Acanthamoeba castellanii: Morphological analysis of the interaction with human cornea

Omaña‐Molina, Maritza; González‐Robles, Arturo; Salazar‐Villatoro, Lizbeth; Cristóbal-Ramos, Ana Ruth; González‐Lázaro, Mónica; Salinas-Moreno, Edmundo; Méndez-Cruz, Adolfo René; Sánchez-Cornejo, Manuel; Torre-González, Enrique De la; Martı́nez-Palomo, Adolfo

doi:10.1016/j.exppara.2010.02.004

Cited by 14 publications

(19 citation statements)

References 31 publications

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“…), and the initial binding of the parasite leads to secondary events, such as phagocytosis (Omaña‐Molina et al. ) and toxin production (Sissons et al. ).…”

Section: Discussionmentioning

confidence: 99%

Acanthamoeba castellanii Proteases are Capable of Degrading Iron‐Binding Proteins as a Possible Mechanism of Pathogenicity

Ramírez-Rico¹,

Martínez-Castillo²,

Garza³

et al. 2015

J Eukaryotic Microbiology

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Acanthamoeba castellanii, a free-living amoeba, is an amphizoic organism that can behave as an opportunistic pathogen, causing granulomatous amoebic encephalitis in immunocompromised patients or infecting immunocompetent individuals via cutaneous lesions, sinusoidal infections, or amoebic keratitis. Therefore, this amoeba could be in contact with different iron-binding proteins, such as lactoferrin in tears and mucosa and transferrin and hemoglobin in blood. Iron is a vital and necessary element for host metabolism but also for parasite survival. Accordingly, parasites have developed iron uptake mechanisms, one of which is the utilization of proteases to degrade host iron-binding proteins. In this work, we performed a partial biochemical characterization of A. castellanii proteases at different pHs and utilizing protease inhibitors with 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and copolymerized with different iron-binding proteins. We describe for the first time the presence of several cysteine proteases in a total A. castellanii crude extract and in conditioned culture medium precipitated with ethanol. These amoebic peptidases degraded human holo-lactoferrin, holo-transferrin, hemoglobin, and horse spleen ferritin; some of these proteases were substrate specific, and others degraded multiple substrates. These proteases could be considered virulence factors that promote iron acquisition from the host.

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“…), and the initial binding of the parasite leads to secondary events, such as phagocytosis (Omaña‐Molina et al. ) and toxin production (Sissons et al. ).…”

Section: Discussionmentioning

confidence: 99%

Acanthamoeba castellanii Proteases are Capable of Degrading Iron‐Binding Proteins as a Possible Mechanism of Pathogenicity

Ramírez-Rico¹,

Martínez-Castillo²,

Garza³

et al. 2015

J Eukaryotic Microbiology

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“…The results observed in this study show that conditioned medium may promote the separation between the cells, leaving small spaces between them, which may facilitate the passage of amoebae between cell junctions. Besides we have proved that conditioned medium alone is able to damage only the most superficial human corneal tissue but amoebae invade and phagocyte epithelial cells reaching the Bowman layer of human cornea [17]. Ruqaiyyah and Khan [35], with reference to contact-independent factors of Acanthamoeba, have mentioned that these amoebae possess hydrolytic enzymes including elastases, phospholipases, glycosidases and a variety of serine, cysteine and metalloproteases, and ensure that their precise mechanisms of action at the molecular level are only beginning to emerge.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, it has also been demonstrated that if Acanthamoeba trophozoites are cocultured with isolated hamster and human corneas, the amoebae are able to invade and cause damage to the intact corneal epithelium, without the requirement of a previous corneal abrasion [17, 18]. …”

Section: Introductionmentioning

confidence: 99%

Reevaluating the Role ofAcanthamoebaProteases in Tissue Invasion: Observation of Cytopathogenic Mechanisms on MDCK Cell Monolayers and Hamster Corneal Cells

Omaña‐Molina

González‐Robles²,

Salazar‐Villatoro³

et al. 2013

BioMed Research International

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The morphological analysis of the cytopathic effect on MDCK cell monolayers and hamster cornea and qualitative and quantitative analyses of conditioned medium and proteases were evaluated and compared between two strains of Acanthamoeba genotype T4. Further than highlighting the biological differences found between both strains, the most important observation in this study was the fact that proteases both in total extracts and in conditioned medium are apparently not determinant in tissue destruction. An interestingly finding was that no lysis of corneal tissue was observed as it was previously suggested. These results, together with previous studies, allow us to conclude that the invasion and disruption of corneal tissue is performed by the penetration of the amoebae through cell junctions, either by the action of proteases promoting cellular separation but not by their destruction and/or a mechanical effect exerted by amoebae. Therefore, contact-dependent mechanisms in Acanthamoeba pathogenesis are more relevant than it has been previously considered. This is supported because the phagocytosis of recently detached cells as well as those attached to the corneal epithelium leads to the modification of the cellular architecture facilitating the migration and destruction of deeper layers of the corneal epithelium.

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“…pathogenesis are complex and have not been completely elucidated. The process includes contact-dependent and contact-independent events (Omaña-Molina et al 2010). Among the former, acanthopodia, characteristic of this amoeba, participate in adhesion and tissue invasion, as well as phagocytosis of target cells.…”

Section: Discussionmentioning

confidence: 99%

Acanthamoeba culbertsoni: Electron‐Dense Granules in a Highly Virulent Clinical Isolate

Chávez‐Munguía¹,

Salazar‐Villatoro²,

Omaña‐Molina

et al. 2016

J Eukaryotic Microbiology

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The virulence of various amoebic parasites has been correlated with the presence of electron-dense granules (EDGs) in the cytoplasm of trophozoites. Here, we report the finding by transmission electron microscopy of a large number of EDGs in a recent culture of Acanthamoeba culbertsoni, isolated from a severe case of human keratitis. When this isolate was maintained in culture for 6 mo, the granules almost disappeared. However, after induction of mice brain lesions with the long-term cultured isolate, recovered amoebas had abundant EDGs. Trophozoites of the original isolate, or those recovered from experimental lesions, secreted EDGs into the medium when incubated with MDCK cells. To analyze a possible cytotoxic effect the conditioned medium was incubated with MDCK monolayers. After 5 h, the media containing EDGs produced opening of the tight junctions; at 24 h, cell viability was compromised, and at 48 h most of the cells were detached from the monolayer. In contrast, trophozoites in long-term cultures did not release EDGs to the medium during incubation with MDCK cells, and the corresponding conditioned medium did not have any effect on MDCK monolayers. Our observations further support the hypothesis that EDGs play a role in the cytopathogenic mechanisms of A. culbertsoni.

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Acanthamoeba castellanii: Morphological analysis of the interaction with human cornea

Cited by 14 publications

References 31 publications

Acanthamoeba castellanii Proteases are Capable of Degrading Iron‐Binding Proteins as a Possible Mechanism of Pathogenicity

Acanthamoeba castellanii Proteases are Capable of Degrading Iron‐Binding Proteins as a Possible Mechanism of Pathogenicity

Reevaluating the Role ofAcanthamoebaProteases in Tissue Invasion: Observation of Cytopathogenic Mechanisms on MDCK Cell Monolayers and Hamster Corneal Cells

Acanthamoeba culbertsoni: Electron‐Dense Granules in a Highly Virulent Clinical Isolate

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