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Kot K, Kupnicka P, Tarnowski M, Tomasiak P, Kosik-Bogacka D, Łanocha-Arendarczyk N. The role of apoptosis and oxidative stress in the pathophysiology of Acanthamoeba spp. infection in the kidneys of hosts with different immunological status. Parasit Vectors 2023; 16:445. [PMID: 38041167 PMCID: PMC10693070 DOI: 10.1186/s13071-023-06052-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/10/2023] [Indexed: 12/03/2023] Open
Abstract
BACKGROUND Acanthamoeba spp. are opportunistic pathogens that cause inflammation, mostly in the brain, lungs and cornea. Recent reports indicate kidney dysfunction in hosts with systemic acanthamoebiasis. The aim of the study was to analyze the gene expression and protein concentration of NADPH oxidase 2 and 4 (NOX2 and NOX4, respectively) and nuclear erythroid 2-related factor (Nrf2) in the kidneys of hosts with systemic acanthamoebiasis. We also aimed to determine the protein and gene expressions of Bcl2, Bax, caspases 3 and 9. METHODS Mice were divided into four groups based on their immunological status and Acanthamoeba sp. infection: A, immunocompetent Acanthamoeba sp.-infected mice; AS, immunosuppressed Acanthamoeba sp.- infected mice; C, immunocompetent uninfected mice; CS, immunosuppressed uninfected mice. NOX2, NOX4 and Nrf2 were analyzed by quantitative reverse transcription PCR (qRT-PCR) and ELISA methods, while pro-apoptotic and anti-apoptotic proteins (Bax and Bcl-2, respectively), Cas9, Cas3 were analyzed by qRT-PCR and western blot methods. RESULTS: Increased gene expression and/or protein concentration of NOX2 and NOX4 were found in both immunocompetent and immunosuppressed mice infected with Acanthamoeba sp. (groups A and AS, respectively). Gene expression and/or protein concentration of Nrf2 were higher in group A than in control animals. Compared to control mice, in the AS group the expression of the Nrf2 gene was upregulated while the concentration of Nrf2 protein was decreased. Additionally in A group, higher gene and protein expression of Bcl-2, and lower gene as well as protein expression of Bax, caspases 3 and 9 were noted. In contrast, the AS group showed lower gene and protein expression of Bcl-2, and higher gene as well as protein expression of Bax, caspases 3 and 9. CONCLUSIONS This study is the first to address the mechanisms occurring in the kidneys of hosts infected with Acanthamoeba sp. The contact of Acanthamoeba sp. with the host cell surface and/or the oxidative burst caused by elevated levels of NOXs lead to an antioxidant response enhanced by the Nrf2 pathway. Acanthamoeba sp. have various strategies concerning apoptosis. In immunocompetent hosts, amoebae inhibit the apoptosis of kidney cells, and in immunosuppressed hosts, they lead to increased apoptosis by the intrinsic pathway and thus to a more severe course of the disease.
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Affiliation(s)
- Karolina Kot
- Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Szczecin, Poland.
| | - Patrycja Kupnicka
- Department of Biochemistry, Pomeranian Medical University in Szczecin, Szczecin, Poland
| | - Maciej Tarnowski
- Department of Physiology in Health Sciences, Pomeranian Medical University in Szczecin, Szczecin, Poland
| | - Patrycja Tomasiak
- Institute of Physical Culture Sciences, University of Szczecin, Szczecin, Poland
| | - Danuta Kosik-Bogacka
- Independent Laboratory of Pharmaceutical Botany, Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Szczecin, Poland
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Martín-Escolano R, Pérez-Cordón G, Arán VJ, Marín C, Sánchez-Moreno M, Rosales MJ. 5-Nitroindazole derivatives as potential therapeutic alternatives against Acanthamoeba castellanii. Acta Trop 2022; 232:106538. [PMID: 35618027 DOI: 10.1016/j.actatropica.2022.106538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/20/2022] [Accepted: 05/22/2022] [Indexed: 11/29/2022]
Abstract
Amoebas of the genus Acanthamoeba are distributed worldwide, including species with a high pathogenic capacity for humans. In a similar way to what occurs with other parasitic protozoa, the available treatments show variable effectiveness in addition to high toxicity, which demands the development of new treatments. Positive results of 5-nitroindazole derivatives against several protozoa parasites suggest that these compounds may be a promising tool for the development of efficient antiparasitic drugs. In the present work we have evaluated the in vitro activity of ten 5-nitroindazole derivatives against Acanthamoeba castellanii trophozoites and cysts. To that end, AlamarBlue Assay Reagent® was used to determine the activity against trophozoites compared to the reference drug chlorhexidine digluconate. Cytotoxicity of the compounds was evaluated using Vero cells. The activity on cysts was evaluated by light microscopy and using a Neubauer chamber to quantifying cysts and presence of trophozoites, as an indication of cyst. Our results showed the effectiveness of the 5-nitroindazole derivatives tested against both trophozoites and cysts of A. castellani highlighting 5-nitroindazole derivative 8 which showed a 80% activity on cysts, which is higher than that of the reference drug. Moreover, 5-nitroindazole derivatives 8, 9 and 10 were more effective on trophozoites than the reference drug showing IC50 values lower than 5 µM. Taking together these results, these 5-nitroindazole derivatives specially compound 8, might be a promising alternative for the development of more efficient treatments against A. castellani infection.
