In the Hepobster and NASH study, liver biopsies were obtained during surgery and immediately processed. After formalin fixation, biopsies were routinely processed and stained with hematoxylin- eosin and Masson trichrome. An experienced pathologist from the Department of Pathology at Ghent University Hospital established the histological diagnosis of NAFLD according to the scoring system of Kleiner et al. [195], blinded to characteristics of participants. At least 6 complete portal tracts in liver specimen are required for adequate histological evaluation. Steatosis was assessed as the percentage of hepatocytes containing fat droplets, with a minimum of 5 %. NAS has been introduced as the unweighted sum of scores for the intensity of steatosis (0-3), lobular inflammation (0-3), and hepatocellular ballooning (0-2), ranging from 0 to 8. NAS of 0 – 2 was considered as SS and scores of 5 or greater were considered as definite NASH. Intermediate scores of 3 or 4 were considered as borderline NASH. Additionally, stage of fibrosis was also scored using a 4-point scale.
48
REFERENCES
1. Despres J. P. and Lemieux I., Abdominal obesity and metabolic syndrome. Nature, 2006. 444(7121): p. 881-887.
2. organization World health, Obesity and overweight, 2015.
3. Virtue S. and Vidal-Puig A., Adipose tissue expandability, lipotoxicity and the Metabolic Syndrome--an allostatic perspective. Biochim Biophys Acta, 2010. 1801(3): p. 338-349.
4. Wells J. C., Sexual dimorphism of body composition. Best Pract Res Clin Endocrinol Metab, 2007. 21(3): p. 415-430.
5. Lemieux S., Prud'homme D., Bouchard C., Tremblay A., and Despres J. P., Sex differences in the relation of visceral adipose tissue accumulation to total body fatness. Am J Clin Nutr, 1993.
58(4): p. 463-467.
6. Vermeulen A., Goemaere S., and Kaufman J. M., Testosterone, body composition and aging. J Endocrinol Invest, 1999. 22(5 Suppl): p. 110-116.
7. Seip M. and Trygstad O., Generalized lipodystrophy, congenital and acquired (lipoatrophy). Acta Paediatr Suppl, 1996. 413: p. 2-28.
8. Avram A. S., Avram M. M., and James W. D., Subcutaneous fat in normal and diseased states: 2. Anatomy and physiology of white and brown adipose tissue. J Am Acad Dermatol, 2005. 53(4): p. 671-683.
9. Marin P., Andersson B., Ottosson M., Olbe L., Chowdhury B., Kvist H., Holm G., Sjostrom L., and Bjorntorp P., The morphology and metabolism of intraabdominal adipose tissue in men. Metabolism, 1992. 41(11): p. 1242-1248.
10. Shadid S., Koutsari C., and Jensen M. D., Direct free fatty acid uptake into human adipocytes in vivo: relation to body fat distribution. Diabetes, 2007. 56(5): p. 1369-1375.
11. You T., Wang X., Murphy K. M., Lyles M. F., Demons J. L., Yang R., Gong D. W., and Nicklas B. J., Regional adipose tissue hormone/cytokine production before and after weight loss in abdominally obese women. Obesity (Silver Spring), 2014. 22(7): p. 1679-1684.
12. Jensen M. D. and Johnson C. M., Contribution of leg and splanchnic free fatty acid (FFA) kinetics to postabsorptive FFA flux in men and women. Metabolism, 1996. 45(5): p. 662-666.
13. Banerji M. A., Lebowitz J., Chaiken R. L., Gordon D., Kral J. G., and Lebovitz H. E., Relationship of visceral adipose tissue and glucose disposal is independent of sex in black NIDDM subjects. Am J Physiol, 1997. 273(2 Pt 1): p. E425-432.
14. Goodpaster B. H., Kelley D. E., Wing R. R., Meier A., and Thaete F. L., Effects of weight loss on regional fat distribution and insulin sensitivity in obesity. Diabetes, 1999. 48(4): p. 839-847. 15. Lebovitz H. E. and Banerji M. A., Point: visceral adiposity is causally related to insulin resistance.
