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1.
Cardiovasc Digit Health J ; 5(3): 156-163, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38989044

ABSTRACT

Introduction: Unmanaged hypertension in pregnancy is the second most common cause of direct maternal death and disproportionately affects women in rural areas. While telehealth technologies have worked to reduce barriers to healthcare, lack of internet access has created new challenges. Cellular-enabled remote patient monitoring devices provide an alternative option for those without access to internet. Objective: This study aimed to assess maternal and neonatal clinical outcomes and patient acceptability of an integrated model of cellular-enabled remote patient monitoring devices for blood pressure supported by a 24/7 nurse call center. Methods: In a mixed-methods study, 20 women with hypertension during pregnancy were given a cellular-enabled BodyTrace blood pressure cuff. Participants' blood pressures were continuously monitored by a nurse call center. Participants completed a baseline survey, post-survey, and semi-structured interview after 8 weeks of device use. Results: Participants reported a significant decrease in perceived stress after device use (P = .0004), high satisfaction with device usability (mean = 78.38, SD = 13.68), and high intention to continue device use (mean = 9.05, SD = 1.96). Relatively low hospitalization and emergency department rates was observed (mean = 0.35, SD = 0.59; mean = 0.75, SD = 0.91). Participant-perceived benefits of device use included convenience, perceived better care owing to increased monitoring, and patient empowerment. Perceived disadvantages included higher blood pressure readings compared to clinical readings and excessive calls from call center. Conclusion: Remote patient monitoring for women whose pregnancies are complicated by hypertension can reduce barriers and improve health outcomes for women living in rural and low-health-resource areas.

2.
Workplace Health Saf ; 69(9): 400-409, 2021 Sep.
Article in English | MEDLINE | ID: mdl-33882733

ABSTRACT

BACKGROUND: Leading Change is one of five Executive Core Qualifications (ECQs) used in developing leaders in the federal government. Leadership development programs that incorporate multirater feedback and executive coaching are valuable in developing competencies to lead change. METHODS: We examined the extent by which coaching influenced Leading Change competencies and identified effective tools and resources used to enhance the leadership capacity of first- and midlevel leaders at Centers for Disease Control and Prevention's National Center for HIV/AIDS, Viral Hepatitis, Sexually Transmitted Diseases, and Tuberculosis Prevention. Data included qualitative data collected via semi-structured interviews that focused on leadership changes made by leaders in the Coaching and Leadership Initiative (CaLI), a leadership development program for Team Leads and Branch Chiefs. FINDINGS: Ninety-six participants completed leadership coaching; 94 (98%) of whom completed one or more interviews. Of those 94 respondents, 74 (79%) reported improvements in their ability to lead change in 3 of 4 leading change competencies: creativity and innovation, flexibility, and resilience. All respondents indicated tools and resources that were effective in leading change: 49 (52%) participated in instructor-led activities during their CaLI experience; 33 (35%) experiential activities; 94 (100%) developmental relationships, assessment, and feedback; and 25 (27%) self-development. CONCLUSIONS/APPLICATION TO PRACTICE: First- and midlevel leaders in a public health agency benefitted from using leadership coaching in developing competencies to lead organizational change. Leadership development programs might benefit from examining Leading Change competencies and including instructor-led and experiential activities as an additional component of a comprehensive leadership development program.


Subject(s)
Feedback , Leadership , Organizational Innovation , Public Health Administration/standards , Humans , Mentoring/methods , Mentoring/standards , Mentoring/statistics & numerical data , Public Health Administration/methods , Public Health Administration/statistics & numerical data
3.
J Public Health Manag Pract ; 27(Suppl 3): S200-S205, 2021.
Article in English | MEDLINE | ID: mdl-33785697

