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Ahmad Zamzuri M‘AI, Abd Majid FN, Mihat M, Ibrahim SS, Ismail M, Abd Aziz S, Mohamed Z, Rejali L, Yahaya H, Abdullah Z, Hassan MR, Dapari R, Mohd Isa AM. Systematic Review of Brain-Eating Amoeba: A Decade Update. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:3021. [PMID: 36833715 PMCID: PMC9964342 DOI: 10.3390/ijerph20043021] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 02/07/2023] [Accepted: 02/08/2023] [Indexed: 05/09/2023]
Abstract
INTRODUCTION Primary amoebic meningoencephalitis (PAM) is a rare but lethal infection of the brain caused by a eukaryote called Naegleria fowleri (N. fowleri). The aim of this review is to consolidate the recently published case reports of N. fowleri infection by describing its epidemiology and clinical features with the goal of ultimately disseminating this information to healthcare personnel. METHODS A comprehensive literature search was carried out using PubMed, Web of Science, Scopus, and OVID databases until 31 December 2022 by two independent reviewers. All studies from the year 2013 were extracted, and quality assessments were carried out meticulously prior to their inclusion in the final analysis. RESULTS A total of 21 studies were selected for qualitative analyses out of the 461 studies extracted. The cases were distributed globally, and 72.7% of the cases succumbed to mortality. The youngest case was an 11-day-old boy, while the eldest was a 75-year-old. Significant exposure to freshwater either from recreational activities or from a habit of irrigating the nostrils preceded onset. The symptoms at early presentation included fever, headache, and vomiting, while late sequalae showed neurological manifestation. An accurate diagnosis remains a challenge, as the symptoms mimic bacterial meningitis. Confirmatory tests include the direct visualisation of the amoeba or the use of the polymerase chain reaction method. CONCLUSIONS N. fowleri infection is rare but leads to PAM. Its occurrence is worldwide with a significant risk of fatality. The suggested probable case definition based on the findings is the acute onset of fever, headache, and vomiting with meningeal symptoms following exposure to freshwater within the previous 14 days. Continuous health promotion and health education activities for the public can help to improve knowledge and awareness prior to engagement in freshwater activities.
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Affiliation(s)
| | - Farah Nabila Abd Majid
- Department of Psychiatry, Hospital Canselor Tuanku Muhriz, Faculty of Medicine, National University of Malaysia Jalan Yaacob Latif, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia
| | - Massitah Mihat
- Negeri Sembilan State Health Department, Jalan Rasah, Seremban 70300, Malaysia
| | - Siti Salwa Ibrahim
- Negeri Sembilan State Health Department, Jalan Rasah, Seremban 70300, Malaysia
| | - Muhammad Ismail
- Negeri Sembilan State Health Department, Jalan Rasah, Seremban 70300, Malaysia
| | - Suriyati Abd Aziz
- Negeri Sembilan State Health Department, Jalan Rasah, Seremban 70300, Malaysia
| | - Zuraida Mohamed
- Negeri Sembilan State Health Department, Jalan Rasah, Seremban 70300, Malaysia
| | - Lokman Rejali
- Negeri Sembilan State Health Department, Jalan Rasah, Seremban 70300, Malaysia
| | - Hazlina Yahaya
- Public Health Division, Ministry of Health Malaysia, Putrajaya 62000, Malaysia
| | - Zulhizzam Abdullah
- Public Health Division, Ministry of Health Malaysia, Putrajaya 62000, Malaysia
| | - Mohd Rohaizat Hassan
- Department of Community Health, Faculty of Medicine, National University of Malaysia Jalan Yaacob Latif, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia
- Borneo Medical and Health Research Centre, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu 88400, Malaysia
| | - Rahmat Dapari
- Department of Community Health, Universiti Putra Malaysia, Serdang 43400, Malaysia
| | - Abd Majid Mohd Isa
- Faculty of Education and Liberal Arts, INTI International University, Persiaran Perdana BBN Putra Nilai, Nilai 71800, Malaysia
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Chen CW, Moseman EA. Pro-inflammatory cytokine responses to Naegleria fowleri infection. FRONTIERS IN TROPICAL DISEASES 2023; 3. [PMID: 37065537 PMCID: PMC10104475 DOI: 10.3389/fitd.2022.1082334] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Naegleria fowleri, or the “brain-eating amoeba,” is responsible for a rare, but lethal, infection known as primary amoebic meningoencephalitis (PAM). Confirmed PAM cases have seen both a rise in numbers, as well as expansion of geographic range over the past several decades. There is no effective therapy for PAM and the clinical prognosis remains grim with a mortality rate over 95%. The role of the immune response in disease prevention and disease severity remains unclear. In this review, we explore potential roles of inflammatory immune responses to N. fowleri in disease pathogenesis with a primary focus on pro-inflammatory cytokines IL-1, IL-6, and TNFα. We also discuss modulating proinflammatory cytokines as an additional immune therapy in PAM treatment.
