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1.
Pigment Cell Melanoma Res ; 37(2): 309-315, 2024 Mar.
Article in English | MEDLINE | ID: mdl-37975535

ABSTRACT

The immune-modulating protein CD52 attenuates lymphocyte function and is associated with autoimmune disorders, for example, multiple sclerosis (MS). CD52 represents a therapeutic target in MS and chronic lymphocytic leukemia (CLL). Its expression has prognostic and predictive value in CLL and is prognostic in breast cancer. Its significance in melanoma is unclear. We analyzed CD52 mRNA expression data from tumor bulk tissues of N = 445 untreated melanoma patients from The Cancer Genome Atlas (TCGA) Research Network and of N = 121 melanoma patients undergoing anti-PD-1 immune checkpoint blockade (ICB) with regard to outcome (overall survival [OS], disease control [DC], and progression-free survival [PFS]), single-cell RNA-Seq data of N = 4645 cells from N = 19 melanoma tissues, and N = 15,457 cells from normal skin provided by N = 5 donors. Higher CD52 mRNA expression was associated with favorable OS (hazard ratio (HR) = 0.820, [95% CI 0.734-0.916], p < .001) in non-ICB-treated melanoma and with PFS (HR = 0.875, [95% CI 0.775-0.989], p = .033) and DC (p = .005) in ICB-treated melanoma. CD52 expression correlated significantly with distinct immune cell subsets and correlated negatively with immune checkpoint expression in T cells. Moreover, our results suggest CD52 expression by a certain type of tissue-resident macrophages. CD52 mRNA was expressed in a small subgroup (8%) of immune checkpoint coexpressing melanoma cells. CD52 expression is associated with features of ICB response in melanoma. Concomitant ICB and anti-CD52 treatment requires critical review.


Subject(s)
Leukemia, Lymphocytic, Chronic, B-Cell , Melanoma , Humans , Melanoma/drug therapy , Melanoma/genetics , Immune Checkpoint Inhibitors/therapeutic use , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Proportional Hazards Models , RNA, Messenger/genetics , CD52 Antigen/genetics
2.
Laryngorhinootologie ; 103(1): 25-34, 2024 01.
Article in German | MEDLINE | ID: mdl-37726020

ABSTRACT

Choanal atresia (CA) is a rare congenital anomaly of the nasal airway with an incidence of 1/5000 to 1/9000, which may occur unilateral (uCA) or bilateral (bCA). bCA manifests as an acute emergency immediately after birth by airway obstruction and paradoxical cyanosis, whereas uCA may present with a heterogeneous clinical picture in addition to unilateral nasal airway obstruction. Fiber endoscopic examination and cranial computed tomography are the gold standard in the diagnosis of CA. CA often occurs in association with congenital malformation syndromes, among which CHARGE syndrome stands out. Due to cardiopulmonary instability and difficult intubation conditions, syndromic CA patients should be considered as a separate risk group. After securing the airway, bCA must be treated surgically without delay, whereas correction of uCA should not be performed until after six months of age. Endoscopic techniques are the surgical standard in the treatment of CA. Different approaches can be distinguished: transnasal puncture of the atresia plate with subsequent extension medially and laterally, creation of a septal window with subsequent resection of the posterior vomer and atresia plate, and elevation of mucoperiosteal flaps with subsequent opening of the atresia plate. The transpalatal approach should only be employed in anatomically complex cases. The use of conventional choanal stents in the primary treatment of CA is increasingly rejected and should be reserved for high-risk constellations. Similarly, local application of mitomycin C should be avoided.


Subject(s)
Choanal Atresia , Nasal Obstruction , Humans , Choanal Atresia/diagnosis , Choanal Atresia/surgery , Endoscopy/methods , Stents , Tomography, X-Ray Computed
3.
Clin Epigenetics ; 15(1): 112, 2023 07 06.
Article in English | MEDLINE | ID: mdl-37415208

