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Scientists from the University of California, Los Angeles (UCLA) and University Medical Center Groningen, The Netherlands, have identified the first panel of candidate salivary proteins, peptides, and messenger RNA (mRNA) for the detection of primary Sjogren's syndrome (pSS). Their study, published in the November 2007 Arthritis & Rheumatism,1 is described as the first “discovery of candidate salivary mRNA markers for [pSS] detection.” The research, though still preliminary, is a promising development for the field of salivary diagnostics and ongoing initiatives to identify potential salivary biomarkers for detecting Sjogren’s syndrome, oral cancer, and other autoimmune diseases.

In the UCLA-UMC Groningen study, scientists aimed to characterize a panel of protein and mRNA biomarkers in whole saliva samples for potential use in pSS detection. Saliva samples were collected from 10 pSS patients and 10 healthy (control) subjects, and processed using mass spectrometry and microarray profiling to measure differences in the molecular profiles of the two patient groups.

After proteomic analysis and independent validation of salivary components, the authors found 27 significantly up-regulated mRNAs in samples taken from pSS patients. Also, 19 of the 27 over-expressed gene transcripts were known products of an immune response to pSS pathogenesis. They also identified a distinct set of over 40 salivary proteins and 16 whole saliva peptides that were at significantly different levels in samples taken from pSS patients than those from the healthy volunteers. According to the authors, the difference in protein levels reflected the damage of glandular cells and activated immune response in the oral cavities of the pSS patients.

Sjogren’s syndrome is a progressive autoimmune condition of the exocrine glands that impairs secretory function in the salivary and lacrimal (tear) glands, producing dryness of the eyes and mouth (xerostomia) as common symptoms. Nearly two million people in the United States have pSS, and at least another million individuals have the secondary form Sjogren’s syndrome, which occurs in the presence of another autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. Sjogren’s syndrome is most commonly found among peri- or postmenopausal women (about 90 percent of all cases). Sjogren’s patients have also been found to be at increased risk of developing lymphoma. The condition has a complex pathogenesis, and is often undertreated and underdiagnosed. The difficulty of diagnosing Sjogren’s syndrome in its earliest stages underscores the importance of validating candidate salivary biomarkers that could eventually be used in diagnostic applications for pSS detection. 

The newly published study was led by Dr. David Wong, professor at the UCLA School of Dentistry and member of the ADA Council on Scientific Affairs, with funding support provided by the National Institutes of Health. Having identified a panel of proteomic and genomic salivary biomarkers that can differentiate pSS patients from control subjects, the UCLA researchers plan additional studies to validate these candidate salivary targets on a population level in independent patient cohorts. The same researchers are also conducting a detailed analysis of the salivary transcriptome (the set of all mRNA molecules in saliva), and further research of oral fluid biomarkers for oral cancer detection. For more information, visit JADA online for a 2006 report on salivary diagnostics and a 2001 report on the management of Sjogren’s syndrome in dental practice.  

Footnotes 

1. Hu S, Wang J, Meijer J, Ieong S, Xie Y, Yu T, Zhou H, Henry S, Vissink A, Pijpe J, Kallenberg C, Elashoff D, Loo JA, Wong DT. Salivary proteomic and genomic biomarkers for primary Sjogren’s syndrome. Arthritis Rheum 2007 Oct 29;56(11):3588-3600 [Epub ahead of print]. Abstract available at: http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=pubmed&dopt=AbstractPlus&list_uids=17968930”. Accessed November 6, 2007.

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Science in the News is a service by the American Dental Association (ADA) to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.

Page Posted November 2007