Regulation of endotoxin-induced proinflammatory activation in human coronary artery cells: expression of functional membrane-bound CD14 by human coronary artery smooth muscle cells

The prognostic potential of long noncoding RNA XIST in cardiovascular diseases: a review

There is a significant mortality rate associated with cardiovascular disease despite advances in treatment. long Non-coding RNAs (lncRNAs) play a critical role in many biological processes and their dysregulation is associated with a wide range of diseases in which their downstream pathways are disrupted. A lncRNA X-inactive specific transcript (XIST) is well known as a factor that regulates the physiological process of chromosome dosage compensation for females. According to recent studies, lncRNA XIST is involved in a variety of cellular processes, including apoptosis, proliferation, invasion, metastasis, oxidative stress and inflammation, through molecular networks with microRNAs and their downstream targets in neoplastic and non-neoplastic diseases. Because these cellular processes play a role in the pathogenesis of cardiovascular diseases, we aim to investigate the role that lncRNA XIST plays in this process. Additionally, we wish to determine whether it is a prognostic factor or a potential therapeutic target in these diseases.

Soluble CD14 and Incident Diabetes Risk: The REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Context

Soluble CD14 (sCD14) is an inflammation biomarker with higher concentrations in White than Black adults. Higher sCD14 is seen in insulin resistance and diabetes. There are limited data on the relationship between sCD14 and incident diabetes.

Objective

To determine the association of sCD14 with incident diabetes risk in a large biracial US cohort and evaluate whether relationships differ by race.

Design

This study included 3401 Black and White participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study without baseline diabetes who completed baseline and follow-up in-home visits. Modified Poisson regression models estimated risk ratios (RR) of incident diabetes per 1-SD increment sCD14, with adjustment for risk factors. A sCD14-by-race interaction evaluated whether associations differed by race.

Results

There were 460 cases of incident diabetes over a mean 9.5 years of follow-up. The association of sCD14 with diabetes differed by race (P for interaction < .09). Stratifying by race, adjusting for age, sex, and region, higher sCD14 was associated with incident diabetes in White (RR: 1.15; 95% CI: 1.01, 1.33) but not Black participants (RR: 0.96; 95% CI: 0.86, 1.08). In models adjusted for clinical and sociodemographic diabetes risk factors, the association was attenuated among White participants (RR: 1.10; 95% CI: 0.95, 1.28) and remained null among Black participants (RR: 0.90; 95% CI: 0.80, 1.01).

Conclusion

sCD14 was associated with incident diabetes risk in White but not Black adults, but this association was explained by diabetes risk factors.

A green tea extract confection decreases circulating endotoxin and fasting glucose by improving gut barrier function but without affecting systemic inflammation: A double-blind, placebo-controlled randomized trial in healthy adults and adults with metabolic syndrome

Anti-inflammatory activities of catechin-rich green tea extract (GTE) in obese rodents protect against metabolic endotoxemia by decreasing intestinal permeability and absorption of gut-derived endotoxin. However, translation to human health has not been established. We hypothesized that GTE would reduce endotoxemia by decreasing gut permeability and intestinal and systemic inflammation in persons with metabolic syndrome (MetS) compared with healthy persons. A randomized, double-blind, placebo-controlled, crossover trial in healthy adults (n = 19, 34 ± 2 years) and adults with MetS (n = 21, 40 ± 3 years) examined 4-week administration of a decaffeinated GTE confection (890 mg/d total catechins) on serum endotoxin, intestinal permeability, gut and systemic inflammation, and cardiometabolic parameters. Compared with the placebo, the GTE confection decreased serum endotoxin (P = .023) in both healthy persons and those with MetS, while increasing concentrations of circulating catechins (P < .0001) and γ-valerolactones (P = .0001). Fecal calprotectin (P = .029) and myeloperoxidase (P = .048) concentrations were decreased by GTE regardless of health status. Following the ingestion of gut permeability probes, urinary lactose/mannitol (P = .043) but not sucralose/erythritol (P > .05) was decreased by GTE regardless of health status. No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass nor were plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected. However, fasting glucose in both study groups was decreased (P = .029) by the GTE confection compared with within-treatment arm baseline concentrations. These findings demonstrate that catechin-rich GTE is effective to decrease circulating endotoxin and improve glycemic control in healthy adults and those with MetS, likely by reducing gut inflammation and small intestinal permeability but without affecting systemic inflammation.

