title: Solitary chemosensory cells and bitter taste receptor signaling in human sinonasal mucosa.
abstract: BACKGROUND
  Solitary chemosensory cells (SCCs) are specialized cells in the respiratory epithelium that respond to noxious chemicals including bacterial signaling molecules. SCCs express components of bitter taste transduction including the taste receptor type 2 (TAS2R) bitter taste receptors and downstream signaling effectors: α-Gustducin, phospholipase Cβ2 (PLCβ2), and transient receptor potential cation channel subfamily M member 5 (TRPM5). When activated, SCCs evoke neurogenic reflexes, resulting in local inflammation. The purpose of this study was to test for the presence SCCs in human sinonasal epithelium, and to test for a correlation with inflammatory disease processes such as allergic rhinitis and chronic rhinosinusitis.
  
  
  METHODS
  Patient demographics and biopsies of human sinonasal mucosa were obtained from control patients (n = 7) and those with allergic rhinitis and/or chronic rhinosinusitis (n = 15). Reverse transcription polymerase chain reaction (RT-PCR), quantitative PCR (qPCR), and immunohistochemistry were used to determine whether expression of signaling effectors was altered in diseased patients.
  
  
  RESULTS
  RT-PCR demonstrated that bitter taste receptors TAS2R4, TAS2R14, and TAS2R46, and downstream signaling effectors α-Gustducin, PLCβ2, and TRPM5 are expressed in the inferior turbinate, middle turbinate, septum, and uncinate of both control and diseased patients. PLCβ2/TRPM5-immunoreactive SCCs were identified in the sinonasal mucosa of both control and diseased patients. qPCR showed similar expression of α-Gustducin and TRPM5 in the uncinate process of control and diseased groups, and there was no correlation between level of expression and 22-item Sino-Nasal Outcomes Test (SNOT-22) or pain scores.
  
  
  CONCLUSIONS
  SCCs are present in human sinonasal mucosa in functionally relevant areas. Expression level of signaling effectors was similar in control and diseased patients and did not correlate with measures of pain and inflammation. Further study into these pathways may provide insight into nasal inflammatory diseases and may offer potential therapeutic targets.
authors: Department of Otolaryngology-Head and Neck Surgery, University of Colorado Denver, Aurora, CO 80045, USA.
authors: Henry P
authors: HP
authors: Barham
authors: Sarah E
authors: SE
authors: Cooper
authors: Catherine B
authors: CB
authors: Anderson
authors: Marco
authors: M
authors: Tizzano
authors: Todd T
authors: TT
authors: Kingdom
authors: Tom E
authors: TE
authors: Finger
authors: Sue C
authors: SC
authors: Kinnamon
authors: Vijay R
authors: VR
authors: Ramakrishnan
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002628:Chemoreceptor Cells / Q000378:metabolism*; D002908:Chronic Disease; D004848:Epithelium / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000378:metabolism*; D010146:Pain; D054799:Phospholipase C beta / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D012220:Rhinitis / Q000378:metabolism*; D065631:Rhinitis, Allergic; D012221:Rhinitis, Allergic, Perennial / Q000378:metabolism; D012852:Sinusitis / Q000378:metabolism*; D050053:TRPM Cation Channels / Q000378:metabolism*; D015293:Transducin / Q000378:metabolism; D000098706:Taste Receptors, Type 2
chemical_list: D043562:Receptors, G-Protein-Coupled; D050053:TRPM Cation Channels; C404409:TRPM5 protein, human; D000098706:Taste Receptors, Type 2; C075192:gustducin; D054799:Phospholipase C beta; D015293:Transducin
references: Otolaryngol Clin North Am. 2005 Dec;38(6):1311-25, x-xi
references: 16326187
references: Otolaryngol Head Neck Surg. 1995 Jul;113(1):104-9
references: 7603703
references: Allergy. 2010 Sep;65(9):1149-57
references: 20192943
references: Am J Rhinol. 2003 Jan-Feb;17(1):27-32
references: 12693653
references: Science. 2009 Aug 28;325(5944):1131-4
references: 19628819
references: Rhinology. 2011 Dec;49(5):507-12
references: 22125779
references: BMC Pulm Med. 2011 Jan 13;11:3
references: 21232137
references: J Neurophysiol. 2008 Jun;99(6):2929-37
references: 18417634
references: Rhinol Suppl. 2007;20:1-136
references: 17844873
references: J Aerosol Med. 2006 Fall;19(3):301-13
references: 17034306
references: J Biomech Eng. 1995 Nov;117(4):429-41
references: 8748525
references: J Neurosci. 2007 May 23;27(21):5777-86
references: 17522321
references: Eur Arch Otorhinolaryngol. 2009 Aug;266(8):1249-56
references: 19125268
references: Proc Natl Acad Sci U S A. 2003 Jul 22;100(15):8981-6
references: 12857948
references: Proc Natl Acad Sci U S A. 2011 Jun 7;108(23):9478-83
references: 21606356
references: Otolaryngol Head Neck Surg. 2003 Sep;129(3 Suppl):S1-32
references: 12958561
references: J Biomed Inform. 2009 Apr;42(2):377-81
references: 18929686
references: BMC Neurosci. 2010 Jun 21;11:77
references: 20565975
references: Ann Otol Rhinol Laryngol Suppl. 1995 Oct;167:17-21
references: 7574265
references: F1000 Biol Rep. 2011;3:20
references: 21941599
references: Rhinology. 1993 Dec;31(4):183-4
references: 8140385
references: Acta Physiol (Oxf). 2012 Feb;204(2):158-68
references: 21481196
references: J Anat. 2006 Sep;209(3):333-7
references: 16928202
references: J Allergy Clin Immunol. 2004 Dec;114(6 Suppl):155-212
references: 15577865
references: PLoS One. 2010 Jul 30;5(7):e11924
references: 20689832
references: Rhinology. 1999 Jun;37(2):50-5
references: 10416248
references: J Clin Invest. 2012 Nov;122(11):4145-59
references: 23041624
references: Proc Natl Acad Sci U S A. 2010 Feb 16;107(7):3210-5
references: 20133764
references: Chem Senses. 2004 Jun;29(5):365-79
references: 15201204
references: J Allergy Clin Immunol. 1994 Dec;94(6 Pt 1):1006-16
references: 7528231
references: Chem Senses. 2011 Sep;36(7):601-12
references: 21471186
references: Int Forum Allergy Rhinol. 2011 Jan-Feb;1(1):3-12
references: 22287302