Activation of mRNA expression of collagen,collagenase and its inhibitor on renal biopsy specimens in patients with IgA nephropathy

Summary: In situ hybridization of mRNA for collagen IV, collagen VI, stromelysin (MMP-3) and TIMP1 was examined in renal biopsy specimens from patients with IgA nephropathy (IgAN) or diabetic nephropathy with various degrees of tissue damage. The majority of cells in the glomeruli expressed these mRNA almost simultaneously, but a few cells demonstrated positive expression for only one of these probes. There was a parallel relationship between the degree of tissue damage and that of mRNA expressions of these probes in patients with IgAN, while patients with diabetic nephropathy showed a reverse relationship between these two parameters. It is concluded that patients with mesangial proliferative glomerulonephritis expressed mRNA for collagen collagenase and its inhibitor in the glomeruli in parallel with the progress of tissue damage. In contrast, glomerular samples from patients with diabetic nephropathy showed that there was an inverse relationship between tissue damage and expression of mRNA. It is concluded that expression of collagen, collagenase and its inhibitor parallels the progression of glomerular changes in IgAN, but such parallel expression was not observed in patients with diabetic nephropathy.     

Hypertension in diabetic nephropathy: epidemiology, mechanisms, and management

Hypertension is highly prevalent in patients with diabetic nephropathy. Diabetic nephropathy is the leading cause of CKD and end-stage kidney disease in the United States. The etiology of hypertension in diabetic nephropathy involves mechanisms with multiple inter-related mediators that result in renal sodium reabsorption and peripheral vasoconstriction. The management of hypertension in these patients is focused on treatments that target these mediators. Clinical trials have established that drugs that inhibit the renin-angiotensin-aldosterone system should be used as first-line agents on the basis of their ability to slow down progression of kidney disease and lower albuminuria. There is further interest into how the combination of drugs that inhibit this pathway at multiple steps will contribute further to the management of hypertension and diabetic nephropathy. This article presents an updated review of the mechanisms involved in hypertension in patients with diabetic nephropathy. It also reviews the past clinical trials using single agents as therapeutics and the more recent trials involving novel drugs or drug combinations used to treat these patients. Retrospective analyses of multiple studies are included to better examine the significance of the currently proposed blood pressure targets for patients with diabetic nephropathy.     

Targeted therapies in diabetic nephropathy: an update

Diabetic nephropathy is the most common cause of end-stage renal disease worldwide. Various pathways in addition to the renin-angiotensinogen system have been implicated in the pathogenesis of diabetic nephropathy. Strategies to interrupt these pathophysiological pathways are a key to the development of new targeted therapies to prevent progression of diabetic nephropathy and are on the horizon. The various pharmacological drugs tried include aliskiren, a direct renin inhibitor blocking the first step in the renin pathway, and pentoxifylline and mammalian target of rapamycin inhibitors, which have antiinflammatory properties and have shown some promising results in management of diabetic nephropathy. Others include endothelin antagonists and vitamin D analogs which have been shown to decrease urinary albumin excretion. Inhibitors of advanced glycation and oxidative stress and plasminogen activator inhibitor-1 have proved useful in animal models of diabetic nephropathy. Others include ruboxistaurin, which blocks protein kinase C overexpression. Such targeted therapies would halt and might even reverse progression of diabetic nephropathy.     

Molecular approaches to the study of renal disease

Summary: Recent developments in cell biology and molecular biology have provided new techniques for molecular studies on renal diseases. the in situ hybridization technique demonstrates the site and the degree of gene expression of various cytokines and regulating proteins associated with the altered function of the glomeruli. It is not known, however, if the expression of these genes is different among various glomerular diseases. the aim of this study was to elucidate the disease specific phenomena in glomerular gene expression. Renal biopsy specimens were obtained from patients with diabetic nephropathy, and IgA nephropathy. the degree of tissue damage as well as the levels of various clinical parameters were matched between these two groups. In situ hybridization of mRNA in renal tissues for transforming growth factor (TGF)-β, storomelysin (MMP-3) and tissue inhibitor of metalloproteinase (TIMP-1) were performed using nonradioactive digoxigenin (DIG)-labelled oligonucleotide probes. In parallel studies, renal biopsy specimens were stained with monoclonal antibody against advanced glycated end-products (AGE). the results demonstrated that the distribution of mRNA expression of TGF-β was similar between these two diseases, but the expression of MMP-3 and TIMP-1 was parallel with the degree of tissue damage in patients with IgA nephropathy while it was diminished in patients with an advanced degree of tissue damage due to diabetic nephropathy. Positive staining of renal tissues with anti-AGE antibody was only observed in patients with diabetic nephropathy. It is concluded that glycation of renal structural proteins might interfere with their metabolism by enzymes and their inhibitors, while a cytokine responsible for mesangial expansion was similarly expressed.     

