Vitamin A and Its Multi-Effects on Pancreas: Recent Advances and Prospects

Abstract

Vitamin A (VA), which is stored in several forms in most tissues, is required to maintain metabolite homeostasis and other processes, including the visual cycle, energy balance, epithelial cell integrity, and infection resistance. In recent years, VA molecules, also known as retinoids, have been extensively explored and used in the treatment of skin disorders and immune-related tumors. To date, several observational and interventional studies have explored the relationship between VA status and the pathogenesis of diabetes. In particular, VA micronutrients have been shown to regulate pancreatic development, β-cell function, pancreatic innate immune responses, and pancreatic stellate cells phenotypes through multiple mechanisms. However, there are still many problems to be proven or resolved. In this review, we summarize and discuss recent and available evidence on VA biological metabolism in the pancreas. Analysis of the effects of VA on metabolism in the pancreas will contribute to our understanding of the supportive physiological roles of VA in pancreas protection.

Keywords: development; diabetes; function; immune response; pancreas; pancreatic stellate cells; vitamin A.

Figure 1

VA metabolic and signaling systems in cells. Retinol, retinal, and retinoic acid are three derivatives of VA. Each molecule has a cis and trans configuration, and the most active form is retinol. Retinol has 6 biologically active isoforms: all-trans, 11-cis, 13-cis, 9,13-di-cis, 9-cis, and 11,13-di-cis, with all-trans being the predominant form [21]. In cells, retinol can be converted to RA which regulates multiple nucleus transcription by activating the RXR-RAR, RXR-PPAR, STAT 3/5.

Figure 2

Effects of VA and its derivatives on pancreas. VA and its derivatives are reported to promote pancreas development, maintain glucose homestasis, regulate pancreatic innate immunity, and transform PSCs phenotype.