Multiple-Site Activation of the Cysteinyl Leukotriene Receptor 2 Is Required for Exacerbation of Ischemia/Reperfusion Injury

Abstract

Leukotrienes are potent proinflammatory lipid mediators synthesized from arachidonic acid via the actions of 5-lipoxygenase and 5-lipoxygenase-activating protein.Cysteinyl leukotrienes (cysLTs) are a subfamily of leukotriene molecules, thus termed because of a common cysteine moiety in their respective structures. The cysLTs, leukotriene C 4 , D 4 , and E 4 (LTC 4 , D 4 , and E 4 , respectively), exert their effects by binding to sequenced G-protein-coupled receptors: cysteinyl leukotriene receptor 1 (CysLT 1 R), cysteinyl leukotriene receptor 2 (CysLT 2 R), and a novel CysLT E receptor (GPR99).3 CysLT 1 R binds LTD 4 preferentially to LTC 4 , whereas CysLT 2 R binds LTD 4 and LTC 4 with equal affinity. Both receptors bind LTE 4 , the most stable and abundant cysLT, with weak affinity. 4 In contrast, GPR99 displays preferential binding affinity for LTE 4 , with weak affinity for LTC 4 and LTD 4 . Objective-Transgenic overexpression of the human cysteinyl leukotriene receptor 2 (CysLT 2 R) in murine endothelium exacerbates vascular permeability and ischemia/reperfusion injury. Here, we explore the underlying mechanisms of CysLT 2 R activation-mediated inflammation and delineate the relative contributions of endogenous murine CysLT 2 R and the transgene-derived receptor. Approach and Results-We created a novel mouse with only endothelial-expressed CysLT 2 R (endothelium-targeted overexpression mice [EC]/CysLT 2 R-knockout mice [KO]) by crossing EC with KO to dissect the role of endothelial CysLT 2 R in tissue injury. Surprisingly, we discovered that damage in EC/KO mice was not elevated (24% versus 47% EC) after ischemia/reperfusion. We examined vascular permeability and leukocyte recruitment/rolling responses in the cremaster vasculature after cysteinyl leukotriene (cysLT) stimulation. Mice possessing transgenic endothelial CysLT 2 R overexpression, whether EC or EC/KO, when stimulated with cysLTs, exhibited vascular hyperpermeability, declining leukocyte flux, and a transient increase in slow-rolling leukocyte fraction. and coronary endothelial cells. 9 CysLT 2 R research had been previously hampered by a lack of selective pharmacological agents, 10 the majority of work instead using the nonselective cysLT antagonist/partial agonist 11 or genetic models of CysLT 2 R expression modulation. 11,12 However, recent studies have characterized 2 novel CysLT 2 R-selective antagonists: HAMI3379 13 and BayCysLT 2 , [14][15][16] which are proving to be useful as tools in eicosanoid research.There is evidence linking cysLTs to cardiovascular disease and inflammation. Expression of components of the leukotriene synthesis pathway is found in human atherosclerotic lesions.17 Furthermore, genetic polymorphisms in 5-lipoxygenase pathway genes have been correlated to increased myocardial infarction and stroke risk in some populations 18 but not all. 19,20 CysLT 2 R can mediate vascular permeability, 12,21 susceptibility to gastrointestinal tract inflammation, 22 and increased vulnerability to ischemic injury in the heart 11 a...

Role of the Cysteinyl Leukotrienes in the Pathogenesis and Progression of Cardiovascular Diseases

“…These findings indicate that CysLT 2 R activation results in heightened facilitation of diapedesis, which enhances the magnitude of the inflammatory response leading to additional damage to the site of injury [ 140 ]. This mechanism was then confirmed by an in vivo study [ 124 ].…”

“…Among a number of inflammatory mediators regulating leukocytes, LTs should be included. Indeed, LTs are necessary for the function and migration of leukocytes [ 91 , 109 ]; moreover, LTs could play a role in the development of MI since they influence fibroblasts [ 30 ], increase contractility and proliferation of smooth muscle cells [ 89 , 106 , 123 ], and are also important for vascular permeability [ 124 ].…”

“…The mechanism of action was partially explained in another study on the same model by demonstrating that CysLT 2 R mediates inflammatory reactions in a vascular bed-specific manner by altering transendothelial vesicle transport-based vascular permeability [ 34 ]. A very recent paper indicated the existence of endothelial and nonendothelial CysLT 2 R niches having separate roles in mediating inflammatory responses in which activation is required for injury exacerbation [ 124 ]. Particularly, endothelial receptor activation results in increased vascular permeability and leukocyte slow rolling, facilitating leukocyte transmigration, whereas nonendothelial receptors, likely located on resident/circulating leukocytes, facilitate leukocyte recruitment to the site of injury and activation of endothelial receptor.…”

Evaluation of Cysteinyl Leukotriene Signaling as a Therapeutic Target for Colorectal Cancer

“…CysLT 1 and CysLT 2 receptors are both expressed in vascular endothelial cells (ECs) and vascular smooth muscle cells, either constitutively or inducibly—although CysLT 2 is the dominant receptor type (Gronert et al, 2001 ; Sjöström et al, 2003 ; Kaetsu et al, 2007 ). Transgenic mice overexpressing endothelial CysLT 2 exhibit vascular hyperpermeability and upregulate ICAM-1 and VCAM-1 expression, adhesion molecules which regulate angiogenesis (Jiang et al, 2008 ; Ni et al, 2014 ). Conflicting reports surround the regulation of EC function by CysLTs—CysLT stimulation has been shown to increase human umbilical vein endothelial cell proliferation in vitro (Duah et al, 2013 ).…”

Cysteinyl Leukotrienes and Their Receptors: Emerging Therapeutic Targets in Central Nervous System Disorders

“…Later studies carried out on mCysLT 2 R found that the homology of mCysLT 2 R to that of hCysLT 2 R was 73.4% and it consisted of 309 amino acids . It is interesting that CysLT 2 R uses different activation niche for the mediation of its inflammatory responses .…”