Role of preferential cyclooxygenase-2 inhibition by meloxicam in ischemia/reperfusion injury of the rat liver

Effect of the Non-steroidal Anti-inflammatory Drug Diclofenac on Ischemia-Reperfusion Injury in Rat Liver: A Nitric Oxide-Dependent Mechanism

Ischemia/reperfusion injury (IRI) is an inevitable complication of liver surgery and transplantation. The purpose of this study was to examine the beneficial effects of diclofenac on hepatic IRI and the mechanism behind it. Wistar rats' livers were subjected to warm ischemia for 60 min followed by 24 h of reperfusion. Diclofenac was administered intravenously 15 min before ischemia at 10, 20, and 40 mg/kg body weight. To determine the mechanism of diclofenac protection, the NOS inhibitor L-Nitro-arginine methyl ester (L-NAME) was administered intravenously 10 min after diclofenac injection (40 mg/kg). Liver injury was evaluated by aminotransferases (ALT and AST) activities and histopathological analysis. Oxidative stress parameters (SOD, GPX, MPO, GSH, MDA, and PSH) were also determined. Then, eNOS gene transcription and p-eNOS and iNOS protein expressions were evaluated. The transcription factors PPAR-γ and NF-κB in addition to the regulatory protein IκBα were also investigated. Finally, the gene expression levels of inflammatory (COX-2, IL-6, IL-1β, IL-18, TNF-α, HMGB-1, and TLR-4) and apoptosis (Bcl-2 and Bax) markers were measured. Diclofenac, at the optimal dose of 40 mg/kg, decreased liver injury and maintained histological integrity. It also reduced oxidative stress, inflammation, and apoptosis. Its mechanism of action essentially depended on eNOS activation rather than COX-2 inhibition, since pre-treatment with L-NAME abolished all the protective effects of diclofenac. To our knowledge, this is the first study demonstrating that diclofenac protects rat liver against warm IRI through the induction of NO-dependent pathway. Diclofenac reduced oxidative balance, attenuated the activation of the subsequent pro-inflammatory response and decreased cellular and tissue damage. Therefore, diclofenac could be a promising molecule for the prevention of liver IRI.

Eicosanoids and other oxylipins in liver injury, inflammation and liver cancer development

Liver cancer is a malignancy developed from underlying liver disease that encompasses liver injury and metabolic disorders. The progression from these underlying liver disease to cancer is accompanied by chronic inflammatory conditions in which liver macrophages play important roles in orchestrating the inflammatory response. During this process, bioactive lipids produced by hepatocytes and macrophages mediate the inflammatory responses by acting as pro-inflammatory factors, as well as, playing roles in the resolution of inflammation conditions. Here, we review the literature discussing the roles of bioactive lipids in acute and chronic hepatic inflammation and progression to cancer.

COX-2 Expression in Hepatocytes Improves Mitochondrial Function after Hepatic Ischemia-Reperfusion Injury

Cyclooxygenase 2 (COX-2) is a key enzyme in prostanoid biosynthesis. The constitutive hepatocyte expression of COX-2 has a protective role in hepatic ischemia-reperfusion (I/R) injury (IRI), decreasing necrosis, reducing reactive oxygen species (ROS) levels, and increasing autophagy and antioxidant and anti-inflammatory response. The physiopathology of IRI directly impacts mitochondrial activity, causing ATP depletion and being the main source of ROS. Using genetically modified mice expressing human COX-2 (h-COX-2 Tg) specifically in hepatocytes, and performing I/R surgery on the liver, we demonstrate that COX-2 expression has a beneficial effect at the mitochondrial level. Mitochondria derived from h-COX-2 Tg mice livers have an increased respiratory rate associated with complex I electron-feeding pathways compared to Wild-type (Wt) littermates, without affecting complex I expression or assembly. Furthermore, Wt-derived mitochondria show a loss of mitochondrial membrane potential (ΔΨm) that correlates to increased proteolysis of fusion-related OPA1 through OMA1 protease activity. All these effects are not observed in h-COX-2 Tg mitochondria, which behave similarly to the Sham condition. These results suggest that COX-2 attenuates IRI at a mitochondrial level, preserving the proteolytic processing of OPA1, in addition to the maintenance of mitochondrial respiration.

Therapeutic implications of cyclooxygenase (COX) inhibitors in ischemic injury

INTRODUCTION

Ischemia-reperfusion injury (IRI) is the inexplicable aggravation of cellular dysfunction that results in blood flow restoration to previously ischemic tissues. COX mediates the oxidative conversion of AA to various prostaglandins and thromboxanes, which are involved in various physiological and pathological processes. In the pathophysiology of I/R injuries, COX has been found to play an important role. I/R injuries affect most vital organs and are characterized by inflammation, oxidative stress, cell death, and apoptosis, leading to morbidity and mortality.

