Is GRP78/BiP a potential salivary biomarker in patients with rheumatoid arthritis?
OBJECTIVE
In the last few years, serum and joint synovial fluid have been extensively analyzed for the proteomic research of rheumatoid arthritis (RA) biomarkers. Nonetheless, to date, there have been no studies investigating salivary biomarkers in this condition. Therefore, aim of this study is to investigate the presence of potential biomarkers of RA in human whole saliva.


METHODS
We combined 2-DE and MS to analyze the whole saliva protein profile of 20 RA patients in comparison with 20 sex- and age-matched healthy subjects.


RESULTS
Eight salivary proteins resulted differentially expressed, namely calgranulin A, calgranulin B, apolipoprotein A-1, 6-phosphogluconate dehydrogenase, peroxiredoxin 5, epidermal fatty acid-binding protein, 78 kDa glucose-regulated protein precursor (GRP78/BiP), and 14-3-3 proteins. It is particularly interesting that chaperone GRP78/BiP showed the greatest increase in RA patients. This finding was validated by Western Blot analysis and the over-expression of GRP78/BiP appear to be distinctive of RA and drugs treatment independent.


CONCLUSIONS
This study provides a rationale for further studies aimed at evaluating any correlation between GRP78/BiP and different clinical/serological aspects of the disease in order to improve the diagnostic algorithms of RA.
Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy.
Laura
L
Giusti
Chiara
C
Baldini
Federica
F
Ciregia
Gino
G
Giannaccini
Camillo
C
Giacomelli
Francesca
F
De Feo
Andrea
A
Delle Sedie
Lucrezia
L
Riente
Antonio
A
Lucacchini
Laura
L
Bazzichi
Stefano
S
Bombardieri
D001172:Arthritis, Rheumatoid / Q000097:blood / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D040901:Proteomics; D015203:Reproducibility of Results; D012463:Saliva / Q000378:metabolism*; D012471:Salivary Proteins and Peptides / Q000378:metabolism; D012698:Serologic Tests
D015415:Biomarkers; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D012471:Salivary Proteins and Peptides