Activated transcription factor nuclear factor-kappa B is present in the atherosclerotic lesion

Regulation of efferocytosis by caspase-dependent apoptotic cell death in atherosclerosis

During the growing process of the atherosclerotic lesions, lipid-filled macrophage foam cells form, accumulate, and ultimately undergo apoptotic death. If the apoptotic foam cells are not timely removed, they may undergo secondary necrosis, and form a necrotic lipid core which renders the plaque unstable and susceptible to rupture. Therefore, the non-lipid-filled fellow macrophages, as the main phagocytic cells in atherosclerotic lesions, need to effectively remove the apoptotic foam cells. In general, in apoptotic macrophages, caspases are the central regulators of several key processes required for their efficient efferocytosis. The processes include the generation of "Find-Me" signals (such as adenosine triphosphate/uridine triphosphate, fractalkine, lysophosphatidylcholine, and sphingosine-1-phosphate) for the recruitment of viable macrophages, generation of the "Eat-Me" signals (for example, phosphatidylserine) for the engulfment process, and, finally, release of anti-inflammatory mediators (including transforming factor β and interleukin-10) as a tolerance-enhancing and an anti-inflammatory response, and for the motile behavior of the apoptotic cell. The caspase-dependent mechanisms are operative also in apoptotic macrophages driving the atherogenesis. In this review, we explore the role of the molecular pathways related to the caspase-dependent events in efferocytosis in the context of atherosclerosis. Understanding of the molecular mechanisms of apoptotic cell death in atherosclerotic lesions is essential when searching for new leads to treat atherosclerosis.

Ficus deltoidea suppresses endothelial activation, inflammation, monocytes adhesion and oxidative stress via NF-κB and eNOS pathways in stimulated human coronary artery endothelial cells

Background

Ficus deltoidea (FD) has been shown to have antidiabetic, anti-inflammatory, antinociceptive and antioxidant properties. However, its effects on key events in the pathogenesis of atherosclerosis are unknown.

Aim

To investigate the endothelial activation, inflammation, monocyte-endothelial cell binding and oxidative stress effects of four FD varieties.

Methods

Human coronary artery endothelial cells (HCAEC) were incubated with different concentrations of aqueous ethanolic extracts of FD var. trengganuensis (FDT), var. kunstleri (FDK), var. deltoidea (FDD) and var. intermedia (FDI), together with LPS. Protein and gene expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular cell adhesion molecule-1 (ICAM-1), endothelial-leukocyte adhesion molecule-1 (E-selectin), interleukin-6 (IL-6), Nuclear factor-κB (NF-κB) p50 and p65 and endothelial nitric oxide synthase (eNOS) were measured using ELISA and QuantiGene plex, respectively. Adhesion of monocyte to HCAEC and formation of reactive oxygen species (ROS) were detected by Rose Bengal staining and 2′-7′-dichlorofluorescein diacetate (DCFH-DA) assay.

Results

FDK exhibited the highest inhibition of biomarkers in relation to endothelial activation and inflammation, second in reducing monocyte binding (17.3%) compared to other varieties. FDK (25.6%) was also the most potent at decreasing ROS production.

Conclusion

FD has anti-atherogenic effects, possibly mediated by NF-κB and eNOS pathways; with FDK being the most potent variety. It is potentially beneficial in mitigating atherogenesis.

Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK)/Fibroblast Growth Factor-Inducible 14 (Fn14) Axis in Cardiovascular Diseases: Progress and Challenges

Cardiovascular diseases (CVD) are the leading cause of mortality in Western countries. CVD include several pathologies, such as coronary artery disease, stroke, peripheral artery disease, and aortic aneurysm, among others. All of them are characterized by a pathological vascular remodeling in which inflammation plays a key role. Interaction between different members of the tumor necrosis factor superfamily and their cognate receptors induce several biological actions that may participate in CVD. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its functional receptor, fibroblast growth factor-inducible 14 (Fn14), are abundantly expressed during pathological cardiovascular remodeling. The TWEAK/Fn14 axis controls a variety of cellular functions, such as proliferation, differentiation, and apoptosis, and has several biological functions, such as inflammation and fibrosis that are linked to CVD. It has been demonstrated that persistent TWEAK/Fn14 activation is involved in both vessel and heart remodeling associated with acute and chronic CVD. In this review, we summarized the role of the TWEAK/Fn14 axis during pathological cardiovascular remodeling, highlighting the cellular components and the signaling pathways that are involved in these processes.

Effect of Sudharshan Kriya Pranayama on Salivary Expression of Human Beta Defensin-2, Peroxisome Proliferator-Activated Receptor Gamma, and Nuclear Factor-Kappa B in Chronic Periodontitis

Introduction

Sudharshan kriya pranayama (SKP) is a form of yoga that reduces inflammation and contributes to general health. Very few prior studies have examined the role of pranayama on oral health. We evaluated the clinical status and inflammatory biomarkers in patients with chronic periodontitis before and after SKP.

Materials and methods

Ninety male subjects were considered for the study and divided into three groups: subjects with a healthy periodontium (Group1), subjects with chronic gingivitis (Group2), and subjects with chronic periodontitis (Group3). The clinical parameters included plaque index (PI), gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL), and salivary markers human beta-defensin-2(HBD-2), peroxisome proliferator-activated receptor gamma (PPAR-γ), and nuclear factor-kappa B (NF-κB). These parameters and markers were evaluated before and after 90 days of SKP. The data obtained were statistically evaluated by McNemar's test, paired sample t-test, and one-way analysis of variance.

Results

There was a significant improvement in PI in all three groups. GI showed an improvement in Groups 2 and 3. PPD and CAL also showed an improvement in Group 3. HBD-2 and NF-κB decreased with SKP, whereas PPAR-γ expression increased after the intervention. In Groups 2 and 3 with the decrease in GI, there was a corresponding decrease in HBD-2. In Group 3 with an improvement in PPD and CAL, there was an improvement in PPAR-γ expression.

Conclusions

The results show that SKP can significantly decrease periodontal inflammation and improve periodontal status. It also effectively improves the expression of PPAR-γ, thereby decreasing salivary levels of HBD-2 and NF-κB, respectively. Based on our results, pranayama can be an effective adjunct in maintaining oral health.

Neutrophil microvesicles drive atherosclerosis by delivering miR-155 to atheroprone endothelium

Neutrophils are implicated in the pathogenesis of atherosclerosis but are seldom detected in atherosclerotic plaques. We investigated whether neutrophil-derived microvesicles may influence arterial pathophysiology. Here we report that levels of circulating neutrophil microvesicles are enhanced by exposure to a high fat diet, a known risk factor for atherosclerosis. Neutrophil microvesicles accumulate at disease-prone regions of arteries exposed to disturbed flow patterns, and promote vascular inflammation and atherosclerosis in a murine model. Using cultured endothelial cells exposed to disturbed flow, we demonstrate that neutrophil microvesicles promote inflammatory gene expression by delivering miR-155, enhancing NF-κB activation. Similarly, neutrophil microvesicles increase miR-155 and enhance NF-κB at disease-prone sites of disturbed flow in vivo. Enhancement of atherosclerotic plaque formation and increase in macrophage content by neutrophil microvesicles is dependent on miR-155. We conclude that neutrophils contribute to vascular inflammation and atherogenesis through delivery of microvesicles carrying miR-155 to disease-prone regions.

Molecular Signature of the Immune Response to Yoga Therapy in Stress-related Chronic Disease Conditions: An Insight

The world Health Organization defines health as complete well-being in terms of physical, mental and social, and not merely the absence of disease. To attain this, individual should adapt and self-mange the social, physical and emotional challenges of life. Exposure to chronic stress due to urbanization, work stress, nuclear family, pollution, unhealthy food habits, lifestyle, accidental death in the family, and natural calamities are the triggering factors, leading to hormonal imbalance and inflammation in the tissue. The relationship between stress and illness is complex; all chronic illnesses such as cardiovascular disease and asthma have their root in chronic stress attributed by inflammation. In recent times, yoga therapy has emerged as an important complementary alternative medicine for many human diseases. Yoga therapy has a positive impact on mind and body; it acts by incorporating appropriate breathing techniques and mindfulness to attain conscious direction of our awareness of the present moment by meditation, which helps achieve harmony between the body and mind. Studies have also demonstrated the important regulatory effects of yoga therapy on brain structure and functions. Despite these advances, the cellular and molecular mechanisms by which yoga therapy renders its beneficial effects are inadequately known. A growing body of evidence suggests that yoga therapy has immunomodulatory effects. However, the precise mechanistic basis has not been addressed empirically. In this review, we have attempted to highlight the effect of yoga therapy on immune system functioning with an aim to identify important immunological signatures that index the effect of yoga therapy. Toward this, we have summarized the available scientific evidence showing positive impacts of yoga therapy. Finally, we have emphasized the efficacy of yoga in improving physical and mental well-being. Yoga has been a part of Indian culture and tradition for long; now, the time has come to scientifically validate this and implement this as an alternative treatment method for stress-related chronic disease.

