Selective inhibition of cyclooxygenase 2 spares renal function and prostaglandin synthesis in cirrhotic rats with ascites

Metamizole-Associated Risks in Decompensated Hepatic Cirrhosis

BACKGROUND

Because of the increased risk of acute renal failure (ARF), the use of cyclooxygenase (COX) inhibitors is not recommended in patients with decompensated hepatic cirrhosis. Metamizole is not a classic COX inhibitor, but there are insufficient data to support its safe use. In this study, we investigate the effect of metamizole on the risk of ARF in these patients.

METHODS

Metamizole use, ARF incidence, and patient mortality were examined in a large, retrospective, exploratory cohort and validated with data from a prospective registry.

RESULTS

523 patients were evaluated in the exploratory cohort. Metamizole use at baseline was documented in 110 cases (21%) and was independently associated with the development of ARF, severe (grade 3) ARF, and lower survival without liver transplantation at follow-up on day 28 (HR: 2.2, p < 0.001; HR: 2.8, p < 0.001; and HR: 2.6, p < 0.001, respectively). Interestingly, the risk of ARF depended on the dose of metamizole administered (HR: 1.038, p < 0.001). Compared to patients who were treated with opioids, the rate of ARF was higher in the metamizole group (49% vs. 79%, p = 0.014). An increased risk of ARF with metamizole use was also demonstrated in the independent validation cohort (p < 0.001).

CONCLUSION

Metamizole therapy, especially at high doses, should only be used with a high level of caution in patients with decompensated cirrhosis.

The therapeutic use of analgesics in patients with liver cirrhosis: a literature review and evidence-based recommendations

CONTEXT

Pain management in cirrhotic patients is a major clinical challenge for medical professionals. Unfortunately there are no concrete guidelines available regarding the administration of analgesics in patients with liver cirrhosis. In this review we aimed to summarize the available literature and suggest appropriate evidence-based recommendations regarding to administration of these drugs.

EVIDENCE ACQUISITION

An indexed MEDLINE search was conducted in July 2014, using keywords "analgesics", "hepatic impairment", "cirrhosis", "acetaminophen or paracetamol", "NSAIDs or nonsteroidal anti-inflammatory drugs", "opioid" for the period of 2004 to 2014. All randomized clinical trials, case series, case report and meta-analysis studies with the above mentioned contents were included in review process. In addition, unpublished information from the Food and Drug Administration are included as well.

RESULTS

Paracetamol is safe in patients with chronic liver disease but a reduced dose of 2-3 g/d is recommended for long-term use. Non-steroidal anti-inflammatory drugs (NSAIDs) are best avoided because of risk of renal impairment, hepatorenal syndrome, and gastrointestinal hemorrhage. Most opioids can have deleterious effects in patients with cirrhosis. They have an increased risk of toxicity and hepatic encephalopathy. They should be administrated with lower and less frequent dosing in these patients and be avoided in patients with a history of encephalopathy or addiction to any substance.

CONCLUSIONS

No evidence-based guidelines exist on the use of analgesics in patients with liver disease and cirrhosis. As a result pain management in these patients generates considerable misconception among health care professionals, leading under-treatment of pain in this population. Providing concrete guidelines toward the administration of these agents will lead to more efficient and safer pain management in this setting.

15-PGDH inhibits hepatocellular carcinoma growth through 15-keto-PGE2/PPARγ-mediated activation of p21WAF1/Cip1

15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a key enzyme in prostaglandin metabolism. This study provides important evidence for inhibition of hepatocellular carcinoma (HCC) growth by 15-PGDH through the 15-keto-PGE₂/PPARγ/p21^WAF1/Cip1 signaling pathway. Forced overexpression of 15-PGDH inhibited HCC cell growth in vitro, whereas knockdown of 15-PGDH enhanced tumor growth parameters. In a tumor xenograft model in SCID mice, inoculation of human HCC cells (Huh7) with overexpression of 15-PGDH led to significant inhibition of tumor growth, while knockdown of 15-PGDH enhanced tumor growth. In a separate tumor xenograft model in which mouse HCC cells (Hepa1-6) were inoculated into syngeneic C57BL/6 mice, intratumoral injection of adenovirus vector expressing 15-PGDH (pAd-15-PGDH) significantly inhibited xenograft tumor growth. The anti-tumor effect of 15-PGDH is mediated through its enzymatic product, 15-keto-PGE₂, which serves as an endogenous PPARγ ligand. Activation of PPARγ by 15-PGDH-derived 15-keto-PGE₂ enhanced the association of PPARγ with the p21^WAF1/Cip1 promoter and increased p21 expression and association with CDK2, CDK4 and PCNA. Depletion of p21 by shRNA reversed 15-PGDH-induced inhibition of HCC cell growth; overexpression of p21 prevented 15-PGDH knockdown-induced tumor cell growth. These results demonstrate a key 15-PGDH/15-keto-PGE₂-mediated activation of PPARγ and p21^WAF1/Cip1 signaling cascade that regulates hepatocarcinogenesis and tumor progression.

