Transcriptomic Profiling of the Sex-linked Biological Pathways of Severe Pulmonary Arterial Hypertension associated with Endothelial Cell Caveolin-1 Depletion and Chronic Hypoxia

Pulmonary arterial hypertension (PAH) is distinguished by elevated blood pressure and vascular resistance in the arteries of the lungs. Patients with PAH demonstrate pulmonary vascular remodeling, wall thickening, and a high rate of morbidity due to right heart failure. Notably, while female patients are more likely to develop PAH, male patients suffer from higher morbidity rates after diagnosis. The molecular mechanism(s) underlying PAH development is poorly understood, though heritable PAH linked to mutations in bone morphogenic protein receptor 2 (BMPR2) and caveolin-1 (CAV1) may provide novel insights into the disease’s pathophysiology. To interrogate this dynamic, we utilized a global CAV1 knockout (CAV1-KO) mouse model (CAV1-/-) in conjunction with chronic hypoxia to induce symptoms of PAH as demonstrated by hemodynamic and ECHO cardiography recordings. Both female and male CAV1-/- mice in chronic hypoxia demonstrated elevated right ventricular systolic pressure (RVSP) of 48.49mmHg and 47.78mmHg respectively. Female knockout mice started to die earlier in hypoxic conditions (4 wks), though male mice showed greater total mortality by the end of the 8 wks of hypoxia. In addition to wildtype controls, we compared this knockout mouse to endothelial-specific CAV1 reconstituted (CAV1-RC) knockouts and found that restoration of CAV1 expression only in endothelial cells (ECs) is sufficient to ameliorate PAH symptoms, highlighting the importance of vascular CAV1 in maintaining pulmonary artery function. RNA-sequencing of the lungs revealed that CAV1-/- is associated with downregulation of biological process gene pathways involved in cilium assembly in normoxic conditions for both sexes. In hypoxic conditions, CAV1 knockout in females leads to downregulation of BMP signaling, while male hypoxic CAV1-/- led to a significant increase in muscle cell development genes. Reconstitution of CAV1 in ECs lead to upregulation of immune signaling pathways, muscle cell development, and various cell differentiation pathways in both sexes. Females showed a unique upregulation of cilia-related pathways, while males demonstrated increased BMP signaling. These data indicate that muscle cell development, angiogenesis, cilia assembly, immune response, and BMP signaling pathways undergo sex-specific transcriptional regulation during PH development that may underlie sex differences in PH patient outcome.