HYPERTROPHIC OBESITY IS ASSOCIATED WITH TYPE 2 DIABETES

HYPERTROPHIC OBESITY IS ASSOCIATED WITH TYPE 2 DIABETES AND IMPAIRED ADIPOGENESIS Ulf Smith, MD, Ph. D Professor of Internal Medicine, The Lundberg Laboratory for Diabetes Research, Center of Excellence for Cardiovascular and Metabolic Research, Sahlgrenska Academy, Göteborg University, Göteborg, Sweden Source: www. myhealthywaist. org

Features of the Metabolic Syndrome Interleukin-6 Low-grade inflammation ( ( Type 2 diabetes Prothrombotic state Hypertension Dyslipidemia Genetics + lifestyle Insulin resistance Source: www. myhealthywaist. org Cardiovascular disease

Vicious Circle of Adipocyte Hypertrophy, Macrophage Recruitment and Activation Increased nutrient influx Adipose hypertrophy and hyperplasia allow adipose tissue to grow Adipocytes Macrophages Larger adipocytes secrete macrophage-attracting chemokines Preadipocytes Chemokines Cytokines Free fatty acids (FFA) Increased FFA release by insulin resistant adipocytes activates macrophages Activated macrophages block preadipocyte recruitment and worsen insulin resistance in mature adipocytes, increasing FFA release and macrophage activation Adapted from Virtue S & Vidal-Puig A Biochim Biophys Acta 2010: 1801: 338 -49 Source: www. myhealthywaist. org

Hypertrophic Obesity is Associated With Local and Systemic Inflammation and Insulin Resistance Source: www. myhealthywaist. org

Steps Leading from Positive Energy Balance to Type 2 Diabetes Weight loss Positive energy balance Increasing adipose tissue storage capacity Failure in adipose tissue expansion Oxidation of lipids Storing of excess lipids in safe forms Increased lipid flux Toxic lipid to non-adipose accummulation in organs non-adipose organs Increasing beta cell number or function Beta cell compensation Beta cell failure Increased insulin demand Local inflammation Insulin resistance Hyperglycemia Adapted from Virtue S & Vidal-Puig A Biochim Biophys Acta 2010: 1801: 338 -49 Source: www. myhealthywaist. org

Adipose Morphology A 1000 500 0 20 40 60 80 100 Body fat mass (kg) 500 60 0 50 100 Body fat mass (kg) D Hyperplasia 150 Hypertrophy 50 Frequency (%) 150 Count 1000 0 120 C 100 50 0 -500 B 1500 Fat cell volume (pl) 1500 -300 -100 300 Morphology value (pl) 500 40 30 20 10 0 Men Women Nonobese Obese Adapted from Arner E et al. Diabetes 2010; 59: 105 -9 Source: www. myhealthywaist. org

Clinical Findings in Women With Adipose Hyperplasia or Hypertrophy Variables Hyperplasia (n=254) Age (years) 38 ± 10 40 ± 11 0. 01 Waist (cm) 100 ± 22 105 ± 19 0. 01 0. 895 ± 0. 085 0. 924 ± 0. 098 32. 5 ± 9. 4 33. 1 ± 8. 1 0. 37 5. 2 ± 1. 4 5. 4 ± 1. 0 0. 12 Insulin (m. U/l) 10. 1 ± 7. 8 13. 0 ± 7. 7 <0. 0001 HOMA index* 0. 25 ± 0. 33 0. 42 ± 0. 29 <0. 0001 4. 9 ± 1. 0 5. 1 ± 1. 1 0. 033 1. 40 ± 0. 39 1. 28 ± 0. 36 0. 001 Triglycerides (mmol/l) 1. 2 ± 0. 8 1. 5 ± 0. 8 0. 002 Fat cell volume (pl) 555 ± 224 825 ± 209 <0. 0001 Fat cell number (x 1010) 7. 9 ± 2. 8 5. 3 ± 1. 7 <0. 0001 Waist-to-hip ratio Body mass index (kg/m 2) Glucose (mmol/l) Cholesterol (mmol/l) HDL cholesterol (mmol/l) Hypertrophy (n=218) p value 0. 0005 Values are mean ± SD. Age was compared by unpaired t-test. Since it was slightly different between groups, the remaining values were compared by analysis of covariance with age as cofactor. * Log 10 transformed Source: www. myhealthywaist. org Adapted from Arner E et al. Diabetes 2010; 59: 105 -9

Insulin Resistance, Obesity and the Dysregulated Adipose Tissue q Hypertrophic (enlarged adipose cells) obesity is associated with a dysregulated adipose tissue with reduced local and systemic insulin sensitivity irrespective of amount of body fat. q These include several markers of reduced cellular PPAR activation (reduced APM, GLUT 4, FABP 4, etc. and increased inflammation). q Ability to recruit new subcutaneous fat cells in (hyperplastic) obesity protects against the insulin-resistant obesity phenotype (metabolic syndrome). APM: adipocyte-specific secretory protein FABP 4: fatty acid binding protein 4 GLUT 4: glucose transporter type 4 PPAR : peroxisome proliferator-activated receptor gamma Source: www. myhealthywaist. org