Nonsteroidal Anti-Inflammatory Drugs and the Kidney

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the isoenzymes COX-1 and COX-2 of cyclooxygenase (COX). Renal side effects (e.g., kidney function, fluid and urinary electrolyte excretion) vary with the extent of COX-2-COX-1 selectivity and the administered dose of these compounds. While young healthy subjects will rarely experience adverse renal effects with the use of NSAIDs, elderly patients and those with co-morbibity (e.g., congestive heart failure, liver cirrhosis or chronic kidney disease) and drug combinations (e.g., renin-angiotensin blockers, diuretics plus NSAIDs) may develop acute renal failure. This review summarizes our present knowledge how traditional NSAIDs and selective COX-2 inhibitors may affect the kidney under various experimental and clinical conditions, and how these drugs may influence renal inflammation, water transport, sodium and potassium balance and how renal dysfunction or hypertension may result.

Management and treatment of patients with cirrhosis and portal hypertension: recommendations from the Department of Veterans Affairs Hepatitis C Resource Center Program and the National Hepatitis C Program

Cirrhosis represents the end stage of any chronic liver disease. Hepatitis C and alcohol are currently the main causes of cirrhosis in the United States. Although initially cirrhosis is compensated, it eventually becomes decompensated, as defined by the presence of ascites, variceal hemorrhage, encephalopathy, and/or jaundice. These management recommendations are divided according to the status, compensated or decompensated, of the cirrhotic patient, with a separate section for the screening, diagnosis, and management of hepatocellular carcinoma (HCC), as this applies to patients with both compensated and decompensated cirrhosis. In the compensated patient, the main objective is to prevent variceal hemorrhage and any practice that could lead to decompensation. In the decompensated patient, acute variceal hemorrhage and spontaneous bacterial peritonitis are severe complications that require hospitalization. Hepatorenal syndrome is also a severe complication of cirrhosis but one that usually occurs in patients who are already in the hospital and, as it represents an extreme of the hemodynamic alterations that lead to ascites formation, it is placed under treatment of ascites. Recent advances in the pathophysiology of the complications of cirrhosis have allowed for a more rational management of cirrhosis and also for the stratification of patients into different risk groups that require different management. These recommendations are based on evidence in the literature, mainly from randomized clinical trials and meta-analyses of these trials. When few or no data exist from well-designed prospective trials, emphasis is given to results from large series and consensus conferences with involvement of recognized experts. A rational management of cirrhosis will result in improvements in quality of life, treatment adherence, and, ultimately, in outcomes.

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.

Chronic indomethacin treatment enhances the portal-systemic collateral vascular response to vasopressin in bile-duct ligated rats

BACKGROUND

Liver cirrhosis is often accompanied by portal-systemic collateral formation with hemorrhage and encephalopathy. Prostacyclin participates in hyperdynamic circulation and vascular hyporeactiveness to vasoconstrictors in cirrhosis. It has been shown that arginine vasopressin (AVP) induces direct collateral vasoconstriction in portal hypertensive rats, which is potentiated by indomethacin preincubation. However, the influence of chronic indomethacin administration in cirrhosis remains unexplored.

METHODS

This study was performed on male Sprague-Dawley rats with liver cirrhosis induced by common bile duct ligation. They received subcutaneous indomethacin (5 mg/kg/day) or distilled water (control) injection from the 36th to 42nd day after operation. On the 43rd day, systemic and portal hemodynamics were evaluated and the following experiments were performed with an in situ collateral perfusion model: in the first series, concentration-response curves to AVP (10(-10) to 10(-7) M) were obtained; in the second series, flow-pressure curves were plotted (Krebs solution, 6-18 mL/min), where the slope represents an index of collateral vascular resistance (the higher the resistance, the smaller the amount of shunting vessels, that is, the lower the degree of shunting).

