DOI QR코드

DOI QR Code

The Role of T Cells in Obesity-Associated Inflammation and Metabolic Disease

  • Chan-Su Park (Department of Pathology, Johns Hopkins University School of Medicine) ;
  • Nilabh Shastri (Department of Pathology, Johns Hopkins University School of Medicine)
  • Received : 2021.11.30
  • Accepted : 2022.01.10
  • Published : 2022.02.28

Abstract

Chronic inflammation plays a critical role in the development of obesity-associated metabolic disorders such as insulin resistance. Obesity alters the microenvironment of adipose tissue and the intestines from anti-inflammatory to pro-inflammatory, which promotes low grade systemic inflammation and insulin resistance in obese mice. Various T cell subsets either help maintain metabolic homeostasis in healthy states or contribute to obesity-associated metabolic syndromes. In this review, we will discuss the T cell subsets that reside in adipose tissue and intestines and their role in the development of obesity-induced systemic inflammation.

Keywords

Acknowledgement

We thank Scheherazade Sadegh-Nasseri for suggestions and guidance on the manuscript and J David Peske and Jesus Contreras Rodriguez for editorial comments. This work was supported by NIH grant (R01AI130210, R01AI121174, R37AI060040).

References

  1. Despres JP, Lemieux I. Abdominal obesity and metabolic syndrome. Nature 2006;444:881-887. https://doi.org/10.1038/nature05488
  2. Saltiel AR, Olefsky JM. Inflammatory mechanisms linking obesity and metabolic disease. J Clin Invest 2017;127:1-4. https://doi.org/10.1172/JCI92035
  3. Esser N, Legrand-Poels S, Piette J, Scheen AJ, Paquot N. Inflammation as a link between obesity, metabolic syndrome and type 2 diabetes. Diabetes Res Clin Pract 2014;105:141-150. https://doi.org/10.1016/j.diabres.2014.04.006
  4. Hotamisligil GS. Inflammation and metabolic disorders. Nature 2006;444:860-867. https://doi.org/10.1038/nature05485
  5. Mraz M, Haluzik M. The role of adipose tissue immune cells in obesity and low-grade inflammation. J Endocrinol 2014;222:R113-R127. https://doi.org/10.1530/JOE-14-0283
  6. Giralt M, Villarroya F. White, brown, beige/brite: different adipose cells for different functions? Endocrinology 2013;154:2992-3000. https://doi.org/10.1210/en.2013-1403
  7. Morigny P, Boucher J, Arner P, Langin D. Lipid and glucose metabolism in white adipocytes: pathways, dysfunction and therapeutics. Nat Rev Endocrinol 2021;17:276-295. https://doi.org/10.1038/s41574-021-00471-8
  8. Thiam AR, Beller M. The why, when and how of lipid droplet diversity. J Cell Sci 2017;130:315-324. https://doi.org/10.1242/jcs.192021
  9. Shuster A, Patlas M, Pinthus JH, Mourtzakis M. The clinical importance of visceral adiposity: a critical review of methods for visceral adipose tissue analysis. Br J Radiol 2012;85:1-10. https://doi.org/10.1259/bjr/38447238
  10. Tchkonia T, Thomou T, Zhu Y, Karagiannides I, Pothoulakis C, Jensen MD, Kirkland JL. Mechanisms and metabolic implications of regional differences among fat depots. Cell Metab 2013;17:644-656. https://doi.org/10.1016/j.cmet.2013.03.008
  11. Tabuchi C, Sul HS. Signaling pathways regulating thermogenesis. Front Endocrinol (Lausanne) 2021;12:595020.
  12. Cannon B, Nedergaard J. Brown adipose tissue: function and physiological significance. Physiol Rev 2004;84:277-359. https://doi.org/10.1152/physrev.00015.2003
  13. Harms M, Seale P. Brown and beige fat: development, function and therapeutic potential. Nat Med 2013;19:1252-1263. https://doi.org/10.1038/nm.3361
  14. Demine S, Renard P, Arnould T. Mitochondrial uncoupling: a key controller of biological processes in physiology and diseases. Cells 2019;8:795.
