1
|
Xi Y, Li X, Liu L, Xiu F, Yi X, Chen H, You X. Sneaky tactics: Ingenious immune evasion mechanisms of Bartonella. Virulence 2024; 15:2322961. [PMID: 38443331 PMCID: PMC10936683 DOI: 10.1080/21505594.2024.2322961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 02/20/2024] [Indexed: 03/07/2024] Open
Abstract
Gram-negative Bartonella species are facultative intracellular bacteria that can survive in the harsh intracellular milieu of host cells. They have evolved strategies to evade detection and degradation by the host immune system, which ensures their proliferation in the host. Following infection, Bartonella alters the initial immunogenic surface-exposed proteins to evade immune recognition via antigen or phase variation. The diverse lipopolysaccharide structures of certain Bartonella species allow them to escape recognition by the host pattern recognition receptors. Additionally, the survival of mature erythrocytes and their resistance to lysosomal fusion further complicate the immune clearance of this species. Certain Bartonella species also evade immune attacks by producing biofilms and anti-inflammatory cytokines and decreasing endothelial cell apoptosis. Overall, these factors create a challenging landscape for the host immune system to rapidly and effectively eradicate the Bartonella species, thereby facilitating the persistence of Bartonella infections and creating a substantial obstacle for therapeutic interventions. This review focuses on the effects of three human-specific Bartonella species, particularly their mechanisms of host invasion and immune escape, to gain new perspectives in the development of effective diagnostic tools, prophylactic measures, and treatment options for Bartonella infections.
Collapse
Affiliation(s)
- Yixuan Xi
- Institute of Pathogenic Biology, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, China
| | - Xinru Li
- Institute of Pathogenic Biology, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, China
| | - Lu Liu
- Institute of Pathogenic Biology, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, China
| | - Feichen Xiu
- Institute of Pathogenic Biology, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, China
| | - Xinchao Yi
- Institute of Pathogenic Biology, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, China
| | - Hongliang Chen
- Chenzhou NO.1 People’s Hospital, The Affiliated Chenzhou Hospital, Hengyang Medical College, University of South China, ChenZhou, China
| | - Xiaoxing You
- Institute of Pathogenic Biology, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, China
| |
Collapse
|
2
|
Kumadaki K, Suzuki N, Tatematsu K, Doi Y, Tsukamoto K. Comparison of Biological Activities of BafA Family Autotransporters within Bartonella Species Derived from Cats and Rodents. Infect Immun 2023; 91:e0018622. [PMID: 36744895 PMCID: PMC10016083 DOI: 10.1128/iai.00186-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bartonella species are hemotropic, facultative intracellular bacteria, some of which cause zoonoses, that are widely disseminated among many mammals, including humans. During infection in humans, vascular endothelial cells play a crucial role as a replicative niche for Bartonella, and some are capable of promoting vascular proliferation. Along with well-studied pathogenic factors such as a trimeric autotransporter adhesin BadA or VirB/D4 type IV secretion system, bacteria-secreted protein BafA is also involved in Bartonella-induced vasoproliferation. Genes encoding BafA orthologs have been found in the genomes of most Bartonella species, but their functionality remains unclear. In this study, we focused on three cat-derived zoonotic species (B. henselae, B. koehlerae, and B. clarridgeiae) and two rodent-derived species (B. grahamii and B. doshiae) and compared the activity of BafA derived from each species. Recombinant BafA proteins of B. henselae, B. koehlerae, B. clarridgeiae, and B. grahamii, species that also cause human disease, induced cell proliferation and tube formation in cultured endothelial cells, while BafA derived from B. doshiae, a species that is rarely found in humans, showed neither activity. Additionally, treatment of cells with these BafA proteins increased phosphorylation of both vascular endothelial growth factor receptor 2 and extracellular signal-regulated kinase 1/2, with the exception of B. doshiae BafA. Differential bafA mRNA expression and BafA secretion among the species likely contributed to the differences in the cell proliferation phenotype of the bacteria-infected cells. These findings suggest that the biological activity of BafA may be involved in the infectivity or pathogenicity of Bartonella species in humans.
Collapse
Affiliation(s)
- Kayo Kumadaki
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Natsumi Suzuki
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Kaoru Tatematsu
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Yohei Doi
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
- Department of Infectious Diseases, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Kentaro Tsukamoto
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| |
Collapse
|
3
|
Suzuki N, Kumadaki K, Tatematsu K, Doi Y, Tsukamoto K. The autotransporter BafA contributes to the proangiogenic potential of Bartonella elizabethae. Microbiol Immunol 2023; 67:248-257. [PMID: 36810719 DOI: 10.1111/1348-0421.13057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/14/2023] [Accepted: 02/19/2023] [Indexed: 02/24/2023]
Abstract
Bartonella elizabethae is a rat-borne zoonotic bacterium that causes human infectious endocarditis or neuroretinitis. Recently, a case of bacillary angiomatosis (BA) resulting from this organism was reported, leading to speculation that B. elizabethae may also trigger vasoproliferation. However, there are no reports of B. elizabethae promoting human vascular endothelial cell (EC) proliferation or angiogenesis, and to date, the effects of this bacterium on ECs are unknown. We recently identified a proangiogenic autotransporter, BafA, secreted from B. henselae and B. quintana, which are recognized as Bartonella spp. responsible for BA in humans. Here, we hypothesized that B. elizabethae also harbored a functional bafA gene and examined the proangiogenic activity of recombinant B. elizabethae-derived BafA. The bafA gene of B. elizabethae, which was found to share a 51.1% amino acid sequence identity with BafA of B. henselae and 52.5% with that of B. quintana in the passenger domain, was located in a syntenic region of the genome. The recombinant protein of the N-terminal passenger domain of B. elizabethae-BafA facilitated EC proliferation and capillary structure formation. Furthermore, it upregulated the receptor signaling pathway of vascular endothelial growth factor, as observed in B. henselae-BafA. Taken together, B. elizabethae-derived BafA stimulates human EC proliferation and may contribute to the proangiogenic potential of this bacterium. So far, functional bafA genes have been found in all BA-causing Bartonella spp., supporting the key role BafA may play in BA pathogenesis.
