维生素D与脑发育相关研究进展

近年来有关维生素D研究进展迅速,其中维生素D与大脑的发育之间的关系日益受到关注。维生素D是一种具有类固醇激素作用的物质,可参与调节细胞増殖、分化及凋亡,大量研究表明,维生素D除了具有促进钙磷吸收、骨骼发育及发挥免疫调节的作用,还可作为一类神经激素影响神经系统的发育和功能,本文将从大脑中的维生素D及维生素D受体、维生素D对脑发育可能的调控作用及维生素D与儿童神经精神障碍疾病的相关性等几方面进行阐述。     

孕期鼠补充维生素D对子鼠胸腺维生素D受体表达

目的 研究给予母孕期大鼠补充不同剂量维生素D,检测子代鼠胸腺中VDR表达变化。方法 健康雌性Wistar大鼠18只,雄性Wistar大鼠9只,以每日晚间17时将雌鼠、雄鼠按2∶1合笼,次日8时对雌鼠阴道分泌物涂片,在40倍光学显微镜检查到精子表示受孕,记为妊娠0 d( gestational day 0,GD0) 。将孕鼠随机入对照组、维生素D低剂量、维生素D高剂量组。于GD 15 d起对照组每日给予肌肉注射生理盐水0.25 ml/(kg·次),低剂量组给予肌肉注射维生素D 20 μg/kg,高剂量组给予肌肉注射维生素D 100 μg/kg,直至子鼠娩出。子鼠哺乳21 d后分离子鼠胸腺,Real-time PCR检测VDRmRNA表达水平,Western blot检测VDR蛋白表达水平。结果 通过Real-tine PCR分析仔鼠胸腺VDR基因表达三组之间差异无统计学意义(P＞0.05)。Western blot检测VDR蛋白水平的表达显示,低剂量及高剂量组VDR蛋白的表达量均高于对照组,三组之间差异存在统计学意义(P＜0.05)。结论 给予母鼠补充维生素D,其仔鼠胸腺VDR蛋白表达量明显增加,与维生素D补充量呈正相关。     

维生素D受体在肠道肿瘤生长中与β-catenin通路之间的关系

目的探讨维生素D受体（VDR）对肠道肿瘤生长的影响以及与β-catenin信号通路之间的关系。方法体外培养的人类结肠癌SW480细胞株经维生素D处理4h,免疫沉淀法检测VDR和t3-catenin蛋白的交互作用,24h后用Westernblot检测细胞E．cadherin蛋白的表达。体内实验比较APCmin／＋VDR-／-与APCmin／＋小鼠,免疫组化法检测两型小鼠肠道肿瘤VDR、β-catenin和Brdu蛋白的表达,Westernblot检测肿瘤和肿瘤旁组织β-catenin蛋白的表达。结果维生素D处理SW480细胞后,VDR和β-catenin蛋白相互结合,随后E-cadherin蛋白表达增高（对照组灰度值145．57±4．21,实验组109．35±3．56,t=32．63,P〈0．05）。缺失VDR的APCmin／＋VDR-／-小鼠肠道肿瘤中β-catenin蛋白表达免疫组化（灰度值140．51±2．57）及Westemblot（灰度值166．47±2．36）检测均高于APCmin／＋肿瘤（分别为145．41±3．62、182．35±3．24,t=2．65,4．36,P〈0．05）。结论维生素D抑制肠道肿瘤增殖的作用可能通过VDR影响β-catenin信号通路来完成。     

Use of a Loading Dose of Vitamin D for Treatment of Vitamin D Deficiency in Patients With Intestinal Failure

Vitamin D deficiency is common in patients with intestinal failure and short bowel syndrome who have been weaned of parenteral nutrition. Dietary supplementation with vitamin D is necessary to correct this deficiency. In certain cases, routine supplementation strategy may be ineffective. We report 3 cases of vitamin D deficiency in patients with intestinal failure who showed improvement in serum 25‐hydroxyvitamin D levels after supplementation with a loading dose of 20,000–40,000 IU vitamin D provided weekly.     

