Introduction 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. Methods 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. Results Both female and male Cav1 -/- mice in chronic hypoxia demonstrated elevated right ventricular systolic pressure (RVSP) of 48.49 mmHg and 47.78 mmHg respectively. Female knockout mice began dying 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 bone morphogenetic protein (BMP) signaling, while male hypoxic Cav1 -/- led to a significant increase in muscle cell development genes. Reconstitution of Cav1 in ECs leads 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. Discussion These data indicate that muscle cell development, angiogenesis, cilia assembly, immune response, and BMP signaling pathways undergo sex-specific transcriptional regulation during PAH development that may underlie sex differences in PAH patient outcome.
Leasure et al. (Fri,) studied this question.