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Affiliation(s)
- Rubén Martín-Escolano
- Laboratory of Molecular & Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, CT27NJ, UK.
| | - Gregorio Pérez-Cordón
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain
| | - Vicente J Arán
- Instituto de Química Médica (IQM), Consejo Superior de Investigaciones Científicas (CSIC), Calle Juan de la Cierva 3, 28006 Madrid, Spain
| | - Clotilde Marín
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain
| | - Manuel Sánchez-Moreno
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain
| | - María José Rosales
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain.
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Concentrations of PGE2 and TXB2 in the Eyes of Mice with Disseminated Acanthamoebiasis. Pathogens 2022; 11:pathogens11040438. [PMID: 35456113 PMCID: PMC9025194 DOI: 10.3390/pathogens11040438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/01/2022] [Accepted: 04/01/2022] [Indexed: 02/04/2023] Open
Abstract
Previous studies have shown that Acanthamoeba spp. may invade the eyes by migrating along the optic nerve to the eyes from the brain. This study aimed to confirm the presence of inflammation in the eyes of mice with disseminated acanthamoebiasis by examining prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) concentrations in the eyes of immunocompetent and immunocompromised mice intranasally inoculated with Acanthamoeba spp. The PGE2 concentration was statistically significantly lower in the immunocompromised amoebae-infected mice on 8 dpi compared with the noninfected group of animals, and it was higher in the eyes of immunosuppressed amoebae-infected mice on 16 dpi than in the control group of animals. There was a statistically significant lower TXB2 concentration in the eyes of immunocompetent infected mice compared with the noninfected group on 8 dpi. However, on 24 dpi, we noted statistically significant higher TXB2 levels in the immunocompetent infected mice than in the control group. In immunocompromised mice, there was a lower TXB2 level on 8 dpi than in control mice. This study confirmed the existence of an inflammatory process in the eyes of immunocompetent and immunocompromised mice infected with Acanthamoeba spp. without damaged corneas.
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Sarink MJ, van der Meijs NL, Denzer K, Koenderman L, Tielens AGM, van Hellemond JJ. Three encephalitis-causing amoebae and their distinct interactions with the host. Trends Parasitol 2021; 38:230-245. [PMID: 34758928 DOI: 10.1016/j.pt.2021.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 10/11/2021] [Accepted: 10/18/2021] [Indexed: 01/21/2023]
Abstract
Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp. can cause devastating brain infections in humans which almost always result in death. The symptoms of the three infections overlap, but brain inflammation and the course of the disease differ, depending on the amoeba that is responsible. Understanding the differences between these amoebae can result in the development of strategies to prevent and treat these infections. Recently, numerous scientific advancements have been made in the understanding of pathogenicity mechanisms in general, and the basic biology, epidemiology, and the human immune response towards these amoebae in particular. In this review, we combine this knowledge and aim to identify which factors can explain the differences between the lethal brain infections caused by N. fowleri, B. mandrillaris, and Acanthamoeba spp.
