The protective effect of prostacyclin on adriamycin-induced apoptosis in rat renal tubular cells

Molecular signaling pathways in doxorubicin-induced nephrotoxicity and potential therapeutic agents

Doxorubicin (DOX), an anthracycline chemotherapeutic agent, is extensively utilized in the clinical management of both solid and hematological malignancies. Nevertheless, the clinical application of this treatment is significantly limited by adverse reactions and toxicity that may arise during or after administration. Its cytotoxic effects are multifaceted, with cardiotoxicity being the most prevalent side effect. Furthermore, it has the potential to adversely affect other organs, including the brain, kidneys, liver, and so on. Notably, it has been reported that DOX may cause renal failure in patients and there is currently no effective treatment for DOX-induced kidney damage, which has raised a high concern about DOX-induced nephrotoxicity (DIN). Although the precise molecular mechanisms underlying DIN remain incompletely elucidated, prior research has indicated that reactive oxygen species (ROS) are pivotal in this process, triggering a cascade of detrimental pathways including apoptosis, inflammation, dysregulated autophagic flux, and fibrosis. In light of these mechanisms, decades of research have uncovered several DIN-associated signaling pathways and found multiple potential therapeutic agents targeting them. Thus, this review intends to delineate the DIN associated signaling pathways, including AMPK, JAKs/STATs, TRPC6/RhoA/ROCK1, YAP/TEAD, SIRTs, Wnt/β-catenin, TGF-β/Smad, MAPK, Nrf2/ARE, NF-κB, and PI3K/AKT, and to summarize their potential regulatory agents, which provide a reference for the development of novel medicines against DIN.

A current view of G protein-coupled receptor - mediated signaling in pulmonary hypertension: finding opportunities for therapeutic intervention

Pathological vascular remodeling is observed in various cardiovascular diseases including pulmonary hypertension (PH), a disease of unknown etiology that has been characterized by pulmonary artery vasoconstriction, right ventricular hypertrophy, vascular inflammation, and abnormal angiogenesis in pulmonary circulation. G protein-coupled receptors (GPCRs) are the largest family in the genome and widely expressed in cardiovascular system. They regulate all aspects of PH pathophysiology and represent therapeutic targets. We overview GPCRs function in vasoconstriction, vasodilation, vascular inflammation-driven remodeling and describe signaling cross talk between GPCR, inflammatory cytokines, and growth factors. Overall, the goal of this review is to emphasize the importance of GPCRs as critical signal transducers and targets for drug development in PH.

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.

Therapeutic efficacy of bone marrow derived mesenchymal stromal cells versus losartan on adriamycin-induced renal cortical injury in adult albino rats

BACKGROUND

Renal disease is a major health problem. Recent studies have reported the efficacy of stem cell therapy in nephropathy animal models.

AIM OF THE WORK

This study was designed to investigate the therapeutic effectiveness of bone marrow-derived mesenchymal stromal cells (MSCs) versus losartan in the treatment of renal alterations induced by adriamycin (ADR).

MATERIALS AND METHODS

Thirty-five adult male albino rats were divided into four groups. Group I was the control group. Group II (adriamycin-treated group),which included ten rats that were injected with a single dose of adriamycin (15 mg/kg) intraperitoneally, was subdivided into subgroup IIa and IIb and they were sacrificed 1 week and 5 weeks after adriamycin injection, respectively. Group III was the adriamycin + losartan-treated group and 1 week after adriamycin injection five rats received 10 mg/kg of losartan orally and daily for 4 weeks. Group IV was the adriamycin + MSC-treated group); five rats were injected with adriamycin as group II then supplied with MSCs at a dose of 1 × 10(6) cells suspended in 0.5 mL of phosphate-buffered saline (PBS) per rat in the tail vein 1 week after adriamycin injection. Rats of this group were sacrificed 4 weeks after the stem cell injection. Blood urea nitrogen and serum creatinine were measured. Samples from renal cortex were processed for light and electron microscope examination. As regards light microscope, sections were stained with hematoxylin and eosin (H-E), periodic acid-Schiff (PAS), masson trichrome, proliferating cell nuclear antigen (PCNA) and Caspase-3 immunohistochemical stains. Morphometrical and statistical analyses were also conducted.

