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Dahmani M, Zhu JC, Cook JH, Riley SP. Anaphylatoxin signaling activates macrophages to control intracellular Rickettsia proliferation. Microbiol Spectr 2023; 11:e0253823. [PMID: 37855623 PMCID: PMC10714731 DOI: 10.1128/spectrum.02538-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 09/11/2023] [Indexed: 10/20/2023] Open
Abstract
IMPORTANCE Pathogenic Rickettsia species are extremely dangerous bacteria that grow within the cytoplasm of host mammalian cells. In most cases, these bacteria are able to overpower the host cell and grow within the protected environment of the cytoplasm. However, a dramatic conflict occurs when Rickettsia encounter innate immune cells; the bacteria can "win" by taking over the host, or the bacteria can "lose" if the host cell efficiently fights the infection. This manuscript examines how the immune complement system is able to detect the presence of Rickettsia and alert nearby cells. Byproducts of complement activation called anaphylatoxins are signals that "activate" innate immune cells to mount an aggressive defensive strategy. This study enhances our collective understanding of the innate immune reaction to intracellular bacteria and will contribute to future efforts at controlling these dangerous infections.
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Affiliation(s)
- Mustapha Dahmani
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
| | - Jinyi C. Zhu
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
| | - Jack H. Cook
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
| | - Sean P. Riley
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
- Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
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2
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Helminiak L, Mishra S, Keun Kim H. Pathogenicity and virulence of Rickettsia. Virulence 2022; 13:1752-1771. [PMID: 36208040 PMCID: PMC9553169 DOI: 10.1080/21505594.2022.2132047] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/16/2022] [Accepted: 09/29/2022] [Indexed: 12/24/2022] Open
Abstract
Rickettsiae include diverse Gram-negative microbial species that exhibit obligatory intracellular lifecycles between mammalian hosts and arthropod vectors. Human infections with arthropod-borne Rickettsia continue to cause significant morbidity and mortality as recent environmental changes foster the proliferation of arthropod vectors and increased exposure to humans. However, the technical difficulties in working with Rickettsia have delayed our progress in understanding the molecular mechanisms involved in rickettsial pathogenesis and disease transmission. Recent advances in developing genetic tools for Rickettsia have enabled investigators to identify virulence genes, uncover molecular functions, and characterize host responses to rickettsial determinants. Therefore, continued efforts to determine virulence genes and their biological functions will help us understand the underlying mechanisms associated with arthropod-borne rickettsioses.
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Affiliation(s)
| | | | - Hwan Keun Kim
- Center for Infectious Diseases, Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY, USA
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3
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Immune Monitoring of Paediatric Patients Infected with Rickettsia rickettsii, Ehrlichia canis and Coinfected. Pathogens 2022; 11:pathogens11111351. [PMID: 36422602 PMCID: PMC9696171 DOI: 10.3390/pathogens11111351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/17/2022] Open
Abstract
In 2021, 273 Rocky Mountain spotted fever cases were reported nationwide in Mexico. In Chihuahua City, fourteen samples were obtained from children suspected of rickettsial infection. The analysis of samples (January to December 2021) showed prevalence rates of 28.5%, 43%, and 28.5% for Rickettsia rickettsii, Ehrlichia canis, and both pathogens in coinfection, respectively. The analysis of clinical haematological and biochemistry analytes showed alterations; 100% of the children had elevated liver enzymes and coagulation times, 64% showed leukocytosis due to neutrophilia, 55% had thrombocytopenia, lymphopenia, and hypoalbuminemia, and 45% showed normocytic normochromic anaemia. Statistically significant differences were observed in the expression of the chemokines IL-8, RANTES, CXCL9/MIG, and CXCL10/IP-10 across the coinfected and control groups, and the difference in IP-10 expression was significant for patients infected by R. rickettsii compared to the control group. Additionally, significant differences were observed for expression levels of IL-1β, IL-6, IL-17, IFNγ, and TNFα among the R. rickettsii-positive group compared to the control group. On the other hand, the coinfected group exhibited modified levels of IL-6, IL-8, and IL-10 compared with the control group. Finally, significant differences were observed for CD8+ T lymphocyte subpopulations between individuals positive for R. rickettsii and those positive for E. canis.
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4
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Xu S, Jin T, Weng J. Endothelial Cells as a Key Cell Type for Innate Immunity: A Focused Review on RIG-I Signaling Pathway. Front Immunol 2022; 13:951614. [PMID: 35865527 PMCID: PMC9294349 DOI: 10.3389/fimmu.2022.951614] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 06/06/2022] [Indexed: 12/25/2022] Open
Abstract
The vascular endothelium consists of a highly heterogeneous monolayer of endothelial cells (ECs) which are the primary target for bacterial and viral infections due to EC’s constant and close contact with the bloodstream. Emerging evidence has shown that ECs are a key cell type for innate immunity. Like macrophages, ECs serve as sentinels when sensing invading pathogens or microbial infection caused by viruses and bacteria. It remains elusive how ECs senses danger signals, transduce the signal and fulfil immune functions. Retinoic acid-inducible gene-I (RIG-I, gene name also known as DDX58) is an important member of RIG-I-like receptor (RLR) family that functions as an important pathogen recognition receptor (PRR) to execute immune surveillance and confer host antiviral response. Recent studies have demonstrated that virus infection, dsRNA, dsDNA, interferons, LPS, and 25-hydroxycholesterol (25-HC) can increase RIG-1 expression in ECs and propagate anti-viral response. Of translational significance, RIG-I activation can be inhibited by Panax notoginseng saponins, endogenous PPARγ ligand 15-PGJ2, tryptanthrin and 2-animopurine. Considering the pivotal role of inflammation and innate immunity in regulating endothelial dysfunction and atherosclerosis, here we provided a concise review of the role of RIG-I in endothelial cell function and highlight future direction to elucidate the potential role of RIG-I in regulating cardiovascular diseases as well as virus infectious disease, including COVID-19. Furthered understanding of RIG-I-mediated signaling pathways is important to control disorders associated with altered immunity and inflammation in ECs.
