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Biomedical subjects

Mark E Cooper

Publications and source records attributed to Mark E Cooper.

At least 55 records · Page 3Linked to original sources
PubMed2005

High glucose-induced impairment in insulin secretion is associated with reduction in islet glucokinase in a mouse model of susceptibility to islet dysfunction.

Type 2 diabetes is characterized by islet dysfunction resulting in hyperglycemia, which can then lead to further deterioration in islet function. A possible mechanism for hyperglycemia-induced islet dysfunction is the accumulation of advanced glycation end products (AGE). The DBA/2 mouse develops pancreatic islet dysfunction when exposed to a high glucose environment and/or obesity-induced insulin resistance. To determine the biochemical cause of dysfunction, DBA/2 and C57BL/6 control islets were incubated in 11.1 mM or 40 mM glucose in the absence or presence of the AGE inhibitor aminoguanidine (AG) for 10 days. Basal (2.8 mM glucose) insulin release was increased in both DBA/2 and C57BL/6 islets incubated with 40 mM vs 11.1 mM glucose for 10 days. Chronic exposure to hyperglycemia decreased glucose (20 mM)-stimulated insulin secretion in DBA/2 but not in C57BL/6 islets. AG significantly increased fold-induced insulin release in high glucose cultured DBA/2 mouse islets, but did not affect C57BL/6 islet function. DBA/2 islet glucokinase was significantly reduced following 40 mM glucose culture, compared with 11.1 mM glucose cultured DBA/2 islets and 40 mM glucose cultured C57BL/6 islets. Incubation of islets with AG resulted in a normalization of DBA/2 islet glucokinase levels. In conclusion, chronic high glucose-induced increases in AGE can result in islet dysfunction and this is associated with reduced glucokinase levels in a mouse model with susceptibility to islet failure.

Animals↗
PubMed2004

Imatinib attenuates diabetic nephropathy in apolipoprotein E-knockout mice.

In the diabetic kidney, clinical as well as experimental observations have shown an upregulation of growth factors such as PDGF. These studies, however, were not designed to address whether upregulation of PDGF is merely a manifestation of diabetic renal injury or whether PDGF plays an active role in the pathophysiology of diabetic nephropathy. The objectives of this study were first to assess whether PDGF-dependent pathways are involved in the development of diabetic nephropathy and second to determine the effects of PDGF receptor antagonism on this disorder and associated molecular and cellular processes. This study used the diabetic apolipoprotein E-knockout (apoE-KO) mouse, a recently described model of accelerated diabetic nephropathy. Diabetes was induced by injection of streptozotocin in 6-wk-old apoE-KO mice. Diabetic animals received treatment with a tyrosine kinase inhibitor that inhibits PDGF action, imatinib (STI-571, 10 mg/kg per d orally) or no treatment for 20 wk. Nondiabetic apoE-KO mice served as controls. This model of accelerated renal disease with albuminuria as well as glomerular and tubulointerstitial injury was associated with increased renal expression of PDGF-B, proliferating cells, and alpha-smooth muscle actin-positive cells. Furthermore, there was increased accumulation of type I and type IV collagen as well as macrophage infiltration. Imatinib treatment ameliorated both renal functional and structural parameters of diabetes as well as overexpression of a number of growth factors, collagens, proliferating cells, alpha-smooth muscle actin-positive cells, and macrophage infiltration within the kidney. Tyrosine kinase inhibition with imatinib seems to retard the development of experimental diabetic nephropathy.

Animals↗
PubMed2004

Albuminuria, a therapeutic target for cardiovascular protection in type 2 diabetic patients with nephropathy.

BACKGROUND: Albuminuria is an established risk marker for both cardiovascular and renal outcomes. Albuminuria can be reduced with drugs that block the renin-angiotensin system (RAS). We questioned whether the short-term drug-induced change in albuminuria would predict the long-term cardioprotective efficacy of RAS intervention. METHODS AND RESULTS: We analyzed data from Reduction in Endpoints in Non-insulin dependent diabetes mellitus with the Angiotensin II Antagonist Losartan (RENAAL), a double-blind, randomized trial in 1513 type 2 diabetic patients with nephropathy, focusing on the relationship between the prespecified cardiovascular end point (composite) or hospitalization for heart failure and baseline or reduction in albuminuria. Patients with high baseline albuminuria (> or =3 g/g creatinine) had a 1.92-fold (95% CI, 1.54 to 2.38) higher risk for the cardiovascular end point and a 2.70-fold (95% CI, 1.94 to 3.75) higher risk for heart failure compared with patients with low albuminuria (<1.5 g/g). Among all available baseline risk markers, albuminuria was the strongest predictor of cardiovascular outcome. The association between albuminuria and cardiovascular outcome was driven by those patients who also had a renal event. Modeling of the initial 6-month change in risk parameters showed that albuminuria reduction was the only predictor for cardiovascular outcome: 18% reduction in cardiovascular risk for every 50% reduction in albuminuria and a 27% reduction in heart failure risk for every 50% reduction in albuminuria. CONCLUSIONS: Albuminuria is an important factor predicting cardiovascular risk in patients with type 2 diabetic nephropathy. Reducing albuminuria in the first 6 months appears to afford cardiovascular protection in these patients.

