The Role of Airborne PCBs in Adipogenesis, Adipose Function, and Metabolic Syndrome

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SUMMARY: Project 2 – Metabolic Syndrome PCBs accumulate in fat and are associated with the development of metabolic syndrome (MetS), yet the specific role of PCB-induced disruption of adipose endocrine signaling in the development of MetS is unknown. Epidemiological studies have demonstrated an association between exposure to PCBs and MetS, a cluster of conditions including obesity, hypertension, dyslipidemia, and hyperglycemia, which increase the risk of heart disease, stroke, and type II diabetes. The Iowa Superfund Research Program (ISRP) has shown children are exposed to high levels of airborne PCBs in schools, putting them at potential risk for the development of MetS. In addition, the ISRP demonstrated that airborne PCB exposure results in the accumulation of PCBs in adipose tissue. We have shown that dioxin-like PCBs can disrupt adipogenesis, leading to aberrant adipocyte function. How volatile PCBs affect adipose tissue to contribute to the development of MetS is unknown. We hypothesize that airborne PCBs and their metabolites contribute to the development of MetS via a mechanism that involves disruption of adipogenesis and adipocyte endocrine function. We have developed unique tools, including multiple unique immortal human preadipocyte cell lines and a 3D organoid model system, that enable the study of PCB-induced alterations in the maturation and function of human adipose tissue in culture. Human preadipocytes cultured in the 3D organoid model system can mature, store lipids, and secrete adipokines more efficiently than those in 2D cultures. This system challenges the status quo of 2D culture with a culture model that is more relevant to human exposure. In Aim 1, we will utilize the 3D system to elucidate the functional consequences of exposure to PCBs (individual congeners and relevant mixtures) on adipogenesis and adipocyte function. In Aim 2, we will develop a human adipose-liver biomimetic on-chip that allows for human- liver specific metabolism of PCBs for facile testing of the effects of PCB and PCB-metabolites on adipose function. In Aim 3, we will assess how PCB11 and PCB52, two PCBs commonly found in air, affect adipose function, adiposity, and metabolism in vivo using a rat model, comparing our results to those found with our 3D system. The studies will be guided by other ISRP projects to determine which PCBs are most prevalent in air and which PCBs and PCB-metabolites are present in adipose tissue. Further, our work will rely on ISRP cores for synthesis and analytical assessment of PCBs in study samples. Our project is relevant to the SRP mandates because it will result in the development of an innovative technology to assess how PCBs act as endocrine disruptors through their effects on adipose tissue, which, in turn, will be important for assessment of exposure risk to the development of MetS. Our findings will be of significant interest to regulatory agencies and communities concerned about how PCB exposure affects MetS in children, adolescents, and young adults.