Effects of estradiol on the endocytic transport of vitamin D carrier protein in hepatocytes. Biochim Biophys Acta Gen Subj. 2013;1830:3421-3426. [PMID: 23416408 DOI: 10.1016/j.bbagen.2013.01.025]

Comparison of serum levels of vitamin D and vitamin D-binding protein in normal, osteopenic and osteoporotic postmenopausal women

Objective:

To compare the serum levels of vitamin D, vitamin D binding protein (VDBP) calcium and phosphate in normal, osteopenic and osteoporotic postmenopausal women categorized on the basis of bone mineral density (BMD) scores.

Methods:

A cross sectional study carried out from May 2017 to August 2018. BMD measured by Dual energy X-ray Absorptiometry categorized women (aged 20- 70 years) into normal (n=37) (T score ≥ -1.0) osteopenic (n=25) (-2.5< T score, < -1) and osteoporotic (n= 26) (T score < -2.5) according to WHO classification. Serum concentrations of vitamin D, VDBP, calcium, phosphate analyzed by enzyme linked immunosorbent assay were compared by Analysis of Variance

Results:

In normal females higher levels of vitamin D and VDBP were observed [15.82 (8 - 69.18), 469.9 (269.57 - 875.55)] vs. osteopenic [(7.45 (4.66 - 15.1), 296.05 (232.58 - 420.23)] and osteoporotic women [(7.25 (3.97 - 17.49), 272.94 (202.23 - 351.24)]; [median interquartile range]; p value < 0.0001.

Conclusion:

Vitamin D and VDBP are linked with bone health and estimation of VDBP appears to be a valuable tool for the assessment of increased bone loss and possible risks of bone fractures especially in postmenopausal women.

Deconvoluting the Biological Roles of Vitamin D-Binding Protein During Pregnancy: A Both Clinical and Theoretical Challenge

The teleological purpose of an ongoing pregnancy is to fulfill its fundamental role of a successful, uncomplicated delivery, in conjunction with an optimal intrauterine environment for the developing fetus. Vitamin D metabolism is adapted to meet both these demands during pregnancy; first by stimulation of calcium absorption for adequate intrauterine bone mineral accrual of the fetus, and second, by enhancing systemic and local maternal tolerance to paternal and fetal alloantigens. Vitamin D-binding protein (VDBP) is one of the key biomolecules that optimize vitamin D homeostasis and also contributes as an immune regulator for a healthy, ongoing pregnancy. In this regard, recent results indicate that dysregulation of VDBP equilibrium could be a risk factor for adverse fetal, maternal, and neonatal outcomes, including preeclampsia, preterm birth, and gestational diabetes. Moreover, it has been hypothesized to be also implicated in the interpretation of vitamin D status in the pregnant state. The aim of this review is to assess available literature regarding the association of VDBP with clinical outcomes during pregnancy, as a potential biomarker for future clinical practice, with a discourse on current knowledge gaps and future research agenda.

VITAMIN D BINDING PROTEIN AND 25-HYDROXYVITAMIN D LEVELS: EMERGING CLINICAL APPLICATIONS

The precursor of the active form of vitamin D, 25-hydroxyvitamin D (25(OH)D), is recognized as the optimal indicator of vitamin D status. Vitamin D3 undergoes conversion through a multitude of enzymatic reactions described within the paper, and vitamin D levels are dependent on many factors including the vitamin D binding protein (DBP). The free hormone hypothesis postulates that protein-bound hormones are not biologically available and that unbound hormones are biologically active. The majority of circulating 25(OH)D and 1,25-dihydroxyvitamin D is tightly bound to DBP and albumin, with less than 1% circulating in an unbound form. As a result, factors affecting DBP alter the interpretation of 25(OH)D levels. The aim of this review is to assess the current methodology used to measure total and free 25(OH)D, and DBP. Additionally, we analyze the effects of other endocrine hormones and disease processes on DBP levels and subsequently, the interpretation of 25(OH)D levels.

ABBREVIATIONS

CF = cystic fibrosis DBP = vitamin D binding protein ELISA = enzyme-linked immunosorbent assay ESLD = end-stage liver disease HC = hormone contraceptives iPTH = intact parathyroid hormone LC-MS = liquid chromatography-mass spectrometry MS = multiple sclerosis 25(OH)D = 25-hydroxyvitamin D PHPT = primary hyperparathyroidism RIA = radioimmunoassay.

Morphometric vertebral fractures in breast cancer patients treated with adjuvant aromatase inhibitor therapy: A cross-sectional study

BACKGROUND

The impact of long-term adjuvant therapy with aromatase inhibitors (AIs) on vertebral fracture (VF) risk is still unclear.