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Affiliation(s)
- Suowen Xu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, China
- Laboratory of Metabolics and Cardiovascular Diseases, Institute of Endocrine and Metabolic Diseases, University of Science and Technology of China, Hefei, China
- Biomedical Sciences and Health Laboratory of Anhui Province , University of Science and Technology of China, Hefei, China
- *Correspondence: Suowen Xu, ; Jianping Weng,
| | - Tengchuan Jin
- Laboratory of Structural Immunology, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jianping Weng
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, China
- Laboratory of Metabolics and Cardiovascular Diseases, Institute of Endocrine and Metabolic Diseases, University of Science and Technology of China, Hefei, China
- Biomedical Sciences and Health Laboratory of Anhui Province , University of Science and Technology of China, Hefei, China
- *Correspondence: Suowen Xu, ; Jianping Weng,
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5
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Rauch J, Eisermann P, Noack B, Mehlhoop U, Muntau B, Schäfer J, Tappe D. Typhus Group Rickettsiosis, Germany, 2010-2017 1. Emerg Infect Dis 2019; 24:1213-1220. [PMID: 29912688 PMCID: PMC6038764 DOI: 10.3201/eid2407.180093] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Typhus group rickettsiosis is caused by the vectorborne bacteria Rickettsia typhi and R. prowazekii. R. typhi, which causes murine typhus, the less severe endemic form of typhus, is transmitted by fleas; R. prowazekii, which causes the severe epidemic form of typhus, is transmitted by body lice. To examine the immunology of human infection with typhus group rickettsiae, we retrospectively reviewed clinical signs and symptoms, laboratory changes, and travel destinations of 28 patients who had typhus group rickettsiosis diagnosed by the German Reference Center for Tropical Pathogens, Hamburg, Germany, during 2010-2017. Immunofluorescence assays of follow-up serum samples indicated simultaneous seroconversion of IgM, IgA, and IgG or concurrence in the first serum sample. Cytokine levels peaked during the second week of infection, coinciding with organ dysfunction and seroconversion. For 3 patients, R. typhi was detected by species-specific nested quantitative PCR. For all 28 patients, R. typhi was the most likely causative pathogen.
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6
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Konradt C, Hunter CA. Pathogen interactions with endothelial cells and the induction of innate and adaptive immunity. Eur J Immunol 2018; 48:1607-1620. [PMID: 30160302 DOI: 10.1002/eji.201646789] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 07/24/2018] [Accepted: 08/23/2018] [Indexed: 12/28/2022]
Abstract
There are over 10 trillion endothelial cells (EC) that line the vasculature of the human body. These cells not only have specialized functions in the maintenance of homeostasis within the circulation and various tissues but they also have a major role in immune function. EC also represent an important replicative niche for a subset of viral, bacterial, and parasitic organisms that are present in the blood or lymph; however, there are major gaps in our knowledge regarding how pathogens interact with EC and how this influences disease outcome. In this article, we review the literature on EC-pathogen interactions and their role in innate and adaptive mechanisms of resistance to infection and highlight opportunities to address prominent knowledge gaps.
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Affiliation(s)
- Christoph Konradt
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Christopher A Hunter
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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7
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Sahni A, Fang R, Sahni SK, Walker DH. Pathogenesis of Rickettsial Diseases: Pathogenic and Immune Mechanisms of an Endotheliotropic Infection. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2018; 14:127-152. [PMID: 30148688 DOI: 10.1146/annurev-pathmechdis-012418-012800] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Obligately intracytosolic rickettsiae that cycle between arthropod and vertebrate hosts cause human diseases with a spectrum of severity, primarily by targeting microvascular endothelial cells, resulting in endothelial dysfunction. Endothelial cells and mononuclear phagocytes have important roles in the intracellular killing of rickettsiae upon activation by the effector molecules of innate and adaptive immunity. In overwhelming infection, immunosuppressive effects contribute to the severity of illness. Rickettsia-host cell interactions involve host cell receptors for rickettsial ligands that mediate cell adhesion and, in some instances, trigger induced phagocytosis. Rickettsiae interact with host cell actin to effect both cellular entry and intracellular actin-based mobility. The interaction of rickettsiae with the host cell also involves rickettsial evasion of host defense mechanisms and exploitation of the intracellular environment. Signal transduction events exemplify these effects. An intriguing frontier is the array of rickettsial noncoding RNA molecules and their potential effects on the pathogenesis and transmission of rickettsial diseases.
