Cyclooxygenase 2 and the kidney

The association of urinary prostaglandins with uric acid in hyperuricemia patients

Purpose

To explore the association between uric acid and urinary prostaglandins in male patients with hyperuricemia.

Methods

A total of 38 male patients with hyperuricemia in outpatients of Huadong Hospital from July 2018 to January 2020 were recruited. Serum uric acid (SUA), 24 h urinary uric acid excretion and other indicators were detected respectively. 10 ml urine was taken to determine prostaglandin prostaglandin D (PGD), prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), 6-keto-PGF1α, thromboxane A2 (TXA2) and thromboxane B2 (TXB2). Fraction of uric acid excretion (FEua) and uric acid clearance rate (Cua) were calculated. According to the mean value of FEua and Cua, patients were divided into two groups, respectively. The independent-samples t test and the Mann–Whitney U test were applied for normally and non-normally distributed data, respectively.

Results

After adjusting confounding factors (age, BMI, eGFR, TG, TC, HDL and LDL), SUA was negatively correlated with urinary PGE1(r = -0.615, P = 0.009) and PGE2(r = -0.824, P < 0.001). Compared with SUA1 group (SUA < 482.6 mg/dl), SUA2 (SUA \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 482.6 mg/dl) had lower urinary PGE1(P = 0.022) and PGE2(P = 0.019) levels. Cua was positively correlated with PGE2 (r = 0.436, P = 0.01). The correlation persisted after adjustment for age, BMI, eGFR, TG, TC, HDL and LDL by multiple linear regression analysis. In the Cua1 group (Cua < 4.869 mL /min/1.73 m²), PGE2 were lower than that in Cua2 (Cua \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 4.869 mL /min/1.73 m²) group (P = 0.011).

Conclusions

In male patients with hyperuricemia, SUA was negatively correlated with urinary PGE2, Cua was positively correlated with urinary PGE2. Urinary PGE2 were significantly different between different SUA and Cua groups.

Modulation of Enzyme-Catalyzed Synthesis of Prostaglandins by Components Contained in Kidney Microsomal Preparations

In the kidney, prostaglandins formed by cyclooxygenase 1 and 2 (COX-1 and COX-2) play an important role in regulating renal blood flow. In the present study, we report our observations regarding a unique modulatory effect of renal microsomal preparation on COX-1/2-mediated formation of major prostaglandin (PG) products in vitro. We found that microsomes prepared from pig and rat kidneys had a dual stimulatory–inhibitory effect on the formation of certain PG products catalyzed by COX-1 and COX-2. At lower concentrations, kidney microsomes stimulated the formation of certain PG products, whereas at higher concentrations, their presence inhibited the formation. Presence of kidney microsomes consistently increased the K_m values of the COX-1/2-mediated reactions, while the V_max might be increased or decreased depending on stimulation or inhibition observed. Experimental evidence was presented to show that a protein component present in the pig kidney microsomes was primarily responsible for the activation of the enzyme-catalyzed arachidonic acid metabolism leading to the formation of certain PG products.

Cannabinoid Receptor 1 Inhibition in Chronic Kidney Disease: A New Therapeutic Toolbox

Chronic kidney disease (CKD) concerns millions of individuals worldwide, with few therapeutic strategies available to date. Recent evidence suggests that the endocannabinoid system (ECS) could be a new therapeutic target to prevent CKD. ECS combines receptors, cannabinoid receptor type 1 (CB1R) and type 2 (CB2R), and ligands. The most prominent receptor within the kidney is CB1R, its endogenous local ligands being anandamide and 2-arachidonoylglycerol. Therefore, the present review focuses on the therapeutic potential of CB1R and not CB2R. In the normal kidney, CB1R is expressed in many cell types, especially in the vasculature where it contributes to the regulation of renal hemodynamics. CB1R could also participate to water and sodium balance and to blood pressure regulation but its precise role remains to decipher. CB1R promotes renal fibrosis in both metabolic and non-metabolic nephropathies. In metabolic syndrome, obesity and diabetes, CB1R inhibition not only improves metabolic parameters, but also exerts a direct role in preventing renal fibrosis. In non-metabolic nephropathies, its inhibition reduces the development of renal fibrosis. There is a growing interest of the industry to develop new CB1R antagonists without central nervous side-effects. Experimental data on renal fibrosis are encouraging and some molecules are currently under early-stage clinical phases (phases I and IIa studies). In the present review, we will first describe the role of the endocannabinoid receptors, especially CB1R, in renal physiology. We will next explore the role of endocannabinoid receptors in both metabolic and non-metabolic CKD and renal fibrosis. Finally, we will discuss the therapeutic potential of CB1R inhibition using the new pharmacological approaches. Overall, the new pharmacological blockers of CB1R could provide an additional therapeutic toolbox in the management of CKD and renal fibrosis from both metabolic and non-metabolic origin.

Coenzyme Q10 coadministration with diclofenac augmented impaired renal function in broiler chickens (Gallus gallus domesticus)

Aim:

This study aimed to investigate the effects of coenzyme Q10 (COQ10) and diclofenac coadministration on the hepatorenal function in broiler chickens (Gallus gallus domesticus).

Materials and Methods:

Birds (21 days old) were divided into six groups of eight birds each. The 1^st group was the control, the 2^nd group was treated orally with COQ10(30mg/kg b.wt), the 3^rdand 4^thgroups were treated intraperitoneally with diclofenac sodium at doses 1 and 2mg/kg b.wt, respectively, and the 5^thand 6^thgroups were treated with COQ10 (dose 30mg/kg b.wt, P.O.) and diclofenac sodium (dose 1mg/kg b.wt, I.P.) and COQ10 (dose 30mg/kg b.wt, P.O.) and diclofenac sodium (dose 2mg/kg b.wt, I.P.), respectively. The experiment lasted 5days. Twenty-four hours after the last administration, all the birds were sacrificed through cervical dislocation; blood samples were collected for serum biochemical analysis.

Results:

COQ10 induced a significant increase in aspartate aminotransferase (AST), urea, creatinine, sodium, potassium, and chloride, while diclofenac induced a significant increase in alanine aminotransferase (ALT), AST, total cholesterol, triglyceride, high-density lipoprotein, urea, creatinine, sodium, potassium, and chloride. However, when COQ10 and diclofenac were coadministered, we observed that COQ10 decreased the liver injury caused by diclofenac. However, COQ10 could not relieve the kidney injury caused by diclofenac, but worsened the impaired renal function.

Conclusion:

COQ10 protects the liver against diclofenac-induced liver injury while augmenting diclofenac-induced kidney injury.

COX-2 mediated crosstalk between Wnt/β-catenin and the NF-κB signaling pathway during inflammatory responses induced by Haemophilus parasuis in PK-15 and NPTr cells

Haemophilus parasuis infection causes typical acute systemic inflammation in pigs, is characterized by fibrinous polyserositis inflammation, and results in great economic losses to the swine industry worldwide. However, the molecular details of how the host modulates the acute inflammatory response induced by H. parasuis are largely unknown. In previous studies, we found that H. parasuis high-virulence strain SH0165 infection induced the activation of both Wnt/β-catenin and NF-κB signaling in PK-15 and NPTr cells. In this study, we found that the activation of NF-κB, a central hub in inflammatory signaling, was impeded by the Wnt/β-catenin pathway during H. parasuis infection. In contrast, blocking NF-κB activity had no effect on the Wnt/β-catenin pathway during H. parasuis infection. Furthermore, we found that the inhibitory effect of β-catenin on NF-κB activity was mediated by its target gene, pig cyclooxygenase-2 (COX-2). Therefore, we demonstrated that H. parasuis infection activates the canonical Wnt/β-catenin signaling pathway, which leads to decreased NF-κB activity, reducing the acute inflammatory response in pigs. Additionally, the data provide a possible perspective for understanding the anti-inflammatory role of Wnt/β-catenin in pigs during bacterial infection.

