Nicholas H Carbonetti

University of Maryland, Baltimore, Baltimore, Maryland, United States

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Publications (33)122.31 Total impact

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    Carey E Connelly, Yezhou Sun, Nicholas H Carbonetti
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    ABSTRACT: Throughout infection, pathogenic bacteria induce dramatic changes in host transcriptional repertoires. Understanding how bacterial factors influence host reprogramming will provide insight into disease pathogenesis. In the human respiratory pathogen Bordetella pertussis, the causative agent of whooping cough, pertussis toxin (PT) is a key virulence factor that promotes colonization, suppresses innate immune responses during early infection, and causes systemic disease symptoms. To determine the full extent of PT-associated gene regulation in the airways through the peak of infection, we measured global transcriptional profiles in the lungs of BALB/c mice infected with wild type (WT) or PT-deficient (ΔPT) B. pertussis. ΔPT bacteria were inoculated at a dose equivalent to WT and at a high dose (ΔPT(high)) to distinguish effects caused by higher bacterial loads achieved in the WT infection from effects associated with PT. Results demonstrated that PT was associated with significant upregulation of immune and inflammatory response genes, as well as several other genes implicated in airway pathology. In contrast to early, transient responses observed in ΔPT(high) infection, WT infection induced prolonged expression of inflammatory genes and increased the extent and duration of lung histopathology. In addition, administration of purified PT to ΔPT(high)-infected mice one day after bacterial inoculation exacerbated and prolonged inflammatory responses and airway pathology. These data indicate that PT is associated not only with exacerbated host airway responses during peak B. pertussis infection, but may also inhibit host mechanisms of attenuating and resolving inflammation in the airways, suggesting possible links between PT and pertussis disease symptoms.
    Infection and immunity 10/2012; · 4.21 Impact Factor
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    Zoë E V Worthington, Nico Van Rooijen, Nicholas H Carbonetti
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    ABSTRACT: The epidemiological and pathogenic relationship between Bordetella pertussis and Bordetella parapertussis, the two causes of whooping cough (pertussis), is unclear. We hypothesized that B. pertussis, due to its immunosuppressive activities, might enhance B. parapertussis infection when the two species were present in a coinfection of the respiratory tract. The dynamics of this relationship were examined using the mouse intranasal inoculation model. Infection of the mouse respiratory tract by B. parapertussis was not only enhanced by the presence of B. pertussis, but B. parapertussis significantly outcompeted B. pertussis in this model. Staggered inoculation of the two organisms revealed that the advantage for B. parapertussis is established at an early stage of infection. Coadministration of PT enhanced B. parapertussis single infection, but had no effect on mixed infections. Mixed infection with a PT-deficient B. pertussis strain did not enhance B. parapertussis infection. Interestingly, the depletion of airway macrophages reversed the competitive relationship between these two organisms, but the depletion of neutrophils had no effect on mixed infection or B. parapertussis infection. We conclude that B. pertussis, through the action of PT, can enhance a B. parapertussis infection, possibly by an inhibitory effect on innate immunity.
    FEMS Immunology & Medical Microbiology 06/2011; 63(1):119-28. · 2.68 Impact Factor
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    ABSTRACT: Pertussis (whooping cough) is frequently complicated by concomitant infections with respiratory viruses. Here we report the effect of Bordetella pertussis infection on subsequent influenza virus (PR8) infection in mouse models and the role of pertussis toxin (PT) in this effect. BALB/c mice infected with a wild-type strain of B. pertussis (WT) and subsequently (up to 14 days later) infected with PR8 had significantly increased pulmonary viral titers, lung pathology and mortality compared to mice similarly infected with a PT-deficient mutant strain (ΔPT) and PR8. Substitution of WT infection by intranasal treatment with purified active PT was sufficient to replicate the exacerbating effects on PR8 infection in BALB/c and C57/BL6 mice, but the effects of PT were lost when toxin was administered 24 h after virus inoculation. PT had no effect on virus titers in primary cultures of murine tracheal epithelial cells (mTECs) in vitro, suggesting the toxin targets an early immune response to increase viral titers in the mouse model. However, type I interferon responses were not affected by PT. Whole genome microarray analysis of gene expression in lung tissue from PT-treated and control PR8-infected mice at 12 and 36 h post-virus inoculation revealed that PT treatment suppressed numerous genes associated with communication between innate and adaptive immune responses. In mice depleted of alveolar macrophages, increase of pulmonary viral titers by PT treatment was lost. PT also suppressed levels of IL-1β, IL-12, IFN-γ, IL-6, KC, MCP-1 and TNF-α in the airways after PR8 infection. Furthermore PT treatment inhibited early recruitment of neutrophils and NK cells to the airways. Together these findings demonstrate that infection with B. pertussis through PT activity predisposes the host to exacerbated influenza infection by countering protective innate immune responses that control virus titers.