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Affiliation(s)
- Maarten J Sarink
- Erasmus MC, University Medical Center Rotterdam, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands
| | - Nadia L van der Meijs
- Erasmus MC, University Medical Center Rotterdam, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands
| | - Kristin Denzer
- Center for Translational Immunology (CTI), University Medical Center Utrecht, Utrecht, The Netherlands
| | - Leo Koenderman
- Center for Translational Immunology (CTI), University Medical Center Utrecht, Utrecht, The Netherlands; Department of Respiratory Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Aloysius G M Tielens
- Erasmus MC, University Medical Center Rotterdam, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands
| | - Jaap J van Hellemond
- Erasmus MC, University Medical Center Rotterdam, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands.
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Morphological Description of the Early Events during the Invasion of Acanthamoeba castellanii Trophozoites in a Murine Model of Skin Irradiated under UV-B Light. Pathogens 2020; 9:pathogens9100794. [PMID: 32992452 PMCID: PMC7600863 DOI: 10.3390/pathogens9100794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 08/27/2020] [Accepted: 09/24/2020] [Indexed: 11/17/2022] Open
Abstract
Skin infections have been associated with Acanthamoeba, nevertheless the events during skin invasion and UV-B light effects on it are unknown. The early morphological events of Acanthamoeba castellanii skin invasion are shown in SKH-1 mice that were chronically UV-B light irradiated. Mice that developed skin lesions (group 1) were topical and intradermally inoculated with A. castellanii trophozoites and sacrificed 48 h or 18 days later. Mice that showed no skin lesions (group 2) were intradermally inoculated and sacrificed 24, 48 or 72 h later. Mice ventral areas were considered controls with and without trophozoites intradermally inoculated. Skin samples were processed by histological and immunohistochemistry techniques. In group 1, trophozoites were immunolocalized in dermal areas, hair cysts, sebaceous glands, and blood vessels, and collagen degradation was observed. One of these mice shown trophozoites in the spleen, liver, and brain. In group 2, few trophozoites nearby collagenolytic activity zones were observed. In control samples, nor histological damage and no trophozoites were observed. Adherence and collagenolytic activity by A. castellanii were corroborated in vitro. We can infer that UV-B light irradiated skin could favor A. castellanii invasiveness causing damage in sites as far away as the brain, confirming the invasive capacity and pathogenic potential of these amphizoic amoebae.
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Kot K, Kosik-Bogacka D, Wojtkowiak-Giera A, Kolasa-Wołosiuk A, Łanocha-Arendarczyk N. The expression of TLR2 and TLR4 in the kidneys and heart of mice infected with Acanthamoeba spp. Parasit Vectors 2020; 13:480. [PMID: 32958053 PMCID: PMC7507663 DOI: 10.1186/s13071-020-04351-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/11/2020] [Indexed: 01/04/2023] Open
Abstract
Background Acanthamoeba spp. are cosmopolitan protozoans that cause infections in the brain, as well as extracerebral infections in the cornea, lungs and skin. Little is known about the mechanisms of the immunological response to these parasites in organs which are not their main biotope. Therefore, the purpose of this study was to determine the expression of TLR2 and TLR4 in the kidneys and heart of Acanthamoeba spp.-infected mice, with respect to the host’s immunological status. Methods The mice were grouped into four groups: immunocompetent control mice; immunosuppressed control mice; immunocompetent Acanthamoeba spp.-infected mice; and immunosuppressed Acanthamoeba spp. infected mice. In the study, we used the amoebae T16 genotype which was isolated from a patient. The TLRs expressions in the kidneys and heart of mice were assessed by quantitative real-time polymerase chain reaction. Moreover, we visualized TLR2 and TLR4 proteins in the organs by immunohistochemical staining. Results In the kidneys, we observed a higher TLR2 expression in immunosuppressed mice at 24 days post-Acanthamoeba spp. infection (dpi) compared to the uninfected mice. There were no statistically significant differences in TLR4 expression in the kidneys between the immunocompetent and immunosuppressed mice, both of infected and uninfected mice. In the heart, we observed a difference in TLR2 expression in immunocompetent mice at 24 dpi compared to immunocompetent mice at 8 dpi. The immunocompetent Acanthamoeba spp.-infected mice had higher TLR4 expression at 8 dpi compared to the immunocompetent uninfected mice. Conclusions Our results indicate that TLR2 is involved in response to Acanthamoeba spp. infection in the kidneys, whereas in the heart, both studied TLRs are involved.![]()
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Affiliation(s)
- Karolina Kot
- Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland
| | - Danuta Kosik-Bogacka
- Independent of Pharmaceutical Botany, Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland.
