Study of calcitriol anti-aging effects on human natural killer cells in vitro

The Potential Use of Vitamin D3 and Phytochemicals for Their Anti-Ageing Effects

Unlike other vitamins, vitamin D3 is synthesised in skin cells in the body. Vitamin D3 has been known as a bone-related hormone. Recently, however, it has been considered as an immune vitamin. Vitamin D3 deficiency influences the onset of a variety of diseases. Vitamin D3 regulates the production of proinflammatory cytokines such as tumour necrosis factor-α (TNF-α) through binding to vitamin D receptors (VDRs) in immune cells. Since blood levels of vitamin D3 (25-OH-D3) were low in coronavirus disease 2019 (COVID-19) patients, there has been growing interest in the importance of vitamin D3 to maintaining a healthy condition. On the other hand, phytochemicals are compounds derived from plants with over 7000 varieties and have various biological activities. They mainly have health-promoting effects and are classified as terpenoids, carotenoids, flavonoids, etc. Flavonoids are known as the anti-inflammatory compounds that control TNF-α production. Chronic inflammation is induced by the continuous production of TNF-α and is the fundamental cause of diseases like obesity, dyslipidaemia, diabetes, heart and brain diseases, autoimmune diseases, Alzheimer's disease, and cancer. In addition, the ageing process is induced by chronic inflammation. This review explains the cooperative effects of vitamin D3 and phytochemicals in the suppression of inflammatory responses, how it balances the natural immune response, and its link to anti-ageing effects. In addition, vitamin D3 and phytochemicals synergistically contribute to anti-ageing by working with ageing-related genes. Furthermore, prevention of ageing processes induced by the chronic inflammation requires the maintenance of healthy gut microbiota, which is related to daily dietary habits. In this regard, supplementation of vitamin D3 and phytochemicals plays an important role. Recently, the association of the prevention of the non-disease condition called "ME-BYO" with the maintenance of a healthy condition has been an attractive regimen, and the anti-ageing effect discussed here is important for a healthy and long life.

The anti-aging effect of vitamin D and vitamin D receptor in Drosophila midgut

Adult stem cells are pivotal for maintaining tissue homeostasis, and their functional decline is linked to aging and its associated diseases, influenced by the niche cells' environment. Age- and cancer-related reduction of vitamin D and its receptor levels are well documented in human clinical studies. However, the mechanisms through which the vitamin D/vitamin D receptor pathway contributes to anti-aging and extends life expectancy are not well understood. In this study, we aimed to determine the protective role of the vitamin D/vitamin D receptor pathway in differentiated enterocytes (ECs) during intestinal stem cell (ISC) aging. By utilizing a well- established Drosophila midgut model for stem cell aging biology, we revealed that vitamin D receptor knockdown in ECs induced ISC proliferation, EC death, ISC aging, and enteroendocrine cell differentiation. Additionally, age- and oxidative stress-induced increases in ISC proliferation and centrosome amplification were reduced by vitamin D treatment. Our findings suggest a direct evidence of the anti-aging role of the vitamin D/vitamin D receptor pathway and provides insights into the molecular mechanisms underlying healthy aging in Drosophila.

Senescence of bone marrow mesenchymal stem cells in Wistar male rats receiving normal chow/high-calorie diets with/without vitamin D

Bone marrow mesenchymal stem cells (BM-MSCs) have a momentous function in the composition of the bone marrow microenvironment because of their many valuable properties and abilities, such as immunomodulation and hematopoiesis. The features and actions of MSCs are influenced by senescence, which may be affected by various factors such as nutritional/micronutrients status, e.g., vitamin D. This study aimed to examine the effects of a high-calorie diet (HCD) with/without vitamin D on BM-MSCs senescence. In the first phase, 48 middle-aged rats were fed a normal chow diet (NCD, n = 24) and an HCD (n = 24) for 26 weeks. Afterward, the rats in each group were randomly divided into three equal subgroups. Immediately, eight-rat from each diet group were sacrificed to assess the HCD effects on the first phase measurements. In the second phase, the remaining 4 groups of rats were fed either NCD or HCD with (6 IU/g) or without vitamin D (standard intake: 1 IU/g); in other words, in this phase, the animals were fed (a) NCD, (b) NCD plus vitamin D, (c) HCD, and (d) HCD plus vitamin D for 4 months. BM-MSCs were isolated and evaluated for P16INK4a, P38 MAPK, and Bmi-1 gene expression, reactive oxygen species (ROS) levels, SA-β-gal activity, and cell cycle profile at the end of both phases. After 26 weeks (first phase), the ROS level, SA-β-gal-positive cells, and cells in the G1 phase were significantly higher in HCD-fed rats than in NCD-fed ones (P < 0.05). HCD prescription did not significantly affect cells in the S and G2 phases (p > 0.05). Compared with the NCD-fed animals, P16INK4a and P38 MAPK gene expression were up-regulated in the HCD-fed animals; also, Bmi-1 gene expression was down-regulated (P < 0.05). BM-MSCs from vitamin D-treated rats (second phase) exhibited reduced mRNA levels of P16INK4a and P38 MAPK genes and increased Bmi-1 mRNA levels (all P < 0.05). Vitamin D prescription also declined the percentage of SA-β-gal-positive cells, ROS levels, and the cells in the G1 phase and increased the cells in the S phase in both NCD and HCD-fed animals (P < 0.05). The reduction of the cells in the G2 phase in rats fed with an NCD plus vitamin D was statistically non-significant (P = 0.128) and significant in HCD plus vitamin D rats (P = 0.002). HCD accelerates BM-MSCs senescence, and vitamin D reduces BM-MSCs senescence biomarkers.