Vitamin D and Crohn's Disease in the Adult Patient

Crohn's disease (CD) is characterized as a chronic immune‐mediated inflammatory disorder of the gastrointestinal tract. Current consensus surrounding the cause of the disease suggests a complex interplay between genetic susceptibility, the intestinal microbiome and environmental factors, leading to the aberrant Th1 and Th17 immune cell mediated response. Vitamin D deficiency is common in CD patients, and long‐standing deficiency has been associated with reduced bone mineral density (BMD). Accumulating evidence now suggests that in addition to maintaining skeletal integrity, vitamin D also plays an integral role in regulating the general immune response, a function employed via its genomic actions on the vitamin D receptor (VDR). The VDR is expressed in all immune cells and both directly and indirectly targeted by the bioactive form of vitamin D, 1,25‐Dihydroxyvitamin D (1,25[OH]₂D). Impaired regulation or deficiency of the vitamin has been linked to the promotion of self‐reactive T cell development, loss of immune tolerance to self‐structures, and experimental colitis in animal models, whereas the subsequent administration of the vitamin in these models resulted in the improvement of immune‐mediated symptoms. In addition, low vitamin D has been associated with disease activity in CD patients, and supplementation appears to be beneficial in improving clinical scores and reducing inflammation. Therefore, the primary aims of this article were to review the molecular evidence supporting the immunoregulatory roles of vitamin D and its supplementation in the CD patient, based on existing literature. The physiological processes, accepted serum concentration values, and its well‐recognized role in bone health were also summarized.     

Inhibition of Antiestrogen-Promoted Pro-Survival Autophagy and Tamoxifen Resistance in Breast Cancer through Vitamin D Receptor

We determined how vitamin D receptor (VDR) is linked to disease outcome in estrogen receptor-positive (ER+) breast cancer patients treated with tamoxifen (TAM). Breast cancer patients (n = 581) in four different datasets were divided into those expressing higher (above median) and lower levels of VDR in pretreatment ER+ tumors. Across all datasets, TAM-treated patients with higher pretreatment tumor VDR expression exhibited significantly longer recurrence-free survival. Ingenuity pathway analysis identified autophagy and unfolded protein response (UPR) as top differentially expressed pathways between high and low VDR-expressing ER+ cancers. Activation of VDR with vitamin D (VitD), either calcitriol or its synthetic analog EB1089, sensitized MCF-7-derived, antiestrogen-resistant LCC9 human breast cancer cells to TAM, and attenuated increased UPR and pro-survival autophagy. Silencing of VDR blocked these effects through the IRE1α-JNK pathway. Further, silencing of VDR impaired sensitivity to TAM in antiestrogen-responsive LCC1 cells, and prevented the effects of calcitriol and EB1089 on UPR and autophagy. In a preclinical mouse model, dietary VitD supplementation induced VDR activation and reduced carcinogen-induced ER+ mammary tumor incidence. In addition, IRE1α-JNK signaling was downregulated and survival autophagy was inhibited in mammary tumors of VitD-supplemented mice. Thus, activation of VDR is predictive of reduced risk of breast cancer recurrence in ER+ patients, possibly by inhibiting antiestrogen-promoted pro-survival autophagy.     

A Novel Role for a Major Component of the Vitamin D Axis: Vitamin D Binding Protein-Derived Macrophage Activating Factor Induces Human Breast Cancer Cell Apoptosis through Stimulation of Macrophages