| | - Agnieszka Wojtkowiak-Giera
- Department of Biology and Medical Parasitology, Poznan University of Medical Sciences, Fredry 10, 61-701, Poznan, Poland
| | - Agnieszka Kolasa-Wołosiuk
- Department of Histology and Embryology, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland
| | - Natalia Łanocha-Arendarczyk
- Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland
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Kot K, Kosik-Bogacka D, Kupnicka P, Łanocha-Arendarczyk N. Antioxidant defense in the eyes of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp. Parasit Vectors 2020; 13:123. [PMID: 32143731 PMCID: PMC7060556 DOI: 10.1186/s13071-020-3979-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/17/2020] [Indexed: 11/10/2022] Open
Abstract
Background Acanthamoeba spp. are ubiquitous pathogens which cause granulomatous amoebic encephalitis and disseminated infection. Moreover, Acanthamoeba spp. infection of the cornea leads to Acanthamoeba keratitis. Our previous study showed that the infection of an eyeball may also take place via the migration of trophozoites through the optic nerve from the brain to the eyes. The aim of the study was to analyze the activity of enzymatic antioxidants and the concentration of non-enzymatic antioxidant in the eyes of immunocompetent and immunocompromised mice with disseminated acanthamoebiasis. Results In the immunocompetent mice infected with Acanthamoeba spp. we noted a significant decrease in catalase activity at 8 and 16 days post-infection (dpi). Glutathione reductase activity was significantly lower at 16 dpi compared to the control group and glutathione concentration was statistically higher at 24 dpi than in the control group. In the immunosuppressed mice, a statistically significant increase in glutathione concentration in the eye samples was found at 16 dpi compared to those not infected with Acanthamoeba spp. In the immunosuppressed mice infected with Acanthamoeba spp., glutathione peroxidase activity was statistically lower at 8 dpi, and glutathione concentration was statistically significantly higher at 16 dpi compared to the control group. Conclusions The inflammatory response in the eyes of hosts with experimental acanthamoebiasis led to changes in the activity of enzymatic antioxidants and the content of non-enzymatic antioxidant. Therefore, the dysregulation of antioxidants may play a role in the pathomechanism of Acanthamoeba eye infection.![]()
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Affiliation(s)
- Karolina Kot
- Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland
| | - Danuta Kosik-Bogacka
- Independent of Pharmaceutical Botany, Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland.
| | - Patrycja Kupnicka
- Department of Biochemistry and Medical Chemistry, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland
| | - Natalia Łanocha-Arendarczyk
- Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Powstancow Wielkopolskich 72, 70-111, Szczecin, Poland
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Crothers JW, Hsu L, Marty FM. Fulminant Acanthamoeba castellanii Encephalitis in an Ibrutinib-Treated Patient. Open Forum Infect Dis 2020; 7:ofaa025. [PMID: 32055639 PMCID: PMC7008473 DOI: 10.1093/ofid/ofaa025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 01/17/2020] [Indexed: 12/17/2022] Open
Abstract
We report a case of fulminant Acanthamoeba castellanii encephalitis in a patient with chronic lymphocytic leukemia treated with ibrutinib. The unusually rapid neurologic decline and fatal outcome observed are probably related to alterations in immunologic function associated with inhibition of Bruton tyrosine kinase.
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Affiliation(s)
| | - Liangge Hsu
- Brigham and Women's Hospital, Boston, Massachusetts, USA
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Solaymani-Mohammadi S, Eckmann L, Singer SM. Interleukin (IL)-21 in Inflammation and Immunity During Parasitic Diseases. Front Cell Infect Microbiol 2019; 9:401. [PMID: 31867283 PMCID: PMC6904299 DOI: 10.3389/fcimb.2019.00401] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/11/2019] [Indexed: 12/30/2022] Open
Abstract
Parasitic diseases cause significant morbidity and mortality in the developing and underdeveloped countries. No efficacious vaccines are available against most parasitic diseases and there is a critical need for developing novel vaccine strategies for care. IL-21 is a pleiotropic cytokine whose functions in protection and immunopathology during parasitic diseases have been explored in limited ways. IL-21 and its cognate receptor, IL-21R, are highly expressed in parasitized organs of infected humans as well in murine models of the human parasitic diseases. Prior studies have indicated the ability of the IL-21/IL-21R signaling axis to regulate the effector functions (e.g., cytokine production) of T cell subsets by enhancing the expression of T-bet and STAT4 in human T cells, resulting in an augmented production of IFN-γ. Mice deficient for either IL-21 (Il21−/−) or IL-21R (Il21r−/−) showed significantly reduced inflammatory responses following parasitic infections as compared with their WT counterparts. Targeting the IL-21/IL-21R signaling axis may provide a novel approach for the development of new therapeutic agents for the prevention of parasite-induced immunopathology and tissue destruction.
