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Pathogens
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Free-Living Amoebae Infections
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Free-Living Amoebae Infections

A special issue of Pathogens (ISSN 2076-0817). This special issue belongs to the section "Parasitic Pathogens".

Deadline for manuscript submissions: 30 November 2024 | Viewed by 6463

Special Issue Editors

Dr. Maritza Omaña-Molina

E-Mail Website
Guest Editor
Laboratorio de Amibas Anfizóicas, Facultad de Estudios Superiores Iztacala (FESI), Medicina, Universidad Nacional Autónoma de México (UNAM), Tlalnepantla 54090, Estado de México (Edo Méx), México
Interests: free living amoebae; amphizoic amoebae; pathogenic mechanisms
Dr. Jacob Lorenzo-Morales

E-Mail Website
Guest Editor
Departamento de Obstetricia, Ginecología, Pediatría, Medicina Preventiva y Salud Pública, Toxicología, Medicina Legal y Forense y Parasitología, Universidad de La Laguna (ULL), Avda. Astrofísico F. Sánchez, 2, 38206 La Laguna, Spain
Interests: free living Amoebae; therapeutics; emerging parasitic protozoa; diagnosis; natural compounds; synthetic compounds
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Free-living amoebae are ecologically relevant cosmopolitan protozoa, since they contribute to the biological control of bacterial populations, recycling nutrients in the soil. However, a group of these amoebas have aroused interest in the biomedical area due to the pathologies they cause, making it necessary to designate this group as amphizoic amoebas, highlighting Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris as etiological agents of infections in most of the cases in the central nervous system, cornea and skin, for which up to now there are no drugs of choice.

It is important to explore advances in the diagnosis and treatment of the pathologies caused by these amoebas, as well as epidemiological data that demonstrate their importance worldwide. No less important is the description of the pathogenicity mechanisms that allow the search for more affective therapeutic targets.

Dr. Maritza Omaña-Molina
Dr. Jacob Lorenzo-Morales
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • free living amoebae
  • amphizoic amoebae
  • infections
  • pathogenic mechanisms
  • pharmacological advances

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Published Papers (4 papers)