The role of vitamin D in maintaining health appears greater than originally thought, and the concept of the vitamin D axis underlines the complexity of the biological events controlled by biologically active vitamin D (1,25(OH)(2)D3), its two binding proteins that are the vitamin D receptor (VDR) and the vitamin D-binding protein-derived macrophage activating factor (GcMAF). In this study we demonstrate that GcMAF stimulates macrophages, which in turn attack human breast cancer cells, induce their apoptosis and eventually phagocytize them. These results are consistent with the observation that macrophages infiltrated implanted tumors in mice after GcMAF injections. In addition, we hypothesize that the last 23 hydrophobic amino acids of VDR, located at the inner part of the plasma membrane, interact with the first 23 hydrophobic amino acids of the GcMAF located at the external part of the plasma membrane. This al1ows 1,25(OH)(2)D3 and oleic acid to become sandwiched between the two vitamin D-binding proteins, thus postulating a novel molecular mode of interaction between GcMAF and VDR. Taken together, these results support and reinforce the hypothesis that GcMAF has multiple biological activities that could be responsible for its anti-cancer effects, possibly through molecular interaction with the VDR that in turn is responsible for a multitude of non-genomic as well as genomic effects.     

Inhibiting TGFβ1 has a protective effect on mouse bone marrow suppression following ionizing radiation exposure in vitro

Ionizing radiation (IR) causes not only acute tissue damage but also residual bone marrow (BM) suppression. The induction of residual BM injury is primarily attributable to the induction of reactive oxygen species (ROS) pressure in hematopoietic cells. In this study, we examined if SB431542, a transforming growth factor β1 (TGFβ1) inhibitor, can mitigate IR-induced BM suppression in vitro. Our results showed that treatment with SB431542 protected mice bone marrow mononuclear cells (BMMNCs), hematopoietic progenitor cells (HPCs) and hematopoietic stem cells (HSCs) from IR-induced suppression using cell viability assays, clonogenic assays and competitive repopulation assays. Moreover, expression of gene-related ROS production in hematopoietic cells was analyzed. The expression of NOX1, NOX2 and NOX4 was increased in irradiated BMMNCs, and that of NOX2 and NOX4 was reduced by SB431542 treatment. Therefore, the results from this study suggest that SB431542, a TGFβ1 inhibitor, alleviates IR-induced BM suppression at least in part via inhibiting IR-induced NOX2 and NOX4 expression.     

维生素D类似物EB1089对肝癌细胞增殖和凋亡的影响

目的探讨维生素D类似物EB1089对肝癌细胞增殖和凋亡的影响。方法体外培养维生素D3受体(VDR)阳性和阴性的肝癌细胞株HepG2和HCCT细胞,培养时添加100、10和1nmol/LEB1089,分别作用2、4和6d后,用四唑蓝比色实验(MTT)、平板克隆形成实验检测细胞的存活和生长;用反转录PCR(RTPCR)检测VDRmRNA的表达;用流式细胞仪和电子显微镜检测细胞凋亡。结果EB1089对VDRmRNA表达阳性的HepG2细胞的抑制率为175%～721%,对VDRmRNA表达阴性的HCCT细胞没有抑制作用;电镜结果显示EB1089可诱导HepG2细胞凋亡,流式细胞仪结果显示凋亡细胞的百分比为214%,并可阻滞细胞周期于G1期。结论EB1089对人肝癌细胞株HepG2的增殖具有抑制作用,可通过VDR受体抑制人肝癌细胞的增殖,并可诱导HepG2细胞凋亡。     

Vitamin D and adipogenesis: new molecular insights

The focus of the current review is to highlight some new insights into the molecular mechanism by which vitamin D, a potentially nutritionally modulated factor, influences adipogenesis. Recent studies, predominantly using the mouse 3T3-L1 pre-adipocyte cell culture model, have shown that the role of vitamin D in inhibiting adipogenesis is mediated at the molecular level through a vitamin D receptor (VDR)-dependent inhibition of CCAAT enhancer binding protein-alpha (C/EBP alpha) and peroxisome proliferator-activated receptor-gamma (PPAR gamma) expression and a decrease in PPAR gamma transactivating activity in the pre-adipocyte. The latter action may reflect a vitamin D-induced decrease in endogenous PPAR gamma ligand availability and a competition between VDR and PPAR gamma for a limiting amount of retinoid X receptor (RXR), a common heterodimeric binding partner of both nuclear receptors.     

