Small molecule selectin ligand inhibition improves outcome in ischemic acute renal failure.

BACKGROUND: The pathophysiologic and potential therapeutic role of selectins in renal ischemia-reperfusion injury (IRI) is not fully understood, due in part to redundancy in the roles of individual selectins. We hypothesized that blockade of ligands for all three selectins using a novel small molecule (TBC-1269) would improve the course of renal IRI by overcoming redundancy issues. This was investigated in a rat model of renal IRI. METHODS: Rats were treated with TBC-1269 either during or post-IRI. The effects of TBC-1269 were investigated in two models of renal IRI: moderate IRI (30 minutes bilateral renal artery clamping) and severe IRI (45 minutes clamping). The combination of anti-E- and anti-P-selectin antibodies also was investigated in rats subjected to moderate IRI. Renal function, histological injury and mortality were assessed. RESULTS: Rats treated with TBC-1269 during moderate IRI showed significantly reduced serum creatinine (SCr) and tubular necrosis post-ischemia compared to control animals. By contrast, delayed treatment (post-IRI) did not show a reduction in SCr. In rats with severe IRI, TBC-1269 treatment during IRI significantly reduced mortality at 48 hours post-ischemia. Rats with moderate IRI and treated with the combination of anti-E- and anti-P-selectin antibodies showed significantly reduced SCr compared to control rats at 24 hours post-ischemia. CONCLUSIONS: Small molecule selectin ligand inhibition provides a novel and effective approach to attenuate ischemic acute renal failure. Timing of treatment is crucial to success.

Metabolic pathogenesis of cardiorenal disease.

Clinical data have established microalbuminuria/proteinuria as an independent risk factor for the development and progression of renal disease in patients with either diabetes or essential hypertension. Decreased kidney function is associated with increased cardiovascular risk, even at modest reductions in estimated creatinine clearance (to approximately 60 mL/min/1.73 m(2)) or modest elevations in serum creatinine (>1.4 mg/dL). Treatment with angiotensin-converting enzyme inhibitors has been shown in clinical trials to delay or stabilize the rate of progression of renal disease. Reduction in cardiovascular events, such as stroke and myocardial infarction, also has been shown in these high-risk individuals. These effects are dependent and independent of blood pressure control, suggesting a nonhemodynamic effect in blockade of the renin-angiotensin system. In conjunction with other therapeutic interventions, such as dietary modification and control of serum lipids, it appears that for at least a subgroup of patients it is possible to delay or prevent progression of kidney failure. There frequently is a clustering of risk factors in these individuals, including insulin resistance, salt sensitivity, hypertension, and dyslipidemia. The mechanism of the relationship between albuminuria and cardiovascular disease is unclear but may be related to endothelial cell dysfunction. Nonetheless, the presence of microalbuminuria/proteinuria as a marker for cardiovascular disease has important implications for the identification and treatment of individuals at risk.

The urgent call of albuminuria/proteinuria. Heeding its significance in early detection of kidney disease.

Microalbuminuria, one of the earliest indicators of kidney injury, could be a harbinger of progressive kidney failure. Similarly, it can also be one of the early signs that a patient at risk for cardiovascular disease is in fact developing the disease. If so, the patient's therapy is failing. Discussion of specific appropriate interventions are beyond the scope of this article. However, publications referred to in this work have recently discussed such interventions in substantial practical detail. Ample evidence shows that factors that are kidney-protective are also cardiovascular-protective.

[Effect of losartan on renal and cardiovascular complications of patients with type 2 diabetes and nephropathy]. / Effekt af losartan på nyre- og kardiovaskulaere komplikationer hos patienter med type 2-diabetes og nefropati.

