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Chou WK, Brynildsen MP. A biochemical engineering view of the quest for immune-potentiating anti-infectives. Curr Opin Chem Eng 2016. [DOI: 10.1016/j.coche.2016.08.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Radomski N, Einenkel R, Müller A, Knittler MR. Chlamydia-host cell interaction not only from a bird's eye view: some lessons fromChlamydia psittaci. FEBS Lett 2016; 590:3920-3940. [DOI: 10.1002/1873-3468.12295] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 07/06/2016] [Accepted: 07/07/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Nadine Radomski
- Friedrich-Loeffler-Institut; Institute of Immunology; Isle of Riems Germany
| | - Rebekka Einenkel
- Friedrich-Loeffler-Institut; Institute of Immunology; Isle of Riems Germany
| | - Anne Müller
- Friedrich-Loeffler-Institut; Institute of Immunology; Isle of Riems Germany
| | - Michael R Knittler
- Friedrich-Loeffler-Institut; Institute of Immunology; Isle of Riems Germany
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Knittler MR, Sachse K. Chlamydia psittaci: update on an underestimated zoonotic agent. Pathog Dis 2014; 73:1-15. [PMID: 25853998 DOI: 10.1093/femspd/ftu007] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2014] [Indexed: 12/16/2022] Open
Abstract
Chlamydia (C.) psittaci is an economically relevant pathogen in poultry and pet birds, where it causes psittacosis/ornithosis, and also a human pathogen causing atypical pneumonia after zoonotic transmission. Despite its well-documented prevalence, the agent has received less attention by researchers than other Chlamydia spp. in the last decades. In the present paper, we review recently published data on C. psittaci infection and attempt to single out characteristic features distinguishing it from related chlamydial agents. It is remarkable that C. psittaci is particularly efficient in disseminating in the host organism causing systemic disease, which occasionally can take a fulminant course. At the cellular level, the pathogen's broad host cell spectrum (from epithelial cells to macrophages), its rapid entry and fast replication, proficient use of intracellular transport routes to mitochondria and the Golgi apparatus, the pronounced physical association of chlamydial inclusions with energy-providing cell compartments, as well as the subversive regulation of host cell survival during productive and persistent states facilitate the characteristic efficient growth and successful host-to-host spread of C. psittaci. At the molecular level, the pathogen was shown to upregulate essential chlamydial genes when facing the host immune response. We hypothesize that this capacity, in concert with expression of specific effectors of the type III secretion system and efficient suppression of selected host defense signals, contributes to successful establishment of the infection in the host. Concerning the immunology of host-pathogen interactions, C. psittaci has been shown to distinguish itself by coping more efficiently than other chlamydiae with pro-inflammatory mediators during early host response, which can, to some extent, explain the effective evasion and adaptation strategies of this bacterium. We conclude that thorough analysis of the large number of whole-genome sequences already available will be essential to identify genetic markers of the species-specific features and trigger more in-depth studies in cellular and animal models to address such vital topics as treatment and vaccination.
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Affiliation(s)
- Michael R Knittler
- Institute of Immunology, Friedrich-Loeffler-Institut, Isle of Riems, 07743 Jena, Germany
| | - Konrad Sachse
- Institute of Molecular Pathogenesis, Friedrich-Loeffler-Institut, 07743 Jena, Germany
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Ronzone E, Paumet F. Two coiled-coil domains of Chlamydia trachomatis IncA affect membrane fusion events during infection. PLoS One 2013; 8:e69769. [PMID: 23936096 PMCID: PMC3720611 DOI: 10.1371/journal.pone.0069769] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/12/2013] [Indexed: 12/29/2022] Open
Abstract
Chlamydia trachomatis replicates in a parasitophorous membrane-bound compartment called an inclusion. The inclusions corrupt host vesicle trafficking networks to avoid the degradative endolysosomal pathway but promote fusion with each other in order to sustain higher bacterial loads in a process known as homotypic fusion. The Chlamydia protein IncA (Inclusion protein A) appears to play central roles in both these processes as it participates to homotypic fusion and inhibits endocytic SNARE-mediated membrane fusion. How IncA selectively inhibits or activates membrane fusion remains poorly understood. In this study, we analyzed the spatial and molecular determinants of IncA’s fusogenic and inhibitory functions. Using a cell-free membrane fusion assay, we found that inhibition of SNARE-mediated fusion requires IncA to be on the same membrane as the endocytic SNARE proteins. IncA displays two coiled-coil domains showing high homology with SNARE proteins. Domain swap and deletion experiments revealed that although both these domains are capable of independently inhibiting SNARE-mediated fusion, these two coiled-coil domains cooperate in mediating IncA multimerization and homotypic membrane interaction. Our results support the hypothesis that Chlamydia employs SNARE-like virulence factors that positively and negatively affect membrane fusion and promote infection.
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Affiliation(s)
- Erik Ronzone
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Fabienne Paumet
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Beeckman DS, De Puysseleyr L, De Puysseleyr K, Vanrompay D. Chlamydial biology and its associated virulence blockers. Crit Rev Microbiol 2012; 40:313-28. [PMID: 23134414 DOI: 10.3109/1040841x.2012.726210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chlamydiales are obligate intracellular parasites of eukaryotic cells. They can be distinguished from other Gram-negative bacteria through their characteristic developmental cycle, in addition to special biochemical and physical adaptations to subvert the eukaryotic host cell. The host spectrum includes humans and other mammals, fish, birds, reptiles, insects and even amoeba, causing a plethora of diseases. The first part of this review focuses on the specific chlamydial infection biology and metabolism. As resistance to classical antibiotics is emerging among Chlamydiae as well, the second part elaborates on specific compounds and tools to block chlamydial virulence traits, such as adhesion and internalization, Type III secretion and modulation of gene expression.
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Affiliation(s)
- Delphine S Beeckman
- Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University , Coupure Links 653, B-9000 Ghent , Belgium
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Li Z, Lu C, Peng B, Zeng H, Zhou Z, Wu Y, Zhong G. Induction of protective immunity against Chlamydia muridarum intravaginal infection with a chlamydial glycogen phosphorylase. PLoS One 2012; 7:e32997. [PMID: 22427926 PMCID: PMC3299733 DOI: 10.1371/journal.pone.0032997] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 02/06/2012] [Indexed: 11/19/2022] Open
Abstract
We evaluated 7 C. muridarum ORFs for their ability to induce protection against chlamydial infection in a mouse intravaginal infection model. These antigens, although encoded in C. muridarum genome, are transcriptionally regulated by a cryptic plasmid that is known to contribute to C. muridarum pathogenesis. Of the 7 plasmid-regulated ORFs, the chlamydial glycogen phosphorylase or GlgP, when delivered into mice intramuscularly, induced the most pronounced protective immunity against C. muridarum intravaginal infection. The GlgP-immunized mice displayed a significant reduction in vaginal shedding of live organisms on day 14 after infection. The protection correlated well with a robust C. muridarum-specific antibody and a Th1-dominant T cell responses, which significantly reduced the severity but not overall incidence of hydrosalpinx. The GlgP-induced partial protection against upper genital tract pathology suggests that GlgP may be considered a component for a multi-subunit vaccine. These results have demonstrated that intramuscular immunization of mice with purified proteins can be used to identify vaccine antigens for preventing intravaginal infection with C. trachomatis in humans.
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Affiliation(s)
- Zhihong Li
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Department of Surgery, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Chunxue Lu
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Department of Microbiology and Pathology, University of South China, Hengyang, Hunan, China
| | - Bo Peng
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Department of Microbiology and Pathology, University of South China, Hengyang, Hunan, China
| | - Hao Zeng
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Zhiguan Zhou
- Department of Surgery, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yimou Wu
- Department of Microbiology and Pathology, University of South China, Hengyang, Hunan, China
| | - Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- * E-mail:
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Yasir M, Pachikara ND, Bao X, Pan Z, Fan H. Regulation of chlamydial infection by host autophagy and vacuolar ATPase-bearing organelles. Infect Immun 2011; 79:4019-28. [PMID: 21807906 PMCID: PMC3187247 DOI: 10.1128/iai.05308-11] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 07/20/2011] [Indexed: 11/20/2022] Open
Abstract
As arguably the most successful parasite, Chlamydia is an obligate intracellular bacterium replicating inside a vacuole of eukaryotic host cells. The chlamydial vacuole does not fuse with the defense cell organelle lysosome. We previously showed that chlamydial infection increases markers of autophagy, an innate antimicrobial activity requiring lysosomal function. However, the work presented here demonstrates that p62, an autophagy protein that is degraded in lysosomes, either remained unchanged or increased in chlamydia-infected human epithelial, mouse fibroblast, and mouse macrophage cell lines. In addition, the activities of three lysosomal enzymes analyzed were diminished in chlamydia-infected macrophages. Bafilomycin A1 (BafA), a specific inhibitor of vacuolar ATPase (vATPase) required for lysosomal function, increased the growth of the human pathogen Chlamydia trachomatis (L2) in wild-type murine fibroblasts and macrophages but inhibited growth in the autophagy-deficient ATG5(-/-) fibroblasts. BafA exhibited only slight inhibition or no effect on L2 growth in multiple human genital epithelial cell lines. In contrast to L2, the mouse pathogen Chlamydia muridarum (MoPn) was consistently inhibited by BafA in all cell lines examined, regardless of species origin and autophagy status. Finally, L2 but not MoPn grew more efficiently in the ATG5(-/-) cells than in wild-type cells. These results suggest that there are two types of vATPase-bearing organelles that regulate chlamydial infection: one supports chlamydial infection, while the other plays a defensive role through autophagy when cells are artificially infected with certain chlamydiae that have not been adapted to the host species.