Dual regulation of cell proliferation and survival via activation of glucagon-like peptide-2 receptor signaling

Peptide hormones regulate cell viability and tissue integrity, directly or indirectly, through activation of G-protein-coupled receptors via diverse mechanisms including stimulation of cell proliferation and inhibition of cell death. Glucagon-like peptide-2 (GLP-2) is a 33 amino acid peptide hormone released from intestinal endocrine cells following nutrient ingestion. GLP-2 stimulates intestinal crypt cell proliferation leading to expansion of the gastrointestinal mucosal epithelium. Exogenous GLP-2 administration attenuates intestinal injury in experimental models of gastrointestinal disease and improves intestinal absorption and nutritional status in human patients with intestinal failure secondary to short bowel syndrome. GLP-2 also promotes mucosal integrity via reduction of injury-associated apoptosis in the intestinal mucosa and directly reduces apoptosis in cells expressing the GLP-2 receptor in vitro. Hence, the regenerative and cytoprotective properties of GLP-2 contribute to its therapeutic potential for the treatment of patients with intestinal disease.     

Association of Vitamin D Receptor and Vitamin D-Binding Protein Polymorphisms with Familial Breast Cancer Prognosis in a Mono-Institutional Cohort

Low 25-hydroxyvitamin D (25OHD) has been associated with an increased cancer incidence and poorer prognosis. Single nucleotide polymorphisms (SNPs) of vitamin D receptor (VDR) and vitamin D binding protein (GC gene) may interfere with vitamin D activity. This study assesses the role of VDR and GC SNPs on breast cancer (BC) recurrence and survival in a cohort of patients with a family history of breast cancer, without the pathogenic variant for BRCA1 and BRCA2. A consecutive series of patients who underwent genetic testing were genotyped for VDR and GC genes. Specifically, ApaI, FokI, TaqI, BsmI and rs2282679, rs4588, rs7041 SNPs were determined. A total of 368 wild type (WT) patients with BC were analyzed for VDR and GC SNPs. The GC rs2282679 minor allele was significantly associated with luminal subtype of the primary tumor compared to Her2+/TN breast cancer (p = 0.007). Multivariate Cox models showed that BmsI and TaqI are significantly associated with BC outcome. Patients with the major alleles showed more than 30% lower hazard of relapse (BsmI p = 0.02 and TaqI p = 0.03). Our study supports the evidence for a pivotal role of 25OHD metabolism in BC. GC SNPs may influence the hormone tumor responsiveness and VDR may affect tumor prognosis.     

维生素D受体基因与骨量的关系

近年来对维生素D受体(VDR)基因和骨量关系的研究颇有争议。有许多研究认为维生素D受体基因多态性与骨量有关联。但还有一部分研究未能证实VDR基因多态性与骨量的关联。本文就VDR基因与钙吸收、骨量、药物治疗的关系和VDR基因的协同作用以及与其它基因、环境因素的交互作用对骨量影响的研究进展进行了综述。     

Vitamin D and tuberculosis

Tuberculosis is highly prevalent worldwide, accounting for nearly two million deaths annually. Vitamin D influences the immune response to tuberculosis, and vitamin D deficiency has been associated with increased tuberculosis risk in different populations. Genetic variability may influence host susceptibility to developing active tuberculosis and treatment response. Studies examining the association between genetic polymorphisms, particularly the gene coding for the vitamin D receptor (VDR), and TB susceptibility and treatment response are inconclusive. However, sufficient evidence is available to warrant larger epidemiologic studies that should aim to identify possible interactions between VDR polymorphisms and vitamin D status.     

