Medicine and Health Sciences Commons^™

The Pseudomonas Aeruginosa Magnesium Transporter Mgte Inhibits Transcription Of The Type Iii Secretion System, Gregory G. Anderson, Timothy L. Yahr, Rustin R. Lovewell, George A. O'Toole

Dartmouth Scholarship

Pseudomonas aeruginosa is an opportunistic pathogen that causes life-long pneumonia in individuals with cystic fibrosis (CF). These long-term infections are maintained by bacterial biofilm formation in the CF lung. We have recently developed a model of P. aeruginosa biofilm formation on cultured CF airway epithelial cells. Using this model, we discovered that mutation of a putative magnesium transporter gene, called mgtE, led to increased cytotoxicity of P. aeruginosa toward epithelial cells. This altered toxicity appeared to be dependent upon expression of the type III secretion system (T3SS). In this study, we found that mutation of mgtE results in increased T3SS …

Salicylic Acid Diminishes Staphylococcus Aureus Capsular Polysaccharide Type 5 Expression, Lucia P. Alvarez, Maria S. Barbagelata, Mariana Gordiola, A. L. Cheung

Dartmouth Scholarship

Capsular polysaccharides (CP) of serotypes 5 (CP5) and 8 (CP8) are major Staphylococcus aureus virulence factors. Previous studies have shown that salicylic acid (SAL), the main aspirin metabolite, affects the expression of certain bacterial virulence factors. In the present study, we found that S. aureus strain Reynolds (CP5) cultured with SAL was internalized by MAC-T cells in larger numbers than strain Reynolds organisms not exposed to SAL. Furthermore, the internalization of the isogenic nonencapsulated Reynolds strain into MAC-T cells was not significantly affected by preexposure to SAL. Pretreatment of S. aureus strain Newman with SAL also enhanced internalization into MAC-T …

The Staphylococcus-Specific Gene Rsr Represses Agr And Virulence In Staphylococcus Aureus, Sandeep Tamber, Dindo Reyes, Niles P. Donegan, Joseph D. Schwartzman, Ambrose L. Cheung, Guido Memmi

Dartmouth Scholarship

The expression of virulence factors in Staphylococcus aureus is tightly coordinated by a vast network of regulatory molecules. In this report, we characterize a genetic locus unique to staphylococci called rsr that has a role in repressing two key virulence regulators, sarR and agr. Using strain SH1000, we showed that the transcription of virulence effectors, such as hla, sspA, and spa, is altered in an rsr mutant in a way consistent with agr upregulation. Analysis of RNAIII expression of the agr locus in rsr and rsr-sarR mutants indicated that rsr likely contributes to agr expression independently …

Anti-Hiv Activity In Cervical-Vaginal Secretions From Hiv-Positive And -Negative Women Correlate With Innate Antimicrobial Levels And Igg Antibodies, Mimi Ghosh, John V. Fahey, Zheng Shen, Timothy Lahey, Susan Cu-Uvin, Zhijin Wu, Kenneth Mayer, Peter F. Wright, John C. Kappes, Christina Ochsenbauer, Charles R. Wira

Dartmouth Scholarship

Background: We investigated the impact of antimicrobials in cervicovaginal lavage (CVL) from HIV(+) and HIV(2) women on target cell infection with HIV. Since female reproductive tract (FRT) secretions contain a spectrum of antimicrobials, we hypothesized that CVL from healthy HIV(+) and (2) women inhibit HIV infection.

