Primary Sjögren's syndrome (pSS) is a chronic systemic inflammatory disease, which mainly affects the lacrimal and salivary glands, leading to sicca syndrome. pSS has a probable autoimmune etiology, with the production of several autoantibodies such as antinuclear antibodies (ANA), anti-Ro/SS-A, anti-La/SS-B, rheumatoid factor (RF) and cryoglobulins. Recently, our group described a high frequency of antibodies directed to DNase I in the serum of pSS patients and these antibodies were associated with the presence of the anti-Epstein-Barr (EBV) early antigen diffuse (anti-EA-D). This finding becomes interesting considering the recent description of reduction of DNase I activity in the tear of patients with xerophthalmia of different causes, which would result in an accumulation of extracellular DNA and neutrophilic inflammatory infiltrate on the ocular surface. This hypothesis is reinforced by the observation that treatment with DNase I as eye drops results in clinical improvement of dry eye. In addition, it has been shown that periodontal disease is an aggravating factor of xerostomia in pSS, as it leads to a chronic inflammatory process and, consequently, to the destruction of minor salivary glands. Therefore, the objective of the present study will be to evaluate the presence of antibodies directed to DNase I in the saliva and serum of pSS patients and its possible capacity of inhibition of the enzyme. Such findings will be correlated with the presence of periodontal disease, with the glandular and extraglandular manifestations of SSp and also with the presence of EBV DNA in the serum and oral lavage of these patients.
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