The Role of Gut-skin Axis in Psoriasis: a Randomized Placebo-controlled Dietary Approach to Assess Clinical Efficacy in Mild-to-moderate Psoriasis
Psoriasis is a systemic chronic inflammatory immune-mediated disease whose etiopathogenetic mechanisms involve genetic predisposition, and immunological and environmental factors. Its prevalence is about 3% in adults, and it is characterized by well-demarcated, erythematous plaques, covered by silvery-white scales, in elbows, knees, trunk, and scalp. However, psoriasis is far from being considered just a dermatologic condition because the cytokine's cascade, which lays behind its inflammatory and immune-mediated pathogenesis, can determine multiple systemic manifestations. In addition, several patients with psoriasis often complains of gastrointestinal (GI) symptoms. Therefore, authors focused their attention over the gut-skin axis and its possible pathogenetic and immunoregulatory role in psoriasis (i.e., altered gut barrier, increased blood concentration of gut microbiota-derived metabolites, systemic inflammation). In this context, several dietetic approaches (e.g., Mediterranean, low calories, protein-restricted, vegetarian diets, and gluten-free diet, GFD) have shown a certain efficacy in improve psoriasis cutaneous and systemic manifestations. In recent years, the existence of a wheat-related disorder in patients who do not suffer from CD or wheat allergy (WA) has been definitively ascertained and defined as Non-Celiac Wheat Sensitivity (NCWS). Its prevalence in the general population is unknown, but self-reported NCWS is around 10%. This condition is characterized by both GI and extraintestinal symptoms, which are triggered by wheat ingestion. In these patients, wheat ingestion might lead to alteration in intestinal permeability and gut microbiota and to systemic immune activation and inflammation. Based on the evidence of gut involvement in the pathogenesis and clinical manifestation of psoriasis, as well as on the ability of gluten/wheat to increase intestinal permeability, it could be hypothesized that gluten/wheat may represents one of the pathogenetic environmental factors of psoriasis and that its intake may be able to worsen symptoms in affected patients. The investigators hypothesize that a wheat-free diet (WFD) can reduce the inflammatory state and ameliorate the clinical symptoms in psoriasis patients. The successive clinical and immunologic reaction to the re-exposure to wheat ingestion, performed by an open challenge, will be also evaluated to confirm a wheat-dependent mechanism and to understand the underlining physiopathology.
• age >18 and <65 years;
• no systemic therapy for psoriasis for at least 3 months before inclusion in the study;
• negativity of anti-deamidated gliadin protein (anti-DGP) immunoglobulins (Ig) class A (IgA) and immunoglobulins (Ig)G, anti-tissue transglutaminase (anti-tTG) class IgA and IgG, and Endomysium antibodies (EmA);
• absence of WA (negative prick-test and/or specific serum immunoglobulins (Ig)E assay for wheat, gluten, and gliadin).