In vitro Treatment of a Murine Mammary Adenocarcinoma Cell Line with Recombinant Trypanosoma cruzi Calreticulin Promotes Immunogenicity and Phagocytosis

American Trypanosomiasis, a parasitic disease produced by Trypanosoma cruzi (T. cruzi), endemic in Latin America, infects about 6 million people. During the chronic stage of the infection, approximately 30% of infected people will develop Chagas Disease, the clinical manifestation. Few decades ago it was reported that, during the chronic stage, the parasite interferes with the development of solid tumors. However, the identification of parasite molecules responsible for such effects remained elusive. Years later, we described T.cruzi Calreticulin (TcCalr), an endoplasmic reticulum resident chaperone that infective trypomastigotes translocate to the parasite exterior, where it displays anticomplement activities. Most likely, at least some of these activities are related with the antitumor properties of TcCalr, as shown in in vitro, ex vivo, in ovum, and in vivo models. In this context we, we have seen that in vivo subcutaneous peritumoral inoculation of rTcCalr enhances local infiltration of T cells and slows tumor development. Based on these precedents, we propose that in vitro treatment of a mammary adenocarcinoma (TA3 cell line) with rTcCalr, will enhance tumor immunogenicity. In agreement with this proposal, we have shown that: i). rTcCalr binds to TA3 cells in a concentration-dependent fashion, ii). C1q binds to TA3 cells in an rTcCalr-dependent fashion, confirmed by the reversion attained using anti-TcS (a central TcCalr domain that binds C1) F(ab')(2) antibody fragments, iii). incubation of TA3 cells with rTcCalr, promotes cell phagocytosis by murine macrophages and, iv). rTcCalr decreases the membrane expression of MHC class II, m-Dectin-1, Galectin-9 and PD-L1, while increasing the expression of Rae-1.. In synthesis, herein we show that in vitro treatment of a murine mammary adenocarcinoma with rTcCalr enhances phagocytosis and modulates the expression of a variety of membrane molecules that correlates with increased tumor immunogenicity.Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) CONICYT FONDECYT 1130099 VID-University of Chil

Exogenous Calreticulin, incorporated onto non-infective Trypanosoma cruzi epimastigotes, promotes their internalization into mammal host cells

© 2016 Elsevier GmbH Chagas disease is an endemic pathology in Latin America, now emerging in developed countries, caused by the intracellular protozoan Trypanosoma cruzi, whose life cycle involves three stages: amastigotes, epimastigotes, and trypomastigotes. T. cruzi Calreticulin (TcCRT), an endoplasmic reticulum resident chaperone, translocates to the external cellular membrane, where it captures complement component C1, ficolins and MBL, thus inactivating the classical and lectin pathways. Trypomastigote-bound C1 is detected as an “eat me” signal by macrophages and promotes the infective process. Unlike infective trypomastigotes, non-infective epimastigotes either do not express or express only marginal levels of TcCRT on their external membrane. We show that epimastigotes bind exogenous rTcCRT to their cellular membrane and, in the presence of C1q, this parasite form is internalized into normal fibroblasts. On the other hand, Calreticulin (CRT)-deficient fibroblasts show impaire

Roles of Trypanosoma cruzi calreticulin in parasite-host interactions and in tumor growth

In Latin America, there are about 10-12 million people infected with Trypanosoma cruzi, the agent of Chagas' disease, one of the most important neglected tropical parasitism. Identification of molecular targets, specific for the aggressor or host cells or both, may be useful in the development of pharmacological and/or immunological therapeutic tools. Classic efforts in Chagas' disease explore those strategies. Although the immune system frequently controls parasite aggressions, sterile immunity is seldom achieved and chronic interactions are thus established. However, laboratory-modified immunologic probes aimed at selected parasite targets, may be more effective than their unmodified counterparts. Calreticulin (CRT) from vertebrates is a calcium binding protein, present mainly in the endoplasmic reticulum (ER), where it directs the conformation of proteins and controls calcium levels. We have isolated, gene-cloned, expressed and characterized T. cruzi calreticulin (TcCRT). Upon infe

Molluskan hemocyanins activate the classical pathway of the human complement system through natural antibodies

© 2017 Pizarro-Bauerle, Maldonado, Sosoniuk-Roche, Vallejos, López, Salazar-Onfray, Aguilar-Guzmán, Valck, Ferreira and Becker. Molluskan hemocyanins are enormous oxygen-carrier glycoproteins that show remarkable immunostimulatory properties when inoculated in mammals, such as the generation of high levels of antibodies, a strong cellular reaction, and generation of non-specific antitumor immune responses in some types of cancer, particularly for superficial bladder cancer. These proteins have the ability to bias the immune response toward a Th1 phenotype. However, despite all their current uses with beneficial clinical outcomes, a clear mechanism explaining these properties is not available. Taking into account reports of natural antibodies against the hemocyanin of the gastropod Megathura crenulata [keyhole limpet hemocyanin (KLH)] in humans as well as other vertebrate species, we report here for the first time, the presence, in sera from unimmunized healthy donors, of antibodies re