Intrinsic pollen NADPH oxidases induce genes by activating innate immune responses in human bronchial epithelial cells

Abstract

Rationale We recently identified intrinsic NADPH-oxidase activity (NOA) in ragweed pollen extract (RWE) that induces oxidative stress in cultured bronchial epithelial cells and in vivo in the airway epithelial cells of mice. This NOA plays a key role in allergic inflammation (Boldogh et al). We hypothesized that NOA may directly modulate gene expression in airway epithelial cells via innate immune pathways. Methods A549 cells, a human bronchial epithelial cell line, were exposed to RWE for 1, 3, and 6 hours, and compared to an unexposed control. Cellular mRNA was analyzed for 15,000 genes by Affymetrix® HG-U133A GeneChip® microarray. Probe sets with an absolute fold change ≥2X from control were compared using a Venn analysis. Candidate genes were compared to three model time-course profiles and ranked by their correlation coefficient against the model trajectory: 1) progressively up/down with time, 2) up/down at 1 hour post-exposure, and 3) up/down at 3 hours post-exposure. Results Venn analysis showed that RWE with NOA had up-regulated 155 genes by 1 hour, 213 genes by 3 hours, and 193 genes by 6 hours more than 2 fold relative to the control. Likewise, RWE with NOA had down-regulated 100 genes by 1 hour, 118 genes by 3 hours, and 80 genes by 6 hours. Profile searches identified 68 genes that positively or negatively correlated at the 95% limit with profile 1, 63 with profile 2 and 82 with profile 3. Conclusions NOA modulates many genes in bronchial epithelial cells by activation of innate immune networks in epithelial cells.