ABSTRACT

BACKGROUND: The majority of patients with recurrent or metastasized head and neck squamous cell carcinoma (HNSCC) do not benefit from immune checkpoint blockade (ICB) while several patients experience severe and persistent immune-mediated side effects. Therefore, predictive biomarkers are urgently needed to allow for a personalized treatment. In this study, we investigated DNA methylation of the immune checkpoint gene CTLA4 with regard to its predictive value. METHODS: We analyzed CTLA4 promoter methylation in tumors of HNSCC patients (N = 29) treated with ICB at the University Medical Center Bonn with regard to response to ICB and progression-free survival. We further analyzed a second cohort (N = 138) of patients that did not receive ICB with regard to CTLA4 promoter methylation, CTLA-4 protein expression, and immune cell infiltrates. Finally, we tested inducibility of CTLA-4 protein expression in HNSCC cells using the DNA methyltransferase inhibitor decitabine. RESULTS: Lower CTLA4 promoter methylation correlated with response to ICB and prolonged progression-free survival. We could show that not only tumor infiltrating immune cells, but also HNSCC cells harbor cytoplasmic and nuclear CTLA-4 expression. CTLA4 promoter methylation inversely correlated with infiltrates of CD3+, CD4+, CD8+, and CD45+ immune cells. CTLA4 methylation did not correlate with protein expression in tumors, however, decitabine treatment led to decreased CTLA4 methylation and an induction of CTLA4 mRNA and CTLA-4 protein expression in HNSCC cell lines. CONCLUSIONS: Our results indicate that CTLA4 DNA hypomethylation is a predictive biomarker for response to ICB in HNSCC. Our study warrants further analyses of the predictive value of CTLA4 DNA methylation in clinical trials of anti-PD-1 and/or anti-CTLA-4 immunotherapy in HNSCC.


Subject(s)
DNA Methylation , Head and Neck Neoplasms , Humans , Squamous Cell Carcinoma of Head and Neck/drug therapy , Squamous Cell Carcinoma of Head and Neck/genetics , CTLA-4 Antigen/genetics , Decitabine/pharmacology , Decitabine/therapeutic use , Immunotherapy/methods , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/genetics , DNA
4.
Biomark Res ; 11(1): 56, 2023 Jun 01.
Article in English | MEDLINE | ID: mdl-37259155

ABSTRACT

BACKGROUND: Inducible T cell costimulator ICOS is an emerging target in immuno-oncology. The aim of this study was to investigate the epigenetic regulation of ICOS in melanoma by DNA methylation. METHODS: We comprehensively investigate ICOS DNA methylation of specific CpG sites and expression pattern within the melanoma microenvironment with regard to immune correlates, differentiation, clinical outcomes, and immune checkpoint blockade (ICB) response. RESULTS: Our study revealed a sequence-contextual CpG methylation pattern consistent with an epigenetically regulated gene. We found a cell type-specific methylation pattern and locus-specific correlations and associations of CpG methylation with ICOS mRNA expression, immune infiltration, melanoma differentiation, prognosis, and response to ICB. High ICOS mRNA expression was identified as a surrogate for enriched immune cell infiltration and was associated with favorable overall survival (OS) in non-ICB-treated patients and predicted response and a prolonged progression-free survival (PFS) following ICB therapy initiation. ICOS hypomethylation, however, significantly correlated with poor OS in non-ICB patients but predicted higher response and prolonged PFS and OS in ICB-treated patients. Moreover, we observed cytoplasmic and sporadically nuclear tumor cell-intrinsic ICOS protein expression. Tumor cell-intrinsic ICOS protein and mRNA expression was inducible by pharmacological demethylation with decitabine. CONCLUSION: Our study identified ICOS DNA methylation and mRNA expression as promising prognostic and predictive biomarkers for immunotherapy in melanoma and points towards a hitherto undescribed role of ICOS in tumor cells.

5.
Int J Drug Policy ; 115: 104000, 2023 05.
Article in English | MEDLINE | ID: mdl-36965303

ABSTRACT

BACKGROUND: This study examines the effect of retail recreational marijuana legalization on traffic fatalities using the most current data available and recent advancements in difference-in-difference estimation methods proposed by Callaway and Sant'Anna, (2021). METHOD: A modified difference-in-difference (CS-DID) is used to estimate the effect of recreational marijuana legalization on traffic fatalities reported in the Fatality Analysis Reporting System (FARS). Difference-in-difference regression models are run at the state-year level, using data from 2007 through 2020, and compared to estimates using traditional two-way-fixed-effects (TWFE) models. RESULTS: Consistent with past studies, results from conventional TWFE suggest traffic fatalities increase at a rate of 1.2 per billion vehicle miles traveled (BVMT) after retail of recreational marijuana begins. However, using the CS-DID model, we find slightly larger average total treatment effects (∼2.2 fatalities per BVMT). Moreover, the size of the effect changes across time, where cohorts "treated" earlier have substantially higher increases than those who more recently legalized. CONCLUSION: Traffic fatalities increase by 2.2 per billion miles driven after retail legalization, which may account for as many as 1400 traffic fatalities annually. States who legalized earlier experienced larger traffic fatality increases. TWFE methods are inadequate for policy evaluation and do not capture heterogeneous effects across time.