Aged↗
PubMed2004

The role of advanced glycation in reduced organic cation transport associated with experimental diabetes.

Tubular dysfunction is an important early manifestation of diabetic nephropathy. Reduced renal expression of organic cation transporters (OCTs) potentially contributes to impaired cation clearance in diabetes. This study examines the role of advanced glycation end-products (AGEs) in mediating these changes. Experimental diabetes was induced with streptozotocin (55 mg/kg). Rats were randomly treated with the AGE inhibitor aminoguanidine for 32 weeks. In a second protocol, diabetic rats were followed with and without low-dose insulin therapy (2 U/day) for 4 weeks. Expression of OCTs was determined by real-time RT-PCR (reverse transcription-polymerase chain reaction) and Western blotting. As a marker of cation transport, the fractional clearance of endogenous N-methylnicotinamide (NMN) was determined by high-performance liquid chromatography. Both short- and long-term diabetes was associated with reduced gene and protein expression of the three renal OCT isotypes. This was associated with a reduction in the fractional clearance of NMN compared with control animals by over 50%. These changes correlated with the accumulation of renal and plasma AGEs. Treatment with the AGE inhibitor aminoguanidine restored the expression of OCT-2 and OCT-3 in diabetic animals and normalized renal NMN clearance. NMN clearance was also improved in diabetic animals receiving low-dose insulin, correlating with a reduction in AGEs and improvement in effective renal plasma flow. These studies demonstrate an early impairment of expression of OCTs and cation clearance associated with diabetes. These changes correlate with the accumulation of AGEs and may be partly attenuated by an AGE inhibitor, implicating a role for AGEs in organic cation transport.

Animals↗
PubMed2004

Irbesartan but not amlodipine suppresses diabetes-associated atherosclerosis.

BACKGROUND: It remains controversial whether specific blockade of the renin-angiotensin system confers superior antiatherosclerotic effects over other antihypertensive agents in diabetes. Therefore, the aim of this study was to compare equihypotensive doses of the angiotensin II subtype 1 (AT1) receptor blocker irbesartan with the calcium antagonist amlodipine on diabetes-induced plaque formation in the apolipoprotein E (apoE)-null mouse and to explore molecular and cellular mechanisms linked to vascular protection. METHODS AND RESULTS: Diabetes was induced by injection of streptozotocin in 6-week-old apoE-null mice. Diabetic animals were randomized to no treatment, irbesartan, or amlodipine for 20 weeks. Diabetes was associated with an increase in plaque area and complexity in the aorta in association with a significant increase in aortic AT1 receptor expression, cellular proliferation, collagen content, macrophage- and alpha-smooth muscle actin-positive cell infiltration, as well as an increased expression of platelet-derived growth factor-B (PDGF-B), monocyte chemoattractant protein-1 (MCP-1), and vascular cell adhesion molecule-1 (VCAM-1). Irbesartan but not amlodipine treatment attenuated the development of atherosclerosis, collagen content, cellular proliferation, and macrophage infiltration as well as diabetes-induced AT1 receptor, PDGF-B, MCP-1, and VCAM-1 overexpression in the aorta despite similar blood pressure reductions by both treatments. CONCLUSIONS: Diabetes-associated atherosclerosis is ameliorated by AT1 receptor blockade but not by calcium channel antagonism, providing further evidence for the vascular renin-angiotensin system playing a pivotal role in the development and acceleration of atherosclerosis in diabetes.

Amlodipine↗
PubMed2004

Imatinib attenuates diabetes-associated atherosclerosis.

