Viana SM, Montoya AL, Carvalho AM, de MendonƧa BS, Portillo S, et al.
Emerging microbes & infections ā¢
American tegumentary leishmaniasis (TL) caused by is characterized by a spectrum of clinical presentations, ranging from localized cutaneous ulcers (CL), mucosal (ML), or disseminated (DL) disease, to a subclinical (SC) asymptomatic form. Current diagnosis based on parasite culture and/or microscopy lacks sensitivity and specificity. Previous studies showed that patients with CL and ML have very high levels of -specific anti-Ī±-Gal antibodies. However, the native parasite Ī±-Gal glycotope(s) is(are) still elusive, thus they have not yet been explored for a more accurate TL diagnosis. Using a chemiluminescent immunoassay, we evaluated the seroreactivity of TL patients across its clinical spectrum, and of endemic (EC) and nonendemic healthy controls (NEC) against three synthetic neoglycoproteins (NGP29b, NGP30b, and NGP28b), respectively comprising the derived type-2 glycoinositolphospholipid (GIPL)-1 (GalĪ²1,3ManĪ±), GIPL-2 (GalĪ±1,3GalĪ²1,3ManĪ±), and GIPL-3 (GalĪ±1,6GalĪ±1,3GalĪ²) glycotopes. Contrary to NGP29b and NGP30b, NGP28b exhibited high sensitivity and specificity to a CL serum pool. More importantly, NGP28b reacted strongly and specifically with individual sera from distinct clinical forms of TL, especially with SC sera, with 94% sensitivity and 97% specificity, by post-two-graph receiver-operating characteristic curve analysis. Contrary to NGP29b, NGP28b showed low cross-reactivity with Chagas disease and control (NEC/EC) sera. Additionally, seroreactivity of CL patients against NGP28b was significantly decreased after successful chemotherapy, indicating that -specific anti-Ī±-Gal antibodies may serve as an early biomarker of cure in CL. Our data also points towards the applicability of type-2 GIPL-3-derived GalĪ±1,6GalĪ±1,3GalĪ² glycotope for the serological diagnosis of American TL, particularly of the subclinical form.
Anti-Ī±-Gal responses may exert a protective effect in falciparum malaria. However, the biological role of such antibodies is still unknown during Plasmodium vivax infections. We investigated IgG and IgM responses to Ī±-Gal in individuals with vivax malaria. Anti-Ī±-Gal IgG and IgM levels were higher in these patients than in controls, but no significant correlation was found between parasitaemia and anti-Ī±-Gal response, nor between this response and ABO blood group status. This is the first study to investigate anti-Ī±-Gal antibodies in P. vivax-infected patients; a larger survey is necessary to achieve a better understanding of host immune response during vivax malaria.
The anaphylaxis response is frequently associated with food allergies, representing a significant public health hazard. Recently, exposure to tick bites and production of specific IgE against Ī±-galactosyl (Ī±-Gal)-containing epitopes has been correlated to red meat allergy. However, this association and the source of terminal, non-reducing Ī±-Gal-containing epitopes have not previously been established in Brazil. Here, we employed the Ī±-1,3-galactosyltransferase knockout mouse (Ī±1,3-GalT-KO) model and bacteriophage QĪ²-virus like particles (QĪ²-VLPs) displaying GalĪ±1,3GalĪ²1,4GlcNAc (GalĪ±3LN) epitopes to investigate the presence of Ī±-Gal-containing epitopes in the saliva of Amblyomma sculptum, a species of the Amblyomma cajennense complex, which represents the main tick that infests humans in Brazil. We confirmed that the Ī±-1,3-galactosyltransferase knockout animals produce significant levels of anti-Ī±-Gal antibodies against the GalĪ±1,3GalĪ²1,4GlcNAc epitopes displayed on QĪ²-virus like particles. The injection of A. sculptum saliva or exposure to feeding ticks was also found to induce both IgG and IgE anti-Ī±-Gal antibodies in Ī±-1,3-galactosyltransferase knockout mice, thus indicating the presence of Ī±-Gal-containing epitopes in the tick saliva. The presence of Ī±-Gal-containing epitopes was confirmed by ELISA and immunoblotting following removal of terminal Ī±-Gal epitopes by Ī±-galactosidase treatment. These results suggest for the first known time that bites from the A. sculptum tick may be associated with the unknown etiology of allergic reactions to red meat in Brazil.
