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Background/Aim: Progressive expansion of mesangial matrix and glomerular basement membrane thickening represent alterations in the balance between synthesis and degradation of glomerular extracellular matrix (ECM) protein and are hallmarks of diabetic nephropathy. In order to elucidate the basis for this imbalance between the synthesis and the degradation of ECM in renal tissues from patients of type 1 diabetes mellitus (type 1D) with diabetic nephropathy (DN), we examined the expression of α1 chain of type IV collagen (IV-C), matrix metalloproteinase-2 and -3 (MMP-2, MMP-3), tissue inhibitor of metalloproteinase-1 (TIMP-1) and β-actin mRNA using a high-resolution in situ hybridization with digoxigenin-labeled oligonucleotide. Methods: Patients were divided into two groups based on both of degree of mesangial expansion using electron microscopic point counting morphometric methods and duration of type 1D: 7 ‘fast-track’ patients were selected for their very rapid development of DN structural changes and 8 ‘slow-track’ patients for their very slow development of DN structural changes. Seven normal human kidney (NHK) tissues were used as controls. Results: Positive cells for each mRNA were observed in glomerular resident cells, including glomerular mesangial, epithelial and endothelial cells and cells of Bowman’s capsule. The percentage of glomerular cells positive for IV-C, MMP-2 and MMP-3 mRNA was significantly greater in the ‘slow-track’ vs. ‘fast-track’ patients. No significant differences in percentage positive cells was seen for β-actin mRNA. Furthermore, to elucidate the total number of positive cells per glomerulus for each mRNA, we estimated total cell number of glomerulus using morphometric techniques on light microscopy tissues. The total cell number per glomerulus was significantly greater in ‘fast-track’ than that in ‘slow-track’ patients and NHK. The total number of positive cells per glomerulus for MMP-2 in NHK was significantly greater than that in ‘slow-track’ and ‘fast-track’ patients. Conclusion: Thus, IV-C, MMP-2, MMP-3 and TIMP-1 mRNA are expressed in resident glomerular cells in renal tissues from NHK and type 1D. Glomerular alterations in these in situ mRNA expressions sufficient to explain ECM accumulation and DN risk were not uncovered. These largely negative results could be due to methodologic quantitative imprecision or could indicate that post-translational differences account for ECM imbalance in DN. However, these studies make it clear that unraveling the nature of the ECM production/removal imbalance in DN will require careful consideration of alterations in glomerular cell number.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Pentosidine, an advanced glycation end product, accumulates in plasma proteins of uremic patients. Its fate is, however, yet to be fully understood. Methods: Three cell lines, JTC-12 (proximal tubular cells), MDCK (distal tubular cells), and BALB3T3 (nonrenal cells), were cultured in a double chamber system and were exposed to uremic serum, and the contents of protein-linked pentosidine derived from uremic sera were determined in each medium by HPLC assay. The presence of pentosidine in the cytoplasm of these cells was assessed by immunoperoxidase staining. Results: When the apical cell membrane was exposed to uremic serum (fortified in the upper chamber), the contents of protein-linked pentosidine in the upper medium decreased by up to 30% after 24- and 48-hour incubations of JTC-12 cells but not of other cells. On the other hand, the contents of protein-linked pentosidine in the lower medium did not change. By contrast, exposure of the basolateral cell membrane of the three cell lines to uremic serum (fortified in the lower chamber) did not change the contents of protein-linked pentosidine both in the upper and lower medium after a 24-hour incubation. Pentosidine was detected immunohistochemically in the cytoplasm of JTC-12 cells, but not of BALB3T3 and MDCK cells, the apical membranes of which were exposed to uremic sera for 8 h. The immunoreaction disappeared 48 h after exposure. Pentosidine was not detected in the cytoplasm of JTC-12 cells, the basolateral membranes of which were exposed to uremic sera. The relevance of the in vitro results to humans was demonstrated by immunohistochemical studies in normal human kidney tissues showing that pentosidine was identified in the proximal renal tubules. Conclusion: These results suggest that the proximal tubular cells play a role in the disposal of plasma pentosidine.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Complement activation is thought to be pathologically important in IgA nephropathy (IgAN). Although C3 deposition in the mesangium is found in IgAN, the origin of C3 is not clear. We recently demonstrated intraglomerular C3 synthesis in the human kidney; however, the activation and pathological role of locally synthesized C3 remains unclear. Here we performed nonradioactive in situ hybridization for C3 mRNA and immunohistochemistry for C3 and its activation products, such as C3d and membrane attack complex (MAC), to determine whether locally produced C3 in glomeruli was activated in IgA nephropathy. Methods: Renal samples from 14 patients with IgAN and 5 with minimal change nephrotic syndrome (MCNS) were examined. Uninvolved portions of surgically removed kidneys with tumors served as normal controls. Results: C3 mRNA was not detected in glomeruli in control tissue and MCNS, but was strongly expressed in resident glomerular cells of IgAN, including mesangial cells, glomerular epithelial cells and the cells of Bowman’s capsule. Examination of serial sections disclosed that more than 70% of cells positive for C3 mRNA were also stained for C3 protein, C3d, and MAC. Double staining for in situ hybridization and immunohistochemistry also revealed that those C3 mRNA signals were present in intraglomerular cells positive for C3. The expression of C3 mRNA and MAC in glomeruli correlated significantly with the degree of mesangial matrix expansion. Conclusions: Our results demonstrated that locally synthesized C3 is activated in the glomeruli of IgAN and that its expression correlated with the severity of mesangial matrix expansion. These findings suggest that activation of C3 may be involved in tissue injury in IgAN through the formation of membrane attack complex.Copyright © 2001 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The prevalence and renal prognosis of diagnosed autosomal dominant polycystic kidney disease (ADPKD) in Japan were estimated. Hospital-based nationwide surveys were conducted in 1995. The number of ADPKD patients who visited hospitals but were not on chronic dialysis was estimated to be 10,000 (95% confidence interval: 8,200–11,900) and that of ADPKD patients on dialysis was 4,590, yielding a prevalence of ADPKD of 117 per million population at the end of 1994 (95% confidence interval: 102–132). The prevalence increased with age and reached a peak value of 261 per million population at the age group of 55–59 years. The rate of end-stage renal disease among living patients was calculated based on the assumption that the prevalence of ADPKD in the population under the age of 55 years was 261 per million population. The rate of end-stage renal disease increased with the progression of the patients’ age, reaching 49% at the age of 65–69 years and declining thereafter. Conclusion: The hospital-based prevalence of ADPKD is lower than the autopsy-based prevalence, suggesting that a fairly large number of these patients do not receive medical care in their lifetime. The probability of end-stage renal disease is at most 50% among ADPKD patients who visit a hospital. [ABSTRACT FROM AUTHOR]