix stiffening and COX-2 suppression

Tissue stiffening is a hallmark of fibrotic disorders but has traditionally been regarded as an outcome of fibrosis, not a contributing factor to pathogenesis. In this study, we show that fibrosis induced by bleomycin injury in the murine lung locally increases median tissue stiffness sixfold relative to normal lung parenchyma. Across this pathophysiological stiffness range, cultured lung fibroblasts transition from a surprisingly quiescent state to progressive increases in proliferation and matrix synthesis, accompanied by coordinated decreases in matrix proteolytic gene expression. Increasing matrix stiffness strongly suppresses fibroblast expression of COX-2 (cyclooxygenase-2) and synthesis of prostaglandin E(2) (PGE(2)), an autocrine inhibitor of fibrogenesis. Exogenous PGE(2) or an agonist of the prostanoid EP2 receptor completely counteracts the proliferative and matrix synthetic effects caused by increased stiffness. Together, these results demonstrate a dominant role for normal tissue compliance, acting in part through autocrine PGE(2), in maintaining fibroblast quiescence and reveal a feedback relationship between matrix stiffening, COX-2 suppression, and fibroblast activation that promotes and amplifies progressive fibrosis.

Antifibrotic and fibrolytic properties of celecoxib in liver damage induced by carbon tetrachloride in the rat

BACKGROUND

Transforming growth factor-beta (TGF-beta) plays a pivotal role in liver fibrosis, because it activates hepatic stellate cells, stimulating extracellular matrix deposition. Cyclooxygenase-2 (COX-2) has been associated with TGF-beta because its inhibition decreases TGF-beta expression and collagen production in some cultured cell types.

AIM

The aim of this work was to evaluate the ability of celecoxib (a selective COX-2 inhibitor) to prevent and to reverse the liver fibrosis induced by CCl(4).

METHODS

We established experimental groups of rats including vehicle and drug controls, damage induced by chronic CCl(4) administration and CCl(4) plus pharmacological treatment in both prevention and reversion models. We determined: alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transpeptidase, COX and metalloproteinase-2 and -9 activities, lipid peroxidation, glutathione levels, glycogen and collagen content and TGF-beta expression.

RESULTS

Celecoxib prevented and aided to the recovery of livers with necrotic and cholestatic damage. Celecoxib exhibited anti-oxidant properties by restoring the redox equilibrium (lipid peroxidation and glutathione levels). Glycogen was decreased by CCl(4), while celecoxib partially prevented and reversed this effect. Celecoxib inhibited COX-2 activity, decreased TGF-beta expression, induced metalloproteinase-2 activity and, consequently, prevented and reversed collagen accumulation.

CONCLUSION

Our findings indicate that celecoxib exerts strong antifibrogenic and fibrolytic effects in the CCl(4) model of cirrhosis.

The anti-inflammatory effect of celecoxib does not prevent liver fibrosis in bile duct-ligated rats

BACKGROUND/AIMS

Celecoxib was used in the treatment of inflammation in patients with cirrhosis. However, data on the progression of liver fibrosis after treatment by celecoxib are not available. This study aims to elucidate the effects of celecoxib on cholestatic liver fibrosis in rats.

METHODS

Rats underwent bile duct ligation (BDL) for 1 or 2 weeks to induce hepatic fibrosis. Celecoxib was introduced on day 1 after operation. The effects of celecoxib were assessed by comparison of the severity of hepatic fibrosis.

RESULTS

Infiltration of inflammatory cells and proliferation of bile ducts was seen after 1 week of BDL and fibrosis was induced after 2 weeks. Reduced alanine aminotransferase (ALT) levels and blunted expression of inflammatory factors [tumour necrosis factor-alpha, interleukin (IL)-1beta and IL-6] were seen in the liver of BDL-treated rats that received celecoxib at week 1. Although celecoxib was sufficient in suppressing the cyclo-oxygenase (COX)-2 expression in the control organ (kidney), it failed to suppress the enhanced hepatic COX-2 expression. At week 2, celecoxib did not alter the ALT level, the severity of fibrosis and hepatic collagen contents. This was associated with unchanged alpha-smooth muscle actin protein expression and tissue inhibitor of metalloproteinase-2 (TIMP-2), matrix metalloproteinase (MMP)-2 and MMP-9 mRNA expressions in the liver. Celecoxib had no effect on the BDL-dependent increase in bilirubin levels at any time point.

CONCLUSIONS

The present study provides morphological and molecular biological evidences for the role of celecoxib in cholestatic liver fibrosis. Celecoxib protects against hepatic inflammation in the early stage of BDL rats, but does not have an effect on liver fibrosis.

Celecoxib exacerbates hepatic fibrosis and induces hepatocellular necrosis in rats treated with porcine serum

Inhibitors against cyclooxygenase-2 (COX-2), an inducible enzyme that catalyzes prostaglandin synthesis, are widely used in clinical. However, the potential hepatic toxicity of COX-2 inhibitors remains incompletely investigated. We report in this study that a clinically available COX-2 inhibitor, celecoxib, exacerbates porcine serum (PS)-induced hepatic fibrosis and induces hepatocellular necrosis in an experimental liver fibrosis model. Histological results revealed that although celecoxib by itself did not cause notable hepatic damages, it markedly enhanced hepatic fibrosis that had been initiated by PS. While PS alone did not cause any necrotic change in liver cells, the addition of celecoxib resulted in hepatocellular necrosis in PS-treated animals. Notably, celecoxib enhanced reduction of plasma prostaglandin E(2) (PGE(2)) levels induced by PS. Taken together, our results indicate that treatment with celecoxib may exacerbate liver fibrosis and cause hepatocellular necrosis. This may be associated with reduction in PGE(2) as an inheritance consequence of inhibition of COX-2.

