TY - JOUR
T1 - Insulin-Like Growth Factor Bioactivity, Stanniocalcin-2, Pregnancy-Associated Plasma Protein-A, and IGF-Binding Protein-4 in Pleural Fluid and Serum From Patients With Pulmonary Disease
AU - Espelund, Ulrick Skipper
AU - Bjerre, Mette
AU - Hjortebjerg, Rikke
AU - Rasmussen, Torben Riis
AU - Lundby, Anders
AU - Hoeflich, Andreas
AU - Folkersen, Birgitte Holst
AU - Oxvig, Claus
AU - Frystyk, Jan
PY - 2017/9/1
Y1 - 2017/9/1
N2 - Context: Members of the insulin-like growth factor (IGF) system are primarily produced in the liver and secreted into the circulation, but they are also produced, recruited, and activated locally in tissues. Objective: To compare activity and concentrations of IGF system components in pleural fluid and blood. Design: Pathological pleural fluid, secondary to lung cancer or nonmalignant disease, and matching blood samples were collected from 24 patients ages 66.7 to 81.9 years. Methods: IGF-related proteins and cytokine levels were measured by immunoassays or immunoblotting. Bioactive IGF was measured by an IGF-1 receptor phosphorylation assay. Results: Total IGF-1 concentration did not differ between the compartments, but concentrations of free IGF-1 and bioactive IGF were more than threefold higher in pleural fluid than in corresponding serum samples (P = 0.0004), regardless of etiology. Median pregnancy-associated plasma protein-A (PAPP-A) and interleukin (IL)-6 levels were increased 47-fold and 143-fold, respectively, in pleural fluid compared with plasma (P , 0.0001). PAPP-A and IL-6 concentrations correlated positively (r = 0.46; P = 0.02). In pleural fluid, levels of PAPP-A-generated IGF binding protein-4 fragments correlated inversely with that of stanniocalcin-2 (r # 20.42; P # 0.05), a PAPP-A inhibitor; such correlations were absent in plasma. Conclusion: Pathological pleural fluid is characterized by increased in vitro IGF bioactivity and elevated concentrations of PAPP-A, an IGF-activating proteinase. Thus, the tissue activity of the IGF system may differ substantially from that of the circulating IGF system. The correlation between IL-6 and PAPP-A indicates that inflammation plays a role in promoting local tissue IGF activity.
AB - Context: Members of the insulin-like growth factor (IGF) system are primarily produced in the liver and secreted into the circulation, but they are also produced, recruited, and activated locally in tissues. Objective: To compare activity and concentrations of IGF system components in pleural fluid and blood. Design: Pathological pleural fluid, secondary to lung cancer or nonmalignant disease, and matching blood samples were collected from 24 patients ages 66.7 to 81.9 years. Methods: IGF-related proteins and cytokine levels were measured by immunoassays or immunoblotting. Bioactive IGF was measured by an IGF-1 receptor phosphorylation assay. Results: Total IGF-1 concentration did not differ between the compartments, but concentrations of free IGF-1 and bioactive IGF were more than threefold higher in pleural fluid than in corresponding serum samples (P = 0.0004), regardless of etiology. Median pregnancy-associated plasma protein-A (PAPP-A) and interleukin (IL)-6 levels were increased 47-fold and 143-fold, respectively, in pleural fluid compared with plasma (P , 0.0001). PAPP-A and IL-6 concentrations correlated positively (r = 0.46; P = 0.02). In pleural fluid, levels of PAPP-A-generated IGF binding protein-4 fragments correlated inversely with that of stanniocalcin-2 (r # 20.42; P # 0.05), a PAPP-A inhibitor; such correlations were absent in plasma. Conclusion: Pathological pleural fluid is characterized by increased in vitro IGF bioactivity and elevated concentrations of PAPP-A, an IGF-activating proteinase. Thus, the tissue activity of the IGF system may differ substantially from that of the circulating IGF system. The correlation between IL-6 and PAPP-A indicates that inflammation plays a role in promoting local tissue IGF activity.
KW - Journal Article
UR - https://www.scopus.com/pages/publications/85031107500
U2 - 10.1210/jc.2017-00033
DO - 10.1210/jc.2017-00033
M3 - Journal article
C2 - 28911149
SN - 0021-972X
VL - 102
SP - 3526
EP - 3534
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
IS - 9
ER -