    PLoS ONE 01/2011; 6(4):e19016. · 3.73 Impact Factor
  • Zoë E.V. Worthington, Nico Van Rooijen, Nicholas H. Carbonetti
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    ABSTRACT: The epidemiological and pathogenic relationship between Bordetella pertussis and Bordetella parapertussis, the two causes of whooping cough (pertussis), is unclear. We hypothesized that B. pertussis, due to its immunosuppressive activities, might enhance B. parapertussis infection when the two species were present in a coinfection of the respiratory tract. The dynamics of this relationship were examined using the mouse intranasal inoculation model. Infection of the mouse respiratory tract by B. parapertussis was not only enhanced by the presence of B. pertussis, but B. parapertussis significantly outcompeted B. pertussis in this model. Staggered inoculation of the two organisms revealed that the advantage for B. parapertussis is established at an early stage of infection. Coadministration of PT enhanced B. parapertussis single infection, but had no effect on mixed infections. Mixed infection with a PT‐deficient B. pertussis strain did not enhance B. parapertussis infection. Interestingly, the depletion of airway macrophages reversed the competitive relationship between these two organisms, but the depletion of neutrophils had no effect on mixed infection or B. parapertussis infection. We conclude that B. pertussis, through the action of PT, can enhance a B. parapertussis infection, possibly by an inhibitory effect on innate immunity.
    FEMS Immunology & Medical Microbiology 01/2011; 63(1). · 2.68 Impact Factor
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    Nicholas H Carbonetti
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    ABSTRACT: Pertussis toxin and adenylate cyclase toxin are two important virulence factors of Bordetella pertussis, the bacterial cause of the respiratory disease pertussis or whooping cough. In addition to studies on the structure, function and role in pathogenesis of these two toxins, they are both used as cell biology tools for a variety of applications owing to their ability to enter mammalian cells, perform enzymatic activities and modify cell signaling events. In this article, recent data from the research literature that enhance our understanding of the nature of these two toxins, their role in the pathogenesis of B. pertussis infection and disease, particularly in modulating host immune responses, and their use as tools for other areas of research will be outlined.
    Future Microbiology 03/2010; 5(3):455-69. · 4.02 Impact Factor
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    Charlotte Andreasen, Nicholas H Carbonetti
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    ABSTRACT: Pertussis is an acute respiratory disease caused by the bacterium Bordetella pertussis, for which humans are the only known reservoir. During infection, B. pertussis releases several toxins, including pertussis toxin (PT) and adenylate cyclase toxin (ACT), which have both been shown to play roles in promoting bacterial growth during early infection in a mouse model. Furthermore, in vitro and in vivo studies suggest that PT and ACT affect neutrophil chemotaxis and/or function, thereby altering the innate immune response. In this study we depleted animals of neutrophils to investigate whether neutrophils play a protective role during B. pertussis infection in mice. In addition, by infection with toxin-deficient strains, we investigated whether neutrophils are the main targets for PT and/or ACT activity in promoting bacterial growth. Surprisingly, we found no role for neutrophils during B. pertussis infection in naïve mice. However, in previously infected (immune) mice or in mice receiving immune serum, we observed a significant role for neutrophils during infection. Furthermore, in this immune mouse model our evidence indicates that neutrophils appear to be the main target cells for ACT, but not for PT.