Subject(s)
Cannabis , Humans , United States , Accidents, Traffic , Travel , Legislation, Drug , Policy , Cannabinoid Receptor Agonists
6.
Geohealth ; 6(10): e2022GH000648, 2022 Oct.
Article in English | MEDLINE | ID: mdl-36248061

ABSTRACT

The link between agriculture and air pollution is well-established, as are the benefits of the US Department of Agriculture's Conservation Reserve Program (CRP). However, little research has linked CRP to air quality directly. This study aims to address this gap by modeling the relationship between CRP and fine particulate matter (PM2.5) concentrations at the county level from 2001 to 2016. Several econometric models are estimated with panel data while controlling for drought, population, and wildfire. Results show that CRP has a statistically significant negative effect on PM2.5 concentrations. Using estimates from this model, we project an avoided 1,353 deaths, 1,687 deaths, and 3,022 deaths nationally in 2008 relative to three different counterfactual scenarios: all CRP acreage placed under cultivation, increased drought, and a combination of the first two. The value of the avoided mortality is estimated to be $9.5 billion, $11.8 billion, and $21.2 billion, respectively. These findings provide evidence that CRP may generate economic gains in terms of avoided mortality, well above the cost of the program.

7.
MethodsX ; 8: 101540, 2021.
Article in English | MEDLINE | ID: mdl-34754808

ABSTRACT

This article contains supporting information on data collection for the research article entitled "Aircraft noise exposure drives the activation of white blood cells and induces microvascular dysfunction in mice" by Eckrich et al. We found that noise-induced stress triggered microvascular dysfunction via involvement of innate immune-derived reactive oxygen species. In this article, we present the instrumentation of mice with dorsal skinfold chambers for in vivo microscopic imaging of blood flow, interaction of leukocytes with the vascular wall (also by fluorescent labelling of blood cells) and vessel diameter. In addition, we explain the preparation of cerebral arterioles for measurement of vascular reactivity in vitro.•visualization of noise-dependent effects in dorsal skinfold chamber.•in vivo microscopy of noise-dependent activation of white blood cells.•analysis of noise-dependent microvascular dysfunction in dorsal skinfold chamber and cannulated cerebral arterioles.

8.
Appl Health Econ Health Policy ; 19(1): 45-56, 2021 01.
Article in English | MEDLINE | ID: mdl-33336326

ABSTRACT

BACKGROUND: Presidential campaigns and election outcomes have significant health implications for voters and communities. The theoretical underpinning of this relationship is multifaceted, but a new and growing field of empirical literature strongly suggests communities that voted for the losing presidential candidate may experience decreased physical and mental health under the leadership of the winning candidate. OBJECTIVE: Our objective was to estimate the relationship between mortality rates and community support for the losing presidential candidate (partisan loss). METHODS: Mortality data compiled by the US Centers for Disease Control and election results at the county level were used across a suite of county-year fixed-effects models to estimate the effect of election outcomes on mortality rates for the years 1999-2017. RESULTS: Mortality rates were positively associated with partisan loss. Results suggest mortality rates increase by as much as 3% in extremely partisan counties following presidential election losses. CONCLUSIONS: We suggest two mechanisms-social disintegration and/or partisan theory-by which mortality rates are likely to increase for counties that voted for the losing presidential candidate.


Subject(s)
Homicide , Politics , Humans
9.
J Environ Manage ; 196: 394-401, 2017 Jul 01.
Article in English | MEDLINE | ID: mdl-28334678

ABSTRACT

Utilities and water suppliers in the southwestern United States have used education and conservation programs over the past two decades in an attempt to ameliorate the pressures of increasing water scarcity. This paper builds on a long history of water demand and environmental psychology literature and attempts to answer a simple question: do households primarily motivated by environmental and social (E&S) considerations consume water differently than households motivated primarily by cost and convenience (C&C)? We find that E&S consumers use less water than C&C consumers on average. We also find that there is no statistical difference between E&S and C&C consumers in their consumption responses to changing prices, temperature, and precipitation. This implies that targeting future conservation efforts to self-reported consumer groups may not improve policy effectiveness.


