Blockade of advanced glycation end product formation attenuates bleomycin-induced pulmonary fibrosis in rats.
BACKGROUND
Advanced glycation end products (AGEs) have been proposed to be involved in pulmonary fibrosis, but its role in this process has not been fully understood. To investigate the role of AGE formation in pulmonary fibrosis, we used a bleomycin (BLM)-stimulated rat model treated with aminoguanidine (AG), a crosslink inhibitor of AGE formation.


METHODS
Rats were intratracheally instilled with BLM (5 mg/kg) and orally administered with AG (40, 80, 120 mg/kg) once daily for two weeks. AGEs level in lung tissue was determined by ELISA and pulmonary fibrosis was evaluated by Ashcroft score and hydroxyproline assay. The expression of heat shock protein 47 (HSP47), a collagen specific molecular chaperone, was measured with RT-PCR and Western blot. Moreover, TGFbeta1 and its downstream Smad proteins were analyzed by Western blot.


RESULTS
AGEs level in rat lungs, as well as lung hydroxyproline content and Ashcroft score, was significantly enhanced by BLM stimulation, which was abrogated by AG treatment. BLM significantly increased the expression of HSP47 mRNA and protein in lung tissues, and AG treatment markedly decreased BLM-induced HSP47 expression in a dose-dependent manner (p < 0.05). In addition, AG dose-dependently downregulated BLM-stimulated overexpressions of TGFbeta1, phosphorylated (p)-Smad2 and p-Smad3 protein in lung tissues.


CONCLUSIONS
These findings suggest AGE formation may participate in the process of BLM-induced pulmonary fibrosis, and blockade of AGE formation by AG treatment attenuates BLM-induced pulmonary fibrosis in rats, which is implicated in inhibition of HSP47 expression and TGFbeta/Smads signaling.
Chen
Lei
L
Division of Pulmonary Diseases, State Key Laboratory of Biotherapy of China, West China Hospital, West China School of Medicine, Sichuan University, Chengdu, Sichuan 610041, PR China. resalex@126.com
Wang
Tao
T
Wang
Xun
X
Sun
Bei-Bei
BB
Li
Ji-Qiong
JQ
Liu
Dai-Shun
DS
Zhang
Shang-Fu
SF
Liu
Lin
L
Xu
Dan
D
Chen
Ya-Juan
YJ
Wen
Fu-Qiang
FQ
D000818:Animals; D000964:Antimetabolites, Antineoplastic; D001761:Bleomycin; D015153:Blotting, Western; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D017127:Glycation End Products, Advanced / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D006146:Guanidines / Q000494:pharmacology*; D050958:HSP47 Heat-Shock Proteins / Q000096:biosynthesis; D006909:Hydroxyproline / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D011658:Pulmonary Fibrosis / Q000139:chemically induced* / Q000473:pathology / Q000517:prevention & control*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics
D000964:Antimetabolites, Antineoplastic; D004791:Enzyme Inhibitors; D017127:Glycation End Products, Advanced; D006146:Guanidines; D050958:HSP47 Heat-Shock Proteins; D012333:RNA, Messenger; D051899:Smad2 Protein; C497784:Smad2 protein, rat; D051900:Smad3 Protein; C497787:Smad3 protein, rat; D016212:Transforming Growth Factor beta; D001761:Bleomycin; D006909:Hydroxyproline; C004479:pimagedine