A pilot data analysis of a metabolomic HPLC-MS/MS study of patients with COPD

Chronic obstructive pulmonary disease (COPD) is a heterogeneous condition with multiple clinical faces. Metabolomic profiling studies small molecules present in biological samples by combined use of chromatography with mass spectrometry.

The goal of our work was to perform a high performance liquid chromatography combined with tandem mass spectrometry (HPLC-MS/MS) metabolomic study to compare the concentrations of metabolites in COPD patients and in controls.

Participants were recruited at the University Hospital, Hradec Králové, Czech Republic, with the approval of the ethics committee. The analysis of blood samples was performed at Health Sciences Center (HSC) in Kuwait. The blood samples were analyzed for concentrations of acylcarnitines and amino acids by high performance liquid chromatography (Waters 2690 HPLC; Waters, Milford, USA) and a triple-quadruple tandem mass spectrometer (Quattro LC, Micromass, Manchester, United Kingdom).

Groups of 10 subjects with COPD and 10 healthy controls were analyzed. Carnitine analysis showed that the free carnitine to acylcarnitine ratio (C0/AC ratio) was significantly lower in COPD (0.58 μM/L) compared to the controls (0.73 μM/L; p = 0.002). The mean C8/C2 ratio in the COPD group was significantly higher (0.03 μM/L) - in the control group it was 0 μM/L (p = 0.03). Amino acid analysis showed lower levels of phenylalanine in the COPD group (22.05 μM/L) compared to the controls (30.05 μM/L; p = 0.008). The alanine concentrations were significantly lower in the COPD group (173 μM/L) than in the control group (253 μM/L; p = 0.001). The pyroglutamate levels were higher in COPD (1.58 μM/L) than in the controls (1 μM/L; p = 0.040).

The carnitine and acylcarnitine levels in COPD subjects in this study possibly indicate a predisposition to atherosclerosis as a result of inadequate β-oxidation of fatty acids and show the presence of oxidative stress. Furthermore, the high sensitivity to changes in circulating amino acid levels may allow us to detect subclinical malnutrition and take early preventative interventions such as nutritional supplementation and patient education.