Abstract 566: Angiotensin II Promotes Proliferation and Fibrosis in Parietal Epithelial Cells Contributing to the Development of Crescentic Glomerulonephritis
Introduction: Parietal epithelial cells (PECs) contribute to the glomerular crescent formation of crescentic glomerulonephritis. Co-cultured model consisting of mesangial cells (MCs), PECs, and macrophages which play a pivotal role in the development of crescentic glomerulonephritis showed an increase in Angiotensin (Ang) II-induced cell proliferation and collagen secretion in PECs. Moreover, Ang II type 1 receptor blocker (ARB) treatment completely prevented an increase in cell proliferation and collagen secretion in PECs under the co-cultured model. However, it is not clear whether Ang II directly promotes PEC fibrosis and proliferation under the monoculture in PECs.
Aim: The aim of present study is to demonstrate that Ang II stimulation directly affects PEC proliferation and fibrosis.
Methods: Primary fluorescein isothiocyanate (FITC)-labeled PEC population was collected from glomeruli in rats using high-speed cell sorter. ERK1/2 phosphorylation was evaluated by Western blotting. Cell proliferation ability was measured by water-soluble tetrazolium salts (WST)-1 and the soluble collagen levels in culture supernatants was determined by the Sircol collagen assay.
Results: FITC-labeled PECs could be identified as a distinct cell population by high-speed cell sorter. The ERK 1/2 phosphorylation in PECs was stimulated by Ang II (100 nmol/l) by about 1.7-fold. After the treatment with 100 nmol/l Ang II for 24 hrs, cell proliferation ability significantly increased in PECs (mean ± SEM: 1.60 ± 0.03 vs. 1.00 ± 0.04, relative ratio). However, the proliferation ability in Ang II-stimulated PECs was suppressed by Ang II plus 10 nmol/l olmesartan (an ARB) or Ang II plus 100 nmol/l PD98059 (a MEK inhibitor). PECs also promoted a collagen secretion after the stimulation by 100 nmol/l Ang II for 24 hrs (52.1 ± 8.1 vs. 16.8 ± 2.4 μg/ml). Furthermore, the significant decrease in soluble collagen secretion was observed by the treatments with Ang II plus 10 nmol/l olmesartan or Ang II plus 10 μg/ml pan-specific neutralizing TGF-β antibody.
Conclusion: These data indicate that Ang II-stimulated PECs promote proliferation and fibrosis and may suggest contributing to the development of crescentic glomerulonephritis by PECs independently from MCs or macrophages.
- © 2013 by American Heart Association, Inc.