ABSTRACT

CONTEXT: There is a long-standing shortage of formally trained Occupational & Environmental Medicine (OEM) physicians despite OEM practitioners experiencing high satisfaction and low burnout. OBJECTIVE: To explore the root causes of this shortage and suggest potential remedies. METHODS: Cross-sectional surveys were administered to medical students queried regarding OEM training, practicing OEM physicians queried regarding timing of specialty choice, and OEM Train-in-Place (TIP) program graduates queried regarding satisfaction with training. RESULTS: Of 247 medical student respondents, 70% had heard of OEM, 60% through one lecture. Of the 160 OEM physicians, 17% first became aware of OEM as medical students, and most would have chosen a different path had they heard sooner. Most TIP program trainees reported that they would not have undertaken specialty training without a TIP program (89%). CONCLUSIONS: Strategies to introduce OEM earlier in medical education and TIP programs for mid-career physicians may help overcome persistent shortages of OEM specialists.


Subject(s)
Burnout, Professional , Occupational Medicine , Physicians , Career Choice , Cross-Sectional Studies , Humans , Surveys and Questionnaires , United States
4.
J Public Health Manag Pract ; 27(1): 46-54, 2021.
Article in English | MEDLINE | ID: mdl-31688734

ABSTRACT

CONTEXT: Public health managers' leadership skills can be improved through multirater feedback and coaching. OBJECTIVE: To explore to what extent participation in a coaching intervention influences leadership behaviors of first- and second-level leaders in a federal public health agency. DESIGN: Team leads and branch chiefs in the Centers for Disease Control and Prevention's (CDC's) National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP) were invited to participate in the Coaching and Leadership Initiative (CaLI), which incorporates the US Office of Personnel Management (OPM) Leadership 360 assessment, 6 coaching sessions, and 2 in-depth interviews. SETTING: NCHHSTP is one of 16 CDC national centers, institute, and offices. PARTICIPANTS: Staff serving as team leads or branch chiefs. MAIN OUTCOME MEASURES: Two in-depth interviews explored CaLI's influence on leadership behaviors regarding the government-wide Leading People executive core qualification. RESULTS: A total of 103 (93%) CaLI participants completed the OPM 360 feedback, 82 (80%) completed leadership coaching; 71 of 82 (87%) completed phase 1 interview, and 46 of 71 (65%) completed phase 2 interview. Eighty unique participants completed 1 or more interviews; all indicated that CaLI helped provide new perspectives, practices, and approaches that led to better communication and relationships, different approaches to conflict resolution, and awareness of individual leadership practices. Of the 71 participants who completed phase 1 evaluation, 66 (93%) said they made changes in developing others, 56 (79%) completed conflict management and team building, and 16 (23%) completed leveraging diversity. Of the 46 participants who completed both phase 1 and phase 2 interviews and among those who made changes post-CaLI, 23 of 26 (88%) sustained those leadership changes in developing others, 21 of 27 (78%) in team building; 24 of 34 (71%) in conflict management; and 5 of 10 (50%) in leveraging diversity. CONCLUSIONS: This study demonstrates the benefits and effectiveness of using multirater feedback and leadership coaching for first- and midlevel public health leaders.


Subject(s)
Leadership , Mentoring , Feedback , Humans , Public Health
5.
Workplace Health Saf ; 68(8): 366-373, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32336257

ABSTRACT

Background: Employee engagement, exemplified by positive perceptions of supervisors, workplace, and job, improves productivity and employee retention. We identified the extent of and barriers to employee engagement at Centers for Disease Control and Prevention's (CDC) National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP). Methods: In 2015, NCHHSTP's leadership collected baseline data through a centerwide Employee Engagement Pulse Survey (EEPS) from NCHHSTP's full-time Civil Service employees, U.S. Public Health Service Commissioned Corps officers, and Title 42 service fellows. EEPS included six demographic questions; nine Likert-type scale questions measuring 26 perceptions related to immediate supervisors, the work environment, and job satisfaction; and four open-ended questions soliciting recommendations for improvement. Findings: Among 727 of 1,171 staff (response rate = 62%), positive perceptions of supervisors ranged from a high of 94% (supervisor conducts performance reviews) to a low of 63% (supervisor assists employees with career development). Perceptions of work experience ranged from 98% (respondents were willing to put in extra effort to get a job done) to 68% (respondents' talents were used well in the workplace). Perceptions of job satisfaction ranged from 87% (support from their coworkers) to 69% (satisfaction with opportunities to learn or grow professionally). Conclusion/Application to Practice: Overall, NCHHSTP staff have positive perceptions of their work, their leaders, and the agency. Other public- and private-sector employers might be able to improve their employees' engagement and retention by listening to their opinions and needs and frequently recognizing their individual achievements. NCHHSTP's workforce development initiatives can be used as a model for assessing a baseline of their employees' engagement.