Monocyte chemoattractant protein-1 promotes the development of diabetic renal injury in streptozotocin-treated mice

Diabetic nephropathy involves a renal inflammatory response induced by the diabetic milieu. Macrophages accumulate in diabetic kidneys in association with the local upregulation of monocyte chemoattractant protein-1 (MCP-1); however, the contribution of macrophages to renal injury and the importance of MCP-1 to their accrual are unclear. Therefore, we examined the progression of streptozotocin (STZ)-induced diabetic nephropathy in mice deficient in MCP-1 in order to explore the role of MCP-1-mediated macrophage accumulation in the development of diabetic kidney damage. Renal pathology was examined at 2, 8, 12 and 18 weeks after STZ treatment in MCP-1 intact (+/+) and deficient (-/-) mice with equivalent blood glucose and hemoglobin A1c levels. In MCP-1(+/+) mice, the development of diabetic nephropathy was associated with increased kidney MCP-1 production, which occurred mostly in tubules, consistent with our in vitro finding that elements of the diabetic milieu (high glucose and advanced glycation end products) directly stimulate tubular MCP-1 secretion. Diabetes of 18 weeks resulted in albuminuria and elevated plasma creatinine in MCP-1(+/+) mice, but these aspects of renal injury were largely suppressed in MCP-1(-/-) mice. Protection from nephropathy in diabetic MCP-1(-/-) mice was associated with marked reductions in glomerular and interstitial macrophage accumulation, histological damage and renal fibrosis. Diabetic MCP-1(-/-) mice also had a smaller proportion of kidney macrophages expressing markers of activation (inducible nitric oxide synthase or sialoadhesin) compared to diabetic MCP-1(+/+) mice. In conclusion, our study demonstrates that MCP-1-mediated macrophage accumulation and activation plays a critical role in the development of STZ-induced mouse diabetic nephropathy.     

Increased urinary excretion of monocyte chemoattractant protein-1 in proteinuric renal diseases

Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that is produced mainly by tubular epithelial cells in kidney and contributes to renal interstitial inflammation and fibrosis. More recently, we have demonstrated that urinary MCP-1 excretion is increased in proportion to the degree of albuminuria (proteinuria) and positively correlated with urinary N-acetylglucosaminidase (NAG) levels in type 2 diabetic patients. Based on these findings, we have suggested that heavy proteinuria, itself, probably aggravates renal tubular damage and accelerates the disease progression in diabetic nephropathy by increasing the MCP-1 expression in renal tubuli. In the present study, to evaluate whether urinary MCP-1 excretion is increased in the proteinuric states not only in diabetic nephropathy but also in other renal diseases, we examined urinary MCP-1 levels in IgA nephropathy patients with macroalbuminuria (IgAN group; n = 6), and compared the results with the data obtained from type 2 diabetic patients with overt diabetic nephropathy (DN group; n = 23) and those without diabetic nephropathy (non-DN group; n = 27). Urinary MCP-1 excretion levels in non-DN, DN, IgAN groups were 157.2 (52.8-378.5), 346.1 (147.0-1276.7), and 274.4 (162.2-994.5) ng/g creatinine, median (range), respectively. Expectedly, urinary MCP-1 and NAG excretion levels in DN and IgAN groups were significantly elevated as compared with non-DN group. Therefore, we suggest that MCP-1 expression in renal tubuli is enhanced in proteinuric states,irrespective of the types of renal disease, and that increased MCP-1 expression probably contributes to renal tubular damage in proteinuric states.     

