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Vascular Pharmacogenomics in a Surgical Shunt Model of Pulmonary Arterial Hypertension (PAH): Analysis by Endoarterial Biopsy

Alex Rothman

D. L. Mann

S. Davidson

R. Wiencek

V. Sarukhanov

W. E. Evans

R. Williams

E. Rouslathi

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Conference: 2008 International PHA Conference and Scientific Sessions

Release Date: 06.20.2008

Presentation Type: Abstracts

Rothman A., Mann D., Davidson S., Wiencek R., Restrepo H., Sarukhanov V., Evans W.E., Williams R., Rouslahti E.

University of Nevada School of Medicine, Children’s Heart Center Nevada, Vascular Biosciences, Inc., Anesthesiology Consultants, Inc., Cardiovascular Surgery Associates, Burnham Institute for Medical Research, BIMR at University of California Santa Barbara, USA

BACKGROUND: The molecular mechanisms associated with PAH are still unclear. Consequently, treatment for PAH, while recently improved, still offers significant and long-lasting improvement in only a minority of patients. There is no cure. A methodology to elucidate the molecular pathways associated with PAH could guide the development of new therapies for this disease. The aim of this study was to obtain endoarterial biopsy samples over a 2-month time-course in a surgical porcine model of PAH in order to construct a microarray-based map of changes in gene expression during the progression of the disease.

METHODS: 20-30 kg Yucatan Micropigs underwent surgical anastomosis of the left pulmonary artery to the descending aorta, resulting in left pulmonary arterial hypertension of at least ½ systemic level. Endovascular samples were obtained from 2-3 mm arteries with an endoarterial biopsy catheter at baseline (prior to surgery), and from the hypertensive left lung 21 and 60 days after surgery. RNA was isolated from biopsy samples, and RNA integrity evaluated. RNA was then amplified and loaded into an Affymetrix GeneChip Porcine Whole Genome Array containing 20,201 Sus scrofa genes. Gene expression level differences between sets of biological replicate samples from baseline, 21- and 60-day time-points were then analyzed using GeneSpring. Gene expression changes relative to baseline were then loaded into Ingenuity Pathway Analysis (IPA) software. IPA was used to identify the expression of dysregulated genes previously described to be associated with PAH as well as new upregulated genes, for which there are known inhibitors, in order to identify existing drugs which could potentially be used to treat or prevent PAH.

RESULTS. Data were obtained from 4 animals. Single endoarterial biopsy samples contained sufficient RNA for microarray analysis. The validity of the model was confirmed by examining the expression changes for selected genes previously found to be dysregulated in PAH, such as EDN1, TIE2, TGFB2, 5-HT2B, BIRC5, ANG2 and others, which were upregulated, eNOS3, iNOS, APOE, PPARG and others, which were downregulated. Genes with known inhibitors currently in use or under investigation for PAH, such as EDNRB, HTR2B, GUCY1B3, PDGFRA, HMGCR, KCNB1, and others, were also found to be upregulated in our model. Interestingly, genes for which there are known inhibitors, but no previous association with PAH such as C5, TACSTD1, CD3G, HPSE, MAOB, HDAC2, CXCR4, IFNAR2, PREP, RRM1, POLG, RARB, HPRT1, CDK7, ADORA3, KCNJ2, CCR5, LTB4R2, MAOA, TLR8, CFTR, DPYD, PPIA, IMPDH2 and others, were also found to be upregulated. Gene dysregulation varied between the 21- and 60-day time points.

CONCLUSIONS: Endoarterial biopsy provides a new method to assess pulmonary vascular gene expression in PAH. This analysis could identify novel PAH applications for existing drugs. The detection of stage- and disease-specific variation in gene expression could lead to individualized pharmacogenomics.