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Affiliation(s)
- Abha Sahni
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
| | - Rong Fang
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
| | - Sanjeev K Sahni
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
| | - David H Walker
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
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8
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Quiroz-Castañeda RE, Cobaxin-Cárdenas M, Cuervo-Soto LI. Exploring the diversity, infectivity and metabolomic landscape of Rickettsial infections for developing novel therapeutic intervention strategies. Cytokine 2018; 112:63-74. [PMID: 30072088 DOI: 10.1016/j.cyto.2018.07.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 07/09/2018] [Accepted: 07/17/2018] [Indexed: 12/25/2022]
Abstract
Rickettsioses are zoonotic infections caused by obligate intracellular bacteria of the genera Rickettsia that affect human health; sometimes humans being considered as accidental hosts. At a molecular level, the rickettsiae infection triggers molecular signaling leading to the secretion of proinflammatory cytokines. These cytokines direct the immune response to the host cell damage and pathogen removal. In this review, we present metabolic aspects of the host cell in the presence of rickettsiae and how this presence triggers an inflammatory response to cope with the pathogen. We also reviewed the secretion of cytokines that modulates host cell response at immune and metabolic levels.
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Affiliation(s)
- Rosa Estela Quiroz-Castañeda
- Unidad de Anaplasmosis, Centro Nacional de Investigación Disciplinaria en Parasitología Veterinaria, (CENID-PAVET, INIFAP), Carretera Federal Cuernavaca Cuautla 8534, Progreso, 62574 Jiutepec, Morelos, Mexico.
| | - Mayra Cobaxin-Cárdenas
- Unidad de Anaplasmosis, Centro Nacional de Investigación Disciplinaria en Parasitología Veterinaria, (CENID-PAVET, INIFAP), Carretera Federal Cuernavaca Cuautla 8534, Progreso, 62574 Jiutepec, Morelos, Mexico.
| | - Laura Inés Cuervo-Soto
- Facultad de Ciencias, Departamento de Biología, Universidad Antonio Nariño, Sede Circunvalar Carrera 3 Este, No. 47 A15, Bogotá, Colombia
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Serum cytokine responses in Rickettsia felis infected febrile children, Ghana. Med Microbiol Immunol 2018; 207:243-248. [PMID: 29736763 PMCID: PMC6096778 DOI: 10.1007/s00430-018-0544-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 04/24/2018] [Indexed: 11/13/2022]
Abstract
The intracellular pathogen Rickettsia felis causes flea-borne spotted fever and is increasingly recognized as an emerging cause of febrile illness in Africa, where co-infection with Plasmodium falciparum is common. Rickettsiae invade endothelial cells. Little is known, however, about the early immune responses to infection. In this study, we characterize for the first time the cytokine profile in the acute phase of illness caused by R. felis infection, as well as in plasmodial co-infection, using serum from 23 febrile children < 15 years of age and 20 age-matched healthy controls from Ghana. Levels of IL-8 (interleukin-8), IP-10 (interferon-γ-induced protein-10), MCP-1 (monocyte chemotactic protein-1), MIP-1α (macrophage inflammatory protein-1α) and VEGF (vascular endothelial growth factor) were significantly elevated in R. felis mono-infection; however, IL-8 and VEGF elevation was not observed in plasmodial co-infections. These results have important implications in understanding the early immune responses to R. felis and suggest a complex interplay in co-infections.
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10
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Helgren TR, Seven ES, Chen C, Edwards TE, Staker BL, Abendroth J, Myler PJ, Horn JR, Hagen TJ. The identification of inhibitory compounds of Rickettsia prowazekii methionine aminopeptidase for antibacterial applications. Bioorg Med Chem Lett 2018; 28:1376-1380. [PMID: 29551481 PMCID: PMC5908248 DOI: 10.1016/j.bmcl.2018.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 02/28/2018] [Accepted: 03/01/2018] [Indexed: 11/25/2022]
Abstract
Methionine aminopeptidase (MetAP) is a dinuclear metalloprotease responsible for the cleavage of methionine initiator residues from nascent proteins. MetAP activity is necessary for bacterial proliferation and is therefore a projected novel antibacterial target. A compound library consisting of 294 members containing metal-binding functional groups was screened against Rickettsia prowazekii MetAP to determine potential inhibitory motifs. The compounds were first screened against the target at a concentration of 10 µM and potential hits were determined to be those exhibiting greater than 50% inhibition of enzymatic activity. These hit compounds were then rescreened against the target in 8-point dose-response curves and 11 compounds were found to inhibit enzymatic activity with IC50 values of less than 10 µM. Finally, compounds (1-5) were docked against RpMetAP with AutoDock to determine potential binding mechanisms and the results were compared with crystal structures deposited within the PDB.
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Affiliation(s)
- Travis R Helgren
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Elif S Seven
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Congling Chen
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Thomas E Edwards
- Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Bart L Staker
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA; Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Avenue N., Seattle, WA 98109, USA
| | - Jan Abendroth
- Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Peter J Myler
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA; Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Avenue N., Seattle, WA 98109, USA
| | - James R Horn
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Timothy J Hagen
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA.