OBJECTIVE

In this cross-sectional study, we explored the prevalence and determinants of VFs in breast cancer (BC) patients before and during AI therapy. Each woman underwent a dual-energy X-ray absorptiometry (DXA) to evaluate bone mineral density (BMD) and identify VFs by a quantitative morphometric approach. Blood samples were collected to measure serum hormone and calcium levels.

RESULTS

We consecutively included 263 postmenopausal women with hormone receptor-positive early BC. One-hundred-sixty-nine women were AI-naïve, and 94 were AI-treated. AI-treated patients had lower BMD at total hip (p=0.01) and lumbar spine (p=0.03), higher serum vitamin D (p<0.001) and parathyroid hormone (p=0.006) values as compared to AI-naïve patients. The prevalence of VFs was 18.9% in AI-naïve patients, and 31.2% in those assessed during AI therapy (odds ratio 1.90, 95% CI 1.1-3.5, p=0.03). In AI-naïve patients, VFs were associated with older age (p=0.002) and lower BMD values at femoral neck (p=0.04) and total hip (p=0.007), whereas VFs occurred without association with any parameter analyzed in AI-treated patients. In AI-treated group, the prevalence of VFs was not significantly different between patients with osteoporosis and those with normal BMD (36.7% vs. 20.0%; p=0.31).

CONCLUSIONS

In women with early BC, AI therapy is associated with high prevalence of radiological VFs, which were shown to be independent of BMD values during the adjuvant treatment. These findings may be clinically relevant since they may lead to a change in management of AI-induced skeletal fragility. Specifically, the results of this study provide a rationale for performing a morphometric evaluation of VFs in all women undergoing treatment with AIs.

T-lymphocyte and glycemic status after vitamin D treatment in type 1 diabetes: A randomized controlled trial with sequential crossover

BACKGROUND

Type 1 diabetes mellitus (T1D) is mediated by autoaggressive T effector cells with an underlying regulatory T-cell (Treg) defect. Vitamin D deficiency is highly prevalent in T1D, which can aggravate immune dysfunction. High-dose vitamin D treatment may enhance Tregs and improve metabolism in T1D patients.

METHODS

In a randomized double-blind placebo-controlled trial with crossover design, patients received either for 3 months cholecalciferol 4000 IU/d followed by 3 months placebo or the sequential alternative. Thirty-nine T1D patients (19 women and 20 men) completed the trial.

RESULTS

Primary outcome was a change of Tregs, secondary HbA1C, and insulin demand. Effects were evaluated based on intra-individual changes between treatment and placebo periods for outcome measures. Exploratory analyses included vitamin D system variant genotyping and C-peptide measurements. Median 25(OH)D₃ increased to 38.8 ng/ml with males showing a significantly stronger increase (p = .003). T-lymphocyte profiles did not change significantly (p > 2); however, the intra-individual change of Tregs between males and females was different with a significantly stronger increase in men (p = .017), as well as between genotypes of the vitamin D receptor (Apa, Taq, and Bsm: genotypes aa, TT, and bb; p = .004-0.015). Insulin demands declined significantly (p = .003-.039) and HbA1C improved (p < .001). Random C-peptide levels were low but rising (median, 0.125 ng/ml; range, 0.02-0.3) in 6 patients. No toxicity was observed.

CONCLUSION

A daily vitamin D dose of 4000 IU for 3 months was well tolerated and enhanced Tregs in males. Glucometabolic control improved in all. Subsequent larger trials need to address ß-cell function and genotyping for individualized vitamin D doses.

Serum Antioxidants Are Associated with Serum Reproductive Hormones and Ovulation among Healthy Women

BACKGROUND

Evidence is growing that the equilibrium between reactive oxygen species and antioxidants plays a vital role in women's reproductive health.

OBJECTIVE

The objective of this study was to evaluate variations in serum antioxidant concentrations across the menstrual cycle and associations between antioxidants and reproductive hormones and anovulation among healthy women.

METHODS

The BioCycle Study, a prospective cohort, followed 259 women aged 18-44 y for up to 2 menstrual cycles. Serum fat-soluble vitamin and micronutrient (α-tocopherol, γ-tocopherol, retinol, lutein, lycopene, and β-carotene), ascorbic acid, and reproductive hormone concentrations were measured 5-8 times/cycle. We used weighted linear mixed models to assess associations between antioxidants and hormone concentrations, after adjustment for age, race, body mass index, parity, sleep, pain medication use, total energy intake, concurrent hormones, serum cholesterol, F2-isoprostanes, and other antioxidants. Generalized linear models were used to identify associations with anovulation.

