Laurel Doghramji

T2R38 taste receptor polymorphisms underlie susceptibility to upper respiratory infection

Innate and adaptive defense mechanisms protect the respiratory system from attack by microbes. Here, we present evidence that the bitter taste receptor T2R38 regulates the mucosal innate defense of the human upper airway. Utilizing immunofluorescent and live cell imaging techniques in polarized primary human sinonasal cells, we demonstrate that T2R38 is expressed in human upper respiratory epithelium and is activated in response to acyl-homoserine lactone quorum-sensing molecules secreted by Pseudomonas aeruginosa and other gram-negative bacteria. Receptor activation regulates calcium-dependent NO production, resulting in stimulation of mucociliary clearance and direct antibacterial effects. Moreover, common polymorphisms of the TAS2R38 gene were linked to significant differences in the ability of upper respiratory cells to clear and kill bacteria. Lastly, TAS2R38 genotype correlated with human sinonasal gram-negative bacterial infection. These data suggest that T2R38 is an upper airway sentinel in innate defense and that genetic variation contributes to individual differences in susceptibility to respiratory infection.

Bitter and sweet taste receptors regulate human upper respiratory innate immunity

Bitter taste receptors (T2Rs) in the human airway detect harmful compounds, including secreted bacterial products. Here, using human primary sinonasal air-liquid interface cultures and tissue explants, we determined that activation of a subset of airway T2Rs expressed in nasal solitary chemosensory cells activates a calcium wave that propagates through gap junctions to the surrounding respiratory epithelial cells. The T2R-dependent calcium wave stimulated robust secretion of antimicrobial peptides into the mucus that was capable of killing a variety of respiratory pathogens. Furthermore, sweet taste receptor (T1R2/3) activation suppressed T2R-mediated antimicrobial peptide secretion, suggesting that T1R2/3-mediated inhibition of T2Rs prevents full antimicrobial peptide release during times of relative health. In contrast, during acute bacterial infection, T1R2/3 is likely deactivated in response to bacterial consumption of airway surface liquid glucose, alleviating T2R inhibition and resulting in antimicrobial peptide secretion. We found that patients with chronic rhinosinusitis have elevated glucose concentrations in their nasal secretions, and other reports have shown that patients with hyperglycemia likewise have elevated nasal glucose levels. These data suggest that increased glucose in respiratory secretions in pathologic states, such as chronic rhinosinusitis or hyperglycemia, promotes tonic activation of T1R2/3 and suppresses T2R-mediated innate defense. Furthermore, targeting T1R2/3-dependent suppression of T2Rs may have therapeutic potential for upper respiratory tract infections.

Baby shampoo nasal irrigations for the symptomatic post-functional endoscopic sinus surgery patient.

Background Symptoms of postnasal drainage and thickened mucus are commonly seen in patients with chronic rhinosinusitis (CRS) recalcitrant to sinus surgery and conventional medical therapies. Chemical surfactants can act as a mucolytic by reducing water surface tension and have the potential to serve as an antimicrobial agent. Baby shampoo is an inexpensive, commercially available solution containing multiple chemical surfactants. This is an in vitro study of its antimicrobial effects on Pseudomonas biofilms with translation to a clinical study for use as an adjuvant nasal wash in patients with CRS who remain symptomatic despite adequate sinus surgery and conventional medical therapies. Methods In vitro testing was performed to determine the optimal concentration of baby shampoo that disrupted preformed bacterial biofilms and inhibited biofilm formation. This concentration was then used in a prospective study of symptomatic post–functional endoscopic sinus surgery (FESS) patients who irrigated twice a day for 4 weeks. Validated outcome forms and objective smell testing was performed before and after therapy. Results One percent baby shampoo in normal saline was the optimal concentration for inhibition of Pseudomonas biofilm formation. Baby shampoo had no effect on the eradication of preformed Pseudomonas biofilms. Eighteen patients with CRS with an average of 2.8 surgeries were studied after irrigating with 1% baby shampoo solution. Two patients discontinued use because of minor nasal and skin irritations; 46.6% of patients experienced an overall improvement in their subjective symptoms, and 60% of patients noted improvement in specific symptoms of thickened mucus and postnasal drainage. Conclusion Baby shampoo nasal irrigation has promise as an inexpensive, tolerable adjuvant to conventional medical therapies for symptomatic patients after FESS. Its greatest benefit may be in improving symptoms of thickened nasal discharge and postnasal drainage.

The bitter taste receptor T2R38 is an independent risk factor for chronic rhinosinusitis requiring sinus surgery

The bitter taste receptor T2R38 was recently described to play a role in upper airway innate mucosal defense. When activated by bacterial quorum‐sensing molecules, T2R38 stimulates the ciliated epithelial cells to produce nitric oxide (NO), resulting in bactericidal activity and an increase in mucociliary clearance (MCC). Polymorphisms within the T2R38 gene (TAS2R38) confer variability in activation of the receptor yielding dramatic differences in upper airway defensive responses (NO production and accelerated MCC) to microbial stimulation based on genotype. Our objective was to determine whether the nonprotective TAS2R38 polymorphisms, which render the receptor inactive, correlate with medically recalcitrant chronic rhinosinusitis (CRS) necessitating surgical intervention in the context of known risk factors, and thus identify whether the TAS2R38 genotype is an independent risk factor for patients undergoing functional endoscopic sinus surgery (FESS).