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11
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Osterloh A. Immune response against rickettsiae: lessons from murine infection models. Med Microbiol Immunol 2017; 206:403-417. [PMID: 28770333 PMCID: PMC5664416 DOI: 10.1007/s00430-017-0514-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 07/20/2017] [Indexed: 12/19/2022]
Abstract
Rickettsiae are small intracellular bacteria that can cause life-threatening febrile diseases. Rickettsioses occur worldwide with increasing incidence. Therefore, a vaccine is highly desired. A prerequisite for the development of a vaccine is the knowledge of the immune response against these bacteria, in particular protective immunity. In recent years murine models of rickettsial infections have been established, and the study of immune response against rickettsiae in mice provided many new insights into protective and pathological immune reactions. This review summarizes the current knowledge about immune mechanisms in protection and pathology in rickettsial infections.
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Affiliation(s)
- Anke Osterloh
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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12
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Outer Membrane Protein OmpB Methylation May Mediate Bacterial Virulence. Trends Biochem Sci 2017; 42:936-945. [PMID: 29037863 DOI: 10.1016/j.tibs.2017.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 09/16/2017] [Accepted: 09/20/2017] [Indexed: 12/29/2022]
Abstract
Methylation of outer membrane proteins (OMPs) has been implicated in bacterial virulence. Lysine methylation in rickettsial OmpB is correlated with rickettsial virulence, and N- and O-methylations are also observed in virulence-relevant OMPs from several pathogenic bacteria that cause typhus, leptospirosis, tuberculosis, and anaplasmosis. We summarize recent findings on the structure of methylated OmpB, biochemical characterization, and crystal structures of OmpB methyltransferases. Native rickettsial OmpB purified from highly virulent strains contains multiple clusters of trimethyllysine, in contrast with mostly monomethyllysine, and no trimethyllysine is found in an avirulent strain. Crystal structure of the methyltransferases reveals mechanistic insights for catalysis, and a working model is discussed for this unusual post-translational modification.
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13
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Helgren TR, Chen C, Wangtrakuldee P, Edwards TE, Staker BL, Abendroth J, Sankaran B, Housley NA, Myler PJ, Audia JP, Horn JR, Hagen TJ. Rickettsia prowazekii methionine aminopeptidase as a promising target for the development of antibacterial agents. Bioorg Med Chem 2017; 25:813-824. [PMID: 28089350 PMCID: PMC5319851 DOI: 10.1016/j.bmc.2016.11.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/06/2016] [Accepted: 11/08/2016] [Indexed: 01/07/2023]
Abstract
Methionine aminopeptidase (MetAP) is a class of ubiquitous enzymes essential for the survival of numerous bacterial species. These enzymes are responsible for the cleavage of N-terminal formyl-methionine initiators from nascent proteins to initiate post-translational modifications that are often essential to proper protein function. Thus, inhibition of MetAP activity has been implicated as a novel antibacterial target. We tested this idea in the present study by targeting the MetAP enzyme in the obligate intracellular pathogen Rickettsia prowazekii. We first identified potent RpMetAP inhibitory species by employing an in vitro enzymatic activity assay. The molecular docking program AutoDock was then utilized to compare published crystal structures of inhibited MetAP species to docked poses of RpMetAP. Based on these in silico and in vitro screens, a subset of 17 compounds was tested for inhibition of R. prowazekii growth in a pulmonary vascular endothelial cell (EC) culture infection model system. All compounds were tested over concentration ranges that were determined to be non-toxic to the ECs and 8 of the 17 compounds displayed substantial inhibition of R. prowazekii growth. These data highlight the therapeutic potential for inhibiting RpMetAP as a novel antimicrobial strategy and set the stage for future studies in pre-clinical animal models of infection.
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Affiliation(s)
- Travis R Helgren
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Congling Chen
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Phumvadee Wangtrakuldee
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Thomas E Edwards
- Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Bart L Staker
- Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Avenue N., Seattle, WA 98109, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Jan Abendroth
- Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Banumathi Sankaran
- Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Nicole A Housley
- Department of Microbiology and Immunology and The Center for Lung Biology, University of South Alabama College of Medicine, Laboratory of Infectious Diseases, 307 North University Blvd, Mobile, AL 36688, USA
| | - Peter J Myler
- Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Avenue N., Seattle, WA 98109, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA; Department of Global Health and Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, WA 98195, USA
| | - Jonathon P Audia
- Department of Microbiology and Immunology and The Center for Lung Biology, University of South Alabama College of Medicine, Laboratory of Infectious Diseases, 307 North University Blvd, Mobile, AL 36688, USA
| | - James R Horn
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Timothy J Hagen
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA.