INTRODUCTION: Diabetic nephropathy is the leading cause of end-stage renal disease. Interruption of the renin-angiotensin system slows the progression of renal disease in type 1 diabetic patients, but similar data are not available for type 2, the most common form of diabetes. We assessed the role of the angiotensin II receptor antagonist, losartan, in type 2 diabetic patients with nephropathy. MATERIAL AND METHODS: One thousand five hundred and thirteen patients were enrolled in this randomised, placebo-controlled study of losartan (50 to 100 mg, once daily) or placebo, in addition to conventional antihypertensive treatment (calcium antagonists, diuretics, alpha- and beta-blockers, centrally acting agents) for a mean of 3.4 years. The primary outcome was the composite of doubling of baseline serum creatinine, end-stage renal disease, or death. Secondary end points included a composite of cardiovascular morbidity and mortality, proteinuria, and the progression rate of renal disease. RESULTS: Baseline demographics in the two groups were similar. Three hundred and twenty-seven patients receiving losartan reached the primary end point, as compared with 359 on placebo (risk reduction = 16 per cent, p = 0.02). Losartan reduced the incidence of doubling of serum creatinine (risk reduction = 25 per cent, p = 0.006) and end-stage renal disease (risk reduction = 28 per cent, p = 0.002), but had no effect on death. Benefits exceeded that attributable to changes in blood pressure. The composite of cardiovascular morbidity and mortality was similar in the two groups, except hospitalisation for heart failure, which was reduced with losartan (risk reduction = 32 per cent, p = 0.005). Proteinuria declined by 35 per cent with losartan (p < 0.001). DISCUSSION: Losartan conferred significant renal benefits in type 2 diabetic patients with nephropathy and was generally well tolerated.

The national epidemic of chronic kidney disease. What we know and what we can do.

The alarming increase in the incidence and mortality rate of end-stage renal disease (ESRD) over the past several years has prompted concerned physicians to ask why--and to ponder what can be done to ameliorate the situation. This article, the first in a seven-part series coordinated by the National Kidney Foundation, examines the factors surrounding the epidemic of chronic kidney disease and introduces readers to the organization's new clinical practice guidelines developed through its Kidney Disease Outcomes Quality Initiative. These recommendations emphasize early detection and treatment and offer a new avenue of communication between primary care physicians and nephrologists.

Effects of losartan on renal and cardiovascular outcomes in patients with type 2 diabetes and nephropathy.

BACKGROUND: Diabetic nephropathy is the leading cause of end-stage renal disease. Interruption of the renin-angiotensin system slows the progression of renal disease in patients with type 1 diabetes, but similar data are not available for patients with type 2, the most common form of diabetes. We assessed the role of the angiotensin-II-receptor antagonist losartan in patients with type 2 diabetes and nephropathy. METHODS: A total of 1513 patients were enrolled in this randomized, double-blind study comparing losartan (50 to 100 mg once daily) with placebo, both taken in addition to conventional antihypertensive treatment (calcium-channel antagonists, diuretics, alpha-blockers, beta-blockers, and centrally acting agents), for a mean of 3.4 years. The primary outcome was the composite of a doubling of the base-line serum creatinine concentration, end-stage renal disease, or death. Secondary end points included a composite of morbidity and mortality from cardiovascular causes, proteinuria, and the rate of progression of renal disease. RESULTS: A total of 327 patients in the losartan group reached the primary end point, as compared with 359 in the placebo group (risk reduction, 16 percent; P=0.02). Losartan reduced the incidence of a doubling of the serum creatinine concentration (risk reduction, 25 percent; P=0.006) and end-stage renal disease (risk reduction, 28 percent; P=0.002) but had no effect on the rate of death. The benefit exceeded that attributable to changes in blood pressure. The composite of morbidity and mortality from cardiovascular causes was similar in the two groups, although the rate of first hospitalization for heart failure was significantly lower with losartan (risk reduction, 32 percent; P=0.005). The level of proteinuria declined by 35 percent with losartan (P<0.001 for the comparison with placebo). CONCLUSIONS: Losartan conferred significant renal benefits in patients with type 2 diabetes and nephropathy, and it was generally well tolerated.

Proteinuria and cardiovascular disease.