  15. Hotamisligil GS, Shargill NS, Spiegelman BM. Adipose expression of tumor necrosis factor-alpha: direct role in obesity-linked insulin resistance. Science 1993;259:87-91. https://doi.org/10.1126/science.7678183
  16. Hotamisligil GS, Arner P, Caro JF, Atkinson RL, Spiegelman BM. Increased adipose tissue expression of tumor necrosis factor-alpha in human obesity and insulin resistance. J Clin Invest 1995;95:2409-2415. https://doi.org/10.1172/JCI117936
  17. Uysal KT, Wiesbrock SM, Marino MW, Hotamisligil GS. Protection from obesity-induced insulin resistance in mice lacking TNF-alpha function. Nature 1997;389:610-614. https://doi.org/10.1038/39335
  18. Kahn SE, Hull RL, Utzschneider KM. Mechanisms linking obesity to insulin resistance and type 2 diabetes. Nature 2006;444:840-846. https://doi.org/10.1038/nature05482
  19. Cancello R, Henegar C, Viguerie N, Taleb S, Poitou C, Rouault C, Coupaye M, Pelloux V, Hugol D, Bouillot JL, et al. Reduction of macrophage infiltration and chemoattractant gene expression changes in white adipose tissue of morbidly obese subjects after surgery-induced weight loss. Diabetes 2005;54:2277-2286. https://doi.org/10.2337/diabetes.54.8.2277
  20. Xu H, Barnes GT, Yang Q, Tan G, Yang D, Chou CJ, Sole J, Nichols A, Ross JS, Tartaglia LA, et al. Chronic inflammation in fat plays a crucial role in the development of obesity-related insulin resistance. J Clin Invest 2003;112:1821-1830. https://doi.org/10.1172/JCI200319451
  21. Ferrante AW Jr. The immune cells in adipose tissue. Diabetes Obes Metab 2013;15 Suppl 3:34-38. https://doi.org/10.1111/dom.12154
  22. Ginhoux F, Jung S. Monocytes and macrophages: developmental pathways and tissue homeostasis. Nat Rev Immunol 2014;14:392-404. https://doi.org/10.1038/nri3671
  23. Lee J, Choi JH. Deciphering macrophage phenotypes upon lipid uptake and atherosclerosis. Immune Netw 2020;20:e22.
  24. Weisberg SP, McCann D, Desai M, Rosenbaum M, Leibel RL, Ferrante AW Jr. Obesity is associated with macrophage accumulation in adipose tissue. J Clin Invest 2003;112:1796-1808. https://doi.org/10.1172/JCI200319246
  25. Sartipy P, Loskutoff DJ. Monocyte chemoattractant protein 1 in obesity and insulin resistance. Proc Natl Acad Sci U S A 2003;100:7265-7270. https://doi.org/10.1073/pnas.1133870100
  26. Kanda H, Tateya S, Tamori Y, Kotani K, Hiasa K, Kitazawa R, Kitazawa S, Miyachi H, Maeda S, Egashira K, et al. MCP-1 contributes to macrophage infiltration into adipose tissue, insulin resistance, and hepatic steatosis in obesity. J Clin Invest 2006;116:1494-1505. https://doi.org/10.1172/JCI26498
  27. Rull A, Camps J, Alonso-Villaverde C, Joven J. Insulin resistance, inflammation, and obesity: role of monocyte chemoattractant protein-1 (or CCL2) in the regulation of metabolism. Mediators Inflamm 2010;2010:326580.
