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Staphylococcus Aureus Alpha-Toxin Augments Viral Load In Keratinocytes
AB206 Abstracts
775
Staphylococcus Aureus Alpha-Toxin Augments Viral Load In Keratinocytes L. Bin1, E. Goleva1, J. Streib1, C. Hall1, P. M. Schlievert2, D. Y. Leung1; 1 National Jewish Health, Denver, CO, 2The University of Iowa, Iowa City, IA. RATIONALE: The factor(s) leading to increase propensity of disseminated herpes simplex virus (HSV) and vaccinia virus (VV) infections in atopic dermatitis (AD) are poorly understood. A history of eczema herpeticum is frequently associated with Staphylococcus aureus infection. This study investigated whether S. aureus toxins augment viral load in normal human keratinocytes (NHK). METHODS: NHK were pretreated with commercially purified staphylococcal enterotoxin (SE) B, toxic shock syndrome toxin 1(TSST1), lipoteichoic acid (LTA), peptidoglycan (PGN), and a-toxin; then incubated with VV or HSV-1 for up to 24 hours. Viral replication was evaluated by real-time PCR and viral plaque assay. RESULTS: SEB, TSST1, and sublytic concentrations of a-toxin significantly increased viral load of VVand HSV-1 in NHK. In contrast, LTA and PGN had no effect on viral load in NHK. Using mass spectrometry and western-blot, we found that commercial SEB and TSST1 prepared from S. aureus cultures were contaminated with a-toxin. Recombinant SEB and TSST1, free of a-toxin, did not enhance viral load in NHK, suggesting that viral enhancement in commercial SEB/TSST1 was from a-toxin contamination. Purified a-toxin (40ng/ml) treated NHK, however, showed increased VV (mean: 0.7260.13 ng VV/ng 18S compared with mock treatment 0.0760.02; p<0.01) and HSV-1 loads (mean: 241.4611.4 ng HSV-1/ng 18S compared to mock treatment 91.1622.7; p<0.01). The mechanism by which sublytic a-toxin increases viral load was related to increased virus uptake into NHK. CONCLUSIONS: S. aureus a-toxin augments viral load in keratinocytes. This novel observation suggests that cutaneous S. aureus on AD skin may increase susceptibility to disseminated viral infections.
776
MONDAY
Genetic Variants Associated with Asthma and Related Phenotypes are Also Risk Factors for Food Allergy C. Vergara1, N. Rafaels1, L. Gao1, C. Foster1, M. Campbell1, J. Potee1, R. Lewis1, T. H. Beaty2, S. Jones3, A. W. Burks4, S. Sicherer5, R. A. Wood6, D. Stablein6, L. A. Beck7, H. A. Sampson8, A. H. Liu8, D. Y. Leung7,8, R. A. Mathias1,9, K. C. Barnes1; 1Division of Allergy and Clinical Immunology, Department of Medicine, The Johns Hopkins University, Baltimore, MD, 2 Department of Epidemiology, Bloomberg School of Public Health, JHU, Baltimore, MD, 3University of Arkansas for Medical Sciences, Little Rock, AR, 4Duke University Medical Center, Durham, NC, 5Mount Sinai School of Medicine, New York, NY, 6The EMMES Corporation, Rockville, MD, 7Department of Dermatology, University of Rochester Medical Center, Rochester, NY, 8Department of Pediatrics, National Jewish Health, Denver, CO, 9Division of General Internal Medicine, Department of Medicine, The Johns Hopkins University, Baltimore, MD. RATIONALE: The high co-morbidity of food allergy (FA) and sensitization (FS) with other IgE-mediated diseases such as asthma, suggests common genetic determinants. We tested this hypothesis for a set of GWAS-identified candidate genes for asthma/atopy in FA/FS. METHODS: 359 single nucleotide polymorphisms (SNPs) representing 46 asthma/total IgE GWAS-identified genes were genotyped (Illumina BeadExpress) in a discovery cohort (Consortium of Food Allergy Research, CoFAR:NIAID) of 317 European-American (EA) and 70 African-American (AA) children with atopic dermatitis (AD) and clinical and/or serologic evidence of FA (milk/egg/peanut) and 270 EA and 332 AA non-FA-non-AD controls. Replication was sought in Atopic Dermatitis Research Network (ADRN:NIAID) participants:139 EA and 84 AA AD cases characterized for FS using a multiallergenspecific Phadia ImmunoCAP tests (FX5E) and compared to 114 EA and 107 AA AD cases without FS, respectively. Association tests were conducted within a logistic framework including relevant covariates. RESULTS: In CoFAR, 7 SNPs were significantly associated with FA risk _2.9x10-5). Six of these mapped to in EA (Bonferonni-corrected-P-values<
J ALLERGY CLIN IMMUNOL FEBRUARY 2012
GPR126, PDE4D, PTCH1, GSTCD and IL13. Another 17 SNPs representing 7 genes (DENND1B, IL1R1, SMAD3, IL-10, ADAM33, RAD50 and ADCY2) were associated at P50.0005-0.041 in EA and AA, but failed Bonferonni corrections. A gene-based-replication for FS was observed for PDE4D in EA and AA of the AD ADRN cohort with lower statistical evidence (uncorrected P50.002). CONCLUSIONS: Genetic variants in genes associated with asthma and high total IgE levels (i.e., PDE4D) may be risk factors for FA/FS in AD individuals.