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Affiliation(s)
| | | | | | - Zui Pan
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, 683 Hoes Lane, Piscataway, New Jersey 08854
| | - Huizhou Fan
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, 683 Hoes Lane, Piscataway, New Jersey 08854
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Identification and functional analysis of CT069 as a novel transcriptional regulator in Chlamydia. J Bacteriol 2011; 193:6123-31. [PMID: 21908669 DOI: 10.1128/jb.05976-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Only a small number of transcription factors have been predicted in Chlamydia spp., which are obligate intracellular bacteria that include a number of important human pathogens. We used a bioinformatics strategy to identify novel transcriptional regulators from the Chlamydia trachomatis genome by predicting proteins with the general structure and characteristic functional domains of a bacterial transcription factor. With this approach, we identified CT069 as a candidate transcription factor with sequence similarity at its C terminus to Treponema pallidum TroR. Like TroR, the gene for CT069 belongs to an operon that encodes components of a putative ABC transporter for importing divalent metal cations. However, CT069 has been annotated as YtgC because of sequence similarity at its N terminus to TroC, a transmembrane component of this metal ion transporter. Instead, CT069 appears to be a fusion protein composed of YtgC and a TroR ortholog that we have called YtgR. Although it has not been previously reported, a similar YtgC-YtgR fusion protein is predicted to be encoded by other Chlamydia spp. and several other bacteria, including Bacillus subtilis. We show that recombinant YtgR polypeptide bound specifically to an operator sequence upstream of the ytg operon and that binding was enhanced by Zn(2+). We also demonstrate that YtgR repressed transcription from the ytg promoter in a heterologous in vivo reporter assay. These results provide evidence that CT069 is a negative regulator of the ytg operon, which encodes a putative metal ion transporter in C. trachomatis.
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Zhong G. Killing me softly: chlamydial use of proteolysis for evading host defenses. Trends Microbiol 2009; 17:467-74. [PMID: 19765998 DOI: 10.1016/j.tim.2009.07.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 04/06/2009] [Accepted: 07/13/2009] [Indexed: 12/13/2022]
Abstract
Chlamydial infections in humans cause severe health problems, including blinding trachoma and sexually transmitted diseases. Although the involved pathogenic mechanisms remain unclear, the ability to replicate and maintain long-term residence in the infected cells seems to significantly contribute to chlamydial pathogenicity. These obligate intracellular parasites maintain a delicate balance between exploiting and protecting their host: they occupy intracellular space and acquire nutrients from the infected cells, but at the same time they have to maintain the integrity of the host cells for the completion of their intracellular growth. For this purpose, chlamydiae hijack certain signaling pathways that prevent the host cells from undergoing apoptosis induced by intracellular stress and protect the infected cells from recognition and attack by host defenses. Interestingly, one of the strategies that chlamydiae use for these purposes is the induction of limited proteolysis of host proteins, which is the main focus of this article.
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Affiliation(s)
- Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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The chlamydial plasmid-encoded protein pgp3 is secreted into the cytosol of Chlamydia-infected cells. Infect Immun 2008; 76:3415-28. [PMID: 18474640 DOI: 10.1128/iai.01377-07] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The chlamydial cryptic plasmid encodes eight putative open reading frames (ORFs), designated pORF1 to -8. Antibodies raised against these ORF proteins were used to localize the endogenous proteins during chlamydial infection. We found that the pORF5 protein (also known as pgp3) was detected mainly in the cytosol of Chlamydia-infected cells, while the remaining seven proteins were found inside the chlamydial inclusions only. The pgp3 distribution pattern in the host cell cytosol is similar to but not overlapping with that of chlamydial protease/proteasome-like activity factor (CPAF), a chlamydial genome-encoded protein known to be secreted from chlamydial inclusions into the host cell cytosol. The anti-pgp3 labeling was removed by preabsorption with pgp3 but not CPAF fusion proteins and vice versa, demonstrating that pgp3 is a unique secretion protein. This conclusion is further supported by the observation that pgp3 was highly enriched in cytosolic fractions and had a minimal presence in the inclusion-containing nuclear fractions prepared from Chlamydia-infected cells. The pgp3 protein was detected as early as 12 h after infection and was secreted by all chlamydial species that carry the cryptic plasmid, suggesting that there is a selection pressure for maintaining pgp3 secretion during chlamydial infection. Although expression of pgp3 in the host cell cytosol via a transgene did not alter the susceptibility of the transfected cells to the subsequent chlamydial infection, purified pgp3 protein stimulated macrophages to release inflammatory cytokines, suggesting that pgp3 may contribute to chlamydial pathogenesis.
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Characterization of hypothetical proteins Cpn0146, 0147, 0284 & 0285 that are predicted to be in the Chlamydia pneumoniae inclusion membrane. BMC Microbiol 2007; 7:38. [PMID: 17504539 PMCID: PMC1878484 DOI: 10.1186/1471-2180-7-38] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 05/15/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Although more than 100 Chlamydia pneumoniae hypothetical proteins have been predicted to be inclusion membrane proteins, only a few have been experimentally demonstrated to be in the inclusion membrane. Using antibodies raised with fusion proteins, we characterized four such hypothetical proteins encoded by two gene clusters (Cpn0146-147 and Cpn0284-285) in the C. pneumoniae genome. RESULTS Cpn0146 and 0147 were detected in the inclusion membrane while Cpn0284 and 0285 inside inclusion and mainly associated with reticulate bodies although all four proteins contain an N-terminal bi-lobed hydrophobic region, a signature motif assigned to inclusion membrane proteins. These four hypothetical proteins were only detected in cells infected with C. pneumoniae but not other chlamydial species, with Cpn0147 at 6 hours and Cpn0146, 0284 & 0285 at 24 hours after infection. Cpn0146 & 147 but not Cpn0284 and 285 co-localized with a host cell endoplasmic reticulum marker, a property known to be possessed by some chlamydial inclusion membrane proteins, when expressed in the host cell cytosol via transgenes. However, the endoplasmic reticulum localization of the C. pneumoniae inclusion membrane proteins did not result in inhibition of the subsequent C. pneumoniae infection. CONCLUSION The hypothetical proteins Cpn0146 & 0147 were localized in the C. pneumoniae inclusion membrane while Cpn0284 & 0285 within the inclusion although all four were predicted to be Inc proteins, suggesting the need to experimentally characterize the predicted Inc proteins.
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Luo J, Jia T, Zhong Y, Chen D, Flores R, Zhong G. Localization of the hypothetical protein Cpn0585 in the inclusion membrane of Chlamydia pneumoniae-infected cells. Microb Pathog 2007; 42:111-6. [PMID: 17236746 PMCID: PMC1850435 DOI: 10.1016/j.micpath.2006.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 11/08/2006] [Accepted: 11/30/2006] [Indexed: 10/23/2022]
Abstract
Cpn0585, encoded by a hypothetical open reading frame in Chlamydia pneumoniae genome, was detected in the inclusion membrane during C. pneumoniae infection using both polyclonal and monoclonal antibodies raised with Cpn0585 fusion protein. The anti-Cpn0585 antibodies specifically recognized the endogenous Cpn0585 without cross-reacting with IncA (a known inclusion membrane protein of C. pneumoniae) or other control antigens. A homologue of Cpn0585 in the C. caviae species (encoded by the ORF CCA00156) was also localized in the inclusion membrane of the C. caviae-infected cells. The Cpn0585 protein became detectable 24h while CCA00156 as early as 8h after infection. Once expressed, both proteins remained in the inclusion membrane throughout the rest of infection course.