Etlingera pavieana extract attenuates TNF-α induced vascular adhesion molecule expression in human endothelial cells through NF-κB and Akt/JNK pathways

The aim of this study was to determine whether ethanol extracts of Etlingera pavieana rhizomes (EPE) can inhibit the expression of ICAM-1 and VCAM-1 in TNF-α-stimulated human vascular endothelial cells. EPE significantly reduced ICAM-1 and VCAM-1 expression in a concentration-dependent manner. EPE also suppressed phospho-IκB level and nuclear translocation of NF-κB. EPE significantly inhibited phosphorylation of JNK and c-Jun, a major component of AP-1, but had no effects on ERK and p38 MAPK pathways. Akt phosphorylation was increased in the presence of EPE, and wortmannin and SP600125 reversed the inhibitory effects of EPE on ICAM-1 and VCAM-1 expression. Furthermore, the active EPE constituents 4-methoxycinnamyl p-coumarate and trans-4-methoxycinnamaldehyde attenuated TNF-α-induced expression of ICAM-1 and VCAM-1. Taken together, our data indicate that EPE protects against vascular inflammation in endothelial cells, in part via NF-κB and Akt/JNK signalings. In future studies, E. pavieana may be developed as a therapeutic agent or dietary supplement for treating and preventing inflammatory diseases.

Intermittent hypoxia and hypercapnia induces inhibitor of nuclear factor-κB kinase subunit β-dependent atherosclerosis in pulmonary arteries

Clinical studies have shown that obstructive sleep apnea (OSA) increases atherosclerosis risk. The inflammation, especially mediated by the macrophages via nuclear factor-κB (NF-κB), has been speculated to contribute to atherogenicity in OSA patients. Inhibitor of NF-κB kinase-β (IKKβ) is an essential element of the NF-κB pathway and is linked to atherosclerosis. We previously reported that atherosclerosis was accelerated in pulmonary artery (PA) but not in aorta when low-density lipoprotein receptor knockout (Ldlr-/-) mice were exposed to intermittent hypoxia/hypercapnia (IHH), a surrogate for recurrent upper-airway obstruction. Therefore, we hypothesized that IKKβ-dependent NF-κB activation in monocytes and macrophages plays a role in IHH-induced PA atherosclerosis. To test this hypothesis, myeloid restricted IKKβ deletion (IkkβΔMye) or control (IkkβF/F) mice were crossed with Ldlr-/- mice to generate double-knockout mice. Then, the mice were exposed to IHH or room air (Air) on high-fat diet for 8 or 16 wk. Lesions of PA and aorta were examined in IkkβΔMye;Ldlr-/- and IkkβF/F;Ldlr-/- male mice under IHH vs. Air. The results revealed that IKKβ deletion abolished IHH-induced PA atherosclerosis after 8-wk exposure but not after 16-wk exposure (8 wk: IkkβF/F;Ldlr-/-, IHH 13.5 ± 1.4 vs. Air 5.7 ± 0.7%, P < 0.01; IkkβΔMye;Ldlr-/-, IHH 7.4 ± 1.9% vs. Air 4.6 ± 1.3%, P = 0.24). Both IKKβ deletion and IHH had no effects on atherosclerosis in the aorta. Our findings demonstrate that IKKβ-dependent NF-κB activity in myeloid-lineage cells plays a critical role in IHH-induced PA atherosclerosis at the early stage.

Hexarelin attenuates atherosclerosis via inhibiting LOX-1-NF-κB signaling pathway-mediated macrophage ox-LDL uptake in ApoE-/- mice

Growth hormone secretagogues (GHS) have been proved to exert protective effects on the cardiovascular system, while their potential beneficial effects on macrophages in atherosclerosis (AS) are rarely been clarified. This study aimed to demonstrate whether hexarelin, a synthetic peptidyl GHS, can suppress AS progression via regulating the function of macrophages. AS was induced by chronic (3 months) feeding with high lipid diet in ApoE^-/- mice. Mice were treated either with hexarelin (100 μg/kg s.c., q.d. for 3 months) (AS + Hex group) or saline (AS group). Age-matched C57BL/6 J mice were used as normal controls. AS and related signaling molecules in aortic tissues and RAW264.7 macrophages were identified with variant methods including histological staining, ELISA, western blotting, confocal microscopy and flow cytometry. AS significantly developed in ApoE^-/- mice fed with high lipids diet. Hexarelin decreased serum TC, TG and LDL-c, increased serum HDL-c and attenuated the formation of atherosclerotic plaques and neointima compared with the AS group. Hexarelin decreased the aortic expressions of CD68 and LOX-1 which were elevated in the AS group. Hexarelin increased GHSR expression, suppressed ox-LDL uptake and LOX-1 expression and inhibited nuclear factor-kappa B (NF-κB) activation both in the aorta of ApoE^-/- mice and in RAW264.7 macrophages. We conclude that hexarelin effectively attenuates AS progression in ApoE^-/- mice by modulating circulatory lipids profile and inhibiting macrophage ox-LDL uptake via suppressing the LOX-1-NF-κB signaling pathway. The study supports the perspective of hexarelin as an anti-AS drug.

[Role of PPARγ, a transcription factor in cardiovascular disease]

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand activated transcription factor known to regulate fatty acid metabolism. Thiazolidinediones (TZDs), PPARγ synthetic agonists, currently used to treat patients with type 2 diabetes, have been shown to lower the blood pressure and protect against vascular diseases such as atherosclerosis. In line with these findings, it has been reported that individuals with loss-of-function mutations of PPARγ developed sever early-onset hypertension in addition to metabolic abnormalities. Accumulating evidences suggest PPARγ in the vasculature has protective effects on cardiovascular disease despite unclear mechanism. Because of ubiquitous expression of PPARγ, TZDs are well-known to be associated with serious side effects such as weight gain, fluid retention, and bone fractures. Thus identification of mechanisms on tissue-specific PPARγ activity may lead to the development of targeted treatment which is characterized by no deleterious effects. This review discusses role of PPARγ in cardiovascular disease.

Allograft inflammatory factor-1 supports macrophage survival and efferocytosis and limits necrosis in atherosclerotic plaques

BACKGROUND AND AIMS

Allograft inflammatory factor-1 (AIF1) has been characterized as a pro-inflammatory molecule expressed primarily in the monocyte/macrophage (MP) lineage and positively associated with various forms of vascular disease, including atherosclerosis. Studies of AIF1 in atherosclerosis have relied on mouse models in which AIF1 was overexpressed in either myeloid or smooth muscle cells, resulting in increased atherosclerotic plaque burden. How physiologic expression of AIF1 contributes to MP biology in atherogenesis is not known.

METHODS

Effects of global AIF1 deficiency on atherosclerosis were assessed by crossing Aif1^-/- and ApoE^-/- mice, and provoking hyperlipidemia with high fat diet feeding. Atherosclerotic plaques were studied en face and in cross section. Bone marrow-derived MPs (BMDMs) were isolated from Aif1^-/- mice for study in culture.

RESULTS

Atherosclerotic plaques in Aif1^-/-;ApoE^-/- mice showed larger necrotic cores compared to those in ApoE^-/- animals, without change in overall lesion burden. In vitro, lack of AIF1 reduced BMDM survival, phagocytosis, and efferocytosis. Mechanistically, AIF1 supported activation of the NF-κB pathway and expression of related target genes involved in stress response, inflammation, and apoptosis. Consistent with this in vitro BMDM phenotype, AIF1 deficiency reduced NF-κB pathway activity in vivo and increased apoptotic cell number in atherosclerotic lesions from Aif1^-/-;ApoE^-/- mice.

CONCLUSIONS

These findings characterize AIF1 as a positive regulator of the NF-κB pathway that supports MP functions such as survival and efferocytosis. In inflammatory settings such as atherosclerosis, these AIF1-dependent activities serve to clear cellular and other debris and limit necrotic core expansion, and may oppose lesion destabilization.

Deficiency of Adipocyte IKKβ Affects Atherosclerotic Plaque Vulnerability in Obese LDLR Deficient Mice

Background

Obesity‐associated chronic inflammation has been known to contribute to atherosclerosis development, but the underlying mechanisms remain elusive. Recent studies have revealed novel functions of IKKβ (inhibitor of NF‐κB [nuclear factor κB] kinase β), a key coordinator of inflammation through activation of NF‐κB, in atherosclerosis and adipose tissue development. However, it is not clear whether IKKβ signaling in adipocytes can also affect atherogenesis. This study aims to investigate the impact of adipocyte IKKβ expression on atherosclerosis development in lean and obese LDLR (low‐density lipoprotein receptor)–deficient (LDLR^−/−) mice.

Methods and Results

To define the role of adipocyte IKKβ in atherogenesis, we generated adipocyte‐specific IKKβ‐deficient LDLR^−/− (IKKβ^ΔAdLDLR^−/−) mice. Targeted deletion of IKKβ in adipocytes did not affect adiposity and atherosclerosis in lean LDLR^−/− mice when fed a low‐fat diet. In response to high‐fat feeding, however, IKKβ^ΔAdLDLR^−/− mice had defective adipose remodeling and increased adipose tissue and systemic inflammation. Deficiency of adipocyte IKKβ did not affect atherosclerotic lesion sizes but resulted in enhanced lesional inflammation and increased plaque vulnerability in obese IKKβ^ΔAdLDLR^−/− mice.