Diabetes Care, 2005. 28(9): p. 2322-2325.
16. Despres J. P., Intra-abdominal obesity: an untreated risk factor for Type 2 diabetes and cardiovascular disease. J Endocrinol Invest, 2006. 29(3 Suppl): p. 77-82.
17. Wajchenberg B. L., Subcutaneous and visceral adipose tissue: their relation to the metabolic syndrome. Endocr Rev, 2000. 21(6): p. 697-738.
18. Tchoukalova Y. D., Votruba S. B., Tchkonia T., Giorgadze N., Kirkland J. L., and Jensen M. D., Regional differences in cellular mechanisms of adipose tissue gain with overfeeding. Proc Natl Acad Sci U S A, 2010. 107(42): p. 18226-18231.
19. Wellens R. I., Roche A. F., Khamis H. J., Jackson A. S., Pollock M. L., and Siervogel R. M., Relationships between the Body Mass Index and body composition. Obes Res, 1996. 4(1): p. 35- 44.
49
20. Cornier M. A., Despres J. P., Davis N., Grossniklaus D. A., Klein S., Lamarche B., Lopez-Jimenez F., Rao G., St-Onge M. P., Towfighi A., and Poirier P., Assessing adiposity: a scientific statement from the American Heart Association. Circulation, 2011. 124(18): p. 1996-2019.
21. Jensen M. D., Kanaley J. A., Reed J. E., and Sheedy P. F., Measurement of abdominal and visceral fat with computed tomography and dual-energy x-ray absorptiometry. Am J Clin Nutr, 1995.
61(2): p. 274-278.
22. Naboush A. and Hamdy O., Measuring visceral and hepatic fat in clinical practice and clinical research. Endocr Pract, 2013. 19(4): p. 587-589.
23. Tchernof A. and Despres J. P., Pathophysiology of human visceral obesity: an update. Physiol Rev, 2013. 93(1): p. 359-404.
24. Lafontan M. and Langin D., Lipolysis and lipid mobilization in human adipose tissue. Prog Lipid Res, 2009. 48(5): p. 275-297.
25. Boone A. N., Chan A., Kulpa J. E., and Brownsey R. W., Bimodal activation of acetyl-CoA carboxylase by glutamate. J Biol Chem, 2000. 275(15): p. 10819-10825.
26. Desvergne B., Michalik L., and Wahli W., Transcriptional regulation of metabolism. Physiol Rev, 2006. 86(2): p. 465-514.
27. Saltiel A. R. and Kahn C. R., Insulin signalling and the regulation of glucose and lipid metabolism. Nature, 2001. 414(6865): p. 799-806.
28. Petersen O. H. and Findlay I., Electrophysiology of the pancreas. Physiol Rev, 1987. 67(3): p. 1054-1116.
29. Jung U. J. and Choi M. S., Obesity and its metabolic complications: the role of adipokines and the relationship between obesity, inflammation, insulin resistance, dyslipidemia and nonalcoholic fatty liver disease. Int J Mol Sci, 2014. 15(4): p. 6184-6223.
30. Lehr S., Hartwig S., Lamers D., Famulla S., Muller S., Hanisch F. G., Cuvelier C., Ruige J., Eckardt K., Ouwens D. M., Sell H., and Eckel J., Identification and validation of novel adipokines released from primary human adipocytes. Mol Cell Proteomics, 2012. 11(1): p. M111 010504.
31. Weisberg S. P., McCann D., Desai M., Rosenbaum M., Leibel R. L., and Ferrante A. W., Jr., Obesity is associated with macrophage accumulation in adipose tissue. J Clin Invest, 2003. 112(12): p. 1796-1808.
32. Hauner H., Secretory factors from human adipose tissue and their functional role. Proc Nutr Soc, 2005. 64(2): p. 163-169.
33. Deng Y. and Scherer P. E., Adipokines as novel biomarkers and regulators of the metabolic syndrome. Ann N Y Acad Sci, 2010. 1212: p. E1-E19.
