Assessing the Effects of Plastics on Intestinal Health: A Comparative Study using 3D Human and Mouse Intestinal Models - Project Summary/Abstract The escalating presence of microplastics (MPs) and nanoplastics (NPs) in the environment raises alarms about their potential impact on both ecological systems and human health. Notably, these particles are often found in the human gastrointestinal tract, yet a comprehensive understanding of their health effects remains elusive. In our lab, we excel in establishing three-dimensional (3D) mini-intestine models sourced from human intestinal organoids, allowing us to simulate both healthy and diseased intestines. Leveraging these capabilities, recent studies in our lab using organoid-derived monolayers—both with and without M cells—have identified clear interactions between human intestinal organoids and polystyrene MPs/NPs. Crucially, we observed that the dose, size of the particles, and the presence of M cells significantly modulate immune responses. Our ongoing research endeavors aim to expand on these findings by synergizing our specialized in vitro 3D human intestinal models with comprehensive in vivo mouse studies. By examining the implications of exposure to various environmentally relevant MPs and NPs across different biological hierarchies—from molecular to cellular to individual levels—we aim to provide a comprehensive understanding of the potential health consequences. We hypothesize that environmentally relevant MPs and NPs disrupt gut homeostasis, exacerbate inflammation in intestines already compromised, with the intensity governed by their attributes and exposure duration, and that M cells play a crucial role in mediating these immune responses. To test the hypothesis, we proposed the following aims. Aim 1 focuses on assessing the acute and chronic effects of MPs and NPs on intestinal health. Using patient-derived, 3D bioengineered human and mouse intestinal models, we will explore how different particle characteristics and exposure durations influence gut health. This will involve comparing the effects of different plastic particles on in vitro 3D human and mouse models, helping us differentiate species-specific responses. Aim 2 investigates the influence of MPs and NPs on inflamed intestines. Our hypothesis posits that these particles exacerbate inflammation in already inflamed gut environments. By using an inflamed variant of our 3D human intestinal model, we will track inflammation markers and examine how plastic particles affect tissue integrity and microbial balance. Findings from the human models will be corroborated through whole- organ examinations in inflamed mouse models, ensuring a holistic understanding of systemic reactions. Aim 3 seeks to unravel the specific role that Microfold (M) cells play when interacting with MPs and NPs. We postulate that these cells can amplify the gut's response to plastic particles, potentially driving inflammation due to their unique properties. This aim will involve creating multiple model variations to explore the apoptotic effects of particles on M cells and their subsequent impact on inflammation. Our project deciphers the multi- dimensional impacts and underlying mechanisms of MPs and NPs on intestinal health, thereby informing future clinical and environmental strategies.
