Crosstalk Between Oxidative Stress, Protein Glycation, and Extracellular Matrix Remodeling in the Skin of Rats with Type 1 Diabetes: Does Insulin Administration Improve Skin Homeostasis?

The exact mechanisms of skin involvement in type 1 diabetes (DM1) remain poorly understood. This study aimed to evaluate the relationship between antioxidants, oxidative stress, protein glycation, and glycoxidation, as well as matrix metalloproteinase (MMP) activity, in the skin of rats with DM1, while investigating whether insulin administration improves skin homeostasis. Male Wistar rats were assigned to three groups: control, diabetes, and diabetes treated with insulin. Significantly higher expression of GSH (gluthatione) and GSH-Px (glutathione peroxidase), elevated levels of AGE (Advanced Glycation End products), DT (dityrosine), KN (kynurenine), NFKN (N-formylkynurenine) and ONOO- (peroxynitrite), as well as increased activity of GLU (β-D-glucuronidase), NADPH oxidase (NOX) and MMP-1, -2, -3, -7, -9, -11 and -13 were observed in the skin of rats with DM1. Insulin treatment normalizes the skin's antioxidant barrier and eliminates oxidative stress. It also reduces the intensity of protein glycation and glycoxidation, though not to the levels observed in the control group. Summarizing, in diabetic skin there is a complex interaction between the thiol antioxidant barrier, oxidative damage, protein glycation and glycoxidation as well as MMP expression. Insulin restores physiological balance in skin cells; however, glycation and ECM remodeling are still more pronounced than in healthy skin.