    Infection and immunity 01/2009; 77(3):1182-8. · 4.21 Impact Factor
  • Charlotte Andreasen, Daniel A. Powell, Nicholas H. Carbonetti
    PLoS ONE 01/2009; 4(9). · 3.73 Impact Factor
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    Charlotte Andreasen, Daniel A Powell, Nicholas H Carbonetti
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    ABSTRACT: In a mouse model of respiratory tract infection by Bordetella pertussis, bacteria multiply in the airways over the first week and are then cleared over the next 3-4 weeks by the host immune response. Pertussis toxin (PT), a virulence factor secreted exclusively by B. pertussis, promotes bacterial growth in the airways by suppression and modulation of host immune responses. By comparison of wild type and PT-deficient strains, we examined the role of PT in modulating airway cytokine and chemokine responses affecting neutrophil recruitment during B. pertussis infection in mice. We found that, despite early inhibition of neutrophil recruitment by PT, high numbers of neutrophils were recruited to the airways by 4 days post-infection with the wild type strain, but not with the PT-deficient strain, and that this correlated with upregulation of neutrophil-attracting chemokine gene expression. In addition, there was similar upregulation of genes expressing the cytokines IL-17A (IL-17), TNF-alpha and IFN-gamma, indicating a mixed Th1/Th17 response. Expression of IL-6, a cytokine involved in Th17 induction, was upregulated earlier than the IL-17 response. We showed that PT, rather than bacterial numbers, was important for induction of these responses. Flow cytometric analysis revealed that the IL-17-producing cells were macrophages and neutrophils as well as T cells, and were present predominantly in the airways rather than the lung tissue. Antibody neutralization of IL-17 significantly reduced chemokine gene expression and neutrophil recruitment to the airways, but only modestly increased peak bacterial loads. These data indicate that PT stimulates inflammatory responses by induction of Th1- and Th17-associated cytokines, including IL-17, during B. pertussis infection in mice, but a role for IL-17 in protection against the infection remains to be established.
    PLoS ONE 01/2009; 4(9):e7079. · 3.73 Impact Factor
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    Charlotte Andreasen, Nicholas H Carbonetti
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    ABSTRACT: Pertussis is an acute respiratory disease of humans caused by the bacterium Bordetella pertussis. Pertussis toxin (PT) plays a major role in the virulence of this pathogen, including important effects that it has soon after inoculation. Studies in our laboratory and other laboratories have indicated that PT inhibits early neutrophil influx to the lungs and airways in response to B. pertussis respiratory tract infection in mice. Previous in vitro and in vivo studies have shown that PT can affect neutrophils directly by ADP ribosylating G(i) proteins associated with surface chemokine receptors, thereby inhibiting neutrophil migration in response to chemokines. However, in this study, by comparing responses to wild-type (WT) and PT-deficient strains, we found that PT has an indirect inhibitory effect on neutrophil recruitment to the airways in response to infection. Analysis of lung chemokine expression indicated that PT suppresses early neutrophil recruitment by inhibiting chemokine upregulation in alveolar macrophages and other lung cells in response to B. pertussis infection. Enhancement of early neutrophil recruitment to the airways in response to WT infection by addition of exogenous keratinocyte-derived chemokine, one of the dominant neutrophil-attracting chemokines in mice, further revealed an indirect effect of PT on neutrophil chemotaxis. Additionally, we showed that intranasal administration of PT inhibits lipopolysaccharide-induced chemokine gene expression and neutrophil recruitment to the airways, presumably by modulation of signaling through Toll-like receptor 4. Collectively, these results demonstrate how PT inhibits early inflammatory responses in the respiratory tract, which reduces neutrophil influx in response to B. pertussis infection, potentially providing an advantage to the pathogen in this interaction.
