-
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 -
Antimicrobial Agents and Chemotherapy Jan 2021Pathogenic and opportunistic free-living amoebae such as spp. can cause keratitis ( keratitis [AK]), which may ultimately lead to permanent visual impairment or...
Pathogenic and opportunistic free-living amoebae such as spp. can cause keratitis ( keratitis [AK]), which may ultimately lead to permanent visual impairment or blindness. can also cause rare but usually fatal granulomatous amoebic encephalitis (GAE). Current therapeutic options for AK require a lengthy treatment with nonspecific drugs that are often associated with adverse effects. Recent developments in the field led us to target cAMP pathways, specifically phosphodiesterase. Guided by computational tools, we targeted the phosphodiesterase RegA. Computational studies led to the construction and validation of a homology model followed by a virtual screening protocol guided by induced-fit docking and chemical scaffold analysis using our medicinal and biological chemistry (MBC) chemical library. Subsequently, 18 virtual screening hits were prioritized for further testing against , identifying amoebicidal hits containing piperidine and urea imidazole cores. Promising activities were confirmed in the resistant cyst form of the amoeba and in additional clinical strains, increasing their therapeutic potential. Mechanism-of-action studies revealed that these compounds produce apoptosis through reactive oxygen species (ROS)-mediated mitochondrial damage. These chemical families show promise for further optimization to produce effective antiacanthamoebal drugs.
Topics: Acanthamoeba Keratitis; Acanthamoeba castellanii; Amebiasis; Amebicides; Humans; Infectious Encephalitis
PubMed: 33229426
DOI: 10.1128/AAC.01749-20 -
Journal of Medicinal Chemistry Jan 2024is an amoeba that inhabits soil and water in every part of the world. Acanthamoeba infection of the eye causes keratitis and can lead to a loss of vision. Current...
is an amoeba that inhabits soil and water in every part of the world. Acanthamoeba infection of the eye causes keratitis and can lead to a loss of vision. Current treatment options are only moderately effective, have multiple harmful side effects, and are tedious. In our study, we developed a novel drug screening method to define the inhibitory properties of potential new drugs against in vitro. We found that the clinically used carbonic anhydrase inhibitors, acetazolamide, ethoxzolamide, and dorzolamide, have promising antiamoebic properties.
Topics: Acanthamoeba castellanii; Carbonic Anhydrase Inhibitors; Amoeba; Drug Evaluation, Preclinical
PubMed: 38150360
DOI: 10.1021/acs.jmedchem.3c01020 -
Nature Communications Jun 2021Chlamydiae are highly successful strictly intracellular bacteria associated with diverse eukaryotic hosts. Here we analyzed metagenome-assembled genomes of the "Genomes...
Chlamydiae are highly successful strictly intracellular bacteria associated with diverse eukaryotic hosts. Here we analyzed metagenome-assembled genomes of the "Genomes from Earth's Microbiomes" initiative from diverse environmental samples, which almost double the known phylogenetic diversity of the phylum and facilitate a highly resolved view at the chlamydial pangenome. Chlamydiae are defined by a relatively large core genome indicative of an intracellular lifestyle, and a highly dynamic accessory genome of environmental lineages. We observe chlamydial lineages that encode enzymes of the reductive tricarboxylic acid cycle and for light-driven ATP synthesis. We show a widespread potential for anaerobic energy generation through pyruvate fermentation or the arginine deiminase pathway, and we add lineages capable of molecular hydrogen production. Genome-informed analysis of environmental distribution revealed lineage-specific niches and a high abundance of chlamydiae in some habitats. Together, our data provide an extended perspective of the variability of chlamydial biology and the ecology of this phylum of intracellular microbes.
Topics: Acanthamoeba; Animals; Chlamydia; Citric Acid Cycle; Ecosystem; Fishes; Genome, Bacterial; Gills; Hydrolases; Metagenome; Phylogeny; Pyruvic Acid; Whole Genome Sequencing
PubMed: 34188040
DOI: 10.1038/s41467-021-24294-3 -
Anais Da Academia Brasileira de Ciencias 2023Within each ecosystem, organisms and populations maintain a complex set of relationships. These interactions can determine the distribution area of a species and play an...
Within each ecosystem, organisms and populations maintain a complex set of relationships. These interactions can determine the distribution area of a species and play an essential role in its evolution. Parasites are ubiquitous components of nature and have a high influence on various aspects of the biology and ecology of organisms, affecting the populations of their hosts and, therefore, their communities and ecosystems. Free-living amoebae are unicellular organisms that can be found in water, soil or air. Some species are of great importance in human health. In Hydra, there are several reports of Hydramoeba hydroxena infections. In this work we present a double parasitosis: two concatenated infectious periods in the host polyp of Hydra vulgaris and Hydra vulgaris pedunculata for three freshwater bodies in the province of Buenos Aires, Argentina. Hydramoeba sp. and Acanthoamoeba sp. unchain a series of anatomical lesions that in all cases cause the death of the polyps due to total disintegration. This finding becomes important at a sanitary level due to the appearance of Acanthoamoeba sp. in waters associated with human recreational activities; For the Hydra genus, the importance lies at an ecological and evolutionary level, considering the possible impact on its natural populations.
