Endothelial Cell Inflammation Research Articles

Mitochondrial Mechanisms of Endothelial Cell Damage in Alzheimer’s Disease and Cerebral Amyloid Angiopathy

AbstractBackgroundCerebrovascular endothelial cells (EC) are crucial regulators of cerebral homeostasis and function through the maintenance of the blood‐brain barrier (BBB). ECs damage and/or dysfunction may result in defects in brain clearance and perfusion, microhemorrhages, inflammation, and neurodegeneration. Damage to the ECs may result from cardiovascular risk factors (CVRF) such as high levels of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy). In Alzheimer’s Disease (AD) and Cerebral Amyloid Angiopathy (CAA), the presence of a CVRF may further exacerbate cerebrovascular function and neurodegeneration. EC do not rely highly on mitochondrial ATP production as they are glycolytic cells. Instead, EC mitochondria serve mostly as signaling organelles, which sense cellular damage and mediate downstream pathways such as inflammation. In this study, we aim to understand the mechanistic nature of endothelial mitochondrial dysfunction and its elicited pathways in Aβ‐ and mixed (Aβ+HHcy)‐mediated vascular pathologies. Understanding the mechanisms by which the mitochondria mediate EC inflammation, may pave the way to new roads for therapeutic advancements in the field.MethodHuman brain microvascular ECs were challenged with Aβ, Hcy, or the combination. Mitochondrial metabolic function, inflammatory cascades and signals, and EC barrier function were assessed.ResultThe presence of Aβ, but not Hcy, induced deficits in mitochondrial respiration and ATP production. In addition, there is evidence of mitochondrial fragmentation and the expression of fission proteins. Preliminary results further suggest a release of mitochondrial danger associated molecular patterns (mtDAMPs) that can promote an inflammatory cascade. The mitochondrial damage and subsequent inflammatory response are associated with an increase in EC barrier permeability and cytokine release, which is exacerbated in the presence of Hcy.ConclusionThe EC dysfunction associated with Aβ is accompanied by severe deficits in mitochondrial metabolism and the release of mtDAMPS. The presence of Hcy exacerbates some of the detrimental effects of Aβ, particularly on mtDAMPS and BBB function, but Hcy does not appear to affect mitochondrial metabolic changes. Overall, our results reveal a novel role for mtDAMPs in vascular dysfunction in the presence of Aβ and/or Hcy.

Colchicine delivered by a novel nanoparticle platform alleviates atherosclerosis by targeted inhibition of NF-κB/NLRP3 pathways in inflammatory endothelial cells

Atherosclerosis, a chronic inflammatory disease characterized by arterial plaque formation, is one of the most prominent causes of cardiovascular diseases. However, the current treatments often do not adequately compromise the chronic inflammation-mediated plaque accumulation and the disease progression. Therefore, a new and effective strategy that blocks atherosclerosis-associated inflammation is urgently needed to further reduce the risk. Colchicine, a potent anti-inflammatory medication, has shown great potential in the treatment of atherosclerosis, but its adverse effects have hampered its clinical application. Herein, we developed a novel delivery nanosystem encapsulated with colchicine (VHPK-PLGA@COL), which exhibited improved biosafety and sustained drug release along with the gradual degradation of PLGA and PEG as confirmed both in vitro and in vivo. Surface modification of the nanoparticles with the VHPK peptide ensured its capability to specifically target inflammatory endothelial cells and alleviate atherosclerotic plaque accumulation. In the ApoE − / − atherosclerotic mouse model, both colchicine and VHPK-PLGA@COL treatment significantly decreased the plaque area and enhanced plaque stability by blocking the NF-κB/NLRP3 pathways, while VHPK-PLGA@COL exhibited enhanced therapeutic effects due to its unique ability to target inflammatory endothelial cells without obvious long-term safety concerns. In summary, VHPK-PLGA@COL has the potential to overcome the key translational barriers of colchicine and open new avenues to repurpose this drug for anti-atherosclerotic therapy.

Modulation of Heme-Induced Inflammation Using MicroRNA-Loaded Liposomes: Implications for Hemolytic Disorders Such as Malaria and Sickle Cell Disease.

