FK506 activates BMPR2, rescues endothelial dysfunction, and reverses pulmonary hypertension

Abstract

Dysfunctional bone morphogenetic protein receptor-2 (BMPR2) signaling is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). We used a transcriptional high-throughput luciferase reporter assay to screen 3,756 FDA-approved drugs and bioactive compounds for induction of BMPR2 signaling. The best response was achieved with FK506 (tacrolimus), via a dual mechanism of action as a calcineurin inhibitor that also binds FK-binding protein-12 (FKBP12), a repressor of BMP signaling. FK506 released FKBP12 from type I receptors activin receptor-like kinase 1 (ALK1), ALK2, and ALK3 and activated downstream SMAD1/5 and MAPK signaling and ID1 gene regulation in a manner superior to the calcineurin inhibitor cyclosporine and the FKBP12 ligand rapamycin. In pulmonary artery endothelial cells (ECs) from patients with idiopathic PAH, low-dose FK506 reversed dysfunctional BMPR2 signaling. In mice with conditional Bmpr2 deletion in ECs, low-dose FK506 prevented exaggerated chronic hypoxic PAH associated with induction of EC targets of BMP signaling, such as apelin. Low-dose FK506 also reversed severe PAH in rats with medial hypertrophy following monocrotaline and in rats with neointima formation following VEGF receptor blockade and chronic hypoxia. Our studies indicate that low-dose FK506 could be useful in the treatment of PAH. IntroductionIdiopathic pulmonary arterial hypertension (IPAH) is a rare disorder thought to develop following a genetic and/or environmental insult that triggers endothelial cell (EC) apoptosis, loss of distal vessels, and occlusive vascular remodeling (1). These pathological changes increase resistance to pulmonary flow and cause progressive right heart failure. Current therapies mainly include drugs with vasodilatory properties that improve cardiopulmonary function (2). However, the obliterative vascular pathology usually continues to progress (3), leaving heart-lung transplantation as the only option for many patients. Therefore, new approaches are needed that focus on activating cellular mechanisms to reverse vascular remodeling. One strategy could be to improve function of the bone morphogenetic protein receptor-2 (BMPR2) signaling pathway. Germline mutations causing loss of BMPR2 function are found in >80% of familial and approximately 20% of sporadic cases of IPAH (4, 5). Acquired somatic chromosomal abnormalities in the BMPR2 signaling pathway have also been described (6). The low penetrance of pulmonary arterial hypertension (PAH) found in nonaffected family members with a BMPR2 mutation has been attributed to a higher level of

RNA Sequencing Analysis Detection of a Novel Pathway of Endothelial Dysfunction in Pulmonary Arterial Hypertension

“…The new data suggest that optimizing BMPR2 receptor function (5,20) may allow for normalization of a wide range of targets. n Author disclosures are available with the text of this article at www.atsjournals.org.…”

“…RV hypertrophy was assessed as the weight of the RV relative to left ventricle (LV) plus septum. Lungs were perfused with normal saline and fixed for routine histology, and morphometric analysis performed as previously described (5). Mouse lung tissue sections were stained with fluorescent antibodies for von Willebrand factor and a-smooth muscle actin as previously described (20).…”

“…Several lines of evidence pinpoint the pulmonary arterial (PA) endothelium as playing a critical role in the pathogenesis of IPAH and pulmonary arterial hypertension (PAH) associated with other primary conditions (APAH). Pulmonary arterial ECs (PAEC) cultured from patients with PAH display impaired angiogenesis (2)(3)(4)(5), altered bioenergetics (6), and chromosomal/genetic instability not present in other cell types (7). These features influence PAH pathogenesis and the potential for reversibility of this condition.…”

“…Reduced BMPR2 expression and function is also described in patients with IPAH or with APAH who do not have a mutation (8). Loss of BMPR2 impairs PAEC survival (2)(3)(4)(5) and barrier function (11). Our previous studies demonstrated that BMPR2 signaling activates b-catenin/peroxisome proliferator-activated receptor (PPAR) g-mediated transcription of PAEC genes, such as apelin (3,4).…”

“…Our previous studies demonstrated that BMPR2 signaling activates b-catenin/peroxisome proliferator-activated receptor (PPAR) g-mediated transcription of PAEC genes, such as apelin (3,4). In PAH PAECs, we have shown that BMPR2 deficiency and the resultant reduction in apelin can lead to apoptosis, and an inability to form vascular networks and to control smooth muscle cell proliferation (4,5).…”