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Lê HG, Kang JM, Võ TC, Na BK. Naegleria fowleri Cathepsin B Induces a Pro-Inflammatory Immune Response in BV-2 Microglial Cells via NF-κB and AP-1 Dependent-MAPK Signaling Pathway. Int J Mol Sci 2022; 23:ijms23158388. [PMID: 35955520 PMCID: PMC9369353 DOI: 10.3390/ijms23158388] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/20/2022] [Accepted: 07/27/2022] [Indexed: 11/30/2022] Open
Abstract
Naegleria fowleri is a ubiquitous protozoa parasite that can cause primary amoebic meningoencephalitis (PAM), a fatal brain infection in humans. Cathepsin Bs of N. fowleri (NfCBs) are multifamily enzymes. Although their pathogenic mechanism in PAM is not clearly understood yet, NfCBs have been proposed as pathogenic factors involved in the pathogenicity of amoeba. In this study, the immune response of BV-2 microglial cells induced by NfCB was analyzed. Recombinant NfCB (rNfCB) evoked enhanced expressions of TLR-2, TLR-4, and MyD88 in BV-2 microglial cells. This enzyme also induced an elevated production of several pro-inflammatory cytokines such as TNF-α, IL-1α, IL-1β, and IL-6 and iNOS in cells. The inhibition of mitogen-activated protein kinases (MAPKs), including JNK, p38, and ERK, effectively reduced the production of these pro-inflammatory cytokines. The rNfCB-induced production of pro-inflammatory cytokines in BV-2 microglial cells was suppressed by inhibiting NF-kB and AP-1. Phosphorylation and nuclear translocation of p65 in cells were also enhanced by rNfCB. These results suggest that NfCB can induce a pro-inflammatory immune response in BV-2 microglial cells via the NF-κB- and AP-1-dependent MAPK signaling pathways. Such a NfCB-induced pro-inflammatory immune response in BV-2 microglial cells might contribute to the pathogenesis of PAM caused by amoeba, by exacerbating deleterious immune responses and tissue damages in N. fowleri-infected foci of the brain.
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Affiliation(s)
- Hương Giang Lê
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea; (H.G.L.); (J.-M.K.); (T.C.V.)
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Jung-Mi Kang
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea; (H.G.L.); (J.-M.K.); (T.C.V.)
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Tuấn Cường Võ
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea; (H.G.L.); (J.-M.K.); (T.C.V.)
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Byoung-Kuk Na
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea; (H.G.L.); (J.-M.K.); (T.C.V.)
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
- Correspondence:
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4
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Malych R, Füssy Z, Ženíšková K, Arbon D, Hampl V, Hrdý I, Sutak R. The response of Naegleria gruberi to oxidative stress. Metallomics 2022; 14:6527579. [PMID: 35150262 DOI: 10.1093/mtomcs/mfac009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/06/2022] [Indexed: 11/14/2022]
Abstract
Aerobic organisms require oxygen for respiration but must simultaneously cope with oxidative damages inherently linked with this molecule. Unicellular amoeboflagellates of the genus Naegleria, containing both free-living species and opportunistic parasite, thrive in aerobic environments. However, they are also known to maintain typical features of anaerobic organisms. Here, we describe the mechanisms of oxidative damage mitigation in Naegleria gruberi and focus on the molecular characteristics of three noncanonical proteins interacting with oxygen and its derived reactive forms. We show that this protist expresses hemerythrin, protoglobin and an aerobic-type rubrerythrin, with spectral properties characteristic of the cofactors they bind. We provide evidence that protoglobin and hemerythrin interact with oxygen in vitro and confirm the mitochondrial localization of rubrerythrin by immunolabeling. Our proteomic analysis and immunoblotting following heavy metal treatment revealed upregulation of hemerythrin, while rotenone treatment resulted in an increase in rubrerythrin protein levels together with vast upregulation of alternative oxidase. Our study provided new insights into the mechanisms employed by N. gruberi to cope with different types of oxidative stress and allowed us to propose specific roles for three unique and understudied proteins: hemerythrin, protoglobin and rubrerythrin.