Vitamin D as a Shield against Aging

Aging can be seen as a physiological progression of biomolecular damage and the accumulation of defective cellular components, which trigger and amplify the process, toward whole-body function weakening. Senescence initiates at the cellular level and consists in an inability to maintain homeostasis, characterized by the overexpression/aberrant expression of inflammatory/immune/stress responses. Aging is associated with significant modifications in immune system cells, toward a decline in immunosurveillance, which, in turn, leads to chronic elevation of inflammation/oxidative stress, increasing the risk of (co)morbidities. Albeit aging is a natural and unavoidable process, it can be regulated by some factors, like lifestyle and diet. Nutrition, indeed, tackles the mechanisms underlying molecular/cellular aging. Many micronutrients, i.e., vitamins and elements, can impact cell function. This review focuses on the role exerted by vitamin D in geroprotection, based on its ability to shape cellular/intracellular processes and drive the immune response toward immune protection against infections and age-related diseases. To this aim, the main biomolecular paths underlying immunosenescence and inflammaging are identified as biotargets of vitamin D. Topics such as heart and skeletal muscle cell function/dysfunction, depending on vitamin D status, are addressed, with comments on hypovitaminosis D correction by food and supplementation. Albeit research has progressed, still limitations exist in translating knowledge into clinical practice, making it necessary to focus attention on the role of vitamin D in aging, especially considering the growing number of older individuals.

Aging affects the biological activity of fibroblast growth factor (FGF) in gastric epithelial cell, which is partially rescued by uridine

Aging has become an irreversible trend in the world, the health problems caused by aging cannot be ignored. The physiological functions of human body begin to decline with aging, the decline of gastrointestinal function caused by aging is an important problem that needs to be resolved. In this work, we evaluated the anti-aging effect of uridine in the senescent gastric epithelial cell model, and found that the aging level of gastric epithelial cell was significantly down-regulated by uridine treatment, uridine could obviously down-regulate the ratio of the SA-β-gal-positive senescent cells. Furthermore, aging-related marker molecules (such as p16 and p21) were also significantly down-regulated under uridine treatment. Additionally, the levels of inflammation and oxidative stress were also significantly reduced by uridine treatment. Next, our further studies the effect of aging on FGF activity on gastric epithelial cell, and found that FGF/FGFR-mediated signaling pathways were significantly down-regulated. However, uridine treatment can not only alleviate the senescence of gastric epithelial cell, but also can partially restore the sensitivity of FGF signaling. Taken together, the current work indicates that uridine shows a good anti-aging effect, which lays a solid foundation for the related research in this filed.

Uric acid, as a double-edged sword, affects the activity of epidermal growth factor (EGF) on human umbilical vein endothelial cells by regulating aging process

Uric acid (UA) is the main metabolite of the human body. Although UA is only a product of metabolism, it is important biological regulator. Epidermal growth factor (EGF) has important biological functions. However, so far, the effect of UA on EGF’s activity has not been revealed. For this, in the current study, we systematically studied the effect of OA on the biological activity of EGF. Human Umbilical Vein Endothelial Cells (HUVECs) were used as an in vitro model, and Western-blot, RT-PCR, laser scanning confocal microscopy (CLSM) and co-localization analyses were carried out. The results showed that high concentration of UA (10 mg/dl) severely affected the biological activity of EGF. High concentration of UA suppressed the activity of EGF, and inhibited the biological effect of EGF on the HUVECs. However, it is interesting that EGF-mediated intracellular signaling was significantly down-regulated in the H₂O₂-induced senescent HUVEC, and physiological concentration of UA could at least partially restore the EGF-mediated signaling. Further work showed that physiological concentration of UA (5 mg/dl) shows the anti-aging effect. Taken together, current research indicates that UA may be a ‘double-edged sword’, physiological concentration of UA may be beneficial, but high concentrations of uric acid (UA) are harmful.