Publications by authors named "Hang Xi"

Background: Hyperhomocysteinemia (HHcy) has been linked to development of Alzheimer's disease (AD) neuropathologically characterized by the accumulation of amyloid β (Aβ). Microglia (MG) play a crucial role in uptake of Aβ fibrils, and its dysfunction worsens AD. However, the effect of HHcy on MG Aβ phagocytosis remains unstudied.

View Article and Find Full Text PDF

To determine whether pro-inflammatory lipid lysophosphatidylinositols (LPIs) upregulate the expressions of membrane proteins for adhesion/signaling and secretory proteins in human aortic endothelial cell (HAEC) activation, we developed an EC biology knowledge-based transcriptomic formula to profile RNA-Seq data panoramically. We made the following primary findings: first, G protein-coupled receptor 55 (GPR55), the LPI receptor, is expressed in the endothelium of both human and mouse aortas, and is significantly upregulated in hyperlipidemia; second, LPIs upregulate 43 clusters of differentiation (CD) in HAECs, promoting EC activation, innate immune trans-differentiation, and immune/inflammatory responses; 72.1% of LPI-upregulated CDs are not induced in influenza virus-, MERS-CoV virus- and herpes virus-infected human endothelial cells, which hinted the specificity of LPIs in HAEC activation; third, LPIs upregulate six types of 640 secretomic genes (SGs), namely, 216 canonical SGs, 60 caspase-1-gasdermin D (GSDMD) SGs, 117 caspase-4/11-GSDMD SGs, 40 exosome SGs, 179 Human Protein Atlas (HPA)-cytokines, and 28 HPA-chemokines, which make HAECs a large secretory organ for inflammation/immune responses and other functions; fourth, LPIs activate transcriptomic remodeling by upregulating 172 transcription factors (TFs), namely, pro-inflammatory factors NR4A3, FOS, KLF3, and HIF1A; fifth, LPIs upregulate 152 nuclear DNA-encoded mitochondrial (mitoCarta) genes, which alter mitochondrial mechanisms and functions, such as mitochondrial organization, respiration, translation, and transport; sixth, LPIs activate reactive oxygen species (ROS) mechanism by upregulating 18 ROS regulators; finally, utilizing the Cytoscape software, we found that three mechanisms, namely, LPI-upregulated TFs, mitoCarta genes, and ROS regulators, are integrated to promote HAEC activation.

View Article and Find Full Text PDF

Recent clinical trials reported that increasing high-density lipoprotein-cholesterol (HDL-C) levels does not improve cardiovascular outcomes. We hypothesize that HDL proteome dynamics determine HDL cardioprotective functions. In this study, we characterized proteome profiles in HDL subclasses and established their functional connection.

View Article and Find Full Text PDF
Article Synopsis
  • Nuclear receptors (NRs) are important transcription factors that regulate gene expression, but their roles in human tissues, atherosclerosis, and inflammation are not completely understood.
  • Researchers analyzed how NRs are expressed in different human and mouse tissues under various conditions and discovered that NRs exhibit tissue-specific expression regulated by various biological pathways.
  • The study suggests that many NRs act as anti-inflammatory receptors and highlights their potential as therapeutic targets for diseases like cancer, metabolic disorders, and inflammatory conditions.
View Article and Find Full Text PDF

Adaptive immunity is critical for disease progression and modulates T cell (TC) and antigen-presenting cell (APC) functions. Three signals were initially proposed for adaptive immune activation: signal 1 antigen recognition, signal 2 co-stimulation or co-inhibition, and signal 3 cytokine stimulation. In this article, we propose to term signal 2 as an immune checkpoint, which describes interactions of paired molecules leading to stimulation (stimulatory immune checkpoint) or inhibition (inhibitory immune checkpoint) of an immune response.

View Article and Find Full Text PDF

Endocytosis is a cellular process mostly responsible for membrane receptor internalization. Cell membrane receptors bind to their ligands and form a complex which can be internalized. We previously proposed that F-BAR protein initiates membrane curvature and mediates endocytosis via its binding partners.

View Article and Find Full Text PDF

Background: Caspase-1 is present in the cytosol as an inactive zymogen and requires the protein complexes named "inflammasomes" for proteolytic activation. However, it remains unclear whether the proteolytic activity of caspase-1 is confined only to the cytosol where inflammasomes are assembled to convert inactive pro-caspase-1 to active caspase-1.

Methods: We conducted meticulous data analysis methods on proteomic, protein interaction, protein intracellular localization, and gene expressions of 114 experimentally identified caspase-1 substrates and 38 caspase-1 interaction proteins in normal physiological conditions and in various pathologies.

View Article and Find Full Text PDF

Rationale: Endothelial injury is an initial mechanism mediating cardiovascular disease.

Objective: Here, we investigated the effect of hyperhomocysteinemia on programed cell death in endothelial cells (EC).

Methods And Results: We established a novel flow-cytometric gating method to define pyrotosis (Annexin V(-)/Propidium iodide(+)).