Subject(s)
Government Employees/psychology , Organizational Culture , Work Engagement , Workplace/organization & administration , Adult , Aged , Centers for Disease Control and Prevention, U.S. , Humans , Job Satisfaction , Leadership , Middle Aged , Personnel Turnover , Public Health , Surveys and Questionnaires , United States , Workplace/psychology
6.
Article in English | MEDLINE | ID: mdl-27993849

ABSTRACT

The loss of fitness in colistin-resistant (CR) Acinetobacter baumannii was investigated using longitudinal isolates from the same patient. Early CR isolates were outcompeted by late CR isolates for growth in broth and survival in the lungs of mice. Fitness loss was associated with an increased susceptibility to oxidative stress since early CR strains had reduced in vitro survival in the presence of hydrogen peroxide and decreased catalase activity compared to that of late CR and colistin-susceptible (CS) strains.


Subject(s)
Acinetobacter baumannii/drug effects , Adaptation, Physiological/drug effects , Anti-Bacterial Agents/pharmacology , Colistin/pharmacology , Drug Resistance, Bacterial/genetics , Acinetobacter Infections/drug therapy , Acinetobacter Infections/microbiology , Acinetobacter Infections/pathology , Acinetobacter baumannii/genetics , Acinetobacter baumannii/isolation & purification , Acinetobacter baumannii/pathogenicity , Adaptation, Physiological/genetics , Adult , Animals , Genetic Fitness , Humans , Hydrogen Peroxide/pharmacology , Male , Mice , Oxidative Stress , Time Factors , Virulence/drug effects , Wounds, Gunshot/drug therapy , Wounds, Gunshot/microbiology , Wounds, Gunshot/pathology
7.
Clin Infect Dis ; 61(2): 145-54, 2015 Jul 15.
Article in English | MEDLINE | ID: mdl-25824815

ABSTRACT

BACKGROUND: Severe Acinetobacter baumannii infections in immunocompetent patients are uncommon, and the virulence mechanisms of this organism are not fully understood. METHODS: Following an outbreak of fatal A. baumannii infections in a cohort of relatively immunocompetent patients (low comorbidity and illness severity scores), isolates were investigated with comparative genomics and in animal models. RESULTS: Two unrelated A. baumannii clades were associated with the outbreak. The clone associated with the majority of patient deaths, clade B, is evolutionarily distinct from the 3 international clonal complexes, belongs to multilocus sequence type (MLST) 10, and is most closely related to strains isolated from the Czech Republic, California, and Germany in 1994, 1997, and 2003, respectively. In 2 different murine models, clade B isolates were more virulent than comparator strains, including the highly virulent reference strain AB5075. The most virulent clade B derivative, MRSN 16897, was isolated from the patient with the lowest combined comorbidity/illness severity score. Clade B isolates possess a unique combination of putative virulence genes involved in iron metabolism, protein secretion, and glycosylation, which was leveraged to develop a rapid and specific clinical assay to detect this clade that cannot be distinguished by MLST. CONCLUSIONS: Clade B warrants continued surveillance and investigation.