Hemolytic disorders, like malaria and sickle cell disease (SCD), are responsible for significant mortality and morbidity rates globally, specifically in the Americas and Africa. In both malaria and SCD, red blood cell hemolysis leads to the release of a cytotoxic heme that triggers the expression of unique inflammatory profiles, which mediate the tissue damage and pathogenesis of both diseases. MicroRNAs (miRNAs), such as miR-451a and let-7i-5p, contribute to a reduction in the pro-inflammatory responses induced by circulating free hemes. MiR-451a targets both IL-6R (pro-inflammatory) and 14-3-3ζ (anti-inflammatory), and when this miRNA is present, IL-6R is reduced and 14-3-3ζ is increased. Let-7i-5p targets and reduces TLR4, which results in anti-inflammatory signaling. These gene targets regulate inflammation via NFκB regulation and increase anti-inflammatory signaling. Additionally, they indirectly regulate the expression of key heme scavengers, such as heme-oxygenase 1 (HO-1) (coded by the HMOX1 gene) and hemopexin, to decrease circulating cytotoxic heme concentration. MiRNAs can be transported within extracellular vesicles (EVs), such as exosomes, offering insights into the mechanisms of mitigating heme-induced inflammation. We tested the hypothesis that miR-451a- or let-7i-5p-loaded artificial EVs (liposomes) will reduce heme-induced inflammation in brain vascular endothelial cells (HBEC-5i, ATCC: CRL-3245) and macrophages (THP-1, ATCC: TIB-202) in vitro. We completed arginase and nitric oxide assays to determine anti- and pro-inflammatory macrophage presence, respectively. We also assessed the gene expression of IL-6R, TLR4, 14-3-3ζ, and NFκB by RT-qPCR for both cell lines. Our findings revealed that the exposure of HBEC-5i and THP-1 to liposomes loaded with miR-451a or let-7i-5p led to a reduced mRNA expression of IL-6R, TLR4, 14-3-3ζ, and NFκB when treated with a heme. It also resulted in the increased expression of HMOX1 and hemopexin. Finally, macrophages exhibited a tendency toward adopting an anti-inflammatory differentiation phenotype. These findings suggest that miRNA-loaded liposomes can modulate heme-induced inflammation and can be used to target specific cellular pathways, mediating inflammation common to hematological conditions, like malaria and SCD.

Changes of plasma Rap1A levels in patients with in-stent restenosis after percutaneous coronary intervention and the underlying mechanisms.

Percutaneous coronary intervention (PCI) is one of the most important treatments for coronary artery disease (CAD). However, in-stent restenosis (ISR) after PCI is a serious complication without effective measures for prevention and treatment. This study aims to investigate the Ras-related protein 1A (Rap1A) level in ISR patients and in the tumor necrosis factor-α (TNF-α)-induced inflammatory injury model of human umbilical vein endothelial cells (HUVECs), to explore the role of Rap1A in regulating TNF-α-induced inflammation in HUVECs and to provide a new potential target for ISR prevention and treatment. A total of 60 CAD patients, who underwent PCI between December 2020 and July 2022 from the Department of Cardiovascular Medicine of Xiangya Hospital, Central South University, and re-examined coronary angiography (CAG) 1 year after the operation, were included. After admission, 27 patients were diagnosed with ISR and 33 patients were diagnosed with non-in-stent restenosis (non-ISR) according to the CAG. Clinical data were collected, and the plasma Rap1A level was determined by enzyme linked immunosorbent assay (ELISA). In cell experiments, an inflammatory injury model was established with TNF-α treatment (10 ng/mL, 24 h) in HUVECs. The mRNA and protein expression levels of Rap1A, interlukin-6 (IL-6), and vascular cell adhesion molecule-1 (VCAM-1) were measured by real-time reverse transcription PCR and Western blotting. Small interfering RNA (siRNA) was used to explore the role of Rap1A in regulating TNF-α-induced inflammation in HUVECs. Compared with the non-ISR patients, a higher proportion of ISR patients had a history of smoking (P=0.005) and diabetes (P=0.028), and higher levels of glycosylated hemoglobin (HbA1c) (P=0.012), low-density lipoprotein cholesterol (LDL-c) (P=0.014), and hypersensitive C-reactive protein (hs-CRP) (P=0.027). The remaining projects did not show significant differences (all P>0.05). The plasma level of Rap1A in the ISR group was significantly higher than that in the non-ISR group [942.14 (873.28 to 1 133.81) μg/mL vs 886.93 (812.61 to 930.98) μg/mL; P=0.004]. Diabetes, LDL-c, and Rap1A were risk factors for ISR by univariate logistic regression analysis (all P<0.05). The mRNA and protein expression levels of inflammatory factors IL-6 and VCAM-1 were increased in HUVECs after 10 ng/mL TNF-α treatment for 24 h compared with the control group (all P<0.05), while the mRNA and protein levels of Rap1A were increased (both P<0.05). After inhibition of Rap1A in HUVECs, the mRNA and protein expression levels of IL-6 and VCAM-1 were significantly decreased (all P<0.05). The plasma Rap1A level was significantly elevated in patients with ISR, suggesting that Rap1A may be a potential biomarker for predicting ISR. In the TNF-α- induced HUVECs inflammatory injury model, the expression level of Rap1A was increased. The level of TNF-α-induced endothelial cell inflammation was decreased after inhibition of Rap1A expression, suggesting that Rap1A may be a potential target for the treatment of endothelial cell inflammation in ISR.

Effect and mechanism of ubiquitin-like protein FAT10 on AngⅡ induced endothelial cell inflammation