Nodular glomerulosclerosis mimicking diabetic nephropathy without overt diabetes mellitus

The duration of diabetes mellitus and presence of hyperglycemia appear to be important in the development of diabetic nephropathy. Here, we present three patients with edema, heavy proteinuria, chronic renal failure, in whom no past or present symptomatic glucose intolerance or diabetic retinopathy were found. The kidney biopsy of these patients showed diffuse glomerular basement membrane thickening and nodular glomerulosclerosis, which resembled diabetic nephropathy. The renal function of these patients deteriorated rapidly and renal replacement therapy started later in the average of 11 months since the first visiting. These cases were diagnosed as diabetic nodular glomerulosclerosis, although there was no obvious evidence for diabetes. The absence of overt diabetes and diabetic retinopathy at presentation of nodular glomerulosclerosis in these cases does not refute the hypothesis that metabolic consequence of hyperglycemia is a prerequisite for the pathogenesis of diabetic microangiopathy, but some factors other than hyperglycemia may be responsible for renal damage in our patients. The modifiable risk factors in such a condition are postulated and discussed.     

Podocyte-specific overexpression of the antioxidant metallothionein reduces diabetic nephropathy

Podocytes are critical components of the selective filtration barrier of the glomerulus and are susceptible to oxidative damage. For investigation of the role of oxidative stress and podocyte damage in diabetic nephropathy, transgenic mice that overexpress the antioxidant protein metallothionein (MT) specifically in podocytes (Nmt mice) were produced. MT expression was increased six- and 18-fold in glomeruli of two independent lines of Nmt mice, and podocyte-specific overexpression was confirmed. Glomerular morphology and urinary albumin excretion were normal in Nmt mice. OVE26 transgenic mice, a previously reported model of diabetic nephropathy, were crossed with Nmt mice to determine whether an antioxidant transgene targeted to podocytes could reduce diabetic nephropathy. Double-transgenic OVE26Nmt mice developed diabetes similar to OVE26 mice, but MT overexpression reduced podocyte damage, indicated by more podocytes, less glomerular cell death, and higher density of podocyte foot processes. In addition, expansion of glomerular and mesangial volume were significantly less in OVE26Nmt mice compared with OVE26 mice. Four-month-old OVE26Nmt mice had a 70 to 90% reduction in 24-h albumin excretion, but this protection does not seem to be permanent. These results provide evidence for the role of oxidative damage to the podocyte in diabetic mice and show that protection of the podocyte can reduce or delay primary features of diabetic nephropathy.     

Mesangial expansion as a central mechanism for loss of kidney function in diabetic patients

Diabetic nephropathy leading to kidney failure is a major complication of both type I (insulin-dependent) and type II (non-insulin-dependent) diabetes mellitus, and glomerular structural lesions (especially expansion of the mesangium) may constitute the principal cause of decline in kidney function experienced by a significant fraction of diabetic patients. Although the biochemical bases of these mesangial abnormalities remain unknown, an understanding of the natural history of diabetic nephropathy from a combined structural and functional approach can lead to greater pathophysiological insight. Work in animals has supported the concept that the metabolic disturbances of diabetes mellitus cause diabetic nephropathy, with structural and functional lesions prevented or reversed with improved or normalized glycemic control. Additional research must address this fundamental issue in humans, especially the response of advancing mesangial lesions to improved glycemic control. Factors not directly related to the metabolic perturbations of diabetes may serve to accelerate or diminish the pathophysiological processes of diabetic nephropathy. The elucidation and management of these factors, when coupled with improved glycemic control, may moderate the development or progression of diabetic kidney lesions in humans.     

Reduced expression of lipoic acid synthase accelerates diabetic nephropathy

Oxidative stress contributes to the pathogenesis of diabetic nephropathy. In mitochondria, lipoic acid synthase produces α-lipoic acid, an antioxidant and an essential cofactor in α-ketoacid dehydrogenase complexes, which participate in glucose oxidation and ATP generation. Administration of lipoic acid abrogates diabetic nephropathy in animal models, but whether lower production of endogenous lipoic acid promotes diabetic nephropathy is unknown. Here, we crossed mice heterozygous for lipoic acid synthase deficiency (Lias(+/-)) with Ins2(Akita/+) mice, a well characterized model of type 1 diabetes. Double mutant mice had more overt diabetic nephropathy, including microalbuminuria, glomerular basement thickening, mesangial matrix expansion, and hypertension, compared with Lias(+/+)Ins2(Akita/+) controls. We also identified proximal tubules as a major site for generation of superoxide anions during diabetic nephropathy. Mitochondria in proximal tubular cells were particularly sensitive to damage in diabetic mice with reduced lipoic acid production. These results suggest that lipoic acid synthase deficiency increases oxidative stress and accelerates the development of diabetic nephropathy.     

