LOX-1 in Ischemic Stroke

Novel Insights into the Link Between Myeloperoxidase Modified LDL, LOX-1, and Neuroserpin in Stroke

Background

Cardiovascular disease that is caused by atherosclerosis is the leading cause of death worldwide. Atherosclerosis is primarily triggered by endothelial dysfunction and the accumulation of modified low-density lipoprotein (LDL) particles in the subendothelial space of blood vessels. Early reports have associated oxidized LDL with altered fibrinolysis and atherogenesis. It has been suggested that myeloperoxidase oxidized LDL (Mox-LDL) is involved in atherosclerosis because of its significant pathophysiological role in the modification of LDL in vivo. It has been equally demonstrated that Mox-LDL binds to the lectin-like oxidized low-density lipoprotein receptor-1 (lox-1) scavenger receptor which leads to the upregulation of inflammatory mediators in endothelial cells and the progression of cardiovascular disease. It has been also shown that neuroserpin, a member of the serine proteinase inhibitor (serpin) superfamily, has an important role at the level of fibrinolysis in the nervous tissue.

Methods

Since little is known about the effects of Mox-LDL on endothelial cell fibrinolytic activity and the involvement of lox-1 in this process, our study aimed at evaluating the in vitro effects of Mox-LDL on neuroserpin release from human aortic endothelial cells (HAECs) and the role of lox-1 scavenger receptor in this context by relying on lox-1 gene silencing in HAECs, culturing the cells in the presence of Mox-LDL, measuring their neuroserpin expression and release by quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively, and assessing their fibrinolytic activity using the Euglobulin Clot Lysis Time (ECLT) method.

Results

Our data show that Mox-LDL decreases endothelial cell fibrinolytic capacity by upregulating neuroserpin in lox-1 knockdown cells.

Conclusions

Lox-1 protects the endothelial cells from a Mox-LDL-induced decrease in pro-fibrinolytic capacity, which has important consequences in the context of stroke.

sLOX-1: A Molecule for Evaluating the Prognosis of Recurrent Ischemic Stroke

Several clinical parameters and biomarkers have been proposed as prognostic markers for stroke. However, it has not been clarified whether the risk factors affecting the prognosis of patients with recurrent and first-ever stroke are similar. In this study, we aimed to explore the relationship between soluble lectin-like oxidized low-density lipoprotein receptor 1 (sLOX-1) levels and the prediction of the functional outcome in patients with recurrent and first-ever stroke. A total of 266 patients with recurrent and first-ever stroke, who underwent follow-up for 3 months, were included in this study. Plasma samples were collected within 24 h after onset. The results showed that biomarkers for the prognosis of patients with recurrent stroke were different from that of those with first-ever stroke. sLOX-1 levels were correlated with modified Rankin Scale scores of patients with recurrent stroke alone (r = 0.3232, p = 0.001). sLOX-1 levels were also associated with an increased risk of unfavorable outcomes in patients with recurrent stroke with an adjusted odds ratio of 1.489 (95% confidence interval, 1.204–1.842, p < 0.0001). Combining the risk factors showed greater accuracy for prognosis, yielding a sensitivity of 93.2% and a specificity of 75%, with an area under the curve of 0.916, evaluated by the receiver operating characteristic curve. These findings suggest that the diagnosis and prognosis are different between patients with recurrent stroke and those with first-ever stroke, and sLOX-1 level is an independent prognostic marker in patients with recurrent stroke.

COVID-19 Pathophysiology Predicts That Ischemic Stroke Occurrence Is an Expectation, Not an Exception-A Systematic Review

Clinical reports of neurological manifestations associated with severe coronavirus disease 2019 (COVID-19), such as acute ischemic stroke (AIS), encephalopathy, seizures, headaches, acute necrotizing encephalitis, cerebral microbleeds, posterior reversible leukoencephalopathy syndrome, hemophagocytic lymphohistiocytosis, peripheral neuropathy, cranial nerve palsies, transverse myelitis, and demyelinating disorders, are increasing rapidly. However, there are comparatively few studies investigating the potential impact of immunological responses secondary to hypoxia, oxidative stress, and excessive platelet-induced aggregation on the brain. This scoping review has focused on the pathophysiological mechanisms associated with peripheral and consequential neural (central) inflammation leading to COVID-19-related ischemic strokes. It also highlights the common biological processes shared between AIS and COVID-19 infection and the importance of the recognition that severe respiratory dysfunction and neurological impairments associated with COVID and chronic inflammation [post-COVID-19 neurological syndrome (PCNS)] may significantly impact recovery and ability to benefit from neurorehabilitation. This study provides a comprehensive review of the pathobiology of COVID-19 and ischemic stroke. It also affirms that the immunological contribution to the pathophysiology of COVID-19 is predictive of the neurological sequelae particularly ischemic stroke, which makes it the expectation rather than the exception. This work is of fundamental significance to the neurorehabilitation community given the increasing number of COVID-related ischemic strokes, the current limited knowledge regarding the risk of reinfection, and recent reports of a PCNS. It further highlights the need for global collaboration and research into new pathobiology-based neurorehabilitation treatment strategies and more integrated evidence-based care.

Current advances in circulating inflammatory biomarkers in atherosclerosis and related cardio-cerebrovascular diseases

Atherosclerosis (AS) is a systemic chronic disease affecting both the coronary and cerebral arteries. Inflammation plays a key role in the initiation and progression of AS, and numerous inflammatory factors have been proposed as potential biomarkers. This article reviews recent research in studies on major circulating inflammatory biomarkers to identify surrogates that may reflect processes associated with AS development and the risk of AS-related vascular events, such as Von Willebrand factor, lectin-like oxidized low-density-lipoprotein receptor-1, soluble urokinase plasminogen activator receptor, regulated upon activation, normal T-cell expressed and secreted, and microparticles, which may provide new perspectives for clinical AS evaluation and risk stratification.

Contribution of lectin-like oxidized low-density lipoprotein receptor-1 and LOX-1 modulating compounds to vascular diseases

The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the major receptor for binding and uptake of oxidized low-density lipoprotein (oxLDL) in endothelial cells. LOX-1 is also expressed in macrophages, smooth muscle cells and platelets. Following internalization of oxLDL, LOX-1 initiates a vicious cycle from activation of pro-inflammatory signaling pathways, thus promoting an increased reactive oxygen species formation and secretion of pro-inflammatory cytokines. LOX-1 plays a pivotal role in the development of endothelial dysfunction, foam cell and advanced lesions formation as well as in myocardial ischemia. Furthermore, it is known that LOX-1 plays a pivotal role in mitochondrial DNA damage, vascular cell apoptosis, and autophagy. A large number of studies provide evidence of a LOX-1's role in endothelial dysfunction, hypertension, diabetes, and obesity. In addition, novel insights into LOX-1 ligands and the activated signaling pathways have been gained. Recent studies have shown an interaction of LOX-1 with microRNA's, thus providing novel tools to regulate LOX-1 function. Because LOX-1 is increased in atherosclerotic plaques and contributes to endothelial dysfunction, several compounds were tested in vivo and in vitro to modulate the LOX-1 expression in therapeutic approaches.