View Article and Find Full Text PDF

Aging involves progressive loss of cellular function and integrity, presumably caused by accumulated stochastic damage to cells. Alterations in energy metabolism contribute to aging, but how energy metabolism changes with age, how these changes affect aging, and whether they can be modified to modulate aging remain unclear. In locomotory muscle of post-fertile Caenorhabditis elegans, we identified a progressive decrease in cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), a longevity-associated metabolic enzyme, and a reciprocal increase in glycolytic pyruvate kinase (PK) that were necessary and sufficient to limit lifespan.

View Article and Find Full Text PDF

Background: Levodopa-induced dyskinesia (LID) is a disabling complication of levodopa therapy in Parkinson's disease (PD) with no effective treatments. Fluctuations in levels of levodopa constitute a key risk factor of LID. There is a pressing need for the development of a simple animal model of LID.

View Article and Find Full Text PDF

Vascular response is an essential pathological mechanism underlying various inflammatory diseases. This study determines whether IL-35, a novel responsive anti-inflammatory cytokine, inhibits vascular response in acute inflammation. Using a mouse model of LPS-induced acute inflammation and plasma samples from sepsis patients, we found that IL-35 was induced in the plasma of mice after LPS injection as well as in the plasma of sepsis patients.

View Article and Find Full Text PDF

Deficient angiogenesis may contribute to worsen the prognosis of myocardial ischemia, peripheral arterial disease, ischemic stroke, etc. Dyslipidemic and inflammatory environments attenuate endothelial cell (EC) proliferation and angiogenesis, worsening the prognosis of ischemia. Under these dyslipidemic and inflammatory environments, EC-caspase-1 becomes activated and induces inflammatory cell death that is defined as pyroptosis.

View Article and Find Full Text PDF

Objective: The role of receptors for endogenous metabolic danger signals-associated molecular patterns has been characterized recently as bridging innate immune sensory systems for danger signals-associated molecular patterns to initiation of inflammation in bone marrow-derived cells, such as macrophages. However, it remains unknown whether endothelial cells (ECs), the cell type with the largest numbers and the first vessel cell type exposed to circulating danger signals-associated molecular patterns in the blood, can sense hyperlipidemia. This report determined whether caspase-1 plays a role in ECs in sensing hyperlipidemia and promoting EC activation.

View Article and Find Full Text PDF

Atherosclerosis, a pathological process that underlies the development of cardiovascular disease, is the primary cause of morbidity and mortality in patients with type 2 diabetes mellitus (T2DM). T2DM is characterized by hyperglycemia and insulin resistance (IR), in which target tissues fail to respond to insulin. Systemic IR is associated with impaired insulin signaling in the metabolic tissues and vasculature.

View Article and Find Full Text PDF

Most of the available evidence on the role of neutrophils on pathological cardiac remodeling has been pertained after acute myocardial infarction. However, whether neutrophils directly contribute to the pathogenesis of cardiac remodeling after events other than acute myocardial infarction remains unknown. Here we show that acute eccentric hypertrophy induced by aorto-caval fistula (ACF) in the rats induced an increase in the inflammatory response characterized by activation of the STAT pathway and increased infiltration of neutrophils in the myocardium.

View Article and Find Full Text PDF
Article Synopsis
  • The study examined the effects of edaravone, a powerful free radical scavenger, on oxidative stress-related damage to endothelial cells and its potential in preventing early atherosclerosis using animal models and cultured cells.
  • Findings showed that edaravone significantly reduced endothelial cell apoptosis induced by hydrogen peroxide (H2O2) and decreased atherosclerotic lesions in mice on a high-cholesterol diet, without affecting plasma lipid levels or blood pressure.
  • The results indicate that edaravone has the potential to protect against early atherosclerosis, but further clinical studies are needed to confirm its effectiveness in humans.
View Article and Find Full Text PDF

Background: The TO-2 hamster is an animal model of dilated cardiomyopathy (DCM). It has genetic and clinical features in common with humans who carry the gene deletion or mutation of the delta-sarcoglycan (SG) gene, a component in dystrophin-related proteins (DRP). DRP stabilise the sarcolemma during cardiac contraction.

View Article and Find Full Text PDF

Background: The effects of angiotensin converting enzyme (ACE) inhibitors on oxidative stress-induced apoptosis of endothelial cells and the intracellular signaling were investigated.

Methods: Cultured endothelial cells derived from a bovine carotid artery were treated with H2O2 or TNF-alpha to induce apoptosis. Apoptosis was evaluated by DNA fragmentation and cell viability, p38 MAP kinase activity by Western blotting, and oxidative stress by formation of 8-isoprostane.

View Article and Find Full Text PDF

The role of the renin-angiotensin system in oxidative stress-induced apoptosis of endothelial cells (ECs) was investigated using a rat model and cultured ECs. EC apoptosis was induced by 5-minute intra-arterial treatment of a rat carotid artery with 0.01 mmol/L H2O2 and was evaluated at 24 hours by chromatin staining of en face specimens with Hoechst 33342.

View Article and Find Full Text PDF

Real-time three-dimensional (3-D) color Doppler echocardiography (RT3D) is capable of quantifying flow. However, low temporal resolution limits its application to stroke volume (SV) measurements. The aim of the present study was, therefore, to develop a reliable method to quantify SV.

View Article and Find Full Text PDF