Microplastics are pervasive environmental contaminants with growing concerns about human health effects after ingestion. The study summarized here used untargeted proteomics to examine how primary rat duodenal epithelial cells respond at the protein level to exposure to polystyrene microplastics. The principal objective was to compare the cellular effects of pristine versus artificially digested microplastic particles, focusing on pathway-level alterations that could identify organelle or process-specific targets for follow-up work.
Primary rat duodenal epithelial cells were cultured and exposed in vitro to 0.5 μm polystyrene microplastic particles. Two physicochemical particle preparations were tested: pristine microplastics and particles that had been artificially digested. Exposures were applied at two concentrations (10 μg/mL and 100 μg/mL) for 72 hours. Following treatment, cells were analyzed using tandem liquid chromatography–mass spectrometry (LC‑MS) in an untargeted proteomic workflow.
Proteins were considered differentially expressed when their intensity differed from control by a threshold of 1.3-fold or greater. Pathway enrichment and functional interpretation used FGSEA with Reactome pathway annotations to identify significantly altered biological pathways across conditions and concentrations.
At the 100 μg/mL concentration of pristine 0.5 μm polystyrene, the authors reported 41 differentially expressed proteins relative to untreated controls. Within that set the manuscript reports 19 proteins classified as downregulated and 21 classified as upregulated. These protein-level changes provided the basis for pathway enrichment analyses that follow.
Particle physicochemistry influenced the proteomic responses. After exposure to 100 μg/mL of the artificially digested microplastics, far fewer proteins met the differential-expression threshold: the authors report 3 upregulated proteins and 7 downregulated proteins. This contrast between pristine and digested particle preparations highlights that biological or environmental transformations of microplastics can change cellular responses in vitro.
Using FGSEA with Reactome pathway definitions, the authors identified 270 Reactome pathways that were significantly altered by microplastic exposure across the tested conditions and concentrations. The altered pathways clustered into several functional domains, specifically:
These pathway-level perturbations indicate a broad cellular response that spans both cytoplasmic and nuclear processes as well as metabolic/energetic adjustments.
Synthesizing the proteomic and pathway analyses, the authors concluded that microplastic exposure was associated with an increase in mitochondrial respiration–related activity and a concurrent downregulation of nuclear-associated processes. Nuclear-related reductions included pathways connected to DNA synthesis, transcription and cell proliferation. In short, the reported proteomic signature suggests a shift toward elevated mitochondrial function alongside suppression of processes essential for nuclear maintenance and cell cycle progression.
The study highlights two cellular compartments—the mitochondria and the nucleus—as priority targets for mechanistic follow-up to define causal links between particle exposure and cellular dysfunction. The differential effects observed between pristine and digested particles underscore the importance of particle physicochemistry and realistic environmental or digestive transformations when designing in vitro exposure models. Future investigations could expand on these findings by reporting dose–response relationships, time-course experiments, complementary functional assays (for example, measures of mitochondrial respiration, DNA synthesis, cell proliferation), and validation across species or human-derived cells.
This report is a preprint and has not undergone peer review. The abstract provides summary results (exposure conditions, fold-change threshold, counts of differentially expressed proteins, and pathway enrichment outcomes), but additional methodological details—such as exact replicate numbers, statistical methods, full protein lists, and specific pathway effect sizes—are not listed in the abstract and should be consulted in the full text and supplementary materials for comprehensive appraisal.
In primary rat duodenal epithelial cells exposed in vitro to 0.5 μm polystyrene microplastics for 72 hours, untargeted proteomics revealed altered protein expression and pathway activity. The response differed between pristine and artificially digested particles, with the pristine preparation producing more extensive proteomic changes. Pathway analysis implicated increased mitochondrial respiration and decreased nuclear processes including DNA replication, transcription and proliferation. The authors recommend further mechanistic investigation of mitochondria and nucleus and call for attention to biological and environmental context in microplastic exposure models.