Notch ligand delta-like 4 blockade attenuates atherosclerosis and metabolic disorders

Adipose tissue-selective ablation of ADAM10 results in divergent metabolic phenotypes following long-term dietary manipulation

A Disintegrin And Metalloproteinase domain-containing protein 10 (ADAM10), is involved in several metabolic and inflammatory pathways. We speculated that ADAM10 plays a modulatory role in adipose tissue inflammation and metabolism. To this end, we studied adipose tissue-specific ADAM10 knock-out mice (aKO). While young, regular chow diet-fed aKO mice showed increased insulin sensitivity, following prolonged (33 weeks) high-fat diet (HFD) exposure, aKO mice developed obesity and insulin resistance. Compared to controls, aKO mice showed less inflammatory adipokine profile despite the significant increase in adiposity. In brown adipose tissue, aKO mice on HFD had changes in CD8+ T cell populations indicating a lesser inflammatory pattern. Following HFD, both aKO and control littermates demonstrated decreased adipose tissue pro-inflammatory macrophages, and increased anti-inflammatory accumulation, without differences between the genotypes. Collectively, our observations indicate that selective deletion of ADAM10 in adipocytes results in a mitigated inflammatory response, leading to increased insulin sensitivity in young mice fed with regular diet. This state of insulin sensitivity, following prolonged HFD, facilitates energy storage resulting in increased fat accumulation which ultimately leads to the development of a phenotype of obesity and insulin resistance. In conclusion, the data indicate that ADAM10 has a modulatory effect of inflammation and whole-body energy metabolism.

Research progress of Ganoderma lucidum polysaccharide in prevention and treatment of Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease resulting from dysregulated lipid metabolism, constituting the pathophysiological foundation of cardiovascular and cerebrovascular diseases. AS has a high incidence rate and mortality rate worldwide. As such, traditional Chinese medicine (TCM) has been widely used recently due to its stable therapeutic effect and high safety. Ganoderma lucidum polysaccharides (GLP) are the main active ingredients of Ganoderma lucidum, a Chinese herbal medicine. Research has also shown that GLP has anti-inflammatory and antioxidant properties, regulates gut microbiota, improves blood glucose and lipid levels, and inhibits obesity. Most of the current research on GLP anti-AS is focused on animal models. Thus, its clinical application remains to be discovered. In this review, we combine relevant research results and start with the pathogenesis and risk factors of GLP on AS, proving that GLP can prevent and treat AS, providing a scientific basis and reference for the future prevention and treatment of AS with GLP.

Obesity-associated Airway Hyperresponsiveness: Mechanisms Underlying Inflammatory Markers and Possible Pharmacological Interventions

Obesity is rapidly becoming a global health problem affecting about 13% of the world's population affecting women and children the most. Recent studies have stated that obese asthmatic subjects suffer from an increased risk of asthma, encounter severe symptoms, respond poorly to anti-asthmatic drugs, and ultimately their quality-of-life decreases. Although, the association between airway hyperresponsiveness (AHR) and obesity is a growing concern among the public due to lifestyle and environmental etiologies, however, the precise mechanism underlying this association is yet to establish. Apart from aiming at the conventional antiasthmatic targets, treatment should be directed towards ameliorating obesity pathogenesis too. Understanding the pathogenesis underlying the association between obesity and AHR is limited, however, a plethora of obesity pathologies have been reported viz., increased pro-inflammatory and decreased anti-inflammatory adipokines, depletion of ROS controller Nrf2/HO-1 axis, NLRP3 associated macrophage polarization, hypertrophy of WAT, and down-regulation of UCP1 in BAT following down-regulated AMPKα and melanocortin pathway that may be correlated with AHR. Increased waist circumference (WC) or central obesity was thought to be related to severe AHR, however, some recent reports suggest body mass index (BMI), not WC tends to exaggerate airway closure in AHR due to some unknown mechanisms. This review aims to co-relate the above-mentioned mechanisms that may explain the copious relation underlying obesity and AHR with the help of published reports. A proper understanding of these mechanisms discussed in this review will ensure an appropriate treatment plan for patients through advanced pharmacological interventions.

Delta- like ligand 4- expressing macrophages and human diseases: Insights into pathophysiology and therapeutic opportunities

Macrophages are key players in the immune response and have been implicated in various human diseases, including atherosclerosis, cancer, and chronic inflammatory disorders. While numerous studies have delved into the nuances of macrophage behavior in these conditions, there remains a gap in understanding the specific role of Delta-like ligand 4 (Dll4)-expressing macrophages and their overarching implications across these diseases. Among the plethora of factors expressed by macrophages, Dll4 has emerged as a molecule of particular interest. Recent studies have highlighted its unique role in modulating macrophage functions and its potential implications in various diseases. This review seeks to consolidate existing knowledge, address this gap, and present a comprehensive overview of Dll4-expressing macrophages in the context of these disorders and highlight their potential as therapeutic targets. We examined the involvement of Dll4-expressing macrophages in multiple human diseases such as atherosclerosis, cancer and chronic inflammatory diseases, emphasizing their influence on disease progression. We also discussed the challenges, limitations, and emerging research areas in targeting Dll4-expressing macrophages and provide an outlook on potential therapeutic strategies for the treatment of these diseases. By addressing the previously existing research gap, we've provided a roadmap that brings together fragmented insights, paving the way for more holistic research and potentially more effective therapeutic strategies centered on Dll4-expressing macrophages.

Small-Extracellular-Vesicle-Derived miRNA Profile Identifies miR-483-3p and miR-326 as Regulators in the Pathogenesis of Antiphospholipid Syndrome (APS)

Primary antiphospholipid syndrome (PAPS) is a systemic autoimmune disease associated with recurrent thrombosis and/or obstetric morbidity with persistent antiphospholipid antibodies (aPL). Although these antibodies drive endothelial injury and thrombophilia, the underlying molecular mechanism is still unclear. Small extracellular vesicles (sEVs) contain miRNAs, key players in intercellular communication. To date, the effects of miRNA-derived sEVs in PAPS are not well understood. We characterised the quantity, cellular origin and miRNA profile of sEVs isolated from thrombotic APS patients (PAPS, n = 50), aPL-carrier patients (aPL, n = 30) and healthy donors (HD, n = 30). We found higher circulating sEVs mainly of activated platelet origin in PAPS and aPL patients compared to HD, that were highly engulfed by HUVECs and monocyte. Through miRNA-sequencing analysis, we identified miR-483-3p to be differentially upregulated in sEVs from patients with PAPS and aPL, and miR-326 to be downregulated only in PAPS sEVs. In vitro studies showed that miR-483-3p overexpression in endothelial cells induced an upregulation of the PI3K-AKT pathway that led to endothelial proliferation/dysfunction. MiR-326 downregulation induced NOTCH pathway activation in monocytes with the upregulation of NFKB1, tissue factor and cytokine production. These results provide evidence that miRNA-derived sEVs contribute to APS pathogenesis by producing endothelial cell proliferation, monocyte activation and adhesion/procoagulant factors.

