Crosstalk between sphingolipids and vitamin D3: potential role in the nervous system

Effect of Sphingomyelin and Vitamin D3 Intake on the Rabbit Brain

Sphingomyelin is a crucial molecule in the sphingolipid metabolic pathway, and its action is closely related to that of vitamin D3. Both molecules are recognized for their involvement in brain pathophysiology. In this study, the effect of a sphingomyelin + vitamin D3-enriched diet was investigated in rabbits. The results showed a strong immunopositive GFAP staining in the brain's white matter. Furthermore, a remodeling of the balance between glycero-phospholipids and ether-phospholipids was observed in the brain, along with an increase in ceramides and hexose ceramides, molecules relevant for the structure, function, and stability of myelin. Taken together, these findings provide clues as to how the combination sphingomyelin + vitamin D3 may play a vital role in normal brain physiology and could potentially be leveraged in the context of neurodegenerative diseases.

Ceramide in Coronary Artery Disease: Troublesome or Helpful Future Tools in the Assessment of Risk Prediction and Therapy Effectiveness?

Lipids are a complex entity of different molecules, among which ceramides (Cers), ubiquitous sphingolipids with remarkable biological activity, can represent a potential additive biomarker that can be used to better understand the underlying mechanisms which drive the onset and development of atherosclerotic damage and plaque vulnerability and facilitate coronary disease management, as possible risk/prognostic biomarkers and targets for therapeutic intervention. Accordingly, this review aims to discuss the available results on the role Cersplay in contributing to atherosclerosis development and acute coronary event precipitation, their impact on complications and adverse prognosis, as well as the impact of treatment options in modulating Cerlevels.

Pharmacokinetic modeling of prenatal vitamin D exposure and the impact on offspring asthma and pulmonary function

Gestational 25-hydroxyvitamin D (25[OH]D) is important in fetal lung development and may influence offspring respiratory outcomes, making accurate exposure assessment essential to understand clinical associations. Therefore, we used the combined data from two large RCTs investigating prenatal vitamin D supplementation, which included early and late prenatal 25(OH)D measurements, to refine a population pharmacokinetic model of vitamin D-25(OH)D and estimate individual area under the curve (AUC) Z-scores. The primary outcome was physician-diagnosed offspring asthma/wheezing at ages 3 and 6 years, and lung function, as a secondary outcome, was evaluated by spirometry at the ages 6 and 8 years. In total, 1319 mother-child pairs were included. We found that clearance of 25(OH)D increased with gestational age and bodyweight, and decreased with higher baseline 25(OH)D levels. Prenatal 25(OH)D AUC Z-scores were negatively associated with asthma/wheezing at age 3 years (aOR = 0.75, 95 % CI = 0.64-0.88, p < 0.001) and 6 years (aOR = 0.83, 95 % CI = 0.72-0.95, p = 0.008). Longitudinal analysis of lung function from age 6-8 years showed that AUC Z-scores were positively associated with percent-predicted FEV1 (β = 1.21%, 95 % CI = 0.30-2.11; p = 0.009), FVC (β = 0.79 %, 95 % CI = 0.13-1.46; p = 0.021), FEV1/FVC ratio (β = 0.56 %, 95 % CI = 0.11-1.01; p = 0.015) and FEF25-75 % (β = 2.18 %, 95 % CI = 0.46-3.91; p = 0.009). These results together indicate an exposure-outcome relationship where higher gestational 25(OH)D exposure, estimated by AUC, is associated with reduced childhood asthma/recurrent wheeze and improved lung function.