  28. Deshmane SL, Kremlev S, Amini S, Sawaya BE. Monocyte chemoattractant protein-1 (MCP-1): an overview. J Interferon Cytokine Res 2009;29:313-326. https://doi.org/10.1089/jir.2008.0027
  29. Kamei N, Tobe K, Suzuki R, Ohsugi M, Watanabe T, Kubota N, Ohtsuka-Kowatari N, Kumagai K, Sakamoto K, Kobayashi M, et al. Overexpression of monocyte chemoattractant protein-1 in adipose tissues causes macrophage recruitment and insulin resistance. J Biol Chem 2006;281:26602-26614. https://doi.org/10.1074/jbc.M601284200
  30. Strissel KJ, Stancheva Z, Miyoshi H, Perfield JW 2nd, DeFuria J, Jick Z, Greenberg AS, Obin MS. Adipocyte death, adipose tissue remodeling, and obesity complications. Diabetes 2007;56:2910-2918. https://doi.org/10.2337/db07-0767
  31. Lumeng CN, Bodzin JL, Saltiel AR. Obesity induces a phenotypic switch in adipose tissue macrophage polarization. J Clin Invest 2007;117:175-184. https://doi.org/10.1172/JCI29881
  32. Wu H, Perrard XD, Wang Q, Perrard JL, Polsani VR, Jones PH, Smith CW, Ballantyne CM. CD11c expression in adipose tissue and blood and its role in diet-induced obesity. Arterioscler Thromb Vasc Biol 2010;30:186-192. https://doi.org/10.1161/ATVBAHA.109.198044
  33. Sun K, Kusminski CM, Scherer PE. Adipose tissue remodeling and obesity. J Clin Invest 2011;121:2094-2101. https://doi.org/10.1172/JCI45887
  34. Cinti S, Mitchell G, Barbatelli G, Murano I, Ceresi E, Faloia E, Wang S, Fortier M, Greenberg AS, Obin MS. Adipocyte death defines macrophage localization and function in adipose tissue of obese mice and humans. J Lipid Res 2005;46:2347-2355. https://doi.org/10.1194/jlr.M500294-JLR200
  35. Lindhorst A, Raulien N, Wieghofer P, Eilers J, Rossi FMV, Bechmann I, Gericke M. Adipocyte death triggers a pro-inflammatory response and induces metabolic activation of resident macrophages. Cell Death Dis 2021;12:579.
  36. Halberg N, Khan T, Trujillo ME, Wernstedt-Asterholm I, Attie AD, Sherwani S, Wang ZV, Landskroner-Eiger S, Dineen S, Magalang UJ, et al. Hypoxia-inducible factor 1alpha induces fibrosis and insulin resistance in white adipose tissue. Mol Cell Biol 2009;29:4467-4483. https://doi.org/10.1128/MCB.00192-09
  37. Fujisaka S, Usui I, Ikutani M, Aminuddin A, Takikawa A, Tsuneyama K, Mahmood A, Goda N, Nagai Y, Takatsu K, et al. Adipose tissue hypoxia induces inflammatory M1 polarity of macrophages in an HIF-1α-dependent and HIF-1α-independent manner in obese mice. Diabetologia 2013;56:1403-1412. https://doi.org/10.1007/s00125-013-2885-1
  38. Shan B, Wang X, Wu Y, Xu C, Xia Z, Dai J, Shao M, Zhao F, He S, Yang L, et al. The metabolic ER stress sensor IRE1α suppresses alternative activation of macrophages and impairs energy expenditure in obesity. Nat Immunol 2017;18:519-529. https://doi.org/10.1038/ni.3709
  39. Fan R, Toubal A, Goni S, Drareni K, Huang Z, Alzaid F, Ballaire R, Ancel P, Liang N, Damdimopoulos A, et al. Loss of the co-repressor GPS2 sensitizes macrophage activation upon metabolic stress induced by obesity and type 2 diabetes. Nat Med 2016;22:780-791. https://doi.org/10.1038/nm.4114
  40. Kratz M, Coats BR, Hisert KB, Hagman D, Mutskov V, Peris E, Schoenfelt KQ, Kuzma JN, Larson I, Billing PS, et al. Metabolic dysfunction drives a mechanistically distinct proinflammatory phenotype in adipose tissue macrophages. Cell Metab 2014;20:614-625. https://doi.org/10.1016/j.cmet.2014.08.010
  41. Wu H, Ghosh S, Perrard XD, Feng L, Garcia GE, Perrard JL, Sweeney JF, Peterson LE, Chan L, Smith CW, et al. T-cell accumulation and regulated on activation, normal T cell expressed and secreted upregulation in adipose tissue in obesity. Circulation 2007;115:1029-1038. https://doi.org/10.1161/CIRCULATIONAHA.106.638379
