176:1 I M de Araújo and others Marrow adipose tissue in 176:1 21–30 Clinical Study type 2 diabetes Marrow adipose tissue spectrum in obesity and type 2 diabetes mellitus Iana M de Araújo¹, Carlos E G Salmon², Andressa K Nahas³, Marcello H Nogueira-Barbosa¹, Jorge Elias Jr¹ and Francisco J A de Paula¹ Correspondence 1Department of Internal Medicine, Ribeirao Preto Medical School, 2Department of Physics, Faculty of should be addressed Philosophy, Sciences and Arts of Ribeirao Preto, and 3Department of Epidemiology, School of Public to F J A de Paula Health, USP, Ribeirão Preto, Sao Paulo,, Brazil Email [email protected] Abstract Objective: To assess the association of bone mass and marrow adipose tissue (MAT) with other fat depots, insulin resistance, bone remodeling markers, adipokines and glucose control in type 2 diabetes and obesity. Design and methods: The study groups comprised 24 controls (C), 26 obese (O) and 28 type 2 diabetes. Dual-energy X-ray absorptiometry was used to determine bone mineral density (BMD). Blood samples were collected for biochemical measurements. 1H Magnetic resonance spectroscopy was used to assess MAT in the L3 vertebra, and abdominal magnetic resonance imaging was used to assess intrahepatic lipids in visceral (VAT) and subcutaneous adipose tissue. Regression analysis models were used to test the association between parameters. Results: At all sites tested, BMD was higher in type 2 diabetes than in O and C subjects. The C group showed lower VAT values than the type 2 diabetes group and lower IHL than the O and type 2 diabetes groups. However, MAT was similar in the 3 groups. Osteocalcin and C-terminal telopeptide of type 1 collagen were lower in type 2 diabetes than those in C and O subjects. Moreover, at allPROOF sites, BMD was negatively ONLY associated with osteocalcin. No association was observed between MAT and VAT. No relationship was observed among MAT and HOMA-IR, leptin, adiponectin or Pref-1, but MAT was positively associated with glycated hemoglobin. Conclusions: MAT is not a niche for fat accumulation under conditions of energy surplus and type 2 diabetes, also is European Journal European of Endocrinology not associated with VAT or insulin resistance. MAT is associated with glycated hemoglobin. European Journal of Endocrinology (2017) 176, 21–30 Introduction Obesity and type 2 diabetes mellitus are part of a spectrum as visceral obesity, ectopic lipid deposition and an respectively linked as cause and consequence, embedded in altered profile in circulating levels of adipokines (1). a metabolic environment of insulin resistance generated by On the other hand, obesity and type 2 diabetes are adipose tissue and muscle. The performance of pancreatic β usually associated with normal bone mass, albeit this cells in insulin secretion determines the transition between feature does not necessarily mean that both have a normal glucose tolerance, pre-diabetes and type 2 diabetes, protective effect against fractures (2, 3, 4). Several a typical pathway followed by obese individuals. studies have shown that fracture risk is higher in obese Obesity and type 2 diabetes are also independent postmenopausal women (5) and obese men (6) and that risk factors for several disorders, including arterial fracture risk is significantly higher in type 2 diabetes (7, hypertension, dyslipidemia, macroangiopathy and 8). However, there are also data showing that, among nonalcoholic steatohepatitis. These disorders have obese individuals, fracture incidence is increased in mechanisms closely related to insulin resistance, such those with low bone mineral density (BMD) (9). www.eje-online.org © 2017 European Society of Endocrinology Published by Bioscientifica Ltd. DOI: 10.1530/EJE-16-0448 Printed in Great Britain Downloaded from Bioscientifica.com at 09/24/2021 12:58:41AM via free access 10.1530/EJE-16-0448 Clinical Study I M de Araújo and others Marrow adipose tissue in 176:1 22 type 2 diabetes The pathophysiology of bone disorder in obesity Subjects and methods and especially type 2 diabetes most likely includes specific factors that do not pertain to the universe of Subjects other chronic complications usually associated with Our study group comprised 24 controls (C: 14 females these metabolic diseases. Osteoblasts and adipocytes and 10 males), 26 obese subjects (O: 16 females and within the bone marrow originate from the same 10 males) and 28 patients with type 2 diabetes mesenchymal stem cell. Several lines of evidence (15 females and 13 males). The clinical characteristics indicate that nutritional deprivation influences the of these groups are shown in Table 1. The study was commitment of progenitor cells toward differentiation approved by the Institutional Review Board of the into osteoblasts