Subject(s)
Acinetobacter Infections/epidemiology , Acinetobacter Infections/mortality , Acinetobacter baumannii/pathogenicity , Disease Outbreaks , Drug Resistance, Multiple, Bacterial , Acinetobacter Infections/genetics , Acinetobacter Infections/microbiology , Acinetobacter baumannii/classification , Acinetobacter baumannii/genetics , Acinetobacter baumannii/isolation & purification , Adult , Aged, 80 and over , Animals , California , Czech Republic , Disease Models, Animal , Drug Resistance, Multiple, Bacterial/genetics , Female , Genomics , Germany , Humans , Immunocompetence , Male , Mice , Middle Aged , Multilocus Sequence Typing , Phylogeny , Tertiary Care Centers/statistics & numerical data , United States/epidemiology , Virulence/genetics
8.
Am J Prev Med ; 47(5 Suppl 3): S288-96, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25439247

ABSTRACT

In February 2010, CDC's National Center for HIV/AIDS, Viral Hepatitis, Sexually Transmitted Disease (STD), and Tuberculosis (TB) Prevention (NCHHSTP) formally institutionalized workforce development and capacity building (WDCB) as one of six overarching goals in its 2010-2015 Strategic Plan. Annually, workforce team members finalize an action plan that lays the foundation for programs to be implemented for NCHHSTP's workforce that year. This paper describes selected WDCB programs implemented by NCHHSTP during the last 4 years in the three strategic goal areas: (1) attracting, recruiting, and retaining a diverse and sustainable workforce; (2) providing staff with development opportunities to ensure the effective and innovative delivery of NCHHSTP programs; and (3) continuously recognizing performance and achievements of staff and creating an atmosphere that promotes a healthy work-life balance. Programs have included but are not limited to an Ambassador Program for new hires, career development training for all staff, leadership and coaching for mid-level managers, and a Laboratory Workforce Development Initiative for laboratory scientists. Additionally, the paper discusses three overarching areas-employee communication, evaluation and continuous review to guide program development, and the implementation of key organizational and leadership structures to ensure accountability and continuity of programs. Since 2010, many lessons have been learned regarding strategic approaches to scaling up organization-wide public health workforce development and capacity building. Perhaps the most important is the value of ensuring the high-level strategic prioritization of this issue, demonstrating to staff and partners the importance of this imperative in achieving NCHHSTP's mission.


Subject(s)
Capacity Building , Education, Public Health Professional , Health Workforce , Public Health , Career Mobility , Centers for Disease Control and Prevention, U.S. , Humans , Organizational Objectives , United States , United States Government Agencies
9.
PLoS One ; 9(12): e114888, 2014.
Article in English | MEDLINE | ID: mdl-25485542

ABSTRACT

In this study we describe the molecular and cellular characterization of a zebrafish mutant that develops tumors in the optic pathway. Heterozygous Tg(flk1:RFP)is18 transgenic adults develop tumors of the retina, optic nerve and optic tract. Molecular and genetic mapping demonstrate the tumor phenotype is linked to a high copy number transgene array integrated in the lincRNA gene lincRNAis18/Zv9_00007276 on chromosome 3. TALENs were used to isolate a 147 kb deletion allele that removes exons 2-5 of the lincRNAis18 gene. Deletion allele homozygotes are viable and do not develop tumors, indicating loss of function of the lincRNAis18 locus is not the trigger for tumor onset. Optic pathway tumors in the Tg(flk1:RFP)is18 mutant occur with a penetrance of 80-100% by 1 year of age. The retinal tumors are highly vascularized and composed of rosettes of various sizes embedded in a fibrous matrix. Immunohistochemical analysis showed increased expression of the glial markers GFAP and BLBP throughout retinal tumors and in dysplastic optic nerve. We performed transcriptome analysis of pre-tumorous retina and retinal tumor tissue and found changes in gene expression signatures of radial glia and astrocytes (slc1a3), activated glia (atf3, blbp, apoeb), proliferating neural progenitors (foxd3, nestin, cdh2, her9/hes1), and glioma markers (S100ß, vim). The transcriptome also revealed activation of cAMP, Stat3 and Wnt signal transduction pathways. qRT-PCR confirmed >10-fold overexpression of the Wnt pathway components hbegfa, ascl1a, and insm1a. Together the data indicate Müller glia and/or astrocyte-derived progenitors could contribute to the zebrafish Tg(flk1:RFP)is18 optic pathway tumors.


