Nonsteroidal anti-inflammatory drugs (NSAIDs) and blood pressure

Endothelial prostacyclin protects the kidney from ischemia-reperfusion injury

Prostacyclin, or PGI₂, is a product of PGI synthase (PGIS), down-stream of cyclooxygenase pathway. PGI₂ has been demonstrated to play an important role in maintaining renal blood flow. Non-steroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygenase are reported to increase the susceptibility of patients to acute kidney injury (AKI). This study explores the role of endothelium-derived prostacyclin in ischemia-reperfusion injury (I/RI). The renal PGIS expression and PGI₂ production markedly increased following I/RI. Loss of one allele of PGIS gene or selective endothelial PGIS deletion (TEK-CRE PGIS^fl/fl mice) caused more severe renal damage following I/RI than control mice. Iloprost, a PGI₂ analog, administered 30 min before the I/R surgery, markedly attenuated the renal damage in both control mice and TEK-CRE PGIS^fl/fl mice. Renal p-PKA expression significantly increased after I/RI in wild-type mice but not in the PGIS deletion mice, consistent with IP receptor mediating the protective effect. Further studies showed that PGIS deficiency was associated with reduced fluorescence microsphere accumulation in the kidney following I/R. Folic acid also induced marked kidney injury; however, endothelial PGIS deletion did not worsen kidney injury compared with wild-type mice. These studies indicate that PGIS-derived PGI₂ can protect the kidney from acute injury caused by ischemia and reperfusion and PGIS/PGI₂ is a potential intervention target for AKI.

Regulation and function of renal medullary cyclooxygenase-2 during high salt loading

Prostaglandins (PGs) are important autocrine/paracrine regulators that contribute to sodium balance and blood pressure control. Along the nephron, the highest amount of PGE₂ is found in the distal nephron, an important site for fine-tuning of urinary sodium and water excretion. Cylooxygenase-2 (COX-2) is abundantly expressed in the renal medulla and its expression along with urinary PGE₂ excretion is highly induced by chronic salt loading. Factors involved in high salt-induced COX-2 expression in the renal medulla include the hypertonicity, fluid shear stress (FSS), and hypoxia-inducible factor-1 alpha (HIF-1 alpha). Site-specific inhibition of COX-2 in the renal medulla of Sprague-Dawley rats causes sodium retention and salt-sensitive hypertension. Together, these results support the concept that renal medullary COX-2 functions an important natriuretic mediator that is activated by salt loading and its products promote sodium excretion and contribute to maintenance of sodium balance and blood pressure.

[Specifics of the use of NSAIDs in senior age]

Nonsteroidal anti-inflammatory drugs (NSAIDs) have a strong analgesic and anti-inflammatory effects and are widely used in clinical practice. Patients with chronic disorders of the joints, in particular the spine, are main consumers of NSAIDs. However, risk factors for side-effects should be taken into consideration in the treatment with NSAIDs, especially in patients of old age. The careful control of treatment taking into account the risk of developing gastrointestinal and cardiovascular events is needed.

Cyclooxygenase-1 inhibition attenuates angiotensin II-salt hypertension and neurogenic pressor activity in the rat

