A significant proportion of patients with fibromyalgia (FM) complain of dry eyes and mouth. Many Sjögren's syndrome (SS) patients also complain of FM symptoms, and there is literature that suggests that there is interplay between these two disorders. Recently, the presence of novel tissue specific autoantibodies (TSAs), SP-1, CA6, and PSP, has been observed in the early stages of SS. These early markers present themselves before the classic autoantibodies, such as SS-A/Ro, SS-B/La, ANA, and RF.
This study aims to examine the relationship between SS and FM by testing patients with FM who also complain of xerostomia and sicca symptoms, for SS- related biomarkers.
A cohort of 185 patients who met both the 1990 and 2010 preliminary diagnostic criteria for FM and who admitted to symptoms of sicca and/or xerostomia were selected for this study. Serum from 151 study patients was sent to a tertiary lab, Immco Diagnostics, for testing of the classic autoantibodies (SS-A/Ro, SS-B/La, ANA and RF) and TSAs (SP-1, CA6, PSP), while the rest (34 patients) were tested for TSAs only.
Of the 151 patients who were evaluated for both the early and classic SS markers, 49 (32%) tested positive for SS autoantibodies. Of those, 4 (3%) tested positive for the classic SS markers only, 40 (26%) of the patients tested positive for the early SS markers only, and 5 (3%) tested positive for both the early and classic SS markers. Of the 34 patients who were tested for early SS markers only, 10 (29%) tested positive and 24 (71%) tested negative. Further analysis of all the patients that tested positive for the TSAs (n = 55), found 83.6% (46) were positive for SP-1, 12.7% (7) were positive for CA6 and 20.0% (11) were positive for PSP. 85.5% (47) of these patients were positive for only one of the TSAs and 14.5% (8) were positive for more than one TSA.
Approximately 1/3 of FM patients that were tested for both the TSAs and classic Sjögren's markers tested positive for a SS biomarker, and the majority of those patients tested positive for one or more of the TSAs. This suggests that autoimmunity, specifically early- stage Sjögren's syndrome, may be involved in the pathophysiology of fibromyalgia.