The Ī±-Gal antigen [GalĪ±(1,3)GalĪ²(1,4)GlcNAcĪ±] is an immunodominant epitope displayed by infective trypomastigote forms of Trypanosoma cruzi, the causative agent of Chagas disease. A virus-like particle displaying a high density of Ī±-Gal was found to be a superior reagent for the ELISA-based serological diagnosis of Chagas disease and the assessment of treatment effectiveness. A panel of sera from patients chronically infected with T. cruzi, both untreated and benznidazole-treated, was compared with sera from patients with leishmaniasis and from healthy donors. The nanoparticle-Ī±-Gal construct allowed for perfect discrimination between Chagas patients and the others, avoiding false negative and false positive results obtained with current state-of-the-art reagents. As previously reported with purified Ī±-Gal-containing glycosylphosphatidylinositol-anchored mucins, the current study also showed concentrations of anti-Ī±-Gal IgG to decrease substantially in patients receiving treatment with benznidazole, suggesting that the semiquantitative assessment of serum levels of this highly abundant type of antibody can report on disease status in individual patients.
Trypomastigote forms of Trypanosoma cruzi, the causative agent of Chagas Disease, shed extracellular vesicles (EVs) enriched with glycoproteins of the gp85/trans-sialidase (TS) superfamily and other Ī±-galactosyl (Ī±-Gal)-containing glycoconjugates, such as mucins. Here, purified vesicles from T. cruzi strains (Y, Colombiana, CL-14 and YuYu) were quantified according to size, intensity and concentration. Qualitative analysis revealed differences in their protein and Ī±-galactosyl contents. Later, those polymorphisms were evaluated in the modulation of immune responses (innate and in the chronic phase) in C57BL/6 mice. EVs isolated from YuYu and CL-14 strains induced in macrophages higher levels of proinflammatory cytokines (TNF-Ī± and IL-6) and nitric oxide via TLR2. In general, no differences were observed in MAPKs activation (p38, JNK and ERK 1/2) after EVs stimulation. In splenic cells derived from chronically infected mice, a different modulation pattern was observed, where Colombiana (followed by Y strain) EVs were more proinflammatory. This modulation was independent of the T. cruzi strain used in the mice infection. To test the functional importance of this modulation, the expression of intracellular cytokines after in vitro exposure was evaluated using EVs from YuYu and Colombiana strains. Both EVs induced cytokine production with the appearance of IL-10 in the chronically infected mice. A high frequency of IL-10 in CD4+ and CD8+ T lymphocytes was observed. A mixed profile of cytokine induction was observed in B cells with the production of TNF-Ī± and IL-10. Finally, dendritic cells produced TNF-Ī± after stimulation with EVs. Polymorphisms in the vesicles surface may be determinant in the immunopathologic events not only in the early steps of infection but also in the chronic phase.
Gazzinelli RT, Romanha AJ, Fontes G, Chiari E, Gazzinelli G, et al.
The Journal of protozoology ā¢
We observed a wide distribution of the carbohydrate epitopes galactosyl alpha(1-3)galactose (gal alpha1-3 gal), alpha-glucoside and alpha-mannoside in mono- and heteroxenic trypanosomatids by using fluorescein-labelled lectins of Euonymus europaeus (EE) and Concanavalin A (Con A) as well as sera from acute chagasic patients who have very high levels of anti-gal alpha(1-3)gal antibodies. The direct fluorescence test for gal alpha1-3 gal with EE was positive at minimum concentrations of 6 micrograms/ml for heteroxenic trypanosomatids and 0.7 micrograms/ml for monoxenic ones and for the plant parasite, Phytomonas. On the other hand, heteroxenic trypanosomatids that infect vertebrates bound ten-fold more Con A than monoxenic flagellates and Phytomonas. These data were confirmed in ELISA and Western Blot assays carried out with peroxidase-labelled EE and Con A. Euonymus europaeus recognized several glycoproteins in all trypanosomatids that we tested. Con A, however, recognized a glycoprotein cluster in heteroxenic protozoa, which ranging from 60-120 kDa, seemed to lack monoxenic parasites and Phytomonas. These findings suggest that alpha-D-mannose and alpha-D-glucose might play an important role in the interaction between trypanosomatids and vertebrate hosts.