Collapse
Affiliation(s)
- Natsumi Suzuki
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Japan
| | - Kayo Kumadaki
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Japan
| | - Kaoru Tatematsu
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Japan
| | - Yohei Doi
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Japan.,Department of Infectious Diseases, Fujita Health University School of Medicine, Toyoake, Japan.,Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Kentaro Tsukamoto
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Japan
| |
Collapse
|
4
|
The Bartonella autotransporter BafA activates the host VEGF pathway to drive angiogenesis. Nat Commun 2020; 11:3571. [PMID: 32678094 PMCID: PMC7366657 DOI: 10.1038/s41467-020-17391-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/26/2020] [Indexed: 12/29/2022] Open
Abstract
Pathogenic bacteria of the genus Bartonella can induce vasoproliferative lesions during infection. The underlying mechanisms are unclear, but involve secretion of an unidentified mitogenic factor. Here, we use functional transposon-mutant screening in Bartonella henselae to identify such factor as a pro-angiogenic autotransporter, called BafA. The passenger domain of BafA induces cell proliferation, tube formation and sprouting of microvessels, and drives angiogenesis in mice. BafA interacts with vascular endothelial growth factor (VEGF) receptor-2 and activates the downstream signaling pathway, suggesting that BafA functions as a VEGF analog. A BafA homolog from a related pathogen, Bartonella quintana, is also functional. Our work unveils the mechanistic basis of vasoproliferative lesions observed in bartonellosis, and we propose BafA as a key pathogenic factor contributing to bacterial spread and host adaptation. Pathogenic bacteria of the genus Bartonella can induce vasoproliferative lesions during infection. Here, Tsukamoto et al. show that this effect is caused by a secreted protein that induces cell proliferation and angiogenesis by acting as an analog of the host’s vascular endothelial growth factor (VEGF).
Collapse
|
5
|
Abstract
Since the reclassification of the genus Bartonella in 1993, the number of species has grown from 1 to 45 currently designated members. Likewise, the association of different Bartonella species with human disease continues to grow, as does the range of clinical presentations associated with these bacteria. Among these, blood-culture-negative endocarditis stands out as a common, often undiagnosed, clinical presentation of infection with several different Bartonella species. The limitations of laboratory tests resulting in this underdiagnosis of Bartonella endocarditis are discussed. The varied clinical picture of Bartonella infection and a review of clinical aspects of endocarditis caused by Bartonella are presented. We also summarize the current knowledge of the molecular basis of Bartonella pathogenesis, focusing on surface adhesins in the two Bartonella species that most commonly cause endocarditis, B. henselae and B. quintana. We discuss evidence that surface adhesins are important factors for autoaggregation and biofilm formation by Bartonella species. Finally, we propose that biofilm formation is a critical step in the formation of vegetative masses during Bartonella-mediated endocarditis and represents a potential reservoir for persistence by these bacteria.
Collapse
|
6
|
Tevis KM, Colson YL, Grinstaff MW. Embedded Spheroids as Models of the Cancer Microenvironment. ADVANCED BIOSYSTEMS 2017; 1:1700083. [PMID: 30221187 PMCID: PMC6135264 DOI: 10.1002/adbi.201700083] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To more accurately study the complex mechanisms behind cancer invasion, progression, and response to treatment, researchers require models that replicate both the multicellular nature and 3D stromal environment present in an in vivo tumor. Multicellular aggregates (i.e., spheroids) embedded in an extracellular matrix mimic are a prevalent model. Recently, quantitative metrics that fully utilize the capability of spheroids are described along with conventional experiments, such as invasion into a matrix, to provide additional details and insights into the underlying cancer biology. The review begins with a discussion of the salient features of the tumor microenvironment, introduces the early work on non-embedded spheroids as tumor models, and then concentrates on the successes achieved with the study of embedded spheroids. Examples of studies include cell movement, drug response, tumor cellular heterogeneity, stromal effects, and cancer progression. Additionally, new methodologies and those borrowed from other research fields (e.g., vascularization and tissue engineering) are highlighted that expand the capability of spheroids to aid future users in designing their cancer-related experiments. The convergence of spheroid research among the various fields catalyzes new applications and leads to a natural synergy. Finally, the review concludes with a reflection and future perspectives for cancer spheroid research.
Collapse
Affiliation(s)
- Kristie M. Tevis
- Departments of Biomedical Engineering, Chemistry, and Medicine, Metcalf Center for Science and Engineering, Boston University, Boston, MA 02215
| | - Yolonda L. Colson
- Division of Thoracic Surgery, Department of Surgery, Brigham and Women’s Hospital, Boston, MA 02215
| | - Mark W. Grinstaff
- Departments of Biomedical Engineering, Chemistry, and Medicine, Metcalf Center for Science and Engineering, Boston University, Boston, MA 02215
| |
Collapse
|
7
|
Minnick MF, Anderson BE, Lima A, Battisti JM, Lawyer PG, Birtles RJ. Oroya fever and verruga peruana: bartonelloses unique to South America. PLoS Negl Trop Dis 2014; 8:e2919. [PMID: 25032975 PMCID: PMC4102455 DOI: 10.1371/journal.pntd.0002919] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Bartonella bacilliformis is the bacterial agent of Carrión's disease and is presumed to be transmitted between humans by phlebotomine sand flies. Carrión's disease is endemic to high-altitude valleys of the South American Andes, and the first reported outbreak (1871) resulted in over 4,000 casualties. Since then, numerous outbreaks have been documented in endemic regions, and over the last two decades, outbreaks have occurred at atypical elevations, strongly suggesting that the area of endemicity is expanding. Approximately 1.7 million South Americans are estimated to be at risk in an area covering roughly 145,000 km2 of Ecuador, Colombia, and Peru. Although disease manifestations vary, two disparate syndromes can occur independently or sequentially. The first, Oroya fever, occurs approximately 60 days following the bite of an infected sand fly, in which infection of nearly all erythrocytes results in an acute hemolytic anemia with attendant symptoms of fever, jaundice, and myalgia. This phase of Carrión's disease often includes secondary infections and is fatal in up to 88% of patients without antimicrobial intervention. The second syndrome, referred to as verruga peruana, describes the endothelial cell-derived, blood-filled tumors that develop on the surface of the skin. Verrugae are rarely fatal, but can bleed and scar the patient. Moreover, these persistently infected humans provide a reservoir for infecting sand flies and thus maintaining B. bacilliformis in nature. Here, we discuss the current state of knowledge regarding this life-threatening, neglected bacterial pathogen and review its host-cell parasitism, molecular pathogenesis, phylogeny, sand fly vectors, diagnostics, and prospects for control.
