Parasite Lectins: More than Adhesion Molecules?

Several studies demonstrate the involvement of lectins in the recognition of carbohydrates present on the surface of different kinds of pathogens [1-3], including parasites of the genus Leishmania [4,5]. The recognition often involves the modulation of the host immune response due to the activation of signaling pathways initiated by the stimulation of lectins present on the surface of cells from immune system by carbohydrates from pathogens [1,2]. On the other hand, lectins from microorganisms are also involved in infections: HeparinBinding Protein (HBP) from Trypanosoma cruzi are involved in processes of amastigote and epimastigotes adhesion to the mammalian host cells and to the intestinal epithelium of insects, respectively [6-8]. Furthermore, galactose/N-acetylgalactosamine (Gal/GalNAc) lectin is involved in the infection by Entamoeba histolytica, responsible for the third highest number of death from parasitic diseases in the world [9-11]. Other relevant lectins from parasites are involved in mediating protozoa attachment to the host cells, acting as valuable tools to study pathogenesis of infection: mannose lectin (MBP) from Acanthamoeba, causative agent of keratitis, mediates parasite adhesion to the host cells, and may serve as a marker of pathogenicity of this parasite; micronemal protein (MIC1), a Toxoplasma gondii adhesin, bind to host sialic acid moieties, playing role in the parasite invasion and virulence; Tritrichomonas foetus lectin (TFL), a sialic acid specific lectin, is involved in mucosal surface attachment and immunogenicity of Tritrichomonas foetus, a protozoan parasite of the bovine urogenital tract; and Cryptosporidium parvum Clec (CpClec), a novel mucin-like glycoprotein with a C-type lectin domain (CTLD), is involved in Cryptosporidium-host cell interactions [12].