A TSP-1 functional fragment inhibits activation of latent transforming growth factor-beta1 derived from rat alveolar macrophage after bleomycin treatment.
The antineoplastic antibiotic, bleomycin, is known to induce a well-recognized model of lung fibrosis. Active transforming growth factor-beta1 (TGF-beta1) plays a key role in lung fibrosis induced by bleomycin, TSP-1 (thrombospondin-1) being critical to the activation of L (latent)-TGF-beta1 by virtue of an association of the TSP-1/L-TGF-beta1 complex with CD36, involving the sequence CSVTCG of the TSP-1 functional fragment. To observe the inhibitory effects of TSP-1 functional fragments, critical for CD36 binding, on the activation of L-TGF-beta1, we isolated alveolar macrophages from Wistar rat lungs 7 days after bleomycin administration (5mg/kg body weight) and cultured the cells with or without TSP-1 functional or control fragments. We observed a cell surface association of TGF-beta1 with CD36 by immunofluorescence and quantified the active and total TGF-beta1 by ELISA. The co-localization of CD36 with TGF-beta1, shown by a yellow fluorescence deriving from a mixture of the green and red of the two components, for the TSP-1 functional fragment groups was clearly less than that of the TSP-1 control fragment groups. The quantities and the percentages of active TGF-beta1 in the TSP-1 functional fragment groups were lower than those in the TSP-1 control fragment groups (P<0.05 or P<0.01). These findings suggest that TSP-1 functional fragments could inhibit the activation of L-TGF-beta1 secreted by activated alveolar macrophages through blocking the binding of TSP-1 to CD36.
Chen
Ying
Y
China Medical University, Shenyang, Liaoning, PR China.
Wang
Xin
X
Weng
Dong
D
Tao
Shasha
S
Lv
Lina
L
Chen
Jie
J
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity; D001761:Bleomycin / Q000633:toxicity; D018955:CD36 Antigens / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D019700:Thrombospondin 1 / Q000378:metabolism / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1 / Q000187:drug effects* / Q000378:metabolism
D000903:Antibiotics, Antineoplastic; D018955:CD36 Antigens; D010446:Peptide Fragments; D019700:Thrombospondin 1; D053773:Transforming Growth Factor beta1; C494028:cysteinyl-seryl-valyl-threonyl-cysteinyl-glycine; D001761:Bleomycin