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Cloete HPP, Rautenbach Y, Leisewitz AL, Mellanby RJ, Thompson PN, Schoeman JP. Prevalence of co-infections with Ehrlichia spp. or Theileria spp. in dogs naturally infected with babesiosis in the Eastern Cape province. Vet Parasitol Reg Stud Reports 2024; 54:101092. [PMID: 39237242 DOI: 10.1016/j.vprsr.2024.101092] [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: 02/28/2024] [Revised: 07/22/2024] [Accepted: 07/31/2024] [Indexed: 09/07/2024]
Abstract
BACKGROUND Canine babesiosis and ehrlichiosis are tick-borne infections of great significance in South Africa. Theileriosis in dogs in South Africa is still poorly understood. Co-infection with multiple tick-borne diseases has been documented and is perceived as a common occurrence in South Africa. OBJECTIVES The main objective of this study was to determine the prevalence of co-infections with Ehrlichia canis or Theileria equi in dogs with babesiosis in the Eastern Cape province. There is a lack of data on canine tick-borne disease distribution in this region. Possible associations of population characteristics and haematological and biochemistry measures with a co-infection of E. canis or T. equi in these dogs were also investigated. METHOD The study population included 150 dogs naturally infected with babesiosis that presented to the Mdantsane State Veterinary Clinic between January 2021 and November 2021. Quantitative polymerase chain reaction was used to confirm the Babesia spp. that the dogs were infected with and to identify co-infections. Association with co-infection for the following parameters were evaluated: sex, breed, age, duration of illness, leukocyte count, band neutrophil count, monocyte count, platelet count, ARC, and serum globulin concentration. Positive and negative predictive values of monocytosis, leukopenia, band neutrophilia, thrombocytopenia, and non-regenerative absolute reticulocyte count for co-infection were also calculated. RESULTS Babesia rossi was identified in 149/150 samples and B. vogeli in only 1/150 samples. A co-infection prevalence of 2.0% (3/149; 95% CI: 0.4-5.7) with B. rossi and E. canis was found. No other co-infections were reported. No investigated variables showed significant associations with co-infections. Monocytosis, in particular, was not associated with co-infection. CONCLUSION Co-infection with other tick-borne diseases in dogs with babesiosis is uncommon in the Eastern Cape province. These findings raise the possibility that B. rossi may have a protective effect against other tick-borne diseases.
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Affiliation(s)
- Henry P P Cloete
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Old Soutpan Road, Onderstepoort, Pretoria, 0110, South Africa; Department of Small Animal Clinical Science, The University of Liverpool, Liverpool, L69 7ZX, United Kingdom.
| | - Yolandi Rautenbach
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Old Soutpan Road, Onderstepoort, Pretoria, 0110, South Africa
| | - Andrew L Leisewitz
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Old Soutpan Road, Onderstepoort, Pretoria, 0110, South Africa; Department of Clinical Studies, Auburn University College of Veterinary Medicine, 1130 Wire Road, Auburn, AL 36849, United States of America
| | - Richard J Mellanby
- The Royal (Dick) School of Veterinary Studies, Easter Bush Campus, University of Edinburgh, Midlothian, EH25 9RG, United Kingdom
| | - Peter N Thompson
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Old Soutpan Road, Onderstepoort, Pretoria, 0110, South Africa
| | - Johan P Schoeman
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Old Soutpan Road, Onderstepoort, Pretoria, 0110, South Africa
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Madesh S, McGill J, Jaworski DC, Ferm J, Liu H, Fitzwater S, Hove P, Ferm D, Nair A, Knox CA, Alizadeh K, Thackrah A, Ganta RR. Long-Term Protective Immunity against Ehrlichia chaffeensis Infection Induced by a Genetically Modified Live Vaccine. Vaccines (Basel) 2024; 12:903. [PMID: 39204029 PMCID: PMC11360114 DOI: 10.3390/vaccines12080903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Revised: 08/02/2024] [Accepted: 08/06/2024] [Indexed: 09/03/2024] Open
Abstract
Human monocytic ehrlichiosis, an emerging tick-borne disease, is caused by Ehrlichia chaffeensis. Infections with the pathogen are also common in the canine host. Our previous studies demonstrated that functional disruption within the E. chaffeensis phage head-to-tail connector protein gene results in bacterial attenuation, creating a modified live attenuated vaccine (MLAV). The MLAV confers protective immunity against intravenous and tick transmission challenges one month following vaccination. In this study, we evaluated the duration of MLAV protection. Dogs vaccinated with the MLAV were challenged with wild-type E. chaffeensis via intravenous infection at 4-, 8-, and 12-months post-vaccination. Immunized dogs rapidly cleared the wild-type pathogen infection and tested positive for bacteremia less frequently than unvaccinated controls. While immune responses varied among dogs, vaccinees consistently mounted IgG and CD4+ T-cell responses specific to E. chaffeensis throughout the assessment period. Our findings demonstrate that MLAV-mediated immune protection persists for at least one year against wild-type bacterial infection, marking a major advancement in combating this serious tick-borne disease. The data presented here serve as the foundation for further studies, elucidating the molecular mechanisms underlying virulence and vaccine development and aiding in preventing the diseases caused by E. chaffeensis and other tick-borne rickettsial pathogens.
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Affiliation(s)
- Swetha Madesh
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Jodi McGill
- Department of Veterinary Microbiology & Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA;
| | - Deborah C. Jaworski
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
| | - Jonathan Ferm
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Huitao Liu
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Shawna Fitzwater
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
| | - Paidashe Hove
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
| | - Dominica Ferm
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Arathy Nair
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
| | - Cheyenne A. Knox
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
| | - Kimia Alizadeh
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
| | - Ashley Thackrah
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
| | - Roman R. Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA; (S.M.); (D.C.J.); (J.F.); (H.L.); (S.F.); (P.H.); (D.F.); (A.N.); (C.A.K.); (K.A.); (A.T.)
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
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Guérin A, Moncada-Vélez M, Jackson K, Ogishi M, Rosain J, Mancini M, Langlais D, Nunez A, Webster S, Goyette J, Khan T, Marr N, Avery DT, Rao G, Waterboer T, Michels B, Neves E, Iracema Morais C, London J, Mestrallet S, Quartier dit Maire P, Neven B, Rapaport F, Seeleuthner Y, Lev A, Simon AJ, Montoya J, Barel O, Gómez-Rodríguez J, Orrego JC, L’Honneur AS, Soudée C, Rojas J, Velez AC, Sereti I, Terrier B, Marin N, García LF, Abel L, Boisson-Dupuis S, Reis J, Marinho A, Lisco A, Faria E, Goodnow CC, Vasconcelos J, Béziat V, Ma CS, Somech R, Casanova JL, Bustamante J, Franco JL, Tangye SG. Helper T cell immunity in humans with inherited CD4 deficiency. J Exp Med 2024; 221:e20231044. [PMID: 38557723 PMCID: PMC10983808 DOI: 10.1084/jem.20231044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 01/04/2024] [Accepted: 01/31/2024] [Indexed: 04/04/2024] Open
Abstract
CD4+ T cells are vital for host defense and immune regulation. However, the fundamental role of CD4 itself remains enigmatic. We report seven patients aged 5-61 years from five families of four ancestries with autosomal recessive CD4 deficiency and a range of infections, including recalcitrant warts and Whipple's disease. All patients are homozygous for rare deleterious CD4 variants impacting expression of the canonical CD4 isoform. A shorter expressed isoform that interacts with LCK, but not HLA class II, is affected by only one variant. All patients lack CD4+ T cells and have increased numbers of TCRαβ+CD4-CD8- T cells, which phenotypically and transcriptionally resemble conventional Th cells. Finally, patient CD4-CD8- αβ T cells exhibit intact responses to HLA class II-restricted antigens and promote B cell differentiation in vitro. Thus, compensatory development of Th cells enables patients with inherited CD4 deficiency to acquire effective cellular and humoral immunity against an unexpectedly large range of pathogens. Nevertheless, CD4 is indispensable for protective immunity against at least human papillomaviruses and Trophyrema whipplei.
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Affiliation(s)
- Antoine Guérin
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Marcela Moncada-Vélez
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | | | - Masato Ogishi
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Jérémie Rosain
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
- Study Center for Primary Immunodeficiencies, Necker Hospital for Sick Children, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Mathieu Mancini
- Department of Human Genetics, McGill University, Montreal, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
- Dahdaleh Institute of Genomic Medicine, McGill Research Centre on Complex Traits, McGill University, Montreal, Canada
| | - David Langlais
- Department of Human Genetics, McGill University, Montreal, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
- Dahdaleh Institute of Genomic Medicine, McGill Research Centre on Complex Traits, McGill University, Montreal, Canada
| | - Andrea Nunez
- Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Samantha Webster
- Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Jesse Goyette
- Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Taushif Khan
- Department of Human Immunology, Sidra Medicine, Doha, Qatar
- The Jackson Laboratory, Farmington, CT, USA
| | - Nico Marr
- Department of Human Immunology, Sidra Medicine, Doha, Qatar
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Danielle T. Avery
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Geetha Rao
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Tim Waterboer
- Division of Infections and Cancer Epidemiology, German Cancer Research Center, Heidelberg, Germany
| | - Birgitta Michels
- Division of Infections and Cancer Epidemiology, German Cancer Research Center, Heidelberg, Germany
| | - Esmeralda Neves
- Immunology Department—Pathology, University Hospital Center of Porto, Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine, Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
| | - Cátia Iracema Morais
- Immunology Department—Pathology, University Hospital Center of Porto, Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine, Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
| | - Jonathan London
- Service of Internal Medicine, Diaconesse-Croix Saint Simon Hospital, Paris, France
| | - Stéphanie Mestrallet
- Department of Internal Medicine and Infectious Diseases, Manchester Hospital, Charleville-Mézières, France
| | - Pierre Quartier dit Maire
- Pediatric Immunology-Hematology and Rheumatology Unit, Necker Hospital for Sick Children, Paris, France
| | - Bénédicte Neven
- Pediatric Immunology-Hematology and Rheumatology Unit, Necker Hospital for Sick Children, Paris, France
| | - Franck Rapaport
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Yoann Seeleuthner
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Atar Lev
- Department of Pediatrics and Immunology Service, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Aviv School of Medicine, Tel Aviv, Israel
| | - Amos J. Simon
- Department of Pediatrics and Immunology Service, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Aviv School of Medicine, Tel Aviv, Israel
| | - Jorge Montoya
- San Vicente de Paul University Hospital, Medellin, Colombia
| | - Ortal Barel
- The Genomic Unit, Sheba Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
| | - Julio Gómez-Rodríguez
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Julio C. Orrego
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Anne-Sophie L’Honneur
- Department of Virology, Paris Cité University and Cochin Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Camille Soudée
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Jessica Rojas
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Alejandra C. Velez
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Irini Sereti
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Benjamin Terrier
- Department of Internal Medicine, Cochin Hospital, Assistance Publique–Hôpitaux de Paris, Paris Cité University, Paris, France
| | - Nancy Marin
- Cellular Immunology and Immunogenetics Group, University of Antioquia UdeA, Medellin, Colombia
| | - Luis F. García
- Cellular Immunology and Immunogenetics Group, University of Antioquia UdeA, Medellin, Colombia
| | - Laurent Abel
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Stéphanie Boisson-Dupuis
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Joel Reis
- Dermatology Service, University Hospital Center of Porto, Porto, Portugal
| | - Antonio Marinho
- School of Medicine and Biomedical Sciences, University of Porto, Porto, Portugal
- Department of Clinical Immunology, University Hospital Center of Porto, Porto, Portugal
| | - Andrea Lisco
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Emilia Faria
- Allergy and Clinical Immunology Department, University Hospital Center of Coimbra, Coimbra, Portugal
| | - Christopher C. Goodnow
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Julia Vasconcelos
- Immunology Department—Pathology, University Hospital Center of Porto, Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine, Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
| | - Vivien Béziat
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
| | - Cindy S. Ma
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
| | - Raz Somech
- Department of Pediatrics and Immunology Service, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Aviv School of Medicine, Tel Aviv, Israel
| | - Jean-Laurent Casanova
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
- Howard Hughes Medical Institute, New York, NY, USA
- Department of Pediatrics, Necker Hospital for Sick Children, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Jacinta Bustamante
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France
- Paris Cité University, Imagine Institute, Paris, France
- Study Center for Primary Immunodeficiencies, Necker Hospital for Sick Children, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Jose Luis Franco
- Primary Immunodeficiencies Group, Department of Microbiology and Parasitology, School of Medicine, University of Antioquia UdeA, Medellin, Colombia
| | - Stuart G. Tangye
- Garvan Institute of Medical Research, Darlinghurst, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, University of New South Wales Sydney, Sydney, Australia
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4
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van Schaik EJ, Fratzke AP, Gregory AE, Dumaine JE, Samuel JE. Vaccine development: obligate intracellular bacteria new tools, old pathogens: the current state of vaccines against obligate intracellular bacteria. Front Cell Infect Microbiol 2024; 14:1282183. [PMID: 38567021 PMCID: PMC10985213 DOI: 10.3389/fcimb.2024.1282183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 03/01/2024] [Indexed: 04/04/2024] Open
Abstract
Obligate intracellular bacteria have remained those for which effective vaccines are unavailable, mostly because protection does not solely rely on an antibody response. Effective antibody-based vaccines, however, have been developed against extracellular bacteria pathogens or toxins. Additionally, obligate intracellular bacteria have evolved many mechanisms to subvert the immune response, making vaccine development complex. Much of what we know about protective immunity for these pathogens has been determined using infection-resolved cases and animal models that mimic disease. These studies have laid the groundwork for antigen discovery, which, combined with recent advances in vaccinology, should allow for the development of safe and efficacious vaccines. Successful vaccines against obligate intracellular bacteria should elicit potent T cell memory responses, in addition to humoral responses. Furthermore, they ought to be designed to specifically induce strong cytotoxic CD8+ T cell responses for protective immunity. This review will describe what we know about the potentially protective immune responses to this group of bacteria. Additionally, we will argue that the novel delivery platforms used during the Sars-CoV-2 pandemic should be excellent candidates to produce protective immunity once antigens are discovered. We will then look more specifically into the vaccine development for Rickettsiaceae, Coxiella burnetti, and Anaplasmataceae from infancy until today. We have not included Chlamydia trachomatis in this review because of the many vaccine related reviews that have been written in recent years.