Subject(s)
Conservation of Natural Resources , Motivation , Water Supply , Commerce , Water
10.
Integr Environ Assess Manag ; 12(2): 328-44, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26123999

ABSTRACT

Businesses may be missing opportunities to account for ecosystem services in their decisions, because they do not have methods to quantify and value ecosystem services. We developed a method to quantify and value coastal protection and other ecosystem services in the context of a cost-benefit analysis of hurricane risk mitigation options for a business. We first analyze linked biophysical and economic models to examine the potential protection provided by marshes. We then applied this method to The Dow Chemical Company's Freeport, Texas facility to evaluate natural (marshes), built (levee), and hybrid (marshes and a levee designed for marshes) defenses against a 100-y hurricane. Model analysis shows that future sea-level rise decreases marsh area, increases flood heights, and increases the required levee height (12%) and cost (8%). In this context, marshes do not provide sufficient protection to the facility, located 12 km inland, to warrant a change in levee design for a 100-y hurricane. Marshes do provide some protection near shore and under smaller storm conditions, which may help maintain the coastline and levee performance in the face of sea-level rise. In sum, the net present value to the business of built defenses ($217 million [2010 US$]) is greater than natural defenses ($15 million [2010 US$]) and similar to the hybrid defense scenario ($229 million [2010 US$]). Examination of a sample of public benefits from the marshes shows they provide at least $117 million (2010 US$) in coastal protection, recreational value, and C sequestration to the public, while supporting 12 fisheries and more than 300 wildlife species. This study provides information on where natural defenses may be effective and a replicable approach that businesses can use to incorporate private, as well as public, ecosystem service values into hurricane risk management at other sites.


Subject(s)
Conservation of Natural Resources/economics , Cyclonic Storms , Ecosystem , Cost-Benefit Analysis , Models, Theoretical , Risk , Wetlands
11.
J Gen Virol ; 93(Pt 8): 1658-1663, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22622326

ABSTRACT

The incursion of the human pandemic influenza A virus H1N1 (2009) (H1N1 pdm) into pig populations and its ongoing co-circulation with endemic swine influenza viruses (SIVs) has yielded distinct human-porcine reassortant virus lineages. The haemagglutinin (HA) gene of H1N1 pdm was detected in 41 influenza virus-positive samples from seven swine herds in north-west Germany in 2011. Eight of these samples yielded virus that carried SIV-derived neuraminidase N2 of three different porcine lineages in an H1N1 pdm backbone. The HA sequences of these viruses clustered in two distinct groups and were distinguishable from human and other porcine H1 pdm by a unique set of eight non-synonymous mutations. In contrast to the human population, where H1N1 pdm replaced seasonal H1N1, this virus seems to co-circulate and interact more intensely with endemic SIV lineages, giving rise to reassortants with as-yet-unknown biological properties and undetermined risks for public health.


Subject(s)
Influenza A Virus, H1N1 Subtype/genetics , Influenza A virus/genetics , Orthomyxoviridae Infections/veterinary , Reassortant Viruses/genetics , Swine Diseases/virology , Animals , Antigens, Viral/genetics , Communicable Diseases, Emerging/veterinary , Endemic Diseases/veterinary , Germany/epidemiology , Humans , Influenza A Virus, H1N1 Subtype/classification , Influenza A virus/classification , Mice , Molecular Sequence Data , Mutation , Orthomyxoviridae Infections/epidemiology , Orthomyxoviridae Infections/virology , Pandemics , Phylogeny , Sequence Alignment , Swine , Swine Diseases/epidemiology
12.
Proteome Sci ; 9(1): 23, 2011 Apr 20.
Article in English | MEDLINE | ID: mdl-21507263