Alterations in the renal elastin-elastase system in type 1 diabetic nephropathy identified by proteomic analysis

Diabetes now accounts for >40% of patients with ESRD. Despite significant progress in understanding diabetic nephropathy, the cellular mechanisms that lead to diabetes-induced renal damage are incompletely defined. For defining changes in protein expression that accompany diabetic nephropathy, the renal proteome of 120-d-old OVE26 transgenic mice with hypoinsulinemia, hyperglycemia, hyperlipidemia, and proteinuria were compared with those of background FVB nondiabetic mice (n = 5). Proteins derived from whole-kidney lysate were separated by two-dimensional PAGE and identified by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. Forty-one proteins from 300 visualized protein spots were differentially expressed in diabetic kidneys. Among these altered proteins, expression of monocyte/neutrophil elastase inhibitor was increased, whereas elastase IIIB was decreased, leading to the hypothesis that elastin expression would be increased in diabetic kidneys. Renal immunohistochemistry for elastin of 325-d-old FVB and OVE26 mice demonstrated marked accumulation of elastin in the macula densa, collecting ducts, and pelvicalyceal epithelia of diabetic kidneys. Elastin immunohistochemistry of human renal biopsies from patients with type 1 diabetes (n = 3) showed increased elastin expression in renal tubular cells and the interstitium but not glomeruli. These results suggest that coordinated changes in elastase inhibitor and elastase expression result in increased tubulointerstitial deposition of elastin in diabetic nephropathy. The identification of these coordinated changes in protein expression in diabetic nephropathy indicates the potential value of proteomic analysis in defining pathophysiology.     

Management of dyslipidemia in diabetic CKD patients

Diabetic nephropathy is a frequent complication in type 2 diabetic. Patients with diabetic nephropathy have a characteristic dyslipidemia profile associated increased concentrations of triglycerides, reduced levels of HDL cholesterol, and qualitative abnormalities of LDL. The dyslipidemia management in patients with diabetic nephropathy not yet in dialysis includes diet, insulin sensitizers (glitazones, metformin?), and hypolipemic agents, with statins as a first choice.     

Sodium-hydrogen antiporter: its possible role in the genesis of diabetic nephropathy

The epidemiological evidence that only a subset of diabetic patients are susceptible to renal damage and the demonstration of clear familiar clustering of diabetic nephropathy are consistent with the possibility that genetic factors may explain the liability to or protection from renal disease of diabetic patients. A predisposition to hypertension and cardiovascular disease may be an important determinant of susceptibility to renal disease and its cardiovascular complications in diabetes since raised blood pressure [1] and an increased frequency of cardiovascular disease [2] are more prevalent in parents of diabetic patients with nephropathy. These results have raised growing interest in the search for intermediate phenotypes significantly associated with diabetic nephropathy, poorly influenced by environment, stable with age, easy to quantify and possibly dependent upon a single major gene effect. Such intermediate phenotypes can be useful for early diagnosis and would help clarify the molecular mechanisms leading to diabetic nephropathy. An elevation of Na+/H+ antiporter activity has consistently been associated with diabetic renal disease both in insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) patients, making this cell membrane exchanger system an ideal intermediate phenotype for the study of diabetic nephropathy.      

Accumulation of 8-hydroxy-2'-deoxyguanosine and mitochondrial DNA deletion in kidney of diabetic rats

Oxidative stress may contribute to the pathogenesis of diabetic nephropathy. However, the detailed molecular mechanism remains uncertain. Here, we report oxidative mitochondrial DNA (mtDNA) damage and accumulation of mtDNA with a 4,834-bp deletion in kidney of streptozotocin-induced diabetic rats. At 8 weeks after the onset of diabetes, levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), which is a marker of oxidative DNA damage, were significantly increased in mtDNA from kidney of diabetic rats but not in nuclear DNA, suggesting the predominant damage of mtDNA. Semiquantitative analysis using PCR showed that the frequency of 4,834-bp deleted mtDNA was markedly increased in kidney of diabetic rats at 8 weeks, but it did not change at 4 weeks. Intervention by insulin treatment starting at 8 weeks rapidly normalized an increase in renal 8-OHdG levels of diabetic rats, but it did not reverse an increase in the frequency of deleted mtDNA. Our study demonstrated for the first time that oxidative mtDNA damage and subsequent mtDNA deletion may be accumulated in kidney of diabetic rats. This may be involved in the pathogenesis of diabetic nephropathy.     