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14
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Curto P, Simões I, Riley SP, Martinez JJ. Differences in Intracellular Fate of Two Spotted Fever Group Rickettsia in Macrophage-Like Cells. Front Cell Infect Microbiol 2016; 6:80. [PMID: 27525249 PMCID: PMC4965480 DOI: 10.3389/fcimb.2016.00080] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 07/18/2016] [Indexed: 12/21/2022] Open
Abstract
Spotted fever group (SFG) rickettsiae are recognized as important agents of human tick-borne diseases worldwide, such as Mediterranean spotted fever (Rickettsia conorii) and Rocky Mountain spotted fever (Rickettsia rickettsii). Recent studies in several animal models have provided evidence of non-endothelial parasitism by pathogenic SFG Rickettsia species, suggesting that the interaction of rickettsiae with cells other than the endothelium may play an important role in pathogenesis of rickettsial diseases. These studies raise the hypothesis that the role of macrophages in rickettsial pathogenesis may have been underappreciated. Herein, we evaluated the ability of two SFG rickettsial species, R. conorii (a recognized human pathogen) and Rickettsia montanensis (a non-virulent member of SFG) to proliferate in THP-1 macrophage-like cells, or within non-phagocytic cell lines. Our results demonstrate that R. conorii was able to survive and proliferate in both phagocytic and epithelial cells in vitro. In contrast, R. montanensis was able to grow in non-phagocytic cells, but was drastically compromised in the ability to proliferate within both undifferentiated and PMA-differentiated THP-1 cells. Interestingly, association assays revealed that R. montanensis was defective in binding to THP-1-derived macrophages; however, the invasion of the bacteria that are able to adhere did not appear to be affected. We have also demonstrated that R. montanensis which entered into THP-1-derived macrophages were rapidly destroyed and partially co-localized with LAMP-2 and cathepsin D, two markers of lysosomal compartments. In contrast, R. conorii was present as intact bacteria and free in the cytoplasm in both cell types. These findings suggest that a phenotypic difference between a non-pathogenic and a pathogenic SFG member lies in their respective ability to proliferate in macrophage-like cells, and may provide an explanation as to why certain SFG rickettsial species are not associated with disease in mammals.
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Affiliation(s)
- Pedro Curto
- PhD Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of CoimbraCoimbra, Portugal
- Institute for Interdisciplinary Research, University of CoimbraCoimbra, Portugal
- Center for Neuroscience and Cell BiologyCoimbra, Portugal
- Vector Borne Disease Laboratories, Department of Pathobiological Sciences, LSU School of Veterinary MedicineBaton Rouge, LA, USA
| | - Isaura Simões
- Center for Neuroscience and Cell BiologyCoimbra, Portugal
- Vector Borne Disease Laboratories, Department of Pathobiological Sciences, LSU School of Veterinary MedicineBaton Rouge, LA, USA
- Biocant, Biotechnology Innovation CenterCantanhede, Portugal
| | - Sean P. Riley
- Vector Borne Disease Laboratories, Department of Pathobiological Sciences, LSU School of Veterinary MedicineBaton Rouge, LA, USA
| | - Juan J. Martinez
- Vector Borne Disease Laboratories, Department of Pathobiological Sciences, LSU School of Veterinary MedicineBaton Rouge, LA, USA
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15
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Ka MB, Bechah Y, Olive D, Mege JL. Programmed death ligand-1 expression and memory T-cell generation in Coxiella burnetii infection. Microb Pathog 2015; 80:1-6. [DOI: 10.1016/j.micpath.2015.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 02/07/2015] [Accepted: 02/09/2015] [Indexed: 10/24/2022]
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16
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Wang J, Dyachenko V, Munderloh UG, Straubinger RK. Transmission of Anaplasma phagocytophilum from endothelial cells to peripheral granulocytes in vitro under shear flow conditions. Med Microbiol Immunol 2015; 204:593-603. [PMID: 25618174 DOI: 10.1007/s00430-015-0387-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 01/13/2015] [Indexed: 01/06/2023]
Abstract
Anaplasma phagocytophilum (Ap) is a tick-borne pathogen, which can cause granulocytic anaplasmosis in humans and animals. In vivo this obligate intracellular pathogen is primarily located in circulating mature granulocytes, but it also infects endothelial cells. In order to study the interaction between Ap-infected endothelial cells and human granulocytes under conditions similar to those found naturally in the infected host, an in vitro model that mimics physiological flow conditions in the microvasculature was established. Cell-to-cell interactions were then visualized by microscopy, which showed that granulocytes adhered strongly to Ap-infected endothelial cells at a shear stress of 0.5 dyne/cm(2). In addition, Ap-transmission assays under flow conditions showed that the bacteria transferred from infected endothelial cells to circulating granulocytes and were able to establish infection in constantly moving granulocytes. Cell surface analysis showed that Ap induced up-regulation of the cell adhesion molecules ICAM-1 and VCAM-1 on infected endothelial cells in a dose-dependent manner. Furthermore, IL-8 secretion by endothelial cells indicated that the presence of Ap induced a pro-inflammatory response. In summary, the results of this study suggest that endothelial cells of the microvasculature (1) provide an excellent site for Ap dissemination to peripheral blood granulocytes under flow conditions and therefore may play a crucial role in the development of persistent infection, and (2) are stimulated by Ap to express surface molecules and cytokines that may lead to inflammatory responses at the site of the infection.