Methodology/Principal Findings: CVL from 32 HIV(+) healthy women with high CD4 counts and 15 healthy HIV(2) women were collected by gently washing the cervicovaginal area with 10 ml of sterile normal saline. Following centrifugation, anti- HIV activity in CVL was determined by incubating CVL with HIV prior to addition to TZM-bl cells. Antimicrobials and …

Role Of Pknb Kinase In Antibiotic Resistance And Virulence In Community-Acquired Methicillin-Resistant Staphylococcus Aureus Strain Usa300, S. Tamber, J. Schwartzman, A. L. Cheung

Dartmouth Scholarship

The regulation of cellular processes by eukaryote-like serine/threonine kinases is widespread in bacteria. In the last 2 years, several studies have examined the role of serine/threonine kinases in Staphylococcus aureus on cell wall metabolism, autolysis, and virulence, mostly in S. aureus laboratory isolates in the 8325-4 lineage. In this study, we showed that the pknB gene (also called stk1) of methicillin-resistant S. aureus (MRSA) strain COL and the community-acquired MRSA (CA-MRSA) strain USA300 is involved in cell wall metabolism, with the pknB mutant exhibiting enhanced sensitivity to β-lactam antibiotics but not to other classes of antibiotics, including aminoglycosides, ciprofloxacin, …

Cd4 T-Cell Suppression By Cells From Toxoplasma Gondii-Infected Retinas Is Mediated By Surface Protein Pd-L1, Elizabeth Charles, Sunil Joshi, John D. Ash, Barbara A. Fox

Dartmouth Scholarship

In the inflamed retina, CD4(+) T cells can cause retinal damage when they are not properly regulated. Since tissue expression of major histocompatibility complex (MHC) class II and costimulatory molecules is a key mechanism for regulating effector T cells, we tested the hypothesis that upregulation of these proteins in the retina contributes to the regulation of CD4 T cells. Here we report that in retinas infected with the protozoan parasite Toxoplasma gondii, MHC class II is upregulated on infiltrating leukocytes as well as on resident retinal cells, including photoreceptors. Flow cytometric analysis indicated that B7 costimulatory family members (CD80, CD86, …

Pseudomonas Aeruginosa Evasion Of Phagocytosis Is Mediated By Loss Of Swimming Motility And Is Independent Of Flagellum Expression, Eyal Amiel, Rustin R. Lovewell, George A. O'Toole, Deborah A. Hogan, Brent Berwin

Dartmouth Scholarship

Pseudomonas aeruginosa is a pathogenic Gram-negative bacterium that causes severe opportunistic infections in immunocompromised individuals; in particular, severity of infection with P. aeruginosa positively correlates with poor prognosis in cystic fibrosis (CF) patients. Establishment of chronic infection by this pathogen is associated with downregulation of flagellar expression and of other genes that regulate P. aeruginosa motility. The current paradigm is that loss of flagellar expression enables immune evasion by the bacteria due to loss of engagement by phagocytic receptors that recognize flagellar components and loss of immune activation through flagellin-mediated Toll-like receptor (TLR) signaling. In this work, we employ bacterial …

Humoral Immunity In Tuberculin Skin Test Anergy And Its Role In High-Risk Persons Exposed To Active Tuberculosis, Liliana Encinales, Joaquin Zuñiga, Julio Granados-Montiel, Maria Yunis, Julio Granados, Ingrid Almeciga, Olga Clavijo, Carlos Awad, Vilma Collazos, María Inés Vargas-Rojas, José Luis Bañales-Mendez, Lilia Vazquez-Castañeda, Joel N Stern, Viviana Romero, Masha Fridkis-Hareli, Masha Frindkis-Hareli, Daniel Terreros, Marcelo Fernandez-Viña, Edmond J Yunis

Journal Articles

The most common test to identify latent tuberculosis is the tuberculin skin test that detects T cell responses of delayed type hypersensitivity type IV. Since it produces false negative reactions in active tuberculosis or in high-risk persons exposed to tuberculosis patients as shown in this report, we studied antibody profiles to explain the anergy of such responses in high-risk individuals without active infection. Our results showed that humoral immunity against tuberculin, regardless of the result of the tuberculin skin test is important for protection from active tuberculosis and that the presence of high antibody titers is a more reliable indicator …

Biomarkers In Systemic Sclerosis., Susan V. Castro, Sergio A. Jimenez

Scleroderma Center Faculty Papers

Systemic sclerosis is an autoimmune inflammatory disorder of unknown etiologycharacterized b y pronounced fibroproliferative alterations in the microvasculature, and frequent cellular and humoral immunity abnormalities, culminating in a severe and often progressive fibrotic process. Numerous biomarkers reflecting the three main pathogenetic mechanisms in systemic sclerosis have been described; however, aside from several disease-specific autoantibodies, other biomarkers have not been thoroughly validated and require further study. Thus, there is an unmet need for validated biomarkers for diagnosis, disease classification, and evaluation of organ involvement and therapeutic response in systemic sclerosis.

