Endothelial Jag1-RBPJ signalling promotes inflammatory leucocyte recruitment and atherosclerosis

Multifaceted Role of Notch Signaling in Vascular Health and Diseases

Notch signaling is evolutionarily conserved from Drosophila to mammals and it functions as an essential modulator of vascular growth and development by directing endothelial cell specification, proliferation, migration, arteriovenous differentiation, inflammation, and apoptosis. The interplay between Notch and other signaling pathways plays a homeostatic role by modulating multiple vascular functions, including permeability regulation, angiogenesis, and vascular remodeling. This review explores current knowledge on Notch signaling in vascular development, homeostasis, and disease. It also discusses recent developments in understanding how endothelial Notch signaling affects vascular inflammation via cytokines or aberrant shear stress in endothelial cells while addressing the reciprocal relationship between Notch signaling and inflammation.

DLL4 promotes partial endothelial-to-mesenchymal transition at atherosclerosis-prone regions of arteries

Flowing blood regulates vascular development, homeostasis and disease by generating wall shear stress which has major effects on endothelial cell (EC) physiology. Low oscillatory shear stress (LOSS) induces a form of cell plasticity called endothelial-to-mesenchymal transition (EndMT). This process has divergent effects; in embryos LOSS-induced EndMT drives the development of atrioventricular valves, whereas in adult arteries it is associated with inflammation and atherosclerosis. The Notch ligand DLL4 is essential for LOSS-dependent valve development; here we investigated whether DLL4 is required for responses to LOSS in adult arteries. Analysis of cultured human coronary artery EC revealed that DLL4 regulates the transcriptome to induce markers of EndMT and inflammation under LOSS conditions. Consistently, genetic deletion of Dll4 from murine EC reduced SNAIL (EndMT marker) and VCAM-1 (inflammation marker) at a LOSS region of the murine aorta. We hypothesized that endothelial Dll4 is pro-atherogenic but this analysis was confounded because endothelial Dll4 negatively regulated plasma cholesterol levels in hyperlipidemic mice. We conclude that endothelial DLL4 is required for LOSS-induction of EndMT and inflammation regulators at atheroprone regions of arteries, and is also a regulator of plasma cholesterol.

The transcription factor CSL homolog in Penaeus vannamei positively regulates the transcription of the hemocyanin small subunit gene

Hemocyanin, a copper-containing respiratory protein, is abundantly present in hemolymph of arthropods and mollusks and performs a variety of immunological functions. However, the regulatory mechanisms of hemocyanin gene transcription remain largely unclear. Our previous work showed that knockdown of the transcription factor CSL, a component of the Notch signaling pathway, downregulated the expression of Penaeus vannamei hemocyanin small subunit gene (PvHMCs), indicating the involvement of CSL in regulating the PvHMCs transcription. In this study, we identified a CSL binding motif ("GAATCCCAGA", +1675/+1684 bp) in the core promoter of PvHMCs (designated as HsP3). Dual luciferase reporter assay and electrophoretic mobility shift assay (EMSA) demonstrated that the CSL homolog in P. vannamei (PvCSL) could directly bind and activate the HsP3 promoter. Moreover, in vivo silencing of PvCSL significantly attenuated the mRNA and protein expression of PvHMCs. Finally, in response to Vibrio parahaemolyticus, Streptococcus iniae and white spot syndrome virus (WSSV) challenge, the transcript of PvCSL and PvHMCs showed a positive correlation, suggesting that PvCSL could also modulate the expression of PvHMCs upon pathogen stimulation. Taken together, our present finding is the first to demonstrate that PvCSL is a crucial factor in transcriptional control of PvHMCs.

Notch Signaling in the Vasculature: Angiogenesis and Angiocrine Functions

Formation of a functional blood vessel network is a complex process tightly controlled by pro- and antiangiogenic signals released within the local microenvironment or delivered through the bloodstream. Endothelial cells precisely integrate such temporal and spatial changes in extracellular signals and generate an orchestrated response by modulating signaling transduction, gene expression, and metabolism. A key regulator in vessel formation is Notch signaling, which controls endothelial cell specification, proliferation, migration, adhesion, and arteriovenous differentiation. This review summarizes the molecular biology of endothelial Notch signaling and how it controls angiogenesis and maintenance of the established, quiescent vasculature. In addition, recent progress in the understanding of Notch signaling in endothelial cells for controlling organ homeostasis by transcriptional regulation of angiocrine factors and its relevance to disease will be discussed.

Somatostatin Receptor PET/MR Imaging of Inflammation in Patients With Large Vessel Vasculitis and Atherosclerosis

BACKGROUND

Assessing inflammatory disease activity in large vessel vasculitis (LVV) can be challenging by conventional measures.

OBJECTIVES

We aimed to investigate somatostatin receptor 2 (SST2) as a novel inflammation-specific molecular imaging target in LVV.

METHODS

In a prospective, observational cohort study, in vivo arterial SST2 expression was assessed by positron emission tomography/magnetic resonance imaging (PET/MRI) using 68Ga-DOTATATE and 18F-FET-βAG-TOCA. Ex vivo mapping of the imaging target was performed using immunofluorescence microscopy; imaging mass cytometry; and bulk, single-cell, and single-nucleus RNA sequencing.

RESULTS

Sixty-one participants (LVV: n = 27; recent atherosclerotic myocardial infarction of ≤2 weeks: n = 25; control subjects with an oncologic indication for imaging: n = 9) were included. Index vessel SST2 maximum tissue-to-blood ratio was 61.8% (P < 0.0001) higher in active/grumbling LVV than inactive LVV and 34.6% (P = 0.0002) higher than myocardial infarction, with good diagnostic accuracy (area under the curve: ≥0.86; P < 0.001 for both). Arterial SST2 signal was not elevated in any of the control subjects. SST2 PET/MRI was generally consistent with 18F-fluorodeoxyglucose PET/computed tomography imaging in LVV patients with contemporaneous clinical scans but with very low background signal in the brain and heart, allowing for unimpeded assessment of nearby coronary, myocardial, and intracranial artery involvement. Clinically effective treatment for LVV was associated with a 0.49 ± 0.24 (standard error of the mean [SEM]) (P = 0.04; 22.3%) reduction in the SST2 maximum tissue-to-blood ratio after 9.3 ± 3.2 months. SST2 expression was localized to macrophages, pericytes, and perivascular adipocytes in vasculitis specimens, with specific receptor binding confirmed by autoradiography. SSTR2-expressing macrophages coexpressed proinflammatory markers.

CONCLUSIONS

SST2 PET/MRI holds major promise for diagnosis and therapeutic monitoring in LVV. (PET Imaging of Giant Cell and Takayasu Arteritis [PITA], NCT04071691; Residual Inflammation and Plaque Progression Long-Term Evaluation [RIPPLE], NCT04073810).

Inhibition of the intracellular domain of Notch1 results in vascular endothelial cell dysfunction in sepsis

Background

Notch signaling is critical for regulating the function of vascular endothelial cells (ECs). However, the effect of the intracellular domain of Notch1 (NICD) on EC injury in sepsis remains unclear.

