Entamoeba histolytica is the causative agent of amebiasis in humans and is responsible for 100,000 deaths annually, making it the third leading cause of death due to a protozoan parasite. Pathogenesis appears to result from the potent cytotoxic activity of the parasite, which kills host cells within minutes. Although the mechanism is unknown, it is well established to be contact-dependent. The life cycle of the parasite alternates with two forms: the resistant cyst and the invasive trophozoite. The adhesive interactions between the parasite and surface glycoconjugates of host cells, as well as those lining the epithelia, are determinants for invasion of human tissues, for its cytotoxic activity, and finally for the outcome of the disease. In this review we present an overview of the information available on the amebic lectins and adhesins that are responsible of those adhesive interactions and we also refer to their effect on the host immune response. Finally, we present some concluding remarks and perspectives in the field.

Amoebiasis in humans is caused by the protozoan parasite Entamoeba histolytica, which cytotoxic activity has been demonstrated on a wide variety of target cells. The process involves the adherence of the parasite to the cell, and such adherence is mediated by an amoebic surface lectin, known as Gal/GalNAc lectin. It is composed of heavy, intermediate, and light subunits. The carbohydrate recognition domain (CRD) has been identified within a cysteine-rich region in the lectin heavy subunit and has an amino acid sequence identity to the receptor-binding domain of hepatocyte growth factor (HGF). Recombinant CRD has been previously shown to compete with HGF for binding to the c-Met receptor IgG fusion protein. In the present study, we searched for evidence of interaction between the Gal/GalNAc lectin at the surface of trophozoites with the c-Met receptor expressed at the surface of HepG2 in coculture assays. Immunoprecipitation of the coculture lysate indicated interaction of the c-Met with a 60 kDa peptide recognized by antiamoebic lectin antibody. Colocalization of both molecules was detected by fluorescence confocal microscopy. Incubation of HepG2 cells with HGF before coculture with trophozoites prevents the cytotoxic effect caused by the parasites but not their adherence to the cells. Our results point to Gal/GalNAc lectin as a ligand of the c-Met receptor at the surface of HepG2 cells.

Problem: Intrauterine infection is one of the most jeopardizing conditions associated with adverse outcomes, including preterm birth; however, multiple tolerance mechanisms operate at the maternal–fetal interface to avoid the rejection of the fetus. Among the factors that maintain the uterus as an immunoprivileged site, Galectin‐1 (Gal‐1), an immunomodulatory glycan‐binding protein secreted by the maternal‐fetal unit, is pivotal in promoting immune cell homeostasis. This work aimed to evaluate the role of Gal‐1 during a lipopolysaccharide (LPS)‐induced‐inflammatory milieu.Method of Study: Using an ex vivo culture with two independent compartments, human fetal membranes at term were pretreated with 40 and 80 ng/mL of Gal‐1, then to reproduce an intraamniotic inflammation, the fetal side of membranes was stimulated with 500 ng/mL of LPS for 24 h. The concentrations of tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, IL‐6, monocyte chemoattractant protein (MCP1), macrophage inflammatory protein (MIP1) α, regulated upon activation normal T cell expressed and secreted (RANTES), and matrix metalloproteinase (MMP)‐9 were measured in both amnion and choriodecidua compartments.Results: In a tissue‐specific fashion profile, pretreatment with the physiologic concentration of Gal‐1 significantly diminished the LPS‐dependent secretion of TNF‐α, IL‐1β, Il‐6, MCP1, MIP1α, RANTES, and MMP‐9.Conclusion: Gal‐1 elicits an anti‐inflammatory effect on the human fetal membranes stimulated with LPS, which supports the hypothesis that Gal‐1 is part of the immunomodulatory mechanisms intended to stop the harmful effect of inflammation of the maternal–fetal interface.

Background: Several studies describe an inverse statistical relationship between the presence of an allergy and development of cancer. However, the immunological mechanism involved in the relationship between these two degenerative diseases has not been explored.Aims: The main objective of this study was to explore the possibility that the lymphocyte T helper (Th) 2 response, a characteristic of allergy, induces recognition of tumor antigens.Methods and results: Patients with a clinical diagnosis of breast ductal carcinoma were included. Histopathological markers related to proliferation of tumor cells were determined (Her‐2‐neu, Ki‐67, estrogen receptor, and progesterone receptor). IHC was performed using IgE antibodies purified from an allergy patient and from each biopsy donor patient. Serum concentrations of cytokines representative of Th1 and Th2 inflammatory responses were determined. A total of 14 patients with a confirmed diagnosis of breast ductal carcinoma were included. IHC performed on biopsies showed a weak response when using purified IgE antibodies from an allergy patient; however, IHC using the IgE of each patient as the primary antibody showed an intense and highly specific signal. Serum concentrations of cytokines of the Th2 response, that is, IL‐4 (130.5 pg/mL (116–135 pg/mL)), IL‐5 (202 pg/mL (191–213 pg/mL)), and IL‐13 (105.5 pg/mL (98–117 pg/mL)), were significantly higher than those of the Th1 response, that is, IL‐6 (86 pg/mL (79–90 pg/mL)) and INF‐γ (93 pg/mL (79–99 pg/mL)).Conclusion: Purified IgE antibodies specifically recognize tumor cells in breast ductal carcinoma.