Interactions between vitamin D and IGF-I: from physiology to clinical practice

New insights into the vitamin D/PTH axis in endocrine-driven metabolic bone diseases

BACKGROUND

Endocrine regulation of bone metabolisms is the focus of the "Skeletal Endocrinology" series of meetings.

AIMS

To report on the outcome of the discussion on the role of vitamin D/PTH axis in endocrine osteopathies held during the 10th Skeletal Endocrinology Meeting which took place in Stresa (Italy) in March 2023.

OUTCOMES

Vitamin D/PTH axis has relevant influence on several outcomes in the general population and in patients affected by endocrinopathies such as hypoparathyroidism and secreting pituitary adenomas.

CONCLUSIONS

Assessing the status of the vitamin D/PTH axis and using vitamin D and PTH as therapeutic agents is mandatory in several endocrine-related bone metabolic conditions.

Vitamin D status and VDR gene polymorphisms in patients with growth hormone deficiency: A case control Tunisian study

Introduction

Growth Hormone Deficiency (GHD) is a rare disease marked by a complete or partial reduction in the production of growth hormone. Vitamin D deficiency is frequent and may be associated with several pathologies. However, the association between GHD and vitamin D deficiency has not been extensively studied. This study aimed to analyse VDR gene polymorphisms related to vitamin D status to ensure better care for patients with GHD.

Material and methods

A case-control study was conducted at the Children's Hospital of Tunis in collaboration with the Farhat Hached's Hospital of Sousse, including patients with GHD and healthy subjects. Genetic analysis of the VDR gene polymorphisms was performed using PCR-RFLP technique. Haplotypes were examined with Haploview software, while statistical analyses were carried out using SPSS and R programming language.

Results

Our study revealed significant differences in vitamin D (p = 0, 049) and calcium concentrations between patients and healthy subjects, which were lower in the GHD group (p = 0,018). A comparison of allelic and genotypic frequencies of the five polymorphisms indicated an association between the FokI polymorphism and GHD. Furthermore, significant difference was observed between the ApaI genotypes and PTH (p = 0,019) and ALP (p = 0,035). FokI genotypes were associated with phosphorus (p = 0,021). Additionally, One haplotype, CTAGT, exhibited a significant difference between the patients and healthy subjects (p = 0,002).

Conclusion

Our study findings indicate that hypovitaminosis D is common among patients with GHD, even when undergoing treatment with rhGH. This underscores the critical importance of vitamin D supplementation during treatment.

Mediating Effect of Insulin-Like Growth Factor-I Underlying the Link Between Vitamin D and Gestational Diabetes Mellitus

Vitamin D was well-known to be associated with gestational diabetes mellitus (GDM). Insulin-like growth factor-I (IGF-I) has been linked to vitamin D and GDM, respectively. We hypothesize that changes in IGF-I metabolism induced by 25(OH)D3 might contribute to GDM. Therefore, we investigated the independent and combined relationships of serum 25(OH)D3 and IGF-I concentrations with GDM risk, and the mediation effect of IGF-I on 25(OH)D3. A total of 278 pregnant women (including 125 cases and 153 controls) were recruited in our current study. Maternal serum 25(OH)D3 and IGF-I were measured in the second trimester. Logistic regression models were used to estimate the associations of 25(OH)D3 and IGF-I concentrations with the risk of GDM. Mediation analyses were used to explore the mediation effect of IGF-I on the association between 25(OH)D3 and the risk of GDM. After adjusted for the confounded factors, both the third and fourth quartile of 25(OH)D3 decreased the risk of GDM (OR = 0.226; 95% CI, 0.103-0.494; OR = 0.109; 95% CI, 0.045-0.265, respectively) compared to the first quartile of 25(OH)D3. However, the third and fourth quartile of serum IGF-I (OR = 5.174; 95% CI, 2.287-11.705; OR = 12.784; 95% CI, 5.292-30.879, respectively) increased the risk of GDM compared to the first quartile of serum IGF-I. Mediation analyses suggested that 19.62% of the associations between 25(OH)D3 and GDM might be mediated by IGF-I. The lower concentration of serum 25(OH)D3 or higher IGF-I in the second trimester was associated with an increased risk of GDM. The serum IGF-I level might be a potential mediator between 25(OH)D3 and GDM.

Osteoporosis and dermatoporosis: a review on the role of vitamin D

Osteoporosis (OP) and Dermatoporosis (DP) are expressions of the aging process at the skin and bone levels, respectively. Both conditions are associated with increased morbidity for elderly people, and this requires necessary interventions. They share many common risk factors; among these, vitamin D (VD) deficiency appears to have a role. VD is involved in either disease with many mechanisms, among which immunomodulation. VD deficiency has been linked to OP because it inhibits the body's capacity to absorb calcium and maintain optimal bone health. Available evidence suggests that proper vitaminosis D also appears to be vital in preventing skin age-related issues. DP is often seen in elderly individuals, particularly those with long-term sun exposure and a history of chronic sun damage. VD deficiency can be linked to DP, since its involvement in collagen production, epidermal barrier function, inflammation regulation, wound healing, and sun protection. Aim of this review is to summarize the most updated existing evidence on the role of VD in the development of fragility syndromes such as DP and OP and the possible benefits of VD supplementation as a simple and harmful weapon against aging.

Causal associations between insulin-like growth factor 1 and vitamin D levels: a two-sample bidirectional Mendelian randomization study

Background

Insulin-like growth factor 1 (IGF-1) plays a vital role in the attainment and maintenance of bone mass throughout life and is closely related to the stature of children. 25-Hydroxyvitamin D (25-OHD) is an intermediate of vitamin D (Vit D) metabolism and a key indicator of Vit D nutritional status. Multiple studies have revealed that IGF-1 levels undergo a non-significant increase after Vit D supplementation. Here, we analyzed the causal and reverse causal relationships between 25-OHD and IGF-1 levels using Mendelian randomization (MR).

Methods

Two-sample MR was used to estimate an unconfounded bidirectional causal relationship between the level of IGF-1 and those of Vit D and 25-OHD. Single nucleotide polymorphisms (SNPs) were filtered from genome-wide association studies (GWAS) after a comprehensive search of the Integrative Epidemiology Unit GWAS database. Several MR methods were employed, including inverse-variance weighted (IVW) method, and a sensitivity analysis was undertaken to detect whether pleiotropy or heterogeneity biased the MR results.

Results

Genetically predicted IGF-1 was found to have a causal association with Vit D and serum 25-OHD levels, where Vit D and serum 25-OHD levels increased with increasing IGF-1 concentrations (Vit D: IVW β:0.021, 95% CI: 0.005-0.036, p = 7.74 × 10^-3; 25-OHD: IVW β: 0.041, 95% CI: 0.026-0.057, p = 2.50 × 10^-7). A reverse causal effect was also found, indicating Vit D and serum 25-OHD have a positive causal relationship with IGF-1 (Vit D: IVW β:0.182, 95% CI: 0.061-0.305, p = 3.25 × 10^-3; 25-OHD: IVW β: 0.057, 95% CI = 0.017-0.096, p = 4.73 × 10^-3). The sensitivity analysis showed that horizontal pleiotropy was unlikely to bias the causality in this study (MR-Egger: Vit D intercept p = 5.1 × 10^-5, 25-OHD intercept p = 6.4 × 10^-4 in forward analysis; Vit D intercept p = 6.6 × 10^-4, 25-OHD intercept p = 1.9 × 10^-3 in reverse analysis), and a leave-one-out analysis did not identify evidence of bias in the results.

Conclusion

The results of the MR analysis provide evidence that IGF-1 has positive causal and reverse causal relationships with Vit D and serum 25-OHD, respectively, in European populations. Our findings also provide guidance for the prevention and treatment of short stature and other related diseases.

COVID-19 infection and metabolic comorbidities: Mitigating role of nutritional sufficiency and drug - nutraceutical combinations of vitamin D

The vulnerability of human health is amplified in recent times with global increase in non-communicable diseases (due to lifestyle changes and environmental insults) and infectious diseases (caused by newer pathogens and drug-resistance strains). Clinical management of diseases is further complicated by disease severity caused by other comorbid factors. Drug-based therapy may not be the sole approach, particularly in scenarios like the COVID-19 pandemic, where there is no specific drug against SARS-CoV-2. Nutritional interventions are significant in armouring human populations in disease prevention, and as adjunctive therapy for disease alleviation. Amidst ongoing clinical trials to determine the efficacy of Vit. D against infections and associated complications, this review examines the pleiotropic benefits of nutritional adequacy of vitamin D (Vit. D) in combating viral infections (COVID-19), its severity and complications due to co-morbidities (obesity, diabetes, stroke and Kawasaki disease), based on research findings and clinical studies. Supplements of Vit. D in combination with other nutrients, and drugs, are suggested as promising preventive-health and adjunct-treatment strategies in the clinical management of viral infections with metabolic comorbidities.

Associations of serum 25(OH)D levels with physical performance and anabolic hormones in young men

Purpose: The present study examined the association of vitamin D measured by serum 25(OH)D with physical performance outcomes and serum levels of anabolic hormones in young men. Methods: 412 young men (age 19 ± 1 year) entering their compulsory military service volunteered to participate in the study. The study consisted of two groups from two different military bases: Group A was studied in January and group B in July. The groups were first compared with each other and due to statistically significant (p < 0.001 analyzed with independent samples t-test) differences in physical condition (sit-up, push-up, and standing long jump-tests and testosterone levels) between the groups, groups were analyzed separately. The serum levels of 25(OH)D, testosterone (TES), sex hormone binding globulin (SHBG), and insulin-like growth factor-1 (IGF-1) were analyzed by electrochemiluminescence immunoassay. Physical performance tests consisted of muscular fitness (sit-ups, push-ups, standing long jump) and aerobic fitness (12-minute-running) tests. The association of serum 25(OH)D with physical performance tests and anabolic hormones was analyzed using linear regression. Results: After controlling for the group, body mass index, and leisure-time physical activity, serum 25(OH)D level was positively associated with aerobic and muscular fitness (β = 0.15-0.20, all p < 0.05). Also, the participants with sufficient serum 25(OH)D levels (≥75 nmol/L) had better aerobic and muscular fitness and higher TES in group B, and better upper extremity muscular fitness in group A (all p < 0.05). In group A, there were 166 participants with serum levels of 25(OH) D < 75 nmol/L and 18 ≥ 75 nmol/L. In group B, the amounts were 92 (<75 nmol/L) and 136 (≥75 nmol/L), respectively. Conclusion: Serum 25(OH)D was positively associated with both aerobic and muscular fitness and those with sufficient vitamin D levels, had higher levels of TES. Thus, maintaining a sufficient serum 25(OH)D level may be beneficial for physical performance and anabolic state in young men.