Hyperglycaemia Aggravates Oxidised Low-Density Lipoprotein-Induced Schwann Cell Death via Hyperactivation of Toll-like Receptor 4

Increased low-density lipoprotein levels are risk factors for diabetic neuropathy. Diabetes mellitus is associated with elevated metabolic stress, leading to oxidised low-density lipoprotein formation. Therefore, it is important to investigate the mechanisms underlying the pathogenesis of diabetic neuropathy in diabetes complicated by dyslipidaemia with increased levels of oxidised low-density lipoprotein. Here, we examined the effects of hyperglycaemia and oxidised low-density lipoprotein treatment on Schwann cell death and its underlying mechanisms. Immortalised mouse Schwann cells were treated with oxidised low-density lipoprotein under normo- or hyperglycaemic conditions. We observed that oxidised low-density lipoprotein-induced cell death increased under hyperglycaemic conditions compared with normoglycaemic conditions. Moreover, hyperglycaemia and oxidised low-density lipoprotein treatment synergistically upregulated the gene and protein expression of toll-like receptor 4. Pre-treatment with TAK-242, a selective toll-like receptor 4 signalling inhibitor, attenuated hyperglycaemia- and oxidised low-density lipoprotein-induced cell death and apoptotic caspase-3 pathway. Our findings suggest that the hyperactivation of toll-like receptor 4 signalling by hyperglycaemia and elevated oxidised low-density lipoprotein levels synergistically exacerbated diabetic neuropathy; thus, it can be a potential therapeutic target for diabetic neuropathy.

Atherosclerosis and Toll-Like Receptor4 (TLR4), Lectin-Like Oxidized Low-Density Lipoprotein-1 (LOX-1), and Proprotein Convertase Subtilisin/Kexin Type9 (PCSK9)

Atherosclerosis is a leading cause of death in the world. A significant body of evidence suggests that inflammation and various players are implicated and have pivotal roles in the formation of atherosclerotic plaques. Toll-like receptor 4 (TLR4) is linked with different stages of atherosclerosis. This receptor is highly expressed in the endothelial cells (ECs) and atherosclerotic plaques. TLR4 activation can lead to the production of inflammatory cytokines and related responses. Lectin-like oxidized low-density lipoprotein-1 (LOX-1), an integral membrane glycoprotein with widespread expression on the ECs, is involved in atherosclerosis and has some common pathways with TLR4 in atherosclerotic lesions. In addition, proprotein convertase subtilisin/kexin type9 (PCSK9), which is a regulatory enzyme with different roles in cholesterol uptake, is implicated in atherosclerosis. At present, TLR4, PCSK9, and LOX-1 are increasingly acknowledged as key players in the pathogenesis of atherosclerotic cardiovascular diseases. Herein, we presented the current evidence on the structure, functions, and roles of TLR4, PCSK9, and LOX-1 in atherosclerosis.

Identification of Important Genes Associated with the Development of Atherosclerosis

Atherosclerosis is one of the most important medical problems due to its prevalence and significant contribution to the structure of temporary and permanent disability and mortality. Atherosclerosis is a complex chain of events occurring in the vascular wall over many years. Disorders of lipid metabolism, inflammation, and impaired hemodynamics are important mechanisms of atherogenesis. A growing body of evidence strengthens the understanding of the role of genetic and epigenetic factors in individual predisposition and development of atherosclerosis and its clinical outcomes. In addition, hemodynamic changes, lipid metabolism abnormalities, and inflammation are closely related and have many overlapping links in regulation. A better study of these mechanisms may improve the quality of diagnosis and management of such patients.

The role of serum circulating microbial toxins in severity and cytokine storm of COVID positive patients

The emergence of Coronavirus disease 2019 (Covid-19) is a global problem nowadays, causing health difficulty with increasing mortality rates, which doesn't have a verified treatment. SARS-CoV-2 infection has various pathological and epidemiological characteristics, one of them is increased amounts of cytokine production, which in order activate an abnormal unrestricted response called "cytokine storm". This event contributes to severe acute respiratory distress syndrome (ARDS), which results in respiratory failure and pneumonia and is the great cause of death associated with Covid-19. Endotoxemia and the release of bacterial lipopolysaccharides (endotoxins) from the lumen into the bloodstream enhance proinflammatory cytokines. SARS-CoV-2 can straightly interplay with endotoxins via its S protein, leading to the extremely elevating release of cytokines and consequently increase the harshness of Covid-19. In this review, we will discuss the possible role of viral-bacterial interaction that occurs through the transfer of bacterial products such as lipopolysaccharide (LPS) from the intestine into the bloodstream, exacerbating the severity of Covid-19 and cytokine storms.