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Research

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13 pages, 5390 KiB  
Article
Lactoferrin and Lysozyme Inhibit the Proteolytic Activity and Cytopathic Effect of Naegleria fowleri Enzymes
by Moises Martinez-Castillo, Gerardo Ramírez-Rico, Mineko Shibayama, Mireya de la Garza and Jesús Serrano-Luna
Pathogens 2024, 13(1), 44; https://doi.org/10.3390/pathogens13010044 - 3 Jan 2024
Cited by 1 | Viewed by 1764
Abstract
Naegleria fowleri is a ubiquitous free-living amoeba that causes primary amoebic meningoencephalitis. As a part of the innate immune response at the mucosal level, the proteins lactoferrin (Lf) and lysozyme (Lz) are secreted and eliminate various microorganisms. We demonstrate that N. fowleri survives [...] Read more.
Naegleria fowleri is a ubiquitous free-living amoeba that causes primary amoebic meningoencephalitis. As a part of the innate immune response at the mucosal level, the proteins lactoferrin (Lf) and lysozyme (Lz) are secreted and eliminate various microorganisms. We demonstrate that N. fowleri survives the individual and combined effects of bovine milk Lf (bLf) and chicken egg Lz (cLz). Moreover, amoebic proliferation was not altered, even at 24 h of co-incubation with each protein. Trophozoites’ ultrastructure was evaluated using transmission electron microscopy, and these proteins did not significantly alter their organelles and cytoplasmic membranes. Protease analysis using gelatin-zymograms showed that secreted proteases of N. fowleri were differentially modulated by bLf and cLz at 3, 6, 12, and 24 h. The bLf and cLz combination resulted in the inhibition of N. fowleri-secreted proteases. Additionally, the use of protease inhibitors on bLf-zymograms demonstrated that secreted cysteine proteases participate in the degradation of bLf. Nevertheless, the co-incubation of trophozoites with bLf and/or cLz reduced the cytopathic effect on the MDCK cell line. Our study suggests that bLf and cLz, alone or together, inhibited secreted proteases and reduced the cytopathic effect produced by N. fowleri; however, they do not affect the viability and proliferation of the trophozoites. Full article
(This article belongs to the Special Issue Free-Living Amoebae Infections)
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12 pages, 4175 KiB  
Article
Saline-Tolerant Pathogenic Acanthamoeba spp. Isolated from a Geothermal Power Plant
by Elizabeth Ramírez-Flores, Patricia Bonilla-Lemus, María M. Carrasco-Yépez, Miguel A. Ramírez-Flores, Karla A. Barrón-Graciano, Saúl Rojas-Hernández, María Reyes-Batlle and Jacob Lorenzo-Morales
Pathogens 2023, 12(11), 1363; https://doi.org/10.3390/pathogens12111363 - 17 Nov 2023
Cited by 2 | Viewed by 1445
Abstract
Few studies have been conducted in the cooling systems of power plants; they have focused on Naegleria fowleri, leaving a gap in the knowledge of other pathogenic free-living amoebae in this environment. The objective of this study was to determine the occurrence of [...] Read more.
Few studies have been conducted in the cooling systems of power plants; they have focused on Naegleria fowleri, leaving a gap in the knowledge of other pathogenic free-living amoebae in this environment. The objective of this study was to determine the occurrence of saline-tolerant pathogenic Acanthamoeba in a geothermal power plant. The identification of isolated amoebae at genus level was carried out, observing their morphological characteristics; the determination of genotype and species of Acanthamoeba was performed via molecular biology (PCR). Water temperature ranged from 18 to 43 °C and conductivity from 4.0 × 104 to 8.7 × 104 μS/cm; this last value was greater than the seawater value. Only five amoeba genera were found. Acanthamoeba was in all the sampling sites, showing high saline tolerance. The high temperature, but mainly high conductivity, were the environmental conditions that determined the presence of pathogenic free-living amoebae in the hot water. All the strains of Acanthamoeba culbertsoni killed the mice, having a mortality of 40 to 100%. Acanthamoeba genotypes T10 and T5 were identified, T10 is rarely isolated from the environment, while T5 is more frequent. This is the first time that genotypes T5 and T10 have been reported in the environment in Mexico. Full article
(This article belongs to the Special Issue Free-Living Amoebae Infections)
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14 pages, 2530 KiB  
Article
Taurine, a Component of the Tear Film, Exacerbates the Pathogenic Mechanisms of Acanthamoeba castellanii in the Ex Vivo Amoebic Keratitis Model
by Lizbeth Salazar-Villatoro, Bibiana Chávez-Munguía, Celia Esther Guevara-Estrada, Anel Lagunes-Guillén, Dolores Hernández-Martínez, Ismael Castelan-Ramírez and Maritza Omaña-Molina
Pathogens 2023, 12(8), 1049; https://doi.org/10.3390/pathogens12081049 - 16 Aug 2023
Cited by 2 | Viewed by 1270
Abstract
Acanthamoeba spp. is the etiological agent of amoebic keratitis. In this study, the effect of taurine in physiological concentrations in tears (195 μM) on trophozoites of Acanthamoeba castellanii through the ex vivo amoebic keratitis model was evaluated. Trophozoites were coincubated with the Syrian [...] Read more.
Acanthamoeba spp. is the etiological agent of amoebic keratitis. In this study, the effect of taurine in physiological concentrations in tears (195 μM) on trophozoites of Acanthamoeba castellanii through the ex vivo amoebic keratitis model was evaluated. Trophozoites were coincubated with the Syrian golden hamster cornea (Mesocricetus auratus) for 3 and 6 h. Group 1: Control (−). Corneas coincubated with amoebic culture medium and taurine. Group 2: Control (+). Corneas coincubated with trophozoites without taurine. Group 3: Corneas coincubated with taurine 15 min before adding trophozoites. Group 4: Trophozoites coincubated 15 min with taurine before placing them on the cornea. Group 5: Corneas coincubated for 15 min with trophozoites; subsequently, taurine was added. Results are similar for both times, as evaluated by scanning electron microscopy. As expected, in the corneas of Group 1, no alterations were observed in the corneal epithelium. In the corneas of Group 2, few adhered trophozoites were observed on the corneal surface initiating migrations through cell junctions as previously described; however, in corneas of Groups 3, 4 and 5, abundant trophozoites were observed, penetrating through different corneal cell areas, emitting food cups and destabilizing corneal surface in areas far from cell junctions. Significant differences were confirmed in trophozoites adherence coincubated with taurine (p < 0.05). Taurine does not prevent the adhesion and invasion of the amoebae, nor does it favor its detachment once these have adhered to the cornea, suggesting that taurine in the physiological concentrations found in tears stimulates pathogenic mechanisms of A. castellanii. Full article
(This article belongs to the Special Issue Free-Living Amoebae Infections)
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Review

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14 pages, 286 KiB  
Review
Approaches for Targeting Naegleria fowleri Using Nanoparticles and Artificial Peptides
by Hayley Fong, Zachary H. Leid and Anjan Debnath
Pathogens 2024, 13(8), 695; https://doi.org/10.3390/pathogens13080695 - 16 Aug 2024
Viewed by 1274
Abstract
Naegleria fowleri is a free-living amoeba which causes primary amoebic meningoencephalitis (PAM). Although PAM is rare, the fatality rate is staggering at over 97%. So, the importance of finding an effective treatment and cure for PAM caused by N. fowleri is a crucial [...] Read more.
Naegleria fowleri is a free-living amoeba which causes primary amoebic meningoencephalitis (PAM). Although PAM is rare, the fatality rate is staggering at over 97%. So, the importance of finding an effective treatment and cure for PAM caused by N. fowleri is a crucial area of research. Existing research on developing novel therapeutic strategies to counter N. fowleri infection is limited. Since the blood–brain barrier (BBB) presents an obstacle to delivering drugs to the site of infection, it is important to employ strategies that can effectively direct the therapeutics to the brain. In this regard, our review focuses on understanding the physiology and mechanisms by which molecules pass through the BBB, the current treatment options available for PAM, and the recent research conducted in the decade of 2012 to 2022 on the use of nanomaterials to enhance drug delivery. In addition, we compile research findings from other central nervous system (CNS) diseases that use shuttle peptides which allow for transport of molecules through the BBB. The approach of utilizing BBB shuttles to administer drugs through the BBB may open up new areas of drug discovery research in the field of N. fowleri infection. Full article
(This article belongs to the Special Issue Free-Living Amoebae Infections)
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