Insulin-like growth factors and their binding proteins in pleural fluid.
We investigated the expression and potential regulatory role of insulin-like growth factors (IGFs) and their specific binding proteins (BPs) in tuberculous and nontuberculous pleuritis. By using a radioimmunoassay after acid gel filtration chromatography, we found that mean concentrations of IGF-I were 211.9 +/- 20.2 microg/l and 203.2 +/- 31.1 microg/l in pleural fluid of 14 patients with tuberculous pleuritis and 9 patients with malignant pleuritis respectively. These values were near those in serum of the same patients (221.3 +/- 19.5 microg/l and 204.6 +/- 21.0 microg/l respectively). By using a specific protein-binding assay, we found that mean concentrations of IGF-II were 345.3 +/- 61.0 microg/l and 167.6 +/- 22.7 microg/l in tuberculous and malignant pleural effusions respectively. These values were significantly lower than those in serum of the same patients (628.3 +/- 79.0 microg/l, P<0.025 and 532.0 +/- 85.9 microg/l, P<0.025 respectively). Because bioavailability and bioactivity of IGFs may be regulated by their binding to IGFBPs, we studied IGFBP patterns in the pleural fluid of 6 patients with tuberculous pleuritis. As assessed by Western ligand blotting the levels of IGFBP-1 and IGFBP-2 were increased whereas those of IGFBP-3 were decreased in pleural fluid in comparison with serum. The decrease in IGFPB-3 levels reflected increased proteolysis, as assessed by Western immunoblotting. In spite of this presence of IGFBPs, IGFs could be responsible for the local biosynthesis of 1.25-dihydroxyvitamin D (1,25-(OH)2D) since pleural fluid levels of both IGF-I and IGF-II significantly correlated with those of 1,25-(OH)2D. These results indicate that IGFs are detectable in pleural fluid and may contribute to control the activity of 25-hydroxyvitamin D-1alpha hydroxylase in tuberculous pleuritis.
Le Bouc
Y
Y
Laboratoire de Physiologie, Hôpital Trousseau, Paris, France.
Bellocq
A
A
Philippe
C
C
Perin
L
L
Garabedian
M
M
Fouqueray
B
B
Zacharias
C
C
Cadranel
J
J
Baud
L
L
D000328:Adult; D001826:Body Fluids / Q000378:metabolism*; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000502:physiology; D007335:Insulin-Like Growth Factor II / Q000378:metabolism* / Q000502:physiology; D010994:Pleura / Q000378:metabolism*; D010998:Pleurisy / Q000382:microbiology* / Q000503:physiopathology*; D014376:Tuberculosis
D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II