Indoxyl sulfate in atherosclerosis

Atherosclerosis (AS), a chronic vascular inflammatory disease, has become a main focus of attention worldwide for its chronic progressing disease course and serious complications in the later period. Nevertheless, explanations for the exact molecular mechanisms of AS initiation and development remain to be an unsolved problem. The classic pathogenesis theories, such as lipid percolation and deposition, endothelium injury, inflammation and immune damage, provide the foundation for discovering the new key molecules or signaling mechanisms. Recently, indoxyl sulfate (IS), one of non-free uremia toxins, has been noticeable for its multiple atherogenic effects. IS exists at high concentration in plasma for its great albumin binding rate. Patients with uremia have markedly elevated serum levels of IS due both to the deterioration of renal function and to the high binding affinity of IS to albumin. Nowadays, elevated incidence of circulatory disease among patients with renal dysfunction indicates correlation of uremic toxins with cardiovascular damage. In this review, the atherogenic effects of IS and the underlying mechanisms are summarized with emphasis on several key pathological events associated with AS developments, such as vascular endothelium dysfunction, arterial medial lesions, vascular oxidative stress, excessive inflammatory responses, calcification, thrombosis and foam cell formation. Although recent studies have proved the great correlation between IS and AS, deciphering cellular and pathophysiological signaling by confirming key factors involved in IS-mediated atherosclerosis development may enable identification of novel therapeutic targets.

TAOK3 limits age-associated inflammation by negatively modulating macrophage differentiation and their production of TNFα

BACKGROUND

Human aging is characterized by a state of chronic inflammation, termed inflammaging, for which the causes are incompletely understood. It is known, however, that macrophages play a driving role in establishing inflammaging by promoting pro-inflammatory rather than anti-inflammatory responses. Numerous genetic and environmental risk factors have been implicated with inflammaging, most of which are directly linked to pro-inflammatory mediators IL-6, IL1Ra, and TNFα. Genes involved in the signaling and production of those molecules have also been highlighted as essential contributors. TAOK3 is a serine/threonine kinase of the STE-20 kinase family that has been associated with an increased risk of developing auto-immune conditions in several genome-wide association studies (GWAS). Yet, the functional role of TAOK3 in inflammation has remained unexplored.

RESULTS

We found that mice deficient in the serine/Threonine kinase Taok3 developed severe inflammatory disorders with age, which was more pronounced in female animals. Further analyses revealed a drastic shift from lymphoid to myeloid cells in the spleens of those aged mice. This shift was accompanied by hematopoietic progenitor cells skewing in Taok3^-/- mice that favored myeloid lineage commitment. Finally, we identified that the kinase activity of the enzyme plays a vital role in limiting the establishment of proinflammatory responses in macrophages.

CONCLUSIONS

Essentially, Taok3 deficiency promotes the accumulation of monocytes in the periphery and their adoption of a pro-inflammatory phenotype. These findings illustrate the role of Taok3 in age-related inflammation and highlight the importance of genetic risk factors in this condition.

CDK6: an attractive therapeutic target for T-ALL/LBL

INTRODUCTION

Human T-cell acute lymphoblastic leukemia/T-cell lymphoblastic lymphoma (T-ALL/LBL) is a type of cancer that originates from the bone marrow and spreads quickly to other organs. Long-term survival rate with current available chemotherapy is less than 20%. Despite the potentially huge market, a truly effective and safe therapy for T-ALL/LBL is elusive. Thus, it is imperative to identify new therapeutic ways to target essential pathways in T-ALL that regulate the proliferation and survival of these cancer cells.

AREAS COVERED

The role of the Cyclin-dependent kinase 6 (CDK6) pathway in human T-ALL is of significant interest with major clinical/translational relevance. This review covers the recent advances in elucidating the essential roles of CDK6 and its closely regulated networks in proliferation, survival, and metabolism of T-ALL cells, with new insight into its mechanisms of action which hopefully could trigger the identification of new therapeutic avenues.

EXPERT OPINION

Animal models showed that inhibition of CDK6 and its related networks blocked initiation, growth, and survival of T-ALL in vivo. Numerous clinical trials of CDK4/6 inhibitors are ongoing in T-ALL. Specific CDK6 inhibitors alone or novel combination regimens may hopefully delay the progression, or even reverse the symptoms of T-ALL, leading to disease eradication and cure.

Selective inhibitors of the PSEN1-gamma-secretase complex

Clinical development of γ-secretases, a family of intramembrane cleaving proteases, as therapeutic targets for a variety of disorders including cancer and Alzheimer's disease, was aborted because of serious mechanism based side effects in phase III trials of unselective inhibitors. Selective inhibition of specific γ-secretase complexes, containing either PSEN1 or PSEN2 as catalytic subunit and APH1A or APH1B as supporting subunits, do provide a feasible therapeutic window in preclinical models of these disorders. We explore here the pharmacophoric features required for PSEN1 versus PSEN2 selective inhibition. We synthesized a series of brain penetrant 2-azabicyclo[2,2,2]octane sulfonamides and identified a compound with low nanomolar potency and high selectivity (>250-fold) towards the PSEN1-APH1B sub-complex versus PSEN2 sub-complexes. We used modelling and site directed mutagenesis to identify critical amino acids along the entry part of this inhibitor into the catalytic site of PSEN1. Specific targeting one of the different γ-secretase complexes might provide safer drugs in the future.

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.

Monocyte-derived Dll4 is a novel contributor to persistent systemic inflammation in HIV patients

Background

In people living with HIV (PLWH) on combination antiretroviral therapy (cART), persistent systemic inflammation is a driving force for the progression of comorbidities, such as cardiovascular and cerebrovascular diseases. In this context, monocyte- and macrophage-related inflammation rather than T cell activation is a major cause of chronic inflammation. However, the underlying mechanism of how monocytes cause persistent systemic inflammation in PLWH is elusive.

Methods and Results

In vitro, we demonstrated that lipopolysaccharides (LPS) or tumor necrosis factor alpha (TNFα), induced a robust increase of Delta-like ligand 4 (Dll4) mRNA and protein expression in human monocytes and Dll4 secretion (extracellular Dll4, exDll4) from monocytes. Enhanced membrane-bound Dll4 (mDll4) expression in monocytes triggered Notch1 activation to promote pro-inflammatory factors expression. Dll4 silencing and inhibition of Nocth1 activation diminished the LPS or TNFα -induced inflammation. exDll4 releases in response to cytokines occurred in monocytes but not endothelial cells or T cells. In clinical specimens, we found that PLWH, both male and female, on cART, showed a significant increase in mDll4 expression, activation of Dll4-Notch1 signaling, and inflammatory markers in monocytes. Although there was no sex effect on mDII4 in PLWH, plasma exDll4 was significantly elevated in males but not females compared to HIV uninfected individuals. Furthermore, exDll4 plasma levels paralleled with monocytes mDll4 in male PLWH. Circulating exDll4 was also positively associated with pro-inflammatory monocytes phenotype and negatively associated with classic monocytes phenotype in male PLWH.

Conclusion

Pro-inflammatory stimuli increase Dll4 expression and Dll4-Notch1 signaling activation in monocytes and enhance monocyte proinflammatory phenotype, contributing to persistent systemic inflammation in male and female PLWH. Therefore, monocyte mDll4 could be a potential biomarker and therapeutic target of systemic inflammation. Plasma exDll4 may also play an additional role in systemic inflammation but primarily in men.

