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Nasher F, Wren BW. Unravelling mechanisms of bacterial recognition by Acanthamoeba: insights into microbial ecology and immune responses. Front Microbiol 2024; 15:1405133. [PMID: 39247694 PMCID: PMC11377244 DOI: 10.3389/fmicb.2024.1405133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 08/08/2024] [Indexed: 09/10/2024] Open
Abstract
Acanthamoeba, are ubiquitous eukaryotic microorganisms, that play a pivotal role in recognizing and engulfing various microbes during predation, offering insights into microbial dynamics and immune responses. An intriguing observation lies in the apparent preference of Acanthamoeba for Gram-negative over Gram-positive bacteria, suggesting potential differences in the recognition and response mechanisms to bacterial prey. Here, we comprehensively review pattern recognition receptors (PRRs) and microbe associated molecular patterns (MAMPs) that influence Acanthamoeba interactions with bacteria. We analyze the molecular mechanisms underlying these interactions, and the key finding of this review is that Acanthamoeba exhibits an affinity for bacterial cell surface appendages that are decorated with carbohydrates. Notably, this parallels warm-blooded immune cells, underscoring a conserved evolutionary strategy in microbial recognition. This review aims to serve as a foundation for exploring PRRs and MAMPs. These insights enhance our understanding of ecological and evolutionary dynamics in microbial interactions and shed light on fundamental principles governing immune responses. Leveraging Acanthamoeba as a model organism, provides a bridge between ecological interactions and immunology, offering valuable perspectives for future research.
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Affiliation(s)
- Fauzy Nasher
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Brendan W Wren
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Wang YJ, Li SC, Lin WC, Huang FC. Intracellular Microbiome Profiling of the Acanthamoeba Clinical Isolates from Lens Associated Keratitis. Pathogens 2021; 10:pathogens10030266. [PMID: 33669045 PMCID: PMC7996525 DOI: 10.3390/pathogens10030266] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 11/16/2022] Open
Abstract
Acanthamoeba act as hosts for various microorganisms and pathogens, causing Acanthamoeba Keratitis (AK). To investigate the association between endosymbionts and AK progression, we performed a metagenomics study to characterize the intracellular microbiome from five lenses associated with AK isolates and standard strains to characterize the role of ocular flora in AK progression. The used clinical isolates were axenic cultured from lenses associated with AK patients. AK isolates and standard controls such as 16S ribosomal RNA sequencing techniques were used for analysis. The microbiome compositions and relative abundance values were compared. The orders of Clostridiales and Bacteroidales presented major populations of intracellular microbes belonging to all isolates. Comparison of the different source isolates showed that most of the abundance in keratitis isolates came from Ruminococcus gnavus (121.0 folds), Eubacterium dolichum (54.15 folds), Roseburia faecis (24.51 folds), and Blautia producta (3.15 folds). Further analysis of the relative abundance data from keratitis isolates showed that Blautia producta was positively correlated with the disease course. In contrast, Bacteroides ovatus was found to be abundant in early-stage keratitis isolates. This study reveals the abundant anaerobic Gram-positive rods present in severe keratitis isolate and characterize the association between Acanthamoeba and ocular flora in AK progression.
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Affiliation(s)
- Yu-Jen Wang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan;
| | - Sung-Chou Li
- Genomics and Proteomics Core Laboratory, Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 83325, Taiwan;
| | - Wei-Chen Lin
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan;
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Correspondence: (W.-C.L.); (F.-C.H.); Tel.: +886-6-2353535 (ext. 5584) (W.-C.L.); +886-2353535 (ext. 5441) (F.-C.H.)
| | - Fu-Chin Huang
- Department of Ophthalmology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
- Correspondence: (W.-C.L.); (F.-C.H.); Tel.: +886-6-2353535 (ext. 5584) (W.-C.L.); +886-2353535 (ext. 5441) (F.-C.H.)