Subject(s)
Animals, Genetically Modified/growth & development , Cell Transformation, Neoplastic/pathology , Neuroglia/cytology , Optic Nerve/cytology , Stem Cells/cytology , Visual Pathways/cytology , Zebrafish/growth & development , Animals , Blotting, Southern , Cell Differentiation , Cell Proliferation , Cell Transformation, Neoplastic/metabolism , Cells, Cultured , Immunoenzyme Techniques , Neuroglia/metabolism , Optic Nerve/metabolism , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Stem Cells/metabolism , Visual Pathways/metabolism , Zebrafish/genetics , Zebrafish Proteins/genetics , Zebrafish Proteins/metabolism
10.
Proc Natl Acad Sci U S A ; 111(30): 11163-8, 2014 Jul 29.
Article in English | MEDLINE | ID: mdl-25024199

ABSTRACT

Clustered, regularly interspaced, short palindromic repeats-CRISPR associated (CRISPR-Cas) systems defend bacteria against foreign nucleic acids, such as during bacteriophage infection and transformation, processes which cause envelope stress. It is unclear if these machineries enhance membrane integrity to combat this stress. Here, we show that the Cas9-dependent CRISPR-Cas system of the intracellular bacterial pathogen Francisella novicida is involved in enhancing envelope integrity through the regulation of a bacterial lipoprotein. This action ultimately provides increased resistance to numerous membrane stressors, including antibiotics. We further find that this previously unappreciated function of Cas9 is critical during infection, as it promotes evasion of the host innate immune absent in melanoma 2/apoptosis associated speck-like protein containing a CARD (AIM2/ASC) inflammasome. Interestingly, the attenuation of the cas9 mutant is complemented only in mice lacking both the AIM2/ASC inflammasome and the bacterial lipoprotein sensor Toll-like receptor 2, but not in single knockout mice, demonstrating that Cas9 is essential for evasion of both pathways. These data represent a paradigm shift in our understanding of the function of CRISPR-Cas systems as regulators of bacterial physiology and provide a framework with which to investigate the roles of these systems in myriad bacteria, including pathogens and commensals.


Subject(s)
Bacterial Proteins/immunology , Drug Resistance, Bacterial/immunology , Francisella/immunology , Gram-Negative Bacterial Infections/immunology , Immune Evasion/immunology , Inflammasomes/immunology , Lipoproteins/immunology , Animals , Cell Membrane/genetics , Cell Membrane/immunology , Drug Resistance, Bacterial/genetics , Francisella/genetics , Gram-Negative Bacterial Infections/genetics , Immune Evasion/genetics , Inflammasomes/genetics , Inverted Repeat Sequences/immunology , Lipoproteins/genetics , Mice , Mice, Knockout
11.
Infect Immun ; 82(10): 4253-64, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25069977

ABSTRACT

Staphylococcus aureus is a Gram-positive pathogen that causes a diverse range of bacterial infections. Invasive S. aureus strains secrete an extensive arsenal of hemolysins, immunomodulators, and exoenzymes to cause disease. Our studies have focused on the secreted enzyme hyaluronidase (HysA), which cleaves the hyaluronic acid polymer at the ß-1,4 glycosidic bond. In the study described in this report, we have investigated the regulation and contribution of this enzyme to S. aureus pathogenesis. Using the Nebraska Transposon Mutant Library (NTML), we identified eight insertions that modulate extracellular levels of HysA activity. Insertions in the sigB operon, as well as in genes encoding the global regulators SarA and CodY, significantly increased HysA protein levels and activity. By altering the availability of branched-chain amino acids, we further demonstrated CodY-dependent repression of HysA activity. Additionally, through mutation of the CodY binding box upstream of hysA, the repression of HysA production was lost, suggesting that CodY is a direct repressor of hysA expression. To determine whether HysA is a virulence factor, a ΔhysA mutant of a community-associated methicillin-resistant S. aureus (CA-MRSA) USA300 strain was constructed and found to be attenuated in a neutropenic, murine model of pulmonary infection. Mice infected with this mutant strain exhibited a 4-log-unit reduction in bacterial burden in their lungs, as well as reduced lung pathology and increased levels of pulmonary hyaluronic acid, compared to mice infected with the wild-type, parent strain. Taken together, these results indicate that S. aureus hyaluronidase is a CodY-regulated virulence factor.