    Infection and immunity 10/2008; 76(11):5139-48. · 4.21 Impact Factor
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    Roger D Plaut, Nicholas H Carbonetti
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    ABSTRACT: Pertussis toxin (PT), an AB5 exotoxin and important virulence factor of Bordetella pertussis, is hypothesized to traffic along a retrograde transport pathway in mammalian cells. This pathway includes endosomal uptake, transport to the Golgi complex and endoplasmic reticulum (ER), dissociation of the holotoxin in the ER and translocation of the A subunit (S1) to the cytosol, where it ADP-ribosylates its G protein targets. In this study, PT was visualized in the Golgi complex by immunofluorescence microscopy, but transport beyond the Golgi could not be detected by this method. To gain evidence for the retrograde pathway, peptide tags with target sites for tyrosine sulfation (a trans-Golgi network-specific activity) and N-glycosylation (an ER-specific activity) were added to either S1 or a B subunit (S4) of PT. Modified PT retained in vitro enzymatic and cellular activity as assessed by ADP-ribosylation assays. Peptide-tagged PT subunits were found to be modified by tyrosine sulfation, and, at later time points, by N-glycosylation. Appearance of sulfated PT subunits was inhibited by pretreatment of cells with brefeldin A. In some cell types, much of the S4 glycosylation, but not that of S1, was resistant to endoglycosidase H, suggesting that, subsequent to core N-glycosylation in the ER, S4 was transported anterograde to the Golgi, where further glycosylation occurred. When cells were pretreated with methyl-beta-cyclodextrin, sulfation of PT subunits and PT cytotoxicity were reduced, suggesting that PT transport is dependent on cellular cholesterol content. These data support a retrograde pathway for PT intracellular transport.
    Cellular Microbiology 06/2008; 10(5):1130-9. · 4.81 Impact Factor
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    Zoë E V Worthington, Nicholas H Carbonetti
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    ABSTRACT: Pertussis toxin (PT) is an important virulence factor produced by Bordetella pertussis. PT holotoxin comprises one enzymatically active A subunit (S1), associated with a pentamer of B subunits. PT is an ADP-ribosyltransferase that modifies several mammalian heterotrimeric G proteins. Some bacterial toxins are believed to undergo retrograde intracellular transport through the Golgi apparatus to the endoplasmic reticulum (ER). The ER-associated degradation (ERAD) pathway involves the removal of misfolded proteins from the ER and degradation upon their return to the cytosol; this pathway may be exploited by PT and other toxins. In the cytosol, ERAD substrates are ubiquitinated at lysine residues, targeting them to the proteasome for degradation. We hypothesize that S1 avoids ubiquitination and proteasome degradation due to its lack of lysine residues. We predicted that the addition of lysine residues would reduce PT toxicity by allowing ubiquitination and degradation to occur. Variant forms of PT were engineered, replacing one, two, or three arginines with lysines in a variety of locations on S1. Several variants were identified with wild-type in vitro enzymatic activity but reduced cellular activity, consistent with our hypothesis. Significant recovery of the cellular activity of these variants was observed when CHO cells were pretreated with a proteasome inhibitor. We concluded that the replacement of arginine residues with lysine in the S1 subunit of PT renders the toxin subject to proteasomal degradation, suggesting that wild-type PT avoids proteasome degradation due to an absence of lysine residues.
    Infection and Immunity 07/2007; 75(6):2946-53. · 4.07 Impact Factor
  • Nicholas H Carbonetti
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    ABSTRACT: Bordetella pertussis infection of the airways causes the disease pertussis (or whooping cough). The infection can be fatal in infants, but in older children, adolescents and adults usually results in a chronic cough of varying severity that persists long after clearance of the infection. The cause of the cough is unknown, but is presumably a result of the pathogenic effects of one or more of the various virulence factors produced by this bacterium. Accumulating recent evidence indicates that the majority of the virulence-associated effects of these factors is devoted to suppression and modulation of the host immune response, which can be skewed towards the recently described Th17 profile. Although the interplay between virulence factors and immune mechanisms might have evolved to benefit both partners in the host-pathogen interaction, it could also contribute to the severe disease pathology associated with this infection.
