INTRODUCTION
Anaphylaxis is the most severe manifestation of allergic disorders being
a systemic hypersensitivity life-threatening reaction that usually
evolves rapidly [1;2]. Currently, 50-112 cases per 100.000 habitants
are registered per year, but this incidence seems to be underestimated
[3]. The plethora of features associated to anaphylaxis confers
difficulties to its diagnosis, thus impairing the ability to treat
adequately these severe reactions. The only marker currently used in
clinical practice is the serum tryptase, however levels of this molecule
are not altered in all cases [4;5]. High-throughput and systems
biology analysis (SBA) implementation allow gaining knowledge on novel
clues of action, aimed to improve patients´ management towards a
personalized medicine for allergy treatment [6]. Different
phenotypes and underlying anaphylactic endotypes have been described
based on a few diagnostic biomarkers [7;8]. The current criteria to
define anaphylaxis is clinical, however considering the pleiotropic
features of the reactions, the approach to precision medicine evolves
towards a larger knowledge of the etiopathogenesis. Mechanistically,
anaphylactic reactions are established, but it is necessary to set up
cellular and molecular processes beyond IgE, mast cells and tryptase
[4;9;10]. Among the affected systems, cutaneous symptoms are the
most frequent, but the respiratory and circulatory ones are relevant in
the onset of severe anaphylactic reactions. The vessels stand out due to
the increased vascular permeability and vasodilation that occurs during
this pathological response, which promotes the development of
anaphylactic shock [11]. The systemic nature of the anaphylactic
reaction demands new approaches to improve diagnosis and molecular
characterization.
Extracellular vesicles (EVs) is the generic term for a heterogeneous
group of particles naturally released by most cell types, delimited by a
lipid bilayer and that cannot replicate [12;13]. A growing body of
evidence points to EVs as an efficient system to transfer targeted
information to recipient cells playing an active role in cell-to-cell
communication [14]. They carry molecular determinants from their
origin including nucleic acids, proteins, lipids and others [15].
EVs biological functions are wide and include antigen presentation,
angiogenesis, inflammation and coagulation. Importantly for the allergy
field, recent findings identify exosomes as important in the progression
of asthma [16;17]. Exosomes are the most known sub-family of EVs and
have been deeply studied in immunity and cancer [18;19]. Mast cells,
basophils and other members of the immune system secrete EVs creating a
dynamic network that could be crucial for the anaphylactic response
[20]. The soluble nature of EVs, their presence in all the
biological fluids and their early detection in many different
pathologies propose them as an economic and promising tool for diagnosis
[21;22]. Even more, proteomic analysis of EVs has been recently
proposed as a bona fide diagnosis method for some cancers
[23]. EVs profiling and their role in human anaphylaxis has not been
reported.
In this study, we have performed a quantitative proteomic signature of
plasma circulating anaphylaxis-derived EVs and point to clarify their
biological and functional properties. In addition, an in vitroevaluation of the endothelial barrier function has been carried out in
response to these particles.