Conclusions

These data demonstrate that adipocyte IKKβ signaling affects the evolution of atherosclerosis plaque vulnerability in obese LDLR^−/− mice. This study suggests that the functions of IKKβ signaling in atherogenesis are complex, and IKKβ in different cell types or tissues may have different effects on atherosclerosis development.

Angiotensin II Increases Endoplasmic Reticulum Stress in Adipose Tissue and Adipocytes

The Renin Angiotensin System (RAS), a key regulator of blood pressure has been linked to metabolic disorders. We have previously reported that adipose overexpression of angiotensinogen in mice (Agt-Tg) induces obesity, in part mediated by adipose tissue inflammation, through yet unidentified mechanisms. Hence, we hypothesize that adipose tissue enrichment of angiotensinogen leads to activation of inflammatory cascades and endoplasmic reticulum (ER) stress, thereby, contributing to obesity. We used wild type (Wt), Agt-Tg and Agt-knockout (KO) mice along with 3T3-L1 and human adipocytes treated with RAS, ER stress and inflammation inhibitors. ER stress and pro-inflammation markers were significantly higher in Agt-Tg compared to Wt mice and captopril significantly reduced their expression. Furthermore, in vitro treatment with Ang II significantly induced ER stress and inflammation, whereas angiotensin II receptor inhibitor, telmisartan reduced RAS effects. Moreover, miR-30 family had significantly lower expression in Agt-Tg group. MiR-708-5p and -143-3p were upregulated when RAS was overexpressed, and RAS antagonists reduced miR-143-3p and -708-5p in both mouse adipose tissue and adipocytes. Activation of RAS by Ang II treatment, increased inflammation and ER stress in adipocytes mainly via AT1 receptor, possibly mediated by miR-30 family, -708-5p and/or -143-3p. Hence, RAS and mediating microRNAs could be used as potential targets to reduce RAS induced obesity and related comorbid diseases.

Role of the COP9 Signalosome (CSN) in Cardiovascular Diseases

The constitutive photomorphogenesis 9 (COP9) signalosome (CSN) is an evolutionarily conserved multi-protein complex, consisting of eight subunits termed CSN1-CSN8. The main biochemical function of the CSN is the control of protein degradation via the ubiquitin-proteasome-system through regulation of cullin-RING E3-ligase (CRL) activity by deNEDDylation of cullins, but the CSN also serves as a docking platform for signaling proteins. The catalytic deNEDDylase (isopeptidase) activity of the complex is executed by CSN5, but only efficiently occurs in the three-dimensional architectural context of the complex. Due to its positioning in a central cellular pathway connected to cell responses such as cell-cycle, proliferation, and signaling, the CSN has been implicated in several human diseases, with most evidence available for a role in cancer. However, emerging evidence also suggests that the CSN is involved in inflammation and cardiovascular diseases. This is both due to its role in controlling CRLs, regulating components of key inflammatory pathways such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and complex-independent interactions of subunits such as CSN5 with inflammatory proteins. In this case, we summarize and discuss studies suggesting that the CSN may have a key role in cardiovascular diseases such as atherosclerosis and heart failure. We discuss the implicated molecular mechanisms ranging from inflammatory NF-κB signaling to proteotoxicity and necrosis, covering disease-relevant cell types such as myeloid and endothelial cells or cardiomyocytes. While the CSN is considered to be disease-exacerbating in most cancer entities, the cardiovascular studies suggest potent protective activities in the vasculature and heart. The underlying mechanisms and potential therapeutic avenues will be critically discussed.

Catalpol Inhibits Homocysteine-induced Oxidation and Inflammation via Inhibiting Nox4/NF-κB and GRP78/PERK Pathways in Human Aorta Endothelial Cells

Hyperhomocysteinemia (HHCY) has been recognized as an independent risk factor for atherosclerosis and plays a vital role in the development of atherosclerosis. Catalpol, an iridoid glucoside extracted from the root of Rehmannia glutinosa, can produce anti-inflammatory, anti-oxidant, anti-tumor, and dopaminergic neurons protecting effects. This study aimed to determine the protecting effects of catalpol against homocysteine (HCY)-induced injuries in human aortic endothelial cells (HAECs) and uncover the underlying mechanisms: 1. HAECs were cultured with different concentrations of HCY (3 mM) and catalpol (7.5 μΜ, 15 μΜ, 30 μΜ) for 24 h. (1) The level of MDA and GSH as well as LDH release was measured with colorimetric assay. (2) Reactive oxygen species (ROS) were detected by flow cytometry analysis. (3) Western blotting analysis was performed to detect the expression of Nox4, p22^phox, ICAM-1, MCP-1, VCAM-1, IκB, nucleus p65, p65 phosphorylation, caspase-3, −9, bax, bcl-2, and ER stress-related proteins. (4) The expressions of CHOP, ATF4 were measured by qRT-PCR. (5) Mitochondrial membrane potential in HCY-treated HAECs was measured by rhodamine 123 staining, and the samples were observed by confocal laser scanning microscopy. 2. DPI, PDTC, and TUDCA were used to determine the interaction among Nox4/ROS, NF-κB, and endoplasmic reticulum stress. 3. TUDCA or Nox4 siRNA were used to investigate whether the effect of catalpol inhibiting the over-production of ROS were associated with inhibiting ER stress and Nox4 expression. Catalpol significantly suppressed LDH release, MDA level, and the reduction of GSH. Catalpol reduced HCY-stimulated ROS over-generation, inhibited the NF-κB transcriptional activation as well as the protein over-expressions of Nox4, ICAM-1, VCAM-1, and MCP-1. Catalpol elevated bcl-2 protein expression and reduced bax, caspase-3, −9 protein expressions in the HCY-treated HAECs. Simultaneously, catalpol could also inhibit the activation of ER stress-associated sensors GRP78, IRE1α, ATF6, P-PERK, P-eIF2α, CHOP, and ATF4 induced by HCY. In addition, the extent of catalpol inhibiting ROS over-generation and NF-κB signaling pathway was reduced after inhibiting Nox4 or ER stress with DPI or TUDCA. The inhibitor of NF-κB PDTC also reduced the effects of catalpol inhibiting the expressions of Nox4 and GRP78. Furthermore, the effect of catalpol inhibiting the over-generation of ROS was reduced by Nox4 siRNA. Catalpol could ameliorate HCY-induced oxidation, cells apoptosis and inflammation in HAECs possibly by inhibiting Nox4/NF-κB and ER stress.

Lack of IκBNS promotes cholate-containing high-fat diet-induced inflammation and atherogenesis in low-density lipoprotein (LDL) receptor-deficient mice

Background

IκBNS, a nuclear IκB protein, regulates a subset of Toll-like receptor (TLR) dependent genes. A cholate-containing high-fat diet (HFD(CA(+))) induces TLR4 mediated early inflammatory response. The present study aims to clarify that the lack of IκBNS promotes atherogenesis in low-density lipoprotein receptor-deficient (LDLr^−/−) mice fed HFD(CA(+)) compared with those fed a cholate-free HFD (HFD(CA(−))).

Methods and results

Mice that lacked IκBNS (IκBNS^−/−) were crossed with LDLr^−/− mice and formation of atherosclerotic lesions was analyzed after 6-week consumption of HFD(CA(+)) or HFD(CA(−)). IκBNS^−/−/LDLr^−/− mice fed HFD(CA(+)) (IκBNS^−/−/LDLr^−/−(CA(+))) showed a 3.5-fold increase of atherosclerotic lesion size in the aorta compared with LDLr^−/−(CA(+)) mice (p < 0.01), whereas there was no difference between LDLr^−/−(CA(−)) and IκBNS^−/−/LDLr^−/−(CA(−)) mice. Immunohistochemical analysis of the aortic root revealed that HFD(CA(+)) significantly increased Mac-3 (macrophage)-positive area by 1.5-fold (p < 0.01) and TLR4, interleukin-6 (IL-6) expression by 1.7-fold (p < 0.05) and 1.5-fold (p < 0.05), respectively, in IκBNS^−/−/LDLr^−/−(CA(+)) compared with LDLr^-/-−−(CA(+)) mice. Furthermore, active STAT3 (pSTAT3)-positive cells were significantly increased by 1.7-fold in the lesions of IκBNS^−/−/LDLr^−/−(CA(+)) compared with LDLr^−/−(CA(+)) mice (p < 0.01). These findings suggest that IκBNS deficiency and HFD(CA(+)) promote atherogenesis in LDLr^−/− mice via TLR4/IL-6/STAT3 pathway. Finally, we showed that the monocytes from peripheral blood of IκBNS^−/−/LDLr^−/−(CA(+)) mice were found to contain the highest proportion of Ly6C^hi monocytes among the four groups, suggesting that lack of IκBNS enhanced inflammation in response to HFD(CA(+)) feeding.

Conclusions

The present study is the first to demonstrate that the activation of innate immune system using HFD(CA(+)) induced significant inflammation and atherogenesis in IκBNS^−/−/LDLr^−/− compared with LDLr^−/− mice.