RESULTS

Examination of adriamycin-treated group revealed deterioration of renal functions and various degrees of renal structural alterations as vacuolated cytoplasm, dark nuclei and detached epithelial lining. Administration of losartan partially improved ADR-induced kidney dysfunction, whereas MSCs denoted a more ameliorative role evidenced by structural and functional recovery.

CONCLUSION

MSCs have a relevant therapeutic potential against ADR-induced renal damage. MSCs may accomplish this role by decreasing caspase-3 expression and increasing proliferating cell nuclear antigen staining which influence the regeneration of the kidney.

Histological study on the protective effect of endogenous stem-cell mobilization in Adriamycin-induced chronic nephropathy in rats

Chronic kidney disease is a global health problem with increasing morbidity and mortality. Therefore, this study was planned to test the protective effect of hematopoietic-stem-cell mobilization by granulocyte colony-stimulating factor (G-CSF) on Adriamycin (ADR)-induced chronic renal disease in rats. Thirty albino rats were equally divided into three groups: control, ADR group [rats received a single intravenous injection of ADR (5 mg/kg)], and G-CSF group [rats received ADR by the same route and the same dose as the previous group, and then G-CSF (70 μg/kg/d) 2 hours after ADR injection then daily for five consecutive days]. At the time of sacrifice (after 6 weeks), blood samples were taken to estimate the blood urea nitrogen and serum creatinine. Kidney sections were stained with hematoxylin and eosin, toluidine blue, Masson's trichrome, periodic acid–Schiff stains, and immunohistochemical staining against CD34 and caspase-3. The G-CSF group exhibited protection against renal injury manifested by reducing blood urea nitrogen and serum-creatinine levels, improving histological architecture, and increasing the proliferative capacity of renal tubules.

Beraprost sodium attenuates cigarette smoke extract-induced apoptosis in vascular endothelial cells

Apoptosis is now widely recognized as an important part of chronic obstructive pulmonary disease (COPD) pathogenesis. Our previous study demonstrated that a prostacyclin (PGI(2)) analogue (beraprost sodium, BPS) prevented cigarette smoke extract (CSE) induced apoptosis of the pulmonary endothelium in rats. So we determined to clarify the apoptosis of vascular endothelial cells in COPD patient and the role of prostacyclin in the protection against apoptosis in vascular endothelial cells induced by CSE. Surgical specimens were obtained from 12 patients with COPD and 10 controls, and the level of apoptosis, prostacyclin synthase (PGI(2)S) expression and 6-keto-PGF1α (a stable metabolite of PGI(2)) were detected. The apoptotic index (AI), caspase-3 activity, expression of caspase-3 and 6-keto-PGF1α were examined in human umbilical vein endothelial cells (HUVECs) under exposure to varied concentrations of CSE for 24 h as well as under exposure to 2.5 % CSE for varied durations. Then, HUVECs under 2.5 % CSE were exposed to varied concentrations of BPS for 24 h and observed the alteration and the level of cAMP. Increased AI, decreased expression of PGI(2)S and 6-keto-PGF1α, were found in the lungs of patients with COPD compared with controls. Moreover, CSE induced apoptosis in means of both dose-dependent and time-dependent manners, and reduced the level of 6-keto-PGF1α in HUVECs. And with the treatment of BPS, an enhanced level of cAMP and decreased apoptosis were detected. The deficiency of PGI(2) critically contributes to the COPD-associated endothelial dysfunction and apoptosis. And BPS protects against the apoptosis in the vascular endothelial cells induced by CSE.

Protective effect of plaunotol against doxorubicin-induced renal cell death

In searching for a safe and effective compound to be used as a chemoprotective agent to prevent toxicity of the anthracyclin doxorubicin to renal cells, the present study demonstrated that plaunotol, a purified acyclic diterpene from Croton stellatopilosus Ohba, showed potential protection against doxorubicin-induced cell death in human proximal tubule cells. Treatment of renal cells with doxorubicin resulted in a significant decrease in viability of the cells, and we next proved that such toxicity was mainly due to apoptotic cell death. Pretreatment of the cells with plaunotol for at least 9 h prior to doxorubicin exposure improved the cells' survival. Plaunotol was shown to up-regulate the anti-apoptotic myeloid cell leukemia-1 (Mcl-1) level whereas it had no effect on the Bcl-2 level. The reduction in Mcl-1 after doxorubicin treatment was shown to be closely associated with the toxic action of the drug, and the increase in Mcl-1 induced by plaunotol pretreatment was able to prevent cell death induced by doxorubicin. Furthermore, the protective effect of plaunotol was evaluated in human lung and melanoma cells. Results indicated that plaunotol had no significantly protective effect in human lung carcinoma cells, whereas it sensitized melanoma cells to drug-induced cell death.