Resveratrol protects intestinal epithelial cells against radiation-induced damage by promoting autophagy and inhibiting apoptosis through SIRT1 activation

Intrinsic autophagy is important for the maintenance of intestinal homeostasis and intestinal regeneration. Ionizing radiation suppresses intrinsic autophagy and reduces damage-induced regeneration in the intestine, resulting in intestinal injury. Resveratrol, a sirtuin 1 (SIRT1) agonist, promotes autophagy and exerts radioprotective effect. In this study, the protective effect of resveratrol against radiation-induced intestinal injury and its potential mechanism were investigated. Intestinal epithelial cells (IEC-6) were exposed to 10 Gy ionizing radiation and resveratrol (0.1–40.0 μM). Cell viability was investigated using Cell Counting Kit 8 (CCK8), apoptosis was observed by Annexin V-fluorescein isothiocyanate/propidium iodide (PI) staining and flow cytometry, and the expression of apoptotic and autophagic proteins was determined by western blotting. Resveratrol exerted a high toxicity against IEC-6 cells, but at low concentrations, it inhibited ionizing radiation-induced apoptosis. Resveratrol increased SIRT1 expression after irradiation and inhibited ionizing radiation-induced p53 acetylation and pro-apoptotic protein, Bax, expression. Furthermore, resveratrol promoted autophagy via the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway, thereby protecting IEC-6 cells against radiation-induced damage. These results suggest that resveratrol reduces radiation-induced IEC-6 cell damage by inhibiting apoptosis and promoting autophagy via the activation of SIRT1, and that the PI3K/AKT/mTOR signaling pathway is involved in the induction of autophagy.     

Vitamin D Deficiency in Children With Intestinal Failure Receiving Home Parenteral Nutrition

Background: Vitamin D plays important roles in both skeletal and nonskeletal health. Limited data suggest that patients with intestinal failure (IF) receiving home parenteral nutrition (PN) are at risk for vitamin D deficiency due to inadequate oral intake, poor absorption, and chronic illness. The purpose of this study was to document vitamin D status in pediatric patients with IF receiving home PN. Materials and Methods: We performed a 2‐year retrospective review of children with IF followed at our center who had been on home PN for ≥6 months and had ≥1 serum 25‐hydroxyvitamin D (25‐OHD) level checked as part of routine clinical care. Patients were then categorized as deficient (<20 ng/mL), insufficient (20–29 ng/mL), or normal (≥30 ng/mL) based on their lowest vitamin D level. Demographic data and clinical characteristics were also assessed. Results: Eleven of 27 children (41%) had ≥1 insufficient 25‐OHD level, including one child with vitamin D deficiency. Diagnosis of short bowel syndrome (compared with dysmotility or malabsorption syndromes) was associated with decreased likelihood of suboptimal vitamin D status, with an odds ratio of 0.12 (95% confidence interval, 0.02–0.8, P = .028). Osteopenia was noted in 59% of the cohort. There was a trend toward higher risk for osteopenia in patients with low 25‐OHD levels compared with those with normal 25‐OHD levels (82% vs 44%, P = .109). Conclusion: Suboptimal 25‐OHD levels are common in children with IF on home PN. This emphasizes the critical importance of routine surveillance of serum vitamin D levels and consideration of enteral supplementation when indicated.     

Circulating levels of vitamin D, vitamin D receptor polymorphisms, and colorectal adenoma: a meta-analysis

Growing evidence suggests an elevated risk for colorectal neoplasia among individuals with low levels of vitamin D, the biological actions of which are mediated by the vitamin D receptor (VDR). To investigate the association among vitamin D status, VDR polymorphisms (FokI, and BsmI), and colorectal adenoma, we conducted a meta-analysis of nine studies of circulating levels of 25-hydroxyvitamin D (25(OH)D) and five studies of FokI or BsmI polymorphisms in relation to colorectal adenomas. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were pooled using a random-effects model. A total of 3398 colorectal adenomas for 25(OH)D and 1754 colorectal adenomas for VDR were included in the meta-analysis. We identified a significant inverse association between colorectal adenoma (combined RR, 0.93; 95% CI, 0.87-0.98 per 10 ng/mL increase in 25(OH)D levels). When we examined FokI and BsmI polymorphisms in the meta-analysis, we found no association for either FokI (combined RR, 1.00; 95% CI, 0.95-1.06) or BsmI (combined RR, 0.99; 95% CI, 0.93-1.05) in the additive model. These data suggest an inverse association between circulating 25(OH)D levels and colorectal adenoma risk.     