Dysregulation and imbalance of innate and adaptive immunity are involved in the cardiomyopathy progression

Background

Cardiomyopathy is known to be a heterogeneous disease with numerous etiologies. They all have varying degrees and types of myocardial pathological changes, resulting in impaired contractility, ventricle relaxation, and heart failure. The purpose of this study was to determine the pathogenesis, immune-related pathways and important biomarkers engaged in the progression of cardiomyopathy from various etiologies.

Methods

We downloaded the gene microarray data from the Gene Expression Omnibus (GEO). The hub genes between cardiomyopathy and non-cardiomyopathy control groups were identified using differential expression analysis, least absolute shrinkage and selection operator (LASSO) regression and weighted gene co-expression network analysis (WGCNA). To assess the diagnostic precision of hub genes, receiver-operating characteristic (ROC) curves as well as the area under the ROC curve (AUC) were utilized. Then, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment pathway analysis and Gene Ontology (GO) analysis were conducted on the obtained differential genes. Finally, single-sample GSEA (ssGSEA) and Gene Set Enrichment Analysis (GSEA) were utilized to analyze the infiltration level of 28 immune cells and their relationship with hub genes based on gene expression profile data and all differential gene files.

Results

A total of 82 differentially expressed genes (DEGs) were screened after the training datasets were merged and intersected. The WGCNA analysis clustered the expression profile data into four co-expression modules, The turquoise module exhibited the strongest relationship with clinical traits, and nine candidate key genes were obtained from the module. Then we intersected DEGs with nine candidate genes. LASSO regression analysis identified the last three hub genes as promising biomarkers to distinguish the cardiomyopathy group from the non-cardiomyopathy control group. ROC curve analysis in the validation dataset revealed the sensitivity and accuracy of three hub genes as marker genes. The majority of the functional enrichment analysis results were concentrated on immunological and inflammatory pathways. Immune infiltration analysis revealed a significant correlation between regulatory T cells, type I helper T cells, macrophages, myeloid-derived suppressor cells, natural killer cells, activated dendritic cells and the abundance of immune infiltration in hub genes.

Conclusion

The hub genes (CD14, CCL2, and SERPINA3) can be used as markers to distinguish cardiomyopathy from non-cardiomyopathy individuals. Among them, SERPINA3 has the best diagnostic performance. T cell immunity (adaptive immune response) is closely linked to cardiomyopathy progression. Hub genes may protect the myocardium from injury through myeloid-derived suppressor cells, regulatory T cells, helper T cells, monocytes/macrophages, natural killer cells and activated dendritic cells. The innate immune response is crucial to this process. Dysregulation and imbalance of innate immune cells or activation of adaptive immune responses are involved in cardiomyopathy disease progression in patients.

Cynarin attenuates LPS-induced endothelial inflammation via upregulation of the negative regulator MKP-3

Clinical observations have revealed that non-resolving low-grade inflammation is linked to the pathogenesis of chronic inflammatory diseases, for example arthritis, atherosclerosis, Alzheimer’s disease, diabetes, and chronic kidney disease. Interestingly, low levels of circulating lipopolysaccharides (LPS) derived from the outer membrane of gram-negative bacteria appear to be one of the primary causes of persistent low-grade inflammation. The inner surface of the blood vessels is lined with endothelial cells; therefore, even low levels of circulating LPS can directly activate these cells and elicit specific cellular responses, such as an increase in the expression levels of cell adhesion molecules and proinflammatory mediators. In endothelial cells, LPS exposure results in an inflammatory response through activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases. Cynarin, a phytochemical found in artichokes, has several pharmacological properties against endothelial inflammation. In the present study, we discovered that cynarin suppressed the LPS-induced increase in the expression levels of vascular cell adhesion molecule-1 and proinflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and interleukin-1β in EA.hy926 cells. Further, cynarin inhibited the activation of p38 and NF-κB pathways by inducing the negative regulator mitogen-activated protein kinase phosphatase 3 (MKP-3) in LPS-stimulated EA.hy926 cells. In conclusion, cynarin alleviates inflammation by upregulating MKP-3, a negative regulator of p38 and NF-κB, and it may be a therapeutic option for treating endothelial inflammation-related diseases.