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Affiliation(s)
- Jianhua Luo
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Tianjun Jia
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
- Department of Immunology, Hebei Medical University, Shijiazhuang, Hebei 050017, The People’s Republic of China
| | - Youmin Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Ding Chen
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Rhonda Flores
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
- *Corresponding author: Guangming Zhong, Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, Phone: 210-567-1169, Fax: 210-567-0293,
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Xiao Y, Zhong Y, Su H, Zhou Z, Chiao P, Zhong G. NF-κB Activation Is Not Required forChlamydia trachomatisInhibition of Host Epithelial Cell Apoptosis. THE JOURNAL OF IMMUNOLOGY 2005; 174:1701-8. [PMID: 15661934 DOI: 10.4049/jimmunol.174.3.1701] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Chlamydia trachomatis, an obligate intracellular bacterial species, is known to inhibit host cell apoptosis. However, the chlamydial antiapoptotic mechanism is still not clear. Because NF-kappaB activation is antiapoptotic, we tested the potential role of NF-kappaB activation in chlamydial antiapoptotic activity in the current study. First, no obvious NF-kappaB activation was detected in the chlamydia-infected cells when these cells were resistant to apoptosis induced via either the intrinsic or extrinsic apoptosis pathways. Second, inhibition of NF-kappaB activation with pharmacologic reagents failed to block the chlamydial antiapoptotic activity. Finally, NF-kappaB p65 gene deletion did not prevent chlamydia from inhibiting host cell apoptosis. These observations together have demonstrated that NF-kappaB activation is not required for the chlamydial antiapoptotic activity.
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Affiliation(s)
- Yangming Xiao
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Sharma J, Bosnic AM, Piper JM, Zhong G. Human antibody responses to a Chlamydia-secreted protease factor. Infect Immun 2004; 72:7164-71. [PMID: 15557641 PMCID: PMC529132 DOI: 10.1128/iai.72.12.7164-7171.2004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously identified a chlamydia-secreted protein (designated chlamydial proteasome/protease-like activity factor, or CPAF) in the cytosol of chlamydia-infected cells. Although CPAF is known to degrade host transcription factors required for major histocompatibility complex antigen expression in cultured cells, it is not clear whether CPAF is produced and maintains similar functions in humans infected with chlamydial organisms. We now report that CPAF does not preexist in chlamydial organisms and that CPAF synthesis requires live organism replication in cultured cells. Mice inoculated with live, but not mice inoculated with dead, chlamydial organisms produced a strong antibody response to CPAF, correlating CPAF-specific antibody production with CPAF synthesis in animals. Sera from women diagnosed with Chlamydia trachomatis cervicitis displayed higher levels of antibodies to CPAF than to either chlamydial major outer membrane protein or heat shock protein 60, suggesting that CPAF is both produced and immunogenic during human chlamydial infection.
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Affiliation(s)
- Jyotika Sharma
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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Abstract
Chlamydiae, bacterial obligate intracellular pathogens, are the etiologic agents of several human diseases. A large part of the chlamydial intracellular survival strategy involves the formation of a unique organelle called the inclusion that provides a protected site within which they replicate. The chlamydial inclusion is effectively isolated from endocytic pathways but is fusogenic with a subset of exocytic vesicles that deliver sphingomyelin from the Golgi apparatus to the plasma membrane. A combination of host and parasite functions contribute to the biogenesis of this compartment. Establishment of the mature inclusion is accompanied by the insertion of multiple chlamydial proteins, suggesting that chlamydiae actively modify the inclusion to define its interactions with the eukaryotic host cell. Despite being sequestered within a membrane-bound vacuole, chlamydiae clearly communicate with and manipulate the host cell from within this privileged intracellular niche.
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Affiliation(s)
- Kenneth A Fields
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana 59840, USA
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Hamrick TS, Diaz AH, Havell EA, Horton JR, Orndorff PE. Influence of extracellular bactericidal agents on bacteria within macrophages. Infect Immun 2003; 71:1016-9. [PMID: 12540587 PMCID: PMC145358 DOI: 10.1128/iai.71.2.1016-1019.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We employed gentamicin-sensitive and -resistant derivatives of Escherichia coli in a macrophage phagocytosis assay that compared lambda bacteriophage and gentamicin as extracellular bactericidal agents. Colony counts and direct microscopic examination of phagocytized E. coli supported the conclusion that gentamicin entered macrophages, even at low concentrations, and contributed to their bactericidal activity. Also, two E. coli strains differing in the ability to express the adhesin of type 1 pili (FimH) were distinguishably different in intracellular survival when lambda was used as the extracellular killing agent but were indistinguishable when gentamicin was employed.
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Affiliation(s)
- Terri S Hamrick
- Department of Microbiology, Pathology, and Parasitology, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA
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Scidmore MA, Fischer ER, Hackstadt T. Restricted fusion of Chlamydia trachomatis vesicles with endocytic compartments during the initial stages of infection. Infect Immun 2003; 71:973-84. [PMID: 12540580 PMCID: PMC145390 DOI: 10.1128/iai.71.2.973-984.2003] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The chlamydial inclusion occupies a unique niche within the eukaryotic cell that does not interact with endocytic compartments but instead is fusogenic with a subset of sphingomyelin-containing exocytic vesicles. The Chlamydia trachomatis inclusion acquires these distinctive properties by as early as 2 h postinfection as demonstrated by the ability to acquire sphingomyelin, endogenously synthesized from 6[N-[(7-nitrobenzo-2-oxa-1,3-diazol-4-yl)amino]caproylsphingosine] (C(6)-NBD-ceramide). The molecular mechanisms involved in transformation of the properties and cellular interactions of the inclusion are unknown except that they require early chlamydial transcription and translation. Although the properties of the inclusion are established by 2 h postinfection, the degree of interaction with endocytic pathways during the brief interval before fusogenicity with an exocytic pathway is established is unknown. Using a combination of confocal and electron microscopy to localize endocytic and lysosomal markers in C. trachomatis infected cells during the early stages of infection, we demonstrate a lack of these markers within the inclusion membrane or lumen of the inclusion to conclude that the nascent chlamydial inclusion is minimally interactive with endosomal compartments during this interval early in infection. Even when prevented from modifying the properties of the inclusion by incubation in the presence of protein synthesis inhibitors, vesicles containing elementary bodies are very slow to acquire lysosomal characteristics. These results imply a two-stage mechanism for chlamydial avoidance of lysosomal fusion: (i) an initial phase of delayed maturation to lysosomes due to an intrinsic property of elementary bodies and (ii) an active modification of the vesicular interactions of the inclusion requiring chlamydial protein synthesis.
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Affiliation(s)
- Marci A Scidmore
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana 59840, USA
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Feldmesser M, Tucker S, Casadevall A. Intracellular parasitism of macrophages by Cryptococcus neoformans. Trends Microbiol 2001; 9:273-8. [PMID: 11390242 DOI: 10.1016/s0966-842x(01)02035-2] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cryptococcus neoformans, an encapsulated fungal pathogen, causes meningoencephalitis in immunocompromised patients. Recent in vivo studies have demonstrated that C. neoformans is a facultative intracellular pathogen, as was previously suggested by in vitro studies. For survival in macrophages, C. neoformans utilizes a novel strategy for intracellular parasitism that includes the accumulation of intracellular polysaccharide in cytoplasmic vesicles. Confirmation of the fact that C. neoformans is a facultative intracellular pathogen could provide new insights into several poorly understood areas of cryptococcal pathogenesis, including mechanisms for latency and persistence and the lack of efficacy of humoral immunity. The finding that C. neoformans replicates inside macrophages in vitro in a manner similar to that observed in vivo provides an excellent system to dissect the molecular mechanisms responsible for this unique pathogenic strategy.
