Glycation and metabolic syndrome in the skin premature aging

Purpose: In recent years, the role of advanced glycation end products (AGEs) in promoting and exacerbating metabolic and skin abnormalities has attracted much attention. In this study, we elucidated the relationship between AGE accumulation and skin characteristics, commonalities, and features in metabolic syndrome (MS) patients and controls.
Methods: Caucasian male and female patients (n = 296) living in Riga, Latvia, divided into MS (n = 149) and non-MS (n = 147), were analyzed by skin lesion (epidermoid nigricans, seborrheic keratosis, actinic keratosis, age-related wrinkles, gravitational wrinkles, and facial telangiectasia). MS was diagnosed using IDF criteria. For glycative stress index, skin autofluorescence (SAF) was measured using AGE Reader, and skin AGE accumulation was evaluated. Skin findings were assessed using Dermatoscopy Dermlite for facial teleangiectasia, dermatosis and dyspigmentation. Blood biochemical analysis included oxidative stress indices (glutathione: GSH, selenoprotein: Se, superoxide dismutase: SOD, glutathione peroxidase glutathione peroxidase: GPx, and malondialdehyde: MDA).
Results: The MS group showed higher body mass index (BMI) (p < 0.001, Mann-Whitney test), higher triglyceride (TG) (p < 0.001, Mann-Whitney test), lower HDL-C (p < 0.001, Mann-Whitney test), and lower Vitamin D (p = 0.05 compared to the non-MS group. For inflammatory response and oxidative stress, the MS group showed higher C-reactive protein (CRP) (p = 0.007, Mann-Whitney test), higher MDA (p = 0.006, Mann-Whitney test), and significantly equal SOD (p = 0.291). SAF, an index of glycative stress, was significantly equal in the MS group (p = 0.468). Next, we conducted a Spearman rank correlation analysis between SAF and each item. Significant correlations were found for the following items: FPG: r = 0.345 (p = 0.036, n = 37), TC: r = 0.328 (p = 0.023, n = 48), HDL-C: r = −0.399 (p = 0.019, n = 34), CRP: r = 0.372 (p = 0.028, n = 37), and CRP: r = 0.372 (p = 0.028, n = 37). No significant correlations were found with other items.
Skin lesions were classified as seborrheic keratosis (n = 109), actinic keratosis (n = 25), acanthosis nigricans (n = 16), aging wrinkles (n = 126), gravity wrinkles (n = 34), facial telangiectasia (n = 242), and lentigo pigmentosa (n = 204). SAF was positively correlated with skin aging parameters of seborrheic keratosis and lentigo pigmentosa (p < 0.05) and associated with the severity of skin aging on the face using the skin aging index (p < 0.05). In skin biopsies, the expression of GLUT-1 was increased, accompanied by a decrease in the number of regulatory T cells.
Conclusion: MS was associated with excess ROS and reduced antioxidant capacity. Accumulation of AGEs in the skin was strongly associated with clinical aging-related changes (seborrheic keratosis, telangiectasia, and skin wrinkles). The AGE accumulation was associated with inflammatory processes, indicating that SAF may be closely related to skin health.