title: Soluble forms of Toll-like receptor 4 are present in human saliva and modulate tumour necrosis factor-alpha secretion by macrophage-like cells.
abstract: In health, mucosal inflammation is prevented by tightly regulated responses via Toll-like receptors (TLR) that interact with specific microbe associated molecular patterns. Currently, 13 TLRs have been identified. Based on the specificity of ligand recognition, TLR-2 and TLR-4 can recognize most oral commensal microorganisms. Recent identification of some soluble TLRs (sTLRs) suggests additional regulatory roles for these receptors. We report here the presence of sTLR-4 polypeptides in adult human saliva. Functionally, the salivary sTLR-4 suppressed cytokine secretion by activated macrophages. The sTLR-4 levels were elevated significantly in oral lichen planus (OLP), a chronic inflammatory condition of the oral mucosa characterized by clinical persistence. In contrast, the epithelial cells in the saliva of OLP subjects expressed significantly reduced TLR-2 and TLR-4 mRNA that correlated with fewer bacteria/salivary epithelial cells. Investigating the soluble and cellular components of saliva is useful in identifying potential biomarkers for oral mucosal lesions.
authors.affiliation: Department of Oral Pathology, Medicine and Radiology, School of Dentistry, Indiana University Purdue University, Indianapolis, IN 46202, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Zunt
authors.forename: L V
authors.initials: LV
authors.lastname: Burton
authors.forename: L I
authors.initials: LI
authors.lastname: Goldblatt
authors.forename: E E
authors.initials: EE
authors.lastname: Dobbins
authors.forename: M
authors.initials: M
authors.lastname: Srinivasan
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D004269:DNA, Bacterial / Q000032:analysis; D004847:Epithelial Cells / Q000737:chemistry* / Q000382:microbiology; D006801:Humans; D017676:Lichen Planus, Oral / Q000378:metabolism*; D018950:Lipopolysaccharide Receptors / Q000032:analysis / Q000235:genetics; D008264:Macrophages / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000032:analysis; D012463:Saliva / Q000737:chemistry*; D051195:Toll-Like Receptor 2 / Q000032:analysis / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000032:analysis* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D018950:Lipopolysaccharide Receptors; D012333:RNA, Messenger; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha