Antibodies against Mucin‐Based Glycopeptides Affect Trypanosoma cruzi Cell Invasion and Tumor Cell Viability

Abstract

This study describes the synthesis of glycopeptides NHAc[βGal]-(Thr)2 -[αGalNAc]-(Thr)2 -[αGlcNAc]-(Thr)2 Gly-OVA (1-OVA) and NHAc[βGal-αGalNAc]-(Thr)3 -[αLacNAc]-(Thr)3 -Gly-OVA (2-OVA) as mimetics of both T. cruzi and tumor mucin glycoproteins. These glycopeptides were obtained by solid-phase synthesis, which involved the prior preparation of the protected glycosyl amino acids αGlcNAc-ThrOH (3), αGalNAc-ThrOH (4), βGal-ThrOH (5), αLacNAc-ThrOH (6), and βGal-αGalNAc-ThrOH (7) through glycosylation reactions. Immunizations of mice with glycopeptides 1-OVA and 2-OVA induced high antibody titers (1:16 000), as verified by ELISA tests, whereas flow cytometry assays showed the capacity of the obtained anti-glycopeptides 1-OVA and 2-OVA antibodies to recognize both T. cruzi and MCF-7 tumor cells. In addition, antisera induced by glycopeptides 1-OVA and 2-OVA were also able to inhibit T. cruzi fibroblast cell invasion (70 %) and to induce antibody-mediated cellular cytotoxicity (ADCC) against MCF-7 cells, with 50 % reduction of cell viability.

Comprehensive glycoprofiling of the epimastigote and trypomastigote stages of Trypanosoma cruzi

“…This mechanism plays diverse and important biological functions to protect the parasite against the alternative complement pathways of the host [43], to promote the host cell adhesion and invasion [11,[44][45][46] and in more general terms to escape of the host immune system [47]. Currently, members of the T. cruzi TS family are being investigated as potential vaccines against Chagas disease [48][49][50].…”

A Synthetic MUC1 Glycopeptide Bearing βGalNAc‐Thr as a Tn Antigen Isomer Induces the Production of Antibodies against Tumor Cells

“…In this context, for the synthesis of the glycosylated amino acid αGalNAc‐ThrOH (Tn; 5 ), we made use of our established glycosylation method employing HgBr 2 , by which glycosylation of FmocThr benzyl ester ( 7 ) with the azido‐derived glycosyl donor αGal(OAc) 3 N 3 Cl ( 8 ; Scheme S1), unable to exhibit any neighboring group effect, afforded exclusively the α isomer αGalN 3 ‐ThrOBn ( 9 , 78 %, Scheme S1) . Subsequently, the sugar azido group of 9 was reductively acetylated by treatment with zinc powder in THF/acetic anhydride/acetic acid, and its benzyl ester group was removed by standard hydrogenolysis (H 2 , 10 % Pd‐C, 1 h), giving the αGalNAc‐ThrOH derivative 5 (60 %) to be utilized in the solid‐phase synthesis of glycopeptide 3 (Scheme S1).…”

“…Solid‐phase synthesis of glycopeptides 3 and 4 : Moving towards the MUC1 glycopeptides 3 and 4 , solid‐phase glycopeptide synthesis (SPPS) was employed, utilizing commercial Wang resin pre‐loaded with Fmoc‐Gly (0.65 mmol g −1 resin) as the solid support and following the orthogonal Fmoc‐based SPPS . Thus, after removal of N ‐Fmoc groups with 50 % morpholine in DMF, the amino acid building blocks were coupled in the presence of the coupling reagents benzotriazol‐1‐yloxytripyrrolidinophosphonium hexafluorophosphate (PyBOP) and 1‐hydroxy‐1 H ‐benzotriazole (HOBt), together with N , N ‐diisopropylethylamine (DIPEA), in DMF.…”

The Trypomastigote Small Surface Antigen (TSSA) regulates Trypanosoma cruzi infectivity and differentiation

“…Alternatively, certain βGal p terminal units of tGPI-mucins may become modified with αGal p residues within the parasite secretory pathway, which generates highly antigenic structures and precludes their further elaboration with SA on the trypomastigote membrane [ 22 ]. Importantly, SA-containing neo-glycotopes on tGPI-mucins are involved in trypomastigote recognition and invasion of mammalian cells [ 23 , 24 ], as well as in providing protection against lytic antibodies [ 11 ] and/or complement opsonization [ 25 ]. In addition to their surface-associated roles, tGPI-mucins are also shed to the milieu as part of multi-cargo and multi-tasking micro-vesicles (MVs) that bud from the trypomastigote plasma membrane [ 26 , 27 ].…”