Collapse
Affiliation(s)
- Michael F. Minnick
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Burt E. Anderson
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Amorce Lima
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - James M. Battisti
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Phillip G. Lawyer
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Richard J. Birtles
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
| |
Collapse
|
8
|
Ben-Tekaya H, Gorvel JP, Dehio C. Bartonella and Brucella--weapons and strategies for stealth attack. Cold Spring Harb Perspect Med 2013; 3:3/8/a010231. [PMID: 23906880 DOI: 10.1101/cshperspect.a010231] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Bartonella spp. and Brucella spp. are closely related α-proteobacterial pathogens that by distinct stealth-attack strategies cause chronic infections in mammals including humans. Human infections manifest by a broad spectrum of clinical symptoms, ranging from mild to fatal disease. Both pathogens establish intracellular replication niches and subvert diverse pathways of the host's immune system. Several virulence factors allow them to adhere to, invade, proliferate, and persist within various host-cell types. In particular, type IV secretion systems (T4SS) represent essential virulence factors that transfer effector proteins tailored to recruit host components and modulate cellular processes to the benefit of the bacterial intruders. This article puts the remarkable features of these two pathogens into perspective, highlighting the mechanisms they use to hijack signaling and trafficking pathways of the host as the basis for their stealthy infection strategies.
Collapse
Affiliation(s)
- Houchaima Ben-Tekaya
- Focal Area Infection Biology, Biozentrum, University of Basel, 4052 Basel, Switzerland
| | | | | |
Collapse
|
9
|
Lu YY, Franz B, Truttmann MC, Riess T, Gay-Fraret J, Faustmann M, Kempf VAJ, Dehio C. Bartonella henselae trimeric autotransporter adhesin BadA expression interferes with effector translocation by the VirB/D4 type IV secretion system. Cell Microbiol 2012; 15:759-78. [PMID: 23163798 DOI: 10.1111/cmi.12070] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 11/07/2012] [Accepted: 11/09/2012] [Indexed: 11/30/2022]
Abstract
The Gram-negative, zoonotic pathogen Bartonella henselae is the aetiological agent of cat scratch disease, bacillary angiomatosis and peliosis hepatis in humans. Two pathogenicity factors of B. henselae - each displaying multiple functions in host cell interaction - have been characterized in greater detail: the trimeric autotransporter Bartonella adhesin A (BadA) and the type IV secretion system VirB/D4 (VirB/D4 T4SS). BadA mediates, e.g. binding to fibronectin (Fn), adherence to endothelial cells (ECs) and secretion of vascular endothelial growth factor (VEGF). VirB/D4 translocates several Bartonella effector proteins (Beps) into the cytoplasm of infected ECs, resulting, e.g. in uptake of bacterial aggregates via the invasome structure, inhibition of apoptosis and activation of a proangiogenic phenotype. Despite this knowledge of the individual activities of BadA or VirB/D4 it is unknown whether these major virulence factors affect each other in their specific activities. In this study, expression and function of BadA and VirB/D4 were analysed in a variety of clinical B. henselae isolates. Data revealed that most isolates have lost expression of either BadA or VirB/D4 during in vitro passages. However, the phenotypic effects of coexpression of both virulence factors was studied in one clinical isolate that was found to stably coexpress BadA and VirB/D4, as well as by ectopic expression of BadA in a strain expressing VirB/D4 but not BadA. BadA, which forms a dense layer on the bacterial surface, negatively affected VirB/D4-dependent Bep translocation and invasome formation by likely preventing close contact between the bacterial cell envelope and the host cell membrane. In contrast, BadA-dependent Fn binding, adhesion to ECs and VEGF secretion were not affected by a functional VirB/D4 T4SS. The obtained data imply that the essential virulence factors BadA and VirB/D4 are likely differentially expressed during different stages of the infection cycle of Bartonella.
Collapse
Affiliation(s)
- Yun-Yueh Lu
- Focal Area Infection Biology, Biozentrum of the University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Paziewska A, Siński E, Harris PD. Recombination, diversity and allele sharing of infectivity proteins between Bartonella species from rodents. MICROBIAL ECOLOGY 2012; 64:525-536. [PMID: 22419104 PMCID: PMC3391547 DOI: 10.1007/s00248-012-0033-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 02/23/2012] [Indexed: 05/31/2023]
Abstract
The alpha-Proteobacterium Bartonella is a common parasite of voles and mice, giving rise to short-lived (4 weeks to 2 months) infections. Here, we report high sequence diversity in genes of the VirB/VirD type IV secretion system (T4SS), amongst Bartonella from natural rodent populations in NE Poland. The VirB5 protein is predicted to consist of three conserved alpha helices separated by loops of variable length which include numerous indels. The C-terminal domain includes repeat stretches of KEK residues, reflecting underlying homopolymeric stretches of adenine residues. A total of 16 variants of VirB5, associated with host identity, but not bacterial taxon, were identified from 22 Bartonella isolates. One was clearly a recombinant from two others, another included an insertion of two KEK repeats. The virB5 gene appears to evolve via both mutation and recombination, as well as slippage mediated insertion/deletion events. The recombinational units are thought to be relatively short, as there was no evidence of linkage disequilibrium between virB5 and the bepA locus only 5.5 kb distant. The diversity of virB5 is assumed to be related to immunological role of this protein in Bartonella infections; diversity of virB5 may assist persistence of Bartonella in the rodent population, despite the relatively short (3-4 weeks) duration of individual infections. It is clear from the distribution of virB5 and bepA alleles that recombination within and between clades is widespread, and frequently crosses the boundaries of conventionally recognised Bartonella species.