RESULTS

The mean arterial pressure and portal pressure were similar between indomethacin and control groups (p > 0.05). Indomethacin elevated the collateral perfusion pressure to AVP (3 x 10(-9), 10(-8) M, p < 0.05) but did not influence the slope of the flow-pressure curve (p > 0.05).

CONCLUSION

In bile duct-ligated cirrhotic rats, indomethacin improves the portal-systemic collateral vascular responsiveness to AVP without alleviating the severity of shunting.

Dose adjustment in patients with liver disease

Unfortunately, there is no endogenous marker for hepatic clearance that can be used as a guide for drug dosing. In order to predict the kinetic behaviour of drugs in cirrhotic patients, agents can be grouped according to their extent of hepatic extraction. For drugs with a high hepatic extraction (low bioavailability in healthy subjects), bioavailability increases and hepatic clearance decreases in cirrhotic patients. If such drugs are administered orally to cirrhotic patients, their initial dose has to be reduced according to hepatic extraction. Furthermore, their maintenance dose has to be adapted irrespective of the route of administration, if possible, according to kinetic studies in cirrhotic patients. For drugs with a low hepatic extraction, bioavailability is not affected by liver disease, but hepatic clearance may be affected. For such drugs, only the maintenance dose has to be reduced, according to the estimated decrease in hepatic drug metabolism. For drugs with an intermediate hepatic extraction, initial oral doses should be chosen in the low range of normal in cirrhotic patients and maintenance doses should be reduced as for high extraction drugs. In cholestatic patients, the clearance of drugs with predominant biliary elimination may be impaired. Guidelines for dose reduction in cholestasis exist for many antineoplastic drugs, but are mostly lacking for other drugs with biliary elimination. Dose adaptation of such drugs in cholestatic patients is, therefore, difficult and has to be performed according to pharmacological effect and/or toxicity. Importantly, the dose of drugs with predominant renal elimination may also have to be adapted in patients with liver disease. Cirrhotic patients often have impaired renal function, despite a normal serum creatinine level. In cirrhotic patients, creatinine clearance should, therefore, be measured or estimated to gain a guideline for the dosing of drugs with predominant renal elimination. Since the creatinine clearance tends to overestimate glomerular filtration in cirrhotic patients, the dose of a given drug may still be too high after adaptation to creatinine clearance. Therefore, the clinical monitoring of pharmacological effects and toxicity of such drugs is important. Besides the mentioned kinetic changes, the dynamics of some drugs is also altered in cirrhotic patients. Examples include opiates, benzodiazepines, NSAIDs and diuretics. Such drugs may exhibit unusual adverse effects that clinicians should be aware of for their safe use. However, it is important to realise that the recommendations for dose adaptation remain general and cannot replace accurate clinical monitoring of patients with liver disease treated with critical drugs.

The selective cyclooxygenase-2 inhibitor SC-236 reduces liver fibrosis by mechanisms involving non-parenchymal cell apoptosis and PPARgamma activation

The importance of inflammation in initiating the sequence of events that lead to liver fibrosis is increasingly recognized. In this study, we tested the effects of SC-236, a selective cyclooxygenase (COX)-2 inhibitor, in rats with carbon tetrachloride (CCl4)-induced liver fibrosis. Livers from CCl4-treated rats showed increased COX-2 expression and 15-deoxy-prostaglandin (PG)J2 (15d-PGJ2) formation, as well as decreased peroxisome proliferator-activated receptor (PPAR)gamma expression. In these animals, SC-236 reduced liver fibrosis as revealed by histological analysis and by a reduction in hepatic hydroxyproline levels, metalloproteinase-2 activity, and alpha-smooth muscle actin expression. Interestingly, SC-236 normalized 15d-PGJ2 levels and restored PPARgamma expression in the liver of CCl4-treated rats. In isolated hepatic stellate cells (HSCs)--the major player in liver fibrogenesis--and Kupffer cells--the cell type primarily responsible for increased hepatic COX-2-SC-236 exhibited remarkable pro-apoptotic and growth inhibitory properties. Of interest, SC-236 decreased HSC viability to a similar extent than the PPARgamma ligand rosiglitazone. Moreover, SC-236 significantly induced PPARgamma expression in HSCs and acted as a potent PPARgamma agonist in a luciferase-reporter trans-activation assay. These data indicate that, by mechanisms involving non-parenchymal cell apoptosis and PPARgamma activation, the selective COX-2 inhibitor SC-236 might have therapeutic potential for prevention of liver fibrosis.