Methods

We established a cell model of vascular endothelial dysfunction and induced sepsis in a mouse model via lipopolysaccharide (LPS) injection and cecal ligation and puncture (CLP). Endothelial barrier function and expression of endothelial-related proteins were determined using CCK-8, permeability, flow cytometry, immunoblot, and immunoprecipitation assays. The effect of NICD inhibition or activation on endothelial barrier function was evaluated in vitro. Melatonin was used for NICD activation in sepsis mice. The survival rate, Evans blue dye of organs, vessel relaxation assay, immunohistochemistry, ELISA, immunoblot were used to explore the specific role of melatonin for sepsis induced vascular dysfunction in vivo.

Results

We found that LPS, interleukin 6, and serum collected from septic children could inhibit the expression of NICD and its downstream regulator Hes1, which impaired endothelial barrier function and led to EC apoptosis through the AKT pathway. Mechanistically, LPS decreased the stability of NICD by inhibiting the expression of a deubiquitylating enzyme, ubiquitin-specific proteases 8 (USP8). Melatonin, however, upregulated USP8 expression, thus maintaining the stability of NICD and Notch signaling, which ultimately reduced EC injury in our sepsis model and elevated the survival rate of septic mice.

Conclusions

We found a previously uncharacterized role of Notch1 in mediating vascular permeability during sepsis, and we showed that inhibition of NICD resulted in vascular EC dysfunction in sepsis, which was reversed by melatonin. Thus, the Notch1 signaling pathway is a potential target for the treatment of sepsis.

Endothelial RBPJ Is Essential for the Education of Tumor-Associated Macrophages

Epithelial ovarian cancer (EOC) is one of the most lethal gynecologic cancers worldwide. EOC cells educate tumor-associated macrophages (TAM) through CD44-mediated cholesterol depletion to generate an immunosuppressive tumor microenvironment (TME). In addition, tumor cells frequently activate Notch1 receptors on endothelial cells (EC) to facilitate metastasis. However, further work is required to establish whether the endothelium also influences the education of recruited monocytes. Here, we report that canonical Notch signaling through RBPJ in ECs is an important player in the education of TAMs and EOC progression. Deletion of Rbpj in the endothelium of adult mice reduced infiltration of monocyte-derived macrophages into the TME of EOC and prevented the acquisition of a typical TAM gene signature; this was associated with stronger cytotoxic activity of T cells and decreased tumor burden. Mechanistically, CXCL2 was identified as a novel Notch/RBPJ target gene that regulated the expression of CD44 on monocytes and subsequent cholesterol depletion of TAMs. Bioinformatic analysis of ovarian cancer patient data showed that increased CXCL2 expression is accompanied by higher expression of CD44 and TAM education. Together, these findings indicate that EOC cells induce the tumor endothelium to secrete CXCL2 to establish an immunosuppressive microenvironment.

SIGNIFICANCE

Endothelial Notch signaling favors immunosuppression by increasing CXCL2 secretion to stimulate CD44 expression in macrophages, facilitating their education by tumor cells.

Gene expression patterns associated with caudal fin shape in the cichlid Lamprologus tigripictilis

Variation in fin shape is one of the most prominent features of morphological diversity among fish. Regulation of fin growth has mainly been studied in zebrafish, and it is not clear whether the molecular mechanisms underlying shape variation are equally diverse or rather conserved across species. In the present study, expression levels of 37 candidate genes were tested for association with fin shape in the cichlid fish Lamprologus tigripictilis. The tested genes included members of a fin shape-associated gene regulatory network identified in a previous study and novel candidates selected within this study. Using both intact and regenerating fin tissue, we tested for expression differences between the elongated and the short regions of the spade-shaped caudal fin and identified 20 genes and transcription factors (including angptl5, cd63, csrp1a, cx43, esco2, gbf1, and rbpj), whose expression patterns were consistent with a role in fin growth. Collated with available gene expression data of two other cichlid species, our study not only highlights several genes that were correlated with fin growth in all three species (e.g., angptl5, cd63, cx43, and mmp9), but also reveals species-specific gene expression and correlation patterns, which indicate considerable divergence in the regulatory mechanisms of fin growth across cichlids.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10750-022-05068-4.

JAG1-NOTCH4 mechanosensing drives atherosclerosis

Endothelial cell (EC) sensing of disturbed blood flow triggers atherosclerosis, a disease of arteries that causes heart attack and stroke, through poorly defined mechanisms. The Notch pathway plays a central role in blood vessel growth and homeostasis, but its potential role in sensing of disturbed flow has not been previously studied. Here, we show using porcine and murine arteries and cultured human coronary artery EC that disturbed flow activates the JAG1-NOTCH4 signaling pathway. Light-sheet imaging revealed enrichment of JAG1 and NOTCH4 in EC of atherosclerotic plaques, and EC-specific genetic deletion of Jag1 (Jag1ECKO) demonstrated that Jag1 promotes atherosclerosis at sites of disturbed flow. Mechanistically, single-cell RNA sequencing in Jag1ECKO mice demonstrated that Jag1 suppresses subsets of ECs that proliferate and migrate. We conclude that JAG1-NOTCH4 sensing of disturbed flow enhances atherosclerosis susceptibility by regulating EC heterogeneity and that therapeutic targeting of this pathway may treat atherosclerosis.

Inflammation and atherosclerosis: signaling pathways and therapeutic intervention

Atherosclerosis is a chronic inflammatory vascular disease driven by traditional and nontraditional risk factors. Genome-wide association combined with clonal lineage tracing and clinical trials have demonstrated that innate and adaptive immune responses can promote or quell atherosclerosis. Several signaling pathways, that are associated with the inflammatory response, have been implicated within atherosclerosis such as NLRP3 inflammasome, toll-like receptors, proprotein convertase subtilisin/kexin type 9, Notch and Wnt signaling pathways, which are of importance for atherosclerosis development and regression. Targeting inflammatory pathways, especially the NLRP3 inflammasome pathway and its regulated inflammatory cytokine interleukin-1β, could represent an attractive new route for the treatment of atherosclerotic diseases. Herein, we summarize the knowledge on cellular participants and key inflammatory signaling pathways in atherosclerosis, and discuss the preclinical studies targeting these key pathways for atherosclerosis, the clinical trials that are going to target some of these processes, and the effects of quelling inflammation and atherosclerosis in the clinic.

Exploring the Relationship of Perivascular Adipose Tissue Inflammation and the Development of Vascular Pathologies

Initially thought to only provide mechanical support for the underlying blood vessels, perivascular adipose tissue (PVAT) has now emerged as a regulator of vascular function. A healthy PVAT exerts anticontractile and anti-inflammatory actions on the underlying vasculature via the release of adipocytokines such as adiponectin, nitric oxide, and omentin. However, dysfunctional PVAT produces more proinflammatory adipocytokines such as leptin, resistin, interleukin- (IL-) 6, IL-1β, and tumor necrosis factor-alpha, thus inducing an inflammatory response that contributes to the pathogenesis of vascular diseases. In this review, current knowledge on the role of PVAT inflammation in the development of vascular pathologies such as atherosclerosis and hypertension was discussed.