OBJECTIVE: Diabetes is associated with accelerated atherosclerosis, the major factor contributing to increased mortality and morbidity in the diabetic population. The molecular mechanisms by which diabetes promotes atherosclerosis are not fully understood. Platelet-derived growth factor has been shown to play a major role in the pathology of vascular diseases, but whether it plays a role in atherosclerosis associated with diabetes remains unknown. The aims of this study were to assess whether platelet-derived growth factor-dependent pathways are involved in the development of diabetes-induced atherosclerosis and to determine the effects of platelet-derived growth factor receptor antagonism on this disorder. METHODS AND RESULTS: Diabetes was induced by injection of streptozotocin in 6-week-old apolipoprotein E knockout mice. Diabetic animals received treatment with a tyrosine kinase inhibitor that inhibits platelet-derived growth factor action, imatinib (STI-571, 10 mg/kg per day), or no treatment for 20 weeks. Nondiabetic apolipoprotein E knockout mice served as controls. Induction of diabetes was associated with a 5-fold increase in plaque area in association with an increase in aortic platelet-derived growth factor-B expression and platelet-derived growth factor-beta receptor phosphorylation as well as other prosclerotic and proinflammatory cytokines. Imatinib treatment prevented the development of atherosclerotic lesions and diabetes-induced inflammatory cytokine overexpression in the aorta. CONCLUSIONS: Tyrosine kinase inhibition with imatinib appears to be a novel therapeutic option to retard the development of atherosclerosis, specifically in the context of diabetes.

Animals↗
PubMed2004

Novel hexad repeats conserved in a putative transporter with restricted expression in cell types associated with growth, calcium exchange and homeostasis.

A transport protein is described with 12 transmembrane spans. Within the cytoplasmic amino-terminal domain, several novel hexad repeats are conserved in human, mouse, rat and pig, four to six of which had the canonical form PS_S_H(+). In the carboxyl-terminal domain, a polyglutamate sequence (5-8) is conserved. Restricted expression of the transporter was identified in acidophil cells of the adult pituitary that secrete growth hormone and prolactin. In the fetus, expression was restricted to osteoclasts, chondrocytes, thyroid, pituitary, central nervous system, eye, liver and heart. In particular, expression was found in structures associated with rapid calcium exchange including the retina, cardiomyocytes and in the intraplacental yolk sac that expresses calcitropic molecules. Furthermore, expression found in osteoclasts and kidney, within the distal portions of nephrons and collecting ducts, was consistent with a role in calcium homeostasis. In human pituitary, four mRNA transcripts, and in mouse kidney, three mRNA transcripts were expressed. In developing mouse kidney, the amount of each transcript varied that suggested the multiple transcripts might be differentially expressed in different physiological states. We propose that the transporter is specific for a calcium-chelator complex and is important for growth and calcium metabolism.

Amino Acid Sequence↗
PubMed2004

Retinal expression of vascular endothelial growth factor is mediated by angiotensin type 1 and type 2 receptors.

Angiotensin II is a known stimulus for the expression of vascular endothelial growth factor (VEGF). This action of angiotensin II is mediated by the angiotensin type 1 (AT1) receptor. However, the role of the angiotensin type 2 (AT2) receptor subtype in inducing VEGF expression has been controversial. The aim of the present study was to assess the effects of AT2 receptor blockade on VEGF expression in the retina, initially in experimental diabetic rats induced by injection of streptozotocin. The AT1 receptor antagonist, valsartan, or the AT2 receptor antagonists, PD123319, were administered to diabetic rats for 4 weeks. Increased gene and protein expressions of VEGF, as assessed by real-time reverse transcription-polymerase chain reaction and immunostaining, respectively, were observed in the retina in diabetic rats. Treatment with either valsartan or PD123319 attenuated retinal VEGF expression. To further explore the link between angiotensin receptor subtypes and VEGF expression, valsartan, or PD123319 were administered to rats that were infused with angiotensin II for 2 weeks. VEGF expression was also increased in the retina from angiotensin II infused rats, and this was attenuated by valsartan and PD123319. These findings suggest that VEGF expression is modulated by AT1 and AT2 receptors, thereby implicating angiotensin II receptor subtypes in retinal diseases such as diabetic retinopathy.

Angiotensin II↗
PubMed2004

Use of genetic mouse models in the study of diabetic nephropathy.