Integrated Transcriptome and Microbiota Reveal the Regulatory Effect of 25-Hydroxyvitamin D Supplementation in Antler Growth of Sika Deer

The level of plasma 25-hydroxyvitamin D (25(OH)D) is associated with the growth of the antler, a fast-growing bone organ of Cervidae. However, the benefits of 25(OH)D supplementation on antler growth and the underlying mechanisms remain unclear. Here, the antler growth profile and transcriptome, plasma parameters, rumen bacteria, and metabolites (volatile fatty acids and amino acids) were determined in sika deer in a 25(OH)D supplementation group (25(OH)D, n = 8) and a control group (Ctrl, n = 8). 25(OH)D supplementation significantly increased the antler weight and growth rate. The levels of IGF-1,25(OH)D and 1,25-dihydroxyvitamin D were significantly higher in the 25(OH)D group than in the Ctrl group, while the levels of LDL-C were lower. The levels of valerate and branched-chain amino acids in the rumen fluid were significantly different between the 25(OH)D and Ctrl groups. The bacterial diversity indices were not significantly different between the two groups. However, the relative abundances of the butyrate-producing bacteria (families Lachnospiraceae and Succinivibrionaceae) and the pyruvate metabolism pathway were higher in the 25(OH)D group. The transcriptomic profile of the antler was significantly different between the 25(OH)D and Ctrl groups, with 356 up- and 668 down-regulated differentially expressed genes (DEGs) in the 25(OH)D group. The up-regulated DEGs were enriched in the proteinaceous extracellular matrix and collagen, while the down-regulated DEGs were enriched in the immune system and lipid metabolism pathways. Overall, these results provide novel insights into the effects of 25(OH)D supplementation on the host metabolism, rumen microbiota, and antler transcriptome of sika deer.

Association between vitamin D and calcium intakes, breast microcalcifications, breast tissue age-related lobular involution and breast density

OBJECTIVE

To demystify the potential role of vitamin D and calcium intakes in breast carcinogenesis, we explored the association between these two nutrients and three biomarkers of breast cancer risk: the presence of microcalcifications, age-related lobular involution and breast density.

METHODS

A total of 82 premenopausal and 79 postmenopausal women diagnosed with breast cancer completed a food frequency questionnaire to assess their total vitamin D and calcium intakes. Presence of microcalcifications was determined by reviewing pathology reports. Age-related lobular involution was assessed in nontumoral breast tissue on hematoxylin-eosin-stained slides and percent breast density was assessed by a computer-assisted method. Multivariate generalized linear models were used to evaluate associations between quartiles of vitamin D and calcium intakes and the biomarkers of breast cancer risk.

RESULTS

Increasing quartiles of vitamin D intake were inversely associated with the presence of microcalcifications (fourth quartile [Q4] prevalence ratio [PR] = 0.55; Ptrend = 0.021) and breast density (Q4-Q1 = -7.7%; Ptrend = 0.023) in postmenopausal women, and positively associated with age-related lobular involution in women with microcalcifications (Q4 PR = 1.62; Ptrend = 0.036). Increasing quartiles of calcium intake were inversely associated with microcalcifications among all (Q4 PR = 0.44), premenopausal (Q4 PR = 0.37) and postmenopausal women (Q4 PR = 0.38; Ptrend < 0.014 for all). It was also inversely associated with breast density in women without microcalcification (Q4-Q1 = -8.3%; Ptrend = 0.047), but positively associated with breast density in women with microcalcifications (Q4-Q1 = 10.0%; Ptrend = 0.032).

CONCLUSIONS

Results suggest that the association between vitamin D and calcium intakes and breast cancer risk factors could be influenced by the presence of microcalcifications.

Evaluation of IGF-1, TNF-α, and TGF-β Gene Expression after Oral Vitamin D Supplementation in School-Aged Children with Chronic Bronchial Asthma

BACKGROUND: Airway remodeling in children with bronchial asthma is due to the effect of inflammatory mediators and growth factors on the bronchial epithelium. Vitamin D (VitD) has immunomodulatory effect in many inflammatory diseases as bronchial asthma. The ant-inflammatory and anti-fibrotic role of VitD could prevent or improve air way remodeling in asthmatic patients. AIM: The study investigated the effect of VitD supplementation on the expression of transforming growth factor-beta (TGF-β), tumor necrosis factor-alpha (TNF-α), and insulin growth factor 1(IGF-1) and to correlate them with asthma severity and level of control. METHODS: The serum level of VitD and the mRNA expression of IGF-1, TGF-β, and TNF-α were estimated in 50 patients and 20 healthy controls control subjects using quantitative PCR in real-time. Asthmatic patients with VitD deficiency received VitD supplementation for 2 months followed by remeasurement of serum VitD and the genes expression TGF-β, TNF-α, and IGF-1. RESULT: Pre-intake of VitD and serum level of VitD were lower in all patients than control subjects (p = 0.005). VitD level was directly correlated with IGF-1 mRNA expression, which was indirectly correlated with TGF-β, r = 0.5 and −0.57; p = 0.0001 and 0.002, respectively. After VitD supplementation, the expression of the TGF-β mRNA gene was the only gene that decreased significantly (p = 0.04) together with improved asthma control and spirometric parameters. CONCLUSIONS: VitD supplementation down regulated the gene expression of TGF-β and improved asthma control level, but it did not significantly affect the gene expression of TNF-α and IGF-1.

Vitamin D and Parathyroid Hormone during Growth Hormone Treatment

Background. There is some controversy concerning a potential interaction between vitamin D and PTH and the GH/IGF-1 axis. The goal of this study is to assess vitamin D and PTH status in children with GH deficiency at diagnostic and during treatment with rhGH. Methods. Longitudinal and descriptive study in 110 patients, aged 3.3−9.1 years, with GH deficiency (GHD group) treated with rhGH. At diagnosis and after 12, 24, 36, and 48 months of treatment, a clinical (height, weight, and bone age) and laboratory (phosphorus, calcium, calcidiol, PTH, IGF-1) evaluation was performed. Concurrently, 377 healthy children, aged 3.8−9.7 years, were enrolled and constituted a control group. Vitamin D status was stated in accordance to the U.S. Endocrine Society criteria. Results. No significant differences were found in the prevalence of vitamin D deficiency among control (11.43%) and GHD (13.6%) groups at the moment of diagnosis, remaining without significant changes at 12 (12.9%), 24 (14.6%), 36 (13.1%), and 48 months (13.3%) of treatment. There were not any significant differences in serum levels of calcium, phosphorus, and calcidiol, but a steady increase (p < 0.001) in PTH was detected. Conclusions. Prepubertal patients with GH deficient do not appear to have a higher risk of vitamin D deficiency than healthy subjects, and with treatment with rhGH, no changes in the organic content of vitamin D were observed although a significant increase in PTH levels was detected.

Vitamin D in Basketball Players: Current Evidence and Future Directions

CONTEXT

Despite growing interest in quantifying and correcting vitamin D inadequacy in basketball players, a critical synthesis of these data is yet to be performed to overcome the low generalizability of findings from individual studies.

OBJECTIVE

To provide a comprehensive analysis of data in basketball pertaining to (1) the prevalence of vitamin D inadequacy; (2) the effects of vitamin D supplementation on 25-hydroxyvitamin D [25(OH)D] concentration (and its association with body composition), bone health, and performance; and (3) crucial aspects that warrant further investigation.

DATA SOURCES

PubMed, MEDLINE, ERIC, Google Scholar, SCIndex, and ScienceDirect databases were searched.

STUDY SELECTION

After screening, 15 studies were included in the systematic review and meta-analysis.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

The prevalence of vitamin D inadequacy, serum 25(OH)D, body composition, stress fractures, and physical performance were extracted.

RESULTS

The pooled prevalence of vitamin D inadequacy for 527 basketball players in 14 studies was 77% (P < 0.001; 95% CI, 0.70-0.84). Supplementation with 4000 IU/d and 4000 IU/wk (absolute mean difference [AMD]: 25.39 nmol/L; P < 0.001; 95% CI, 13.44-37.33), as well as 10,000 IU/d (AMD: 100.01; P < 0.001; 95% CI, 70.39-129.63) vitamin D restored 25(OH)D to normal concentrations. Body composition data revealed inverse correlations between changes in serum 25(OH)D (from pre- to postsupplementation) and body fat (r = -0.80; very large). Data concerning positive impacts of vitamin D supplementation on bone health and physical performance remain sparse.

CONCLUSION

The high proportion of vitamin D inadequacy underscores the need to screen for serum 25(OH)D in basketball players. Although supplementation restored vitamin D sufficiency, the beneficial effects on bone health and physical performance remain sparse. Adiposity can modulate 25(OH)D response to supplementation.