EGF repeats of epidermal growth factor‑like domain 7 promote endothelial cell activation and tumor escape from the immune system

The tumor blood vessel endothelium forms a barrier that must be crossed by circulating immune cells in order for them to reach and kill cancer cells. Epidermal growth factor‑like domain 7 (Egfl7) represses this immune infiltration by lowering the expression levels of leukocyte adhesion receptors on the surface of endothelial cells. However, the protein domains involved in these properties are not completely understood. Egfl7 is structurally composed of the predicted EMI‑, EGF‑ and C‑terminal domains. The present study aimed to investigate the roles of these different domains in tumor development by designing retroviruses coding for deletion mutants and then infecting 4T1 breast cancer cell populations, which consequently overexpressed the variants. By performing in vitro soft‑agar assays, it was found that Egfl7 and its deletion variants did not affect cell proliferation or anchorage‑independent growth. When 4T1 cells expressing either the wild‑type Egfl7 protein or Egfl7 domain variants were implanted in mice, Egfl7 expression markedly promoted tumor development and deletion of the EGF repeats decreased the tumor growth rate. By contrast, deleting any other domain displayed no significant effect on tumor development. The overexpression of Egfl7 also decreased T cell and natural killer cell infiltration in tumors, as determined by immunofluorescence staining of tumor sections, whereas deletion of the EGF repeats inhibited this effect. Reverse transcription‑quantitative PCR analysis of the mechanisms involved revealed that deleting the EGF repeats partially restored the expression levels of vascular cell adhesion molecule 1 and E‑selectin, which were suppressed by overexpression of Egfl7 in endothelial cells in vitro. This resulted in a higher number of lymphocytes bound to HUVEC expressing Egfl7‑ΔEGF compared with HUVEC expressing wild‑type Egfl7, as assessed by fluorescent‑THP‑1 adhesion assays onto endothelial cells. Overall, the present study demonstrated that the EGF repeats may participate in the protumoral and anti‑inflammatory effects of Egfl7.

An update on the roles of immune system-derived microRNAs in cardiovascular diseases

Cardiovascular diseases (CVD) are a leading cause of human death worldwide. Over the past two decades, the emerging field of cardioimmunology has demonstrated how cells of the immune system play vital roles in the pathogenesis of CVD. MicroRNAs (miRNAs) are critical regulators of cellular identity and function. Cell-intrinsic, as well as cell-extrinsic, roles of immune and inflammatory cell-derived miRNAs have been, and continue to be, extensively studied. Several 'immuno-miRNAs' appear to be specifically expressed or demonstrate greatly enriched expression within leucocytes. Identification of miRNAs as critical regulators of immune system signalling pathways has posed the question of whether and how targeting these molecules therapeutically, may afford opportunities for disease treatment and/or management. As the field of cardioimmunology rapidly continues to advance, this review discusses findings from recent human and murine studies which contribute to our understanding of how leucocytes of innate and adaptive immunity are regulated-and may also regulate other cell types, via the actions of the miRNAs they express, in the context of CVD. Finally, we focus on available information regarding miRNA regulation of regulatory T cells and argue that targeted manipulation of miRNA regulated pathways in these cells may hold therapeutic promise for the treatment of CVD and associated risk factors.

Dynamic alterations of H3K4me3 and H3K27me3 at ADAM17 and Jagged-1 gene promoters cause an inflammatory switch of endothelial cells

Histone protein modifications control the inflammatory state of many immune cells. However, how dynamic alteration in histone methylation causes endothelial inflammation and apoptosis is not clearly understood. To examine this, we explored two contrasting histone methylations; an activating histone H3 lysine 4 trimethylation (H3K4me3) and a repressive histone H3 lysine 27 trimethylation (H3K27me3) in endothelial cells (EC) undergoing inflammation. Through computer-aided reconstruction and 3D printing of the human coronary artery, we developed a unique model where EC were exposed to a pattern of oscillatory/disturbed flow as similar to in vivo conditions. Upon induction of endothelial inflammation, we detected a significant rise in H3K4me3 caused by an increase in the expression of SET1/COMPASS family of H3K4 methyltransferases, including MLL1, MLL2, and SET1B. In contrast, EC undergoing inflammation exhibited truncated H3K27me3 level engendered by EZH2 cytosolic translocation through threonine 367 phosphorylation and an increase in the expression of histone demethylating enzyme JMJD3 and UTX. Additionally, many SET1/COMPASS family of proteins, including MLL1 (C), MLL2, and WDR5, were associated with either UTX or JMJD3 or both and such association was elevated in EC upon exposure to inflammatory stimuli. Dynamic enrichment of H3K4me3 and loss of H3K27me3 at Notch-associated gene promoters caused ADAM17 and Jagged-1 derepression and abrupt Notch activation. Conversely, either reducing H3K4me3 or increasing H3K27me3 in EC undergoing inflammation attenuated Notch activation, endothelial inflammation, and apoptosis. Together, these findings indicate that dynamic chromatin modifications may cause an inflammatory and apoptotic switch of EC and that epigenetic reprogramming can potentially improve outcomes in endothelial inflammation-associated cardiovascular diseases.

Fibrous Caps in Atherosclerosis Form by Notch-Dependent Mechanisms Common to Arterial Media Development

Objective

Atheromatous fibrous caps are produced by smooth muscle cells (SMCs) that are recruited to the subendothelial space. We tested whether the recruitment mechanisms are the same as in embryonic artery development, which relies prominently on Notch signaling to form the subendothelial medial SMC layers.

Approach and Results

Notch elements were expressed in regions of fibrous cap in human and mouse plaques. To assess the causal role of Notch signaling in cap formation, we studied atherosclerosis in mice where the Notch pathway was inactivated in SMCs by conditional knockout of the essential effector transcription factor RBPJ (recombination signal-binding protein for immunoglobulin kappa J region). The recruitment of cap SMCs was significantly reduced without major effects on plaque size. Lineage tracing revealed the accumulation of SMC-derived plaque cells in the cap region was unaltered but that Notch-defective cells failed to re-acquire the SMC phenotype in the cap. Conversely, to analyze whether the loss of Notch signaling is required for SMC-derived cells to accumulate in atherogenesis, we studied atherosclerosis in mice with constitutive activation of Notch signaling in SMCs achieved by conditional expression of the Notch intracellular domain. Forced Notch signaling inhibited the ability of medial SMCs to contribute to plaque cells, including both cap SMCs and osteochondrogenic cells, and significantly reduced atherosclerosis development.

Conclusions

Sequential loss and gain of Notch signaling is needed to build the cap SMC population. The shared mechanisms with embryonic arterial media assembly suggest that the cap forms as a neo-media that restores the connection between endothelium and subendothelial SMCs, transiently disrupted in early atherogenesis.