  42. Wang Q, Wu H. T cells in adipose tissue: critical players in immunometabolism. Front Immunol 2018;9:2509.
  43. Raphael I, Nalawade S, Eagar TN, Forsthuber TG. T cell subsets and their signature cytokines in autoimmune and inflammatory diseases. Cytokine 2015;74:5-17. https://doi.org/10.1016/j.cyto.2014.09.011
  44. Mosmann TR, Coffman RL. Th1 and Th2 cells: different patterns of lymphokine secretion lead to different functional properties. Annu Rev Immunol 1989;7:145-173. https://doi.org/10.1146/annurev.iy.07.040189.001045
  45. Korn T, Bettelli E, Oukka M, Kuchroo VK. Il-17 and Th17 cells. Annu Rev Immunol 2009;27:485-517. https://doi.org/10.1146/annurev.immunol.021908.132710
  46. Dominguez-Villar M, Hafler DA. Regulatory T cells in autoimmune disease. Nat Immunol 2018;19:665-673. https://doi.org/10.1038/s41590-018-0120-4
  47. Kintscher U, Hartge M, Hess K, Foryst-Ludwig A, Clemenz M, Wabitsch M, Fischer-Posovszky P, Barth TF, Dragun D, Skurk T, et al. T-lymphocyte infiltration in visceral adipose tissue: a primary event in adipose tissue inflammation and the development of obesity-mediated insulin resistance. Arterioscler Thromb Vasc Biol 2008;28:1304-1310. https://doi.org/10.1161/ATVBAHA.108.165100
  48. Deng T, Lyon CJ, Minze LJ, Lin J, Zou J, Liu JZ, Ren Y, Yin Z, Hamilton DJ, Reardon PR, et al. Class II major histocompatibility complex plays an essential role in obesity-induced adipose inflammation. Cell Metab 2013;17:411-422. https://doi.org/10.1016/j.cmet.2013.02.009
  49. Cho KW, Morris DL, DelProposto JL, Geletka L, Zamarron B, Martinez-Santibanez G, Meyer KA, Singer K, O'Rourke RW, Lumeng CN. An MHC II-dependent activation loop between adipose tissue macrophages and CD4+ T cells controls obesity-induced inflammation. Cell Reports 2014;9:605-617. https://doi.org/10.1016/j.celrep.2014.09.004
  50. Morris DL, Cho KW, Delproposto JL, Oatmen KE, Geletka LM, Martinez-Santibanez G, Singer K, Lumeng CN. Adipose tissue macrophages function as antigen-presenting cells and regulate adipose tissue CD4+ T cells in mice. Diabetes 2013;62:2762-2772. https://doi.org/10.2337/db12-1404
  51. Rocha VZ, Folco EJ, Sukhova G, Shimizu K, Gotsman I, Vernon AH, Libby P. Interferon-gamma, a Th1 cytokine, regulates fat inflammation: a role for adaptive immunity in obesity. Circ Res 2008;103:467-476. https://doi.org/10.1161/CIRCRESAHA.108.177105
  52. Khan IM, Dai Perrard XY, Perrard JL, Mansoori A, Wayne Smith C, Wu H, Ballantyne CM. Attenuated adipose tissue and skeletal muscle inflammation in obese mice with combined CD4+ and CD8+ T cell deficiency. Atherosclerosis 2014;233:419-428. https://doi.org/10.1016/j.atherosclerosis.2014.01.011
  53. Winer S, Chan Y, Paltser G, Truong D, Tsui H, Bahrami J, Dorfman R, Wang Y, Zielenski J, Mastronardi F, et al. Normalization of obesity-associated insulin resistance through immunotherapy. Nat Med 2009;15:921-929. https://doi.org/10.1038/nm.2001
  54. McLaughlin T, Liu LF, Lamendola C, Shen L, Morton J, Rivas H, Winer D, Tolentino L, Choi O, Zhang H, et al. T-cell profile in adipose tissue is associated with insulin resistance and systemic inflammation in humans. Arterioscler Thromb Vasc Biol 2014;34:2637-2643.  https://doi.org/10.1161/ATVBAHA.114.304636
  55. Yang H, Youm YH, Vandanmagsar B, Ravussin A, Gimble JM, Greenway F, Stephens JM, Mynatt RL, Dixit VD. Obesity increases the production of proinflammatory mediators from adipose tissue T cells and compromises TCR repertoire diversity: implications for systemic inflammation and insulin resistance. J Immunol 2010;185:1836-1845. https://doi.org/10.4049/jimmunol.1000021
  56. Zeng Q, Sun X, Xiao L, Xie Z, Bettini M, Deng T. A unique population: adipose-resident regulatory T cells. Front Immunol 2018;9:2075.
