Prenatal Exposures to Flame-Retardants: Mitochondrial Signatures and Childhood Obesity

PROJECT SUMMARY: Childhood obesity is a major public health risk in critical need of novel prevention and therapeutic efforts. Environmental exposures may promote the onset of childhood obesity through altered developmental programming. Poly-brominated diphenyl ether (PBDE) flame-retardants can bioaccumulate in utero resulting in elevated prenatal exposure. Experimental evidence suggests that PBDEs are adipogenic, however, studies in human populations are limited and the mechanisms remain unclear. PBDEs may induce mitochondrial dysfunction, which is further implicated in obesity, reflecting the key role of mitochondria in energy consumption. We propose to investigate associations of prenatal PBDE exposure with childhood adiposity, examining mitochondrial DNA (mtDNA) content, oxidative damage, and mutations as potential mechanisms of exposure and effect. In this K99/R00, Dr. Allison Kupsco will complement her skills in experimental toxicology with training in human population studies, specifically in mitochondriomics, environmental health, epidemiology, and statistics. As persistent, endocrine disrupting chemicals, PBDEs are an excellent paradigm exposure for this research/training program. In this proposal, we will leverage a longitudinal birth cohort, the Columbia Center for Children?s Environmental Health (CCCEH) with cord blood PBDE data, longitudinal data on adiposity (BMI and fat mass) from 5 to 18 years of age, and innovative abdominal magnetic resonance imaging (MRI) at 18 years to identify adipose sub-depots. In the K99 phase, existing adiposity data will provide precise information on longitudinal and adipose-tissue specific effects of PBDEs, individually and in mixtures (Aim 1), and we will generate longitudinal markers of mtDNA content, an excellent general indicator of mitochondrial health (Aim 2). In the R00 phase, Dr. Kupsco will complete mtDNA content data analysis and initiate a new investigation of mtDNA oxidative damage and mutations (heteroplasmy) with a novel deep-sequencing method, to assess specific effects of PBDEs on mtDNA and elucidate the mitochondrial basis of adiposity (Aim 3). These endpoints may serve as early biomarkers to identify children with high obesity risk, which would be critical to prevention efforts. To complete these aims, Dr. Kupsco will undergo training as a mix of formal coursework and expert guidance from her renowned mentoring team of Drs. Andrea Baccarelli, Julie Herbstman, Andrew Rundle, Jeff Goldsmith and Dympna Gallagher. Specifically, Dr. Kupsco will receive training in; 1) Mitochondrial markers with Dr. Baccarelli; 2) Prenatal exposure and children?s environmental health with Dr. Herbstman; 3) Methods in environmental epidemiology and causal mediation with Dr. Rundle; 4) Advanced longitudinal data analysis with Dr. Goldsmith; and 5) Clinical markers of adiposity/MRI with Dr. Gallagher. This will prepare Dr. Kupsco for a career as an independent molecular environmental epidemiologist, investigating prenatal exposures, mitochondrial toxicity and child obesity. Results from this work will advance the field of children?s environmental health and contribute to new hypotheses on drivers and mechanisms of adiposity.