Effects of celecoxib and naproxen on renal function in nonazotemic patients with cirrhosis and ascites

Nonselective inhibition of cyclooxygenase (COX) by nonsteroidal anti-inflammatory drugs frequently induces renal failure in decompensated cirrhosis. Studies in experimental cirrhosis suggest that selective inhibitors of the inducible isoform COX-2 do not adversely affect renal function. However, very limited information is available on the effects of these compounds on renal function in human cirrhosis. This investigation consists of a double-blind, randomized, placebo-controlled trial aimed at comparing the effects of the selective COX-2 inhibitor celecoxib (200 mg every 12 hours for a total of 5 doses) on platelet and renal function and the renal response to furosemide (40 mg intravenously) with those of naproxen (500 mg every 12 hours for a total of 5 doses) and placebo in 28 patients with cirrhosis and ascites. A significant reduction (P < .05) in glomerular filtration rate (113 +/- 27 to 84 +/- 22 mL/min), renal plasma flow (592 +/- 158 to 429 +/- 106 mL/min) and urinary prostaglandin E(2) excretion (3430 +/- 430 to 2068 +/- 549 pg/min) and suppression of the diuretic (urine volume: 561 +/- 128 to 414 +/- 107 mL/h) and natriuretic (urine sodium: 53 +/- 13 to 34 +/- 10 mEq/h) responses to furosemide were observed in the group of patients treated with naproxen but not in the other two groups. Naproxen, but not celecoxib or placebo, significantly inhibited platelet aggregation (72% +/- 8% to 47% +/- 8%, P < .05) and thromboxane B(2) production (41 +/- 12 to 14 +/- 5 pg/mL, P < .05). In conclusion, our results indicate that short-term administration of celecoxib does not impair platelet and renal function and the response to diuretics in decompensated cirrhosis. Further studies are needed to evaluate the long-term safety of this drug in cirrhosis.

The selective cyclooxygenase-2 inhibitor celecoxib modulates the formation of vasoconstrictor eicosanoids and activates PPARgamma. Influence of albumin

BACKGROUND/AIMS

Selective cyclooxygenase (COX)-2 inhibitors do not adversely affect renal function in experimental cirrhosis. In the current study, we investigated the molecular mechanisms underlying the effects of the selective COX-2 inhibitor, celecoxib, and assessed the influence of albumin on its actions.

METHODS

Rat mesangial cells (RMC) were incubated with celecoxib in the absence or presence of albumin, and levels of selected vasoconstrictor eicosanoids, renin release and alpha-smooth muscle actin (alpha-SMA) expression were determined. The effects of celecoxib on PPARgamma were assessed in RMC co-transfected with PPARgamma and luciferase reporter constructs.

RESULTS

Under resting conditions, RMC expressed COX-1, COX-2 and 12/15-lipoxygenase and mainly generated prostaglandin (PG)E2, thromboxane (TX)B2, 12-hydroxyeicosatetraenoic acid (12-HETE) and 8-epi-PGF2alpha. Celecoxib, in addition to reducing PGE2, significantly decreased 8-epi-PGF2alpha formation. In the presence of albumin, celecoxib also reduced TXB2 and 12-HETE. Albumin per se inhibited PGE2 as well as renin release. In trans-activation assays, celecoxib acted as a PPARgamma agonist whereas albumin inhibited PPARgamma as well as 15d-PGJ2-induced PPARgamma activation. Finally, celecoxib and albumin potentiated the inhibitory effect of 15d-PGJ2 on alpha-SMA expression.

CONCLUSIONS

These data provide novel molecular mechanisms of celecoxib and their modulation by albumin, that may be relevant to prevent renal dysfunction in conditions of unbalanced effective blood volume.

Distribution of constitutive (COX-1) and inducible (COX-2) cyclooxygenase in postviral human liver cirrhosis: a possible role for COX-2 in the pathogenesis of liver cirrhosis

AIMS

Prostaglandins produced by the action of cyclooxygenases (COX) are important mediators of systemic vasodilatation and inflammation in liver cirrhosis. The aim of this study was to investigate the distribution of COX-1 and COX-2 in postviral cirrhosis.

METHODS

The immunohistochemical expression of the constitutive (COX-1) and the inducible (COX-2) isoenzymes was investigated in 15 patients with cirrhosis after hepatitis B and C infection; three normal control livers were also analysed.