Cyclooxygenase-2, Asymmetric Dimethylarginine, and the Cardiovascular Hazard From Nonsteroidal Anti-Inflammatory Drugs

BACKGROUND

Large-scale, placebo-controlled trials established that nonsteroidal anti-inflammatory drugs confer a cardiovascular hazard: this has been attributed to depression of cardioprotective products of cyclooxygenase (COX)-2, especially prostacyclin. An alternative mechanism by which nonsteroidal anti-inflammatory drugs might constrain cardioprotection is by enhancing the formation of methylarginines in the kidney that would limit the action of nitric oxide throughout the vasculature.

METHODS

Targeted and untargeted metabolomics were used to investigate the effect of COX-2 deletion or inhibition in mice and in osteoarthritis patients exposed to nonsteroidal anti-inflammatory drugs on the l-arginine/nitric oxide pathway.

RESULTS

Analysis of the plasma and renal metabolome was performed in postnatal tamoxifen-inducible Cox-2 knockout mice, which exhibit normal renal function and blood pressure. This revealed no changes in arginine and methylarginines compared with their wild-type controls. Moreover, the expression of genes in the l-arginine/nitric oxide pathway was not altered in the renal medulla or cortex of tamoxifen inducible Cox-2 knockout mice. Therapeutic concentrations of the selective COX-2 inhibitors, rofecoxib, celecoxib, and parecoxib, none of which altered basal blood pressure or renal function as reflected by plasma creatinine, failed to elevate plasma arginine and methylarginines in mice. Finally, plasma arginine or methylarginines were not altered in osteoarthritis patients with confirmed exposure to nonsteroidal anti-inflammatory drugs that inhibit COX-1 and COX-2. By contrast, plasma asymmetrical dimethylarginine was increased in mice infused with angiotensin II sufficient to elevate blood pressure and impair renal function. Four weeks later, blood pressure, plasma creatinine, and asymmetrical dimethylarginine were restored to normal levels. The increase in asymmetrical dimethylarginine in response to infusion with angiotensin II in celecoxib-treated mice was also related to transient impairment of renal function.

CONCLUSIONS

Plasma methylarginines are not altered by COX-2 deletion or inhibition but rather are elevated coincident with renal compromise.

PGE1-Containing Protocols Generate Mature (Leukemia-Derived) Dendritic Cells Directly from Leukemic Whole Blood

Dendritic cells (DCs) and leukemia-derived DC (DC_leu) are potent stimulators of various immunoreactive cells and they play a pivotal role in the (re-) activation of the immune system. As a potential treatment tool for patients with acute myeloid leukemia, we developed and analyzed two new PGE₁-containing protocols (Pici-_PGE1, Kit M) to generate DC/DC_leu ex vivo from leukemic peripheral blood mononuclear cells (PBMCs) or directly from leukemic whole blood (WB) to simulate physiological conditions. Pici-_PGE1 generated significantly higher amounts of DCs from leukemic and healthy PBMCs when compared to control and comparable amounts as the already established protocol Pici-_PGE2. The proportions of sufficient DC-generation were even higher after DC/DC_leu-generation with Pici-_PGE1. With Kits, it was possible to generate DCs and DC_leu directly from leukemic and healthy WB without induction of blast proliferation. The average amounts of generated DCs and DC_leu-subgroups were comparable with all Kits. The PGE₁ containing Kit M generated significantly higher amounts of mature DCs when compared to the PGE₂-containing Kit K and increased the anti-leukemic-activity. In summary PGE₁-containing protocols were suitable for generating DC/DC_leu from PBMCs as well as from WB, which reliably (re-) activated immunoreactive cells, improved the overall ex vivo anti-leukemic activity, and influenced cytokine-release-profiles.

Prostaglandins in the pathogenesis of kidney diseases

Prostaglandins (PGs) are important lipid mediators produced from arachidonic acid via the sequential catalyzation of cyclooxygenases (COXs) and specific prostaglandin synthases. There are five subtypes of PGs, namely PGE2, PGI2, PGD2, PGF2α, and thromboxane A2 (TXA2). PGs exert distinct roles by combining to a diverse family of membrane-spanning G protein-coupled prostanoid receptors. The distribution of these PGs, their specific synthases and receptors vary a lot in the kidney. This review summarized the recent findings of PGs together with the COXs and their specific synthases and receptors in regulating renal function and highlighted the insights into their roles in the pathogenesis of various kidney diseases.

COX-2 expression mediated by calcium-TonEBP signaling axis under hyperosmotic conditions serves osmoprotective function in nucleus pulposus cells

The nucleus pulposus (NP) of intervertebral discs experiences dynamic changes in tissue osmolarity because of diurnal loading of the spine. TonEBP/NFAT5 is a transcription factor that is critical in osmoregulation as well as survival of NP cells in the hyperosmotic milieu. The goal of this study was to investigate whether cyclooxygenase-2 (COX-2) expression is osmoresponsive and dependent on TonEBP, and whether it serves an osmoprotective role. NP cells up-regulated COX-2 expression in hyperosmotic media. The induction of COX-2 depended on elevation of intracellular calcium levels and p38 MAPK pathway, but independent of calcineurin signaling as well as MEK/ERK and JNK pathways. Under hyperosmotic conditions, both COX-2 mRNA stability and its proximal promoter activity were increased. The proximal COX-2 promoter (-1840/+123 bp) contained predicted binding sites for TonEBP, AP-1, NF-κB, and C/EBP-β. While COX-2 promoter activity was positively regulated by both AP-1 and NF-κB, AP-1 had no effect and NF-κB negatively regulated COX-2 protein levels under hyperosmotic conditions. On the other hand, TonEBP was necessary for both COX-2 promoter activity and protein up-regulation in response to hyperosmotic stimuli. Ex vivo disc organ culture studies using hypomorphic TonEBP^+/- mice confirmed that TonEBP is required for hyperosmotic induction of COX-2. Importantly, the inhibition of COX-2 activity under hyperosmotic conditions resulted in decreased cell viability, suggesting that COX-2 plays a cytoprotective and homeostatic role in NP cells for their adaptation to dynamically loaded hyperosmotic niches.

Natural products as inhibitors of prostaglandin E2 and pro-inflammatory 5-lipoxygenase-derived lipid mediator biosynthesis

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit prostanoid formation and represent prevalent therapeutics for treatment of inflammatory disorders. However, NSAIDs are afflicted with severe side effects, which might be circumvented by more selective suppression of pro-inflammatory eicosanoid biosynthesis. This concept led to dual inhibitors of microsomal prostaglandin E₂ synthase (mPGES)-1 and 5-lipoxygenase that are crucial enzymes in the biosynthesis of pro-inflammatory prostaglandin E₂ and leukotrienes. The potential of their dual inhibition in light of superior efficacy and safety is discussed. Focus is placed on natural products, for which direct inhibition of mPGES-1 and leukotriene biosynthesis has been confirmed.