Subject(s)
Bacterial Proteins/metabolism , Gene Expression Regulation, Bacterial , Polysaccharide-Lyases/biosynthesis , Repressor Proteins/metabolism , Staphylococcus aureus/genetics , Staphylococcus aureus/pathogenicity , Virulence Factors/biosynthesis , Animals , Bacterial Load , Disease Models, Animal , Female , Histocytochemistry , Lung/microbiology , Lung/pathology , Mice , Mice, Inbred BALB C , Pneumonia, Staphylococcal/microbiology , Pneumonia, Staphylococcal/pathology , Virulence
12.
J Antimicrob Chemother ; 69(7): 1830-3, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24583361

ABSTRACT

OBJECTIVES: Nosocomial pathogens such as Acinetobacter baumannii are a growing public health threat, due in part to their increasing resistance to antibiotics. Since some strains are resistant to all available antibiotics, novel therapies are urgently needed. Plasmablasts are short-lived B cells found in the blood that can be collected and harnessed to produce therapeutic antibodies. We set out to determine whether plasmablasts are induced during infection with A. baumannii and other nosocomial pathogens. METHODS: We obtained blood samples from patients infected with antibiotic-resistant nosocomial pathogens, and analysed their plasmablast response by flow cytometry. RESULTS: We observed a strong induction of plasmablasts in patients with antibiotic-resistant A. baumannii infection. Furthermore, plasmablasts were also induced in response to other drug-resistant nosocomial pathogens. CONCLUSIONS: These data suggest that plasmablasts may be broadly harnessed to develop therapeutic antibodies to combat otherwise untreatable antibiotic-resistant infections.


Subject(s)
Acinetobacter baumannii/immunology , Cross Infection/microbiology , Plasma Cells/immunology , Acinetobacter baumannii/drug effects , Acinetobacter baumannii/isolation & purification , Adult , Aged , Drug Resistance, Bacterial , Female , Flow Cytometry , Humans , Lymphocyte Activation , Male , Middle Aged
13.
Microbiol Mol Biol Rev ; 76(2): 383-404, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22688817

ABSTRACT

Francisella tularensis is a gram-negative intracellular pathogen and the causative agent of the disease tularemia. Inhalation of as few as 10 bacteria is sufficient to cause severe disease, making F. tularensis one of the most highly virulent bacterial pathogens. The initial stage of infection is characterized by the "silent" replication of bacteria in the absence of a significant inflammatory response. Francisella achieves this difficult task using several strategies: (i) strong integrity of the bacterial surface to resist host killing mechanisms and the release of inflammatory bacterial components (pathogen-associated molecular patterns [PAMPs]), (ii) modification of PAMPs to prevent activation of inflammatory pathways, and (iii) active modulation of the host response by escaping the phagosome and directly suppressing inflammatory pathways. We review the specific mechanisms by which Francisella achieves these goals to subvert host defenses and promote pathogenesis, highlighting as-yet-unanswered questions and important areas for future study.


Subject(s)
Francisella tularensis/pathogenicity , Tularemia/microbiology , Animals , Francisella tularensis/growth & development , Genome, Bacterial , Host-Pathogen Interactions , Humans , Inflammation Mediators/metabolism , Microbial Viability , Phagosomes/microbiology
14.
Cell Microbiol ; 14(10): 1531-43, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22632124