Vitamin D Receptor Gene Polymorphism and Left Ventricular Hypertrophy in Chronic Kidney Disease

FokI and BsmI polymorphisms of vitamin D receptor (VDR) gene are regarded as reliable markers of disturbed vitamin D signaling pathway. Left ventricular hypertrophy (LVH) is a strong cardiovascular risk marker in end stage renal disease (ESRD) patients. Since BsmI polymorphism has been associated with LVH in ESRD patients, we addressed this study in patients with chronic kidney disease (CKD) not yet on dialysis. One hundred and forty five patients with CKD stage 3 were genotyped for FokI and BsmI VDR polymorphisms, in order to assess the relationships between these VDR polymorphisms, some markers of mineral bone disorders, and LVH measured by echocardiography. Patients bearing either the Ff heterozygous or FF homozygous genotype had significantly higher PTH values than those bearing the ff genotype. The relationships between VDR genotypes and LVH revealed a highly significant association of the BsmI Bb heterozygous genotype with LVH. In patients with CKD stage 3 BsmI B allele was independently related to LVH. Since LVH is a frequent finding in dialysis population due to several mechanisms, the presence of the same relationship in patients with CKD strengthens the hypothesis that alterations of vitamin D signaling are implicated in LVH development in patients with renal diseases.     

儿童血清维生素D水平、自噬、免疫调节及机体各系统疾病的相关性综述

维生素D对人体作用广泛且复杂,是一种与特异性受体相结合而发挥作用的一类脂溶性类固醇激素,其受体在多种组织细胞中都有分布,含量最多的器官为小肠、肾脏、甲状旁腺及骨骼,此外,心血管、胃肠道、中枢神经系统等其他脏器也有维生素D受体的表达。血清维生素D水平异常时,机体会出现相应的病理改变,如:呼吸道疾病、消化道疾病、泌尿系统疾病、风湿免疫疾病、自身免疫性疾病、肥胖等疾病,本文就维生素D水平、自噬、免疫调节及各系统疾病的相关性进行综述。     

Amelioration of radiation-induced hematopoietic and gastrointestinal damage by Ex-RAD(R) in mice

The aim of the present study was to assess recovery from hematopoietic and gastrointestinal damage by Ex-RAD^®, also known as ON01210.Na (4-carboxystyryl-4-chlorobenzylsulfone, sodium salt), after total body radiation. In our previous study, we reported that Ex-RAD, a small-molecule radioprotectant, enhances survival of mice exposed to gamma radiation, and prevents radiation-induced apoptosis as measured by the inhibition of radiation-induced protein 53 (p53) expression in cultured cells. We have expanded this study to determine best effective dose, dose-reduction factor (DRF), hematological and gastrointestinal protection, and in vivo inhibition of p53 signaling. A total of 500 mg/kg of Ex-RAD administered at 24 h and 15 min before radiation resulted in a DRF of 1.16. Ex-RAD ameliorated radiation-induced hematopoietic damage as monitored by the accelerated recovery of peripheral blood cells, and protection of granulocyte macrophage colony-forming units (GM-CFU) in bone marrow. Western blot analysis on spleen indicated that Ex-RAD treatment inhibited p53 phosphorylation. Ex-RAD treatment reduces terminal deoxynucleotidyl transferase mediated dUTP nick end labeling assay (TUNEL)-positive cells in jejunum compared with vehicle-treated mice after radiation injury. Finally, Ex-RAD preserved intestinal crypt cells compared with the vehicle control at 13 and 14 Gy. The results demonstrated that Ex-RAD ameliorates radiation-induced peripheral blood cell depletion, promotes bone marrow recovery, reduces p53 signaling in spleen and protects intestine from radiation injury.