Avaliação das alterações nucleares e cromatínicas em linfócitos do sangue periférico de portadores de diabetes

Abstract

Diabetes mellitus (DM) is considered an heterogenous group of metabolic disorders with hyperglycemia as a common event, because of defects in insulin secretion and/or action. Hyperglycemic condition resultant of DM can have a key role in changing cellular homeostasis, as a result of functional and structural alterations in several cellular components, being chromatin and example. Some changes in chromatin may be associated with changes in gene expression in immune cells as lymphocytes, which can lead to the dysfunction immune response on diabetes mellitus . Therefore, our aim was to screen for changes in chromatin organization of peripheral blood lymphocytes of both types 1 and 2 diabetic and non-diabetic subjects. In the present study, 20 men and women, with age range between 18 to 55 years old, have participated. Subjects were divided into three groups: Group 1, DM1 subjects, Group 2, DM2 subjects, and Group3, non-diabetic subjects or control group, paired with the other two groups by age and gender. Peripheral blood samples were collected from all subjects in the morning after an 8 hours fasting period, followed by dosage of glycaemia and glycated hemoglobin. Peripherical blood mononuclear cells from heparinized samples were isolated using the Ficoll method. Isolated cells were cytocentrifuged onto microscopy slides, fixed and Feulgen-stained. For evaluation of morphometric parameters of nuclear and chromatinic organization, digital images of stained nuclei were subjected to image analysis, and the results were correlated with results from blood dosages. Similar changes in chromatin organization were found in blood lymphocytes for both types of diabetes, including increased chromatin packaging and reorganization in diabetic subjects, but with a much more pronounced evidence of aneuploidy on lymphocytes of DM1 subjects. Glycated hemoglobin levels were positively correlated with blood glucose levels in both types of diabetes. However, for group1 the only statistical significant correlation found was between glycaemia, glycated hemoglobin and DNA content. For the group 2, glycaemia, even showing smaller values when compared with those for DM1, correlated well with all nuclear parameters, except changes in DNA content, which were more discrete for this group. According to present results, it is clear that both types of diabetes, as a consequence of hyperglycemia, are associated with important structural alterations in nuclei of human lymphocytes, which, we believe, may be causative agents of functional changes in this cell type, with consequent decline in immune functions of individuals.