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Affiliation(s)
- M Feldmesser
- Dept of Medicine, Division of Infectious Diseases, Albert Einstein College of Medicine, Bronx, NY Golding Building Room 701, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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19
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Subtil A, Parsot C, Dautry-Varsat A. Secretion of predicted Inc proteins of Chlamydia pneumoniae by a heterologous type III machinery. Mol Microbiol 2001; 39:792-800. [PMID: 11169118 DOI: 10.1046/j.1365-2958.2001.02272.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Chlamydia spp. are strictly intracellular pathogens that grow inside a vacuole, called an inclusion. They possess genes encoding proteins homologous to components of type III secretion machineries, which, in other bacterial pathogens, are involved in delivery of bacterial proteins within or through the membrane of eukaryotic host cells. Inc proteins are chlamydial proteins that are associated with the inclusion membrane and are characterized by the presence of a large hydrophobic domain in their amino acid sequence. To investigate whether Inc proteins and other proteins exhibiting a similar hydropathic profile might be secreted by a type III system, we used a heterologous secretion system. Chimeras were constructed by fusing the N-terminal part of these proteins with a reporter, the Cya protein of Bordetella pertussis, and these were expressed in various strains of Shigella flexneri. We demonstrate that these hybrid proteins are secreted by the type III secretion system of S. flexneri, thereby providing evidence that IncA, IncB and IncC are secreted by a type III mechanism in chlamydiae. Moreover, we show that three other proteins from Chlamydia pneumoniae, all of which have in common the presence of a large hydrophobic domain, are also secreted by S. flexneri type III secretion machinery.
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Affiliation(s)
- A Subtil
- Unité de Biologie des Interactions Cellulaires, URA CNRS 1960, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France.
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20
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Hosseinzadeh S, Brewis IA, Pacey AA, Moore HD, Eley A. Coincubation of human spermatozoa with Chlamydia trachomatis in vitro causes increased tyrosine phosphorylation of sperm proteins. Infect Immun 2000; 68:4872-6. [PMID: 10948099 PMCID: PMC101686 DOI: 10.1128/iai.68.9.4872-4876.2000] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Elementary bodies (EBs) of the obligate intracellular bacterium Chlamydia trachomatis are responsible for the first step of attachment to host cells. We have studied the effects of EBs on human sperm protein tyrosine phosphorylation, which is important to sperm function. Indirect immunofluorescence using antiphosphotyrosine antibodies showed that serovar E, but not LGV, caused increased tyrosine phosphorylation which was localized to the sperm tail region. Immunoblotting revealed that serovar E caused a marked increase in tyrosine phosphorylation of 80- and 95-kDa sperm proteins, whereas serovar LGV caused increased phosphorylation of only the 80-kDa moiety. Considering the importance of tyrosine phosphorylation for sperm capacitation and other aspects of sperm function, we conclude that EBs may affect these events.
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Affiliation(s)
- S Hosseinzadeh
- Division of Molecular and Genetic Medicine, The Medical School, The University of Sheffield, Sheffield, S10 2RX, United Kingdom
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21
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Affiliation(s)
- M Scidmore-Carlson
- Host-Parasite Interactions Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana 59840, USA
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Abstract
Bacterial and protozoon intracellular parasites have evolved diverse mechanisms for evasion of host cellular defenses associated with adaptations for survival in distinct intracellular compartments. As the reagents identifying discrete steps in vesicle maturation and trafficking have become increasingly available, it has become clear that the vacuoles occupied by intracellular parasites are much more diverse than had been previously appreciated. Many parasites induce selective fusion competence with the vacuoles they occupy, without affecting vesicular trafficking elsewhere in the cell. A likely means of controlling vesicular interactions is modification of the parasitophorous vacuole membrane by the insertion of parasite-specific proteins. A rapidly expanding class of bacterial proteins that modify the vacuolar membrane are the chlamydial inclusion membrane proteins. Although the functions of most of these proteins remain to be defined, the majority are expressed early in the infectious process, suggesting that modification of the vacuole is critical to the outcome of the host-parasite interaction.
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Affiliation(s)
- T Hackstadt
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, NIAID, Rocky Mountain Laboratories, Hamilton, MT 59840, USA.
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23
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Van Nerom A, Ducatelle R, Haesebrouck F. Oxidative activity of turkey monocytes, following the inoculation with Chlamydia psittaci. Vet Microbiol 1999; 65:173-84. [PMID: 10189192 DOI: 10.1016/s0378-1135(98)00294-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chemiluminescence (CL) was used to investigate the competence of turkey monocytes to mount a respiratory burst response upon interaction with Chlamydia psittaci. The oxidative activity of purified turkey monocytes, following inoculation with the avian C. psittaci serovar D strain 92/1293, was studied using luminol- and lucigenin-enhanced CL. Purified turkey monocytes were inoculated with C. psittaci at multiplicity of infection (MOI) of approximately 100, 10 and 1. In the presence of luminol, no detectable CL or only a weak CL response was obtained, and if present it increased with increasing MOI. Either sham inoculated monocytes, or monocyte-free control assays supplemented with C. psittaci, gave no detectable luminol-enhanced CL responses. In the lucigenin-enhanced assays, monocytes inoculated with C. psittaci demonstrated an immediate CL peak, the height of which was proportional to the MOI used. Following inoculations at a MOI 1, a faint second peak was observed, when applying high concentrations of lucigenin. Sham inoculated monocytes gave no detectable lucigenin-enhanced CL responses. However, in the presence of lucigenin, the addition of C psittaci to monocyte-free controls also resulted in an immediate CL peak, though no second peak was detected. This immediate lucigenin-dependent CL peak induced by C. psittaci was similar to the one observed in the presence of monocytes, and was not inhibited by superoxide dismutase. We demonstrated that this avian C. psittaci strain induces only a very weak respiratory burst response in turkey monocytes. In contrast, C. psittaci itself elicited an intense non-superoxide mediated lucigenin-dependent CL, indicating that in chlamydial research the detection of superoxide, using lucigenin, should be confirmed with a specific superoxide inhibitor.
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Affiliation(s)
- A Van Nerom
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, University of Ghent, Salisburylaan, Merelbeke, Belgium.
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24
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Majeed M, Krause KH, Clark RA, Kihlström E, Stendahl O. Localization of intracellular Ca2+ stores in HeLa cells during infection with Chlamydia trachomatis. J Cell Sci 1999; 112 ( Pt 1):35-44. [PMID: 9841902 DOI: 10.1242/jcs.112.1.35] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chlamydia trachomatis elementary bodies (EBs) enter epithelial cells within membrane-bound endosomes that aggregate with each other in a calcium-regulated process, but avoid fusion with lysosomes. Annexin III but not I translocates to chlamydial aggregates and inclusions. In this study, we localize the intracellular Ca2+ stores during the course of infection by analyzing the distribution of three intracellular Ca2+ store proteins: calreticulin, type-1 inositol-1,4, 5-trisphosphate receptor (IP3-R), and Sarcoplasmic/Endoplasmic Reticulum Ca2+ ATPase type 2 (SERCA2) in HeLa cells infected with C. trachomatis serovar L2. In uninfected cells, immunofluorescence staining of the proteins showed a fine granular distributed pattern for all three proteins. After infection with C. trachomatis, calreticulin was found at the periphery of chlamydial aggregates and inclusions from 3 to 48 hours post-infection. In infected cells, SERCA2 was intimately associated with chlamydial inclusions after 3 and 24 hours, but not after 48 hours. Moreover, IP3-R was translocated to and colocalized with EB aggregates and chlamydial inclusions and had a distribution very similar to that of SERCA 2. After 24 hours incubation with chlamydiae, there was a local accumulation of [Ca2+]i (105+/-17 nM) in the proximity of chlamydial inclusions, compared to 50+/-13 nM in other parts of the cell cytoplasm. In the absence of extracellular Ca2+, this local accumulation of Ca2+ increased to 295+/-50 nM after adding 50 microM ATP, and to a similar extent after adding 100 nM thapsigargin (Tg). These data indicate that during infection of HeLa cells with chlamydiae, intracellular Ca2+ stores are redistributed, causing local accumulation of Ca2+ in the vicinity of chlamydial inclusions. These changes may trigger the association of certain proteins such as annexins with chlamydia-containing vesicles, and thereby regulation of membrane-membrane interaction during endosome aggregation and inclusion formation.
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Affiliation(s)
- M Majeed
- Divisions of Medical Microbiology and Clinical Microbiology, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden.
