Repercussões imunológicas e metabólicas da ingestão continuada de antígeno por animais sensibilizados

Abstract

Food allergy affects about 5% of children and 3% ofadults in western world. The allergen restriction is the chosen treatment in this condition, but the ingestion of the antigen in increasing doses has shown interesting results in experimental clinical protocols. We developed an experimental food allergy model to Ovalbumin (OVA) in mice that induces several signals similar to those we found in human beings. In this model, the ingestion of OVA by sensitized mice results in an increased anti-OVA IgE and IgG1 production, besides a marked weight and adipose tissue loss which is inflamed. Because of the strong association between metabolic disorders and adipose tissue inflammation, it is important to study the immunological and metabolic consequences of the continued ingestion of antigen by sensitized mice. The aim of this study was to evaluate the development of the immunological and metabolic alterations caused by the continued ingestion of OVA by previously sensitized mice. The allergic process, that happened after 7 days of OVA ingestion by sensitized mice, was evidenced by the increased anti-OVA IgE and IgG1 levels and the development of antigen aversion. This process resulted in body andvisceral adipose tissue weight loss with an adipocyte hypotrophy. Also, in the adipose tissue, there was an increase in the leucocyte recruitment and in the production of IL-6. In systemic levels, it was possible to observe a decrease in the serum titers of adipokines such as adiponectin, resistin and leptin as well as the glucose and triglyceride levels. Also in this time, mice were more tolerant to the oral glucose tolerance test (OGTT). After 14 days of oral challenge, sensitized mice showed an anti-OVA IgE level similar to the mice that were only sensitized, but the anti-OVA IgG1 level didnt change. With this developed desensitization to OVA, different parameters returned to the levels showed by nonsensitized animals. For example, the amount of OVA eaten, the body weight, the adipocyte area, the leukocyte recruitment to the adipose tissue, the production of IL-6 by this tissue, the tolerance to glucose (OGTT) and the serum levels of adiponectin, leptin, resistin and triglycerides. However, the loss of visceral adipose tissue and the serum levels of glucose were kept similar to the mice that received the OVA diet for only 7 days. Our data suggest that the continued ingestion of OVA by sensitized mice leads to a desensitization with systemic metabolic consequence.