  57. Feuerer M, Herrero L, Cipolletta D, Naaz A, Wong J, Nayer A, Lee J, Goldfine AB, Benoist C, Shoelson S, et al. Lean, but not obese, fat is enriched for a unique population of regulatory T cells that affect metabolic parameters. Nat Med 2009;15:930-939. https://doi.org/10.1038/nm.2002
  58. Rausch ME, Weisberg S, Vardhana P, Tortoriello DV. Obesity in C57BL/6J mice is characterized by adipose tissue hypoxia and cytotoxic T-cell infiltration. Int J Obes 2008;32:451-463. https://doi.org/10.1038/sj.ijo.0803744
  59. Nishimura S, Manabe I, Nagasaki M, Eto K, Yamashita H, Ohsugi M, Otsu M, Hara K, Ueki K, Sugiura S, et al. CD8+ effector T cells contribute to macrophage recruitment and adipose tissue inflammation in obesity. Nat Med 2009;15:914-920. https://doi.org/10.1038/nm.1964
  60. Kiran S, Kumar V, Murphy EA, Enos RT, Singh UP. High fat diet-induced CD8+ T cells in adipose tissue mediate macrophages to sustain low-grade chronic inflammation. Front Immunol 2021;12:680944.
  61. Tokunaga R, Zhang W, Naseem M, Puccini A, Berger MD, Soni S, McSkane M, Baba H, Lenz HJ. CXCL9, CXCL10, CXCL11/CXCR3 axis for immune activation - a target for novel cancer therapy. Cancer Treat Rev 2018;63:40-47. https://doi.org/10.1016/j.ctrv.2017.11.007
  62. Bendelac A, Savage PB, Teyton L. The biology of NKT cells. Annu Rev Immunol 2007;25:297-336. https://doi.org/10.1146/annurev.immunol.25.022106.141711
  63. Lynch L, Nowak M, Varghese B, Clark J, Hogan AE, Toxavidis V, Balk SP, O'Shea D, O'Farrelly C, Exley MA. Adipose tissue invariant NKT cells protect against diet-induced obesity and metabolic disorder through regulatory cytokine production. Immunity 2012;37:574-587. https://doi.org/10.1016/j.immuni.2012.06.016
  64. Lynch L, Hogan AE, Duquette D, Lester C, Banks A, LeClair K, Cohen DE, Ghosh A, Lu B, Corrigan M, et al. iNKT cells induce FGF21 for thermogenesis and are required for maximal weight loss in GLP1 therapy. Cell Metab 2016;24:510-519. https://doi.org/10.1016/j.cmet.2016.08.003
  65. Paul S, Singh AK, Shilpi , Lal G. Phenotypic and functional plasticity of gamma-delta (γδ) T cells in inflammation and tolerance. Int Rev Immunol 2014;33:537-558. https://doi.org/10.3109/08830185.2013.863306
  66. Mehta P, Nuotio-Antar AM, Smith CW. γδ T cells promote inflammation and insulin resistance during high fat diet-induced obesity in mice. J Leukoc Biol 2015;97:121-134. https://doi.org/10.1189/jlb.3A0414-211RR
  67. Kohlgruber AC, Gal-Oz ST, LaMarche NM, Shimazaki M, Duquette D, Koay HF, Nguyen HN, Mina AI, Paras T, Tavakkoli A, et al. γδ T cells producing interleukin-17A regulate adipose regulatory T cell homeostasis and thermogenesis. Nat Immunol 2018;19:464-474. https://doi.org/10.1038/s41590-018-0094-2
