Extracellular vesicles of Echinococcus sp. carry allergenic proteins involved in immune crosstalk with the host

NICOLAO MARÍA CELESTE; COCCIMIGLIO MAGALÍ; AMBROSIO RAFAEL; RODRIGUEZ R CHRISTIAN; CUMINO ANDREA C

Rockville

Workshop; Extracellular vesicle studies From benchtop to therapeutics; 2021

AMERICAN SOCIETY FOR BIOCHEMISTRY AND MOLECULAR BIOLOGY

Echinococcosis is a worldwide zoonotic infection caused by Echinococcus larval stage. Like other helminths, this cestode has the ability to establish chronic infections in which the secretion of immunomodulatory molecules has a central role in the continuous crosstalk with the mammalian host. In this context, parasitic extracellular vesicles (EVs) have been considered key components of parasite-host interaction. Here, we isolated EVs from control and anti-echinococcal drug-treated protoscolex cultures. EVs were defined as exosome-like vesicles by dynamic light scattering, TEM and proteomic analysis. This allowed identifying 20 antigen proteins and more than 40 proteins involved in host interaction and immune modulation. Particularly, we focus on E-cupin and E-profilin, two small proteins, which belong to the 10 most abundant allergenic protein families. We employed protein sequence and structure-based computational methods to identify putative allergenic-epitope regions. We determined by RT-PCR that both proteins are highly and ubiquitously expressedin the larval stage (protoscoleces and metacestodes) of E. granulosus and E. multilocularis. E-cupin (U6IZE6 of 105 amino-acid, Pfam CL0029, CATH:2.60.120.10) shows 50-85% identity with cyanobacteria and flatworm orthologs, respectively. It contains two characteristic motifs (G41(X)5HXH(X)2E(X)7G60 and G76(X)5PXG(X)2H(X)6N94), which comprise a set of highly conserved metal-coordinating histidines (H) employed as sugar and nucleotide-binding domains. Besides, this protein may possess enzyme activity for ketoenol tautomerization of carbohydrates due to it preserves a signature motif in the putative active site [R19F36 47H49F64R74H87L97E98F100K104], similarly to its structural prototype, 5fq0.1.A. On the other hand, E-Profilin (U6JIW0 of 125 residues, Pfam PF00235 as actin-binding protein) contains conserved and key basic residues (R and K), which can be linked to G-actin and polyphosphoinositide and are required for its cellular and extracellular roles, such as cytoskeletal reorganization, signal transduction, membrane and nuclear trafficking and vesicle recycling. Finally, additional studies facing recombinant proteins against host dendritic cells will shed some light on the understanding of the possible mechanisms that lead to an immune response for the EVsin this zoonosis.