    Current Opinion in Pharmacology 07/2007; 7(3):272-8. · 5.44 Impact Factor
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    ABSTRACT: Pertussis toxin (PT), a secreted virulence factor of Bordetella pertussis, ADP ribosylates mammalian G(i) proteins and plays an important early role in respiratory tract infection by this pathogen in a mouse intranasal infection model. To test the hypothesis that PT targets resident airway macrophages (AM) to promote this infection, we depleted AM by intranasal administration of liposome-encapsulated clodronate prior to bacterial inoculation. This treatment enhanced respiratory tract infection by B. pertussis, even though it also induced a rapid influx of neutrophils to the airways. Strikingly, AM depletion also enhanced infection by mutant strains deficient in PT production or activity to the same level as the wild-type infection, indicating that AM may be the primary target cells for PT in promoting infection. The enhancing effect of clodronate-liposome treatment on infection (i) was shown to be due to macrophage depletion rather than neutrophil influx; (ii) was observed for both tracheal infection and lung infection; (iii) was observed during the early and peak phases of the infection but was lost by day 14 postinoculation, during clearance of the infection; (iv) persisted for at least 1 week (prior to bacterial inoculation); and (v) was equivalent in magnitude to the effect of PT pretreatment and the effects were not additive, consistent with the idea that PT targets AM. We found that PT efficiently ADP ribosylated AM G proteins both in vitro and after intranasal administration of PT in mice and that the duration of G protein modification in vivo was equivalent to the duration of the enhancing effect of PT treatment on the bacterial infection. Collectively, these observations indicate that PT targets AM to promote early infection of the respiratory tract by B. pertussis.
    Infection and Immunity 05/2007; 75(4):1713-20. · 4.07 Impact Factor
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    ABSTRACT: We observed a remarkable reduction in the frequency and immunosuppressive activity of splenic CD4+CD25+ T cells in C57BL/6 mice with MOG33-55-induced experimental autoimmune encephalomyelitis (EAE). Our study revealed that pertussis toxin (PTx), one component of the immunogen used to induce murine EAE, was responsible for down-regulating splenic CD4+CD25+ cells. Treatment of normal BALB/c mice with PTx in vivo reduced the frequency, suppressive activity and FoxP3 expression by splenic CD4+CD25+ T cells. However, PTx treatment did not alter the expression of characteristic phenotypic markers (CD45RB, CD103, GITR and CTLA-4) and did not increase the expression of CD44 and CD69 by the residual splenic and lymph node CD4+CD25+ T cells. This property of PTx was attributable to its ADP-ribosyltransferase activity. PTx did not inhibit suppressive activity of purified CD4+CD25+ T regulatory (Treg) cells in vitro, but did so in vivo, presumably due to an indirect effect. Although the exact molecular target of PTx that reduces Treg activity remains to be defined, our data suggests that alteration of both distribution and function of splenic immunocytes should play a role. This study concludes that an underlying cause for the immunological adjuvanticity of PTx is down-regulation of Treg cell number and function.
    European Journal of Immunology 04/2006; 36(3):671-80. · 4.97 Impact Factor
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    ABSTRACT: Previously we found that pertussis toxin (PT), an exotoxin virulence factor produced by Bordetella pertussis, plays an important early role in colonization of the respiratory tract by this pathogen, using a mouse intranasal infection model. In this study, we examined the early role played by another exotoxin produced by this pathogen, adenylate cyclase toxin (ACT). By comparing a wild-type strain to a mutant strain (DeltaCYA) with an in-frame deletion of the cyaA gene encoding ACT, we found that the lack of ACT confers a significant peak (day 7) colonization defect (1 to 2 log(10)). In mixed-infection experiments, the DeltaCYA strain was significantly outcompeted by the wild-type strain, and intranasal administration of purified ACT did not increase colonization by DeltaCYA. These data suggest that ACT benefits the bacterial cells that produce it and, unlike PT, does not act as a soluble factor benefiting the entire infecting bacterial population. Comparison of lower respiratory tract infections over the first 4 days after inoculation revealed that the colonization defect of the PT deletion strain was apparent earlier than that of DeltaCYA, suggesting that PT plays an earlier role than ACT in the establishment of B. pertussis infection. Examination of cells in the bronchoalveolar lavage fluid of infected mice revealed that, unlike PT, ACT does not appear to inhibit neutrophil influx to the respiratory tract early after infection but may combat neutrophil activity once influx has occurred.
