Effect of aldosterone on epithelial-to-mesenchymal transition of human peritoneal mesothelial cells.
BACKGROUND
Peritoneal fibrosis is one of the major causes of technical failure in patients on peritoneal dialysis. Epithelial-to-mesenchymal transition (EMT) of the peritoneum is an early and reversible mechanism of peritoneal fibrosis. Human peritoneal mesothelial cells (HPMCs) have their own renin-angiotensin-aldosterone system (RAAS), however, it has not been investigated whether aldosterone, an end-product of the RAAS, induces EMT in HPMCs, and which mechanisms are responsible for aldosterone-induced EMT.


METHODS
EMT of HPMCs was evaluated by comparing the expression of epithelial cell marker, E-cadherin, and mesenchymal cell marker, α-smooth muscle actin after stimulation with aldosterone (1-100nM) or spironolactone. Activation of extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) and generation of reactive oxygen species (ROS) were assessed by western blotting and 2',7'-dichlorofluororescein diacetate staining, respectively. The effects of MAPK inhibitors or antioxidants (N-acetyl cysteine, apocynin, and rotenone) on aldosterone-induced EMT were evaluated.


RESULTS
Aldosterone induced EMT in cultured HPMCs, and spironolactone blocked aldosterone-induced EMT. Aldosterone induced activation of both ERK1/2 and p38 MAPK from 1 hour. Either PD98059, an inhibitor of ERK1/2, or SB20358, an inhibitor of p38 MAPK, attenuated aldosterone-induced EMT. Aldosterone induced ROS in HPMCs from 5 minutes, and antioxidant treatment ameliorated aldosterone-induced EMT. N-acetyl cysteine and apocynin alleviated activation of ERK and p38 MAPK.


CONCLUSIONS
Aldosterone induced EMT in HPMCs by acting through the mineralocorticoid receptor. Aldosterone-induced generation of ROS followed by activation of ERK, and p38 MAPK served as one of the mechanisms of aldosterone-induced EMT of HPMCs.
Department of Internal Medicine, Seonam Hospital, Seoul, Korea.
Mina
M
Yu
Department of Internal Medicine, Ewha Womans University School of Medicine, Ewha Medical Research Center, Seoul, Korea.
Hyun-Soo
HS
Shin
Department of Surgery, Ewha Womans University School of Medicine, Seoul, Korea.
Hyeon Kook
HK
Lee
Department of Internal Medicine, Ewha Womans University School of Medicine, Ewha Medical Research Center, Seoul, Korea.
Dong-Ryeol
DR
Ryu
Department of Internal Medicine, Ewha Womans University School of Medicine, Ewha Medical Research Center, Seoul, Korea.
Seung-Jung
SJ
Kim
Department of Internal Medicine, Ewha Womans University School of Medicine, Ewha Medical Research Center, Seoul, Korea.
Kyu-Bok
KB
Choi
Department of Internal Medicine, Ewha Womans University School of Medicine, Ewha Medical Research Center, Seoul, Korea.
Duk-Hee
DH
Kang
Aldosterone; Epithelial-to-mesenchymal transition; Mesothelial cell; Peritoneal dialysis; Peritoneal fibrosis