Recent data show that some foods can increase intestinal mucosa permeability and immune activation of subjects with gastrointestinal (GI) symptoms. Wheat seems the most frequent food which activates this inflammatory response and can cause both GI and extra-intestinal symptoms. Patients suffering from wheat-related troubles, in absence of celiac disease diagnosis, can suffer from non-celiac wheat sensitivity (NCWS) and our previous studies showed that about 25% of them are also affected by autoimmune diseases (AD). A gluten-free diet (GFD) can influence inflammatory pattern of AD, including Sjogren's syndrome (SS). Thus, the investigators would enquire if SS patients may also suffer from NCWS and how a wheat-free diet (WFD) modifies their clinical features, and inflammatory and cytokine pattern. The investigators will also assess how wheat reintroduction, by an open challenge, modifies their clinical parameters, intestinal permeability, and both local and systemic inflammatory response.