The Role of Monocytes and Macrophages in Human Atherosclerosis, Plaque Neoangiogenesis, and Atherothrombosis

Atherosclerosis is one of the leading causes of death and disability worldwide. It is a complex disease characterized by lipid accumulation within the arterial wall, inflammation, local neoangiogenesis, and apoptosis. Innate immune effectors, in particular monocytes and macrophages, play a pivotal role in atherosclerosis initiation and progression. Although most of available evidence on the role of monocytes and macrophages in atherosclerosis is derived from animal studies, a growing body of evidence elucidating the role of these mononuclear cell subtypes in human atherosclerosis is currently accumulating. A novel pathogenic role of monocytes and macrophages in terms of atherosclerosis initiation and progression, in particular concerning the role of these cell subsets in neovascularization, has been discovered. The aim of the present article is to review currently available evidence on the role of monocytes and macrophages in human atherosclerosis and in relation to plaque characteristics, such as plaque neoangiogenesis, and patients' prognosis and their potential role as biomarkers.

Cholesterol crystals promote endothelial cell and monocyte interactions via H2O2-mediated PP2A inhibition, NFκB activation and ICAM1 and VCAM1 expression

In the present study, we show that cholesterol crystals induce NFκB activation, and ICAM1 and VCAM1 expression via xanthine oxidase-mediated H₂O₂ production and PP2A inhibition in influencing endothelial cell and monocyte interactions and all these adverse effects of cholesterol crystals could be attenuated by proresolving lipid mediator RvD1. In addition, feeding mice with cholesterol rich diet (CRD) increased xanthine oxidase expression, its activity and H₂O₂ production leading to PP2A inhibition, NFκB activation, and ICAM1 and VCAM1 expression and RvD1 attenuated all these effects of CRD substantially. Furthermore, peripheral blood mononuclear cells (PBMCs) from wild type mice when injected into mice that were fed with CRD or RvD1 + CRD showed increased leukocyte trafficking to arteries of CRD-fed mice as compared to RvD1 + CRD mice. These findings suggest that cholesterol crystals via promoting oxidant stress and inhibiting Ser/Thr phosphatases such as PP2A stimulate NFκB activation and ICAM1 and VCAM1 expression, and thereby enhance EC-monocyte interactions. In addition, proresolving lipid mediators such as RvD1 appear to exert their anti-inflammatory effects via countering the adverse effects of cholesterol crystals or CRD.

Modeling CADASIL vascular pathologies with patient-derived induced pluripotent stem cells

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare hereditary cerebrovascular disease caused by a NOTCH3 mutation. However, the underlying cellular and molecular mechanisms remain unidentified. Here, we generated non-integrative induced pluripotent stem cells (iPSCs) from fibroblasts of a CADASIL patient harboring a heterozygous NOTCH3 mutation (c.3226C>T, p.R1076C). Vascular smooth muscle cells (VSMCs) differentiated from CADASIL-specific iPSCs showed gene expression changes associated with disease phenotypes, including activation of the NOTCH and NF-κB signaling pathway, cytoskeleton disorganization, and excessive cell proliferation. In comparison, these abnormalities were not observed in vascular endothelial cells (VECs) derived from the patient's iPSCs. Importantly, the abnormal upregulation of NF-κB target genes in CADASIL VSMCs was diminished by a NOTCH pathway inhibitor, providing a potential therapeutic strategy for CADASIL. Overall, using this iPSC-based disease model, our study identified clues for studying the pathogenic mechanisms of CADASIL and developing treatment strategies for this disease.

Shear-Induced CCN1 Promotes Atheroprone Endothelial Phenotypes and Atherosclerosis

BACKGROUND

Atherosclerosis occurs preferentially at the blood vessels encountering blood flow turbulence. The matricellular protein CCN1 is induced in endothelial cells by disturbed flow, and is expressed in advanced atherosclerotic lesions in patients and in the Apoe^-/- mouse model. The role of CCN1 in atherosclerosis remains undefined.

METHODS

To assess the function of CCN1 in vivo, knock-in mice carrying the integrin α6β1-binding-defective mutant allele Ccn1-dm on the Apoe^-/- background were tested in an atherosclerosis model generated by carotid artery ligation. Additionally, CCN1-regulated functional phenotypes of human umbilical vein endothelial cells, or primary mouse aortic endothelial cells isolated from wild-type and Ccn1 ^dm/dm mice, were investigated in the in vitro shear stress experiments under unidirectional laminar shear stress (12 dyn/cm²) versus oscillatory shear stress (±5 dyn/cm²) conditions.

RESULTS

We found that Ccn1 expression was upregulated in the arterial endothelium 3 days after ligation before any detectable structural changes, and intensified with the progression of atherosclerotic lesions. Compared with Apoe^-/- controls, Ccn1 ^dm/dm/ Apoe^-/- mice were remarkably resistant to ligation-induced plaque formation (n=6). These mice exhibited lower oxidative stress, expression of endothelin-1 and monocyte chemoattractant protein-1, and monocyte homing. CCN1/α6β1 critically mediated flow-induced activation of the pleiotropic transcription factor nuclear factor-κB and therefore the induction of atheroprone gene expression in the mouse arterial endothelium after ligation (n=6), or in cultured human umbilical vein endothelial cells or primary mouse aortic endothelial cells exposed to oscillatory shear stress (n=3 in triplicate). Interestingly, the activation of nuclear factor-κB by CCN1/α6β1 signaling prompted more production of CCN1 and α6β1. Blocking CCN1-α6β1 binding by the Ccn1-dm mutation or by T1 peptide (derived from an α6β1-binding sequence of CCN1) disrupted the positive-feedback regulation between CCN1/α6β1 and nuclear factor-κB, and prevented flow-induced atheroprone phenotypic alterations in endothelial cells or atherosclerosis in mice.

CONCLUSIONS

These data demonstrate a causative role of CCN1 in atherosclerosis via modulating endothelial phenotypes. CCN1 binds to its receptor integrin α6β1 to activate nuclear factor-κB, thereby instigating a vicious circle to persistently promote atherogenesis. T1, a peptide antagonist selectively targeting CCN1-α6β1, can be further optimized for developing T1-mimetics to treat atherosclerosis.

NF-κB-responsive miR-155 induces functional impairment of vascular smooth muscle cells by downregulating soluble guanylyl cyclase

Vascular smooth muscle cells (VSMCs) play an important role in maintaining vascular function. Inflammation-mediated VSMC dysfunction leads to atherosclerotic intimal hyperplasia and preeclamptic hypertension; however, the underlying mechanisms are not clearly understood. We analyzed the expression levels of microRNA-155 (miR-155) in cultured VSMCs, mouse vessels, and clinical specimens and then assessed its role in VSMC function. Treatment with tumor necrosis factor-α (TNF-α) elevated miR-155 biogenesis in cultured VSMCs and vessel segments, which was prevented by NF-κB inhibition. MiR-155 expression was also increased in high-fat diet-fed ApoE^−/− mice and in patients with atherosclerosis and preeclampsia. The miR-155 levels were inversely correlated with soluble guanylyl cyclase β1 (sGCβ1) expression and nitric oxide (NO)-dependent cGMP production through targeting the sGCβ1 transcript. TNF-α-induced miR-155 caused VSMC phenotypic switching, which was confirmed by the downregulation of VSMC-specific marker genes, suppression of cell proliferation and migration, alterations in cell morphology, and NO-induced vasorelaxation. These events were mitigated by miR-155 inhibition. Moreover, TNF-α did not cause VSMC phenotypic modulation and limit NO-induced vasodilation in aortic vessels of miR-155^−/− mice. These findings suggest that NF-κB-induced miR-155 impairs the VSMC contractile phenotype and NO-mediated vasorelaxation by downregulating sGCβ1 expression. These data suggest that NF-κB-responsive miR-155 is a novel negative regulator of VSMC functions by impairing the sGC/cGMP pathway, which is essential for maintaining the VSMC contractile phenotype and vasorelaxation, offering a new therapeutic target for the treatment of atherosclerosis and preeclampsia.

The overexpression of a microRNA molecule adversely affects the functioning of vascular smooth muscle cells (VSMCs) and may contribute to the development of artherosclerosis and preeclampsia. The interactions between VSMCs and the cells lining blood vessels (endothelium) are crucial for maintaining the healthy phenotype and relaxation of blood vessels. Disruption to these interactions via inflammation, for example, can trigger serious vascular diseases. Young-Myeong Kim at Kangwon National University, Chungcheon, South Korea, and co-workers demonstrated that expression levels of a microRNA-155 are elevated in patients with artherosclerosis and preeclampsia, while an enzyme found in VSMCs called soluble guanylyl cyclase is considerably reduced. Using human and mice tissues, the team showed that miR-155 impairs the contractile phenotype and relaxation of VSMCs by reducing guanylyl cyclase expression. Their findings may inform new therapies for vascular diseases.

M2b macrophage polarization and its roles in diseases

Macrophages play an important role in a wide variety of physiologic and pathologic processes. Plasticity and functional polarization are hallmarks of macrophages. Macrophages commonly exist in two distinct subsets: classically activated macrophages (M1) and alternatively activated macrophages (M2). M2b, a subtype of M2 macrophages, has attracted increasing attention over the past decade due to its strong immune‐regulated and anti‐inflammatory effects. A wide variety of stimuli and multiple factors modulate M2b macrophage polarization in vitro and in vivo. M2b macrophages possess both protective and pathogenic roles in various diseases. Understanding the mechanisms of M2b macrophage activation and the modulation of their polarization might provide a great perspective for the design of novel therapeutic strategies. The purpose of this review is to discuss current knowledge of M2b macrophage polarization, the roles of M2b macrophages in a variety of diseases and the stimuli to modulate M2b macrophage polarization.

