The scientific exploration of saliva in the post-proteomic era: from database back to basic function

Abstract

The proteome of human saliva can be considered as being essentially completed. Diagnostic markers for a number of diseases have been identified among salivary proteins and peptides, taking advantage of saliva as an easy-to-obtain biological fluid. Yet, the majority of disease markers identified so far are serum components and not intrinsic proteins produced by the salivary glands. Furthermore, despite the fact that saliva is essential for protecting the oral integuments and dentition, little progress has been made in finding risk predictors in the salivary proteome for dental caries or periodontal disease. Since salivary proteins, and in particular the attached glycans, play an important role in interactions with the microbial world, the salivary glycoproteome and other post-translational modifications of salivary proteins need to be studied. Risk markers for microbial diseases, including dental caries, are likely to be discovered among the highly glycosylated major protein species in saliva. This review will attempt to raise new ideas and also point to under-researched areas that may hold promise for future applicability in oral diagnostics and prediction of oral disease.

Host Defense Proteins Derived from Human Saliva Bind to Staphylococcus aureus

“…aliva plays a key role in host defense against invading pathogens (1)(2)(3)(4). Among the more than 2,000 proteins and peptides found in saliva (5), many exhibit direct antimicrobial activity (6).…”

“…Thus, binding of salivary proteins to pathogens is thought to play an important role in preventing systemic infections. In hospitalized patients, the protective and antimicrobial functions of saliva, which play a crucial role in host defense against invading pathogens (1)(2)(3), are frequently impaired by reduction of salivary flow or lack of salivary secretion (9)(10)(11). Under such conditions of dry mouth and poor oral hygiene, the normal commensal oral microflora shifts to a community that harbors a higher number of pathogens (12,13).…”

“…The plates were incubated statically at 37°C for 21 h aerobically. Culture supernatants were decanted and nonadherent bacteria removed by rinsing with 5 ml of phosphate-buffered saline (PBS; 20 mM sodium phosphate, 150 mM NaCl, pH 7.2) containing 0.04% NaN 3 . For visualization, adherent biofilms were fixed with 100% ethanol and air dried prior to staining for 2 min with 5 ml of 0.4% (wt/vol) crystal violet (C-0775; Sigma, St. Louis, MO) in 12% ethanol.…”

The Use of Electrophoresis for the Study of Saliva Involvement in Ingestive Behavior

“…For a given quantity of quinine, subjects with lower levels of histatin 5 had therefore more free quinine which could interact with their taste receptors, thereby increasing their sensitivity. Another example of salivary protein -tastant interaction has been suggested by [31] based on the demonstration by 1 H-NMR that the PROP molecule could interact with the arginine and lysine amino-acids. This investigation followed a study where top-down analysis of saliva of supertasters vs nontasters of PROP revealed that saliva of supertasters had higher levels of basic proline-rich proteins (PRPs), in particular the Ps1 protein which contains a high proportion of arginine and lysine [9].…”

“…Whole saliva contains a wide variety of proteins and peptides, of glandular or blood origin, with diverse functions, namely proteins that participate in teeth and oral tissues protection, as well as proteins related to ingestive and digestive processes [1]. Several studies, in animals and humans, present evidences that saliva is involved in eating behaviour [e.g.…”