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Affiliation(s)
- Ronald Malych
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Zoltán Füssy
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Kateřina Ženíšková
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Dominik Arbon
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Vladimír Hampl
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Ivan Hrdý
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Robert Sutak
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
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5
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Various brain-eating amoebae: the protozoa, the pathogenesis, and the disease. Front Med 2021; 15:842-866. [PMID: 34825341 DOI: 10.1007/s11684-021-0865-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/25/2021] [Indexed: 10/19/2022]
Abstract
Among various genera of free-living amoebae prevalent in nature, some members are identified as causative agents of human encephalitis, in which Naegleria fowleri followed by Acanthamoeba spp. and Balamuthia mandrillaris have been successively discovered. As the three dominant genera responsible for infections, Acanthamoeba and Balamuthia work as opportunistic pathogens of granulomatous amoebic encephalitis in immunocompetent and immunocompromised individuals, whereas Naegleria induces primary amoebic meningoencephalitis mostly in healthy children and young adults as a more violent and deadly disease. Due to the lack of typical symptoms and laboratory findings, all these amoebic encephalitic diseases are difficult to diagnose. Considering that subsequent therapies are also affected, all these brain infections cause significant mortality worldwide, with more than 90% of the cases being fatal. Along with global warming and population explosion, expanding areas of human and amoebae activity in some regions lead to increased contact, resulting in more serious infections and drawing increased public attention. In this review, we summarize the present information of these pathogenic free-living amoebae, including their phylogeny, classification, biology, and ecology. The mechanisms of pathogenesis, immunology, pathophysiology, clinical manifestations, epidemiology, diagnosis, and therapies are also discussed.
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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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7
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Güémez A, García E. Primary Amoebic Meningoencephalitis by Naegleria fowleri: Pathogenesis and Treatments. Biomolecules 2021; 11:biom11091320. [PMID: 34572533 PMCID: PMC8469197 DOI: 10.3390/biom11091320] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/20/2021] [Accepted: 08/25/2021] [Indexed: 12/29/2022] Open
Abstract
Naegleria fowleri is a free-living amoeba (FLA) that is commonly known as the "brain-eating amoeba." This parasite can invade the central nervous system (CNS), causing an acute and fulminating infection known as primary amoebic meningoencephalitis (PAM). Even though PAM is characterized by low morbidity, it has shown a mortality rate of 98%, usually causing death in less than two weeks after the initial exposure. This review summarizes the most recent information about N. fowleri, its pathogenic molecular mechanisms, and the neuropathological processes implicated. Additionally, this review includes the main therapeutic strategies described in case reports and preclinical studies, including the possible use of immunomodulatory agents to decrease neurological damage.
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8
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Marcos‐López M, Rodger HD. Amoebic gill disease and host response in Atlantic salmon (
Salmo salar
L.): A review. Parasite Immunol 2020; 42:e12766. [DOI: 10.1111/pim.12766] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 04/13/2020] [Accepted: 06/16/2020] [Indexed: 12/16/2022]
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9
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Shi D, Chahal KK, Oto P, Nothias LF, Debnath A, McKerrow JH, Podust LM, Abagyan R. Identification of Four Amoebicidal Nontoxic Compounds by a Molecular Docking Screen of Naegleria fowleri Sterol Δ8-Δ7-Isomerase and Phenotypic Assays. ACS Infect Dis 2019; 5:2029-2038. [PMID: 31583882 PMCID: PMC7085920 DOI: 10.1021/acsinfecdis.9b00227] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Naegleria fowleri is a free-living amoeba causing primary amoebic meningoencephalitis, a rapid-onset brain infection in humans with over 97% mortality rate. Despite some progress in the treatment of the disease, there is no single, proven, evidence-based treatment with a high probability of cure. Here we report the chemical library screening and experimental identification of four new compounds with amoebicidal effects against N. fowleri. The chemical library was screened by molecular docking against a homology model of sterol Δ8-Δ7 isomerase (NfERG2). Thirty top-ranking hits were then tested in a cell-based assay for antiproliferative/amoebicidal activities. Eight chemicals exhibited nearly 100% inhibition of N. fowleri at 50 μM, with the EC50 values ranging from 6 to 25 μM. A cell toxicity assay using human HEK-293 cells was also performed. Four of the compounds preferentially kill amoeba cells with no apparent human cell toxicities. These compounds fall into two distinct chemical scaffolds with druglike properties.