MATERIALS AND METHODS

A systematic literature review of Bentham, Scopus, PubMed, Medline, and EMBASE (Elsevier) databases was carried out to understand the Nature and mechanistic interventions of the Cyclooxygenase modulations in ischemic injury. Here, we have discussed the COX Physiology and downstream signalling pathways modulated by COX, e.g., Camp Pathway, Peroxisome Proliferator-Activated Receptor Activity, NF-kB Signalling, PI3K/Akt Signalling in ischemic injury.

CONCLUSION

This review will discuss the various COX types, specifically COX-1 and COX-2, which are involved in developing I/R injury in organs such as the brain, spinal cord, heart, kidney, liver, and intestine.

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.

Effects of endothelin receptor blockade and COX inhibition on intestinal I/R injury in a rat model: Experimental research

BACKGROUND

Intestinal ischemia is a highly morbid and mortal condition with no specific treatment. The present study aimed to investigate the effects of cyclooxygenase (COX) inhibition synchronized with nitric oxide (NO) release and endothelin (ET) receptor blockade on oxidative stress, inflammation, vasoconstriction, and bacterial translocation which occur during ischemia-reperfusion (I/R) injury in in-vivo rat intestinal I/R model.

MATERIALS AND METHODS

36 male Wistar rats were randomly divided into six groups (n = 6). Superior mesenteric artery blood flow (SMABF) was recorded; SMA was occluded for 30 min; SMABF was re-recorded at the beginning of the reperfusion phase. Rats were sacrificed after the reperfusion period of 60 min. Blood and tissue samples were obtained. Acetylsalicylic acid (ASA), NO-ASA, flurbiprofen (FLUR), and Tezosentan (TS) were administered 15 min after ischemia. Histopathological examination, bacterial translocation, and biochemical analysis were performed in plasma and tissue samples.

RESULTS

SMABF difference, mean Chiu's score and bacterial translocation were increased in the I/R group and decreased in the treatment groups. Plasma LDH, transaminases, intestinal fatty acid-binding protein (I-FABP), TNF-α, ICAM-1, interferon-gamma (IFN-Ɣ) and proinflammatory cytokine panel; tissue lipid peroxidation, MPO, xanthine oxidase (XO), NO, NF-kB levels and the expression of TNF-α were significantly elevated in the I/R group and markedly decreased in the treatment groups. The tissue antioxidant status was decreased in the I/R group and increased in the treatment groups.

CONCLUSION

It is suggested that NO-ASA, TS, and FLUR can be introduced as promising therapeutics to improve intestinal I/R injury.

INSTITUTIONAL PROTOCOL NO

2018-29-05 (Animal Experimentations Ethics Committee, Hacettepe University).

Protective Role of Hepatocyte Cyclooxygenase-2 Expression Against Liver Ischemia-Reperfusion Injury in Mice

Liver ischemia and reperfusion injury (IRI) remains a serious clinical problem affecting liver transplantation outcomes. IRI causes up to 10% of early organ failure and predisposes to chronic rejection. Cyclooxygenase-2 (COX-2) is involved in different liver diseases, but the significance of COX-2 in IRI is a matter of controversy. This study was designed to elucidate the role of COX-2 induction in hepatocytes against liver IRI. In the present work, hepatocyte-specific COX-2 transgenic mice (hCOX-2-Tg) and their wild-type (Wt) littermates were subjected to IRI. hCOX-2-Tg mice exhibited lower grades of necrosis and inflammation than Wt mice, in part by reduced hepatic recruitment and infiltration of neutrophils, with a concomitant decrease in serum levels of proinflammatory cytokines. Moreover, hCOX-2-Tg mice showed a significant attenuation of the IRI-induced increase in oxidative stress and hepatic apoptosis, an increase in autophagic flux, and a decrease in endoplasmic reticulum stress compared to Wt mice. Interestingly, ischemic preconditioning of Wt mice resembles the beneficial effects observed in hCOX-2-Tg mice against IRI due to a preconditioning-derived increase in endogenous COX-2, which is mainly localized in hepatocytes. Furthermore, measurement of prostaglandin E₂ (PGE₂ ) levels in plasma from patients who underwent liver transplantation revealed a significantly positive correlation of PGE₂ levels and graft function and an inverse correlation with the time of ischemia. Conclusion: These data support the view of a protective effect of hepatic COX-2 induction and the consequent rise of derived prostaglandins against IRI.

A Network Pharmacology Approach to Uncover the Potential Mechanism of Yinchensini Decoction

Objective

To predict and explore the potential mechanism of Yinchensini decoction (YCSND) based on systemic pharmacology.