The Intriguing Role of TLR Accessory Molecules in Cardiovascular Health and Disease

Activation of Toll like receptors (TLR) plays an important role in cardiovascular disease development, progression and outcomes. Complex TLR mediated signaling affects vascular and cardiac function including tissue remodeling and repair. Being central components of both innate and adaptive arms of the immune system, TLRs interact as pattern recognition receptors with a series of exogenous ligands and endogenous molecules or so-called danger associated molecular patterns (DAMPs) that are released upon tissue injury and cellular stress. Besides immune cells, a number of structural cells within the cardiovascular system, including endothelial cells, smooth muscle cells, fibroblasts and cardiac myocytes express TLRs and are able to release or sense DAMPs. Local activation of TLR-mediated signaling cascade induces cardiovascular tissue repair but in a presence of constant stimuli can overshoot and cause chronic inflammation and tissue damage. TLR accessory molecules are essential in guiding and dampening these responses toward an adequate reaction. Furthermore, accessory molecules assure specific and exclusive TLR-mediated signal transduction for distinct cells and pathways involved in the pathogenesis of cardiovascular diseases. Although much has been learned about TLRs activation in cardiovascular remodeling, the exact role of TLR accessory molecules is not entirely understood. Deeper understanding of the role of TLR accessory molecules in cardiovascular system may open therapeutic avenues aiming at manipulation of inflammatory response in cardiovascular disease. The present review outlines accessory molecules for membrane TLRs that are involved in cardiovascular disease progression. We first summarize the up-to-date knowledge on TLR signaling focusing on membrane TLRs and their ligands that play a key role in cardiovascular system. We then survey the current evidence of the contribution of TLRs accessory molecules in vascular and cardiac remodeling including myocardial infarction, heart failure, stroke, atherosclerosis, vein graft disease and arterio-venous fistula failure.

TLR2 and TLR4 molecules and antigen-presenting cell compositions in cecal tonsils of broiler chicks (Gallus gallus domesticus) in the first two weeks of the post-hatch period

Chickens do not have lymph nodes. Gut-associated lymphoid tissue is the major immunological organization for the digestive system. Cecal tonsils are an important part of this organization. This study is a descriptive and experimental study that was conducted to determine the histological development of the cecal tonsils and the distribution of Toll-like receptor (TLR) 2, TLR4 and antigen-presenting cells during the first 2 weeks of the chick's life. The tissue sections were stained using Crossmon's triple technique, Gordon and Sweet's silver impregnation, and streptavidin-biotin-peroxidase complex methods. The classical tonsil framework with fossa and tonsillar units were observed in 4 days cecal tissue. The web of reticular fibres forming the stroma of the tissue had the impression that the lymphoid cells filling in time. The development of cecal tonsil was completed histologically on the day 10 and following day 14 samples. Regardless of the antigenic stimulation, TLR2, TLR4 and CD83, major histocompatibility complex (MHC) class II molecules are present in proximal cecal tissue. However, CD83-positive dendritic cells in the germinal centre were first distinguished on day 7. Furthermore, the high antigen presentation capacity of the cecum with an intense MHC class II molecule expression was determined. Histological and immunohistochemical findings in this study revealed that both innate and adaptive cecal defence mechanisms were in the learning period during the first 2 weeks. The learning period of innate immunity may require more detailed research. However, the results obtained in this study will be taken into consideration in the vaccination programmes in chicks.

Cardiovascular Health and The Intestinal Microbial Ecosystem: The Impact of Cardiovascular Therapies on The Gut Microbiota

It has become evident over the past several years that the intestinal microbial ecosystem plays a critical role in the development and prevention of cardiovascular diseases (CVDs) and other metabolic disorders, such as hypertension, obesity, diabetes mellitus, and metabolic syndrome. The intestinal microbiota ecosystem functions as a major virtual endocrine organ that interacts and responds to molecules' signals within the host. Several meta-organismal pathways are involved in the gut-host interaction, including trimethylamine-N-oxide (TMAO) and short-chain fatty acids (SCFA). Host phenotype and cardiovascular diseases (CVDs) varying from hypertension, insulin resistance, and obesity to more specific inflammatory processes, such as atherosclerosis and hypercoagulability, have shown to be affected by the gut-host interaction. Additionally, several studies that involved animals and humans demonstrated a striking connection between the development of new CVDs and an imbalance in the gut microbiota composition along with the presence of their derived metabolites. Through this review article, we aim to evaluate the role of the normal gut microbiota ecosystem, its association with CVDs, effects of the therapies used to control and manage CVDs in the gut microbiota environment and explore potential therapeutic interventions to amplify disease outcomes in patients with CVDs.

