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Scientific Reports Sep 2022Amoebae from the genus Acanthamoeba are important pathogens responsible for severe illnesses in humans such as Acanthamoeba keratitis and granulomatous amoebic...
Amoebae from the genus Acanthamoeba are important pathogens responsible for severe illnesses in humans such as Acanthamoeba keratitis and granulomatous amoebic encephalitis. In the last few decades, AK diagnoses have steadily increased. Most patients suffering from AK were contact lens users and the infection was related to poor hygiene. However, therapy is not yet well established, and treatments may last for several months due to resistance. Moreover, these treatments have been described to generate cytotoxicity. Therefore, there is an urgent need to develop new therapeutic strategies against AK. In this study, the amoebicidal activity of different generation cationic carbosilane dendrons derived with 4-phenylbutyric acid was demonstrated against Acanthamoeba polyphaga and Acanthamoeba griffini trophozoites and cysts. In addition, the combination of chlorhexidine digluconate and the most effective dendron (ArCOG(SNMeI)) showed an in vitro effect against Acanthamoeba trophozoites and cysts, reducing the minimal trophozoite amoebicidal concentration as well as concentrations with cysticidal activity.
Topics: Acanthamoeba; Acanthamoeba castellanii; Amebicides; Animals; Cations; Cysts; Dendrimers; Humans; Phenylbutyrates; Silanes; Trophozoites
PubMed: 36056060
DOI: 10.1038/s41598-022-19200-w -
Biomedicine & Pharmacotherapy =... Feb 2023Free Living Amoeba (FLA) infections caused by Acanthamoeba genus include chronic nervous system diseases such as Granulomatous Amoebic Encephalitis (GAE), or a severe...
Free Living Amoeba (FLA) infections caused by Acanthamoeba genus include chronic nervous system diseases such as Granulomatous Amoebic Encephalitis (GAE), or a severe eye infection known as Acanthamoeba keratitis (AK). Current studies focused on therapy against these diseases are aiming to find novel compounds with amoebicidal activity and low toxicity to human tissues. Brown algae, such as Gongolaria abies-marina (previously known as Cystoseira abies-marina, S.G. Gmelin), presents bioactive molecules of interest, including some with antiprotozoal activity. In this study, six meroterpenoids were isolated and purified from the species Gongolaria abies-marina. Gongolarones A (1), B (2) and C (3) were identified as new compounds. Additionally, cystomexicone B (4), 1'-methoxyamentadione (5) and 6Z-1'-methoxyamentadione (6) were isolated. All compounds exhibited amoebicidal activity against Acanthamoeba castellanii Neff, A. polyphaga and A. griffini strains. Gongolarones A (1) and C (3) showed the lowest IC values against the two stages of these amoebae (trophozoite and cyst). Structure-activity relationship revealed that the cyclization by ether formation from C-12 to C-15 of 1, and the isomerization Δ to Δ of 3, increased the antiamoeboid activity of both compounds. Furthermore, gongolarones A (1) and C (3) triggered chromatin condensation, mitochondrial malfunction, oxidative stress, and disorganization of the tubulin-actin cytoskeleton in treated trophozoites. Moreover, transmission electron microscopy (TEM) images analysis revealed that compounds 1 and 3 induced autophagy process and inhibited the encystation process. All those results suggest that both compounds could induce programmed cell death (PCD) in Acanthamoeba.
Topics: Animals; Humans; Acanthamoeba castellanii; Amebicides; Trophozoites; Actin Cytoskeleton
PubMed: 36916403
DOI: 10.1016/j.biopha.2022.114185 -
Heliyon Sep 2020causes severe diseases such as Granulomatous Amebic Encephalitis (GAE) and keratitis (AK). Improving the culture media classically used for this amoeba could help to...
causes severe diseases such as Granulomatous Amebic Encephalitis (GAE) and keratitis (AK). Improving the culture media classically used for this amoeba could help to identify it quickly and facilitate its study as a biological model. The purpose of this study was to compare the growth of two genotypes (T3 and T4) in several culture media. (T3 genotype) and (T4 genotype) were cultured in PYG, TSY, TYI-S-33, RPMI, and RPMI-FBS medium. The number of amoebas grown in different culture media was counted and compared to each other for 14 days. Findings in this research revealed the highest growth in RPMI-FBS medium. For this reason, we can recommend this culture medium to promote the growth of in its biological studies.