34. Hube F., Lietz U., Igel M., Jensen P. B., Tornqvist H., Joost H. G., and Hauner H., Difference in leptin mRNA levels between omental and subcutaneous abdominal adipose tissue from obese humans. Horm Metab Res, 1996. 28(12): p. 690-693.
35. Van Harmelen V., Reynisdottir S., Eriksson P., Thorne A., Hoffstedt J., Lonnqvist F., and Arner P., Leptin secretion from subcutaneous and visceral adipose tissue in women. Diabetes, 1998. 47(6): p. 913-917.
36. Li J., Papadopoulos V., and Vihma V., Steroid biosynthesis in adipose tissue. Steroids, 2015. 103: p. 89-104.
37. Ng M., Fleming T., Robinson M., Thomson B., Graetz N., Margono C., et al. Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet, 2014. 384(9945): p. 766-781.
38. Organization World Health, Obesity and Overweight fact sheet. 2014.
39. Eckel R. H., Grundy S. M., and Zimmet P. Z., The metabolic syndrome. Lancet, 2005. 365(9468): p. 1415-1428.
50
40. Cornier M. A., Dabelea D., Hernandez T. L., Lindstrom R. C., Steig A. J., Stob N. R., Van Pelt R. E., Wang H., and Eckel R. H., The metabolic syndrome. Endocr Rev, 2008. 29(7): p. 777-822.
41. Mozumdar A. and Liguori G., Persistent increase of prevalence of metabolic syndrome among U.S. adults: NHANES III to NHANES 1999-2006. Diabetes Care, 2011. 34(1): p. 216-219.
42. Miller J. M., Kaylor M. B., Johannsson M., Bay C., and Churilla J. R., Prevalence of metabolic syndrome and individual criterion in US adolescents: 2001-2010 National Health and Nutrition Examination Survey. Metab Syndr Relat Disord, 2014. 12(10): p. 527-532.
43. Alexander C. M., Landsman P. B., Teutsch S. M., and Haffner S. M., NCEP-defined metabolic syndrome, diabetes, and prevalence of coronary heart disease among NHANES III participants age 50 years and older. Diabetes, 2003. 52(5): p. 1210-1214.
44. Galassi A., Reynolds K., and He J., Metabolic syndrome and risk of cardiovascular disease: a meta-analysis. Am J Med, 2006. 119(10): p. 812-819.
45. Wilson P. W., D'Agostino R. B., Parise H., Sullivan L., and Meigs J. B., Metabolic syndrome as a precursor of cardiovascular disease and type 2 diabetes mellitus. Circulation, 2005. 112(20): p. 3066-3072.
46. Teixeira T. F., Alves R. D., Moreira A. P., and Peluzio Mdo C., Main characteristics of metabolically obese normal weight and metabolically healthy obese phenotypes. Nutr Rev, 2015.
73(3): p. 175-190.
47. Spalding K. L., Arner E., Westermark P. O., Bernard S., Buchholz B. A., Bergmann O., Blomqvist L., Hoffstedt J., Naslund E., Britton T., Concha H., Hassan M., Ryden M., Frisen J., and Arner P., Dynamics of fat cell turnover in humans. Nature, 2008. 453(7196): p. 783-787.
48. Singh P., Somers V. K., Romero-Corral A., Sert-Kuniyoshi F. H., Pusalavidyasagar S., Davison D. E., and Jensen M. D., Effects of weight gain and weight loss on regional fat distribution. Am J Clin Nutr, 2012. 96(2): p. 229-233.
49. Trayhurn P., Hypoxia and adipocyte physiology: implications for adipose tissue dysfunction in obesity. Annu Rev Nutr, 2014. 34: p. 207-236.
50. Manu P., Ionescu-Tirgoviste C., Tsang J., Napolitano B. A., Lesser M. L., and Correll C. U., Dysmetabolic signals in "metabolically healthy" obesity. Obes Res Clin Pract, 2012. 6(1): p. e1- e90.
51. Jensen M. D., Is visceral fat involved in the pathogenesis of the metabolic syndrome? Human model. Obesity (Silver Spring), 2006. 14 Suppl 1: p. 20S-24S.
52. Karpe F., Dickmann J. R., and Frayn K. N., Fatty acids, obesity, and insulin resistance: time for a reevaluation. Diabetes, 2011. 60(10): p. 2441-2449.
53. Samuel V. T., Petersen K. F., and Shulman G. I., Lipid-induced insulin resistance: unravelling the mechanism. Lancet, 2010. 375(9733): p. 2267-2277.
54. Hotamisligil G. S., Inflammation and metabolic disorders. Nature, 2006. 444(7121): p. 860-867. 55. Lumeng C. N. and Saltiel A. R., Inflammatory links between obesity and metabolic disease.
Journal of Clinical Investigation, 2011. 121(6): p. 2111-2117.
56. Shi H., Kokoeva M. V., Inouye K., Tzameli I., Yin H., and Flier J. S., TLR4 links innate immunity and fatty acid-induced insulin resistance. J Clin Invest, 2006. 116(11): p. 3015-3025.
57. Stefan N. and Haring H. U., The metabolically benign and malignant fatty liver. Diabetes, 2011. 60(8): p. 2011-2017.
58. Grant R. W. and Dixit V. D., Adipose tissue as an immunological organ. Obesity (Silver Spring), 2015. 23(3): p. 512-518.
59. Kershaw E. E. and Flier J. S., Adipose tissue as an endocrine organ. J Clin Endocrinol Metab, 2004. 89(6): p. 2548-2556.
60. Diez J. J. and Iglesias P., The role of the novel adipocyte-derived hormone adiponectin in human disease. Eur J Endocrinol, 2003. 148(3): p. 293-300.
51
61. Friedman J. M. and Halaas J. L., Leptin and the regulation of body weight in mammals. Nature, 1998. 395(6704): p. 763-770.
62. Considine R. V., Sinha M. K., Heiman M. L., Kriauciunas A., Stephens T. W., Nyce M. R., Ohannesian J. P., Marco C. C., McKee L. J., Bauer T. L., and et al., Serum immunoreactive-leptin concentrations in normal-weight and obese humans. N Engl J Med, 1996. 334(5): p. 292-295. 63. Lord G. M., Matarese G., Howard J. K., Baker R. J., Bloom S. R., and Lechler R. I., Leptin
modulates the T-cell immune response and reverses starvation-induced immunosuppression. Nature, 1998. 394(6696): p. 897-901.
64. Ouchi N., Parker J. L., Lugus J. J., and Walsh K., Adipokines in inflammation and metabolic disease. Nat Rev Immunol, 2011. 11(2): p. 85-97.
65. Hotamisligil G. S., Shargill N. S., and Spiegelman B. M., Adipose expression of tumor necrosis factor-alpha: direct role in obesity-linked insulin resistance. Science, 1993. 259(5091): p. 87-91. 66. McArdle M. A., Finucane O. M., Connaughton R. M., McMorrow A. M., and Roche H. M.,
Mechanisms of obesity-induced inflammation and insulin resistance: insights into the emerging role of nutritional strategies. Front Endocrinol (Lausanne), 2013. 4: p. 52.
67. Huber J., Kiefer F. W., Zeyda M., Ludvik B., Silberhumer G. R., Prager G., Zlabinger G. J., and Stulnig T. M., CC chemokine and CC chemokine receptor profiles in visceral and subcutaneous adipose tissue are altered in human obesity. J Clin Endocrinol Metab, 2008. 93(8): p. 3215-3221. 68. Bluher M., Adipose tissue dysfunction in obesity. Exp Clin Endocrinol Diabetes, 2009. 117(6): p.
241-250.
69. Sell H., Laurencikiene J., Taube A., Eckardt K., Cramer A., Horrighs A., Arner P., and Eckel J., Chemerin is a novel adipocyte-derived factor inducing insulin resistance in primary human skeletal muscle cells. Diabetes, 2009. 58(12): p. 2731-2740.
70. Goralski K. B., McCarthy T. C., Hanniman E. A., Zabel B. A., Butcher E. C., Parlee S. D., Muruganandan S., and Sinal C. J., Chemerin, a novel adipokine that regulates adipogenesis and adipocyte metabolism. J Biol Chem, 2007. 282(38): p. 28175-28188.
71. Takahashi M., Takahashi Y., Takahashi K., Zolotaryov F. N., Hong K. S., Kitazawa R., Iida K., Okimura Y., Kaji H., Kitazawa S., Kasuga M., and Chihara K., Chemerin enhances insulin signaling and potentiates insulin-stimulated glucose uptake in 3T3-L1 adipocytes. FEBS Lett, 2008. 582(5): p. 573-578.
72. Wittamer V., Franssen J. D., Vulcano M., Mirjolet J. F., Le Poul E., Migeotte I., Brezillon S., Tyldesley R., Blanpain C., Detheux M., Mantovani A., Sozzani S., Vassart G., Parmentier M., and Communi D., Specific recruitment of antigen-presenting cells by chemerin, a novel processed ligand from human inflammatory fluids. J Exp Med, 2003. 198(7): p. 977-985.
73. Zabel B. A., Silverio A. M., and Butcher E. C., Chemokine-like receptor 1 expression and chemerin- directed chemotaxis distinguish plasmacytoid from myeloid dendritic cells in human blood. J Immunol, 2005. 174(1): p. 244-251.
74. de Souza Batista C. M., Yang R. Z., Lee M. J., Glynn N. M., Yu D. Z., Pray J., Ndubuizu K., Patil S., Schwartz A., Kligman M., Fried S. K., Gong D. W., Shuldiner A. R., Pollin T. I., and McLenithan J. C., Omentin plasma levels and gene expression are decreased in obesity. Diabetes, 2007. 56(6): p. 1655-1661.
75. Greulich S., Chen W. J., Maxhera B., Rijzewijk L. J., van der Meer R. W., Jonker J. T., et al. Cardioprotective properties of omentin-1 in type 2 diabetes: evidence from clinical and in vitro studies. PLoS One, 2013. 8(3): p. e59697.
76. Yang R. Z., Lee M. J., Hu H., Pray J., Wu H. B., Hansen B. C., Shuldiner A. R., Fried S. K., McLenithan J. C., and Gong D. W., Identification of omentin as a novel depot-specific adipokine in human adipose tissue: possible role in modulating insulin action. Am J Physiol Endocrinol Metab, 2006. 290(6): p. E1253-1261.
52
77. Zhong X., Li X., Liu F., Tan H., and Shang D., Omentin inhibits TNF-alpha-induced expression of adhesion molecules in endothelial cells via ERK/NF-kappaB pathway. Biochem Biophys Res Commun, 2012. 425(2): p. 401-406.
78. Yamawaki H., Kuramoto J., Kameshima S., Usui T., Okada M., and Hara Y., Omentin, a novel adipocytokine inhibits TNF-induced vascular inflammation in human endothelial cells. Biochem Biophys Res Commun, 2011. 408(2): p. 339-343.
79. Christiansen T., Richelsen B., and Bruun J. M., Monocyte chemoattractant protein-1 is produced in isolated adipocytes, associated with adiposity and reduced after weight loss in morbid obese subjects. Int J Obes (Lond), 2005. 29(1): p. 146-150.
80. Weisberg S. P., Hunter D., Huber R., Lemieux J., Slaymaker S., Vaddi K., Charo I., Leibel R. L., and Ferrante A. W., Jr., CCR2 modulates inflammatory and metabolic effects of high-fat feeding. J Clin Invest, 2006. 116(1): p. 115-124.
81. Kanda H., Tateya S., Tamori Y., Kotani K., Hiasa K., Kitazawa R., Kitazawa S., Miyachi H., Maeda S., Egashira K., and Kasuga M., MCP-1 contributes to macrophage infiltration into adipose tissue, insulin resistance, and hepatic steatosis in obesity. J Clin Invest, 2006. 116(6): p. 1494-1505. 82. Seki E., de Minicis S., Inokuchi S., Taura K., Miyai K., van Rooijen N., Schwabe R. F., and Brenner