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Rajashekar R, Hensel M. Dynamic modification of microtubule-dependent transport by effector proteins of intracellular Salmonella enterica. Eur J Cell Biol 2011; 90:897-902. [PMID: 21803443 DOI: 10.1016/j.ejcb.2011.05.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 05/15/2011] [Accepted: 05/18/2011] [Indexed: 12/17/2022] Open
Abstract
Intracellular Salmonella enterica translocate effector proteins that modify microtubule-dependent transport processes of the host cell and modulate the biogenesis of the Salmonella-containing vacuole (SCV). One functional consequence is the induction of tubular aggregates of endosomal membranes, termed Salmonella-induced filaments or SIFs, and further tubular membrane compartments have recently been described. SIFs are unique, highly dynamic compartments that form by modification of vesicular transport on microtubules. The molecular mechanism of the interference of intracellular Salmonella with host cell vesicular transport is still elusive, but recent studies demonstrate the complexity of pathogenic activities and the intricacy of manipulating host cell functions.
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52
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Carreño LJ, González PA, Bueno SM, Riedel CA, Kalergis AM. Modulation of the dendritic cell-T-cell synapse to promote pathogen immunity and prevent autoimmunity. Immunotherapy 2011; 3:6-11. [PMID: 21524159 DOI: 10.2217/imt.11.38] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The molecular interactions occurring at the interface between dendritic cells (DCs) and T cells play an important role in the immune surveillance against infectious agents, as well as in autoimmune pathogenesis. Therefore, regulation of this interaction arises as an important tool for the prevention and treatment of immune disorders and to improve the protection against pathogens without causing detrimental inflammation. Some of the molecular interactions defining the outcome of the DC-T cell interaction are: T-cell receptor (TCR) binding to the pMHC on the DC surface, which is responsible for the antigenic specificity; and the ratio of activating/inhibitory receptor pairs on the surface of DCs and T cells, which modulate DC immunogenicity and T-cell function, respectively. An alteration in the proper function of these molecules could lead to unbalanced DC-T-cell synapses that either cause a failure to control infections or exacerbated inflammation. Furthermore, some pathogens have developed molecular strategies to impair the function of the synapse to evade adaptive immunity. In this article, we will discuss recent work relative to the molecular mechanisms controlling DC-T-cell synapse and their implications on immunoregulation to control autoimmunity and potentiate pathogen immunity.
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Affiliation(s)
- Leandro J Carreño
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Casilla 114-D, Santiago, Chile
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53
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Development of protective immunity to Salmonella, a mucosal pathogen with a systemic agenda. Mucosal Immunol 2011; 4:371-82. [PMID: 21307847 PMCID: PMC4084725 DOI: 10.1038/mi.2011.2] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Salmonella infections can cause a range of intestinal and systemic diseases in human and animal hosts. Although some Salmonella serovars initiate a localized intestinal inflammatory response, others use the intestine as a portal of entry to initiate a systemic infection. Considerable progress has been made in understanding bacterial invasion and dissemination strategies, as well as the nature of the Salmonella-specific immune response to oral infection. Innate and adaptive immunity are rapidly initiated after oral infection, but these effector responses can also be hindered by bacterial evasion strategies. Furthermore, although Salmonella resides within intramacrophage phagosomes, recent studies have highlighted a surprising collaboration of CD4 Th1, Th17, and B-cell responses in mediating resistance to Salmonella infection.
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54
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Jantsch J, Chikkaballi D, Hensel M. Cellular aspects of immunity to intracellular Salmonella enterica. Immunol Rev 2011; 240:185-95. [PMID: 21349094 DOI: 10.1111/j.1600-065x.2010.00981.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Salmonella enterica is a frequent gastrointestinal pathogen with ability to cause diseases ranging from local gastrointestinal inflammation and diarrhea to life-threatening typhoid fever. Salmonella is an invasive, facultative intracellular pathogen that infects various cell types of the host and can survive and proliferate in different populations of immune cells. During pathogenesis, Salmonella is confronted with various lines of immune defense. To successfully colonize host organisms, the pathogen deploys a set of sophisticated mechanisms of immune evasion and direct manipulation of immune cell functions. In addition to resistance against innate immune mechanisms, including the ability to avoid killing by macrophages and dendritic cells (DCs), Salmonella interferes with antigen presentation by DCs and the formation of an efficient adaptive immune response. In this review, we describe the current understanding of Salmonella virulence factors during intracellular life and focus on the recent advances in the understanding of interference of intracellular Salmonella with cellular functions of immune cells.
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Affiliation(s)
- Jonathan Jantsch
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Erlangen, Germany
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55
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Abstract
The last decade has witnessed increasing research on dissemination of bacterial pathogens in their hosts and on the processes that underlie bacterial spread and growth during organ colonization. Here, we discuss work on the mouse model of human typhoid fever caused by Salmonella enterica serovar Typhimurium. This has revealed the use of several routes of systemic dissemination that result in colonization and growth within the spleen and liver, the major sites of bacterial proliferation. We also highlight techniques that enable in vivo analysis of the infecting population at the spatiotemporal and single cell levels. These approaches have provided more detailed insights into the events underlying the dynamics of Salmonella replication, spread and clearance within host organs and tissues.
