The metabolic syndrome (MetS) is a constellation of biochemical and physical derangements that afflicts nearly 20-25% of individuals worldwide. It is increasingly appreciated that chronic inflammation is a unifying underlying mechanism not only for the development of MetS but also for the subsequent development of atherothrombotic cardiovascular disease - the primary source of morbidity and mortality in these individuals. Recent studies highlight an essential role for cells of the monocyte/macrophage lineage in the development of MetS and its consequences such as atherothrombosis. Cells of the monocyte/macrophages lineage exhibit remarkable plasticity that allows them to modulate their phenotype and efficiently respond to environmental signals and change their phenotype. For purposes of simplicity, a model system that classifies inflammatory macrophages as M1 and anti-inflammatory macrophages as M2 macrophages has been developed. The balance of these two subsets is thought to critically influence the physiologic and pathologic inflammatory response yet the molecular determinants of their speciation and function remain poorly understood. Kruppel-like factors (KLFs) are zinc-finger transcription factors implicated in a wide spectrum of biological processes including hematopoietic biology. Although previous studies by our group and others implicated KLF4 in myeloid cell biology, the in vivo physiological relevance has not been elucidated. Based on our preliminary studies, KLF4 expression is identified with the M2 population and strongly reduced in M1 macrophages - observations that are recapitulated in human inflammatory paradigms in vivo. Gain and loss-of-function studies reveal that KLF4 promotes an M2 genetic program and inhibits M1 target genes. Mice bearing myeloid-specific deletion of KLF4 exhibit a characteristic M1 phenotype as evidenced by enhanced bactericidal activity. Further, in response to a high fat diet (HFD), these animals develop numerous features consistent with MetS including obesity, dyslipidemia, insulin resistance, and a pro-atherogenic/pro-thrombotic state. These observations provide the foundation for the central hypothesis that KLF4 is an upstream molecular switch governing macrophage subset specification and function. To better understand the precise role of KLF4 in macrophage polarization and function, three aims are proposed.
In Aim 1, we will delineate the upstream mechanisms governing KLF4 expression in myeloid cells.
In Aim 2, we will determine the molecular basis for KLF4's ability to regulate the M1/M2 phenotype.
In Aim 3, studies will determine the effect of altered myeloid KLF4 expression on insulin resistance and atherothrombosis. Collectively, these studies will elucidate the molecular basis for KLF4-mediated polarization towards the M2 phenotype and the functional consequences of KLF4 sufficiency and deficiency on insulin resistance and atherothrombosis.

Public Health Relevance

The macrophage is a critical regulator of the body's response to inflammation that contributes to disease processes such as insulin resistant states and atherothrombotic vascular disease. Recent studies from our group have identified a factor that regulates key aspects of macrophage biology. This proposal seeks to understand the mechanisms underlying the function of this factor with the goal of developing novel therapies for the treatment of inflammatory disease states.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL110630-02
Application #
8313876
Study Section
Special Emphasis Panel (ZRG1-VH-D (02))
Program Officer
Kindzelski, Andrei L
Project Start
2011-08-05
Project End
2015-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
2
Fiscal Year
2012
Total Cost
$392,500
Indirect Cost
$142,500
Name
Case Western Reserve University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
Sangwung, Panjamaporn; Zhou, Guangjin; Nayak, Lalitha et al. (2017) KLF2 and KLF4 control endothelial identity and vascular integrity. JCI Insight 2:e91700
Sangwung, Panjamaporn; Zhou, Guangjin; Lu, Yuan et al. (2017) Regulation of endothelial hemoglobin alpha expression by Kruppel-like factors. Vasc Med 22:363-369
Zhang, Lilei; Prosdocimo, Domenick A; Bai, Xiaodong et al. (2015) KLF15 Establishes the Landscape of Diurnal Expression in the Heart. Cell Rep 13:2368-2375
Prosdocimo, Domenick A; Sabeh, M Khaled; Jain, Mukesh K (2015) Kruppel-like factors in muscle health and disease. Trends Cardiovasc Med 25:278-87
Liao, Xudong; Zhang, Rongli; Lu, Yuan et al. (2015) Kruppel-like factor 4 is critical for transcriptional control of cardiac mitochondrial homeostasis. J Clin Invest 125:3461-76
Jain, Mukesh K; Sangwung, Panjamaporn; Hamik, Anne (2014) Regulation of an inflammatory disease: Krüppel-like factors and atherosclerosis. Arterioscler Thromb Vasc Biol 34:499-508
Date, Dipali; Das, Riku; Narla, Goutham et al. (2014) Kruppel-like transcription factor 6 regulates inflammatory macrophage polarization. J Biol Chem 289:10318-29
Tugal, Derin; Jain, Mukesh K; Simon, Daniel I (2014) Endothelial KLF4: crippling vascular injury? J Am Heart Assoc 3:e000769
Shi, Hong; Sheng, Baiyang; Zhang, Chao et al. (2014) Myeloid Kruppel-like factor 2 deficiency exacerbates neurological dysfunction and neuroinflammation in a murine model of multiple sclerosis. J Neuroimmunol 274:234-9
Shatat, Mohammad A; Tian, Hongmei; Zhang, Rongli et al. (2014) Endothelial Krüppel-like factor 4 modulates pulmonary arterial hypertension. Am J Respir Cell Mol Biol 50:647-53

Showing the most recent 10 out of 25 publications