Lipoprotein-associated phospholipase A2 predicts exercise tolerance in COPD patients

Abstract Background & aimsImpaired exercise tolerance is a clinical feature of chronic obstructive pulmonary disease (COPD) associated with disease progression and increased mortality. The 6-minute walk test (6MWT) is a reliable and widely used measure of exercise capacity. However, it is not commonly used in primary medical institutions because it requires a suitable venue and professional training. Developing a simple tool to assess exercise tolerance is important. Molecular biomarkers show potential for evaluating the clinical outcomes (mortality, exacerbation) of COPD patients. The aim of this study was to identify simple and effective biomarkers to predict poor exercise tolerance in COPD patients.MethodsTen genes were selected by weighted correlation network analysis and differentially expressed gene analysis. Validation in an independent dataset led to the identification of PLA2G7, which was verified as a potential biomarker in COPD by bioinformatics analysis. The concentration of lipoprotein-associated phospholipase A2 (Lp-PLA2), which is encoded by the PLA2G7 gene, was assessed by enzyme-linked immunosorbent assay in a prospective validation cohort. The predictive capacity of Lp-PLA2 for 6-minute walk distance (6MWD) < 350 m was assessed using the area under the receiver operating characteristic curve (AUC). Traditional clinical features and Lp-PLA2 levels were incorporated into a nomogram to build a predictive model for poor exercise tolerance.ResultsThe final cohort included 92 stable COPD patients and 16 healthy smokers. Lp-PLA2 was upregulated in COPD patients and increased along with GOLD stage. Lp-PLA2 level was significant correlated with FEV1/FVC, BMI, FFMI, CAT score, mMRC score, and 6MWD in COPD patients. The predictive efficacy of Lp-PLA2 level (AUC: 0.796) and the derived nomogram model (AUC: 0.884) for exercise tolerance was superior to that of the sit-to-stand test and traditional clinical features.ConclusionLp-PLA2 is a promising biomarker for COPD patients and is suitable for assessing exercise tolerance in clinical practice.