Effect of selective cyclooxygenase-2 inhibitor meloxicam on liver fibrosis in rats with ligated common bile ducts

AIM

Cholestasis triggers fibrogenesis in the liver. Hepatic cyclooxygenase-2 (COX-2) expression increases in various chronic liver diseases caused either by viruses or toxins. We hypothesized that selective COX-2 inhibitor meloxicam could suppress inflammation and fibrogenesis in a rat model of cholestasis induced by bile duct ligation (BDL).

METHODS

Forty-three Sprague-Dawley rats were assigned to one of four treatment groups (sham-operation, BDL, daily meloxicam injections following BDL, and daily meloxicam injection without BDL). Liver histopathology was analyzed with hematoxylin-eosin and Masson's trichrome staining. The expression of alpha-smooth muscle actin (alpha-SMA), transforming growth factor-beta1 (TGF-beta1), and COX-2 were measured with immunohistochemical staining. The levels of COX-2, TGF-beta1, and matrix metalloproteinase-9 (MMP-9) production were measured with the Western blot method and an enzyme immunoassay.

RESULTS

Meloxicam treatment attenuated the expression of alpha-SMA, TGF-beta1, and COX-2 in rats that were treated with BDL for 3 weeks. This was associated with a marked reduction in collagen accumulation and histological improvement. In addition, meloxicam treatment was found to downregulate the levels of hepatic COX-2, TGF-beta1, and MMP-9 production.

CONCLUSION

Cholestasis in BDL rats induces hepatic COX-2 expression. Selective COX-2 inhibitor meloxicam reduces BDL-induced hepatic fibrosis, and this is associated with reduced hepatic TGF-beta1 expression as well as decreased cyclooxygenase activity in the liver.

Elucidation of the role of COX-2 in liver fibrogenesis using transgenic mice

Hepatic COX-2 overexpression is sufficient to induce hepatitis, but its role on liver fibrosis remains unknown. We aim to elucidate possible biological effects of COX-2 in liver fibrosis using both gain-of-function and loss-of-function mouse models. COX-2 transgenic (TG) mice that specifically overexpress the human COX-2 cDNA in the liver, knockout (KO), and wild type (WT) mice were studied in two different murine fibrosis models induced by carbon tetrachloride (CCl(4)) injection or methionine and choline-deficient (MCD) diet. Liver injury was assessed by serum ALT and bilirubin levels and histological examination. Hepatic collagen content was determined by picrosirius red stain morphometry assay and quantitation of hydroxyproline. Hepatic stellate cell (HSC) activation was determined by immunohistochemical analysis of alpha-smooth muscle actin (alpha-SMA). mRNA expression of fibrogenic genes was assayed by real-time quantitative PCR. COX-2 protein was overexpressed in the liver of TG mice compared with WT littermates. CCl(4) or MCD-induced liver fibrotic injury was equally severe in TG and WT mice, as demonstrated by similar elevated levels of hepatic collagen contents. Enhanced COX-2 expression in TG liver did not affect HSC activation and fibrogenic gene expression upon CCl(4) or MCD treatment. Importantly, CCl(4)-treated KO mice did not show significant difference in liver fibrotic damage and fibrogenic gene expression compared with the WT counterparts. This is the first report on the effect of COX-2 in liver fibrosis based on genetic mouse models. The results suggest that COX-2 does not appear to mediate the development of liver fibrosis.

Renal injury in streptozotocin-diabetic Ren2-transgenic rats is mainly dependent on hypertension, not on diabetes

Induction of streptozotocin (STZ) diabetes in hypertensive rats transgenic for the mouse ren-2 gene (TGR) has been described as a model of progressive diabetic nephropathy. We investigated the long-term course of STZ diabetes in TGR and appropriate Sprague-Dawley control rats (SD) and tested the role of angiotensin-dependent hypertension by treating rats with the angiotensin II type 1 receptor blocker losartan (1 mg·kg−1·day−1) via osmotic minipumps. Five weeks after STZ injection, diabetes developed in TGR and SD. Urinary albumin excretion was increased by diabetes and, to a much higher degree, by hypertension. The effects of hypertension and diabetes were not additive, and only the effects of hypertension were ameliorated by losartan. A similar pattern was observed for cell proliferation and macrophage infiltration in the kidney. In contrast, the effects of hypertension and diabetes on glomerular collagen IV accumulation were additive 5 wk after STZ injection. In a long-term study for 20 wk after STZ, survival was better in STZ-treated TGR than in normoglycemic TGR, whereas all SD survived. Impaired creatinine clearance and increased macrophage infiltration as well as glomerular and interstitial matrix deposition were prominent in TGR compared with SD, regardless of the presence or absence of diabetes. In conclusion, STZ diabetes in TGR may be useful to study glomerular and interstitial matrix deposition early in the course of diabetes. However, the long-term course of this animal model resembles severe hypertensive nephrosclerosis, rather than progressive diabetic nephropathy.