Second-hand smoke-induced cardiac fibrosis is related to the Fas death receptor apoptotic pathway without mitochondria-dependent pathway involvement in rats.
Exposure to environmental tobacco smoke has been epidemiologically linked to heart disease among nonsmokers. However, the molecular mechanism behind the pathogenesis of cardiac disease is unknown. In this study, we found that Wistar rats, exposed to tobacco cigarette smoke at doses of 5, 10, or 15 cigarettes for 30 min twice a day for 1 month, had a dose-dependently reduced heart weight to body weight ratio and enhanced interstitial fibrosis as identified by histopathologic analysis. The mRNA and activity of matrix metalloprotease-2 (MMP-2), representing the progress of cardiac remodeling, were also elevated in the heart. In addition, we used reverse-transcriptase polymerase chain reaction and Western blotting to demonstrate significantly increased levels of the apoptotic effecter caspase-3 in treated animal hearts. Dose-dependently elevated mRNA and protein levels of Fas, and promoted apoptotic initiator caspase-8 (active form), a molecule of a death-receptor-dependent pathway, coupled with unaltered or decreased levels of cytosolic cytochrome c and the apoptotic initiator caspase-9 (active form), molecules of mitochondria-dependent pathways, may be indicative of cardiac apoptosis, which is Fas death-receptor apoptotic-signaling dependent, but not mitochondria pathway dependent in rats exposed to second-hand smoke (SHS). With regard to the regulation of survival pathway, using dot blotting, we found cardiac insulin-like growth factor-1 (IGF-1) and IGF-1 receptor mRNA levels to be significantly increased, indicating that compensative effects of IGF-1 survival signaling could occur. In conclusion, we found that the effects of SHS on cardiomyocyte are mediated by the Fas death-receptor-dependent apoptotic pathway and might be related to the epidemiologic incidence of cardiac disease of SHS-exposed nonsmokers.
Kuo
Wei-Wen
WW
Department of Biological Science and Technology, China Medical University, Taichung, Taiwan.
Wu
Chieh-Hsi
CH
Lee
Shin-Da
SD
Lin
James A
JA
Chu
Chia-Yih
CY
Hwang
Jin-Ming
JM
Ueng
Kwo-Chang
KC
Chang
Mu-Hsin
MH
Yeh
Yu-Lan
YL
Wang
Chau-Jong
CJ
Liu
Jer-Yuh
JY
Huang
Chih-Yang
CY
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000235:genetics; D005355:Fibrosis / Q000201:enzymology / Q000209:etiology*; D006331:Heart Diseases / Q000201:enzymology / Q000209:etiology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D008297:Male; D008928:Mitochondria / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D017526:Receptor, IGF Type 1 / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D019014:fas Receptor / Q000502:physiology*
D012333:RNA, Messenger; D014028:Tobacco Smoke Pollution; D019014:fas Receptor; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases