Histological Visualization of Glyceraldehyde-Derived Glycation with Glucose using Ultrasound Microscopy

Abstract

Background: Reducing sugars and reactive aldehydes, such as glyceraldehyde (GA), non-enzymatically react with proteins to form advanced glycation end-products (AGEs). GA is produced in the glycolysis pathway, and GA-derived AGEs play an essential role in the pathogenesis of angiopathy associated with hyperglycemia in patients with diabetes. Aims: Several studies have reported on chemical alterations in glycation. However, histological confirmation of these biochemical changes has been relatively rare. This study aimed to visualize glyceraldehyde-induced glycation and evaluate the severity of glycation using attenuation of sound (AOS) values. Given that glycation promotes cross-links between proteins and sugars, the energy loss of sound that passes through them increases. We hypothesized that AOS alteration would reflect the glycation state of the tissues and cells. Methods: Fresh frozen sections or fresh cells were briefly fixed in ethanol and soaked in GA with different glucose concentrations. Thereafter, AOS images were obtained via scanning acoustic microscopy over time, and tissue and cellular glycation induced by GA with glucose was evaluated using AOS values. Results: AOS images were able to visualize GA-induced glycation over time. Compared to GA alone, glucose supplements concentration-dependently accelerated glycation. The arterial smooth muscle, collagen, and intima were apt to accept glycation, whereas the mucosa was unaffected. Conclusion: The comparability and digital nature of AOS images make them suitable for statistical analysis of glycation. Higher glucose concentrations promoted a greater increase in the AOS values of the sections and cells. Moreover, the increase in AOS values varied according to organs and cells, which supports the difference in affected organs among patients with diabetes mellitus. Our findings suggest that a longer hyperglycemic state promotes greater glycation.