Cyclooxygenase (COX)-derived prostanoids contribute to angiotensin II (ANG II) hypertension (HTN). However, the specific mechanisms by which prostanoids act are unclear. ANG II-induced HTN is caused partly by increased sympathetic nervous system activity, especially in a setting of high dietary salt intake. This study tested the hypothesis that COX-derived prostanoids cause ANG II-salt sympathoexcitation and HTN. Experiments were conducted in conscious rats. Infusion of ANG II (150 ng·kg(-1)·min(-1) sc) caused a marked HTN in rats on 2% salt diet, but a much smaller increase in blood pressure in rats on 0.4% salt diet. The nonselective COX inhibitor ketoprofen (2 mg/kg sc) given throughout the ANG-II infusion period attenuated HTN development in rats on 2% NaCl diet, but not in rats on 0.4% NaCl diet. The acute depressor response to ganglion blockade was used to assess neurogenic pressor activity in rats on 2% NaCl diet. Ketoprofen-treated rats showed a smaller fall in arterial pressure in response to ganglion blockade during ANG-II infusion than did nontreated controls. In additional experiments, ketoprofen-treated rats exhibited smaller increases in plasma norepinephrine levels and whole body norepinephrine spillover than we previously reported in ANG II-salt HTN. Finally, the effects of the selective COX-1 inhibitor SC560 (10 mg·kg(-1)·day(-1) ip) and the selective COX-2 inhibitor nimesulide (10 mg·kg(-1)·day(-1) ip) were investigated. Treatment with SC560 but not nimesulide significantly reduced blood pressure and the depressor response to ganglion blockade in ANG II-salt HTN rats. The results suggest that COX-1 products are critical for sympathoexcitation and the full development of ANG II-salt HTN in rats.

Increased dietary sodium induces COX2 expression by activating NFκB in renal medullary interstitial cells

High salt diet induces renal medullary cyclooxygenase 2 (COX2) expression. Selective blockade of renal medullary COX2 activity in rats causes salt-sensitive hypertension, suggesting a role for renal medullary COX2 in maintaining systemic sodium balance. The present study characterized the cellular location of COX2 induction in the kidney of mice following high salt diet and examined the role of NFκB in mediating this COX2 induction in response to increased dietary salt. High salt diet (8 % NaCl) for 3 days markedly increased renal medullary COX2 expression in C57Bl/6 J mice. Co-immunofluorescence using a COX2 antibody and antibodies against aquaporin-2, ClC-K, aquaporin-1, and CD31 showed that high salt diet-induced COX2 was selectively expressed in renal medullary interstitial cells. By using NFκB reporter transgenic mice, we observed a sevenfold increase of luciferase activity in the renal medulla of the NFκB-luciferase reporter mice following high salt diet, and a robust induction of enhanced green fluorescent protein (EGFP) expression mainly in renal medullary interstitial cells of the NFκB-EGFP reporter mice following high salt diet. Treating high salt diet-fed C57Bl/6 J mice with selective IκB kinase inhibitor IMD-0354 (8 mg/kg bw) substantially suppressed COX2 induction in renal medulla, and also significantly reduced urinary prostaglandin E2 (PGE2). These data therefore suggest that renal medullary interstitial cell NFκB plays an important role in mediating renal medullary COX2 expression and promoting renal PGE2 synthesis in response to increased dietary sodium.

Enhanced pressor response to acute Ang II infusion in mice lacking membrane-associated prostaglandin E2 synthase-1

AIM

To examine the contribution of vascular membrane-associated prostaglandin E2 synthase-1 (mPGES-1) to acute blood pressure homeostasis.

METHODS

Angiotensin II (AngII, 75 pmol·kg⁻¹·min⁻¹) was continuously infused via the jugular vein into wild-type and mPGES-1(-/-) mice for 30 min, and blood pressure was measured by carotid arterial catheterization. RT-PCR and immunohistochemistry were performed to detect the expression and localization of mPGES-1 in the mouse arterial vessels. Mesenteric arteries were dissected from mice of both genotypes to study vessel tension and measure vascular PGE2 levels.

RESULTS

Wild-type and mPGES-1(-/-) mice showed similar blood pressure levels at baseline, and the acute intravenous infusion of AngII caused a greater increase in mean arterial pressure in the mPGES-1(-/-) group, with a similar diuretic and natriuretic response in both groups. mPGES-1 was constitutively expressed in the aortic and mesenteric arteries and vascular smooth muscle cells of wild-type mice. Strong staining was detected in the smooth muscle layer of arterial vessels. Ex vivo treatment of mesenteric arteries with AngII produced more vasodilatory PGE2 in wild-type than in mPGES-1(-/-) mice. In vitro tension assays further revealed that the mesenteric arteries of mPGES-1(-/-) mice exhibited a greater vasopressor response to AngII than those arteries of wild-type mice.