Objective: To investigate the role and related mechanism of ubiquitin-like protein FAT10 in the angiotensin Ⅱ (AngⅡ)-induced endothelial cell inflammatory responses. Methods: The Western blot was used to detect the protein expression of FAT10 in 16-weeks old WKY rat carotid artery, thoracic aorta artery, renal artery and vascular smooth muscle cells (VSMC), human umbilical vein endothelial cells (HUVEC) and human breast cancer cells (MDA-MB-231). The optimal concentration and stimulation time of AngⅡ on inducing the highest FAT10 in HUVEC were determined. The following plasmids were constructed: control plasmid, overexpression FAT10 plasmid (Flag-FAT10), invalid interference plasmid, and interference FAT10 plasmid (sh-FAT10). These plasmids were then transfected into HUVEC cells and divided into following groups: control group, Flag-FAT10 group, invalid interference group, and sh-FAT10 group. After culturing with 100 nmol/L AngⅡ for 36 h, the control group and the Flag-FAT10 group were treated with reactive oxygen species scavenger N-acetyl-L-cysteine ​​(NAC), the protein expression levels of the inflammatory factor monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) were measured. Laser confocal microscopy was used to detect the generation levels of reactive oxygen species in the cells of vrious groups. Results: FAT10 was expressed in carotid artery, thoracic aorta, and renal artery of normal blood pressure rats and expressed in HUVEC, VSMC, MDA-MB-231. The expression level of FAT10 gradually increased in proportion to the increase of the time and concentration of AngⅡ stimulation in HUVEC, and the expression level of FAT10 was the highest when the HUVEC was treated with 100 nmol/L AngⅡ for 36 h (P<0.01). The protein expression level of MCP-1 (P<0.001) and TNF-α (P<0.01) was higher in AngⅡ treated HUVEC with FAT10 overexpression, while the expression level of MCP-1 and TNF-α protein was lower in AngⅡ treated HUVEC with FAT10 knockdown (all P<0.01). The level of intracellular reactive oxygen species (ROS) production was significantly increased with FAT10 overexpression (P<0.001), and the level of ROS was decreased when the expression of FAT10 was interfered (P<0.05). The increased level of MCP-1 and TNF-α proteins in FAT10 overexpressed HUVEC was reversed by NAC (all P<0.05). Conclusion: FAT10 promotes the release of inflammatory factors induced by AngⅡ in endothelial cells by increasing the level of intracellular ROS production.

Effects of circulating endothelial microvesicles isolated from adults with obesity on endothelial cell inflammation, apoptosis, and nitric oxide production.

Circulating endothelial cell-derived microvesicles (EMVs) have been shown to be elevated with obesity and associated with endothelial dysfunction; however, their direct effect on endothelial cells is unknown. The experimental aim of this study was to determine the effect of EMVs isolated from adults with obesity on endothelial cell inflammation, apoptosis, and nitric oxide (NO) production. EMVs (CD144+ microvesicles) were identified, enumerated, and isolated from plasma by flow cytometry from 24 sedentary adults: 12 normal-weight adults [8 M/4 F; age: 55 ± 6 yr; body mass index (BMI): 24.3 ± 0.7 kg/m2; EMV: 144 ± 53 EMVs/µL] and 12 adults with obesity (6 M/6 F; 59 ± 7 yr; BMI: 31.0 ± 1.1 kg/m2; EMV: 245 ± 89 EMVs/µL). Human umbilical vein endothelial cells were cultured and treated with EMVs from either normal-weight adults or adults with obesity. EMVs from obese adults induced significantly higher release of interleukin (IL)-6 (108.2 ± 7.7 vs. 90.9 ± 10.0 pg/mL) and IL-8 (75.4 ± 9.8 vs. 59.5 ± 11.5 pg/mL) from endothelial cells vs. EMVs from normal-weight adults, concordant with greater intracellular expression of phosphorylated NF-κB p65 (Ser536; active NF-κB) [145.0 ± 34.1 vs. 114.5 ± 30.4 arbitrary units (AU)]. Expression of phosphorylated p38-MAPK (15.4 ± 5.7 vs. 9.2 ± 2.5 AU) and active caspase-3 (168.2 ± 65.5 vs. 107.8 ± 40.5 AU), markers of cell apoptosis, was higher in cells treated with obesity-related EMVs. Phosphorylated endothelial nitric oxide synthase (eNOS) (Ser1177) expression (23.5 ± 7.2 vs. 34.7 ± 9.7 AU) and NO production (6.9 ± 1.4 vs. 8.7 ± 0.7 µmol/L) were significantly lower in the cells treated with EMVs from obese adults. These data indicate that circulating EMVs from adults with obesity promote a proinflammatory, proapoptotic, and NO-compromised endothelial phenotype. Circulating EMVs are a potential mediator of obesity-related endothelial dysfunction.NEW & NOTEWORTHY In the present study, we determined the effect of circulating endothelial cell-derived microvesicles (EMVs) isolated from adults with obesity on endothelial cell inflammation, apoptosis, and nitric oxide (NO) production in vitro. Circulating EMVs harvested from adults with obesity promoted a proinflammatory, proapoptotic, and NO-compromised endothelial phenotype. Elevated circulating EMVs in adults with obesity, independent of other cardiometabolic risk factors, are a potential novel systemic mediator of obesity-related endothelial dysfunction and vascular risk.

Differential vascular endothelial cell toxicity of established and novel BCR-ABL tyrosine kinase inhibitors.

