Project description:Empirical evidence from both animals and humans suggest that PM2.5 (particulate matter < 2.5μm) exposure accelerates a variety of non-communicable diseases (NCDs) including Type 2 diabetes. We investigated whether chronic exposure to ambient air pollution (PM2.5), disrupts circadian rhythm to facilitate metabolic insulin resistance and compared the impact of inhaled ambient PM2.5 alone or in combination with continuous light exposure (LL). Exposure to PM2.5 induced peripheral IR, disrupted circadian steroid release, reduced peak oxygen consumption and altered brown adipose 18Ffluorodeoxyglucose uptake on PET imaging. These findings were identical to that seen with LL with no additive interaction between PM2.5 and LL. Transcriptome profiles in the liver revealed a number of differentially expressed circadian genes Bmal1 (Arntl/Npas2), Period (Per) and Cryptochrome (Cry) in response to PM2.5. Alteration in chromatin accessibility in circadian targets was observed with PM2.5 by Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) while chromatin immunoprecipitation (ChIP) analysis, showed a marked difference in promoter occupancy by p300. Our data suggest a previously unrecognized role of particulate air pollution in promoting circadian disruption and metabolic dysfunction through epigenetic regulation of multiple circadian targets
Project description:Chronic exposure to ambient particulate matter <2.5µ (PM2.5) has been linked to cardiopulmonary disease. Tissue-resident (TR) alveolar macrophages (AΦ) are long lived, self-renew and critical to the health impact of inhalational insults. There is inadequate understanding of the impact of PM2.5 exposure on nature/time course of transcriptional responses and the proliferation/maintenance of AΦ including the contribution from bone marrow (BM) over chronic time periods. We investigated the effects of exposure to real-world concentrated PM2.5 or filtered air (FA) in chimeric (CD45.2/CD45.1) mice. Here, we show that PM2.5 exposure induces an influx of BM-derived monocytes to lungs at 4-weeks, with no contribution to TR-AΦ population. Chronic (32-weeks) PM2.5 exposure resulted in enhanced apoptosis (Annexin V+) and decreased proliferation (BrdU+) of TR-AΦ and presence of BM-AΦ in inflamed lungs. RNA-seq analysis of flow sorted TR-AΦ and BM-AΦ from 4 and 32-weeks exposed mice, revealed a unique time dependent pattern of differentially expressed genes, with PM2.5 exposure with a pro-inflammatory bias. PM2.5 exposure resulted in pulmonary fibrosis and reduced alveolar fraction which corresponded to protracted lung inflammation. Our findings suggest a time dependent PM2.5 entrainment of a BM-derived monocytes infiltration into PM2.5 exposed lungs with an inflammatory phenotype, that together with enhanced apoptosis of TR-AΦ and pro-inflammatory polarization may contribute to perpetuation of chronic inflammation and lung fibrosis.
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.
Project description:In this study, we modeled early life air pollution exposure using C57BL/6J male mice on a controlled chow diet, exposed to real-world inhaled concentrated PM2.5 (~10x ambient level/ ~60-120g/m3) or filtered air (FA) over 14 weeks. We investigated PM2.5 effects on phenotype, transcriptome and chromatin accessibility, compared the effects with a prototypical high-fat diet (HFD) stimulus, and examined the effects of cessation of exposure on reversibility of phenotype/genotype.