Allergy Asthma Immunol Res.  2020 Jul;12(4):684-700. 10.4168/aair.2020.12.4.684.

Activation of Transient Receptor Potential Melastatin Family Member 8 (TRPM8) Receptors Induces Proinflammatory Cytokine Expressions in Bronchial Epithelial Cells

Affiliations
  • 1Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Lung Research Institute of Hallym University College of Medicine, Anyang, Korea
  • 2Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, Korea
  • 3Division of Allergy and Respiratory Disease, Department of Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea

Abstract

Purpose
Cold air is a major environmental factor that exacerbates asthma. Transient receptor potential melastatin family member 8 (TRPM8) is a cold-sensing channel expressed in the airway epithelium. However, its role in airway inflammation remains unknown. We investigated the role of TRPM8 in innate immune responses in bronchial epithelial cells and asthmatic subjects.
Methods
The TRPM8 mRNA and protein expression on BEAS2B human bronchial epithelial cells was examined by real-time polymerase chain reaction (PCR), immunofluorescence staining and western blotting. Additionally, interleukin (IL)-4, IL-6, IL-8, IL-13, IL-25 and thymic stromal lymphopoietin (TSLP) levels before and after menthol, dexamethasone and N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl) piperazine-1-carboxamide (BCTC) treatments were measured via real-time PCR. TRPM8 protein levels in the supernatants of induced sputum from asthmatic subjects and normal control subjects were measured using enzyme-linked immunosorbent assay, and mRNA levels in sputum cell lysates were measured using real-time PCR.
Results
Treatment with up to 2 mM menthol dose-dependently increased TRPM8 mRNA and protein in BEAS2B cells compared to untreated cells (P < 0.001) and concomitantly increased IL-25 and TSLP mRNA (P < 0.05), but not IL-33 mRNA. BCTC (10 μM) significantly abolished menthol-induced up-regulation of TRPM8 mRNA and protein and IL-25 and TSLP mRNA (P < 0.01). TRPM8 protein levels were higher in the supernatants of induced sputum from asthmatic subjects (n = 107) than in those from healthy controls (n = 19) (P < 0.001), and IL-25, TSLP and IL-33 mRNA levels were concomitantly increased (P < 0.001). Additionally, TRPM8 mRNA levels correlated strongly with those of IL-25 and TSLP (P < 0.001), and TRPM8 protein levels were significantly higher in bronchodilator-responsive asthmatic subjects than in nonresponders.
Conclusions
TRPM8 may be involved in the airway epithelial cell innate immune response and a molecular target for the treatment of asthma.

Keyword

Asthma; transient receptor potential channels; epithelium; interleukin-25; thymic stromal lymphopoietin
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