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Affymetrix Gene Expression Microarrays Application to Pulmonary Arterial Hypertension Bob Stearman 02/24/2014
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Pulmonary Arterial Hypertension (PAH) Rare Disease: USA ~1000 new cases/yr More Common in Females (2:1) with Earlier Presentation (30s-40s vs 40s-50s) BMPR2 Mutations Found in HPAH with Incomplete Penetrance Combination Drug Therapy Common PDE5 and Endothelin Inhibitors plus Prostacyclin Slows Progression But No Cure (5-yr 66%) Elevations of Pulmonary Hemodynamics
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Pulmonary Arterial Hypertension (PAH) Hyperproliferation of PAECs and SMCs Structural Changes in Lung Vasculature Stacher et al., AJRCCM 186, 261 (2012) Vessel ThickeningMuscularization (SMCs)Plexiform Lesion (ECs)
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Pulmonary Arterial Hypertension (PAH) Elevation in Pulmonary Hemodynamics Echocardiogram and Right Heart Catherization Studies Increased Inflammation Stacher et al., AJRCCM 186, 261 (2012) Vessel Thickening vs mPAP (p-value 0.03; r=0.27) Perivascular Inflammation
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Multi-Center Lung Tissue Procurement 9 Geographically Spread Procurement Centers “Excessively” Complex Tissue Dissection 3+ Hours To Carryout 1 Central Tissue Repository Genomics Core & Secondary Tissue Repository (Frozen and RNALater) Rare Disease = Slow Recruitment Pulmonary Hypertension Breakthrough Initiative
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PHBI Clinical Information Stacher et al., AJRCCM 186, 261 (2012)
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PHBI Pathological Information Vessel Thickness (measured and fractional) Total, Intima, Media, Internal Diameter Plexiform Lesions Number and Density Inflammation Thrombi Pulmonary Vein Remodeling Stacher et al., AJRCCM 186, 261 (2012)
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RUL = right upper lobe RML = right middle lobe RLL = right lower lobe H= Hilum. PHBI Lung Tissue Harvest Stacher et al., AJRCCM 186, 261 (2012)
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PAH Patients: End-stage disease getting transplant 4 General Types of PAH: HPAH, IPAH, APAH, Other Failed Donors (FDs; controls): No match for lungs but available for research Slow Recruitment: MAs run in 3 “annual” batches PAH: Female Bias (2:1 F:M) and older FDs: Male Bias (1:2 F:M) and younger compared to PAH Pulmonary Hypertension Breakthrough Initiative: Sample Summary
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Workflow of Gene Expression Reddy Gali, Ph.D. Microarray Analysis Using R/Bioconductor Biological question Experimental design Tissue / sample preparation Extraction of Total RNA Microarray hybridization & processing Image analysis Probe amplification & labeling Data analysis Expression measures - Normalization - Statistical Filtering - Clustering - Pathway analysis Biological Verification QC
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PHBI: Experimental Design PAH Patients vs. FD Disease-specific gene expression patterns? 4 General Types of PAH: HPAH, IPAH, APAH, Other Will Gene Expression Patterns Detect Clinical Subclasses? PAH Patient Gender Bias PAH vs FD Gender and Age (?) Bias Microarrays run in 3 “annual” batches Different lots of arrays and reagents Changes in labeling methodology
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PHBI Lung RNA Samples (in RNALater) Are Variable
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PHBI: Normalization Uncorrected PHBI Data
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PHBI: Normalization Corrected PHBI Data By Batch and Gender
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PHBI: Normalization Corrected PHBI Data By Batch and Gender Low Variance Genes Removed (33K->6K)
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PHBI: Clustering
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PHBI: Expression Correlation With Clinical Parameters
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Sources of Reproducibility (Experimental Design- Randomization) C4 Hybridized Sample B & A1 (Day 1); A6 & A15 (Day 2) [while same day samples had very similar #DE genes as C1, C2, and C3] C5 Hybridized Samples B & A1 (Day 1); A6 (Day 2); A15 (Day 3) C2 and C3 Stored Male Arrays ON, 4 o C while Female Arrays were Wash/Stain (Yang et al 2008)
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Sources of Reproducibility (Experimental Design- Randomization) (Yang et al 2008) Each dataset is self-consistent Training on Center 3 generally groups M and F by sample type Training on Center 4 produces poor correlation between M and F by sample type
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Stability of Results Critical Review of Published Microarray Studies for Cancer Outcome and Guidelines on Statistical Analysis and Reporting Alain Dupuy, Richard M. Simon (JNCI 2007) “Simon Says Top 40”
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Nature Biotechnology 28, 827 (2010)
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Affymetrix Gene Expression Microarrays Report Expectations Experimental Design and Questions Summary Signal Intensities Before and After Normalization PCA plots Significant Genes Listing including FC, p-value, FDR analysis Cluster Diagram (+/- Signal Intensities) Over-represented Gene Ontology Categories RDAVID?? Experimental Conclusions and Discussion
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Affymetrix Gene Expression Microarrays Report Expectations
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