RhoA/Rho-kinase contribute to the pathogenesis of diabetic renal disease.

OBJECTIVE: Accumulation of glomerular matrix proteins is central to the pathogenesis of diabetic nephropathy, with resident mesangial cells (MCs) known to upregulate matrix protein synthesis in response to high glucose. Because activation of the GTPase RhoA has been implicated in matrix upregulation, we studied its role in induction of the matrix protein fibronectin in diabetic MCs and in vivo in diabetic nephropathy. RESEARCH DESIGN AND METHODS: Glucose (30 mmol/l)-induced RhoA/Rho-kinase, AP-1 activation, and fibronectin upregulation were assessed by immunoblotting, luciferase, electrophoretic mobility shift assay, enzyme-linked immunosorbent assay, real-time PCR, Northern blots, and immunofluorescence. Streptozotocin-induced diabetic rats were treated with the rho-kinase inhibitor fasudil, which was compared with enalapril, and functional and pathologic parameters were assessed. RESULTS: Glucose led to RhoA and downstream Rho-kinase activation. Mannitol was without effect. Activity of the transcription factor AP-1, increased in diabetic MCs and kidneys, is important in the profibrotic effects of glucose, and this was dependent on Rho-kinase signaling. Upregulation of fibronectin by glucose, shown to be mediated by activator protein-1 (AP-1), was prevented by Rho-kinase inhibition. RhoA siRNA and dominant-negative RhoA also markedly attenuated fibronectin upregulation by high glucose. Applicability of these findings were tested in vivo. Fasudil prevented glomerular fibronectin upregulation, glomerular sclerosis, and proteinuria in diabetic rats, with effectiveness similar to enalapril. CONCLUSIONS: High glucose activates RhoA/Rho-kinase in MCs, leading to downstream AP-1 activation and fibronectin induction. Inhibition of this pathway in vivo prevents the pathologic changes of diabetic nephropathy, supporting a potential role for inhibitors of RhoA/Rho in the treatment of diabetic renal disease.

Computer modeling technology to assess extracapsular tissue coverage of whole mount sections after retropubic and laparoscopic radical prostatectomy.

PURPOSE: The introduction of new surgical approaches to radical prostatectomy requires methodologies that permit valid comparison that are more expedient than long-term outcomes of biochemical local and distant failure and survival. We used a computer modeling program to assess the percent of extracapsular tissue coverage of prostate glands removed by the open retropubic and laparoscopic approaches. MATERIALS AND METHODS: Specimens were available for 15 and 17 patients who underwent open and laparoscopic radical prostatectomy, respectively. Serial whole mount sections were taken at 5 mm intervals. A genitourinary pathologist drew the contours of the prostate capsule on each tissue section. The whole mount was scanned to produce digital images. A software program was used to create a file with capsule information and a file with extraprostatic fibroadipose tissue information. Two separate point cloud files were generated to represent the capsule and extraprostatic models, and software algorithms were used to generate differences in the point clouds to quantify the extent of extracapsular tissue coverage. RESULTS: When separated into sides dissected by a nerve or nonnerve sparing technique, the overall percent of gland surface coverage by extracapsular fibroadipose tissue was statistically greater with laparoscopic dissection than with the open approach. When a segmental analysis of gland coverage was evaluated, a statistically greater percent of fibroadipose coverage was associated with laparoscopic dissection in the apical and inferolateral segments with nonnerve sparing, and in the apical segment with nerve sparing. CONCLUSIONS: This small radical prostatectomy series, analyzed by computer reconstruction as described, provides information suggesting that overall extracapsular tissue coverage is at least equal if not superior using the laparoscopic vs the open approach. This was specifically the case in areas of inferolateral and apical dissection with nonnerve sparing procedures and in areas of the apical dissection with nerve sparing procedures.