title: Characterising the mechanism of airway smooth muscle β2 adrenoceptor desensitization by rhinovirus infected bronchial epithelial cells.
abstract: Rhinovirus (RV) infections account for approximately two thirds of all virus-induced asthma exacerbations and often result in an impaired response to β2 agonist therapy. Using an in vitro model of RV infection, we investigated the mechanisms underlying RV-induced β2 adrenoceptor desensitization in primary human airway smooth muscle cells (ASMC). RV infection of primary human bronchial epithelial cells (HBEC) for 24 hours produced conditioned medium that caused β2 adrenoceptor desensitization on ASMCs without an effect on ASMCs viability. Less than 3 kDa size fractionation together with trypsin digestion of RV-induced conditioned medium did not prevent β2 adrenoceptor desensitization, suggesting it could potentially be mediated by a small peptide or lipid. RV infection of BECs, ASMCs and fibroblasts produced prostaglandins, of which PGE2, PGF2α and PGI2 had the ability to cause β2 adrenoceptor desensitization on ASMCs. RV-induced conditioned medium from HBECs depleted of PGE2 did not prevent ASMC β2 adrenoceptor desensitization; however this medium induced PGE2 from ASMCs, suggesting that autocrine prostaglandin production may be responsible. Using inhibitors of cyclooxygenase and prostaglandin receptor antagonists, we found that β2 adrenoceptor desensitization was mediated through ASMC derived COX-2 induced prostaglandins. Since ASMC prostaglandin production is unlikely to be caused by RV-induced epithelial derived proteins or lipids we next investigated activation of toll-like receptors (TLR) by viral RNA. The combination of TLR agonists poly I:C and imiquimod induced PGE2 and β2 adrenoceptor desensitization on ASMC as did the RNA extracted from RV-induced conditioned medium. Viral RNA but not epithelial RNA caused β2 adrenoceptor desensitization confirming that viral RNA and not endogenous human RNA was responsible. It was deduced that the mechanism by which β2 adrenoceptor desensitization occurs was by pattern recognition receptor activation of COX-2 induced prostaglandins.
authors: Woolcock Institute of Medical Research, Sydney, Australia. dvan7422@gmail.com
authors: David
authors: D
authors: Van Ly
authors: Alen
authors: A
authors: Faiz
authors: Christine
authors: C
authors: Jenkins
authors: Ben
authors: B
authors: Crossett
authors: Judith L
authors: JL
authors: Black
authors: Brent
authors: B
authors: McParland
authors: Janette K
authors: JK
authors: Burgess
authors: Brian G G
authors: BG
authors: Oliver
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001980:Bronchi / Q000166:cytology / Q000276:immunology / Q000821:virology*; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000032:analysis; D004847:Epithelial Cells / Q000276:immunology / Q000821:virology*; D005260:Female; D054884:Host-Pathogen Interactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000276:immunology / Q000821:virology*; D010850:Picornaviridae Infections / Q000276:immunology* / Q000821:virology; D011453:Prostaglandins / Q000276:immunology; D012313:RNA / Q000032:analysis; D018343:Receptors, Adrenergic, beta-2 / Q000276:immunology*; D011982:Receptors, Prostaglandin / Q000037:antagonists & inhibitors; D012229:Rhinovirus / Q000502:physiology*; D051193:Toll-Like Receptors / Q000819:agonists / Q000276:immunology; D055815:Young Adult
chemical_list: D017077:Culture Media, Conditioned; D011453:Prostaglandins; D018343:Receptors, Adrenergic, beta-2; D011982:Receptors, Prostaglandin; D051193:Toll-Like Receptors; D012313:RNA