777
Reliability, Validity, and Responsiveness of the Asthma Control Questionnaire among Pediatric Patients J. M. Nguyen1, J. Holbrook2, C. Bime1, W. G. Teague3, R. A. Wise1, for the American Lung Association-ACRC1. 1Johns Hopkins University School of Medicine, Baltimore, MD, 2Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, 3University of Virginia Children’s Hospital, Charlottesville, VA. RATIONALE: The Juniper Asthma Control Questionnaire (ACQ) represents a concise, patient-centered tool for evaluating asthma control. It has been validated in the adult population but its validity among children is not as well-established. We hypothesize that the ACQ is a reliable, valid, and responsive tool for identifying poorly-controlled asthma among pediatric patients ages 6 to 17. METHODS: Approximately three hundred pediatric asthmatic patients from 18 different U.S. outpatient centers completed the ACQ at 9 separate visits (4 weeks apart). Patients ages 6 to 10 had the assistance of an adult in completing the ACQ. RESULTS: Internal consistency reliability of the ACQ was 0.74 (baseline) for the overall group and did not differ significantly for separate age brackets (ages 6 to 10, and 11 to 17). Construct validity was shown through significant correlation between baseline ACQ scores and ACT scores (r 5 -0.54, p<0.001). Discriminant validity was demonstrated through significant differences in mean ACQ scores across patients differing based on the presence or absence of an exacerbation event (p <0.001). Responsiveness of the ACQ was shown through significant differences in mean changes in ACQ scores across patients differing in changes in ACT scores (p<0.001) and pulmonary function (p<0.001). A minimally important difference based on differences in ACQ scores across patient groups differing on criterion measures was determined to be 0.482 points (range 0.28 to 0.65). CONCLUSIONS: The ACQ is a reliable, valid, and responsive tool for assessing asthma control among pediatric patients in the research setting with meaningful implications for use in the clinical setting.
775
Staphylococcus Aureus Alpha-Toxin Augments Viral Load In Keratinocytes L. Bin1, E. Goleva1, J. Streib1, C. Hall1, P. M. Schlievert2, D. Y. Leung1; 1 National Jewish Health, Denver, CO, 2The University of Iowa, Iowa City, IA. RATIONALE: The factor(s) leading to increase propensity of disseminated herpes simplex virus (HSV) and vaccinia virus (VV) infections in atopic dermatitis (AD) are poorly understood. A history of eczema herpeticum is frequently associated with Staphylococcus aureus infection. This study investigated whether S. aureus toxins augment viral load in normal human keratinocytes (NHK). METHODS: NHK were pretreated with commercially purified staphylococcal enterotoxin (SE) B, toxic shock syndrome toxin 1(TSST1), lipoteichoic acid (LTA), peptidoglycan (PGN), and a-toxin; then incubated with VV or HSV-1 for up to 24 hours. Viral replication was evaluated by real-time PCR and viral plaque assay. RESULTS: SEB, TSST1, and sublytic concentrations of a-toxin significantly increased viral load of VVand HSV-1 in NHK. In contrast, LTA and PGN had no effect on viral load in NHK. Using mass spectrometry and western-blot, we found that commercial SEB and TSST1 prepared from S. aureus cultures were contaminated with a-toxin. Recombinant SEB and TSST1, free of a-toxin, did not enhance viral load in NHK, suggesting that viral enhancement in commercial SEB/TSST1 was from a-toxin contamination. Purified a-toxin (40ng/ml) treated NHK, however, showed increased VV (mean: 0.7260.13 ng VV/ng 18S compared with mock treatment 0.0760.02; p<0.01) and HSV-1 loads (mean: 241.4611.4 ng HSV-1/ng 18S compared to mock treatment 91.1622.7; p<0.01). The mechanism by which sublytic a-toxin increases viral load was related to increased virus uptake into NHK. CONCLUSIONS: S. aureus a-toxin augments viral load in keratinocytes. This novel observation suggests that cutaneous S. aureus on AD skin may increase susceptibility to disseminated viral infections.
