Matrix Bound Nanovesicles Modulatory Effect of Inflammation In Vitro in THP-1 Cells

Background: Matrix-bound nanovesicles (MBV) are extracellular vesicles (EVs) that are embedded within the extracellular matrix (ECM), and they have shown immunomodulatory effects in various cell types. The THP-1 cell line is often used to study monocyte and macrophage functions due to its easy culture potential and relatively simple conditioning into different macrophage phenotypes, but the optimal culturing conditions that allow MBV immunomodulation have not been established. Methods: In this study, we evaluated different culturing and differentiation conditions of THP-1 cells in which MBVs showed immunomodulatory effects. We also studied the effect of MBVs on relevant inflammation pathways (NF-κB and ERK 1/2). Results: Quantification of inflammatory cytokine IL-6 indicated modulation effects by MBVs in the majority of the conditions, but TNF-α showed very limited modulation. ERK1/p44 phosphorylation was significantly increased in MBV groups, but NF-κB protein p65 expression was unaffected. When compared to serum EVs, vesicle uptake by THP-1 cells remained low after 24 h. Multispectral flow cytometry analysis of THP-1 cells exposed to MBV and serum EVs showed internalization of lipids, proteins and RNA within the cells in higher cell proportions, but colocalization of the different vesicle components was not observed. Conclusions: Overall, this study provided insights into MBV immunomodulatory effects on THP-1 cells and compared the effects of MBV and serum EVs. Slight differences in modulation were observed between both EV sources, pointing to cargo differences that need further investigation.