  68. Hu B, Jin C, Zeng X, Resch JM, Jedrychowski MP, Yang Z, Desai BN, Banks AS, Lowell BB, Mathis D, et al. γδ T cells and adipocyte IL-17RC control fat innervation and thermogenesis. Nature 2020;578:610-614. https://doi.org/10.1038/s41586-020-2028-z
  69. Backhed F, Ding H, Wang T, Hooper LV, Koh GY, Nagy A, Semenkovich CF, Gordon JI. The gut microbiota as an environmental factor that regulates fat storage. Proc Natl Acad Sci U S A 2004;101:15718-15723. https://doi.org/10.1073/pnas.0407076101
  70. Backhed F, Manchester JK, Semenkovich CF, Gordon JI. Mechanisms underlying the resistance to diet-induced obesity in germ-free mice. Proc Natl Acad Sci U S A 2007;104:979-984. https://doi.org/10.1073/pnas.0605374104
  71. Membrez M, Blancher F, Jaquet M, Bibiloni R, Cani PD, Burcelin RG, Corthesy I, Mace K, Chou CJ. Gut microbiota modulation with norfloxacin and ampicillin enhances glucose tolerance in mice. FASEB J 2008;22:2416-2426.  https://doi.org/10.1096/fj.07-102723
  72. Turnbaugh PJ, Ley RE, Mahowald MA, Magrini V, Mardis ER, Gordon JI. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature 2006;444:1027-1031. https://doi.org/10.1038/nature05414
  73. Cani PD, Amar J, Iglesias MA, Poggi M, Knauf C, Bastelica D, Neyrinck AM, Fava F, Tuohy KM, Chabo C, et al. Metabolic endotoxemia initiates obesity and insulin resistance. Diabetes 2007;56:1761-1772. https://doi.org/10.2337/db06-1491
  74. de La Serre CB, Ellis CL, Lee J, Hartman AL, Rutledge JC, Raybould HE. Propensity to high-fat diet-induced obesity in rats is associated with changes in the gut microbiota and gut inflammation. Am J Physiol Gastrointest Liver Physiol 2010;299:G440-G448. https://doi.org/10.1152/ajpgi.00098.2010
  75. Cani PD, Bibiloni R, Knauf C, Waget A, Neyrinck AM, Delzenne NM, Burcelin R. Changes in gut microbiota control metabolic endotoxemia-induced inflammation in high-fat diet-induced obesity and diabetes in mice. Diabetes 2008;57:1470-1481. https://doi.org/10.2337/db07-1403
  76. Caesar R, Reigstad CS, Backhed HK, Reinhardt C, Ketonen M, Lunden GO, Cani PD, Backhed F. Gut-derived lipopolysaccharide augments adipose macrophage accumulation but is not essential for impaired glucose or insulin tolerance in mice. Gut 2012;61:1701-1707. https://doi.org/10.1136/gutjnl-2011-301689
  77. Wang Y, Li J, Tang L, Wang Y, Charnigo R, de Villiers W, Eckhardt E. T-lymphocyte responses to intestinally absorbed antigens can contribute to adipose tissue inflammation and glucose intolerance during high fat feeding. PLoS One 2010;5:e13951.
