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

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.

Increasing the Therapeutic Efficacy of Extracellular Vesicles From the Antigen-Specific Antibody and Light Chain Perspective

“…On the other hand, almost 20 years ago it was observed that cross-linking of major histocompatibility complex (MHC) class II-expressing EVs with latex beads greatly augments their biological effectiveness ( Vincent-Schneider et al, 2002 ). Similar enhancement was recently demonstrated by us after aggregating MHC class II-expressing EVs with antigen-specific antibodies ( Nazimek et al, 2021 ). These findings imply that EV’s aggregation may increase not only their half-life in circulation, as mentioned above, but also the amount of vesicles targeting desired cell population ( Figures 1 , 2 ).…”

“…Moreover, it can be hypothesized that EV’s aggregation together with directing them towards desired target tissue or cell population will greatly enhance their therapeutic efficacy. As discussed below, our results showed that this could be achieved by incubating EVs with antigen-specific antibodies ( Nazimek et al, 2021 ) ( Figure 1 ).…”

“…The latter fits in with the consideration of the optimal EV’s dosing at a single cell scale and at the body scale ( Gupta et al, 2021 ). Proposed by us EV’s aggregation with antigen-specific antibodies takes an advantage over the latex beads, since antibodies could be safely degraded intracellularly, could limit the unwanted clearance of EVs by phagocytes, and may increase the specificity of cell targeting ( Nazimek et al, 2021 ). Besides, one can assume that EV’s could be similarly aggregated with antibodies directed against their surface proteins, which greatly extends the application spectrum of this phenomenon ( Figure 2 ).…”

“…However, chosen surface molecules bound by aggregating antibodies cannot be involved in EV’s cellular uptake to not disturb this process. The latter is implied by the observation that the attempts to use anti-CD9 antibodies abolished the immune activity of EVs ( Nazimek et al, 2021 ).…”

Extracellular Vesicles—Oral Therapeutics of the Future

“…Remarkably, intragastric administration of miRNA-150-transmitting EVs to mice with elicited cutaneous symptoms of delayed-type hypersensitivity to food allergens, i.e., ovalbumin and casein, significantly ameliorated the course of the contact allergic reaction [ 108 , 109 ]. Based on our other research findings [ 110 ], we suspect that miRNA-carrying EVs could be endocytosed by macrophages in the digestive tract, which would stimulate these cells to release secondary EVs inducing a tolerogenic effect at distant tissues. Altogether, our findings provide research evidence for the possible application of immune regulatory EVs for oral treatment of various diseases, including allergies and autoimmunity diseases [ 111 ].…”