[Evaluation of biomarkers of intestinal permeability and inflammation in food allergies].

The digestive tract performs an important barrier function, protecting the internal environment of the organism from excessive intake of various macromolecules, especially of food origin. Despite numerous works devoted to the study of the mechanisms of development of food allergy (FA), many aspects of its pathogenesis require further interpretation and research. This is necessary for the introduction of effective diagnostic methods and new therapies. The purpose of the research was to determine the diagnostic and pathogenetic significance of markers of increased intestinal permeability and inflammation in children with FA.

Material and methods: The criteria for inclusion in the research were the age of children from 3 to 7 years old; patients with a diagnosis of FA. 45 children with FA were examined, the clinical marker of which was atopic dermatitis (AtD) associated with underlying disease (AtD + FA). The control group consisted of 20 practically healthy children. The levels of zonulin, calprotectin, eosinophilic neurotoxin and secretory immunoglobulin A (sIgA) in coprofiltrates, total immunoglobulin E (IgE), specific IgE antibodies to food allergens and eosinophilic cationic protein in the blood serum were determined for all children.

Results: The examined children with AtD + FA showed high levels of blood total IgE 273.89 [157.2; 597.2] IU/L, hypersensitivity to a number of foods (cow's milk, egg, fish, wheat), eosinophilia (6.90±1.15%). Zonulin levels were increased (p<0.05) in patients with moderate FA compared with mild FA and amounted to 84.3 [67.8; 93.5] and 26.5 [17.5; 62.3] ng/ml, respectively, versus 21.5 [13.2; 30.9] ng/ml in healthy children. The amount of calprotectin in the stool was within the normal range. The sIgA content in feces was reduced in all patients, amounting to 32.3 [1.66; 50.7] μg/g versus 61.4±3.2 μg/g in children from the control group (p<0.05). The amount of eosinophilic neurotoxin in feces (1025.65 [327.96; 1739.54] ng/g) and eosinophilic cationic protein in blood serum (35.23 [30.12; 39.78] ng/ml) was increased, unlike in children of the control group (610.4 [300.25; 1101.97] ng/g and 29.67 [25.43; 32.75] ng/ml respectively, p<0.05).

Conclusion: The study revealed the signs of increased intestinal permeability, eosinophilic inflammation, and impaired mucosal immunity in children with AtD + FA. Patients with moderate disease severity showed increased intestinal barrier permeability, as evidenced by high levels of zonulin in coprofiltrates, as well as activation of eosinophilic inflammation, as indicated by elevated levels of eosinophilic neurotoxin and cationic protein. In addition, a decrease in mucosal immunity was detected, as evidenced by low values of secretory IgA, which indicates a disruption of the barrier function of the gastrointestinal mucosa. These findings suggest an important role of intestinal permeability and eosinophilic inflammation in the pathogenesis of moderate forms of AtD + FA, which may have significant implications for the development of new therapeutic approaches.