The study of experimental diabetic nephropathy in rodent models has led to many changes in the clinical management of human diabetic nephropathy. With the development of technology to generate knockout and transgenic animals, the mouse has become a favored species in medical research. There are several genetic mouse models of diabetes, with the majority being models of type 2 diabetes mellitus. These include the hypoinsulinemic non-obese diabetic mouse, the Kkay mouse, the New Zealand obese mouse, the hyperinsulinemic ob/ob mouse, and the different strains of obese hyperinsulinemic db/db mouse. Each of these models displays some renal changes, but by far the best model of renal disease and the one that is the most studied is the db/db mouse. The db/db mouse displays substantial glomerular pathology, including mesangial matrix expansion and modest albuminuria. It has been reported that the db/db mouse has a decline in creatinine clearance after 5 months of age, but more specific approaches are warranted to confirm these findings. A number of intervention studies show renoprotection in this model. Although mice have many advantages, such as being able to be cross-bred with genetically manipulated animals, in many ways they are not very similar to humans, and in some respects the rat may be a better choice, particularly in relation to some features of end-organ injury.

Animals↗
PubMed2004

Use of genetic mouse models in the study of diabetic nephropathy.

The study of experimental diabetic nephropathy in rodent models has led to many changes in the clinical management of human diabetic nephropathy. With the development of technology to generate knockout and transgenic animals, the mouse has become a favored species in medical research. There are several genetic mouse models of diabetes, with the majority being models of type 2 diabetes mellitus. These include the hypoinsulinemic nonobese diabetic mouse, the KKAy mouse, the New Zealand obese mouse, the hyperinsulinemic ob/ob mouse, and the different strains of obese hyperinsulinemic db/db mouse. Each of these models displays some renal changes, but by far the best model of renal disease and the one that is the most studied is the db/db mouse. The db/db mouse displays substantial glomerular pathology, including mesangial matrix expansion and modest albuminuria. It has been reported that the db/db mouse has a decline in creatinine clearance after 5 months of age, but more specific approaches are warranted to confirm these findings. A number of intervention studies show renoprotection in this model. Although mice have many advantages, such as being able to be crossbred with genetically manipulated animals, in many ways they are not very similar to humans, and in some respects the rat may be a better choice, particularly in relation to some features of end-organ injury.

Animals↗
PubMed2004

Antiproteinuric effect of RAS blockade: new mechanisms.

Experimental and clinical studies have shown that blockade of the renin-angiotensin system (RAS) is effective in reducing proteinuria in conditions such as diabetes by reducing systemic and intraglomerular hydrostatic pressure. However, increasing evidence suggests that nonhemodynamic effects, such as preservation of the podocyte slit diaphragm structure and function, may also mediate the antiproteinuric effects of RAS blockade. In this review, we analyze in detail the evidence for known and novel mechanisms considered to play important roles in mediating the antiproteinuric effect of RAS blockers, with a particular focus on diabetic nephropathy.

Albuminuria↗
PubMed2004

The role of the renin-angiotensin-aldosterone system in diabetes and its vascular complications.

Clinical trials have demonstrated the benefit of blood pressure (BP) reduction in reducing the risk of cardiovascular and renal complications in patients with diabetes mellitus. Incorporation of agents that inhibit the renin-angiotensin-aldosterone system (RAAS) into antihypertensive regimens has been shown to provide reductions in renal and cardiovascular events that are mediated by both BP-dependent and -independent mechanisms. Recent studies exploring these potential mechanisms have demonstrated a direct role of angiotensin II (ATII) in the pathology of the vasculature and other sites of end-organ injury. In animal models of diabetes, inhibition of the RAAS with angiotensin-converting enzyme (ACE) inhibition or angiotensin type 1 (AT(1)) receptor blockade has been shown to prevent atherosclerosis, an effect that was independent of BP reduction. In addition to its direct effects on the vasculature, ATII also has direct detrimental effects on end organs, including the kidney and the heart, which lead to the development of proteinuria and left ventricular hypertrophy (LVH), respectively. Left ventricular hypertrophy has been shown to be predictive of cardiovascular and renal events, and the benefits of RAAS inhibition with angiotensin receptor blocker therapy are accompanied by a reduction in LVH. In addition to preventing the cardiovascular and renal complications of diabetes, the RAAS blockade has also been shown, in several large randomized clinical trials, to inhibit new onset of diabetes. Recent studies have revealed that many tissues, including pancreatic islets and adipose tissue, have a local RAAS. In the diabetic rat model (Zucker diabetic fatty rats), pancreatic islets exhibit an increased intraislet expression of ACE and AT(1) as well as increased intraislet fibrosis, apoptosis, and oxidative stress. The local RAAS also appears to play a role in the function of the adipocyte. Angiotensin II inhibits adipocyte differentiation, potentially decreasing the storage capacity of adipose tissue. The reduced capacity of adipose tissue to store fatty acids may cause their accumulation in other tissues, leading to insulin resistance and development of diabetes. Collectively, these studies demonstrate that ATII has direct effects on multiple tissues, and inhibition of ATII action in these tissues may be responsible for many of the clinical benefits observed with RAAS inhibition.

