Enhanced vasoactive intestinal peptide signaling prevents the development of Duchenne muscular dystrophy-associated cardiomyopathy through inhibition of NF-κB signaling

Duchenne muscular dystrophy (DMD) is an X-linked recessive neuromuscular disorder caused by mutations in the dystrophin gene. Loss of dystrophin in cardiomyocytes leads to cell death, myocardial fibrosis, and ultimately, dilated cardiomyopathy. Vasoactive intestinal peptide (VIP) is a cardioprotective neuropeptide that signals through VPAC1 and VPAC2 receptors to activate cAMP-PKA signaling in cardiomyocytes. Elevated PKA activity in the heart may suppress NF-κB signaling, although the mechanism remains incompletely understood. Using physiological, histological, and molecular approaches, we evaluated whether PB1046, a long-acting VIP polymer developed by PhaseBio Inc., prevents cardiac dysfunction in mdx:Utrn+/- mice. Animals received PB1046 (0.75 or 1.5 mg/kg) or saline every other day from 4 to 12 weeks of age. Cardiac function was assessed weekly by echocardiography, and hearts were collected at 14 weeks of age for histological and molecular analyses. High-dose PB1046 treatment preserved cardiac function and reduced fibrosis in mdx:Utrn+/- mice. Bulk RNA sequencing analysis of cardiomyocytes isolated from mdx:Utrn+/- mice treated with high-dose PB1046 revealed an upregulation of cAMP-associated transcripts and a downregulation of NF-κB pathway genes. The activation of cAMP signaling was confirmed by elevated cardiac cAMP levels and increased phosphorylation of nuclear CREB in mdx:Utrn+/- mice treated with high-dose PB1046. Nuclear phosphorylation of p65 was significantly reduced, suggesting that NF-κB signaling was suppressed. Together, these results indicate that activation of VIP signaling protects against cardiac dysfunction in a murine model of DMD, likely through inhibition of NF-κB signaling pathways.