CONCLUSION

Vascular mPGES-1 acts as an important tonic vasodilator, contributing to acute blood pressure regulation.

Nonsteroidal Anti-Inflammatory Drugs and the Kidney

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

Increased dietary NaCl induces renal medullary PGE2 production and natriuresis via the EP2 receptor

A high-NaCl diet induces renal medullary cyclooxygenase (COX)2 expression, and selective intramedullary infusion of a COX2 inhibitor increases blood pressure in rats on a high-salt diet. The present study characterized the specific prostanoid contributing to the antihypertensive effect of COX2. C57BL/6J mice placed on a high-NaCl diet exhibited increased medullary COX2 and microsomal prostaglandin E synthase1 (mPGES1) expression as determined by immunoblot and real-time PCR. Cytosolic prostaglandin E synthase and prostacyclin synthase were not induced by the high-salt diet. Immunofluorescence showed mPGES1 in collecting ducts and interstitial cells. High salt increased renal medullary PGE(2) as determined by gas chromatography/negative ion chemical ionization mass spectrometry. The effect of direct intramedullary PGE(2) infusion was examined in anesthetized uninephrectomized mice. Intramedullary PGE(2) infusion (10 ng/h) increased urine volume (from 3.3 +/- 0.6 to 9.5 +/- 1.6 mul/min) and urine sodium excretion (0.11 +/- 0.02 to 0.32 +/- 0.05 mueq/min). To determine which E-prostanoid (EP) receptor(s) mediated PGE(2)- dependent natriuresis, EP-selective prostanoids were infused. The EP(2) agonist butaprost produced natriuresis (from 0.06 +/- 0.02 to 0.32 +/- 0.05 mueq/min). The natriuretic effect of intramedullary PGE(2) or butaprost was abolished in EP2-deficient mice, which exhibit NaCl-dependent hypertension. In conclusion, a high-salt diet increases renal medullary COX2 and mPGES1 expression, and increases renal medullary PGE(2) synthesis. Renal medullary PGE(2) promotes renal sodium excretion via the EP2 receptor, thereby maintaining normotension in the setting of high salt intake.

Physiological regulation of prostaglandins in the kidney

Cyclooxygenase-derived prostanoids exert complex and diverse functions within the kidney. The biological effect of each prostanoid is controlled at multiple levels, including (a) enzymatic reactions catalyzed sequentially by cyclooxygenase and prostanoid synthase for the synthesis of bioactive prostanoid and (b) the interaction with its receptors that mediate its functions. Cyclooxygenase-derived prostanoids act in an autocrine or a paracrine fashion and can serve as physiological buffers, protecting the kidney from excessive functional changes during physiological stress. Through these actions, prostanoids play important roles in maintaining renal function, body fluid homeostasis, and blood pressure. Renal cortical COX2-derived prostanoids, particularly PGI2 and PGE2, play critical roles in maintaining blood pressure and renal function in volume-contracted states. Renal medullary COX2-derived prostanoids appear to have an antihypertensive effect in individuals challenged with a high-salt diet. Loss of EP2 or IP receptor is associated with salt-sensitive hypertension. COX2 also plays a role in maintaining renal medullary interstitial cell viability in the hypertonic environment of the medulla. Cyclooxygenase-derived prostanoids also are involved in certain pathological processes. The cortical COX2-derived PGI2 participates in the pathogenesis of renal vascular hypertension through stimulating renal renin synthesis and release. COX-derived prostanoids also appear to be involved in the pathogenesis of diabetic nephropathy. COXs, prostanoid synthases, and prostanoid receptors should provide fruitful targets for intervention in the pharmacological treatment of renal disease.

