Introduction: Pulmonary hypertension (PH) is a devastating disease characterized by increased pulmonary arterial pressure, leading to right-heart failure and death. Accumulating evidence is showing increased levels of circulating cytokines, associated with poor prognosis, in PAH and CTEPH patients. Currently, it is unknown if these circulating cytokine levels are already elevated at diagnosis, and if different cytokine profiles are existing in different PAH subsets.
Our aim was to investigate circulating inflammatory biomarkers at diagnosis (treatment-naïve/baseline) and after 1-year follow-up in PAH-subsets and CTEPH patients.
Materials/Methods: Plasma samples from 50 PAH patients (16 idiopathic (I)PAH, 24 Connective Tissue Disease (CTD)-21 PAH and 10 Congenital Heart Disease(CHD)-PAH), 37 CTEPH patients and 18 healthy controls (HC) were measured at diagnosis (baseline) and in a subset of patients at 1-year follow-up for circulating inflammatory biomarkers (VEGF-A, TGF-β, CXCL-9, CXCL-13, interleukin (IL)-1β, IL-6, IL-8, IL-10) and were related to hemodynamic parameters.
Results: At baseline, plasma IL-6 concentrations were elevated in CTD-PAH, IL-10 was increased in IPAH, and TGF-β was significantly enhanced in IPAH and CHD-PAH patients compared to HC. CXCL-9 was elevated in patients (IPAH, CTD-PAH and CTEPH) compared to HC, whereas CXCL-13 was higher in CTD-PAH compared to controls and CTEPH patients. No differences were observed for VEGF-A, IL-31 1b and IL-8. In our cohort, no significant hemodynamic correlations were found between circulating cytokines and hemodynamic parameters at baseline. After 1-year follow-up, the concentrations of IL-8, 33 IL-10 and TGF- β increased significantly in paired samples from CTD-PAH patients.
Conclusion: Our findings indicate that different inflammatory profiles in PH exist at diagnosis, seemingly independent of WHO subgroup classification within PAH subsets and CTEPH. After 1-year of reatment, these inflammatory profiles differentially changed for each PH subgroup. Additional analyses are required to determine the prognostic and clinical implications of these results.