Hisayuki Nishioka

Oxidative DNA Damage and Tubulointerstitial Injury in Diabetic Nephropathy

Background: Oxidative stress is an important pathogenetic factor in underlying diabetic complications. Recently, 8-hydroxy-2′-deoxyguanosine (8-OHdG) has been reported to serve as a new sensitive biomarker of the oxidative DNA damage in vivo. We studied the relationship between oxidative DNA damage and tubulointerstitial injury in patients with diabetic nephropathy. Methods: Type 2 diabetic patients (n = 25) and healthy control subjects (n = 20) were studied. The urine concentrations of 8-OHdG were measured by a competitive ELISA. The severity of the glomerular changes was graded using Gellman’s criteria, and the severity of the tubulointerstitial lesions was determined by a semiquantitative estimate of the space occupied by the fibrous tissue and/or interstitial infiltrates. Results: The urinary 8-OHdG excretion were significantly higher in the diabetics than in the healthy controls, and tended to increase with severity of the glomerular diffuse lesion, but it was not significant. The urinary 8-OHdG excretion significantly increased with severity of the tubulointerstitial lesion. Conclusions: Oxidative stress may contribute to the progression of tubulointerstitial injury in patients with diabetic nephropathy.

Work-related aggression and violence committed by patients and its psychological influence on doctors.

Work‐related Aggression and Violence Committed by Patients and Its Psychological Influence on Doctors: Keigo Saeki, et al. Department of Community Health and Epidemiology, Nara Medical University School of Medicine

Serum Levels of Advanced Glycosylation End Products in Diabetic Nephropathy

Background/Aims: Advanced glycosylation end products (AGEs) are important pathogenetic factors underlying diabetic complications. Recently, a highly reliable new enzyme-linked immunosorbent assay for these metabolites has been established. We used the assay to correlate AGEs in serum with renal function categories and histopathology in patients with diabetic nephropathy. Methods: Type 2 diabetic patients (n = 71) and healthy control subjects (n = 35) were studied. The diabetic subjects were divided into two groups: normal renal function and chronic renal failure not requiring dialysis. In renal biopsy specimens from 22 diabetic subjects with a normal renal function, the severity of glomerular lesions was assessed morphometrically in terms of the ratio of the area of periodic acid-Schiff stained mesangium to total glomerular area. Results: The serum AGE concentrations were higher in both undialyzed diabetic groups, especially in those with renal failure, than in the controls. The serum AGE concentrations increased with the severity of glomerular lesions (morphometric ratio under 15%, 2.85 ± 0.73 mU/ml; 15–24%, 4.01 ± 0.71 mU/ml; 25% or more, 5.12 ± 0.64 mU/ml). Conclusions: The serum AGE levels measured by the new enzyme-linked immunosorbent assay reflected the severity of glomerulopathy, and, therefore, it may be a clinically useful tool for assessing diabetic renal complications.

The role of extracellular glutathione peroxidase in diabetic nephropathy.

Accessible online at: www.karger.com/journals/nef Dear Sir, Oxidative stress is an underlying common pathogenetic mechanism of diabetic complications [1]. Increased active oxygen and reduced antioxidant activity will result in an increase in oxidative stress, and may contribute to the development of diabetic nephropathy [1]. Glutathione peroxidase (GPX) is believed to play a key role in the antioxidant defense system, and three types of GPX have been identified: cellular GPX (cGPX), membrane-bound GPX (mGPX) and extracellular GPX (eGPX). Recently, a reliable enzyme-linked immunosorbent assay (ELISA) for human eGPX was developed [2]. However, only a few studies have examined the plasma eGPX concentration in renal diseases [3–6], and there is no information about eGPX in patients with diabetic nephropathy. We therefore investigated the relationship between the plasma and urinary concentrations of eGPX and the severity of the glomerular and tubular lesions in patients with diabetic nephropathy. Thirty type 2 diabetic patients (17 males and 13 females, mean age 52 years) who had undergone a renal biopsy were enrolled in this study after giving informed consent. Twenty nondiabetic healthy volunteers (HV; 13 males and 7 females, mean age 45 years) and 20 type 2 diabetic patients on hemodialysis (HD; 12 males and 8 females, mean age 55 years) served as controls. Plasma samples were obtained from each subject. Twentyfour-hour urine specimens (except for the HD patients) were collected, and aliquots were stored at –20 °C. The plasma and urine concentrations of eGPX were measured by a one-step sandwich enzyme immunoassay (Oxis International, USA). The severity of the glomerular changes was graded as D1, D2 and D3 using Gellman’s criteria [7]. The severity of the tubulointerstitial lesions was determined by a semiquantitative estimate of the space occupied by the fibrous tissue and/or interstitial infiltrates using the criteria: T1 (damaged area !10%, T2 (10%! damaged area !30%) and T3 (30%! damaged area). In the diabetic subjects, 15 patients were normoalbuminuric (AER !20 Ìg), 9 were microalbuminuric (AER 20–200 Ìg) and 6 had overt proteinuria. The mean serum creatinine was 0.87 B 0.65 (range 0.6–1.8) mg/ dl and the HbA1c was 7.8 B 4.5% (range 6.5–9.3%). The plasma concentrations of eGPX were significantly higher in the D1 patients compared to the HV, and significantly lower in the D3 patients compared to the HV, D1 and D2 patients. The concentrations varied inversely with severity of the diffuse glomerular lesions. There was no correlation between the plasma eGPX concentrations and the grade of the tubulointerstitial lesions. The HD patients had significantly lower concentrations of plasma eGPx than Table 1. Plasma and urinary eGPX concentrations in control and study subjects

Glomerular tuft ballooning in mitomycin-C-induced renal impairment.

