Table 1.
Clinical characteristics of subjects.
Fig 1.
Platelets from Group 2 PH patients exhibit altered mitochondrial bioenergetics.
(A) Basal glycolytic rate, measured by ECAR in control (n = 20) and Group 2 PH (n = 20) subjects. (B) Representative platelet OCR profiles from a healthy control subject and a patient with Group 2 PH. (C) Quantification of individual components of the platelet OCR profile in control (n = 20) and Group 2 PH (n = 20) subjects. (D) Mitochondrial superoxide production, measured by MitoSOX fluorescence, in control (n = 12) and Group 2 PH (n = 17) platelets. (E) % activated platelets, as measured by CD62 positivity, in control (n = 11) and Group 2 PH (n = 10) subjects. (F) Enzymatic activity (fold change of control) of mitochondrial complexes (Cx) I, II, IV, and citrate synthase (CS) from control (n = 5–7) and Group 2 PH (n = 5–11) subjects. Data are mean ± SEM. Unpaired 2-tailed t-test was used to compare groups.***p < 0.001, **p < 0.01, #p < 0.1.
Fig 2.
Fatty acid and glucose oxidation contribute to enhanced OCR in Group 2 PH Platelets.
(A) Maximal OCR in platelets from Group 2 PH subjects (n = 6) untreated and treated with etomoxir or 2-deoxyglucose (2DG). Paired 2-tailed t-test was used to compare groups. (B) Representative western blots for integrin αIIβ, CPT1, and PDK1 in platelets from control and Group 2 PH subjects. (C) Quantification of CPT1/integrin αIIβ protein expression in platelets from control (n = 4) and Group 2 PH (n = 4) patients. Data are mean ± SEM. Unpaired 2-tailed t-test used to compare groups. (D) Enzymatic activity of platelet CPT1 in control (n = 9) and Group 2 PH (n = 11) subjects. Data are mean ± SEM. Unpaired 2-tailed t-test used to compare groups. (E) Quantification of PDK1/integrin αIIβ protein expression in platelets from control (n = 4) and Group 2 PH (n = 4) patients. Data are mean ± SEM. Unpaired 2-tailed t-test was used to compare groups. *p < 0.05.
Fig 3.
Group 2 PH platelet bioenergetics correlates with RV dysfunction.
Pearson’s correlation of platelet reserve oxygen consumption rate with (A) pulmonary vascular resistance (PVR), (B) mean pulmonary artery pressure (mPAP), (C) right ventricular stroke work index (RV SWI), (D) body mass index (BMI). (E) Platelet reserve oxygen consumption rate in subject with and without diabetes mellitus (DM). Data are mean ± SEM. Unpaired 2-tailed t-test used to compare groups, #p < 0.1.
Table 2.
Degree of precapillary PH does not affect WHO Group 2 PH platelet bioenergetics.
Fig 4.
Nitrite does not affect Group 2 PH platelet respiration.
(A) Quantification of individual components of the platelet OCR profile in Group 2 PH patients (n = 16) at baseline and after inhaled nitrite. Data are mean ± SEM. (B) Enzymatic activity (fold change of control) of mitochondrial complexes (Cx) I, II, IV, and citrate synthase (CS) from Group 2 PH platelets (n = 6–12) at baseline and after inhaled nitrite. Data are mean ± SEM. One-way ANOVA was used to compare groups. (C) Enzymatic activity of CPT1 in Group 2 PH platelets (n = 9) at baseline and after inhaled nitrite. (D) Platelet activation, as measured by CD62 positivity in Group 2 PH platelets (n = 17) at baseline and after inhaled nitrite. One-way ANOVA was used to compare groups. #p < 0.1, *p < 0.05, **p < 0.01.