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Affiliation(s)
- Da Shi
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
| | - Kirti Kandhwal Chahal
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
- Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Hisar-Delhi Bypass Road, Hisar, Haryana 125001, India
| | - Patricia Oto
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
| | - Louis-Felix Nothias
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
| | - Anjan Debnath
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
| | - James H. McKerrow
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
| | - Larissa M. Podust
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
| | - Ruben Abagyan
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego,9500 Gilman Drive, La Jolla, California, 92093, United States of America
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10
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Jahangeer M, Mahmood Z, Munir N, Waraich U, Tahir IM, Akram M, Ali Shah SM, Zulfqar A, Zainab R. Naegleria fowleri: Sources of infection, pathophysiology, diagnosis, and management; a review. Clin Exp Pharmacol Physiol 2019; 47:199-212. [DOI: 10.1111/1440-1681.13192] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/07/2019] [Accepted: 10/12/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Muhammad Jahangeer
- Department of Biochemistry Government College University Faisalabad Faisalabad Pakistan
| | - Zahed Mahmood
- Department of Biochemistry Government College University Faisalabad Faisalabad Pakistan
| | - Naveed Munir
- Department of Biochemistry Government College University Faisalabad Faisalabad Pakistan
- College of Allied Health Professionals Directorate of Medical Sciences Government College University Faisalabad Faisalabad Pakistan
| | | | - Imtiaz Mahmood Tahir
- College of Allied Health Professionals Directorate of Medical Sciences Government College University Faisalabad Faisalabad Pakistan
| | - Muhammad Akram
- Department of Eastern Medicine Directorate of Medical Sciences Government College University Faisalabad Faisalabad Pakistan
| | - Syed Muhammad Ali Shah
- Department of Eastern Medicine Directorate of Medical Sciences Government College University Faisalabad Faisalabad Pakistan
| | - Ayesha Zulfqar
- Department of Biochemistry Government College University Faisalabad Faisalabad Pakistan
| | - Rida Zainab
- Department of Eastern Medicine Directorate of Medical Sciences Government College University Faisalabad Faisalabad Pakistan
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Marcos-López M, Espinosa CR, Rodger HD, O'Connor I, MacCarthy E, Esteban MA. Oxidative stress is associated with late-stage amoebic gill disease in farmed Atlantic salmon (Salmo salar L.). JOURNAL OF FISH DISEASES 2018; 41:383-387. [PMID: 28836667 DOI: 10.1111/jfd.12699] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 07/10/2017] [Accepted: 07/12/2017] [Indexed: 06/07/2023]
Affiliation(s)
- M Marcos-López
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
- FishVet Group Ireland, Oranmore, Ireland
| | - C Ruiz Espinosa
- Department of Cell Biology and Histology, Faculty of Biology, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", University of Murcia, Murcia, Spain
| | - H D Rodger
- FishVet Group Ireland, Oranmore, Ireland
| | - I O'Connor
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
| | - E MacCarthy
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland
| | - M A Esteban
- Department of Cell Biology and Histology, Faculty of Biology, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", University of Murcia, Murcia, Spain
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Martínez-Castillo M, Santos-Argumedo L, Galván-Moroyoqui JM, Serrano-Luna J, Shibayama M. Toll-like receptors participate in Naegleria fowleri recognition. Parasitol Res 2017; 117:75-87. [PMID: 29128927 DOI: 10.1007/s00436-017-5666-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 10/25/2017] [Indexed: 02/06/2023]
Abstract
Naegleria fowleri is a protozoan that invades the central nervous system and causes primary amoebic meningoencephalitis. It has been reported that N. fowleri induces an important inflammatory response during the infection. In the present study, we evaluated the roles of Toll-like receptors in the recognition of N. fowleri trophozoites by human mucoepithelial cells, analyzing the expression and production of innate immune response mediators. After amoebic interactions with NCI-H292 cells, the expression and production levels of IL-8, TNF-α, IL-1β, and human beta defensin-2 were evaluated by RT-PCR, ELISA, immunofluorescence, and dot blot assays, respectively. To determine whether the canonical signaling pathways were engaged, we used different inhibitors, namely, IMG-2005 for MyD88 and BAY 11-7085 for the nuclear factor NFkB. Our results showed that the expression and production of the pro-inflammatory cytokines and beta defensin-2 were induced by N. fowleri mainly through the canonical TLR4 pathway in a time-dependent manner.
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Affiliation(s)
- Moisés Martínez-Castillo
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, 07360, Mexico City, Mexico
| | - Leopoldo Santos-Argumedo
- Department of Molecular Biomedicine, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, 07360, Mexico City, Mexico
| | - José Manuel Galván-Moroyoqui
- Department of Medicine and Health Sciences, University of Sonora, Boulevard Luis Donaldo Colosio and Francisco Q. Salazar S/N, 83000, Hermosillo, SON, Mexico
| | - Jesús Serrano-Luna
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, 07360, Mexico City, Mexico
| | - Mineko Shibayama
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, 07360, Mexico City, Mexico.
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Siddiqui R, Ali IKM, Cope JR, Khan NA. Biology and pathogenesis of Naegleria fowleri. Acta Trop 2016; 164:375-394. [PMID: 27616699 DOI: 10.1016/j.actatropica.2016.09.009] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/06/2016] [Accepted: 09/06/2016] [Indexed: 12/13/2022]
Abstract
Naegleria fowleri is a protist pathogen that can cause lethal brain infection. Despite decades of research, the mortality rate related with primary amoebic meningoencephalitis owing to N. fowleri remains more than 90%. The amoebae pass through the nose to enter the central nervous system killing the host within days, making it one of the deadliest opportunistic parasites. Accordingly, we present an up to date review of the biology and pathogenesis of N. fowleri and discuss needs for future research against this fatal infection.