Notch signaling is activated in knee-innervating dorsal root ganglia in experimental models of osteoarthritis joint pain

BACKGROUND

We aimed to explore activation of the Notch signaling pathway in knee-innervating lumbar dorsal root ganglia (DRG) in the course of experimental osteoarthritis (OA) in mice, and its role in knee hyperalgesia.

METHODS

Cultured DRG cells were stimulated with the TLR4 agonist, lipopolysaccharide (LPS). Notch signaling in the cells was either inhibited with the γ-secretase inhibitor, DAPT, or with soluble Jagged1, or activated through immobilized Jagged1. CCL2 production was analyzed at mRNA and protein levels. In in vivo experiments, knee hyperalgesia was induced in naïve mice through intra-articular (IA) injection of LPS. The effect of inhibiting Notch signaling was examined by pre-injecting DAPT one hour before LPS. OA was induced through surgical destabilization of the medial meniscus (DMM) in male C57BL/6 mice. Gene expression in DRG was analyzed by qRT-PCR and RNAscope in situ hybridization. Activated Notch protein (NICD) expression in DRG was evaluated by ELISA and immunofluorescence staining. DAPT was injected IA 12 weeks post DMM to inhibit Notch signaling, followed by assessing knee hyperalgesia and CCL2 expression in the DRG.

RESULTS

In DRG cell cultures, LPS increased NICD in neuronal cells. Inhibition of Notch signaling with either DAPT or soluble Jagged1 attenuated LPS-induced increases of Ccl2 mRNA and CCL2 protein. Conversely, activating Notch signaling with immobilized Jagged1 enhanced these LPS effects. In vivo, IA injection of LPS increased expression of Notch genes and NICD in the DRG. Pre-injection of DAPT prior to LPS alleviated LPS-induced knee hyperalgesia, and decreased LPS-induced CCL2 expression in the DRG. Notch signaling genes were differentially expressed in the DRG from late-stage experimental OA. Notch1, Hes1, and NICD were increased in the neuronal cell bodies in DRG after DMM surgery. IA administration of DAPT alleviated knee hyperalgesia post DMM, and decreased CCL2 expression in the DRG.

CONCLUSIONS

These findings suggest a synergistic effect of Notch signaling with TLR4 in promoting CCL2 production and mediating knee hyperalgesia. Notch signaling is activated in knee-innervating lumbar DRG in mice with experimental OA, and is involved in mediating knee hyperalgesia. The pathway may therefore be explored as a target for alleviating OA pain.

DLL4-Notch signalling in acute-on-chronic liver failure: State of the art and perspectives

Acute-on-chronic liver failure (ACLF) is a syndrome characterized by acute decompensation of chronic liver disease associated with multiple-organ failures and high short-term mortality. Acute insults to patients with chronic liver disease can lead to ACLF, among which, hepatitis B virus-related ACLF is the most common type of liver failure in the Asia-Pacific region. Currently, immune-metabolism disorders and systemic inflammation are proposed to be the main mechanisms of ACLF. The resulting cholestasis and intrahepatic microcirculatory dysfunction accelerate the development of ACLF. Treatments targeting immune regulation, metabolic balance, microcirculation maintenance and bile duct repair can alleviate inflammation and restore the tissue structure. An increasing number of studies have demonstrated that delta-like ligand 4 (DLL4), one of the Notch signalling ligands, plays a vital role in immune regulation, metabolism, angiogenesis, and biliary regeneration, which participate in liver pathological and physiological processes. The detailed mechanism of the DLL4-Notch signalling pathway in ACLF has rarely been investigated. Here, we review the evidence showing that DLL4-Notch signalling is involved in ACLF and analyse the potential role of DLL4 in the treatment of ACLF.

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.

Macrophages as a therapeutic target to promote diabetic wound healing

It is well‏ ‏established that macrophages are key regulators of wound healing, displaying impressive plasticity and an evolving phenotype, from an aggressive pro-inflammatory or "M1" phenotype to a pro-healing or "M2" phenotype, depending on the wound healing stage, to ensure proper healing. Because dysregulated macrophage responses have been linked to impaired healing of diabetic wounds, macrophages are being considered as a therapeutic target for improved wound healing. In this review, we first discuss the role of macrophages in a normal skin wound healing process and discuss the aberrations that occur in macrophages under diabetic conditions. Next we provide an overview of recent macrophage-based therapeutic approaches, including delivery of ex-vivo-activated macrophages and delivery of pharmacological strategies aimed at eliminating or re-educating local skin macrophages. In particular, we focus on strategies to silence key regulator genes to repolarize wound macrophages to the M2 phenotype, and we provide a discussion of their potential future clinical translation.

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.

The Notch Signaling Pathway Contributes to Angiogenesis and Tumor Immunity in Breast Cancer

Breast cancer in women is the first leading tumor in terms of incidence worldwide. Some subtypes of BC lack distinct molecular targets and exhibit therapeutic resistance; these patients have a poor prognosis. Thus, the search for new molecular targets is an ongoing challenge for BC therapy. The Notch signaling pathway is found in both vertebrates and invertebrates, and it is a highly conserved in the evolution of the species, controlling cellular fates such as death, proliferation, and differentiation. Numerous studies have shown that improper activation of Notch signaling may lead to excessive cell proliferation and cancer, with tumor-promoting and tumor-suppressive effects in various carcinomas. Thus, inhibitors of Notch signaling are actively being investigated for the treatment of various tumors. The role of Notch signaling in BC has been widely studied in recent years. There is a growing body of evidence suggesting that Notch signaling has a pro-oncogenic role in BC, and the tumor-promoting effect is largely a result of the diverse nature of tumor immunity. Immunological abnormality is also a factor involved in the pathogenesis of BC, suggesting that Notch signaling could be a target for BC immunotherapies. Furthermore, angiogenesis is essential for BC growth and metastasis, and the Notch signaling pathway has been implicated in angiogenesis, so studying the role of Notch signaling in BC angiogenesis will provide new prospects for the treatment of BC. We summarize the potential roles of the current Notch signaling pathway and its inhibitors in BC angiogenesis and the immune response in this review and describe the pharmacological targets of Notch signaling in BC, which may serve as a theoretical foundation for future research into exploring this pathway for novel BC therapies.

Therapeutic Targeting Notch2 Protects Bone Micro-Vasculatures from Methotrexate Chemotherapy-Induced Adverse Effects in Rats

Intensive cancer chemotherapy is well known to cause bone vasculature disfunction and damage, but the mechanism is poorly understood and there is a lack of treatment. Using a rat model of methotrexate (MTX) chemotherapy (five once-daily dosses at 0.75 mg/kg), this study investigated the roles of the Notch2 signalling pathway in MTX chemotherapy-induced bone micro-vasculature impairment. Gene expression, histological and micro-computed tomography (micro-CT) analyses revealed that MTX-induced micro-vasculature dilation and regression is associated with the induction of Notch2 activity in endothelial cells and increased production of inflammatory cytokine tumour necrosis factor alpha (TNFα) from osteoblasts (bone forming cells) and bone marrow cells. Blockade of Notch2 by a neutralising antibody ameliorated MTX adverse effects on bone micro-vasculature, both directly by supressing Notch2 signalling in endothelial cells and indirectly via reducing TNFα production. Furthermore, in vitro studies using rat bone marrow-derived endothelial cell revealed that MTX treatment induces Notch2/Hey1 pathway and negatively affects their ability in migration and tube formation, and Notch2 blockade can partially protect endothelial cell functions from MTX damage.