Method

TCMSP database was searched for the active constituents and related target proteins of YCSND. Cytoscape 3.5.1 was used to construct the active ingredient-target interaction of YCSND and network topology analysis, with STRING online database for protein-protein interaction (PPI) network construction and analysis; and collection from the UniProt database of target protein gene name, with the DAVID database for the gene ontology (GO) functional analysis, KEGG pathway enrichment analysis mechanism and targets of YCSND.

Results

The results indicate the core compounds of YCSND, namely, kaempferol, 7-Methoxy-2-methyl isoflavone, and formononetin. And its core targets are prostaglandin G/H synthase 2, estrogen receptor, Calmodulin, heat shock protein HSP 90, etc. PPI network analysis shows that the key components of the active ingredients of YCSND are JUN, TP53, MARK1, RELA, MYC, and so on. The results of the GO analysis demonstrate that extracellular space, cytosol, and plasma membrane are the main cellular components of YCSND. Its molecular functions are mainly acting on enzyme binding, protein heterodimerization activity, and drug binding. The biological process of YCSND is focused on response to drug, positive regulation of transcription from RNA polymerase II promoter, the response to ethanol, etc. KEGG results suggest that the pathways, including pathways in cancer, hepatitis B, and pancreatic cancer, play a key role in YCSND.

Conclusion

YCSND exerts its drug effect through various signaling pathways and acts on kinds of targets. By system pharmacology, the potential role of drugs and the mechanism of action can be well predicted.

Meloxicam increases epidermal growth factor receptor expression improving survival after hepatic resection in diet-induced obese mice

BACKGROUND

Patients with fatty liver have delayed regenerative responses, increased hepatocellular injury, and increased risk for perioperative mortality. Currently, no clinical therapy exists to prevent liver failure or improve regeneration in patients with fatty liver. Previously we demonstrated that obese mice have markedly reduced levels of epidermal growth factor receptor in liver. We sought to identify pharmacologic agents to increase epidermal growth factor receptor expression to improve hepatic regeneration in the setting of fatty liver resection.

METHODS

Lean (20% calories from fat) and diet-induced obese mice (60% calories from fat) were subjected to 70% or 80% hepatectomy.

RESULTS

Using the BaseSpace Correlation Engine of deposited gene arrays we identified agents that increased hepatic epidermal growth factor receptor. Meloxicam was identified as inducing epidermal growth factor receptor expression across species. Meloxicam improved hepatic steatosis in diet-induced obese mice both grossly and histologically. Immunohistochemistry and Western blot analysis demonstrated that meloxicam pretreatment of diet-induced obese mice dramatically increased epidermal growth factor receptor protein expression in hepatocytes. After 70% hepatectomy, meloxicam pretreatment ameliorated liver injury and significantly accelerated mitotic rates of hepatocytes in obese mice. Recovery of liver mass was accelerated in obese mice pretreated with meloxicam (by 26% at 24 hours and 38% at 48 hours, respectively). After 80% hepatectomy, survival was dramatically increased with meloxicam treatment.

CONCLUSION

Low epidermal growth factor receptor expression is a common feature of fatty liver disease. Meloxicam restores epidermal growth factor receptor expression in steatotic hepatocytes. Meloxicam pretreatment may be applied to improve outcome after fatty liver resection or transplantation with steatotic graft.

Sirtuin 1 Stimulation Attenuates Ischemic Liver Injury and Enhances Mitochondrial Recovery and Autophagy

OBJECTIVES

Hepatic ischemia-reperfusion is a major clinical problem with limited treatment options. The pathophysiology of hepatic ischemia-reperfusion is characterized by mitochondrial dysfunction and cellular energy deficits. Sirtuin 1 is an energy-sensing enzyme known to modulate mitochondrial biogenesis. We hypothesized that pharmacologic activation of sirtuin 1 is protective after hepatic ischemia-reperfusion injury.

DESIGN

Animal study.

SETTING

University-based experimental laboratory.

SUBJECTS

Wild-type C57BL/6 mice.

INTERVENTIONS

C57BL/6 mice were subjected to 60-minute partial hepatic ischemia-reperfusion and posttreated with sirtuin 1 activator, SRT1720 (20 mg/kg), or vehicle. Blood and liver were collected at 24 hours after ischemia-reperfusion for analyses of hepatic injury, adenosine triphosphate levels, mitochondrial mass, autophagy, inflammation, and oxidative stress. H4IIE hepatoma cells and rat primary hepatocytes were incubated with oxyrase to induce hypoxia followed by reoxygenation in the presence or absence of SRT1720 for assessment of mitochondrial mass, mitochondrial membrane potential, and autophagy.