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St John JA, Walkden H, Nazareth L, Beagley KW, Ulett GC, Batzloff MR, Beacham IR, Ekberg JAK. Burkholderia pseudomallei Rapidly Infects the Brain Stem and Spinal Cord via the Trigeminal Nerve after Intranasal Inoculation. Infect Immun 2016; 84:2681-8. [PMID: 27382023 PMCID: PMC4995904 DOI: 10.1128/iai.00361-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 06/27/2016] [Indexed: 11/20/2022] Open
Abstract
Infection with Burkholderia pseudomallei causes melioidosis, a disease with a high mortality rate (20% in Australia and 40% in Southeast Asia). Neurological melioidosis is particularly prevalent in northern Australian patients and involves brain stem infection, which can progress to the spinal cord; however, the route by which the bacteria invade the central nervous system (CNS) is unknown. We have previously demonstrated that B. pseudomallei can infect the olfactory and trigeminal nerves within the nasal cavity following intranasal inoculation. As the trigeminal nerve projects into the brain stem, we investigated whether the bacteria could continue along this nerve to penetrate the CNS. After intranasal inoculation of mice, B. pseudomallei caused low-level localized infection within the nasal cavity epithelium, prior to invasion of the trigeminal nerve in small numbers. B. pseudomallei rapidly invaded the trigeminal nerve and crossed the astrocytic barrier to enter the brain stem within 24 h and then rapidly progressed over 2,000 μm into the spinal cord. To rule out that the bacteria used a hematogenous route, we used a capsule-deficient mutant of B. pseudomallei that does not survive in the blood and found that it also entered the CNS via the trigeminal nerve. This suggests that the primary route of entry is via the nerves that innervate the nasal cavity. We found that actin-mediated motility could facilitate initial infection of the olfactory epithelium. Thus, we have demonstrated that B. pseudomallei can rapidly infect the brain and spinal cord via the trigeminal nerve branches that innervate the nasal cavity.
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Affiliation(s)
- James A St John
- Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Heidi Walkden
- Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Queensland, Australia
| | - Lynn Nazareth
- Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Queensland, Australia
| | - Kenneth W Beagley
- Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Glen C Ulett
- School of Medical Science, Griffith University, Gold Coast, Queensland, Australia Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Michael R Batzloff
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Ifor R Beacham
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Jenny A K Ekberg
- Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Queensland, Australia Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
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NLRP3 Inflammasome Activation in THP-1 Target Cells Triggered by Pathogenic Naegleria fowleri. Infect Immun 2016; 84:2422-8. [PMID: 27297387 DOI: 10.1128/iai.00275-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/06/2016] [Indexed: 01/06/2023] Open
Abstract
Naegleria fowleri, known as the brain-eating amoeba, causes acute primary amoebic meningoencephalitis. During swimming and other recreational water activities, N. fowleri trophozoites penetrate the nasal mucosa and invade the olfactory bulbs, resulting in intense inflammatory reactions in the forebrain tissue. To investigate what kinds of inflammasome molecules are expressed in target cells due to N. fowleri infection, human macrophage cells (THP-1 cells) were cocultured with N. fowleri trophozoites in a noncontact system, and consequently, interleukin-1β (IL-1β) production was estimated. Caspase-1 activation and IL-1β production from THP-1 cells by Western blotting and the culture supernatant by enzyme-linked immunosorbent assay analysis were observed at 3 h after cocultivation. In addition, the increased expression of ASC and NLRP3, which make up an inflammasome complex, was also observed at 3 h after cocultivation. To confirm the caspase-1 activation and IL-1β production via the NLRP3 inflammasome in THP-1 cells triggered by N. fowleri trophozoites, THP-1 cells were pretreated with several inhibitors. The inhibition assay showed that CA-074 (a cathepsin B inhibitor), glybenclamide (an NLRP3 molecule inhibitor), and N-benzyloxycarbony-Val-Ala-Asp(O-methyl)-fluoromethylketone (Z-VAD-FMK; a caspase-1 inhibitor) reduced the levels of caspase-1 activation and IL-1β production from THP-1 cells. This study suggests that N. fowleri infection induces the NLRP3 inflammasome, which activates caspase-1 and subsequently produces IL-1β, thus resulting in inflammation.