    Infection and Immunity 06/2005; 73(5):2698-703. · 4.07 Impact Factor
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    ABSTRACT: Pertussis toxin (PT) is an exotoxin virulence factor produced by Bordetella pertussis, the causative agent of whooping cough. PT consists of an active subunit (S1) that ADP-ribosylates the alpha subunit of several mammalian G proteins, and a B oligomer (S2-S5) that binds glycoconjugate receptors on cells. PT appears to enter cells by endocytosis, and retrograde transport through the Golgi apparatus may be important for its cytotoxicity. A previous study demonstrated that proteolytic processing of S1 occurs after PT enters mammalian cells. We sought to determine whether this proteolytic processing of S1 is necessary for PT cytotoxicity. Protease inhibitor studies suggested that S1 processing may involve a metalloprotease, and processing does not involve furin, a mammalian cell protease that cleaves several other bacterial toxins. However, inhibitor studies showed a general lack of correlation of S1 processing with PT cellular activity. A combination of replacement, insertion and deletion mutations in the C-terminal region of S1, as well as mass spectrometry data, suggested that the cleavage site is located around residue 203-204, but that cleavage is not strongly sequence-dependent. Processing of S1 was abolished by each of 3 overlapping 8 residue deletions just downstream of the putative cleavage site, but not by smaller deletions in the same region. Processing of the various mutant forms of PT did not correlate with cellular activity of the toxin, nor with the ability of the bacteria producing them to infect the mouse respiratory tract. In addition, S1 processing was not detected in transfected cells expressing S1, even though S1 was fully active in these cells. S1 processing is not essential for the cellular activity of PT. This distinguishes it from the processing of various other bacterial toxins, which has been shown to be important for their cytotoxicity. S1 processing may be mediated primarily by a metalloprotease, but the cleavage site on S1 is not sequence-dependent and processing appears to depend on the general topology of the protein in that region, indicating that multiple proteases may contribute to this cleavage.
    BMC Microbiology 02/2005; 5:7. · 3.10 Impact Factor
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    ABSTRACT: Pertussis toxin (PT), a virulence factor secreted by Bordetella pertussis, contributes to respiratory tract infection and disease caused by this pathogen. By comparing a wild-type (WT) B. pertussis strain to a mutant strain with an in-frame deletion of the ptx genes encoding PT (DeltaPT), we recently found that the lack of PT confers a significant defect in respiratory tract colonization in mice after intranasal inoculation. In this study, we analyzed serum antibody responses in mice infected with the WT or DeltaPT strain and found that infection with the DeltaPT strain elicited greater responses to several B. pertussis antigens than did infection with the WT, despite the lower colonization level achieved by the DeltaPT strain. The same enhanced antibody response was observed after infection with a strain expressing an enzymatically inactive PT; but this response was not observed after infection with B. pertussis mutant strains lacking filamentous hemagglutinin or adenylate cyclase toxin, nor when purified PT was administered with the DeltaPT inoculum, indicating a specific role for PT activity in this immunosuppressive effect. In particular, there were consistent strong serum antibody responses to one or more low-molecular-weight antigens after infection with the DeltaPT strain. These antigens were Bvg independent, membrane localized, and also expressed by the closely related pathogens Bordetella parapertussis and Bordetella bronchiseptica. Two-dimensional gel electrophoresis and mass spectrometry were used to identify one of the immunodominant low-molecular-weight antigens as a protein with significant sequence homology to peptidoglycan-associated lipoprotein in several other gram-negative bacterial species. However, a serum antibody response to this protein alone did not protect mice against respiratory tract infection by B. pertussis.
    Infection and Immunity 07/2004; 72(6):3350-8. · 4.07 Impact Factor
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    ABSTRACT: Levels of pulmonary and activation-regulated chemokine (PARC) mRNA and protein are increased in the lungs of patients with pulmonary fibrosis. The purpose of this study was to establish whether PARC could be directly involved in development of pulmonary fibrosis by stimulating collagen production in lung fibroblasts. Exposure to PARC increased production of collagen mRNA and protein by 3- to 4-fold in normal adult lung and dermal fibroblast cells. Collagen mRNA transiently increased after 3-6 h of activation with PARC, with an increase in collagen protein detected after 24 h of activation. At the same time, PARC had less pronounced effect on fibroblast proliferation, not exceeding 50% increase over control nonstimulated cells. PARC intracellular signaling led to activation of ERK1/2, but not p38, in fibroblasts; pharmacologic inhibition of ERK, but not p38, also blocked PARC's effect on collagen production. Inhibition experiments with pertussis toxin suggested that PARC receptor is G protein-coupled. Thus, PARC is a member of the CC chemokine family that acts directly as a profibrotic factor.