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25
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Van Ooij C, Homola E, Kincaid E, Engel J. Fusion of Chlamydia trachomatis-containing inclusions is inhibited at low temperatures and requires bacterial protein synthesis. Infect Immun 1998; 66:5364-71. [PMID: 9784545 PMCID: PMC108671 DOI: 10.1128/iai.66.11.5364-5371.1998] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human pathogen Chlamydia trachomatis is an obligate intracellular bacterium with a unique developmental cycle. Within the host cell cytoplasm, it resides within a membrane-bound compartment, the inclusion. A distinguishing characteristic of the C. trachomatis life cycle is the fusion of the chlamydia-containing inclusions with each other in the host cell cytoplasm. We report that fusion of inclusions does not occur at 32 degreesC in multiple mammalian cell lines and with three different serovars of C. trachomatis. The inhibition of fusion was inclusion specific; the fusion with sphingolipid-containing secretory vesicles and the interaction with early endosomes were unaffected by incubation at 32 degreesC. The inhibition of fusion of the inclusions was not primarily the result of delayed maturation of the inclusion, as infectious progeny was produced in host cells incubated at 32 degreesC, and the unfused inclusions remained competent to fuse up to 48 h postinfection. The ability to reverse the inhibition of fusion by shifting the infected cells from 32 to 37 degreesC allowed the measurement of the rate and the time of fusion of the inclusions after entry of the bacteria. Most significantly, we demonstrate that fusion of inclusions with each other requires bacterial protein synthesis and that the required bacterial protein(s) is present, but inactive or not secreted, at 32 degreesC.
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Affiliation(s)
- C Van Ooij
- Biomedical Sciences Program, University of California, San Francisco, San Francisco, California 94143, USA
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26
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Haas A. Reprogramming the phagocytic pathway--intracellular pathogens and their vacuoles (review). Mol Membr Biol 1998; 15:103-21. [PMID: 9859108 DOI: 10.3109/09687689809074522] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Phagocytic immune cells (particularly macrophages and neutrophils) take up and digest particles that have invaded our bodies. In doing so, they represent a very early line of defence against a microbial attack. During uptake, the particles are wrapped by a portion of the phagocyte's plasma membrane, and a new endocytic compartment, the phagosome, is formed. The typical fate of a phagosome is its fusion with lysosomes to yield a phagolysosome in which the particle is digested. Recent data show that some 'intracellular microorganisms' that can cause severe illnesses (tuberculosis, leprosy, legionnaire's disease and others) manage to reprogramme the host phagocytes not to deliver them to the lysosomal compartment. This probably results in increased survival of the pathogens. The analysis of the composition of such 'novel' compartments and research on the molecular mechanisms underlying the microbial interference with host cell functions are likely to yield important insights into: (1) which endocytic/phagocytic compartments phagocytes employ to handle ingested material in general; (2) how some pathogenic microorganisms can reprogramme the phagocytic pathway; and possibly (3) how infections caused by these microorganisms can be treated more effectively. Here, some studies are presented analysing which compartments intracellular pathogens inhabit and how microbes might be able to reprogramme their host cells.
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Affiliation(s)
- A Haas
- Department of Microbiology, Biocentre of the University, Würzburg, Germany
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27
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Abstract
Our understanding of both membrane traffic in mammalian cells and the cell biology of infection with intracellular pathogens has increased dramatically in recent years. In this review, we discuss the cell biology of the host-microbe interaction for four intracellular pathogens: Chlamydia spp., Legionella pneumophila, Mycobacterium spp., and the protozoan parasite Toxoplasma gondii. All of these organisms reside in vacuoles inside cells that have restricted fusion with host organelles of the endocytic cascade. Despite this restricted fusion, the vacuoles surrounding each pathogen display novel interactions with other host cell organelles. In addition to the effect of infection on host membrane traffic, we focus on these novel interactions and relate them where possible to nutrient acquisition by the intracellular organisms.
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Affiliation(s)
- A P Sinai
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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28
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Hackstadt T, Fischer ER, Scidmore MA, Rockey DD, Heinzen RA. Origins and functions of the chlamydial inclusion. Trends Microbiol 1997; 5:288-93. [PMID: 9234512 DOI: 10.1016/s0966-842x(97)01061-5] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Chlamydiae dissociate themselves from the endocytic pathway shortly after internalization by actively modifying the vacuole to become fusogenic with sphingomyelin-containing exocytic vesicles. Interaction with this secretory pathway appears to provide a pathogenic mechanism that allows chlamydiae to establish themselves in a site that is not destined to fuse with lysosomes.
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Affiliation(s)
- T Hackstadt
- Host-Parasite Interactions Section, National Institute of Allergy and Infections Diseases, NIH, Rocky Mountain Laboratories, Hamilton, MT 59840, USA.
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29
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Ojcius DM, Hellio R, Dautry-Varsat A. Distribution of endosomal, lysosomal, and major histocompatability complex markers in a monocytic cell line infected with Chlamydia psittaci. Infect Immun 1997; 65:2437-42. [PMID: 9169786 PMCID: PMC175338 DOI: 10.1128/iai.65.6.2437-2442.1997] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The intracellular fate of Chlamydia psittaci during infection of a monocytic cell line, THP1, was characterized. Cytochalasin D inhibited phagocytosis of latex beads but had no effect on infection by C. psittaci, and vacuoles expressed the transferrin receptor, suggesting accessibility to the endocytic pathway. Early Chlamydia-containing vacuoles expressed major histocompatibility complex (MHC) class I molecules, and most vacuoles fused with host cell lysosomes, since they expressed LAMP-1 and had acidic pHs. In cells prestimulated with gamma interferon, vacuoles also expressed MHC class II molecules, suggesting that the monocytes might effectively process Chlamydia-derived antigens for presentation by MHC class I and class II molecules.
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Affiliation(s)
- D M Ojcius
- Unité de Biologie des Interactions Cellulaires, CNRS URA 1960, Institut Pasteur, Paris, France.
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30
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van Ooij C, Apodaca G, Engel J. Characterization of the Chlamydia trachomatis vacuole and its interaction with the host endocytic pathway in HeLa cells. Infect Immun 1997; 65:758-66. [PMID: 9009339 PMCID: PMC176122 DOI: 10.1128/iai.65.2.758-766.1997] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Chlamydia trachomatis, an obligate intracellular parasite and a major human pathogen, invades eukaryotic host cells and replicates within a membrane-bound compartment (termed the vacuole or inclusion) in the cytoplasm of the host cell. In this report, we describe in detail the characteristics of the vacuole throughout the chlamydial life cycle in terms of the endocytic pathway, as determined by epifluorescent and confocal immunofluorescence microscopy. By indirect immunofluorescence, the transferrin receptor (TfR), a component of early endosomes, and the cation-independent mannose-6-phosphate receptor (CI-M6PR), a component of late endosomes, were found in close association with the chlamydial vacuole as early as 4 h postinfection (hpi) and as late as 20 hpi. Fluorescein isothiocyanate (FITC)-labeled Tf was also found to colocalize with the vacuole at 4, 12, and 20 hpi, indicating that exogenously added ligands can be transported to the region of the vacuole. Antibodies to several different lysosomal proteins failed to label the chlamydial vacuole at any time point during the life cycle. Indirect immunofluorescence of cells infected with chlamydiae stained with an antibody to the trans-Golgi network (TGN) protein TGN38 demonstrated that in infected cells, the integrity and structure of the TGN was altered. The rates of Tf recycling in infected and uninfected cells were compared by fluorescence microscopy and quantitated with 125I-Tf. While the rate of FITC-Tf recycling from endocytic compartments in chlamydia-infected cells did not appear different from that of uninfected cells, a small pool of FITC-Tf that had accumulated adjacent to the chlamydial vacuole recycled at a slower rate. Quantitation of Tf recycling with 125I-Tf showed that Tf was recycled more slowly in infected cells than in uninfected cells. The altered distribution of several endocytic pathway markers and the slowed Tf recycling are consistent with the hypothesis that the chlamydial vacuole interacts with the endocytic pathway of the host. These results furthermore suggest that the chlamydial vacuole does not correspond to a canonical endocytic compartment but that it is a unique and dynamic organelle that shares several characteristics with recycling endosomes of the host cell. Interactions with the early and/or late endosomal compartments, in addition to the Golgi apparatus, may provide a source of membrane or nutrients for the replicating organisms.
