Abstract 18653: MiR-223 Improves Experimental Pulmonary Arterial Hypertension
Background: We reported that pulmonary arterial hypertension (PAH) is associated with increased activation of Poly(ADP-ribose) polymerase-1 (PARP-1) and transcription factor STAT3 within the pulmonary arterial smooth muscle cells (PASMC). PARP-1/STAT3 are common denominators to numerous pathways implicated in PAH including inflammation, Warburg effect, DNA repair, proliferation and apoptosis; thus PARP-1/STAT3 activation can eventually lead to PAH. Despite extensive research, PARP-1/STAT3 activation mechanism remains elusive. Micro-RNAs are non-coding small RNA implicated in PAH etiology, in sillico analysis revealed that an interaction between the transcription factor CEBPα and miR-233 is likely implicated in PARP-1/STAT3 activation. We hypothesized that miR-223 is downregulated in PAH contributing to PARP-1/STAT3 activation and thus to PAH development.
Methods and Results: Using qRT-PCR, we demonstrated that miR-223 is significantly (p<0.05) decreased in human PAH lungs, distal pulmonary arteries (<800μm) and cultured PAH PASMCs compared to control donors (n=11 patients). This downregulation was also observed in lungs of both monocrotaline- and sugen-induced PAH rat models (n=8; p<0.05). Downregulation of miR-223 was associated with increased phosphorylation and subsequent inactivation of CEBPα, a transcription factor known to regulate miR-223. In vitro, miR-223 reverses the PAH phenotype by decreasing PARP-1 expression (immunoblot and qRT-PCR; p<0.05), proliferation (Ki67; p<0.05) and also by increasing DNA damage (γH2AX immunofluorescence p<0.05) and apoptosis (TUNEL; p<0.05) in PAH-PASMCs. In vivo, miR-223 nebulization in rats with established monocrotaline-induced PAH improves pulmonary vascular resistance, and cardiac output measured by closed-chest right heart catheterization (n=6 per group; p<0.05).
Conclusion: We provide preliminary evidences of the implication of a CEBPα/miR-223 axis in PAH etiology, and its likely implication in the activation of PARP-1 signaling known to regulate DNA damage repair, as well as PASMC proliferation and resistance to apoptosis. Moreover, we demonstrated the therapeutic impact of miR-223 in the monocrotaline-induced PAH model.
Author Disclosures: J. Vinck: None. J. Meloche: None. V. Tremblay: None. S. Breuils-Bonnet: None. P. Ferraro: None. S. Provencher: None. S. Bonnet: Research Grant; Modest; Bayer. Other Research Support; Modest; actellion. Honoraria; Modest; Merck.
- © 2014 by American Heart Association, Inc.