title: MD2 expression is reduced in large airways of smokers and COPD smokers.
abstract: Toll-like receptor 4 (TLR4) signaling requires a number of accessory proteins to initiate a signal. MD-2 is one of the accessory proteins with a relevant role in lipopolysaccharide responses. Although cigarette smoke increases TLR4 expression, TLR4 signaling is altered in smokers and in smokers COPD patients. The main aims of this study were to explore whether MD2 is altered in large and small airways of COPD and of smokers without COPD. The expression of MD2 ex vivo was assessed by immunohistochemistry in surgical specimens from current smokers COPD (s-COPD; n = 14), smokers without COPD (S; n = 7), and from non-smoker non-COPD subjects (C; n = 11. The in vitro effects of cigarette smoke extracts on the MD2 expression in a human bronchial epithelial cell line (16-HBE) were also assessed by flow cytometry. MD2 is reduced in the epithelium and in the submucosa in large airways but not in the epithelium and in the submucosa in small airways of smokers and of s-COPD. The expression of MD2 in the submucosa of the large airways is significantly higher in comparison to the submucosa of the small airways in all the studied groups. In vitro, cigarette smoke is able to increase TLR4 but it reduces MD2 in a dose-dependent manner in bronchial epithelial cells. Cigarette smoke may alter innate immune responses reducing the expression of the MD2, a molecule with an important role in TLR4 signaling.
authors.affiliation: Institute of Biomedicine and Molecular Immunology (IBIM), National Research Council (CNR), Via Ugo La Malfa, 153, 90146, Palermo, Italy, pace@ibim.cnr.it.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Pace
authors.forename: Maria
authors.initials: M
authors.lastname: Ferraro
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Chiappara
authors.forename: Patrizio
authors.initials: P
authors.lastname: Vitulo
authors.forename: Loredana
authors.initials: L
authors.lastname: Pipitone
authors.forename: Serena
authors.initials: S
authors.lastname: Di Vincenzo
authors.forename: Mark
authors.initials: M
authors.lastname: Gjomarkaj
mesh_terms: D000368:Aged; D001980:Bronchi / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007113:Immunity, Innate; D051218:Lymphocyte Antigen 96 / Q000378:metabolism*; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000473:pathology; D012907:Smoking / Q000009:adverse effects / Q000378:metabolism* / Q000473:pathology; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C495377:LY96 protein, human; D051218:Lymphocyte Antigen 96; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4