Celecoxib induces cell death on non-small cell lung cancer cells through endoplasmic reticulum stress

Cyclooxygenase-2 (COX-2) is an enzyme induced by various proinflammatory and mitogenic stimuli. Celecoxib is a selective inhibitor of COX-2 that have been shown to affect cell growth and apoptosis. Lung cancer cells expressing COX-2 is able to be a target of celecoxib, this study focuses on investigating that celecoxib induces apoptosis via endoplasmic reticulum (ER) stress on lung cancer cells. We investigated whether celecoxib induced apoptosis on non-small cell lung cancer cell line, A549 and H460. The 50 µM of celecoxib increased apoptotic cells and 100 µM of celecoxib significantly induced apoptosis. To check involvement of caspase cascade, pretreatment of z-VAD-fmk blocked celecoxib-induced apoptosis. However, caspase-3, -8, and -9 were not activated, but cleavage of non-classical caspase-4 was detected using western blot. As checking ER stress associated molecules, celecoxib did not increase expressions of growth arrest and DNA damage inducible protein 34, activating transcription factor 4, and spliced X-box binding protiens-1, but increase of both glucose-regulated protein 78 (GRP78) and C/EBP homologous transcription factor were detected. Salubrinal, inhibitor of eIF2 and siRNA for IRE1 did not alter celecoxib-induced apoptosis. Instead, celecoxib-induced apoptosis might be deeply associated with ER stress depending on GRP78 because siRNA for GRP78 enhanced apoptosis. Taken together, celecoxib triggered ER stress on lung cancer cells and celecoxib-induced apoptosis might be involved in both non-classical caspase-4 and GRP78.

Protective effects of curcumin against doxorubicin-induced toxicity and resistance: A review

Doxorubicin (DOX)-induced toxicity and resistance are major obstacles in chemotherapeutic approaches. Despite effective in the treatment of numerous malignancies, some clinicians have voiced concern that DOX has the potential to cause debilitating consequences in organ tissues, especially the heart. The mechanisms of toxicity and resistance are respectively related to induction of reactive oxygen species (ROS) and up-regulation of ATP-binding cassette (ABC) transporter. Curcumin (CUR) with several biological and pharmacological properties is expected to restore DOX-mediated impairments to tissues. This review is intended to address the current knowledge on DOX adverse effects and CUR protective actions in the heart, kidneys, liver, brain, and reproductive organs. Coadministration of CUR and DOX is capable of ameliorating DOX toxicity pertained to antioxidant, apoptosis, autophagy, and mitochondrial permeability.

Cyclooxygenase-2 expression is induced by celecoxib treatment in lung cancer cells and is transferred to neighbor cells via exosomes

Lung cancer is one of most common types of cancer worldwide. Lung cancer results in a death higher rate each year compared to colon, breast and prostate cancer combined. Celecoxib is a selective inhibitor of cyclooxygenase-2 (COX‑2), an enzyme of which the expression is induced by various stimuli, such as inflammation. In addition, celecoxib triggers COX-2 loading on exosomes. Exosomes are small vesicles composed of a lipid bilayer membrane and are found in most biological fluids, such as blood breast milk and urine. In this study, we focused on exosomes containing COX-2 proteins from lung cancer cells to determine their involvement in the interaction with neighbor cells following treatment with celecoxib. We found that celecoxib induced COX-2 expression in both the cytosol and exosomes in lung cancer cells. Exosomes from celecoxib-treated lung cancer cell culture supernatant were isolated and incubated with several types of cells. The THP-1, monocytic leukemia cell line effectively absorbed COX-2 by lung cancer cell-derived exosomes. Following incubation with exosomes, the COX-2 protein level was increased in the THP-1 cells; however, COX-2 mRNA expression was not affected. Moreover, prostaglandin E2 (PGE2) and vascular endothelial growth factor (VEGF) production by THP-1 cells was increased following incubation with exosomes from celecoxib-treated lung cancer cells. Conditioned medium from THP-1 following incubation with exosomes promoted formation in EA.hy926 cells. Taken together, our findings suggest that celecoxib induces COX-2 expression in lung cancer cells, and that highly expressed COX-2 in exosomes can be transferred to other cells.

Stimulation of diuresis and natriuresis by renomedullary infusion of a dual inhibitor of fatty acid amide hydrolase and monoacylglycerol lipase

The renal medulla, considered critical for the regulation of salt and water balance and long-term blood pressure control, is enriched in anandamide and two of its major metabolizing enzymes, cyclooxygenase-2 (COX-2) and fatty acid amide hydrolase (FAAH). Infusion of anandamide (15, 30, and 60 nmol·min^-1·kg^-1) into the renal medulla of C57BL/6J mice stimulated diuresis and salt excretion in a COX-2- but not COX-1-dependent manner. To determine whether endogenous endocannabinoids in the renal medulla can elicit similar effects, the effects of intramedullary isopropyl dodecyl fluorophosphate (IDFP), which inhibits the two major endocannabinoid hydrolases, were studied. IDFP treatment increased the urine formation rate and sodium excretion in a COX-2- but not COX-1-dependent manner. Neither anandamide nor IDFP affected the glomerular filtration rate. Neither systemic (0.625 mg·kg^-1·30 min^-1 iv) nor intramedullary (15 nmol·min^-1·kg^-1·30 min^-1) IDFP pretreatment before intramedullary anandamide (15-30 nmol·min^-1·kg^-1) strictly blocked effects of anandamide, suggesting that hydrolysis of anandamide was not necessary for its diuretic effect. Intramedullary IDFP had no effect on renal blood flow but stimulated renal medullary blood flow. The effects of IDFP on urine flow rate and medullary blood flow were FAAH-dependent as demonstrated using FAAH knockout mice. Analysis of mouse urinary PGE₂ concentrations by HPLC-electrospray ionization tandem mass spectrometry showed that IDFP treatment decreased urinary PGE₂ These data are consistent with a role of FAAH and endogenous anandamide acting through a COX-2-dependent metabolite to regulate diuresis and salt excretion in the mouse kidney.

Distinct effects of dietary flax compared to fish oil, soy protein compared to casein, and sex on the renal oxylipin profile in models of polycystic kidney disease

Oxylipins are bioactive lipids derived from polyunsaturated fatty acids (PUFA) that are important regulators of kidney function and health. Targeted lipidomic analyses of renal oxylipins from four studies of rodent models of renal disease were performed to investigate the differential effects of dietary flax compared to fish oil, soy protein compared to casein, and sex. Across all studies, dietary fish oil was more effective than flax oil in reducing n-6 PUFA derived oxylipins and elevating eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derived oxylipins, whereas dietary flax oil resulted in higher α-linolenic acid (ALA) oxylipins. Dietary soy protein compared to casein resulted in higher linoleic acid (LA) derived oxylipins. Kidneys from females had higher levels of arachidonic acid (AA) oxylipins, but similar or lower levels of oxylipins from other PUFA. Modulation of the oxylipin profile by diet and sex may help elucidate their effects on renal physiology and health.

