Glycotoxicity, oxidative stress and tissue senescence: role of microRNAs and effects on wound healing

Abstract

Using in vitro and in vivo systems, we have studied the role of chronic hyperglycemia present in Diabetes Mellitus (DM) on migration and function of fibroblasts. Impaired wound healing is a common complication of DM and contributes to the formation of chronic wounds, which reduce patient's life quality and entail enormous costs for the public health system. We demonstrated deleterious effects of high glucose on fibroblasts migration, which were reversed in the presence of an antioxidant. We also demonstrated that systemic or topical administration of antioxidants (such as vitamins C and E, proanthocyanidins, honey) significantly accelerated skin healing in diabetic mice. Using primary fibroblasts and the NIH-3T3 fibroblast lineage, we identified an oxidative stress-dependent glucose-regulated miRNA capable of modulating some aspects of cell migration: miR-31. Another high glucose-regulated miRNA with potential effects on cell migration is miR-29c, which can also modulate the composition of the extracellular matrix (ECM), altering the healing microenvironment. As a stressor, high glucose can accelerate the aging of fibroblasts, inducing a senescence-associated secretory phenotype (SASP). SASP fibroblasts, through the secretion of cytokines, metalloproteases and growth factors, can regulate the activity of other cell types and modify the microenvironment, favoring the aging of the entire tissue. The role of glycotoxicity in fibroblast aging, however, is still poorly understood; even less is known about the potential involvement of miRNAs in this process. In this project we intend to evaluate, in normoglycemic and hyperglycemic mice, the cellular senescence process in the dermis during wound healing, in the presence and absence of treatment with antioxidants. In vitro, using human fibroblasts, we intend to study the role of elevated glucose and consequent oxidative stress on the expression of miR-146b and miR-29c, as well as their potential involvement in cell senescence and migration in collagen I matrices (2-D and 3-D). Potential targets will be identified and validated through luciferase assays. In the dermis, processes related to cell migration, ECM production and senescence are essential for tissue homeostasis and healing; therefore, there is considerable interest in understanding the effects of hyperglycemia on these processes, especially in areas focused on biotechnology. The identification of potential regulatory agents, such as antioxidants and regulators of the expression of miRNAs (miR mimics or antagomiRs) is of great interest. This is an important and pioneering assessment, and the results obtained may eventually serve as a basis for senolitic treatments aimed at limiting the effect of senescent cells on tissue aging. (AU)