AUTHOR=Stafa Klodjan , Rella Antonella , Eagle Whitby , Dong Kelly , Morris Kelsey , Layman Dawn , Corallo Krystle , Trivero Jacqueline , Maidhof Robert , Goyarts Earl , Pernodet Nadine 

TITLE=miR-146a is a critical target associated with multiple biological pathways of skin aging

JOURNAL=Frontiers in Physiology

VOLUME=Volume 15 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1291344

DOI=10.3389/fphys.2024.1291344

ISSN=1664-042X

ABSTRACT=The skin is the largest organ of the human body and fulfills protective, immune, and metabolic functions. Skin function and barrier integrity are actively regulated through circadian rhythm-associated genes and epigenetic mechanisms including DNA methylation/demethylation, histone acetylation/deacetylation, and microRNAs. MicroRNA-146a-5p (miR-146a) has been associated with immune activation and skin inflammation; however, the role of miR-146a in regulating skin aging is an open question. This study investigated the role of miR-146a in fibroblasts obtained from different donors in the context of aging, and a potential association of this miRNA with circadian rhythm.Methods: Normal human dermal fibroblasts (NHDFs) from 19y, 27y, 40y, and 62y old were used to analyze for miR-146a expression. Expression of miR-146a was down-regulated with the has-mirVana miR-146a inhibitor, and up-regulated with an extract from Adansonia digitata. Effects on markers of skin aging, including cell proliferation, production of Collagen-1 and inflammatory cytokines were assessed.We show that the expression of miR-146a decreases with age in dermal fibroblasts and inhibition of miR-146a in 19y and 62y old NHDFs induced significant changes in essential clock genes indicating an association with circadian rhythm control. Furthermore, downregulation of miR-146a results in a reduction of cellular proliferation, Collagen-1 production, as well as an increase in DNA damage and proinflammatory markers. Activation of miR-146a with the Adansonia digitata extract reduced the deleterious effects seen during miR-146a inhibition and increased miR-146a transport through exosome transfer.Conclusions: miR-146a interacts with multiple biological pathways related to skin aging, including circadian rhythm machinery, cell-to-cell communication, cell damage repair, cell proliferation, and collagen production and represents a promising target to fight skin aging. Adansonia digitata extract can promote miR-146a expression and therefore support skin cells' health.