Collapse
Affiliation(s)
- Anna Paziewska
- National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172, Blindern, Oslo, Norway.
| | | | | |
Collapse
|
11
|
Voth DE, Broederdorf LJ, Graham JG. Bacterial Type IV secretion systems: versatile virulence machines. Future Microbiol 2012; 7:241-57. [PMID: 22324993 DOI: 10.2217/fmb.11.150] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Many bacterial pathogens employ multicomponent protein complexes to deliver macromolecules directly into their eukaryotic host cell to promote infection. Some Gram-negative pathogens use a versatile Type IV secretion system (T4SS) that can translocate DNA or proteins into host cells. T4SSs represent major bacterial virulence determinants and have recently been the focus of intense research efforts designed to better understand and combat infectious diseases. Interestingly, although the two major classes of T4SSs function in a similar manner to secrete proteins, the translocated 'effectors' vary substantially from one organism to another. In fact, differing effector repertoires likely contribute to organism-specific host cell interactions and disease outcomes. In this review, we discuss the current state of T4SS research, with an emphasis on intracellular bacterial pathogens of humans and the diverse array of translocated effectors used to manipulate host cells.
Collapse
Affiliation(s)
- Daniel E Voth
- Department of Microbiology & Immunology, University of Arkansas for Medical Sciences, 4301 W. Markham, Little Rock, AR 72205, USA.
| | | | | |
Collapse
|
12
|
Deng H, Le Rhun D, Buffet JPR, Cotté V, Read A, Birtles RJ, Vayssier-Taussat M. Strategies of exploitation of mammalian reservoirs by Bartonella species. Vet Res 2012; 43:15. [PMID: 22369683 PMCID: PMC3430587 DOI: 10.1186/1297-9716-43-15] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 01/17/2012] [Indexed: 11/16/2022] Open
Abstract
Numerous mammal species, including domestic and wild animals such as ruminants, dogs, cats and rodents, as well as humans, serve as reservoir hosts for various Bartonella species. Some of those species that exploit non-human mammals as reservoir hosts have zoonotic potential. Our understanding of interactions between bartonellae and reservoir hosts has been greatly improved by the development of animal models for infection and the use of molecular tools allowing large scale mutagenesis of Bartonella species. By reviewing and combining the results of these and other approaches we can obtain a comprehensive insight into the molecular interactions that underlie the exploitation of reservoir hosts by Bartonella species, particularly the well-studied interactions with vascular endothelial cells and erythrocytes.
Collapse
Affiliation(s)
- Hongkuan Deng
- USC INRA Bartonella et Tiques, ANSES, 23 Avenue du Général de Gaulle, 94700, Maisons-Alfort, France.
| | | | | | | | | | | | | |
Collapse
|
13
|
Pulliainen AT, Dehio C. Persistence of Bartonella spp. stealth pathogens: from subclinical infections to vasoproliferative tumor formation. FEMS Microbiol Rev 2012; 36:563-99. [PMID: 22229763 DOI: 10.1111/j.1574-6976.2012.00324.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 12/13/2011] [Accepted: 12/13/2011] [Indexed: 01/11/2023] Open
Abstract
Bartonella spp. are facultative intracellular bacteria that typically cause a long-lasting intraerythrocytic bacteremia in their mammalian reservoir hosts, thereby favoring transmission by blood-sucking arthropods. In most cases, natural reservoir host infections are subclinical and the relapsing intraerythrocytic bacteremia may last weeks, months, or even years. In this review, we will follow the infection cycle of Bartonella spp. in a reservoir host, which typically starts with an intradermal inoculation of bacteria that are superficially scratched into the skin from arthropod feces and terminates with the pathogen exit by the blood-sucking arthropod. The current knowledge of bacterial countermeasures against mammalian immune response will be presented for each critical step of the pathogenesis. The prevailing models of the still-enigmatic primary niche and the anatomical location where bacteria reside, persist, and are periodically seeded into the bloodstream to cause the typical relapsing Bartonella spp. bacteremia will also be critically discussed. The review will end up with a discussion of the ability of Bartonella spp., namely Bartonella henselae, Bartonella quintana, and Bartonella bacilliformis, to induce tumor-like vascular deformations in humans having compromised immune response such as in patients with AIDS.
Collapse
|
14
|
Abstract
Bartonella spp. are facultative intracellular pathogens that employ a unique stealth infection strategy comprising immune evasion and modulation, intimate interaction with nucleated cells, and intraerythrocytic persistence. Infections with Bartonella are ubiquitous among mammals, and many species can infect humans either as their natural host or incidentally as zoonotic pathogens. Upon inoculation into a naive host, the bartonellae first colonize a primary niche that is widely accepted to involve the manipulation of nucleated host cells, e.g., in the microvasculature. Consistently, in vitro research showed that Bartonella harbors an ample arsenal of virulence factors to modulate the response of such cells, gain entrance, and establish an intracellular niche. Subsequently, the bacteria are seeded into the bloodstream where they invade erythrocytes and give rise to a typically asymptomatic intraerythrocytic bacteremia. While this course of infection is characteristic for natural hosts, zoonotic infections or the infection of immunocompromised patients may alter the path of Bartonella and result in considerable morbidity. In this review we compile current knowledge on the molecular processes underlying both the infection strategy and pathogenesis of Bartonella and discuss their connection to the clinical presentation of human patients, which ranges from minor complaints to life-threatening disease.
