Biology subjects

Kleinjan, M.

Publications and source records attributed to Kleinjan, M..

4 recordsLinked to original sources

bioRxiv2026

Extracellular vesicles from Manila clam (Ruditapes philippinarum): tailored isolation from hemolymph and insights into water-derived vesicles

Extracellular vesicles (EVs) are evolutionarily conserved mediators of intercellular communication released by cells into biological fluids and the extracellular environment. Despite their growing relevance in biomedical and veterinary research, knowledge on EVs in marine bivalves remains limited. The aim of this study was to optimize tailored protocols for EV isolation from the hemolymph of the Manila clam (Ruditapes philippinarum) based on density gradient ultracentrifugation (dgUC) or size exclusion chromatography (SEC). EV-enriched fractions were identified through nanoparticle tracking analysis, protein quantification, transmission electron microscopy, and cryo-electron microscopy. Both methods successfully isolated small EVs (<200 nm). While dgUC yielded higher-purity preparations, SEC provided a higher recovery rate and compatibility with downstream metabolomic analyses. Metabolomics performed on SEC fractions and on hemolymph, revealed that EV-enriched fractions possessed a distinct metabolic signature including enrichment in metabolites associated with nucleotide metabolism, glycolysis, redox regulation, and energy metabolism. Furthermore, we performed a pilot investigation into the presence of EVs released into conditioned water by Manila clams. Using tangential flow filtration and ultrafiltration, EVs were successfully concentrated from water samples and characterized by nanoparticle tracking analysis, CONAN assay, atomic force microscopy, and electron microscopy. Our findings demonstrate the feasibility of isolating EVs both from Manila clam hemolymph and from conditioned water, providing the first evidence of water-derived EV recovery in aquatic animals. Although further methodological refinement is needed to improve the purity of EVs isolated from water, and additional characterization studies are required to better define the molecular composition of clam-derived EVs, these results establish a foundation for future investigations into the role of EVs in bivalve biology and their potential application as minimally invasive biomarkers for aquaculture, environmental monitoring, and ecosystem health assessment.

systems biology↗

bioRxiv2023

Maternal allergic sensitization affects the T cell modulatory capacity and molecular cargo of milk derived extracellular vesicles

BackgroundHuman milk extracellular vesicles (EVs) affect various cell types in the gastrointestinal tract, including T cells, and play a role in the development of the newborns immune system by delivering specific molecular cargo to target cells. Although maternal allergic sensitization alters the composition of milk, it is unknown whether this impacts the function of milk EVs. Therefore, we analyzed the T cell modulatory capacity and compared the protein and miRNA cargoes of EVs from milk of allergic and non-allergic mothers. MethodsEVs were isolated from human milk from allergic and non-allergic donors by differential centrifugation, density gradient floatation and size exclusion chromatography. Functional modulation of primary human CD4+ T cells by EVs was assessed in vitro. Proteomic analysis and small RNA sequencing was performed on milk EVs to evaluate protein and miRNA abundance and to identify cellular targets of this EV cargo in relevant T cell signaling pathways. ResultsT cell proliferation, activation and cytokine production were suppressed in the presence of milk EVs. Remarkably, milk EVs from allergic mothers inhibited T cell activation to a lesser extent than EVs from non-allergic mothers. Integrative multi-omics analysis identified EV cargo of which the cellular targets could be linked to differential modulation of T cell activation-associated processes . ConclusionsMilk EVs from non-allergic mothers are stronger inhibitors of T cell activation compared to milk EVs from allergic mothers. This altered functionality might be linked to changes in miRNA and protein cargo that modulate T cell signaling pathways in an integrative manner.

immunology↗

bioRxiv2020

Human milk extracellular vesicles target nodes in interconnected signalling pathways that enhance oral epithelial barrier function and dampen immune responses

Maternal milk is natures first functional food. It plays a crucial role in the development of the infants gastrointestinal (GI) tract and the immune system. Extracellular vesicles (EVs) are a heterogeneous population of lipid bilayer enclosed vesicles released by cells for intercellular communication and are a component of milk. Recently, we discovered that human milk EVs contain a unique proteome compared to other milk components. Here, we show that physiological concentrations of milk EVs support epithelial barrier function by increasing cell migration via the p38 MAPK pathway. Additionally, milk EVs inhibit agonist-induced activation of endosomal Toll like receptors TLR3 and TLR9. Furthermore, milk EVs directly inhibit activation of CD4+ T cells by temporarily suppressing T cell activation without inducing tolerance. We show that milk EV proteins target key hotspots of signalling networks that can modulate cellular processes in various cell types of the GI tract.

immunology↗

bioRxiv2019

AFM-based High-Throughput Nanomechanical Screening of Single Extracellular Vesicles

We herein describe an Atomic Force Microscopy (AFM)-based experimental procedure which allows the simultaneous mechanical and morphological characterization of several hundred individual nanosized vesicles within the hour timescale. When deposited on a flat rigid surface from aqueous solution, vesicles are deformed by adhesion forces into oblate spheroids whose geometry is a direct consequence of their mechanical stiffness. AFM image analysis can be used to quantitatively measure the contact angle of individual vesicles, which is a size-independent descriptor of their deformation and, consequently, of their stiffness. The same geometrical measurements can be used to infer vesicle diameter in its original, spherical shape. We demonstrate the applicability of the proposed approach to natural vesicles obtained from different sources, recovering their size and stiffness distributions by simple AFM imaging in liquid. We show how the combined EV stiffness/size readout is able to discriminate between subpopulations of vesicular and non-vesicular objects in the same sample, and between populations of vesicles with similar sizes but different mechanical characteristics. We also discuss a force spectroscopy calibration procedure to quantitatively link the stiffness of EVs to their average contact angle. Finally, we discuss expected extensions and applications of the methodology.

biophysics↗