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.

Advanced Glycation End Products Induce Atherosclerosis via RAGE/TLR4 Signaling Mediated-M1 Macrophage Polarization-Dependent Vascular Smooth Muscle Cell Phenotypic Conversion

Objective. The objective of this study was to investigate the involved mechanisms of advanced glycation end product- (AGE-) exacerbated atherosclerosis (AS). Methods. Toll-like receptor 4 (TLR4) inhibitor was administrated to type 2 diabetes mellitus (T2DM) AS rats. Atherosclerotic plaque, M1 macrophage infiltration, and VSMCs phenotypes were evaluated. AGE-exposed primary macrophages were treated with specific siRNAs knocking down receptor for AGEs (RAGE) and TLR4. Phenotypes of M1 macrophage and VSMCs were identified by fluorescent stains. Contact and noncontact coculture models were established. VSMCs and macrophages were cocultured in these models. ELISA was used to detect inflammatory cytokine concentrations. Relative mRNA expression levels were determined by real-time PCR. Relative protein expression and phosphorylation levels were evaluated by Western blots assays. Results. TLR4 inhibitor treatment significantly reduced arterial stenosis, infiltration of M1 polarized macrophages, and contractile-to-synthetic phenotype conversion of VSMCs in DM AS animals. RAGE and TLR4 silencing dramatically reduced AGE-induced macrophage M1 polarization, inflammatory cytokine secretion, and RAGE/TLR4/forkhead box protein C2 (FOXC2)/signaling which inhibited delta-like ligand 4 (Dll4) expression in macrophages. AGE-treated macrophages induced VSMC phenotypic conversion via activating Notch pathway in a contact coculture model rather than a noncontact model. The VSMC phenotypic conversion induction capability of macrophages was attenuated by RAGE and TLR4 silencing. Conclusions. AGEs induced activation of RAGE/TLR4/FOXC2 signaling, which featured macrophage with Dll4 high expression during M1 polarization. These macrophages promoted contractile-synthetic phenotypic conversion of VSMCs through the Dll4/Notch pathway after direct cell-to-cell contacts.

Reduced Notch1 Cleavage Promotes the Development of Pulmonary Hypertension

Clinical trials of Dll4 (Delta-like 4) neutralizing antibodies (Dll4nAbs) in cancer patients are ongoing. Surprisingly, pulmonary hypertension (PH) occurs in 14% to 18% of patients treated with Dll4nAbs, but the mechanisms have not been studied. Here, PH progression was measured in mice treated with Dll4nAbs. We detected Notch signaling in lung tissues and analyzed pulmonary vascular permeability and inflammation. Notch target gene array was performed on adult human pulmonary microvascular endothelial cells (ECs) after inhibiting Notch cleavage. Similar mechanisms were studied in PH mouse models and pulmonary arterial hypertension patients. The rescue effects of constitutively activated Notch1 in vivo were also measured. We observed that Dll4nAbs induced PH in mice as indicated by significantly increased right ventricular systolic pressure, as well as pulmonary vascular and right ventricular remodeling. Mechanistically, Dll4nAbs inhibited Notch1 cleavage and subsequently impaired lung endothelial barrier function and increased immune cell infiltration in vessel walls. In vitro, Notch targeted genes' expression related to cell growth and inflammation was decreased in human pulmonary microvascular ECs after the Notch1 inactivation. In lungs of PH mouse models and pulmonary arterial hypertension patients, Notch1 cleavage was inhibited. Consistently, EC cell-cell junction was leaky, and immune cell infiltration increased in PH mouse models. Overexpression activated Notch1-attenuated progression of PH in mice. In conclusion, Dll4nAbs led to PH development in mice by impaired EC barrier function and increased immune cell infiltration through inhibition of Notch1 cleavage in lung ECs. Reduced Notch1 cleavage in lung ECs could be an underlying mechanism of PH pathogenesis.

Cross-regulation of notch/AKT and serum/glucocorticoid regulated kinase 1 (SGK1) in IL-4-stimulated human macrophages

Notch signaling regulates the responses of macrophages to different stimuli in a context-dependent manner. The roles of Notch signaling in proinflammatory macrophages are well characterized, whereas its involvement, if any, in IL-4-stimulated macrophages (M(IL-4)) is still unclear. We observed that Notch signaling is functional in human M(IL-4). We performed transcriptome analysis of the Notch1 intracellular domain (NIC1)-overexpressing human monocytic cell line THP-1 with or without IL-4 stimulation to understand the global impact of Notch signaling in M(IL-4). The results revealed that NIC1-overexpressing THP-1 upregulated proinflammatory-associated genes and target genes of IL-4 signaling. We identified serum/glucocorticoid regulated kinase 1 (SGK1) as one of the genes increased by NIC1 overexpression in M(IL-4). To dissect the signaling pathway leading to SGK1 upregulation, we pretreated THP-1-derived macrophages with specific inhibitors of Notch (DAPT), AKT (LY294002) or ERK (U0126). Among these inhibitors, only LY294002 decreased the SGK1 mRNA levels in M(IL-4), indicating that the AKT pathway plays a key role in SGK1 transcription in M(IL-4). Furthermore, treatment of THP-1-derived macrophages with the SGK1 inhibitor (GSK650394) suppressed AKT phosphorylation, but not STAT6, in response to IL-4, indicating that SGK1 positively regulates AKT pathway in M(IL-4). Finally, GSK650394 treatment of human M(IL-4) increased the levels of PPARG mRNA and its protein, indicating a negative role of SGK1 in M(IL-4) function. Overall, we report that the Notch signaling and AKT pathways cooperatively regulate SGK1 expression in M(IL-4) where SGK1, in turn, plays an important role in suppressing IL-4-induced PPAR_γ expression.

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.

Substrate stiffness modulates endothelial cell function via the YAP-Dll4-Notch1 pathway

Endothelial cells adapt their functions as a consequence of sensing extracellular substrate stiffness; these alterations allow them to maintain their vascular structure and function. Substrate stiffness-mediated yes-associated protein 1 (YAP) activation plays an important role in mechano-transduction and pro-angiogenic phenotype of endothelial cells, and Delta-like ligand 4 (Dll4)-Notch1 signaling is closely related to angiogenesis; however, the impact of substrate stiffness-mediated interrelation of these pathways on endothelial cell functions remains elusive. We confirmed that endothelial cells on softer substrates not only elongate cellular aspects but also attenuate YAP activation compared to cells on stiffer substrates. Endothelial cells on softer substrates also upregulate the vascular endothelial growth factor receptor 1 (VEGFR1) and VEGFR2 mRNA expression that is enhanced by VEGF stimulation. We determined that endothelial cells on softer substrates increased Dll4 expression, but not Notch1 expression, via YAP signaling. Moreover, endothelial cells on soft substrates induced not only VEGFRs upregulation but also suppression of pro-inflammatory interleukin-6 and plasminogen activator inhibitor-1 mRNA expression and the facilitation of anti-coagulant thrombomodulin and pro-coagulant tissue factor mRNA expression. Our results suggest that endothelial cells activate the YAP-Dll4-Notch signaling pathway in response to substrate stiffness and dictate cellular function.