In the last few decades, clinical and experimental data have established microalbuminuria/proteinuria as an independent risk factor for renal disease and for progression of renal disease in patients with diabetes and in those with essential hypertension. Reduction of proteinuria with the use of angiotensin-converting enzyme inhibitors has been shown in clinical trials to delay or stabilize the rate of progression of renal disease. This effect appears to be independent of any effect on blood pressure control. In conjunction with other therapeutic interventions such as dietary modification and control of serum lipids, it appears that for at least a subgroup of patients, it is possible to delay or prevent progression of kidney failure. More recently, evidence has accumulated that establishes microalbuminuria/proteinuria as an independent risk factor for cardiovascular morbidity and mortality even in those without other clinical evidence of kidney disease. There is frequently a clustering of risk factors in these individuals that includes insulin resistance, salt-sensitivity, hypertension, and dyslipidemia. The mechanism of this relationship of proteinuria and cardiovascular disease is unclear, but the presence of proteinuria as a marker for cardiovascular disease has important implications for the identification and treatment of individuals at risk.

A novel IL-18BP ELISA shows elevated serum IL-18BP in sepsis and extensive decrease of free IL-18.

IL-18 binding protein (IL-18BP) is a circulating antagonist of the proinflammatory Th1 cytokine IL-18. It effectively blocks IL-18 by forming a 1:1 high affinity (Kd=400 pM) complex, exhibiting a very low dissociation rate. We have developed a sandwich ELISA for IL-18BPa and determined its limit of detection (62 pg/ml). Interference by IL-18 and related cytokines, as well as cross reactivity with other IL-18BP isoforms (b, c, and d) were determined. Using this ELISA, we measured serum IL-18BPa in large cohorts of healthy individuals and in septic patients. Serum IL-18BPa in healthy individuals was 2.15+/-0.15 ng/ml (range 0.5-7 ng/ml). In sepsis, the level rose to 21.9+/-1.44 ng/ml (range 4-132 ng/ml). Total IL-18 was measured in the same sera by an electrochemiluminescence assay and free IL-18 was calculated based on the mass action law. Total IL-18 was low in healthy individuals (64+/-17 pg/ml) and most of it ( approximately 85%) was in its free form. Total IL-18 and IL-18BPa were both elevated in sepsis patients upon admission (1.5+/-0.4 ng/ml and 28.6+/-4.5 ng/ml, respectively). At these levels, most of the IL-18 is bound to IL-18BPa, however the remaining free IL-18 is still higher than in healthy individuals. We conclude that IL-18BPa considerably inhibits circulating IL-18 in sepsis. Yet, exogenous administration of IL-18BPa may further reduce circulating IL-18 activity.

The CHORUS (Cerivastatin in Heart Outcomes in Renal Disease: Understanding Survival) protocol: a double-blind, placebo-controlled trial in patients with esrd.

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin)-mediated lowering of serum cholesterol has been associated with a significant reduction in cardiovascular morbidity and mortality. Recent studies suggest that additional non-lipid lowering effects (eg, endothelial stabilization, anti-inflammatory, antithrombogenic) may be important in modulating their effectiveness. Dyslipidemia is common in end-stage renal disease (ESRD), and hemodialysis patients have increased cardiovascular morbidity and mortality. Cerivastatin, a new statin with powerful low-density lipoprotein-cholesterol (LDL-C) lowering capabilities, possesses some unique non-LDL-C-mediated properties that may contribute to a reduction of coronary events in the patient with ESRD. The primary objective of this multicenter multinational study of 1,054 hemodialysis patients is to compare 2 years of treatment with cerivastatin (0.4 mg/d) versus placebo on the composite clinical event rate of myocardial infarction, sudden cardiac death, ischemic stroke, and the need for coronary arterial bypass graft (CABG) or percutaneous transluminal coronary angioplasty (PTCA) procedures in these patients. Changes in lipids, inflammatory proteins including heat stable C-reactive protein (hsCRP), interleukin-6 (IL-6), oncostatin-M, intracellular adhesion molecule-1 (ICAM-1) and monocyte-chemoattractant protein-1 (MCP-1), as well as markers of cardiac muscle pathology, such as troponin I and troponin T, will be assessed in a subset of patients. This study is the first of its kind to assess the effect of a statin on the reduction of cardiovascular morbidity and mortality in an incident hemodialysis population. It will determine whether treatment with cerivastatin can effectively reduce the significant cardiovascular morbidity and mortality.