Topics: Humans; Animals; Amoeba; Ecosystem; Hydra; Acanthamoeba; Argentina
PubMed: 37162082
DOI: 10.1590/0001-3765202320211025 -
Virulence Dec 2018Acanthamoeba castellanii (Ac) are ubiquitously distributed in nature, and by contaminating medical devices such as heart valves and contact lenses, they cause a broad...
Extracellular vesicles and vesicle-free secretome of the protozoa Acanthamoeba castellanii under homeostasis and nutritional stress and their damaging potential to host cells.
Acanthamoeba castellanii (Ac) are ubiquitously distributed in nature, and by contaminating medical devices such as heart valves and contact lenses, they cause a broad range of clinical presentations to humans. Although several molecules have been described to play a role in Ac pathogenesis, including parasite host-tissue invasion and escaping of host-defense, little information is available on their mechanisms of secretion. Herein, we describe the molecular components secreted by Ac, under different protein availability conditions to simulate host niches. Ac extracellular vesicles (EVs) were morphologically and biochemically characterized. Dynamic light scattering analysis of Ac EVs identified polydisperse populations, which correlated to electron microscopy measurements. High-performance thin liquid chromatography of Ac EVs identified phospholipids, steryl-esters, sterol and free-fatty acid, the last two also characterized by GC-MS. Secretome composition (EVs and EVs-free supernatants) was also determined and proteins biological functions classified. In peptone-yeast-glucose (PYG) medium, a total of 179 proteins were identified (21 common proteins, 89 exclusive of EVs and 69 in EVs-free supernatant). In glucose alone, 205 proteins were identified (134 in EVs, 14 common and 57 proteins in EVs-free supernatant). From those, stress response, oxidative and protein and amino acid metabolism proteins prevailed. Qualitative differences were observed on carbohydrate metabolism enzymes from Krebs cycle and pentose phosphate shunt. Serine proteases and metalloproteinases predominated. Analysis of the cytotoxicity of Ac EVs (upon uptake) and EVs-free supernatant to epithelial and glioblastoma cells revealed a dose-dependent effect. Therefore, the Ac secretome differs depending on nutrient conditions, and is also likely to vary during infection.
Topics: Acanthamoeba castellanii; Amebiasis; Animals; Cell Line; Extracellular Vesicles; Homeostasis; Humans; Protein Transport; Proteome; Proteomics; Protozoan Proteins; Secretory Pathway
PubMed: 29560793
DOI: 10.1080/21505594.2018.1451184 -
ACS Biomaterials Science & Engineering Feb 2020In many situations, cells migrate through tiny orifices. Examples include the extravasation of immune cells from the bloodstream for fighting infections, the...
In many situations, cells migrate through tiny orifices. Examples include the extravasation of immune cells from the bloodstream for fighting infections, the infiltration of cancer cells during metastasis, and the migration of human pathogens. An extremely motile and medically relevant type of human pathogen is . In the study presented here, we investigated how a combination of microparticles and microstructured interfaces controls the migration of trophozoites. The microinterfaces comprised well-defined micropillar arrays, and the trophozoites easily migrated through the given constrictions by adapting the shape and size of their intracellular vacuoles and by adapting intracellular motion. After feeding the trophozoite cells in microinterfaces with synthetic, stiff microparticles of various sizes and shapes, their behavior changed drastically: if the particles were smaller than the micropillar gap, migration was still possible. If the cells incorporated particles larger than the pillar gap, they could become immobilized but could also display remarkable problem-solving capabilities. For example, they turned rod-shaped microparticles such that their short axis fit through the pillar gap or they transported the particles above the structure. As migration is a crucial contribution to pathogenicity and is also relevant to other biological processes in microenvironments, such as cancer metastasis, our results provide an interesting strategy for controlling the migration of cells containing intracellular particles by microstructured interfaces that serve as migration-limiting environments.
Topics: Acanthamoeba castellanii; Amoeba; Animals; Humans; Trophozoites
PubMed: 32215319
DOI: 10.1021/acsbiomaterials.9b00496 -
Pathogens and Global Health Oct 2023This study examines the effects of three different drugs with metformin, acarbose and pioglitazone active ingredients used for antidiabetic purposes on cysts and...