Protective effect of 20-hydroxyeicosatetraenoic acid (20-HETE) on adriamycin-induced toxicity of human renal tubular epithelial cell (HK-2)

20-Hydroxyeicosatetraenoic acid is a cytochrome P4504A11 metabolite of arachidonic acid that plays an important role in the regulation of human renal functions. In the present study, we investigated the role of 20-hydroxyeicosatetraenoic acid on adriamycin induced toxicity in human renal tubular epithelial cells. Results showed that cell viability was decreased significantly and lactate dehydrogenase activity was increased significantly in a concentration-dependent manner when human renal tubular epithelial cells were incubated with adriamycin (10⁻⁷-10⁻³ mol/l) for 24h. In contrast, 20-hydroxyeicosatetraenoic acid (0.1, 1, 10, 50 μmol/l) increased cell survival and decreased lactate dehydrogenase activity concentration dependently in human renal tubular epithelial cells. When 20-hydroxyeicosatetraenoic acid (10, 50 μmol/l) was co-administered with adriamycin (10⁻³ mol/l), it significantly increased cell viability and decreased lactate dehydrogenase activity. On the other hand, N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine (HET-0016) (1 μM), a selective inhibitor of 20-hydroxyeicosatetraenoic acid synthesizing enzyme exaggerated cell viability reduction and lactate dehydrogenase activity augmentation induced by adriamycin. Adriamycin suppressed the expression of cytochrome P4504A11 gene and its protein production in human renal tubular epithelial cells. Furthermore, adriamycin was more effective than N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine at lowering the expression of cytochrome P4504A11 gene and its protein. These results suggest that 20-hydroxyeicosatetraenoic acid may protect adriamycin-induced toxicity of human renal tubular epithelial cells, meanwhile, adriamycin-induced toxicity of human renal tubular epithelial cells possibly involves inhibiting cytochrome P4504A11 expression.

PGI synthase overexpression protects against bleomycin-induced mortality and is associated with increased Nqo 1 expression

The mortality rate for acute lung injury (ALI) is reported to be between 35-40%, and there are very few treatment strategies that improve the death rate from this condition. Previous studies have suggested that signaling through the prostaglandin (PG) I(2) receptor may protect against bleomycin-induced ALI in mice. We found that mice that overexpress PGI synthase (PGIS) in the airway epithelium were significantly protected against bleomycin-induced mortality and had reduced parenchymal consolidation, apoptosis of lung tissue, and generation of F(2)-isoprostanes compared with littermate wild-type controls. In addition, we show for the first time in both in vivo and in vitro experiments that PGI(2) induced the expression of NADP (H): quinoneoxidoreductase 1 (Nqo 1), an enzyme that prevents the generation of reactive oxygen species. PGI(2) induction of Nqo 1 provides a possible novel mechanism by which this prostanoid protects against bleomycin-induced mortality and identifies a potential therapeutic target for human ALI.

Methylguanidine cytotoxicity on HK-2 cells and protective effect of antioxidants against MG-induced apoptosis in renal proximal tubular cells in vitro

