Evaluation of the Suitability of Dried Saliva Spots for In-Depth Proteome Analyses for Clinical Applications

Previously,
we performed nontargeted proteome analysis using dried blood spots
(DBSs) that are widely used in newborn screening for the clinical
diagnosis of congenital genetic diseases and immunodeficiency. We
have developed an efficient and simple pretreatment method for DBSs
that can detect more than 1000 proteins. To complement proteins that
are difficult to detect via DBS analysis with less invasive alternative
body fluids, we conducted this study to investigate the proteins detected
from dried saliva spots (DSSs) using single-shot LC–MS/MS,
which is practical in clinical settings. We also clarified whether
DSSs have the same advantages as DBSs, and we investigated the influence
of saliva collection conditions and the storage environment on their
protein profile. As a result, we detected approximately 5000 proteins
in DSSs and whole saliva, and we concluded that they were sufficient
to complement the proteins lacking in the blood analysis. DSSs could
be used as an alternative tool to DBSs for detecting the presence
of causative proteins.