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.

Interleukin-22: a potential therapeutic target in atherosclerosis

BACKGROUND

Atherosclerosis is recognized as a chronic immuno-inflammatory disease that is characterized by the accumulation of immune cells and lipids in the vascular wall. In this review, we focus on the latest advance regarding the regulation and signaling pathways of IL-22 and highlight its impacts on atherosclerosis.

MAIN BODY

IL-22, an important member of the IL-10 family of cytokines, is released by cells of the adaptive and innate immune system and plays a key role in the development of inflammatory diseases. The binding of IL-22 to its receptor complex can trigger a diverse array of downstream signaling pathways, in particular the JAK/STAT, to induce the expression of chemokines and proinflammatory cytokines. Recently, numerous studies suggest that IL-22 is involved in the pathogenesis of atherosclerosis by regulation of VSMC proliferation and migration, angiogenesis, inflammatory response, hypertension, and cholesterol metabolism.

CONCLUSION

IL-22 promotes the development of atherosclerosis by multiple mechanisms, which may be a promising therapeutic target in the pathogenesis of atherosclerosis.

Emerging Roles of the Innate Immune System Regulated by DNA Sensors in the Development of Vascular and Metabolic Diseases

Sterile chronic inflammation causes cardiometabolic disorders; however, the mechanisms are not fully understood. Previous studies have demonstrated the degradation of cells/tissues in the vasculature and metabolic organs in lifestyle-associated diseases, such as diabetes and hyperlipidemia, suggesting the release and/or accumulation of nucleic acids from damaged cells. DNA is indispensable for life; however, DNA fragments, especially those from pathogens, strongly induce inflammation by the activation of DNA sensors. Growing evidence suggests that DNA-sensing mechanisms, which are normally involved in self-defense against pathogens as the innate immune system, are associated with the progression of inflammatory diseases in response to endogenous DNA fragments. There are several types of DNA sensors in our bodies. Toll-like receptor 9 (TLR9)—one of the most studied DNA sensors—recognizes DNA fragments in endosome. In addition, stimulator of interferon genes (STING), which has recently been extensively investigated, recognizes cyclic GMP-AMP (cGAMP) generated from DNA fragments in the cytosol. Both TLR9 and STING are known to play pivotal roles in host defense as the innate immune system. However, recent studies have indicated that the activation of these DNA sensors in immune cells, such as macrophages, promotes inflammation leading to the development of vascular and metabolic diseases associated with lifestyle. In this review, we discuss recent advances in determining the roles of DNA sensors in these disease contexts. Revealing a novel mechanism of sterile chronic inflammation regulated by DNA sensors might facilitate clinical interventions for these health conditions.

Notch Signaling Ligand Jagged1 Enhances Macrophage-Mediated Response to Helicobacter pylori

Helicobacter pylori (H. pylori) is one of the gram-negative bacteria that mainly colonize the stomach mucosa and cause many gastrointestinal diseases, such as gastritis, peptic ulcer, and gastric cancer. Macrophages play a key role in eradicating H. pylori. Recent data have shown that Notch signaling could modulate the activation and bactericidal activities of macrophages. However, the role of Notch signaling in macrophages against H. pylori remains unclear. In the present study, in the co-culture model of macrophages with H. pylori, the inhibition of Notch signaling using γ-secretase decreased the expression of inducible nitric oxide synthase (iNOS) and its product, nitric oxide (NO), and downregulated the secretion of pro-inflammatory cytokine and attenuated phagocytosis and bactericidal activities of macrophages to H. pylori. Furthermore, we identified that Jagged1, one of Notch signaling ligands, was both upregulated in mRNA and protein level in activated macrophages induced by H. pylori. Clinical specimens showed that the number of Jagged1⁺ macrophages in the stomach mucosa from H. pylori-infected patients was significantly higher than that in healthy control. The overexpression of Jagged1 promoted bactericidal activities of macrophages against H. pylori and siRNA-Jagged1 presented the opposite effect. Besides, the addition of exogenous rJagged1 facilitated the pro-inflammatory mediators of macrophages against H. pylori, but the treatment of anti-Jagged1 neutralizing antibody attenuated it. Taken together, these results suggest that Jagged1 is a promoting molecule for macrophages against H. pylori, which will provide insight for exploring Jagged1 as a novel therapeutic target for the control of H. pylori infection.

Ganoderma lucidum triterpenoids and polysaccharides attenuate atherosclerotic plaque in high-fat diet rabbits

BACKGROUND AND AIMS

Atherosclerosis is characterized by lipid deposition, oxidative stress, and inflammation in the arterial intima. Ganoderma lucidum triterpenoids (GLTs) and polysaccharides (GLPs) are traditional Chinese medicines with potential cardiovascular benefits. We aimed to comprehensively evaluate the effect of GLTs and GLPs on atherosclerosis and the associated underlying mechanisms in vivo and in vitro.

METHODS AND RESULTS

Japanese big-ear white rabbits were randomly divided into three groups of blank, model, and treatment, and the treatment group was fed with GLSO and GLSP (0.3 g/kg body-weight/day) for 4 months. Serum levels of triglyceride (TG), total (TC), and low density lipoprotein cholesterol (LDL-C) in GL treatment group were significantly lower than those in the model group. The area of aortic plaques was significantly reduced in the treatment group. Further, GL administration in oxidized low-density lipoprotein (ox-LDL) stimulated human umbilical vein endothelial cells (HUVECs) reduced the generation of reactive oxygen species (ROS) and malondialdehyde (MDA) by inhibiting the upregulation of the nuclear transcription factor (NF)-κB p65 and the relative receptor LOX-1. In THP-1 cells treated with phorbol myristate acetate, GL inhibited the inflammatory polarization of macrophages (as evidenced by reduced TNF-α levels) via regulation of Notch1 and DLL4 pathways. Ox-LDL-stimulated THP-1 cells treated with GL showed an increase in the apoptosis of foam cells.

CONCLUSIONS

GLTs and GLPs attenuated the progression of atherosclerosis by alleviating endothelial dysfunction and inflammatory polarization of macrophages, thus promoting apoptosis of foam cells.

Restorative effect of adipose tissue-derived stem cells on impaired hepatocytes through Notch signaling in non-alcoholic steatohepatitis mice

Adipose tissue-derived stem cells (ADSCs) have been suggested as a novel treatment for non-alcoholic steatohepatitis (NASH); however, the mechanisms underlying their therapeutic effect remain poorly understood. In this study, we aimed to investigate the association of Notch signaling, which is crucial for cellular proliferation and differentiation in ADSC-mediated treatment of NASH. Flow cytometry analysis of ADSCs showed that they expressed the Notch ligands JAG1, DLL1, and DLL4. The expression of genes associated with the Notch signaling pathway was attenuated in hepatocytes of NASH model mice. We further observed ADSC-mediated activation of Notch signaling in these hepatocytes in addition to an increase in proliferating cell nuclear antigen⁺ cells and a decrease in TdT-mediated dUTP-biotin nick end labeling⁺ apoptotic cells. Co-culture of palmitic acid-induced steatotic hepatocytes and ADSCs resulted in the activation of Notch signaling and reduction of apoptosis of steatotic hepatocytes. Moreover, inhibition of Notch signaling by a γ-secretase inhibitor and knockdown of Notch ligands using siRNA attenuated the anti-apoptotic effect of co-cultured ADSCs in vitro. Our findings show that the Notch signaling pathway is involved in the inhibition of apoptosis and restoration of cellular proliferation of hepatocytes from NASH mice following ADSC treatment.

