Unravelling the interactions of the environmental host<i>Acanthamoeba castellanii</i>with fungi through the recognition by mannose‐binding proteins

Gonçalves, Diego de Souza; Ferreira, Marina da Silva; Gomes, Kamilla Xavier; Noval, C.; Liedke, Susie Coutinho; Costa, Giovani Carlo Veríssimo da; Albuquerque, Patrícia; Cortines, Juliana R.; Peralta, Regina Helena Saramago; Peralta, José Mauro; Casadevall, Arturo; Guimarães, Allan J.

doi:10.1111/cmi.13066

Cited by 28 publications

(61 citation statements)

References 89 publications

(121 reference statements)

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“…The amoeba-passaged C. neoformans selected in our study differ from those reported in prior studies [24,39,76] in that they did not increase in virulence. Instead, we observed reductions in murine virulence for two of the isolates studied despite increased capacity to damage macrophages from their long interaction with amoeba.…”

Section: Discussioncontrasting

confidence: 83%

“…The 'amoeboid predator-fungal animal virulence hypothesis' formulates the notion that the capacity for virulence in soil fungi with no need for an animal host arose accidently from the traits for survival against ameboid predators that accidently also functioned as virulence factors for animal infection [12]. Consistent with this notion there is a remarkable concordance between fungal phenotypes that promote survival against amoeba and in animal hosts [14,23] and passage in amoeba is associated with increased virulence for several fungal species [24,39,76]. Analysis of virulence for the amoeba-selected strains described in our study in wax moths revealed no major changes in virulence from the parental strains.…”

Section: Discussionmentioning

confidence: 99%

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Amoeba predation ofCryptococcus neoformansresults in pleiotropic changes to traits associated with virulence

Liporagi-Lopes

Santos

et al. 2020

Preprint

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Phagocytic amoeboid predators such as amoeba have been proposed to select for survival traits in soil microbes such as Cryptococcus neoformans that can also function in animal virulence by defeating phagocytic immune cells, such as macrophages. Several prior studies have shown that incubation of various fungal species with amoeba can enhance their virulence. However, the mechanisms by which fungi adapt to amoeba and thus change their virulence are unknown. In this study we exposed three strains of C. neoformans (1 clinical and 2 environmental) to predation by Acanthamoeba castellanii for prolonged periods of time and then analyzed surviving colonies phenotypically and genetically. Surviving colonies were comprised of cells that expressed either pseudohyphal or yeast phenotypes, which demonstrated variable expression of such traits associated with virulence such as capsule size, urease production and melanization. Phenotypic changes were associated with aneuploidy and DNA sequence mutations in some amoeba-passaged isolates, but not in others. Mutations in the gene encoding for the oligopeptide transporter (CNAG_03013; OPT1) were observed among amoeba-passaged isolates from each of the three strains. In addition, isolates derived from environmental strains gained the capacity for enhanced macrophage toxicity after amoeba selection and carried mutations on the CNAG_00570 gene, which encodes Pkr1 (AMP-dependent protein kinase regulator) but were less virulence in mice because they elicited more effective fungal-clearing immune responses. Our results indicate that C. neoformans survival under constant amoeba predation involves the generation of strains expressing pleiotropic phenotypic and genetic changes, which confer increase resistance against protozoal predation. Given the myriad of potential predators in soils the diversity observed among amoeba-selected strains suggests a bet-hedging strategy whereby variant diversity increases the likelihood that some will survive predation.Author summaryCryptococcus neoformans is a ubiquitous environmental fungus that is also a leading cause of fatal fungal infection in humans, especially among immunocompromised patients. Cryptococcosis is a worldwide concern due to its high mortality rate. A major question in the field is how an environmental yeast such as C. neoformans becomes a human pathogen when it has no need for animal host in its life cycle. Previous studies showed evidence that C. neoformans increases its pathogenicity after interacting with its environmental predator amoebae. Amoebae behave like macrophages, an important immune cell in human body, so it is considered as a training ground for pathogens to resist macrophages. However, how C. neoformans changes its virulence through interacting with amoebae is unknown. Here, we exposed C. neoformans to amoebae for a long period of time. We found that C. neoformans cells recovered from amoebae manifested numerous changes to phenotypes related to its virulence and one of the amoeba-passaged C. neoformans cells had enhanced ability to kill macrophages. We further analyzed their genome sequences and found various mutations in different cells of amoeba-passaged C. neoformans, showing that DNA mutations may be the major cause of the phenotypic changes after interacting with amoebae. Our study indicates that fungal survival in the face of amoeba predation is associated with the emergence of pleiotropic phenotypic and genomic changes that increase the chance of fungal survival.

