Plasma E-selectin and C-C motif chemokine ligand 3 differentiate pulmonary arterial hypertension from other forms of pulmonary hypertension and healthy controls

Background Pulmonary arterial hypertension (PAH) is a progressive vasculopathy characterized by substantial diagnostic delays and high mortality. Inflammation and tumor necrosis factor (TNF) signaling pathways have been recognized in the development and progression of pulmonary vascular disease in PAH. Plasma biomarkers may facilitate earlier PAH diagnosis, clinical decisions, and improve outcome. Purpose To investigate the diagnostic potential of plasma proteins related to TNF and inflammation in PAH. Methods Plasma levels from two independent prospective cohorts (n=429) were assessed for 90 proteins and B-type natriuretic peptide (BNP) using proximity extension assays. Blood samples were collected at the time of diagnostic right heart catheterization. The Swedish discovery cohort (n=371) included patients with PAH (n=95), chronic thromboembolic pulmonary hypertension (CTEPH, n=54), heart failure with reduced (HFrEF-PH, n=62) and preserved ejection fraction with pulmonary hypertension (PH, HFpEF-PH, n=58), heart failure without PH (HF-non-PH, n=47), and 55 healthy cardiopulmonary controls. Plasma biomarkers of interest were further assessed in a Danish external validation cohort (n=58), comprising patients with PAH (n=39) and CTEPH (n=19). Results Among the 90 proteins initially assessed, plasma levels of E-selectin were highest in patients with PAH compared with all other groups, including healthy controls (false discovery rate<0.05, p<0.005). Plasma C-C motif chemokine ligand 3 (CCL3) levels were lowest in healthy controls vs CTEPH (p<0.00003), as well as lower in CTEPH compared with PAH, HFrEF-PH, and HFpEF-PH (p<0.005). In univariable analysis, plasma E-selectin differentiated PAH from all groups except CTEPH, with an area under the receiver operating characteristic curve (AUC) of 0.67 (p<0.00001), whereas CCL3 differentiated CTEPH from PAH (AUC: 0.63, p<0.0075). In multivariable logistic regression adjusted for age, sex, BNP, body surface area, and number of comorbidities, the combination of E-selectin and CCL3 using rank-based normalization of probabilities derived from logistic regression odds, identified PAH from all other study groups (AUC: 0.81, p<0.00001). In the Danish validation cohort, the adjusted multivariable model of E-selectin and CCL3 yielded a non-inferior AUC of 0.88 for identifying patients with PAH from the other groups (p<0.0001), Figure 1. Conclusions Among the different PH groups, plasma E-selectin levels were highest in PAH, whereas CCL3 levels were lowest in CTEPH. The combination of plasma E-selectin and CCL3 identified PAH from healthy controls, CTEPH, HFpEF-PH, HFrEF-PH and HF-non-PH, independent of demographic parameters and BNP. This dual biomarker panel may complement clinical decision-making and facilitate early recognition of PAH to improve patient outcomes.