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Affiliation(s)
- Kathryn G Watson
- Centre for Molecular Microbiology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK
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56
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Forest CG, Ferraro E, Sabbagh SC, Daigle F. Intracellular survival of Salmonella enterica serovar Typhi in human macrophages is independent of Salmonella pathogenicity island (SPI)-2. MICROBIOLOGY-SGM 2010; 156:3689-3698. [PMID: 20817644 DOI: 10.1099/mic.0.041624-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
For successful infection, Salmonella enterica secretes and injects effector proteins into host cells by two distinct type three secretion systems (T3SSs) located on Salmonella pathogenicity islands (SPIs)-1 and -2. The SPI-2 T3SS is involved in intracellular survival of S. enterica serovar Typhimurium and systemic disease. As little is known regarding the function of the SPI-2 T3SS from S. enterica serovar Typhi, the aetiological agent of typhoid fever, we investigated its role for survival in human macrophages. Mutations in the translocon (sseB), basal secretion apparatus (ssaR) and regulator (ssrB) did not result in any reduction in survival under many of the conditions tested. Similar results were obtained with another S. Typhi strain or by using human primary cells. Results were corroborated based on complete deletion of the SPI-2 T3SS. Surprisingly, the data suggest that the SPI-2 T3SS of S. Typhi is not required for survival in human macrophages.
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Affiliation(s)
- Chantal G Forest
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - Elyse Ferraro
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - Sébastien C Sabbagh
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - France Daigle
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
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57
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Araya DV, Quiroz TS, Tobar HE, Lizana RJ, Quezada CP, Santiviago CA, Riedel CA, Kalergis AM, Bueno SM. Deletion of a prophage-like element causes attenuation of Salmonella enterica serovar Enteritidis and promotes protective immunity. Vaccine 2010; 28:5458-66. [PMID: 20558245 DOI: 10.1016/j.vaccine.2010.05.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 05/23/2010] [Accepted: 05/28/2010] [Indexed: 10/19/2022]
Abstract
Salmonella enterica serovar Enteritidis (S. Enteritidis) is a wide host range serovar belonging to the S. enterica genus. Worldwide, it is one of the most frequent causes of food borne disease. Similar to S. Typhimurium, some virulence genes of S. Enteritidis are located in pathogenicity islands and prophages. In this study we have generated a mutant strain of S. Enteritidis lacking a prophage-like element, denominated varphiSE12. The resulting mutant strain was attenuated and promoted protective immunity in infected mice. Although S. Enteritidis strains lacking the complete prophage varphiSE12 remained capable of surviving inside phagocytic cells, they showed a significantly reduced capacity to colonize internal organs and failed to cause lethal disease in mice. Consistent with these data, infection with S. Enteritidis strains lacking prophage varphiSE12 promoted the production of anti-Salmonella IgG antibodies and led to protection against a challenge with virulent strains of S. Enteritidis. These results suggest that strains lacking this prophage can induce a protective immunity in mice and be considered as potential attenuated vaccines against S. Enteritidis.
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Affiliation(s)
- Daniela V Araya
- Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago 8331010, Chile
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58
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Bernal-Bayard J, Cardenal-Muñoz E, Ramos-Morales F. The Salmonella type III secretion effector, salmonella leucine-rich repeat protein (SlrP), targets the human chaperone ERdj3. J Biol Chem 2010; 285:16360-8. [PMID: 20335166 DOI: 10.1074/jbc.m110.100669] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Effectors of the type III secretion systems (T3SS) are key elements in the interaction between many Gram-negative pathogens and their hosts. SlrP is an effector that is translocated into the eukaryotic host cell through the two virulence-associated T3SS of Salmonella enterica. We found previously that this effector is an E3 ubiquitin ligase for mammalian thioredoxin. Here, we identified ERdj3, an endoplasmic reticulum lumenal chaperone of the Hsp40/DnaJ family, as a new target for SlrP. Experiments with truncated forms of ERdj3 showed that domain II was essential for the interaction with SlrP. Confocal microscopy and subcellular fractionation demonstrated that, in transfected HeLa cells, SlrP was partially located in the endoplasmic reticulum. The presence of SlrP interfered with the binding of ERdj3 to a denatured substrate. Taken together, these data suggest that the role of SlrP in the interaction between Salmonella and the host cell is exerted through the modulation of the function of two independent targets: thioredoxin in the cytosol, and ERdj3 in the endoplasmic reticulum.