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16
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Yu H, Yang J, Xiao Q, Lü Y, Zhou X, Xia L, Nie D. Regulation of high glucose-mediated mucin expression by matrix metalloproteinase-9 in human airway epithelial cells. Exp Cell Res 2015; 333:127-35. [PMID: 25704757 DOI: 10.1016/j.yexcr.2015.02.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/02/2015] [Accepted: 02/10/2015] [Indexed: 11/15/2022]
Abstract
Mucus hypersecretion is the key manifestation in patients with chronic inflammatory airway diseases and mucin 5AC (MUC5AC) is a major component of airway mucus. Matrix metalloproteinases (MMP)-9, have been found to be involved in the pathogenesis of inflammatory airway diseases. Hyperglycemia has been shown to be an independent risk factor for respiratory infections. We hypothesize that high glucose (HG)-regulates MMP-9 production and MMP-9 activity through nicotinamide adenine dinucleotide phosphate (NADPH)/reactive oxygen species (ROS) cascades pathways, leading to mucin production in human airway epithelial cells (16HBE). We show that HG increases MMP-9 production, MMP-9 activity and MUC5AC expression. These effects are prevented by small interfering RNA (siRNA) for MMP-9, indicating that HG-induced mucin production is MMP-9-dependent. HG activates MMP-9 production, MMP-9 activity and MUC5AC overproduction, which is inhibited by nPG, DMSO and DPI (inhibitors of ROS and NADPH), suggesting that HG-activated mucin synthesis is mediated by NADPH/ROS in 16HBE cells. These observations demonstrate an important role for MMP-9 activated by NADPH/ROS signaling pathways in regulating HG-induced MUC5AC expression. These findings may bring new insights into the molecular pathogenesis of the infections related to diabetes mellitus and lead to novel therapeutic intervention for mucin overproduction in chronic inflammatory airway diseases.
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Affiliation(s)
- Hongmei Yu
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, No. 1, Youyi Road, Yuzhong District, Chongqing 400016, China.
| | - Juan Yang
- Division of Respiratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Qian Xiao
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, No. 1, Youyi Road, Yuzhong District, Chongqing 400016, China
| | - Yang Lü
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, No. 1, Youyi Road, Yuzhong District, Chongqing 400016, China
| | - Xiangdong Zhou
- Division of Respiratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Li Xia
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, No. 1, Youyi Road, Yuzhong District, Chongqing 400016, China
| | - Daijing Nie
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, No. 1, Youyi Road, Yuzhong District, Chongqing 400016, China
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Dando SJ, Mackay-Sim A, Norton R, Currie BJ, St John JA, Ekberg JAK, Batzloff M, Ulett GC, Beacham IR. Pathogens penetrating the central nervous system: infection pathways and the cellular and molecular mechanisms of invasion. Clin Microbiol Rev 2014; 27:691-726. [PMID: 25278572 PMCID: PMC4187632 DOI: 10.1128/cmr.00118-13] [Citation(s) in RCA: 273] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The brain is well protected against microbial invasion by cellular barriers, such as the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB). In addition, cells within the central nervous system (CNS) are capable of producing an immune response against invading pathogens. Nonetheless, a range of pathogenic microbes make their way to the CNS, and the resulting infections can cause significant morbidity and mortality. Bacteria, amoebae, fungi, and viruses are capable of CNS invasion, with the latter using axonal transport as a common route of infection. In this review, we compare the mechanisms by which bacterial pathogens reach the CNS and infect the brain. In particular, we focus on recent data regarding mechanisms of bacterial translocation from the nasal mucosa to the brain, which represents a little explored pathway of bacterial invasion but has been proposed as being particularly important in explaining how infection with Burkholderia pseudomallei can result in melioidosis encephalomyelitis.