This study examines the effects of three different drugs with metformin, acarbose and pioglitazone active ingredients used for antidiabetic purposes on cysts and trophozoites. Cultures of trophozoites and cysts were prepared to test the anti-amoebic activity of metformin, acarbose and pioglitazone. Cultures were then prepared for cyst and trophozoite forms and parasites were exposed to different concentrations (0.750 mg/mL, 0.375 mg/mL, 0.186 mg/mL and 0.093 mg/mL) of metformin, acarbose and pioglitazone. As a result of the study, the reproductive potential suppressive effects and conversion from trophozoite form to cyst form of all three substances on trophozoites and cysts were determined. Parasites were counted at 12, 24 and 48 hours in the cell counter after staining with trypan blue. In comparison of the effects of metformin, acarbose and pioglitazone used in the study on trophozoites and cysts, it was observed that all three substances were statistically effective against cysts and trophozoites at a concentration of 0.750 mg/mL. Furthermore, it was determined that all concentrations of the three active substances included in the study significantly decreased the rate of cyst formation even at the end of the 7th day. In this context, it was determined that all three substances have amebicidal effects, and they significantly inhibit the transformation of trophozoites to cyst form. It is thought that these active substances, which are currently used as anti-diabetic, can be used in combination with other drugs in infections based on our study findings.
Topics: Animals; Trophozoites; Acanthamoeba castellanii; Hypoglycemic Agents; Acarbose; Pioglitazone; Metformin
PubMed: 36436006
DOI: 10.1080/20477724.2022.2151859 -
The Korean Journal of Parasitology Oct 2018Acanthamoeba spp. are free-living protozoa that are opportunistic pathogens for humans. Cysteine proteases of Acanthamoeba have been partially characterized, but their...
Acanthamoeba spp. are free-living protozoa that are opportunistic pathogens for humans. Cysteine proteases of Acanthamoeba have been partially characterized, but their biochemical and functional properties are not clearly understood yet. In this study, we isolated a gene encoding cysteine protease of A. castellanii (AcCP) and its biochemical and functional properties were analyzed. Sequence analysis of AcCP suggests that this enzyme is a typical cathepsin L family cysteine protease, which shares similar structural characteristics with other cathepsin L-like enzymes. The recombinant AcCP showed enzymatic activity in acidic conditions with an optimum at pH 4.0. The recombinant enzyme effectively hydrolyzed human proteins including hemoglobin, albumin, immunoglobuins A and G, and fibronectin at acidic pH. AcCP mainly localized in lysosomal compartment and its expression was observed in both trophozoites and cysts. AcCP was also identified in cultured medium of A. castellanii. Considering to lysosomal localization, secretion or release by trophozoites and continuous expression in trophozoites and cysts, the enzyme could be a multifunctional enzyme that plays important biological functions for nutrition, development and pathogenicity of A. castellanii. These results also imply that AcCP can be a promising target for development of chemotherapeutic drug for Acanthamoeba infections.
Topics: Acanthamoeba castellanii; Amino Acid Sequence; Base Sequence; Cysteine Proteases; Hydrogen-Ion Concentration; Lysosomes; Trophozoites
PubMed: 30419726
DOI: 10.3347/kjp.2018.56.5.409 -
Translational Vision Science &... Nov 2020The purpose of this study was to analyze the concentration-dependent effects of biguanides (polyhexamethylene biguanide [PHMB], chlorhexidine [CH]); diamidines...
PURPOSE
The purpose of this study was to analyze the concentration-dependent effects of biguanides (polyhexamethylene biguanide [PHMB], chlorhexidine [CH]); diamidines (hexamidine-diisethionate [HD], propamidine-isethionate [PD], dibromopropamidine-diisethionate [DD]); natamycin (NM); miltefosine (MF); povidone iodine (PVPI), and chlorin e6 PDT on trophozoites and cysts, in vitro.
METHODS
Strain 1BU was cultured in peptone-yeast extract-glucose medium. Trophozoites or cysts were cultured in PYG medium containing each agent at 100%, 50%, and 25% of maximum concentration for 2 hours. The percentage of dead trophozoites was determined using a non-radioactive cytotoxicity assay and trypan blue staining. Treated cysts were also maintained on non-nutrient agar () plates and observed for 3 weeks.
RESULTS
All tested drugs displayed significant cytotoxic effects on 1BU cells based on the biochemical and staining-based viability assays tested. On non-nutrient agar plates, neither trophozoites nor freshly formed cysts were observed after PHMB, PD, NM, and PVPI treatment, respectively, within 3 weeks. However, CH-, HD-, DD-, and MF-treated cysts could excyst, multiply, and encyst again.
CONCLUSIONS
The off-label drugs PHMB, PD, NM, and PVPI are under in vitro conditions more effective against strain 1BU than CH, HD, DD, and MF. Our findings also suggest that the non-nutrient agar plate assay should be considered as method of choice for the in vitro analysis of the treatment efficacy of anti-amoebic agents.
TRANSLATIONAL RELEVANCE
Ophthalmologists may optimize the treatment regime against keratitis by pre-testing the in vitro susceptibilities of the strain against drugs of interest with the non-nutrient agar plate assay.
Topics: Acanthamoeba castellanii; Amebicides; Animals; Escherichia coli; Triazenes; Trophozoites
PubMed: 33262903
DOI: 10.1167/tvst.9.12.29