Methylguanidine (MG), a small molecule among guanidine compounds, is a product of protein catabolism. The concentration of MG in the serum of uremic patients is nearly 80 times of that in the serum of normal people. The present study was designed to explore the toxic effect of MG on renal proximal tubular cells as well as the protective effect of antioxidants PGE1 and probucol against MG-induced apoptosis in renal proximal tubular cells. HK-2 cells were used as the subject. The cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. N-Acetyl-3-D-glucosaminidase (NAG) activity, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity were determined. Cell apoptosis was determined by flow cytometry (light scatter and propidium iodide/annexin V-FTC fluorescence) and by nuclear staining with Hoechst 33258. Cells were exposed to MG (0.25, 0.5, or 1 mmol/L), MG (0.5 mmol/L) + PGE1 (2 microg/L), and MG (0.5 mmol/L) + probucol (20 micromol/L) respectively for 24 h. MG induced a significant dose-dependent loss of cell viability. Both PGE1 and probucol improved the viability of MG-treated HK-2 cells. Cells showed apoptotic morphology (deepened stain, karyopyknosis, and apoptotic body) when exposed to 0.5 mmol/L MG for 24 h, and the apoptosis ratio was increased compared with the control. The presence of PGE1 or probucol significantly lowered the apoptotic ratio. Moreover, PGE1 or probucol notably decreased the MDA content and increased the SOD activity compared with when the cells were treated with MG only. The results of the present study clearly demonstrate that MG could promote apoptosis of renal proximal tubular cells in vitro. Both PGE1 and probucol could protect renal proximal tubular cells from MG-induced apoptosis.

Peroxisome proliferator-activated receptor alpha plays a crucial role in L-carnitine anti-apoptosis effect in renal tubular cells

BACKGROUND

L-carnitine is synthesized mainly in the liver and kidneys from lysine and methionine from dietary sources. Many reports have shown that L-carnitine can protect certain cells against the toxicity of several anticancer and toxic agents, although the detailed mechanism is poorly understood. In this study, we investigated the protective effect of L-carnitine and its molecular mechanism in renal tubular cells undergoing gentamicin-induced apoptosis.

METHODS

Rat tubular cell line (NRK-52E) and mice were used as the model system. Gentamicin-induced apoptosis in renal tubular cells was examined using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling. We introduced short interfering RNA transfection and gene-deficient mice to investigate the protective mechanism of L-carnitine.

RESULTS

We found that L-carnitine inhibited gentamicin-induced reactive oxygen species generation and correlative apoptotic pathways, resulting in the protection of NRK-52E cells from gentamicin-induced apoptosis. The treatment of L-carnitine also lessened gentamicin-induced renal tubular cell apoptosis in mice. L-carnitine was found to increase the prostacyclin (PGI(2)) generation in NRK-52E cells. The siRNA transfection for PGI(2) synthase significantly reduced L-carnitine-induced PGI(2) and L-carnitine's protective effect. We found that the activity of the potential PGI(2) nuclear receptor, peroxisome proliferator-activated receptor alpha (PPARalpha), was elevated by L-carnitine treatment. The siRNA-mediated blockage of PPARalpha considerably reduced the anti-apoptotic effect of L-carnitine. In PPARalpha-deficient mice, L-carnitine treatment also lost the inhibitory effect on gentamicin-induced apoptosis in kidneys.

CONCLUSIONS

Based on these findings, we suggest that L-carnitine protects renal tubular cells from gentamicin-induced apoptosis through PGI(2)-mediated PPARalpha activation.

Protective effect of beraprost sodium, a stable prostacyclin analog, in the development of cigarette smoke extract-induced emphysema

Chronic inflammation, imbalance of proteolytic and anti-proteolytic activities, oxidative stress, and apoptosis of lung structural cells contribute to the pathogenesis of COPD. Prostacyclin protects cells against apoptosis, has anti-inflammatory properties, partially prevents cigarette smoke extract (CSE)-induced apoptosis of the pulmonary endothelium, and thus may be relevant in the pathogenesis of emphysema. We determined whether a synthetic stable prostacyclin analog, beraprost sodium (BPS), attenuates the development of CSE-induced emphysema and elucidated the molecular mechanisms involved in its effect. Sprague-Dawley rats were treated with BPS and injected with CSE once a week for 3 wk. We measured the DNA damage of cells, the expression of caspase-3, and the activity of matrix metalloproteinase (MMP)-2 and MMP-9. We also analyzed TNFalpha and IL-1beta concentrations and the serum antioxidant activity. BPS prevented the development of CSE-induced emphysema, resulting in significant attenuation in alveolar enlargement and pulmonary parenchymal destruction. BPS inhibited pulmonary apoptosis and induction of MMP-2 and MMP-9 activity. Moreover, the protective effect of BPS was associated with a reduction of the expression of proinflammatory cytokines including TNFalpha and IL-1beta and a normalized biological oxidant activity. BPS introduces all these events, probably by activating cAMP signaling through acting specific prostacyclin receptors. In conclusion, BPS protects against the development of CSE-induced emphysema by attenuating apoptosis, inhibiting proteolytic enzyme activity, reducing inflammatory cytokine levels, and augmenting antioxidant activity. BPS may potentially represent a new therapeutic option in the prevention of emphysema in humans in prospect.