Collapse
Affiliation(s)
- Alexander Harms
- Focal Area Infection Biology, Biozentrum, University of Basel, Switzerland
| | | |
Collapse
|
15
|
Truttmann MC, Misselwitz B, Huser S, Hardt WD, Critchley DR, Dehio C. Bartonella henselae engages inside-out and outside-in signaling by integrin β1 and talin1 during invasome-mediated bacterial uptake. J Cell Sci 2011; 124:3591-602. [PMID: 22045736 DOI: 10.1242/jcs.084459] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The VirB/D4 type IV secretion system (T4SS) of the bacterial pathogen Bartonella henselae (Bhe) translocates seven effector proteins (BepA-BepG) into human cells that subvert host cellular functions. Two redundant pathways dependent on BepG or the combination of BepC and BepF trigger the formation of a bacterial uptake structure termed the invasome. Invasome formation is a multi-step process consisting of bacterial adherence, effector translocation, aggregation of bacteria on the cell surface and engulfment, and eventually, complete internalization of the bacterial aggregate occurs in an F-actin-dependent manner. In the present study, we show that Bhe-triggered invasome formation depends on integrin-β1-mediated signaling cascades that enable assembly of the F-actin invasome structure. We demonstrate that Bhe interacts with integrin β1 in a fibronectin- and VirB/D4 T4SS-independent manner and that activated integrin β1 is essential for both effector translocation and the actin rearrangements leading to invasome formation. Furthermore, we show that talin1, but not talin2, is required for inside-out activation of integrin β1 during invasome formation. Finally, integrin-β1-mediated outside-in signaling by FAK, Src, paxillin and vinculin is necessary for invasome formation. This is the first example of a bacterial entry process that fully exploits the bi-directional signaling capacity of integrin receptors in a talin1-specific manner.
Collapse
Affiliation(s)
- Matthias C Truttmann
- Focal Area Infection Biology, Biozentrum of the University of Basel, Klingelbergstr. 70, CH-4056 Basel, Switzerland
| | | | | | | | | | | |
Collapse
|
16
|
Truttmann MC, Guye P, Dehio C. BID-F1 and BID-F2 domains of Bartonella henselae effector protein BepF trigger together with BepC the formation of invasome structures. PLoS One 2011; 6:e25106. [PMID: 22043280 PMCID: PMC3197191 DOI: 10.1371/journal.pone.0025106] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 08/24/2011] [Indexed: 11/18/2022] Open
Abstract
The gram-negative, zoonotic pathogen Bartonella henselae (Bhe) translocates seven distinct Bartonella effector proteins (Beps) via the VirB/VirD4 type IV secretion system (T4SS) into human cells, thereby interfering with host cell signaling [1], [2]. In particular, the effector protein BepG alone or the combination of effector proteins BepC and BepF trigger massive F-actin rearrangements that lead to the establishment of invasome structures eventually resulting in the internalization of entire Bhe aggregates [2], [3]. In this report, we investigate the molecular function of the effector protein BepF in the eukaryotic host cell. We show that the N-terminal [E/T]PLYAT tyrosine phosphorylation motifs of BepF get phosphorylated upon translocation but do not contribute to invasome-mediated Bhe uptake. In contrast, we found that two of the three BID domains of BepF are capable to trigger invasome formation together with BepC, while a mutation of the WxxxE motif of the BID-F1 domain inhibited its ability to contribute to the formation of invasome structures. Next, we show that BepF function during invasome formation can be replaced by the over-expression of constitutive-active Rho GTPases Rac1 or Cdc42. Finally we demonstrate that BID-F1 and BID-F2 domains promote the formation of filopodia-like extensions in NIH 3T3 and HeLa cells as well as membrane protrusions in HeLa cells, suggesting a role for BepF in Rac1 and Cdc42 activation during the process of invasome formation.
Collapse
Affiliation(s)
- Matthias C. Truttmann
- Focal Area Infection Biology, Biozentrum of the University of Basel, Basel, Switzerland
| | - Patrick Guye
- Focal Area Infection Biology, Biozentrum of the University of Basel, Basel, Switzerland
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, United States of America
| | - Christoph Dehio
- Focal Area Infection Biology, Biozentrum of the University of Basel, Basel, Switzerland
- * E-mail:
| |
Collapse
|
17
|
Berrich M, Kieda C, Grillon C, Monteil M, Lamerant N, Gavard J, Boulouis HJ, Haddad N. Differential effects of Bartonella henselae on human and feline macro- and micro-vascular endothelial cells. PLoS One 2011; 6:e20204. [PMID: 21637717 PMCID: PMC3103534 DOI: 10.1371/journal.pone.0020204] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 04/26/2011] [Indexed: 01/03/2023] Open
Abstract
Bartonella henselae, a zoonotic agent, induces tumors of endothelial cells (ECs), namely bacillary angiomatosis and peliosis in immunosuppressed humans but not in cats. In vitro studies on ECs represent to date the only way to explore the interactions between Bartonella henselae and vascular endothelium. However, no comparative study of the interactions between Bartonella henselae and human (incidental host) ECs vs feline (reservoir host) ECs has been carried out because of the absence of any available feline endothelial cell lines.To this purpose, we have developed nine feline EC lines which allowed comparing the effects of Bartonella strains on human and feline micro-vascular ECs representative of the infection development sites such as skin, versus macro-vascular ECs, such as umbilical vein.Our model revealed intrinsic differences between human (Human Skin Microvascular ECs -HSkMEC and Human Umbilical Vein ECs - iHUVEC) and feline ECs susceptibility to Bartonella henselae infection.While no effect was observed on the feline ECs upon Bartonella henselae infection, the human ones displayed accelerated angiogenesis and wound healing.Noticeable differences were demonstrated between human micro- and macro-vasculature derived ECs both in terms of pseudo-tube formation and healing. Interestingly, Bartonella henselae effects on human ECs were also elicited by soluble factors.Neither Bartonella henselae-infected Human Skin Microvascular ECs clinically involved in bacillary angiomatosis, nor feline ECs increased cAMP production, as opposed to HUVEC.Bartonella henselae could stimulate the activation of Vascular Endothelial Growth Factor Receptor-2 (VEGFR-2) in homologous cellular systems and trigger VEGF production by HSkMECs only, but not iHUVEC or any feline ECs tested.These results may explain the decreased pathogenic potential of Bartonella henselae infection for cats as compared to humans and strongly suggest that an autocrine secretion of VEGF by human skin endothelial cells might induce their growth and ultimately lead to bacillary angiomatosis formation.