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3
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Soil Pollution from Micro- and Nanoplastic Debris: A Hidden and Unknown Biohazard. SUSTAINABILITY 2020. [DOI: 10.3390/su12187255] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The fate, properties and determination of microplastics (MPs) and nanoplastics (NPs) in soil are poorly known. In fact, most of the 300 million tons of plastics produced each year ends up in the environment and the soil acts as a log-term sink for these plastic debris. Therefore, the aim of this review is to discuss MP and NP pollution in soil as well as highlighting the knowledge gaps that are mainly related to the complexity of the soil ecosystem. The fate of MPs and NPs in soil is strongly determined by physical properties of plastics, whereas negligible effect is exerted by their chemical structures. The degradative processes of plastic, termed ageing, besides generating micro-and nano-size debris, can induce marked changes in their chemical and physical properties with relevant effects on their reactivity. Further, these processes could cause the release of toxic oligomeric and monomeric constituents from plastics, as well as toxic additives, which may enter in the food chain, representing a possible hazard to human health and potentially affecting the fauna and flora in the environment. In relation to their persistence in soil, the list of soil-inhabiting, plastic-eating bacteria, fungi and insect is increasing daily. One of the main ecological functions attributable to MPs is related to their function as vectors for microorganisms through the soil. However, the main ecological effect of NPs (limited to the fraction size < than 50 nm) is their capacity to pass through the membrane of both prokaryotic and eukaryotic cells. Soil biota, particularly earthworms and collembola, can be both MPs and NPs carriers through soil profile. The use of molecular techniques, especially omics approaches, can gain insights into the effects of MPs and NPs on composition and activity of microbial communities inhabiting the soil and into those living on MPs surface and in the gut of the soil plastic-ingesting fauna.
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Rillig MC, Bonkowski M. Microplastic and soil protists: A call for research. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 241:1128-1131. [PMID: 30029321 PMCID: PMC6485376 DOI: 10.1016/j.envpol.2018.04.147] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/28/2018] [Accepted: 04/28/2018] [Indexed: 05/19/2023]
Abstract
Microplastic is an emerging contaminant of concern in soils globally, probably gradually increasing in soil due to slow degradation. Few studies on microplastic effects on soil biota are available, and no study in a microplastic contamination context has specifically addressed soil protists. Soil protists, a phylogenetically and functionally diverse group of eukaryotic, unicellular soil organisms, are major consumers of bacteria in soils and are potentially important vehicles for the delivery of microplastics into the soil food chain. Here we build a case for focusing research on soil protists by drawing on data from previous, older studies of phagocytosis in protist taxa, which have long made use of polystyrene latex beads (microspheres). Various soil-borne taxa, including ciliates, flagellates and amoebae take up microplastic beads in the size range of a few micrometers. This included filter feeders as well as amoebae which engulf their prey. Discrimination in microplastic particle uptake depended on species, physiological state as well as particle size. Based on the results of the studies we review here, there is now a need to study microplastic effects in a pollution ecology context: this means considering a broad range of particle types under realistic conditions in the soil, and exploring longer-term effects on soil protist communities and functions.
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Affiliation(s)
- Matthias C Rillig
- Freie Universität Berlin, Institut für Biologie, Altensteinstr. 6, D-14195, Berlin, Germany; Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), D-14195, Berlin, Germany.
| | - Michael Bonkowski
- Universität zu Köln, Institut für Zoologie, Zülpicher Str 47b, D-50674, Köln, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Germany
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Madu UL, Ogundeji AO, Mochochoko BM, Pohl CH, Albertyn J, Swart CW, Allwood JW, Southam AD, Dunn WB, May RC, Sebolai OM. Cryptococcal 3-Hydroxy Fatty Acids Protect Cells Against Amoebal Phagocytosis. Front Microbiol 2015; 6:1351. [PMID: 26696972 PMCID: PMC4673343 DOI: 10.3389/fmicb.2015.01351] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 11/16/2015] [Indexed: 11/21/2022] Open
Abstract
We previously reported on a 3-hydroxy fatty acid that is secreted via cryptococcal capsular protuberances - possibly to promote pathogenesis and survival. Thus, we investigated the role of this molecule in mediating the fate of Cryptococcus (C.) neoformans and the related species C. gattii when predated upon by amoebae. We show that this molecule protects cells against the phagocytic effects of amoebae. C. neoformans UOFS Y-1378 (which produces 3-hydroxy fatty acids) was less sensitive toward amoebae compared to C. neoformans LMPE 046 and C. gattii R265 (both do not produce 3-hydroxy fatty acids) and addition of 3-hydroxy fatty acids to C. neoformans LMPE 046 and C. gattii R265 culture media, causes these strains to become more resistant to amoebal predation. Conversely, addition of aspirin (a 3-hydroxy fatty acid inhibitor) to C. neoformans UOFS Y-1378 culture media made cells more susceptible to amoebae. Our data suggest that this molecule is secreted at a high enough concentration to effect intracellular signaling within amoeba, which in turn, promotes fungal survival.
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Affiliation(s)
- Uju L. Madu
- Pathogenic Yeast Research Group, Department of Microbial, Biochemical and Food Biotechnology, University of the Free StateBloemfontein, South Africa
| | - Adepemi O. Ogundeji
- Pathogenic Yeast Research Group, Department of Microbial, Biochemical and Food Biotechnology, University of the Free StateBloemfontein, South Africa
| | - Bonang M. Mochochoko
- Pathogenic Yeast Research Group, Department of Microbial, Biochemical and Food Biotechnology, University of the Free StateBloemfontein, South Africa
| | - Carolina H. Pohl
- Pathogenic Yeast Research Group, Department of Microbial, Biochemical and Food Biotechnology, University of the Free StateBloemfontein, South Africa
| | - Jacobus Albertyn
- Pathogenic Yeast Research Group, Department of Microbial, Biochemical and Food Biotechnology, University of the Free StateBloemfontein, South Africa
| | - Chantel W. Swart
- Pathogenic Yeast Research Group, Department of Microbial, Biochemical and Food Biotechnology, University of the Free StateBloemfontein, South Africa
| | | | | | - Warwick B. Dunn
- School of Biosciences, University of BirminghamBirmingham, UK
| | - Robin C. May
- School of Biosciences, University of BirminghamBirmingham, UK
- Institute of Microbiology and Infection and the School of Biosciences, University of BirminghamBirmingham, UK
| | - Olihile M. Sebolai
- Pathogenic Yeast Research Group, Department of Microbial, Biochemical and Food Biotechnology, University of the Free StateBloemfontein, South Africa
- Institute of Microbiology and Infection and the School of Biosciences, University of BirminghamBirmingham, UK
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José Maschio V, Corção G, Rott MB. identification of Pseudomonas spp. as amoeba-resistant microorganisms in isolates of Acanthamoeba. Rev Inst Med Trop Sao Paulo 2015; 57:81-3. [PMID: 25651331 PMCID: PMC4325528 DOI: 10.1590/s0036-46652015000100012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 03/28/2014] [Indexed: 11/22/2022] Open
Abstract
Acanthamoeba is a “Trojan horse” of the microbial world. The aim of
this study was to identify the presence of Pseudomonas as an
amoeba-resistant microorganism in 12 isolates of Acanthamoeba. All
isolates showed the genus Pseudomonas spp. as amoeba-resistant
microorganisms. Thus, one can see that the Acanthamoeba isolates
studied are hosts of Pseudomonas.
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Affiliation(s)
- Vinicius José Maschio
- Departamento de Microbiologia, Imunologia e Parasitologia. Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Gertrudes Corção
- Departamento de Microbiologia, Imunologia e Parasitologia. Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Marilise Brittes Rott
- Departamento de Microbiologia, Imunologia e Parasitologia. Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Raghu Nadhanan R, Thomas CJ. Colpoda secrete viable Listeria monocytogenes within faecal pellets. Environ Microbiol 2013; 16:396-404. [PMID: 23981071 DOI: 10.1111/1462-2920.12230] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/21/2013] [Accepted: 07/28/2013] [Indexed: 01/30/2023]
Abstract
Transmission electron microscopy was used to demonstrate that co-cultures of the ciliate Colpoda RR (an environmental isolate) and Colpoda MLS-5 (a food processing environment isolate) with the pathogenic Listeria monocytogenes DRDC8 resulted in secretion of faecal pellets containing intact DRDC8 cells. A green fluorescent protein expressing variant of DRDC8 was used in co-cultures to confirm that the pellet-associated bacterial cells were L. monocytogenes. Viability was confirmed by plate counts, and assay of microbial respiratory activity-proved DRDC8 cells present within faecal pellets was metabolically active. Following treatment of faecal pellets secreted by Colpoda RR and MLS-5 with gentamycin and sodium hypochlorite (NaOCl), no loss of viability of the pellet-located DRDC8 cells was observed, indicating that faecal pellet encapsulated DRDC8 cells are resistant to biocidal agents. This work suggests that Colpoda-derived faecal pellets may provide a mechanism for transmission of L. monocytogenes and other pathogenic bacteria. Furthermore, bacteria encapsulated by faecal pellets may be resistant to disinfectants and cleaning agents used in food manufacturing and preparation facilities.
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Affiliation(s)
- Rethish Raghu Nadhanan
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SA, 5005, Australia
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8
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Cardas M, Khan NA, Alsam S. Staphylococcus aureus exhibit similarities in their interactions with Acanthamoeba and ThP1 macrophage-like cells. Exp Parasitol 2012; 132:513-8. [DOI: 10.1016/j.exppara.2012.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 08/15/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
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9
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Bui XT, Qvortrup K, Wolff A, Bang DD, Creuzenet C. Effect of environmental stress factors on the uptake and survival of Campylobacter jejuni in Acanthamoeba castellanii. BMC Microbiol 2012; 12:232. [PMID: 23051891 PMCID: PMC3538707 DOI: 10.1186/1471-2180-12-232] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 10/03/2012] [Indexed: 11/22/2022] Open
Abstract
Background Campylobacter jejuni is a major cause of bacterial food-borne illness in Europe and North America. The mechanisms allowing survival in the environment and transmission to new hosts are not well understood. Environmental free-living protozoa may facilitate both processes. Pre-exposure to heat, starvation, oxidative or osmotic stresses encountered in the environment may affect the subsequent interaction of C. jejuni with free-living protozoa. To test this hypothesis, we examined the impact of environmental stress on expression of virulence-associated genes (ciaB, dnaJ, and htrA) of C. jejuni and on its uptake by and intracellular survival within Acanthamoeba castellanii. Results Heat, starvation and osmotic stress reduced the survival of C. jejuni significantly, whereas oxidative stress had no effect. Quantitative RT-PCR experiments showed that the transcription of virulence genes was slightly up-regulated under heat and oxidative stresses but down-regulated under starvation and osmotic stresses, the htrA gene showing the largest down-regulation in response to osmotic stress. Pre-exposure of bacteria to low nutrient or osmotic stress reduced bacterial uptake by amoeba, but no effect of heat or oxidative stress was observed. Finally, C. jejuni rapidly lost viability within amoeba cells and pre-exposure to oxidative stress had no significant effect on intracellular survival. However, the numbers of intracellular bacteria recovered 5 h post-gentamicin treatment were lower with starved, heat treated or osmotically stressed bacteria than with control bacteria. Also, while ~1.5 × 103 colony forming unit/ml internalized bacteria could typically be recovered 24 h post-gentamicin treatment with control bacteria, no starved, heat treated or osmotically stressed bacteria could be recovered at this time point. Overall, pre-exposure of C. jejuni to environmental stresses did not promote intracellular survival in A. castellanii. Conclusions Together, these findings suggest that the stress response in C. jejuni and its interaction with A. castellanii are complex and multifactorial, but that pre-exposure to various stresses does not prime C. jejuni for survival within A. castellanii.
