The mineralocorticoid receptor-p38MAPK-NFκB or ERK-Sp1 signal pathways mediate aldosterone-stimulated inflammatory and profibrotic responses in rat vascular smooth muscle cells.
OBJECTIVE
To explore the signalling pathways involved in aldosterone-induced inflammation and fibrosis in rat vascular smooth muscle cells (VSMCs).


METHODS
Using Western blotting and real-time RT-PCR, we investigated the effects of aldosterone on the expression of cyclooxygenase-2 (Cox-2) and IL-6, two important proinflammatory factors, and TGFβ1, a critical profibrotic factor, in VSMCs.


RESULTS
Aldosterone treatment significantly increased the expression of Cox-2 and IL-6 and activation of p38MAPK and NF-κB. The expression of both Cox-2 and IL-6 could be blocked by the mineralocorticoid receptor (MR) antagonist spironolactone and the p38MAPK inhibitor SB203580. Also, the rapid phosphorylation of p38MAPK could be suppressed by SB203580 but not by spironolactone, implicating in nongenomic effects of aldosterone. Similar to SB203580 and spironolactone, the NF-κB inhibitor α-p-tosyl-L-lysine chloromethyl ketone (TLCK) markedly attenuated expression of Cox-2, indicating that MR, p38MAPK and NF-κB are associated with aldosterone-induced inflammatory responses. Furthermore, aldosterone enhanced expression of TGFβ1 in rat VSMCs. This result may be related to activation of the MR/ERK-Sp1 signalling pathway because PD98059, an ERK1/2 inhibitor, significantly blocked the rapid phosphorylation of ERK1/2 and function of Sp1 and led to reduced expression of TGFβ1. Spironolactone was also shown to significantly inhibit TGFβ1 and Sp1 expression but not ERK1/2 phosphorylation.


CONCLUSIONS
These results suggest that aldosterone-induced inflammatory responses and fibrotic responses may be mediated by the MR/p38MAPK-NF-κB pathways and the MR/ERK-Sp1 pathways in VSMCs, respectively.
State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. zhucj@imm.ac.cn
Chuan-jiang
CJ
Zhu
Qing-qing
QQ
Wang
Jun-lan
JL
Zhou
Han-zhi
HZ
Liu
Fang
F
Hua
Hong-zheng
HZ
Yang
Zhuo-wei
ZW
Hu
D000450:Aldosterone / Q000276:immunology*; D000818:Animals; D002460:Cell Line; D002466:Cell Nucleolus / Q000276:immunology / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000276:immunology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000276:immunology*; D016328:NF-kappa B / Q000276:immunology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D051996:Transcription Factor RelA / Q000235:genetics / Q000276:immunology; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000276:immunology; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology*
D015850:Interleukin-6; D016328:NF-kappa B; D012333:RNA, Messenger; C498145:Rela protein, rat; D051996:Transcription Factor RelA; D053773:Transforming Growth Factor beta1; D000450:Aldosterone; D051546:Cyclooxygenase 2; D011494:Protein Kinases; C065999:Sp1 kinase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases