High-Density Lipoprotein Therapy in Stroke: Evaluation of Endothelial SR-BI-Dependent Neuroprotective Effects

Scavenger Receptor Class B Type I Modulates Epileptic Seizures and Receptor α2δ-1 Expression

Scavenger receptor class B type I (SR-BI) is abundant in adult mouse and human brains, but its function in the central nervous system (CNS) remains unclear. This study explored the role of SR-BI in epilepsy and its possible underlying mechanism. Expression patterns of SR-BI in the brains of mice with kainic acid (KA)-induced epilepsy were detected using immunofluorescence staining, quantitative real-time polymerase chain reaction (qPCR), and Western blotting(WB). Behavioral analysis was performed by 24-hour video monitoring and hippocampal local field potential (LFP) recordings were employed to verify the role of SR-BI in epileptogenesis. RNA sequencing (RNA-seq) was used to obtain biological information on SR-BI in the CNS. WB, qPCR, and co-immunoprecipitation (Co-IP) were performed to identify the relationship between SR-BI and the gabapentin receptor α2δ-1.The results showed that SR-BI was primarily co-localized with astrocytes and its expression was down-regulated in the hippocampus of KA mice. Notably, overexpressing SR-BI alleviated the epileptic behavioral phenotype in KA mice. Hippocampal transcriptomic analysis revealed 1043 differentially expressed genes (DEGs) in the SR-BI-overexpressing group. Most DEGs confirmed by RNA-seq analysis were associated with synapses, neuronal projections, neuron development, and ion binding. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that the DEGs were enriched in the glutamatergic synapse pathway. Furthermore, the gabapentin receptor α2δ-1 decreased with SR-BI overexpression in epileptic mice. Overall, these findings highlight the important role of SR-BI in regulating epileptogenesis and that the gabapentin receptor α2δ-1 is a potential downstream target of SR-BI.

Association between neutrophil to high-density lipoprotein cholesterol ratio (NHR) and depression symptoms among the United States adults: a cross-sectional study

BACKGROUND

Depression acts as a noteworthy worldwide public health challenge. Identifying accessible biomarkers is crucial for early diagnosis and intervention. The relationship between depression in adult Americans and the neutrophil to high-density lipoprotein cholesterol ratio (NHR) was investigated in this research.

METHODS

The relationship between NHR and depressive symptoms was analyzed utilizing National Health and Nutrition Examination Survey data from 2005 to 2018 and the Patient Health Questionnaire-9. The study included 33,871 participants with complete NHR and depression data. Adjusted multivariable logistic regression models were used to account for possible confounders, and subgroup analyses were conducted to investigate effect changes.

RESULTS

Elevated NHR levels were positively correlated with a heightened risk of depression (OR = 1.03, 95% CI: 1.01-1.05, P < 0.0005). After the NHR was divided into tertiles, those in the top tertile had an 18% higher chance of developing depression than those in the bottom tertile (OR = 1.18; 95% CI: 1.05-1.32; P for trend = 0.0041). Subgroup analyses revealed variations in this association based on race and marital status. Additionally, the relationship between NHR and depression demonstrated a U-shaped pattern, with a significant breakpoint identified at an NHR of 6.97.

CONCLUSION

These results imply that the NHR may be a potential biomarker for depression risk, with implications for early detection and personalized treatment. Further research is needed to elucidate the mechanisms underlying the NHR-depression link and establish causality.

Association of Plasma Lipids with White Matter Hyperintensities in Patients with Acute Ischemic Stroke

Purpose

White matter hyperintensities (WMH) are the common marker of cerebral small vessel disease (CSVD). Dyslipidemia plays a notable role in the pathogenesis of CSVD. However, the relationship between dyslipidemia and WMH is poorly elucidated. This study aims to investigate the association between serum lipid fractions and WMH in patients with acute ischemic stroke (AIS).

Patients and Methods

A total of 901 patients with AIS were included in this study. The burden of WMH, including deep white matter hyperintensities (DWMH), periventricular white matter hyperintensities (PVWMH), and total WMH load, were evaluated on magnetic resonance imaging (MRI) by the Fazekas scale. All the WMH burden were set as dichotomous variables. Serum levels of triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) were collected. The association of serum lipid fractions with WMH burden was analyzed using univariate and multivariate logistic regression models.

Results

The average age of the participants was 67.6±11.6 years, and 584 cases (64.8%) were male. About 33.5% (n = 302) patients were smoker, and 23.5% (n = 212) patients had a history of alcohol consumption. The proportion of previous diabetes, ischemic cardiomyopathy and hypertension was 39.0% (n = 351), 21.2% (n = 191) and 75.9% (n = 684), respectively. The average of serum HDL-c, TC, TG, LDL-c levels for all participants were 1.26 ± 0.28 mmol/l, 4.54 ± 1.06 mmol/l, 1.67 ± 1.09 mmol/l, 3.08 ± 0.94 mmol/l. There were no statistical associations between HDL-c, TG, TC, LDL-c and each type of WMH burden (P > 0.05) in multivariate logistic regression analysis. Similar findings were found in subgroup analysis based on gender classification.

Conclusion

Serum lipid levels were not associated with the presence of any type of WMH in patients with AIS.

Bio-fabricated nanodrugs with chemo-immunotherapy to inhibit glioma proliferation and recurrence

Glioblastoma multiforme (GBM) is the most malignant brain tumor with high mortality. Knowledge of the stemness concept has developed recently, giving rising to a novel hallmark with therapeutic potential that can help in management of GBM recurrence and prognosis. However, limited blood-brain barrier (BBB) penetration, non-discriminatory distribution, and deficiency of diagnosis remain three major obstacles need to be overcome for further facilitating therapeutic effects. Herein, D4F and α-Melittin (a-Mel) are co-assembled to construct bio-fabricated nanoplatforms, which endowed with inherent BBB permeability, precise tumor accumulation, deep penetration, and immune activation. After carrying arsenic trioxide (ATO) and manganese dichloride (MnCl₂), these elaborated nanodrugs, Mel-LNPs/MnAs, gather in tumor foci by natural pathways and respond to microenvironment to synchronously release Mn²⁺ and As³⁺, achieving real-time navigating-diagnosis and tumor cell proliferation inhibition. Through down regulating CD44 and CD133 expression, the GBM stemness was suppressed to overcome its high recurrence, invasion, and chemoresistance. After being combined with temozolomide (TMZ), the survival rate of GBM-bearing mice is significantly enhanced, and the rate of recurrence is powerfully limited. Collectively, this tumor-specific actuating multi-modality nanotheranostics provide a promising candidate for clinical application with high security.

Recombinant High-Density Lipoprotein Boosts the Therapeutic Efficacy of Mild Hypothermia in Traumatic Brain Injury

Traumatic brain injury (TBI) leads to neuropsychiatric symptoms and increased risk of neurodegenerative disorders. Mild hypothermia is commonly used in patients suffering from severe TBI. However, its effect for long-term protection is limited, mostly because of its insufficient anti-inflammatory and neuroprotective efficacy and restricted treatment duration. Recombinant high-density lipoprotein (rHDL), which possesses anti-inflammatory and antioxidant activity and blood-brain barrier (BBB) permeability, was expected to potentially strengthen the therapeutic effect of mild hypothermia in TBI treatment. To test this hypothesis and optimize the regimen for combination therapy, the efficacy of mild hypothermia plus concurrent or sequential rHDL on oxidative stress, inflammatory reaction, and cell survival in the damaged brain cells was evaluated. It was found that the effect of combining mild hypothermia with concurrent rHDL was modest, as mild hypothermia inhibited the cellular uptake and lesion-site-targeting delivery of rHDL. In contrast, the combination of mild hypothermia with sequential rHDL more powerfully improved the anti-inflammatory and antioxidant activities, promoted nerve cell survival and BBB restoration, and ameliorated neurologic changes, which thus remarkably restored the spatial learning and memory ability of TBI mice. Collectively, these findings suggest that rHDL may serve as a novel nanomedicine for adjunctive therapy of TBI and highlight the importance of timing of combination therapy for optimal treatment outcome.

Brain Endothelial Cells in Contrary to the Aortic Do Not Transport but Degrade Low-Density Lipoproteins via Both LDLR and ALK1

The transport of low-density lipoprotein (LDL) through the endothelium is a key step in the development of atherosclerosis, but it is notorious that phenotypic differences exist between endothelial cells originating from different vascular beds. Endothelial cells forming the blood–brain barrier restrict paracellular and transcellular passage of plasma proteins. Here, we systematically compared brain versus aortic endothelial cells towards their interaction with LDL and the role of proteins known to regulate the uptake of LDL by endothelial cells. Both brain endothelial cells and aortic endothelial cells bind and internalize LDL. However, whereas aortic endothelial cells degrade very small amounts of LDL and transcytose the majority, brain endothelial cells degrade but do not transport LDL. Using RNA interference (siRNA), we found that the LDLR–clathrin pathway leads to LDL degradation in either endothelial cell type. Both loss- and gain-of-function experiments showed that ALK1, which promotes transcellular LDL transport in aortic endothelial cells, also limits LDL degradation in brain endothelial cells. SR-BI and caveolin-1, which promote LDL uptake and transport into aortic endothelial cells, limit neither binding nor association of LDL to brain endothelial cells. Together, these results indicate distinct LDL trafficking by brain microvascular endothelial cells and aortic endothelial cells.

Conductance Artery Wall Layers and Their Respective Roles in the Clearance Functions

Evolutionary organization of the arterial wall into layers occurred concomitantly with the emergence of a highly muscularized, pressurized arterial system that facilitates outward hydraulic conductance and mass transport of soluble substances across the arterial wall. Although colliding circulating cells disperse potential energy within the arterial wall, the different layers counteract this effect: (1) the endothelium ensures a partial barrier function; (2) the media comprises smooth muscle cells capable of endocytosis/phagocytosis; (3) the outer adventitia and perivascular adipocytic tissue are the final receptacles of convected substances. While the endothelium forms a physical and a biochemical barrier, the medial layer is avascular, relying on the specific permeability properties of the endothelium for metabolic support. Different components of the media interact with convected molecules: medial smooth muscle cells take up numerous molecules via scavenger receptors and are capable of phagocytosis of macro/micro particles. The outer layers-the highly microvascularized innervated adventitia and perivascular adipose tissue-are also involved in the clearance functions of the media: the adventitia is the seat of immune response development, inward angiogenesis, macromolecular lymphatic drainage, and neuronal stimulation. Consequently, the clearance functions of the arterial wall are physiologically essential, but also may favor the development of arterial wall pathologies. This review describes how the walls of large conductance arteries have acquired physiological clearance functions, how this is determined by the attributes of the endothelial barrier, governed by endocytic and phagocytic capacities of smooth muscle cells, impacting adventitial functions, and the role of these clearance functions in arterial wall diseases.

Macrophage SR-B1 in atherosclerotic cardiovascular disease

PURPOSE OF REVIEW

Scavenger receptor class B type 1 (SR-B1) promotes atheroprotection through its role in HDL metabolism and reverse cholesterol transport in the liver. However, evidence indicates that SR-B1 may impact atherosclerosis through nonhepatic mechanisms.

RECENT FINDINGS

Recent studies have brought to light various mechanisms by which SR-B1 affects lesional macrophage function and protects against atherosclerosis. Efferocytosis is efficient in early atherosclerotic lesions. At this stage, and beyond its role in cholesterol efflux, SR-B1 promotes free cholesterol-induced apoptosis of macrophages through its control of apoptosis inhibitor of macrophage (AIM). At more advanced stages, macrophage SR-B1 binds and mediates the removal of apoptotic cells. SR-B1 also participates in the induction of autophagy which limits necrotic core formation and increases plaque stability.