Vitamin D and Ceramide Metabolomic Profile in Acute Myocardial Infarction

Sphingolipids (SLs) influence several cellular pathways, while vitamin D exerts many extraskeletal effects in addition to its traditional biological functions, including the modulation of calcium homeostasis and bone health. Moreover, Vitamin D and SLs affect the regulation of each others' metabolism; hence, this study aims to evaluate the relationship between the levels of 25(OH)D and ceramides in acute myocardial infarction (AMI). In particular, the blood abundance of eight ceramides and 25(OH)D was evaluated in 134 AMI patients (aged 68.4 ± 12.0 years, 72% males). A significant inverse correlation between 25(OH)D and both Cer(d18:1/16:0) and Cer(d18:1/18:0) was found; indeed, patients with severe hypovitaminosis D (<10 ng/mL) showed the highest levels of the two investigated ceramides. Moreover, diabetic/dyslipidemic patients with suboptimal levels of 25(OH)D (<30 ng/mL) had higher levels of both the ceramides when compared with the rest of the population. On the other hand, 25(OH)D remained an independent determinant for Cer(d18:1/16:0) (STD Coeff -0.18, t-Value -2, p ≤ 0.05) and Cer(d18:1/18:0) (-0.2, -2.2, p < 0.05). In light of these findings, the crosstalk between sphingolipids and vitamin D may unravel additional mechanisms by which these molecules can influence CV risk in AMI.

Interplay between Vitamin D and Sphingolipids in Cardiometabolic Diseases

Sphingolipids (SLs) are structural, bioactive molecules with several key cellular roles, whereas 1,25-dihydroxyvitamin D (1,25(OH)D), the active form of vitamin D, is considered the major regulator of calcium homeostasis, although it also exerts other extraskeletal effects. Many studies reported the physiological connection between vitamin D and SLs, highlighting not only the effects of vitamin D on SL metabolism and signaling but also the influence of SLs on vitamin D levels and function, thus strongly suggesting a crosstalk between these molecules. After a brief description of 1,25(OH)D and SL metabolism, this review aims to discuss the preclinical and clinical evidence on the crosstalk between SLs and 1,25(OH)D, with a special focus on cardiometabolic diseases.

Maternal 17q21 genotype influences prenatal vitamin D effects on offspring asthma/recurrent wheeze

BACKGROUND

Prenatal vitamin D3 supplementation has been linked to reduced risk of early-life asthma/recurrent wheeze. This protective effect appears to be influenced by variations in the 17q21 functional single nucleotide polymorphism rs12936231 of the child, which regulates the expression of ORMDL3 (ORM1-like 3) and for which the high-risk CC genotype is associated with early-onset asthma. However, this does not fully explain the differential effects of supplementation. We investigated the influence of maternal rs12936231 genotype variation on the protective effect of prenatal vitamin D3 supplementation against offspring asthma/recurrent wheeze.

METHODS

We determined the rs12936231 genotype of mother-child pairs from two randomised controlled trials: the Vitamin D Antenatal Asthma Reduction Trial (VDAART, n=613) and the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC2010, n=563), to examine the effect of maternal genotype variation on offspring asthma/recurrent wheeze at age 0-3 years between groups who received high-dose prenatal vitamin D3 supplementation versus placebo.

RESULTS

Offspring of mothers with the low-risk GG or GC genotype who received high-dose vitamin D3 supplementation had a significantly reduced risk of asthma/recurrent wheeze when compared with the placebo group (hazard ratio (HR) 0.54, 95% CI 0.37-0.77; p<0.001 for VDAART and HR 0.56, 95% CI 0.35-0.92; p=0.021 for COPSAC2010), whereas no difference was observed among the offspring of mothers with the high-risk CC genotype (HR 1.05, 95% CI 0.61-1.84; p=0.853 for VDAART and HR 1.11, 95% CI 0.54-2.28; p=0.785 for COPSAC2010).

CONCLUSION

Maternal 17q21 genotype has an important influence on the protective effects of prenatal vitamin D3 supplementation against offspring asthma/recurrent wheeze.

Vitamin D3 Enriches Ceramide Content in Exosomes Released by Embryonic Hippocampal Cells

The release of exosomes can lead to cell–cell communication. Nutrients such as vitamin D3 and sphingolipids have important roles in many cellular functions, including proliferation, differentiation, senescence, and cancer. However, the specific composition of sphingolipids in exosomes and their changes induced by vitamin D3 treatment have not been elucidated. Here, we initially observed neutral sphingomyelinase and vitamin D receptors in exosomes released from HN9.10 embryonic hippocampal cells. Using ultrafast liquid chromatography tandem mass spectrometry, we showed that exosomes are rich in sphingomyelin species compared to whole cells. To interrogate the possible functions of vitamin D3, we established the optimal conditions of cell treatment and we analyzed exosome composition. Vitamin D3 was identified as responsible for the vitamin D receptor loss, for the increase in neutral sphingomyelinase content and sphingomyelin changes. As a consequence, the generation of ceramide upon vitamin D3 treatment was evident. Incubation of the cells with neutral sphingomyelinase, or the same concentration of ceramide produced in exosomes was necessary and sufficient to stimulate embryonic hippocampal cell differentiation, as vitamin D3. This is the first time that exosome ceramide is interrogated for mediate the effect of vitamin D3 in inducing cell differentiation.

