Association Between Psoriasis and Coeliac Disease? A Case-control Study

The first published data concerning a possible relationship between psoriasis and pathologies of the gastrointestinal tract appeared as long as 30 years ago (1, 2), and subsequently there have been numerous reports on psoriasis and coeliac disease (3-5). These reports have included investigations into the presence of antibodies specific to coeliac disease in patients with psoriasis compared with controls. The findings demonstrated, in some cases, no correlation (6-8), but in others the presence of high titre in the IgA antibodies anti-gliadin, anti-reticulin, anti-endomysium and tissue anti-transglutaminase (9, 10). Furthermore, the presence of these antibodies and their increase was linked to a greater severity in the skin pathology (4). There have also been reports of patients with extensive psoriasis lesions and positivity for anti-gliadin, whose skin lesions regressed significantly after following a gluten-free diet for 3—6 months only to reappear on stopping the diet (11). In particular, it was also found that using a gluten-free diet as sole therapy in patients with psoriasis, who were positive for anti-gliadin and with high transglutaminase titres, improvement in skin lesions occurred along with a reduction in transglutaminase titre (12). As regards the pathogenetic mechanism behind this possible association, little is known, although there have been diverse hypotheses (3, 13): (i) the anomalous intestinal permeability in people with coeliac disease could represent a trigger factor for psoriasis; (ii) in coeliac disease gliadin induces a sensibilization of T cells, and their activation could be associated with the pathogenesis of the cutaneous lesions; (iii) psoriasis lesions in people with coeliac disease could be related to vitamin D deficiency, a characteristic of both diseases. Because in Sardinia there is a high prevalence of subclinical coeliac disease (14), we performed a case-control study to evaluate a possible association between this disease and psoriasis.