Antibodies Enhance the Suppressive Activity of Extracellular Vesicles in Mouse Delayed-Type Hypersensitivity.

Katarzyna Nazimek,Olga Woźnicka,Eugenio Bustos-Morán,Francisco Sánchez-Madrid,Krzysztof Bryniarski,Rafał Szatanek,Justyna Totoń-Żurańska,Bernadeta Nowak,Michał T Seweryn,Philip W Askenase,Maciej Siedlar,Noelia Blas-Rus,Paweł Wołkow

doi:10.3390/ph14080734

Abstract

Previously, we showed that mouse delayed-type hypersensitivity (DTH) can be antigen-specifically downregulated by suppressor T cell-derived miRNA-150 carried by extracellular vesicles (EVs) that target antigen-presenting macrophages. However, the exact mechanism of the suppressive action of miRNA-150-targeted macrophages on effector T cells remained unclear, and our current studies aimed to investigate it. By employing the DTH mouse model, we showed that effector T cells were inhibited by macrophage-released EVs in a miRNA-150-dependent manner. This effect was enhanced by the pre-incubation of EVs with antigen-specific antibodies. Their specific binding to MHC class II-expressing EVs was proved in flow cytometry and ELISA-based experiments. Furthermore, by the use of nanoparticle tracking analysis and transmission electron microscopy, we found that the incubation of macrophage-released EVs with antigen-specific antibodies resulted in EVs’ aggregation, which significantly enhanced their suppressive activity in vivo. Nowadays, it is increasingly evident that EVs play an exceptional role in intercellular communication and selective cargo transfer, and thus are considered promising candidates for therapeutic usage. However, EVs appear to be less effective than their parental cells. In this context, our current studies provide evidence that antigen-specific antibodies can be easily used for increasing EVs’ biological activity, which has great therapeutic potential.

Highlights

Recent advances in studies on the biology of extracellular vesicles (EVs) demonstrated their exceptional role in intercellular communication [1], both in physiological and pathological conditions [2]
We cultured Ts-EV-treated macrophages isolated from picryl chloride (PCL)-sensitized mice in protein-free medium and collected the resulting supernatants after 90 min, 24 h and 48 h of the culture
The suppression of the subsequently elicited contact hypersensitivity (CHS) ear swelling response was observed in recipients of CHS effector cells pre-incubated with the pellet from ultracentrifuged supernatant collected from 24- and 48-h culture of Ts-EV-treated macrophages, while other supernatant preparations failed to modulate CHS reaction (Figure 1A)

Summary

Introduction

Recent advances in studies on the biology of extracellular vesicles (EVs) demonstrated their exceptional role in intercellular communication [1], both in physiological and pathological conditions [2]. EVs have been proposed to substitute for the activity of parental immune cells; they seem to be Pharmaceuticals 2021, 14, 734. Pharmaceuticals 2021, 14, 734 less effective [3]. EVs receive special attention as physiological delivery tools, the usage of which reduces the side effects of treatment. The latter application is still fraught with many challenges, including enhancing their biological effectiveness and directing them towards desired target cells [4].

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Conclusion