Altered surfactant protein A gene expression and protein homeostasis in rats with emphysematous changes.
BACKGROUND
The decrease of surfactant protein (SP) secreted by the alveolar type II cell is one of the important causes of limiting air of pulmonary emphysema. However, the SP-A gene and protein changes in this disease are rarely studied. This study was undertaken to investigate alterations in SP-A gene activity and protein, and to explore their roles in the pathogenesis of emphysematous changes.


METHODS
Twenty Wistar rats were divided randomly into a normal control group (n = 10) and a cigarette smoking (CS) + lipopolysaccharide (LPS) group (n = 10). Ultra-structural changes were observed under an electron microscope. The number of cells positive for SP-A was measured by immunohistochemistry. The mRNA expression and protein level of SP-A in the lung tissues were determined by quantitative polymerase chain reaction (qPCR) and Western blot separately. The protein level of SP-A in lavage fluid was determined by Western blot.


RESULTS
The number of cells positive for SP-A of the CS + LPS group (0.35 +/- 0.03) was lower than that of the blank control group (0.72 +/- 0.06, P < 0.05). The level of SP-A in the lung tissues of rats in the CS + LPS group (0.2765 +/- 0.0890) was lower than that in the blank control group (0.6875 +/- 0.1578, P < 0.05). The level of SP-A in the lavage fluid of rats in the CS + LPS group (0.8567 +/- 0.1458) was lower than that in the blank control group (1.3541 +/- 0.2475, P < 0.05). The lung tissues of rats in the CS + LPS group showed an approximate increase (0.4-fold) in SP-A mRNA levels relative to beta-actin mRNA (P < 0.05).


CONCLUSIONS
The changes of SP-A may be related to emphysematous changes in the lung. And cigarette smoke and LPS alter lung SP-A gene activity and protein homeostasis.
Hu
Qiong-jie
QJ
Department of Respiratory Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Xiong
Sheng-dao
SD
Zhang
Hui-lan
HL
Shi
Xue-mei
XM
Xu
Yong-jian
YJ
Zhang
Zhen-xiang
ZX
Zhen
Guo-hua
GH
Zhao
Jian-ping
JP
D000818:Animals; D015153:Blotting, Western; D004646:Emphysema / Q000378:metabolism* / Q000473:pathology; D006706:Homeostasis; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D016133:Polymerase Chain Reaction; D037662:Pulmonary Surfactant-Associated Protein A / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar
D037662:Pulmonary Surfactant-Associated Protein A; D012333:RNA, Messenger