Associations of Vitamin D Levels with Physical Fitness and Motor Performance; A Cross-Sectional Study in Youth Soccer Players from Southern Croatia

Simple Summary

Vitamin D is a fat-soluble prohormone crucial for bone mineralization, muscle contractility, and neurological conductivity. It is theorized that Vitamin D plays an important role in sport performances, especially in young athletes. In this study we examined the associations of levels of 25-hydroxyvitamin D (25(OH)D) with physical fitness and motor-performance achievements in youth soccer players from Southern Croatia. Participants were tested on physical fitness, motor performance and vitamin D at the end of the winter period, when levels of vitamin D are known to be lowest due to low exposure to sunlight. Results showed that deficiency of 25(OH)D was widespread among youth soccer players living in Southern Croatia. Low 25(OH)D levels were associated with lower results in fitness tests (i.e., tests of energetic capacities), but there was no correlation between 25(OH)D levels and the results in motor performance tests (i.e., skill tests). Our results support the theory of the association between vitamin D and energetic capacities of athletes, but there is no evidence on association between vitamin D and skill-based capacities.

Abstract

Vitamin D level is known to be a factor potentially influencing physical fitness, but few studies have examined this phenomenon among youth athletes. We aimed to evaluate the associations of vitamin D levels (as measured by 25-hydroxyvitamin D concentrations—25(OH)D) with various physical fitness and motor performance tests in youth football (soccer) players. This cross-sectional study included a total of 52 youth soccer players (15.98 ± 2.26 years old) from Southern Croatia. The participants were evaluated at the end of the winter period and data were collected of anthropometric measures (body mass and body height), vitamin D status (25(OH)D levels), physical fitness tests (sprints of 10 and 20 m, 20 yards test, the countermovement jump, the reactive strength index (RSI)) and motor performance tests (the soccer-specific CODS, the soccer-specific agility, and static balance). Among the studied players, 54% had 25(OH)D insufficiency/deficiency, showing a lack of 25(OH)D is widespread even in youth athletes living at a southern latitude. The 25(OH)D level was correlated with sprint 20 m, 20 yards tests, and RSI, showing a greater role of 25(OH)D in physical fitness tests where energetic capacity is essential than in sport-related motor performance tests where skills are crucial. Our results support the idea that vitamin D can play a determinant role in physical fitness tests with a clear physiological component, but is not crucial in motor performance tests related to specific sports where skills are a key component. Future studies should investigate the effects of vitamin D supplementation on the performance in physical fitness and motor performance tests among youth athletes.

Vitamin D as a Potential Therapeutic Option in Cancer Treatment: Is There a Role for Chemoprevention?

BACKGROUND

Vitamin D (Vit D) serves as a precursor to the potent steroid hormone calcitriol, which regulates numerous genes that control homeostasis, epithelial cell differentiation, proliferation, and apoptosis. Low level of Vit D is implicated in the development and progression of several diseases including bone fractures, cardiovascular disease, diabetes mellitus, and cancers. The present review highlights the role of vitamin D in cancer with a particular emphasis on genetic variants related to Vit D metabolism as well as clinical trials of Vit D supplementation as a potential therapeutic option in the treatment of cancer patients.

METHODS

Data were collected following an electronic search in the Web of Science, Medline, PubMed, and Scopus databases by using some keywords such as "cancer", "tumor", "malignancy", "vitamin D", "cholecalciferol" and "calcitriol".

RESULTS

The collected evidence from the studies revealed a consistent and strong association between Vit D status and cancer risk and survival. The associations between Vit D-related genetic variants and cancer survival support the hypothesis that Vit D may affect cancer outcomes. The mechanisms whereby Vit D reduces cancer risk and increases survival are regulation of cellular differentiation, proliferation and apoptosis as well as decreased angiogenesis in tumor microenvironment and inhibition of metastasis.

CONCLUSION

There is a paucity of evidence-based recommendations for the optimal 25(OH)D levels in patients with cancer and the role of Vit D supplementation for primary or secondary prevention of cancer. Well-designed and sufficiently powered randomized clinical trials are necessary to assess the clinical application of Vit D in enhancing the clinical efficacy of standard and adjuvant chemotherapy regimens.

Regulation of GH and GH Signaling by Nutrients

Growth hormone (GH) and insulin-like growth factor-1 (IGF-I) are pleiotropic hormones with important roles in lifespan. They promote growth, anabolic actions, and body maintenance, and in conditions of energy deprivation, favor catabolic feedback mechanisms switching from carbohydrate oxidation to lipolysis, with the aim to preserve protein storages and survival. IGF-I/insulin signaling was also the first one identified in the regulation of lifespan in relation to the nutrient-sensing. Indeed, nutrients are crucial modifiers of the GH/IGF-I axis, and these hormones also regulate the complex orchestration of utilization of nutrients in cell and tissues. The aim of this review is to summarize current knowledge on the reciprocal feedback among the GH/IGF-I axis, macro and micronutrients, and dietary regimens, including caloric restriction. Expanding the depth of information on this topic could open perspectives in nutrition management, prevention, and treatment of GH/IGF-I deficiency or excess during life.

Potential role of hypovitaminosis D and vitamin D supplementation during COVID-19 pandemic

Vitamin D deficiency is a pandemic disorder affecting over 1 billion of subjects worldwide and displaying a broad spectrum of implications on cardiovascular and inflammatory disorders. Since the initial reports of the association between hypovitaminosis D and COVID-19, Vitamin D has been pointed as a potentially interesting treatment for SARS-CoV-2 infection. We provide an overview on the current status of vitamin D deficiency, the mechanisms of action of vitamin D and the current literature on the topic, with a special focus on the potential implications for COVID-19 pandemic.

Measurement of Serum Chemerin, Oxidized LDL, and Vitamin D Levels in Prader–Willi Syndrome: A Cross-Sectional Study in Pediatric Egyptian Patients

Prader–Willi syndrome (PWS) is the commonest genetic cause of obesity. Oxidative stress and chronic low-grade inflammation play a crucial role in the pathogenesis of obesity. Alterations of vitamin D (25-OHD) levels are commonly encountered with obesity. The aim of this study was to analyze serum chemerin, oxidized low-density lipoprotein (ox-LDL), and 25-OHD values in pediatric PWS patients in comparison with obese healthy children and nonobese control groups, highlighting possible correlations with body mass index (BMI) and obesity. Twenty-six PWS Egyptian patients and 26 obese healthy individuals referred to the outpatient clinic of the Clinical Genetics Department, National Research Centre, Cairo, Egypt, and 20 control patients with matching age and sex were enrolled in the study. Patients were clinically diagnosed and confirmed by routine cytogenetic and fluorescence in-situ hybridization analysis. Anthropometric measurements were performed, and BMI was calculated by weight/height2 (kg/m2), and BMI z score was also determined. Serum chemerin, ox-LDL, and vitamin D were determined by enzyme-linked immunosorbent assay. Chemerin levels, which reflected chronic inflammation, were significantly elevated as compared with obese and nonobese controls (p ≤ 0.0001). Concerning oxidative damage, children with PWS showed higher Ox-LDL levels compared with obese and nonobese controls (p < 0.0001). Vitamin D levels were significantly lower in PWS patients compared with obese and nonobese controls (p ≤ 0.0001). Our data showed that obesity in PWS is associated with oxidative stress and chronic low-grade inflammation. Ox-LDL is a good indicator of oxidative stress, and chemerin could be used as a biomarker for the chronic inflammatory state. Furthermore, vitamin D supplementation is recommended in PWS patients

Vitamin D status and response to growth hormone treatment in prepubertal children with growth hormone deficiency

PURPOSE

To analyze whether vitamin D deficiency could condition the growth response to GH therapy, as well as to analyze if GH treatment modifies both seasonal variations and vitamin D levels in these patients.

METHODS

Retrospective study in 98 prepubertal children with GH deficiency (GHD), aged 4.1-8.9 years treated with GH. Growth rate and blood testing (calcium, phosphorus, IGF-I, 25(0H)D and PTH) were monitored at diagnostic and every six months until 24 months of treatment. A control group was recruited (247 healthy children, aged 3.8-9.7 years). The criteria of the US Endocrine Society were used for the definition of hypovitaminosis D.

RESULTS

There were no significant differences in vitamin D deficiency among control (12.5%) and GHD groups (15.3%) before starting treatment. Growth rate and IGF-1 and PTH increased (p < 0.05) during GH treatment, but there were no significant differences in calcium, phosphorus and 25(OH)D. There were no significant differences in growth rate and IGF-1, calcium and phosphorus levels in relation to the seasons along GH treatment. There was no correlation between 25(OH)D and IGF-1 during GH therapy. In every programmed control, patients with vitamin D deficiency showed lower growth rate (p < 0.05) compared to patients with vitamin D insufficiency or sufficiency.

CONCLUSION

GH treatment, at least during the first two years, does not modify the vitamin D levels. Vitamin D deficiency could condition the response to GH therapy so vitamin D monitoring should be considered as part of the routine evaluation of children with GH treatment.

Vitamin D and the insulin-like growth factor system: Implications for colorectal neoplasia

Epidemiological studies have strongly associated lower levels of vitamin D and its metabolites with an increased risk of colorectal cancer (CRC). The action of calcitriol, the active metabolite of vitamin D, is mediated by the vitamin D receptor (VDR) that is present in most tissues. In advanced CRC, VDR expression is lowered. Calcitriol has several antineoplastic effects in CRC: it promotes the G1-phase cycle arrest, lowers vascular endothelial growth factor (VEGF) synthesis and acts on tumour stromal fibroblasts to limit cell migration and angiogenesis. Hyperinsulinemia and insulin-like growth factors (IGFs) have been implicated in the pathophysiology of CRC. IGF-1 and IGFBP-3 have been the most studied components of the IGF system. Only 1% of the total serum IGF-1 is free and bioactive, and 80% of it binds to IGFBP-3. IGF-1 and its receptor IGF-1R are known to induce cell proliferation. Both IGF-1 and IGFBP-3 can favour angiogenesis by increasing the transcription of the VEGF gene. A high serum IGF-1/IGFBP-3 ratio is associated with increased risk for CRC. VDR is a transcription factor for the IGFBP-3 gene, and IGF-1 can increase calcitriol synthesis. Studies examining the effect of vitamin D treatment on serum IGF-1 and IGFBP-3 have not been in agreement since different populations, dosages and intervention periods have been used. New vitamin D treatment studies that examine CRC should take in account confounding factors such as obesity or VDR genotypes.