Radiochemistry on electrodes: Synthesis of an 18F-labelled and in vivo stable COX-2 inhibitor

New radiochemistry techniques can yield novel PET tracers for COX-2 and address the shortcomings in in vivo stability and specificity, which have held back clinical translation of tracers to image COX-2 expression. Current techniques limit radiosynthesis to analogs of the COX-2 inhibitors with fluorine-18 added via a carbon chain, or on an aromatic position which renders the radiolabeled analog less specific towards COX-2, resulting in tracers with low in vivo stability or specificity. To solve this problem, we have developed a new high affinity, ¹⁸F-labelled COX-2 inhibitor that is radiolabeled directly on a heteroaromatic ring. This molecule exhibits favorable biodistribution and increased metabolic stability. Synthesis of this molecule cannot be achieved by traditional means; consequently, we have developed an automated electrochemical radiosynthesis platform to synthesize up to 5 mCi of radiochemically pure ¹⁸F-COX-2ib in 4 hours (2% decay-corrected radiochemical yield). In vitro studies demonstrated clear correlation between COX-2 expression and uptake of the tracer. PET imaging of healthy animals confirmed that the molecule is excreted from blood within an hour, mainly through the hepatobiliary excretion pathway. In vivo metabolism data demonstrated that > 95% of the injected radioactivity remains in the form of the parent molecule 1 hour after injection.

Anti-interleukin-33 Reduces Ovalbumin-Induced Nephrotoxicity and Expression of Kidney Injury Molecule-1

Purpose:

To evaluate the effect of anti-interleukin-33 (anti-IL-33) on a mouse model of ovalbumin (OVA)-induced acute kidney injury (AKI).

Methods:

Twenty-four female BALB/c mice were assigned to 4 groups: group A (control, n=6) was administered sterile saline intraperitoneally (i.p.) and intranasally (i.n.); group B (allergic, n=6) was administered i.p./i.n. OVA challenge; group C (null treatment, n=6) was administered control IgG i.p. before OVA challenge; and group D (anti-IL-33, n=6) was pretreated with 3.6 µg of anti-IL-33 i.p. before every OVA challenge. The following were evaluated after sacrifice: serum blood urea nitrogen and creatinine levels, Kidney injury molecule-1 gene (Kim-1) and protein (KIM-1) expression in renal parenchyma, and expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), phosphorylated endothelial NOS (p-eNOS), and phosphorylated AMP kinase (p-AMPK) proteins in renal parenchyma.

Results:

After OVA injection and intranasal challenge, mice in groups B and C showed significant increases in the expression of Kim-1 at both the mRNA and protein levels. After anti-IL-33 treatment, mice in group D showed significant Kim-1 down-regulation at the mRNA and protein levels. Group D also showed significantly lower COX-2 protein expression, marginally lesser iNOS expression than groups B and C, and p-eNOS and p-AMPK expression at baseline levels.

Conclusions:

Kim-1 could be a useful marker for detecting early-stage renal injury in mouse models of OVA-induced AKI. Further, anti-IL-33 might have beneficial effects on these mouse models.

Anandamide and its metabolites: what are their roles in the kidney?

Anandamide (AEA) is the N-acyl ethanolamide of arachidonic acid, an agonist of cannabinoid and non-cannabinoid receptors in the body. The kidneys are enriched in AEA and in enzymes that metabolize AEA, but the roles of AEA and its metabolites in the kidney remain poorly understood. This system likely is involved in the regulation of renal blood flow and hemodynamics and of tubular sodium and fluid reabsorption. It may act as a neuromodulator of the renal sympathetic nervous system. AEA and its cyclooxygenase-2 metabolites, the prostamides, in the renal medulla may represent a unique antihypertensive system involved in the long-term control of blood pressure. AEA and its metabolites are also implicated as modulators of inflammation and mediators of signaling in inflammation. AEA and its metabolites may be influential in chronic kidney disease states associated with inflammation and cardiovascular diseases associated with hyperhomocysteinemia. The current knowledge of the roles of AEA and its derivatives highlights the need for further research to define and potentially exploit the role of this endocannabinoid system in the kidney.

A fetal sheep model for studying compensatory mechanisms in the healthy contralateral kidney after unilateral ureteral obstruction

INTRODUCTION

Fetal unilateral ureteral obstruction (UUO) triggers complex pathophysiology involving not only the affected organ but also the contralateral kidney, which undergoes evident compensatory changes.

OBJECTIVE

We hypothesized that it would be possible to characterize a transcriptomic fingerprint and selected molecular mechanisms for compensatory growth of contralateral kidneys in UUO, specifically focusing on mediators, carriers, membrane transport, and organ crosstalk in an ovine fetal UUO model.

STUDY DESIGN

A fetal ovine model of complete UUO was created on the 60th day of gestation. For transcriptomics profiling, total RNA was extracted from vital renal biopsies of contralateral (non-obstructed) kidneys harvested on the 80th day of gestation, and kidneys of untreated fetuses served as controls. Statistical analysis provided the set of differentially regulated genes further forwarded to bioinformatics analysis for identification of eventual compensatory molecular mechanisms. Histological analysis was performed with hematoxylin and eosin and periodic acid-Schiff stains.

RESULTS

Contralateral kidneys showed compensatory hypertrophic renal growth, represented on the molecular side by 324 protein coding genes differentially regulated compared with the control kidney samples. Bioinformatics analysis identified an interactome (Figure) consisting of 102 genes with 108 interactions mainly involving transporters (protein transport and protein localization as well as in protein degradation), signaling molecules, DNA/nucleotide/RNA processing, and components of catabolism and cell cycle regulation. Within the interactome, nine receptors were identified as differentially regulated on the contralateral kidney, involving potential renoprotective ligands of the prostaglandin and the bradykinin receptor, arginine vasopressin receptor 1B, and integrin beta 4. Interestingly, a broad range of molecules found differentially expressed, has been previously described in stress response, renoprotection and repair (e.g., MAPK3, MCP1, DICER1, and others).

DISCUSSION

The compensatory renal growth interactome provides a network of transcripts significantly altered in the contralateral kidney, potentially allowing novel insights into mechanisms, interactions, and signaling pathways associated with compensatory growth, and renal protection and repair. Interestingly, the finding of an embedded gene signature reflecting signaling and communication suggests a key role of these processes in CRG either by crosstalk, soluble substances, carriers, or membrane signaling.

CONCLUSIONS

Using a transcriptomics approach, it was possible to identify a gene expression fingerprint of contralateral renal growth in a fetal UUO model. Further studies are warranted to validate those processes and to allow incorporation of this knowledge in new fetal diagnostic or even therapeutic strategies.

Physiology and pathophysiology of cyclooxygenase-2 and prostaglandin E2 in the kidney

The cyclooxygenase (COX) enzyme system is the major pathway catalyzing the conversion of arachidonic acid into prostaglandins (PGs). PGs are lipid mediators implicated in a variety of physiological and pathophysiological processes in the kidney, including renal hemodynamics, body water and sodium balance, and the inflammatory injury characteristic in multiple renal diseases. Since the beginning of 1990s, it has been confirmed that COX exists in 2 isoforms, referred to as COX-1 and COX-2. Even though the 2 enzymes are similar in size and structure, COX-1 and COX-2 are regulated by different systems and have different functional roles. This review summarizes the current data on renal expression of the 2 COX isoforms and highlights mainly the role of COX-2 and PGE2 in several physiological and pathophysiological processes in the kidney.