Defensins In Ocular Immunity, Minhao Wu

Wayne State University Dissertations

Corneal infection with P. aeruginosa results in corneal perforation in susceptible

B6, but not resistant BALB/c mice. This study explored their role mBD 1-4 in corneal

infection, and their potential synergy. Immunostaining and real-time RT-PCR data

demonstrated that their expression was either constitutive (mBD1 and mBD2) or

inducible (mBD3 and mBD4) in normal BALB/c and B6 corneas, and disparately

regulated in BALB/c vs B6 corneas after infection. Knock down studies using siRNA

treatment indicated that mBD2 and mBD3, but neither mBD1 nor mBD4, is required in

ocular defense. Moreover, in vivo studies demonstrated individual and combined effects

of mBD2 and …

The Development Of Humoral And Cellular Responses To Plasmodium Falciparum Malaria In The Hypoendemic Peruvian Amazon And Potential Clinical Protection, Eva Helen Clark

All ETDs from UAB

Each year 300-500 million cases of Plasmodium falciparum malaria occur, leading to more than 1 million deaths. In high malaria transmission regions, development of immunity from severe infection requires 2-10 years of persistent parasitemia. This delay has been attributed to difficulties in the development of protective humoral responses. Indeed, anti-malarial antibody responses tend to be short-lived, and immunologic memory seems to be dysfunctional in high-transmission regions. In contrast, in the low-transmission Peruvian Amazon >60% of infections are asymptomatic, suggesting that clinical immunity occurs despite low parasite exposure. To analyze more precisely the naturally-acquired humoral responses to malarial antigens and their …

Population Genetic Analysis Of Large Sequence Polymorphisms In Plasmodium Falciparum Blood-Stage Antigens, A.D. Ahouidi, A.K. Bei, D.E. Neafsey, O. Sarr, S. Volkman, D. Milner, J. Cox-Singh, M.U. Ferreira, O. Ndir, Zul Premji, S. Mboup, M.T. Duraisingh

Pathology, East Africa

Plasmodium falciparum, the causative agent of human malaria, invades host erythrocytes using several proteins on the surface of the invasive merozoite, which have been proposed as potential vaccine candidates. Members of the multi-gene PfRh family are surface antigens that have been shown to play a central role in directing merozoites to alternative erythrocyte receptors for invasion. Recently, we identified a large structural polymorphism, a 0.58 Kb deletion, in the C-terminal region of the PfRh2b gene, present at a high frequency in parasite populations from Senegal. We hypothesize that this region is a target of humoral immunity. Here, by analyzing 371 …

Mechanisms Of Major Outer Membrane Protein (Momp)-Vaccine Induced Protective Immunity Against Chlamydia Muridarum Genital Infection, Christina M. Farris

All ETDs from UAB

Urogenital infection with Chlamydia trachomatis is the most common bacterial sexually transmit-ted disease with an estimated 90 million new infections occurring each year worldwide. In women infection with C. trachomatis can result in serious complications including ectopic pregnancy, pelvic inflammatory disease and tubal factor infertility. Despite very effective antimicrobial chemotherapy, control of the infection will likely require an effective vaccine. We have assessed the protective effect of an outer membrane based vaccine using a murine model of chlamydial genital tract infection. Female mice were vaccinated with C. muridarum major outer membrane protein (MOMP) plus the immunostimulatory adjuvants CpG-1826 and Montanide …