S1P/S1P Receptor Signaling in Neuromuscolar Disorders

The bioactive sphingolipid metabolite, sphingosine 1-phosphate (S1P), and the signaling pathways triggered by its binding to specific G protein-coupled receptors play a critical regulatory role in many pathophysiological processes, including skeletal muscle and nervous system degeneration. The signaling transduced by S1P binding appears to be much more complex than previously thought, with important implications for clinical applications and for personalized medicine. In particular, the understanding of S1P/S1P receptor signaling functions in specific compartmentalized locations of the cell is worthy of being better investigated, because in various circumstances it might be crucial for the development or/and the progression of neuromuscular diseases, such as Charcot-Marie-Tooth disease, myasthenia gravis, and Duchenne muscular dystrophy.

A Role for Neutral Sphingomyelinase in Wound Healing Induced by Keratinocyte Proliferation upon 1α, 25-Dihydroxyvitamin D3 Treatment

The skin has many functions, such as providing a barrier against injury and pathogens, protecting from ultraviolet light, and regulating body temperature. Mechanical causes and many different pathologies can lead to skin damage. Therefore, it is important for the skin to be always adaptable and renewable and for cells to undergo proliferation. Here, we demonstrate that 1α, 25-dihydroxyvitamin D₃ (VD3) stimulates keratinocyte proliferation, leading to wound closure in a simulation model of injury. Functionally, our results show that VD3 acts by stimulating cyclin D1, a cyclin that promotes the G1/S transition of the cell cycle. The study on the mechanism underlying cyclin D1 expression upon VD3 stimulation clearly demonstrates a key role of neutral sphingomyelinase. The enzyme, whose gene and protein expression is stimulated by VD3, is itself able to induce effects on cyclin D1 and wound healing similar to those obtained with VD3. These results could be very useful in the future to better understand wound mechanisms and improve therapeutic interventions.

Vitamin D effects on sphingosine 1-phosphate signaling and metabolism in monocytes from type 2 diabetes patients and controls

Elevated sphingosine 1-phopshate (S1P) concentration was observed in type 2 diabetes mellitus (T2D). On the other side, 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) can influence the formation of sphingosine 1-phopshate (S1P) and the expression of S1P receptors, which are known to be involved in T2D. In order to evaluate mechanisms for the antiinflammatory potential of 1,25(OH)₂D₃, we investigated whether 1,25(OH)₂D₃ alters S1P signaling and metabolism in human CD14⁺ monocytes. Primary monocytes isolated from healthy controls (HC) and T2D patients were treated for 24 h with 10 nM 1,25(OH)₂D₃ in the absence or presence of 500 IU/ml interleukin-(IL)-1β. Thereafter, sphingosine kinase (SPHK)1, SPHK2 and S1P receptor 1-5 (S1P_1-5) mRNA expression levels were measured by TaqMan^™ analyses. Sphingolipid levels in cell supernatant were determined by high-performance liquid chromatography/tandem mass spectrometry (LC-MS/MS). 1,25(OH)₂D₃ treatment downregulated S1P₁ and S1P₂ mRNA expression compared to untreated monocytes of HC and T2D patients. In contrast, SPHK1, S1P₃ and S1P₄ mRNA expression levels were upregulated by 1,25(OH)₂D₃ treatment compared to the respective controls. Furthermore, reduced S1P₂ and increased S1P₃ and S1P₄ mRNA expression levels upon treatment with 1,25(OH)₂D₃ occurred in the presence of IL-1β. Additionally, S1P levels in cell supernatants were decreased in monocytes from HC and T2D patients by 1,25(OH)₂D₃ with or without IL-1β costimulation. The levels of sphingosine in cell supernatants were not influenced by 1,25(OH)₂D_3. Overall, our results demonstrate for the first time that 1,25(OH)₂D₃ treatment can influence S1P receptor and SPHK expression and S1P levels in primary monocytes of both HC and subjects with T2D. These findings justify further investigations into the sphingolipid metabolism and potential benefits of vitamin D treatment in diabetes.