Therapeutic Targeting of Notch Signaling: From Cancer to Inflammatory Disorders

Over the past two decades, the Notch signaling pathway has been investigated as a therapeutic target for the treatment of cancers, and more recently in the context of immune and inflammatory disorders. Notch is an evolutionary conserved pathway found in all metazoans that is critical for proper embryonic development and for the postnatal maintenance of selected tissues. Through cell-to-cell contacts, Notch orchestrates cell fate decisions and differentiation in non-hematopoietic and hematopoietic cell types, regulates immune cell development, and is integral to shaping the amplitude as well as the quality of different types of immune responses. Depriving some cancer types of Notch signals has been shown in preclinical studies to stunt tumor growth, consistent with an oncogenic function of Notch signaling. In addition, therapeutically antagonizing Notch signals showed preclinical potential to prevent or reverse inflammatory disorders, including autoimmune diseases, allergic inflammation and immune complications of life-saving procedures such allogeneic bone marrow and solid organ transplantation (graft-versus-host disease and graft rejection). In this review, we discuss some of these unique approaches, along with the successes and challenges encountered so far to target Notch signaling in preclinical and early clinical studies. Our goal is to emphasize lessons learned to provide guidance about emerging strategies of Notch-based therapeutics that could be deployed safely and efficiently in patients with immune and inflammatory disorders.

Targeting the Notch Signaling Pathway in Chronic Inflammatory Diseases

The Notch signaling pathway regulates developmental cell-fate decisions and has recently also been linked to inflammatory diseases. Although therapies targeting Notch signaling in inflammation in theory are attractive, their design and implementation have proven difficult, at least partly due to the broad involvement of Notch signaling in regenerative and homeostatic processes. In this review, we summarize the supporting role of Notch signaling in various inflammation-driven diseases, and highlight efforts to intervene with this pathway by targeting Notch ligands and/or receptors with distinct therapeutic strategies, including antibody designs. We discuss this in light of lessons learned from Notch targeting in cancer treatment. Finally, we elaborate on the impact of individual Notch members in inflammation, which may lay the foundation for development of therapeutic strategies in chronic inflammatory diseases.

SVEP1 is a human coronary artery disease locus that promotes atherosclerosis

A low-frequency variant of sushi, von Willebrand factor type A, EGF, and pentraxin domain-containing protein 1 (SVEP1), an extracellular matrix protein, is associated with risk of coronary disease in humans independent of plasma lipids. Despite a robust statistical association, if and how SVEP1 might contribute to atherosclerosis remained unclear. Here, using Mendelian randomization and complementary mouse models, we provide evidence that SVEP1 promotes atherosclerosis in humans and mice and is expressed by vascular smooth muscle cells (VSMCs) within the atherosclerotic plaque. VSMCs also interact with SVEP1, causing proliferation and dysregulation of key differentiation pathways, including integrin and Notch signaling. Fibroblast growth factor receptor transcription increases in VSMCs interacting with SVEP1 and is further increased by the coronary disease-associated SVEP1 variant p.D2702G. These effects ultimately drive inflammation and promote atherosclerosis. Together, our results suggest that VSMC-derived SVEP1 is a proatherogenic factor and support the concept that pharmacological inhibition of SVEP1 should protect against atherosclerosis in humans.

Mural Cells: Potential Therapeutic Targets to Bridge Cardiovascular Disease and Neurodegeneration

Mural cells collectively refer to the smooth muscle cells and pericytes of the vasculature. This heterogenous population of cells play a crucial role in the regulation of blood pressure, distribution, and the structural integrity of the vascular wall. As such, dysfunction of mural cells can lead to the pathogenesis and progression of a number of diseases pertaining to the vascular system. Cardiovascular diseases, particularly atherosclerosis, are perhaps the most well-described mural cell-centric case. For instance, atherosclerotic plaques are most often described as being composed of a proliferative smooth muscle cap accompanied by a necrotic core. More recently, the role of dysfunctional mural cells in neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease, is being recognized. In this review, we begin with an exploration of the mechanisms underlying atherosclerosis and neurodegenerative diseases, such as mural cell plasticity. Next, we highlight a selection of signaling pathways (PDGF, Notch and inflammatory signaling) that are conserved across both diseases. We propose that conserved mural cell signaling mechanisms can be exploited for the identification or development of dual-pronged therapeutics that impart both cardio- and neuroprotective qualities.

Regulatory microRNAs in Brown, Brite and White Adipose Tissue

MicroRNAs (miRNAs) constitute a class of short noncoding RNAs which regulate gene expression by targeting messenger RNA, inducing translational repression and messenger RNA degradation. This regulation of gene expression by miRNAs in adipose tissue (AT) can impact on the regulation of metabolism and energy homeostasis, particularly considering the different types of adipocytes which exist in mammals, i.e., white adipocytes (white AT; WAT), brown adipocytes (brown AT; BAT), and inducible brown adipocytes in WAT (beige or brite or brown-in-white adipocytes). Indeed, an increasing number of miRNAs has been identified to regulate key signaling pathways of adipogenesis in BAT, brite AT, and WAT by acting on transcription factors that promote or inhibit adipocyte differentiation. For example, MiR-328, MiR-378, MiR-30b/c, MiR-455, MiR-32, and MiR-193b-365 activate brown adipogenesis, whereas MiR-34a, MiR-133, MiR-155, and MiR-27b are brown adipogenesis inhibitors. Given that WAT mainly stores energy as lipids, whilst BAT mainly dissipates energy as heat, clarifying the effects of miRNAs in different types of AT has recently attracted significant research interest, aiming to also develop novel miRNA-based therapies against obesity, diabetes, and other obesity-related diseases. Therefore, this review presents an up-to-date comprehensive overview of the role of key regulatory miRNAs in BAT, brite AT, and WAT.

Notch Signaling and Liver Cancer

Interactions between liver cells are closely regulated by Notch signaling. Notch signaling has been reported clinically related to bile duct hypogenesis in Alagille syndrome, which is caused by mutations in the Jagged1 gene. Notch activation and hepatocarcinogenesis are closely associated since cancer signaling is affected by the development of liver cells and cancer stem cells. Gene expression and genomic analysis using a microarray revealed that abnormalities in Notch-related genes were associated with the aggressiveness of liver cancer. This pattern was also accompanied with α-fetoprotein- and EpCAM-expressing phenotypes in vitro, in vivo, and in clinical tissues. Hepatitis B or C virus chronic infection or alcohol- or steatosis-related liver fibrosis induces liver cancer. Previous reports demonstrated that HBx, a hepatitis B virus protein, was associated with Jagged1 expression. We found that the Jagged1 and Notch1 signaling pathways were closely associated with the transcription of covalently closed circular hepatitis B virus DNA, which regulated cAMP response element-binding protein, thereby affecting Notch1 regulation by the E3 ubiquitin ligase ITCH. This viral pathogenesis in hepatocytes induces liver cancer. In conclusion, Notch signaling exerts various actions and is a clinical signature associated with hepatocarcinogenesis and liver context-related developmental function.

