RESUMO
OBJECTIVE: Silicosis, caused by inhalation of silica dust, is the most serious occupational disease in China and the aim of present study was to explore the protective effect of Ang (1-7) on silicotic fibrosis and myofibroblast differentiation induced by Ang II. METHODS: HOPE-MED 8050 exposure control apparatus was used to establish the rat silicosis model. Pathological changes and collagen deposition of the lung tissue were examined by H.E. and VG staining, respectively. The localizations of ACE2 and α-smooth muscle actin (α-SMA) in the lung were detected by immunohistochemistry. Expression levels of collagen type I, α-SMA, ACE2, and Mas in the lung tissue and fibroblasts were examined by western blot. Levels of ACE2, Ang (1-7), and Ang II in serum were determined by ELISA. Co-localization of ACE2 and α-SMA in fibroblasts was detected by immunofluorescence. RESULTS: Ang (1-7) induced pathological changes and enhanced collagen deposition in vivo. Ang (1-7) decreased the expressions of collagen type I and α-SMA and increased the expressions of ACE2 and Mas in the silicotic rat lung tissue and fibroblasts stimulated by Ang II. Ang (1-7) increased the levels of ACE2 and Ang (1-7) and decreased the level of Ang II in silicotic rat serum. A779 enhanced the protective effect of Ang (1-7) in fibroblasts stimulated by Ang II. CONCLUSION: Ang (1-7) exerted protective effect on silicotic fibrosis and myofibroblast differentiation induced by Ang II by regulating ACE2-Ang (1-7)-Mas axis.
Assuntos
Angiotensina II/sangue , Angiotensina I/uso terapêutico , Pulmão/metabolismo , Miofibroblastos/efeitos dos fármacos , Fragmentos de Peptídeos/uso terapêutico , Silicose/prevenção & controle , Actinas/metabolismo , Angiotensina I/sangue , Angiotensina I/farmacologia , Enzima de Conversão de Angiotensina 2 , Animais , Animais Recém-Nascidos , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Colágeno Tipo I/metabolismo , Modelos Animais de Doenças , Pulmão/patologia , Fragmentos de Peptídeos/sangue , Fragmentos de Peptídeos/farmacologia , Peptidil Dipeptidase A/metabolismo , Ratos Wistar , Silicose/metabolismo , Silicose/patologiaRESUMO
The dynamic variation of renin-angiotensin system (RAS) in silicosis remains unclear. Seventy Wistar rats were divided into 7 groups including control group, silicosis groups (inhaling SiO2 for 2, 4, 8, 16 and 24 weeks, respectively) and Captopril (Cap) group. Rat lung primary fibroblasts were divided into control group, SiO2-stimulated group (0, 0.5, 1, 3, 6, 12, 24 and 48 h) and Cap group. The silicotic nodules were formed and collagens were deposited gradually in silicosis group observed by haematoxylin and eosin (HE) staining and Van Gieson (VG) staining. Cap relieved the lung fibrosis and collagen deposition. Immunohistochemistry indicated the positive expression of α-smooth muscle actin (α-SMA) was increased gradually in silicotic rat lung tissue. Western blotting revealed the expression of collagen type I (Col I) and α-SMA was up-regulated in silicotic rat lung tissue and fibroblasts stimulated by SiO2. Cap decreased the expression of Col I and α-SMA in silicotic rat lung tissue and fibroblasts stimulated by SiO2. Western blotting also demonstrated the expression of angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT1) was increased, and the expression of ACE2 and Mas was decreased gradually in silicotic rat lung tissue and fibroblasts stimulated by SiO2. ELISA showed the serum levels of ACE and angiotensin II (Ang II) were also increased and ACE2 and Ang (1-7) were decreased in the silicosis group. Treatment with Cap decreased the expression levels of ACE, Ang II and AT1, and increased the expression levels of ACE2, Ang (1-7) and Mas. These findings suggested that an imbalance between ACE-Ang II-AT1 axis and ACE2-Ang (1-7)-Mas axis may participate in the development of silicosis.
Assuntos
Captopril/farmacologia , Peptidil Dipeptidase A/genética , Receptor Tipo 1 de Angiotensina/genética , Silicose/tratamento farmacológico , Actinas/genética , Angiotensina II/genética , Enzima de Conversão de Angiotensina 2 , Animais , Colágeno Tipo I/genética , Fibroblastos/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Pulmão/patologia , Cultura Primária de Células , Ratos , Ratos Wistar , Sistema Renina-Angiotensina , Dióxido de Silício/farmacologia , Silicose/genética , Silicose/patologiaRESUMO
Rhododendron dauricum L. is an ancient Chinese traditional herb. The pharmacological effects of R. dauricum extract have been shown in chronic tracheitis. The aim of this study was to investigate the cardiovascular effects of Rhododendron dauricum L. flavonoids (RF) on rats and its mechanisms. This study was performed in isolated vascular rings and a rat model of myocardial infarction and isolated myocytes. RF (0.5 - 4 mg/mL) induced a concentration-dependent relaxant effect on the phenylephrine (10(-5) M) and KCl (60 mM) contracted aortic rings, with or without intact endothelium. This effect was attenuated by pretreated with L-NAME (10(-5) M) and K(+) channel inhibitor 4 - AP (1 mM) and TEA (1 mM). The Ca(2+)-induced contraction and PE-induced contraction were obviously attenuated after pretreated with RF (2 mg/mL) for 30 min in Krebs solution, without Ca(2+), containing 10(-4) mol EGTA. KCl (60 mM) significantly increased the intracellular free Ca(2+) concentration ([Ca(2+)]i) and RF inhibited the changes induced by KCl in single cardiac myocytes. RF obviously prolonged the survival time of hypoxia mice pretreated with isoprenaline and reduced the myocardial infarction size in rat coronary artery ligation. These findings suggest that RF induces concentration-dependent vasodilation and myocardial preservation.