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Affiliation(s)
- Jinyong Wang
- Institute for Infectious Diseases and Zoonoses, Department of Veterinary Sciences, Faculty of Veterinary Medicine, LMU Munich, Veterinärstr. 13, 80539, Munich, Germany
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17
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Robinson RT. IL12Rβ1: the cytokine receptor that we used to know. Cytokine 2014; 71:348-59. [PMID: 25516297 DOI: 10.1016/j.cyto.2014.11.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 11/15/2014] [Accepted: 11/17/2014] [Indexed: 12/22/2022]
Abstract
Human IL12RB1 encodes IL12Rβ1, a type I transmembrane receptor that is an essential component of the IL12- and IL23-signaling complex. IL12RB1 is well-established as being a promoter of delayed type hypersensitivity (DTH), the immunological reaction that limits tuberculosis. However, recent data demonstrate that in addition to promoting DTH, IL12RB1 also promotes autoimmunity. The contradictory roles of IL12RB1 in human health raises the question, what are the factors governing IL12RB1 function in a given individual, and how is inter-individual variability in IL12RB1 function introduced? Here we review recent data that demonstrate individual variability in IL12RB1 function is introduced at the epigenetic, genomic polymorphism, and mRNA splicing levels. Where and how these differences contribute to disease susceptibility and outcome are also reviewed. Collectively, recent data support a model wherein IL12RB1 sequence variability - whether introduced at the genomic or post-transcriptional level - contributes to disease, and that human IL12RB1 is not as simple a gene as we once believed.
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Affiliation(s)
- Richard T Robinson
- Department of Microbiology and Molecular Genetics, The Medical College of Wisconsin, Milwaukee, WI 53226, United States.
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18
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Bechah Y, Verneau J, Ben Amara A, Barry AO, Lépolard C, Achard V, Panicot-Dubois L, Textoris J, Capo C, Ghigo E, Mege JL. Persistence of Coxiella burnetii, the agent of Q fever, in murine adipose tissue. PLoS One 2014; 9:e97503. [PMID: 24835240 PMCID: PMC4023977 DOI: 10.1371/journal.pone.0097503] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 04/17/2014] [Indexed: 12/12/2022] Open
Abstract
Coxiella burnetii, the agent of Q fever, is known to persist in humans and rodents but its cellular reservoir in hosts remains undetermined. We hypothesized that adipose tissue serves as a C. burnetii reservoir during bacterial latency. BALB/c and C57BL/6 mice were infected with C. burnetii by the intraperitoneal route or the intracheal route. Adipose tissue was tested for the presence of C. burnetii several months after infection. C. burnetii was detected in abdominal, inguinal and dorsal adipose tissue 4 months post-infection, when no bacteria were detected in blood, liver, lungs and spleen, regardless of the inoculation route and independently of mouse strain. The transfer of abdominal adipose tissue from convalescent BALB/c mice to naïve immunodeficient mice resulted in the infection of the recipient animals. It is likely that C. burnetii infects adipocytes in vivo because bacteria were found in adipocytes within adipose tissue and replicated within in vitro-differentiated adipocytes. In addition, C. burnetii induced a specific transcriptional program in in-vivo and in vitro-differentiated adipocytes, which was enriched in categories associated with inflammatory response, hormone response and cytoskeleton. These changes may account for bacterial replication in in-vitro and chronic infection in-vivo. Adipose tissue may be the reservoir in which C. burnetii persists for prolonged periods after apparent clinical cure. The mouse model of C. burnetii infection may be used to understand the relapses of Q fever and provide new perspectives to the follow-up of patients.
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Affiliation(s)
- Yassina Bechah
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
- * E-mail:
| | - Johanna Verneau
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
| | - Amira Ben Amara
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
| | - Abdoulaye O. Barry
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
| | - Catherine Lépolard
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
| | - Vincent Achard
- Nutrition, Obésité et Risque Thrombotique, Aix-Marseille Université, UMR_S INSERM, Marseille, France
| | - Laurence Panicot-Dubois
- Aix-Marseille Université UMR-S1076, Endothélium, Pathologies Vasculaires et Cibles Thérapeutiques, Marseille, France
| | - Julien Textoris
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
| | - Christian Capo
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
| | - Eric Ghigo
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
| | - Jean-Louis Mege
- Unité de Recherche sur les Maladies Infectieuses Transmissibles et Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Marseille, France
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Kernif T, Socolovschi C, Bitam I, Raoult D, Parola P. Vector-Borne Rickettsioses in North Africa. Infect Dis Clin North Am 2012; 26:455-78. [DOI: 10.1016/j.idc.2012.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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20
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Chochlakis D, Ioannou I, Sandalakis V, Dimitriou T, Kassinis N, Papadopoulos B, Tselentis Y, Psaroulaki A. Spotted fever group Rickettsiae in ticks in Cyprus. MICROBIAL ECOLOGY 2012; 63:314-23. [PMID: 21833539 DOI: 10.1007/s00248-011-9926-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 07/21/2011] [Indexed: 05/24/2023]
Abstract
In two surveys conducted from March 1999 to March 2001 and from January 2004 to December 2006, a total of 3,950 ticks (belonging to ten different species) were collected from seven domestic and wild animals (goat, sheep, cattle, dog, fox, hare, and mouflon) from different localities throughout Cyprus. In order to establish their infection rate with Spotted Fever Rickettsiae (SFG), ticks were pooled and tested by polymerase chain reaction targeting gltA and ompA genes, followed by sequencing analysis. When tick pools tested positive, individual ticks were then tested one by one, and of the 3,950 ticks screened, rickettsial DNA was identified in 315 ticks (infection rate, 8%). Five SFG Rickettsiae were identified: Rickettsia aeschlimannii in Hyalomma marginatum marginatum, Rickettsia massiliae in Rhipicephalus turanicus and Rhipicephalus sanguineus, Rickettsia sibirica mongolotimonae in Hyalomma anatolicum excavatum, and a Rickettsia endosymbiont of Haemaphysalis sulcata (later described as Rickettsia hoogstraalii) in Haemaphysalis punctata. Two additional genes, 17 kDa and ompB, were targeted to characterize a new genotype of "Candidatus Rickettsia barbariae" genotype in R. turanicus, designated here as "Candidatus Rickettsia barbariae" Cretocypriensis. These results confirm the presence of a spectrum of SFG Rickettsiae on the island. Further studies are necessary to gain better knowledge on the epidemiology of SFG Rickettsiae in Cyprus.