Nutrition Regulates Innate Immunity in Health and Disease

Nutrient content and nutrient timing are considered key regulators of human health and a variety of diseases and involve complex interactions with the mucosal immune system. In particular, the innate immune system is emerging as an important signaling hub that modulates the response to nutritional signals, in part via signaling through the gut microbiota. In this review we elucidate emerging evidence that interactions between innate immunity and diet affect human metabolic health and disease, including cardiometabolic disorders, allergic diseases, autoimmune disorders, infections, and cancers. Furthermore, we discuss the potential modulatory effects of the gut microbiota on interactions between the immune system and nutrition in health and disease, namely how it relays nutritional signals to the innate immune system under specific physiological contexts. Finally, we identify key open questions and challenges to comprehensively understanding the intersection between nutrition and innate immunity and how potential nutritional, immune, and microbial therapeutics may be developed into promising future avenues of precision treatment.

p.P476S mutation of RBPJL inhibits the efficacy of anti-PD-1 therapy in oesophageal squamous cell carcinoma by blunting T-cell responses

Objectives

Anti-PD-1 immune checkpoint blockade represents the onset of a new era in cancer immunotherapy. However, robust predictors are necessary for screening patients with immune checkpoint-responsive oesophageal squamous cell carcinoma (ESCC).

Methods

We obtained biopsy samples from an ESCC patient with mixed responses. The expression of CD4, CD8, CD68, PD-L1, RBPJL and IL-16 was analysed by immunohistochemistry, and the correlation with prognostic value was obtained from the GEPIA portal. T-cell functions were examined by flow cytometry, MTS and transwell assays. The secreted cytokines were identified using an Inflammation Array Kit. The concentration of soluble IFN-γ was measured by enzyme-linked immunosorbent assay. The clinical benefit of RBPJL was examined in a PBMC xenograft mouse model.

Results

The patient had an exceptional clinical response with shrinkage of the primary oesophageal and lung metastatic lesions as well as enlargement of liver metastatic lesions after toripalimab monotherapy. Four liver-specific gene mutations were identified. RBPJL showed better response to toripalimab in the PBMC cell-derived xenograft (CDX) ESCC model. Conditional medium from RBPJL overexpression induced chemotaxis and proliferation of T lymphocytes, as well as Th2/Th1 differentiation through the RBPJL-NF-κB-IL-16 axis in vitro. These functions were all inhibited by the p.P476S mutation of RBPJL (RBPJL (p.P476S)).

Conclusions

We report for the first time that RBPJL (p.P476S) promotes tumor growth in ESCC and inhibits the efficacy of anti-PD-1 therapy through blunting T-cell responses. Our findings provide a potential new predictor for evaluating the efficacy of anti-PD-1 therapy in ESCC patients.

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.

Distinct subsets of T cells and macrophages impact venous remodeling during arteriovenous fistula maturation

Patients with end-stage renal failure depend on hemodialysis indefinitely without renal transplantation, requiring a long-term patent vascular access. While the arteriovenous fistula (AVF) remains the preferred vascular access for hemodialysis because of its longer patency and fewer complications compared with other vascular accesses, the primary patency of AVF is only 50-60%, presenting a clinical need for improvement. AVF mature by developing a thickened vascular wall and increased diameter to adapt to arterial blood pressure and flow volume. Inflammation plays a critical role during vascular remodeling and fistula maturation; increased shear stress triggers infiltration of T-cells and macrophages that initiate inflammation, with involvement of several different subsets of T-cells and macrophages. We review the literature describing distinct roles of the various subsets of T-cells and macrophages during vascular remodeling. Immunosuppression with sirolimus or prednisolone reduces neointimal hyperplasia during AVF maturation, suggesting novel approaches to enhance vascular remodeling. However, M2 macrophages and CD4+ T-cells play essential roles during AVF maturation, suggesting that total immunosuppression may suppress adaptive vascular remodeling. Therefore it is likely that regulation of inflammation during fistula maturation will require a balanced approach to coordinate the various inflammatory cell subsets. Advances in immunosuppressive drug development and delivery systems may allow for more targeted regulation of inflammation to improve vascular remodeling and enhance AVF maturation.

Toll-Like Receptor 9 Plays a Pivotal Role in Angiotensin II-Induced Atherosclerosis

Background Toll-like receptor ( TLR ) 9 recognizes bacterial DNA , activating innate immunity, whereas it also provokes inflammation in response to fragmented DNA released from mammalian cells. We investigated whether TLR 9 contributes to the development of vascular inflammation and atherogenesis using apolipoprotein E-deficient ( Apoe ^-/-) mice. Methods and Results Tlr9-deficient Apoe ^-/- ( Tlr9 ^-/- Apoe ^-/-) mice and Apoe ^-/- mice on a Western-type diet received subcutaneous angiotensin II infusion (1000 ng/kg per minute) for 28 days. Angiotensin II increased the plasma level of double-stranded DNA, an endogenous ligand of TLR 9, in these mice. Genetic deletion or pharmacologic blockade of TLR 9 in angiotensin II-infused Apoe ^-/- mice attenuated atherogenesis in the aortic arch ( P<0.05), reduced the accumulation of lipid and macrophages in atherosclerotic plaques, and decreased RNA expression of inflammatory molecules in the aorta with no alteration of metabolic parameters. On the other hand, restoration of TLR 9 in bone marrow in Tlr9 ^-/- Apoe ^-/- mice promoted atherogenesis in the aortic arch ( P<0.05). A TLR 9 agonist markedly promoted proinflammatory activation of Apoe ^-/- macrophages, partially through p38 mitogen-activated protein kinase signaling. In addition, genomic DNA extracted from macrophages promoted inflammatory molecule expression more effectively in Apoe ^-/- macrophages than in Tlr9 ^-/- Apoe ^-/- macrophages. Furthermore, in humans, circulating double-stranded DNA in the coronary artery positively correlated with inflammatory features of coronary plaques determined by optical coherence tomography in patients with acute myocardial infarction ( P<0.05). Conclusions TLR 9 plays a pivotal role in the development of vascular inflammation and atherogenesis through proinflammatory activation of macrophages. TLR 9 may serve as a potential therapeutic target for atherosclerosis.

Lymphatic Endothelial Cell Junctions: Molecular Regulation in Physiology and Diseases

Lymphatic endothelial cells (LECs) lining lymphatic vessels develop specialized cell-cell junctions that are crucial for the maintenance of vessel integrity and proper lymphatic vascular functions. Successful lymphatic drainage requires a division of labor between lymphatic capillaries that take up lymph via open "button-like" junctions, and collectors that transport lymph to veins, which have tight "zipper-like" junctions that prevent lymph leakage. In recent years, progress has been made in the understanding of these specialized junctions, as a result of the application of state-of-the-art imaging tools and novel transgenic animal models. In this review, we discuss lymphatic development and mechanisms governing junction remodeling between button and zipper-like states in LECs. Understanding lymphatic junction remodeling is important in order to unravel lymphatic drainage regulation in obesity and inflammatory diseases and may pave the way towards future novel therapeutic interventions.

The Role of Notch Signaling in Macrophages during Inflammation and Infection: Implication in Rheumatoid Arthritis?

