Gene expression profiles based on Pulmonary Artery Pressures in Pulmonary Fibrosis

Pulmonary Hypertension (PH) is a frequent complication of Pulmonary Fibrosis (PF). PH can be seen in PF in the abscence of hypoxemia, irrespective of the degree of fibrosis. At the same time, a consistent number of patients with advanced PF never develop PH. The pathogenesis of PH secondary to PF remains unclear. PF patients are often referred to lung transplantation, but they present a higher incidence of pimary graft dysfunction than other diseases. The cause of this is unknown, and the relationship with PH remains unclear. We used microarray to identifiy the gene expression profiles in PF patients with and without PH Fresh frozen lung samples were obtained from the recipients organs of 116 PF patients undergoing lung transplantation. RNA was extracted and hybridized on Affymetrix microarrays. Pulmonary artery pressures were recorded intraoperatively with right heart catheters before starting lung transplantation. Patients were divided in different groups based on the mean pulmonary artery pressure. We compared the gene expression profiles in the group with severe PH (mPAP>40 mmHg, n=17) and in that without PH (mPAP<20 mmHg, n=22)) and obtained a gene signature, which was used for clusterying analysis. The clustering analysis based on the gene signature was then validated in an Intermediate PH group (mPAP 21-39 mmHg, n=45) and in a Validation Set (n=32).