BCR-ABL tyrosine kinase inhibitors (TKIs) have dramatically improved survival in Philadelphia chromosome-positive leukemias. Newer BCR-ABL TKIs provide superior cancer outcomes but with increased risk of acute arterial thrombosis, which further increases in patients with cardiovascular comorbidities and mitigates survival benefits compared to imatinib. Recent studies implicate endothelial cell (EC) damage in this toxicity by unknown mechanisms with few side-by-side comparisons of multiple TKIs and with no available data on endothelial impact of recently approved TKIs or novels TKIs being tested in clinical trials. To characterize BCR-ABL TKI induced EC dysfunction we exposed primary human umbilical vein ECs in 2D and 3D culture to clinically relevant concentrations of seven BCR-ABL TKIs and quantified their impact on EC scratch-wound healing, viability, inflammation, and permeability mechanisms. Dasatinib, ponatinib, and nilotinib, the TKIs associated with thrombosis in patients, all significantly impaired EC wound healing, survival, and proliferation compared to imatinib, but only dasatinib and ponatinib impaired cell migration and only nilotinib enhanced EC necrosis. Dasatinib and ponatinib increased leukocyte adhesion to ECs with upregulation of adhesion molecule expression in ECs (ICAM1, VCAM1, and P-selectin) and leukocytes (PSGL1). Dasatinib increased permeability and impaired cell junctional integrity in human engineered microvessels, consistent with its unique association with pleural effusions. Of the new agents, bafetinib decreased EC viability and increased microvessel permeability while asciminib and radotinib did not impact any EC function tested. In summary, the vasculotoxic TKIs (dasatinib, ponatinib, nilotinib) cause EC toxicity but with mechanistic differences, supporting the potential need for drug-specific vasculoprotective strategies. Asciminib and radotinib do not induce EC toxicity at clinically relevant concentrations suggesting a better safety profile.

Moutan cortex exerts blood-activating and anti-inflammatory effects by regulating coagulation-inflammation cascades pathway in cells, rats and zebrafish

Ethnopharmacological relevanceAs a traditional Chinese medicine, raw Moutan Cortex (RMC) has been used in clinical practice for thousands of years. However, its blood-cooling and blood-activating medicinal effects as well as the underlying mechanisms have not been preliminarily verified until recent years. Aim of the studyOur group's previous network pharmacological studies suggested that RMC might exert its blood-activating and anti-inflammatory effects by modulating the coagulation-inflammation cascade pathway. Therefore, the present study aimed to further investigate the mechanisms relevant to the blood-activating and anti-inflammatory effects of RMC so as to provide more robust data supporting its clinical application. Materials and methodsThe inflammation and coagulation models of human umbilical vein endothelial cells (HUVECs) were induced by TNF-α; The rat models with blood-heat and blood-stasis syndrome (BHS) were constructed by ice-water bath with a combined use of epinephrine hydrochloride and dried yeast; The thrombus models of zebrafish were induced by arachidonic acid, and the inflammation models were established using LPS and CuSO4. The regulatory effects of RMC on the key targets in the pathway of the coagulation-inflammation cascade were investigated by combining ELISA, RT-PCR, and western blot techniques in an attempt to provide multiple validations concerning RMC's pharmacological efficacy and mechanism associated with cooling blood and activating blood circulation. ResultThe findings from the pharmacodynamic research demonstrated that RMC could inhibit the coagulation and inflammation process of HUVECs. Besides, it lowered the anal temperature and whole blood viscosity in BHS rats in addition to a prolongation of their prothrombin time (PT), thrombin time (TT), and activated partial thromboplastin time (APTT). Successfully constrained thrombotic area and reduced inflammatory cell counts were also observed in zebrafish models. Meanwhile, ELISA, RT-PCR and WB showed that RMC were capable of inhibiting the factors related to coagulation-MARK inflammation pathway—FⅡ, TF, FⅦ, FⅧ, FⅩ, and PAI, as well as down-regulating the expression of IL-6, COX-2, iNOS, TNF-α, ERK, JNK and p38. ConclusionRMC exerts blood-activating and anti-inflammatory effects through regulating the target genes of the coagulation-MARK inflammation cascade pathway.

Short-chain fatty acids are potential goalkeepers of atherosclerosis.

Short-chain fatty acids (SCFAs) are metabolites produced by gut bacteria and play a crucial role in various inflammatory diseases. Increasing evidence suggests that SCFAs can improve the occurrence and progression of atherosclerosis. However, the molecular mechanisms through which SCFAs regulate the development of atherosclerosis have not been fully elucidated. This review provides an overview of the research progress on SCFAs regarding their impact on the risk factors and pathogenesis associated with atherosclerosis, with a specific focus on their interactions with the endothelium and immune cells. These interactions encompass the inflammation and oxidative stress of endothelial cells, the migration of monocytes/macrophages, the lipid metabolism of macrophages, the proliferation and migration of smooth muscle cells, and the proliferation and differentiation of Treg cells. Nevertheless, the current body of research is insufficient to comprehensively understand the full spectrum of SCFAs' mechanisms of action. Therefore, further in-depth investigations are imperative to establish a solid theoretical foundation for the development of clinical therapeutics in this context.

Multidimensional progressive single-cell sequencing reveals cell microenvironment composition and cancer heterogeneity in lung cancer.

Despite substantial advances in cancer biology and treatment, the clinical outcomes of patients with lung cancer remain unsatisfactory. The tumor microenvironment (TME) is a potential target. Using single-cell RNA sequencing, we could distinguish eight distinct cell types in the lung cancer microenvironment, demonstrating substantial intratumoral heterogeneity in 19 different lung cancer tumor samples. Through the re-dimensional grouping of cancer-associated fibroblasts (CAFs), myeloid cells, epithelial cells, natural killer (NK) cells, and T cells, the difference in the TME of lung cancer was revealed. We discovered SFTPB, SFN, and KRT8 as possible predictive biomarkers for lung cancer by assessing the gene expression patterns in epithelial cells. Examining cell-to-cell communications showed a robust association between the quantity of matrix CAFs, epithelial cells, and macrophages in the thrombospondin signaling pathway. Additionally, we found that the amyloid precursor protein signaling pathway primarily originated from the matrix, and inflammatory cancer-associated endothelial and fibroblast cells showed a co-expression relationship with myeloid cells and B cells. Through cell-to-cell correlation analysis, we found positive regulation between NK cells, regulatory T cells, GZMB-CD8 T cells, and GZMK-CD8 T cells, which could play a role in developing immune TMEs. These findings support studies on cancer heterogeneity and add to our understanding of lung cancer's cellular microenvironment.

The vitamin-k-cycle-enzyme VKORC1L1, but not its isoenzyme VKORC1, reduces inflammation in coronary endothelial cells

Abstract Introduction Vascular inflammation is a crucial contributor to atherosclerosis, in which oxidative stress, endoplasmic reticulum (ER) stress and transition of endothelial to mesenchymal cells (EndMT) are of critical importance. Vitamin-K-antagonists (VKA) promote vascular dysfunction, while vitamin K intake was proposed to reduce incidence of coronary artery disease. Key enzyme for regeneration of vitamin K is the Vitamin K epoxide reductase complex subunit 1 (VKORC1), which also represents the pharmacological target of VKA. VKOR-like1 (VKORC1L1) is an isoenzyme of VKORC1, which resides at the ER-membrane, exerts antioxidative properties and is involved in vitamin K maintenance. Aim of this study was to investigate the role of VKORC1 and VKORC1L1 in inflammation of human coronary artery endothelial cells (HCAEC). Methods and Results In silico analyses of the proteome of human coronary atherosclerosis revealed increased expression of VKORC1L1, but not of VKORC1. In vitro induction of oxidative stress (H2O2) and ER-Stress (tunicamycin) in HCAEC promoted time- and dose-dependent enhanced expression of VKORC1L1, without altering VKORC1 expression (H2O2: 2.3-fold vs. 0.8-fold after 40 minutes, p=0.04; tunicamycin: 1 μg/ml: 1.43-fold vs. 0.8-fold, p&amp;lt;0.01). Moreover, inducing EndMT by treatment with a differentiation medium (containing TGF-ß2, IL-1ß) resulted in a reduction of VKORC1L1, but not of VKORC1 (Fig.1). To analyze the relevance of the VKOR-enzymes on endothelial cell function, VKORC1 and VKORC1L1 were downregulated by siRNA. VKORC1L1 downregulation increased formation of reactive oxygen species (ROS) (DCFDA signal: 0.98-fold vs. 1.31-fold, p = 0.03) and reduced proliferation (EdU signal: 0.56 ± 0.02 vs. control, p &amp;lt; 0.01), whereas viability of HCAEC remained unchanged. ELISA and qPCR experiments revealed enhanced expression of a variety of markers of vascular inflammation after VKORC1L1 (e.g., IL-6: 3.42-fold ± 0.53, NF-κB: 1.95-fold ± 0.13, VCAM-1: 1.59-fold ± 0.12, vs. control). Additionally, expression of ER-stress markers was increased (e.g., GRP78; 1.32-fold ± 0.04 vs. control, p&amp;lt;0.01) (Fig.1). In contrast, VKORC1 downregulation significantly promoted proliferation (EdU signal: 3.9 ± 1.7 vs. control, p&amp;lt;0.01) as well as viability (alamarBlue® absorbance: 1.07 ± 0.08 vs. control, p=0.04), and decreased ROS (0.88 ± 0.17 vs. control, p=0.03). Pro-inflammatory and ER-stress proteins were either unaltered or decreased after VKORC1 knockdown (e.g., GRP78: 0.89-fold, VCAM-1: 0.68-fold) (Fig.2). To further elucidate these findings, we will perform overexpression experiments and stable knockdown of the VKOR-enzymes. Conclusion VKORC1 and its isoenzyme VKORC1L1 exhibit divergent effects on endothelial cell inflammation. Further studies are warranted to shed light on the regulation of the enzymes to improve our understanding regarding vascular side effects of VKA treatment and beneficial effects of vitamin K supplementation.