Adding a "Notch" to Cardiovascular Disease Therapeutics: A MicroRNA-Based Approach

Dysregulation of the Notch pathway is implicated in the pathophysiology of cardiovascular diseases (CVDs), but, as of today, therapies based on the re-establishing the physiological levels of Notch in the heart and vessels are not available. A possible reason is the context-dependent role of Notch in the cardiovascular system, which would require a finely tuned, cell-specific approach. MicroRNAs (miRNAs) are short functional endogenous, non-coding RNA sequences able to regulate gene expression at post-transcriptional levels influencing most, if not all, biological processes. Dysregulation of miRNAs expression is implicated in the molecular mechanisms underlying many CVDs. Notch is regulated and regulates a large number of miRNAs expressed in the cardiovascular system and, thus, targeting these miRNAs could represent an avenue to be explored to target Notch for CVDs. In this Review, we provide an overview of both established and potential, based on evidence in other pathologies, crosstalks between miRNAs and Notch in cellular processes underlying atherosclerosis, myocardial ischemia, heart failure, calcification of aortic valve, and arrhythmias. We also discuss the potential advantages, as well as the challenges, of using miRNAs for a Notch-based approach for the diagnosis and treatment of the most common CVDs.

Cellular Crosstalk between Endothelial and Smooth Muscle Cells in Vascular Wall Remodeling

Pathological vascular wall remodeling refers to the structural and functional changes of the vessel wall that occur in response to injury that eventually leads to cardiovascular disease (CVD). Vessel wall are composed of two major primary cells types, endothelial cells (EC) and vascular smooth muscle cells (VSMCs). The physiological communications between these two cell types (EC–VSMCs) are crucial in the development of the vasculature and in the homeostasis of mature vessels. Moreover, aberrant EC–VSMCs communication has been associated to the promotor of various disease states including vascular wall remodeling. Paracrine regulations by bioactive molecules, communication via direct contact (junctions) or information transfer via extracellular vesicles or extracellular matrix are main crosstalk mechanisms. Identification of the nature of this EC–VSMCs crosstalk may offer strategies to develop new insights for prevention and treatment of disease that curse with vascular remodeling. Here, we will review the molecular mechanisms underlying the interplay between EC and VSMCs. Additionally, we highlight the potential applicable methodologies of the co-culture systems to identify cellular and molecular mechanisms involved in pathological vascular wall remodeling, opening questions about the future research directions.

Role of Notch in endothelial biology

The Notch signalling pathway is one of the main regulators of endothelial biology. In the last 20 years the critical function of Notch has been uncovered in the context of angiogenesis, participating in tip-stalk specification, arterial-venous differentiation, vessel stabilization, and maturation processes. Importantly, pharmacological compounds targeting distinct members of the Notch signalling pathway have been used in the clinics for cancer therapy. However, the underlying mechanisms that support the variety of outcomes triggered by Notch in apparently opposite contexts such as angiogenesis and vascular homeostasis remain unknown. In recent years, advances in -omics technologies together with mosaic analysis and high molecular, cellular and temporal resolution studies have allowed a better understanding of the mechanisms driven by the Notch signalling pathway in different endothelial contexts. In this review we will focus on the main findings that revisit the role of Notch signalling in vascular biology. We will also discuss potential future directions and technologies that will shed light on the puzzling role of Notch during endothelial growth and homeostasis. Addressing these open questions may allow the improvement and development of therapeutic strategies based on modulation of the Notch signalling pathway.

Overexpressed miR-335-5p reduces atherosclerotic vulnerable plaque formation in acute coronary syndrome

BACKGROUND

Acute coronary syndrome (ACS) may induce cardiovascular death. The correlation of mast cells related microRNAs (miRs) with risk of ACS has been investigated. We explored regulatory mechanism of miR-335-5p on macrophage innate immune response, atherosclerotic vulnerable plaque formation, and revascularization in ACS in relation to Notch signaling.

METHODS

ACS-related gene microarray was collected from Gene Expression Omnibus database. After different agomir or antagomir, or inhibitor of Notch signaling treatment, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, and VCAM-1 levels were tested in ACS mice. Additionally, Notch signaling-related genes and matrix metalloproteinases (MMPs) were measured after miR-335-5p interference. Finally, mouse atherosclerosis, lipid accumulation, and the collagen/vessel area ratio of plaque were determined.

RESULTS

miR-335-5p targeted JAG1 and mediated Notch signaling in ACS. miR-335-5p up-regulation and Notch signaling inhibition reduced expression of JAG1, Notch pathway-related genes, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, VCAM-1, and MMPs, but promote TIMP1 and TIMP2 expression. Additionally, vulnerable plaques were decreased and collagen fiber contents were observed to increase after miR-335-5p overexpression and Notch signaling inhibition.

CONCLUSIONS

Overexpression of miR-335-5p inhibited innate immune response of macrophage, reduced atherosclerotic vulnerable plaque formation, and promoted revascularization in ACS mice targeting JAG1 through Notch signaling.

Overexpressed miR-335-5p reduces atherosclerotic vulnerable plaque formation in acute coronary syndrome

BACKGROUND

Acute coronary syndrome (ACS) may induce cardiovascular death. The correlation of mast cells related microRNAs (miRs) with risk of ACS has been investigated. We explored regulatory mechanism of miR-335-5p on macrophage innate immune response, atherosclerotic vulnerable plaque formation, and revascularization in ACS in relation to Notch signaling.

METHODS

ACS-related gene microarray was collected from Gene Expression Omnibus database. After different agomir or antagomir, or inhibitor of Notch signaling treatment, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, and VCAM-1 levels were tested in ACS mice. Additionally, Notch signaling-related genes and matrix metalloproteinases (MMPs) were measured after miR-335-5p interference. Finally, mouse atherosclerosis, lipid accumulation, and the collagen/vessel area ratio of plaque were determined.

RESULTS

miR-335-5p targeted JAG1 and mediated Notch signaling in ACS. miR-335-5p up-regulation and Notch signaling inhibition reduced expression of JAG1, Notch pathway-related genes, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, VCAM-1, and MMPs, but promote TIMP1 and TIMP2 expression. Additionally, vulnerable plaques were decreased and collagen fiber contents were observed to increase after miR-335-5p overexpression and Notch signaling inhibition.

CONCLUSIONS

Overexpression of miR-335-5p inhibited innate immune response of macrophage, reduced atherosclerotic vulnerable plaque formation, and promoted revascularization in ACS mice targeting JAG1 through Notch signaling.

