Vascular-specific growth factor mRNA levels in the human diaphragm.

Background: Angiogenesis is an adaptation mechanism of skeletal muscles to increased load. Animal data have shown increased vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and transforming growth factor-beta(1) (TGF-beta(1)) mRNA levels in the diaphragm as a result of increased minute ventilation, but there are no data concerning the human diaphragm.

Objectives: The purpose of this study was to investigate the VEGF, bFGF, TGF-beta(1) mRNA levels in the human diaphragm of normal subjects and patients with altered respiratory mechanics.

Methods: We studied 9 patients with chronic obstructive pulmonary disease (COPD), 4 obese patients and 12 controls. We performed multiplex semiquantitative reverse transcription polymerase chain reaction to determine the VEGF, bFGF and TGF-beta(1) mRNA levels in specimens taken from their diaphragm.

Results: VEGF mRNA levels were 18% higher in COPD patients compared with controls (p = 0.04), while for the obese patients, these levels were not statistically significantly different. bFGF and TGF-beta(1) mRNA levels in COPD patients or obese individuals compared with controls did not differ significantly either.

Conclusions: The results of our study showed that TGF-beta(1), VEGF and bFGF mRNA was detected in the human diaphragm. The VEGF levels were higher in COPD patients than in normal subjects. This upregulation of VEGF may suggest an enhancement of angiogenesis in the diaphragm in COPD patients.