PubMed: 32984575
DOI: 10.1016/j.heliyon.2020.e04805 -
International Journal For Parasitology.... Dec 2021Free-living amoebae of Acanthamoeba spp. are causative agents of human infections such as granulomatous amoebic encephalitis (GAE) and Acanthamoeba keratitis (AK). The...
Free-living amoebae of Acanthamoeba spp. are causative agents of human infections such as granulomatous amoebic encephalitis (GAE) and Acanthamoeba keratitis (AK). The exploration of innovative chemical entities from natural sources that induce intrinsic apoptotic pathway or a Programmed Cell Death (PCD) in Acanthamoeba protozoa is essential to develop new therapeutic strategies. In this work, the antiamoeboid activity of squamins C-F (1-4), four cyclooctapeptides isolated from Annona globiflora was tested in vitro against Acanthamoeba castellanii Neff, A. polyphaga, A. quina, and A. griffini, and a structure-activity relationship was also established. The most sensitive strain against all tested cyclooctapeptides was A. castellanii Neff being the R conformers of the S-oxo-methionine residue, squamins D (2) and F (4), the most active against the trophozoite stage. It is remarkable that all four peptides showed no cytotoxic effects against murine macrophages cell line J774A.1. The analysis of the mode of action of squamins C-F against A. castellanii indicate that these cyclopeptides induced the mechanisms of programmed cell death (PCD). All peptides trigger mitochondrial damages, significant inhibition of ATP production compared to the negative control, chromatin condensation and slight damages in membrane that affects its permeability despite it conserves integrity at the IC for 24 h. An increase in reactive oxygen species (ROS) was observed in all cases.
Topics: Acanthamoeba Keratitis; Acanthamoeba castellanii; Amebiasis; Animals; Annona; Humans; Mice; Trophozoites
PubMed: 34411895
DOI: 10.1016/j.ijpddr.2021.08.003 -
Antibiotics (Basel, Switzerland) Feb 2022is a ubiquitous opportunistic protozoan pathogen that is known to cause blinding keratitis and rare, but usually fatal, granulomatous encephalitis. The difficulty in...
is a ubiquitous opportunistic protozoan pathogen that is known to cause blinding keratitis and rare, but usually fatal, granulomatous encephalitis. The difficulty in treating infections and the toxicity issues of the current treatments emphasize the need to use alternative agents with amoebicidal activity. The aim of this study was to evaluate the in vitro antiamoebic activity of three third-generation statins-cerivastatin, pitavastatin and rosuvastatin-against both cysts and trophozoites of the following four strains of Neff, and . Furthermore, programmed cell death (PCD) induction traits were evaluated by measuring chromatin condensation, damages at the mitochondrial level, production of reactive oxygen species (ROS) and the distribution of actin cytoskeleton fibers. Neff was the strain most sensitive to all the statins, where cerivastatin showed the lowest amoebicidal activity for both trophozoite and cyst forms (0.114 ± 0.050 and 0.704 ± 0.129 µM, respectively). All the statins were able to cause DNA condensation, collapse in the mitochondrial membrane potential and a reduction in ATP level production, and disorganization of the total actin fibers in the cytoskeleton of all the evaluated strains. Our results showed that the tested statins were able to induce PCD compatible events in the treated amoebae, including chromatin condensation, collapse in the mitochondrial potential and ATP levels, cytoskeleton disassembly and ROS generation.
PubMed: 35203882
DOI: 10.3390/antibiotics11020280 -
Scientific Reports Sep 2018Gemmata spp. bacteria thrive in the same aquatic environments as free-living amoebae. DNA-based detection of Gemmata spp. sequences in the microbiota of the human...