The effect of vitamin D supplementation on insulin-like growth factor-1: A systematic review and meta-analysis of randomized controlled trials

PURPOSE

There is equivocality regarding the interaction between vitamin D and insulin-like growth factor-1 (IGF-1). Thus, the aim of this study was to elucidate the effect of vitamin D supplementation on serum levels of IGF-1 by conducting a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

PubMed, Scopus, and ISI Web of Science databases were searched up to May 2019 for RCTs that evaluated the effect of vitamin D supplementation on IGF-1 levels. Mean and standard deviation changes of IGF-1 in each treatment group were considered for analysis and pooled using random-effect model. Risk of bias for included studies was assessed by the Cochrane scale and the NutriGrade approach was applied to evaluate the quality of evidence.

RESULTS

Six trials (n = 773 participants) were included in the meta-analysis. Compared with control group, vitamin D supplementation yielded no significant effect on serum level of IGF-1 (weighted mean difference [WMD] =4.66 ng/ml, 95 % CIs: -6.72 to 16.03, P = 0.42, I² = 74.8, P_{-heterogeneity} = 0.001). Additionally, no meaningful changes were observed in subgroup analyses.

CONCLUSION

The evidence from the limited number of published trials does not convincingly show that vitamin D supplementation elicits any clinically relevant effects on IGF-1 levels. More high-quality studies are needed to reach a consensual conclusion in this area.

Fasting to enhance Cancer treatment in models: the next steps

Short-term fasting (STF) is a technique to reduce nutrient intake for a specific period. Since metabolism plays a pivotal role in tumor progression, it can be hypothesized that STF can improve the efficacy of chemotherapy. Recent studies have demonstrated the efficacy of STF in cell and animal tumor models. However, large-scale clinical trials must be conducted to verify the safety and effectiveness of these diets. In this review, we re-examine the concept of how metabolism affects pathophysiological pathways. Next, we provided a comprehensive discussion of the specific mechanisms of STF on tumor progression, derived through studies carried out with tumor models. There are currently at least four active clinical trials on fasting and cancer treatment. Based on these studies, we highlight the potential caveats of fasting in clinical applications, including the onset of metabolic syndrome and other metabolic complications during chemotherapy, with a particular focus on the regulation of the epithelial to mesenchymal pathway and cancer heterogeneity. We further discuss the advantages and disadvantages of the current state-of-art tumor models for assessing the impact of STF on cancer treatment. Finally, we explored upcoming fasting strategies that could complement existing chemotherapy and immunotherapy strategies to enable personalized medicine. Overall, these studies have the potential for breakthroughs in cancer management.

Vitamin D Treatment Attenuates Heart Apoptosis After Coronary Artery Bypass Surgery: A Double-Blind, Randomized, Placebo-Controlled Clinical Trial

BACKGROUND

Vitamin D plays an important role in immune system and in the regulation of inflammatory cytokines. Coronary artery bypass graft (CABG) with cardiopulmonary bypass (CPB) is associated with an extensive inflammatory response. The aim of this study is to examine the effect of vitamin D treatment on the apoptosis and inflammatory changes developed after CABG.

METHODS

This trial was conducted on 70 patients undergoing CABG with CPB. Patients were randomly administered either in placebo or in the group of orally consuming 150 000 IU vitamin D daily for 3 consecutive days before surgery. The right atrium sample was taken to assess caspases 2, 3, and 7 activity using immunohistochemistry method. The serum level of interleukin-10 (IL-10) and insulin-like growth factor 1 (IGF-1) were compared at intervals.

RESULTS

The average number of positive cells for caspases 2 and 3 were less in vitamin D group (P = .006 and P < .001, respectively). There was an increase in serum levels of IL-10 after 3 days from vitamin D treatment before surgery (vitamin D group = 4.4 ± 4.9 ng/mL and control group = 1 ± 0.5 ng/mL, P = .001). After operation, IL-10 increased in both groups, higher level in vitamin D group (P < .001). The comparison of serum IGF-1 showed significant difference after 3 days (P = .006) and remained higher in vitamin D group after CPB (P < .001).

CONCLUSIONS

These findings suggest the apoptosis rate after CPB can be reduced by vitamin D. Vitamin D treatment may improve the inflammatory status before and after surgery. Further studies are needed to confirm the antiapoptotic property of vitamin D and clinical implication.

The influence of vitamin D supplementation on IGF-1 levels in humans: A systematic review and meta-analysis

BACKGROUND

Inconsistencies exist with regard to influence of vitamin D supplementation on IGF-1 levels. The inconsistencies could be attributed to several factors, such as dosage and duration of intervention, among others. To address these inconsistencies, this study was conducted to determine the impact of vitamin D supplementation on IGF-1 levels through a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

A comprehensive systematic search was carried out in PubMed/MEDLINE, Web of Science, SCOPUS and Embase for RCTs that investigated the impact of vitamin D intake on circulating IGF-1 levels from inception until June 2019. Weighted mean difference (WMD) with the 95 % CI were applied for estimating combined effect size. Subgroup analysis was performed to specify the source of heterogeneity among studies.

RESULTS

Pooled results from eight studies demonstrated an overall non-significant increase in IGF-1 following vitamin D supplementation (WMD: 4 ng/ml, 95 % CI: -4 to 11). However, a significant degree of heterogeneity among studies was observed (I² = 66 %). The subgroup analyses showed that vitamin D dosage of ≤1000 IU/day (WMD: 10 ng/ml) significantly increased IGF-1 compared to the vitamin D dosage of <1000 IU/day (WMD: -1 ng/ml). Moreover, intervention duration ≤12 weeks (WMD: 11 ng/ml) significantly increased IGF-1 compared to intervention duration <12 weeks (WMD: -3 ng/ml). In the epidemiological cohort study, participants under 60 years of age with a higher dietary vitamin D intake had significantly higher IGF-1 levels when compared to those with lower dietary vitamin D intake in second categories.

CONCLUSION

The main results indicate a non-significant increase in IGF-1 following vitamin D supplementation. Additionally, vitamin D dosages of <1000 IU/day and intervention durations of <12 weeks significantly raised IGF-1 levels.

Circulating IGF-1 Independently Predicts Blood Pressure in Children With Higher Calcium-Phosphorus Product Levels

OBJECTIVE

To study the association between insulin-like growth factor 1 (IGF-1) and blood pressure in children, in particular, the potential interaction with the serum calcium-phosphorus product (Ca*P).

METHODS

A longitudinal study included 521 children (age 8.8 ± 0.1) from northeastern Spain, of whom 158 were followed-up after 5 years. IGF-1, insulin-like growth factor-binding protein 3 (IGFBP-3), and serum calcium and phosphorus were measured at baseline. Anthropometric (body-mass index [BMI] and waist) and cardiometabolic variables (systolic [SBP] and diastolic blood pressure), pulse pressure, insulin, homeostatic model assessment of insulin resistance [HOMA-IR], high-density lipoprotein [HDL]-cholesterol, and triglycerides) were assessed at baseline and at the end of follow-up. Statistical analysis included Pearson correlations followed by multivariable linear regression analyses.

RESULTS

Baseline IGF-1 and IGF-1/IGFBP-3 molar ratio positively correlated with baseline and follow-up BMI, waist, SBP, pulse pressure, insulin, HOMA-IR and triglycerides (r 0.138-0.603; all P < 0.05). The associations with SBP were stronger with increasing Ca*P (r 0.261-0.625 for IGF-1; and r 0.174-0.583 for IGF-1/IGFBP-3). After adjusting for confounding variables, baseline IGF-1 and IGF-1/IGFBP-3 remained independently associated with both baseline and follow-up SBP in children in the highest Ca*P tertile (β = 0.245-0.381; P < 0.01; model R2 = 0.246-0.566).

CONCLUSIONS

Our results suggest that IGF-1 in childhood is an independent predictor of SBP in apparently healthy children, especially in those with high Ca*P levels.

Decreased Levels of Serum IGF-1 and Vitamin D Are Associated With Cognitive Impairment in Patients With Type 2 Diabetes

PURPOSE

To determine the association of serum insulin-like growth factor 1 (IGF-1) and vitamin D levels with cognition status in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 173 patients with T2DM were recruited and divided into mild cognitive impairment (MCI) group (n = 94) and normal cognition (NC) group (n = 79). Levels of IGF-1 and 25(OH)D were measured and compared, and the correlations among IGF-1, 25(OH)D, and cognitive function were analyzed.

RESULTS

Insulin-like growth factor 1 and 25(OH)D levels significantly decreased in MCI group than those in the NC group (both P < .001). Multiple stepwise regression analysis revealed that IGF-1 (β = .146, P < .001) and 25(OH)D (β = .199, P < .001) independently predicted Montreal Cognitive Assessment (MoCA) scores. Partial least square regression showed that contributions of both 25(OH)D (P < .001) and IGF-1 (P < .001) to MoCA scores were significant, while no cross-effect was observed between them (P = .714).

CONCLUSIONS

Low serum IGF-1 and 25(OH)D levels may separately predict poor cognitive performance in patients with diabetes.

Sweat and vitamin D status in congenital, lifetime, untreated GH deficiency

PURPOSE

A reciprocal relationship exists between the skin and the GH/IGF-I axis. Skin produces both IGF- I and vitamin D, and GH and IGF-I exert several actions in the skin. Reduced sweating and altered phosphor-calcium homeostasis are occasionally reported in subjects with GH deficiency (GHD), mostly in the setting of hypopituitarism, therefore associated to other hormonal deficiencies. It is unclear whether these findings are due to GHD. The aim of this study was to assess skin function in subjects with isolated GHD (IGHD) due to a mutation in the GHRH receptor gene.