Vascular Notch Signaling in Stress Hematopoiesis

Canonical Notch signaling is one of the most conserved signaling cascades. It regulates cell proliferation, cell differentiation, and cell fate maintenance in a variety of biological systems during development and cancer (Fortini, 2009; Kopan and Ilagan, 2009; Andersson et al., 2011; Ntziachristos et al., 2014). For the hematopoietic system, during embryonic development, Notch1 is essential for the emergence of hematopoietic stem cells (HSCs) at the aorta-gornado-mesonephro regions of the dorsal aorta. At adult stage, Notch receptors and Notch targets are expressed at different levels in diverse hematopoietic cell types and influence lineage choices. For example, Notch specifies T cell lineage over B cells. However, there has been a long-lasting debate on whether Notch signaling is required for the maintenance of adult HSCs, utilizing transgenic animals inactivating different components of the Notch signaling pathway in HSCs or niche cells. The aims of the current mini-review are to summarize the evidence that disapproves or supports such hypothesis and point at imperative questions waiting to be addressed; hence, some of the seemingly contradictory findings could be reconciled. We need to better delineate the Notch signaling events using biochemical assays to identify direct Notch targets within HSCs or niche cells in specific biological context. More importantly, we call for more elaborate studies that pertain to whether niche cell type (vascular endothelial cells or other stromal cell)-specific Notch ligands regulate the differentiation of T cells in solid tumors during the progression of T-lymphoblastic lymphoma (T-ALL) or chronic myelomonocytic leukemia (CMML). We believe that the investigation of vascular endothelial cells' or other stromal cell types' interaction with hematopoietic cells during homeostasis and stress can offer insights toward specific and effective Notch-related therapeutics.

Methotrexate attenuates vascular inflammation through an adenosine-microRNA-dependent pathway

Endothelial cell (EC) activation is an early hallmark in the pathogenesis of chronic vascular diseases. MicroRNA-181b (Mir181b) is an important anti-inflammatory mediator in the vascular endothelium affecting endotoxemia, atherosclerosis, and insulin resistance. Herein, we identify that the drug methotrexate (MTX) and its downstream metabolite adenosine exert anti-inflammatory effects in the vascular endothelium by targeting and activating Mir181b expression. Both systemic and endothelial-specific Mir181a2b2-deficient mice develop vascular inflammation, white adipose tissue (WAT) inflammation, and insulin resistance in a diet-induced obesity model. Moreover, MTX attenuated diet-induced WAT inflammation, insulin resistance, and EC activation in a Mir181a2b2-dependent manner. Mechanistically, MTX attenuated cytokine-induced EC activation through a unique adenosine-adenosine receptor A3-SMAD3/4-Mir181b signaling cascade. These findings establish an essential role of endothelial Mir181b in controlling vascular inflammation and that restoring Mir181b in ECs by high-dose MTX or adenosine signaling may provide a potential therapeutic opportunity for anti-inflammatory therapy.

Integrating systematic biological and proteomics strategies to explore the pharmacological mechanism of danshen yin modified on atherosclerosis

This research utilized the systematic biological and proteomics strategies to explore the regulatory mechanism of Danshen Yin Modified (DSYM) on atherosclerosis (AS) biological network. The traditional Chinese medicine database and HPLC was used to find the active compounds of DSYM, Pharmmapper database was used to predict potential targets, and OMIM database and GeneCards database were used to collect AS targets. String database was utilized to obtain the other protein of proteomics proteins and the protein-protein interaction (PPI) data of DSYM targets, AS genes, proteomics proteins and other proteins. The Cytoscape 3.7.1 software was utilized to construct and analyse the network. The DAVID database is used to discover the biological processes and signalling pathways that these proteins aggregate. Finally, animal experiments and proteomics analysis were used to further verify the prediction results. The results showed that 140 active compounds, 405 DSYM targets and 590 AS genes were obtained, and 51 differentially expressed proteins were identified in the DSYM-treated ApoE-/- mouse AS model. A total of 4 major networks and a number of their derivative networks were constructed and analysed. The prediction results showed that DSYM can regulate AS-related biological processes and signalling pathways. Animal experiments have also shown that DSYM has a therapeutic effect on ApoE-/-mouse AS model (P < .05). Therefore, this study proposed a new method based on systems biology, proteomics, and experimental pharmacology, and analysed the pharmacological mechanism of DSYM. DSYM may achieve therapeutic effects by regulating AS-related signalling pathways and biological processes found in this research.

Decreased Jagged1 expression in vascular smooth muscle cells delays endothelial regeneration in arteriovenous graft

AIMS

It is well-established that endothelial dysfunction promotes activation of vascular smooth muscle cell (VSMC). Whether decreased accumulation of VSMCs affects endothelial regeneration and functions in arteriovenous graft (AVG) remodelling has not been studied. We sought to identify mechanisms by which the Notch ligand, Jagged1, in VSMCs regulates endothelial cell (EC) functions in AVGs.

METHODS AND RESULTS

AVGs were created in transgenic mice bearing VSMC-specific knockout (KO) or overexpression of Jagged1. VSMC migration, EC regeneration, and its barrier functions as well as AVG remodelling were evaluated. Jagged1 expression was induced in VSMCs of neointima in the AVGs. Jagged1 KO in VSMCs inhibited the accumulation of extracellular matrix as well as VSMC migration. Fewer α-SMA-positive VSMCs were found in AVGs created in VSMC-specific Jagged1 KO mice (VSMCJagged1 KO mice) vs. in WT mice. Decreased VSMCs in AVGs were associated with deterioration of EC functions. In AVGs created in transgenic mice bearing Jagged1 KO in VSMCs exhibited delayed EC regeneration and impaired EC barrier function. Barrier dysfunction of ECs increased inflammatory cell infiltration and dysregulation of AVG remodelling and arterialization. The increased expression of IL-1β in macrophages was associated with expression of adhesion markers in ECs in AVGs created in VSMCJagged1 KO mice. In contrast, AVGs created in mice with overexpression of Jagged1 in VSMCs exhibited improved EC regeneration plus decreased macrophage infiltration. This led to AVG remodelling and arterialization. In co-cultures of ECs and VSMCs, Jagged1 deficiency in VSMCs suppressed N-cadherin and integrin β3 expression in ECs. Inhibition of integrin β3 activation delayed EC spreading and migration. Notably, Jagged1 overexpression in VSMCs or treatment with recombinant Jagged1 stimulated the expression of N-cadherin and integrin β3 in ECs. Jagged1-induced responses were blocked by inhibition of Notch signalling.

CONCLUSIONS

Jagged1 expression in VSMCs maintains EC barrier functions and blocks infiltration of macrophages. These responses promote remodelling and arterialization of AVGs.