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Affiliation(s)
- Xuan Thanh Bui
- National Veterinary Institute, Technical University of Denmark, Aarhus NDK-8200, Denmark
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Doyscher D, Fieseler L, Dons L, Loessner MJ, Schuppler M. Acanthamoebafeature a unique backpacking strategy to trap and feed onListeria monocytogenesand other motile bacteria. Environ Microbiol 2012; 15:433-46. [DOI: 10.1111/j.1462-2920.2012.02858.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 07/05/2012] [Accepted: 07/24/2012] [Indexed: 12/28/2022]
Affiliation(s)
- Dominik Doyscher
- Institute of Food, Nutrition and Health; ETH Zurich; Schmelzbergstrasse 7; 8092; Zurich; Switzerland
| | | | - Lone Dons
- Department of Food Science; University of Copenhagen; Rolighedsvej 30; DK-1958; Frederiksberg C; Denmark
| | - Martin J. Loessner
- Institute of Food, Nutrition and Health; ETH Zurich; Schmelzbergstrasse 7; 8092; Zurich; Switzerland
| | - Markus Schuppler
- Institute of Food, Nutrition and Health; ETH Zurich; Schmelzbergstrasse 7; 8092; Zurich; Switzerland
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Revisiting the Acanthamoeba species that form star-shaped cysts (genotypes T7, T8, T9, and T17): characterization of seven new Brazilian environmental isolates and phylogenetic inferences. Parasitology 2011; 139:45-52. [PMID: 21943405 DOI: 10.1017/s0031182011001648] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Free-living amoebae of the genus Acanthamoeba are the agents of both opportunistic and non-opportunistic infections and are frequently isolated from the environment. Of the 17 genotypes (T1-T17) identified thus far, 4 (T7, T8, T9, and T17) accommodate the rarely investigated species of morphological group I, those that form large, star-shaped cysts. We report the isolation and characterization of 7 new Brazilian environmental Acanthamoeba isolates, all assigned to group I. Phylogenetic analyses based on partial (~1200 bp) SSU rRNA gene sequences placed the new isolates in the robustly supported clade composed of the species of morphological group I. One of the Brazilian isolates is closely related to A. comandoni (genotype T9), while the other 6, together with 2 isolates recently assigned to genotype T17, form a homogeneous, well-supported group (2·0% sequence divergence) that likely represents a new Acanthamoeba species. Thermotolerance, osmotolerance, and cytophatic effects, features often associated with pathogenic potential, were also examined. The results indicated that all 7 Brazilian isolates grow at temperatures up to 40°C, and resist under hyperosmotic conditions. Additionally, media conditioned by each of the new Acanthamoeba isolates induced the disruption of SIRC and HeLa cell monolayers.
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Avery SV, Harwood JL, Lloyd D. Quantification and Characterization of Phagocytosis in the Soil Amoeba Acanthamoeba castellanii by Flow Cytometry. Appl Environ Microbiol 2010; 61:1124-32. [PMID: 16534962 PMCID: PMC1388394 DOI: 10.1128/aem.61.3.1124-1132.1995] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phagocytosis in the common grazing soil amoeba Acanthamoeba castellanii was characterized by flow cytometry. Uptake of fluorescently labelled latex microbeads by cells was quantified by appropriate setting of thresholds on light scatter channels and, subsequently, on fluorescence histograms. Confocal laser scanning microscopy was used to verify the effectiveness of sodium azide as a control for distinguishing between cell surface binding and internalization of beads. It was found that binding of beads at the cell surface was complete within 5 min and 80% of cells had beads associated with them after 10 min. However, the total number of phagocytosed beads continued to rise up to 2 h. The prolonged increase in numbers of beads phagocytosed was due to cell populations containing increasing numbers of beads peaking at increasing time intervals from the onset of phagocytosis. Fine adjustment of thresholds on light scatter channels was used to fractionate cells according to cell volume (cell cycle stage). Phagocytotic activity was approximately threefold higher in the largest (oldest) than in the smallest (newly divided) cells of A. castellanii and showed some evidence of periodicity. At no stage in the cell cycle did phagocytosis cease. Binding and phagocytosis of beads were also markedly influenced by culture age and rate of rotary agitation of cell suspensions. Saturation of phagocytosis (per cell) at increasing bead or decreasing cell concentrations occurred at bead/cell ratios exceeding 10:1. This was probably a result of a limitation of the vacuolar uptake system of A. castellanii, as no saturation of bead binding was evident. The advantages of flow cytometry for characterization of phagocytosis at the single-cell level in heterogeneous protozoal populations and the significance of the present results are discussed.