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Affiliation(s)
- C van Ooij
- Biomedical Sciences Program, University of California, San Francisco 94143-0654, USA
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31
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Rasmussen SJ, Eckmann L, Quayle AJ, Shen L, Zhang YX, Anderson DJ, Fierer J, Stephens RS, Kagnoff MF. Secretion of proinflammatory cytokines by epithelial cells in response to Chlamydia infection suggests a central role for epithelial cells in chlamydial pathogenesis. J Clin Invest 1997; 99:77-87. [PMID: 9011579 PMCID: PMC507770 DOI: 10.1172/jci119136] [Citation(s) in RCA: 402] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Chlamydia species infect epithelial cells at mucosal surfaces, and are major causes of sexually transmitted diseases. Infection is characterized by inflammation which is exacerbated upon reinfection, ultimately leading to tissue damage and scarring. Although central for the development of disease manifestations, little is known about the mechanisms that initiate and sustain the inflammatory response to Chlamydia. Infection of cervical and colonic epithelial cells with Chlamydia trachomatis and Chlamydia psittaci is shown in the present studies to upregulate mRNA expression and secretion of the proinflammatory cytokines IL-8, GRO alpha, GM-CSF, and IL-6. In contrast to the rapid, but transient, cytokine induction following infection with other invasive bacteria, the epithelial cytokine response to Chlamydia was delayed until 20-24 h after infection, persisted throughout the chlamydial growth cycle (2-4 d), and required bacterial protein synthesis. Moreover, epithelial cell lines and primary endocervical epithelial cells released IL-1alpha after Chlamydia infection, and increased secretion of the proinflammatory cytokines could be inhibited by anti-IL-1alpha. This suggests that IL-1alpha, released following lysis of infected epithelial cells, may amplify the inflammatory response by stimulating additional cytokine production by noninfected neighboring cells. These findings suggest a novel pathophysiologic concept wherein the acute host response to Chlamydia at mucosal surfaces is primarily initiated and sustained by epithelial cells, the first and major targets of chlamydial infection.
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Affiliation(s)
- S J Rasmussen
- Francis I. Proctor Foundation, University of California, San Francisco 94143, USA
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32
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Scidmore MA, Rockey DD, Fischer ER, Heinzen RA, Hackstadt T. Vesicular interactions of the Chlamydia trachomatis inclusion are determined by chlamydial early protein synthesis rather than route of entry. Infect Immun 1996; 64:5366-72. [PMID: 8945589 PMCID: PMC174531 DOI: 10.1128/iai.64.12.5366-5372.1996] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Chlamydiae replicate intracellularly within a vacuole that has recently been characterized as intersecting an exocytic pathway. One of the initial events during chlamydial infection is the expression of a chlamydial early gene product(s) that effectively isolates the inclusion from the endocytic-lysosomal pathway and makes it fusogenic with sphingomyelin-containing exocytic vesicles. Associated with this change in vesicular interaction is the delivery of the vacuole to the peri-Golgi region of the host cell. Inhibition of chlamydial early transcription or translation causes Chlamydia trachomatis-containing vesicles to remain dispersed throughout the cytoplasm, where they eventually fuse with lysosomes. Chlamydiae that have been internalized by Fc-mediated endocytosis also avoid lysosomal digestion by a mechanism that requires chlamydial protein synthesis. These results suggest that the vesicular interactions of the chlamydial inclusion are defined by parasite-directed modification of the endocytic vesicle rather than by the route of internalization.
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Affiliation(s)
- M A Scidmore
- Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana 59840, USA
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33
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Taraska T, Ward DM, Ajioka RS, Wyrick PB, Davis-Kaplan SR, Davis CH, Kaplan J. The late chlamydial inclusion membrane is not derived from the endocytic pathway and is relatively deficient in host proteins. Infect Immun 1996; 64:3713-27. [PMID: 8751921 PMCID: PMC174285 DOI: 10.1128/iai.64.9.3713-3727.1996] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Chlamydiae are obligate intracellular parasites which multiply within infected cells in a membrane-bound structure termed an inclusion. Newly internalized bacteria are surrounded by host plasma membrane; however, the source of membrane for the expansion of the inclusion is unknown. To determine if the membrane for the mature inclusion was derived by fusion with cellular organelles, we stained infected cells with fluorescent or electron-dense markers specific for organelles and examined inclusions for those markers. We observed no evidence for the presence of endoplasmic reticulum, Golgi, late endosomal, or lysosomal proteins in the inclusion. These data suggest that the expansion of the inclusion membrane, beginning 24 h postinoculation, does not occur by the addition of host proteins resulting from either de novo host synthesis or by fusion with preexisting membranes. To determine the source of the expanding inclusion membrane, antibodies were produced against isolated membranes from Chlamydia-infected mouse cells. The antibodies were demonstrated to be solely against Chlamydia-specified proteins by both immunoprecipitation of [35S]methionine-labeled extracts and Western blotting (immunoblotting). Techniques were used to semipermeabilize Chlamydia-infected cells without disrupting the permeability of the inclusion, allowing antibodies access to the outer surface of the inclusion membrane. Immunofluorescent staining demonstrated a ring-like fluorescence around inclusions in semipermeabilized cells, whereas Triton X-100-permeabilized cells showed staining throughout the inclusion. These studies demonstrate that the inclusion membrane is made up, in part, of Chlamydia-specified proteins and not of existing host membrane proteins.
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Affiliation(s)
- T Taraska
- Department of Pharmacology and Psychiatry, Veterans Administration Medical Center, Salt Lake City, Utah, USA
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34
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Heinzen RA, Scidmore MA, Rockey DD, Hackstadt T. Differential interaction with endocytic and exocytic pathways distinguish parasitophorous vacuoles of Coxiella burnetii and Chlamydia trachomatis. Infect Immun 1996; 64:796-809. [PMID: 8641784 PMCID: PMC173840 DOI: 10.1128/iai.64.3.796-809.1996] [Citation(s) in RCA: 305] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Coxiella burnetii and Chlamydia trachomatis are bacterial obligate intracellular parasites that occupy distinct vacuolar niches within eucaryotic host cells. We have employed immunofluorescence, cytochemistry, fluorescent vital stains, and fluid-phase markers in conjunction with electron, confocal, and conventional microscopy to characterize the vacuolar environments of these pathogens. The acidic nature of the C. burnetii-containing vacuole was confirmed by its acquisition of the acidotropic base acridine orange (AO). The presence of the vacuolar-type (H+) ATPase (V-ATPase) within the Coxiella vacuolar membrane was demonstrated by indirect immunofluorescence, and growth of C. burnetii was inhibited by bafilomycin A1 (Baf A), a specific inhibitor of the V-ATPase. In contrast, AO did not accumulate in C. trachomatis inclusions nor was the V-ATPase found in the inclusion membrane. Moreover, chlamydial growth was not inhibited by Baf A or the lysosomotropic amines methylamine, ammonium chloride, and chloroquine. Vacuoles harboring C. burnetii incorporated the fluorescent fluid- phase markers, fluorescein isothiocyanate-dextran (FITC-dex) and Lucifer yellow (LY), indicating trafficking between that vacuole and the endocytic pathway. Neither FITC-dex nor LY was sequestered by chlamydial inclusions. The late endosomal-prelysosomal marker cation-independent mannose 6-phosphate receptor was not detectable in the vacuolar membranes encompassing either parasite. However, the lysosomal enzymes acid phosphatase and cathepsin D and the lysosomal glycoproteins LAMP-1 and LAMP-2 localized to the C. burnetii vacuole but not the chlamydial vacuole. Interaction of C. trachomatis inclusions with the Golgi-derived vesicles was demonstrated by the transport of sphingomyelin, endogenously synthesized from C6-NBD-ceramide, to the chlamydial inclusion and incorporation into the bacterial cell wall. Similar trafficking of C-NBD-ceramide was not evident in C. burnetii-infected cells. Collectively, the data indicate that C. trachomatis replicates within a nonacidified vacuole that is disconnected from endosome-lysosome trafficking but may receive lipid from exocytic vesicles derived from the trans-Golgi network. These observations are in sharp contrast to those for C. burnetii, which by all criteria resides in a typical phagolysosome.
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Affiliation(s)
- R A Heinzen
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana 59840-2999,USA
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35
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Prospects for a vaccine against Chlamydia genital disease I. — Microbiology and pathogenesis. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/0020-2452(96)85299-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ting LM, Hsia RC, Haidaris CG, Bavoil PM. Interaction of outer envelope proteins of Chlamydia psittaci GPIC with the HeLa cell surface. Infect Immun 1995; 63:3600-8. [PMID: 7642297 PMCID: PMC173500 DOI: 10.1128/iai.63.9.3600-3608.1995] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The chlamydial life cycle involves the intimate interaction of components of the infectious elementary body (EB) surface with receptors on the susceptible eukaryotic cell plasma membrane. We have developed an in vitro ligand binding assay system for the identification and characterization of detergent-extracted EB envelope proteins capable of binding to glutaraldehyde-fixed HeLa cell surfaces. With this assay, the developmentally regulated cysteine-rich envelope protein Omp2 of Chlamydia psittaci strain guinea pig inclusion conjunctivitis was shown to bind specifically to HeLa cells. HeLa cells bound Omp2 selectively over other cell wall-associated proteins, including the major outer membrane protein, and the binding of Omp2 was abolished under conditions which alter its conformation. Furthermore, trypsin treatment, which reduces EB adherence, resulted in the proteolytic removal of a small terminal peptide of Omp2 at the EB surface and inactivated Omp2 in the ligand binding assay, while having a negligible effect on the major outer membrane protein. Collectively, our results suggest that Omp2 possesses the capacity to engage in a specific interaction with the host eukaryotic cell. We speculate that, since Omp2 is present only in the infectious EB form, the observed in vitro interaction may be representative of a determining step of the chlamydial pathogenic process.