NOTCH3 signaling is essential for NF-κB activation in TLR-activated macrophages

Macrophage activation by Toll receptors is an essential event in the development of the response against pathogens. NOTCH signaling pathway is involved in the control of macrophage activation and the inflammatory processes. In this work, we have characterized NOTCH signaling in macrophages activated by Toll-like receptor (TLR) triggering and determined that DLL1 and DLL4 are the main ligands responsible for NOTCH signaling. We have identified ADAM10 as the main protease implicated in NOTCH processing and activation. We have also observed that furin, which processes NOTCH receptors, is induced by TLR signaling in a NOTCH-dependent manner. NOTCH3 is the only NOTCH receptor expressed in resting macrophages. Its expression increased rapidly in the first hours after TLR4 activation, followed by a gradual decrease, which was coincident with an elevation of the expression of the other NOTCH receptors. All NOTCH1, 2 and 3 contribute to the increased NOTCH signaling detected in activated macrophages. We also observed a crosstalk between NOTCH3 and NOTCH1 during macrophage activation. Finally, our results highlight the relevance of NOTCH3 in the activation of NF-κB, increasing p65 phosphorylation by p38 MAP kinase. Our data identify, for the first time, NOTCH3 as a relevant player in the control of inflammation.

Molecular Regulation of Notch Signaling by Gremlin

Gremlin is a member of the TGF-β superfamily that can act as a BMP antagonist, and recently, has been described as a ligand of the vascular endothelial growth factor receptor 2 (VEGFR2). Gremlin shares properties with the Notch signaling pathway. Both participate in embryonic development and are reactivated in pathological conditions. Gremlin is emerging as a potential therapeutic target and biomarker of renal diseases. Here we review the role of the Gremlin-VEGFR2 axis in renal damage and downstream signaling mechanisms, such as Notch pathway.

The Microbiota Promotes Arterial Thrombosis in Low-Density Lipoprotein Receptor-Deficient Mice

Atherosclerotic plaque development depends on chronic inflammation of the arterial wall. A dysbiotic gut microbiota can cause low-grade inflammation, and microbiota composition was linked to cardiovascular disease risk. However, the role of this environmental factor in atherothrombosis remains undefined. To analyze the impact of gut microbiota on atherothrombosis, we rederived low-density lipoprotein receptor-deficient (Ldlr^-/- ) mice as germfree (GF) and kept these mice for 16 weeks on an atherogenic high-fat Western diet (HFD) under GF isolator conditions and under conventionally raised specific-pathogen-free conditions (CONV-R). In spite of reduced diversity of the cecal gut microbiome, caused by atherogenic HFD, GF Ldlr^-/- mice and CONV-R Ldlr^-/- mice exhibited atherosclerotic lesions of comparable sizes in the common carotid artery. In contrast to HFD-fed mice, showing no difference in total cholesterol levels, CONV-R Ldlr^-/- mice fed control diet (CD) had significantly reduced total plasma cholesterol, very-low-density lipoprotein (VLDL), and LDL levels compared with GF Ldlr^-/- mice. Myeloid cell counts in blood as well as leukocyte adhesion to the vessel wall at the common carotid artery of GF Ldlr^-/- mice on HFD were diminished compared to CONV-R Ldlr^-/- controls. Plasma cytokine profiling revealed reduced levels of the proinflammatory chemokines CCL7 and CXCL1 in GF Ldlr^-/- mice, whereas the T-cell-related interleukin 9 (IL-9) and IL-27 were elevated. In the atherothrombosis model of ultrasound-induced rupture of the common carotid artery plaque, thrombus area was significantly reduced in GF Ldlr^-/- mice relative to CONV-R Ldlr^-/- mice. Ex vivo, this atherothrombotic phenotype was explained by decreased adhesion-dependent platelet activation and thrombus growth of HFD-fed GF Ldlr^-/- mice on type III collagen.IMPORTANCE Our results demonstrate a functional role for the commensal microbiota in atherothrombosis. In a ferric chloride injury model of the carotid artery, GF C57BL/6J mice had increased occlusion times compared to colonized controls. Interestingly, in late atherosclerosis, HFD-fed GF Ldlr^-/- mice had reduced plaque rupture-induced thrombus growth in the carotid artery and diminished ex vivo thrombus formation under arterial flow conditions.

The Notch pathway: a novel therapeutic target for cardiovascular diseases?

Introduction: The Notch pathway is involved in determining cell fate during development and postnatally in continuously renewing tissues, such as the endothelium, the epithelium, and in the stem cells pool. The dysregulation of the Notch pathway is one of the causes of limited response, or resistance, to available cancer treatments and novel therapeutic strategies based on Notch inhibition are being investigated in preclinical and clinical studies in oncology. A large body of evidence now shows that the dysregulation of the Notch pathway is also involved in the pathophysiology of cardiovascular diseases (CVDs). Areas covered: This review discusses the molecular mechanisms involving Notch which underlie heart failure, aortic valve calcification, and aortic aneurysm. Expert opinion: Despite the existence of preventive, pharmacological and surgical interventions approaches, CVDs are the first causes of mortality worldwide. The Notch pathway is becoming increasingly recognized as being involved in heart failure, aortic aneurysm and aortic valve calcification, which are among the most common global causes of mortality due to CVDs. As already shown in cancer, the dissection of the biological processes and molecular mechanisms involving Notch should pave the way for new strategies to prevent and cure these diseases.

Loss of SRSF3 in Cardiomyocytes Leads to Decapping of Contraction-Related mRNAs and Severe Systolic Dysfunction

RATIONALE

RBPs (RNA binding proteins) play critical roles in the cell by regulating mRNA transport, splicing, editing, and stability. The RBP SRSF3 (serine/arginine-rich splicing factor 3) is essential for blastocyst formation and for proper liver development and function. However, its role in the heart has not been explored.

OBJECTIVE

To investigate the role of SRSF3 in cardiac function.

METHODS AND RESULTS

Cardiac SRSF3 expression was high at mid gestation and decreased during late embryonic development. Mice lacking SRSF3 in the embryonic heart showed impaired cardiomyocyte proliferation and died in utero. In the adult heart, SRSF3 expression was reduced after myocardial infarction, suggesting a possible role in cardiac homeostasis. To determine the role of this RBP in the adult heart, we used an inducible, cardiomyocyte-specific SRSF3 knockout mouse model. After SRSF3 depletion in cardiomyocytes, mice developed severe systolic dysfunction that resulted in death within 8 days. RNA-Seq analysis revealed downregulation of mRNAs encoding sarcomeric and calcium handling proteins. Cardiomyocyte-specific SRSF3 knockout mice also showed evidence of alternative splicing of mTOR (mammalian target of rapamycin) mRNA, generating a shorter protein isoform lacking catalytic activity. This was associated with decreased phosphorylation of 4E-BP1 (eIF4E-binding protein 1), a protein that binds to eIF4E (eukaryotic translation initiation factor 4E) and prevents mRNA decapping. Consequently, we found increased decapping of mRNAs encoding proteins involved in cardiac contraction. Decapping was partially reversed by mTOR activation.

CONCLUSIONS

We show that cardiomyocyte-specific loss of SRSF3 expression results in decapping of critical mRNAs involved in cardiac contraction. The molecular mechanism underlying this effect likely involves the generation of a short mTOR isoform by alternative splicing, resulting in reduced 4E-BP1 phosphorylation. The identification of mRNA decapping as a mechanism of systolic heart failure may open the way to the development of urgently needed therapeutic tools.