    American Journal of Respiratory Cell and Molecular Biology 01/2004; 29(6):743-9. · 4.15 Impact Factor
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    ABSTRACT: In this study, we sought to determine whether pertussis toxin (PT), an exotoxin virulence factor produced exclusively by Bordetella pertussis, is important for colonization of the respiratory tract by this pathogen by using a mouse intranasal infection model. By comparing a wild-type Tohama I strain to a mutant strain with an in-frame deletion of the ptx genes encoding PT (deltaPT), we found that the lack of PT confers a significant peak (day 7) colonization defect (1 to 2 log(10) units) over a range of bacterial inoculum doses and that this defect was apparent within 1 to 2 days postinoculation. In mixed-strain infection experiments, the deltaPT strain showed no competitive disadvantage versus the wild-type strain and colonized at higher levels than in the single-strain infection experiments. To test the hypothesis that soluble PT produced by the wild-type strain in mixed infections enhanced respiratory tract colonization by deltaPT, we coadministered purified PT with the deltaPT inoculum and found that colonization was increased to wild-type levels. This effect was not observed when PT was coadministered via a systemic route. Intranasal administration of purified PT up to 14 days prior to inoculation with deltaPT significantly increased bacterial colonization, but PT administration 1 day after bacterial inoculation did not enhance colonization versus a phosphate-buffered saline control. Analysis of bronchoalveolar lavage fluid samples from mice infected with either wild-type or deltaPT strains at early times after infection revealed that neutrophil influx to the lungs 48 h postinfection was significantly greater in response to deltaPT infection, implicating neutrophil chemotaxis as a possible target of PT activity promoting B. pertussis colonization of the respiratory tract.
    Infection and Immunity 12/2003; 71(11):6358-66. · 4.07 Impact Factor
  • N H Carbonetti, R G Tuskan, G K Lewis
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    ABSTRACT: CD8+ cytolytic T lymphocytes (CTL) are almost certainly an important component of a potentially protective immune response to HIV. To test the ability of pertussis toxin (PT) to deliver an HIV-derived major histocompatibility complex (MHC) class I peptide for CTL stimulation, we constructed a fusion of the gp120 P18-I10 CTL epitope with a genetically detoxified derivative of PT (PT9K/129G) and assayed this fusion for its ability to stimulate a gp120-specific CTL response in vitro and in vivo. Antigen-presenting cells incubated with this fusion protein were lysed by P18-I10-specific CTL in vitro and this activity was shown to be MHC class I restricted. The activity was inhibited by brefeldin A but was not inhibited by proteasome inhibitors, possibly because PT undergoes retrograde intracellular transport through the Golgi apparatus to the endoplasmic reticulum and delivers epitopes directly to nascent class I molecules. Mice immunized intraperitoneally with a single dose of the fusion protein without adjuvant raised a strong gp120-specific CTL response in the spleen. This CTL response was dependent on (1) the dose of fusion administered, (2) the fusion of the epitope with the toxin (since coadministration of peptide and toxin gave no response), and (3) the activity of CD8+ cells. These data demonstrate that this detoxified derivative to PT, which is already a component of a licensed vaccine for humans, could represent a useful vaccine vector molecule for stimulation of HIV-specific CTL responses.
    AIDS Research and Human Retroviruses 07/2001; 17(9):819-27. · 2.71 Impact Factor

Publication Stats

673 Citations
122.31 Total Impact Points

Institutions

  • 1993–2011
    • University of Maryland, Baltimore
      • Department of Microbiology and Immunology
      Baltimore, Maryland, United States
  • 2007
    • Freie Universität Berlin
      Berlín, Berlin, Germany
  • 1995
    • U.S. Food and Drug Administration
      Washington, Washington, D.C., United States