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Affiliation(s)
- Joaquín Bernal-Bayard
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain
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59
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Bueno SM, Wozniak A, Leiva ED, Riquelme SA, Carreño LJ, Hardt WD, Riedel CA, Kalergis AM. Salmonella pathogenicity island 1 differentially modulates bacterial entry to dendritic and non-phagocytic cells. Immunology 2010; 130:273-87. [PMID: 20201987 DOI: 10.1111/j.1365-2567.2009.03233.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Salmonella enterica serovar Typhimurium can enter non-phagocytic cells, such as intestinal epithelial cells, by virtue of a Type Three Secretion System (TTSS) encoded in the Salmonella Pathogenicity Island 1 (SPI-1), which translocates bacterial effector molecules into the host cell. Salmonella can also be taken up by dendritic cells (DCs). Although the role of SPI-1 in non-phagocytic cell invasion is well established, its contribution to invasion of phagocytic cells has not been evaluated. Here, we have tested the invasive capacity of a S. Typhimurium strain lacking a key component of its TTSS-1 (DeltaInvC) leading to defective translocation of SPI-1-encoded effectors. Whereas this mutant Salmonella strain was impaired for invasion of non-phagocytic cells, it was taken up by DCs at a significantly higher rate than wild-type Salmonella. Similar to wild-type Salmonella, the DeltaInvC mutant strain retained the capacity to avoid antigen presentation to T cells. However, mice infected with the DeltaInvC mutant strain showed higher survival rate and reduced organ colonization. Our data suggest that, besides promoting phagocytosis by non-phagocytic cells, SPI-1 modulates the number of bacteria that enters DCs. The SPI-1 could be considered not only as an inducer of epithelial cell invasion but as a controller of DC entry.
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Affiliation(s)
- Susan M Bueno
- Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
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60
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Valdez Y, Ferreira RBR, Finlay BB. Molecular mechanisms of Salmonella virulence and host resistance. Curr Top Microbiol Immunol 2010; 337:93-127. [PMID: 19812981 DOI: 10.1007/978-3-642-01846-6_4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Salmonella species can cause typhoid fever and gastroenteritis in humans and pose a global threat to human health. In order to establish a successful infection, Salmonella utilize a large number of genes encoding a variety of virulence factors. Different animal models of infection have been used to better understand the mechanisms underlying each disease including cattle, rodents, and nematodes. To date, a number of different bacterial virulence factors have been identified using such animal models, most of which are secreted by two type three secretion systems (T3SS) encoded within Salmonella pathogenicity islands (SPI) 1 and 2. These proteins alter various host cell pathways, facilitating the invasion of epithelial cells during infection, as well as the survival and replication of Salmonella inside phagocytic cells. On the other hand, host genetics and resistance also play a role in the susceptibility to Salmonella infection. The natural resistance-associated macrophage protein 1 (Nramp1), for example, is critical for host defense, since mice lacking Nramp1 fail to control bacterial replication and succumb to low doses of S. Typhimurium. In this chapter, we analyze the different pathogen and host factors that play a role in the dynamic interaction between Salmonella and its host and their impact on disease.
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Affiliation(s)
- Yanet Valdez
- Department of Microbiology and Immunology, Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
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61
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McLaughlin LM, Govoni GR, Gerke C, Gopinath S, Peng K, Laidlaw G, Chien YH, Jeong HW, Li Z, Brown MD, Sacks DB, Monack D. The Salmonella SPI2 effector SseI mediates long-term systemic infection by modulating host cell migration. PLoS Pathog 2009; 5:e1000671. [PMID: 19956712 PMCID: PMC2777311 DOI: 10.1371/journal.ppat.1000671] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 10/28/2009] [Indexed: 11/24/2022] Open
Abstract
Host-adapted strains of Salmonella enterica cause systemic infections and have the ability to persist systemically for long periods of time despite the presence of a robust immune response. Chronically infected hosts are asymptomatic and transmit disease to naïve hosts via fecal shedding of bacteria, thereby serving as a critical reservoir for disease. We show that the bacterial effector protein SseI (also called SrfH), which is translocated into host cells by the Salmonella Pathogenicity Island 2 (SPI2) type III secretion system (T3SS), is required for Salmonella typhimurium to maintain a long-term chronic systemic infection in mice. SseI inhibits normal cell migration of primary macrophages and dendritic cells (DC) in vitro, and such inhibition requires the host factor IQ motif containing GTPase activating protein 1 (IQGAP1), an important regulator of cell migration. SseI binds directly to IQGAP1 and co-localizes with this factor at the cell periphery. The C-terminal domain of SseI is similar to PMT/ToxA, a bacterial toxin that contains a cysteine residue (C1165) that is critical for activity. Mutation of the corresponding residue in SseI (C178A) eliminates SseI function in vitro and in vivo, but not binding to IQGAP1. In addition, infection with wild-type (WT) S. typhimurium suppressed DC migration to the spleen in vivo in an SseI-dependent manner. Correspondingly, examination of spleens from mice infected with WT S. typhimurium revealed fewer DC and CD4+ T lymphocytes compared to mice infected with ΔsseI S. typhimurium. Taken together, our results demonstrate that SseI inhibits normal host cell migration, which ultimately counteracts the ability of the host to clear systemic bacteria. Bacteria belonging to the genus Salmonella are capable of causing long-term chronic systemic infections, and bacteria primarily reside within macrophages in lymphoid tissues and sporadically are shed in the feces. These persistently infected individuals serve as a significant reservoir for disease transmission. Despite the importance of Salmonella as a human pathogen, relatively little is known about the host immune response or virulence mechanisms of long-term systemic infections. Host-adapted Salmonella strains invade and manipulate host cells by releasing specialized bacterial effector proteins into the host cell. We show that one of these bacterial effector proteins, SseI (SrfH), is required for Salmonella to maintain a long-term chronic systemic infection in mice. SseI is able to block the migration of host immune cells and consequentially attenuate the host's ability to clear systemic bacteria. SseI accomplishes this inhibitory activity in part by associating with the host protein IQGAP1, an important regulator of cell migration. The amino acid sequence of SseI is similar to several other protein sequences of known bacterial pathogens, including PMT/ToxA, a toxin, indicating that these factors may function similarly to one another and may comprise a new family of bacterial effector proteins.
