Poster Session Abstracts
377
DHQ activates PqsR to initiate transcription of the operon for subsequent
virulence factor production.
Preliminary data generated from sputum samples by CF outpatients
maintaining their lung functions contained a median DHQ concentration of
175 μM (SE 204, n=28). Trends of DHQ during an exacerbation demonstrated a decline in concentration between admission day 1 and final hospitalized day (n=3). This study will enroll up to 70 patients and quantify
samples from both outpatient and inpatient groups for two years. Patient
data, such as %FEV1, antibiotic usage, cultured organisms, and CF genotype, will be used to striate data for trend analysis.
Discussion: This study demonstrated DHQ is an important component
of the Pqs system for virulence factor production. Quantification of DHQ
in patient samples indicates that DHQ may also be used as a biomarker
for exacerbated disease stage since DHQ is linked to both virulence factor
production and toxicity towards the host.
PH-DEPENDENT DIFFERENTIAL PSEUDOMONAS
AERUGINOSA KILLING IN CF SPUTUM INCUBATED IN
HYPERTONIC SALINE SOLUTIONS
Burns, J.L.1,2; Griffith, A.1 1. Pediatrics, Seattle Children’s
Research Institute, Seattle, WA, USA; 2. Pediatrics, University of
Washington, Seattle, WA, USA
The use of 7% hypertonic saline (7%HS) has proven useful as a mechanism of airway clearance in individuals with CF. A number of studies
have demonstrated improved lung function, accelerated mucus clearance,
fewer pulmonary exacerbations and a higher percentage of patients without
exacerbations. The majority of currently available 7%HS solutions follow
USP guidelines and have a pH between 4.5 and 7.0. The average is pH 6.2,
although there can be variability between each batch produced by an individual company. A recently released 7%HS solution is pH controlled with a
pH of 7.4, which is within the NIH range for physiologic pH in the human
lung (pH 7.38 to 7.42), although not within USP guidelines. Based on data
in the literature reporting that CF airway surface liquid is acidic, which may
contribute to the poor clearance of P. aeruginosa, we hypothesized that
addition of a 7%HS solution that was physiologic pH would decrease P.
aeruginosa density over time more than acidic 7%HS solutions. We tested
this by performing 24-hour killing curves in sterilized CF sputum that was
“spiked” with P. aeruginosa PA01 and diluted 10% wt/vol in commercial
saline products of differing pH. We used three different 7%HS products:
pH 5.86 (HyperSal®, PARI), pH 6.6 (generic 7%HS, Nephron) and pH
7.4 (PulmoSal™7% (pH+)™, PharmaCaribe). Results are shown in the
figure. These data show approximately 5 log decrease in bacterial density
in the pH 7.4 solution compared with approximately 2 log decrease in the
pH 5.86 and pH 6.6 solutions at 24 hours. The density difference between
solutions is even more dramatic at 8 and 12 hours. These results suggest that
a clinical trial designed to determine if increasing the pH of 7%HS reduces
microbial density may be warranted. Given the dosing frequency of 7%HS
in CF, these findings suggest that the use of physiologic pH+ solution could
have a marked impact on bacterial density in CF sputum. Supported by
PharmaCaribe LLC, Punta Gorda, FL, W. Randolph Warner, Werner Gutmann; Scientific Advisory Preston Campbell, Daniel Klein, Cystic Fibrosis
Foundation, Bethesda, MD.
376
TAS2R38 GENOTYPE IMPLICATIONS IN BASELINE
LUNG FUNCTION IN ΔF508 HOMOZYGOUS CYSTIC
FIBROSIS PATIENTS
Adappa, N.D.1; Hadjiliadis, D.2; Dorgan, D.2; Frame, D.M.2;
Lee, R.J.1; Palmer, J.N.1; Cohen, N.A.1 1. Otorhinolaryngology,
University of Pennsylvania, Philadelphia, PA, USA; 2. Division
of Pulmonary, Allergy, and Critical Care, University of
Pennsylvania, Philadelphia, PA, USA
Introduction: The bitter taste receptor T2R38 was recently identified to regulate upper airway innate defenses through nitric oxide (NO)
production in response to Gram-negative microbial quorum sensing molecules yielding direct bactericidal activity as well as stimulating mucociliary clearance (Lee RJ, et al. J Clin Invest. 2012;122:4145-59). Previous
investigations demonstrated that the robustness of defensive responses is
modulated by common polymorphisms within the TAS2R38 gene which
consist of either a proline/alanine/valine (PAV) or alanine/valine/isoleucine
(AVI) at positions 29, 262 and 296. Thus the predominant haplotypes are
PAV or AVI. Individuals with the PAV/PAV genotype demonstrate the
greatest upregulation of NO and mucociliary clearance to quorum sensing
molecules. Conversely, those with the PAV/AVI AND AVI/AVI genotype
demonstrate minimal antimicrobial or mucociliary clearance activity in
response to quorum sensing molecules. It has also been demonstrated that
in non-CF patients, those with the PAV/PAV genotype do not require sinus
surgery as frequently as other polymorphisms (p value 0.038) (Adappa ND,
et al. Int Forum Allergy Rhinol. 2014;4:3-7). While the vast majority of CF
patients have radiographic evidence of chronic sinus pathology, it is unclear
why some CF patients develop sinusitis symptomatology while others do
not and whether this may play a role in pulmonary outcomes.
Methods: Determine whether the protective polymorphism in the
TAS2R38 gene (PAV/PAV) is predictive of pulmonary function and sinonasal quality of life (QoL) in an adult CF ΔF508 homozygous population. A prospective study was performed on patients who were genotyped
for TAS2R38 and evaluated with a validated sinonasal outcomes test-22
(SNOT-22) as well as baseline predicted FEV1% and FVC%. Other factors
including age, sex, lung transplant status, body mass index, and diabetes
status were also evaluated. A one-way ANOVA was performed for statistical analysis.
Results: We genotyped 43 ΔF508 homozygous patients. The distribution included 8 PAV/PAV, 21 PAV/AVI, and 14 AVI/AVI. The baseline
FEV1% was 70.3 for the PAV/PAV group and 56.9 for the other polymorphisms (p value 0.089) and the FVC% was 87.5 for the PAV/PAV group
and 71.7 for the others (p value 0.065). The mean SNOT-22 score was 21.3
for PAV/PAV and 25.1 for the other genotypes (p value 0.566)
Conclusion: In a homogenous population of adult CF ΔF508 homozygous patients, the protective T2R38 genotype (PAV/PAV) demonstrates a
very strong trend for improved lung function both for baseline FEV1% and
FVC%. Further investigation in a larger population is warranted based on
these promising data on a novel bitter taste receptor that may be a disease
modifier in the CF population.
Supported by the Cystic Fibrosis Foundation Pilot and Feasibility
Award as well as the American Rhinology Society Young Investigator
Award.
Peds Pulmonol 2014. 49; S38: 351.
Supplement to the 28th NACFC, Atlanta,
351
216-456_NACFC14_Abstracts-5.indd 351
8/12/14 3:40 PM