METHODS

In a cross-sectional study we enrolled 20 IGHD and 20 local controls. Sweating (volume, conductivity and chloride content) was assessed by a 30 min pilocarpine iontophoresis test, using the Macroduct® Sweat Collection System. IGF-I, Insulin, PTH, 25-hydroxyvitamin D, C-reactive protein (CRP), CPK, glucose, calcium, phosphate, alkaline phosphatase, total proteins and fractions, urinary calcium, and insulin were measured. HOMA-IR was calculated.

RESULTS

IGHD presented lower sweating, but normal vitamin D and phosphor-calcium homeostasis. Additionally, IGHD subjects presented lower HOMA-IR, higher CRP and reduced CPK.

CONCLUSION

Untreated IGHD cause reduction in sweating, but does not affect phosphor-calcium homeostasis.

Lean body mass accretion is elevated in response to dietary vitamin D: A dose-response study in female weanling rats

Vitamin D status positively relates to lean body mass in infants. This study tested the effect of vitamin D on body composition and growth-related hormones. It was hypothesized that low vitamin D status programs for higher fat mass accretion. Female weanling Sprague-Dawley rats (4 weeks; n = 6/diet) were randomized to AIN-93G diets with modified vitamin D contents for 8 weeks: group 1 (1 IU vitamin D₃/g diet), group 2 (2 IU vitamin D₃/g diet), and group 3 (4 IU vitamin D₃/g diet). At week 0, 4, and 8 of study, measurements included: serum 25(OH)D₃, IGF-1, IGFBP3, leptin, and whole body composition assessed with DXA. Differences among groups were tested using mixed model ANOVA with Tukey's post hoc t-tests. No differences were observed in baseline body composition and biomarkers, nor did body weight and food intake differ over the study. At week 8, serum 25(OH)D₃ in group 3 was higher (P < .0001) compared to groups 1 and 2. At 8 weeks, lean mass (P < .05) and lean mass accretion (P < .05) were significantly higher in groups 2 and 3 compared to group 1. Serum IGF-1 concentration declined over time (P < .001) with smaller declines at week 8 in group 3 (P < .05). Serum IGFBP3 concentration was lower at week 4 in group 2 compared to groups 1 and 3. Serum leptin concentration and fat mass were not affected by diet. These results suggested that the achievement of higher vitamin D status may support a lean body phenotype without altering weight gain.

Effect of Calcium and Vitamin D Supplements as an Adjuvant Therapy to Metformin on Menstrual Cycle Abnormalities, Hormonal Profile, and IGF-1 System in Polycystic Ovary Syndrome Patients: A Randomized, Placebo-Controlled Clinical Trial

Objective

This study aims to investigate the effect of combining calcium and vitamin D supplements with metformin on menstrual cycle abnormalities, gonadotropins, and IGF-1 system in vitamin D-deficient/insufficient PCOS women.

Study Design

This is a randomized, placebo-controlled clinical trial.

Setting

This study was performed in Damascus University of Obstetrics and Gynecology Hospital and Orient Hospital, in Damascus, Syria.

Materials and Methods

Forty PCOS women with 25-OH-vitamin D < 30 ng/ml were randomly assigned to take either metformin (1500 mg/daily) plus placebo or metformin (1500 mg/daily) plus calcium (1000 mg/daily) and vitamin D₃ (6000 IU/daily) orally for 8 weeks. Serum levels of gonadotropins (luteinizing hormone (LH) and follicle-stimulating hormone (FSH)), insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein-1 (IGFBP-1) were detected at the baseline during the early follicular phase of a spontaneous or induced menstrual cycle and after 8 weeks of intervention (except for the final gonadotropins levels which were assayed from samples obtained during the early follicular phase of a spontaneous menstrual cycle).

Results

Thirty-four patients (85%) completed the study. After 8 weeks of intervention, calcium and vitamin D co-supplementation led to a significant increase in 25-OH-vitamin D levels and calcium levels in the supplementation group compared to the other group (change in 25-OH-vitamin D levels: +19.38 ± 7.78 vs +0.11 ± 4.79 ng/ml, respectively; p value=0.0001) (change in calcium levels: +0.83 ± 0.82 vs +0.01 ± 0.86 mg/dl, respectively; p value=0.014). An improvement in menstrual cycle irregularity was detected in 38.5% and 58.8% of patients in metformin-placebo group and metformin-calcium-vitamin D group, respectively; but the change was statistically significant only in the supplementation group (p value=0.002). Nevertheless, the means of changes from baseline in gonadotropins levels (serum levels of LH, FSH, and LH to FSH ratio) and the studied parameters of IGF-1 system (serum levels of IGF-1, IGFBP-1, and IGF-1 to IGFBP-I ratio) did not differ significantly between the two groups.

Conclusions

Calcium and vitamin D supplements can support metformin effect on regulation of menstrual cycle irregularity in vitamin D-deficient/insufficient PCOS patients, but this effect is not associated with any significant changes in gonadotropins or IGF-1 system. These results suggest a possible role of calcium and vitamin D supplements in managing PCOS. However, further studies are needed to identify the underlying mechanisms. The Clinical Trial Registration Number is NCT03792984.

Prenatal vitamin D and cord blood insulin-like growth factors in Dhaka, Bangladesh

Fetal growth restriction is linked to adverse health outcomes and is prevalent in low- and middle-income countries; however, determinants of fetal growth are still poorly understood. The objectives were to determine the effect of prenatal vitamin D supplementation on the insulin-like growth factor (IGF) axis at birth, to compare the concentrations of IGF-I in newborns in Bangladesh to a European reference population and to estimate the associations between IGF protein concentrations and birth size. In a randomized controlled trial in Dhaka, Bangladesh, pregnant women enrolled at 17-24 weeks of gestation were assigned to weekly oral vitamin D3 supplementation from enrolment to delivery at doses of 4200 IU/week, 16,800 IU/week, 28,000 IU/week or placebo. In this sub-study, 559 woman-infant pairs were included for analysis and cord blood IGF protein concentrations were quantified at birth. There were no significant effects of vitamin D supplementation on cord blood concentrations of IGF-I (P = 0.398), IGF-II (P = 0.525), binding proteins (BPs) IGFBP-1 (P = 0.170), IGFBP-3 (P = 0.203) or the molar ratio of IGF-I/IGFBP-3 (P = 0.941). In comparison to a European reference population, 6% of girls and 23% of boys had IGF-I concentrations below the 2.5th percentile of the reference population. IGF-I, IGF-II, IGFBP-3 and the IGF-I/IGFBP-3 ratio were positively associated with at least one anthropometric parameter, whereas IGFBP-1 was negatively associated with birth anthropometry. In conclusion, prenatal vitamin D supplementation does not alter or enhance fetal IGF pathways.

Vitamin D and growth hormone in children: a review of the current scientific knowledge

Background

Human growth is a complex mechanism that depends on genetic, environmental, nutritional and hormonal factors. The main hormone involved in growth at each stage of development is growth hormone (GH) and its mediator, insulin-like growth factor 1 (IGF-1). In contrast, vitamin D is involved in the processes of bone growth and mineralization through the regulation of calcium and phosphorus metabolism. Nevertheless, no scientific study has yet elucidated how they interact with one another, especially as a dysfunction in which one influences the other, even if numerous biochemical and clinical studies confirm the presence of a close relationship.

Main body

We reviewed and analyzed the clinical studies that have considered the relationship between vitamin D and the GH/IGF-1 axis in pediatric populations. We found two main areas of interest: the vitamin D deficiency status in patients affected by GH deficit (GHD) and the relationship between serum vitamin D metabolites and IGF-1. Although limited by some bias, from the analysis of the studies presented in the scientific literature, it is possible to hypothesize a greater frequency of hypovitaminosis D in the subjects affected by GHD, a reduced possibility of its correction with only substitution treatment with recombinant growth hormone (rGH) and an improvement of IGF-1 levels after supplementation treatment with vitamin D.

Conclusions

These results could be followed by preventive interventions aimed at reducing the vitamin D deficit in pediatric age. In addition, further research is needed to fully understand how vitamin D and growth are intertwined.

Vitamin D3 Activates Phosphatidylinositol-3-Kinase/Protein Kinase B via Insulin-Like Growth Factor-1 to Improve Testicular Function in Diabetic Rats

OBJECTIVE

In diabetes mellitus, vitamin D₃ deficiency affects sex hormone levels and male fertility; however, the mechanism leading to the disorder is unclear. This research was designed to investigate the mechanism of vitamin D₃ deficiency and hypogonadism in diabetic rats. Our aim was to assess serum vitamin D₃ levels and the relationship among vitamin D₃, insulin-like growth factor-1 (IGF-1), and testicular function.

MATERIALS AND METHODS

Rats with streptozotocin-induced diabetes were randomly divided into four groups and treated with different doses of vitamin D₃: no vitamin D₃, low (0.025 μg/kg/day), high (0.1 μg/kg/day), and high (0.1 μg/kg/day) with JB-1 (the insulin-like growth factor-1 receptor inhibitor group, 100 μg/kg/day). The groups were compared with wild-type rats, which function as the control group. Various parameters such as vitamin D₃ and IGF-1 were compared between the experimental and wild-type groups, and their correlations were determined.

RESULTS

Twelve weeks of vitamin D₃ supplementation improved the testosterone levels, as shown by the increase in the level of serum IGF-1 in diabetic rats. Phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT), which was a downstream of the signaling pathway of IGF-1, was significantly increased after vitamin D₃ treatment.

CONCLUSIONS

The study shows that vitamin D₃ may promote the expression of testosterone and improve testicular function in diabetic rats by activating PI3K/AKT via IGF-1.