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Affiliation(s)
- Dimosthenis Chochlakis
- Laboratory of Clinical Bacteriology, Parasitology, Zoonoses and Geographical Medicine (WHO Collaborating Center), Medical School, University of Crete, Voutes, Heraklion, Crete 71100, Greece
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21
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Bechah Y, El Karkouri K, Mediannikov O, Leroy Q, Pelletier N, Robert C, Médigue C, Mege JL, Raoult D. Genomic, proteomic, and transcriptomic analysis of virulent and avirulent Rickettsia prowazekii reveals its adaptive mutation capabilities. Genome Res 2010; 20:655-63. [PMID: 20368341 PMCID: PMC2860167 DOI: 10.1101/gr.103564.109] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 02/11/2010] [Indexed: 11/24/2022]
Abstract
Rickettsia prowazekii, the agent of epidemic typhus, is an obligate intracellular bacterium that is transmitted to human beings by the body louse. Several strains that differ considerably in virulence are recognized, but the genetic basis for these variations has remained unknown since the initial description of the avirulent vaccine strain nearly 70 yr ago. We use a recently developed murine model of epidemic typhus and transcriptomic, proteomic, and genetic techniques to identify the factors associated with virulence. We identified four phenotypes of R. prowazekii that differed in virulence, associated with the up-regulation of antiapoptotic genes or the interferon I pathway in the host cells. Transcriptional and proteomic analyses of R. prowazekii surface protein expression and protein methylation varied with virulence. By sequencing a virulent strain and using comparative genomics, we found hotspots of mutations in homopolymeric tracts of poly(A) and poly(T) in eight genes in an avirulent strain that split and inactivated these genes. These included recO, putative methyltransferase, and exported protein. Passage of the avirulent Madrid E strain in cells or in experimental animals was associated with a cascade of gene reactivations, beginning with recO, that restored the virulent phenotype. An area of genomic plasticity appears to determine virulence in R. prowazekii and represents an example of adaptive mutation for this pathogen.
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Affiliation(s)
- Yassina Bechah
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
| | - Khalid El Karkouri
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
| | - Oleg Mediannikov
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
| | - Quentin Leroy
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
| | - Nicolas Pelletier
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
| | - Catherine Robert
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
| | - Claudine Médigue
- Genoscope, Centre National de Séquençage, Laboratoire de Génomique Comparative, 91057 Evry cedex, France
| | - Jean-Louis Mege
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
| | - Didier Raoult
- Unit for Research on Emergent and Tropical Infectious Diseases (URMITE), Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement, Faculty of Medicine, University of the Mediterranean, 13005 Marseille, France
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22
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Abstract
Infectious agents have been implicated in the etiopathogenesis of various vasculitides via numerous and overlapping mechanisms including direct microbial invasion of endothelial cells, immune complex mediated vessel wall damage and stimulation of autoreactive B and/or T cells through molecular mimicry and superantigens. While the causative role of hepatitis B virus in polyarteritis nodosa and hepatitis C virus in mixed cryoglobulinemia is clearly established, evidence for the association of other infectious agents with vasculitis, including human immunodeficiency virus, parvovirus B19, cytomegalovirus, varicella zoster virus, Staphylococcus aureus, rickettsiaceae, Treponema pallidum and Borrelia burgdorferi, among numerous others, is accumulating. The spectrum of association of infectious agents; bacteria, viruses and parasites, with systemic vasculitides, will be reviewed herewith.
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Affiliation(s)
- Merav Lidar
- Center for Autoimmune Diseases, Rheumatology Unit, Sheba Medical Center (SMC), Tel Hashomer and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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23
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Fernandez-Borja M, van Buul JD, Hordijk PL. The regulation of leucocyte transendothelial migration by endothelial signalling events. Cardiovasc Res 2010; 86:202-10. [PMID: 20068003 DOI: 10.1093/cvr/cvq003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Leucocytes use sophisticated mechanisms to cross the endothelium lining the vasculature. This is initiated by chemokine- and adhesion molecule-induced intracellular signalling that controls adhesion, spreading, and motility. At the same time, adherent leucocytes trigger the endothelium, manipulating the barrier to promote their transmigration into the underlying tissues. Over the past years, our insights in the associated signalling events within the endothelium have increased considerably, albeit the order of events, their crosstalk, and the consequences for endothelial cells and leucocytes are only partially resolved. Here, we briefly review endothelial signalling that is initiated at the apical endothelial membrane, where the first contact with the leucocytes takes place and signal transduction is induced. In addition, we discuss subsequent events at endothelial cell-cell junctions insofar as they have been linked to transendothelial migration. Finally, we briefly touch upon the modulation of endothelial signalling by infectious pathogens, since these have developed additional, elegant ways to manipulate the endothelium and transendothelial migration that may provide new, relevant insights into this process.