The endoplasmic reticulum (ER) chaperone GRP78 is secreted during ER Stress and alleviates endothelial cell inflammation

Abstract Introduction Glucose-Regulated Protein 78kD (GRP78) is a chaperone and the main regulator of the ER-stress response which is triggered by a variety of conditions that disturb folding of proteins in the ER. Upon ER Stress, GRP78 activates the unfolded protein response (UPR), which aims to clear unfolded proteins and restore ER homeostasis. Recently, extracellular secretion of GRP78 was described. However, the pathophysiological relevance of secreted GRP78 in atherosclerosis and endothelial cell inflammation remains to be elucidated. Aim of this study is to investigate the role of GRP78 secretion in endothelial cells. Methods and Results First, we sought to investigate if vascular cells secrete GRP78 during ER Stress. Human coronary artery endothelial cells (HCAEC) were treated with the ER stress inductor tunicamycin for up to 48h. After ER Stress induction, Western Blot and ELISA experiments detected an increased intracellular GRP78 expression. Intriguingly, prolonged ER Stress also promoted extracellular secretion of GRP78. Unbiased proteomic analysis of the HCAEC secretome confirmed that after ER-Stress induction, GRP78 is one of the most highly upregulated extracellular proteins (2.43-fold). Co-incubation with Brefeldin A, an inhibitor of ER-Golgi protein transport, abolished extracellular secretion (Fig.1). Hence, ER-Stress-induced GRP78 secretion is an actively regulated process. Next, the effect of GRP78 containing conditioned medium (CM) on HCAEC was analyzed. For control, HCAEC were co-incubated with BFA, or GRP78-knockdown was performed by siRNA. Treatment with GRP78 containing CM decreased GRP78 mRNA expression in target cells (0.35-fold vs. control [+BFA], p&amp;lt;0.0001). Furthermore, it increased viability ( BFA: 93.0 % vs. 83%, p=0.002; GRP78-siRNA: 94% vs. 85%, p=0.01) and decreased the rate of apoptosis (e.g. BFA: 1.7-fold vs. 5.1, p=0.02). Moreover, expression of markers of vascular inflammation and ER Stress (e.g., NF-κB and CHOP) were decreased when compared to CM without GRP78 (Fig.2). Furthermore, increased H2O2-generation was measured (BFA: 1.4-fold, p&amp;gt;0.001, GRP78-siRNA:1.3-fold, p=0.004) (Fig. 2). To confirm that the beneficial effects of the CM are in fact caused by GRP78, we treated HCAEC with recombinant GRP78 and observed an increased cell viability in a dose-dependent manner (1000 ng/ml: p=0.02 vs. control). CRIPTO is a membrane-bound co-receptor for growth factors and was previously linked to GRP78-signalling. siRNA-Knockdown of CRIPTO reduces viability and leads to cell apoptosis, irrespective of GRP78-treatment. Thus, GRP78-mediated effects may be mediated by CRIPTO. Conclusion Endothelial ER Stress promotes GRP78 secretion. Presence of GRP78 in conditioned medium ameliorates subsequent ER Stress and endothelial inflammation, which play a critical role in atherogenesis. Further investigations are important to shed light on the mechanism of release and the effect on target cells.

Intravenous iron administration in patients with heart failure alters endothelial homeostasis with early release of endothelial microvesicles and subsequent mobilization of endothelial progenitor cell

Abstract Background Intravenous iron supplementation is an established therapy for patients with heart failure (HF) with reduced ejection fraction (LV-EF&amp;lt;50%) and iron deficiency, resulting in reduced risk of HF hospitalization. Since iron may induce oxidative stress, inflammation and apoptosis in endothelial cells, concerns persist regarding potential adverse vascular effects of iron therapy. To evaluate endothelial health following ferric carboxymaltose (FCM) administration, we assessed the profile of circulating endothelial microvesicles (EMVs) and endothelial progenitor cells (EPCs) in a cohort of 23 HF patients using flow cytometry. Results Compared to healthy control subjects (HC; n=15), baseline levels of CD31+/CD41- EMVs were significantly higher and EMVs featured a more apoptotic phenotype in HF patients. Following administration of 1000mg FCM, EMV levels showed an early but transient increase (Fig. 1) and displayed an altered phenotype profile with dominant augmentation of EMVs expressing the inducible markers CD62E and CD54, indicating endothelial activation and injury. Levels of circulating vasoregenerative CD45lowCD34+KDR+ EPCs were lower in HF patients and FCM application resulted in an early decrease of EPCs followed by substantial mobilization into the circulation after one week (Fig. 2). Levels of EMVs and EPCs returned to baseline values within two and four weeks, respectively. Compared to HF patients with preserved renal function, the EMV/EPC ratio was higher in HF patients whereas EPC mobilization was diminished with additional chronic kidney disease, suggesting impaired vascular repair capacity. In vitro experiments with cultured endothelial cells revealed that FCM at therapeutic concentrations dose-dependently promotes endothelial apoptosis, increases expression of adhesion molecules and CXCL12, and triggers the generation of EMVs. Conclusion Intravenous iron supplementation with FCM in HF patients provokes a biphasic response with early release of CD62E+ and CD54+ enriched EMVs and subsequent mobilization of EPCs, suggesting temporary aggravation of endothelial dysfunction upon FCM supplementation and consecutive engagement of a vascular defense program.