Collapse
Affiliation(s)
- Moez Berrich
- Unité Mixte de Recherche de Biologie Moléculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, Université Paris-Est, Maisons-Alfort, France
| | - Claudine Kieda
- Unité Propre de Recherche 4301, Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique, Orléans, France
| | - Catherine Grillon
- Unité Propre de Recherche 4301, Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique, Orléans, France
| | - Martine Monteil
- Unité Mixte de Recherche de Biologie Moléculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, Université Paris-Est, Maisons-Alfort, France
| | - Nathalie Lamerant
- Unité Propre de Recherche 4301, Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique, Orléans, France
| | - Julie Gavard
- Unité 1016 Inserm, Institut Cochin, CNRS, Université Paris Descartes, Paris, France
| | - Henri Jean Boulouis
- Unité Mixte de Recherche de Biologie Moléculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, Université Paris-Est, Maisons-Alfort, France
| | - Nadia Haddad
- Unité Mixte de Recherche de Biologie Moléculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, Université Paris-Est, Maisons-Alfort, France
| |
Collapse
|
18
|
Franz B, Kempf VAJ. Adhesion and host cell modulation: critical pathogenicity determinants of Bartonella henselae. Parasit Vectors 2011; 4:54. [PMID: 21489243 PMCID: PMC3083372 DOI: 10.1186/1756-3305-4-54] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 04/13/2011] [Indexed: 12/27/2022] Open
Abstract
Bartonella henselae, the agent of cat scratch disease and the vasculoproliferative disorders bacillary angiomatosis and peliosis hepatis, contains to date two groups of described pathogenicity factors: adhesins and type IV secretion systems. Bartonella adhesin A (BadA), the Trw system and possibly filamentous hemagglutinin act as promiscous or specific adhesins, whereas the virulence locus (Vir)B/VirD4 type IV secretion system modulates a variety of host cell functions. BadA mediates bacterial adherence to endothelial cells and extracellular matrix proteins and triggers the induction of angiogenic gene programming. The VirB/VirD4 type IV secretion system is responsible for, e.g., inhibition of host cell apoptosis, bacterial persistence in erythrocytes, and endothelial sprouting. The Trw-conjugation system of Bartonella spp. mediates host-specific adherence to erythrocytes. Filamentous hemagglutinins represent additional potential pathogenicity factors which are not yet characterized. The exact molecular functions of these pathogenicity factors and their contribution to an orchestral interplay need to be analyzed to understand B. henselae pathogenicity in detail.
Collapse
Affiliation(s)
- Bettina Franz
- University hospital of the Johann Wolfgang Goethe-University, Institute for Medical Microbiology and Infection Control, Paul-Ehrlich-Strasse 40, Frankfurt am Main, D-60596, Germany
| | - Volkhard AJ Kempf
- University hospital of the Johann Wolfgang Goethe-University, Institute for Medical Microbiology and Infection Control, Paul-Ehrlich-Strasse 40, Frankfurt am Main, D-60596, Germany
| |
Collapse
|
19
|
Engel P, Salzburger W, Liesch M, Chang CC, Maruyama S, Lanz C, Calteau A, Lajus A, Médigue C, Schuster SC, Dehio C. Parallel evolution of a type IV secretion system in radiating lineages of the host-restricted bacterial pathogen Bartonella. PLoS Genet 2011; 7:e1001296. [PMID: 21347280 PMCID: PMC3037411 DOI: 10.1371/journal.pgen.1001296] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 01/07/2011] [Indexed: 12/03/2022] Open
Abstract
Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered to be responsible for the genesis of a great portion of the diversity of life. Bacteria have evolved enormous biological diversity by exploiting an exceptional range of environments, yet diversification of bacteria via adaptive radiation has been documented in a few cases only and the underlying molecular mechanisms are largely unknown. Here we show a compelling example of adaptive radiation in pathogenic bacteria and reveal their genetic basis. Our evolutionary genomic analyses of the α-proteobacterial genus Bartonella uncover two parallel adaptive radiations within these host-restricted mammalian pathogens. We identify a horizontally-acquired protein secretion system, which has evolved to target specific bacterial effector proteins into host cells as the evolutionary key innovation triggering these parallel adaptive radiations. We show that the functional versatility and adaptive potential of the VirB type IV secretion system (T4SS), and thereby translocated Bartonella effector proteins (Beps), evolved in parallel in the two lineages prior to their radiations. Independent chromosomal fixation of the virB operon and consecutive rounds of lineage-specific bep gene duplications followed by their functional diversification characterize these parallel evolutionary trajectories. Whereas most Beps maintained their ancestral domain constitution, strikingly, a novel type of effector protein emerged convergently in both lineages. This resulted in similar arrays of host cell-targeted effector proteins in the two lineages of Bartonella as the basis of their independent radiation. The parallel molecular evolution of the VirB/Bep system displays a striking example of a key innovation involved in independent adaptive processes and the emergence of bacterial pathogens. Furthermore, our study highlights the remarkable evolvability of T4SSs and their effector proteins, explaining their broad application in bacterial interactions with the environment. Adaptive radiation is the rapid origination of an array of species by the divergent colonization of disparate ecological niches. In the case of pathogenic bacteria, radiations can lead to the emergence of novel human pathogens. Being divergently adapted to a range of different mammalian hosts, including humans as reservoir or incidental hosts, the genus Bartonella represents a suitable model to study genomic mechanisms underpinning divergent adaptation of pathogens. Here we show that two distinct lineages of Bartonella have radiated in parallel, resulting in two arrays of evolutionary distinct species adapted to overlapping sets of mammalian hosts. Such parallelisms display excellent models to reveal insights into the genetic mechanisms underlying these independent evolutionary processes. Our genome-wide analysis identifies a striking evolutionary parallelism in a horizontally-acquired protein secretion system in the two lineages. The parallel evolutionary trajectory of this system in the two lineages is characterized by the convergent origination of a wide array of adaptive functions dedicated to the cellular interaction within the mammalian hosts. The parallel evolution of the two radiating lineages on the ecological as well as on the molecular level suggests that the horizontal acquisition and the functional diversification of the secretion system display an evolutionary key innovation underlying adaptive evolution.
