Медицинская иммунология (Mar 2022)
Role of diamine oxidase in the pathogenesis of chronic urticaria
Abstract
Chronic urticaria is a polyetiological disease proceeding by various immunological and non-immunological (pseudo-allergic) mechanisms. Food intolerance is a distinct type of pseudo-allergies, manifesting, e.g., with histamine intolerance syndrome, caused by imbalance between the histamine accumulation and the ability to degrade it. The purpose of this article was to summarize results of recent studies, to discuss the difficulties of diagnosing this pathology, which primarily depends on the degree of impaired histamine degradation under the influence of diamine oxidase. Diamine oxidase is the main enzyme required for histamine destruction in the intestines, being synthesized by apical enterocytes. The review draws attention to the reasons leading to increased level of histamine not only with consumed food, given its different concentration in the same food products, depending, for example, on their processing and storage, but also with suppressing activity of the enzymes required for metabolism of histamine by various food additives, by the influence of microbiota. The results of studies in which the levels of histamine and/or diamine oxidase activity were determined, which depend on adherence to the diet confirming the association of diamine oxidase with the symptoms of histamine intolerance. According to most studies, the compliance with diet led to increased level of diamine oxidase. However, in some studies, no changes in the activity of this enzyme were found. There are several studies that have evaluated the levels of diamine oxidase in patients with true allergies. Moreover, some authors, in addition to adherence to the diet, evaluated the effectiveness of drugs containing diamine oxidase in patients with low levels of this enzyme in blood serum. The workers also confirm high proportion of histamine intolerance syndrome among various food reactions, suggesting a need for differential diagnosis with other non-immune reactions, including disorders of gastrointestinal tract and psychosomatic reactions. Thus, all the authors confirm the need for laboratory diagnosis of histamine intolerance syndrome, since this will not only increase the efficiency of dietary adherence, but also substantiate the usage of drugs containing diamine oxidase, which will improve quality of life in these cohorts. However, these patients are still treated with low-histamine diets. The literature data confirm the opportunity of using this histamine degradation enzyme as a biological marker of histamine intolerance syndrome, and recommend its assays for inclusion into the diagnostic algorithm for chronic urticaria.
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