Adipose tissue and vitamin D

Obesity and a low vitamin D (VD) status, as well as a positive association between them, are prevalent worldwide. Additionally, a low VD status has been positively correlated with metabolic dysfunction (although not so convincingly as for obesity). The VD receptor (VDR) mediates VD biological actions in adipose tissue (AT), where VD can be activated or inactivated/degraded through specific hydroxylation steps. Additionally, AT can also store and release VD when needed. A lower VD activation/VD inactivation ratio and an impaired VDR signaling in AT could contribute to metabolic dysfunction besides the aforementioned association between obesity and VD status...

Obesity is recognized as a state of chronic low-grade systemic inflammation due to adipose tissue macrophage infiltration and production of proinflammatory adipokines. Decreased vitamin D status is associated with obesity. The specific aim of the present study is to investigate the effects of vitamin D on obesity-induced adipose tissue inflammation. Male Sprague-Dawley rats were randomized and fed a normal diet (NOR, 1000 IU vitamin D/kg diet), a 45% high-fat diet (HF, 1000 IU vitamin D/kg diet), or a 45% high-fat diet containing 25 IU vitamin D/kg diet (HF+LVD) for 12 weeks...

Age-associated decline in muscle function represents a significant public health burden. Vitamin D-deficiency is also prevalent in aging subjects, and has been linked to loss of muscle mass and strength (sarcopenia), but the precise role of specific vitamin D metabolites in determining muscle phenotype and function is still unclear. To address this we quantified serum concentrations of multiple vitamin D metabolites, and assessed the impact of these metabolites on body composition/muscle function parameters, and muscle biopsy gene expression in a retrospective study of a cohort of healthy volunteers...

Context: Vitamin D accumulates in adipose tissue (AT), and vitamin D deficiency is frequent in obesity. Objective: We hypothesize that trafficking of vitamin D is altered in dysfunctional AT. Design, Patients, Settings: Fifty-four normal-weight and 67 obese males were recruited in a prospective study and randomly assigned to supplementation with 50 µg/wk 25-hydroxyvitamin-D3 or 150 µg/wk vitamin D3 for 1 year, raising dosage by 50% if vitamin D sufficiency [serum 25-hydroxyvitamin-D3 >50 nmol/L], was not achieved at 6 months; 97 subjects completed the study...

Inflammation of adipose tissue is believed to be a contributing factor to many chronic diseases associated with obesity. Vitamin D (VD) is now known to limit this metabolic inflammation by decreasing inflammatory marker expression and leukocyte infiltration in adipose tissue. In this study, we investigated the impact of VD on microRNA (miR) expression in inflammatory conditions in human and mouse adipocytes, using high-throughput methodology (miRNA PCR arrays). Firstly, we identified three miRs (miR-146a, miR-150, and miR-155) positively regulated by TNFα in human adipocytes...

In recent years, attention has been focused on pleiotropic directions of effects exerted by vitamin D. Epidemiological data indicate that deficiency of vitamin D in various population groups represents an increasingly widespread phenomenon, while a decreased serum concentration of calcitriol correlates with manifestation of civilization-linked diseases, including visceral obesity. This study aims at a review and synthesis of data linked to relationships between lowered vitamin D concentrations in blood and manifestation of obesity, and potential mechanisms which affect the concentration of the vitamin in conditions of an excessive accumulation of adipose tissue...

Vitamin D related research continues to expand and theorise regarding its involvement in obesity, as both hypovitaminosis D and obesity strike in pandemic proportions. Vitamin D plays an important role in immune system through Vitamin D Receptors (VDR), which are transcription factors located abundantly in the body. Due to this characteristic, it is potentially linked to obesity, which is a state of inflammation involving the release of cytokines from adipose tissue, and exerting stress on other organs in a state of positive energy balance...

Adipose tissue has long been identified as the major site of vitamin D storage. Recent studies have demonstrated that VDR and vitamin D metabolizing enzymes are expressed in adipocytes. Furthermore, it has been shown that vitamin D regulates adipogenic gene expression as well as adipocyte apoptosis. Vitamin D is active in adipocytes at all levels. It interacts with membrane receptors, adaptor molecules, and nuclear coregulator proteins. Several functions of unliganded nVDR were discovered by studying human samples from patients having hereditary vitamin D resistant rickets, transgenic mice overexpressing the VDR and VDR knockout mice...

BACKGROUND: Vitamin D, a hormone once thought to have a role limited to calcium homeostasis and bone mineralization, has pleiotropic effects on different types of cells. Vitamin D receptors are reported in vascular smooth muscle cells, endothelial cells, and cardiomyocytes. Adipose-derived MSCs (ADMSCs) are multipotent cells with the capacity to differentiate into cells of different lineages. To our knowledge, the presence of vitamin D machinery on porcine ADMSCs has not yet been examined...

PURPOSE OF REVIEW: Low vitamin D levels have been extensively reported in obesity. Thus, the pandemic of obesity has been paralleled by a high prevalence of low vitamin D status. Given the well documented associations linking poor vitamin D status to adverse health outcomes (diabetes, cardiovascular disease, cancers, all-cause mortality), a proper understanding of the mechanisms linking excess adiposity to low vitamin D status is key to identify and implement effective interventions to replenish vitamin D levels in obese individuals...