RESULTS

COX-2 was absent from normal liver but was highly expressed in cirrhosis, mainly in the inflammatory, sinusoidal, vascular endothelial, and biliary epithelial cells. Low amounts of COX-1 were expressed in both normal and cirrhotic livers, exclusively in sinusoidal and vascular endothelial cells, with no differences seen between normal and cirrhotic livers.

CONCLUSIONS

COX-2 is overexpressed in liver cirrhosis, and possibly contributes to prostaglandin overproduction, which may be a major component of the inflammation and hyperdynamic circulation associated with cirrhosis. Because COX-2 is thought to contribute to tumour development, high COX-2 production could be a contributor to hepatocellular carcinoma development in cirrhosis. The finding of COX-2 and not COX-1 upregulation in cirrhosis could provide a possible new role for selective COX-2 inhibitors in reducing inflammation and minimising the occurrence of hepatocellular carcinoma in patients with cirrhosis.

Cyclooxygenase 2 (COX2)-prostanoid pathway and liver diseases

Cycloocygenases 2 (COX2)-prostanoid pathway plays important and complex roles in the pathogenesis of various liver diseases. Most studies indicated that COX2-prostanoid pathway might suppress hepatic fibrogenesis by decreasing proliferation, migration, and contractility of hepatic stellate cells (HSCs). In animal model, COX2-prostanoid pathway increases portal hypertension, which can be reduced by treatment with COX2 inhibitor. In cirrhosis, COX2-prostanoid pathway may reduce formation of ascites by enhancing free water excretion, and protect gastric mucosa from ulcerative insults. Aberrant expression of COX2 has been well associated with hepatocarcinogenesis. COX2 inhibitors can effectively suppress proliferation of hepatocellular carcinoma (HCC) cells. This provided rationale for further testing COX2 inhibitors as clinical agents for HCC chemoprovention. Further studies will be needed to examine how COX2 inhibitors affect pathogenesis of various liver diseases.

JTE-522, a cyclooxygenase-2 inhibitor, is an effective chemopreventive agent against rat experimental liver fibrosis1

BACKGROUND & AIMS

The aim of this study was to assess the effects of cyclooxygenase (COX)-2 inhibition on rat experimental liver fibrogenesis.

METHODS

We investigated the inhibitory effects of a selective COX-2 inhibitor, JTE-522, on liver fibrosis induced by a choline-deficient, l-amino acid-defined diet (CDAA). Inhibitory effect was also tested in a second model of thioacetamide (TAA)-induced liver fibrosis.

RESULTS

CDAA induced liver fibrosis and preneoplastic foci at 12 weeks and cirrhosis at 36 weeks. Hepatocellular carcinoma was noted in 13 of 15 rats (87%). JTE-522 significantly inhibited fibrosis and development of preneoplastic lesions in a dose-dependent manner and completely inhibited generation of cirrhosis and hepatocellular carcinoma at both low and high doses (10 and 30 mg/kg body wt/day, respectively). JTE-522 administrated only from 12 weeks to 36 weeks also prevented cirrhosis and formation of hepatocellular carcinoma. JTE-522 itself did not cause local or systemic gross or histopathologic changes at 36 weeks. Mechanistic studies indicated that the CDAA model displayed up-regulation of several biomarkers, including COX-2, arachidonate metabolite (prostaglandin E(2)), serum aspartate aminotransferase, and c-myc expression. The model also showed an increased proportion of activated hepatic stellate cells, proliferating cell nuclear antigen index, and CD45-positive inflammatory cells in the liver. JTE-522 effectively diminished these changes. JTE-522 exhibited similar antifibrosis effects in the TAA model.

CONCLUSIONS

Our results suggest that COX-2 is involved in CDAA- and TAA-induced liver fibrosis. Our data also indicate that JTE-522 is a potent chemopreventive agent of rat liver fibrosis with low toxicity.

Adverse renal effects of anti-inflammatory agents: evaluation of selective and nonselective cyclooxygenase inhibitors

Conventional nonsteroidal anti-inflammatory drugs (NSAIDs), i.e. nonselective cyclooxygenase COX inhibitors have well-documented nephrotoxicity. Adverse renal effects occur because of inhibition of the synthesis of cyclooxygenase-derived prostaglandins which act to modulate pathologic processes that would normally impair various renal functions. The introduction of the selective COX-2 inhibitors raised hope that this class of drugs would reduce injury in both the gastrointestinal tract and the kidneys. Animal and human data, however, suggest that COX-2 synthesized prostaglandins are important in the modulation of renal physiology during adverse conditions. Hence, it appears that these drugs are equal in causing nephrotoxicity as the nonselective COX inhibitors.