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Affiliation(s)
- L M Ting
- Department of Microbiology and Immunology, University of Rochester Medical Center, New York 14642, USA
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Hackstadt T, Scidmore MA, Rockey DD. Lipid metabolism in Chlamydia trachomatis-infected cells: directed trafficking of Golgi-derived sphingolipids to the chlamydial inclusion. Proc Natl Acad Sci U S A 1995; 92:4877-81. [PMID: 7761416 PMCID: PMC41810 DOI: 10.1073/pnas.92.11.4877] [Citation(s) in RCA: 265] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Chlamydia trachomatis undergoes its entire life cycle within an uncharacterized intracellular vesicle that does not fuse with lysosomes. We used a fluorescent Golgi-specific probe, (N-[7-(4-nitrobenzo-2-oxa-1,3-diazole)]) aminocaproylsphingosine (C6-NBD-Cer), in conjunction with conventional fluorescence or confocal microscopy to identify interactions between the Golgi apparatus and the chlamydial inclusion. We observed not only a close physical association between the Golgi apparatus and the chlamydial inclusion but the eventual presence of a metabolite of this fluorescent probe associated with the chlamydiae themselves. Sphingomyelin, endogenously synthesized from C6-NBD-Cer, was specifically transported to the inclusion and incorporated into the cell wall of the intracellular chlamydiae. Incorporation of the fluorescent sphingolipid by chlamydiae was inhibited by brefeldin A. Chlamydiae therefore occupy a vesicle distal to the Golgi apparatus that receives anterograde vesicular traffic from the Golgi normally bound for the plasma membrane. Collectively, the data suggest that the chlamydial inclusion may represent a unique compartment within the trans-Golgi network.
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Affiliation(s)
- T Hackstadt
- Host-Parasite Interactions Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT 59840, USA
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Rockey DD, Heinzen RA, Hackstadt T. Cloning and characterization of a Chlamydia psittaci gene coding for a protein localized in the inclusion membrane of infected cells. Mol Microbiol 1995; 15:617-26. [PMID: 7783634 DOI: 10.1111/j.1365-2958.1995.tb02371.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Chlamydiae are obligate intracellular bacteria which occupy a non-acidified vacuole (the inclusion) throughout their developmental cycle. Little is known about events leading to the establishment and maintenance of the chlamydial inclusion membrane. To identify chlamydial proteins which are unique to the intracellular phase of the life cycle, an expression library of Chlamydia psittaci DNA was screened with convalescent antisera from infected animals and hyperimmune antisera generated against formalin-killed purified chlamydiae. Overlapping genomic clones were identified which expressed a 39 kDa protein only recognized by the convalescent sera. Sequence analysis of the clones identified two open reading frames (ORFs), one of which (ORF1) coded for a predicted 39 kDa gene product. The ORF1 sequence was amplified and fused to the malE gene of Escherichia coli and antisera were raised against the resulting fusion protein. Immunoblotting with these antisera demonstrated that the 39 kDa protein was present in lysates of infected cells and in reticulate bodies (RBs), but was at the limit of detection in lysates of purified C. psittaci elementary bodies. Fluorescence microscopy experiments demonstrated that this protein was localized in the inclusion membrane of infected HeLa cells, but was not detected on the developmental forms within the inclusion. Because the protein produced by ORF1 is deposited on the inclusion membrane of infected cells, this gene has been designated incA, (inclusion membrane protein A) and its gene product, IncA. In addition to the inclusion membrane, these antisera labelled structures that extended from the inclusion over the nucleus or into the cytoplasm of infected cells. Immunoblotting also demonstrated that IncA, in lysates of infected cells, had a migration pattern that seemed indicative of post-translational modification. This pattern was not observed in immunoblots of RBs or in the E. coli expressing IncA. Collectively, these data identify a chlamydial gene which codes for a protein that is released from RB and is localized in the inclusion membrane of infected cells.
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Affiliation(s)
- D D Rockey
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, Montana 59840, USA
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Abstract
Infection of genital epithelial cells by the closely related sexually transmitted pathogens Chlamydia trachomatis serovars E and L2 results in different clinical disease manifestations. Following entry into target host cells, individual vesicles containing chlamydiae fuse with one another to form one large inclusion. At the cellular level, the only obvious difference between these serovars is the time until inclusion maturation, which is 48 h for the invasive serovar L2 and 72 h for serovar E. To begin to define the intracellular events of these pathogens, the effect of cytoskeletal disruption on early endosome fusion and inclusion development in epithelial (HEC-1B) and fibroblast (McCoy) cells was analyzed by fluorescence microscopy. Disruption of microfilaments with cytochalasin D markedly reduced serovar E, but not serovar L2, infection of both cell lines. Conversely, microfilament as well as microtubule disruption, with colchicine or nocodazole, had no effect on serovar E inclusion development but resulted in the formation of multiple serovar L2 inclusions per cell during early and mid-development. Later in serovar L2 inclusion development (> 36 h postinfection), vesicles containing chlamydiae fused to form one large inclusion in the absence of an intact cytoskeleton. These results imply that (i) C. trachomatis serovar E may utilize a different pathway for uptake and development from serovar L2; (ii) these differences are consistent in both epithelial cells and fibroblasts; and (iii) the cytoskeleton plays a unique role in the infection of host cells by these two genital pathogens.
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Affiliation(s)
- N Schramm
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill 27599
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Rockey DD, Rosquist JL. Protein antigens of Chlamydia psittaci present in infected cells but not detected in the infectious elementary body. Infect Immun 1994; 62:106-12. [PMID: 8262615 PMCID: PMC186074 DOI: 10.1128/iai.62.1.106-112.1994] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Ocular infection of guinea pigs with the guinea pig inclusion conjunctivitis (GPIC) strain of Chlamydia psittaci produces a clinical condition representative of acute chlamydial conjunctivitis in humans. Guinea pigs which had recovered from two challenges with GPIC were used as a source of sera for the identification of antigens present in GPIC-infected tissue culture cells but absent in the infectious elementary body (EB). Immunoblots of lysates of infected HeLa cells probed with the convalescent-phase sera identified protein antigens of 22, 34, and 52 kDa (p22, p34, and p52, respectively) that were not detected in lysates of purified EB or in uninfected HeLa cells. Protein p22 was also not detected in lysates of purified reticulate bodies. Immunoblotting of lysates of HeLa cells infected with other chlamydiae demonstrated that the antigenicity of p22 and p34 was subspecies specific. Immunoblotting was also used to detect p22 and p34 in lysates of the conjunctivae of infected guinea pigs. Adsorption of convalescent-phase sera with GPIC EB produced a reagent with dominant reactivity toward p22, p34, and a 28-kDa EB protein. Immunofluorescent staining of GPIC-infected HeLa cells demonstrated that these adsorbed sera labeled the inclusion and inclusion membrane, with no apparent reactivity toward EB or reticulate bodies. Collectively, these data identify non-EB chlamydial components which may be released into the inclusion during intracellular growth.
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Affiliation(s)
- D D Rockey
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana 59840
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Raulston J, Davis C, Schmiel D, Morgan M, Wyrick P. Molecular characterization and outer membrane association of a Chlamydia trachomatis protein related to the hsp70 family of proteins. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)49438-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Majeed M, Kihlström E. Mobilization of F-actin and clathrin during redistribution of Chlamydia trachomatis to an intracellular site in eucaryotic cells. Infect Immun 1991; 59:4465-72. [PMID: 1937805 PMCID: PMC259064 DOI: 10.1128/iai.59.12.4465-4472.1991] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Immunofluorescence was used to examine the distribution of Chlamydia trachomatis serovars L2 and E, F-actin, and clathrin in infected McCoy and HeLa cells. After incubation at 4 degrees C, C. trachomatis serovar L2 was randomly distributed on the McCoy cell surface. After a temperature shift to 37 degrees C, chlamydiae redistributed, within 30 min, to one local aggregate in the central or perinuclear region of individual cells. About 90% of these aggregated chlamydiae were intracellularly localized, but some remained randomly distributed on the cell surface. Similar results were obtained with HeLa cells and C. trachomatis serovar E, except that the redistribution was slower in HeLa cells than in McCoy cells and fewer cells infected with serovar E exhibited a local aggregate than those infected with serovar L2. Cytochalasin D inhibited more than 90% of this local aggregation. Instead, in cytochalasin D-treated cells, the entry of chlamydiae was inhibited and the organisms became localized on the cell surface in a peripheral local aggregate that distributed in a manner similar to that of phalloidin-stained actin. In a double immunofluorescence assay, F-actin and clathrin aggregated correspondingly in time and position with central or perinuclear aggregation of chlamydiae. These results indicate that polymerized actin and clathrin participate in a rapid redistribution of chlamydiae to an intracellular aggregate.