Renal cell apoptosis induced by nephrotoxic drugs: cellular and molecular mechanisms and potential approaches to modulation

Apoptosis plays a central role not only in the physiological processes of kidney growth and remodeling, but also in various human renal diseases and drug-induced nephrotoxicity. We present in a synthetic fashion the main molecular and cellular pathways leading to drug-induced apoptosis in kidney and the mechanisms regulating it. We illustrate them using three main nephrotoxic drugs (cisplatin, gentamicin, and cyclosporine A). We discuss the main regulators and effectors that have emerged as key targets for the design of therapeutic strategies. Novel approaches using gene therapy, antisense strategies, recombinant proteins, or compounds obtained from both classical organic and combinatorial chemistry are examined. Finally, key issues that need to be addressed for the success of apoptosis-based therapies are underlined.

Prostacyclin protects renal tubular cells from gentamicin-induced apoptosis via a PPARalpha-dependent pathway

To study the protective effect of prostacyclin (PGI2) we increased PGI2 production by infected NRK-52E cells with an adenovirus carrying cyclooxygenase-1 and prostacyclin synthase. PGI2 overexpression protected these cells from gentamicin-induced apoptosis by reducing cleaved caspase-3 and caspase-9, cytochrome c, and decreasing generation of reactive oxygen species. Expression of the nuclear receptor of PGI2, peroxisome proliferator-activated receptor-alpha (PPARalpha), was reduced during gentamicin treatment of the cells, while its overexpression significantly inhibited gentamicin-induced apoptosis and the amount of cleaved caspase-3. Transformation with PPARalpha short interfering RNA abolished the protective effect of PGI2 overproduction in gentamicin-treated cells. The PPARalpha activator docosahexaenoic acid given to gentamicin-treated mice significantly reduced the number of apoptotic cells in renal cortex, but this protective effect was not seen in PPARalpha knockout mice. Our study suggests that increased endogenous PGI2 production protects renal tubular cells from gentamicin-induced apoptosis through a PPARalpha-signaling pathway.

Copper-aspirin complex inhibits cyclooxygenase-2 more selectively than aspirin

The antiinflammatory effects of the copper-aspirin complex (Cu-Asp) were more potent than that of Asp in rats or mice with fewer classic adverse effects. The aim of this study was to determine the cause by evaluating Cu-Asp selective inhibition on cyclooxygenases (COX). COX-1 inhibition was evaluated based on 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)) in an endothelial cell model, and COX-2 inhibition was based on prostaglandin E(2) (PGE(2)) in a macrophage model. Radioimmunoassay (RIA) was applied to determine 6-keto-PGF(1alpha) in resting human umbilical vein endothelial cell line (ECV304), and PGE(2) in activated macrophages. The results showed that the inhibition of 6-keto-PGF(1alpha) yield by Cu-Asp (3 to 0.01 mM) was markedly weaker than that by aspirin (Asp); while the inhibition of PGE(2) yield by Cu-Asp (10 to 0.1 mM) was significantly stronger than that by Asp. Based on the inhibition on 6-keto-PGF(1alpha) and PGE(2), the medium inhibitory concentration (IC(50)) of Cu-Asp on COX-1 and on COX-2 was 1.03+/-0.15 mM, and 0.32+/-0.04 mM, respectively. The selective inhibition index on COX-2, IC(50) (COX-1)/IC(50) (COX-2), of Cu-Asp was 3.33+/-0.89, while that of Asp was 0.42+/-0.12. The results suggest that, unlike Asp, Cu-Asp is a relatively selective inhibitor of COX-2 in the present models; the selectivity of Cu-Asp is about seven-fold greater than that of Asp.