Cyclooxygenase-derived products modulate the increased intrahepatic resistance of cirrhotic rat livers

In cirrhotic livers, increased resistance to portal flow, in part due to an exaggerated response to vasoconstrictors, is the primary factor in the pathophysiology of portal hypertension. Our aim was to evaluate the response of the intrahepatic circulation of cirrhotic rat livers to the alpha(1)-adrenergic vasoconstrictor methoxamine and the mechanisms involved in its regulation. A portal perfusion pressure dose-response curve to methoxamine was performed in control and cirrhotic rat livers preincubated with vehicle, the nitric oxide synthase blocker N(G)-nitro-L-arginine (L-NNA), indomethacin cyclooxygenase (COX) inhibitor, L-NNA + indomethacin, or the thromboxane (TX) A(2) receptor blocker SQ 29,548. TXA(2) production, COX-1 and COX-2 mRNA expression, and immunostaining for TXA(2) synthase were evaluated. Cirrhotic livers exhibited a hyperresponse to methoxamine associated with overexpression of COX-2 and TXA(2) synthase as well as with increased production of TXA(2). The hyperresponse to methoxamine of cirrhotic livers disappeared by COX inhibition with indomethacin but not after NO inhibition. SQ 29,548 also corrected the hyperresponse of cirrhotic livers to methoxamine. In conclusion, COX-derived prostanoids, mainly TXA(2), play a major role in regulating the response of cirrhotic livers to methoxamine.

Effect of misoprostol on ibuprofen-induced renal dysfunction in patients with decompensated cirrhosis: results of a double-blind placebo-controlled parallel group study

OBJECTIVES

Patients with cirrhosis are prone to develop renal failure upon administration of nonsteroidal anti-inflammatory drugs. The aim of the present study was to determine the safety and efficacy of misoprostol (400 microg) in two repeated doses for the prevention of ibuprofen-induced decrements in renal function in decompensated cirrhotics.

METHODS

Patients were given ibuprofen (800 mg) with either misoprostol (n = 9) or a placebo (n = 10). Sixty minutes later another dose of misoprostol or the placebo was administered. Renal function tests were assessed by clearance techniques.

RESULTS

Administration of ibuprofen with a placebo caused significant decreases in urinary output, inulin clearance, sodium excretion, osmolar clearance, free water clearance, and urinary prostaglandin E2 excretion. Coadministration of ibuprofen and the first misoprostol dose maintained urinary output and sodium excretion, and caused an increase in free water clearance. These changes were maintained only for 1 h. Administration of the second dose of misoprostol temporarily improved inulin and creatinine clearances. Half the patients who received misoprostol suffered from episodes of chills, fever, and diarrhea.

CONCLUSION

Ibuprofen causes renal dysfunction in decompensated cirrhotics, whereas misoprostol may have some protective renal effects, which are, however, short lived and clinically insignificant. Because of side effects, misoprostol should be used with caution in these patients.

Effect of Nimesulide on proliferation and apoptosis of human hepatoma SMMC-7721 cells

AIM: Cyclooxygenase-2 (COX-2) has been suggested to be associated with carcinogenesis. We sought to investigate the effect of the selective COX-2 inhibitor, Nimesulide on proliferation and apoptosis of SMMC-7721 human hepatoma cells.

METHODS: This study was carried out on the culture of hepatic carcinoma SMMC-7721 cell line. Various concentrations of Nimesulide (0, 200 μmol/L, 300 μmol/L, 400 μmol/L) were added and incubated. Cell proliferation was detected with MTT colorimetric assay, cell apoptosis by electron microscopy, flow cytometry and TUNEL.

RESULTS: Nimesulide could significantly inhibit SMMC-7721 cells proliferation dose-dependent and in a dependent manner compared with that of the control group. The duration lowest inhibition rate produced by Nimesulide in SMMC-7721 cells was 19.06%, the highest inhibition rate was 58.49%. After incubation with Nimesulide for 72 h, the most highest apoptosis rate and apoptosis index of SMMC-7721 cells comparing with those of the control were 21.20% ± 1.62% vs 2.24% ± 0.26% and 21.23 ± 1.78 vs 2.01 ± 0.23 (P < 0.05).