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Affiliation(s)
- Mar Fernandez-Borja
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands
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24
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Abstract
The vascular endothelium is the main target of a limited number of infectious agents, Rickettsia, Ehrlichia ruminantium, and Orientia tsutsugamushi are among them. These arthropod-transmitted obligately-intracellular bacteria cause serious systemic diseases that are not infrequently lethal. In this review, we discuss the bacterial biology, vector biology, and clinical aspects of these conditions with particular emphasis on the interactions of these bacteria with the vascular endothelium and how it responds to intracellular infection. The study of these bacteria in relevant in vivo models is likely to offer new insights into the physiology of the endothelium that have not been revealed by other models.
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Affiliation(s)
- Gustavo Valbuena
- Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0609, USA.
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25
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Sahni SK, Rydkina E. Host-cell interactions with pathogenic Rickettsia species. Future Microbiol 2009; 4:323-39. [PMID: 19327117 DOI: 10.2217/fmb.09.6] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Pathogenic Rickettsia species are Gram-negative, obligate intracellular bacteria responsible for the spotted fever and typhus groups of diseases around the world. It is now well established that a majority of sequelae associated with human rickettsioses are the outcome of the pathogen's affinity for endothelium lining the blood vessels, the consequences of which are vascular inflammation, insult to vascular integrity and compromised vascular permeability, collectively termed 'Rickettsial vasculitis'. Signaling mechanisms leading to transcriptional activation of target cells in response to Rickettsial adhesion and/or invasion, differential activation of host-cell signaling due to infection with spotted fever versus typhus subgroups of Rickettsiae, and their contributions to the host's immune responses and determination of cell fate are the major subtopics of this review. Also included is a succinct analysis of established in vivo models and their use for understanding Rickettsial interactions with host cells and pathogenesis of vasculotropic rickettsioses. Continued progress in these important but relatively under-explored areas of bacterial pathogenesis research should further highlight unique aspects of Rickettsial interactions with host cells, elucidate the biological basis of endothelial tropism and reveal novel chemotherapeutic and vaccination strategies for debilitating Rickettsial diseases.
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Affiliation(s)
- Sanjeev K Sahni
- Department of Microbiology & Immunology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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26
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Bechah Y, Capo C, Grau G, Raoult D, Mege JL. Rickettsia prowazekii infection of endothelial cells increases leukocyte adhesion through alphavbeta3 integrin engagement. Clin Microbiol Infect 2009; 15 Suppl 2:249-50. [PMID: 19438625 DOI: 10.1111/j.1469-0691.2008.02675.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Y Bechah
- Faculté de Médecine, URMITE, CNRS-IRD UMR 6236, Université de la Méditerranée, Jean Moulin, Marseille Cedex, France
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27
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Damås JK, Davì G, Jensenius M, Santilli F, Otterdal K, Ueland T, Flo TH, Lien E, Espevik T, Frøland SS, Vitale G, Raoult D, Aukrust P. Relative chemokine and adhesion molecule expression in Mediterranean spotted fever and African tick bite fever. J Infect 2008; 58:68-75. [PMID: 19091423 DOI: 10.1016/j.jinf.2008.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 11/12/2008] [Accepted: 11/13/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVES Mediterranean spotted fever (MSF) caused by Rickettsia conorii (R. conorii) is a potential lethal disease while African tick bite fever (ATBF) caused by Rickettsia africae is a self-limiting flu-like illness. We hypothesized that different inflammatory potential in endothelial cells could contribute to the different clinical features in these rickettsioses. METHODS We analyzed the effect of heat-inactivated R. africae and R. conorii on the mRNA and protein levels of monocyte chemoattractant protein (MCP)-1, interleukin (IL)-8 and adhesion molecules in endothelial cells. Serum samples from patients with MSF (n=16) and ATBF (n=15) were collected before and after therapy. RESULTS R. conorii induced a marked increase in MCP-1, IL-8, and adhesion molecules in endothelial cells, involving toll-like receptor 4 activation. In contrast, R. africae induced MCP-1 expression, but only modest or no responses were seen on IL-8 and adhesion molecules. Comparable to the in vitro response, levels of IL-8 and adhesion molecules showed no or only a modest increase in ATBF patients while these inflammatory markers were markedly elevated during MSF. CONCLUSIONS Our findings suggest a superior inflammatory potential of R. conorii as compared to R. africae in endothelial cells, potentially related to the more severe inflammation in MSF comparing ATBF.
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Affiliation(s)
- Jan K Damås
- Research Institute for Internal Medicine, Rikshospitalet University Hospital, 0027 Oslo, Norway.
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28
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Bechah Y, Capo C, Mege JL, Raoult D. Epidemic typhus. THE LANCET. INFECTIOUS DISEASES 2008; 8:417-26. [DOI: 10.1016/s1473-3099(08)70150-6] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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