Saliva Collection Methods Evaluated for Proteome Analysis

Subjects had to be free of fever, without a cold, and maintained good oral hygiene. Immediately, after saliva collection, a Proteinase Inhibitor Cocktail (Sigma Aldrich; St. Louis, MO, USA) was added and saliva collection by the three methods was performed on three consecutive days.

Stimulated Salivette Saliva was collected by Salivette with cotton swabs (Sarstedt; Nümbrecht, Germany). For the stimulated paraffin gum study, volunteers were asked to chew for one minute using commercially available paraffin gum (Ivoclar Vivadent; Schaan, Lichtenstein). Afterwards the fluid was collected in a 15 mL falcon tube. A 50 mL falcon tube was also used to collect for one minute the passive unstimulated drooled saliva from the volunteers. The protein lysates from the saliva samples were analyzed by shotgun liquid chromatography–mass spectrometry. The amount and concentration of the protein as well as protein profiling data of whole saliva were comparatively analyzed.

Samples collected using paraffin gum showed the highest saliva volume at 4.1 ± 1.5 mL, followed by Salivette collection at 1.8 ± 0.4 mL and drooling at 1.0 ± 0.4 mL. Saliva protein concentrations with a mean of 1,145 μg/mL showed no significant differences between the three sampling schemes. Each collection approach facilitated the identification of about 160 proteins with more than two distinct peptides per subject, but collection-method dependent variations in protein composition were observed.

The authors concluded that the three collection methods allows similar coverage of the whole saliva proteome, but the specific proteins observed depended on the collection approach. Therefore, only one type of collection device should be used for quantitative proteome analysis, especially when performing large-scale cross-sectional or multicentric studies. The study was published on April 18, 2013, in the journal Clinica Chimica Acta.

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