The Use of Nutraceuticals to Counteract Atherosclerosis: The Role of the Notch Pathway

Despite the currently available pharmacotherapies, today, thirty percent of worldwide deaths are due to cardiovascular diseases (CVDs), whose primary cause is atherosclerosis, an inflammatory disorder characterized by the buildup of lipid deposits on the inside of arteries. Multiple cellular signaling pathways have been shown to be involved in the processes underlying atherosclerosis, and evidence has been accumulating for the crucial role of Notch receptors in regulating the functions of the diverse cell types involved in atherosclerosis onset and progression. Several classes of nutraceuticals have potential benefits for the prevention and treatment of atherosclerosis and CVDs, some of which could in part be due to their ability to modulate the Notch pathway. In this review, we summarize the current state of knowledge on the role of Notch in vascular health and its modulation by nutraceuticals for the prevention of atherosclerosis and/or treatment of related CVDs.

Estrogen-mediated protection against coronary heart disease: The role of the Notch pathway

Estrogen regulates a plethora of biological processes, under physiological and pathological conditions, by affecting key pathways involved in the regulation of cell proliferation, fate, survival and metabolism. The Notch receptors are mediators of communication between adjacent cells and are key determinants of cell fate during development and in postnatal life. Crosstalk between estrogen and the Notch pathway intervenes in many processes underlying the development and maintenance of the cardiovascular system. The identification of molecular mechanisms underlying the interaction between these types of endocrine and juxtacrine signaling are leading to a deeper understanding of physiological conditions regulated by these steroid hormones and, potentially, to novel therapeutic approaches to prevent pathologies linked to reduced levels of estrogen, such as coronary heart disease, and cardiotoxicity caused by hormone therapy for estrogen-receptor-positive breast cancer.

Characterization of smooth muscle cells from human atherosclerotic lesions and their responses to Notch signaling

Atherosclerosis is the most common cause of heart disease and stroke. The use of animal models has advanced our understanding of the molecular signaling that contributes to atherosclerosis. Further understanding of this degenerative process in humans will require human tissue. Plaque removed during endarterectomy procedures to relieve arterial obstructions is usually discarded, but can be an important source of diseased cells. Resected tissue from carotid and femoral endarterectomy procedures were compared with carotid arteries from donors with no known cardiovascular disease. Vascular smooth muscle cells (SMC) contribute to plaque formation and may determine susceptibility to rupture. Notch signaling is implicated in the progression of atherosclerosis, and plays a receptor-specific regulatory role in SMC. We defined protein localization of Notch2 and Notch3 within medial and plaque SMC using immunostaining, and compared Notch2 and Notch3 levels in total plaques with whole normal arteries using immunoblot. We successfully derived SMC populations from multiple endarterectomy specimens for molecular analysis. To better define the protein signature of diseased SMC, we utilized sequential window acquisition of all theoretical spectra (SWATH) proteomic analysis to compare normal carotid artery SMC with endarterectomy-derived SMC. Similarities in protein profile and differentiation markers validated the SMC identity of our explants. We identified a subset of differentially expressed proteins that are candidates as functional markers of diseased SMC. To understand how Notch signaling may affect diseased SMC, we performed Jagged1 stimulation of primary cultures. In populations that displayed significant growth, Jagged1 signaling through Notch2 suppressed proliferation; cultures with low growth potential were non-responsive to Jagged1. In addition, Jagged1 did not promote contractile smooth muscle actin nor have a significant effect on the mature differentiated phenotype. Thus, SMC derived from atherosclerotic lesions show distinct proteomic profiles and have altered Notch signaling in response to Jagged1 as a differentiation stimulus, compared with normal SMC.

NOTCH regulation of the endothelial cell phenotype

Purpose of review

The formation of a hierarchical vascular network is a complex process that requires precise temporal and spatial integration of several signaling pathways. Amongst those, Notch has emerged as a key regulator of multiple steps that expand from endothelial sprouting to arterial specification and remains relevant in the adult. This review aims to summarize major concepts and rising hypotheses on the role of Notch signaling in the endothelium.

Recent findings

A wealth of new information has helped to clarify how Notch signaling cooperates with other pathways to orchestrate vascular morphogenesis, branching, and function. Endothelial vascular endothelial growth factor, C-X-C chemokine receptor type 4, and nicotinamide adenine dinucleotide phosphate oxidase 2 have been highlighted as key regulators of the pathway. Furthermore, blood flow forces during vascular development induce Notch1 signaling to suppress endothelial cell proliferation, enhance barrier function, and promote arterial specification. Importantly, Notch1 has been recently recognized as an endothelial mechanosensor that is highly responsive to the level of shear stress to enable differential Notch activation in distinct regions of the vessel wall and suppress inflammation.

Summary

Although it is well accepted that the Notch signaling pathway is essential for vascular morphogenesis, its contributions to the homeostasis of adult endothelium were uncovered only recently. Furthermore, its exquisite regulation by flow and impressive interface with multiple signaling pathways indicates that Notch is at the center of a highly interactive web that integrates both physical and chemical signals to ensure vascular stability.

Tetramethylpyrazine and Paeoniflorin Inhibit Oxidized LDL-Induced Angiogenesis in Human Umbilical Vein Endothelial Cells via VEGF and Notch Pathways

Atherosclerotic plaque angiogenesis is key factor in plaque instability and vulnerability, and low concentrations of oxidized low density lipoprotein (ox-LDL) promote the in vitro angiogenesis of endothelial cells and play an important role in plaque angiogenesis. Ligusticum chuanxiong Hort. and Radix Paeoniae Rubra herb pair in Chinese medicine obtains the optimum therapeutic efficacy in atherosclerosis, and their major active ingredients tetramethylpyrazine (TMP) and paeoniflorin (PF) are reported to alleviate atherosclerosis. The aim of this study was to investigate the effects of TMP and PF on ox-LDL-induced angiogenesis and the underlying mechanism. Human umbilical vein endothelial cells (HUVECs) were incubated with ox-LDL and were then treated with TMP, PF, or a combination of TMP and PF. Cell proliferation, migration, tube formation, and the expression of angiogenesis-related proteins were measured. Synergism was evaluated using the combination index in cell proliferation. We found that TMP and PF attenuated the in vitro angiogenesis in ox-LDL-induced HUVECs. In addition, the combination of TMP and PF not only inhibited the ox-LDL-induced expression of CD31, vascular endothelial growth factor (VEGF), and VEGF receptor 2 (VEGFR2) but also decreased the ox-LDL-induced expression of Notch1, Jagged1, and Hes1. In summary, the combination of TMP and PF suppresses ox-LDL-induced angiogenesis in HUVECs by inhibiting both the VEGF/VEGFR2 and the Jagged1/Notch1 signaling pathways, which might contribute to the stability of plaques in atherosclerosis.

