Heterogeneous nanoplastic exposure induces integrated immunometabolic transcriptional responses in human monocytes under continuous flow.

Nanoplastics interact continuously with circulating immune cells, yet how particle size and exposure complexity shape immune transcriptional responses under dynamic exposure conditions remains poorly understood. Here, controlled microfluidic exposure was combined with single-cell RNA sequencing to investigate the effects of size-defined polystyrene nanoplastics (PSNPs; 40 nm, 200 nm, and 40 + 200 nm) on primary human peripheral blood mononuclear cells (PBMCs) under continuous flow conditions. Across immune populations, PSNP exposure induced a conserved ribosome-associated and RNA-regulatory transcriptional program, indicating a shared intracellular transcriptional response. Monocytes displayed particularly prominent transcriptional remodeling, characterized by coordinated modulation of ribosome-associated, metabolic, and inflammatory signaling pathways across exposure conditions. Exposure to 40 nm PSNPs showed negative enrichment of mitochondrial metabolic pathways, whereas 200 nm PSNPs showed enrichment of inflammatory signaling programs. Heterogeneous particle-size exposure induced concurrent metabolic and inflammatory pathway engagement without evidence of major inter-lineage connectivity disruption or discrete inflammatory state transitions. Orthogonal flow cytometry measurements in PBMCs from three donors showed trends towards increased frequencies of IL-6- and TNF-α-positive monocytes following PSNP exposure. In contrast, adaptive immune cells exhibited comparatively modest and lineage-preserving transcriptional modulation. Together, these findings indicate that size-defined PSNP exposure conditions and exposure composition are associated with coordinated immunometabolic transcriptional responses in human immune cells under continuous flow conditions and establish a framework for studying dynamic material-immune interactions at single-cell resolution.