Group 3 PH PASMCs exhibited reduced aconitase and metabolic reprogramming, and silencing aconitase in control cells enhanced basal respiration and antioxidant response.
Decreased aconitase levels in Group 3 pulmonary hypertension PASMCs drive metabolic reprogramming and redox imbalance, highlighting mitochondrial function as a potential therapeutic target.
Abstract Rationale Pulmonary hypertension (PH) is characterized by vascular remodeling, increased pulmonary resistance, right ventricular hypertrophy, and high mortality. Our recent retrospective study in a veteran cohort revealed that patients with PH and chronic lung disease (Group 3 PH) exhibited poorer survival compared to some of the other groups of PH. Emerging literature indicates that pulmonary artery smooth muscle cells (PASMCs) from Group 3 PH patients exhibit metabolic reprogramming, increased oxidative stress, a hyperproliferative phenotype, and resistance to apoptosis. However, the underlying mechanisms and the specific role of oxidative stress in these PASMCs remain unclear. Hypothesis: We hypothesize that changes in aconitase, a TCA cycle enzyme and mitochondrial redox sensor, and increases in oxidative stress are crucial for inducing redox imbalance, driving metabolic reprogramming, and promoting hyperproliferation in Group 3 PH PASMCs. Methods Human PASMCs from idiopathic pulmonary fibrosis-associated PH (IPF-PH) patients and non-diseased controls were analyzed for redox imbalance, metabolic reprogramming, and proliferation using biochemical assays. Mitochondrial and glycolytic profiles were assessed with an extracellular flux analyzer, while redox balance and mitochondrial function were evaluated through fluorescent microscopy and high-performance liquid chromatography. Enzyme gene and protein levels, including aconitase, glutathione peroxidase 4 (GPX4), and manganese superoxide dismutase (MnSOD), were measured via RT-PCR and Western blot. Results Group 3 PH PASMCs demonstrated elevated lactate dehydrogenase, reduced aconitase, and increased MnSOD levels, indicating metabolic reprogramming with heightened redox imbalance affecting mitochondrial bioenergetics. Silencing aconitase in control PASMCs resulted in enhanced basal and ATP-dependent respiration, increased lipid peroxidation, and elevated antioxidant response. These alterations did not perturb mitochondrial membrane potential or cellular redox couples. Conclusions These findings highlight the critical roles of redox imbalance and altered mitochondrial function of enzymes, such as aconitase. In modeling these perturbations using in vitro cellular tools, we determined that decreased levels of aconitase regulate mitochondrial function and increase antioxidant response. These results also provide additional support for the critical role of mitochondria in Group 3 PH PASMC regulation and identify them as a potential therapeutic target in the treatment of Group 3 pulmonary hypertension. This abstract is funded by: US Department of Veterans Affairs; NIH
Smith et al. (Fri,) conducted a other in Group 3 Pulmonary Hypertension. Aconitase silencing vs. Non-diseased controls was evaluated on Redox balance, metabolic reprogramming, and proliferation. Group 3 PH PASMCs exhibited reduced aconitase and metabolic reprogramming, and silencing aconitase in control cells enhanced basal respiration and antioxidant response.