Human Lung Project: Evaluating Variance of Gene Expression in the Human Lung

Abstract

Nondiseased tissue is an important reference for microarray studies of pulmonary disease. We obtained 23 single lungs from multiorgan donors at time of procurement. Donors varied in age, sex, smoking history, and ethnicity. Lungs were dissected into upper and lower lobe peripheral sections for RNA extraction. Microarray analysis was performed using Affymetrix Hu-133 Plus 2.0 arrays. We observed that the relative variability of gene expression increased rapidly from technical (lowest), to regional, to population (highest). In addition, age and sex have measurable effects on gene expression. Gene expression variability is heterogeneously distributed among biologic categories. We conclude that gene expression variability is greater between individuals than within individuals and that population variability is the most important factor in the study design of microarray experiments of the human lung. Classes of genes with high population variability are biologically important and provide a novel perspective into lung physiology and pathobiology. Our study represents the first comprehensive analysis of nondiseased lung tissue. The generation of this robust dataset has important implications for the design and implementation of future comparative expression analysis with pulmonary disease states.

Regulated gene expression in cultured type II cells of adult human lung

“…The precision of our expression profiling is influenced by biological variability between individual donors, including smoking history, and is likely further affected by variables such as extent of hypoxemia prior to death, use of mechanical ventilation, time from death to cell isolation, duration of the isolation procedure, and cell purity. The variability in lung gene expression between individuals is recognized and was similar for our experiments (median coefficient of variation of 32%) and those with postmortem human lung tissue (34). All donor lungs in our study were from males, which may have a minor effect on our results; in a genderspecific microarray study of lung tissue, 11% of X-linked genes were expressed at Ͼ1.5-fold different level between genders (60).…”

Gene Expression Profile of Human Airway Epithelium Induced by Hyperoxia In Vivo

“…Recent studies validated changes in modulated genes similar in direction and magnitude when compared with semiquantitative RT-PCR (38,41,42). The new strategies developed to improve the validity of the analysis focus on the identification of sets of genes instead of individual genes by themselves (43,44). In this study, we used the same approach, assuming that a set of genes displaying coordinated expression level is involved in a functional pathway.…”

Global expression profiles from C57BL/6J and DBA/2J mouse lungs to determine aging-related genes

“…The use of inbred mice achieves several advantages such as isogenicity and genomewide homozygosity among individuals within a strain, which significantly reduces gene expression variability between individuals. This variability was confounding in the aging human study (18). Aging mouse models have been used, for example, to evaluate global gene expression changes in skeletal muscle (35).…”

“…However, differential gene expression analyses have not been applied to the aging lung, a critical primary organ in the defense against environmental insults such as airborne pollutants. To date, only one study has documented global expression in healthy human lungs (18) as a function of age. Although this study did not actually achieve statistical significance in gene expression variation with age, modest global differences in gene expression between young and old subjects were observed.…”