Gorecki, A. M. | Search bioRxiv

bioRxiv2026

Polystyrene microplastic exposure disrupts mitochondrial pathways and nuclear processes in primary intestinal epithelial cells

Microplastics are pervasive environmental pollutants that pose a growing concern for human health. Oral ingestion is a common route of human microplastic exposure, yet the proteomic response of the gut epithelium to microplastics remains unclear. This study aimed to investigate the cellular effects of pristine and artificially digested microplastic exposure in primary rat duodenal epithelial cells using untargeted proteomics. Cells were exposed to pristine or digested 0.5 um polystyrene microplastics at 10 or 100 ug/mL for 72 hours and were then analyzed by tandem liquid chromatography and mass spectrometry (LC-MS). Proteins that were both significantly different in intensity compared to controls, with a threshold change of 1.3 or greater, were considered to be differentially expressed. This criterion identified 41 differentially expressed proteins after 100 ug/mL pristine MP exposure, with 19 downregulated and 21 upregulated. Following exposure to 100 ug/mL digested MP, only 3 differentially expressed proteins were upregulated and 7 were down regulated, demonstrating the impact of microplastic physicochemistry. FGSEA pathway analysis revealed that 270 Reactome pathways were significantly altered following microplastic exposure in either condition at both concentrations. These pathways contributed to functional domains including protein synthesis, DNA replication, cell cycle control and aerobic respiration. Overall, microplastic exposure was associated with upregulated mitochondrial respiration, and downregulation of nuclear-related processes including DNA synthesis, transcription and cell proliferation. This study provides targets for future investigation (mitochondria and nucleus) and emphasizes the need to consider biological and environmental conditions for in vitro models of microplastic exposure.

molecular biology↗

bioRxiv2022

Rate of neuronal turnover in the healthy adult murine myenteric ganglia varies with ganglia size

Maintenance of normal structure of the enteric nervous system (ENS), which regulates key gastrointestinal functions, requires robust homeostatic mechanisms, since by virtue of its location within the gut wall, the ENS is subject to constant mechanical, chemical, and biological stressors. Using transgenic and thymidine analogue-based experiments, we previously discovered that neuronal turnover - where continual neurogenesis offsets ongoing neuronal loss at steady state - represents one such mechanism. Although other studies confirmed that neuronal death continues into adulthood in the myenteric plexus of the enteric nervous system (ENS), the complicated nature of thymidine analogue presents challenges in substantiating the occurrence of adult neurogenesis. Therefore, its vital to employ alternative, well-recognized techniques to substantiate the existence of adult enteric neurogenesis in the healthy gut. Here, by using established methods of assessing nuclear DNA content and detecting known mitotic marker phosphor-histone H3 (pH3) in Hu+ adult ENS cells, we show that [~]10% of adult murine small intestinal myenteric Hu+ cells, and [~]20% of adult human small intestinal myenteric Hu+ cells show evidence of mitosis and hence are cycling neuroblasts. We observe that proportions of Hu+ cycling neuroblasts in the adult murine ENS neither vary with ganglia size, nor do they differ significantly between two intestinal regions - duodenum and ileum, or between sexes. Confocal microscopy provides further evidence of cytokinesis in Hu+ cells. The presence of a significant population of cycling neuroblasts in adult ENS provide further evidence of steady state neurogenesis in the adult ENS.

neuroscience↗