Peroxisomal proliferator-activated receptor-alpha protects renal tubular cells from doxorubicin-induced apoptosis

Peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is a transcription factor and has been reported to inhibit cisplatin-mediated proximal tubule cell death. In addition, doxorubicin (Adriamycin)-induced nephrosis in rats is a commonly used experimental model for pharmacological studies of human chronic renal diseases. In this study, we investigated the protective effect of PPAR-alpha on doxorubicin-induced apoptosis and its detailed mechanism in NRK-52E cells and animal models. The mRNA level of PPAR-alpha was found to be reduced by doxorubicin treatment in NRK-52E cells. PPAR-alpha overexpression in NRK-52E cells significantly inhibited doxorubicin-induced apoptosis and the quantity of cleaved caspase-3. Endogenous prostacyclin (PGI(2)) augmentation, which has been reported to protect NRK-52E cells from doxorubicin-induced apoptosis, induced the translocation and activation of PPAR-alpha. The transformation of PPAR-alpha short interfering RNA was applied to silence the PPAR-alpha gene, which abolished the protective effect of PGI(2) augmentation in doxorubicin-treated cells. To confirm the protective role of PPAR-alpha in vivo, PPAR-alpha activator docosahexaenoic acid (DHA) was administered to doxorubicin-treated mice, and it has been shown to significantly reduce the doxorubicin-induced apoptotic cells in renal cortex. However, this protective effect of DHA did not exist in PPAR-alpha-deficient mice. In NRK-52E cells, the overexpression of PPAR-alpha elevated the activity of catalase and superoxide dismutase and inhibited doxorubicin-induced reactive oxygen species (ROS). PPAR-alpha overexpression also inhibited the doxorubicin-induced activity of nuclear factor-kappaB (NF-kappaB), which was associated with the interaction between PPAR-alpha and NF-kappaB p65 subunit as revealed in immunoprecipitation assays. Therefore, PPAR-alpha is capable of inhibiting doxorubicin-induced ROS and NF-kappaB activity and protecting NRK-52E cells from doxorubicin-induced apoptosis.

Prostaglandins in the kidney: developments since Y2K

There are five major PGs (prostaglandins/prostanoids) produced from arachidonic acid via the COX (cyclo-oxygenase) pathway: PGE(2), PGI(2) (prostacyclin), PGD(2), PGF(2alpha) and TXA(2) (thromboxane A(2)). They exert many biological effects through specific G-protein-coupled membrane receptors, namely EP (PGE(2) receptor), IP (PGI(2) receptor), DP (PGD(2) receptor), FP (PGF(2alpha) receptor) and TP (TXA(2) receptor) respectively. PGs are implicated in physiological and pathological processes in all major organ systems, including cardiovascular function, gastrointestinal responses, reproductive processes, renal effects etc. This review highlights recent insights into the role of each prostanoid in regulating various aspects of renal function, including haemodynamics, renin secretion, growth responses, tubular transport processes and cell fate. A thorough review of the literature since Y2K (year 2000) is provided, with a general overview of PGs and their synthesis enzymes, and then specific considerations of each PG/prostanoid receptor system in the kidney.

Prostacyclin prevents pulmonary endothelial cell apoptosis induced by cigarette smoke

RATIONALE

Impaired endothelial cell-dependent vasodilation, inflammation, apoptosis, and proliferation are manifestations of endothelial dysfunction in chronic obstructive pulmonary disease (COPD). Prostacyclin (PGI(2)) is a major product of the cyclooxygenase pathway with potent vasodilatory and antimitogenic properties and may be relevant to endothelial dysfunction in COPD.

OBJECTIVES

To determine if PGI(2) expression is altered in smoking-related lung disease and if it may be protective in COPD-associated endothelial dysfunction.

METHODS

We evaluated, by immunohistochemistry, Western blotting, and polymerase chain reaction, human emphysema tissue compared with normal tissue for expression of prostacyclin synthase (PGI(2)S). We examined the effects of cigarette smoke extract (CSE) and aldehyde components on eicosanoid expression in primary human pulmonary microvascular endothelial cells. Finally, we used a murine model of lung-specific PGI(2)S overexpression and in vitro studies to determine if PGI(2) expression has protective effects on cigarette smoke-induced endothelial apoptosis.

