Project description:Exposure to particulate matter (PM) is consistently associated with increased morbidity and mortality attributable in part to respiratory illnesses. The alveolar macrophage (AM) is one of the cell types in the lung constantly exposed to and activated by ambient pollutants. Upon contact with environmental particulate pollutants, AM produces reactive oxygen species (ROS) and antioxidant enzymes, but the scope of this oxidative stress response induced by PM remains poorly defined. In this study, we used microarray analysis to determine the gene expression profile in human alveolar macrophages upon exposure to PM and sought to gain more insight into the global response of pro- and anti-oxidant enzymes to PM exposure. Human AM were obtained by bronchoscopy from normal individuals. They were then incubated with Chapel Hill PM2.5 (1 ïg/ml) or vehicle for 4 hours (n = 6 independent samples each). mRNAs were extracted, amplified and hybridized to Agilent Human 1A microarray. Differentially expressed genes were identified by Statistical Analysis for Microarrays (SAM) with a FDR of 10% and a P â¤ 0.05. Significant genes were also mapped with Gene Ontology (GO) based on their molecular function. We found 34 and 41 up- and down-regulated genes respectively. Of these, 22 genes (~30%) were involved in metal binding and 14 genes were linked to oxidative stress, including 5 metallothionein-1 (MT1) isoform genes. In lung cells, addition of MT-1F in the medium attenuated PM2.5-induced H2O2 production while knockdown of MT1F gene expression increased H2O2 and IL-6 release induced by PM2.5. Our microarray experiments provided a global view of gene expression after in vitro PM2.5 exposure in human AM. The expression profile was most notable for differential expression of genes related to metal binding and oxidative stress, especially upregulation of MT1 isoform genes. Our findings suggest that metals associated with PM, e.g., zinc, copper, and arsenic, induce MT-1 and may be the primary mediators for PM-induced oxidative stress. Keywords: in vitro exposure, PM2.5 particle treatment, human alveolar macrophages Total RNA was isolated from alveolar macrophages from 6 subjects were treated in vitro with PM2.5 particles or vehicle control for 4 hrs. All particle-treated samples were co-hybridized with the common reference sample (pool of all 6 vehicle-treated samples) twice with Cy3 and Cy5 dyes flipped (12 hybridizations). Three samples were also co-hybridized with its own individual control (vehicle-treatment for the same subject) with Cy3 and Cy5 dyes flipped (6 additional hybridizations).

Project description:The perinatal period and early infancy are considered critical periods for lung development, and adversities during this period are believed to impact lung health in adulthood.The main factors affecting postnatal lung development and growth include environmental exposures, cigarette smoking, (viral) infections, allergic sensitization, and asthma.Therefore, we hypothesized that concomitant exposure in the early postnatal period in mice would cause more profound alterations in lung alveolarization and growth in adult life, quantified by stereology, and differently modulate lung inflammation and gene expression than either insult alone.Five-day-old male mice were immunized intraperitoneally (i.p.) with 10 µg of ovalbumin (OVA). This procedure was repeated at the 7th day of life, animals from the control group received i.p. injection of PBS only. Mice were exposed to either ambient PM2.5 or filtered air from the 5th to the 39th day of life, using an ambient particle concentrator developed at the Harvard School of Public Health (HAPC).Total RNA of lung samples (n=3 animals per group) was extracted using RNeasy Mini Kit (Qiagen, Hilden, Germany), according to manufacturer's instructions. The microarray analysis was performed using three RNA samples for each studied group (Control, OVA, PM2.5, OVA+PM2.5), totalizing 12 samples. One hundred nanograms of total RNA was ampliﬁed with the Ambion WT Expression Kit and hybridized onto the GeneChip Mouse Gene 2.0 ST Array (Thermo Scientific, Massachusetts, USA), following manufacturer’s protocol. The comparison between the control and OVA group exhibit 32 DEGs (28 up-regulated and 4 down-regulated), between the control and PM2.5 group had 6 DEGs (4 up and 2 down) and between the control and OVA+PM2.5 group had 5 DEGs (4 up and 1 down). The comparison between OVA and PM2.5 group showed 97 DEGS (22 up and 75 down) and between OVA and OVA+PM2.5 group had 7 DEGs (4 up and 3 down). Finally, the comparison between the PM2.5 and OVA+PM2.5 group exhibit 34 DEGs (2 up and 32 down).Our experimental data provide pathological support for the hypothesis that either allergic or environmental insults in early life have permanent adverse consequences to lung growth. In addition, combined insults were associated with the development of a COPD-like phenotype in young adult mice.

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