Background: The aim of this study was to define the involvement of some biomarkers in patients with chronic obstructive pulmonary disease (COPD) and pulmonary hypertension (PH), with particular attention to sub-groups with a PH that is "out of proportion" (OP).
Materials and methods: Patients with COPD without PH, with PH and marked airways obstruction, and with PH and mild airways obstruction were compared. Assays for human interleukin-6 (IL-6), leukotriene B4 (LTB4), vasoactive intestinal peptide (VIP), and endothelin-1 (ET-1) were performed on the blood samples taken during right heart catheterization (RHC) in a pulmonary artery.
Results: In all, 83 patients were enrolled and divided into three groups: 37 simple COPD (mean pulmonary artery pressure [mPAP] <25 mmHg) and 46 COPD with PH (mPAP ≥25 mmHg). Among the latter, those who had a mPAP ≥35 mmHg and forced expiratory volume in 1 sec [FEV1] ≥50% were classified as OP (7 patients). Patients with PH were older and had a body mass index (BMI) higher than the other groups; moreover, they had lower FEV1 and carbon monoxide diffusion (DLCO) values. A lower level of partial pressure of oxygen in arterial blood (PaO2) was observed in the group of OP patients. The levels of ET-1, IL-6, and LTB4 were similar in each group; VIP was higher in the OP patients than in simple COPD and was related to PAP.
Conclusions: In the patients with COPD and PH and in particular in the group of OP PH, VIP is significantly increased, probably to correct the imbalance between vasoconstrictor and vasodilatator mediators.