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Magliano AC, da Silva FM, Teixeira MM, Alfieri SC. Genotyping, physiological features and proteolytic activities of a potentially pathogenic Acanthamoeba sp. isolated from tap water in Brazil. Exp Parasitol 2009; 123:231-5. [DOI: 10.1016/j.exppara.2009.07.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 06/23/2009] [Accepted: 07/21/2009] [Indexed: 11/26/2022]
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Akya A, Pointon A, Thomas C. Mechanism involved in phagocytosis and killing of Listeria monocytogenes by Acanthamoeba polyphaga. Parasitol Res 2009; 105:1375-83. [PMID: 19644706 DOI: 10.1007/s00436-009-1565-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 07/09/2009] [Indexed: 11/30/2022]
Abstract
Intra-cellular pathogen, Listeria monocytogenes, is capable of invasion and survival within mammalian cells. However, Acanthamoeba polyphaga trophozoites phagocytose and rapidly degrade Listeria cells. In order to provide more information on amoeba phagocytosis and killing mechanisms, this study used several inhibitor agents known to affect the phagocytosis and killing of bacteria by eukaryotes. Amoebae were pre-treated with mannose, cytochalasin D, wortmannin, suramin, ammonium chloride, bafilomycin A and monensin followed by co-culture with bacteria. Phagocytosis and killing of bacterial cells by amoeba trophozoites was assessed using plate counting methods and microscopy. The data presented indicates that actin polymerisation and cytoskeletal rearrangement are involved in phagocytosis of L. monocytogenes cells by A. polyphaga trophozoites. Further, both phagosomal acidification and phagosome-lysosome fusion are involved in killing and degradation of L. monocytogenes cells by A. polyphaga. However, the mannose-binding protein receptor does not play an important role in uptake of bacteria by amoeba trophozoites. In conclusion, this data reveals the similar principles of molecular mechanisms used by different types of eukaryotes in uptake and killing of bacteria.
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Affiliation(s)
- Alisha Akya
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia.
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15
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De Moraes J, Alfieri SC. Growth, encystment and survival of Acanthamoeba castellanii grazing on different bacteria. FEMS Microbiol Ecol 2008; 66:221-9. [DOI: 10.1111/j.1574-6941.2008.00594.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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16
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Pickup ZL, Pickup R, Parry JD. Growth of Acanthamoeba castellanii and Hartmannella vermiformis on live, heat-killed and DTAF-stained bacterial prey. FEMS Microbiol Ecol 2007; 61:264-72. [PMID: 17596189 DOI: 10.1111/j.1574-6941.2007.00346.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The growth responses of two species of amoeba were evaluated in the presence of live, heat-killed and heat-killed/5-(4,6-dichlorotriazin-2-yl) aminofluorescein (DTAF)-stained cells of Escherichia coli, Pseudomonas aeruginosa, Klebsiella aerogenes, Klebsiella ozaenae and Staphylococcus aureus. The specific growth rates of both species were significantly higher with live bacterial prey, the only exception being Hartmannella vermiformis feeding on S. aureus, for which growth rates were equivalent on all prey states. There was no significant difference between growth rates, yield or ingestion rates of amoebae feeding on heat-killed or heat-killed/stained bacterial cells, suggesting that it was the heat-killing process that influenced the amoeba-bacteria interaction. Pretreatment of prey cells had a greater influence on amoebic processing of Gram-negative bacteria compared with the Gram-positive bacterium, which appeared to be as a result of the former cells being more difficult to digest and/or losing their ability to deter amoebic ingestion. These antipredatory mechanisms included microcolony formation in P. aeruginosa, toxin production in K. ozaenae, and the presence of an intact capsule in K. aerogenes. E. coli and S. aureus did not appear to possess an antipredator mechanism, although intact cells of the S. aureus were observed in faecal pellets, suggesting that any antipredatory mechanism was occurring at the digestion stage.