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Affiliation(s)
- E J van Schaik
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
| | - A P Fratzke
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
- Charles River Laboratories, Reno, NV, United States
| | - A E Gregory
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| | - Jennifer E Dumaine
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
| | - J E Samuel
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
- Department of Veterinary Pathobiology, School of Veterinary Medicine, Texas A&M University (TAMU), College Station, TX, United States
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5
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Pessôa-Pereira D, Scorza BM, Cyndari KI, Beasley EA, Petersen CA. Modulation of Macrophage Redox and Apoptotic Processes to Leishmania infantum during Coinfection with the Tick-Borne Bacteria Borrelia burgdorferi. Pathogens 2023; 12:1128. [PMID: 37764937 PMCID: PMC10537792 DOI: 10.3390/pathogens12091128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/01/2023] [Accepted: 09/02/2023] [Indexed: 09/29/2023] Open
Abstract
Canine leishmaniosis (CanL) is a zoonotic disease caused by protozoan Leishmania infantum. Dogs with CanL are often coinfected with tick-borne bacterial pathogens, including Borrelia burgdorferi in the United States. These coinfections have been causally associated with hastened disease progression and mortality. However, the specific cellular mechanisms of how coinfections affect microbicidal responses against L. infantum are unknown. We hypothesized that B. burgdorferi coinfection impacts host macrophage effector functions, prompting L. infantum intracellular survival. In vitro experiments demonstrated that exposure to B. burgdorferi spirochetes significantly increased L. infantum parasite burden and pro-inflammatory responses in DH82 canine macrophage cells. Induction of cell death and generation of mitochondrial ROS were significantly decreased in coinfected DH82 cells compared to uninfected and L. infantum-infected cells. Ex vivo stimulation of PBMCs from L. infantum-seronegative and -seropositive subclinical dogs with spirochetes and/or total Leishmania antigens promoted limited induction of IFNγ. Coexposure significantly induced expression of pro-inflammatory cytokines and chemokines associated with Th17 differentiation and neutrophilic and monocytic recruitment in PBMCs from L. infantum-seropositive dogs. Excessive pro-inflammatory responses have previously been shown to cause CanL pathology. This work supports effective tick prevention and risk management of coinfections as critical strategies to prevent and control L. infantum progression in dogs.
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Affiliation(s)
- Danielle Pessôa-Pereira
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (D.P.-P.); (B.M.S.); (E.A.B.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA;
| | - Breanna M. Scorza
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (D.P.-P.); (B.M.S.); (E.A.B.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA;
| | - Karen I. Cyndari
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA;
- Department of Emergency Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA
| | - Erin A. Beasley
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (D.P.-P.); (B.M.S.); (E.A.B.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA;
| | - Christine A. Petersen
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (D.P.-P.); (B.M.S.); (E.A.B.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA;
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Beasley EA, Pessôa-Pereira D, Scorza BM, Petersen CA. Epidemiologic, Clinical and Immunological Consequences of Co-Infections during Canine Leishmaniosis. Animals (Basel) 2021; 11:ani11113206. [PMID: 34827938 PMCID: PMC8614518 DOI: 10.3390/ani11113206] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 11/24/2022] Open
Abstract
Simple Summary Canine leishmaniosis (CanL), the most severe, visceralizing form of disease caused by Leishmania infantum transmitted by phlebotomine sand flies. CanL is frequently diagnosed in the Mediterranean basin and South America, although it is also found in other regions, including the United States (U.S.). Dogs in these regions are at risk for co-infections, prominently tick-borne diseases. Our review examines epidemiologic, clinical, and immunologic mechanisms found during the most common eight CanL co-infections reported in published literature. Co-infections alter immunologic processes and disease progression impacting CanL diagnosis, therapeutic responses, and prognosis. Abstract Canine leishmaniosis (CanL) is a vector-borne, parasitic disease. CanL is endemic in the Mediterranean basin and South America but also found in Northern Africa, Asia, and the U.S. Regions with both competent sand fly vectors and L. infantum parasites are also endemic for additional infectious diseases that could cause co-infections in dogs. Growing evidence indicates that co-infections can impact immunologic responses and thus the clinical course of both CanL and the comorbid disease(s). The aim for this review is to summarize epidemiologic, clinical, and immunologic factors contributing to eight primary co-infections reported with CanL: Ehrlichia spp., Anaplasma spp., Borrelia spp., Babesia spp., Trypanosoma cruzi, Toxoplasma gondii, Dirofilaria immitis, Paracoccidioides braziliensis. Co-infection causes mechanistic differences in immunity which can alter diagnostics, therapeutic management, and prognosis of dogs with CanL. More research is needed to further explore immunomodulation during CanL co-infection(s) and their clinical impact.
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Affiliation(s)
- Erin A. Beasley
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
| | - Danielle Pessôa-Pereira
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
| | - Breanna M. Scorza
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
| | - Christine A. Petersen
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
- Correspondence:
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7
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Lin M, Xiong Q, Chung M, Daugherty SC, Nagaraj S, Sengamalay N, Ott S, Godinez A, Tallon LJ, Sadzewicz L, Fraser C, Dunning Hotopp JC, Rikihisa Y. Comparative Analysis of Genome of Ehrlichia sp. HF, a Model Bacterium to Study Fatal Human Ehrlichiosis. BMC Genomics 2021; 22:11. [PMID: 33407096 PMCID: PMC7789307 DOI: 10.1186/s12864-020-07309-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The genus Ehrlichia consists of tick-borne obligatory intracellular bacteria that can cause deadly diseases of medical and agricultural importance. Ehrlichia sp. HF, isolated from Ixodes ovatus ticks in Japan [also referred to as I. ovatus Ehrlichia (IOE) agent], causes acute fatal infection in laboratory mice that resembles acute fatal human monocytic ehrlichiosis caused by Ehrlichia chaffeensis. As there is no small laboratory animal model to study fatal human ehrlichiosis, Ehrlichia sp. HF provides a needed disease model. However, the inability to culture Ehrlichia sp. HF and the lack of genomic information have been a barrier to advance this animal model. In addition, Ehrlichia sp. HF has several designations in the literature as it lacks a taxonomically recognized name. RESULTS We stably cultured Ehrlichia sp. HF in canine histiocytic leukemia DH82 cells from the HF strain-infected mice, and determined its complete genome sequence. Ehrlichia sp. HF has a single double-stranded circular chromosome of 1,148,904 bp, which encodes 866 proteins with a similar metabolic potential as E. chaffeensis. Ehrlichia sp. HF encodes homologs of all virulence factors identified in E. chaffeensis, including 23 paralogs of P28/OMP-1 family outer membrane proteins, type IV secretion system apparatus and effector proteins, two-component systems, ankyrin-repeat proteins, and tandem repeat proteins. Ehrlichia sp. HF is a novel species in the genus Ehrlichia, as demonstrated through whole genome comparisons with six representative Ehrlichia species, subspecies, and strains, using average nucleotide identity, digital DNA-DNA hybridization, and core genome alignment sequence identity. CONCLUSIONS The genome of Ehrlichia sp. HF encodes all known virulence factors found in E. chaffeensis, substantiating it as a model Ehrlichia species to study fatal human ehrlichiosis. Comparisons between Ehrlichia sp. HF and E. chaffeensis will enable identification of in vivo virulence factors that are related to host specificity, disease severity, and host inflammatory responses. We propose to name Ehrlichia sp. HF as Ehrlichia japonica sp. nov. (type strain HF), to denote the geographic region where this bacterium was initially isolated.
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Affiliation(s)
- Mingqun Lin
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA.
| | - Qingming Xiong
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA
| | - Matthew Chung
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sean C Daugherty
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sushma Nagaraj
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Naomi Sengamalay
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sandra Ott
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Al Godinez
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Luke J Tallon
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Lisa Sadzewicz
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Claire Fraser
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Department of Medicine, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Julie C Dunning Hotopp
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Greenebaum Cancer Center, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA.
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8
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Torina A, Blanda V, Villari S, Piazza A, La Russa F, Grippi F, La Manna MP, Di Liberto D, de la Fuente J, Sireci G. Immune Response to Tick-Borne Hemoparasites: Host Adaptive Immune Response Mechanisms as Potential Targets for Therapies and Vaccines. Int J Mol Sci 2020; 21:ijms21228813. [PMID: 33233869 PMCID: PMC7699928 DOI: 10.3390/ijms21228813] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/12/2020] [Accepted: 11/12/2020] [Indexed: 02/06/2023] Open
Abstract
Tick-transmitted pathogens cause infectious diseases in both humans and animals. Different types of adaptive immune mechanisms could be induced in hosts by these microorganisms, triggered either directly by pathogen antigens or indirectly through soluble factors, such as cytokines and/or chemokines, secreted by host cells as response. Adaptive immunity effectors, such as antibody secretion and cytotoxic and/or T helper cell responses, are mainly involved in the late and long-lasting protective immune response. Proteins and/or epitopes derived from pathogens and tick vectors have been isolated and characterized for the immune response induced in different hosts. This review was focused on the interactions between tick-borne pathogenic hemoparasites and different host effector mechanisms of T- and/or B cell-mediated adaptive immunity, describing the efforts to define immunodominant proteins or epitopes for vaccine development and/or immunotherapeutic purposes. A better understanding of these mechanisms of host immunity could lead to the assessment of possible new immunotherapies for these pathogens as well as to the prediction of possible new candidate vaccine antigens.
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Affiliation(s)
- Alessandra Torina
- Area Diagnostica Sierologica, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy; (A.T.); (F.G.)
- Laboratorio di Riferimento OIE Theileriosi, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy
| | - Valeria Blanda
- Laboratorio di Riferimento OIE Theileriosi, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
- Correspondence:
| | - Sara Villari
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
| | - Antonio Piazza
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
| | - Francesco La Russa
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
| | - Francesca Grippi
- Area Diagnostica Sierologica, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy; (A.T.); (F.G.)
| | - Marco Pio La Manna
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (D.D.L.); (G.S.)
| | - Diana Di Liberto
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (D.D.L.); (G.S.)
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain;
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Guido Sireci
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (D.D.L.); (G.S.)
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9
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Ehrlichia chaffeensis Outer Membrane Protein 1-Specific Human Antibody-Mediated Immunity Is Defined by Intracellular TRIM21-Dependent Innate Immune Activation and Extracellular Neutralization. Infect Immun 2019; 87:IAI.00383-19. [PMID: 31548319 PMCID: PMC6867850 DOI: 10.1128/iai.00383-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/18/2019] [Indexed: 01/05/2023] Open
Abstract
Antibodies are essential for immunity against Ehrlichia chaffeensis, and protective mechanisms involve blocking of ehrlichial attachment or complement and Fcγ-receptor-dependent destruction. In this study, we determined that major outer membrane protein 1 (OMP-19) hypervariable region 1 (HVR1)-specific human monoclonal antibodies (huMAbs) are protective through conventional extracellular neutralization and, more significantly, through a novel intracellular TRIM21-mediated mechanism. Antibodies are essential for immunity against Ehrlichia chaffeensis, and protective mechanisms involve blocking of ehrlichial attachment or complement and Fcγ-receptor-dependent destruction. In this study, we determined that major outer membrane protein 1 (OMP-19) hypervariable region 1 (HVR1)-specific human monoclonal antibodies (huMAbs) are protective through conventional extracellular neutralization and, more significantly, through a novel intracellular TRIM21-mediated mechanism. Addition of OMP-1-specific huMAb EHRL-15 (IgG1) prevented infection by blocking attachment/entry, a mechanism previously reported; conversely, OMP-1-specific huMAb EHRL-4 (IgG3) engaged intracellular TRIM21 and initiated an immediate innate immune response and rapid intracellular degradation of ehrlichiae. EHRL-4-TRIM21-mediated inhibition was significantly impaired in TRIM21 knockout THP-1 cells. EHRL-4 interacted with cytosolic Fc receptor TRIM21, observed by confocal microscopy and confirmed by co-immunoprecipitation. E. chaffeensis-EHRL-4-TRIM21 complexes caused significant upregulation of proinflammatory cytokine/chemokine transcripts and resulted in rapid (<30 min) nuclear accumulation of NF-κB and TRIM21 and ehrlichial destruction. We investigated the role of TRIM21 in the autophagic clearance of ehrlichiae in the presence of EHRL-4. Colocalization between EHRL-4-opsonized ehrlichiae, polyubiquitinated TRIM21, autophagy regulators (ULK1 and beclin 1) and effectors (LC3 and p62), and lysosome-associated membrane protein 2 (LAMP2) was observed. Moreover, autophagic flux defined by conversion of LC3I to LC3II and accumulation and degradation of p62 was detected, and EHRL-4-mediated degradation of E. chaffeensis was abrogated by the autophagy inhibitor 3-methyladenine. Our results demonstrate that huMAbs are capable of inhibiting E. chaffeensis infection by distinct effector mechanisms: extracellularly by neutralization and intracellularly by engaging TRIM21, which mediates a rapid innate immune response that mobilizes the core autophagy components, triggering localized selective autophagic degradation of ehrlichiae.
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10
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Haloul M, Oliveira ERA, Kader M, Wells JZ, Tominello TR, El Andaloussi A, Yates CC, Ismail N. mTORC1-mediated polarization of M1 macrophages and their accumulation in the liver correlate with immunopathology in fatal ehrlichiosis. Sci Rep 2019; 9:14050. [PMID: 31575880 PMCID: PMC6773708 DOI: 10.1038/s41598-019-50320-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/02/2019] [Indexed: 12/13/2022] Open
Abstract
A polarized macrophage response into inflammatory (M1) or regenerative/anti-inflammatory (M2) phenotypes is critical in host response to multiple intracellular bacterial infections. Ehrlichia is an obligate Gram-negative intracellular bacterium that causes human monocytic ehrlichiosis (HME): a febrile illness that may progress to fatal sepsis with multi-organ failure. We have shown that liver injury and Ehrlichia-induced sepsis occur due to dysregulated inflammation. Here, we investigated the contribution of macrophages to Ehrlichia-induced sepsis using murine models of mild and fatal ehrlichiosis. Lethally-infected mice showed accumulation of M1 macrophages (iNOS-positive) in the liver. In contrast, non-lethally infected mice showed polarization of M2 macrophages and their accumulation in peritoneum, but not in the liver. Predominance of M1 macrophages in lethally-infected mice was associated with expansion of IL-17-producing T, NK, and NKT cells. Consistent with the in vivo data, infection of bone marrow-derived macrophages (BMM) with lethal Ehrlichia polarized M0 macrophages into M1 phenotype under an mTORC1-dependent manner, while infection with non-lethal Ehrlichia polarized these cells into M2 types. This work highlights that mTORC1-mediated polarization of macrophages towards M1 phenotype may contribute to induction of pathogenic immune responses during fatal ehrlichiosis. Targeting mTORC1 pathway may provide a novel aproach for treatment of HME.
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Affiliation(s)
- Mohamed Haloul
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Children's Cancer Hospital Egypt, 57357, Cairo, Egypt
| | - Edson R A Oliveira
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Muhamuda Kader
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jakob Z Wells
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tyler R Tominello
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Abdeljabar El Andaloussi
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Cecelia C Yates
- Nursing School, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nahed Ismail
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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11
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McGill JL, Wang Y, Ganta CK, Boorgula GDY, Ganta RR. Antigen-Specific CD4 +CD8 + Double-Positive T Cells Are Increased in the Blood and Spleen During Ehrlichia chaffeensis Infection in the Canine Host. Front Immunol 2018; 9:1585. [PMID: 30050533 PMCID: PMC6050357 DOI: 10.3389/fimmu.2018.01585] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 06/26/2018] [Indexed: 12/11/2022] Open
Abstract
Ehrlichia chaffeensis is an obligate intracellular bacterium belonging to the order, Rickettsiales and is a frequent cause of severe and fatal tick-borne infection in people in North America. The reservoir host for E. chaffeensis is the white-tailed deer, while humans and dogs are regarded as common incidental hosts. In dogs, we and others have shown that E. chaffeensis establishes a chronic infection that persists for several weeks to months, while promoting the development of Th1 and Th17 cellular responses and pathogen-specific humoral immunity. We demonstrate here that vaccination with a live, attenuated clone of E. chaffeensis bearing a targeted mutation in the Ech_0230 gene neither promotes the development of long-lived cellular or humoral immunity, nor confers protection against secondary wild-type E. chaffeensis challenge. In dogs, a population of mature CD4+CD8+ double-positive (DP) T cells exists in the periphery that shares similarities with the DP T cell populations that have been described in humans and swine. Little is known about the function of these cells, particularly in the context of infectious diseases. Here, we demonstrate that canine DP T cells expand significantly in response to E. chaffeensis infection. Using in vitro antigen recall assays, we further demonstrate that canine DP T cells undergo clonal expansion, produce IFNγ and IL-17, and upregulate expression of granzyme B and granulysin. Together, our results demonstrate that DP T cells accumulate in the host during E. chaffeensis infection, and suggest that alternative lymphocyte populations may participate in the immune response to tick-borne infections in the incidental host.
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Affiliation(s)
- Jodi L. McGill
- Department of Veterinary Microbiology and Preventative Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Ying Wang
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Chanran K. Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Gunavanthi D. Y. Boorgula
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Roman R. Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
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12
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Tomlinson JE, Žygelytė E, Grenier JK, Edwards MG, Cheetham J. Temporal changes in macrophage phenotype after peripheral nerve injury. J Neuroinflammation 2018; 15:185. [PMID: 29907154 PMCID: PMC6003127 DOI: 10.1186/s12974-018-1219-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 05/29/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Macrophages play a key role in peripheral nerve repair and demonstrate complex phenotypes that are highly dependent on microenvironmental cues. METHODS We determined temporal changes in macrophage gene expression over time using RNA sequencing after fluorescence-activated cell sorting (FACS) macrophage populations from injured peripheral nerve. We identified key upstream regulators and dominant pathways using ingenuity pathway analysis and confirmed these changes with NanoString technology. We then investigate the effects of extreme polarizers of macrophage phenotype (IL4 and IFNγ) on nerve regeneration. We determined macrophage gene expression in vivo at the site of peripheral nerve injury with NanoString technology, and assessed recovery from sciatic nerve injury by cranial tibial muscle weights and retrograde labeling motor neurons in mice with deletion of IL4 or IFNγ receptors. RESULTS We demonstrate that IL4R and IFNγR deletions provide complementary responses to polarization, and alter expression of genes associated with angiogenesis and axonal extension, but do not influence recovery from peripheral nerve transection at 8 weeks after repair. CONCLUSIONS Overall, this study provides a framework to evaluate the phenotype of macrophages over time, and provides a broader and more precise assessment of gene expression changes than has previously been commonly used. This data suggests ways in which polarization may be modulated to improve repair.
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Affiliation(s)
- Joy E. Tomlinson
- Cornell University College of Veterinary Medicine, Ithaca, NY USA
| | - Emilija Žygelytė
- Cornell University College of Veterinary Medicine, Ithaca, NY USA
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13
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Kader M, Alaoui-EL-Azher M, Vorhauer J, Kode BB, Wells JZ, Stolz D, Michalopoulos G, Wells A, Scott M, Ismail N. MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock. PLoS Pathog 2017; 13:e1006644. [PMID: 29049365 PMCID: PMC5663626 DOI: 10.1371/journal.ppat.1006644] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 10/31/2017] [Accepted: 09/11/2017] [Indexed: 01/19/2023] Open
Abstract
Severe hepatic inflammation is a common cause of acute liver injury following systemic infection with Ehrlichia, obligate Gram-negative intracellular bacteria that lack lipopolysaccharide (LPS). We have previously shown that type I IFN (IFN-I) and inflammasome activation are key host-pathogenic mediators that promote excessive inflammation and liver damage following fatal Ehrlichia infection. However, the underlying signals and mechanisms that regulate protective immunity and immunopathology during Ehrlichia infection are not well understood. To address this issue, we compared susceptibility to lethal Ixodes ovatus Ehrlichia (IOE) infection between wild type (WT) and MyD88-deficient (MyD88-/-) mice. We show here that MyD88-/- mice exhibited decreased inflammasome activation, attenuated liver injury, and were more resistant to lethal infection than WT mice, despite suppressed protective immunity and increased bacterial burden in the liver. MyD88-dependent inflammasome activation was also dependent on activation of the metabolic checkpoint kinase mammalian target of rapamycin complex 1 (mTORC1), inhibition of autophagic flux, and defective mitophagy in macrophages. Blocking mTORC1 signaling in infected WT mice and primary macrophages enhanced bacterial replication and attenuated inflammasome activation, suggesting autophagy promotes bacterial replication while inhibiting inflammasome activation. Finally, our data suggest TLR9 and IFN-I are upstream signaling mechanisms triggering MyD88-mediated mTORC1 and inflammasome activation in macrophages following Ehrlichia infection. This study reveals that Ehrlichia-induced liver injury and toxic shock are mediated by MyD88-dependent inflammasome activation and autophagy inhibition. Human monocytic ehrlichiosis (HME) is the most prevalent emerging infectious disease in the United States. Ehrlichia chaffeensis, etiologic agent of HME, is a Gram negative obligate intracellular bacterium transmitted by infected tick bites and can infect different cell type. Although Ehrlichia lack lipopolysaccharide (LPS), they induce potentially life threatening HME that mimic sepsis or toxic shock associated with multi-organ failure. The clinical diagnosis of HME is difficult, and definitive diagnosis is most often retrospective. Late antibiotic treatment is frequently ineffective in preventing disease progression to fatal multi-organ failure. Liver failure is one of the most serious complications and the most frequent cause of death in patients with HME, however we only have a limited understanding of how this liver failure is caused during fatal Ehrlichia infection. The objective of this study is to determine how LPS-negative Ehrlichia activates inflammatory responses in macrophages during Ehrlichia infection to promote liver damage. We show here that MyD88-signaling causes detrimental derangement of the immune system and subsequent liver damage by regulating two key innate immune events in macrophages: autophagy and inflammasome activation. Targeting host-pathogenic pathways in ehrlichiosis can be incorporated into future design of novel therapeutic approaches for HME.
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MESH Headings
- Animals
- Autophagy/immunology
- Blotting, Western
- Disease Models, Animal
- Ehrlichia/immunology
- Ehrlichiosis/immunology
- Ehrlichiosis/metabolism
- Enzyme-Linked Immunosorbent Assay
- Female
- Flow Cytometry
- Fluorescent Antibody Technique
- Image Processing, Computer-Assisted
- In Situ Nick-End Labeling
- Inflammasomes/immunology
- Inflammasomes/metabolism
- Liver Failure, Acute/immunology
- Liver Failure, Acute/metabolism
- Liver Failure, Acute/microbiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Confocal
- Microscopy, Electron, Transmission
- Myeloid Differentiation Factor 88/immunology
- Myeloid Differentiation Factor 88/metabolism
- Real-Time Polymerase Chain Reaction
- Shock, Septic/immunology
- Shock, Septic/metabolism
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Affiliation(s)
- Muhamuda Kader
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Mounia Alaoui-EL-Azher
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jennie Vorhauer
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Bhushan B Kode
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jakob Z. Wells
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Donna Stolz
- Center for Biologic Imaging, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - George Michalopoulos
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Alan Wells
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Melanie Scott
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Nahed Ismail
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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14
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CD11c+ T-bet+ memory B cells: Immune maintenance during chronic infection and inflammation? Cell Immunol 2017; 321:8-17. [PMID: 28838763 DOI: 10.1016/j.cellimm.2017.07.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/18/2017] [Indexed: 01/30/2023]
Abstract
CD11c+ T-bet+ B cells have now been detected and characterized in different experimental and clinical settings, in both mice and humans. Whether such cells are monolithic, or define subsets of B cells with different functions is not yet known. Our studies have identified CD11c+ IgM+ CD19hi splenic IgM memory B cells that appear at approximately three weeks post-ehrlichial infection, and persist indefinitely, during low-level chronic infection. Although the CD11c+ T-bet+ B cells we have described are distinct, they appear to share many features with similar cells detected under diverse conditions, including viral infections, aging, and autoimmunity. We propose that CD11c+ T-bet+ B cells as a group share characteristics of memory B cells that are maintained under conditions of inflammation and/or low-level chronic antigen stimulation. In some cases, these cells may be advantageous, by providing immunity to re-infection, but in others may be deleterious, by contributing to aged-associated autoimmune responses.
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15
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Abstract
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne infectious diseases caused by various members from the genera Ehrlichia and Anaplasma. Ehrlichia chaffeensis is the major etiologic agent of human monocytotropic ehrlichiosis (HME), while Anaplasma phagocytophilum is the major cause of human granulocytic anaplasmosis (HGA). The clinical manifestations of HME and HGA ranges from subclinical to potentially life-threatening diseases associated with multi-organ failure. Macrophages and neutrophils are the major target cells for Ehrlichia and Anaplasma, respectively. The threat to public health is increasing with newly emerging ehrlichial and anaplasma agents, yet vaccines for human ehrlichioses and anaplasmosis are not available, and therapeutic options are limited. This article reviews recent advances in the understanding of HME and HGA.
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16
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Tago D, Meyer DF. Economic Game Theory to Model the Attenuation of Virulence of an Obligate Intracellular Bacterium. Front Cell Infect Microbiol 2016; 6:86. [PMID: 27610355 PMCID: PMC4997789 DOI: 10.3389/fcimb.2016.00086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/09/2016] [Indexed: 12/19/2022] Open
Abstract
Diseases induced by obligate intracellular pathogens have a large burden on global human and animal health. Understanding the factors involved in the virulence and fitness of these pathogens contributes to the development of control strategies against these diseases. Based on biological observations, a theoretical model using game theory is proposed to explain how obligate intracellular bacteria interact with their host. The equilibrium in such a game shows that the virulence and fitness of the bacterium is host-triggered and by changing the host's defense system to which the bacterium is confronted, an evolutionary process leads to an attenuated strain. Although, the attenuation procedure has already been conducted in practice in order to develop an attenuated vaccine (e.g., with Ehrlichia ruminantium), there was a lack of understanding of the theoretical basis behind this process. Our work provides a model to better comprehend the existence of different phenotypes and some underlying evolutionary mechanisms for the virulence of obligate intracellular bacteria.
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Affiliation(s)
- Damian Tago
- La Recherche Agronomique Pour le Développement (CIRAD), UMR Contrôle des Maladies Animales, Exotiques et Émergentes (CMAEE)Petit-Bourg, France; Institut National de la Recherche Agronomique, UMR1309 CMAEEMontpellier, France
| | - Damien F Meyer
- La Recherche Agronomique Pour le Développement (CIRAD), UMR Contrôle des Maladies Animales, Exotiques et Émergentes (CMAEE)Petit-Bourg, France; Institut National de la Recherche Agronomique, UMR1309 CMAEEMontpellier, France
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17
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Abstract
Ehrlichia chaffeensis is an obligatory intracellular and cholesterol-dependent bacterium that has evolved special proteins and functions to proliferate inside leukocytes and cause disease. E. chaffeensis has a multigene family of major outer membrane proteins with porin activity and induces infectious entry using its entry-triggering protein to bind the human cell surface protein DNase X. During intracellular replication, three functional pairs of two-component systems are sequentially expressed to regulate metabolism, aggregation, and the development of stress-resistance traits for transmission. A type IV secretion effector of E. chaffeensis blocks mitochondrion-mediated host cell apoptosis. Several type I secretion proteins are secreted at the Ehrlichia-host interface. E. chaffeensis strains induce strikingly variable inflammation in mice. The central role of MyD88, but not Toll-like receptors, suggests that Ehrlichia species have unique inflammatory molecules. A recent report about transient targeted mutagenesis and random transposon mutagenesis suggests that stable targeted knockouts may become feasible in Ehrlichia.
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Affiliation(s)
- Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210;
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18
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Habib S, El Andaloussi A, Hisham A, Ismail N. NK Cell-Mediated Regulation of Protective Memory Responses against Intracellular Ehrlichial Pathogens. PLoS One 2016; 11:e0153223. [PMID: 27092553 PMCID: PMC4836677 DOI: 10.1371/journal.pone.0153223] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/25/2016] [Indexed: 11/18/2022] Open
Abstract
Ehrlichiae are gram-negative obligate intracellular bacteria that cause potentially fatal human monocytic ehrlichiosis. We previously showed that natural killer (NK) cells play a critical role in host defense against Ehrlichia during primary infection. However, the contribution of NK cells to the memory response against Ehrlichia remains elusive. Primary infection of C57BL/6 mice with Ehrlichia muris provides long-term protection against a second challenge with the highly virulent Ixodes ovatus Ehrlichia (IOE), which ordinarily causes fatal disease in naïve mice. Here, we show that the depletion of NK cells in E. muris-primed mice abrogates the protective memory response against IOE. Approximately, 80% of NK cell-depleted E. muris-primed mice succumbed to lethal IOE infection on days 8-10 after IOE infection, similar to naïve mice infected with the same dose of IOE. The lack of a recall response in NK cell-depleted mice correlated with an increased bacterial burden, extensive liver injury, decreased frequency of Ehrlichia-specific IFN-γ-producing memory CD4+ and CD8+ T-cells, and a low titer of Ehrlichia-specific antibodies. Intraperitoneal infection of mice with E. muris resulted in the production of IL-15, IL-12, and IFN-γ as well as an expansion of activated NKG2D+ NK cells. The adoptive transfer of purified E. muris-primed hepatic and splenic NK cells into Rag2-/-Il2rg-/- recipient mice provided protective immunity against challenge with E. muris. Together, these data suggest that E. muris-induced memory-like NK cells, which contribute to the protective, recall response against Ehrlichia.
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Affiliation(s)
- Samar Habib
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Abdeljabar El Andaloussi
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Ahmed Hisham
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Nahed Ismail
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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19
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McGill JL, Nair ADS, Cheng C, Rusk RA, Jaworski DC, Ganta RR. Vaccination with an Attenuated Mutant of Ehrlichia chaffeensis Induces Pathogen-Specific CD4+ T Cell Immunity and Protection from Tick-Transmitted Wild-Type Challenge in the Canine Host. PLoS One 2016; 11:e0148229. [PMID: 26841025 PMCID: PMC4739596 DOI: 10.1371/journal.pone.0148229] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 01/14/2016] [Indexed: 01/02/2023] Open
Abstract
Ehrlichia chaffeensis is a tick-borne rickettsial pathogen and the causative agent of human monocytic ehrlichiosis. Transmitted by the Amblyomma americanum tick, E. chaffeensis also causes disease in several other vertebrate species including white-tailed deer and dogs. We have recently described the generation of an attenuated mutant strain of E. chaffeensis, with a mutation in the Ech_0660 gene, which is able to confer protection from secondary, intravenous-administered, wild-type E. chaffeensis infection in dogs. Here, we extend our previous results, demonstrating that vaccination with the Ech_0660 mutant protects dogs from physiologic, tick-transmitted, secondary challenge with wild-type E. chaffeensis; and describing, for the first time, the cellular and humoral immune responses induced by Ech_0660 mutant vaccination and wild-type E. chaffeensis infection in the canine host. Both vaccination and infection induced a rise in E. chaffeensis-specific antibody titers and a significant Th1 response in peripheral blood as measured by E. chaffeensis antigen-dependent CD4+ T cell proliferation and IFNγ production. Further, we describe for the first time significant IL-17 production by peripheral blood leukocytes from both Ech_0660 mutant vaccinated animals and control animals infected with wild-type E. chaffeensis, suggesting a previously unrecognized role for IL-17 and Th17 cells in the immune response to rickettsial pathogens. Our results are a critical first step towards defining the role of the immune system in vaccine-induced protection from E. chaffeensis infection in an incidental host; and confirm the potential of the attenuated mutant clone, Ech_0660, to be used as a vaccine candidate for protection against tick-transmitted E. chaffeensis infection.
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Affiliation(s)
- Jodi L. McGill
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
| | - Arathy D. S. Nair
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America
| | - Chuanmin Cheng
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America
| | - Rachel A. Rusk
- Pathobiology Graduate Program, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America
| | - Deborah C. Jaworski
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America
| | - Roman R. Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America
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20
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Villaescusa A, García-Sancho M, Rodríguez-Franco F, Tesouro MÁ, Sainz Á. Effects of doxycycline on haematology, blood chemistry and peripheral blood lymphocyte subsets of healthy dogs and dogs naturally infected with Ehrlichia canis. Vet J 2015; 204:263-8. [PMID: 25957920 DOI: 10.1016/j.tvjl.2015.03.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 03/25/2015] [Accepted: 03/27/2015] [Indexed: 10/23/2022]
Abstract
Canine monocytic ehrlichiosis (CME), caused by Ehrlichia canis, is a vector-borne disease with a worldwide distribution. It has been proposed that the pathogenesis, clinical severity and outcome of disease caused by Ehrlichia spp. can be attributed to the immune response rather than to any direct rickettsial effect. Moreover, doxycycline, the antimicrobial of choice for the treatment of CME, has immunomodulatory and anti-inflammatory properties associated with blood leukocyte proliferation function, cytokine synthesis, and matrix metalloproteinase activity. In order to assess the potential effects of doxycycline, dependent and independent of its antimicrobial activity, the present study compared changes in haematology, blood chemistry and circulating lymphocyte subpopulations in 12 healthy dogs and 20 dogs with CME after doxycycline therapy. Some changes were recorded only in the CME affected dogs, probably due to the antimicrobial effect of doxycycline. However, increases in mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, platelet count and α2-globulins, and decreased plasma creatinine were observed in both healthy and CME affected dogs. The absolute count of B lymphocytes (CD21(+)) increased initially, but then decreased until the end of the study period in both groups. A potential effect of doxycycline unrelated to its antimicrobial activity against E. canis is suggested, taking into account the results observed both in healthy dogs and in dogs with CME.
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Affiliation(s)
- A Villaescusa
- Department of Animal Medicine and Surgery, College of Veterinary Medicine, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040, Madrid, Spain.
| | - M García-Sancho
- Department of Animal Medicine and Surgery, College of Veterinary Medicine, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040, Madrid, Spain
| | - F Rodríguez-Franco
- Department of Animal Medicine and Surgery, College of Veterinary Medicine, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040, Madrid, Spain
| | - M Á Tesouro
- Department of Veterinary Medicine, Surgery and Anatomy, College of Veterinary Medicine, University of León, Campus de Vegazana s/n, 24071, León, Spain
| | - Á Sainz
- Department of Animal Medicine and Surgery, College of Veterinary Medicine, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040, Madrid, Spain
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21
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Early induction of interleukin-10 limits antigen-specific CD4⁺ T cell expansion, function, and secondary recall responses during persistent phagosomal infection. Infect Immun 2014; 82:4092-103. [PMID: 25024370 DOI: 10.1128/iai.02101-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Diverse pathogens have evolved to survive and replicate in the endosomes or phagosomes of the host cells and establish persistent infection. Ehrlichiae are Gram-negative, intracellular bacteria that are transmitted by ticks. Ehrlichiae reside in the endosomes of the host phagocytic or endothelial cells and establish persistent infection in their vertebrate reservoir hosts. CD4(+) T cells play a critical role in protection against phagosomal infections. In the present study, we investigated the expansion, maintenance, and functional status of antigen-specific CD4(+) T cells during persistent Ehrlichia muris infection in wild-type and interleukin-10 (IL-10)-deficient mice. Our study indicated that early induction of IL-10 led to reduced inflammatory responses and impaired bacterial clearance during persistent Ehrlichia infection. Notably, we demonstrated that the functional production of gamma interferon (IFN-γ) by antigen-specific CD4(+) T cells maintained during a persistent phagosomal infection progressively deteriorates. The functional loss of IFN-γ production by antigen-specific CD4(+) T cells was reversed in the absence of IL-10. Furthermore, we demonstrated that transient blockade of IL-10 receptor during the T cell priming phase early in infection was sufficient to enhance the magnitude and the functional capacity of antigen-specific effector and memory CD4(+) T cells, which translated into an enhanced recall response. Our findings provide new insights into the functional status of antigen-specific CD4(+) T cells maintained during persistent phagosomal infection. The study supports the concept that a better understanding of the factors that influence the priming and differentiation of CD4(+) T cells may provide a basis to induce a protective immune response against persistent infections.
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22
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Type I interferons promote severe disease in a mouse model of lethal ehrlichiosis. Infect Immun 2014; 82:1698-709. [PMID: 24491580 DOI: 10.1128/iai.01564-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Human monocytic ehrlichiosis (HME) is caused by a tick-borne obligate intracellular pathogen of the order Rickettsiales. HME disease can range from mild to a fatal, toxic shock-like syndrome, yet the mechanisms regulating pathogenesis are not well understood. We define a central role for type I interferons (alpha interferon [IFN-α] and IFN-β) in severe disease in a mouse model of fatal ehrlichiosis caused by Ixodes ovatus Ehrlichia (IOE). IFN-α and IFN-β were induced by IOE infection but not in response to a less virulent strain, Ehrlichia muris. The major sources of type I IFNs during IOE infection were plasmacytoid dendritic cells and monocytes. Mice lacking the receptor for type I IFNs (Ifnar deficient) or neutralization of IFN-α and IFN-β resulted in a reduced bacterial burden. Ifnar-deficient mice exhibited significantly increased survival after IOE infection, relative to that of wild-type (WT) mice, that correlated with increased type II IFN (IFN-γ) production. Pathogen-specific antibody responses were also elevated in Ifnar-deficient mice, and this required IFN-γ. Remarkably, increased IFN-γ and IgM were not essential for protection in the absence of type I IFN signaling. The direct effect of type I IFNs on hematopoietic and nonhematopoietic cells was evaluated in bone marrow chimeric mice. We observed that chimeric mice containing Ifnar-deficient hematopoietic cells succumbed to infection early, whereas Ifnar-deficient mice containing WT hematopoietic cells exhibited increased survival, despite having a higher bacterial burden. These data demonstrate that IFN-α receptor signaling in nonhematopoietic cells is important for pathogenesis. Thus, type I IFNs are induced during a rickettsial infection in vivo and promote severe disease.
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23
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Tajima T, Wada M. Inhibitory effect of interferon gamma on frequency of Ehrlichia canis-infected cells in vitro. Vet Immunol Immunopathol 2013; 156:200-4. [PMID: 24148826 DOI: 10.1016/j.vetimm.2013.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 09/02/2013] [Accepted: 09/23/2013] [Indexed: 10/26/2022]
Abstract
Ehrlichia canis is an obligate intracellular bacterium that infects the macrophage-monocyte cells of dogs, causing canine monocytic ehrlichiosis. Interferon-γ (IFN-γ), along with other cytokines, mediates the immune response to such intracellular bacterial invasions. To determine the role of IFN-γ in the immunity of dogs to E. canis infection, peripheral blood mononuclear cells (PBMC) and white blood cells (WBC) were collected from E. canis-infected dogs and added to a culture of E. canis in DH82 cells. The number of E. canis inclusion-positive cells was significantly reduced in cultures containing PBMC and WBC from E. canis-infected dogs compared to uninfected dogs. However, this resistance was inhibited by the addition of an anti-dog IFN-γ antibody. Resistance was also observed when PBMC were added to the Cell Culture Inserts, which prohibited contact of PBMC to DH82 cells, while allowed the diffusion of soluble cell products. The results of this study indicate that resistance was not dependent on cell to cell contact, but was associated with soluble cell products, such as IFN-γ. The addition of recombinant canine IFN-γ to the E. canis culture also reduced the number of infected cells. A commercial recombinant canine IFN-γ, which is sold in Japan, was also effective at reducing E. canis-infected cell number. These results indicate that IFN-γ has an inhibitory effect on the frequency of E. canis-infected cells in vitro and that contact between effector and target cells is not necessary for the resistance.
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Affiliation(s)
- Tomoko Tajima
- Department of Veterinary Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-58 Rinku-orai-kita, Izumisano, Osaka 598-8531, Japan.
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24
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Thirumalapura NR, Crocquet-Valdes PA, Saito TB, Thomas S, McBride JW, Walker DH. Recombinant Ehrlichia P29 protein induces a protective immune response in a mouse model of ehrlichiosis. Vaccine 2013; 31:5960-7. [PMID: 24144475 DOI: 10.1016/j.vaccine.2013.10.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/19/2013] [Accepted: 10/08/2013] [Indexed: 01/26/2023]
Abstract
Ehrlichioses are emerging tick-borne bacterial diseases of humans and animals for which no vaccines are available. The diseases are caused by obligately intracellular bacteria belonging to the genus Ehrlichia. Several immunoreactive proteins of ehrlichiae have been identified based on their reactivity with immune sera from human patients and animals. These include the major outer membrane proteins, ankyrin repeat proteins and tandem repeat proteins (TRP). Polyclonal antibodies directed against the tandem repeats (TRs) of Ehrlichia chaffeensis TRP32, TRP47 and TRP120 have been shown to provide protection in mice. In the present study, we evaluated E. muris P29, which is the ortholog of E. chaffeensis TRP47 and E. canis TRP36, as a subunit vaccine in a mouse model of ehrlichiosis. Our study indicated that unlike E. chaffeensis TRP47 and E. canis TRP36, orthologs of E. muris (P29) and E. muris-like agent (EMLA) do not contain tandem repeats. Immunization of mice with recombinant E. muris P29 induced significant protection against a challenge infection. The protection induced by E. muris P29 was associated with induction of strong antibody responses. In contrast to development of P29-specific IgG antibodies following immunization, development of P29-specific IgG antibodies, but not IgM antibodies, was impaired during persistent E. muris infection. Furthermore, our study indicated that CD4+ T cells target P29 during E. muris infection and differentiate into IFN-γ-producing Th1 effector/memory cells. In conclusion, our study indicated that orthologs of E. muris P29 showed considerable variation in the central tandem repeat region among different species, induction of P29-specific IgG antibody response was impaired during persistent E. muris infection, and rP29 induced protective immune responses.
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MESH Headings
- Animals
- Antibodies, Bacterial/blood
- Bacterial Proteins/genetics
- Bacterial Proteins/immunology
- Bacterial Vaccines/administration & dosage
- Bacterial Vaccines/genetics
- Bacterial Vaccines/immunology
- CD4-Positive T-Lymphocytes/immunology
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- Disease Models, Animal
- Ehrlichia/genetics
- Ehrlichia/immunology
- Ehrlichiosis/immunology
- Ehrlichiosis/prevention & control
- Female
- Immunologic Memory
- Interferon-gamma/metabolism
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
- Sequence Analysis, DNA
- Vaccines, Subunit/administration & dosage
- Vaccines, Subunit/genetics
- Vaccines, Subunit/immunology
- Vaccines, Synthetic/administration & dosage
- Vaccines, Synthetic/genetics
- Vaccines, Synthetic/immunology
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Affiliation(s)
- Nagaraja R Thirumalapura
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, United States; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, United States; Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, United States; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, United States.
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25
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TLR2 and Nod2 mediate resistance or susceptibility to fatal intracellular Ehrlichia infection in murine models of ehrlichiosis. PLoS One 2013; 8:e58514. [PMID: 23526993 PMCID: PMC3602367 DOI: 10.1371/journal.pone.0058514] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 02/05/2013] [Indexed: 01/23/2023] Open
Abstract
Our murine models of human monocytic ehrlichiosis (HME) have shown that severe and fatal ehrlichiosis is due to generation of pathogenic T cell responses causing immunopathology and multi-organ failure. However, the early events in the liver, the main site of infection, are not well understood. In this study, we examined the liver transcriptome during the course of lethal and nonlethal infections caused by Ixodes ovatus Ehrlichia and Ehrlichia muris, respectively. On day 3 post-infection (p.i.), although most host genes were down regulated in the two groups of infected mice compared to naïve counterparts, lethal infection induced significantly higher expression of caspase 1, caspase 4, nucleotide binding oligomerization domain-containing proteins (Nod1), tumor necrosis factor-alpha, interleukin 10, and CCL7 compared to nonlethal infection. On day 7 p.i., lethal infection induced highly significant upregulation of type-1 interferon, several inflammatory cytokines and chemokines, which was associated with increased expression levels of Toll-like receptor-2 (TLR2), Nod2, MyD88, nuclear factor-kappa B (NF-kB), Caspase 4, NLRP1, NLRP12, Pycard, and IL-1β, suggesting enhanced TLR signals and inflammasomes activation. We next evaluated the participation of TLR2 and Nod2 in the host response during lethal Ehrlichia infection. Although lack of TLR2 impaired bacterial elimination and increased tissue necrosis, Nod2 deficiency attenuated pathology and enhanced bacterial clearance, which correlated with increased interferon-γ and interleukin-10 levels and a decreased frequency of pathogenic CD8(+) T cells in response to lethal infection. Thus, these data indicate that Nod2, but not TLR2, contributes to susceptibility to severe Ehrlichia-induced shock. Together, our studies provide, for the first time, insight into the diversity of host factors and novel molecular pathogenic mechanisms that may contribute to severe HME.
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26
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Paim FC, Da Silva AS, Paim CBV, França RT, Costa MM, Duarte MMMF, Sangoi MB, Moresco RN, Monteiro SG, Lopes STA. Increased cytokine and nitric oxide levels in serum of dogs experimentally infected with Rangelia vitalii. THE KOREAN JOURNAL OF PARASITOLOGY 2013; 51:133-7. [PMID: 23467990 PMCID: PMC3587743 DOI: 10.3347/kjp.2013.51.1.133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 10/01/2012] [Accepted: 10/04/2012] [Indexed: 11/23/2022]
Abstract
This study aimed to measure the levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), and nitrite/nitrate (NOx) in serum of dogs experimentally infected with Rangelia vitalii. Twelve female mongrel dogs were divided into 2 groups; group A (uninfected controls) composed by healthy dogs (n=5) and group B consisting of dogs inoculated with R. vitalii (n=7). Animals were monitored by blood smear examinations, which showed intraerythrocytic forms of the parasite on day 5 post-infection (PI). Blood samples were collected through the jugular vein on days 0, 10, and 20 PI to determine the serum levels of IFN-γ, TNF-α, IL-1, IL-6, and NOx. Cytokines were assessed by ELISA quantitative sandwich technique, and NOx was measured by the modified Griess method. Cytokine levels (IFN-γ, TNF-α, IL-1, and IL-6) were increased (P<0.01) in serum of infected animals. Serum levels of NOx were also increased on days 10 PI (P<0.01) and 20 PI (P<0.05) in infected animals. Therefore, the infection with R. vitalii causes an increase in proinflammatory cytokines and nitric oxide content. These alterations may be associated with host immune protection against the parasite.
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Affiliation(s)
- Francine C Paim
- Laboratory of Veterinary Clinical Analysis-LACVet, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
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27
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Evaluation of peripheral blood lymphocyte subsets in family-owned dogs naturally infected by Ehrlichia canis. Comp Immunol Microbiol Infect Dis 2012; 35:391-6. [DOI: 10.1016/j.cimid.2012.03.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 03/05/2012] [Accepted: 03/16/2012] [Indexed: 11/22/2022]
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Ismail N, Walker DH, Ghose P, Tang YW. Immune mediators of protective and pathogenic immune responses in patients with mild and fatal human monocytotropic ehrlichiosis. BMC Immunol 2012; 13:26. [PMID: 22607204 PMCID: PMC3517396 DOI: 10.1186/1471-2172-13-26] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 05/03/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ehrlichia chaffeensis is a bacterial pathogen that causes fatal human monocytic ehrlichiosis (HME) that mimic toxic shock-like syndrome. Murine studies indicate that over activation of cellular immunity followed by immune suppression plays a central role in mediating tissue injury and organ failure during fatal HME. However, there are no human studies that examine the correlates of resistance or susceptibility to severe and fatal HME. RESULTS In this study, we compared the immune responses in two patients with mild/non fatal and severe/fatal HME who had marked lymphopenia, thrombocytopenia and elevated liver enzymes. The levels of different immunological factors in the blood of those patients were examined and compared to healthy controls. Our data showed that fatal HME is associated with defective production of Th1 cytokines such as ( IFNγ and IL-2), increased anti-inflammatory (IL-10 and IL-13) and pro-inflammatory (TNF-α, IL-1α, IL-1β, and IL-6) cytokines, increased levels of macrophages, T cells, and NK cells chemokines such as MCP-1, MIP-1α, MIP-1β, but not RANTES and IP-10, increased levels of neutrophils chemokine and growth factor (IL-8 and G-CSF), and elevated expression of tumor necrosis factor receptor (TNFR), and toll like receptors 2 and 4 compared to patients with non fatal HME and healthy controls. CONCLUSIONS Fatal Ehrlichia-induced toxic shock is associated with defective Th1 responses, possible immune suppression mediated by IL-10. In addition, marked leukopenia observed in patients with fatal disease could be attributed to enhanced apoptosis of leukocytes and/or elevated chemokine production that could promote migration of immune cells to sites of infection causing tissue injury.
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Affiliation(s)
- Nahed Ismail
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA.
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Thomas S, Thirumalapura NR, Crocquet-Valdes PA, Luxon BA, Walker DH. Structure-based vaccines provide protection in a mouse model of ehrlichiosis. PLoS One 2011; 6:e27981. [PMID: 22114733 PMCID: PMC3219711 DOI: 10.1371/journal.pone.0027981] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 10/28/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Recent advances in bioinformatics have made it possible to predict the B cell and T cell epitopes of antigenic proteins. This has led to design of peptide based vaccines that are more specific, safe, and easy to produce. The obligately intracellular gram negative bacteria Ehrlichia cause ehrlichioses in humans and animals. As yet there are no vaccines to protect against Ehrlichia infection. METHODOLOGY/PRINCIPAL FINDINGS We applied the principle of structural vaccinology to design peptides to the epitopes of Ehrlichia muris outer membrane P28-19 (OMP-1/P28) and Ehrlichia Heat shock protein 60 (Hsp60/GroEL) antigenic proteins. Both P28-19 and Ehrlichia Hsp60 peptides reacted with polyclonal antibodies against E. canis and E. chaffeensis and could be used as a diagnostic tool for ehrlichiosis. In addition, we demonstrated that mice vaccinated with Ehrlichia P28-19 and Hsp60 peptides and later challenged with E. muris were protected against the pathogen. CONCLUSIONS/SIGNIFICANCE Our results demonstrate the power of structural vaccines and could be a new strategy in the development of vaccines to provide protection against pathogenic microorganisms.
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Affiliation(s)
- Sunil Thomas
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Nagaraja R. Thirumalapura
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | | | - Bruce A. Luxon
- Institute of Human Infections and Immunity, Institute for Translational Science, Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David H. Walker
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, United States of America
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Immunization with Ehrlichia P28 outer membrane proteins confers protection in a mouse model of ehrlichiosis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:2018-25. [PMID: 22030371 DOI: 10.1128/cvi.05292-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The obligately intracellular bacterium Ehrlichia chaffeensis that resides in mononuclear phagocytes is the etiologic agent of human monocytotropic ehrlichiosis (HME). HME is an emerging and often life-threatening, tick-transmitted infectious disease in the United States. Effective primary immune responses against Ehrlichia infection involve generation of Ehrlichia-specific gamma interferon (IFN-γ)-producing CD4(+) T cells and cytotoxic CD8(+) T cells, activation of macrophages by IFN-γ, and production of Ehrlichia-specific antibodies of the Th1 isotype. Currently, there are no vaccines available against HME. We evaluated the ability of 28-kDa outer membrane proteins (P28-OMP-1) of the closely related Ehrlichia muris to stimulate long-term protective memory T and B cell responses and confer protection in mice. The spleens of mice vaccinated with E. muris P28-9, P28-12, P28-19, or a mixture of these three P28 proteins (P28s) using a DNA prime-protein boost regimen and challenged with E. muris had significantly lower bacterial loads than the spleens of mock-vaccinated mice. Mice immunized with P28-9, P28-12, P28-19, or the mixture induced Ehrlichia-specific CD4(+) Th1 cells. Interestingly, mice immunized with P28-14, orthologs of which in E. chaffeensis and E. canis are primarily expressed in tick cells, failed to lower the ehrlichial burden in the spleen. Immunization with the recombinant P28-19 protein alone also significantly decreased the bacterial load in the spleen and liver compared to those of the controls. Our study reports, for the first time, the protective roles of the Ehrlichia P28-9 and P28-12 proteins in addition to confirming previous reports of the protective ability of P28-19. Partial protection induced by immunization with P28-9, P28-12, and P28-19 against Ehrlichia was associated with the generation of Ehrlichia-specific cell-mediated and humoral immune responses.
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Ghose P, Ali AQ, Fang R, Forbes D, Ballard B, Ismail N. The interaction between IL-18 and IL-18 receptor limits the magnitude of protective immunity and enhances pathogenic responses following infection with intracellular bacteria. THE JOURNAL OF IMMUNOLOGY 2011; 187:1333-46. [PMID: 21715688 DOI: 10.4049/jimmunol.1100092] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The binding of IL-18 to IL-18Rα induces both proinflammatory and protective functions during infection, depending on the context in which it occurs. IL-18 is highly expressed in the liver of wild-type (WT) C57BL/6 mice following lethal infection with highly virulent Ixodes ovatus ehrlichia (IOE), an obligate intracellular bacterium that causes acute fatal toxic shock-like syndrome. In this study, we found that IOE infection of IL-18Rα(-/-) mice resulted in significantly less host cell apoptosis, decreased hepatic leukocyte recruitment, enhanced bacterial clearance, and prolonged survival compared with infected WT mice, suggesting a pathogenic role for IL-18/IL-18Rα in Ehrlichia-induced toxic shock. Although lack of IL-18R decreased the magnitude of IFN-γ producing type-1 immune response, enhanced resistance of IL-18Rα(-/-) mice against Ehrlichia correlated with increased proinflammatory cytokines at sites of infection, decreased systemic IL-10 production, increased frequency of protective NKT cells producing TNF-α and IFN-γ, and decreased frequency of pathogenic TNF-α-producing CD8(+) T cells. Adoptive transfer of immune WT CD8(+) T cells increased bacterial burden in IL-18Rα(-/-) mice following IOE infection. Furthermore, rIL-18 treatment of WT mice infected with mildly virulent Ehrlichia muris impaired bacterial clearance and enhanced liver injury. Finally, lack of IL-18R signal reduced dendritic cell maturation and their TNF-α production, suggesting that IL-18 might promote the adaptive pathogenic immune responses against Ehrlichia by influencing T cell priming functions of dendritic cells. Together, these results suggested that the presence or absence of IL-18R signals governs the pathogenic versus protective immunity in a model of Ehrlichia-induced immunopathology.
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Affiliation(s)
- Purnima Ghose
- Department of Pathology, Meharry Medical College, Nashville, TN 37028, USA
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McBride JW, Walker DH. Progress and obstacles in vaccine development for the ehrlichioses. Expert Rev Vaccines 2010; 9:1071-82. [PMID: 20822349 DOI: 10.1586/erv.10.93] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Ehrlichia are tick-borne obligately intracellular bacteria that cause significant diseases in veterinary natural hosts, including livestock and companion animals, and are now considered important zoonotic pathogens in humans. Vaccines are needed for these veterinary and zoonotic human pathogens, but many obstacles exist that have impeded their development. These obstacles include understanding genetic and antigenic variability, influence of the host on the pathogen phenotype and immunogenicity, identification of the ehrlichial antigens that stimulate protective immunity and those that elicit immunopathology, development of animal models that faithfully reflect the immune responses of the hosts and understanding molecular host-pathogen interactions involved in immune evasion or that may be blocked by the host immune response. We review the obstacles and progress in addressing barriers associated with vaccine development to protect livestock, companion animals and humans against these host defense-evasive and cell function-manipulative, vector-transmitted pathogens.
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Affiliation(s)
- Jere W McBride
- Department of Pathology, Center for Emerging Infectious Diseases and Biodefense, Sealy Center for Vaccine Development, and the Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
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Abstract
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne diseases caused by various members of the genera Ehrlichia and Anaplasma (Anaplasmataceae). Human monocytotropic ehrlichiosis has become one of the most prevalent life-threatening tick-borne disease in the United States. Ehrlichiosis and anaplasmosis are becoming more frequently diagnosed as the cause of human infections, as animal reservoirs and tick vectors have increased in number and humans have inhabited areas where reservoir and tick populations are high. Ehrlichia chaffeensis, the etiologic agent of human monocytotropic ehrlichiosis (HME), is an emerging zoonosis that causes clinical manifestations ranging from a mild febrile illness to a fulminant disease characterized by multiorgan system failure. Anaplasma phagocytophilum causes human granulocytotropic anaplasmosis (HGA), previously known as human granulocytotropic ehrlichiosis. This article reviews recent advances in the understanding of ehrlichial diseases related to microbiology, epidemiology, diagnosis, pathogenesis, immunity, and treatment of the 2 prevalent tick-borne diseases found in the United States, HME and HGA.
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Koh YS, Koo JE, Biswas A, Kobayashi KS. MyD88-dependent signaling contributes to host defense against ehrlichial infection. PLoS One 2010; 5:e11758. [PMID: 20668698 PMCID: PMC2909256 DOI: 10.1371/journal.pone.0011758] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 07/01/2010] [Indexed: 01/01/2023] Open
Abstract
The ehrlichiae are small Gram-negative obligate intracellular bacteria in the family Anaplasmataceae. Ehrlichial infection in an accidental host may result in fatal diseases such as human monocytotropic ehrlichiosis, an emerging, tick-borne disease. Although the role of adaptive immune responses in the protection against ehrlichiosis has been well studied, the mechanism by which the innate immune system is activated is not fully understood. Using Ehrlichia muris as a model organism, we show here that MyD88-dependent signaling pathways play a pivotal role in the host defense against ehrlichial infection. Upon E. muris infection, MyD88-deficient mice had significantly impaired clearance of E. muris, as well as decreased inflammation, characterized by reduced splenomegaly and recruitment of macrophages and neutrophils. Furthermore, MyD88-deficient mice produced markedly lower levels of IL-12, which correlated well with an impaired Th1 immune response. In vitro, dendritic cells, but not macrophages, efficiently produced IL-12 upon E. muris infection through a MyD88-dependent mechanism. Therefore, MyD88-dependent signaling is required for controlling ehrlichial infection by playing an essential role in the immediate activation of the innate immune system and inflammatory cytokine production, as well as in the activation of the adaptive immune system at a later stage by providing for optimal Th1 immune responses.
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Affiliation(s)
- Young-Sang Koh
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Microbiology and Brain Korea 21 Program, Jeju National University School of Medicine, Jeju, Jeju-Do, South Korea
| | - Jung-Eun Koo
- Department of Microbiology and Brain Korea 21 Program, Jeju National University School of Medicine, Jeju, Jeju-Do, South Korea
| | - Amlan Biswas
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Koichi S. Kobayashi
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Stevenson HL, Estes MD, Thirumalapura NR, Walker DH, Ismail N. Natural killer cells promote tissue injury and systemic inflammatory responses during fatal Ehrlichia-induced toxic shock-like syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:766-76. [PMID: 20616341 DOI: 10.2353/ajpath.2010.091110] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Human monocytotropic ehrlichiosis is caused by Ehrlichia chaffeensis, a Gram-negative bacterium lacking lipopolysaccharide. We have shown that fatal murine ehrlichiosis is associated with CD8(+)T cell-mediated tissue damage, tumor necrosis factor-alpha, and interleukin (IL)-10 overproduction, and CD4(+)Th1 hyporesponsiveness. In this study, we examined the relative contributions of natural killer (NK) and NKT cells in Ehrlichia-induced toxic shock. Lethal ehrlichial infection in wild-type mice induced a decline in NKT cell numbers, and late expansion and migration of activated NK cells to the liver, a main infection site that coincided with development of hepatic injury. The spatial and temporal changes in NK and NKT cells in lethally infected mice correlated with higher NK cell cytotoxic activity, higher expression of cytotoxic molecules such as granzyme B, higher production of interferon-gamma and tumor necrosis factor-alpha, increased hepatic infiltration with CD8alphaCD11c(+) dendritic cells and CD8(+)T cells, decreased splenic CD4(+)T cells, increased serum concentrations of IL-12p40, IL-18, RANTES, and monocyte chemotactic protein-1, and elevated production of IL-18 by liver mononuclear cells compared with nonlethally infected mice. Depletion of NK cells prevented development of severe liver injury, decreased serum levels of interferon-gamma, tumor necrosis factor-alpha, and IL-10, and enhanced bacterial elimination. These data indicate that NK cells promote immunopathology and defective anti-ehrlichial immunity, possibly via decreasing the protective immune response mediated by interferon-gamma producing CD4(+)Th1 and NKT cells.
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Affiliation(s)
- Heather L Stevenson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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Persistent infection contributes to heterologous protective immunity against fatal ehrlichiosis. Infect Immun 2009; 77:5682-9. [PMID: 19805532 DOI: 10.1128/iai.00720-09] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Human monocytotropic ehrlichiosis (HME), an emerging and often life-threatening tick-transmitted disease, is caused by the obligately intracellular bacterium Ehrlichia chaffeensis. HME is modeled in C57BL/6 mice using Ehrlichia muris, which causes persistent infection, and Ixodes ovatus Ehrlichia (IOE), which is either acutely lethal or sublethal depending on the dose and route of inoculation. A persistent primary E. muris infection, but not a sublethal IOE infection, protects mice against an ordinarily lethal secondary IOE challenge. In the present study, we determined the role of persistent infection in maintenance of protective memory immune responses. E. muris-infected mice were treated with doxycycline or left untreated and then challenged with an ordinarily lethal dose of IOE. Compared to E. muris-primed mice treated with doxycycline, untreated mice persistently infected with E. muris had significantly greater numbers of antigen-specific gamma interferon-producing splenic memory T cells, significant expansion of CD4(+) CD25(+) T regulatory cells, and production of transforming growth factor beta1 in the spleen. Importantly, E. muris-primed mice treated with doxycycline showed significantly greater susceptibility to challenge infection with IOE compared to untreated mice persistently infected with E. muris. The study indicated that persistent ehrlichial infection contributes to heterologous protection by stimulating the maintenance of memory T-cell responses.
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Munderloh UG, Silverman DJ, MacNamara KC, Ahlstrand GG, Chatterjee M, Winslow GM. Ixodes ovatus Ehrlichia exhibits unique ultrastructural characteristics in mammalian endothelial and tick-derived cells. Ann N Y Acad Sci 2009; 1166:112-9. [PMID: 19538270 DOI: 10.1111/j.1749-6632.2009.04520.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Tick-borne pathogens in the genus Ehrlichia cause emerging zoonoses. Although laboratory mice are susceptible to Ehrlichia infections, many isolates do not cause clinical illness. In contrast, the Ixodes ovatus Ehrlichia-like agent (IOE) causes disease and immune responses in mice comparable to the human illness caused by Ehrlichia chaffeensis. No culture system had been developed for IOE, however, which limited studies of this pathogen. We reasoned that endothelial and tick cell lines could potentially serve as host cells, since the IOE is found in ticks and in endothelial cells in mice. Infected spleen cells from RAG-deficient mice were overlaid onto ISE6 and RF/6A cultures, and colonies typical of Ehrlichia were noted in RF/6A cells within 2 weeks. Infection of ISE6 cells was established after transfer of IOE from RF/6A cells. Electron microscopy revealed densely packed inclusions in infected RF/6A and ISE6 cells; these inclusions contained copious amounts of filamentous structures, apparently originating from Ehrlichial cells. In particular, within RF/6A cells the structures assumed an ordered morphology of finely combed hair. IOE from RF/6A cells, when inoculated into C57BL/6 and RAG-deficient mice, induced fatal disease. These data reveal unique structural features of IOE that may contribute to the pathogen's high virulence.
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Affiliation(s)
- Ulrike G Munderloh
- Department of Entomology, University of Minnesota, St. Paul, Minnesota 55108, USA
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Birkner K, Steiner B, Rinkler C, Kern Y, Aichele P, Bogdan C, von Loewenich FD. The elimination of Anaplasma phagocytophilum requires CD4+ T cells, but is independent of Th1 cytokines and a wide spectrum of effector mechanisms. Eur J Immunol 2009; 38:3395-410. [PMID: 19039769 DOI: 10.1002/eji.200838615] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Anaplasma phagocytophilum is a Gram-negative, obligate intracellular bacterium that exhibits a striking tropism for neutrophils. When we depleted mice of neutrophils, we found that murine susceptibility to anaplasmal infection was dependent on their presence. While serving as sites of bacterial replication, neutrophils do not seem to act as efficient killer cells in A. phagocytophilum infection, because mice deficient for antimicrobial effectors of neutrophils such as myeloperoxidase, granulocyte elastase, and cathepsin G were fully competent in pathogen elimination. To identify components of the immune system other than neutrophils that control A. phagocytophilum, we studied the course of infection in several gene-deficient mouse strains. IFN-gamma production by NK cells was important for initial defense, but not critical for pathogen elimination. In contrast, bacterial clearance was strictly dependent on CD4(+) T cells, but unexpectedly achieved in the absence of perforin, Fas/FasL and major Th1 cytokines such as IL-12, IFN-gamma, and MCP-1. These findings provide a novel paradigm for the control of an intracellular pathogen, which appears to be strikingly different from the CD4(+) T cell-, IL-12-, and IFN-gamma-dependent immunity to other intracellular bacteria.
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Affiliation(s)
- Katharina Birkner
- Department of Medical Microbiology and Hygiene, Institute of Medical Microbiology and Hygiene, University of Freiburg, Freiburg, Germany
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Chapes SK, Ganta RR. Defining the immune response to Ehrlichia species using murine models. Vet Parasitol 2008; 158:344-59. [PMID: 19028013 DOI: 10.1016/j.vetpar.2008.09.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 09/06/2008] [Accepted: 09/09/2008] [Indexed: 01/01/2023]
Abstract
Pathogenic bacteria belonging to the family Anaplasmataceae include species of the genera Ehrlichia and Anaplasma. Ehrlichia chaffeensis, first known as the causative agent of human monocytic ehrlichiosis, also infects several vertebrate hosts including white-tailed deer, dogs, coyotes and goats. E. chaffeensis is transmitted from the bite of an infected hard tick, such as Amblyomma americanum. E. chaffeensis and other tick-transmitted pathogens have adapted to both the tick and vertebrate host cell environments. Although E. chaffeensis persists in both vertebrate and tick hosts for long periods of time, little is known about that process. Immunological studies will be valuable in assessing how the pathogen persists in nature in both vertebrate and invertebrate hosts. Understanding the host immune response to the pathogen originating from dual host backgrounds is also important to develop effective methods of diagnosis, control and treatment. In this paper, we provide our perspective of the current understanding of the immune response against E. chaffeensis in relation to other related Anaplasmataceae pathogens.
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Affiliation(s)
- Stephen K Chapes
- Division of Biology, College of Arts and Sciences, Kansas State University, Manhattan, KS 66506, USA
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Racine R, Chatterjee M, Winslow GM. CD11c expression identifies a population of extrafollicular antigen-specific splenic plasmablasts responsible for CD4 T-independent antibody responses during intracellular bacterial infection. THE JOURNAL OF IMMUNOLOGY 2008; 181:1375-85. [PMID: 18606692 DOI: 10.4049/jimmunol.181.2.1375] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Although T-independent immunity is known to be generated against bacterial capsular and cell wall polysaccharides expressed by a number of bacterial pathogens, it has not been studied in depth during intracellular bacterial infections. Our previous study demonstrated that Ehrlichia muris, an obligate intracellular tick-borne pathogen, generates protective classical TI responses in CD4 T cell-deficient C57BL/6 mice. We found that E. muris T-independent immunity is accompanied by the expansion of a very large extrafollicular spleen population of CD11c(low)-expressing plasmablasts that exhibit characteristics of both B-1 and marginal zone B cells. The plasmablasts comprised up to 15% of the total spleen lymphocytes and approximately 70% of total spleen IgM(high)IgD(low) cells during peak infection in both wild-type and MHC class II-deficient mice. The CD11c(low) cells exhibited low surface expression of B220, CD19, and CD1d, high expression of CD11b, CD43, but did not express CD5. Approximately 50% of the CD11c(low) cells also expressed CD138. In addition to CD11b and CD11c, the plasmablasts expressed the beta(1) (CD29) and alpha4 (CD49d) integrins, as well as the chemokine receptor CXCR4, molecules which may play roles in localizing the B cells extrafollicular region of the spleen. During peak infection, the CD11c(low) cells accounted for the majority of the IgM-producing splenic B cells and nearly all of the E. muris outer membrane protein-specific IgM-secreting cells. Thus, during this intracellular bacterial infection, CD11c expression identifies a population of Ag-specific spleen plasmablasts responsible for T-independent Ab production.
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Affiliation(s)
- Rachael Racine
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
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Proteomic analysis of and immune responses to Ehrlichia chaffeensis lipoproteins. Infect Immun 2008; 76:3405-14. [PMID: 18490460 DOI: 10.1128/iai.00056-08] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ehrlichia chaffeensis is an obligately intracellular gram-negative bacterium and is the etiologic agent of human monocytic ehrlichiosis (HME). Although E. chaffeensis induces the generation of several cytokines and chemokines by leukocytes, E. chaffeensis lacks lipopolysaccharide and peptidoglycan. Bioinfomatic analysis of the E. chaffeensis genome, however, predicted genes encoding 15 lipoproteins and 3 posttranslational lipoprotein-processing enzymes. The present study showed that by use of multidimensional liquid chromatography followed by tandem mass spectrometry, all predicted lipoproteins as well as lipoprotein-processing enzymes were expressed by E. chaffeensis cultured in the human promyelocytic leukemia cell line HL-60. Consistent with this observation, a signal peptidase II inhibitor, globomycin, was found to inhibit E. chaffeensis infection and lipoprotein processing in HL-60 cell culture. To study in vivo E. chaffeensis lipoprotein expression and host immune responses to E. chaffeensis lipoproteins, 13 E. chaffeensis lipoprotein genes were cloned into a mammalian expression vector. When the DNA constructs were inoculated into naïve dogs, or when dogs were infected with E. chaffeensis, the animals developed delayed-type hypersensitivity reactions at cutaneous sites of the DNA construct deposition and serum antibodies to these lipoproteins. This is the first demonstration of lipoprotein expression and elicitation of immune responses by a member of the order Rickettsiales. Multiple lipoproteins expressed by E. chaffeensis in vitro and in vivo may play key roles in pathogenesis and immune responses in HME.
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Protective heterologous immunity against fatal ehrlichiosis and lack of protection following homologous challenge. Infect Immun 2008; 76:1920-30. [PMID: 18285501 DOI: 10.1128/iai.01293-07] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The roles of antibodies and memory T cells in protection against virulent Ehrlichia have not been completely investigated. In this study, we addressed these issues by using murine models of mild and fatal ehrlichiosis caused by related monocytotropic Ehrlichia strains. Mice were primed with either Ehrlichia muris or closely related virulent ehrlichiae transmitted by Ixodes ovatus (IOE) ticks given intraperitoneally or intradermally. All groups were reinfected intraperitoneally, 30 days later, with a lethal high dose of IOE. Priming with E. muris, but not IOE, induced strong CD4+ and CD8+ memory type 1 T-cell responses, Ehrlichia-specific immunoglobulin G (IgG) antibodies, and persistent infection. Compared to IOE-primed mice, subsequent lethal IOE challenge of E. muris-primed mice, resulted in (i) 100% protection against lethal infection, (ii) strong Ehrlichia-specific secondary gamma interferon (IFN-gamma)-producing effector/effector memory CD4+ and CD8+ T-cell responses, (iii) enhanced secondary anti-ehrlichial antibody response, (iv) accelerated bacterial clearance, and (v) the formation of granulomas in the liver and lung. E. muris-primed mice challenged with IOE had lower levels of serum interleukin-1alpha (IL-1alpha), IL-6, and IL-10 compared to unprimed mice challenged with IOE. Interestingly, the fatal secondary response in IOE-primed mice correlated with (i) decline in the Ehrlichia-specific CD4+ and CD8+ type 1 responses, (ii) marked hepatic apoptosis and necrosis, and (iii) substantial bacterial clearance, suggesting that fatal secondary response is due to immune-mediated tissue damage. In conclusion, protection against fatal ehrlichial infection correlates with strong expansion of IFN-gamma-producing CD4+ and CD8+ effector memory type 1 T cells, which appear to be maintained in the presence of IgG antibodies and persistent infection.
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Regulatory roles of CD1d-restricted NKT cells in the induction of toxic shock-like syndrome in an animal model of fatal ehrlichiosis. Infect Immun 2008; 76:1434-44. [PMID: 18212072 DOI: 10.1128/iai.01242-07] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD1d-restricted NKT cells are key players in host defense against various microbial infections. Using a murine model of fatal ehrlichiosis, we investigated the role of CD1d-restricted NKT cells in induction of toxic shock-like syndrome caused by gram-negative, lipopolysaccharide-lacking, monocytotropic Ehrlichia. Our previous studies showed that intraperitoneal infection of wild-type (WT) mice with virulent Ehrlichia (Ixodes ovatus Ehrlichia [IOE]) results in CD8+ T-cell-mediated fatal toxic shock-like syndrome marked by apoptosis of CD4+ T cells, a weak CD4+ Th1 response, overproduction of tumor necrosis factor alpha and interleukin-10, and severe liver injury. Although CD1d-/- mice succumbed to high-dose IOE infection similar to WT mice, they did not develop signs of toxic shock, as shown by elevated bacterial burdens, low serum levels of tumor necrosis factor, normal serum levels of liver enzymes, and the presence of few apoptotic hepatic cells. An absence of NKT cells restored the percentages and absolute numbers of CD4+ and CD8+ T cells and CD11b+ cells in the spleen compared to WT mice and was also associated with decreased expression of Fas on splenic CD4+ lymphocytes and granzyme B in hepatic CD8+ lymphocytes. Furthermore, our data show that NKT cells promote apoptosis of macrophages and up-regulation of the costimulatory molecule CD40 on antigen-presenting cells, including dendritic cells, B cells, and macrophages, which may contribute to the induction of pathogenic T-cell responses. In conclusion, our data suggest that NKT cells mediate Ehrlichia-induced T-cell-mediated toxic shock-like syndrome, most likely via cognate and noncognate interactions with antigen-presenting cells.
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Nandi B, Hogle K, Vitko N, Winslow GM. CD4 T-cell epitopes associated with protective immunity induced following vaccination of mice with an ehrlichial variable outer membrane protein. Infect Immun 2007; 75:5453-9. [PMID: 17698576 PMCID: PMC2168300 DOI: 10.1128/iai.00713-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The ehrlichiae express variable outer membrane proteins (OMPs) that play important roles in both pathogenesis and host defense. Previous studies revealed that OMPs are immunodominant B-cell antigens and that passive transfer of anti-OMP antibodies can protect SCID mice from fatal ehrlichial infection. In this study, we used a model of fatal monocytotropic ehrlichiosis caused by Ehrlichia bacteria from Ixodes ovatus (IOE) to determine whether OMP immunization could generate protective immunity in immunocompetent mice. Immunization of C57BL/6 mice with a purified recombinant OMP expressed by IOE omp19 generated protection from fatal IOE infection and elicited robust humoral and CD4 T-cell responses. To identify CD4 T-cell epitopes within OMPs, we performed enzyme-linked immunospot analyses for gamma interferon (IFN-gamma) production using a panel of overlapping 16-mer peptides from IOE OMP-19. Five immunoreactive peptides comprising residues 30 to 45, 77 to 92, 107 to 122, 197 to 212, and 247 to 264 were identified; the strongest response was generated against OMP-19(107-122). Most of the peptides are conserved between E. muris and E. chaffeensis OMP-19, and they elicited IFN-gamma production in CD4 T cells from E. muris-infected mice, indicating that T-cell epitope cross-reactivity likely contributes to heterologous immunity. Accordingly, CD4 T-cell responses to both OMP-19 and OMP-19(107-122) were of greater magnitude following high-dose IOE challenge of mice that had been immunized by prior infection with E. muris. Our studies cumulatively identify B- and T-cell epitopes that are associated with protective homologous and heterologous immunity during ehrlichial infection.
