Insulin-Like Growth Factors and IGF-Binding Proteins levels in serum from smokers and patients with different grades of COPD, COPD and lung cancer and exacerbated COPD

Abstract

Context: Members of the insulin-like growth factor (IGF) system, including IGF1 and 2 and IGF binding proteins (IGFBPs), are involved in lung homeostasis and respiratory diseases, including COPD.

Aim: To compare levels of IGF components in serum between groups of patients with different COPD status, smoking habit and controls.

Methods: Serum levels of IGF1 and IGF2, and IGFBP2 to 5, measured by ELISA and immunoblotting, were compared between seven groups of patients (n=200): healthy controls (n=30), smokers (n=30), mild-COPD (n=30), moderate-COPD (n=30), severe-COPD (n=23), COPD+lung cancer (n=21) and exacerbated-COPD (n=36).

Results: While IGF1 concentration was increased in smokers respect to controls and exacerbated-COPD patients, IGF2 was reduced in exacerbated-COPD respect to all groups, in COPD+lung cancer group respect to controls and smokers, and in severe-COPD respect to controls. IGFBP2 levels were elevated in both exacerbated-COPD, respect the rest of groups except COPD+lung cancer, and in COPD+lung cancer respect to controls, smokers and severe COPD. In contrast, IGFBP3 and IGFBP5 levels were reduced in exacerbated COPD with respect the rest of groups. The ratio fragmented/intact IGFBP3 was increased in smokers and exacerbated-COPD. Levels of IGFBP4 were significantly increased in COPD+lung cancer respect the rest of groups except smokers.

Conclusion: Serum levels of IGF components changed with COPD status. IGFBP2 and 3 showed opposed serum concentration profiles in COPD. While IGFBP4 was upregulated in COPD+lung cancer, variations in IGFs and IGBP2 and 3 levels were more marked in exacerbated-COPD.