CONCLUSION: The selective COX-2 inhibitor, Nimesulide can inhibit the proliferation of SMMC-7721 cells and increase apoptosis rate and apoptosis index of SMMC-7721 cells. The apoptosis rate and the apoptosis index are dose-dependent. Under electron microscope SMMC-7721 cells incubated with 300 μmol and 400 μmol Nimesulide show apoptotic characteristics. With the clarification of the mechanism of selective COX-2 inhibitors, These COX-2 selective inhibitors can become the choice of prevention and treatment of cancers.

Cyclo-oxygenase-2 inhibitors and the kidney: a case for caution

Cyclo-oxygenase (COX) is one of the key enzymes in the biosynthesis of prostaglandins. Two isoforms of this enzyme COX-1 and COX-2 are known to exist. Among other functions, prostaglandins play an important role in the protection of the gastric mucosa and maintenance of renal function in pathophysiological conditions which would otherwise threaten it. Conventional nonsteroidal anti-inflammatory drugs (NSAIDs) block prostaglandin synthesis, resulting in gastric mucosal injury and renal dysfunction in susceptible individuals. The recent introduction of selective COX-2 inhibitors, celecoxib and rofecoxib, appear to induce less gastrointestinal morbidity. Although conclusive data are still lacking, there is evidence to suggest that COX-2 antagonists may be capable of causing some of the same renal syndromes seen in association with the older, less selective NSAIDs.

Pharmacology of cyclooxygenase-2 inhibition in the kidney

Cyclooxygenase (COX) exists as two unique isoforms (that is, COX-1 and COX-2) which are poorly understood with regard to their roles in renal function. The renal effects of conventional non-steroidal anti-inflammatory drugs (NSAIDs) are believed to result from the inhibition of one or both isoforms. Drugs that selectively inhibit COX-2 provide useful pharmacological tools for discerning the effects associated with the inhibition of the individual isoforms, and may help clarify the renal roles of COX-1 and COX-2. This review summarizes the current data on the renal expression of COX isoforms and their potential roles in renal function, and reviews the studies that have attempted to correlate renal functional changes with selective isoform inhibition. Since there are significant differences in the expression of COX isoforms in the kidneys of laboratory animals and humans, this review also examines the correlation of the results of COX inhibition in experimental studies in laboratory animals with clinical data. Because of potential interspecies differences in the roles of COX isoforms in renal function, animal models may have limited predictive value for patients, particularly those with renal risk factors. Accordingly, any uncertainty concerning the safety or therapeutic benefit of COX-2-specific drugs in these patient populations will need to be resolved with clinical investigations.

Cyclooxygenase-1 derived prostaglandins are involved in the maintenance of renal function in rats with cirrhosis and ascites

1. The maintenance of renal function in decompensated cirrhosis is highly dependent on prostaglandins (PGs). Since PG synthesis is mediated by cyclooxygenase-1 and -2 (COX-1 and COX-2), the present study was designed to examine which COX isoform is involved in this phenomenon. 2. Renal COX-1 and COX-2 protein expression and distribution were analysed by Western blot and immunohistochemistry in nine rats with carbon tetrachloride-induced cirrhosis and ascites and 10 control animals. The effects of placebo and selective COX-1 (SC-560) and COX-2 (celecoxib) inhibitors on urine flow (V), urinary excretion of sodium (U(Na)V) and PGE(2) (U(PGE2)V), glomerular filtration rate (GFR), renal plasma flow (RPF), the diuretic and natriuretic responses to furosemide and renal water metabolism were assessed in 88 rats with cirrhosis and ascites. 3. COX-1 protein levels were found to be unchanged in kidneys from cirrhotic rats. In contrast, these animals showed enhanced renal COX-2 protein expression which was focally increased in the corticomedullary region. Although U(PGE2)V was equally reduced by SC-560 and celecoxib, only SC-560 produced a significant decrease in U(Na)V, GFR and RPF and a pronounced impairment in the diuretic and natriuretic responses to furosemide in rats with cirrhosis and ascites. Neither SC-560 nor celecoxib affected renal water metabolism in cirrhotic rats. 4. These results indicate that despite abundant renal COX-2 protein expression, the maintenance of renal function in cirrhotic rats is mainly dependent on COX-1-derived prostaglandins.

Prostanoid production via COX-2 as a causative mechanism of rodent postoperative ileus

BACKGROUND & AIMS

This study demonstrates a significant role for cyclooxygenase (COX)-2 and prostanoid production as mechanisms for surgically induced postoperative ileus.

