Background. Progressive expansion of the mesangial matrix is one of the most characteristic histological features of diabetic nephropathy (DN). Connective tissue growth factor (CTGF) is an important factor in the pathogenesis of mesangial matrix expansion and progressive glomerulosclerosis. Methods. To evaluate the expression and localization of CTGF mRNA in the renal tissues of 23 patients with DN and in normal human kidney (NHK), high-resolution in situ hybridization, using a digoxigenin-labeled oligonucleotide, was performed. The patients with DN were classified into three groups based on the histopathological severity of the DN: mild (grade I; n ϭ 9), moderate (grade II; n ϭ 10), and severe (grade III; n ϭ 4). Mesangial expansion and tubulointerstitial injury were evaluated histologically. To quantitate the expression of CTGF mRNA, all nuclei as well as nuclei surrounded by CTGF-positive cytoplasm, in at least ten randomly selected cross-sections of nonsclerotic glomeruli were counted, and the results were expressed as a percentage of the total number of glomerular cells. Results. In both DN and NHK, CTGF mRNA was expressed mainly in intrinsic glomerular cells, including glomerular mesangial cells, epithelial cells and cells of Bowman's capsule. In the tubulointerstitial area, some tubules, particularly atrophic tubules, and some infiltrating cells in DN, were positively stained for CTGF mRNA, especially in DN grade III. The percentage of CTGF mRNA-positive cells was significantly higher in DN than in NHK, and the percentage of these cells was higher in grades I and II DN than in grade III DN. Conclusions.Our results suggest that the expression of CTGF mRNA may be associated with the development and progression of human diabetic nephropathy.

Background. Connective tissue growth factor (CTGF) is a cysteine-rich member of a new family of growth regulators. Its upregulation is an important factor in the pathogenesis of mesangial matrix accumulation and progressive glomerulosclerosis. Methods. We evaluated the expression and localization of CTGF mRNA in renal tissues of 20 patients with IgA nephropathy (IgA-N) and 5 normal human kidneys (NHK), using high-resolution in situ hybridization with digoxigeninlabeled oligonucleotide. The expression level of CTGF mRNA was quantitated by counting all nuclei, as well as nuclei surrounded by CTGF mRNA-positive cytoplasm in at least ten randomly selected cross-sections of nonsclerotic glomeruli, and expressing the results as percentage of positive cells.

Background. Hyperglycemia is the most important contributor to the development of diabetic nephropathy (DN). The activation of protein kinase C (PKC) caused by hyperglycemia is implicated in the pathogenesis of DN. PKC, which comprises a family of enzymes, plays a role in many signal transduction pathways and is involved in the regulation of cell growth and differentiation. However, the precise role of PKC in the progression of human DN is not fully understood. Methods. To evaluate the pathological role of PKC in DN, we examined the mRNA expression levels of PKC α and PKC I isoforms in normal renal tissues and in renal tissues affected by DN. Tissues from open renal biopsies were obtained from 20 type 2 diabetic patients with DN. The expression levels of PKC α and PKC I mRNA in kidneys with DN and in normal human kidney (NHK) were evaluated by in-situ hybridization, using digoxigenin-labeled oligonucleotide probes. Results. Cells positive for PKC α and I mRNA were mainly observed in glomeruli, and some mRNA was also detected in the tubulointerstitium. The percentages of glomerular cells positive for PKC α and I mRNA were higher in kidneys with DN than in NHK. In the glomeruli of kidneys with DN, the percentage of cells positive for PKC I mRNA, but not the percentage of cells positive for PKC α mRNA, tended to be decreased with the degree of mesangial expansion. Conclusions. Our results suggest that the expression of mRNA for PKC α and/or I may be associated with the progression of DN.

Connective tissue growth factor (CTGF) induces kidney fibroblast proliferation and extracellular matrix synthesis. Furthermore, the effects of transforming growth factor-b (TGF-b) on fibrosis were found to be partially mediated by CTGF. To explore the roles of TGF-b and CTGF in the pathogenesis of IgA nephropathy (IgAN), we examined the expression of CTGF mRNA and TGFb mRNA in human IgAN and normal human kidney (NHK) using high-resolution with the in situ hybridization method.We evaluated the expression and localization of these two mRNAs in renal tissue samples from 12 patients with IgAN and 4 subjects with NHK. To quantify the expression of these mRNAs, all nuclei as well as surrounding nuclei in mRNA positive cytoplasm of at least 10 randomly selected cross-sections of non-sclerotic glomeruli were blindly enumerated. Results were expressed as percentages of positive cells.In both IgAN and NHK, CTGF and TGF-b mRNAs were mainly expressed in glomerular intrinsic cells including glomerular mesangial and epithelial cells, and some Bowman's capsule cells. In the interstitium, some tubules, particularly atrophic tubules, and some infiltrating cells were positively stained for both CTGF and TGF-b mRNAs in IgAN.The percentage of positive cells for these mRNAs was significantly greater in IgAN than in NHK. This percentage was also significantly higher in IgAN with moderate mesangial proliferative lesions than in IgAN with mild mesangial proliferative lesions and/or sclerotic lesions. Furthermore, the percentage of positive cells for CTGF mRNA was significantly correlated with that for TGF-b mRNA. These results suggest that the link between the expression of CTGF and TGF-b mRNAs may play an important role in the development and progression of human IgAN Table 1 Percentage of positive cells of CTGF and TGF-b Mrna in IgAN and NHK (mean ± SD) Grade CTGF TFG-b IgAN1 (n = 3) 15.6 ± 1.0a 15.1 ± 0.6 a,b IgAN2 (n = 3) 24.3 ± 2.5 a,b,c 23.0 ± 1.3 a,b,c IgAN3 (n = 3) 24.8 ± 1.0 a,b,c 21.0 ± 1.2 a,b,c IgAN4 (n = 3) 15.7 ± 1.2 a 13.4 ± 0.2 a NHK (n = 4) 9.6 ± 1.0 11.3 ± 0.8 a < 0.05 vs. NHK; b < 0.05 vs. IgAN4; c < 0.05 vs. IgAN1Fig. 1 Correlation between TGF-b and CTGF in IgA nephropathy (n = 12) 14 18 22 26 30 12 14 16 18 20 22 24 26 TGF-b mRNA (%) CTGF mRNA (%) r 2 = 0.778 p<0.001