Anti-GRP78 autoantibodies induce endothelial cell activation and accelerate the development of atherosclerotic lesions

The 78-kDa glucose-regulated protein (GRP78) is an ER molecular chaperone that aids in protein folding and secretion. However, pathological conditions that cause ER stress can promote the relocalization of GRP78 to the cell surface (csGRP78), where it acts as a signaling receptor to promote cancer progression. csGRP78 also possesses antigenic properties, leading to the production of anti-GRP78 autoantibodies, which contribute to tumor growth. In contrast, the presence and role of anti-GRP78 autoantibodies in atherosclerosis is unknown. Here, we show that atherosclerotic-prone ApoE-/- mice develop circulating anti-GRP78 autoantibodies that bind to csGRP78 on lesion-resident endothelial cells. Moreover, GRP78-immunized ApoE-/- mice exhibit a marked increase in circulating anti-GRP78 autoantibody titers that correlated with accelerated lesion growth. Mechanistically, engagement of anti-GRP78 autoantibodies with csGRP78 on human endothelial cells activated NF-κB, thereby inducing the expression of ICAM-1 and VCAM-1, a process blocked by NF-κB inhibitors. Disrupting the autoantibody/csGRP78 complex with enoxaparin, a low-molecular-weight heparin, reduced the expression of adhesion molecules and attenuated lesion growth. In conclusion, anti-GRP78 autoantibodies play a crucial role in atherosclerosis development, and disruption of the interaction between anti-GRP78 autoantibodies and csGRP78 represents a therapeutic strategy.

CRISPR/Cas9-mediated gene knockout reveals a guardian role of NF-κB/RelA in maintaining the homeostasis of human vascular cells

Vascular cell functionality is critical to blood vessel homeostasis. Constitutive NF-κB activation in vascular cells results in chronic vascular inflammation, leading to various cardiovascular diseases. However, how NF-κB regulates human blood vessel homeostasis remains largely elusive. Here, using CRISPR/Cas9-mediated gene editing, we generated RelA knockout human embryonic stem cells (hESCs) and differentiated them into various vascular cell derivatives to study how NF-κB modulates human vascular cells under basal and inflammatory conditions. Multi-dimensional phenotypic assessments and transcriptomic analyses revealed that RelA deficiency affected vascular cells via modulating inflammation, survival, vasculogenesis, cell differentiation and extracellular matrix organization in a cell type-specific manner under basal condition, and that RelA protected vascular cells against apoptosis and modulated vascular inflammatory response upon tumor necrosis factor α (TNFα) stimulation. Lastly, further evaluation of gene expression patterns in IκBα knockout vascular cells demonstrated that IκBα acted largely independent of RelA signaling. Taken together, our data reveal a protective role of NF-κB/RelA in modulating human blood vessel homeostasis and map the human vascular transcriptomic landscapes for the discovery of novel therapeutic targets.

TNF-α elicits phenotypic and functional alterations of vascular smooth muscle cells by miR-155-5p-dependent down-regulation of cGMP-dependent kinase 1

cGMP-dependent protein kinase 1 (PKG1) plays an important role in nitric oxide (NO)/cGMP-mediated maintenance of vascular smooth muscle cell (VSMC) phenotype and vasorelaxation. Inflammatory cytokines, including tumor necrosis factor-α (TNFα), have long been understood to mediate several inflammatory vascular diseases. However, the underlying mechanism of TNFα-dependent inflammatory vascular disease is unclear. Here, we found that TNFα treatment decreased PKG1 expression in cultured VSMCs, which correlated with NF-κB-dependent biogenesis of miR-155-5p that targeted the 3'-UTR of PKG1 mRNA. TNFα induced VSMC phenotypic switching from a contractile to a synthetic state through the down-regulation of VSMC marker genes, suppression of actin polymerization, alteration of cell morphology, and elevation of cell proliferation and migration. All of these events were blocked by treatment with an inhibitor of miR-155-5p or PKG1, whereas transfection with miR-155-5p mimic or PKG1 siRNA promoted phenotypic modulation, similar to the response to TNFα. In addition, TNFα-induced miR-155-5p inhibited the vasorelaxant response of de-endothelialized mouse aortic vessels to 8-Br-cGMP by suppressing phosphorylation of myosin phosphatase and myosin light chain, both of which are downstream signal modulators of PKG1. Moreover, TNFα-induced VSMC phenotypic alteration and vasodilatory dysfunction were blocked by NF-κB inhibition. These results suggest that TNFα impairs NO/cGMP-mediated maintenance of the VSMC contractile phenotype and vascular relaxation by down-regulating PKG1 through NF-κB-dependent biogenesis of miR-155-5p. Thus, the NF-κB/miR-155-5p/PKG1 axis may be crucial in the pathogenesis of inflammatory vascular diseases, such as atherosclerotic intimal hyperplasia and preeclamptic hypertension.

Vascular smooth muscle cell proliferation as a therapeutic target. Part 1: molecular targets and pathways

Cardiovascular diseases are a major cause of human death worldwide. Excessive proliferation of vascular smooth muscle cells contributes to the etiology of such diseases, including atherosclerosis, restenosis, and pulmonary hypertension. The control of vascular cell proliferation is complex and encompasses interactions of many regulatory molecules and signaling pathways. Herein, we recapitulated the importance of signaling cascades relevant for the regulation of vascular cell proliferation. Detailed understanding of the mechanism underlying this process is essential for the identification of new lead compounds (e.g., natural products) for vascular therapies.

Chicoric acid is a potent anti-atherosclerotic ingredient by anti-oxidant action and anti-inflammation capacity

Atherosclerotic cardiovascular disease is linked to both oxidative stress and endothelial cell dysfunction. Chicoric acid has antioxidant and anti-inflammatory properties. In the present investigation, we demonstrated that chicoric acid inhibits oxidized low-density lipoprotein (oxLDL)-facilitated dysfunction in human umbilical vein endothelial cells (HUVECs). Oxidative injuries were tested by investigating the formation of intracellular reactive oxygen species (ROS) and by examining the activity of antioxidant enzymes and the function of endothelial nitric oxide synthase (eNOS). We also confirmed that chicoric acid mitigates apoptotic features caused by oxLDL, such as the subsequent break down of mitochondrial transmembrane potential and the activation of Bax, which promote DNA strand breaks and activate caspase-3. Moreover, our data revealed that chicoric acid attenuated the oxLDL activation of NF-κB, the attachment of THP-1 cells and the overexpression of adhesion molecules in human endothelial cells. The results of this study suggest a potential molecular mechanism through which chicoric acid inhibits oxLDL-induced human endothelial dysfunction.

Nitric Oxide-Delivering High-Density Lipoprotein-like Nanoparticles as a Biomimetic Nanotherapy for Vascular Diseases

Disorders of blood vessels cause a range of severe health problems. As a powerful vasodilator and cellular second messenger, nitric oxide (NO) is known to have beneficial vascular functions. However, NO typically has a short half-life and is not specifically targeted. On the other hand, high-density lipoproteins (HDLs) are targeted natural nanoparticles (NPs) that transport cholesterol in the systemic circulation and whose protective effects in vascular homeostasis overlap with those of NO. Evolving the AuNP-templated HDL-like nanoparticles (HDL NPs), a platform of bioinspired HDL, we set up a targeted biomimetic nanotherapy for vascular disease that combines the functions of NO and HDL. A synthetic S-nitrosylated (SNO) phospholipid (1,2-dipalmitoyl-sn-glycero-3-phosphonitrosothioethanol) was synthesized and assembled with S-containing phospholipids and the principal protein of HDL, apolipoprotein A-I, to construct NO-delivering HDL-like particles (SNO HDL NPs). SNO HDL NPs self-assemble under mild conditions similar to natural processes, avoiding the complex postassembly modification needed for most synthetic NO-release nanoparticles. In vitro data demonstrate that the SNO HDL NPs merge the functional properties of NO and HDL into a targeted nanocarrier. Also, SNO HDL NPs were demonstrated to reduce ischemia/reperfusion injury in vivo in a mouse kidney transplant model and atherosclerotic plaque burden in a mouse model of atherosclerosis. Thus, the synthesis of SNO HDL NPs provides not only a bioinspired nanotherapy for vascular disease but also a foundation to construct diversified multifunctional platforms based on HDL NPs in the future.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

Reactive oxygen and nitrogen species are indispensable in cellular physiology and signaling. Overproduction of these reactive species or failure to maintain their levels within the physiological range results in cellular redox dysfunction, often termed cellular oxidative stress. Redox dysfunction in turn is at the molecular basis of disease etiology and progression. Accordingly, antioxidant intervention to restore redox homeostasis has been pursued as a therapeutic strategy for cardiovascular disease, cancer, and neurodegenerative disorders among many others. Despite preliminary success in cellular and animal models, redox-based interventions have virtually been ineffective in clinical trials. We propose the fundamental reason for their failure is a flawed delivery approach. Namely, systemic delivery for a geographically local disease limits the effectiveness of the antioxidant. We take a critical look at the literature and evaluate successful and unsuccessful approaches to translation of redox intervention to the clinical arena, including dose, patient selection, and delivery approach. We argue that when interpreting a failed antioxidant-based clinical trial, it is crucial to take into account these variables and importantly, whether the drug had an effect on the redox status. Finally, we propose that local and targeted delivery hold promise to translate redox-based therapies from the bench to the bedside.