MEASUREMENTS AND MAIN RESULTS

SRT1720 restored the reduction in mitochondrial mass, enhanced autophagy, and preserved adenosine triphosphate levels in the liver after ischemia-reperfusion, which was associated with a decrease in ischemia-reperfusion-induced hepatic injury, apoptosis, and necrosis. Ischemia-reperfusion-induced inflammation was also significantly reduced by SRT1720 as measured by systemic and hepatic cytokine and chemokine levels, as well as a decrease in neutrophil infiltration to the liver. Furthermore, oxidative stress was markedly attenuated in the SRT1720-treated mice compared with the vehicle. SRT1720 treatment increased adenosine triphosphate levels and survival of cultured hepatocytes after hypoxia-reoxygenation. SRT1720 not only increased the mitochondrial mass but also increased mitochondrial membrane potential per cell in cultured hepatocytes after hypoxia-reoxygenation. Moreover, SRT1720 prevented the hypoxia-reoxygenation-induced mitochondrial depolarization and resulted in an enhancement of autophagy in cultured hepatocytes after hypoxia-reoxygenation.

CONCLUSIONS

Pharmacologic stimulation of sirtuin 1 attenuates liver injury after hepatic ischemia-reperfusion by restoring mitochondrial mass and membrane potential, which is associated with the enhancement of autophagy.

Cyclooxygenase-2 Inhibitor Reduces Hepatic Stiffness in Pediatric Chronic Liver Disease Patients Following Kasai Portoenterostomy

PURPOSE

The purpose of this study was to define the role of cyclooxygenase-2 inhibitors (COX-2i) in reducing hepatic fibrosis in pediatric patients with chronic liver disease.

MATERIALS AND METHODS

From September 2009 to September 2010, patients over 2 years old who visited our outpatient clinic for follow-up to manage their chronic liver disease after Kasai portoenterostomy for biliary atresia, were included in this study. Volunteers were assigned to the study or control groups, according to their preference. A COX-2i was given to only the study group after obtaining consent. The degree of hepatic fibrosis (liver stiffness score, LSS) was prospectively measured using FibroScan, and liver function was examined using serum analysis before and after treatment. After 1 year, changes in LSSs and liver function were compared between the two groups.

RESULTS

Twenty-five patients (18 females and 7 males) were enrolled in the study group. The control group included 44 patients (26 females and 18 males). After 1 year, the least square mean values for the LSSs were significantly decreased by 3.91±0.98 kPa (p=0.004) only in the study group. Serum total bilirubin did not decrease significantly in either group.

CONCLUSION

COX-2i treatment improved the LSS in patients with chronic liver disease after Kasai portoenterostomy for biliary atresia.

Synthesis of dihydropyrazole sulphonamide derivatives that act as anti-cancer agents through COX-2 inhibition

COX-2 has long been exploited in the treatment of inflammation and relief of pain; however, research increasingly suggests COX-2 inhibitors might possess potential benefits to thwart tumour processes. In the present study, we designed a series of novel COX-2 inhibitors based on analysis of known inhibitors combined with an in silico scaffold modification strategy. A docking simulation combined with a primary screen in vitro were performed to filter for the lead compound, which was then substituted, synthesized and evaluated by a variety of bioassays. Derivative 4d was identified as a potent COX-2 enzyme inhibitor and exerted an anticancer effect through COX-2 inhibition. Further investigation confirmed that 4d could induce A549 cell apoptosis and arrest the cell cycle at the G2/M phase. Moreover, treatment with 4d reduced A549 cell adhesive ability and COX-2 expression. The morphological variation of treated cells was also visualized by confocal microscopy. Overall, the biological profile of 4d suggests that this compound may be developed as a potential anticancer agent.

Assessment of the potential ototoxicity of high-dose celecoxib, a selective cyclooxygenase-2 inhibitor, in rats

OBJECTIVE

To evaluate the potential ototoxicity of high-dose celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor.

STUDY DESIGN

Prospective animal study.

SETTING

Laboratory.

METHODS

Twenty adult male Sprague Dawley rats were divided into 2 groups for hearing and tinnitus tests, respectively. The auditory brain-stem response (ABR) and the gap prepulse inhibition of acoustic startle (GPIAS) were used as indicators of hearing loss and tinnitus, respectively, and were measured before and at 2, 4, 6, 8, 12, 24, and 48 hours after administration of celecoxib (2 g/kg) via gavage.

RESULTS

ABR threshold and wave III latencies did not increase significantly at any frequency following celecoxib administration, at any time point (P > .05). GPIAS remained below 30% after celecoxib, from a baseline of 20.03% ± 3.62%; no change was significant.

CONCLUSION

High-dose celecoxib (2 g/kg), a selective COX-2 inhibitor, did not cause hearing loss or tinnitus in Sprague Dawley rats within 48 hours of administration. Further studies are needed to explore the roles played by COX-related mechanisms when nonselective COX inhibitors induce ototoxicity.