APOE polymorphism and diabetic nephropathy

Epidemiological studies suggest the existence of a genetic susceptibility to the development of diabetic nephropathy. The apolipoprotein E gene (APOE), which is well known to have a polymorphism (ε2, ε3, and ε4) in exon 4, has been considered a candidate gene susceptible to this complication, because this variation was reportedly involved in lipid metabolism. To date, numerous case–control studies in patients with type 1 and type 2 diabetes have been reported. Although the ε2 allele of the APOE polymorphism tends to be associated with an increased risk for diabetic nephropathy, the results of these case–control comparisons are conflicting. However, a family-based study (the transmission/disequilibrium test) provided strong evidence that the ε2 allele was preferentially transmitted to patients with diabetic nephropathy but not transmitted to those without it. Several prospective follow-up studies also reported an increased risk for progression to higher stages of diabetic nephropathy for the ε2 carriers. Furthermore, two recent meta-analyses reported that the ε2 allele is associated with a risk for diabetic nephropathy. Based on the results of these studies, the ε2 allele of the APOE polymorphism seems to be a genetic risk factor for diabetic nephropathy susceptibility. However, this genetic effect only accounts for a small proportion of this complication, and the mechanism remains unclear at present. Further studies are needed to explore whether genotyping of the APOE polymorphism in patients with diabetes is of value for better management in clinical practice.     

Diabetic nephropathy--what have we learned in the last three decades?

The past three decades have seen enormous conceptual advances in understanding the pathogenesis of diabetic nephropathy. Increasing evidence points to important genetic determination of the renal risk, i.e. the propensity to develop diabetic nephropathy, in type 1 and type 2 diabetic patients. We are also further along the path to understanding the abnormalities of renal hemodynamics that underly these patients' propensity to develop diabetic glomerulosclerosis, i.e. afferent arterial vasodilation and increased glomerular pressure, identified in elegant experimental studies. Another important advance is the recognition that increased urinary albumin excretion is not only an extremely sensitive marker, but also an important player in the pathogenesis of diabetic nephropathy. Finally, the concept of the toxicity of hyperglycemia ("glucotoxicity") has been carried to the molecular level, so that pathomechanisms such as activation of protein kinase C and cellular damage by advanced glycation endproducts (AGE), to name only two, have been elucidated. Diabetic nephropathy has become the leading cause of endstage renal failure (ESRF) in Western countries, particularly in patients with type 2 diabetes. Three treatment modalities are available: (i) hemodialysis,(ii) CAPD and (iii) transplantation, meaning kidney transplantation, combined pancreas and kidney transplantation or - still in a very preliminary stage - islet cell transplantation. The ideal is to have all three modalities available to meet each patient's individual needs. Treatment outcome continues to be considerably worse, however, in diabetic than non-diabetic patients. This highlights the importance of prevention. Progression to ESRF in diabetic nephropathy is preventable, at least to a large extent.     

Diabetic nephropathy: recent insights into the pathophysiology and the progression of diabetic nephropathy

Diabetes has become the single most frequent comorbid condition in patients admitted for renal replacement therapy. This is the result of a greater prevalence of type 2 diabetes and better survival of diabetic patients. Progress has been made in pinpointing the predisposition to diabetes on metabolic abnormalities of muscle mitochondrial metabolism, but the long sought genes predisposing to diabetes and to diabetic nephropathy have not yet been identified. Of great concern are experimental studies documenting that maternal hyperglycemia causes nephron underdosing in the offspring. Relevant to pathogenesis and treatment of diabetic nephropathy are, among others, recent insights that hyperglycemia sensitizes target organs to blood pressure-induced damage, and that local renin-angiotensin systems play an important role in genesis and progression of diabetic nephropathy.     

