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bioRxiv · 10.64898/2026.05.27.728317

Nano- and microplastics in pediatric tonsil tissue: bioaccumulation, distribution, and immunomodulatory effects in human lymphoid aggregate organoids

Golchin Sani Masouleh, A.·Georgiadis, A. W.·Zhang, M. H.·Lin, Y.-W.·Kandlikar, I.·Kiessling, P. T.·Alikhani, M. A.·Miranda, A. M.·Alves, N. J.·Bindemann, A. D.·Umesh, A.·Campen, M.·Taylor, R. M.·Harper, S.·Meister, K. D.
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Abstract

Nano- and microplastics (NMPs), by-products of the fragmentation and degradation of plastic products, are ubiquitous environmental contaminants, yet their burden in pediatric immune tissues and functional consequences for developing immunity remain unknown. Here we report the first comprehensive characterization of NMPs in surgically excised pediatric tonsils (n = 30) using pyrolysis gas chromatography- mass spectrometry (Py-GC/MS), Nile Red fluorescence microscopy, and optical photothermal infrared (O-PTIR) spectroscopy. NMPs were detected in all specimens, with polystyrene, polyethylene, polyethylene terephthalate, and acrylonitrile butadiene styrene present in >90% of samples. To bridge clinical exposure data with mechanistic insight, we formulated a cryo-milled multi-polymer mixture reflecting the patient-derived polymer profile and challenged human lymphoid aggregate culture (HLAC) tonsil organoids at environmentally relevant concentrations. Multiplexed cytokine profiling of culture supernatants revealed a robust early inflammatory response at day 3, with significant upregulation of IL-6 (p = 0.011) and MIP-1{beta}/CCL4 (p = 0.011), followed by convergence toward control levels by day 14. Functional cytokine modules spanning immune, metabolic, structural, and growth factor pathways showed coordinated deviation from controls at day 3 post-exposure with subsequent normalization. Fluorescence-guided depth profiling demonstrated time-dependent penetration of 100 nm particles into organoid aggregates (70% tissue depth at day 3 versus 95% at day 14), and transmission electron microscopy revealed intracellular polyethylene within lymphocyte lysosomes. These findings establish pediatric tonsils as a sentinel tissue for NMP bioaccumulation and demonstrate that environmentally relevant polymer mixtures elicit transient but significant immunomodulatory responses in human lymphoid tissue, with implications for mucosal and systemic immune health in children. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/728317v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@19395f4org.highwire.dtl.DTLVardef@5a0380org.highwire.dtl.DTLVardef@19c0741org.highwire.dtl.DTLVardef@a052c5_HPS_FORMAT_FIGEXP M_FIG Structure: Translational pipeline from clinical tissue characterization to patient-informed preclinical modeling of nano-microplastic (NMP) exposure in pediatric lymphoid tissue. Pediatric tonsil tissue collected from clinically indicated tonsillectomies underwent tissue digestion for NMP characterization to identify NMP type and size distributions. In parallel, tonsil tissue was used to generate human lymphoid aggregate culture (HLAC) organoids that recapitulate the cellular complexity of the native tissue. These patient-derived organoids were then exposed to environmentally relevant compositions and concentrations of NMPs over time-course experiments, with longitudinal assessment of immunomodulatory responses including cytokine profiling and functional readouts. This bedside-to-bench approach establishes a physiologically relevant human system for investigating NMP-immune interactions, bridging clinical tissue analysis with mechanistic preclinical modeling to inform understanding of pediatric environmental exposures and their potential health impacts. C_FIG

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Golchin Sani Masouleh, A., Georgiadis, A. W., Zhang, M. H., Lin, Y.-W., Kandlikar, I., Kiessling, P. T., Alikhani, M. A., Miranda, A. M., Alves, N. J., Bindemann, A. D., Umesh, A., Campen, M., Taylor, R. M., Harper, S., Meister, K. D.. 2026-06-01. Nano- and microplastics in pediatric tonsil tissue: bioaccumulation, distribution, and immunomodulatory effects in human lymphoid aggregate organoids. https://doi.org/10.64898/2026.05.27.728317

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