Gemmata spp. bacteria thrive in the same aquatic environments as free-living amoebae. DNA-based detection of Gemmata spp. sequences in the microbiota of the human digestive tract and blood further questioned the susceptibility of Gemmata spp. to phagocytes. Here, Gemmata obscuriglobus and Gemmata massiliana were co-cultured with the amoebae Acanthamoeba polyphaga, Acanthamoeba castellanii, Acanthamoeba griffini and THP-1 macrophage-like phagocytes. All experiments were performed in five independant replicates. The ratio amoeba/bacteria was 1:20 and the ratio THP-1/bacteria was 1:10. After a 2-hour co-culture, extracellular bacteria were killed by kanamycin or amikacin and eliminated. The intracellular location of Gemmata bacteria was specified by confocal microscopy. Microscopic enumerations and culture-based enumerations of colony-forming units were performed at T = 0, 1, 2, 3, 4, 8, 16, 24, 48 and 72 hours post-infection. Then, Gemmata bacteria were engulfed into the phagocytes' cytoplasmic vacuoles, more than (98 ± 2)% of Gemmata bacteria, compared to controls, were destroyed by phagocytic cells after a 48-h co-culture according to microscopy and culture results, and no positive culture was observed at T = 72-hours. Under our co-culture conditions, Gemmata bacteria were therefore susceptible to the environmental and host phagocytes here investigated. These data suggest that these Acanthamoeba species and THP-1 cells cannot be used to isolate G. massiliana and G. obscuriglobus under the co-culture conditions applied in this study. Although the THP-1 response can point towards potential responses that might occur in vivo, these responses should first bevalidated by in vivo studies to draw definite conclusions.
Topics: Acanthamoeba; Coculture Techniques; Humans; Macrophages; Planctomycetales; THP-1 Cells
PubMed: 30190504
DOI: 10.1038/s41598-018-31667-0 -
European Journal of Pharmaceutics and... Nov 2022Statins are effective sterol lowering agents with high amoebicidal activity. Nevertheless, due to their poor aqueous solubility, they remain underused especially in eye...
Statins are effective sterol lowering agents with high amoebicidal activity. Nevertheless, due to their poor aqueous solubility, they remain underused especially in eye drop formulation. The aim of the present study is to develop Pitavastatin loaded nanoparticles suitable for ophthalmic administration and designed for the management of Acanthamoeba Keratitis. These nanocarriers are aimed to solve both the ophthalmic route-associated problems and the limited aqueous drug solubility issues of Pitavastatin. Nanoparticles were obtained by a nanoprecipitation-solvent displacement method and their amoebicidal activity was evaluated against four strains of Acanthamoeba: A. castellanii Neff, A. polyphaga, A. griffini and A. quina. In Acanthamoeba polyphaga, the effect of the present nanoparticles was investigated with respect to the microtubule distribution and several programmed cell death features. Nanoparticles were able to eliminate all the tested strains and Acanthamoeba polyphaga was determined to be the most resistance strain. Nanoparticles induced chromatin condensation, autophagic vacuoles and mitochondria dysfunction.
Topics: Humans; Acanthamoeba Keratitis; Administration, Ophthalmic; Acanthamoeba; Amebicides; Cell Death; Autophagy; Nanoparticles
PubMed: 36162636
DOI: 10.1016/j.ejpb.2022.09.020 -
Frontiers in Microbiology 2024Free-living amoebae are an extensive group of protistans that can be found in a wide variety of environments. Among them, the genus and stand out as two of the most...
INTRODUCTION
Free-living amoebae are an extensive group of protistans that can be found in a wide variety of environments. Among them, the genus and stand out as two of the most pathogenic amoebae and with a higher number of reported cases. is mainly found in warm freshwater water bodies whereas amoebae of the genus are broadly distributed through natural and anthropogenic environments. In this regard, the management and the control of the amoebic populations in swimming pools has become a major public health challenge for institutions.
METHODS
The aim of this work was to evaluate the growth pattern of trophozoites of and at different temperatures and salt concentrations.