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Affiliation(s)
- Laura M. McLaughlin
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
| | - Gregory R. Govoni
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
| | - Christiane Gerke
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
| | - Smita Gopinath
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
| | - Kaitian Peng
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
| | - Grace Laidlaw
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
| | - Yueh-Hsiu Chien
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
| | - Ha-Won Jeong
- Department of Pathology, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Zhigang Li
- Department of Pathology, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Matthew D. Brown
- Department of Pathology, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - David B. Sacks
- Department of Pathology, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Denise Monack
- Department of Microbiology and Immunology, Stanford University Medical Center, Stanford, California, United States of America
- * E-mail:
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62
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Elgueta R, Tobar JA, Shoji KF, De Calisto J, Kalergis AM, Bono MR, Rosemblatt M, Sáez JC. Gap junctions at the dendritic cell-T cell interface are key elements for antigen-dependent T cell activation. THE JOURNAL OF IMMUNOLOGY 2009; 183:277-84. [PMID: 19542439 DOI: 10.4049/jimmunol.0801854] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The acquired immune response begins with Ag presentation by dendritic cells (DCs) to naive T cells in a heterocellular cell-cell contact-dependent process. Although both DCs and T cells are known to express connexin43, a gap junction protein subunit, the role of connexin43 on the initiation of T cell responses remains to be elucidated. In the present work, we report the formation of gap junctions between DCs and T cells and their role on T cell activation during Ag presentation by DCs. In cocultures of DCs and T cells, Lucifer yellow microinjected into DCs is transferred to adjacent transgenic CD4(+) T cells, only if the specific antigenic peptide was present at least during the first 24 h of cocultures. This dye transfer was sensitive to gap junction blockers, such as oleamide, and small peptides containing the extracellular loop sequences of conexin. Furthermore, in this system, gap junction blockers drastically reduced T cell activation as reflected by lower proliferation, CD69 expression, and IL-2 secretion. This lower T cell activation produced by gap junction blockers was not due to a lower expression of CD80, CD86, CD40, and MHC-II on DCs. Furthermore, gap junction blocker did not affect polyclonal activation of T cell induced with anti-CD3 plus anti-CD28 Abs in the absence of DCs. These results strongly suggest that functional gap junctions assemble at the interface between DCs and T cells during Ag presentation and that they play an essential role in T cell activation.
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63
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Albaghdadi H, Robinson N, Finlay B, Krishnan L, Sad S. Selectively reduced intracellular proliferation of Salmonella enterica serovar typhimurium within APCs limits antigen presentation and development of a rapid CD8 T cell response. THE JOURNAL OF IMMUNOLOGY 2009; 183:3778-87. [PMID: 19692639 DOI: 10.4049/jimmunol.0900843] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ag presentation to CD8(+) T cells commences immediately after infection, which facilitates their rapid expansion and control of pathogen. This paradigm is not followed during infection with virulent Salmonella enterica serovar Typhimurium (ST), an intracellular bacterium that causes mortality in susceptible C57BL/6J mice within 7 days and a chronic infection in resistant mice (129 x 1SvJ). Infection of mice with OVA-expressing ST results in the development of a CD8(+) T cell response that is detectable only after the second week of infection despite the early detectable bacterial burden. The mechanism behind the delayed CD8(+) T cell activation was evaluated, and it was found that dendritic cells/macrophages or mice infected with ST-OVA failed to present Ag to OVA-specific CD8(+) T cells. Lack of early Ag presentation was not rescued when mice or dendritic cells/macrophages were infected with an attenuated aroA mutant of ST or with mutants having defective Salmonella pathogenicity island I/II genes. Although extracellular ST proliferated extensively, the replication of ST was highly muted once inside macrophages. This muted intracellular proliferation of ST resulted in the generation of poor levels of intracellular Ag and peptide-MHC complex on the surface of dendritic cells. Additional experiments revealed that ST did not actively inhibit Ag presentation, rather it inhibited the uptake of another intracellular pathogen, Listeria monocytogenes, thereby causing inhibition of Ag presentation against L. monocytogenes. Taken together, this study reveals a dichotomy in the proliferation of ST and indicates that selectively reduced intracellular proliferation of virulent pathogens may be an important mechanism of immune evasion.
