Relation Between Tissue Iron Content and Polarization of Macrophages in Diabetic Ulcer and the Transitional Zone of Diabetic Ulcers with Major Amputation

Abstract

Most diabetic lower-limb amputations probably result from combinations of contributing causes rather than from unitary causes. Iron-induced damage might modulate the development of chronic diabetes complications. In this study, the relationship between tissue iron levels and polarization of macrophages in induction of angiogenesis was investigated in diabetic ulcer samples and the transitional zone of diabetic ulcers. Patients with diabetic ulcers who underwent amputation were included. The transitional zone of diabetic ulcers, from the same diabetic patients, was used as a control group. After tissue preparation, Perls Prussian blue staining and immunohistochemistry for CD11c, CD163, and CD68 markers were done. Vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF), Tie2, and protein kinase B (also known as AKT) transcription of genes were measured by real-time polymerase chain reaction. For statistical analysis, we used independent samples t-test or its nonparametric equivalents, Mann–Whitney U test was used for quantitative variables, and chi-square (or Fisher's exact test) for qualitative variables. According to the results, the ratio of M2 to M1 macrophages was decreased in ulcers tissue compared to the transitional zone of diabetic ulcers. The expression of angiogenesis-related genes was increased due to hypoxia induction such as HIF and VEGF in ulcer tissue (P < .0001), but the expression of vascular stability-related genes such as Tie2 was decreased (P < .0001).In amputated diabetic ulcers, the polarization of macrophages is toward the classic type, but no connection was found in terms of tissue iron and help in the polarization of macrophages.