Genetics of the taste receptor T2R38 correlates with chronic rhinosinusitis necessitating surgical intervention

We recently demonstrated the bitter taste receptor T2R38 upregulates sinonasal mucosal innate defense in response to gram‐negative quorum‐sensing molecules through increased nitric oxide production and mucociliary clearance. T2R38 was initially identified in the quest to understand the variability in bitter taste perception to the compound phenylthiocarbamide (PTC) and demonstrated to have polymorphisms generating diplotypes dividing people into PTC supertasters, heterozygotes (with variable PTC detection), and nontasters. We have further demonstrated that sinonasal epithelial cultures derived from supertasters significantly increase innate defenses in response to gram‐negative quorum‐sensing molecules compared with sinonasal cultures derived from heterozygotes and nontaster individuals. Based on this data, we hypothesize that supertasters are less likely to require sinus surgery compared with heterozygous or nontasters and that supertasters have improved surgical outcomes.

Tobacco smoke mediated induction of sinonasal microbial biofilms.

Cigarette smokers and those exposed to second hand smoke are more susceptible to life threatening infection than non-smokers. While much is known about the devastating effect tobacco exposure has on the human body, less is known about the effect of tobacco smoke on the commensal and commonly found pathogenic bacteria of the human respiratory tract, or human respiratory tract microbiome. Chronic rhinosinusitis (CRS) is a common medical complaint, affecting 16% of the US population with an estimated aggregated cost of

Biofilms correlate with TH1 inflammation in the sinonasal tissue of patients with chronic rhinosinusitis

6 billion annually. Epidemiologic studies demonstrate a correlation between tobacco smoke exposure and rhinosinusitis. Although a common cause of CRS has not been defined, bacterial presence within the nasal and paranasal sinuses is assumed to be contributory. Here we demonstrate that repetitive tobacco smoke exposure induces biofilm formation in a diverse set of bacteria isolated from the sinonasal cavities of patients with CRS. Additionally, bacteria isolated from patients with tobacco smoke exposure demonstrate robust in vitro biofilm formation when challenged with tobacco smoke compared to those isolated from smoke naïve patients. Lastly, bacteria from smoke exposed patients can revert to a non-biofilm phenotype when grown in the absence of tobacco smoke. These observations support the hypothesis that tobacco exposure induces sinonasal biofilm formation, thereby contributing to the conversion of a transient and medically treatable infection to a persistent and therapeutically recalcitrant condition.

Vasoactive intestinal peptide regulates sinonasal mucociliary clearance and synergizes with histamine in stimulating sinonasal fluid secretion

OBJECTIVE: Determine the prevalence of bacterial biofilms in surgical chronic rhinosinusitis (CRS) patients and characterize the inflammatory response associated with biofilm CRS. STUDY DESIGN: Cross-sectional. SETTING: Tertiary care academic center. SUBJECTS AND METHODS: Sinonasal mucosa and peripheral blood were collected from 60 CRS patients. Mucosal biofilms were demonstrated by scanning electron microscopy. Leukocyte subpopulations were determined by flow cytometry. Cytokines were identified with a luminex-based assay on the lysate of homogenized tissue or plasma. RESULTS: Of the 60 samples, 17 were determined to be positive for the presence of biofilms. Oral steroid-naive CRS patients with biofilm demonstrated a local TH1 inflammatory response with significantly elevated levels of interferon-γ (INF-γ), granulocyte colony-stimulating factor, macrophage inflammatory protein-1 β, and neutrophils in the sinonasal mucosa. No differences were present at the systemic level. CONCLUSION: Sinonasal bacterial biofilms correlate to a TH1 skewed local but not systemic inflammatory response in CRS. This difference is abrogated by the use of oral steroids.

TAS2R38 genotype predicts surgical outcome in nonpolypoid chronic rhinosinusitis.

Mucociliary clearance (MCC) is the primary physical airway defense against inhaled pathogens and particulates. MCC depends on both proper fluid/mucus homeostasis and epithelial ciliary beating. Vasoactive intestinal peptide (VIP) is a neurotransmitter expressed in the sinonasal epithelium that is up‐regulated in allergy. However, the effects of VIP on human sinonasal physiology are unknown, as are VIPs interactions with histamine, a major regulator of allergic disease. We imaged ciliary beat frequency, mucociliary transport, apical Cl‐ permeability, and airway surface liquid (ASL) height in primary human sinonasal air‐liquid‐interface cultures to investigate the effects of VIP and histamine. VIP stimulated an increase in ciliary beat frequency (EC50 0.5 μM; maximal increase ~40% compared with control) and cystic fibrosis transmembrane conductance regulator (CFTR)‐dependent and Na+K+2Cl‐ cotransporter‐dependent fluid secretion, all requiring cAMP/PKA signaling. Histamine activated Ca2+ signaling that increased ASL height but not ciliary beating. Low concentrations of VIP and histamine had synergistic effects on CFTR‐dependent fluid secretion, revealed by increased ASL heights. An up‐regulation of VIP in histamine‐driven allergic rhinitis would likely enhance mucosal fluid secretion and contribute to allergic rhinorrhea. Conversely, a loss of VIP‐activated secretion in patients with CF may impair mucociliary transport, contributing to increased incidences of sinonasal infections and rhinosinusitis.—Lee, R. J., Chen, B., Doghramji, L., Adappa, N. D., Palmer, J. N., Kennedy, D. W., Cohen, N. A., Vasoactive intestinal peptide regulates sinonasal mucociliary clearance and synergizes with histamine in stimulating sinonasal fluid secretion. FASEB J. 27, 5094–5103 (2013). www.fasebj.org

The effect of diabetes mellitus on chronic rhinosinusitis and sinus surgery outcome.

Over 550,000 sinus surgeries are performed annually in the United States on patients with chronic rhinosinusitis (CRS). Although the results of sinus surgery vary widely, no known genetic factor has been identified to predict surgical outcomes. The bitter taste receptor T2R38 has recently been demonstrated to regulate upper airway innate defense and may affect patient responses to therapy. Our goal was to determine whether TAS2R38 genetics predicts outcomes in CRS patients following sinus surgery.