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Affiliation(s)
- Samantha J Dando
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Alan Mackay-Sim
- Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Robert Norton
- Townsville Hospital, Townsville, Queensland, Australia
| | - Bart J Currie
- Menzies School of Health Research and Royal Darwin Hospital, Darwin, Northern Territory, Australia
| | - James A St John
- Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Jenny A K Ekberg
- Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Michael Batzloff
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Glen C Ulett
- School of Medical Science and Griffith Health Institute, Griffith University, Gold Coast, Queensland, Australia
| | - Ifor R Beacham
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
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18
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Johnson L, Shah I, Loh AX, Vinall LE, Teixeira AS, Rousseau K, Holloway JW, Hardy R, Swallow DM. MUC5AC and inflammatory mediators associated with respiratory outcomes in the British 1946 birth cohort. Respirology 2014; 18:1003-10. [PMID: 23551418 PMCID: PMC3784974 DOI: 10.1111/resp.12092] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 01/10/2013] [Accepted: 01/24/2013] [Indexed: 01/21/2023]
Abstract
Background and objective: Dysregulation of respiratory mucins, MUC5AC in particular, has been implicated in respiratory disease and MUC5AC expression is up-regulated in response to environmental challenges and inflammatory mediators. The aim of this study was to examine the effect of genetic variation on susceptibility to common respiratory conditions. Methods: The association of MUC5AC and the closely linked genes MUC2 and MUC5B with respiratory outcomes was tested in the MRC National Survey of Health and Development, a longitudinal birth cohort of men and women born in 1946. Also examined were the functional variants of the genes encoding inflammatory mediators, IL13, IL1B, IL1RN, TNFA and ERBB1, for which there is a likely influence on MUC5AC expression and were explored potential gene-gene interactions with these inflammatory mediators. Results: Statistically significant associations between the 3'ter MUC5AC simple nucleotide polymorphism (SNP) rs1132440 and various non-independent respiratory outcomes (bronchitis, wheeze, asthma, hay fever) were reported while the adjacent loci show slight (but largely non-statistically significant) differences, presumably reflective of linkage disequilibrium (allelic association) across the region. A novel association between bronchitis and a non-synonymous functional ERBB1 SNP, rs2227983 (aka epidermal growth factor receptor:R497K, R521K) is also reported and evidence presented of interaction between MUC5AC and ERBB1 and between MUC5AC and IL1RN with respect to bronchitis. The ERBB1 result suggests a clear mechanism for a biological interaction in which the allelic variants of epidermal growth factor receptor differentially affect mucin expression. Conclusions: The MUC5AC association and the interactions with inflammatory mediators suggest that genetically determined differences in MUC5AC expression alter susceptibility to respiratory disease. SUMMARY AT A GLANCE This longitudinal cohort study shows occurrence of the common respiratory conditions bronchitis, wheeze, asthma and hay fever to be associated with genetic variation in a mucin gene, MUC5AC. Functional variation in the epidermal growth factor receptor (epidermal growth factor receptor encoded by ERBB1) is also associated with bronchitis and modulates the MUC5AC effect.
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Affiliation(s)
- Lauren Johnson
- Research Department of Genetics, Evolution and Environment, University College London Darwin Building, London, UK
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19
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Kim JH, Song AR, Sohn HJ, Lee J, Yoo JK, Kwon D, Shin HJ. IL-1β and IL-6 activate inflammatory responses of astrocytes againstNaegleria fowleriinfection via the modulation of MAPKs and AP-1. Parasite Immunol 2013. [DOI: 10.1111/pim.12021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- J.-H. Kim
- Department of Microbiology; Department of Molecular Science and Technology; Ajou University School of Medicine; Suwon Republic of Korea
| | - A.-R. Song
- Department of Microbiology; Department of Molecular Science and Technology; Ajou University School of Medicine; Suwon Republic of Korea
| | - H.-J. Sohn
- Department of Microbiology; Department of Molecular Science and Technology; Ajou University School of Medicine; Suwon Republic of Korea
| | - J. Lee
- Department of Microbiology; Department of Molecular Science and Technology; Ajou University School of Medicine; Suwon Republic of Korea
| | - J.-K. Yoo
- Department of Microbiology; Department of Molecular Science and Technology; Ajou University School of Medicine; Suwon Republic of Korea
| | - D. Kwon
- Department of Microbiology; School of Medicine; Kwandong University; Gangneung Republic of Korea
| | - H.-J. Shin
- Department of Microbiology; Department of Molecular Science and Technology; Ajou University School of Medicine; Suwon Republic of Korea
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20
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Abstract
Mucus pathology in cystic fibrosis (CF) has been known for as long as the disease has been recognized and is sometimes called mucoviscidosis. The disease is marked by mucus hyperproduction and plugging in many organs, which are usually most fatal in the airways of CF patients, once the problem of meconium ileus at birth is resolved. After the CF gene, CFTR, was cloned and its protein product identified as a cAMP-regulated Cl(-) channel, causal mechanisms underlying the strong mucus phenotype of the disease became obscure. Here we focus on mucin genes and polymeric mucin glycoproteins, examining their regulation and potential relationships to a dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR). Detailed examination of CFTR expression in organs and different cell types indicates that changes in CFTR expression do not always correlate with the severity of CF disease or mucus accumulation. Thus, the mucus hyperproduction that typifies CF does not appear to be a direct cause of a defective CFTR but, rather, to be a downstream consequence. In organs like the lung, up-regulation of mucin gene expression by inflammation results from chronic infection; however, in other instances and organs, the inflammation may have a non-infectious origin. The mucus plugging phenotype of the β-subunit of the epithelial Na(+) channel (βENaC)-overexpressing mouse is proving to be an archetypal example of this kind of inflammation, with a dehydrated airway surface/concentrated mucus gel apparently providing the inflammatory stimulus. Data indicate that the luminal HCO(3)(-) deficiency recently described for CF epithelia may also provide such a stimulus, perhaps by causing a mal-maturation of mucins as they are released onto luminal surfaces. In any event, the path between CFTR dysfunction and mucus hyperproduction has proven tortuous, and its unraveling continues to offer its own twists and turns, along with fascinating glimpses into biology.