Vascular Endothelial Growth Factor-A165b Is Protective and Restores Endothelial Glycocalyx in Diabetic Nephropathy

Diabetic nephropathy is the leading cause of ESRD in high-income countries and a growing problem across the world. Vascular endothelial growth factor-A (VEGF-A) is thought to be a critical mediator of vascular dysfunction in diabetic nephropathy, yet VEGF-A knockout and overexpression of angiogenic VEGF-A isoforms each worsen diabetic nephropathy. We examined the vasculoprotective effects of the VEGF-A isoform VEGF-A₁₆₅b in diabetic nephropathy. Renal expression of VEGF-A₁₆₅b mRNA was upregulated in diabetic individuals with well preserved kidney function, but not in those with progressive disease. Reproducing this VEGF-A₁₆₅b upregulation in mouse podocytes in vivo prevented functional and histologic abnormalities in diabetic nephropathy. Biweekly systemic injections of recombinant human VEGF-A₁₆₅b reduced features of diabetic nephropathy when initiated during early or advanced nephropathy in a model of type 1 diabetes and when initiated during early nephropathy in a model of type 2 diabetes. VEGF-A₁₆₅b normalized glomerular permeability through phosphorylation of VEGF receptor 2 in glomerular endothelial cells, and reversed diabetes-induced damage to the glomerular endothelial glycocalyx. VEGF-A₁₆₅b also improved the permeability function of isolated diabetic human glomeruli. These results show that VEGF-A₁₆₅b acts via the endothelium to protect blood vessels and ameliorate diabetic nephropathy.     

Immunohistochemical analysis of extracellular components on the glomerular sclerosis in patients with glomerulonephritis and diabetic nephropathy

Immunofluorescence and immunoperoxidase staining were carried out to determine the correlations between the progression of glomerular sclerosis and changes in the amount and distribution of glomerular extracellular components, such as Type I, III, IV, V, VI collagen, laminin (LN) and fibronectin (FN) in patients with various types of glomerulonephritis and diabetic nephropathy. Six patients with IgA nephropathy, four patients with membrano-proliferative glomerulonephritis, four patients with rapidly progressive glomerulonephritis and six patients with diabetic nephropathy were examined. The intensity and distribution of Type IV collagen, LN and FN were similar between the glomeruli from normal individuals and patients with mild stages of glomerulonephritis and diabetic nephropathy. However, staining of Type I, III or V collagen was not observed in the glomeruli from normal individuals and such patients. In more advanced stages of glomerulonephritis and diabetic nephropathy, the amounts of Types IV and VI collagen, LN and FN were increased markedly in the mesangium, and their distribution extended along the glomerular capillary walls. The intensity of Type IV collagen, LN or FN in the nodular sclerotic lesions of glomeruli was decreased significantly in patients with glomerulonephritis and diabetic nephropathy. On the other hand, staining of Types I, III and V collagen was observed focally in the sclerotic or hyalinotic glomeruli and around such glomeruli in these patients. In light microscopic examinations, the patients who had marked staining of Type I, III or V collagen by immunofluorescence showed severe damage of the basement membrane in Bowman's capsules. It is concluded that hyperproduction and/or infiltration of interstitial collagens, i.e. Types I, III and V collagen, is closely linked to the progression of glomerular sclerosis and hyalinosis in patients with various types of glomerulonephritis and diabetic nephropathy.     

Increased Urinary Excretion of Monocyte Chemoattractant Protein-1 in Proteinuric Renal Diseases

Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that is produced mainly by tubular epithelial cells in kidney and contributes to renal interstitial inflammation and fibrosis. More recently, we have demonstrated that urinary MCP-1 excretion is increased in proportion to the degree of albuminuria (proteinuria) and positively correlated with urinary N-acetylglucosaminidase (NAG) levels in type 2 diabetic patients. Based on these findings, we have suggested that heavy proteinuria, itself, probably aggravates renal tubular damage and accelerates the disease progression in diabetic nephropathy by increasing the MCP-1 expression in renal tubuli. In the present study, to evaluate whether urinary MCP-1 excretion is increased in the proteinuric states not only in diabetic nephropathy but also in other renal diseases, we examined urinary MCP-1 levels in IgA nephropathy patients with macroalbuminuria (IgAN group; n = 6), and compared the results with the data obtained from type 2 diabetic patients with overt diabetic nephropathy (DN group; n = 23) and those without diabetic nephropathy (non-DN group; n = 27). Urinary MCP-1 excretion levels in non-DN, DN, IgAN groups were 157.2 (52.8–378.5), 346.1 (147.0–1276.7), and 274.4 (162.2–994.5) ng/g creatinine, median (range), respectively. Expectedly, urinary MCP-1 and NAG excretion levels in DN and IgAN groups were significantly elevated as compared with non-DN group. Therefore, we suggest that MCP-1 expression in renal tubuli is enhanced in proteinuric states, irrespective of the types of renal disease, and that increased MCP-1 expression probably contributes to renal tubular damage in proteinuric states.