Gremlin activates the Notch pathway linked to renal inflammation

Preclinical studies suggest that Gremlin participates in renal damage and could be a potential therapeutic target for human chronic kidney diseases. Inflammation is a common characteristic of progressive renal disease, and therefore novel anti-inflammatory therapeutic targets should be investigated. The Notch signaling pathway is involved in kidney development and is activated in human chronic kidney disease, but whether Gremlin regulates the Notch pathway has not been investigated. In cultured tubular cells, Gremlin up-regulated gene expression of several Notch pathway components, increased the production of the canonical ligand Jagged-1, and caused the nuclear translocation of active Notch-1 (N1ICD). In vivo administration of Gremlin into murine kidneys elicited Jagged-1 production, increased N1ICD nuclear levels, and up-regulated the gene expression of the Notch effectors hes-1 and hey-1 All these data clearly demonstrate that Gremlin activates the Notch pathway in the kidney. Notch inhibition using the γ-secretase inhibitor DAPT impaired renal inflammatory cell infiltration and proinflammatory cytokines overexpression in Gremlin-injected mice and in experimental models of renal injury. Moreover, Notch inhibition blocked Gremlin-induced activation of the canonical and noncanonical nuclear factor-κB (NF-κB) pathway, identifying an important mechanism involved in the anti-inflammatory actions of Notch inhibition. In conclusion, Gremlin activates the Notch pathway in the kidney and this is linked to NF-κB-mediated inflammation, supporting the hypothesis that Notch inhibition could be a potential anti-inflammatory strategy for renal diseases.

The role of infiltrating immune cells in dysfunctional adipose tissue

Adipose tissue (AT) dysfunction, characterized by loss of its homeostatic functions, is a hallmark of non-communicable diseases. It is characterized by chronic low-grade inflammation and is observed in obesity, metabolic disorders such as insulin resistance and diabetes. While classically it has been identified by increased cytokine or chemokine expression, such as increased MCP-1, RANTES, IL-6, interferon (IFN) gamma or TNFα, mechanistically, immune cell infiltration is a prominent feature of the dysfunctional AT. These immune cells include M1 and M2 macrophages, effector and memory T cells, IL-10 producing FoxP3+ T regulatory cells, natural killer and NKT cells and granulocytes. Immune composition varies, depending on the stage and the type of pathology. Infiltrating immune cells not only produce cytokines but also metalloproteinases, reactive oxygen species, and chemokines that participate in tissue remodelling, cell signalling, and regulation of immunity. The presence of inflammatory cells in AT affects adjacent tissues and organs. In blood vessels, perivascular AT inflammation leads to vascular remodelling, superoxide production, endothelial dysfunction with loss of nitric oxide (NO) bioavailability, contributing to vascular disease, atherosclerosis, and plaque instability. Dysfunctional AT also releases adipokines such as leptin, resistin, and visfatin that promote metabolic dysfunction, alter systemic homeostasis, sympathetic outflow, glucose handling, and insulin sensitivity. Anti-inflammatory and protective adiponectin is reduced. AT may also serve as an important reservoir and possible site of activation in autoimmune-mediated and inflammatory diseases. Thus, reciprocal regulation between immune cell infiltration and AT dysfunction is a promising future therapeutic target.

Inhibition of Endothelial NOTCH1 Signaling Attenuates Inflammation by Reducing Cytokine-Mediated Histone Acetylation at Inflammatory Enhancers

OBJECTIVE

Endothelial upregulation of adhesion molecules serves to recruit leukocytes to inflammatory sites and appears to be promoted by NOTCH1; however, current models based on interactions between active NOTCH1 and NF-κB components cannot explain the transcriptional selectivity exerted by NOTCH1 in this context.

APPROACH AND RESULTS

Observing that Cre/Lox-induced conditional mutations of endothelial Notch modulated inflammation in murine contact hypersensitivity, we found that IL (interleukin)-1β stimulation induced rapid recruitment of RELA (v-rel avian reticuloendotheliosis viral oncogene homolog A) to genomic sites occupied by NOTCH1-RBPJ (recombination signal-binding protein for immunoglobulin kappa J region) and that NOTCH1 knockdown reduced histone H3K27 acetylation at a subset of NF-κB-directed inflammatory enhancers.

CONCLUSIONS

Our findings reveal that NOTCH1 signaling supports the expression of a subset of inflammatory genes at the enhancer level and demonstrate how key signaling pathways converge on chromatin to coordinate the transition to an infla mmatory endothelial phenotype.

Monocyte-Macrophages and T Cells in Atherosclerosis

Atherosclerosis is an arterial disease process characterized by the focal subendothelial accumulation of apolipoprotein-B-containing lipoproteins, immune and vascular wall cells, and extracellular matrix. The lipoproteins acquire features of damage-associated molecular patterns and trigger first an innate immune response, dominated by monocyte-macrophages, and then an adaptive immune response. These inflammatory responses often become chronic and non-resolving and can lead to arterial damage and thrombosis-induced organ infarction. The innate immune response is regulated at various stages, from hematopoiesis to monocyte changes and macrophage activation. The adaptive immune response is regulated primarily by mechanisms that affect the balance between regulatory and effector T cells. Mechanisms related to cellular cholesterol, phenotypic plasticity, metabolism, and aging play key roles in affecting these responses. Herein, we review select topics that shed light on these processes and suggest new treatment strategies.

Galectin-3 acts as an angiogenic switch to induce tumor angiogenesis via Jagged-1/Notch activation

Angiogenesis is a coordinated process tightly regulated by the balance between Delta-like-4 (DLL4) and Jagged-1 (JAG1) in endothelial cells. Here we show that galectin-3 (gal-3), a glycan-binding protein secreted by cancer cells under hypoxic conditions, triggers sprouting angiogenesis, assisted by hypoxic changes in the glycosylation status of endothelial cells that enhance binding to gal-3. Galectin-3's proangiogenic functions were found to be predominantly dependent on the Notch ligand JAG1. Differential direct binding to JAG1 was shown by surface plasmon resonance assay. Upon binding to Notch ligands, gal-3 preferentially increased JAG1 protein half-life over DLL4 and preferentially activated JAG1/Notch-1 signaling in endothelial cells. JAG1 overexpression in Lewis lung carcinoma cells accelerated tumor growth in vivo, but this effect was prevented in Lgals3-/- mice. Our findings establish gal-3 as a molecular regulator of the JAG1/Notch-1 signaling pathway and have direct implications for the development of strategies aimed at controlling tumor angiogenesis.

Context-dependent function of ROS in the vascular endothelium: The role of the Notch pathway and shear stress

Reactive oxygen species (ROS) act as signal molecules in several biological processes whereas excessive, unregulated, ROS production contributes to the development of pathological conditions including endothelial dysfunction and atherosclerosis. The maintenance of a healthy endothelium depends on many factors and on their reciprocal interactions; in this framework, the Notch pathway and shear stress (SS) play two lead roles. Recently, evidence of a crosstalk between ROS, Notch, and SS, is emerging. The aim of this review is to describe the way ROS interact with the Notch pathway and SS protecting from-or promoting-the development of endothelial dysfunction. © 2017 BioFactors, 43(4):475-485, 2017.