Yeast membrane lipid imbalance leads to trafficking defects toward the Golgi

Protein recycling is an essential cellular process involving endocytosis, intracellular trafficking, and exocytosis. In mammalian systems membrane lipids, including cholesterol, sphingolipids, and phospholipids, play a pivotal role in protein recycling. To address this role in budding yeast, Saccharomyces cerevisiae, we utilized GFP-Snc1, a v-SNARE protein serving as a fluorescent marker for faithfully reporting the recycling pathway. Here we demonstrate results that display moderate to significant GFP-Snc1 recycling defects upon overexpression or inactivation of phospholipid, ergosterol, and sphingolipid biosynthesis enzymes, indicating that the homeostasis of membrane lipid levels is prerequisite for proper protein recycling. By using a truncated version of GFP-Snc1 that cannot be recycled from the plasma membrane, we determined that abnormalities in Snc1 localization in membrane lipid overexpression or underexpression mutants are not due to defects in the synthetic/secretory pathway, but rather in the intracellular trafficking pathway. We found that membrane lipid imbalance resulted in an accumulation of the late endosome marker Vps10-GFP, indicating trafficking from the endosomes to the Golgi may be being hindered, preventing recycling to the plasma membrane. To elucidate the possible mechanism for this trafficking hindrance, we stained the actin cytoskeleton, then quantified the percentage of cells with visible actin cables. Compared to wild-type cells, membrane lipid mutant cells exhibited lower levels of actin cables, indicating the actin cytoskeleton is disrupted upon membrane lipid imbalance. Taken together, our results show that impairment of proper recycling may be due to disruption of the actin cytoskeleton, which causes trafficking hindrance between the endosomes and Golgi.

The investigation of immunoprotective and sedative hypnotic effect of total polysaccharide from Suanzaoren decoction by serum metabonomics approach

Suanzaoren decoction, as one of the traditional Chinese medicine prescriptions, has been most commonly used in Asian countries and reported to inhibit the process of immunodeficiency insomnia. Polysaccharide is important component which also contributes to the role of immunoprotective and sedative hypnotic effects. This study was aimed to explore the immunoprotective and sedative hypnotic mechanisms of polysaccharide from Suanzaoren decoction by serum metabonomics approach. With this purpose, complex physical and chemical immunodeficiency insomnia models were firstly established according to its multi-target property. Serum samples were analyzed using UHPLC/Q-TOF-MS spectrometry approach to determine endogenous metabolites. Then, principal component analysis was used to distinguish the groups, and partial least squares discriminate analysis was carried out to confirm the important variables. The serum metabolic profiling was identified and pathway analysis was performed after the total polysaccharide administration. The twenty-one potential biomarkers were screened, and the levels were all reversed to different degrees in the total polysaccharide treated groups. These potential biomarkers were mainly related to vitamin, sphingolipid, bile acid, phospholipid and acylcarnitine metabolisms. The result has indicated that total polysaccharide could inhibit insomnia triggered by immunodeficiency stimulation through regulating those metabolic pathways. This study provides a useful approach for exploring the mechanism and evaluating the efficacy of total polysaccharide from Suanzaoren decoction.

Crosstalk between sphingolipids and vitamin D3: potential role in the nervous system

Sphingolipids are both structural and bioactive compounds. In particular, ceramide and sphingosine 1-phosphate regulate cell fate, inflammation and excitability. 1-α,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ) is known to play an important physiological role in growth and differentiation in a variety of cell types, including neural cells, through genomic actions mediated by its specific receptor, and non-genomic effects that result in the activation of specific signalling pathways. 1,25(OH)2 D3 and sphingolipids, in particular sphingosine 1-phosphate, share many common effectors, including calcium regulation, growth factors and inflammatory cytokines, but it is still not known whether they can act synergistically. Alterations in the signalling and concentrations of sphingolipids and 1,25(OH)2 D3 have been found in neurodegenerative diseases and fingolimod, a structural analogue of sphingosine, has been approved for the treatment of multiple sclerosis. This review, after a brief description of the role of sphingolipids and 1,25(OH)2 D3 , will focus on the potential crosstalk between sphingolipids and 1,25(OH)2 D3 in neural cells.