Indomethacin, amiloride, or eplerenone for treating hypokalemia in Gitelman syndrome

Patients with Gitelman syndrome (GS), an inherited salt-losing tubulopathy, are usually treated with potassium-sparing diuretics or nonsteroidal anti-inflammatory drugs and oral potassium and magnesium supplementations. However, evidence supporting these treatment options is limited to case series studies. We designed an open-label, randomized, crossover study with blind end point evaluation to compare the efficacy and safety of 6-week treatments with one time daily 75 mg slow-release indomethacin, 150 mg eplerenone, or 20 mg amiloride added to constant potassium and magnesium supplementation in 30 patients with GS (individual participation: 48 weeks). Baseline plasma potassium concentration was 2.8±0.4 mmol/L and increased by 0.38 mmol/L (95% confidence interval [95% CI], 0.23 to 0.53; P<0.001) with indomethacin, 0.15 mmol/L (95% CI, 0.02 to 0.29; P=0.03) with eplerenone, and 0.19 mmol/L (95% CI, 0.05 to 0.33; P<0.01) with amiloride. Fifteen patients became normokalemic: six with indomethacin, three with eplerenone, and six with amiloride. Indomethacin significantly reduced eGFR and plasma renin concentration. Eplerenone and amiloride each increased plasma aldosterone by 3-fold and renin concentration slightly but did not significantly change eGFR. BP did not significantly change. Eight patients discontinued treatment early because of gastrointestinal intolerance to indomethacin (six patients) and hypotension with eplerenone (two patients). In conclusion, each drug increases plasma potassium concentration in patients with GS. Indomethacin was the most effective but can cause gastrointestinal intolerance and decreased eGFR. Amiloride and eplerenone have similar but lower efficacies and increase sodium depletion. The benefit/risk ratio of each drug should be carefully evaluated for each patient.

ROS dependence of cyclooxygenase-2 induction in rats subjected to unilateral ureteral obstruction

Oxidative stress resulting from unilateral ureteral obstruction (UUO) may be aggravated by increased production of ROS. Previous studies have demonstrated increased cyclooxygenase (COX)-2 expression in renal medullary interstitial cells (RMICs) in response to UUO. We investigated, both in vivo and in vitro, the role of ROS in the induction of COX-2 in rats subjected to UUO and in RMICs exposed to oxidative and mechanical stress. Rats subjected to 3-day UUO were treated with two mechanistically distinct antioxidants, the NADPH oxidase inhibitor diphenyleneiodonium (DPI) and the complex I inhibitor rotenone (ROT), to interfere with ROS production. We found that UUO-mediated induction of COX-2 in the inner medulla was attenuated by both antioxidants. In addition, DPI and ROT reduced tubular damage and oxidative stress after UUO. Moreover, mechanical stretch induced COX-2 and oxidative stress in RMICs. Likewise, RMICs exposed to H2O2 as an inducer of oxidative stress showed increased COX-2 expression and activity, both of which were reduced by DPI and ROT. Similarly, ROS production, which was increased after exposure of RMICs to H2O2, was also reduced by DPI and ROT. Furthermore, oxidative stress-induced phosphorylation of ERK1/2 and p38 was blocked by both antioxidants, and inhibition of ERK1/2 and p38 attenuated the induction of COX-2 in RMICs. Notably, COX-2 inhibitors further exacerbated the oxidative stress level in H2O2-exposed RMICs. We conclude that oxidative stress as a consequence of UUO stimulates COX-2 expression through the activation of multiple MAPKs and that the induction of COX-2 may exert a cytoprotective function in RMICs.

The pain management in orthodontics

Pain and discomfort are the frequent side-effects of the orthodontic therapy with fixed appliances. The people who experience orthodontic pain are likely to self-medicate with nonprescription pain relievers before seeing the dentist. It is imperative for an orthodontist to address questions that might arise in a clinical setting from the viewpoint of the clinicians and the patients/parents. This article will provide an overview of the current management strategies which are employed for alleviating orthodontic pain.

Pharmacogenetics of nonsteroidal anti-inflammatory drugs

With the beginning of the Human Genome Project, an emerging field of science was brought to the forefront of the pharmaceutical community. Pharmacogenetics facilitates optimization of the current patient-centered care model and pharmacotherapy as a whole. Utilizing these ever-expanding branches of science to nonsteroidal anti-inflammatory drugs (NSAIDs) can provide novel opportunities to affect patient care. With a wide range of NSAID choices available as treatment options for relieving pain and/or reducing inflammation or fever, a more systematic way of selecting the ideal agent for the patients based upon their genetic information could spare them from a potentially permanent health-care condition. Furthermore, if a patient possesses or lacks certain alleles, serious adverse events can be anticipated and avoided. The tailoring of drug therapy can be achieved using the published data and cutting-edge genetic testing to attain a higher standard of care for patients.

Effect of selective and non-selective cyclooxygenase inhibitors on doxorubicin-induced cardiotoxicity and nephrotoxicity in rats

CONTEXT

Doxorubicin (DX) is a highly effective chemotherapeutic agent used widely in the treatment of solid tumors; however, its optimal use was associated with cardiotoxicity and nephrotoxicity. The exact mechanism of DX-induced cardiotoxicity and nephrotoxicity is not fully explored. Induction of cyclooxygenase-2 (COX-2) activity in either cardiac or renal tissue by DX has been previously reported, indicating a possible role of COX-2 in DX-induced tissue injury. However, the nature of this role in either tissue injury is an issue of controversy.

OBJECTIVE

This study was the first that simultaneously evaluated the effects of a selective COX-2 inhibitor, nimesulide, and a non-selective COX-inhibitor, indomethacin, on DX-induced cardiotoxicity and nephrotoxicity in male Wistar rats.

MATERIALS AND METHODS

Rats were allocated into four groups. Control group, DX group (received 15 mg/kg, ip), DX + nimesulide (10 mg/kg/day, po) group, and DX + indomethacin (2 mg/kg/day, po) group. Nimesulide and indomethacin were started at the same day of DX injection and continued for 5 days.

RESULTS

The results of the present study showed that inhibition of COX-2 either by selective or non-selective COX-2 inhibitor ameliorated DX-induced cardiotoxicity but aggravated DX-induced nephrotoxicity in rats, as evidenced biochemically and histopathologically.

DISCUSSION AND CONCLUSION

Our study indicates that production of COX-2 is organ specific; consequently, the differential effect of COX-inhibitors should be considered in DX-treated patients. However, a wide scale experiment is needed for further confirmation and testing other members of COX-inhibitors (e.g. celecoxib and diclofenac).