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Affiliation(s)
- Homam Albaghdadi
- National Research Council Institute for Biological Sciences, Ottawa, Ontario, Canada
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64
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Zenk SF, Jantsch J, Hensel M. Role of Salmonella enterica lipopolysaccharide in activation of dendritic cell functions and bacterial containment. THE JOURNAL OF IMMUNOLOGY 2009; 183:2697-707. [PMID: 19625639 DOI: 10.4049/jimmunol.0900937] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In contrast to nonpathogenic bacteria, the Gram-negative pathogen Salmonella enterica is not eradicated, but persists in murine dendritic cells (DC). The molecular basis of this phenotype is unknown. We set out to characterize bacterial and DC functions that are involved in Salmonella persistence. Our data prove that neither bacterial nor host cell de novo protein biosynthesis is required for Salmonella persistence in DC. We identified the Salmonella O-Ag of the LPS of Salmonella as an important factor for controlling the intracellular fate of Salmonella in DC. A Salmonella strain with entirely absent O-Ag showed an increased rate of uptake by DC, altered intracellular processing, and increased degradation, and also boosted the activation of immune functions of DC. These novel findings demonstrate that in addition to the multiple functions of the bacterial LPS in adaptation to the intestinal environment and protection against innate immune function, this molecule also has an important role in interaction of Salmonella with DC.
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Affiliation(s)
- Sebastian F Zenk
- Infektionsbiologische Abteilung, Universitätsklinikum Erlangen, Erlangen, Germany
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65
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Deatherage BL, Lara JC, Bergsbaken T, Rassoulian Barrett SL, Lara S, Cookson BT. Biogenesis of bacterial membrane vesicles. Mol Microbiol 2009; 72:1395-407. [PMID: 19432795 DOI: 10.1111/j.1365-2958.2009.06731.x] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Membrane vesicle (MV) release remains undefined, despite its conservation among replicating Gram-negative bacteria both in vitro and in vivo. Proteins identified in Salmonella MVs, derived from the envelope, control MV production via specific defined domains that promote outer membrane protein-peptidoglycan (OM-PG) and OM protein-inner membrane protein (OM-PG-IM) interactions within the envelope structure. Modulation of OM-PG and OM-PG-IM interactions along the cell body and at division septa, respectively, maintains membrane integrity while co-ordinating localized release of MVs with distinct size distribution and protein content. These data support a model of MV biogenesis, wherein bacterial growth and division invoke temporary, localized reductions in the density of OM-PG and OM-PG-IM associations within the envelope structure, thus releasing OM as MVs.
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Affiliation(s)
- Brooke L Deatherage
- Department of Microbiology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
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66
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Ramirez K, Capozzo AVE, Lloyd SA, Sztein MB, Nataro JP, Pasetti MF. Mucosally delivered Salmonella typhi expressing the Yersinia pestis F1 antigen elicits mucosal and systemic immunity early in life and primes the neonatal immune system for a vigorous anamnestic response to parenteral F1 boost. THE JOURNAL OF IMMUNOLOGY 2009; 182:1211-22. [PMID: 19124765 DOI: 10.4049/jimmunol.182.2.1211] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neonates respond poorly to conventional vaccines. This has been attributed, in part, to the immaturity of neonatal dendritic cells that lack full capacity for Ag presentation and T cell stimulation. We engineered an attenuated Salmonella Typhi strain to express and export the F1 Ag of Y. pestis (S. Typhi(F1)) and investigated its immunogenicity early in life using a heterologous prime-boost regimen. Newborn mice primed intranasally with a single dose of S. Typhi(F1) elicited mucosal Ab- and IFN-gamma-secreting cells 1 wk after immunization. They also developed a potent and fast anamnestic response to a subsequent parenteral boost with F1-alum, which surpassed those of mice primed and boosted with S. Typhi(F1) or F1-alum. Neonatal priming with S. Typhi(F1), as opposed to priming with F1-alum, resulted in a more balanced IgG2a/IgG1 profile, enhanced avidity maturation and stimulation of B memory cells, and strong Th1-type cell-mediated immunity. S. Typhi(F1) enhanced the activation and maturation of neonatal CD11c+ dendritic cells, shown by increased expression of CD80, CD86, CD40, and MHC-II cell surface markers and production of proinflammatory cytokines IL-12, TNF-alpha, IL-6, and MCP-1. S. Typhi(F1)-stimulated neonatal DC had improved capacity for Ag presentation and T cell stimulation in vitro and induced F1-specific CD4+ and CD8+ T cell responses when adoptively transferred to newborn mice. Mucosal immunization with S. Typhi expressing a foreign Ag effectively primes the neonatal immune system for potent, fast, and broader responses to a parenteral Ag boost. Such a strategy can prevent infectious diseases, including those considered biowarfare threats, early in life.
