Desert hedgehog enhances endothelial resilience and prevents atherosclerosis by mitigating PAI-1 signaling

BACKGROUND

Atherosclerotic cardiovascular disease remains the leading cause of death worldwide. Most current pharmacotherapies target conventional risk factors that promote atherosclerosis (e.g., hyperlipidemia) rather than intrinsic resilience factors that protect against atherosclerosis in the face of risk factors. Here, we investigated the role of desert hedgehog ( DHH ), a canonical ligand of the hedgehog signaling pathway, as a novel resilience factor that restrains endothelial mesenchymal transition (EndoMT) and protects against atherosclerosis.

METHODS

Single-cell RNA sequencing (scRNA-seq) was performed on atheroprone and atheroprotective regions of the ApoE knockout mouse aorta to identify mechanoresponsive genes associated with atherosclerosis. Endothelial cell-specific Dhh knockout mice were subjected to partial carotid ligation and hypercholesterolemic conditions to investigate the role of endothelial Dhh in atherosclerosis progression. scRNA-seq, bulk RNA sequencing, endothelial lineage tracing, immunoprecipitation-coupled mass spectrometry, and surface plasmon resonance were used to in-vestigate the role and mechanism of DHH in EndoMT. Pharmacological interventions and recombinant DHH administration were performed in vivo to evaluate therapeutic potential of DHH targeting. DHH expression was also examined in human atherosclerotic arteries and serum samples from patients with coronary artery disease.

RESULTS

DHH protein expression was enriched in arterial endothelium from mice, porcine, and humans. However, DHH expression was significantly reduced in atherosclerotic arteries and serum from patients with coronary artery disease. scRNA-seq of atheroprone and atheroresistant region of mouse aorta identified Dhh as a novel mechanoresponsive gene enriched in aortic regions exposed to unidirectional laminar flow. Endothelial cell-specific Dhh knockout ( Dhh ^ecKO ) mice exhibited increased atherosclerotic lesion area, large necrotic cores, and reduced collagen content following partial carotid ligation. Similarly, under hypercholesterolemic conditions, both male and female Dhh ^ecKO mice showed aggravated atherosclerosis progression. scRNA-seq of Dhh ^ecKO mouse aortas revealed an increased proportion of endothelial cells undergoing mesenchymal transition, indicating enhanced EndoMT. These findings were corroborated by bulk RNA-sequencing of DHH depleted HUVECs and endothelial lineage tracing in inducible Dhh ^ecKO mice. Mechanistically, DHH directly interacted with plasminogen activator inhibitor type 1 (PAI-1) and suppressed PAI-1-induced EndoMT. PAI-1 promoted EndoMT in ECs through activation of canonical TGF-β signaling (SMAD2/3) and noncanonical AKT/ERK1/2 signaling via interaction with low-density lipoprotein receptor-related protein (LRP1). Neutralization of PAI-1 or inhibition of LRP1, AKT/ERK1/2, or SMAD3 signaling abolished DHH deficiency-induced EndoMT. DHH competitively inhibited PAI-1 binding to LRP1, thereby attenuating downstream pro-EndoMT signaling. Intriguingly, treatment with PAI-1 inhibitor TM5275 mitigated endothelial Dhh deficiency induced EndoMT in vivo . Of translational relevance, recombinant mouse DHH protein administration reduced atherosclerosis progression, stabilized plaque, and decreased the expression of EndoMT markers in ApoE knockout mice.

CONCLUSIONS

Desert hedgehog (DHH) is an intrinsic endothelial cell-enriched resilience factor that protects against EndoMT and atherosclerosis by preventing PAI-1 signaling. The present study implicates endothelial DHH as a potential therapeutic target for atherosclerotic cardiovascular disease.

Desert hedgehog (DHH) is an intrinsic endothelial cell-enriched resilience factor that protects against EndoMT and atherosclerosis by preventing PAI-1 binding to LRP1 and downstream AKT/ERK, as well as SMAD2/3 signaling.

Clinical Perspective