Endocrine Abstracts

Introduction: Type 1 diabetes mellitus is a T-cell mediated autoimmune disease characterized by the destruction of β-cells of the pancreas. Numerous studies have demonstrated the key role of FoxP3+ regulatory T-cells in the development of type 1 diabetes.

Aim: The aim of research: 1) to determine the expression patterns of transcription factor FoxP3 in the pancreatic lymph node cells in animal model of diabetes mellitus and 2) to assay an effect of metformin of these processes.

Methods: Researches are made on Wistar rats. For an induction of diabetes streptozotocin was used in doses 50 mg/kg. Structure of population of FoxP3⁺ cells has been studied by the analysis of serial histological sections using the method of indirect immunofluorescense with monoclonal antibodies to FoxP3 of rat.

Results: Development of experimental streptozotocin-induced diabetes mellitus (3-week ESIDM) led to a change in representation of FoxP3⁺-lymphocytes in paracortical zone and medullary cords of pancreatic lymph nodes (PLN), in which the total density decreased by 25% (P<0.05) and 28% (P<0.05) as compared to control group. Indicators in the group of rats with 5-week ESIDM decreased by 50% (P<0.05) only in medullary cords of PLN. After the administration of metformin in rats with 3-week ESIDM total density of FoxP3+-lymphocytes increased by 96% (P<0.05) in the paracortical area and by 93% (P<0.05) in medullary cords PLN rats with respect to 3-week ESIDM. The fluorescence intensity of FoxP3⁺-cells appeared to be a significant increased in medullary cords PLN as at 3-week ESIDM and at 5-week ESIDM, namely FoxP3⁺-medium and small lymphocytes. Administration of metformin resulted in a decrease in medullary cords PLN concentration FoxP3 in FoxP3⁺-medium and small lymphocytes with respect to indicators of a group of animals with a 3-week ESIDM that did not take metformin.

Conclusions: Our results demonstrate the metformin is able to increase the Treg number in PLN, by the way these effects manifest on the third week of the diabetes mellitus and they reduce of the fifth week of the pathological process duration.