title: Constitutive expression of a bacterial pattern recognition receptor, CD14, in human salivary glands and secretion as a soluble form in saliva.
abstract: Saliva contains a number of proteins and glycoproteins that protect oral tissues, but little is known about the role of human saliva in innate immunity. Here we showed that human major salivary gland cells constitutively expressed a bacterial pattern recognition receptor, CD14, by immunohistochemistry. Human salivary gland cells in culture express CD14 mRNA and a 55-kDa CD14 protein in, but not on the cells, and secrete a soluble form with the same molecular mass. Human whole saliva contains a 55-kDa CD14, and the concentration of parotid saliva was 10-fold higher than whole saliva, which is comparable to that of serum CD14. Levels of CD14 in unstimulated whole and parotid saliva were unchanged before and after a meal and between unstimulated and stimulated saliva, indicating that saliva CD14 is constitutively secreted into the oral cavity. In contrast, lipopolysaccharide (LPS)-binding protein was below the detectable level. The saliva CD14 is functionally active in that it mediated the activation of CD14-lacking intestinal epithelial cells by LPS in a Toll-like receptor 4-dependent manner. These results suggested that saliva CD14 is important for the maintenance of oral health and possibly intestinal homeostasis.
authors.affiliation: Department of Microbiology and Immunology, Tohoku University School of Dentistry, Sendai 980-8575, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Uehara
authors.forename: Shunji
authors.initials: S
authors.lastname: Sugawara
authors.forename: Kouichi
authors.initials: K
authors.lastname: Watanabe
authors.forename: Seishi
authors.initials: S
authors.lastname: Echigo
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Sato
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Takada
mesh_terms: D004847:Epithelial Cells / Q000166:cytology; D006706:Homeostasis / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D007422:Intestines / Q000276:immunology; D018950:Lipopolysaccharide Receptors / Q000032:analysis* / Q000276:immunology*; D009909:Oral Health; D010306:Parotid Gland / Q000166:cytology; D012463:Saliva / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D012995:Solubility; D013363:Submandibular Gland / Q000166:cytology; D014407:Tumor Cells, Cultured
chemical_list: D018950:Lipopolysaccharide Receptors