High‐salt intake induced visceral adipose tissue hypoxia and its association with circulating monocyte subsets in humans

• Published in: Obesity (Silver Spring, Md.) Md.), 2014-06, Vol.22 (6), p.1470-1476
• Main Authors: Zhou, Xin, Yuan, Fei, Ji, Wen‐Jie, Guo, Zhao‐Zeng, Zhang, Ling, Lu, Rui‐Yi, Liu, Xing, Liu, Hong‐Mei, Zhang, Wen‐Cheng, Jiang, Tie‐Min, Zhang, Zhuoli, Li, Yu‐Ming
• Format: Article
• Language: English
• Subjects: Abdomen; Adult; Body fat; Body Mass Index; Deoxyribonucleic acid; Diet, Sodium-Restricted; DNA; Feasibility Studies; Female; Flow cytometry; Gene expression; Healthy Volunteers; Heart attacks; Humans; Hypoxia; Hypoxia - pathology; Insulin; Insulin resistance; Intra-Abdominal Fat - metabolism; Liver; Magnetic Resonance Imaging; Male; Metabolic disorders; Methods; Monocytes - cytology; NMR; Nuclear magnetic resonance; Oxidative stress; Oxygen - blood; Renin-Angiotensin System; Sodium Chloride, Dietary - administration & dosage; Sodium Chloride, Dietary - adverse effects; Waist-Hip Ratio
• ISSN: 1930-7381; 1930-739X
• DOI: 10.1002/oby.20716

Objective To investigate the feasibility of blood oxygen level dependent magnetic resonance imaging (BOLD‐MRI) in evaluating human visceral adipose tissue (AT) oxygenation induced by salt loading/depletion and its association with changes in circulating monocyte subsets. Methods A dietary intervention study was performed in 23 healthy volunteers beginning with a 3‐day usual diet followed by a 7‐day high‐salt diet (≥15 g NaCl/day) and a 7‐day low‐salt diet (≤5 g NaCl/day). BOLD‐MRI was used to evaluate oxygenation in perirenal AT. Results Salt loading led to a consistent AT hypoxia (increase in the R2* signal, 25.2 ± 0.90 s−1 vs. baseline 21.5 ± 0.71 s−1, P < 0.001) and suppression of circulating renin‐angiotensin‐aldosterone system (RAAS), as well as an expansion of the CD14++CD16+ monocytes and monocyte pro‐inflammatory activation. In salt depletion phase, the hypoxic state of AT and the expanded CD14++CD16+ monocyte pool were regressed to baseline levels, accompanied by a rebound activation of RAAS. Moreover, AT oxygenation level was positively correlated with the CD14++CD16+ monocytes (r = 0.419, P < 0.001). Conclusions This work provides proof‐of‐principle evidence supporting the feasibility of BOLD‐MRI in monitoring visceral AT oxygenation in humans induced by dietary salt loading/depletion. In addition, the CD14++CD16+ monocytes may participate in the pathogenesis of high‐salt intake induced AT hypoxia.