Inflammation, in excess, was believed to be an underlying factor in the pathogenesis of proliferative cardiovascular diseases such as atherosclerosis. Phospholipase A2s (PLA2s) play an important role in inflammation. Arachidonic acid (AA), which is produced primarily by PLA2s, metabolizes via the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 monooxygenase (CYP) pathways producing prostaglandins (PGs), hydroperoxyeicosatetraenoic acids (HPETEs) and epoxyeicosatrienoic acids (EETs), respectively. While some of the COX and LOX products of AA are proinflammatory, CYP, particularly CYP2C8/9 products of AA, are anti-inflammatory. Atherosclerotic arteries produce 15(S)-HETE as a major 15- LOX product of AA. Although the involvement of 15-LOX1 in the oxidation of low-density lipoprotein has been extensively studied in understanding its role in the pathobiology of atherosclerosis, very little is known in regard to its AA product, 15(S)-HETE, in atherosclerosis. In this regard, during the previous funding cycle of this grant application we have shown that 15(S)-HETE via inducing the expression of fibroblast growth factor-2, vascular endothelial growth factor and matrix metalloproteinase-2 modulates angiogenesis, an important factor in vascular wall diseases. During the course of these studies, we have discovered that 15(S)-HETE disrupts endothelial cell (EC) barrier function. Since one of the crucial functions of ECs is to maintain vessel wall integrity, perturbation in EC barrier function could be an initiation point for EC dysfunction and inflammation, two fundamental events in the pathogenesis of atherosclerosis. Based on these novel observations, we predict that eicosanoids, particularly the 15-LOX product of AA, namely, 15(S)-HETE via its capacity to perturb EC barrier function promotes paracellular movement of inflammatory cells into sub-endothelial space and sets the soil for the development of atherosclerosis. To address this hypothesis, we have proposed to test the following specific aims: 1. 15-LOX1-15(S)-HETE axis via tyrosine phosphorylation of tight junction (TJ) proteins disrupts TJs and thereby perturbs EC barrier function;2. Non-receptor tyrosine kinases, Src and Pyk2 mediate 15- LOX1-15(S)-HETE-induced tyrosine phosphorylation of TJ proteins and their disassembly from TJs resulting in EC barrier dysfunction;3. Mitogen-activated protein kinases (MAPKs) mediate 15-LOX1-15(S)-HETE-induced TJ protein serine/threonine phosphorylation and their disassembly from TJs resulting in EC barrier dysfunction and 4. 15-LOX1-15(S)-HETE axis via disrupting endothelial barrier function facilitates paracellular movement of inflammatory cells into the subendothelial space and promotes inflammation and atherosclerosis in response to feeding mice with high-fat diet. Thus, the experiments proposed in this grant application will provide novel information on the potential role of 15-LOX1-15(S)-HETE axis in endothelial barrier dysfunction leading to inflammation and atherosclerosis, which could be useful in the development of therapeutic drugs.

Public Health Relevance

Inflammation and endothelial cell (EC) dysfunction are crucial factors in the development of atherosclerosis. Although, atherosclerotic arteries have been shown to produce 15(S)-HETE as a major eicosanoid, its role in vascular wall remodeling is less clear. In this regard, the present grant proposal seeks to study the molecular mechanisms by which 15(S)-HETE disrupts EC barrier function and thereby sets the soil for initiation of EC dysfunction, inflammation and atherosclerosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL074860-10
Application #
8451471
Study Section
Vascular Cell and Molecular Biology Study Section (VCMB)
Program Officer
Srinivas, Pothur R
Project Start
2004-04-01
Project End
2016-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
10
Fiscal Year
2013
Total Cost
$357,000
Indirect Cost
$119,000
Name
University of Tennessee Health Science Center
Department
Physiology
Type
Schools of Medicine
DUNS #
941884009
City
Memphis
State
TN
Country
United States
Zip Code
38163
Chattopadhyay, Rima; Dyukova, Elena; Singh, Nikhlesh K et al. (2014) Vascular endothelial tight junctions and barrier function are disrupted by 15(S)-hydroxyeicosatetraenoic acid partly via protein kinase C ýý-mediated zona occludens-1 phosphorylation at threonine 770/772. J Biol Chem 289:3148-63
Kotla, Sivareddy; Singh, Nikhlesh K; Traylor Jr, James G et al. (2014) ROS-dependent Syk and Pyk2-mediated STAT1 activation is required for 15(S)-hydroxyeicosatetraenoic acid-induced CD36 expression and foam cell formation. Free Radic Biol Med 76:147-62
Kundumani-Sridharan, Venkatesh; Dyukova, Elena; Hansen 3rd, Dale E et al. (2013) 12/15-Lipoxygenase mediates high-fat diet-induced endothelial tight junction disruption and monocyte transmigration: a new role for 15(S)-hydroxyeicosatetraenoic acid in endothelial cell dysfunction. J Biol Chem 288:15830-42
Kotla, Sivareddy; Singh, Nikhlesh K; Heckle, Mark R et al. (2013) The transcription factor CREB enhances interleukin-17A production and inflammation in a mouse model of atherosclerosis. Sci Signal 6:ra83
Singh, Nikhlesh K; Kundumani-Sridharan, Venkatesh; Rao, Gadiparthi N (2011) 12/15-Lipoxygenase gene knockout severely impairs ischemia-induced angiogenesis due to lack of Rac1 farnesylation. Blood 118:5701-12
Kundumani-Sridharan, Venkatesh; Niu, Jixiao; Wang, Dong et al. (2010) 15(S)-hydroxyeicosatetraenoic acid-induced angiogenesis requires Src-mediated Egr-1-dependent rapid induction of FGF-2 expression. Blood 115:2105-16
Singh, Nikhlesh K; Quyen, Dong Van; Kundumani-Sridharan, Venkatesh et al. (2010) AP-1 (Fra-1/c-Jun)-mediated induction of expression of matrix metalloproteinase-2 is required for 15S-hydroxyeicosatetraenoic acid-induced angiogenesis. J Biol Chem 285:16830-43
Cheranov, Sergey Y; Karpurapu, Manjula; Wang, Dong et al. (2008) An essential role for SRC-activated STAT-3 in 14,15-EET-induced VEGF expression and angiogenesis. Blood 111:5581-91
Srivastava, Kalyan; Kundumani-Sridharan, Venkatesh; Zhang, Baolin et al. (2007) 15(S)-hydroxyeicosatetraenoic acid-induced angiogenesis requires STAT3-dependent expression of VEGF. Cancer Res 67:4328-36
Zhang, Baolin; Cao, Huiqing; Rao, Gadiparthi N (2006) Fibroblast growth factor-2 is a downstream mediator of phosphatidylinositol 3-kinase-Akt signaling in 14,15-epoxyeicosatrienoic acid-induced angiogenesis. J Biol Chem 281:905-14

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