  78. Park C, Cheung KP, Limon N, Costanzo A, Barba C, Miranda N, Gargas S, Johnson AMF, Olefsky JM, Jameson JM. Obesity modulates intestinal intraepithelial T cell persistence, CD103 and CCR9 expression, and outcome in dextran sulfate sodium-induced colitis. J Immunol 2019;203:3427-3435. https://doi.org/10.4049/jimmunol.1900082
  79. Schon MP, Arya A, Murphy EA, Adams CM, Strauch UG, Agace WW, Marsal J, Donohue JP, Her H, Beier DR, et al. Mucosal T lymphocyte numbers are selectively reduced in integrin alpha E (CD103)-deficient mice. J Immunol 1999;162:6641-6649. https://doi.org/10.4049/jimmunol.162.11.6641
  80. Uehara S, Grinberg A, Farber JM, Love PE. A role for CCR9 in T lymphocyte development and migration. J Immunol 2002;168:2811-2819. https://doi.org/10.4049/jimmunol.168.6.2811
  81. Amiya T, Nakamoto N, Irie J, Taniki N, Chu PS, Koda Y, Miyamoto K, Yamaguchi A, Shiba S, Morikawa R, et al. C-C motif chemokine receptor 9 regulates obesity-induced insulin resistance via inflammation of the small intestine in mice. Diabetologia 2021;64:603-617. https://doi.org/10.1007/s00125-020-05349-4
  82. Luck H, Tsai S, Chung J, Clemente-Casares X, Ghazarian M, Revelo XS, Lei H, Luk CT, Shi SY, Surendra A, et al. Regulation of obesity-related insulin resistance with gut anti-inflammatory agents. Cell Metab 2015;21:527-542. https://doi.org/10.1016/j.cmet.2015.03.001
  83. Garidou L, Pomie C, Klopp P, Waget A, Charpentier J, Aloulou M, Giry A, Serino M, Stenman L, Lahtinen S, et al. The gut microbiota regulates intestinal CD4 T cells expressing RORγt and controls metabolic disease. Cell Metab 2015;22:100-112. https://doi.org/10.1016/j.cmet.2015.06.001
  84. Hong CP, Park A, Yang BG, Yun CH, Kwak MJ, Lee GW, Kim JH, Jang MS, Lee EJ, Jeun EJ, et al. Gut-specific delivery of T-helper 17 cells reduces obesity and insulin resistance in mice. Gastroenterology 2017;152:1998-2010. https://doi.org/10.1053/j.gastro.2017.02.016
  85. Omenetti S, Bussi C, Metidji A, Iseppon A, Lee S, Tolaini M, Li Y, Kelly G, Chakravarty P, Shoaie S, et al. The intestine harbors functionally distinct homeostatic tissue-resident and inflammatory Th17 cells. Immunity 2019;51:77-89.e6. https://doi.org/10.1016/j.immuni.2019.05.004
  86. Hinks TSC, Zhang XW. MAIT cell activation and functions. Front Immunol 2020;11:1014.
  87. Toubal A, Kiaf B, Beaudoin L, Cagninacci L, Rhimi M, Fruchet B, da Silva J, Corbett AJ, Simoni Y, Lantz O, et al. Mucosal-associated invariant T cells promote inflammation and intestinal dysbiosis leading to metabolic dysfunction during obesity. Nat Commun 2020;11:3755. 
  88. He S, Kahles F, Rattik S, Nairz M, McAlpine CS, Anzai A, Selgrade D, Fenn AM, Chan CT, Mindur JE, et al. Gut intraepithelial T cells calibrate metabolism and accelerate cardiovascular disease. Nature 2019;566:115-119. https://doi.org/10.1038/s41586-018-0849-9
  89. Muller TD, Finan B, Bloom SR, D'Alessio D, Drucker DJ, Flatt PR, Fritsche A, Gribble F, Grill HJ, Habener JF, et al. Glucagon-like peptide 1 (GLP-1). Mol Metab 2019;30:72-130. https://doi.org/10.1016/j.molmet.2019.09.010