Novel autoantibodies in Sjogren's syndrome

The Potential Role for Early Biomarker Testing as Part of a Modern, Multidisciplinary Approach to Sjögren’s Syndrome Diagnosis

“…In a study using an interleukin 14alpha transgenic (IL14aTG) mouse model which develops many features of SS, Shen et al found that only about 25% of the IL14aTG mice developed antibodies to SS-A or SS-B [58]. Further investigations of the timing of antibody appearance found that antibodies to SP-1 and CA-6 occurred earlier and at much higher prevalence overall compared with anti-SS-A or anti-AA-B antibodies.…”

“…Finally, the investigators tested the sera from 29 patients with idiopathic xerostomia and xerophthalmia of less than 2 years' duration, all of whom met at least three diagnostic criteria for SS. Within this group of patients with apparent early SS, 76% demonstrated antibodies to SP-1 or CA-6, while only 31% had antibodies to SS-A or SS-B [58].…”

“…The same investigators also tested sera from 13 patients having SS for at least 5 years and found 69% of them positive for antibodies to SP-1 or CA-6. While 62% of the patients tested positive for the traditional biomarkers (anti-SS-A or anti-SS-B), 38% of the patients tested negative for these antibodies [58]. Finally, the investigators tested the sera from 29 patients with idiopathic xerostomia and xerophthalmia of less than 2 years' duration, all of whom met at least three diagnostic criteria for SS.…”

“…In fact, three early biomarkers of SS have been identified that are specific to proteins selectively originating from the salivary and lacrimal glands, unlike SS-A and SS-B autoantibodies which are found in virtually every cell. These new biomarkers are auto-antibodies to salivary protein-1 (SP-1), parotid secretory protein (PSP), and carbonic anhydrase VI (CA-6) [58,59]. An emerging hypothesis regarding SS pathogenesis includes a major role of the innate immune system [60].…”

“…It was identified as a product of one of the genes upregulated in the thymus by the autoimmune regulator gene (AIRE) to prevent development of T lymphocytes. PSP is a protein that is involved in the binding and clearance of infectious agents, while CA-6 is an enzyme that has been found to be involved in the buffering of saliva, and it is found in the cytoplasm and secretory granules of serous acinar cells in the submandibular and parotid glands [58].…”