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Affiliation(s)
- Zoë L Pickup
- Department of Biological Sciences, The Lancaster Environment Centre, Lancaster University, Lancaster, UK
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Abstract
Acanthamoeba is an opportunistic protozoan that is widely distributed in the environment and is well recognized to produce serious human infections, including a blinding keratitis and a fatal encephalitis. This review presents our current understanding of the burden of Acanthamoeba infections on human health, their pathogenesis and pathophysiology, and molecular mechanisms associated with the disease, as well as virulence traits of Acanthamoeba that may be targets for therapeutic interventions and/or the development of preventative measures.
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Affiliation(s)
- Naveed Ahmed Khan
- School of Biological and Chemical Sciences, Birkbeck College, University of London, London, UK.
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18
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Abstract
Free-living amoebae feed on bacteria, fungi, and algae. However, some microorganisms have evolved to become resistant to these protists. These amoeba-resistant microorganisms include established pathogens, such as Cryptococcus neoformans, Legionella spp., Chlamydophila pneumoniae, Mycobacterium avium, Listeria monocytogenes, Pseudomonas aeruginosa, and Francisella tularensis, and emerging pathogens, such as Bosea spp., Simkania negevensis, Parachlamydia acanthamoebae, and Legionella-like amoebal pathogens. Some of these amoeba-resistant bacteria (ARB) are lytic for their amoebal host, while others are considered endosymbionts, since a stable host-parasite ratio is maintained. Free-living amoebae represent an important reservoir of ARB and may, while encysted, protect the internalized bacteria from chlorine and other biocides. Free-living amoebae may act as a Trojan horse, bringing hidden ARB within the human "Troy," and may produce vesicles filled with ARB, increasing their transmission potential. Free-living amoebae may also play a role in the selection of virulence traits and in adaptation to survival in macrophages. Thus, intra-amoebal growth was found to enhance virulence, and similar mechanisms seem to be implicated in the survival of ARB in response to both amoebae and macrophages. Moreover, free-living amoebae represent a useful tool for the culture of some intracellular bacteria and new bacterial species that might be potential emerging pathogens.
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Affiliation(s)
- Gilbert Greub
- Unité des Rickettsies, Faculté de Médecine, Université de la Méditerranée, Marseille, France
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19
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Willcox MD, Low R, Hon J, Harmis N. Does Acanthamoeba protect Pseudomonas aeruginosa from the bactericidal effects of contact lens disinfecting systems? AUSTRALIAN AND NEW ZEALAND JOURNAL OF OPHTHALMOLOGY 1998; 26 Suppl 1:S32-5. [PMID: 9685017 DOI: 10.1111/j.1442-9071.1998.tb01366.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of this study was to test the hypothesis that Pseudomonas aeruginosa that have been internalized in Acanthamoeba are protected against the action of contact lens disinfecting solutions. METHODS The experiments were divided into two parts. First, five commercially available disinfecting solutions, hydrogen peroxide and non-peroxide based, were tested for their efficacy against four strains of P. aeruginosa and one strain of A. castellanii. Cells were inoculated into working concentrations of disinfecting solutions, incubated for 18 h and the numbers of viable bacteria or amoeba were analysed after appropriate growth on agar plates. Second, two strains of P. aeruginosa were allowed to interact with A. castellanii for 4 h prior to addition to disinfecting solutions. The numbers of P. aeruginosa after incubation with the disinfecting solutions were measured after growth on agar plates. RESULTS In general, disinfecting solutions containing hydrogen peroxide were most effective against the micro-organisms. Solutions containing only traces of polyaminopropyl biguanide were least effective. CONCLUSIONS For strains of P. aeruginosa, the presence of the amoebae did not protect the bacteria against the disinfecting agents. The amoeba appeared to kill the bacteria, perhaps using them as a food source.
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Affiliation(s)
- M D Willcox
- School of Optometry, and Cooperative Research Centre for Eye Research and Technology, University of New South Wales, Sydney, Australia.