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Affiliation(s)
- Bisweswar Nandi
- Wadsworth Center, 120 New Scotland Avenue, Albany, NY 12208, USA
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Bitsaktsis C, Nandi B, Racine R, MacNamara KC, Winslow G. T-Cell-independent humoral immunity is sufficient for protection against fatal intracellular ehrlichia infection. Infect Immun 2007; 75:4933-41. [PMID: 17664264 PMCID: PMC2044530 DOI: 10.1128/iai.00705-07] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Although humoral immunity has been shown to contribute to host defense during intracellular bacterial infections, its role has generally been ancillary. Instead, CD4 T cells are often considered to play the dominant role in protective immunity via their production of type I cytokines. Our studies of highly pathogenic Ehrlichia bacteria isolated from Ixodes ovatus (IOE) reveal, however, that this paradigm is not always correct. Immunity to IOE infection can be induced by infection with a closely related weakly pathogenic ehrlichia, Ehrlichia muris. Type I cytokines (i.e., gamma interferon, tumor necrosis factor alpha, and interleukin-12) were not necessary for E. muris-induced immunity. In contrast, humoral immunity was essential, as shown by the fact that E. muris-infected B-cell-deficient mice were not protected from IOE challenge and because E. muris immunization was effective in CD4-, CD8-, and major histocompatibility complex (MHC) class II-deficient mice. Immunity was unlikely due to nonspecific inflammation, as prior infection with Listeria monocytogenes did not induce immunity to IOE. Antisera from both wild-type and MHC-II-deficient mice provided at least partial resistance to challenge infection, and protection could also be achieved following transfer of total, but not B-cell-depleted, splenocytes obtained from E. muris-immunized mice. The titers of class-switched antibodies in immunized CD4 T-cell- and MHC class II-deficient mice, although lower than those observed in immunized wild-type mice, were significant, indicating that E. muris can induce class switch recombination in the absence of classical T-cell-mediated help. These studies highlight a major protective role for classical T-cell-independent humoral immunity during an intracellular bacterial infection.
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Affiliation(s)
- Constantine Bitsaktsis
- Wadsworth Center, New York State Department of Health, PO Box 22002, Albany, New York 12201-2002, USA
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Ismail N, Crossley EC, Stevenson HL, Walker DH. Relative importance of T-cell subsets in monocytotropic ehrlichiosis: a novel effector mechanism involved in Ehrlichia-induced immunopathology in murine ehrlichiosis. Infect Immun 2007; 75:4608-20. [PMID: 17562770 PMCID: PMC1951155 DOI: 10.1128/iai.00198-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Infection with gram-negative monocytotropic Ehrlichia strains results in a fatal toxic shock-like syndrome characterized by a decreased number of Ehrlichia-specific CD4(+) Th1 cells, the expansion of tumor necrosis factor alpha (TNF-alpha)-producing CD8(+) T cells, and the systemic overproduction of interleukin-10 (IL-10) and TNF-alpha. Here, we investigated the role of CD4(+) and CD8(+) T cells in immunity to Ehrlichia and the pathogenesis of fatal ehrlichiosis caused by infection with low- and high-dose (10(3) and 10(5) bacterial genomes/mouse, respectively) ehrlichial inocula. The CD4(+) T-cell-deficient mice showed exacerbated susceptibility to a lethal high- or low-dose infection and harbored higher bacterial numbers than did wild-type (WT) mice. Interestingly, the CD8(+) T-cell-deficient mice were resistant to a low dose but succumbed to a high dose of Ehrlichia. The absence of CD8(+) T cells abrogated TNF-alpha and IL-10 production, reduced tissue injury and bacterial burden, restored splenic CD4(+) T-cell numbers, and increased the frequency of Ehrlichia-specific CD4(+) Th1 cells in comparison to infected WT mice. Although fatal disease is perforin independent, our data suggested that perforin played a critical role in controlling bacterial burden and mediating liver injury. Similar to WT mice, mortality of infected perforin-deficient mice was associated with CD4(+) T-cell apoptosis and a high serum concentration of IL-10. Depletion of IL-10 restored the number of CD4(+) and CD8(+) T cells in infected WT mice. Our data demonstrate a novel mechanism of immunopathology in which CD8(+) T cells mediate Ehrlichia-induced toxic shock, which is associated with IL-10 overproduction and CD4(+) T-cell apoptosis.
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Affiliation(s)
- Nahed Ismail
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, 301 University Blvd., Galveston, TX 77555-0609, USA.
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Ganta RR, Cheng C, Miller EC, McGuire BL, Peddireddi L, Sirigireddy KR, Chapes SK. Differential clearance and immune responses to tick cell-derived versus macrophage culture-derived Ehrlichia chaffeensis in mice. Infect Immun 2007; 75:135-45. [PMID: 17060466 PMCID: PMC1828415 DOI: 10.1128/iai.01127-06] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 08/16/2006] [Accepted: 10/02/2006] [Indexed: 11/20/2022] Open
Abstract
Human monocytic ehrlichiosis is caused by a tick-transmitted rickettsia, Ehrlichia chaffeensis. We recently reported that E. chaffeensis grown in tick cells expresses different proteins than bacteria grown in macrophages. Therefore, we tested the hypothesis that immune responses against E. chaffeensis would be different if the mice are challenged with bacteria grown in macrophages or tick cells. We assessed the E. chaffeensis clearance from the peritoneum, spleen, and liver by C57BL/6J mice using a TaqMan-based real-time reverse transcription-PCR assay. Macrophage-grown E. chaffeensis was cleared in 2 weeks from the peritoneum, whereas the pathogen from tick cells persisted for nine additional days and included three relapses of increasing bacterial load separated by three-day intervals. Tick cell-grown bacteria also persisted in the livers and spleens with higher bacterial loads compared to macrophage-grown bacteria and fluctuated over a period of 35 days. Three-day periodic cycles were detected in T-cell CD62L/CD44 ratios in the spleen and bone marrow in response to infections with both tick cell- and macrophage-grown bacteria and were accompanied by similar periodic cycles of spleen cell cytokine secretions and nitric oxide and interleukin-6 by peritoneal macrophages. The E. chaffeensis-specific immunoglobulin G response was considerably higher and steadily increased in mice infected with the tick cell-derived E. chaffeensis compared to DH82-grown bacteria. In addition, antigens detected by the immunoglobulins were significantly different between mice infected with the E. chaffeensis originating from tick cells or macrophages. The differences in the immune response to tick cell-grown bacteria compared to macrophage-grown bacteria reflected a delay in the shift of gene expression from the tick cell-specific Omp 14 gene to the macrophage-specific Omp 19 gene. These data suggest that the host response to E. chaffeensis depends on the source of the bacteria and that this experimental model requires the most natural inoculum possible to allow for a realistic understanding of host resistance.
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Affiliation(s)
- Roman R Ganta
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Ave., Manhattan, KS 66506, USA.
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Bitsaktsis C, Winslow G. Fatal recall responses mediated by CD8 T cells during intracellular bacterial challenge infection. THE JOURNAL OF IMMUNOLOGY 2006; 177:4644-51. [PMID: 16982903 DOI: 10.4049/jimmunol.177.7.4644] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The roles(s) of CD8 T cells during infections by intracellular bacteria that reside in host cell endocytic compartments are not well understood. Our previous studies in a mouse model of human monocytotropic ehrlichiosis indicated that CD8 T cells are not essential for immunity. However, we have observed an unexpected role for these cells during challenge infection. Although immunocompetent mice cleared a primary low-dose (nonfatal) Ixodes ovatus ehrlichia infection, a secondary low-dose challenge infection resulted in fatal disease and loss of control of infection. The outcome was CD8-dependent, because CD8-deficient mice survived secondary low-dose challenge infection. Moreover, effector and/or memory phenotype CD8 T cells were responsible, because adoptive transfer of purified CD44(high) CD8 T cells to naive mice induced fatal responses following a primary low-dose infection. The fatal responses were perforin- and Fas ligand-independent, and were associated with high serum concentrations of TNF-alpha and CCL2, and low levels of IL-10. Accordingly, blockade of either TNF-alpha or CCL2 ameliorated fatal recall responses, and in vitro coculture of memory CD8 T cells and Ixodes ovatus ehrlichia-infected peritoneal exudate cells resulted in substantial increases in TNF-alpha and CCL2. Thus, during monocytotropic ehrlichiosis, inflammatory cytokine production, by CD8 T cells and/or other host cells, can trigger chemokine-dependent disease. These findings highlight a novel role for CD8 T cells, and reveal that live vaccines for intracellular bacteria can, under some conditions, induce undesirable consequences.
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Affiliation(s)
- Constantine Bitsaktsis
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12201, USA
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Stevenson HL, Jordan JM, Peerwani Z, Wang HQ, Walker DH, Ismail N. An intradermal environment promotes a protective type-1 response against lethal systemic monocytotropic ehrlichial infection. Infect Immun 2006; 74:4856-64. [PMID: 16861674 PMCID: PMC1539596 DOI: 10.1128/iai.00246-06] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Immune responses against monocytotropic ehrlichiosis during infection with a strain of Ehrlichia from Ixodes ovatus (IOE) were evaluated using a model that closely reproduces the pathology and immunity associated with tick-transmitted human monocytotropic ehrlichiosis. C57BL/6 mice were inoculated intradermally or intraperitoneally with high-dose highly virulent IOE or intraperitoneally with mildly virulent Ehrlichia muris. Intradermal (i.d.) infection with IOE established mild, self-limited disease associated with minimal hepatic apoptosis, and all mice survived past 30 days. Intraperitoneal (i.p.) infection with IOE resulted in acute, severe toxic shock-like syndrome and severe multifocal hepatic apoptosis and necrosis, and all mice succumbed to disease. Compared to i.p. infection with IOE, intradermally infected mice had a 100- to 1,000-fold lower bacterial load in the spleen with limited dissemination. Compared to mice infected intraperitoneally with IOE, i.d. infection stimulated a stronger protective type-1 cell-mediated response on day 7 of infection, characterized by increased percentages of both CD4+ and CD8+ splenic T cells, generation of a greater number of IOE-specific, gamma interferon-producing CD4+ Th1 cells, and higher levels of tumor necrosis factor (TNF-alpha) in the spleen but lower concentrations of serum TNF-alpha and interleukin-10. These data suggest that under the conditions of natural route of challenge (i.e., i.d. inoculation), the immune response has the capacity to confer complete protection against monocytotropic ehrlichiosis, which is associated with a strong cell-mediated type-1 response and decreased systemic production of pro- and anti-inflammatory cytokines.
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Affiliation(s)
- Heather L Stevenson
- Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-0609, USA
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Winslow GM, Bitsaktsis C, Yager E. Susceptibility and resistance to monocytic ehrlichiosis in the mouse. Ann N Y Acad Sci 2006; 1063:395-402. [PMID: 16481547 DOI: 10.1196/annals.1355.071] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
To address the role of cellular immunity during ehrlichia infection, we have utilized a model of monocytic ehrlichiosis that results from infection of mice by Ixodes ovatus ehrlichia (IOE). Although ehrlichiosis in humans is largely a disease of immunocompromised individuals, the use of the IOE model has allowed us to identify factors required for host defense in normal mice. Using a low-dose infection C57BL/6 mouse model, we have demonstrated that host defense requires immune mechanisms involving CD4 T cell-mediated, TNF-alpha-, IL-12-, and IFN-gamma-dependent, macrophage activation. We have also provided formal evidence that IFN-gamma produced by CD4 Th1 cells is sufficient for protective immunity. Our recent studies have demonstrated, in addition, an essential role for IL-10, which is probably important in inhibiting immunopathological responses, and for inducible nitric oxide synthase. The latter observation establishes an important role for reactive nitrogen intermediates in bacterial elimination in vivo. In contrast, evaluation of mice carrying wild-type and mutant alleles of Nramp1 revealed at most a modest role for this gene in resistance to fatal IOE infection. Other studies in low-dose infected mice have indicated that the generation of immunological memory may be impaired during low-dose IOE infection, possibly due to bacterial immune subversion. These studies highlight the utility of the IOE mouse model in identifying important parameters of the immune response during ehrlichiosis.
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Affiliation(s)
- Gary M Winslow
- Wadsworth Center, New York State Department of Health, Albany, NY 12201-2002, USA.
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