Browsing by Subject "Asthma exacerbations"

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    Clinical and molecular implications of RGS2 promoter genetic variation in severe asthma
    (Elsevier, 2022) Cardet, Juan Carlos; Kim, Donghwa; Bleecker, Eugene R.; Casale, Thomas B.; Israel, Elliot; Mauger, David; Meyers, Deborah A.; Ampleford, Elizabeth; Hawkins, Gregory A.; Tu, Yaping; Liggett, Stephen B.; Ortega, Victor E.; SARP-3 investigators; Pediatrics, School of Medicine
    Background: Regulator of G protein signaling (RGS) 2 terminates bronchoconstrictive Gαq signaling; murine RGS2 knockout demonstrate airway hyperresponsiveness. While RGS2 promoter variants rs2746071 and rs2746072 associate with a clinical mild asthma phenotype, their impact on human airway smooth muscle (HASM) contractility and asthma severity outcomes is unknown. Objective: We sought to determine whether reductions in RGS2 expression seen with these 2 RGS2 promoter variants augment HASM contractility and associate with an asthma severity phenotype. Methods: We transfected HASM with a range of RGS2-specific small interfering RNA (siRNA) concentrations and determined RGS2 protein expression by Western blot analysis and intracellular calcium flux induced by histamine (a Gαq-coupled H1 receptor bronchoconstrictive agonist). We conducted regression-based genotype association analyses of RGS2 variants from 611 patients from the National Heart, Lung, and Blood Institute Severe Asthma Research Program 3. Results: RGS2-specific siRNA caused dose-dependent increases in histamine-stimulated bronchoconstrictive intracellular calcium signaling (2-way ANOVA, P < .0001) with a concomitant decrease in RGS2 protein expression. RGS2-specific siRNA did not affect Gαq-independent ionomycin-induced intracellular calcium signaling (P = .42). The minor allele frequency of rs2746071 and rs2746072 was 0.46 and 0.28 among African American/non-Hispanic Black patients and was 0.28 and 0.27 among non-Hispanic White patients, among whom these single nucleotide polymorphisms were in stronger linkage disequilibrium (r2 = 0.97). Among non-Hispanic White patients, risk allele homozygotes for rs2746072 and rs2746071 each had nearly 2-fold greater asthma exacerbation rates relative to alternative genotypes with wild-type alleles (Padditive = 2.86 × 10-5/Precessive = 5.22 × 10-6 and Padditive = 3.46 × 10-6/Precessive = 6.74 × 10-7, respectively) at baseline, which was confirmed by prospective longitudinal exacerbation data. Conclusion: RGS2 promoter variation associates with a molecular and clinical phenotype characterized by enhanced bronchoconstrictive stimulation in vitro and higher asthma exacerbations rates in non-Hispanic White patients.
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    Determinants of Lung Function Across Childhood in the Severe Asthma Research Program (SARP) 3
    (Elsevier, 2023) Gaffin, Jonathan M.; Petty, Carter R.; Sorkness, Ronald L.; Denlinger, Loren C.; Phillips, Brenda R.; Ly, Ngoc P.; Gaston, Benjamin; Ross, Kristie; Fitzpatrick, Anne; Bacharier, Leonard B.; DeBoer, Mark D.; Teague, W. Gerald; Wenzel, Sally E.; Ramratnam, Sima; Israel, Elliot; Mauger, David T.; Phipatanakul, Wanda; National Heart, Lung and Blood Institute’s Severe Asthma Research Program-3 Investigators; Pediatrics, School of Medicine
    Background: Children with asthma are at risk for low lung function extending into adulthood, but understanding of clinical predictors is incomplete. Objective: We sought to determine phenotypic factors associated with FEV1 throughout childhood in the Severe Asthma Research Program 3 pediatric cohort. Methods: Lung function was measured at baseline and annually. Multivariate linear mixed-effects models were constructed to assess the effect of baseline and time-varying predictors of prebronchodilator FEV1 at each assessment for up to 6 years. All models were adjusted for age, predicted FEV1 by Global Lung Function Initiative reference equations, race, sex, and height. Secondary outcomes included postbronchodilator FEV1 and prebronchodilator FEV1/forced vital capacity. Results: A total of 862 spirometry assessments were performed for 188 participants. Factors associated with FEV1 include baseline Feno (B, -49 mL/log2 PPB; 95% CI, -92 to -6), response to a characterizing dose of triamcinolone acetonide (B, -8.4 mL/1% change FEV1 posttriamcinolone; 95% CI, -12.3 to -4.5), and maximal bronchodilator reversibility (B, -27 mL/1% change postbronchodilator FEV1; 95% CI, -37 to -16). Annually assessed time-varying factors of age, obesity, and exacerbation frequency predicted FEV1 over time. Notably, there was a significant age and sex interaction. Among girls, there was no exacerbation effect. For boys, however, moderate (1-2) exacerbation frequency in the previous 12 months was associated with -20 mL (95% CI, -39 to -2) FEV1 at each successive year. High exacerbation frequency (≥3) 12 to 24 months before assessment was associated with -34 mL (95% CI, -61 to -7) FEV1 at each successive year. Conclusions: In children with severe and nonsevere asthma, several clinically relevant factors predict FEV1 over time. Boys with recurrent exacerbations are at high risk of lower FEV1 through childhood.