PROJECT SUMMARY/ABSTRACT
Pulmonary hypertension (PH) is common in left heart failure and is present in both heart failure with reduced
ejection fraction and heart failure with preserved ejection fraction (HFpEF). HFpEF afflicts approximately 32
million people globally with five year mortality and readmission rates estimated at 75.7% and 84%, respectively.
PH is present in 83% of patients with HFpEF (PH-HFpEF) and portends worse prognosis. PH-HFpEF is classified
in isolated post-capillary pulmonary hypertension (IpcPH) and combined pre- and post-capillary pulmonary
hypertension (CpcPH). Both forms are characterized by increased pulmonary artery mean and wedge pressures,
but the distinctive hallmark between the two is the presence of elevated pulmonary vascular resistance in CpcPH,
due to intrinsic pulmonary vasoconstriction and vascular remodeling. CpcPH confers increased mortality and
hospitalization risk compared to IpcPH. There are no proven or approved treatments for PH-HFpEF and finding
a treatment has been identified as an unmet need by the NHLBI. We published that mitochondria-derived reactive
oxygen species (mROS) produced by metabolic syndrome and maximal intensity exercise in CpcPH decrease
the expression of the nitric oxide receptor soluble guanylate cyclase subunit b1 (sGCb1) by downregulating the
expression of the sGC transcription factor Nuclear Factor Y subunit alpha (NFYa). Downregulation of sGC leads
to lower concentration of the vasodilatory cyclic guanosine monophosphate (cGMP) impairing pulmonary artery
vasodilation. Additionally, mROS decrease pulmonary artery smooth muscle cell (PASMC) apoptosis and
increase vascular tone by increasing intracellular calcium in PASMCs. The long-term objective of this proposal
is to test mitoquinol, a mitochondria-targeted antioxidant as treatment for CpcPH. Mitoquinol was chosen
because it is mitochondria specific, and safe for use in humans, allowing for translation of our findings. We
hypothesize that mitoquinol treatment of PASMCs from rats with CpcPH will decrease mROS formation and
rescue NFYa-sGC expression, increase apoptosis and decrease proliferation of PASMCs (Aim 1); and
mitoquinol treatment of a rat CpcPH model will decrease pulmonary artery pressures by decreasing mROS in
the smooth muscle cell layer of the pulmonary artery (Aim 2). Our lab has established cell culture models to
induce mROS and measure NFYa-sGC expression, cellular apoptosis and proliferation. In addition we developed
a CpcPH rat model and methods to measure pulmonary artery hemodynamics at rest and during exercise.
Cardiac evaluation will be supplemented using ultrasound. Completion of the proposed aims will identify mROS
as a therapeutic target for CpcPH and pave the way for clinical trial design since mitoquinol has been found safe
in humans. These outcomes, in addition to career development, mentored training, and didactic workshops, will
provide the primary investigator with the background knowledge, technical expertise, and leadership skills
necessary to proceed towards scientific independence as a physician-scientist. The objectives of this training
grant will be performed at the Vascular Medicine Institute of the University of Pittsburgh.