SUMMARY

These studies shed new light on the atheroprotective role of SR-B1 by emphasizing its essential contribution in macrophages during atherogenesis as a function of lesion stages. These new findings suggest that macrophage SR-B1 is a therapeutic target in cardiovascular disease.

Protective effects of adipose-derived biogenic nanoparticles on the pulmonary microvascular endothelial barrier in mice with ventilator-induced lung injury via the TRPV4/ROCK1 signalling pathway

PURPOSE

The "obesity paradox" phenomenon occurs in critically ill patients who receive mechanical ventilation. Our previous studies found that the adipose-derived exosomes secreted by obese mice have a protective effect on the pulmonary microvascular endothelial barrier. However, the extraction of exosomes is cumbersome, their yield is low, and their storage is difficult. After further research, we discovered a new type of adipose-derived bioactive material called: lipoaspirate nanoparticles (Lipo-NPs).

METHODS

Lipo-NPs were extracted and identified using a tangential flow filtration system. The Lipo-NPs were used as an intervention in ventilator-induced lung injury (VILI) models in vivo and in vitro to investigate whether they have a protective effect on lung tissue damage (haematoxylin and eosin staining), lung barrier function (lung wet/dry [W/D] weight ratio, protein concentration in bronchoalveolar lavage fluid (BALF), and Vascular endothelial (VE)-expression), as well as their related mechanisms.

RESULTS

In both in vivo and in vitro studies, Lipo-NPs can attenuate lung injury, reduce lung W/D ratio and protein concentration in BALF, and augment the expression of the adhesion link-protein VE-cadherin, thus playing a protective role in lung barrier function. This protective effect involves the activation of the transient receptor potential vanilloid 4 (TRPV4)/Rho-associated kinase1 (ROCK1) signalling pathway. We further verified the role of this signalling pathway via activation and inhibition of TRPV4 and ROCK1. Moreover, phosphorylation of myosin light chain 2 (MLC2) regulates F-actin and is a target of the ROCK pathway.

CONCLUSION

Lipo-NPs can enhance the expression of VE-cadherin by inhibiting the TRPV4/ROCK1/pMLC2 signalling pathway in the mechanical ventilation model, thereby exerting a protective effect on the VILI pulmonary microvascular endothelial barrier.

ApoA-I Nanoparticles as Curcumin Carriers for Cerebral Endothelial Cells: Improved Cytoprotective Effects against Methylglyoxal

Methylglyoxal (MGO) is a highly reactive metabolite of glucose present at elevated levels in diabetic patients. Its cytotoxicity is associated with endothelial dysfunction, which plays a role in cardiovascular and cerebrovascular complications. Although curcumin has many therapeutic benefits, these are limited due to its low bioavailability. We aimed to improve the bioavailability of curcumin and evaluate a potential synergistic effect of curcumin and reconstituted high-density lipoprotein (rHDL) nanoparticles (Cur-rHDLs) on MGO-induced cytotoxicity and oxidative stress in murine cerebrovascular endothelial cells (bEnd.3). Cur-rHDL nanoparticles (14.02 ± 0.95 nm) prepared by ultracentrifugation and containing curcumin were quantified by LC–MS/MS. The synergistic effect of cur-rHDL nanoparticles was tested on bEnd.3 cytotoxicity, reactive oxygen species (ROS) production, chromatin condensation, endoplasmic reticulum (ER) stress, and endothelial barrier integrity by impedancemetry. The uptake of curcumin, alone or associated with HDLs, was also assessed by mass spectrometry. Pretreatment with Cur-rHDLs followed by incubation with MGO showed a protective effect on MGO-induced cytotoxicity and chromatin condensation, as well as a strong protective effect on ROS production, endothelial cell barrier integrity, and ER stress. These results suggest that Cur-rHDLs could be used as a potential therapeutic agent to limit MGO-induced dysfunction in cerebrovascular endothelial cells by enhancing the bioavailability and protective effects of curcumin.