Reassessing the Association between Circulating Vitamin D and IGFBP-3: Observational and Mendelian Randomization Estimates from Independent Sources

BACKGROUND

Circulating insulin-like growth factor binding protein 3 (IGFBP-3) has been associated with prostate cancer. Preclinical studies found that vitamin D regulates IGFBP-3 expression, although evidence from epidemiologic studies is conflicting.

METHODS

Mendelian randomization analyses (MR) were conducted to reassess associations between IGFBP-3 and prostate cancer risk and advanced prostate cancer using summary statistics from the PRACTICAL consortium (44,825 cases; 27,904 controls). Observational and MR analyses were conducted to assess the relationship between inactive vitamin D [25(OH)D] and IGFBP-3 using data from the ProtecT study (1,366 cases;1,071 controls) and summary statistics from the CHARGE consortium (n = 18,995).

RESULTS

The OR for prostate cancer per SD unit increase in circulating IGFBP-3 was 1.14 [95% confidence interval (CI), 1.02-1.28]. The OR for advanced prostate cancer per SD unit increase in IGFBP-3 was 1.22 (95% CI, 1.07-1.40). Observationally, a SD increase in 25(OH)D was associated with a 0.1SD (95% CI, 0.05-0.14) increase in IGFBP-3. MR analyses found little evidence for a causal relationship between circulating 25(OH)D and IGFBP-3 in the circulation.

CONCLUSIONS

This study provided confirmatory evidence that IGFBP-3 is a risk factor for prostate cancer risk and progression. Observationally, there was evidence that 25(OH)D is associated with IGFBP-3, but MR analyses suggested that these findings were unlikely to be causal. Findings may be limited by the nature of instrumentation of 25(OH)D and IGFBP-3 and the utility of circulating measures. 25(OH)D appears unlikely to be causally related to IGFBP-3 in the circulation, however, our findings do not preclude causal associations at the tissue level.

IMPACT

IGFBP-3 is a prostate cancer risk factor but 25(OH)D are unlikely to be causally related to IGFBP-3 in the circulation.

Vitamin D exposure and Risk of Breast Cancer: a meta-analysis

The relationship between vitamin D and breast cancer is still controversial. The present meta-analysis examines the effects of the 25(OH)D, 1,25(OH)2D and vitamin D intake on breast cancer risk. For this purpose, a PubMed, Scopus and Web of Science-databases search was conducted including all papers published with the keywords “breast cancer” and “vitamin D” with at least one reported relative risk (RR) or odds ratio (OR). In total sixty eight studies published between 1998 and 2018 were analyzed. Information about type of study, hormonal receptors and menopausal status was retrieved. Pooled OR or RR were estimated by weighting individual OR/RR by the inverse of their variance Our study showed a protective effect between 25 (OH) D and breast cancer in both cohort studies (RR = 0.85, 95%CI:0.74–0.98) and case-control studies (OR = 0.65, 95%CI: 0.56–0.76). However, analyzing by menopausal status, the protective vitamin D – breast cancer association persisted only in the premenopausal group (OR = 0.67, 95%CI: 0.49–0.92) when restricting the analysis to nested case-control studies. No significant association was found for vitamin D intake or 1,25(OH)2D. Conclusion: This systematic review suggests a protective relationship between circulating vitamin D (measured as 25(OH) D) and breast cancer development in premenopausal women.

IGF and IGFBP as an index for discrimination between vitamin D supplementation responders and nonresponders in overweight Saudi subjects

Vitamin D deficiency is common in the Kingdom of Saudi Arabia (KSA). Therefore, it is significant to recognize which biochemical markers modulate serum 25 hydroxyvitamin D (25(OH)D) in response to vitamin D supplementation in such a population. Our aim was to study the correlation of insulin-like growth factor (IGF) and insulin growth factor binding protein (IGFBP) with serum 25(OH)D in response to vitamin D supplementation in a Saudi population. A total of 199 (89 males/110 females) vitamin D deficient subjects (25(OH)D level <50 nmol/L), aged 40.4 ± 11.4 years, were given vitamin D supplements (50,000 IU/mL every week) for the first 2 months, then twice a month for 2 months, followed by daily 1000 IU in the last 2 months. Fasting blood samples were taken at baseline and 6 months after the final dose of vitamin D. Serum 25(OH)D, IGF-1 and IGF-2, and IGFBPs 2-5 were measured. Vitamin D response was computed for all subjects as the difference in levels of serum 25(OH)D concentration at the end of 6 months compared to baseline. After intervention, serum 25(OH)D concentration significantly increased from 35.6 nmol/L (26.6-43.5) to 61.8 nmol/L (54.8-73.3) in responder subjects (P < .01) and from 35.1 nmol/L (21.2-58.2) to 38.3 nmol/L (25.5-48.3) in nonresponders (P = .13). Subjects with lower baseline serum IGF-II, IGFBP-2, and IGF-1/IGFBP-3 ratio are more sensitive to acute vitamin D status changes. IGF1 and IGF-1/IGFBP-3 ratio significantly increased in all subjects after 6 months (P = .01). Changes in 25(OH)D was significantly associated with changes in IGFBP-2 and IGF-1/IGFBP-3 ratio in responders only. This study proposes that changes in circulating IGF-I and IGFBP-3 are modulated by vitamin D supplementation and can be taken into consideration in investigations involving vitamin D correction. Moreover, increase in serum 25(OH)D and IGF-I/IGFBP-3 molar ratio are more sensitive markers for the response to vitamin D supplementation in Saudi population.

Associations between bone and energy metabolism in cows fed diets differing in level of dietary cation-anion difference and supplemented with cholecalciferol or calcidiol

Bone-derived hormones play an important role in metabolism. This study examined the hypothesis that interactions between bone and energy metabolism, particularly those involving osteocalcin, are present in dairy cattle and have feedback mechanisms over time. Associations between metabolites in blood were examined in 32 Holstein cows blocked by parity and milk yield and randomly allocated to diets containing either 0.27 mg/kg dry matter (DM) calcidiol or cholecalciferol for an anticipated intake of 3 mg/d (120,000 IU/d) at 11 kg of DM, and positive (+130 mEq/kg DM) or negative (-130 mEq/kg DM) dietary cation-anion difference (DCAD) from 252 d of gestation to calving. Blood was sampled every 3 d, from 9 d prepartum to 30 d postpartum, and plasma concentrations of vitamin D₃, 25-hydroxyvitamin D₃, adiponectin, C-telopeptide of type 1 collagen (CTX1), glucose, insulin-like growth factor 1 (IGF1), insulin, undercarboxylated osteocalcin (uOC), and carboxylated osteocalcin (cOC) were determined. Feeding calcidiol compared with cholecalciferol increased plasma concentrations of 25-hydroxyvitamin D₃ pre- (264.2 ± 8.0 vs. 61.3 ± 8.0 ng/mL) and postpartum (170.8 ± 6.2 vs. 51.3 ± 6.2 ng/mL) but decreased concentrations of vitamin D₃ pre- (1.2 ± 0.6 vs. 14.5 ± 0.6 ng/mL) and postpartum (1.9 ± 0.4 vs. 3.2 ± 0.6 ng/mL). Prepartum, cows fed the negative DCAD diet had reduced concentrations of vitamin D₃ and glucose compared with cows fed a positive DCAD. The combination of negative DCAD and cholecalciferol reduced IGF1 concentrations prepartum. The DCAD treatment had no effect on postpartum concentrations of metabolites. Nulliparous cows had increased concentrations of OC, CTX1, IGF1, glucose, and insulin compared with parous cows. Time series analysis identified associations between metabolites on the same day and over 3-d lags up to ±9 d that suggest feedback between 25-hydroxyvitamin D₃ and vitamin D₃ in the negative lags, indicating that 25-hydroxyvitamin D₃ may exert feedback on vitamin D₃ but not vice versa. We found evidence of a feedback mechanism between vitamin D₃ and IGF1, with positive effect size (ES) on the same day and 3 d later, and negative ES 9 d later, that was more evident in cholecalciferol-fed cows. This suggests an important role of IGF1 in integrating bone metabolism with energy and protein metabolic pathways. Evidence of feedback was found between uOC and particularly cOC with IGF1, with positive ES on the same day but negative ES 6 d before and 6 d after. An association between uOC or cOC and IGF1 has not been previously identified in cattle and suggests that both uOC and cOC may have marked biological activity. Associations between OC and insulin identified in mice were not observed herein, although associations between OC and glucose were similar to those between IGF1 and glucose, supporting associations between glucose, OC, and IGF1. We provide further statistical evidence of crosstalk between vitamin D compounds, bone hormones, and energy metabolism in cattle. In particular, associations between uOC or cOC and IGF1 may provide links between prepartum diets and observations of prolonged increases in milk production and allow better control of peripartum metabolism.

Association of insulin-like growth factor-1 and IGF binding protein-3 with 25-hydroxy vitamin D in pre-pubertal and adolescent Indian girls

BACKGROUND

There is a high prevalence of vitamin D deficiency (VDD) in India. Molecular mechanisms suggest a strong relationship between vitamin D and growth factors. However, there is a paucity of literature with regard to a relationship between insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) and vitamin D particularly in subjects with VDD. The objective of the study was to assess the relationship between growth factors and serum vitamin D-parathormone (PTH) status in school girls and study the impact of vitamin D supplementation on growth factors in pre-pubertal girls with VDD.

METHODS

Our study subjects were apparently healthy school girls aged 6-18 years. The baseline height, weight, body mass index (BMI), pubertal status, serum 25-hydroxy vitamin D (25OHD), PTH, IGF-1 and IGFBP-3 were assessed in 847 girls aged 6-18 years and in 190 pre-pubertal girls with VDD following supplementation.

