Browsing by Autor "Elizabeth Barbosa"

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Innate immunity prevents tissue invasion by<i>Entamoeba histolytica</i>
(Canadian Science Publishing, 2008) Mineko Shibayama; Víctor Rivera‐Aguilar; Elizabeth Barbosa; Saúl Rojas‐Hernández; Adriana Jarillo‐Luna; Vı́ctor Tsutsumi; Judith Pacheco‐Yépez; Rafael Campos-Rodrı́guez
Although innate and adaptive immunity both play a role in amoebiasis, the mechanisms involved in the elimination of Entamoeba histolytica are poorly understood. To provide more information about the innate immune mechanisms that may confer protection against invasive amoebiasis, we administered inflammatory substances (bacillus Calmette-Guérin, lipopolysaccharide, complete Freund's adjuvant, or mineral oil) into the peritoneum of hamsters. The animals were then challenged with pathogenic trophozoites of E. histolytica and, after 7 days, the protective host response was analysed. We found that the nonspecific inflammatory response induced in the peritoneum was sufficient to prevent liver invasion by E. histolytica. In vitro experiments showed that the killing of trophozoites was mediated by peritoneal macrophages and a protein of 68 kDa with peroxidase activity.
Myeloperoxidase binds to and kills <i>Entamoeba histolytica</i> trophozoites
(Wiley, 2010) Judith Pacheco‐Yépez; Víctor Rivera‐Aguilar; Elizabeth Barbosa; Saúl Rojas‐Hernández; Rosa Adriana Jarillo‐Luna; Rafael Campos-Rodrı́guez
During amebic invasion, neutrophils are a key component in either protecting against invading trophozoites or contributing to tissue damage. Upon degranulating or being lysed, neutrophils release toxic substances that can kill amebas as well as damage host tissue. In a previous study we identified a protein from nonspecifically stimulated peritoneal exudates of hamster that has peroxidase and marked amebicidal activity. In the current study we analyzed the in vitro amebicidal effect of purified hamster myeloperoxidase (MPO). The results demonstrate that MPO must bind directly to the surface of Entamoeba histolytica trophozoites in order to carry out amebicidal activity by using the H(2) O(2) produced by the amebas themselves. Myeloperoxidase-incubated amebas showed important morphological and ultrastructural alterations that increased with incubation time. Changes included an increase of vacuoles in the cytoplasm, a decrease of glycogen, alterations of nuclear morphology and disturbances in the plasma membrane culminating in complete ameba destruction.