The effect of enzyme therapy on skin symptoms and immune responses in patients with dermatitis herpetiformis

Background: The aetiology of coeliac disease (CD) has many similarities to that of dermatitis herpetiformis (DH), except that DH lesions are mainly manifested in the skin. Mucosal enzyme deficiency plays an important part in CD pathology. Clinical studies indicated that the gluten exposure in CD could be partly corrected by the use of enzyme supplementation. Objective: Enzyme therapy, using enterically coated tablets containing caricain, was investigated as a means of protecting patients with DH against wheat gluten. Methods: A randomized, placebo-controlled clinical trial was carried out on 20 DH patients in clinical remission. The patients were divided into two groups of 10, one group given a placebo daily and the other the enzyme - containing tablets. Both groups were challenged with 6g of gluten daily in a double-blind trial. Symptoms and signs of skin involvement were recorded and graded at the start of the trial, after 7 days and after 14 days. Blood was also taken at the start and after 14 days and assayed for IgA EMA and anti-gliadin antibodies. Results: After 7 days the major features associated with DH were more severe and more common with the placebo compared with enzyme therapy. Before 14 days, seven patients in total, six on placebo, had to withdraw from the trial because of the effects of the gluten challenge whilst 2 patients on therapy developed blisters, erythema and itching. Serological tests indicated that IgA EmA antibodies and anti-gliadin antibodies after 14 days were not affected significantly, but indicated that abnormally high antibodies titers of both types were present in 8 patients at the start of the trial, suggesting the need for enzyme therapy in addition to the normal gluten-free diet for patient well-being. Conclusions: This study supports the use of enzyme supplementation as a safeguard for patients with DH on a nominal gluten-free diet.