Although vitamin D deficiency is prevalent among obese individuals, its cause is poorly understood. Few studies have measured vitamin D concentrations in adipose of obese (OB) subjects, and none have included normal weight controls (C). The goal of this study was to investigate whether the relationship between body composition, serum 25-hydroxyvitamin D (25OHD), vitamin D in subcutaneous (SQ) and omental (OM) adipose, and total adipose stores of vitamin D differ among OB and C. Obese women undergoing bariatric surgery and normal-weight women undergoing abdominal surgery for benign gynecologic conditions were enrolled...

Vitamin D is a fat-soluble vitamin and a steroid hormone that plays a central role in maintaining calcium-phosphorus and bone homeostasis in close interaction with parathyroid hormone, acting on its classical target tissues, namely, bone, kidney, intestine, and parathyroid glands. However, vitamin D endocrine system regulates several genes (about 3 % of the human genome) involved in cell differentiation, cell-cycle control, and cell function and exerts noncalcemic/pleiotropic effects on extraskeletal target tissues, such as immune and cardiovascular system, pancreatic endocrine cells, muscle, and adipose tissue...

Vitamin D (VitD), a lipid-soluble hormone, is able to regulate the transcription of many genes through vitamin D receptor (vitD receptor-VDR). It has been shown that VitD deficiency is associated with obesity, characterized by a low degree inflammatory state, which contribute to the pathogeny of metabolic syndrome and type 2 diabetes mellitus. VitD deficiency is a public health problem, at the same time the global prevalence of obesity and cardiovascular diseases is continuously growing. Evidence from recent studies on animal models suggest that VitD or VDR deficiency promotes cardiomyocyte hypertrophy, which can be one of the mechanisms for increasing cardiovascular risk...

Rats overfed during lactation show higher visceral adipose tissue (VAT) mass and metabolic dysfunctions at adulthood. As both vitamin D and glucocorticoids change adipogenesis, parameters related to metabolism and action of these hormones in the adipocyte can be altered in rats raised in small litters (SL). We also studied the antiobesity effects of high calcium diet since it decreases visceral fat in obesity models. On postnatal day (PN) 3, litter size was adjusted to 3pups/dam (SL) to induce overfeeding. Control litters (NL) remained with 10pups/dam until weaning...

UNLABELLED: After a single cholecalciferol load, peak serum 25-hydroxycholecalciferol (25OHD) is lower in individuals with a higher body mass index (BMI), probably due to it being distributed in a greater volume. Its subsequent disappearance from the serum is slower the higher the individual's BMI, probably due to the combination of a larger body volume and a slower release into the circulation of vitamin D stored in adipose tissue. INTRODUCTION: The aim of the study is to examine 25-hydroxycholecalciferol (25OHD) response to a single oral load of cholecalciferol in the normal weight, overweight, and obese...

OBJECTIVE: Previous studies suggest that low vitamin D status is associated with obesity characterized by excess lipid storage in adipocytes. The aim of the present study was to determine the effects of the most hormonally active form of vitamin D 1,25-dihydroxyvitamin D [1,25(OH)2D] on adipocyte fat storage and lipid metabolism in mature 3T3-L1 cells. METHODS: Differentiated 3T3-L1 cells were treated with various concentrations of 1,25(OH)2D. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell proliferation, intracellular lipid content, and basal and isoproterenol-stimulated lipolysis were measured to investigate the regulatory role of 1,25(OH)2D in adipocyte lipid metabolism...

SCOPE: Early weaning (EW) is associated with an impairment of offspring development and leads to overweight and higher 25-hydroxyvitamin D (25(OH)D) levels in adulthood, which can be corrected by calcium supplementation, potentially via vitamin D regulation of adipogenesis. METHODS AND RESULTS: We examined vitamin D status in adipose tissue in EW obese rats, treated with calcium. Dams were separated into: EW- dams were wrapped with a bandage to interrupt lactation (last 3 days), and C- pups with free access to milk...

Fatty acids (FAs) are a major energy source in the body. White adipose tissue (WAT) is a primary site where FAs are stored as triacylglycerols. Brown adipose tissue also stores and recruits FAs as a carbon source for uncoupled β-oxidation during thermogenesis. The deletion of the vitamin D nuclear hormone receptor (VDR) gene in mice (VDRKO) results in a lean WAT phenotype with increased levels of expression of the brown adipose tissue marker Ucp1 in the WAT. However, the impact of vitamin D/VDR on FA composition in WAT has not been explored in detail...

Cross-sectional studies depict an inverse relationship between vitamin D (VD) status reflected by plasma 25-hydroxy-vitamin D and obesity. Furthermore, recent studies in vitro and in animal models tend to demonstrate an impact of VD and VD receptor on adipose tissue and adipocyte biology, pointing to at least a part-causal role of VD insufficiency in obesity and associated physiopathological disorders such as adipose tissue inflammation and subsequent insulin resistance. However, clinical and genetic studies are far less convincing, with highly contrasted results ruling out solid conclusions for the moment...

CONTEXT: Both vitamin D deficiency and inflammation have been associated with insulin resistance and type 2 diabetes risk. In vitro vitamin D treatment of subcutaneous (SC) adipose tissue (AT) may reduce inflammation, but data are conflicting. OBJECTIVES: To evaluate the effects of vitamin D (25(OH)D3 and 1,25(OH)2D3) on the secretion of inflammatory cytokines (TNF-α and IL-6) in omental (OM) and SC human AT and to explore factors that could correlate with the individual response to vitamin D including age, smoking status, BMI, comorbidities, medication, HbA1c, apolipoprotein B, serum 25-hydroxyvitamin D and high sensitivity C-reactive protein...