RESULTS AND DISCUSSION
Our results showed that resisted a higher concentration of salt than . Moreover, no trophozoites could withstand the salt levels of the sea in conditions. This work supports the contention that salinity could represent an important and useful tool for the control of the most pathogenic amoebic populations in recreational water bodies.
PubMed: 38426057
DOI: 10.3389/fmicb.2024.1356452 -
Journal of Parasitology Research 2014Light and transmission electron microscopy observations are reported on the structure and in vitro cytopathic effect of Acanthamoeba griffini trophozoites isolated from...
Light and transmission electron microscopy observations are reported on the structure and in vitro cytopathic effect of Acanthamoeba griffini trophozoites isolated from a clinical case. Live trophozoites were moderately active with a remarkable pleomorphism which changed from ovoid to quite elongated shapes. When moving, amoebae formed cytoplasmic projections such as wide lamellae and acanthopodia of diverse size and thickness which contain a significant amount of actin. Ultrastructurally, the cytoplasm showed the main organelles found in other free-living amoebae. Coincubation of trophozoites with MDCK cell monolayers resulted in a local damage to target cells after 24 h of interaction, suggesting that the cytopathic effect is contact-dependent. By transmission electron microscopy, amoebae appeared to engulf small portions of the MDCK cells; however, the cells that were not in contact with trophozoites had an unaltered morphology. When epithelial monolayers were incubated with conditioned medium for 24 h, small areas of cell injury were also observed. The phylogenetical analysis as well as the sequencing of the acquired amplified product for the DF3 region of the amoebae isolate confirmed that it belongs to genotype T3, which includes other pathogenic amoebae; besides the activity of two drugs currently used against Acanthamoeba was tested on A. griffini.
PubMed: 25313337
DOI: 10.1155/2014/256310 -
Genome Biology and Evolution Oct 2020Peroxisomes perform various metabolic processes that are primarily related to the elimination of reactive oxygen species and oxidative lipid metabolism. These organelles...
Ultrastructural, Cytochemical, and Comparative Genomic Evidence of Peroxisomes in Three Genera of Pathogenic Free-Living Amoebae, Including the First Morphological Data for the Presence of This Organelle in Heteroloboseans.
Peroxisomes perform various metabolic processes that are primarily related to the elimination of reactive oxygen species and oxidative lipid metabolism. These organelles are present in all major eukaryotic lineages, nevertheless, information regarding the presence of peroxisomes in opportunistic parasitic protozoa is scarce and in many cases it is still unknown whether these organisms have peroxisomes at all. Here, we performed ultrastructural, cytochemical, and bioinformatic studies to investigate the presence of peroxisomes in three genera of free-living amoebae from two different taxonomic groups that are known to cause fatal infections in humans. By transmission electron microscopy, round structures with a granular content limited by a single membrane were observed in Acanthamoeba castellanii, Acanthamoeba griffini, Acanthamoeba polyphaga, Acanthamoeba royreba, Balamuthia mandrillaris (Amoebozoa), and Naegleria fowleri (Heterolobosea). Further confirmation for the presence of peroxisomes was obtained by treating trophozoites in situ with diaminobenzidine and hydrogen peroxide, which showed positive reaction products for the presence of catalase. We then performed comparative genomic analyses to identify predicted peroxin homologues in these organisms. Our results demonstrate that a complete set of peroxins-which are essential for peroxisome biogenesis, proliferation, and protein import-are present in all of these amoebae. Likewise, our in silico analyses allowed us to identify a complete set of peroxins in Naegleria lovaniensis and three novel peroxin homologues in Naegleria gruberi. Thus, our results indicate that peroxisomes are present in these three genera of free-living amoebae and that they have a similar peroxin complement despite belonging to different evolutionary lineages.
Topics: Acanthamoeba castellanii; Balamuthia mandrillaris; Catalase; Microscopy, Electron, Transmission; Peroxins; Peroxisomes; Phylogeny
PubMed: 32602891
DOI: 10.1093/gbe/evaa129