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Affiliation(s)
- Karina Ramirez
- Center for Vaccine Development, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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67
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Abstract
Over the last decade, significant advances have been made in the methodology for studying immune responses in vivo. It is now possible to follow almost every aspect of pathogen-specific immunity using in vivo models that incorporate physiological infectious doses and natural routes of infection. This new ability to study immunity in a relevant physiological context will greatly expand our understanding of the dynamic interplay between host and pathogen. Visualizing the resolution of primary infection and the development of long-term immunological memory should also aid the development of new vaccines and therapeutics for infectious diseases. In this review, we will describe the application of in vivo visualization technology to Salmonella infection, describe our current understanding of Salmonella-specific immunity, and discuss some unanswered questions that remain in this model.
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Affiliation(s)
- James J. Moon
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, MN, 55455
- Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, 55455
| | - Stephen J. McSorley
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, 55455
- Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, 55455
- Center for Infectious Diseases & Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, MN, 55455
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68
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Bakowski MA, Braun V, Brumell JH. Salmonella-Containing Vacuoles: Directing Traffic and Nesting to Grow. Traffic 2008; 9:2022-31. [DOI: 10.1111/j.1600-0854.2008.00827.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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69
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González PA, Prado CE, Leiva ED, Carreño LJ, Bueno SM, Riedel CA, Kalergis AM. Respiratory syncytial virus impairs T cell activation by preventing synapse assembly with dendritic cells. Proc Natl Acad Sci U S A 2008; 105:14999-5004. [PMID: 18818306 PMCID: PMC2567482 DOI: 10.1073/pnas.0802555105] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Indexed: 12/11/2022] Open
Abstract
Respiratory syncytial virus (RSV) infection is one of the leading causes of infant hospitalization and a major health and economic burden worldwide. Infection with this virus induces an exacerbated innate proinflammatory immune response characterized by abundant immune cell infiltration into the airways and lung tissue damage. RSV also impairs the induction of an adequate adaptive T cell immune response, which favors virus pathogenesis. Unfortunately, to date there are no efficient vaccines against this virus. Recent in vitro and in vivo studies suggest that RSV infection can prevent T cell activation, a phenomenon attributed in part to cytokines and chemokines secreted by RSV-infected cells. Efficient immunity against viruses is promoted by dendritic cells (DCs), professional antigen-presenting cells, that prime antigen-specific helper and cytotoxic T cells. Therefore, it would be to the advantage of RSV to impair DC function and prevent the induction of T cell immunity. Here, we show that, although RSV infection induces maturation of murine DCs, these cells are rendered unable to activate antigen-specific T cells. Inhibition of T cell activation by RSV was observed independently of the type of TCR ligand on the DC surface and applied to cognate-, allo-, and superantigen stimulation. As a result of exposure to RSV-infected DCs, T cells became unresponsive to subsequent TCR engagement. RSV-mediated impairment in T cell activation required DC-T cell contact and involved inhibition of immunological synapse assembly among these cells. Our data suggest that impairment of immunological synapse could contribute to RSV pathogenesis by evading adaptive immunity and reducing T cell-mediated virus clearance.
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Affiliation(s)
- Pablo A. González
- *Millennium Nucleus of Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, and
| | - Carolina E. Prado
- *Millennium Nucleus of Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, and
| | - Eduardo D. Leiva
- *Millennium Nucleus of Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, and
| | - Leandro J. Carreño
- *Millennium Nucleus of Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, and
| | - Susan M. Bueno
- *Millennium Nucleus of Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, and
| | - Claudia A. Riedel
- Laboratorio de Biología Celular y Farmacología, Departamento de Ciencias Biológicas, Universidad Andrés Bello, Santiago 8370146, Chile
| | - Alexis M. Kalergis
- *Millennium Nucleus of Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, and
- Departamento de Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago 8331010, Chile; and
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70
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Functional analysis of the Salmonella pathogenicity island 2-mediated inhibition of antigen presentation in dendritic cells. Infect Immun 2008; 76:4924-33. [PMID: 18765734 DOI: 10.1128/iai.00531-08] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Salmonella enterica is a facultative intracellular pathogen that is able to modify host cell functions by means of effector proteins translocated by the type III secretion system (T3SS) encoded by Salmonella Pathogenicity Island 2 (SPI2). The SPI2-T3SS is also active in Salmonella after uptake by murine bone marrow-derived dendritic cells (BM-DC). We have previously shown that intracellular Salmonella interfere with the ability of BM-DC to stimulate antigen-dependent T-cell proliferation in an SPI2-T3SS-dependent manner. We observed that Salmonella-mediated inhibition of antigen presentation could be restored by external addition of peptides on major histocompatibility complex class II (MHC-II). The processing of antigens in Salmonella-infected cells was not altered; however, the intracellular loading of peptides on MHC-II was reduced as a function of the SPI2-T3SS. We set out to identify the effector proteins of the SPI2-T3SS involved in inhibition of antigen presentation and demonstrated that effector proteins SifA, SspH2, SlrP, PipB2, and SopD2 were equally important for the interference with antigen presentation, whereas SseF and SseG contributed to a lesser extent to this phenotype. These observations indicate the presence of a host cell-specific virulence function of a novel subset of SPI2-effector proteins.
