Lemay, S.-E.; Montesinos, M. S.; Grobs, Y.; Yokokawa, T.; Shimauchi, T.; Romanet, C.; Sauvaget, M.; Breuils-Bonnet, S.; Bourgeois, A.; Theberge, C.; Pelletier, A.; El Kabbout, R.; Martineau, S.; Yamamoto, K.; Ray, A. S.; Lippa, B.; Goodwin, B.; Lin, F.-Y.; Wang, H.; Dowling, J. E.; Lu, M.; Qiao, Q.; McTeague, A.; Moy, T. I.; Potus, F.; Provencher, S.; Boucherat, O.; Bonnet, S.

Pulmonary arterial hypertension (PAH) is characterized by obliterative vascular remodeling of the small pulmonary arteries (PA) and progressive increase in pulmonary vascular resistance (PVR) leading to right ventricular (RV) failure. Although several drugs are approved for the treatment of PAH, mortality remains high. Accumulating evidence supports a pathological function of integrins in vessel remodeling, which are gaining renewed interest as drug targets. However, their role in PAH remains largely unexplored. We found that the arginine-glycine-aspartate (RGD)-binding integrin 5{beta}1 is upregulated in PA endothelial cells (PAEC) and PA smooth muscle cells (PASMC) from PAH patients and remodeled PAs from animal models. Blockade of the integrin 5{beta}1 or depletion of the 5 subunit resulted in mitotic defects and inhibition of the pro-proliferative and apoptosis-resistant phenotype of PAH cells. Using a novel small molecule integrin inhibitor and neutralizing antibodies, we demonstrated that 5{beta}1 integrin blockade attenuates pulmonary vascular remodeling and improves hemodynamics and RV function in multiple preclinical models. Our results provide converging evidence to consider 5{beta}1 integrin inhibition as a promising therapy for pulmonary hypertension.