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Affiliation(s)
- Shahram Solaymani-Mohammadi
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Lars Eckmann
- Department of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Steven M Singer
- Department of Biology, Georgetown University, Washington, DC, United States
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Expression of Toll-Like Receptors (TLR2 and TLR4) in the Eyes of Mice with Disseminated Acanthamoebiasis. BIOMED RESEARCH INTERNATIONAL 2019; 2019:1401894. [PMID: 31309100 PMCID: PMC6594330 DOI: 10.1155/2019/1401894] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/28/2019] [Indexed: 12/20/2022]
Abstract
Toll-like receptors (TLRs) play a key role in the innate immune response to numerous pathogens, including Acanthamoeba spp. The aim of this study was to determine the expression of TLR2 and TLR4 in the eyes of mice following intranasal infection with Acanthamoeba spp. in relation to the host's immunological status. Amoebae used in this study were isolated from the bronchial aspirate of a patient with acute myeloid leukemia (AML) and atypical symptoms of pneumonia. We found statistically significant differences in the expression of TLR2 and TLR4 in the eye of immunocompetent mice at 8, 16, and 24 days after Acanthamoeba spp. infection (dpi) compared to control group. Immunosuppressed mice showed significant differences in the expression of TLR2 at 16 and 24 dpi compared to uninfected animals. Our results indicate that TLR2 and TLR4 are upregulated in the eyes of mice in response to Acanthamoeba spp. We suggest that it is possible for trophozoites to migrate through the optic nerve from the brain to the eyes. The course of disseminated acanthamoebiasis may be influenced by the host's immunological status, and the observed changes in expression of TLR2 and TLR4 in the host's organs may indicate the role of these receptors in the pathomechanism of acanthamoebiasis.
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Efficient therapeutic effect of Nigella sativa aqueous extract and chitosan nanoparticles against experimentally induced Acanthamoeba keratitis. Parasitol Res 2019; 118:2443-2454. [PMID: 31144032 DOI: 10.1007/s00436-019-06359-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/16/2019] [Indexed: 10/26/2022]
Abstract
Acanthamoeba keratitis (AK) is a devastating, painful corneal infection, which may lead to loss of vision. The development of resistance and failure of the currently used drugs represent a therapeutic predicament. Thus, novel therapies with lethal effects on resistant Acanthamoeba are necessary to combat AK. In the present study, the curative effect of Nigella sativa aqueous extract (N. sativa) and chitosan nanoparticles (nCs) and both agents combined were assessed in experimentally induced AK. All inoculated corneas developed varying grades of AK. The study medications were applied on the 5th day postinoculation and were evaluated by clinical examination of the cornea and cultivation of corneal scraps. On the 10th day posttreatment, a 100% cure of AK was obtained with nCs (100 μg/ml) in grades 1 and 2 of corneal opacity as well as with N. sativa 60 mg/ml-nCs 100 μg/ml in grades 1, 2, and 3 of corneal opacity, highlighting a possible synergistic effect. On the 15th day posttreatment, a 100% cure was reached with N. sativa aqueous extract (60 mg/ml). Moreover, on the 20th day posttreatment, N. sativa (30 mg/ml) provided a cure rate of 87.5%, while nCs (50 μg/ml) as well as N. sativa 30 mg/ml-nCs 50 μg/ml yielded a cure rate of 75%; the lowest percentage of cure (25%) was obtained with chlorhexidine (0.02%), showing a non-significant difference compared to the parasite control. The clinical outcomes were in agreement with the results of corneal scrap cultivation. The results of the present study demonstrate the effectiveness of N. sativa aqueous extract and nCs (singly or combined) when used against AK, and these agents show potential for the development of new, effective, and safe therapeutic alternatives.
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