Heavy metals exposure regulates secretory lineage in intestinal injury

项目总结 超过16万个废弃的矿山废弃场集中在美国西部，并继续 重金属含量升高，渗入周围的沉积物和地下水，使环境恶化。 废弃铀矿场附近社区使用的沉积粉尘和水 经常超过铀的最大污染水平(铀，环境保护局最高水平30μg/L)。长期接触 环境毒素和重金属与肠道炎症有关，增加了对 病原体引起的疾病和结直肠癌的较高发病率；所有这些都是稳定的 在过去的40年里，患病率不断上升。重金属对肠道的负面影响 已经描述了微生物区系、屏障通透性和抑制肠上皮愈合；然而， 肠上皮细胞内转录的变化在很大程度上是未知的。一旦摄入，铀就会被 全身吸收不良(~1.5%)，因此分布在整个肠道，表明U甚至很低 其水平足以造成肠道损伤。因此，我们的目标是表征颗粒粉尘(指 作为一种环境毒物，损害肠道上皮细胞，并确定 作为对这种损伤的反应而发展起来的分子变化。我们之前已经描述了肠道的特征 在稳态和病原体感染条件下，人类肠道器官(HIO)中的粘液层，以 将HIOS描述为一种肠道病理生理模型。我们接触UBD的HIO的初步数据 发现接触化学物质会对结肠中的分泌谱系产生负面影响，特别是对粘液- 产生杯状细胞和产生激素的内分泌细胞。因此，我们假设UBD有一个 直接作用于：1)粘膜表面，表现为粘液层变薄和杯状细胞功能障碍 2)隐窝内的肠道内分泌细胞。这导致对肠道的易感性增加。 精神错乱。以下目标将以机械的方式解决这些问题。第一个目标是 确定UBD对粘液层变薄、导致的促炎反应以及随后的 杯状细胞扩张。第二个目标将研究增加内分泌激素分泌对 UBD化学治疗后肠道愈合与肠内分泌细胞扩增的特定途径 受伤。有必要了解重金属，特别是那些以颗粒物形式自然存在的重金属， 推动暴露个人的变化，使他们易患肠道疾病，并开发新的策略 这将有助于预防。这一提议的成功完成将有助于我们理解 可能导致结肠炎或相关疾病的环境诱导损伤的基础，确定潜在的 治疗靶点，并确定可能导致易感性的基因变异。

PROJECT SUMMARY Over 160,000 abandoned mine waste sites are concentrated in the western United States and continue to degrade the environment with elevated heavy metals penetrating the surrounding sediment and groundwater. The sedimentary dust and water used by communities located near abandoned uranium mine (AUM) sites often exceeds the maximum contamination level for uranium (U, EPA max level 30 μg/L). Chronic exposure to environmental toxins and heavy metals has been linked to intestinal inflammation, increased susceptibility to pathogen-induced diseases, and higher incidences of colorectal cancer; all of which have been steadily increasing in prevalence for the past 40 years. The negative effects of heavy metals on the intestinal microbiota, barrier permeability, and inhibition of intestinal epithelial healing have been described; however, transcriptomic changes within the intestinal epithelial cells are largely unknown. Upon ingestion, uranium is poorly absorbed systemically (~1.5%) and thus distributed through the entire intestine, suggesting even low U levels are sufficient to cause intestinal damage. Thus, our goals are to characterize particulate dust (referred to as U-bearing dust, UBD) as an environmental toxicant that damages the intestinal epithelia and determine the molecular changes that develop as a response to this injury. We have previously characterized the intestinal mucus layer in human intestinal organoids (HIOs) under homeostasis and pathogen infected conditions, to characterize HIOs as an intestinal pathophysiological model. Our preliminary data of HIOs exposed to UBD found that chemical exposure negatively impacts the secretory lineage in the colon, specifically the mucus- producing goblet cells and hormone-producing enteroendocrine cells. Thus, we hypothesize that UBD has a direct effect on: 1) the mucosal surface, represented by a thinning mucus layer and goblet cell dysfunction and 2) the intestinal enteroendocrine cells in the crypt. This leads to increased susceptibility to intestinal disorders. The following Aims will address these questions in a mechanistic manner. The first aim will determine the impact of UBD on mucus layer thinning, resulting pro-inflammatory response, and subsequent goblet cell expansion. The second aim will examine the roles of increased endocrine hormone secretion for intestinal healing and the specific pathway that direct enteroendocrine cell expansion following UBD chemical injury. There is a need to understand how heavy metals, especially those naturally occurring as particulates, drive changes in exposed individuals to predispose them to intestinal disorders and to develop novel strategies that will aid in prevention. Successful completion of this proposal will help us understand the mechanistic underpinnings of environmental-induced injury that may promote colitis or related diseases, identify potential therapeutic targets, and identify genetic variations that may contribute to susceptibility.