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Section: Discussioncontrasting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Amoeba predation ofCryptococcus neoformansresults in pleiotropic changes to traits associated with virulence

Liporagi-Lopes

Santos

et al. 2020

Preprint

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“…Our analyses indicated that S schenckii and S brasiliensis suffered phagocytic events by A castellanii , at a significantly higher rate for S schenckii in the first two hours compared to S brasiliensis. This could be explained by the hypothesis tested by Gonçalves et al that receptors on the surface of the amoeba participate differently in fungal recognition. Amoebae possess a variety of surface proteins, with different affinities for the fungal surface.…”

Section: Discussionmentioning

confidence: 99%

The interaction between Sporothrix schenckii sensu stricto and Sporothrix brasiliensis with Acanthamoeba castellanii

Tavares

Ribeiro

Berte

et al. 2019

Mycoses

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Summary Background Sporotrichosis is a group of zoonotic subcutaneous mycoses, found worldwide and caused by fungi belonging to the genus Sporothrix. Protozoans of the genus Acanthamoeba are widely distributed, and some species may be pathogenic and/or opportunistic. These organisms coexist in the same environment and may interact. Objectives This study determined the profile of interactions of S schenckii sensu stricto and S brasiliensis with A castellanii, using an in vitro co‐culture model to evaluate the intrinsic characteristics of the two Sporothrix species and A castellanii. Methods We compared the rate of phagocytosis of S schenckii sensu stricto and S brasiliensis by A castellanii; the viability of S schenckii sensu stricto and S brasiliensis after contact with A castellanii; the viability of the amoeba after contact with a fungal species; and the influence of S schenckii sensu stricto and S brasiliensis on the encystment process of A castellanii. Results The analyses indicated that A castellanii phagocytised both S schenckii and S brasiliensis, with significantly more S schenckii than S brasiliensis in the first two hours of contact. Our results showed a significant increase in conidia and hyphae count after 72 hours of co‐culture of A castellanii with S brasiliensis, and the amoebae lysed after they ingested the fungi, indicating that the fungi probably used the amoebae as a source of nutrition. Conclusions Our results were obtained in vitro and these organisms may not behave similarly in vivo; in vivo studies of co‐infections are necessary in order to gain a thorough understanding of this relationship.

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“…Fungus bind to amoeba with implication of mannose‐binding proteins 24 . Therefore, we verified whether the interaction of Tr with A. castellanii occurs through these receptors.…”

Section: Discussionmentioning

confidence: 84%

“…Trophozoites were treated with 1 mmol/L mannose 1 hour before challenging with Tr conidia, and then, phagocytosis, fungicidal activity and exocytosis were analysed as described above (section 2.5 and 2.6). 24 …”

Section: Methodsmentioning

confidence: 99%

Acanthamoeba castellanii as an alternative interaction model for the dermatophyte Trichophyton rubrum

Faria

Carmo

Costa

et al. 2020

Mycoses

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Summary Background Trichophyton rubrum (Tr) is the main aetiological agent of human dermatophytosis, being isolated from the environment and keratinised tissues. In the environment, Tr can interact with other organisms, such as free‐living amoebas (FLA), which can act as an alternative host system to study the interaction between microbes and phagocytic cells. Objectives To characterise the Acanthamoeba castellanii (ALX)‐Tr interaction. Methods Interaction was characterised in three conditions: trophozoites (PYG), late (PYG/NES) and early (NES) encystation stimulus, evaluating encystation kinetics, phagocytosis, exocytosis and fungicidal activity dynamics. Results Tr was able to induce ALX encystation and be internalised by ALX. The number of internalised conidia was high at 1 hour, and ALX presented fungicidal activity with increased intracellular ROS production and exocytosis. In PYG/NES, phagocytosis and ROS production were reduced, with decreased ALX’s fungicidal activity. However, in NES there was an increased fungal engulfment, and a reduced ROS production and higher fungal burden. Furthermore, exogenous mannose decreased phagocytosis of Tr conidia, and divalent cations induced ROS production and increased ALX’s fungicidal activity. Interestingly, phagocytosis was reduced in the presence of cytoskeleton inhibitor, but exocytosis was increased, suggesting that Tr conidia may have alternative pathways to escape ALX's cells. Conclusion A castellanii is a proper model for studying Tr‐FLA interaction, since ALX can engulf, produce ROS and kill Tr, and all these parameters are influenced by an encystation stimulus and divalent cations. Moreover, this interaction is likely to occur in the environment implicating in the adaptation to environmental stressful conditions in both organisms.

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Unravelling the interactions of the environmental hostAcanthamoeba castellaniiwith fungi through the recognition by mannose‐binding proteins

Cited by 28 publications

References 89 publications

Amoeba predation ofCryptococcus neoformansresults in pleiotropic changes to traits associated with virulence

Amoeba predation ofCryptococcus neoformansresults in pleiotropic changes to traits associated with virulence

The interaction between Sporothrix schenckii sensu stricto and Sporothrix brasiliensis with Acanthamoeba castellanii

Acanthamoeba castellanii as an alternative interaction model for the dermatophyte Trichophyton rubrum

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