RESULTS

The mean age, BMI and serum 25OHD of girls were 11.5±3.2 years, 18.7±4.8 kg/m2 and 9.9±5.6 ng/mL, respectively. VDD was observed in 94.6% of girls. Unadjusted serum IGF-1 levels and IGF-1/IGFBP-3 molar ratio were significantly higher in girls with severe VDD as compared to girls with mild-to-moderate VDD. However, these differences disappeared when adjusted for age, height or sexual maturation. The serum IGF-1 and IGFBP-3 levels increased significantly post supplementation with vitamin D.

CONCLUSIONS

There were no differences in serum IGF-1 levels and the IGF-1/IGFBP-3 molar ratio among VDD categories when adjusted for age, height and sexual maturation in girls. Vitamin D supplementation resulted in a significant increase in serum IGF-1 levels in VDD pre-pubertal girls.

Vitamin D status in prepubertal children with isolated idiopathic growth hormone deficiency: effect of growth hormone therapy

Few studies, and with controversial results, analyzed vitamin D status in children before and after growth hormone (GH) treatment. Thus, we aimed to assess vitamin D status in prepubertal children with idiopathic growth hormone deficiency (GHD), and to evaluate the effect of GHD and GH treatment on vitamin D levels. Fifty prepubertal children with isolated GHD were compared with 50 controls. All were subjected to history, anthropometric assessment and measurement of 25 hydroxyvitamin D (25(OH)D), serum calcium, phosphorous, alkaline phosphatase and parathyroid hormone (PTH) at diagnosis and 1 year after GH therapy. Serum 25(OH)D levels <30 ng/mL and 20 ng/mL were defined as vitamin D insufficiency and deficiency, respectively. 25(OH)D was lower in cases than controls. Forty per cent of children with GHD were 25(OH)D insufficient and 44% deficient, while 16% were sufficient at baseline. There was a positive correlation between 25(OH)D and peak GH levels. Peak GH was a significant predictor of 25(OH)D levels. After 1 year of GH therapy, 25(OH)D increased (18.42±5.41 vs 34.5±10.1 ng/mL; P<0.001). Overall, 22% of cases remained insufficient and 24% deficient, with an increase in prevalence of children with normal levels (54%; P<0.001). 25(OH) correlated negatively with PTH (r=-0.71, P=0.01). In conclusion, hypovitaminosis D is prevalent in children with GHD and significantly improved 1 year after GH therapy. 25(OH)D should be assessed in children with GHD at diagnosis and during follow-up.

Impact of Western and Mediterranean Diets and Vitamin D on Muscle Fibers of Sedentary Rats

Background: The metabolic syndrome is associated with sarcopenia. Decreased serum levels of Vitamin D (VitD) and insulin-like growth factor (IGF)-1 and their mutual relationship were also reported. We aimed to evaluate whether different dietary profiles, containing or not VitD, may exert different effects on muscle molecular morphology. Methods: Twenty-eight male rats were fed for 10 weeks in order to detect early defects induced by different dietary regimens: regular diet (R); regular diet with vitamin D supplementation (R-DS) and regular diet with vitamin D restriction (R-DR); high-fat butter-based diets (HFB-DS and HFB-DR) with 41% energy from fat; high-fat extra-virgin olive oil-based diets (HFEVO-DS and HFEVO-DR) with 41% energy from fat. IL-1β, insulin-like growth factor (IGF)1, Dickkopf-1 (DKK-1), and VitD-receptor (VDR) expressions were evaluated by immunohistochemistry. Muscle fiber perimeter was measured by histology and morphometric analysis. Results: The muscle fibers of the HEVO-DS rats were hypertrophic, comparable to those of the R-DS rats. An inverse correlation existed between the dietary fat content and the perimeter of the muscle fibers (p < 0.01). In the HFB-DR rats, the muscle fibers appeared hypotrophic with an increase of IL-1β and a dramatic decrease of IGF-1 expression. Conclusions: High-fat western diet could impair muscle metabolism and lay the ground for subsequent muscle damage. VitD associated with a Mediterranean diet showed trophic action on the muscle fibers.

Winter vitamin D3 supplementation does not increase muscle strength, but modulates the IGF-axis in young children

PURPOSE

To explore whether muscle strength, the insulin-like growth factor axis (IGF-axis), height, and body composition were associated with serum 25-hydroxyvitamin D [25(OH)D] and affected by winter vitamin D supplementation in healthy children, and furthermore to explore potential sex differences.

METHODS

We performed a double-blind, placebo-controlled, dose-response winter trial at 55ºN. A total of 117 children aged 4-8 years were randomly assigned to either placebo, 10, or 20 µg/day of vitamin D₃ for 20 weeks. At baseline and endpoint, we measured muscle strength with handgrip dynamometer, fat mass index (FMI), fat free mass index (FFMI), height, plasma IGF-1, IGF-binding protein 3 (IGFBP-3), and serum 25(OH)D.

RESULTS

At baseline, serum 25(OH)D was positively associated with muscle strength, FFMI, and IGFBP-3 in girls only (all p < 0.01). At endpoint, baseline-adjusted muscle strength, FMI and FFMI did not differ between intervention groups. However, baseline-adjusted IGF-1 and IGFBP-3 were higher after 20 µg/day compared to placebo (p = 0.043 and p = 0.006, respectively) and IGFBP-3 was also higher after 20 µg/day compared to 10 µg/day (p = 0.011). Children tended to be taller after 20 µg/day compared to placebo (p = 0.064). No sex interactions were seen at endpoint.

CONCLUSIONS

Avoiding the winter-related decline in serum 25(OH)D may influence IGF-1 and IGFBP-3 in children. Larger trials are required to confirm these effects, and the long-term implication for linear growth.

Vitamin D in children with growth hormone deficiency due to pituitary stalk interruption syndrome

Background

Recent studies have shown a relationship between vitamin D status and growth hormone (GH) and insulin-like growth factor 1 (IGF1). The objective of this study was to assess vitamin D status in children with GH deficiency due to pituitary stalk interruption syndrome (PSIS) and to investigate the relationship between 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25 (OH) ₂D) serum levels and patient characteristics.

Methods

A retrospective single-center study of 25OHD and 1,25(OH)₂D serum concentrations in 50 children with PSIS at the initial evaluation before treatment.

Results

Mean concentrations of 33.2 ± 18.0 ng/mL for 25OHD and 74.5 ± 40.7 ng/L for 1,25(OH)₂D were measured. Additionally, 25OHD concentrations were significantly higher in boys than in girls (p = 0.04) and lower in the cold season than in the sunny season (p = 0.03). Significant positive correlations were observed between the GH peak and serum 1,25 (OH) ₂D concentrations (Rho = 0.35; p = 0.015) and the 1,25(OH)₂D/25OHD ratio (Rho = 0.29; p < 0.05). No correlation was found for other characteristics, including IGF1.

Conclusions

Vitamin D status in children with hypothalamic-pituitary deficiency due to PSIS was similar to that reported in national and European studies in healthy children. The positive significant correlations between the GH peak and the 1,25 (OH)₂D concentration as well as with the 1,25 (OH)₂D/25OHD ratio suggest that even in these patients who had severely impaired GH secretion and low IGF1 levels, an interplay between the GH/IGF1 axis and the vitamin D system still exists.

IGFBP-3 Interacts with the Vitamin D Receptor in Insulin Signaling Associated with Obesity in Visceral Adipose Tissue

Adipose tissue has traditionally only been considered as an energy storage organ. Nevertheless, the importance of this tissue in systemic physiology and, especially, in systemic inflammation has been highlighted in recent years. Adipose tissue expresses proteins related to vitamin D (VD) metabolism, and it has been proposed that it can act as a VD storage tissue. The active form of VD, 1,25-dihydroxyvitamin D3 (1,25(OH)₂D₃), is able to modify adipocyte and adipose tissue physiology via the VD receptor (VDR), decreasing the expression of pro-inflammatory cytokines in adipose tissue. Moreover, VD deficiency and VDR has been reported to be associated with obesity and diabetes. However, the results of the different studies are not conclusive. Insulin growth binding proteins (IGFBPs) have been identified in adipose tissue, but their roles are poorly understood. Therefore, the objective of this study was to analyze the plasma levels of VD and the gene expression of VDR in the adipose tissue of subjects with morbid obesity (MO) and with different degrees of insulin resistance (IR), as well as the functionality of direct interaction between IGFBP-3 and VDR, which could explain its inhibitory role in adipogenesis. Our results show a novel role of the VD system in the regulation and activation of IGFBP-3 in visceral adipose tissue (VAT) of patients with MO, as a new and alternative mechanism proposed in the insulin signaling associated with obesity.

Prognostic value of vitamin D receptor and insulin-like growth factor receptor 1 expression in triple-negative breast cancer

Aim

Triple-negative breast cancer (TNBC) is characterised by shorter overall survival and an early peak of distant recurrences with still no specific targeted treatment available. Vitamin D receptor (VDR) and insulin-like growth factor receptor 1 (IGFR) have recently been described as potential new targets for anticancer therapy, yet their roles in TNBCs are still to be explored. In this study we investigated VDR and IGFR expression in patients with TNBC and compared them with clinical and pathological parameters and survival to possibly demonstrate their prognostic and therapeutic relevance.

Methods

The study included 96 patients with TNBC. Clinical and pathological parameters were compared with the immunohistochemical expression of VDR and IGFR.

Results

Positive VDR immunostaining was present in 27% of tumours and inversely correlated with higher mitotic score, histological grade and higher proliferation index measured by Ki-67 and related to the increased overall survival (OS). Out of 96 patients with TNBC, 35.5% of tumours were IGFR positive and correlated with higher mitotic score and Ki-67, and strongly correlated with shorter disease-free survival (DFS). Patients with VDR-negative and IGF-positive tumours had significantly lower DFS and OS.

Conclusion

Approximately one third of TNBCs express VDR and/or IGFR. Their expression is linked with the recurrence of the disease and survival, which make them possible targets for treatment and a prognostic tool for dividing TNBCs into more homogeneous subgroups.