Metformin ameliorates the progression of atherosclerosis via suppressing macrophage infiltration and inflammatory responses in rabbits

AIMS

The present study aimed to investigate the possible effects of metformin on the progression of atherosclerosis in a rabbit model.

MAIN METHODS

Rabbits were randomly divided into three groups (n = 10): the control (Ctrl) group (fed with a chow diet), and two experimental groups, the AS group and the Met group (both received an atherogenic diet). After 2 weeks of acclimatization, the rabbits in the AS and Met groups were given a placebo and metformin, respectively, daily by gavage for 10 weeks. Plasma lipids and inflammatory cytokines were measured. The aorta was isolated for histological and immunohistochemical analysis. In vitro, human umbilical vein endothelial cells (HUVECs) were treated with metformin, and monocyte adhesion and adhesion molecule expression were measured.

KEY FINDINGS

Metformin reduced plasma inflammatory cytokine levels but did not alter lipid content. Compared with that in the AS group, the atherosclerosis burden in the Met group was significantly decreased. The lesional macrophage content was reduced, but the lesional collagen content was not affected in the metformin-treated rabbits, compared with the corresponding levels in the non-treated controls. Furthermore, the aortic mRNA expression levels of adhesion molecules and inflammatory cytokines in the Met group were also significantly reduced compared with those in the AS group. Metformin treatment reduced monocyte adhesion to endothelial cells (ECs) and adhesion molecule expression, and inhibited rabbit monocyte differentiation into macrophages and the macrophage inflammatory response.

SIGNIFICANCE

Our results suggest that metformin impeded the progression of atherosclerosis, possibly by suppressing macrophage infiltration and inflammatory responses.

Toll-like receptor 2 downregulates the cholesterol efflux by activating the nuclear factor-κB pathway in macrophages and may be a potential therapeutic target for the prevention of atherosclerosis

Atherosclerosis is a chronic inflammatory disease, which is triggered by lipid retention. Toll-like receptor 2 (TLR2) is a novel target for therapeutic intervention in atherosclerosis. In addition, nuclear factor-κB (NF-κB) serves important roles in stress response and inflammation. The present study investigated whether TLR2 is involved in the activation of cholesterol efflux in macrophages by regulating the NF-κB pathway. The human monocytic THP-1 cell line and murine macrophage RAW264.7 cell line were treated with 50 µg/ml oxidized low-density lipoprotein (ox-LDL) for 48 h in order to obtain macrophage foam cells. The cholesterol efflux of the cell lines under exogenous TLR2 treatment was assessed by liquid scintillation counting. Furthermore, the protein and mRNA expression levels of ATP binding cassette transporter A1 (ABCA1), ABCG1 and scavenger receptor B1 (SR-B1) were examined by western blot and quantitative polymerase chain reaction assays, respectively. To detect the effect of NF-κB on cholesterol efflux, the cells were divided into three groups, including the control, 10 ng/ml lipopolysaccharides (LPS; 24 h) and 10 ng/ml LPS + 50 µM pyrrolidinedithiocarbamate (PDTC; 24 h) groups. The results indicated that ox-LDL induced foam cell formation in the THP-1 and RAW264.7 cells, while TLR2 significantly decreased the cholesterol efflux in dose- and time-dependent manners. Accordingly, TLR2 reduced ABCA1, ABCG1 and SR-B1 expression at the transcriptional and translational levels in a dose-dependent manner. In addition, application of PDTC (an NF-κB specific inhibitor) markedly suppressed the LPS-induced downregulation of cholesterol efflux. These data revealed that TLR2 may be involved in the activation of cholesterol efflux in macrophages by regulating the NF-κB signaling pathway.

Suppression of chronic inflammation with engineered nanomaterials delivering nuclear factor κB transcription factor decoy oligodeoxynucleotides

As a prototypical pro-inflammatory transcription factor, constitutive activation of NF-κB signaling pathway has been reported in several chronic inflammatory disorders including inflammatory bowel disease, cystic fibrosis, rheumatoid arthritis and cancer. Application of decoy oligodeoxynucleotides (ODNs) against NF-κB, as an effective molecular therapy approach, has brought about several promising outcomes in treatment of chronic inflammatory disorders. However, systematic administration of these genetic constructs is mostly hampered due to their instability, rapid degradation by nucleases and poor cellular uptake. Both chemical modification and application of delivery systems have shown to effectively overcome some of these limitations. Among different administered delivery systems, nanomaterials have gained much attention for delivering NF-κB decoy ODNs owing to their high loading capacity, targeted delivery and ease of synthesis. In this review, we highlight some of the most recently developed nanomaterial-based delivery systems for overcoming limitations associated with clinical application of these genetic constructs.

Crosstalk between endoplasmic reticulum stress and brain inflammation in Alzheimer's disease

While most often noted for its cognitive symptoms, Alzheimer's disease (AD) is, at its core, a disease of protein misfolding/aggregation, with an intriguing inflammatory component. Defective clearance and/or abnormal production of the amyloid-β peptide (Aβ), and its ensuing accumulation and aggregation, underlie two hallmark features of AD: brain accumulation of insoluble protein deposits known as amyloid or senile plaques, and buildup of soluble Aβ oligomers (AβOs), diffusible toxins linked to synapse dysfunction and memory impairment. In neurons, as in typical eukaryotic cells, the endoplasmic reticulum (ER) serves as a main compartment for the folding, maturation, trafficking and quality control of newly synthesized proteins. The ER lumen, a calcium-rich, oxidizing environment, provides favorable conditions for these physiological functions to occur. These conditions, however, also favor protein aggregation. Several stressors, including metabolic/nutrient stress and certain pathologies, may upset the ER homeostasis, e.g., by affecting calcium levels or by causing the accumulation of unfolded or misfolded proteins. Whatever the underlying cause, the result is what is commonly known as "ER stress". This, in turn, triggers a conserved cellular response mechanism known as the "unfolded protein response" (UPR). The UPR comprises three pathways involving transcriptional or translational regulators aimed at normalizing ER function, and each of them results in pro-inflammatory signaling. A positive feedback loop exists between ER stress and inflammation, with clear implications for neurodegeneration and AD. Here, we explore recent findings on the role of ER stress and the UPR in inflammatory processes leading to synapse failure and memory impairment in AD. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'

LincRNA DYN-LRB2-2 upregulates cholesterol efflux by decreasing TLR2 expression in macrophages

This study is designed to determine whether lincRNA-DYNLRB2-2 could promote cholesterol efflux through regulating the expression of TLR2. THP-1 and RAW264.7 cells were incubated with oxLDL for 48 h to induce the formation of foam cells, and ORO staining was performed and intracellular cholesterol contents were measured by HPLC assay. qRT-PCR and Western blotting were performed to detect mRNA and protein expression levels, respectively. Lentiviral vector LV-DYNLRB2-2 and lincRNA-DYNLRB2-2 siRNA was constructed to explore its potential role. The cholesterol efflux was assessed by liquid scintillation counting. The effects of TRL2 were determined in apoE^-/- mice that fed a high fat diet and were randomly divided into three groups and infected with LV-Mock, LV-Sh-TRL2, or LV-TRL2. Atherosclerosis was observed in the aortic sinus and the levels of cytokines and serum biochemical parameters were measured. Ox-LDL induced foam cell formation in the THP-1 and RAW264.7 cells. LincRNA DYN-LRB2-2 was upregulated in oxLDL-treated THP-1 and Raw264.7 cells. LincRNA-DYNLRB2-2 plays important role in regulating the cholesterol efflux, ABCA1 expression level and anti-inflammatory processes in THP-1 and RAW264.7 cells. Further study indicated that lincRNA-DYNLRB2-2 negatively regulated TRL2 expression and TRL2 overexpression reversed the effects of lincRNA-DYNLRB2-2 on cholesterol efflux and ABCA1 expression level in THP-1 and RAW264.7 cells. Besides, we found TRL2 plays important role in lipid accumulation, plaque formation and regulating serum inflammatory cytokines level in apoE^-/- mice with a high fat diet. LincRNA DYN-LRB2-2 upregulates cholesterol efflux by decreasing TLR2 expression in macrophages.

Macrophage complexity in human atherosclerosis: opportunities for treatment?

PURPOSE OF REVIEW

The pivotal role of macrophages in experimental atherosclerosis is firmly established, but their contribution to human disease is less well defined. In this review we have outlined the current insights on macrophage phenotypes and their presumed precursors, monocytes, in clinical atherosclerosis, and their association with disease progression. Moreover, we will assess major clinical modifiers of macrophage-mediated plaque inflammation and define the outstanding questions for further study.

RECENT FINDINGS

Our survey indicates that macrophage accumulation and status in human plaques are linked with lesion progression and destabilization as well as with symptomatic coronary artery disease. Likewise, levels of their precursors, circulating monocytes were repeatedly seen to associate with atherosclerosis and to predict clinical outcome. Furthermore, the presence and phenotype of both macrophages and monocytes appears to be responsive to the traditional risk factors of atherosclerosis, including hypercholesterolemia, hypertension, and type 2 diabetes, and to treatment thereof, with clear repercussions on disease development.