Recombinant erythropoietin rapidly treats anemia in ischemic acute renal failure.

BACKGROUND: The anemia associated with acute renal failure (ARF) is currently treated with blood transfusions, while the anemia of chronic renal failure is treated with recombinant erythropoietin (EPO). We hypothesized that EPO treatment during ARF could rapidly improve hemoglobin levels and be a useful therapeutic approach. In addition, as tubular epithelial cells have EPO receptors that can mediate proliferation, enhanced recovery of renal function may occur with EPO use. METHODS: An established rat model of ischemic ARF was studied, using either moderate or severe ischemia. EPO was administered in a dose of 500 or 3000 U/kg starting at time of ischemia. Hematocrit (Hct), serum creatinine, reticulocyte count, and mortality rate were measured. RESULTS: EPO treatment led to a rapid and significant increase in Hct at 48 and 72 hours after moderate ischemic renal reperfusion injury (IRI) in EPO (500 U/kg)-treated rats compared with control (saline treated) rats (mean +/- SE; 45.6 +/- 0.3% vs. 42.0 +/- 1.0%, P < 0.01) and (46.6 +/- 0.3 vs. 41.0 +/- 1.0, P < 0.01, N = 3 per group). In severe renal IRI, EPO treatment also led to significantly increased Hct at 48 (40.0 +/- 4.4% vs. 36.8 +/- 0.3%, P < 0.01, N = 3 per group) and 72 hours (43.5 +/- 1.5% vs. 34.7 +/- 2.3%, P < 0.01, N = 3 per group). Higher dose (3000 U/kg) EPO led to a more pronounced Hct increase after severe IRI at 48 hours compared with the 500 U/kg dose (43.5 +/- 0.3 vs. 40.3 +/- 0.3, P < 0.01, N = 3 per group). EPO treatment during moderate or severe renal IRI did not change the course of the renal dysfunction. EPO treatment (N = 19) had a significant protective effect on mortality during severe IRI. In addition, loss of body weight during ARF was not affected by EPO therapy. CONCLUSIONS: Recombinant EPO can rapidly increase Hct and improve mortality during ARF. Human studies are warranted to evaluate the clinical applicability of this important finding.

Pharmacokinetics and blood pressure response of losartan in end-stage renal disease.

BACKGROUND: Losartan is a selective angiotensin AT1 receptor antagonist currently employed in the management of essential hypertension. This compound is in common use in populations with renal failure and end-stage renal disease (ESRD). OBJECTIVE: To investigate the pharmacokinetics and pharmacodynamics of losartan in patients with ESRD in order to establish administration guidelines. METHODS: Patients were administered losartan 100 mg/day for 7 days, and after the seventh and final dose pharmacokinetic parameters were determined for both losartan and its active metabolite E-3174. During the study, the haemodialytic clearances of losartan and E-3174 were measured during a standard 4-hour dialysis session. Neurohumoral and biochemical changes were assessed during losartan administration. RESULTS: The pharmacokinetics of losartan and E-3174 in haemodialysis patients did not alter to a clinically significant level. Losartan administration was accompanied by a decline in plasma aldosterone level as well as by an increase in plasma renin activity. Losartan administration resulted in a decline in plasma uric acid level, despite the fact that the study participants had no residual renal function. Losartan and E-3174 were not dialysable. CONCLUSIONS: The pharmacokinetics of losartan and E-3174 are minimally altered in ESRD; thus, dosage adjustment is not required in the presence of advanced dialysis-dependent renal failure. In addition, postdialysis supplementation is not required for losartan because of the negligible dialysability of losartan and E-3174.

The role of lipids in renal disease: future challenges.

