miR-224 orchestrates BMP and TGFβ signaling in pulmonary arterial hypertension, and its inhibition via aerosolized AAV1-ToughDecoy-miR-224 or chemically modified antisense oligonucleotides attenuated disease severity across multiple preclinical models, identifying miR-224 inhibition as a promising therapeutic strategy for PAH.
Key Findings
Results
miR-224 expression was elevated in the lungs of patients with PAH and across multiple experimental models of pulmonary hypertension.
Increased miR-224 expression was observed in human PAH lung tissue
Elevated expression was confirmed across mouse, rat, and pig experimental models of pulmonary hypertension
miR-224 was also upregulated in pulmonary arterial smooth muscle cells (PASMCs) isolated from patients with PAH
The consistent elevation across species and model types supports miR-224 as a conserved disease-associated signal
Results
In vitro overexpression of miR-224 was sufficient to induce PASMC proliferation.
miR-224 overexpression alone drove proliferation of pulmonary arterial smooth muscle cells without additional external stimuli
This finding established a causal role for miR-224 in promoting the cellular behavior central to pulmonary vascular remodeling
The result supports miR-224 as an upstream regulator rather than merely a downstream marker of PAH
Results
AAV1-mediated overexpression of miR-224 in vivo exacerbated PAH in mice.
Delivery of AAV1 vector driving miR-224 overexpression worsened pulmonary arterial hypertension phenotype in mice
This gain-of-function experiment confirmed the pathological role of miR-224 in vivo
The adeno-associated virus 1 (AAV1) serotype was used for lung-directed gene delivery
Results
Intratracheal delivery of aerosolized AAV1-ToughDecoy-miR-224 attenuated PAH severity in both Sugen/Hypoxia and monocrotaline models in mice and rats.
AAV1 vectors expressing ToughDecoy constructs designed to sequester and inhibit miR-224 were delivered via intratracheal aerosolization
Therapeutic benefit was demonstrated in the Sugen/Hypoxia (Su/Hx) mouse model and the monocrotaline model
Efficacy was shown across two species (mice and rats) and two mechanistically distinct PAH models
The aerosolized intratracheal route represents a clinically translatable, lung-targeted delivery approach
Results
A chemically modified antisense oligonucleotide targeting miR-224 (LNA-224) attenuated PAH disease severity in preclinical models.
LNA-224 is a locked nucleic acid (LNA)-based antisense oligonucleotide designed to inhibit miR-224
LNA-224 treatment reduced disease severity in Su/Hx and monocrotaline models in mice and rats
Chemically modified antisense oligonucleotides represent a pharmacologically tractable therapeutic modality distinct from gene therapy vectors
Results
SMC-specific inhibition of miR-224 via AAV1-ToughDecoy-miR-224 reversed pulmonary vascular remodeling and improved right ventricular function in the Su/Hx mouse model.
Smooth muscle cell-specific targeting was achieved using an AAV1 vector expressing ToughDecoy-miR-224
Both structural endpoints (pulmonary vascular remodeling reversal) and functional endpoints (right ventricular function improvement) were improved
The Su/Hx mouse model was used for this cell-type-specific intervention experiment
Results demonstrate that miR-224 inhibition specifically in SMCs is sufficient for therapeutic benefit
Results
miR-224 mechanistically targeted multiple components of the BMP/TGFβ signaling pathway, suppressing BMP/SMAD signaling and enhancing TGFβ-associated responses.
miR-224 was found to target multiple components of both the bone morphogenetic protein (BMP) and transforming growth factor-β (TGFβ) signaling pathways
The net effect of miR-224 activity was suppression of growth-inhibitory BMP/SMAD signaling
Inhibition of miR-224 restored the balance between BMP and TGFβ signaling in PASMCs
This dual mechanism explains how a single miRNA can dysregulate the BMP/TGFβ axis that is central to PAH pathogenesis
What This Means
Pulmonary arterial hypertension (PAH) is a serious disease where the blood vessels in the lungs become thickened and narrowed, forcing the heart to work harder until it eventually fails. This research identifies a small genetic molecule called microRNA-224 (miR-224) as a key driver of this abnormal blood vessel thickening. The study found that miR-224 levels are abnormally high in the lung tissue of PAH patients and in several animal models of the disease across multiple species, and that artificially raising miR-224 levels is enough to make lung smooth muscle cells grow uncontrollably — a hallmark of PAH.
The researchers then tested whether blocking miR-224 could treat the disease. Using two different approaches — a gene therapy delivered directly into the lungs as an aerosol, and a chemically engineered drug molecule (called LNA-224) — they were able to reduce disease severity in multiple animal models of PAH. Notably, when miR-224 was blocked specifically in smooth muscle cells, it not only slowed or halted the abnormal vessel thickening but also improved the function of the right side of the heart, which is the part that fails in PAH. The study also uncovered how miR-224 causes harm: it simultaneously shuts down a protective signaling pathway (BMP/SMAD) and amplifies a harmful one (TGFβ), tipping the balance toward abnormal cell growth.
This research suggests that miR-224 is a promising new therapeutic target for PAH. The fact that two different inhibitor strategies — gene therapy and a drug-like oligonucleotide — both worked across multiple animal species and disease models strengthens confidence in the approach. The lung-targeted aerosol delivery method is also potentially relevant for clinical translation, as it could concentrate treatment where it is needed while minimizing side effects elsewhere in the body.
Bikou O, Halouani A, Sun Y, Bisserier M, Eisenacher C, Antar S, et al.. (2026). MicroRNA-224 orchestrates BMP and TGFβ signaling and is a therapeutic target in preclinical pulmonary arterial hypertension.. Science translational medicine. https://doi.org/10.1126/scitranslmed.aef6676