Salivary proteins in relation to oral diseases

Abstract

Saliva represents an early, principal defense system against infections affecting the oral cavity, including periodontal disease and dental caries. The isolation and characterization of human salivary proteins have led to the identification of responsible beneficial protective effects of these proteins towards oral diseases. Secreted exclusively by salivary glands, histatins and acidic proline-rich proteins (PRPs) are two protein families which demonstrate many important functions pertinent to the maintenance of a healthy oral cavity. Histatins are small salivary proteins which display multiple interactions with bacteria which have been associated to periodontal inflammation. These activities range from direct killing, growth inhibition to neutralization of virulence factors. Acidic PRPs, are a group of salivary proteins which adhere to the tooth surfaces and contribute to the formation of the acquired enamel pellicle. They exert various functional roles in saliva such as inhibiting crystal growth in a salivary environment which is supersaturated with respect to calcium phosphate salts. Acidic PRPs, as well as other pellicle phosphoproteins, retard calcium phosphate exchanges between saliva and HA, which will in turn diminish the calcium phosphate dissolution occurring during the carious process. While many studies have looked at the properties of histatins and PRPs in their intact forms, few have analyzed their structural stability in the oral environment. Once glandular secretions are released into the oral cavity, their proteins are exposed to a whole mixture of enzymes derived from bacteria, epithelial cells and other host cells. Therefore, WS proteolysis has to be considered when analyzing the functional activity of histatins and acidic PRPs in the oral cavity. The aim of this study is to gain insight into the endogenous histatin and PRP concentrations and structural stability in parotid secretion (PS), whole saliva (WS) and whole saliva supernatant (WSS). [TRUNCATED]