Experimental studies have provided in vivo and in vitro data to support the notion that dyslipidemia contributes to glomerular and interstitial injury of the renal parenchyma. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are a new class of lipid-lowering agents that have been extensively studied during the past decade. These agents have significant effects on circulating lipids and both renal and vascular injury. New insights into the mechanisms of action of these agents have revealed an important effect on a variety of inflammatory and fibrogenic processes that appear to have major implications for human renal and cardiovascular diseases.

Proteinuria: its clinical importance and role in progressive renal disease.

In patients with essential hypertension and in those with diabetes mellitus, the presence of increased amounts of urinary protein or albumin has been shown to be an important and independent risk for an increased incidence of cardiovascular morbidity and mortality. A constellation of cardiovascular risk factors has been described in these individuals, as well as evidence for diffuse endothelial cell dysfunction, which suggests these individuals are particularly susceptible to the development of extensive vascular disease. Recent studies have also suggested that proteinuria is not only a marker for renal disease but it also predicts those patients at greatest risk for the development of chronic and progressive renal insufficiency. This effect of proteinuria was evident in patients in whom urinary protein excretion rates exceeded 1 g/24 hours, but probably is true even in patients with smaller amounts of proteinuria. This effect of proteinuria on progression of renal disease is independent of other risk factors such as level of renal function, blood pressure, and dyslipidemia. Recent clinical studies have demonstrated that modification of proteinuria by the use of angiotensin-converting enzyme (ACE) inhibitors independent of reductions in systemic blood pressure results in slowing of the rate of loss of renal function and even stabilization of renal function over longer periods of treatment. In patients with renal disease, the totality of evidence suggests that multiple pharmacological and dietary modifications will be necessary to achieve the optimal slowing of the progression of renal disease. In addition, strategies will be required to reduce risks involved in the development of cardiovascular disease to ensure optimal patient survival. The similarity of risk factors involved in cardio-renal disease progression should allow us to achieve this goal with our current therapeutic armamentarium.

Diabetes in the elderly population.

Type 2 diabetes mellitus has emerged as an important condition of older patients in which both microvascular and macrovascular complications are a common cause of morbidity and mortality. In contrast to type 1 diabetes mellitus, this endocrinopathy is clustered in minority populations and has both strong genetic and environmental factors that influence disease manifestation. A number of physiological alterations of glucose metabolism including hepatic overproduction of glucose, and reduced glucose utilization by peripheral tissues as a result of insulin resistance contribute to the development of the metabolic manifestations of this disease. Ultimately, pancreatic failure and reduced insulin secretion lead to hyperglycemia and the diabetic state. Frequently, many of these metabolic manifestations, or what has been termed Syndrome X, antecede the development of overt diabetes by many years. This syndrome is manifest clinically by such cardiovascular risk factors as hypertension, dyslipidemia, and coagulation abnormalities. This abnormal metabolic milieu contributes to the high prevalence of macrovascular complications including coronary artery disease as well as more generalized atherosclerosis. Microvascular complications have only more recently been recognized as an important and frequent complication of type 2 diabetes. Among the elderly and minority populations, this has become the single most important cause of end-stage renal failure that necessitates renal replacement therapies. The outcome for these patients on hemodialysis, the modality most frequently selected, is poor, with the majority of these patients dying of cardiovascular causes. Unfortunately, interventional strategies to reduce or prevent the microvascular and macrovascular complications have only recently received the needed attention and will require considerable effort and resources to improve the clinical outcomes and life expectancies for these patients.

Low-density lipoprotein-induced expression of interleukin-6, a marker of human mesangial cell inflammation: effects of oxidation and modulation by lovastatin.

Low-density lipoprotein (LDL) may contribute to the pathogenesis of glomerulosclerosis by stimulating a mesangial cell inflammatory response. Interleukin-6 (IL-6) is a marker of active inflammation and ongoing glomerular injury. Therefore, we investigated the effects of native and oxidized LDL on human mesangial cell production of IL-6 and a possible modulation of this inflammatory response by lovastatin, which has been shown to ameliorate experimental glomerulosclerosis. Human mesangial cells were exposed for 6 or 24 h to culture medium containing either native LDL alone or a LDL mixture containing 5 or 20% oxidized LDL. We found that native LDL stimulated 6 h mRNA expression and secretion of IL-6. This effect was further enhanced, in a dose-related manner, when mesangial cells were exposed to increasing concentrations of oxidized LDL. Lovastatin markedly inhibited mesangial cell expression of IL-6 mRNA and reduced IL-6 secretion. The inhibitory effects of lovastatin were overridden at least partially by exogenous mevalonate. We conclude that LDL, and particularly oxidized LDL, might contribute to the pathogenesis of glomerular disease by modulating the inflammatory response of human mesangial cells, as assessed by the stimulation of IL-6 expression. Moreover, this inflammatory response can be prevented by lovastatin, providing a potential direct anti-inflammatory mechanism by which HMG-CoA reductase inhibitors may attenuate lipid-induced glomerular injury.

The losartan renal protection study--rationale, study design and baseline characteristics of RENAAL (Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan).

The RENAAL Study is a double-blind, placebo-controlled trial to evaluate the renal protective effects of losartan in Type 2 diabetic patients with nephropathy. The study has enrolled 1513 patients and is expected to continue for 3.5 years after the last patient has been entered. Eligible patients must have a urinary albumin:creatinine ratio of at least 300 mg/g and serum creatinine between 1.3 to 3.0 mg/dL. Eligible hypertensive or normotensive patients are randomised to receive either losartan or placebo, in addition to their existing antihypertensive therapy. Medications that block angiotensin production or action, are excluded. The primary endpoint is a composite of the time to first event of doubling of serum creatinine, end-stage renal disease, or death; secondary endpoints include cardiovascular events, progression of renal disease, and changes in proteinuria; tertiary endpoints include quality of life, healthcare resource utilisation, and amputations. Patients include Caucasians (48.6%), Blacks (15.2%), Asians (16.7%), and Hispanics (18.2%). Baseline urinary albumin:creatinine ratio and serum creatinine levels average 1867 mg/g and 1.9 mg/dL, respectively. Mean systolic and diastolic blood pressures are 153 and 82 mmHg, respectively. RENAAL will document whether blockade of the AII receptor with losartan produces clinical benefits in patients with Type 2 diabetes and nephropathy.

Rabeprazole: pharmacokinetics and tolerability in patients with stable, end-stage renal failure.

The authors compare the pharmacokinetic profiles, safety, and tolerability of rabeprazole, a new proton pump inhibitor (PPI), in healthy volunteers and in subjects with stable, end-stage renal failure. This single-center, open-label trial included two groups of subjects: 10 healthy males with 24-hour creatinine clearance > or = 90 mL/min/m2 and 10 males with renal failure (24-hour creatinine clearance < or = 5 mL/min/m2) receiving hemodialytic therapy. Normal subjects received a single, oral 20 mg rabeprazole dose. Those with renal failure received a 20 mg dose of rabeprazole on the day after hemodialysis and a second dose after a 2-week washout period during dialysis. Blood samples were drawn before and up to 24 hours after rabeprazole administration for determination of plasma rabeprazole concentrations by high-performance liquid chromatography. Safety and tolerability of rabeprazole were determined by reporting adverse events and comparing vital signs, ECG, physical examinations, and clinical laboratory tests before and during treatment. Comparison of pharmacokinetic results from healthy volunteers with those from subjects with renal failure indicated no clinically significant differences between groups. In addition, there were no statistically significant differences between any pharmacokinetic parameters recorded during or after hemodialysis. Rabeprazole was well tolerated by both groups. Only two drug-related adverse events were reported, and there were no significant treatment-emergent changes in vital signs or ECG. Treatment-emergent changes in hematologic and clinical chemistry parameters were observed for a few subjects in each group and generally represented only slight deviations from the normal range. These results indicate that no dosage adjustment of rabeprazole is required in patients with renal dysfunction. These findings and the well-documented clinical efficacy of this new PPI in patients with gastric ulcers, duodenal ulcers, or gastroesophageal reflux disease support rabeprazole's use in the treatment of patients with acid peptic disorders.