Notch signaling coordinates numerous cellular processes and has been implicated in many pathological conditions, including rheumatoid arthritis (RA). Although the role of Notch signaling in development, maturation, differentiation, and activation of lymphocytes has been comprehensively reported, less is known about its role in myeloid cells. Certainly, limited data are available about the role of Notch signaling in macrophages during inflammation and infection. In this review, we discuss the recent advances pertaining to the role of Notch signaling in differentiation, activation, and metabolism of macrophages during inflammation and infection. We also highlight the reciprocal interplay between Notch signaling and other signaling pathways in macrophages under different inflammatory and infectious conditions including pathogenesis of RA. Finally, we discuss approaches that could consider Notch signaling as a potential therapeutic target against infection- and inflammation-driven diseases.

Elevated Kallikrein-binding protein in diabetes impairs wound healing through inducing macrophage M1 polarization

Background

The accumulation of M1-polarized macrophages and excessive inflammation are important in the pathogenesis of diabetic foot ulcer (DFU). However, the underlying mechanism of DFU pathogenesis and the crucial regulators of DFU are less well known. Our previous study reported that kallikrein-binding protein (KBP), an angiogenesis inhibitor, was significantly upregulated in diabetic patients compared to its levels in controls. The effects of KBP on monocyte chemotaxis and macrophage M1 polarization were elucidated in this study.

Methods

Plasma KBP levels and monocyte counts were assessed by ELISA and flow cytometry. Wound closure rates in different groups were monitored daily. The phenotype and recruitment of macrophages were measured by real-time PCR, western blot and immunofluorescence assays. The expression of Notch and NF-κB signalling pathway members was determined by the methods mentioned above. ChIP and dual-luciferase reporter gene assays were employed to explore the binding and transcriptional regulation of Hes1 and iNOS.

Results

We found that plasma KBP levels and circulating monocytes were elevated in diabetic patients compared to those in nondiabetic controls, and both were higher in diabetic patients with DFU than in diabetic patients without DFU. KBP delayed wound healing in normal mice; correspondingly, KBP-neutralizing antibody ameliorated delayed wound healing in diabetic mice. Circulating monocytes and macrophage infiltration in the wound were upregulated in KBP-TG mice compared to those in control mice. KBP promoted the recruitment and M1 polarization of macrophages. Mechanistically, KBP upregulated iNOS by activating the Notch1/RBP-Jκ/Hes1 signalling pathway. Hes1 downregulated CYLD, a negative regulator of NF-κB signalling, and then activated the IKK/IκBα/NF-κB signalling pathway.

Conclusions

Our findings demonstrate that KBP is the key regulator of excessive inflammation in DFUs and provide a novel target for DFU therapy.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0376-9) contains supplementary material, which is available to authorized users.

Safe targeting of T cell acute lymphoblastic leukemia by pathology-specific NOTCH inhibition

Given the high frequency of activating NOTCH1 mutations in T cell acute lymphoblastic leukemia (T-ALL), inhibition of the γ-secretase complex remains an attractive target to prevent ligand-independent release of the cytoplasmic tail and oncogenic NOTCH1 signaling. However, four different γ-secretase complexes exist, and available inhibitors block all complexes equally. As a result, these cause severe “on-target” gastrointestinal tract, skin, and thymus toxicity, limiting their therapeutic application. Here, we demonstrate that genetic deletion or pharmacologic inhibition of the presenilin-1 (PSEN1) subclass of γ-secretase complexes is highly effective in decreasing leukemia while avoiding dose-limiting toxicities. Clinically, T-ALL samples were found to selectively express only PSEN1-containing γ-secretase complexes. The conditional knockout of Psen1 in developing T cells attenuated the development of a mutant NOTCH1-driven leukemia in mice in vivo but did not abrogate normal T cell development. Treatment of T-ALL cell lines with the selective PSEN1 inhibitor MRK-560 effectively decreased mutant NOTCH1 processing and led to cell cycle arrest. These observations were extended to T-ALL patient-derived xenografts in vivo, demonstrating that MRK-560 treatment decreases leukemia burden and increased overall survival without any associated gut toxicity. Therefore, PSEN1-selective compounds provide a potential therapeutic strategy for safe and effective targeting of T-ALL and possibly also for other diseases in which NOTCH signaling plays a role.

Notch Signaling Regulates Immune Responses in Atherosclerosis

Atherosclerosis is a chronic autoimmune inflammatory disease that can cause coronary artery disease, stroke, peripheral artery disease, depending on which arteries are affected. At the beginning of atherosclerosis plasma lipoproteins accumulate in the sub-endothelial space. In response, monocytes migrate from the circulation through the endothelium into the intima where they differentiate into macrophages. These early events trigger a complex immune response that eventually involves many cellular subtypes of both innate and adaptive immunity. The Notch signaling pathway is an evolutionary conserved cell signaling system that mediates cell-to-cell communication. Recent studies have revealed that Notch modulate atherosclerosis by controlling macrophages polarization into M1 or M2 subtypes. Furthermore, it is known that Notch signaling controls differentiation and activity of T-helper and cytotoxic T-cells in inflammatory diseases. In this review, we will discuss the role of Notch in modulating immunity in the context of atherosclerosis and whether targeting Notch may represent a therapeutic strategy.

Cannabinoid Receptor 1 Blockade Attenuates Obesity and Adipose Tissue Type 1 Inflammation Through miR-30e-5p Regulation of Delta-Like-4 in Macrophages and Consequently Downregulation of Th1 Cells

Obesity is characterized by chronic low-grade inflammation that contributes to development of cardiometabolic disorders. Cannabinoid receptor 1 (CB1) antagonists attenuate diet-induced obesity (DIO) and related inflammation, although the precise anti-inflammatory mechanisms involved have not been fully explored. In the current study we used a mouse model of DIO intervention to determine the microRNA (miRNA, miR)-mediated anti-obesity and anti-inflammatory effects of the CB1 antagonist, AM251. DIO mice that were fed high-fat diet (HFD) for 12 weeks were treated with AM251 (10 mg/kg) for an additional 4 weeks. HFD + AM251 mice experienced rapid and prolonged weight loss and reduced inflammatory M1 adipose tissue macrophage (ATM) infiltration. To investigate miRNA-mediated regulation of ATMs, F4/80+ cells from stromal vascular fractions (SVF) of epididymal fat were subjected to miR microarray analysis. Several miRs were differentially expressed in AM251-treated mice that were independent of calorie restriction. Prominently, miR-30e-5p was upregulated in ATMs from HFD + AM251 mice while the miR-30e-5p target, DLL4, was downregulated. Consistent with a decrease in DLL4-Notch signaling, fat storage and pro-inflammatory cytokine/chemokine expression was reduced following AM251 treatment. Furthermore, we found that AM251-treated macrophages can suppress DLL4-mediated Th1 polarization in CD4+ T cells. Together these data demonstrate that blocking CB1 receptors leads to upregulation of miR-30e-5p and down regulation of DLL4 in ATMs, which in turn suppress DLL4-Notch signaling-induced polarization of inflammatory Th1 cells and adipocyte energy storage. This combined effect of ATMs and T cells leads to an anti-inflammatory state and attenuation of DIO. These data support therapeutic potential of miR-30 in the treatment of cardiometabolic disorders.

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.