Human glomerular endothelium: interplay among glucose, free fatty acids, angiotensin II, and oxidative stress

Glomerular endothelial cells (GEC) are strategically situated within the capillary loop and adjacent to the glomerular mesangium. GEC serve as targets of metabolic, biochemical, and hemodynamic signals that regulate the glomerular microcirculation. Unequivocally, hyperglycemia, hypertension, and the local renin-angiotensin system partake in the initiation and progression of diabetic nephropathy (DN). Whether free fatty acids (FFA) and reactive oxygen species (ROS) that have been associated with the endothelial dysfunction of diabetic macrovascular disease also contribute to DN is not known. Since endothelial cells from different organs and from different species may display different phenotypes, we employed human GEC to investigate the effect of high glucose (22.5 mmol/l), FFA (800 micromol/l), and angiotensin II (ANG II; 10(-7) mol/l) on the genesis of ROS and their effects on endothelial nitric oxide synthase (eNOS), cyclooxygenase-2 (COX-2), and the synthesis of prostaglandins (PGs). We demonstrated that high glucose but not high FFA increased the expression of a dysfunctional eNOS as well as increased ROS from NADPH oxidase (100%) and likely from uncoupled eNOS. ANG II also induced ROS from NADPH oxidase. High glucose and ANG II upregulated (100%) COX-2 via ROS and significantly increased the synthesis of prostacyclin (PGI(2)) by 300%. In contrast, FFA did not upregulate COX-2 but increased PGI(2) (500%). These novel studies are the first in human GEC that characterize the differential role of FFA, hyperglycemia, and ANG II on the genesis of ROS, COX-2, and PGs and their interplay in the early stages of hyperglcyemia.

The effect of parecoxib on kidney function at laparoscopic hysterectomy

Conventional nonsteroidal anti-inflammatory drugs (NSAIDs) have a well-documented nephrotoxic action. Still, there are only few studies that have investigated the nephrotoxicity of cyclo-oxycenase-2-inhibitors during the perioperative period. Thirty patients scheduled for elective laparoscopic hysterectomy were enrolled in this prospective, randomized double-blind study. Patients were randomized into two groups: a saline-treated control group (placebo) and 80 mg parecoxib-treated group (parecoxib). The samples for the analyses of serum and urine were collected at the induction of anesthesia, two hours thereafter, two hours from the end of anesthesia, and on the first postoperative day (POD). S-crea, S-urea, S-cystatin C, S-Na, S-K, U-1mikroglobulin/U-crea, U-GST/U-crea, and U-GST/U-crea were analyzed from the samples. Urine output was measured every hour for the first five hours, and total amount of urine was measured until the first postoperative day. There were no clinical and few statistical significant differences between the two groups in the renal measurements during the study period. The urinary output was also similar in the two groups. A single dose of 80 mg of parecoxib was well tolerated by the kidneys in the short-term perioperative use in patients undergoing laparoscopic hysterectomy with ASA physiological status I-II and age under 60 years.

Effects of lipids on ENaC activity in cultured mouse cortical collecting duct cells

Direct effects on epithelial Na+ channels (ENaC) activity by lipids, e.g., arachidonic acid (AA), eicosatetraynoic acid (ETYA), linoleic acid (LA), stearic acid (SA), hydroxyeicosatetraenoic acid (HETE), 11,12-epoxyeicosatrienoic acid (EET), (PGF2), and (PGE2), in cultured mouse cortical collecting duct (M1) cells were clarified by using single-channel recordings in this study. In a cell-attached recording, a bath application of 10 microM AA significantly reduced the ENaC open probability (NPo), whereas 10 microM ETYA or 5 microM LA only induced a slight inhibition. The inside-out recording as a standard protocol was thereafter performed to examine effects of these lipids on ENaC activity. Within 10 min after the formation of the inside-out configuration, the NPo of ENaC in cultured mouse cortical collecting duct (M1) cells remained relatively constant. Application of ETYA or LA or SA exhibited a similar inhibition on the channel NPo when applied to the extracellular side, suggesting that fatty acids could exert a nonspecific inhibition on ENaC activity. 11,12-EET, a metabolite of AA via the cytochrome P450 epoxygenase pathway, significantly inhibited the ENaC NPo, whereas 20-HETE, a metabolite of AA via the hydroxylase pathway, only caused a small inhibition of the ENaC NPo, to a similar degree as that seen with ETYA and LA. However, both PGE2 and PGF2alpha significantly enhanced the ENaC NPo. These results suggest that fatty acids exert a nonspecific effect on ENaC activity due to the interaction between the channel proximity and the lipid. The opposite effects of 11,12-EET and prostaglandin (PG) implicate different mechanisms in regulation of ENaC activity by activation of epoxygenase and cyclooxygenase.

Succinate receptor GPR91 provides a direct link between high glucose levels and renin release in murine and rabbit kidney

Diabetes mellitus is the most common and rapidly growing cause of end-stage renal disease in developed countries. A classic hallmark of early diabetes mellitus includes activation of the renin-angiotensin system (RAS), which may lead to hypertension and renal tissue injury, but the mechanism of RAS activation is elusive. Here we identified a paracrine signaling pathway in the kidney in which high levels of glucose directly triggered the release of the prohypertensive hormone renin. The signaling cascade involved the local accumulation of succinate and activation of the kidney-specific G protein-coupled metabolic receptor, GPR91, in the glomerular endothelium as observed in rat, mouse, and rabbit kidney sections. Elements of signal transduction included endothelial Ca2+, the production of NO and prostaglandin (PGE2), and their paracrine actions on adjacent renin-producing cells. This GPR91 signaling cascade may serve to modulate kidney function and help remove metabolic waste products through renal hyperfiltration, and it could also link metabolic diseases, such as diabetes, or metabolic syndrome with RAS overactivation, systemic hypertension, and organ injury.

Pulmonary and cardiorenal cyclooxygenase-1 (COX-1), -2 (COX-2), and microsomal prostaglandin E synthase-1 (mPGES-1) and -2 (mPGES-2) expression in a hypertension model

Hypertensive mice that express the human renin and angiotensinogen genes are used as a model for human hypertension because they develop hypertension secondary to increased renin-angiotensin system activity. Our study investigated the cellular localization and distribution of COX-1, COX-2, mPGES-1, and mPGES-2 in organ tissues from a mouse model of human hypertension. Male (n = 15) and female (n = 15) double transgenic mice (h-Ang 204/1 h-Ren 9) were used in the study. Lung, kidney, and heart tissues were obtained from mice at necropsy and fixed in 10% neutral buffered formalin followed by embedding in paraffin wax. Cut sections were stained immunohistochemically with antibodies to COX-1, COX-2, mPGES-1, and mPGES-2 and analyzed by light microscopy. Renal expression of COX-1 was the highest in the distal convoluted tubules, cortical collecting ducts, and medullary collecting ducts; while proximal convoluted tubules lacked COX-1 expression. Bronchial and bronchiolar epithelial cells, alveolar macrophages, and cardiac vascular endothelial cells also had strong COX-1 expression, with other renal, pulmonary, or cardiac microanatomic locations having mild-to-moderate expression. mPGES-2 expression was strong in the bronchial and bronchiolar epithelial cells, mild to moderate in various renal microanatomic locations, and absent in cardiac tissues. COX-2 expression was strong in the proximal and distal convoluted tubules, alveolar macrophages, and bronchial and bronchiolar epithelial cells. Marked mPGES-1 was present only in bronchial and bronchiolar epithelial cells; while mild-to-moderate expression was present in other pulmonary, renal, or cardiac microanatomic locations. Expression of these molecules was similar between males and females. Our work suggests that in hypertensive mice, there are (a) significant microanatomic variations in the pulmonary, renal, and cardiac distribution and cellular localization of COX-1, COX-2, mPGES-1, and mPGES-2, and (b) no differences in expression between genders.