Effects of Vitamin D Supplementation on IGF-1 and Calcitriol: A Randomized-Controlled Trial

Increasing evidence suggests a possible interaction between vitamin D and insulin-like growth factor-1 (IGF-1). We aimed to investigate effects of vitamin D supplementation on IGF-1 (primary outcome) and calcitriol (1,25(OH)₂D) concentrations (secondary outcome). This is a post-hoc analysis of the Styrian Vitamin D Hypertension Trial—a single-center, double-blind, randomized, placebo-controlled trial (RCT) conducted from 2011 to 2014 at the Medical University of Graz, Austria. Two-hundred subjects with arterial hypertension and 25(OH)D concentrations <30 ng/mL were randomized to either receive 2800 IU of vitamin D daily or placebo for eight weeks. A total of 175 participants (mean ± standard deviation age, 60 ± 11 years; 49% women) with available IGF-1 concentrations were included in the present analysis. At baseline, IGF-1 concentrations were significantly correlated with 1,25(OH)₂D (r = 0.21; p = 0.005) but not with 25(OH)D (r = −0.008; p = 0.91). In the RCT, vitamin D had no significant effect on IGF-1 (mean treatment effect 3.1; 95% confidence interval −5.6 to 11.9 ng/mL; p = 0.48), but it increased 1,25(OH)₂D concentrations (mean treatment effect 9.2; 95% confidence interval 4.4 to 13.9 pg/mL; p ≤ 0.001). In this RCT, in hypertensive patients with low 25(OH)D concentrations, there was no significant effect of vitamin D supplementation on IGF-1 concentrations. However, we observed a cross-sectional correlation between 1,25(OH)₂D and IGF-1 and an increase of 1,25(OH)₂D after vitamin D supplementation.

Persistent Reduction of Circulating Myeloid Calcifying Cells in Acromegaly: Relevance to the Bone-Vascular Axis

CONTEXT

Acromegaly is a systemic disease characterized by persistent bone pathology and excess cardiovascular mortality. Despite multiple concomitant risk factors, atherosclerosis does not seem to be accelerated in acromegaly.

OBJECTIVE

To compare the levels of circulating myeloid calcifying cells (MCCs), which promote ectopic calcification and inhibit angiogenesis, in individuals with and without acromegaly.

DESIGN

Cross-sectional case-control study.

SETTING

Tertiary ambulatory referral endocrinology center.

PATIENTS

44 acromegalic patients (25 active; 19 inactive), 44 control subjects matched by age, sex, risk factors, and medications, and 8 patients cured of acromegaly.

INTERVENTION

MCCs were measured using flow cytometry based on the expression of osteocalcin (OC) and bone alkaline phosphatase (BAP) on monocytes and circulating CD34+ stem cells.

MAIN OUTCOME MEASURE

Differences in MCCs between patients and controls.

RESULTS

OC+BAP+ MCCs were severely reduced in acromegalic compared with control patients (0.17% ± 0.02% vs 1.00% ± 0.24%; P < 0.001), as were the total OC+ and BAP+ monocytic cells. Patients with inactive acromegaly and those cured of acromegaly displayed persistently reduced levels of MCCs. In the controls, but not acromegalic patients, MCCs were increased in the presence of diabetes or cardiovascular disease. A direct correlation was noted between MCCs and parathyroid hormone (r = 0.61; P < 0.0001), supporting a link between bone biology and MCCs.

CONCLUSIONS

In patients with acromegaly, the levels of MCCs are reduced and remain low, even years after a complete cure. This finding might be related to low atherosclerotic calcification and the persistence of bone pathology after acromegaly remission or cure.

Interactions of the Insulin-Like Growth Factor Axis and Vitamin D in Prostate Cancer Risk in the Prostate Cancer Prevention Trial

Some, but not all, epidemiologic studies report an association between vitamin D and prostate cancer risk. The inconsistent findings might be explained in the context of modification by members of the insulin-like growth factor (IGF) axis. Data and specimens for this nested case-control study (n = 1695 cases and n = 1682 controls) are from the Prostate Cancer Prevention Trial (PCPT). Baseline serum samples were assayed for 25(OH)D, IGF-1, IGF-2, IGFBP-2, IGFBP-3, and the ratio of IGF1:BP3, along with insulin-related markers c-peptide and leptin. The presence of prostate cancer was assessed by prostate biopsy. Multivariate logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs) for prostate cancer risk. There were no interactions between serum 25(OH)D and IGF analytes in relation to prostate cancer risk when PCPT treatment arms were combined. In the placebo arm, above median serum 25(OH)D levels were associated with increased risk of prostate cancer among men with higher IGF-2 (OR:1.33, 95% CI: 1.00–1.65), with a significant interaction between 25(OH)D and treatment arm (P_interaction = 0.04). Additionally, there was an interaction between treatment arm and serum IGFBP-3 (P_interaction = 0.03). Higher serum 25(OH)D may increase risk of prostate cancer in the presence of higher circulating IGF-2.

SERUM INSULIN-LIKE GROWTH FACTOR 1 IN LEBANESE SCHOOLCHILDREN AND ITS RELATION TO VITAMIN D AND FERRITIN LEVELS

OBJECTIVE

The aims of our study were to establish reference values for insulin-like growth factor 1 (IGF-1) in Lebanese schoolchildren and to evaluate the relationship between IGF-1 and age, sex, body mass index (BMI), vitamin D, and ferritin.

METHODS

This cross-sectional study included 952 Lebanese schoolchildren (495 boys and 457 girls) aged 8 to 18 years. Blood samples were taken from children attending 10 schools with different socio-economic status (SES). Chemiluminescent immunoassays were used for IGF-1, 25 hydroxyvitamin D (25(OH)D), testosterone, and ferritin measurements.

RESULTS

The mean age was 13.46 ± 2.80 with no significant difference according to sex. IGF-1 was correlated with age in both sexes (P<.0001); it was higher in girls compared to boys (P = .007) and peaked at the ages of 14 and 12 for boys and girls, respectively. For each age group, the median IGF-1 value was higher compared to the values provided by the kit. IGF-1 was significantly correlated with BMI in boys (r = 0.16, P<.0001) but not girls. In both sexes, IGF-1 was inversely correlated with 25(OH)D and ferritin values. After adjustment for age, BMI, and height, the correlation between IGF-1 and 25(OH)D disappeared, whereas the relationship with ferritin persisted (P<.001 for boys, P = .002 for girls). For both sexes, multivariate regression analysis revealed independent associations between IGF-1 and height, Tanner stage, and ferritin. An association was also noted in boys for BMI and testosterone.

CONCLUSION

Our results showed higher and earlier peak IGF-1 values in the pediatric Lebanese population compared to western populations. In addition, an independent inverse relationship was observed between IGF-1 and ferritin. Further studies are needed to identify the reason(s) underlying these results.

ABBREVIATIONS

BMI = body mass index CRP = C-reactive protein CV = coefficient of variation GH = growth hormone IGF-1 = insulin-like growth factor 1 25(OH)D = 25 hydroxyvitamin D SES = socio-economic status TSH = thyroid-stimulating hormone.

Proteomic analysis of the INS-1E secretome identify novel vitamin D-regulated proteins

BACKGROUND

Experimental evidence indicates that vitamin D may have a beneficial role in pancreatic β-cell function.

METHODS

In the present study, stable isotope labelling by amino acids in cell culture (SILAC) in combination with liquid chromatography-tandem mass spectrometry was used to quantitatively assess the impact of the active vitamin D metabolite, 1,25-(OH)2 D3 , on global protein expression in INS-1E cell secretome.

RESULTS

Twenty-one proteins were found up-regulated (≥1.5 fold changes) and three down-regulated (≤0.67) after treatment of INS-1E cells with 1,25-(OH)2 D3 . Up-regulation of proteins implicated in β-cell growth and proliferation, such as IGF2, IGFBP7 and gelsolin, suggest that 1,25-(OH)2 D3 has a positive effect on β-cell growth and proliferation. Moreover, modulations of several proteins implicated in prohormone processing and insulin exocytosis (IGF2, IGFBP7, Scg5, ProSAAS, Fabp5, Ptprn2 and gelsolin) appear to support the hypothesis that 1,25-(OH)2 D3 plays positive modulatory role in insulin processing and secretion.

CONCLUSIONS

Together, we reveal a number of novel vitamin D-regulated proteins that may contribute to a better understanding of the reported beneficial effects of vitamin D on pancreatic β-cells. Copyright © 2016 John Wiley & Sons, Ltd.

Serum 25-Hydroxyvitamin D3 and Mammography Density among Mexican Women

Low circulating levels of vitamin D and high mammographic density (MD) have been associated with higher risk of breast cancer. Although some evidence suggested an inverse association between circulating vitamin D and MD, no studies have investigated this association among Mexican women. We examined whether serum 25-hydroxyvitamin D3 [25(OH)D3] levels were associated with MD in a cross-sectional study nested within the large Mexican Teacher's Cohort. This study included 491 premenopausal women with a mean age of 42.9 years. Serum 25(OH)D3 levels were measured by liquid chromatography/tandem mass spectrometry. Linear regression and non-linear adjusted models were used to estimate the association of MD with serum 25(OH)D3. Median serum 25(OH)D3 level was 27.3 (23.3-32.8) (ng/ml). Forty one (8%) women had 25(OH)D3 levels in the deficient range (< 20 ng/ml). Body mass index (BMI) and total physical activity were significantly correlated with 25(OH)D3 (r = -0.109, P = 0.019 and r = 0.095, P = 0.003, respectively). In the multivariable linear regression, no significant association was observed between 25(OH)D3 levels and MD overall. However, in stratified analyses, higher serum 25(OH)D3 levels (≥27.3 ng/ml) were significantly inversely associated with percent MD among women with BMI below the median (β = -0.52, P = 0.047). Although no significant association was observed between serum 25(OH)D3 and percent MD in the overall population, specific subgroups of women may benefit from higher serum 25(OH)D3 levels.