A Nomogram That Includes Neutrophils and High-Density Lipoprotein Cholesterol Can Predict the Prognosis of Acute Ischaemic Stroke

Lipids are implicated in inflammatory responses affecting acute ischaemic stroke prognosis. Therefore, we aimed to develop a predictive model that considers neutrophils and high-density lipoprotein cholesterol to predict its prognosis. This prospective study enrolled patients with acute ischaemic stroke within 24 h of onset between January 2015 and December 2017. The main outcome was a modified Rankin Scale score ≥3 at the 90th day of follow-up. Patients were divided into training and testing sets. The training set was divided into four states according to the median of neutrophils and high-density lipoprotein cholesterol levels in all patients. Through binary logistic regression analysis, the relationship between factors and prognosis was determined. A nomogram based on the results was developed; its predictive value was evaluated through internal and external validations. Altogether, 1,090 patients were enrolled with 872 (80%) and 218 (20%) in the training and testing sets, respectively. In the training set, the major outcomes occurred in 24 (10.4%), 24 (11.6%), 37 (17.2%), and 49 (22.3%) in states 1–4, respectively (P = 0.002). Validation of calibration and decision curve analyses showed that the nomogram showed better performance. The internal and external testing set receiver operating characteristics verified the predictive value [area under the curve = 0.794 (0.753–0.834), P &lt; 0.001, and area under the curve = 0.973 (0.954–0.992), P &lt; 0.001, respectively]. A nomogram that includes neutrophils and high-density lipoprotein cholesterol can predict the prognosis of acute ischaemic stroke, thus providing us with an effective visualization tool.

Lack of Neuroprotective Effects of High-Density Lipoprotein Therapy in Stroke under Acute Hyperglycemic Conditions

Introduction: The pleiotropic protective effects of high-density lipoproteins (HDLs) on cerebral ischemia have never been tested under acute hyperglycemic conditions. The aim of this study is to evaluate the potential neuroprotective effect of HDL intracarotid injection in a mouse model of middle cerebral artery occlusion (MCAO) under hyperglycemic conditions. Methods: Forty-two mice were randomized to receive either an intracarotid injection of HDLs or saline. Acute hyperglycemia was induced by an intraperitoneal injection of glucose (2.2 g/kg) 20 min before MCAO. Infarct size (2,3,5-triphenyltetrazolium chloride (TTC)-staining), blood–brain barrier leakage (IgG infiltration), and hemorrhagic changes (hemoglobin assay by ELISA and hemorrhagic transformation score) were analyzed 24 h post-stroke. Brain tissue inflammation (IL-6 by ELISA, neutrophil infiltration and myeloperoxidase by immunohisto-fluorescence) and apoptosis (caspase 3 activation) were also assessed. Results: Intraperitoneal D-glucose injection allowed HDL- and saline-treated groups to reach a blood glucose level of 300 mg/dl in the acute phase of cerebral ischemia. HDL injection did not significantly reduce mortality (19% versus 29% in the saline-injected group) or cerebral infarct size (p = 0.25). Hemorrhagic transformations and inflammation parameters were not different between the two groups. In addition, HDL did not inhibit apoptosis under acute hyperglycemic conditions. Conclusion: We observed a nonsignificant decrease in cerebral infarct size in the HDL group. The deleterious consequences of reperfusion such as hemorrhagic transformation or inflammation were not improved by HDL infusion. In acute hyperglycemia, HDLs are not potent enough to counteract the adverse effects of hyperglycemia. The addition of antioxidants to therapeutic HDLs could improve their neuroprotective capacity.