Immunomodulatory effect of selective serotonin reuptake inhibitors (SSRIs) on human T lymphocyte function and gene expression

Antidepressants have an antiproliferative effect in some cell lines. Depression may be associated with activation of some pro-inflammatory cytokines. Therefore, we evaluated the ex-vivo immunomodulatory effect of selective serotonin reuptake inhibitors (SSRIs) in T cells. We found that the SSRIs, paroxetine and sertraline decreased T-cell viability with IC50 around 10 microM. The inhibition obtained with exposure to the SSRIs was more pronounced than that achieved with dexamethasone. Moreover, these SSRIs inhibit the secretion of the TH1 factor-tumor necrosis factor(TNF)alpha from the cells. On the molecular level, the SSRIs suppressed signal transducer and activator of transcription 3 (Stat3) and cyclooxygenase(Cox)2 protein expression. The inhibitory effects were accompanied by alterations in gene expression as assessed in the gene array. These findings reveal an immunomodulatory effect of the SSRIs paroxetine and sertraline in human T cells. The clinical implications of our findings merit further investigation.

Effects of parecoxib and dipyrone on platelet aggregation in patients undergoing meniscectomy: a double-blind, randomized, parallel-group study

BACKGROUND

Based on a PubMed search of the literature using the terms parecoxib, platelets, thromboxane, bleeding, and platelet aggregation, the effects of parecoxib on platelet function have not fully been established under clinical conditions.

OBJECTIVE

The aim of this study was to determine platelet aggregation, thromboxane B(2) (TxB(2)) formation, and plasma concentrations with the use of parecoxib in postoperative pain management.

METHODS

This double-blind, randomized, parallel-group trial was conducted at the University Hospital for Orthopedic Surgery, Friedrichsheim, Frankfurt, Germany. Male and female patients aged 18 to 55 years and scheduled to undergo routine partial meniscectomy (or a similar arthroscopic procedure) were eligible. All patients received dose-adjusted enoxaparin before surgery and parecoxib 40 mg BID or dipyrone 1000 mg QID. Blood samples were drawn before first injection (predose) and at 0.5, 2, and 6 hours after injection. Platelet aggregation (expressed as percentage of the maximal light transmittance [A(max)]) was induced with arachidonic acid (A(max)AA) and collagen (A(max)CO). TxB(2) formation was determined using enzyme-linked immunosorbent assay.

RESULTS

This study included 26 patients. In both treatment groups, 8 males and 5 females, all white, were enrolled. In the dipyrone group, the mean age was 48 years (range, 32-61 years) and the mean weight was 85 kg (range, 63-122 kg); in the parecoxib group, the mean age was 47 years (range, 31-61 years) and the mean weight was 81 kg (range, 57-100 kg). Median (interquartile range [IQR]) predose values for A(max)AA were 76% (65%-83%) in the parecoxib group and 87% (80%-89%) in the dipyrone group. At 0.5 hour after injection, A(max)AA was 52% (5%-77%) with parecoxib and 8% (0%-11%) with dipyrone (P=0.004). At 2 hours after injection, A(max)AA was 78% (72%-80%) in the parecoxib group versus 7% (5%-11%) in the dipyrone group (P<0.001). At 6 hours after study drug administration, no treatment differences were found. For A(max)CO, no statistically significant differences were found. Consistent with the stronger inhibition of aggregation, patients who received dipyrone had lower TxB(2) formation values. Six hours after parecoxib administration, mean TxB(2) formation was significantly enhanced compared with predose values (132 ng/mL [IQR, 62-228 ng/mL] vs 185 ng/mL [IQR, 135-239 ng/mL]; P=0.05).

CONCLUSIONS

Platelet aggregation and TxB(2) formation were significantly lower for 6 hours in dipyronetreated patients compared with parecoxib-treated patients. In contrast, TxB(2) formation was increased with parecoxib 6 hours after administration compared with pretreatment values. In this small study, parecoxib did not affect platelet aggregation in a population of patients undergoing routine partial meniscectomy (or a similar arthroscopic procedure) under clinical conditions.

Effect of a cyclooxygenase-2 inhibitor on interleukin-1beta-stimulated activation of the transcription factor nuclear factor-kappa B in human gingival fibroblasts

BACKGROUND

In previous work, the cyclooxygenase-2 inhibitor NS-398 inhibited interleukin (IL)-1beta-stimulated prostaglandin E(2) (PGE(2)) production almost completely while partially inhibiting IL-6 production in aggressive periodontitis (AgP) human gingival fibroblasts. PGE(2) and the transcription factor nuclear factor-kappa B (NF-kappaB) regulate IL-1beta-stimulated IL-6 production. Cytoplasmic NF-kappaB is bound to inhibitors (IkappaB proteins). IL-1beta initiates a cascade resulting in phosphorylation and degradation of IkappaB, allowing nuclear translocation of NF-kappaB and target gene activation. The purpose of this study was to determine whether NS-398 inhibited phosphorylation of IkappaB and NF-kappaB activation.

METHODS

AgP fibroblasts (1 to 2 x 10(6)) were exposed to IL-1beta (1 x 10(11)M) with or without NS-398 (10 nM) in serum-free medium. The NF-kappaB subunit p65 and phospho-IkappaBalpha were measured in whole cell, cytoplasmic, or nuclear extracts, using colorimetric assays. Enzyme-linked immunosorbent assays were used to measure PGE(2) and IL-6 production by 2.5 x 10(4) cells after exposure to IL-1beta with or without NS-398 in serum-free medium.

RESULTS

Consistent with previous results, NS-398 reduced IL-1beta-stimulated PGE(2) by approximately 98% (P <0.001) and IL-6 by approximately 65% (P <0.001). IL-1beta increased nuclear and cytoplasmic p65 ( approximately 8-fold [P <0.001] and approximately 2.5-fold [P <0.03], respectively) over control levels. NS-398 reduced IL-1beta-stimulated nuclear and cytoplasmic p65 to control levels. IL-1beta increased phospho-IkappaBalpha in whole cell extracts by a maximum of approximately 9.5 times (P = 0.0001), and this was inhibited significantly by NS-398 (P <or=0.008).

CONCLUSIONS

NS-398 inhibited NF-kappaB activation and nuclear p65 levels in human gingival fibroblasts. This seemed to be due to inhibition of the phosphorylation cascade resulting in formation of phospho-IkappaBalpha and free p65. NF-kappaB inhibition may be useful in treating inflammatory diseases such as AgP.

Cyclooxygenases in rat Leydig cells: effects of luteinizing hormone and aging

Previous studies suggested that increased Leydig cell cyclooxygenase (COX)2 expression may be involved in the reduced testosterone production that characterizes aged Leydig cells. Our objective herein was to further elucidate the relationships among LH stimulation, Leydig cell COX2 and COX1 expression, aging, and testosterone production. Incubation of Leydig cells from young or aged rats with LH or dibutyryl cAMP resulted in increases in both intracellular COX2 protein expression and testosterone production. COX1 expression did not respond to LH or dibutyryl cAMP. Incubation of adult cells with a protein kinase A inhibitor suppressed the stimulatory effects of LH on COX2 and testosterone production. Short-term incubation of Leydig cells with TGF-alpha or IL-1beta also increased COX2 protein levels; IGF-I had no effect. In vivo, LH also was found to stimulate both COX2 and testosterone, but not COX1. As reported previously, COX2 expression was greater in old than in young cells, and old Leydig cells responded to inhibition of COX2 in vitro with increased testosterone production. However, the effects of the COX2 inhibitors were not restricted to old cells; young Leydig cells also responded to COX2 inhibition with increased testosterone production. This and the observation that the incubation of young or old cells with LH resulted in increased COX2 and testosterone production in both cases suggests that the relationship between COX2 and testosterone production is not unique to aged Leydig cells. Moreover, the close correlation between increases in COX2 and testosterone in LH-stimulated young and aged Leydig cells is difficult to reconcile with the contention that the increased expression of COX2 in aged cells is responsible for age-related suppression of Leydig cell testosterone production.

