The overall goal of Project 1 is to understand the signaling pathways and metabolic or biological changes by which bioactive nutrients modulate impacts of acute or chronic exposure to persistent organic pollutants such as polychlorinated biphenyls (PCBs) and long-chain per- and polyfluoroalkyl substances (PFAS). Such persistent pollutants express significant chemical stability in the environment, and toxic insults from POPs are known to correlate with a range of post-exposure human health impacts, including vascular inflammation. Atherosclerosis, a chronic inflammatory disease, remains the leading cause of death in the United States. Biological events associated with inflammation and atherosclerosis can be modified by circulating toxicants and bioactive nutrients and their metabolites, which dictate final redox changes and inflammatory outcomes, by altering NF-kB and Nrf2 signaling. For example, preliminary data demonstrate down-regulation of PCB 126- mediated toxicity and inflammation by plant-derived bioactive nutrients, e.g., polyphenols, and fiber (e.g., inulin). Importantly, it is known that the pathology of atherosclerosis is dependent on the health and cross-talk of multiple tertiary organ systems including the liver and gut, as exemplified by recent findings linking PCB exposure with increased plasma levels of trimethylamine N-oxide (TMAO), a diet-derived metabolite formed through cross-talk between gut microbiota and hepatic oxidation and associated with risk of atherosclerosis. Preliminary findings indicate that persistent organic pollutants, and especially PCBs, caused liver dysfunction and alterations of gut microbiota, and that prior liver injury exacerbated PCB-mediated systemic inflammation. Metabolomic profiling further suggested that increased formation of pro-atherogenic metabolites (e.g., ceramides) may drive multi-organ inflammation and increased cardiovascular risk. Based on these findings, three specific aims test the hypotheses that 1) administration of PCB 126 and/or PFAS to mice increases cardiometabolic disease risk by increasing ceramide production via modulation of hepatic gene expression and/or the gut microbiota; 2) administration of green tea catechins and/or soluble inulin fiber in vivo decreases ceramides and thereby stabilizes cellular redox status, modulating NF-kB and Nrf2 signaling and pro- atherosclerotic pathologies as determined by en face and lipid staining in atherogenic LDL receptor-deficient mice; and 3) exposure to PCBs and/or PFAS increases pro-atherogenic metabolites (e.g., ceramides) through increased de novo synthesis in preclinical models. Transcriptomic and metabolomic technologies will be used to explore the mechanistic interactions between pollutant exposure, nutritional intervention, and cardiovascular disease (CVD) risks. These data will be confirmed in biobanked samples of humans with CVD. Results will support the paradigm that healthful nutrition interventions offer a powerful strategy to reduce disease risks associated with environmental toxic insults and to prevent inflammatory diseases, such as atherosclerosis, that have been linked to exposure to Superfund pollutants.
This project explores connections between two major public health concerns that are highly relevant to Superfund Research Program (SRP) stakeholders and the SRP: widespread contamination of the environment by a class of long-lasting toxic chemical contaminants known as PCBs and PFAS. These contaminants have been linked to a leading U.S. health challenge, cardiovascular diseases, and also linked to the liver and gut. The project addresses specifically SRP Mandate 4 by testing dietary interventions that may disrupt disease processes by stabilizing the gut bacteria and liver and reducing cardiovascular risks initiated by exposure to pollutants, particularly in people who reside near Superfund or other hazardous waste sites where PCBs and other pollutants are prevalent.
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