Background Sjögren’s syndrome (SS) is a chronic autoimmune exocrinopathy, manifested by a wide spectrum of clinical sequelae ranging from sicca to severe extra-glandular features. A hallmark of the pathogenesis of SS is inflammation of MSG. Vitamin D is well-known to participate actively in different key pathways in the immune system, and plays an important role in pathogenesis of many autoimmune diseases. There are few prior studies of the role of VD in primary SS (pSS) in the context of comorbidities and disease severity
Objectives To evaluate serum VD levels and severity of sialadenitis with relationship of clinical and laboratory profiles in patients with pSS
Methods We reviewed 214 records of patients who had a MSG biopsy for a clinical suspicion of SS, in the Division of Rheumatology at UM, between 1993 and 2011. Eighteen patients with other autoimmune/neoplastic processes were excluded. Pathology results were assessed of the remaining 196 patients with SS, and showed sialadenitis with a Focus Score (FS)≥1 in 111 vs. 85 with FS<1. Chemiluminescence immunoassays for serum VD levels (25-100 ng/mL), were performed in 77 patients. Serum VD levels were assessed in the context of severity of sialadenitis, as well as other clinical, laboratory and serological data. Demographic, clinical and immunological data were collected including sicca symptoms, extra-glandular manifestations, autoantibodies, and clinical laboratory test. The protocol was approved by the UM Institutional Review Board. Statistical analysis included Students t-test with results indicated as mean ± standard deviation of the mean (SD) and correlations, parametric and nonparametric. A two-tailed value of p<0.05 was taken to indicate statistical significance
Results Patients were divided into those with a (FS)≥1 and FS<1. VD means were comparable in both groups 28.5 (15.0), vs. 27.8 (13.2) (p=0.825). In patients with a FS≥1, VD means were not associated with gender, ethnicity, age, or smoking history. In this group 22/48 (48.8%) patients met AECG-criteria for pSS. Mean VD levels were comparable in patients with and without pSS. However, high W-ESR, present in 25% of pSS patients, associated with low VD levels 12.4 (6.2) vs. 28.5 (15.0) (p=0.033). Fibromyalgia present in 19/48 (39.6%) patients was associated with lower mean VD levels of 22.2 (13.4) vs. 32.7 (14.7) mean VD level in those without it (p=0.016). Hypothyroidism, present in 11/48 (22.9%) patients, was associated with lower VD levels 19.5 (9.8) vs. a mean VD level of 31 (15.3) (p=0.022) in those without it. Patients with a FS>1, present in 36/48 (75%) vs. FS=1 had higher VD levels 31.4 (14.3) vs. 19.92 (14.3) (p=0.02).
VD levels correlated directly with the FS>1, 0.594 (p<0.0001). Vitamin D levels correlated indirectly with fibromyalgia, r=-0.345 (p=0.016) and hypothyroidism, r=-0.33 (p=0.022). When comparing other clinical-laboratory-serology variables specific for SS, mean VD levels were not different
Conclusions Low VD associate with high W-ESR in patients with diagnosis of pSS. Higher VD levels were associated with a higher level of inflammation in minor salivary glands. Low VD levels are seen in patients with SS who also have comorbities of hypothyroidism and fibromyalgia
Acknowledgements We appreciate the input of Dr. Sheeja Francis for her comments and critical review
Disclosure of Interest: R. Peredo Employee of: University of Michigan. Nothing to declare, A. Impens Employee of: Midwestern University. Nothing to declare, K. Phillips Employee of: University of Michigan. Nothing to declare