Nanomaterials are increasingly used in consumer products, processed food, and food packaging, and few studies have determined the consequences of nanoparticle ingestion. The ultimate goal of this work is to determine if and how ingested metal oxide nanoparticles alter microorganism populations and intestinal function. A model of the GI tract and a panel of functional assays have been developed, and preliminary data shows that dietary doses of pristine metal oxide nanoparticles decrease mineral, glucose, and lipid absorption. These decreases in absorption are due to nanoparticle-induced alterations in microvilli structure. The presence of a single species of beneficial bacteria in the model prevents changes in nutrient absorption following nanoparticle exposure, and early results suggest that nanoparticle reactivity with biological components is related to metal oxidation state. The central hypothesis is that the microbiota can detoxify ingested metal oxide nanomaterials, but high doses or chronic exposure can induce small intestinal dysbiosis, alter intestinal epithelial structure, and result in decreased barrier properties and nutrient absorption. This hypothesis will be tested with three aims. First, individual strains of bacteria will be introduced into the GI tract model and molecular, functional, and structural epithelial characteristics and microbial viability and genotoxicity affected by acute and chronic metal oxide nanoparticle exposure will be identified. Second, a mock community of upper GI bacteria will be engineered and incorporated into the GI tract model to determine the effects of acute or chronic metal oxide nanoparticle exposure on microbial community dynamics and epithelial cell properties under both static and fluidic conditions. Third, a broiler chicken model (Gallus gallus), which is an established and robust method for quantifying nutrient bioavailability, brush border enzyme activity, and microbiome alterations will be used to validate in vitro results. This system, which will be the first to model upper GI conditions using a physiologically realistic, reproducible, high-throughput method with human-derived cells, will provide insight into nanoparticle-biological interactions. This valuable information is necessary for health and safety decisions and will be provided to both researchers and consumers. The scientific outcomes of this work are twofold: 1) the model created will allow quantitative assessment of the contributions of bacteria toward GI health and function and the ability to determine how what we eat governs microbial dynamics; and 2) data collected will determine the overarching behavior of metal oxide nanoparticles with biological GI components and allow for extrapolation across a broad class of commonly ingested nanomaterials.
Metal oxide nanomaterials are currently used in food and food packaging, but the relationship between metal oxide nanoparticle ingestion, gut microbial populations, and intestinal function has not been established. The project outlined in this proposal will provide a substantial amount of data on how a broad class of nanomaterials interact with the human body and will offer scientists a new way, using human-derived eukaryotic and prokaryotic cell populations, to test the interactions between consumed materials, the microbiota, and human GI cells. This information and these methods are valuable for health and safety, policy, and regulatory purposes.
