Vitamin D and Its Metabolites Quantification in Adipose Tissues of Obese and Non-obese Patients.

Official title

Vitamin D and Its Metabolites Quantification in Adipose Tissues of Obese and Non-obese

Overview

Vitamin D (VD) is a pleiotropic hormone, involved in many physiological processes including calcium and phosphorus absorption. The VD metabolism begin to be well-known and involves a hepatic hydroxylation (mediated by enzymes, which belong to the cytochrome P450 family) leading to the production of the 25(OH)D, which corresponds to the circulating form of the VD. After circulation in blood, the 25(OH)D is submitted to a second hydroxylation in the kidney resulting to the generation of 1,25(OH)2D, the active metabolite of VD. Numerous epidemiological studies reported an inverse relationship between obesity and circulation level of 25(OH)D. Several mechanisms could explain the low level of 25(OH)D observed in obese subjects, the more classical evoked being based on sequestration and/or dilution of VD in adipose tissue (AT), the main VD storage site. However, this mechanism has never been demonstrated. In order to confirm this hypothesis, the concentration of VD and its metabolites in adipose tissue need to be quantified. The objective of this study is to determine the concentration of VD and its metabolites in adipose tissue as well as adipose tissue mass quantification and distribution (visceral or subcutaneous) to highlight putative difference of VD and its metabolites quantities between obese and non-obese patients. A quantification of VD metabolism, inflammation and lipid metabolism gene expression will be realized on biopsies. Correlations between gene expression and quantity of VD in tissue will be carrying out.

Interventions

• Biological subcutaneous and visceral adipose tissue biopsies
  Subcutaneous and visceral adipose tissue biopsies during operation
• Biological blood samples analysis
  Blood sampling is required to measure plasma cholecalciferol, calcidiol and calcitriol concentrations, as well as biological parameters of interest. Another plasma/serum tube is used to measure pro- and anti-inflammatory cytokines and adiponectin.

Primary outcome measures

• quantification of VD and its metabolites on subcutaneous and visceral adipose tissue biopsies [Time frame: 12 months]

Eligibility criteria

Inclusion criteria

• Subject with a BMI greater than 35 kg / m2 (group OB) or less than 30 kg / m² (group NO)
• Subject undergoing bariatric surgery (OB group) or abdominal surgery (group NO)

Exclusion criteria

• Regular intake of dietary supplements or vitamin supplements in the last three months
• For the subjects of the group NO:

• Malnourished patient (BMI <18.5 kg / m2, weight loss greater than 5% in 1 month or 10% in 6 months)
• Subject with an infection or inflammatory syndrome (CRP> 10 mg / L and / or white blood cells> 12000 / mm3)
• Non-cancerous subject

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Non-randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Basic science

Study locations

France · 1 center

• Assistance Publique Hôpitaux de Marseille — Marseille

Identifiers

NCT: NCT03008525 · 2016-23

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