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20
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Denton M, Kerr KG. Microbiological and clinical aspects of infection associated with Stenotrophomonas maltophilia. Clin Microbiol Rev 1998; 11:57-80. [PMID: 9457429 PMCID: PMC121376 DOI: 10.1128/cmr.11.1.57] [Citation(s) in RCA: 580] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The gram-negative bacterium Stenotrophomonas maltophilia is increasingly recognized as an important cause of nosocomial infection. Infection occurs principally, but not exclusively, in debilitated and immunosuppressed individuals. Management of S. maltophilia-associated infection is problematic because many strains of the bacterium manifest resistance to multiple antibiotics. These difficulties are compounded by methodological problems in in vitro susceptibility testing for which there are, as yet, no formal guidelines. Despite its acknowledged importance as a nosocomial pathogen, little is known of the epidemiology of S. maltophilia, and although it is considered an environmental bacterium, its sources and reservoirs are often not readily apparent. Molecular typing systems may contribute to our knowledge of the epidemiology of S. maltophilia infection, thus allowing the development of strategies to interrupt the transmission of the bacterium in the hospital setting. Even less is known of pathogenic mechanisms and putative virulence factors involved in the natural history of S. maltophilia infection and this, coupled with difficulties in distinguishing colonization from true infection, has fostered the view that the bacterium is essentially nonpathogenic. This article aims to review the current taxonomic status of S. maltophilia, and it discusses the laboratory identification of the bacterium. The epidemiology of the organism is considered with particular reference to nosocomial outbreaks, several of which have been investigated by molecular typing techniques. Risk factors for acquisition of the bacterium are also reviewed, and the ever-expanding spectrum of clinical syndromes associated with S. maltophilia is surveyed. Antimicrobial resistance mechanisms, pitfalls in in vitro susceptibility testing, and therapy of S. maltophilia infections are also discussed.
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Affiliation(s)
- M Denton
- Department of Microbiology, University of Leeds, United Kingdom
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21
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Penland RL, Wilhelmus KR. Comparison of axenic and monoxenic media for isolation of Acanthamoeba. J Clin Microbiol 1997; 35:915-22. [PMID: 9157153 PMCID: PMC229701 DOI: 10.1128/jcm.35.4.915-922.1997] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Acanthamoeba is a genus of ubiquitous, free-living amebae that can be difficult to isolate by standard microbiologic techniques. We retrospectively reviewed the laboratory records of patients with ocular acanthamoebic infection for the period from January 1973 to June 1996 and found that Acanthamoeba isolates were recovered from 73, 71, and 70% of clinical specimens inoculated onto buffered charcoal-yeast extract agar (BCYE), nonnutrient agar with live or dead Escherichia coli, and tryptic soy agar (TSA) with horse or sheep blood, respectively. We then prospectively compared the recovery of a corneal isolate of Acanthamoeba on commercial media from Remel and BBL (TSA with 5% sheep blood, TSA with 5% horse blood, TSA with 5% rabbit blood, V agar, chocolate agar, BCYE, and selective BCYE with polymyxin B, anisomycin, and vancomycin) and on axenic and monoxenic media prepared with live or dead bacteria (Enterobacter aerogenes, E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, and Stenotrophomonas maltophilia). Good recovery of trophozoites was obtained on BCYE, TSA with rabbit blood, TSA with horse blood, and Remel TSA with sheep blood. BBL TSA with horse blood or rabbit blood provided good recovery of cysts. All species of live or dead bacteria yielded good recovery of trophozoites; however, only nonnutrient agar with live P. aeruginosa, live E. aerogenes, or live S. maltophilia gave good recovery of cysts. TSA with either rabbit blood or horse blood, BCYE, and nonnutrient agar prepared with live P. aeruginosa, E. aerogenes, or S. maltophilia offer optimal recovery of Acanthamoeba.
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Affiliation(s)
- R L Penland
- Sid W. Richardson Ocular Microbiology Laboratory, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas 77030, USA
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22
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Ahearn DG, Gabriel MM. Contact lenses, disinfectants, and Acanthamoeba keratitis. ADVANCES IN APPLIED MICROBIOLOGY 1997; 43:35-56. [PMID: 9097411 DOI: 10.1016/s0065-2164(08)70222-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- D G Ahearn
- Department of Biology, Georgia State University, Atlanta 30302-4010, USA
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