Physiologic and pathophysiologic roles of lipid mediators in the kidney

Small lipids such as eicosanoids exert diverse and complex functions. In addition to their role in regulating normal kidney function, these lipids also play important roles in the pathogenesis of kidney diseases. Cyclooxygenase (COX)-derived prostanoids play important role in maintaining renal function, body fluid homeostasis, and blood pressure. Renal cortical COX2-derived prostanoids, particularly (PGI2) and PGE2 play critical roles in maintaining blood pressure and renal function in volume contracted states. Renal medullary COX2-derived prostanoids appear to have antihypertensive effect in individuals challenged with a high salt diet. 5-Lipoxygenase (LO)-derived leukotrienes are involved in inflammatory glomerular injury. LO product 12-hydroxyeicosatetraenoic acid (12-HETE) is associated with pathogenesis of hypertension, and may mediate angiotensin II and TGFbeta induced mesengial cell abnormality in diabetic nephropathy. P450 hydroxylase-derived 20-HETE is a potent vasoconstrictor and is involved in the pathogenesis of hypertension. P450 epoxygenase derived epoxyeicosatrienoic acids (EETs) have vasodilator and natriuretic effect. Blockade of EET formation is associated with salt-sensitive hypertension. Ceramide has also been demonstrated to be an important signaling molecule, which is involved in pathogenesis of acute kidney injury caused by ischemia/reperfusion, and toxic insults. Those pathways should provide fruitful targets for intervention in the pharmacologic treatment of renal disease.

Review of resistant hypertension

Despite the prevalence of hypertension, blood pressure (BP) can be controlled with effective therapy in most patients. However, in a small percentage of the hypertensive population, BP remains refractory to therapeutic measures. In such patients who have so-called "resistant" hypertension, proper evaluation and assessment have to be undertaken to improve the BP control. There are some situations or factors that may make hypertension control difficult in some patients. Therefore, it is necessary to identify possible reasons for the loss of BP control and rectify them to achieve normotension. In addition to indicated work-up for secondary causes, aggressive treatment (nonpharmacologic and pharmacologic) of hypertension is required to prevent excessive morbidity and mortality in this special population.

[Effect of short-term nonsteroidal antiinflammatory therapy on mean blood pressure. A prospective, randomized clinical trial]

Our objective was to evaluate the effect of short-term therapy with nonsteroidal antiinflammatory drugs (NSAID) on mean blood pressure (MBP). Two hundred thirty-three consecutive patients (185 women, 54 men; 53.9±13.5 years) requiring NSAID therapy were prospectively randomized to: indomethacin (21 patients), naproxen (33 patients), diclofenac (40 patients), sulindac (42 patients), meloxicam (35 patients) and celecoxib (40 patients) for 8.5±2 days. BP was measured at the beginning and end of follow-up using a Kenz OS22 monitor. At the end of follow-up, 211 (88%) patients were still available for evaluation. A slight posttreatment decrease in MBP (-1.4±9.0 mm Hg, 95%CI: -2.7 to -0.2) was found. No significant differences in posttreatment changes in MBP were found among the distinct NSAIDs evaluated. Fifty-five patients (23%; 95% CI: 18-29) showed a posttreatment increase in MBP of>5 mm Hg. This increase was not associated with hypertension, old age, or any specific NSAID. We conclude that, overall, shortterm NSAID therapy does not seem to have a clinically significant effect on MAP. However, 23% of patients undergoing this therapy showed an increase in MBP that, if persistent, could lead to a higher risk of cardiovascular disease. Further research is needed to identify whether this outcome persists in long-term NSAID therapy.