or adipocytes, whereas far less is known Ribeirao Preto Medical School, USP (#1149/2012), about the effect of energy surplus. and all subjects gave written informed consent to The mechanisms related to higher fracture risk participate. in obesity and type 2 diabetes have not been clearly Exclusion criteria were pregnancy, presence of a delineated. A previous study reported derangement of chronic disease known to affect bone metabolism, collagen crosslinking and cortical porosity as possible abnormal thyroid functioning, hypothalamic or pituitary mechanisms of decreased bone strength in type 2 disorders, use of estrogen/oral contraceptive, hormone diabetes (10). However, there is no consensus in the replacement therapy, glucocorticoid or osteoporosis literature about the impact of insulin resistance, adipose therapy (bisphosphonates, denosumab, teriparatide, tissue distribution and fat overflow to marrow adipose strontium ranelate and calcitonin). tissue (MAT) on BMD. Russel et al. reported that BMD Due to claustrophobia, 1 control, 1 obese and has an inverse relationship with the rate of visceral 5 type 2 diabetes subjects did not undergo any MRI adipose tissue (VAT) and subcutaneous adipose tissue examination. In addition, 3 individuals in the obese (SAT) in adolescent girls (11). There are also results group and 4 in the type 2 diabetes group refused to suggesting that bone volume is negatively associated complete the abdominal examination. Serum insulin with MAT and VAT in obese individuals. On the other levels were measured in 17 C and 17 O subjects, but hand, improvement in insulin sensitivityPROOF does not notONLY in type 2 diabetes individuals due to antidiabetic necessarily lead to a beneficial effect on bone mass. For therapy. instance, both calorie restriction and treatment with thiazolidinediones have a positive effect on insulin European Journal European of Endocrinology action and glucose tolerance, but concomitantly Methods provoke bone loss and MAT enhancement. The Biochemical assessment relationship between serum insulin levels and insulin resistance and different niches of fat depot, including Blood samples were collected between 0800 and 0900 h MAT, has been recently evaluated in non-diabetic after a 12-h overnight fast. Biochemical measurements women (12). The study showed an inverse relationship (calcium, glucose, glycated hemoglobin, phosphorous, between VAT and intrahepatic lipid (IHL) and serum albumin, alkaline phosphatase, aspartate aminotransferase levels of insulin, but no relationship was observed (AST), alanine aminotransferase (ALT) and creatinine) between MAT and circulating insulin levels. Despite were performed on the day of blood collection. Calcium, these lines of evidence, the effect of insulin resistance phosphorus, alkaline phosphatase, fasting glucose, and type 2 diabetes on bone quantity and quality has albumin, AST, ALT and creatinine were determined using not been assessed. an automatic biochemistry analyzer (Wiener lab, CT The focus of this study was to assess BMD and diverse 600 i, Thermo Fisher Scientific). The levels of glycated fat depots in obese and type 2 diabetes individuals and to hemoglobin (HbA1c) were measured by high-performance investigate the association of bone mass and MAT with liquid chromatography (D10 – Hemoglobin A1C Testing VAT, IHL and insulin resistance. The second objective System, Bio Rad). The serum aliquots for the other was to analyze the association of MAT with factors parameters were stored at −70°C until the day of the assay. originating in adipocyte cell lines and osteoblasts (leptin, 25-Hydroxyvitamin D (25 (OH) D) (Liaison, DiaSorin, adiponectin, Pref-1 and osteocalcin) as well as with Saluggia VC, Italy), intact PTH (Immulite I, Siemens) metabolic control. and IGF-I (Immulite 2000 Siemens) were determined www.eje-online.org Downloaded from Bioscientifica.com at 09/24/2021 12:58:41AM via free access Clinical Study I M de Araújo and others Marrow adipose tissue in 176:1 23 type 2 diabetes Table 1 Clinical characteristics of the patients, biochemical measurements, BMD, MAT, VAT and IHL results. Control (n = 14F/10M) Obese (n = 16F/10M) Type 2 diabetes (n = 15F/13M) Age (years) 55 ± 7 52 ± 11 54 ± 8 Body mass index (kg/m²) 23.9 ± 1.7* 30.8 ± 4.0 33.0 ± 7.3 Height (m) 1.67 ± 0.1 1.64 ± 0.1 1.62 ± 0.1 Weight (kg) 67 ± 8* 83 ± 17 86 ± 16 Time of diagnostic (years) – – 11.8 ± 6.6 Glucose level (mmol/L) 5.0 ± 0.3 5.0 ± 0.4 9.1 ± 4.5† HbA1c (%) 5.6 ± 0.4 5.6 ± 0.3 9.2 ± 2.8† HbA1c (mmol/mol) 37 ± 4 38 ± 4 77 ± 31† HOMA-IR 1.73 ± 0.79 2.93 ± 2.18 – Calcium (mmol/L) 2.5 ± 0.1 2.5 ± 0.2 2.4 ± 0.1 Phosphorus (mmol/L) 1.1 ± 0.2 1.1 ± 0.2 1.2 ± 0.3 PTH (pmol/L) 3.78 ± 1.86 4.28 ± 1.86 3.78 ± 2.33 Alkaline phosphatase (U/L) 165 ± 48 188 ± 55 180