Naegleria fowleri: Contact-dependent secretion of electrondense granules (EDG)

Chávez‐Munguía, Bibiana; Villatoro, Lizbeth Salazar; Omaña‐Molina, Maritza; Rodríguez-Monroy, Marco Aurelio; Segovia-Gamboa, Norma; Martı́nez-Palomo, Adolfo

doi:10.1016/j.exppara.2014.03.027

Cited by 10 publications

(8 citation statements)

References 35 publications

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“…FLA species may also secrete different antimicrobial factors into their surroundings [ 40 , 42 , 43 ], and the fresh media supplements may have diluted any toxic factor produced by Acanthamoeba species, allowing X . oryzae to survive and multiply.…”

Section: Resultsmentioning

confidence: 99%

Interactions of free-living amoebae with rice bacterial pathogens Xanthomonas oryzae pathovars oryzae and oryzicola

et al. 2018

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BackgroundFree-living amoebae (FLA) are voracious feeders, consuming bacteria and other microbes during colonization of the phytobiome. FLA are also known to secrete bacteriocidal or bacteriostatic compounds into their growth environment.Methodology and principal findingsHere, we explore the impacts of co-cultivation of five FLA species, including Acanthamoeba castellanii, A. lenticulata, A. polyphaga, Dictyostelium discoideum and Vermamoeba vermiformis, on survival of two devastating bacterial pathogens of rice, Xanthomonas oryzae pathovars (pv.) oryzae and oryzicola. In co-cultivation assays, the five FLA species were either bacteriostatic or bactericidal to X. oryzae pv. oryzae and X. oryzae pv. oryzicola. Despite these effects, bacteria were rarely detected inside amoebal cells. Furthermore, amoebae did not disrupt X. oryzae biofilms. The bactericidal effects persisted when bacteria were added to a cell-free supernatant from amoebal cultures, suggesting some amoebae produce an extracellular bactericidal compound.Conclusions/SignificanceThis work establishes novel, basal dynamics between important plant pathogenic bacteria and diverse amoebae, and lays the framework for future mechanistic studies.

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Section: Resultsmentioning

confidence: 99%

Interactions of free-living amoebae with rice bacterial pathogens Xanthomonas oryzae pathovars oryzae and oryzicola

et al. 2018

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“…Release of EDGs has also been observed in experimental infections with Naegleria fowleri (Chávez‐Munguía et al. ) and during excystation of Naegleria sp. and Acanthamoeba castellanii (Chávez‐Munguía et al.…”

mentioning

confidence: 75%

“…Contact‐dependent release of EDGs has been reported in E. histolytica and N. fowleri following incubation with cultured epithelial cells or collagen substrates (Chávez‐Munguía et al. , ). Release of these granules has also been observed during excystation in A. castellanii, N. fowleri, and E. invadens (Chávez‐Munguía et al.…”

Section: Discussionmentioning

confidence: 99%

“…A common observation both in E. histolytica and in N. fowleri trophozoites recovered from experimental lesions has been the increased number of EDGs compared to EDGs in long‐term cultured parasites (Chávez‐Munguía et al. , ). In Acanthamoeba spp., up‐regulation of genes related with proteolytic activity and virulence has been reported after mouse brain passage of cultured trophozoites (Han et al.…”

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confidence: 99%

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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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“…By using this strategy, there will be no products originating from apoptotic or necrotic cells that attract and activate immune cells, which probably enables N. fowleri to invade without eliciting a strong immune response. Once past the epithelial lining, N. fowleri adheres to the extracellular matrix (ECM) by an integrin-like protein [19] and secretes a range of proteases [20][21][22][23] to break down the ECM (Figure 2C). In this way, N. fowleri penetrates the epithelium and swiftly migrates towards the central nervous system (CNS).…”

Section: Naegleria Fowleri Invasion Of the Brain Occurs Directly Via ...mentioning

confidence: 99%

Three encephalitis-causing amoebae and their distinct interactions with the host

Sarink

Meijs

Denzer

et al. 2022

Trends in Parasitology

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Naegleria fowleri: Contact-dependent secretion of electrondense granules (EDG)

Cited by 10 publications

References 35 publications

Interactions of free-living amoebae with rice bacterial pathogens Xanthomonas oryzae pathovars oryzae and oryzicola

Interactions of free-living amoebae with rice bacterial pathogens Xanthomonas oryzae pathovars oryzae and oryzicola

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

Three encephalitis-causing amoebae and their distinct interactions with the host

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