776
MONDAY
Genetic Variants Associated with Asthma and Related Phenotypes are Also Risk Factors for Food Allergy C. Vergara1, N. Rafaels1, L. Gao1, C. Foster1, M. Campbell1, J. Potee1, R. Lewis1, T. H. Beaty2, S. Jones3, A. W. Burks4, S. Sicherer5, R. A. Wood6, D. Stablein6, L. A. Beck7, H. A. Sampson8, A. H. Liu8, D. Y. Leung7,8, R. A. Mathias1,9, K. C. Barnes1; 1Division of Allergy and Clinical Immunology, Department of Medicine, The Johns Hopkins University, Baltimore, MD, 2 Department of Epidemiology, Bloomberg School of Public Health, JHU, Baltimore, MD, 3University of Arkansas for Medical Sciences, Little Rock, AR, 4Duke University Medical Center, Durham, NC, 5Mount Sinai School of Medicine, New York, NY, 6The EMMES Corporation, Rockville, MD, 7Department of Dermatology, University of Rochester Medical Center, Rochester, NY, 8Department of Pediatrics, National Jewish Health, Denver, CO, 9Division of General Internal Medicine, Department of Medicine, The Johns Hopkins University, Baltimore, MD. RATIONALE: The high co-morbidity of food allergy (FA) and sensitization (FS) with other IgE-mediated diseases such as asthma, suggests common genetic determinants. We tested this hypothesis for a set of GWAS-identified candidate genes for asthma/atopy in FA/FS. METHODS: 359 single nucleotide polymorphisms (SNPs) representing 46 asthma/total IgE GWAS-identified genes were genotyped (Illumina BeadExpress) in a discovery cohort (Consortium of Food Allergy Research, CoFAR:NIAID) of 317 European-American (EA) and 70 African-American (AA) children with atopic dermatitis (AD) and clinical and/or serologic evidence of FA (milk/egg/peanut) and 270 EA and 332 AA non-FA-non-AD controls. Replication was sought in Atopic Dermatitis Research Network (ADRN:NIAID) participants:139 EA and 84 AA AD cases characterized for FS using a multiallergenspecific Phadia ImmunoCAP tests (FX5E) and compared to 114 EA and 107 AA AD cases without FS, respectively. Association tests were conducted within a logistic framework including relevant covariates. RESULTS: In CoFAR, 7 SNPs were significantly associated with FA risk _2.9x10-5). Six of these mapped to in EA (Bonferonni-corrected-P-values<
J ALLERGY CLIN IMMUNOL FEBRUARY 2012
GPR126, PDE4D, PTCH1, GSTCD and IL13. Another 17 SNPs representing 7 genes (DENND1B, IL1R1, SMAD3, IL-10, ADAM33, RAD50 and ADCY2) were associated at P50.0005-0.041 in EA and AA, but failed Bonferonni corrections. A gene-based-replication for FS was observed for PDE4D in EA and AA of the AD ADRN cohort with lower statistical evidence (uncorrected P50.002). CONCLUSIONS: Genetic variants in genes associated with asthma and high total IgE levels (i.e., PDE4D) may be risk factors for FA/FS in AD individuals.
777
Reliability, Validity, and Responsiveness of the Asthma Control Questionnaire among Pediatric Patients J. M. Nguyen1, J. Holbrook2, C. Bime1, W. G. Teague3, R. A. Wise1, for the American Lung Association-ACRC1. 1Johns Hopkins University School of Medicine, Baltimore, MD, 2Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, 3University of Virginia Children’s Hospital, Charlottesville, VA. RATIONALE: The Juniper Asthma Control Questionnaire (ACQ) represents a concise, patient-centered tool for evaluating asthma control. It has been validated in the adult population but its validity among children is not as well-established. We hypothesize that the ACQ is a reliable, valid, and responsive tool for identifying poorly-controlled asthma among pediatric patients ages 6 to 17. METHODS: Approximately three hundred pediatric asthmatic patients from 18 different U.S. outpatient centers completed the ACQ at 9 separate visits (4 weeks apart). Patients ages 6 to 10 had the assistance of an adult in completing the ACQ. RESULTS: Internal consistency reliability of the ACQ was 0.74 (baseline) for the overall group and did not differ significantly for separate age brackets (ages 6 to 10, and 11 to 17). Construct validity was shown through significant correlation between baseline ACQ scores and ACT scores (r 5 -0.54, p<0.001). Discriminant validity was demonstrated through significant differences in mean ACQ scores across patients differing based on the presence or absence of an exacerbation event (p <0.001). Responsiveness of the ACQ was shown through significant differences in mean changes in ACQ scores across patients differing in changes in ACT scores (p<0.001) and pulmonary function (p<0.001). A minimally important difference based on differences in ACQ scores across patient groups differing on criterion measures was determined to be 0.482 points (range 0.28 to 0.65). CONCLUSIONS: The ACQ is a reliable, valid, and responsive tool for assessing asthma control among pediatric patients in the research setting with meaningful implications for use in the clinical setting.