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Changes in transforming growth factor (TGF)-β and mothers against decapentaplegic homolog (Smad) expression in chronic asthmatic rats induced by ovalbumin and aluminum hydroxide


Zhu-Mei Sun
Fu-Feng Li
Peng Qian
Jie Zhao

Abstract

The aim of this study was to investigate the transforming growth factor (TGF)-β 1/mothers against decapentaplegic homolog (Smad) signaling pathway associated with airway reconstruction in chronic asthmatic rats by studying mRNA and protein expression. Twenty-four (24) Sprague-Dawley rats were randomly divided into two groups: a normal control group treated with 0.9% saline and an OVE+ALU group treated with a mixture of 10% ovalbumin and 10% aluminum hydroxide. Hematoxylin-eosin (HE) staining was used to observe the pathomorphological changes, and the locations of TGF-β and Smad 2, 4 and 7 were determined by immunohistochemistry. The mRNA expression of TGF-β and Smad 2, 4 and 7 was determined by real time-polymerase chain reaction (RT-PCR). The protein expression of TGF-β was determined by enzyme-linked immunosorbent assay (ELISA), whereas that of Smad 2, 4 and 7 was determined by western blotting. HE staining revealed that the OVE+ALU group displayed obvious signs of bleeding and expansion of lung alveolar and inflammatory cells. Immunofluorescence showed that TGF-β and Smad 2, 4 and 7 proteins were located in the bronchial wall or alveolar wall. RT-PCR showed that mRNA expression of Smad 2 was significantly higher in the OVE+ALU group than in the control group (P < 0.05) and that mRNA expression of Smad 7 was significantly lower in the OVE+ALU group than in the control group (P < 0.05). There was no significant difference in Smad 4 mRNA expression between the two groups (P > 0.05). Western blotting showed that TGF-β 1 and Smad 2 protein expression was significantly higher in the OVE+ALU group than in the control group (P < 0.05), whereas, in contrast, Smad 4 and 7 protein expression was significantly lower in the OVE+ALU group than in the control group (P < 0.05). The process of chronic asthma rats, TGF-β  and Smad 2, 4 and 7 expressions were changeable, thus the TGF-β/Smad signaling pathway may play a role in chronic asthma.

Keywords: Chronic asthma, Smad 2, 4 and 7, real time-polymerase chain reaction (RT-PCR)

African Journal of Biotechnology Vol. 11(29), pp. 7528-7534, 10 April, 2012

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