Diabetic Angiopathies↗
PubMed2004

Importance of advanced glycation end products in diabetes-associated cardiovascular and renal disease.

Although the features of diabetic cardiomyopathy, atherosclerosis, and nephropathy have been clinically characterized, the pathogenesis and the mechanisms underlying the abnormalities in the diabetic heart and kidney are not fully understood. During the past several years, in an attempt to discover interventions for diabetes-related complications, researchers have refocused their attention from the hemodynamic aspects of the disease to the biochemical interactions of glucose and proteins. Diabetes is a disorder of chronic hyperglycemia, and glucose participates in diabetic complications such as atherosclerosis, cardiac dysfunction, and nephropathy. Chronic hyperglycemia accelerates the reaction between glucose and proteins and leads to the formation of advanced glycation end products (AGE), which form irreversible cross-links with many macromolecules such as collagen. In diabetes, these AGE accumulate in tissues at an accelerated rate. The development of the novel compound dimethyl-3-phenacylthiazolium chloride (alagebrium chloride), which chemically breaks AGE cross-links, led to several preclinical animal studies that showed an attenuation or reversal of disease processes of the heart and kidney. In diabetes, AGE not only structurally stiffen structural collagen backbones but also act as agonists to AGE receptors (RAGE) on various cell types, which stimulate the release of profibrotic growth factors, promote collagen deposition, increase inflammation, and ultimately lead to tissue fibrosis. In the heart, large vessels, and kidney, these reactions produce diastolic dysfunction, atherosclerosis, and renal fibrosis. Administration of the cross-link breaker alagebrium chloride in these diabetic animals attenuates these pathologic phenomena, restoring functionality to the heart, vasculature, and kidney.

Animals↗
PubMed2004

Advanced glycation end products induce tubular epithelial-myofibroblast transition through the RAGE-ERK1/2 MAP kinase signaling pathway.

Advanced glycation end products (AGEs) have been shown to play a role in tubular epithelial-myofibroblast transdifferentiation (TEMT) in diabetic nephropathy, but the intracellular signaling pathway remains unknown. We report here that AGEs signal through the receptor for AGEs (RAGE) to induce TEMT, as determined by de novo expression of a mesenchymal marker (alpha-smooth muscle actin, alpha-SMA) and loss of epithelial marker (E-cadherin), directly through the MEK1-ERK1/2 MAP kinase pathway, which is TGF-beta independent. This is supported by the following findings: AGEs induced de novo alpha-SMA mRNA expression as early as 2 hours followed by a loss of E-cadherin before TGF-beta mRNA expression at 24 hours and occurred in the absence of TGF-beta and AGE-induced activation of ERK1/2 MAP kinase at 15 minutes and TEMT at 24 hours were completely blocked by a neutralizing RAGE antibody, a soluble RAGE receptor, an ERK1/2 MAP kinase inhibitor (PD98059), and DN-MEK1, but not by a neutralizing TGF-beta antibody. Thus, this study demonstrates that AGEs activate the RAGE-ERK1/2 MAP kinase pathway to mediate the early TEMT process. The findings from this study suggest that targeting the RAGE or the ERK MAP kinase pathway may provide new therapeutic strategies for diabetic nephropathy and shed new light on the pathogenesis of diabetic nephropathy.

Actins↗
PubMed2004

Cardiorenal protective effects of vasopeptidase inhibition with omapatrilat in hypertensive transgenic (mREN-2)27 rats.

Vasopeptidase inhibitors simultaneously inhibit both angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP). The aim of this study was to determine the cardiorenal effects of the vasopeptidase inhibitor omapatrilat in the transgenic m(Ren-2)27 rat which exhibits fulminant hypertension and severe organ pathology. At 6 weeks of age, male Ren-2 rats were randomized to receive no treatment (N = 10), the ACE inhibitor fosinopril 10 mg/kg/day (N = 10), or omapatrilat 10 mg/kg/day (N = 10) or 40 mg/kg/day (N = 10) by daily gavage for 24 weeks. Various cardiorenal functional and structural parameters were assessed. Compared to controls, all treatment groups reduced hypertension in control Ren-2 rats, with both doses of omapatrilat reducing systolic blood pressure significantly more than fosinopril (control, 178 +/- 3 mmHg; fosinopril 10 mg/kg/day, 130 +/- 4 mmHg; omapatrilat 10 mg/kg/day, 110 +/- 3 mmHg; omapatrilat 40 mg/kg/day, 91 +/- 3 mmHg). Omapatrilat dose-dependently reduced cardiac hypertrophy, caused a greater inhibition of renal ACE than fosinopril, and was the only treatment to inhibit renal NEP. Attenuation of albuminuria, glomerulosclerosis and cardiorenal fibrosis occurred to a similar degree with omapatrilat and fosinopril. Omapatrilat confers cardiorenal protection in the hypertensive Ren-2 rat. Although inhibition of tissue NEP may contribute to the superior blood pressure reduction by omapatrilat, overall, the results are consistent with the central role that angiotensin II plays in renal and cardiac fibrosis in this model of hypertension.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2004

New insights into the significance of microalbuminuria.

PURPOSE OF REVIEW: This review summarizes recent work that has explored the association between microalbuminuria and adverse clinical outcomes in the presence and absence of diabetes. RECENT FINDINGS: Recent investigations have documented the prevalence of microalbuminuria in the general community and have also highlighted the continuous relationship between the level of urinary albumin excretion and clinical endpoints. Even below traditional microalbuminuria thresholds, urinary albumin levels appear to correlate with clinical outcomes. Microalbuminuria is becoming increasingly recognized as an independent risk factor for cardiovascular morbidity and mortality. At least for subjects with type 2 diabetes and microalbuminuria, intensive, multifactorial interventions can reduce the risk of cardiovascular events by about 50%. Although several studies have found an association between microalbuminuria and surrogate measurements of vascular disease, the exact molecular mechanisms linking an increase in urinary albumin excretion and vascular disease are still unknown. Microalbuminuria also has a well-documented association with progressive diabetic renal disease but recent studies have suggested that the prognostic significance of microalbuminuria in this regard may not be as powerful as originally reported. SUMMARY: Aggressive, multifactorial interventions, including the use of drugs that interrupt the renin-angiotensin system are strongly recommended for patients with diabetes and micro-albuminuria to ameliorate the progression of renal and vascular complications. This approach should also possibly apply to microalbuminuric subjects without diabetes. The relationship between microalbuminuria and progressive diabetic renal disease requires re-evaluation given temporal trends in the prevention and treatment of diabetic complications.

Albuminuria↗
PubMed2004

Heparanase is involved in the pathogenesis of proteinuria as a result of glomerulonephritis.

The beta-D-endoglycosidase heparanase has been proposed to be important in the pathogenesis of proteinuria by selectively degrading the negatively charged side chains of heparan sulfate proteoglycans within the glomerular basement membrane. A loss of negatively charged heparan sulfate proteoglycans may result in alteration of the permselective properties of the glomerular basement membrane, loss of glomerular epithelial and endothelial cell anchor points, and liberation of growth factors. In this study, therefore, the role of heparanase in passive Heymann nephritis (PHN) was examined. Normal glomeruli showed low-level heparanase expression as determined by immunohistochemistry and Western blot analysis. Days 5, 14, and 28 of PHN were associated with an increase in endothelial and glomerular epithelial cell heparanase. Reverse transcription-PCR confirmed a significant increase in mRNA at day 21 of disease (P < 0.0004). Furthermore, urinary and glomerular heparanase activities were significantly increased at days 5 and 21 of disease, respectively. Western blot analysis of isolated glomeruli separated into membrane- and cytosol-enriched protein fractions showed that the active 58-kD heparanase species was increased but restricted to the cytosol of diseased glomeruli at day 21. The inactive 65-kD precursor, however, was found in membrane and cytosol-diseased fractions, suggesting cell membrane processing. Complement depletion prevented glomerular heparanase expression; in addition, administration of a polyclonal anti-heparanase antibody significantly reduced urinary protein excretion at day 5 of disease to 62 +/- 11 mg/d compared with 203 +/- 43 and 159 +/- 18 mg/d in the normal rabbit serum- and normal saline-treated experimental groups, respectively (P < 0.002). Proteinuria was reduced in the absence of any altered glomerular C5b-9 activity, sheep IgG deposition, or rat anti-sheep antibody titers. These data suggest that heparanase contributes to the pathogenesis of proteinuria in PHN.

Animals↗