SUMMARY

Although plaque macrophages and their precursor cells do represent attractive targets for treating cardiovascular diseases, this therapeutic avenue requires much deeper understanding of the complexity of macrophage biology in human atherosclerosis than available at present.

Androgens and Hypertension in Men and Women: a Unifying View

PURPOSE OF REVIEW

This review was designed to revaluate the androgen role on the mechanisms of hypertension and cardiovascular risks in both men and women. Sex steroids are involved in the regulation of blood pressure, but pathophysiological mechanism is not well understood. Androgens have an important effect on metabolism, adipose and endothelial cell function, and cardiovascular risk in both men and women. A focal point in this contest is represented by the possible gender-specific regulation of different tissues and in particular of the adipose cell. Available data confirm that androgen deficiency is linked to increased prevalence of hypertension and cardiovascular diseases. Adipocyte dysfunction seems to be the main involved mechanism. Androgen replacement reduces inflammation state in man, protecting by metabolic syndrome progression. In women, androgen excess has been considered as promoting factor of cardiovascular risk. However, recent data suggest that excessive androgen production has little effect per se in inducing hypertension in young women of reproductive age. Also in postmenopausal women, data on relative androgen excess and hypertension are missing, while adrenal androgen deficiency has been associated to increased mortality.

RECENT FINDINGS

Molecular mechanisms linking androgen dysregulation to hypertension are almost Unknown, but they seem to be related to increased visceral fat, promoting a chronic inflammatory state through different mechanisms. One of these may involve the recruitment and over-activation of NF-kB, a ubiquitous transcription factor also expressed in adipose cells, where it may cause the production of cytokines and other immune factors. The NF-kB signalling pathway may also influence brown adipogenesis leading to the preferential enlargement of visceral adipocytes. Chronic inflammation and adipocyte dysfunction may alter endothelial function leading to hypertension. Both in men and in women, particularly in the post-menopausal period, hypoandrogenism seems to be a major determinant of the increased prevalence of hypertension. The relationship between androgen signalling and NF-kB might explain the pathophysiological mechanism leading to the development of endothelium dysfunction and hypertension.

Flow pattern-dependent endothelial cell responses through transcriptional regulation

Blood flow provides endothelial cells (ECs) lining the inside of blood vessels with mechanical stimuli as well as humoral stimuli. Fluid shear stress, the frictional force between flowing blood and ECs, is recognized as an essential mechanical cue for vascular growth, remodeling, and homeostasis. ECs differentially respond to distinct flow patterns. High laminar shear flow leads to inhibition of cell cycle progression and stabilizes vessels, whereas low shear flow or disturbed flow leads to increased turnover of ECs and inflammatory responses of ECs prone to atherogenic. These differences of EC responses dependent on flow pattern are mainly ascribed to distinct patterns of gene expression. In this review, we highlight flow pattern-dependent transcriptional regulation in ECs by focusing on KLF2 and NFκB, major transcription factors responding to laminar flow and disturbed flow, respectively. Moreover, we introduce roles of a new flow-responsive transcriptional co-regulator, YAP, in blood vessel maintenance and discuss how these transcriptional regulators are spatiotemporally regulated by flow and then regulate EC functions in normal and pathological conditions.

Paradoxical Suppression of Atherosclerosis in the Absence of microRNA-146a

RATIONALE

Inflammation is a key contributor to atherosclerosis. MicroRNA-146a (miR-146a) has been identified as a critical brake on proinflammatory nuclear factor κ light chain enhancer of activated B cells signaling in several cell types, including endothelial cells and bone marrow (BM)-derived cells. Importantly, miR-146a expression is elevated in human atherosclerotic plaques, and polymorphisms in the miR-146a precursor have been associated with risk of coronary artery disease.

OBJECTIVE

To define the role of endogenous miR-146a during atherogenesis.

METHODS AND RESULTS

Paradoxically, Ldlr^-/- (low-density lipoprotein receptor null) mice deficient in miR-146a develop less atherosclerosis, despite having highly elevated levels of circulating proinflammatory cytokines. In contrast, cytokine levels are normalized in Ldlr^-/-;miR-146a^-/- mice receiving wild-type BM transplantation, and these mice have enhanced endothelial cell activation and elevated atherosclerotic plaque burden compared with Ldlr^-/- mice receiving wild-type BM, demonstrating the atheroprotective role of miR-146a in the endothelium. We find that deficiency of miR-146a in BM-derived cells precipitates defects in hematopoietic stem cell function, contributing to extramedullary hematopoiesis, splenomegaly, BM failure, and decreased levels of circulating proatherogenic cells in mice fed an atherogenic diet. These hematopoietic phenotypes seem to be driven by unrestrained inflammatory signaling that leads to the expansion and eventual exhaustion of hematopoietic cells, and this occurs in the face of lower levels of circulating low-density lipoprotein cholesterol in mice lacking miR-146a in BM-derived cells. Furthermore, we identify sortilin-1(Sort1), a known regulator of circulating low-density lipoprotein levels in humans, as a novel target of miR-146a.

CONCLUSIONS

Our study reveals that miR-146a regulates cholesterol metabolism and tempers chronic inflammatory responses to atherogenic diet by restraining proinflammatory signaling in endothelial cells and BM-derived cells.

Effect of Pranayama on Ppar-γ, Nf-κB Expressions and Red Complex Microorganisms in Patients with Chronic Periodontitis - A Clinical Trial

INTRODUCTION

Sudarshankriya pranayama is the control of breathing movements to regulate the energy flow throughout the body, which has shown to positively affect immune function, autonomic nervous system and psychologic-neuro pathways. The practice of pranayama has been proven to show several benefits such as reduction in stress levels, relieves anxiety and depression, increase in antioxidant levels, reduces insulin resistance and improves respiratory function.

AIM

The objective of the study was to evaluate the levels of Peroxisome Proliferator-Activated Receptor Gamma (PPAR-γ), Nuclear Factor-Kappa B (NF-κB) and the presence of Red Complex Microorganisms (RCM) such as Treponema denticola, Porphyromonas gingivalis and Tannerella forsythia in the subgingivalpl aque samples of chronic periodontitis subjects before and after intervention with pranayama as an adjunct to Scaling and Root Planing (SRP).

MATERIALS AND METHODS

A total of 30 subjects (control group) were treated with SRP and 30 subjects (pranayama group) underwent SRP and pranayama for three months. Probing Pocket Depth (PPD), Clinical Attachment Level (CAL), Bleeding Index (BI) and Plaque Index (PI) were recorded and the presence of PPAR-γ, NF-κB and RCM were assessed at baseline and after three months using polymerase chain reaction. ANCOVA test was done to compare the clinical parameters between the groups. Fisher's Exact test was done to identify RCM and Mann-Whitney and Wilcoxon-signed test was used to identify the expression of NF-κB and PPAR-γ in the plaque samples.

RESULTS

The change in the mean CAL from baseline to third month was significantly higher in pranayama group compared to control group (p≤0.05). There was a statistically significant reduction in the expression of NF-κB and increase in PPAR-γ expression levels in pranayama group on comparison with the control group (p<0.001). The reduction in number of positive samples with T.denticola, P.gingivalis and T.forsythia at third month post-intervention did not affect the change in the expression levels of NF-κB and PPAR-γ.

CONCLUSION

The CAL showed significant improvement with reduction in the RCM, NF-κB and increase in PPAR-γ levels in subjects who underwent pranayama as an adjunct to SRP. In future, pranayama can be used as an additional treatment modality to provide a new dimension in treatment of periodontitis.

Hypertension-Causing Mutation in Peroxisome Proliferator-Activated Receptor γ Impairs Nuclear Export of Nuclear Factor-κB p65 in Vascular Smooth Muscle

Selective expression of dominant negative (DN) peroxisome proliferator-activated receptor γ (PPARγ) in vascular smooth muscle cells (SMC) results in hypertension, atherosclerosis, and increased nuclear factor-κB (NF-κB) target gene expression. Mesenteric SMC were cultured from mice designed to conditionally express wild-type (WT) or DN-PPARγ in response to Cre recombinase to determine how SMC PPARγ regulates expression of NF-κB target inflammatory genes. SMC-specific overexpression of WT-PPARγ or agonist-induced activation of endogenous PPARγ blunted tumor necrosis factor α (TNF-α)-induced NF-κB target gene expression and activity of an NF-κB-responsive promoter. TNF-α-induced gene expression responses were enhanced by DN-PPARγ in SMC. Although expression of NF-κB p65 was unchanged, nuclear export of p65 was accelerated by WT-PPARγ and prevented by DN-PPARγ in SMC. Leptomycin B, a nuclear export inhibitor, blocked p65 nuclear export and inhibited the anti-inflammatory action of PPARγ. Consistent with a role in facilitating p65 nuclear export, WT-PPARγ coimmunoprecipitated with p65, and WT-PPARγ was also exported from the nucleus after TNF-α treatment. Conversely, DN-PPARγ does not bind to p65 and was retained in the nucleus after TNF-α treatment. Transgenic mice expressing WT-PPARγ or DN-PPARγ specifically in SMC (S-WT or S-DN) were bred with mice expressing luciferase controlled by an NF-κB-responsive promoter to assess effects on NF-κB activity in whole tissue. TNF-α-induced NF-κB activity was decreased in aorta and carotid artery from S-WT but was increased in vessels from S-DN mice. We conclude that SMC PPARγ blunts expression of proinflammatory genes by inhibition of NF-κB activity through a mechanism promoting nuclear export of p65, which is abolished by DN mutation in PPARγ.

Tim-3 inhibits low-density lipoprotein-induced atherogenic responses in human umbilical vein endothelial cells

Endothelial injury and dysfunction followed by endothelial activation and inflammatory cell recruitment are factors contributing to the initiation and progression of atherosclerosis. Oxidized low-density lipoprotein (ox-LDL) promotes inflammation during atherogenesis and lipid deposition in the arterial wall. We observed that stimulation of human umbilical vein endothelial cells (HUVECs) with ox-LDL activated pro-inflammatory cytokine production and apoptosis, inhibited cell migration, and upregulated T-cell immunoglobulin and mucin domain 3 (Tim-3) expression. Tim-3, in turn, protected HUVECs from ox-LDL-induced apoptosis via the JNK pathway and reversed the inhibition of migration. Tim-3 also inhibited ox-LDL-induced inflammatory cytokine production by suppressing NF-κB activation. In addition, Tim-3 increased production of type 2 T helper cells (Th2) and regulatory T cell (Treg)-associated cytokines. Blocking Tim-3 reversed its effects on the inflammatory response to ox-LDL. Thus, Tim-3 signaling may be a “self-control” mechanism in ox-LDL-triggered inflammation in HUVECs. These results identify Tim-3 as a factor in HUVEC activity and suggest its potential in the treatment of atherosclerosis.

The ligand-bound thyroid hormone receptor in macrophages ameliorates kidney injury via inhibition of nuclear factor-κB activities

In chronic kidney disease (CKD) patients, inflammation plays a pivotal role in the progression of renal fibrosis. Hypothyroidism is associated with an increased occurrence of atherosclerosis and inflammation, suggesting protective roles of thyroid hormones and their receptors against inflammatory processes. The contribution of thyroid hormone receptors to macrophage differentiation has not been well documented. Here, we focused on the endogenous thyroid hormone receptor α (TRα) in macrophages and examined the role of ligand-bound TRα in macrophage polarization-mediated anti-inflammatory effects. TRα-deficient irradiated chimeric mice showed exacerbated tubulointerstitial injury in a unilateral ureteral obstruction model. Compared with wild-type macrophages, macrophages isolated from the obstructed kidneys of mice lacking TRα displayed increased expression of proinflammatory cytokines that was accompanied by enhanced nuclear translocation of p65. Comparison of TRα-deficient bone marrow-derived macrophages with wild-type macrophages confirmed the propensity of the former cells to produce excessive IL-1β levels. Co-culture of these macrophages with renal epithelial cells induced more severe damage to the epithelial cells via the IL-1 receptor. Our findings indicate that ligand-bound TRα on macrophages plays a protective role in kidney inflammation through the inhibition of NF-κB pathways, possibly by affecting the pro- and anti-inflammatory balance that controls the development of CKD.

Vinexin β Ablation Inhibits Atherosclerosis in Apolipoprotein E-Deficient Mice by Inactivating the Akt-Nuclear Factor κB Inflammatory Axis

BACKGROUND

Vinexin β is a novel adaptor protein that regulates cellular adhesion, cytoskeletal reorganization, signal transduction, and transcription; however, the exact role that vinexin β plays in atherosclerosis remains unknown.

METHODS AND RESULTS

Immunoblot analysis showed that vinexin β expression is upregulated in the atherosclerotic lesions of both patients with coronary heart disease and hyperlipemic apolipoprotein E-deficient mice and is primarily localized in macrophages indicated by immunofluorescence staining. The high-fat diet-induced double-knockout mice exhibited lower aortic plaque burdens than apolipoprotein E-/- littermates and decreased macrophage content. Vinexin β deficiency improved plaque stability by attenuating lipid accumulation and increasing smooth muscle cell content and collagen. Moreover, the bone marrow transplant experiment demonstrated that vinexin β deficiency exerts atheroprotective effects in hematopoietic cells. Consistent with these changes, the mRNA expression of proinflammatory cytokines were downregulated in vinexin β-/- apolipoprotein E-/- mice, whereas the anti-inflammatory M2 macrophage markers were upregulated. The immunohistochemical staining and in vitro experiments showed that deficiency of vinexin β inhibited the accumulation of monocytes and the migration of macrophages induced by tumor necrosis factor α-stimulated human umbilical vein endothelial cells as well as macrophage proliferation. Finally, the inhibitory effects exerted by vinexin β deficiency on foam cell formation, nuclear factor κB activation, and inflammatory cytokine expression were largely reversed by constitutive Akt activation, whereas the increased expression of the nuclear factor κB subset promoted by adenoviral vinexin β was dramatically suppressed by inhibition of AKT.

CONCLUSIONS

Vinexin β deficiency attenuates atherogenesis primarily by suppressing vascular inflammation and inactivating Akt-nuclear factor κB signaling. Our data suggest that vinexin β could be a therapeutic target for the treatment of atherosclerosis.

Sargachromenol protects against vascular inflammation by preventing TNF-α-induced monocyte adhesion to primary endothelial cells via inhibition of NF-κB activation

Vascular inflammation is a key factor in the pathogenesis of atherosclerosis. The purpose of this study was to investigate the protective effects of sargachromenol (SCM) against tumor necrosis factor (TNF)-α-induced vascular inflammation. SCM decreased the expression of cell adhesion molecules, including intracellular adhesion molecule-1 and vascular cell adhesion molecule-1, in TNF-α-stimulated human umbilical vein endothelial cells (HUVECs), resulted in reduced adhesion of monocytes to HUVECs. SCM also decreased the production of monocyte chemoattractant protein-1 and matrix metalloproteinase-9 in TNF-α-induced HUVECs. Additionally, SCM inhibited activation of nuclear factor kappa B (NF-κB) induced by TNF-α through preventing the degradation of inhibitor kappa B. Moreover, SCM reduced the production of reactive oxygen species in TNF-α-treated HUVECs. Overall, SCM alleviated vascular inflammation through the regulation of NF-κB activation and through its intrinsic antioxidant activity in TNF-α-induced HUVECs. These results indicate that SCM may have potential application as a therapeutic agent against vascular inflammation.

Loss of Caspase-Activated DNase Protects Against Atherosclerosis in Apolipoprotein E-Deficient Mice

BACKGROUND

Atherosclerosis is a chronic disease that is closely related to inflammation and macrophage apoptosis, which leads to secondary necrosis and proinflammatory responses in advanced lesions. Caspase-activated DNase (CAD) is a double-strand specific endonuclease that leads to the subsequent degradation of chromosome DNA during apoptosis. However, whether CAD is involved in the progression of atherosclerosis remains elusive.

METHODS AND RESULTS

CAD-/-ApoE-/- and ApoE-/- littermates were fed a high-fat diet for 28 weeks to develop atherosclerosis. Human specimens were collected from coronary heart disease (CHD) patients who were not suitable for transplantation. CAD expression was increased in the atheromatous lesions of CHD patients and high-fat diet-treated ApoE-deficient mice. Further investigation demonstrated that CAD deficiency inhibited high-fat diet-induced atherosclerosis, as evidenced by decreased atherosclerotic plaques, inhibited inflammatory response, and macrophage apoptosis, as well as enhanced stability of plaques in CAD-/-ApoE-/- mice compared to the ApoE-/- controls. Bone marrow transplantation verified the effect of CAD on atherosclerosis from macrophages. Mechanically, the decrease in the phosphorylated levels of mitogen-activated protein kinase (MAPK) kinase/extracellular signal-regulated kinase 1 and 2 (MEK-ERK1/2) that resulted from CAD knockout and the activation of nuclear factor kappa B signaling mediated by CAD stimulation that was suppressed by inhibiting ERK1/2 phosphorylation revealed the potential association between the role of CAD in atherosclerosis and the MAPK signaling pathway.

CONCLUSIONS

In conclusion, CAD deficiency protects against atherosclerosis through inhibiting inflammation and macrophage apoptosis, which is partially through inactivation of the MEK-ERK1/2 signaling pathway. This finding provides a promising therapeutic target for treating atherosclerosis.

α-Tocopherol and Atherosclerosis

Cardiovascular disease is the leading cause of morbidity and mortality in the Western world. There is compelling evidence incriminating oxidative stress in the pathogenesis of the atherosclerotic lesion. Several lines of evidence suggest that antioxidants, especially α-tocopherol, have potential beneficial effects with regard to cardiovascular disease. In vitro, α-tocopherol has been shown to inhibit platelet adhesion and aggregation and smooth muscle cell proliferation, exert anti-inflammatory effects on monocytes, and improve endothelial function. Also, supplementation with α-tocopherol has been shown to decrease lipid peroxidation, platelet aggregation, and pro-inflammatory activity of monocytes. However, clinical trials with α-tocopherol supplementation to date have been equivocal. Thus, although mounting in vitro evidence and animal models provide a sound scientific basis for α-tocopherol supplementation, further clinical trials are required before a definitive recommendation can be made with respect to the primary and secondary prevention of heart disease.