Reduced IRS-1 in Adipocytes BLOT: IRS-1 anti-IRS-1 anti-p 85 anti-IRS-1 (c-t) ← IRS-1 anti-IRS-1 (NH 2 -t) ← IRS-1 anti-IR ← p 85 anti-p 85 C anti-syp C Type 2 diabetes Type 2 Type 1 diabetes anti-IR: insulin receptor antibody anti-IRS-1: insulin receptor substrate-1 antibody C: healthy control IRS-1: insulin receptor substrate-1 Copyright (1997) National Academy of Sciences, U. S. A. Proc Natl Acad Sci U S A 1997; 94: 4171 -5 Source: www. myhealthywaist. org

Reduced GLUT 4 in Adipocytes BLOT: GLUT 4 C Type 2 diabetes C: healthy control GLUT 4: glucose transporter type 4 Source: www. myhealthywaist. org Type 1 diabetes From Smith U Unpublished data

Enlarged Abdominal Adipose Cells in Individuals With Low IRS-1 Expression Low IRS-1/ GLUT 4 (n=20) Normal IRS-1/ GLUT 4 (n=52) p value Cell size (µg/cell) 0. 55 ± 0. 03 0. 42 ± 0. 02 <0. 001 Body mass index (kg/m 2) 25. 8 ± 0. 6 24. 6 ± 0. 4 NS Waist-to-hip ratio 0. 92 ± 0. 02 0. 84 ± 0. 01 <0. 001 Markers of impaired differentiation is ~4 -times more frequent in first-degree relatives vs. nongenetic predisposition Question: Is impaired adipose cell differentiation with enlarged cells a consequence of genetic predisposition for type 2 diabetes and associated with insulin resistance? GLUT 4: glucose transporter type 4 IRS-1: insulin receptor substrate-1 Adapted from Carvalho E et al. FASEB J 2001; 15: 1101 -3 and Jansson PA et al. FASEB J 2003; 17: 1434 -40 Source: www. myhealthywaist. org

Comparison of Lean and Overweight Individuals With or Without a Genetic Predisposition for Type 2 Diabetes or Overweight/Obesity Lean individuals Genetic predisposition Type 2 diabetes Measure Yes (n=17) Overweight or obesity No (n=65) Yes (n=56) No (n=26) Age (years) 38 ± 2 33 ± 1 35 ± 1 32 ± 1 Waist circumference (cm) 82 ± 2(*) 79 ± 1 80 ± 1* 77 ± 1 22. 9 ± 0. 4 22. 4 ± 0. 2 22. 7 ± 0. 2 22. 2 ± 0. 3 19 ± 1 18 ± 1 17 ± 1 511 ± 45** 400 ± 19 431 ± 23 407 ± 30 64 ± 38** -37 ± 18 -15 ± 21 -18 ± 28 HOMA index 1. 62 ± 0. 24* 1. 17 ± 0. 08 1. 26 ± 0. 09 1. 26 ± 0. 16 HDL cholesterol (mmol/l) 1. 39 ± 0. 10* 1. 62 ± 0. 05 1. 56 ± 0. 07 1. 60 ± 0. 07 Apolipoprotein AI (mmol/l) 1. 37 ± 0. 07 1. 48 ± 0. 05 1. 43 ± 0. 05 1. 51 ± 0. 07 Apolipoprotein B (mmol/l) 0. 94 ± 0. 06(*) 0. 82 ± 0. 04 0. 86 ± 0. 04 0. 84 ± 0. 06 Apo B/apo AI 0. 72 ± 0. 07* 0. 57 ± 0. 03 0. 63 ± 0. 04 0. 56 ± 0. 04 BMI (kg/m 2) Body fat mass (kg) Fat cell volume (pl) Delta value (pl) Values are mean ± SE. Significances (by t-test) were only calculated between groups with heredity or not for type 2 diabetes and between groups with heredity or not for overweight or obesity. (*) 0. 05<p<0. 1, *p<0. 05, **p=0. 01 Adapted from Arner P et al. PLo. S One 2011; 6: e 18284 Source: www. myhealthywaist. org

Adipocyte Hypertrophy, Fatty Liver and Metabolic Risk Factors in South Asians: The Molecular Study of Health and Risk in Ethnic Groups (mol-SHARE) Sonia S. Anand, Mark A. Tarnopolsky, Shirya Rashid, Karleen M. Schulze, Dipika Desai, Andrew Mente, Sandy Rao, Salim Yusuf, Hertzel C. Gerstein, and Arya M. Sharma Conclusions South Asians have an increased adipocyte area compared to white Caucasians. This difference accounts for the ethnic differences in insulin, HDL cholesterol, adiponectin, and ectopic fat deposition in the liver. Adapted from Anand SS et al. PLo. S One 2011; 6: e 22112 Source: www. myhealthywaist. org