Abstract 16881: Endothelial KLF11 is a Novel Endogenous Protectant Against Diabetic Atherosclerosis

Background: Atherosclerosis is the leading cause of cardiovascular diseases, which is also the primary cause of mortality among diabetic patients. Endothelial cell (EC) dysfunction is a critical early step in the development of atherosclerosis and aggravated in the presence of concurrent diabetes. Krüppel like factor 11 (KLF11), a transcription factor involved in diabetes, inhibits EC inflammation via regulation of NF-κB signaling. However, the potential function of KLF11 in pathogenesis of diabetic atherosclerosis remains undefined. Methods and results: Diet-induced type 2 diabetic atherosclerosis model is established in LDLR -/- mice by feeding a diabetogenic high-fat diet with cholesterol (DDC). KLF11 expression was increased in ECs from ascending aorta of LDLR -/- mice fed DDC diet. Moreover, EC specific KLF11 gain- (transgenic) and loss-of-function (knockout) mice in a LDLR -/- background were fed a DDC for 16 weeks. Endothelial KLF11 deficiency (Klf11 ECKO -LDLR -/- ) markedly increased atherogenesis, while EC-selective KLF11 overexpression significantly inhibited DDC-induced atherogenesis. Single cell RNA sequencing profiling the ECs isolated from DDC-fed Klf11 ECKO -LDLR -/- mice and littermate controls showed that KLF11 depletion increased endothelial-to-mesenchymal transition (EndMT) during atherogenesis. In vitro studies showed that KLF11 not only inhibited EC inflammation and oxidative stress, but also diminished EndMT in response to high glucose. Conversely, knockdown of KLF11 augmented the EC dysfunction and EndMT. Conclusions: Our study indicates that endothelial KLF11 protects against diabetic atherosclerosis through inhibition of EC inflammation, oxidative stress and EndMT.

CREB1 Silencing Protects Against Inflammatory Response in Rats with Deep Vein Thrombosis Through Reducing RPL9 Expression and Blocking NF-κB Signaling.

Apoptosis and inflammation of vascular endothelial cells (VECs) are the most important causes of deep vein thrombosis (DVT). cAMP response element binding protein 1 (CREB1) encodes a transcription factor that binds as a homodimer to the cAMP-responsive element and can promote inflammation. CREB1 is found to be upregulated in the plasma of patients with venous thromboembolism. However, the biological functions of CREB1 in DVT remain unknown. We evaluated the effect of CREB1 in a rat model of inferior vena cava (IVA) stenosis-induced DVT. IVC stenosis resulted in stable thrombus, inflammatory response and CREB1 upregulation, whereas CREB1 knockdown inhibited thrombus and inflammation in DVT rats. In vitro analysis showed that CREB1 knockdown inhibited VEC apoptosis. Mechanistically, CREB1 knockdown reduced Ribosomal protein L9 (RPL9) expression and blocked the NF-κB pathway. Therefore, CREB1 may become a potential therapeutic target of DVT prevention.

Visualizing the spatial distribution of inflammation in the depressed brain with a targeted MRI nanoprobe in vivo

Depression is a prevalent mental illness that imposes a substantial public health burden. However, the diverse clinical phenotypes observed in patients make it difficult to realize precise diagnosis. Recently, accumulating preclinical and clinical evidence has suggested that inflammation is involved in the pathophysiology of depression. Herein, a molecular imaging–based strategy was proposed as a means to diagnose depression precisely by specifically visualizing the inflammation status associated with depression. Inflammation-targeting MRI nanoprobes were constructed by attaching an intercellular cell adhesion molecule-1 (ICAM-1)-targeting peptide to biocompatible Fe3O4 nanoparticles. Systematic studies demonstrated that the nanoprobes could specifically target inflamed vascular endothelial cells and visualize the spatial distribution of inflammation in the depressed brain in vivo through susceptibility-weighted imaging (SWI), which was further confirmed by histological analysis. Additionally, these inflammatory brain regions identified by nanoprobe-based imaging are consistent with the focal regions closely associated with the symptoms of depression as reported in previous behavioral studies. Overall, this is the first study to directly visualize the distribution of inflammation in the depressed brain in vivo through a molecular imaging strategy, which may not only facilitate insight into the biological mechanism underlying depression but also provide a potential target within the depressed brain for the further development of anti-inflammatory therapies.

HMGB1 Induced Oxidative Stress and Inflammation in Endothelial Cells Exposed to Impinging Flow

Plain Language SummaryOxidative stress and inflammatory are two important factors that are involved in the formation and development of intracranial aneurysm (IA). Wall shear stress (WSS) produced by impinging flow can induce oxidative stress and inflammatory. However, the specific mechanisms remain unclear. Accumulating evidence has shown that high mobility group box-1 (HMGB1) is associated with oxidative stress-related chronic diseases and inflammatory. We used a modified T-chamber to simulate the in vitro situation of human umbilical vein ECs (HUVECs) subjected to impinging flow at the arterial bifurcation in order to analyze the effect of WSS on HUVECs. The levels of oxidative stress were determined by measuring ROS levels using flow cytometry. The inflammatory was examined using Western blot to measure IL-1β, IL-6, and IL-8 expression levels. Our results demonstrate that WSS can induce oxidative stress and inflammatory in HUVECs. Moreover, we used Western blot to find high expression of HMGB1 in response to impinging flow. We also found by immunofluorescence that HMGB1 undergoes nuclear to cytoplasmic translocation upon exposure to impinging flow. Subsequently, we knocked down HMGB1 using lentiviral transfection of HUVECs and found that the levels of inflammatory and oxidative stress in HUVECs were significantly reduced. This allows us to conclude that HMGB1 is indeed involved in mediating the inflammatory and oxidative stress in HUVECs exposed to WSS. Those findings provide a theoretical basis and a research direction for targeting IA disease through the regulation of oxidative stress and inflammatory response.