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71
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Mittal R, Prasadarao NV. Outer Membrane Protein A Expression inEscherichia coliK1 Is Required to Prevent the Maturation of Myeloid Dendritic Cells and the Induction of IL-10 and TGF-β. THE JOURNAL OF IMMUNOLOGY 2008; 181:2672-82. [DOI: 10.4049/jimmunol.181.4.2672] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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72
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Bueno SM, González PA, Carreño LJ, Tobar JA, Mora GC, Pereda CJ, Salazar-Onfray F, Kalergis AM. The capacity of Salmonella to survive inside dendritic cells and prevent antigen presentation to T cells is host specific. Immunology 2008; 124:522-33. [PMID: 18266715 DOI: 10.1111/j.1365-2567.2008.02805.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Infection with Salmonella enterica serovar Typhimurium (S. Typhimurium) causes a severe and lethal systemic disease in mice, characterized by poor activation of the adaptive immune response against Salmonella-derived antigens. Recently, we and others have reported that this feature relies on the ability of S. Typhimurium to survive within murine dendritic cells (DCs) and avoid the presentation of bacteria-derived antigens to T cells. In contrast, here we show that infection of murine DCs with either S. Typhi or S. Enteritidis, two serovars adapted to different hosts, leads to an efficient T-cell activation both in vitro and in vivo. Accordingly, S. Typhi and S. Enteritidis failed to replicate within murine DCs and were quickly degraded, allowing T-cell activation. In contrast, human DCs were found to be permissive for survival and proliferation of S. Typhi, but not for S. Typhimurium or S. Enteritidis. Our data suggest that Salmonella host restriction is characterized by the ability of these bacteria to survive within DCs and avoid activation of the adaptive immune response in their specific hosts.
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Affiliation(s)
- Susan M Bueno
- Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
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73
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Alaniz RC, Deatherage BL, Lara JC, Cookson BT. Membrane Vesicles Are Immunogenic Facsimiles ofSalmonella typhimuriumThat Potently Activate Dendritic Cells, Prime B and T Cell Responses, and Stimulate Protective Immunity In Vivo. THE JOURNAL OF IMMUNOLOGY 2007; 179:7692-701. [DOI: 10.4049/jimmunol.179.11.7692] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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74
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Chan SSM, Mastroeni P, McConnell I, Blacklaws BA. Salmonella infection of afferent lymph dendritic cells. J Leukoc Biol 2007; 83:272-9. [PMID: 17986631 DOI: 10.1189/jlb.0607401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The interactions of Salmonella enterica subspecies I serotype Abortusovis (S. Abortusovis) with ovine afferent lymph dendritic cells (ALDCs) were investigated for their ability to deliver Maedi visna virus (MVV) GAG p25 antigens to ALDCs purified from afferent lymph. Salmonellae were found to enter ALDC populations by a process of cell invasion, as confirmed by electron and confocal microscopy. This led to phenotypical changes in ALDC populations, as defined by CD1b and CD14 expression. No differences in the clearance kinetics of intracellular aroA-negative Salmonella from CD1b+ CD14lo and CD1b+ CD14(-) ALDC populations were noted over 72 h. ALDCs were also shown to present MVV GAG p25 expressed by aroA-negative S. Abortusovis to CD4+ T lymphocytes. Thus, the poor immune responses that Salmonella vaccines elicited in large animal models compared with mice are neither a result of an inability of Salmonella to infect large animal DCs nor an inability of these DCs to present delivered antigens. However, the low efficiency of infection of ALDC compared with macrophages or monocyte-derived DCs may account for the poor immune responses induced in large animal models.
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Affiliation(s)
- Simon S M Chan
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, UK
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75
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Abstract
Salmonella enterica is an important pathogen of animals and humans causing a variety of infectious diseases. The large number of cases of typhoid fever due to S. enterica serovar Typhi infections gives rise to the continuous need for improved vaccines against this life-threatening infection. However, S. enterica is also an interesting organism to act as a live attenuated carrier for the presentation of recombinant heterologous antigens. Comprehensive experimental studies have been performed and a detailed knowledge of the molecular mechanisms of important virulence factors is available. This allows the rationale design of improved Salmonella carrier strains and the development of novel strategies for the expression and presentation of recombinant antigens. Here, we review recent advances in generation of live attenuated Salmonella vaccines and discuss criteria for expression strategies of heterologous antigens by Salmonella carrier strains.