Influence of Adipose Tissue Characteristics on Ethnic Differences in Adiponectin, Insulin and HDL cholesterol South Asian European Adiponectin (µg/ml) 9 p=0. 002 p=0. 15 Fasting insulin-In (pmol/l) 8 4. 5 7 4. 0 6 3. 5 5 N=108 N=79 Age + sex + BMI + adipocyte cell area HDL cholesterol (mmol/l) 5. 0 p=0. 006 p=0. 13 1. 5 p=0. 03 p=0. 84 1. 0 0. 5 0. 0 3. 0 N=101 N=79 Age + sex + BMI + adipocyte cell area N=108 N=79 Age + sex + BMI + adipocyte cell area Adapted from Anand SS et al. PLo. S One 2011; 6: e 22112 Source: www. myhealthywaist. org

Influence of Adipose Tissue Characteristics on Ethnic Differences in Liver Fat South Asian European 14 12 Liver fat (%) p=0. 005 10 p=0. 04 8 p=0. 30 6 4 2 0 N=95 N=74 N=55 Age + sex + BMI + adipocyte cell area + deep/superficial fat ratio Adapted from Anand SS et al. PLo. S One 2011; 6: e 22112 Source: www. myhealthywaist. org

Lower Capacity of South Asians to Store Fat in Subcutaneous Adipocytes Compared to White Caucasians Visceral depot Excess energy No change in cardiometabolic factors Superficial subcutaneous adipose tissue Deep subcutaneous adipose tissue Adipocyte hyperplasia No liver fat Abnormal response to chronic overnutrition (e. g. in South Asians vs. white Caucasians) Visceral fat Excess energy Change in cardiometabolic factors: Fatty acid flux Superficial subcutaneous adipose tissue Deep subcutaneous adipose tissue Adipocyte hypertrophy ↓ Adiponectin Source: www. myhealthywaist. org Liver fat accumulation ↑ Insulin ↑ Glucose ↑ Triglycerides ↓ HDL cholesterol ↑ C-reactive protein ↑ Blood pressure Adapted from Anand SS et al. PLo. S One 2011; 6: e 22112

Summary q Genetic predisposition for type 2 diabetes is associated with a restricted adipogenesis and, thus, hypertrophic obesity even in the absence of obesity (body mass index). § Due to lack of precursor cells to undergo adipogenesis? (Diabetes 2009; 58: 15507) § Or inadequate signalling/activation of adipogenesis? Prime candidates: § BMP 4 induces committment of precursor cells into the adipocyte lineage. § Canonical Wnt prevents PPAR activation and differentiation of preadipocytes. BMP 4: bone morphogenetic protein 4 PPAR : peroxisome proliferator-activated receptor gamma Source: www. myhealthywaist. org

Canonical Wnt Signalling Regulates Mesenchymal Stem Cell Fate Wnt + Mesenchymal stem cells Myoblasts Wnt - + Preadipocytes Osteoblasts BMP 4: bone morphogenetic protein 4 C/EBPα: CCAAT/enhancer binding protein alpha C/EBPδ/β: CCAAT/enhancer ninding protein delta/beta PPAR : peroxisome proliferator-activated receptor gamma TNF- : tumor necrosis factor-alpha BMP 4 TNF- + Preadipocyte genes Adipogenic stimuli Wnt β-catenin C/EBPδ/β PPARγ C/EBPα Adipocytes Source: www. myhealthywaist. org Adipocyte genes Adapted from Christodoulides C et al. Trends Endocrinol Metab 2009; 20: 16 -24

Local Factors Regulates Adipogenesis A) Nutritional deprivation Preadipocyte Adipogenesis Adipocyte hyperplasia B) Overnutrition Adipocyte Preadipocyte Adipogenesis Ectopic lipid accumulation (liver and muscle) C) Chronic overnutrition Hypertrophic adipocytes Preadipocyte Adipose tissue inflammation Adipogenesis Source: www. myhealthywaist. org Adapted from Christodoulides C et al. Trends Endocrinol Metab 2009; 20: 16 -24

A Model for the Wnt Activation of the Beta-Catenin Signalling Pathway With Wnt Signal Wnt LRP Frizzled Active dishevelled Axin Inactive GSK-3β Stable β-catenin APC Unphosphorylated β-catenin migrates to nucleus and displaces groucho Groucho LEF-1/TCF Transcription From Smith U Unpublished data Source: www. myhealthywaist. org

Impaired Adipogenesis in Hypertrophic Obesity 140 Cell size (µm) 120 100 80 60 40 0 1 2 3 4 5 Oil Red O (fold change) Adapted from Gustafson B & Smith U Diabetes 2012: 61; 1217 -24 Source: www. myhealthywaist. org

Hypertrophic Obesity q Is not due to lack of adipogenic precursor cells but to inappropriate inhibitory signalling. q BMP 4 plays a role for precursor cell commitment and differentiation. q Wnt activation prevents the effect of BMP 4 and is inappropriately activated in hypertrophic obesity. BMP 4: bone morphogenetic protein 4 Source: www. myhealthywaist. org

Conclusions 1. Genetic predisposition for type 2 diabetes is associated with a restricted adipogenesis and hypertrophic obesity. 2. The restricted adipogenesis in hypertrophic obesity is not due to lack of precursor cells but to inadequate signalling/activation mainly involving inadequate suppression of canonical Wnt. Source: www. myhealthywaist. org

Source: www. myhealthywaist. org