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Affiliation(s)
- M Majeed
- Department of Clinical Bacteriology, Faculty of Health Sciences, Linköping University, Sweden
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Abstract
The obligately intracellular bacteria of the genus Chlamydia, which is only remotely related to other eubacterial genera, cause many diseases of humans, nonhuman mammals, and birds. Interaction of chlamydiae with host cells in vitro has been studied as a model of infection in natural hosts and as an example of the adaptation of an organism to an unusual environment, the inside of another living cell. Among the novel adaptations made by chlamydiae have been the substitution of disulfide-bond-cross-linked polypeptides for peptidoglycans and the use of host-generated nucleotide triphosphates as sources of metabolic energy. The effect of contact between chlamydiae and host cells in culture varies from no effect at all to rapid destruction of either chlamydiae or host cells. When successful infection occurs, it is usually followed by production of large numbers of progeny and destruction of host cells. However, host cells containing chlamydiae sometimes continue to divide, with or without overt signs of infection, and chlamydiae may persist indefinitely in cell cultures. Some of the many factors that influence the outcome of chlamydia-host cell interaction are kind of chlamydiae, kind of host cells, mode of chlamydial entry, nutritional adequacy of the culture medium, presence of antimicrobial agents, and presence of immune cells and soluble immune factors. General characteristics of chlamydial multiplication in cells of their natural hosts are reproduced in established cell lines, but reproduction in vitro of the subtle differences in chlamydial behavior responsible for the individuality of the different chlamydial diseases will require better in vitro models.
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Affiliation(s)
- J W Moulder
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
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Ryter A. Contribution of electron microscopy in the study of the interactions between pathogenic bacteria and their host cells. J Struct Biol 1990; 104:163-8. [PMID: 2088444 DOI: 10.1016/1047-8477(90)90072-k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Our knowledge on the functional anatomy of bacteria is based on the electron microscopic (EM) studies performed during the last forty years. Most pathogenic properties however cannot be visualized in EM because they are not related to defined structures. In contrast, EM studies have provided important data on the behaviour of pathogenic bacteria in their host cells. They have shown that many bacterial species have developed different stratagems to survive and multiply in their host cell. Some are even able to use the host cell machinery to move and invade adjacent cells.
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Affiliation(s)
- A Ryter
- Département de Biologie Moléculaire, Institut Pasteur, Paris, France
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Tauber AI, Pavlotsky N, Lin JS, Rice PA. Inhibition of human neutrophil NADPH oxidase by Chlamydia serovars E, K, and L2. Infect Immun 1989; 57:1108-12. [PMID: 2538397 PMCID: PMC313237 DOI: 10.1128/iai.57.4.1108-1112.1989] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The effects of Chlamydia trachomatis (serovars E, K, and L2) on human neutrophil activation were examined with respect to the organisms both as primary agonists and as agents that modulate cell responses to a second stimulus. Unopsonized chlamydiae alone, at ratios of 1.5 to 100 organisms per cell, failed to elicit changes in intracellular calcium or membrane depolarization or to stimulate the respiratory burst or degranulation during 60 min of incubation. Each of these functions except the respiratory burst was also normally activated when chlamydia-infected neutrophils were subsequently stimulated with formylmethionyl leucine phenylalanine or phorbol myristate acetate; the respiratory burst was inhibited 30 to 65%. Inhibition was dependent on live organisms and was maximal within 5 min of incubation. The organisms had no effect on the superoxide (O2-) assay, and the site of chlamydial inhibition was determined at the level of the NADPH oxidase itself, not at an intermediate step in the activation cascade. The mechanism of enzyme inactivation could not be determined. These results show that unopsonized chlamydiae do not elicit responses from infected neutrophils and suggest that microbicidal mechanisms other than those dependent on elaboration of toxic oxygen-derived species are required to inactivate chlamydiae.
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Affiliation(s)
- A I Tauber
- Department of Medicine, Boston City Hospital, Massachusetts
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Hodinka RL, Davis CH, Choong J, Wyrick PB. Ultrastructural study of endocytosis of Chlamydia trachomatis by McCoy cells. Infect Immun 1988; 56:1456-63. [PMID: 3131245 PMCID: PMC259421 DOI: 10.1128/iai.56.6.1456-1463.1988] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The entry of Chlamydia trachomatis into McCoy cells (fibroblasts) was studied by transmission electron microscopy. On adsorption of elementary bodies (EBs) to host cells at 37 degrees C, the EBs were bound primarily to preexisting cell-surface microvilli. They were also observed in coated pits located at the bases of the microvilli and along smooth surfaces of the host cells and were internalized within coated vesicles at this temperature. Postembedding immunogold labeling on Lowicryl thin sections with anti-clathrin antibody as the primary reagent revealed the gold marker localized in pits and vesicles containing chlamydiae. Some EBs were present in smooth-surfaced invaginations at or near the bases of microvilli and in vesicles devoid of distinguishable coat material. A similar entry process was observed with centrifugation-assisted inoculation of EBs onto the McCoy cells. Individual EBs were initially internalized into tightly bound endocytic vesicles. However, within 1 to 3 h postinfection, multiple C. trachomatis EBs were observed in large, loosely bound vesicles. Evidence suggests that vesicles containing C. trachomatis may have fused with one another early in the infectious process. These results indicate that chlamydiae can exploit the specific process of adsorptive endocytosis for entry into host cells and for translocation to a given intracellular destination, which may be different for each species.
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Affiliation(s)
- R L Hodinka
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill 27514
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Mørland B, Byrne GI, Jones TC. The effect of intracellular Chlamydia psittaci on lysosomal enzyme activities in mouse peritoneal macrophages. ACTA PATHOLOGICA, MICROBIOLOGICA, ET IMMUNOLOGICA SCANDINAVICA. SECTION C, IMMUNOLOGY 1987; 95:291-3. [PMID: 3442238 DOI: 10.1111/j.1699-0463.1987.tb00043.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Live or heat killed (30 min at 56 degrees C) Chlamydia psittaci elementary bodies (EB) were phagocytosed by mouse peritoneal macrophages. Inoculation with killed Chlamydia caused rises in three lysosomal enzyme activities tested, especially in acid phosphatase activity. In contrast, after infection with live Chlamydia, only a negligible increase was seen in acid phosphatase activity, and no change in the activities of beta-glucuronidase and cathepsin D was observed. It was concluded that regulation of lysosomal enzyme synthesis in macrophages may be linked to signals mediated by phago-lysosome fusions.
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Affiliation(s)
- B Mørland
- Council for Medical Research, Norwegian Research Council for Science and the Humanities, Oslo, Norway
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Kubo A, Sasada M, Nishimura T, Moriguchi T, Kakita T, Yamamoto K, Uchino H. Oxygen radical generation by polymorphonuclear leucocytes of beige mice. Clin Exp Immunol 1987; 70:658-63. [PMID: 2830072 PMCID: PMC1542194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Oxygen radical generation was measured using peritoneal exudate polymorphonuclear leucocytes (PMN) from a strain of beige mice, an animal model of the Chediak-Higashi syndrome. These PMN have been shown to exhibit delayed microbial killing and impaired phagosome-lysosome fusion. The amount of superoxide anion released by the PMN of the beige mice was similar to that released by the PMN of the control mice. The PMN of beige mice generated slightly less hydrogen peroxide than the control. Hydroxyl radical (.OH) generation and luminol-dependent chemiluminescence were significantly lowered in beige PMN stimulated with opsonized zymosan (OZ) or phorbol myristate acetate (PMA). Cytochalasin B-treated beige PMN showed a decreased ability to degranulate myeloperoxidase in response to OZ or PMA. We demonstrated the significant decrease in .OH generation and chemiluminescence in beige PMN, which might be one of the reasons to explain delayed microbial killing.
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Affiliation(s)
- A Kubo
- First Division of Internal Medicine, Faculty of Medicine, Kyoto University, Japan
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