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Affiliation(s)
- Silvia M Kreda
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, NC 27517-7248, USA
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21
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Yu H, Zhou X, Wen S, Xiao Q. Flagellin/TLR5 responses induce mucus hypersecretion by activating EGFR via an epithelial cell signaling cascades. Exp Cell Res 2012; 318:723-31. [DOI: 10.1016/j.yexcr.2011.12.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Revised: 12/12/2011] [Accepted: 12/16/2011] [Indexed: 11/26/2022]
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22
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Kim JH, Sohn HJ, Lee SH, Kwon D, Shin HJ. Induction of interleukin-8 by Naegleria fowleri lysates requires activation of extracellular signal-regulated kinase in human astroglial cells. Parasitol Res 2012; 111:587-92. [PMID: 22411631 PMCID: PMC7088079 DOI: 10.1007/s00436-012-2872-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 02/21/2012] [Indexed: 10/28/2022]
Abstract
Naegleria fowleri is a pathogenic free-living amoeba which causes primary amoebic meningoencephalitis in humans and experimental animals. To investigate the mechanisms of such inflammatory diseases, potential chemokine gene activation in human astroglial cells was investigated following treatment with N. fowleri lysates. We demonstrated that N. fowleri are potent inducers for the expression of interleukin-8 (IL-8) genes in human astroglial cells which was preceded by activation of extracellular signal-regulated kinase (ERK). In addition, N. fowleri lysates induces the DNA binding activity of activator protein-1 (AP-1), an important transcription factor for IL-8 induction. The specific mitogen-activated protein kinase kinase/ERK inhibitor, U0126, blocks N. fowleri-mediated AP-1 activation and subsequent IL-8 induction. N. fowleri-induced IL-8 expression requires activation of ERK in human astroglial cells. These findings indicate that treatment of N. fowleri on human astroglial cells leads to the activation of AP-1 and subsequent expression of IL-8 which are dependent on ERK activation. These results may help understand the N. fowleri-mediated upregulation of chemokine and cytokine expression in the astroglial cells.
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Affiliation(s)
- Jong-Hyun Kim
- Department of Microbiology, and Molecular Science & Technology, Ajou University School of Medicine, Suwon 443-721, Republic of Korea
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Yu H, Li Q, Zhou X, Kolosov VP, Perelman JM. Role of hyaluronan and CD44 in reactive oxygen species-induced mucus hypersecretion. Mol Cell Biochem 2011; 352:65-75. [PMID: 21308480 DOI: 10.1007/s11010-011-0740-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 01/27/2011] [Indexed: 02/05/2023]
Abstract
Mucus hypersecretion is an important manifestation in patients with chronic inflammatory airway diseases. Mucin 5AC (MUC5AC) is a major component of airway mucus. MUC5AC expression is regulated by epidermal growth factor receptor (EGFR) which can be activated by reactive oxygen species (ROS). Hyaluronan (HA), a linear glycosaminoglycan with molecular weights ranging from 2 × 10(5) to 1 × 10(7), is expressed in airway epithelium and can be depolymerized by ROS into hyaluronan fragments. The mechanisms through which fragmented HA exerts its biologic functions have been elucidated by interactions with its receptor CD44. The aim of our study was to examine the role of HA and CD44 in ROS-induced EGFR activation and MUC5AC expression. We exposed NCI-H292 cells to ROS generated by xanthine/xanthine oxidase (X/XO). ROS-induced EGFR phosphorylation, which was activated by tissue kallekrein (TK) activation and EGF release. We found ROS promoted CD44 co-immunoprecipitation with EGFR and MUC5AC up-regulation. These effects were mimicked by hyaluronan fragments. All the effects were inhibited by blocking CD44 or EGFR, suggesting that CD44 plays a critical role in ROS-induced MUC5AC up-regulation. These results show that ROS depolymerizes hyaluronan into fragments, and these fragments bind their receptor CD44 to induce TK activation, which cleaves EGF precursors into mature EGF to activate its receptor EGFR. Furthermore, we provide evidence that hyaluronan fragments are sufficient to induce CD44/EGFR interaction and EGFR signaling which lead to MUC5AC expression. The results indicate that the regulation of ROS-induced MUC5AC expression by hyaluronan and CD44 may provide important insights in the mechanism of mucus hypersecretion.
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Affiliation(s)
- Hongmei Yu
- Division of Respiratory Medicine, Second Affiliated Hospital, Chongqing Medical University, Yuzhong District, Chongqing, China
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