Collapse
Affiliation(s)
- Philipp Engel
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
Adhesion to host cells represents the first step in the infection process and one of the decisive features in the pathogenicity of Bartonella spp. B. henselae and B. quintana are considered to be the most important human pathogenic species, responsible for cat scratch disease, bacillary angiomatosis, trench fever and other diseases. The ability to cause vasculoproliferative disorders and intraerythrocytic bacteraemia are unique features of the genus Bartonella. Consequently, the interaction with endothelial cells and erythrocytes is a focus in Bartonella research. The genus harbours a variety of trimeric autotransporter adhesins (TAAs) such as the Bartonella adhesin A (BadA) of B. henselae and the variably expressed outer-membrane proteins (Vomps) of B. quintana, which display remarkable variations in length and modular construction. These adhesins mediate many of the biologically-important properties of Bartonella spp. such as adherence to endothelial cells and extracellular matrix proteins and induction of angiogenic gene programming. There is also significant evidence that the laterally acquired Trw-conjugation systems of Bartonella spp. mediate host-specific adherence to erythrocytes. Other potential adhesins are the filamentous haemagglutinins and several outer membrane proteins. The exact molecular functions of these adhesins and their interplay with other pathogenicity factors (e.g., the VirB/D4 type 4 secretion system) need to be analysed in detail to understand how these pathogens adapt to their mammalian hosts.
Collapse
|
21
|
Scheidegger F, Quebatte M, Mistl C, Dehio C. The Bartonella henselae VirB/Bep system interferes with vascular endothelial growth factor (VEGF) signalling in human vascular endothelial cells. Cell Microbiol 2010; 13:419-31. [PMID: 21044238 DOI: 10.1111/j.1462-5822.2010.01545.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The vasculotropic pathogen Bartonella henselae (Bh) intimately interacts with human endothelial cells (ECs) and subverts multiple cellular functions. Here we report that Bh specifically interferes with vascular endothelial growth factor (VEGF) signalling in ECs. Bh infection abrogated VEGF-induced proliferation and wound closure of EC monolayers as well as the capillary-like sprouting of EC spheroids. On the molecular level, Bh infection did not alter VEGF receptor 2 (VEGFR2) expression or cell surface localization, but impeded VEGF-stimulated phosphorylation of VEGFR2 at tyrosine(1175) . Consistently, we observed that Bh infection diminished downstream events of the tyrosine(1175) -dependent VEGFR2-signalling pathway leading to EC proliferation, i.e. phospholipase-Cγ activation, cytosolic calcium fluxes and mitogen-activated protein kinase ERK1/2 phosphorylation. Pervanadate treatment neutralized the inhibitory activity of Bh on VEGF signalling, suggesting that Bh infection may activate a phosphatase that alleviates VEGFR2 phosphorylation. Inhibition of VEGFR2 signalling by Bh infection was strictly dependent on a functional VirB type IV secretion system and thereby translocated Bep effector proteins. The data presented in this study underscore the role of the VirB/Bep system as important factor controlling EC proliferation in response to Bh infection; not only as previously reported by counter-acting an intrinsic bacterial mitogenic stimulus, but also by restricting the exogenous angiogenic stimulation by Bh-induced VEGF.
Collapse
|
22
|
Truttmann MC, Rhomberg TA, Dehio C. Combined action of the type IV secretion effector proteins BepC and BepF promotes invasome formation of Bartonella henselae on endothelial and epithelial cells. Cell Microbiol 2010; 13:284-99. [PMID: 20964799 DOI: 10.1111/j.1462-5822.2010.01535.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bartonella henselae (Bhe) can invade human endothelial cells (ECs) by two distinguishable entry routes: either individually by endocytosis or as large bacterial aggregates by invasome-mediated internalization. Only the latter process is dependent on a functional VirB/VirD4 type IV secretion system (T4SS) and the thereby translocated Bep effector proteins. Here, we introduce HeLa cells as a new cell system suitable to study invasome formation. We describe a novel route to trigger invasome formation by the combined action of the effectors BepC and BepF. Co-infections of either HUVEC or HeLa cells with the Bep-deficient ΔbepA-G mutant expressing either BepC or BepF restores invasome formation. Likewise, ectopic expression of a combination of BepC and BepF in HeLa cells enables invasome-mediated uptake of the Bhe ΔbepA-G mutant strain. Further, eGFP-BepC and eGFP-BepF fusion proteins localize to the cell membrane and, upon invasome formation, to the invasome. Furthermore, the combined action of BepC and BepF inhibits endocytic uptake of inert microspheres. Finally, we show that BepC and BepF-triggered invasome formation differs from BepG-triggered invasome formation in its requirement for cofilin1, while the Rac1/Scar1/WAVE/Arp2/3 and Cdc42/WASP/Arp2/3 signalling pathways are required in both cases.
Collapse
Affiliation(s)
- Matthias C Truttmann
- Focal Area Infection Biology, Biozentrum of the University of Basel, Klingelbergstrasse 70, Basel, Switzerland
| | | | | |
Collapse
|
23
|
The BatR/BatS two-component regulatory system controls the adaptive response of Bartonella henselae during human endothelial cell infection. J Bacteriol 2010; 192:3352-67. [PMID: 20418395 DOI: 10.1128/jb.01676-09] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here, we report the first comprehensive study of Bartonella henselae gene expression during infection of human endothelial cells. Expression of the main cluster of upregulated genes, comprising the VirB type IV secretion system and its secreted protein substrates, is shown to be under the positive control of the transcriptional regulator BatR. We demonstrate binding of BatR to the promoters of the virB operon and a substrate-encoding gene and provide biochemical evidence that BatR and BatS constitute a functional two-component regulatory system. Moreover, in contrast to the acid-inducible (pH 5.5) homologs ChvG/ChvI of Agrobacterium tumefaciens, BatR/BatS are optimally activated at the physiological pH of blood (pH 7.4). By conservation analysis of the BatR regulon, we show that BatR/BatS are uniquely adapted to upregulate a genus-specific virulence regulon during hemotropic infection in mammals. Thus, we propose that BatR/BatS two-component system homologs represent vertically inherited pH sensors that control the expression of horizontally transmitted gene sets critical for the diverse host-associated life styles of the alphaproteobacteria.