ABSTRACT

BACKGROUND: Protection of pigs by vaccination against Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is hampered by the presence of 15 different serotypes. A DIVA subunit vaccine comprised of detergent-released proteins from A. pleuropneumoniae serotypes 1, 2 and 5 has been developed and shown to protect pigs from clinical symptoms upon homologous and heterologous challenge. This vaccine has not been characterized in-depth so far. Thus we performed i) mass spectrometry in order to identify the exact protein content of the vaccine and ii) cross-serotype 2-D immunoblotting in order to discover cross-reactive antigens. By these approaches we expected to gain results enabling us to argue about the reasons for the efficacy of the analyzed vaccine. RESULTS: We identified 75 different proteins in the vaccine. Using the PSORTb algorithm these proteins were classified according to their cellular localization. Highly enriched proteins are outer membrane-associated lipoproteins like OmlA and TbpB, integral outer membrane proteins like FrpB, TbpA, OmpA1, OmpA2, HgbA and OmpP2, and secreted Apx toxins. The subunit vaccine also contained large amounts of the ApxIVA toxin so far thought to be expressed only during infection. Applying two-dimensional difference gel electrophoresis (2-D DIGE) we showed different isoforms and variations in expression levels of several proteins among the strains used for vaccine production. For detection of cross-reactive antigens we used detergent released proteins of serotype 7. Sera of pigs vaccinated with the detergent-released proteins of serotypes 1, 2, and 5 detected seven different proteins of serotype 7, and convalescent sera of pigs surviving experimental infection with serotype 7 reacted with 13 different proteins of the detergent-released proteins of A. pleuropneumoniae serotypes 1, 2, and 5. CONCLUSIONS: A detergent extraction-based subunit vaccine of A. pleuropneumoniae was characterized by mass spectrometry. It contained a large variety of immunogenic and virulence associated proteins, among them the ApxIVA toxin. The identification of differences in expression as well as isoform variation between the serotypes implied the importance of combining proteins of different serotypes for vaccine generation. This finding was supported by immunoblotting showing the induction of cross-reactive antibodies against several surface associated proteins in immunized animals.

13.
Vet Microbiol ; 127(1-2): 106-15, 2008 Feb 05.
Article in English | MEDLINE | ID: mdl-17881160

ABSTRACT

Actinobacillus pleuropneumoniae is a facultative anaerobic pathogen of the porcine respiratory tract requiring anaerobic metabolic activity for persistence on lung epithelium. The ArcAB two-component system facilitating metabolic adaptation to anaerobicity was investigated with regard to its impact on virulence and colonization of the porcine respiratory tract. Using pig infection experiments we demonstrate that deletion of arcA renders A. pleuropneumoniae significantly attenuated in acute infection and reduced long-term survival on unaltered lung epithelium as well as in sequesters. Contrary to its role in enterobacteria, the deletion of arcA in A. pleuropneumoniae does not affect growth and survival under anaerobic conditions. Instead, other than the parent strain A. pleuropneumoniae DeltaarcA does not show autoaggregation under anaerobic conditions and is deficient in biofilm formation. It is hypothesized that the lack of these functions is, at least in part, responsible for the reduction of virulence.


Subject(s)
Actinobacillus Infections/veterinary , Actinobacillus pleuropneumoniae/genetics , Actinobacillus pleuropneumoniae/pathogenicity , Bacterial Outer Membrane Proteins/genetics , Biofilms/growth & development , Swine Diseases/microbiology , Actinobacillus Infections/microbiology , Actinobacillus pleuropneumoniae/growth & development , Actinobacillus pleuropneumoniae/isolation & purification , Animals , DNA Mutational Analysis/methods , Microscopy, Electron , Sequence Deletion/genetics , Survival Analysis , Swine , Time Factors , Virulence/genetics
14.
Vaccine ; 24(49-50): 7226-37, 2006 Nov 30.
Article in English | MEDLINE | ID: mdl-17027123

ABSTRACT

Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia which leads to high economic losses in the swine industry worldwide. Vaccination against this pathogen is hampered by the occurrence of 15 serotypes, and commonly used whole cell bacterin vaccines are not sufficiently cross-serotype protective. In addition, for generating and maintaining specified pathogen-free herds it is desirable to use DIVA (differentiating infected from vaccinated animals) vaccines. Based on a detergent wash extraction of outer membrane associated proteins and secreted proteins we developed a DIVA vaccine using the immunogenic ApxII toxin which is present in 13 of the 15 A. pleuropneumoniae serotypes as the DIVA antigen. The apxIIA gene was deleted in one strain each of serotypes 1, 2, and 5 using a single-step transconjugation system, and equal parts of detergent washes from these strains served as the vaccine antigen. After intramuscular immunisation all pigs developed a strong humoral immune response to the vaccine antigen and showed no reactivity in an ApxIIA ELISA. Upon challenge all pigs were completely protected from clinical symptoms in trials with a homologous (serotype 2) as well as with a heterologous strain (serotype 9); in addition, colonisation of the challenge strain was clearly reduced but not abolished completely. As a result of the highly efficient protection, however, immunised pigs did not develop antibodies to the DIVA-antigen at levels detectable by ELISA but only by a more sensitive Western blotting approach, thereby demonstrating the challenge in developing appropriate marker vaccines for the livestock industry.


