Obesity increases risk for diabetes and atherosclerotic cardiovascular disease (CVD). However, the underlying mechanisms remain poorly understood. It is currently known that obesity is associated with chronic inflammation-characterized by increased production and secretion of cytokines/chemokines by adipose tissue (AT) and liver-and with increased hepatic production of triglyceride-rich lipoproteins (TGRLs) and increased levels of fatty acids (FAs, saturated FAs in particular). Current data suggest that these changes activate leukocytes in blood and AT. Blood monocyte activation can increase monocyte adhesion and migration, which is implicated in the development of atherosclerosis and accelerates inflammation in AT. Leukocyte accumulation and activation in AT may be critical to the development of adverse metabolic and pathogenic effects of obesity. CD11c is a b2 integrin primarily expressed on monocytes/macrophages and dendritic cells (DCs) that is a marker for monocyte/macrophage activation and participates in monocyte recruitment. Our preliminary data show that: (1) obesity with insulin resistance induced by high-fat (HF) diet rich in saturated FAs up-regulates CD11c on blood monocytes and AT macrophages;(2) CD11c contributes to monocyte adhesion and migration on inflamed endothelial cells (ECs) by binding vascular cell adhesion molecule-1 (VCAM-1);and (3) deficiency of CD11c in obese mice reduces atherosclerosis and decreases AT inflammation. Therefore, we hypothesize that obesity is associated with monocyte activation with increased CD11c expression, and that CD11c is mechanistically linked to obesity-related diseases including CVD and diabetes.
Three specific aims are proposed to test our hypotheses:
Aim 1. Examine blood monocyte activation, including CD11c expression, in obese mice and humans;and its modulation by weight loss and by dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA);
Aim 2. Determine the role of increased CD11c in the development of atherosclerosis and in monocyte adhesion and recruitment into atherosclerotic lesions by using animal models of obesity with hypercholesterolemia, and by in vitro flow adhesion assay and in vivo adoptive transfer of blood monocytes with or without CD11c;
and Aim 3. Examine the role of CD11c in AT inflammation including macrophage and T cell accumulation and activation;and in metabolic abnormalities in mice with HF diet-induced obesity. This approach will help us better understand the mechanisms of obesity- linked inflammation, specifically the role of CD11c in recruitment and activation of macrophages and T cells in atherosclerotic lesions and AT. Considering the demonstrated role of chronic inflammation in obesity-related CVD and metabolic disease, this approach is of significant interest and has the potential to provide novel preventive and therapeutic targets for obesity-linked diseases.

Public Health Relevance

Obesity is associated with inflammation, which contributes to the development of atherosclerosis and diabetes. Our project will study the role of CD11c, a """"""""sticky"""""""" protein on white blood cells, in inflammation, including its contribution to the development of atherosclerosis and diabetes associated with obesity. This study has the potential to provide novel preventive and therapeutic targets for obesity-related atherosclerosis and diabetes.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL098839-03
Application #
8231447
Study Section
Clinical and Integrative Diabetes and Obesity Study Section (CIDO)
Program Officer
Hasan, Ahmed AK
Project Start
2010-04-01
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
3
Fiscal Year
2012
Total Cost
$339,216
Indirect Cost
$100,634
Name
Baylor College of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
051113330
City
Houston
State
TX
Country
United States
Zip Code
77030
Khan, Ilvira M; Pokharel, Yashashwi; Dadu, Razvan T et al. (2016) Postprandial Monocyte Activation in Individuals With Metabolic Syndrome. J Clin Endocrinol Metab 101:4195-4204
Lin, Ligen; Lee, Jong Han; Buras, Eric D et al. (2016) Ghrelin receptor regulates adipose tissue inflammation in aging. Aging (Albany NY) 8:178-91
Zhou, Hao; Ran, Yali; Da, Qi et al. (2016) Defective Association of the Platelet Glycoprotein Ib-IX Complex with the Glycosphingolipid-Enriched Membrane Domain Inhibits Murine Thrombus and Atheroma Formation. J Immunol 197:288-95
Xu, Lu; Dai Perrard, Xiaoyuan; Perrard, Jerry L et al. (2015) Foamy monocytes form early and contribute to nascent atherosclerosis in mice with hypercholesterolemia. Arterioscler Thromb Vasc Biol 35:1787-97
Foster, Greg A; Xu, Lu; Chidambaram, Alagu A et al. (2015) CD11c/CD18 Signals Very Late Antigen-4 Activation To Initiate Foamy Monocyte Recruitment during the Onset of Hypercholesterolemia. J Immunol 195:5380-92
Khan, I M; Perrard, X Yd; Brunner, G et al. (2015) Intermuscular and perimuscular fat expansion in obesity correlates with skeletal muscle T cell and macrophage infiltration and insulin resistance. Int J Obes (Lond) 39:1607-18
Wu, Huaizhu; Ballantyne, Christie M (2014) Inflammation versus host defense in obesity. Cell Metab 20:708-9
Jiang, Erlie; Perrard, Xiaoyuan Dai; Yang, Donglin et al. (2014) Essential role of CD11a in CD8+ T-cell accumulation and activation in adipose tissue. Arterioscler Thromb Vasc Biol 34:34-43
Wooten, Joshua S; Wu, Huaizhu; Raya, Joe et al. (2014) The Influence of an Obesogenic Diet on Oxysterol Metabolism in C57BL/6J Mice. Cholesterol 2014:843468
Khan, Ilvira M; Dai Perrard, Xiao-Yuan; Perrard, Jerry L et al. (2014) Attenuated adipose tissue and skeletal muscle inflammation in obese mice with combined CD4+ and CD8+ T cell deficiency. Atherosclerosis 233:419-28

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