Impact of T2R38 receptor polymorphisms on Pseudomonas aeruginosa infection in cystic fibrosis

The T2R38 (taste receptor 2 member 38) bitter taste receptor on respiratory epithelia detects Pseudomonas aeruginosa N-acyl-l-homoserine lactones (AHLs). In vitro, T2R38 activation by AHLs initiates calcium-mediated increases in nitric oxide production and ciliary beat frequency, dependent on polymorphisms in the TAS2R38 gene (1). In patients with chronic rhinosinusitis, the TAS2R38 genotype is proposed to modify mucosal responses to P. aeruginosa (1). Polymorphisms in the TAS2R38 gene result in two high-frequency haplotypes associated with taste perception of the bitter compound phenylthiocarbamide (2). The “taster” haplotype codes proline-alanine-valine (PAV), and the “nontaster” haplotype codes alanine-valine-isoleucine (AVI) at positions 49, 262, and 296 in the receptor protein. Responses to AHLs in vitro are greatest in PAV/PAV epithelial cells, and this genotype is reported to be protective against P. aeruginosa in the sinonasal airway (1). P. aeruginosa is the most frequently isolated respiratory pathogen in cystic fibrosis (CF), and chronic infection is associated with accelerated rates of disease progression. Determining the impact of TAS2R38 polymorphisms on P. aeruginosa infection in CF could have implications for patient risk stratification and, as naturally occurring and synthetic agonists to T2R38 are already in clinical use (3), could identify promising therapeutic targets. We characterized T2R38 localization in the CF airway and investigated the hypothesis that TAS2R38 polymorphisms would modify the prevalence and impact of P. aeruginosa infection in CF. Some of the results of these studies have previously been reported in the form of abstracts

Limb strength gain of all the groups in both study cohorts.

<p>Mean values and standard deviation of limb strength gain of the immobilization (top panel) and recovery (bottom panel) cohorts of mice. Definition of abbreviations: I, immobilization; R, recovery. Statistical significance is represented as follows: **, p≤0.01, and ***, p≤0.001 between any of the immobilized animals and the non-immobilized controls; §, p≤0.05, §§§, p≤0.001, and n.s., non-significant differences between any of the R groups of animals and the 7-day I mice.</p

Delta of the slow- and fast-twitch fibers cross-sectional area of all the groups in both study cohorts.

<p>Mean values and standard deviation of delta of the variables fiber type I and type II cross sectional areas of the immobilization (top panel) and recovery (bottom panel) cohorts of mice. Definition of abbreviations: μm², square micrometers; I, immobilization; R, recovery. Statistical significance is represented as follows: **, p≤0.01, ***, p≤0.001, and n.s., non-significant differences in type I cross-sectional area between any of the immobilized animals and the non-immobilized controls; ¶¶, p≤0.01, ¶¶¶, p≤0.001, and n.s., non-significant differences in type II cross-sectional area between any of the immobilized animals and the non-immobilized controls; §§, p≤0.01, and n.s., non-significant differences in type I cross-sectional area between any of the R groups of animals and the 7-day I mice; #, p≤0.05, ##, p≤0.01, and n.s., non-significant differences in type II cross-sectional area between any of the R groups of animals and the 7-day I mice.</p

Delta of muscle fibers proportions of all the groups in both study cohorts.

<p>Mean values and standard deviation of delta of the variables type I and type II fibers proportions of the immobilization (top panel) and recovery (bottom panel) cohorts of mice. Definition of abbreviations: I, immobilization; R, recovery. Statistical significance is represented as follows: **, p≤0.01, and n.s., non-significant differences in type I fibers proportions between any of the immobilized animals and the non-immobilized controls; ¶¶, p≤0.01, and n.s., non-significant differences in type II fibers proportions between any of the immobilized animals and the non-immobilized controls; n.s., non-significant differences in either type I or type II fibers proportions between any of the R groups of animals and the 7-day I mice.</p

Activated Akt content of all the groups in both study cohorts.

<p>Mean values and standard deviation from the p-Akt/Akt ratio is depicted in the gastrocnemius of the immobilization (top panel) and recovery (bottom panel) cohorts of mice, as measured by optical densities in arbitrary units (OD, a.u.). Definition of abbreviations: Akt, RAC-alpha serine/threonine-protein kinase; p-Akt, phosphorylated-Akt; OD, optical densities; a.u., arbitrary units; I, immobilization; R, recovery. Statistical significance is represented as follows: n.s., non-significant differences between any of the immobilized animals and the non-immobilized controls; n.s., non-significant differences between any of the R groups of animals and the 7-day I mice. Note that as arbitrary units were used for the measurement of the optical densities in each set of immunoblots (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164951#sec006" target="_blank">methods</a>), scale bars in the ordinate axes differ in the graphs of the immobilization groups from those of the recovery cohorts.</p

Plasma Troponin-I levels in both study cohorts.

<p>Mean values and standard deviation of fast troponin I plasma levels (ng/ml) of the immobilization (top panel) and recovery (bottom panel) cohorts of mice. Definition of abbreviations: ng, nanogram; ml, milliliter; I, immobilization; R, recovery. Statistical significance is represented as follows: **, p≤0.01, ***, p≤0.001, and n.s., non-significant differences between any of the immobilized animals and the non-immobilized controls; §§, p≤0.01, and n.s., non-significant differences between any of the R groups of animals and the 7-day I mice.</p

Total protein ubiquitination content of all the groups in both study cohorts.

<p>Mean values and standard deviation of total ubiquitinated proteins in the gastrocnemius of the immobilization (top panel) and recovery (bottom panel) cohorts of mice, as measured by optical densities in arbitrary units (OD, a.u.). Definition of abbreviations: OD, optical densities; a.u., arbitrary units; I, immobilization; R, recovery. Statistical significance is represented as follows: *, p≤0.05, and n.s., non-significant differences between any of the immobilized animals and the non-immobilized controls; §, p≤0.05, §§§, p≤0.001, and n.s., non-significant differences between any of the R groups of animals and the 7-day I mice. Note that as arbitrary units were used for the measurement of the optical densities in each set of immunoblots (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164951#sec006" target="_blank">methods</a>), scale bars in the ordinate axes differ in the graphs of the immobilization groups from those of the recovery cohorts.</p

Delta of muscle structural abnormalities of all the groups of the recovery cohorts.

<p>Mean values and standard deviation of deltas of the variables abnormal fraction (top panel), internal nuclei (middle panel), and inflammatory cells (bottom panel) in the gastrocnemius of the recovery cohorts of rodents. Definition of abbreviations: I, immobilization; R, recovery. Statistical significance is represented as follows: §, p≤0.05, §§§, p≤0.001, and n.s., non-significant differences between any of the R groups of animals and the 7-day I mice.</p

Delta of gastrocnemius proteasome trypsin-like and chymotrypsin-like activities of all the groups in both study cohorts.

<p>Mean values and standard deviation of delta of the variables trypsin-like and chymotrypsin-like activities (nmol/mg/30’) in the gastrocnemius of the immobilization (top panel) and recovery (bottom panel) cohorts of mice. Definition of abbreviations: nmol, nanomol; mg, milligram; I, immobilization; R, recovery. Statistical significance is represented as follows: **, p≤0.01, ***, p≤0.001 and n.s., non-significant differences in trypsin-like activity between any of the immobilized animals and the non-immobilized controls; ¶¶¶, p≤0.001, and n.s., non-significant differences in chymotrypsin-like activity between any of the immobilized animals and the non-immobilized controls; §, p≤0.05, and n.s., non-significant differences in trypsin-like activity between any of the R groups of animals and the 7-day I mice; ##, p≤0.01, ###, p≤0.001, and n.s., non-significant differences in chymotrypsin-like activity between any of the R groups of animals and the 7-day I mice.</p

Activated p70S6K content of all the groups in both study cohorts.

<p>Mean values and standard deviation from the p-p70S6K/p70S6K ratio is depicted in the gastrocnemius of the immobilization (top panel) and recovery (bottom panel) cohorts of mice, as measured by optical densities in arbitrary units (OD, a.u.). Definition of abbreviations: p70S6K, p70 S6 kinase; p-70S6K, phosphorylated p70S6K; OD, optical densities; a.u., arbitrary units; I, immobilization; R, recovery. Statistical significance is represented as follows: *, p≤0.05, and n.s., non-significant differences between any of the immobilized animals and the non-immobilized controls; §, p≤0.05, §§, p≤0.01, and n.s., non-significant differences between any of the R groups of animals and the 7-day I mice. Note that as arbitrary units were used for the measurement of the optical densities in each set of immunoblots (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164951#sec006" target="_blank">methods</a>), scale bars in the ordinate axes differ in the graphs of the immobilization groups from those of the recovery cohorts.</p