ABSTRACT

Innate recognition systems, including the Toll-like receptors (TLRs), play a critical role in activating host defences and proinflammatory pathways in response to infection. Pathogens have developed strategies to subvert TLRs in order to survive and replicate within the host. The model intracellular pathogen, Francisella novicida, modulates host defences to promote survival and replication in macrophages. TLR2, which recognizes bacterial lipoproteins (BLPs), is critical for activating host defences and proinflammatory cytokine production in response to Francisella infection. Here we show that the F. novicida protein FTN_0757 acts to repress BLP production, dampening TLR2 activation. The ΔFTN_0757 mutant strain induced robust TLR2-dependent cytokine production in macrophages compared with wild-type bacteria, and produced increased amounts of BLPs. The deletion of one BLP (FTN_1103) from ΔFTN_0757 decreased the total BLP concentration to near wild-type level sand correlated with a decrease in the inductionof TLR2 signalling. The overproduction of BLPs also contributed to the in vivo attenuation of the ΔFTN_0757 mutant, which was significantly rescued when FTN_1103 was deleted. Taken together, these data reveal a novel mechanism of immune evasion by the downregulation of BLP expression to subvert TLR2 activation, which is likely used by numerous other intracellular bacterial pathogens.


Subject(s)
Francisella tularensis/immunology , Francisella tularensis/pathogenicity , Immune Evasion , Lipoproteins/biosynthesis , Macrophages/immunology , Macrophages/microbiology , Repressor Proteins/metabolism , Animals , Cells, Cultured , Cytokines/metabolism , Francisella tularensis/genetics , Gene Deletion , Lipoproteins/antagonists & inhibitors , Lipoproteins/genetics , Mice , Repressor Proteins/genetics , Toll-Like Receptor 2/metabolism , Virulence
15.
PLoS One ; 6(9): e24201, 2011.
Article in English | MEDLINE | ID: mdl-21915295

ABSTRACT

Francisella tularensis is a gram-negative facultative intracellular pathogen and the causative agent of tularemia. Recently, genome-wide screens have identified Francisella genes required for virulence in mice. However, the mechanisms by which most of the corresponding proteins contribute to pathogenesis are still largely unknown. To further elucidate the roles of these virulence determinants in Francisella pathogenesis, we tested whether each gene was required for replication of the model pathogen F. novicida within macrophages, an important virulence trait. Fifty-three of the 224 genes tested were involved in intracellular replication, including many of those within the Francisella pathogenicity island (FPI), validating our results. Interestingly, over one third of the genes identified are annotated as hypothetical, indicating that F. novicida likely utilizes novel virulence factors for intracellular replication. To further characterize these virulence determinants, we selected two hypothetical genes to study in more detail. As predicted by our screen, deletion mutants of FTN_0096 and FTN_1133 were attenuated for replication in macrophages. The mutants displayed differing levels of attenuation in vivo, with the FTN_1133 mutant being the most attenuated. FTN_1133 has sequence similarity to the organic hydroperoxide resistance protein Ohr, an enzyme involved in the bacterial response to oxidative stress. We show that FTN_1133 is required for F. novicida resistance to, and degradation of, organic hydroperoxides as well as resistance to the action of the NADPH oxidase both in macrophages and mice. Furthermore, we demonstrate that F. holarctica LVS, a strain derived from a highly virulent human pathogenic species of Francisella, also requires this protein for organic hydroperoxide resistance as well as replication in macrophages and mice. This study expands our knowledge of Francisella's largely uncharacterized intracellular lifecycle and demonstrates that FTN_1133 is an important novel mediator of oxidative stress resistance.


Subject(s)
Bacterial Proteins/metabolism , Francisella/metabolism , Francisella/pathogenicity , Hydrogen Peroxide/pharmacology , Macrophages/microbiology , Animals , Bacterial Proteins/genetics , Cell Line , Female , Francisella/genetics , Genomic Islands/genetics , Genomic Islands/physiology , Macrophages/metabolism , Mice , Mice, Inbred C57BL , NADPH Oxidases/genetics , NADPH Oxidases/metabolism , Real-Time Polymerase Chain Reaction , Virulence/genetics , Virulence/physiology
16.
PLoS One ; 6(6): e20609, 2011.
Article in English | MEDLINE | ID: mdl-21698237