Subject(s)
Actinobacillus Infections/immunology , Actinobacillus Infections/veterinary , Actinobacillus pleuropneumoniae/immunology , Bacterial Vaccines/immunology , Pleuropneumonia/immunology , Pleuropneumonia/veterinary , Swine Diseases/immunology , Actinobacillus Infections/prevention & control , Actinobacillus pleuropneumoniae/genetics , Animals , Antibody Formation/immunology , Bacterial Outer Membrane Proteins/genetics , Bacterial Outer Membrane Proteins/immunology , Blotting, Western , DNA, Bacterial/genetics , DNA, Bacterial/isolation & purification , Enzyme-Linked Immunosorbent Assay , Mutation/genetics , Plasmids/genetics , Pleuropneumonia/prevention & control , Swine , Swine Diseases/prevention & control , Vaccination , Vaccines, Subunit/immunology
15.
Infect Immun ; 74(7): 4124-32, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16790786

ABSTRACT

Vaccination against Actinobacillus pleuropneumoniae is hampered by the lack of vaccines inducing reliable cross-serotype protection. In contrast, pigs surviving natural infection are at least partially protected from clinical symptoms upon reinfection with any serotype. Thus, we set out to construct an attenuated A. pleuropneumoniae live vaccine allowing the differentiation of vaccinated from infected animals (the DIVA concept) by successively deleting virulence-associated genes. Based on an A. pleuropneumoniae serotype 2 prototype live negative marker vaccine (W. Tonpitak, N. Baltes, I. Hennig-Pauka, and G.-F. Gerlach, Infect. Immun. 70:7120-7125, 2002), genes encoding three enzymes involved in anaerobic respiration and the ferric uptake regulator Fur were deleted, resulting in a highly attenuated sixfold mutant; this mutant was still able to colonize the lower respiratory tract and induced a detectable immune response. Upon a single aerosol application, this mutant provided significant protection from clinical symptoms upon heterologous infection with an antigenically distinct A. pleuropneumoniae serotype 9 challenge strain and allowed the serological discrimination between infected and vaccinated groups.


Subject(s)
Actinobacillus Infections/prevention & control , Actinobacillus pleuropneumoniae/genetics , Actinobacillus pleuropneumoniae/immunology , Bacterial Vaccines/immunology , Mutation , Swine/immunology , Actinobacillus Infections/immunology , Actinobacillus Infections/veterinary , Actinobacillus pleuropneumoniae/pathogenicity , Animals , Bacterial Proteins/physiology , Bacterial Vaccines/administration & dosage , Humans , Repressor Proteins/physiology , Swine/microbiology , Vaccines, Attenuated/administration & dosage , Vaccines, Attenuated/immunology , Virulence
16.
Infect Immun ; 73(8): 4614-9, 2005 Aug.
Article in English | MEDLINE | ID: mdl-16040973

ABSTRACT

Actinobacillus pleuropneumoniae, the etiological agent of porcine pleuropneumonia, is able to persist on respiratory epithelia, in tonsils, and in the anaerobic environment of encapsulated lung sequesters. We have demonstrated previously that putative HlyX-regulated genes, coding for dimethyl sulfoxide (DMSO) reductase and aspartate ammonia lyase, are upregulated during infection and that deletions in these genes result in attenuation of the organism. The study presented here investigates the role of HlyX, the fumarate nitrate reductase regulator (FNR) homologue of A. pleuropneumoniae. By constructing an isogenic A. pleuropneumoniae hlyX mutant, the HlyX protein is shown to be responsible for upregulated expression of both DMSO reductase and aspartate ammonia lyase (AspA) under anaerobic conditions. In a challenge experiment the A. pleuropneumoniae hlyX mutant is shown to be highly attenuated, unable to persist in healthy lung epithelium and tonsils, and impaired in survival inside sequestered lung tissue. Further, using an A. pleuropneumoniae strain carrying the luxAB genes as transcriptional fusion to aspA on the chromosome, the airway antioxidant glutathione was identified as one factor potentially responsible for inducing HlyX-dependent gene expression of A. pleuropneumoniae in epithelial lining fluid.


Subject(s)
Actinobacillus Infections/metabolism , Actinobacillus pleuropneumoniae/metabolism , DNA-Binding Proteins/deficiency , Respiratory System/microbiology , Transcription Factors/deficiency , Actinobacillus Infections/veterinary , Actinobacillus pleuropneumoniae/genetics , Actinobacillus pleuropneumoniae/pathogenicity , Animals , Aspartate Ammonia-Lyase/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Glutathione/metabolism , Mutation , Swine , Transcription Factors/genetics , Transcription Factors/metabolism , Virulence/genetics
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