Molecular Mechanisms of Neuroimmune Crosstalk in the Pathogenesis of Stroke

Stroke disrupts the homeostatic balance within the brain and is associated with a significant accumulation of necrotic cellular debris, fluid, and peripheral immune cells in the central nervous system (CNS). Additionally, cells, antigens, and other factors exit the brain into the periphery via damaged blood–brain barrier cells, glymphatic transport mechanisms, and lymphatic vessels, which dramatically influence the systemic immune response and lead to complex neuroimmune communication. As a result, the immunological response after stroke is a highly dynamic event that involves communication between multiple organ systems and cell types, with significant consequences on not only the initial stroke tissue injury but long-term recovery in the CNS. In this review, we discuss the complex immunological and physiological interactions that occur after stroke with a focus on how the peripheral immune system and CNS communicate to regulate post-stroke brain homeostasis. First, we discuss the post-stroke immune cascade across different contexts as well as homeostatic regulation within the brain. Then, we focus on the lymphatic vessels surrounding the brain and their ability to coordinate both immune response and fluid homeostasis within the brain after stroke. Finally, we discuss how therapeutic manipulation of peripheral systems may provide new mechanisms to treat stroke injury.

Carnosine Protects against Cerebral Ischemic Injury by Inhibiting Matrix-Metalloproteinases

Stroke is one of the leading causes of death and disability worldwide. However, treatment options for ischemic stroke remain limited. Matrix-metalloproteinases (MMPs) contribute to brain damage during ischemic strokes by disrupting the blood-brain barrier (BBB) and causing brain edemas. Carnosine, an endogenous dipeptide, was found by us and others to be protective against ischemic brain injury. In this study, we investigated whether carnosine influences MMP activity. Brain MMP levels and activity were measured by gelatin zymography after permanent occlusion of the middle cerebral artery (pMCAO) in rats and in vitro enzyme assays. Carnosine significantly reduced infarct volume and edema. Gelatin zymography and in vitro enzyme assays showed that carnosine inhibited brain MMPs. We showed that carnosine inhibited both MMP-2 and MMP-9 activity by chelating zinc. Carnosine also reduced the ischemia-mediated degradation of the tight junction proteins that comprise the BBB. In summary, our findings show that carnosine inhibits MMP activity by chelating zinc, an essential MMP co-factor, resulting in the reduction of edema and brain injury. We believe that our findings shed new light on the neuroprotective mechanism of carnosine against ischemic brain damage.

The Endothelium Is Both a Target and a Barrier of HDL's Protective Functions

The vascular endothelium serves as a barrier between the intravascular and extravascular compartments. High-density lipoproteins (HDL) have two kinds of interactions with this barrier. First, bloodborne HDL must pass the endothelium to access extravascular tissues, for example the arterial wall or the brain, to mediate cholesterol efflux from macrophages and other cells or exert other functions. To complete reverse cholesterol transport, HDL must even pass the endothelium a second time to re-enter circulation via the lymphatics. Transendothelial HDL transport is a regulated process involving scavenger receptor SR-BI, endothelial lipase, and ATP binding cassette transporters A1 and G1. Second, HDL helps to maintain the integrity of the endothelial barrier by (i) promoting junction closure as well as (ii) repair by stimulating the proliferation and migration of endothelial cells and their progenitor cells, and by preventing (iii) loss of glycocalix, (iv) apoptosis, as well as (v) transmigration of inflammatory cells. Additional vasoprotective functions of HDL include (vi) the induction of nitric oxide (NO) production and (vii) the inhibition of reactive oxygen species (ROS) production. These vasoprotective functions are exerted by the interactions of HDL particles with SR-BI as well as specific agonists carried by HDL, notably sphingosine-1-phophate (S1P), with their specific cellular counterparts, e.g., S1P receptors. Various diseases modify the protein and lipid composition and thereby the endothelial functionality of HDL. Thorough understanding of the structure-function relationships underlying the multiple interactions of HDL with endothelial cells is expected to elucidate new targets and strategies for the treatment or prevention of various diseases.