Chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) are two distinct subtypes of pulmonary hypertension (PH). Endothelial dysfunction is believed to be the main cause of the hyperproliferative and antiapoptotic phenotype in PH. The proposed metabolic shift in PAH is mainly characterized by increased glycolysis. It is unknown whether PAH and CTEPH share the same metabolic abnormalities. The aim of our study is to perform a systematic metabolic comparison of endothelial cells (ECs) derived from PAH and CTEPH patients.
ECs from three controls (human pulmonary artery endothelial cells, HPAECs), seven CTEPH and six PAH subjects were expanded until same passage. Metabolic targets were analysed by qRT-PCR and Western Blot. Viability and migration were studied using MTT and wound healing assay, respectively. Supernatants were assessed by EPOC Blood analysis (BGEM Test Cards). All values are shown as mean ± standard deviation. Group comparison was performed using one-way ANOVA (p<0.05 as statistically significant).
Gene and protein expression of key glycolytic enzymes were significantly upregulated in PAH-ECs compared to CTEPH-ECs and HPAECs. Also, mitochondrial enzymes, pentose phosphate pathway and glutamine metabolism related enzymes were upregulated in PAH-ECs compared to the CTEPH-ECs and HPAECs. Both PAH and CTEPH-ECs showed a significant higher viability compared to HPAECs. No statistically significant difference was found in migration ratios between CTEPH-ECs and PAH-ECs. Lower pH, CHCO3- and cTCO2 values, indicating acidification of the supernatant, were detected in both patients’ lines. Statistical higher glucose and lower lactate concentration in supernatant were shown in HPAECs compared to CTEPH-ECs and PAH-ECs.
The endothelial phenotype was found metabolically different in PAH and CTEPH indicating distinct pathogenic mechanisms in the development of the two PH subtypes. This creates the opportunity to specifically target the distinct metabolic abnormalities in both diseases.
Funding: Supported by grants H2020-Marie Skłodowska-Curie ITN (No. 675527), SEPAR (188/2013, 164/2016), SOCAP, FCHP, Fondo de Investigación Sanitaria (PI15/00582), O. Tura-Ceide was the recipient of Marie Curie Post-Doctoral Fellowship Award BIOTRACK: IDIBAPS and a Miguel Servet grant from the Instituto de Salud Carlos III (CP17/00114). The Netherlands CardioVascular Research Initiative grant (2012-08), The Netherlands Organization for Health Research and Development, and the Royal Netherlands Academy of Sciences