ABSTRACT

BACKGROUND: Early detection of microorganisms by the innate immune system is provided by surface-expressed and endosomal pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs). Detection of microbial components by TLRs initiates a signaling cascade leading to the expression of proinflammatory cytokines including IL-6 and IL-1ß. Some intracellular bacteria subvert the TLR response by rapidly escaping the phagosome and entering the cytosol. However, these bacteria may be recognized by the inflammasome, a multi-protein complex comprised of a sensor protein, ASC and the cysteine protease caspase-1. Inflammasome activation leads to release of the proinflammatory cytokines IL-1ß and IL-18 and death of the infected cell, an important host defense that eliminates the pathogen's replicative niche. While TLRs and inflammasomes are critical for controlling bacterial infections, it is unknown whether these distinct host pathways cooperate to activate defenses against intracellular bacteria. METHODOLOGY/SIGNIFICANT FINDINGS: Using the intracellular bacterium Francisella novicida as a model, we show that TLR2(-/-) macrophages exhibited delayed inflammasome activation compared to wild-type macrophages as measured by inflammasome assembly, caspase-1 activation, cell death and IL-18 release. TLR2 also contributed to inflammasome activation in response to infection by the cytosolic bacterium Listeria monocytogenes. Components of the TLR2 signaling pathway, MyD88 and NF-κB, were required for rapid inflammasome activation. Furthermore, TLR2(-/-) mice exhibited lower levels of cell death, caspase-1 activation, and IL-18 production than wild-type mice upon F. novicida infection. CONCLUSIONS/SIGNIFICANCE: These results show that TLR2 is required for rapid inflammasome activation in response to infection by cytosolic bacterial pathogens. In addition to further characterizing the role of TLR2 in host defense, these findings broaden our understanding of how the host integrates signals from spatiotemporally separated PRRs to coordinate an innate response against intracellular bacteria.


Subject(s)
Francisella/physiology , Gram-Negative Bacterial Infections/metabolism , Inflammasomes/metabolism , Signal Transduction , Toll-Like Receptor 2/metabolism , Animals , Fluorescent Antibody Technique , Mice , Mice, Inbred C57BL , Mice, Knockout , Toll-Like Receptor 2/genetics
17.
J Biol Chem ; 277(49): 47517-23, 2002 Dec 06.
Article in English | MEDLINE | ID: mdl-12351624

ABSTRACT

Cytokines that signal through Class II receptors form a distinct family that includes the interferons and interleukin 10 (IL-10). Recent identification of several IL-10 homologs has defined a cytokine subfamily that includes AK155, IL-19, IL-20, IL-22, and IL-24. Within this subfamily, IL-19, IL-20, and IL-24 exhibit substantial sharing of receptor complexes; all three are capable of signaling through IL-20RA/IL-20RB, and IL-20 and IL-24 both can also use IL-22R/IL-20RB. However, the biological effects of these three cytokines appear quite distinct: immune activity with IL-19, skin biology with IL-20, and tumor apoptosis with IL-24. To more fully elucidate their interactions with the receptor complexes, we have performed a series of in vitro assays. Reporter, proliferation, and direct STAT activation assays using cell lines expressing transfected receptors revealed differences between the receptor complexes. IL-19 and IL-24 also exhibited growth inhibition on a cell line endogenously expressing all three receptor subunits, an effect that was seen at cytokine levels two orders of magnitude above those required for STAT activation or proliferation. These results demonstrate that, although this subclass exhibits receptor complex redundancy, there are differences in ligand/receptor interactions and in signal transduction that may lead to specificity and a distinct biology for each cytokine.


Subject(s)
Interleukin-10/chemistry , Interleukins/chemistry , Signal Transduction , Cell Division , Cell Line , Cytokines/metabolism , Dose-Response Relationship, Drug , Genes, Reporter , Genes, Tumor Suppressor , Humans , In Situ Hybridization , Interleukin-10/metabolism , Interleukins/metabolism , Ligands , Luciferases/metabolism , Lung/pathology , Protein Binding , Protein Transport , Reverse Transcriptase Polymerase Chain Reaction , Thymidine/chemistry , Tissue Distribution , Transfection , Tumor Cells, Cultured
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