Collapse
|
24
|
Rikihisa Y, Lin M. Anaplasma phagocytophilum and Ehrlichia chaffeensis type IV secretion and Ank proteins. Curr Opin Microbiol 2010; 13:59-66. [PMID: 20053580 DOI: 10.1016/j.mib.2009.12.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 12/02/2009] [Accepted: 12/09/2009] [Indexed: 02/04/2023]
Abstract
The obligatory intracellular bacterial pathogens Anaplasma and Ehrlichia infect leukocytes by hijacking host-cell components and processes. The type IV secretion system is up-regulated during infection. Among type IV secretion candidate substrates, an ankyrin repeat protein of Anaplasma phagocytophilum, AnkA, is delivered into the host cytoplasm via a complex that includes VirD4. AnkA is highly tyrosine phosphorylated and binds to the Abl interactor 1, SHP-1, and nuclear DNA fragments. Ehrlichia chaffeensis AnkA was recently reported to be translocated into host-cell nucleus. The recent discovery of several ankyrin repeat proteins secreted via the type IV secretion system of different intracellular bacteria suggests that a common strategy evolved to subvert host-cell functions.
Collapse
Affiliation(s)
- Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
| | | |
Collapse
|
25
|
Abstract
The endothelium lining blood and lymphatic vessels is a key barrier separating body fluids from host tissues and is a major target of pathogenic bacteria. Endothelial cells are actively involved in host responses to infectious agents, producing inflammatory cytokines, controlling coagulation cascades and regulating leukocyte trafficking. In this Review, a range of bacteria and bacterial toxins are used to illustrate how pathogens establish intimate interactions with endothelial cells, triggering inflammatory responses and coagulation processes and modifying endothelial cell plasma membranes and junctions to adhere to their surfaces and then invade, cross and even disrupt the endothelial barrier.
Collapse
|
26
|
Minnick MF, Battisti JM. Pestilence, persistence and pathogenicity: infection strategies of Bartonella. Future Microbiol 2009; 4:743-58. [PMID: 19659429 DOI: 10.2217/fmb.09.41] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
It has been nearly two decades since the discovery of Bartonella as an agent of bacillary angiomatosis in AIDS patients and persistent bacteremia and 'nonculturable' endocarditis in homeless people. Since that time, the number of Bartonella species identified has increased from one to 24, and 10 of these bacteria are associated with human disease. Although Bartonella is the only genus that infects human erythrocytes and triggers pathological angiogenesis in the vascular bed, the group remains understudied compared with most other bacterial pathogens. Numerous questions regarding Bartonella's molecular pathogenesis and epidemiology remain unanswered. Virtually every mammal harbors one or more Bartonella species and their transmission typically involves a hematophagous arthropod vector. However, many details regarding epidemiology and the public health threat imposed by these animal reservoirs is unclear. A handful of studies have shown that bartonellae are highly-adapted pathogens whose parasitic strategy has evolved to cause persistent infections of the host. To this end, virulence attributes of Bartonella include the subversion of host cells with effector molecules delivered via a type IV secretion system, induction of pathological angiogenesis through various means, including inhibition of apoptosis and activation of hypoxia-inducing factor 1, use of afimbrial adhesins that are orthologs of Yersinia adhesin A, incorporation of lipopolysaccharides with low endotoxic potency in the outer membrane, and several other virulence factors that help Bartonella infect and persist in erythrocytes and endothelial cells of the host circulatory system.
Collapse
Affiliation(s)
- Michael F Minnick
- The University of Montana, Division of Biological Sciences, Missoula, MT 59812, USA.
| | | |
Collapse
|
27
|
Rhomberg TA, Truttmann MC, Guye P, Ellner Y, Dehio C. A translocated protein of Bartonella henselae interferes with endocytic uptake of individual bacteria and triggers uptake of large bacterial aggregates via the invasome. Cell Microbiol 2009; 11:927-45. [PMID: 19302579 DOI: 10.1111/j.1462-5822.2009.01302.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bartonella henselae enters human endothelial cells (ECs) by two alternative routes: either by endocytosis, giving rise to Bartonella-containing vacuoles or by invasome-mediated internalization. Only the latter process depends on the type IV secretion system VirB/VirD4 and involves the formation of cell surface-associated bacterial aggregates, which get engulfed by EC membranes in an F-actin-dependent manner, eventually resulting in their complete internalization. Here, we report that among the VirB/VirD4-translocated effector proteins BepA-BepG only BepG is required for triggering invasome-mediated internalization. Expression of BepG in the Bep-deficient DeltabepA-G mutant restored invasome-mediated internalization. Likewise, ectopic expression of BepG in ECs also restored invasome-mediated internalization of the DeltabepA-G mutant, while no discernable cytoskeletal rearrangements were triggered in uninfected cells. Rather, BepG inhibited endocytic uptake of B. henselae into Bartonella-containing vacuoles and other endocytic processes, that is, invasin-mediated uptake of Yersinia enterocolitica and uptake of inert microspheres. BepG thus triggers invasome-mediated internalization primarily by inhibiting bacterial endocytosis. Bacteria accumulating on the cell surface then induce locally the F-actin rearrangements characteristic for the invasome. These cytoskeletal changes encompass both the rearrangement of pre-existing F-actin fibres and the de novo polymerization of cortical F-actin in the periphery of the invasome by Rac1/Scar1/WAVE- and Cdc42/WASP-dependent pathways that involve the recruitment of the Arp2/3 complex.
Collapse
Affiliation(s)
- Thomas A Rhomberg
- Focal Area Infection Biology, Biozentrum of the University of Basel, CH-4056 Basel, Switzerland
| | | | | | | | | |
Collapse
|