A novel circular RNA, circSQSTM1, protects the endothelial function in atherosclerosis

A novel circRNA named circSQSTM1 (hsa_circRNA_075320) was screened out in atorvastatin (ATV) stimulated endothelial cells (ECs) by our group. Considering the anti-atherosclerotic function of ATV, we hypothesized the circSQSTM1 could protect ECs functions in AS progression. The effects of circSQSTM1 on ECs inflammation, oxidative stress and autophagy were measured by qRT-PCR, Western blotting, monocyte-endothelial adhesion assay, dichloro-dihydro-fluorescein diacetate and mCherry-GFP-LC3 labeling. A luciferase reporter assay, RNA immunoprecipitation, MS2-tagging system and fluorescence in situ hybridization were performed to identify the biological functions of circSQSTM1. The partial left carotid artery ligation model and atherosclerosis model were established to analyze the effects of circSQSTM1 on atherosclerosis progression in vivo. Our results revealed that ATV induced the accumulation of circSQSTM1 in ECs via suppressing m6A modified degradation. In the cytoplasm, circSQSTM1 could relieve Sirt1 by competitively sponging miR-23b-3p. In the nucleus, circSQSTM1 directly interacts with eIF4A3 and promoting the efficient nuclear export of FOXO1 mRNA, which encodes FOXO1 transcription factor to directly activate Sirt1 promoter activity. Hence, circSQSTM1 reduced inflammation, inhibited oxidative stress and promoted autophagy by upregulating Sirt1 in ECs. Moreover, circSQSTM1 overexpression in ECs attenuated the progression of atherosclerosis in ApoE−/− mice. Taken together, the unique noncoding RNA known as circSQSTM1 took a protective role to the ECs in atherosclerosis.

Mitochondrial DNA is a key driver in cigarette smoke extract-induced IL-6 expression.

Smoking is an independent risk factor for atherosclerosis, the primary pathogenesis of which is inflammation. We recently reported that cigarette smoke extract (CSE) causes cytosolic and extracellular accumulation of both nuclear (n) and mitochondrial (mt) DNA, which leads to inflammation in human umbilical vein endothelial cells (HUVECs). In this study, we examined whether inflammation induction depends more on cytosolic nDNA or mtDNA, and which chemical constituents of CSE are involved. Acrolein (ACR), methyl vinyl ketone (MVK), and 2-cyclopenten-1-one (CPO) were used in the experiments, as these are the major cytotoxic factors in CSE in various cell types. Stimulation with ACR, MVK, or CPO alone resulted in the accumulation of DNA double-strand breaks (DSBs), but not oxidative DNA damage, accumulation of cytosolic DNA, or increased expression of inflammatory cytokines. Simultaneous administration of all three constituents (ALL) resulted in oxidative DNA damage in both the nucleus and mitochondria, accumulation of DSBs, reduced mitochondrial membrane potential, induction of minority mitochondrial outer membrane permeabilization, accumulation of cytosolic free DNA, and increased expression of inflammatory cytokines such as IL-6 and IL-1α. Treatment with N-acetyl-L-cysteine, a reactive oxygen species scavenger, suppressed oxidative DNA damage and the increased expression of IL-6 and IL-1α induced by ALL or CSE. The ALL- or CSE-induced increase in IL-6 expression, but not that of IL-1α, was suppressed by mtDNA depletion. In conclusion, ACR, MVK, and CPO may strongly contribute to CSE-induced inflammation. More importantly, cytosolic free mtDNA is thought to play an important role in IL-6 expression, a central mediator of inflammation.

Dendritic Cell-Derived Exosomes Stimulated by Treponema pallidum Induce Endothelial Cell Inflammatory Response through the TLR4/MyD88/NF-κB Signaling Pathway.

Exosomes have been implicated in vascular damage in recent research. The influence of dendritic cell-derived exosomes generated by Treponema pallidum (T. pallidum) on the inflammatory process of vascular cells was examined in this study. Human umbilical vein endothelial cells (HUVECs) were cocultured with exosomes isolated from dendritic cells induced by T. pallidum. Western blot and reverse transcription-quantitative real-time polymerase chain reaction were used to assess toll-like receptor 4 (TLR4) expression and the quantity of proinflammatory cytokines. The findings showed that the expression of TLR4 was considerably upregulated, and TLR4 knockdown dramatically reduced interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) production in exosome-treated HUVECs. Furthermore, TLR4 silencing reduced myeloid differentiation primary response protein 88 (MyD88) and nuclear factor kappa light chain enhancer of activated B cells (NF-κB) levels in exosome-treated HUVECs. Additionally, suppression of the activity of NF-κB with BAY11-7082, an NF-κB inhibitor, also reduced the exosome-treated inflammatory response. Our results suggested that dendritic cell-derived exosomes stimulated by T. pallidum induced endothelial cell inflammation, and the TLR4/MyD88/NF-κB signal axis was activated, significantly increasing IL-1β, IL-6, and TNF-α expression. This may have a significant role in the vascular inflammatory response in syphilis, which would contribute to the understanding of the pathogenesis of syphilis and the host immunological response to T. pallidum.