MEASUREMENTS AND MAIN RESULTS

Human emphysema lung tissue exhibited lower PGI(2)S expression within the pulmonary endothelium than in normal lung. In vitro studies demonstrated that CSE, and in particular the alpha,beta unsaturated aldehyde acrolein, suppressed PGI(2)S gene expression, whereas CSE significantly induced the upstream mediators COX-2 and cytosolic phospholipase A2 in human pulmonary microvascular endothelial cells. Mice with lung-specific PGI(2)S overexpression exhibited less endothelial apoptosis after chronic smoke exposure. In vitro, iloprost exhibited protective effects on CSE-induced apoptosis.

CONCLUSIONS

PGI(2) has protective effects in the pulmonary vasculature after acute and chronic cigarette smoke exposure. An imbalance in eicosanoid expression may be important to COPD-associated endothelial dysfunction.

Cyclooxygenase-independent inhibition of H2O2-induced cell death by S-ketoprofen in renal cells

The stress response of the distal tubule to oxidative attack may be relevant to recovery from acute renal failure. In distal tubular Madin-Darby cells (MDCK), H(2)O(2) induced up-regulation of cyclooxygenases (COX-1 and COX-2), prostaglandin-E(2) production and caspase-independent cell death. Cell death was inhibited by S-ketoprofen, but not by the much weaker COX inhibitor R-ketoprofen. Interestingly, we identified 15-deoxy-Delta(12,14)-prostaglandin-J(2) (15d-PGJ(2)), a peroxisome-proliferator activated receptor-gamma agonist, as a lethal prostaglandin whose effect was reproduced by the PPAR-gamma agonist ciglitazone. Nevertheless, H(2)O(2)-induced cell death was unaffected by other non-steroidal anti-inflammatory drugs (NSAIDs) or all-trans-retinoic acid. Moreover, c-Jun-N-terminal kinase inhibitor SP600125 prevented 15-deoxy-Delta(12,14)-PGJ(2)-induced cell death, but not H(2)O(2)-induced cell death. PPAR-gamma antagonist GW9662 showed no affect on the cell death. These results indicated that protection by S-ketoprofen was COX-independent and PPARgamma independent. Moreover, the IC(50) value of the action of S-ketoprofen for the inhibition of H(2)O(2)-induced MDCK cell death ( approximately equal 140microM) was much higher than the IC(50) value for the inhibition of COX-1 and COX-2 activities ( approximately equal 1microM). Further design of S-ketoprofen derivatives devoid of COX inhibitory activity will give opportunity to protect the kidney against oxidative attack while avoiding unwanted effects of NSAID.

Prostaglandin I(2) and E(2) mediate the protective effects of cyclooxygenase-2 in a mouse model of immune-mediated liver injury

Studies of the molecular and cellular mechanisms of concanavalin A (ConA)-induced liver injury have provided important knowledge on the pathogenesis of many liver diseases involving hepatic inflammation. However, studies identifying hepato-protective factors based on the mechanistic understanding of this model are lacking. Evidence suggests that certain prostaglandin (PG) products of cyclooxygenase (COX)-1 and COX-2 provide important anti-inflammatory and cytoprotective functions in some pathophysiological states. In the present study, we demonstrate a protective role of COX-2 derived PGs in ConA-induced liver injury. COX-2(-/-) mice developed much more severe liver damage upon ConA treatment compared with wild-type and COX-1(-/-) mice. Treatment of COX-2(-/-) mice with misoprostol (a PGE(1/2) analog) or beraprost (a PGI(2) analog) significantly decreased ConA-induced liver injury. Data from both in vivo and in vitro experiments demonstrated that misoprostol and beraprost acted directly on hepatic leukocytes, including natural killer (NK)T and T cells, and down-regulated their production of interferon (IFN)-gamma, which are critical in mediating ConA-induced tissue damage. Collectively, the results provide strong evidence that the protective effects of COX-2 within the liver are mediated through the production of PGE(2) and PGI(2), which exert anti-inflammatory functions. These findings suggest that COX-2-derived PGs may have great therapeutic potentials in treating patients with inflammatory liver diseases.