Extent of renal effect of cyclo-oxygenase-2-selective inhibitors is pharmacokinetic dependent

Non-steroidal anti-inflammatory drugs (NSAIDs) cause renal side-effects. In the present study, we tested the hypothesis that the extent of the renal effects of cyclo-oxygenase (COX)-2-selective NSAIDs is linked to their pharmacokinetics. A single oral dose of rofecoxib (10 mg/kg), celecoxib (40 mg/kg), meloxicam (3 mg/kg) or placebo was administered to rats. Urinary excretion of electrolytes, a marker of renal effects, and plasma and kidney concentrations of NSAIDs were measured. Rofecoxib and celecoxib, but not meloxicam, significantly decreased urinary sodium and potassium excretion. There was a significant correlation between the area under the 24 h plasma concentration-time curve (AUC0-24) of rofecoxib and the change in sodium (r = -0.65; P < 0.02) and potassium (r = -0.82; P < 0.0006) excretion. The AUC0-24 of celecoxib was correlated with sodium (r = -0.80; P < 0.05) but not potassium excretion. The ratios of kidney to plasma drug concentrations were 1.72, 3.16 and 0.17 for rofecoxib, celecoxib and meloxicam, respectively. The renal effect of the COX-2-selective NSAIDs examined, marked by their ability to reduce the excretion of electrolytes, is influenced by systemic exposure to the drugs. The relatively higher distribution into the kidneys of rofecoxib and celecoxib compared with meloxicam suggests involvement of direct drug exposure in the kidneys in the adverse renal effect.

Expression of cyclooxygenase-2 in Wilms tumor: immunohistochemical study using tissue microarray methodology

PURPOSE

Cyclooxygenase-2, a key enzyme in prostaglandin biosynthesis, has been shown to be involved in the modulation of cell growth, inflammation and apoptosis. Its involvement in the development of several human neoplasms has also been documented as well as the significant antitumor effects of its inhibitors. To our knowledge cyclooxygenase-2 expression in Wilms tumor has not been studied.

MATERIALS AND METHODS

A tissue microarray multitissue block was prepared from 14 samples of Wilms tumor, each from a different patient, from xenografts derived thereof, and from normal human lung, liver, renal cortex and medulla tissues as controls. Each sample was represented in the block by 3 or 4 cores 0.6 mm in diameter. After serial slicing to 4 mum the histological slides were stained with hematoxylin and eosin, and immunostained with anti-cyclooxygenase-2 antibodies. Immunostaining was graded semiquantitatively according to the percent of stained cells with the cytoplasmic pattern of staining and according to staining intensity.

RESULTS

All authentic human pathological samples except 1 anaplastic Wilms tumor as well as Wilms tumor xenografts expressed cyclooxygenase-2 in all Wilms tumor cellular components except the stroma. Expression was also observed in Wilms tumor lung metastasis and in tumors that overgrew chemotherapy. In comparison, cyclooxygenase-2 expression in normal kidneys was less prominent than in Wilms tumor samples and it was confined to the tubular epithelium in the cortex and medulla.

CONCLUSIONS

Cyclooxygenase-2 expression is characteristic of all nonanaplastic Wilms tumors at all stages. It is similar to the previously observed pan-expression of ErbB2 receptors in these tumors. The potential therapeutic role of cyclooxygenase-2 inhibitors should be evaluated for Wilms tumor.

Expression of mouse membrane-associated prostaglandin E2 synthase-2 (mPGES-2) along the urogenital tract

Prostaglandin E(2) (PGE(2)) is the most common prostanoid and has a variety of bioactivities including a crucial role in urogenital function. Multiple enzymes are involved in its biosynthesis. Among 3 PGE(2) terminal synthetic enzymes, membrane-associated PGE(2) synthase-2 (mPGES-2) is the most recently identified, and its role remains uncharacterized. In previous studies, membrane-associated PGE(2) synthase-1 (mPGES-1) and cytosolic PGE(2) synthase (cPGES) were reported to be expressed along the urogenital tracts. Here we report the genomic structure and tissue distribution of mPGES-2 in the urogenital system. Analysis of several bioinformatic databases demonstrated that mouse mPGES-2 spans 7 kb and consists of 7 exons. The mPGES-2 promoter contains multiple Sp1 sites and a GC box without a TATA box motif. Real-time quantitative PCR revealed that constitutive mPGES-2 mRNA was most abundant in the heart, brain, kidney and small intestine. In the urogenital system, mPGES-2 was highly expressed in the renal cortex, followed by the renal medulla and ovary, with lower levels in the ureter, bladder and uterus. Immunohistochemistry studies indicated that mPGES-2 was ubiquitously expressed along the nephron, with much lower levels in the glomeruli. In the ureter and bladder, mPGES-2 was mainly localized to the urothelium. In the reproductive system, mPGES-2 was restricted to the epithelial cells of the testis, epididymis, vas deferens and seminal vesicle in males, and oocytes, stroma cells and corpus luteum of the ovary and epithelial cells of the oviduct and uterus in females. This expression pattern is consistent with an important role for mPGES-2-mediated PGE(2) in urogenital function.

Nitric oxide stimulates COX-2 expression in cultured collecting duct cells through MAP kinases and superoxide but not cGMP

Collecting ducts are a major site of renal production and action of both prostaglandins and nitric oxide. Experiments were undertaken to examine whether nitric oxide regulates cyclooxygenase (COX)-2 expression and PGE(2) release in cultured collecting duct cells. In mIMCD-K2 cells, sodium nitroprusside (SNP) in the 50- to 800-microM range induced a marked dose- and time-dependent increase in COX-2 protein levels, determined by immunoblotting, and the induction was detectable at 4 h. This was preceded by induction of COX-2 mRNA as determined by real-time-RT-PCR. The COX-2 induction was accompanied by a significant rise in PGE(2) release as determined by enzyme immunoassay. S-nitroso-N-acetylpenicillamine (SNAP) had a similar stimulatory effect on COX-2 expression and PGE(2) release. 8-bromo-cGMP (200 microM) had no effect on COX-2 expression. The SNP-stimulated COX-2 expression was not affected by the guanylyl cyclase inhibitor methylene blue or the protein kinase G inhibitor KT-5823 (2.0 microM). In contrast, the SNP-stimulated COX-2 expression was significantly reduced by either the Erk1/2 inhibitor PD-98059 or the P38 inhibitor SB-203580 and was abolished by combination of the two kinase inhibitors. The stimulation was also significantly blocked by the SOD mimetic tempol. Thus we conclude that NO stimulates COX-2 expression in collecting duct cells through mechanisms involving MAP kinase and superoxide, but not cGMP.