METHODS

Rats, COX-2+/+, and COX-2-/- mice underwent simple intestinal manipulation. Reverse-transcription polymerase chain reaction and immunohistochemistry were used to detect and localize COX-2 expression. Prostaglandin levels were measured from serum, peritoneal lavage fluid, and muscularis culture media. Jejunal circular muscle contractions were measured in an organ bath, and gastrointestinal transit was measured in vivo.

RESULTS

The data show that intestinal manipulation induces COX-2 messenger RNA and protein within resident muscularis macrophages, a discrete subpopulation of myenteric neurons and recruited monocytes. The manipulation-induced increase in COX-2 expression resulted in significantly elevated prostaglandin levels within the circulation and peritoneal cavity. The source of these prostanoids could be directly attributed to their release from the inflamed muscularis externa. As a consequence of the molecular up-regulation of COX-2, we observed a decrease in in vitro jejunal circular muscle contractility and gastrointestinal transit, both of which could be alleviated pharmacologically with selective COX-2 inhibition. These studies were corroborated with the use of COX-2-/- mice.

CONCLUSIONS

Prostaglandins, through the induction of COX-2, are major participants in rodent postoperative ileus induced by intestinal manipulation.

Lipopolysaccharide-induced increase of prostaglandin E(2) is mediated by inducible nitric oxide synthase activation of the constitutive cyclooxygenase and induction of membrane-associated prostaglandin E synthase

NO produced by the inducible NO synthase (NOS2) and prostanoids generated by the cyclooxygenase (COX) isoforms and terminal prostanoid synthases are major components of the host innate immune and inflammatory response. Evidence exists that pharmacological manipulation of one pathway could result in cross-modulation of the other, but the sense, amplitude, and relevance of these interactions are controversial, especially in vivo. Administration of 6 mg/kg LPS to rats i.p. resulted 6 h later in induction of NOS2 and the membrane-associated PGE synthase (mPGES) expression, and decreased constitutive COX (COX-1) expression. Low level inducible COX (COX-2) mRNA with absent COX-2 protein expression was observed. The NOS2 inhibitor aminoguanidine (50 and 100 mg/kg i.p.) dose dependently decreased both NO and prostanoid production. The LPS-induced increase in PGE(2) concentration was mediated by NOS2-derived NO-dependent activation of COX-1 pathway and by induction of mPGES. Despite absent COX-2 protein, SC-236, a putative COX-2-specific inhibitor, decreased mPGES RNA expression and PGE(2) concentration. Ketoprofen, a nonspecific COX inhibitor, and SC-236 had no effect on the NOS2 pathway. Our results suggest that in a model of systemic inflammation characterized by the absence of COX-2 protein expression, NOS2-derived NO activates COX-1 pathway, and inhibitors of COX isoforms have no effect on NOS2 or NOS3 (endothelial NOS) pathways. These results could explain, at least in part, the deleterious effects of NOS2 inhibitors in some experimental and clinical settings, and could imply that there is a major conceptual limitation to the use of NOS2 inhibitors during systemic inflammation.

Cellular and molecular mediators in common pathway mechanisms of chronic renal disease progression

Injury mechanisms activated by the hemodynamic adaptations to nephron loss are considered to represent a final common pathway that underlies the progressive nature of chronic renal disease. In this article, we review experimental evidence that the induction of cell adhesion molecule, cytokine and profibrotic growth factor gene expression and the resultant renal infiltration by inflammatory cells, especially macrophages, are important components of these common pathway mechanisms. Interventions aimed at inhibiting these mechanisms may offer new treatments for slowing or arresting the progression of chronic renal disease.

Portal hypertension

Cirrhosis represents the end-stage of any chronic liver disease. Two major syndromes result from cirrhosis-portal hypertension and hepatic insufficiency. Additionally, vasodilatation and the hyperdynamic circulation are hemodynamic abnormalities typical of cirrhosis and portal hypertension. Complications of cirrhosis occur as a consequence of a combination of these factors. Gastroesophageal varices result almost solely from portal hypertension, although the hyperdynamic circulation contributes to variceal growth and hemorrhage. Ascites results from sinusoidal hypertension and sodium retention, which is, in turn, secondary to vasodilatation and activation of neurohumoral systems. Hepatorenal syndrome also results from severe peripheral vasodilatation that leads to renal vasoconstriction. Another complication of cirrhosis, portosystemic encephalopathy, is a consequence of both portal hypertension (shunting of blood through portosystemic collaterals) and hepatic insufficiency. In this article, recent advances in pathophysiology and management of the complications of cirrhosis and portal hypertension are reviewed.