Comparative cardiovascular safety of traditional nonsteroidal anti-inflammatory drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for their anti-inflammatory and analgesic effects. Unfortunately, these drugs are not without toxicity, namely on the gastric mucosa, but also on the cardiovascular system. In this context, the marketing of the coxibs, a new series of NSAIDs that selectively inhibit COX-2, resulted in a large debate around their cardiovascular safety, because they may increase the incidence of myocardial infarction and stroke. The recent suspension of a large, randomised, controlled trial comparing celecoxib, naproxen and placebo in Alzheimer patients (the ADAPT trial) because of an apparent elevated cardiovascular risk in the naproxen group revived the debate on the cardiovascular safety of these drugs, but this time with special emphasis on the effect of traditional nonselective NSAIDs (tNSAIDs). In this paper that reviews and discusses the cardiovascular safety profile of tNSAIDs, essentially naproxen and ibuprofen in view of the most recent experimental and clinical data, the authors note that the published data are quite discordant and one cannot conclude that there is clear evidence to support a cardiovascular hazard from the administration of naproxen or non-naproxen NSAIDs unless additional information is provided. In addition, the results of retrospective case-control studies have to be interpreted very carefully because of the risk of confounding factors that are not always taken into account when subjects were classified either as cases or controls. Thus, in the absence of clear cut data, physicians will have to use traditional NSAIDs (or coxibs) in patients with a high cardiovascular risk on the basis of their common sense rather than on evidence-based medicine. For these patients, one should not forget that an inadequate long-term control of cardiovascular risk factors such as a hypertension, dyslipidaemia, diabetes, smoking and weight excess is more deleterious in terms of cardiovascular mortality than the administration of NSAIDs itself.

Factors associated with uncontrolled hypertension in an affluent, elderly population

OBJECTIVE

To explore demographic, economic, and treatment-related associations with uncontrolled hypertension in a relatively affluent, community-dwelling population.

METHODS

Two home surveys of 655 and 432 subjects with a diagnosis of hypertension were completed in 1995 and 1999, respectively. Trained surveyors recorded medication history plus demographic and socioeconomic variables, as well as several measurements of blood pressure in the home. Uncontrolled hypertension was defined according to guidelines set forth by the Sixth Report of the Joint National Committee on prevention, detection, evaluation, and treatment of high blood pressure. Odds ratios for observing an elevated blood pressure given the patients' medication history, income, insurance coverage, demographic variables, and concomitant disease were estimated using multivariable logistic regression.

RESULTS

On both occasions, >60% of the study population had an average blood pressure that was above recommended levels. Diuretic therapy alone (1995 survey) or in combination with an angiotensin-converting enzyme inhibitor (1999 survey) decreased the odds ratio for uncontrolled hypertension by 39% (p = 0.027) and 62% (p = 0.005), respectively. Lack of prescription drug insurance and a history of arthritis had negative effects, increasing the odds ratio for uncontrolled hypertension by more than twofold (p < 0.05).

CONCLUSIONS

Uncontrolled hypertension occurs commonly among elderly patients notwithstanding a relatively high standard of living. The choice of medication, presence of concomitant disease, and availability of insurance may be important factors influencing blood pressure control.

Update of ACR guidelines for osteoarthritis: role of the coxibs

The American College of Rheumatology (ACR) recently provided an update to the guidelines published in 1995 on the management of osteoarthritis (OA) of the knee and hip. Members of the Ad Hoc Committee on OA Guidelines followed an evidence-based medicine approach to revise the guidelines by reviewing an extensive literature search of the Cochrane and Medline databases and published abstracts, and discussing evidence with expert rheumatologists. The goal of the guidelines is to provide recommendations to control patients' OA pain, improve function and health-related quality of life, and avoid therapeutic toxicity. As in the original guidelines, nonpharmacologic interventions involving patient education and physical measures are recommended following initial diagnosis of OA. The pharmacologic algorithm was updated to include currently available therapeutic agents. Acetaminophen remains first-line therapy because of its cost, efficacy, and safety profiles. Cyclooxygenase-2-selective inhibitors (coxibs) have been included as an alternative to nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) in patients at risk for upper gastrointestinal adverse events. Tramadol is an available alternative for patients who have a contraindication to coxibs or nonselective NSAIDs or for those who have not responded to previous oral therapy. Intra-articular injections or topical therapy may be used as monotherapy, or as an adjunct to oral analgesia. Surgical treatment of OA remains a last resort for patients who have failed to respond to nonpharmacologic and pharmacologic treatment approaches, and have progressive limitation in their activities of daily living. Several therapies for the prevention or treatment of OA are currently under investigation, including nutritional supplements, such as glucosamine and chondroitin, disease-modifying OA drugs, and devices, such as acupuncture and electromagnetic therapy. It is anticipated that the guidelines for the management of OA will continue to evolve as new therapies become available.

