Comparison of serum levels of inflammatory marker Calprotectin, indicating intestinal inflammation, in patients with Sjögren´s syndrome versus patients with IBD, and detection of autoreactive T cells

Abstract: Sjögren’s syndrome (SS) is a chronic autoimmune disease with exocrine glands dysfunction and multi organ involvement. Sicca symptoms such as xerophthalmia and xerostomia are the most common features in this disease. Increased intestinal permeability has been demonstrated in various autoimmune disorders, and Calprotectin, a protein released by neutrophils and monocytes due to cell stress or damage, is used as a biomarker in gastrointestinal disorders. In the present study we investigated intestinal inflammation in Sjögren’s syndrome patients by measuring Calprotectin concentration in serum samples of these patients. Calprotectin concentration was measured by ELISA in serum samples of patients with Sjögren’s syndrome, serum samples of patients with inflammatory bowel disease (IBD) including ulcerative colitis (UC) and Crohn’s disease (CD) with known increased intestinal permeability. Serum samples of healthy individuals were used as negative controls. As expected, we found higher levels of Calprotectin in serum samples from patients suffering from UC and CD. We have also shown increased levels of serum Calprotectin in samples of SS patients but with lower concentration compared to IBD patients. Furthermore, since a sensitive and specific diagnostic method is lacking for Sjögren’s syndrome, we have optimized an assay that could be used as a diagnostic tool for detection of disease specific T cells. The assay was evaluated using cells from experimental autoimmune encephalomyelitis (EAE) mice, an established animal model for human multiple sclerosis (MS).