RESULTS

Serum antioxidant concentrations varied across the menstrual cycle. Retinol and α-tocopherol were associated with higher estradiol [RR: 1.00 pg/mL (95% CI: 0.67, 1.34 pg/mL); RR: 0.02 pg/mL (95% CI: 0.003, 0.03 pg/mL), respectively] and testosterone [RR: 0.61 ng/dL (95% CI: 0.44, 0.78 ng/dL); RR: 0.01 ng/dL (95% CI: 0.001, 0.01 ng/dL), respectively]. Ascorbic acid was associated with higher progesterone (RR: 0.15 ng/mL; 95% CI: 0.05, 0.25 ng/mL) and with lower follicle-stimulating hormone (RR: -0.06 mIU/mL; 95% CI: -0.09, -0.03 mIU/mL). The ratio of α- to γ-tocopherol was associated with an increased risk of anovulation (RR: 1.03; 95% CI: 1.01, 1.06).

CONCLUSIONS

These findings shed new light on the intricate associations between serum antioxidants and endogenous hormones in healthy premenopausal women and support the hypothesis that concentrations of serum vitamins affect steroidogenesis even after adjustment for oxidative stress.

Gender-related differences in irritable bowel syndrome: Potential mechanisms of sex hormones

According to epidemiological studies, twice as many women as men are affected by irritable bowel syndrome (IBS) in western countries, suggesting a role for sex hormones in IBS pathophysiology. Despite growing evidence about the implications of sex hormones in IBS symptom modulation, data on mechanisms by which they influence disease development are sparse. This review aims to determine the state of knowledge about the role of sex hormones in sensorimotor dysfunctions and to address the possible interplay of sex hormones with common risk factors associated with IBS. The scientific bibliography was searched using the following keywords: irritable bowel syndrome, sex, gender, ovarian hormone, estradiol, progesterone, testosterone, symptoms, pain, sensitivity, motility, permeability, stress, immune system, brain activity, spinal, supraspinal, imaging. Ovarian hormones variations along the menstrual cycle affect sensorimotor gastrointestinal function in both healthy and IBS populations. They can modulate pain processing by interacting with neuromodulator systems and the emotional system responsible for visceral pain perception. These hormones can also modulate the susceptibility to stress, which is a pivotal factor in IBS occurrence and symptom severity. For instance, estrogen-dependent hyper-responsiveness to stress can promote immune activation or impairments of gut barrier function. In conclusion, whereas it is important to keep in mind that ovarian hormones cannot be considered as a causal factor of IBS, they arguably modulate IBS onset and symptomatology. However, our understanding of the underlying mechanisms remains limited and studies assessing the link between IBS symptoms and ovarian hormone levels are needed to improve our knowledge of the disease evolution with regard to gender. Further studies assessing the role of male hormones are also needed to understand fully the role of sex hormones in IBS. Finally, investigation of brain-gut interactions is critical to decipher how stress, ovarian hormones, and female brain processing of pain can translate into gut dysfunctions.

Xenopus embryonic epidermis as a mucociliary cellular ecosystem to assess the effect of sex hormones in a non-reproductive context

Background

How important are sexual hormones beyond their function in reproductive biology has yet to be understood. In this study, we analyzed the effects of sex steroids on the biology of the embryonic amphibian epidermis, which represents an easily amenable model of non-reproductive mucociliary epithelia (MCE). MCE are integrated systems formed by multiciliated (MC), mucus-secreting (MS) and mitochondrion-rich (MR) cell populations that are shaped by their microenvironment. Therefore, MCE could be considered as ecosystems at the cellular scale, found in a wide array of contexts from mussel gills to mammalian oviduct.

Results

We showed that the natural estrogen (estradiol, E2) and androgen (testosterone, T) as well as the synthetic estrogen (ethinyl-estradiol, EE2), all induced a significant enhancement of MC cell numbers. The effect of E2, T and EE2 extended to the MS and MR cell populations, to varying degrees. They also modified the expression profile of RNA MCE markers, and induced a range of “non-typical” cellular phenotypes, with mixed identities and aberrant morphologies, as revealed by imaging analysis through biomarker confocal detection and scanning electron microscopy. Finally, these hormones also affected tadpole pigmentation, revealing an effect on the entire cellular ecosystem of the Xenopus embryonic skin.

Conclusions

This study reveals the impact in vivo, at the molecular, cellular, tissue and organism levels, of sex steroids on non-reproductive mucociliary epithelium biogenesis, and validates the use of Xenopus as a relevant model system in this field.