Renal effects of cyclooxygenase-2 selective inhibitors

Recent in-vitro and animal data show that cyclooxygenase-2 has an integral role in the physiology and pathophysiology of the kidney. Cyclooxygenase-2 regulates renin-angiotensin secretion, and thereby glomerular filtration rate and sodium homeostasis. It is also important for protecting against hypertonic stress. As a consequence, it is not surprising that clinical data verify that selective inhibitors of cyclooxygenase-2 affect renal function to a degree similar to that which has previously been documented with nonselective nonsteroidal anti-inflammatory drugs.

Characterization of murine vasopressor and vasodepressor prostaglandin E(2) receptors

Four E-prostanoid (EP) receptors, designated EP(1), EP(2), EP(3), and EP(4), mediate the cellular effects of prostaglandin E(2) (PGE(2)). The present studies pharmacologically characterize the vasopressor and vasodepressor EP receptors in wild-type mice (EP(2)(+/+) mice) and mice with targeted disruption of the EP(2) receptor (EP(2)(-/-) mice). Mean arterial pressure (MAP) was measured via a carotid artery catheter in anesthetized male mice. Intravenous infusion of PGE(2) decreased MAP in EP(2)(+/+) mice but increased MAP in EP(2)(-/-) mice. Infusion of EP(3)-selective agonists, including MB28767, SC46275, and sulprostone, increased MAP in both EP(2)(+/+) and EP(2)(-/-) mice. Pretreatment with SC46275 desensitized mice to the subsequent pressor effect of sulprostone, but the vasodepressor effect of PGE(2) in EP(2)(+/+) mice remained intact. Although PGE(2) alone increased MAP in EP(2)(-/-) mice, prior desensitization of the pressor effect with SC46275 allowed a residual vasodepressor effect of PGE(2) to be seen in the EP(2)(-/-) mice. An EP(4)-selective agonist (prostaglandin E(1)-OH) functioned also as a vasodepressor in both EP(2)(-/-) and EP(2)(+/+) mice. High levels of EP(3) receptor mRNA were detected in mouse aortas and rabbit preglomerular arterioles by nuclease protection, with lower expressions of EP(1), EP(2), and EP(4) mRNA. The findings suggest that combined vasodepressor effects of EP(2) and EP(4) receptors normally dominate, accounting for the depressor effects of PGE(2). In contrast, in EP(2)(-/-) mice, EP(4) receptor activity alone is insufficient to overcome the EP(3) vasopressor effect. These findings suggest that a balance between pressor and depressor PGE(2) receptors determines its net effect on arterial pressure and that these receptors may be important therapeutic targets.

Controlling isolated systolic hypertension. No time to be complacent

Isolated systolic hypertension (ISH) is the most common form of hypertension in the elderly. It is an even better predictor of morbidity and mortality than is diastolic blood pressure. Several large trials have documented a clear benefit to treating ISH. Therapy should be initiated only after careful evaluation of the patient's overall medical status, because the elderly are at increased risk of adverse effects from medications. Pharmacologic therapy should be started at a low dose and increased slowly, if necessary. If hypertension is still present after the addition of two or three medications, a cause other than essential hypertension should be considered, such as white coat hypertension, secondary hypertension, or pseudohypertension.