Severe ballooning of the glomerular tufts was observed in a 65-year-old man who was treated with mitomycin C (MMC) and had typical MMC-induced renal lesions. He developed renal failure and severe anaemia 6 months after initiation of chemotherapy. Ballooned tufts were caused by enormous expansion of the sub-endothelial space simultaneously associated with mesangiolysis. Glomerular cysts, described in a variety of disorders including thrombotic microangiopathy and diabetes mellitus, are derived from cystically dilated and united capillary luminae secondary to mesangiolysis. The morphogenesis of this unusual lesion when induced by MMC differs from that of the glomerular cysts previously reported.

MATRIX METALLOPROTEINASE-2 AND MESANGIOLYSIS IN DIABETIC NEPHROPATHY

Accessible online at: http://BioMedNet.com/karger Dear Sir, Diabetic nephropathy is characterized by the accumulation or extracellular matrix (ECM) in the glomerular basement membrane and mesangium, which depends on the balance between its synthesis and degradation [1]. The role of matrix metalloproteinases (MMPs) in the development of diabetic nephropathy has been investigated, and it has been hypothesized that decreased degradation by MMPs may be responsible for the increase in ECM [2]. MMP-2 (gelatinase A), the 72-kD type IV collagenase, is a member of this family of enzymes which specifically degrades type IV collagen, fibronectin, laminin and proteoglycans [3]. Mesangiolysis, as dissolution or attenuation of the mesangial matrix and degeneration of mesangial cells, is the initial event in the remodeling of glomerular lesions and/or the process of nodular formation in diabetic nephropathy [4]. One hypothesis suggests that excess MMP-2 proteolytic activity causes ECM degradation resulting in mesangiolysis. We therefore investigated the relationship between the serum MMP-2 activity and the severity of glomerular lesions in type 2 diabetic patients. Thirty-nine type 2 diabetic patients (26 men and 13 women, 35–74 years of age, mean 57 B 10 years) were enrolled in this study after informed consent. Patients with any clinical and/or serologic evidence of chronic liver disease or underlying malignancy were excluded from the study. Serum MMP-2 activity was measured using a onestep sandwich enzyme immunoassay [5]. Tissue specimens obtained by percutaneous renal biopsy were processed for morphometric evaluation using light microscopy. The severity of glomerular lesions was graded as D1, D2, D3+4 using Gellman’s criteria [6]. Mesangiolysis was defined as light microscopic evidence of focal and segmental lesions consisting of loosening and disintegration of mesangial structures with associated cystic dilatation of the involved tuft and/or a fibrillar or reticular appearance or the mesangial matrix [7]. Relationship between serum MMP-2 activity and severity of glomerular lesions is shown in table 1. Mesangiolysis was observed in 3 patients with grade D2, and 5 patients with grade D3+4, glomerular lesions, but was not detected in patients with grade D1 lesions. In D3+4 group, the serum MMP-2 activity was significantly higher in patients with mesangiolysis than in patients without evidence of mesangiolysis. Human mesangial cells secrete both neutral metalloproteinase enzymes and a 68to 72-kD gelatinase [8]. MMP-2 is constitutively expressed by renal cells in culture, by mesangial cells in the normal kidney, and by macrophages that have infiltrated glomeruli [9]. The early decrease in glomerular MMP-2 gene expression has been demonstrated in renal biopsy specimens obtained from type 2 diabetic patients [10], and decreased degradation of matrix may contribute to mesangial matrix accumulation in the setting of Table 1. Serum MMP-2 activity (ng/ml) and mesangiolysis

Role of secreted protein acidic and rich in cysteine (SPARC) in patients with diabetic nephropathy

BackgroundA protein called “secreted protein acidic and rich in cysteine” (SPARC) may be important in the progression of diabetic nephropathy. Recent animal studies have shown a possible correlation between SPARC levels and diabetes-related kidney growth.MethodsWe measured serum levels of SPARC in patients with diabetic nephropathy and compared them to the severity of glomerular lesions as determined by renal biopsy. A total of 50 non-insulin-dependent diabetic patients were divided into 2 groups; patients with endstage diabetic nephropathy (ESDN, n=10) or without ESDN (DM, n=40). Renal biopsies were performed in all patients without ESDN. Serum levels of SPARC were measured by enzyme-linked immunosorbent assay (ELISA) in the 50 patients with diabetes, in 10 healthy controls, and in 10 patients with immunoglobulin (Ig) A nephropathy. Values for serum creatinine, creatinine clearance, β2-microglobulin, and hemoglobin A1C also were obtained.ResultsThe mean serum SPARC levels (ng/mL) were 29±12, 41±21, 43±20, and 85±28, for healthy controls, IgA nephropathy, DM, and ESDN patients, respectively. Serum SPARC levels showed a significant increase with an increase in severity of glomerular diffuse lesions. Serum levels of SPARC were significantly higher in the DM group than in controls, and significantly higher in the ESDN group than in the control, IgA nephropathy and DM groups.ConclusionThe findings suggest that SPARC may contribute to the progression of diabetic nephropathy.