Is pulmonary vascular disease reversible with PPAR ɣ agonists?

Severe angio-obliterative PAH remains a disease characterized by great morbidity and shortened survival. Unfortunately, the only currently available treatments for angio-obliterative changes are palliative in the form of pulmonary vasodilators evolving from the phosphodiesterase inhibitor sildenafil to endothelin receptor antagonist: Bosentan; while the only definitive treatment is lung transplantation which remains dependent on the availability of donors and the transplant policies which vary widely from a country to another. PPARs, especially the γ isoform, are largely expressed in pulmonary artery endothelial cells and smooth muscle cells. They are also found on endothelial progenitor cells. Several previous studies have highlighted the role of PPAR γ agonists in reversal of vascular remodeling especially in coronary, carotid and peripheral vascular disease atherosclerotic plaques. Experimental studies have also revealed that PPAR γ activation affects many different pathways; thus, the effect of PPAR γ is multifaceted, affecting almost every pathobiological pathway involved in the development of PAH simultaneously. We thereby hypothesize that PPAR γ agonists may play a key role in reversing severe pulmonary angio-obliterative changes and promote microvascular regeneration which may substitute the need for heart-lung transplantation in such patients.