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76
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Herrada AA, Contreras FJ, Tobar JA, Pacheco R, Kalergis AM. Immune complex-induced enhancement of bacterial antigen presentation requires Fcgamma receptor III expression on dendritic cells. Proc Natl Acad Sci U S A 2007; 104:13402-7. [PMID: 17679697 PMCID: PMC1948949 DOI: 10.1073/pnas.0700999104] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Dendritic cells (DCs) are capable of initiating adaptive immune responses against infectious agents by presenting pathogen-derived antigens on MHC molecules to naïve T cells. Because of their key role in priming adaptive immunity, it is expected that interfering with DC function would be advantageous to the pathogen. We have previously shown that Salmonella enterica serovar Typhimurium (ST), is able to survive inside DCs and interfere with their function by avoiding activation of bacteria-specific T cells. In contrast, when ST is targeted to Fcgamma receptors on the DC surface, bacteria are degraded and their antigens presented to T cells. However, the specific Fcgamma receptor responsible of restoring presentation of antigens remains unknown. Here, we show that IgG-coated ST was targeted to lysosomes and degraded and its antigens presented on MHC molecules only when the low-affinity activating FcgammaRIII was expressed on DCs. FcgammaRIII-mediated enhancement of Ag presentation led to a robust activation of T cells specific for bacteria-expressed antigens. Laser confocal and electron microscopy analyses revealed that IgG-coated ST was rerouted to the lysosomal pathway through an FcgammaRIII-dependent mechanism. PI-3K activity was required for this process, because specific inhibitors promoted the survival of IgG-coated ST inside DCs and prevented DCs from activating bacteria-specific T cells. Our data suggest that the DC capacity to efficiently activate T cells upon capturing IgG-coated virulent bacteria is mediated by FcgammaRIII and requires PI-3K activity.
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Affiliation(s)
- Andrés A. Herrada
- *Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and
| | - Francisco J. Contreras
- *Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and
| | - Jaime A. Tobar
- *Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and
| | - Rodrigo Pacheco
- *Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and
| | - Alexis M. Kalergis
- *Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and
- Departamento de Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago E-8331010, Chile
- To whom correspondence should be addressed at:
Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda #340, Santiago E-8331010, Chile. E-mail:
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77
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Bueno SM, González PA, Schwebach JR, Kalergis AM. T cell immunity evasion by virulent Salmonella enterica. Immunol Lett 2007; 111:14-20. [PMID: 17583359 DOI: 10.1016/j.imlet.2007.05.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/13/2007] [Accepted: 05/11/2007] [Indexed: 12/30/2022]
Abstract
Salmonella enterica are Gram-negative bacteria that cause systemic disease in their specific hosts. One of the recently appreciated features of Salmonella pathogenicity is the capacity of the bacteria to impair host adaptive immunity by interfering with DC function and T cell activation. It is likely that this feature of virulent Salmonella is needed to promote systemic dissemination in the host. Recent studies have suggested explanations for some of the molecular mechanisms developed by virulent Salmonella to impair DC and T cell function. Several of these mechanisms require the expression of virulence genes encoded within Salmonella pathogenicity islands. Targeted deletion of these genes diminishes Salmonella pathogenicity and leads to efficient activation of T cells by Salmonella-infected DCs. In this review, recent data that support the subversion of DC function by Salmonella as a means to evade host adaptive immunity and cause systemic infection are discussed. These new findings suggest a new pathogenesis model with DCs as key targets for Salmonella virulence factors.
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Affiliation(s)
- Susan M Bueno
- Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Chile
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78
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Bohez L, Ducatelle R, Pasmans F, Haesebrouck F, Van Immerseel F. Long-term colonisation–inhibition studies to protect broilers against colonisation with Salmonella Enteritidis, using Salmonella Pathogenicity Island 1 and 2 mutants. Vaccine 2007; 25:4235-43. [PMID: 17408817 DOI: 10.1016/j.vaccine.2007.02.082] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 02/13/2007] [Accepted: 02/27/2007] [Indexed: 01/05/2023]
Abstract
Mutants in the Salmonella Pathogenicity Island 1 (hilA and sipA) and 2 (ssrA) were tested for their potential to induce protection against infection by homologous virulent Salmonella Enteritidis challenge strain, administered 24h later, in chickens. Although they colonised the internal organs to a significantly lower degree compared to the wild type strain, both a sipA and a ssrA mutant persistently colonised the gut when inoculated to newly hatched chicks. After inoculation of 1-day-old chicks with a sipA or a ssrA mutant and subsequent challenge with a wild type Salmonella Enteritidis 24h later, a significant degree of resistance against caecal and internal organ colonisation by the challenge strain was found. The protection lasted for the full 6 weeks of study, but due to their persistence, the sipA and ssrA mutants are not useful to induce broiler protection. After inoculation of newly hatched chicks with a hilA mutant no positive cloacal swabs could be detected anymore at 4 weeks post-inoculation and the hilA mutant was almost completely cleared from the gut. When newly hatched chicks were inoculated with a hilA mutant and challenged 24h later, the excretion of the virulent challenge strain was significantly reduced and the intestinal colonisation of the challenge strain was inhibited to a high level until the age of 9 days. Moreover, the hilA mutant exerted a significant profound inhibition of internal organ colonisation by the virulent challenge strain throughout the study period. The approach of vaccination with a hilA mutant strain can be a valuable basis for development of vaccine strains for broilers protection.
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Affiliation(s)
- Lotte Bohez
- Department of Pathology, Bacteriology and Avian Diseases, Research Group Veterinary Public Health and Zoonoses, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
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