Heavy metals exposure regulates secretory lineage in intestinal injury

项目摘要 超过160，000个废弃的矿山废物场集中在美国西部，并继续 随着重金属含量的增加，环境恶化，渗透到周围的沉积物和地下水中。 位于废弃铀矿（AUM）场地附近的社区使用的沉积灰尘和水 通常超过铀的最大污染水平（U，EPA最大水平30 μg/L）。长期暴露于 环境毒素和重金属与肠道炎症有关， 病原体引起的疾病，以及结直肠癌的发病率较高;所有这些都是稳步增长的。 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 已经描述了微生物群、屏障渗透性和肠上皮愈合的抑制;然而， 肠上皮细胞内的转录组变化在很大程度上是未知的。摄入后，铀 全身吸收较差（~1.5%），因此分布于整个肠道，表明即使是低U 足以造成肠道损伤因此，我们的目标是表征颗粒灰尘（指 作为含铀粉尘，UBD）作为一种环境毒物，损害肠上皮细胞，并决定 作为对这种损伤的反应而产生的分子变化。我们之前已经描述了肠道 在体内平衡和病原体感染条件下人肠类器官（HIO）中的粘液层， 将HIO表征为肠病理生理学模型。我们对暴露于UBD的HIO的初步数据 发现化学暴露对结肠分泌谱系产生负面影响，特别是粘液- 产生杯状细胞和产生唾液酸的肠内分泌细胞。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）隐窝内的肠内分泌细胞。这导致对肠道疾病的易感性增加。 紊乱以下目标将以机械的方式解决这些问题。第一个目标将 确定UBD对粘液层变薄的影响，导致促炎反应，以及随后的 杯状细胞扩增。第二个目标是研究内分泌激素分泌增加对 肠愈合和特定的途径，指导肠内分泌细胞扩增后UBD化学 损伤有必要了解重金属，特别是那些自然存在的颗粒， 促使暴露个体发生变化，使其易患肠道疾病，并开发新的策略 有助于预防。成功完成这一提案将有助于我们了解 可能促进结肠炎或相关疾病的环境引起的损伤的基础， 治疗目标，并确定可能导致易感性的遗传变异。

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.