Implications for the role of lipopolysaccharide in the development of atherosclerosis

Mounting scientific evidence over decades has established that atherosclerosis is a chronic inflammatory disorder. Among the potentially critical sources of vascular inflammation during atherosclerosis are the components of pathogenic bacteria, especially lipopolysaccharide (LPS). Toll-like receptor (TLR)-4, expressed on different inflammatory cells involved with the recognition of bacterial LPS, has been recognized to have mutations that are prevalent in a number of ethnic groups. Such mutations have been associated with a decreased risk of atherosclerosis. In addition, epidemiological investigations have proposed that LPS confers a risk factor for the development of atherosclerosis. Gram-negative bacteria are the major source of LPS in an individual's serum, which may be generated during subclinical infections. The major cell receptors on inflammatory cells involved in the pathogenesis of atherosclerosis, like macrophages, monocytes, and dendritic cells (DCs), are CD14, MD-2, and LPS binding protein (LBP). These receptors have been blamed for the development of atherosclerosis through dysregulated activation following LPS recognition. Lipoproteins may also play a role in modulating the LPS-induced inflammatory events during atherosclerosis development. In this review article, we attempt to clarify the role of LPS in the initiation and progression of atherosclerotic lesion development.

Toll-Like Receptor 4 and Inflammatory Micro-Environment of Pancreatic Islets in Type-2 Diabetes Mellitus: A Therapeutic Perspective

Patients with type-2 diabetes mellitus (T2DM) display chronic low-grade inflammation induced by activation of the innate immune system. Toll-like receptor (TLR)4 is a pattern recognition receptor that plays a vital part in activation of the innate immune system. Results from animal and computer-simulation studies have demonstrated that targeting TLR4 to block the TLR4-nuclear factor-kappa B (NF-κB) pathway reduces the inflammatory response and complications associated with T2DM. Therefore, TLR4-targeted therapy has broad prospects. Here, we reviewed the role of TLR4 in inflammation during chronic hyperglycemia in T2DM and its therapeutic prospects.

CD14: Biology and role in the pathogenesis of disease

Human monocyte differentiation antigen CD14 is a pattern recognition receptor (PRR) that enhances innate immune responses. CD14 was first identified as a marker of monocytes to signal intracellular responses upon bacterial encounters. Given the absence of an intracellular tail, CD14 was doubted to have the signaling capacities. Later CD14 was confirmed as the TLR co-receptor for the detection of pathogen-associated molecular patterns. However, CD14 has been revealed as a multi-talented receptor. In last decade, CD14 was identified to activate NFAT to regulate the life cycle of myeloid cells in a TLR4-independent manner and to transport inflammatory lipids to induce phagocyte hyperactivation. And its influences on multiple related diseases have been further considered. In this review, we summarize advancements in the basic biology of the CD14 including its structure, binding ligands, signaling pathways, and its roles in the pathogenesis of inflammation, atherosclerosis, tumor and metabolic diseases. We also discuss the therapeutic potential of targeting the CD14 in related diseases.

Molecular markers relevant to myocardial injury following dental extraction in patients with or without coronary artery disease

Objectives

The aim of this study was to characterize biological changes following dental extractions in patients with and without coronary artery disease (CAD).

Materials and methods

Forty-five patients (36 males and 9 females) referred for dental extraction underwent treatment and provided blood samples before, immediately after, and 24 h after the procedure. A broad array of biomarkers was employed to assess myocardial injury (highly sensitive troponin T, hs-TnT), bacterial burden (LPS endotoxin activity), and systemic inflammation (CRP, fibrinogen, IFN-γ, IL-1β, IL-6, IL-8, IL-10, IL-12, and TNF-α).

Results

Dental extraction in patients with and without CAD was associated with rises in hs-TnT (p = 0.013), hs-CRP (p < 0.001), fibrinogen (p = 0.005), endotoxin activity (p < 0.001), IFN-γ (p < 0.001), IL-6 (p < 0.001), IL-8 (p = 0.011), and IL-12 (p < 0.001) at 24 h compared with immediately post procedure. Changes in systemic inflammation and endotoxin activity were more evident in those with hs-TnT rise.

Conclusions

Simple dental extractions may cause mild increase in hs-TnT, indicating minor myocardial injury in both patients with and without CAD. Acute systemic inflammation and endotoxemia could represent a possible link between invasive dental treatment and increased risk of acute cardiovascular events. These findings indicate that invasive dental treatment (as simple as a single dental extraction) may impact negatively on clinical outcomes in dental patients, especially those with CAD.

Monocyte-Derived Interleukin-1β As the Driver of S100A12-Induced Sterile Inflammatory Activation of Human Coronary Artery Endothelial Cells: Implications for the Pathogenesis of Kawasaki Disease

OBJECTIVE

Kawasaki disease (KD) is an acute vasculitis of childhood, predominantly affecting the coronary arteries. S100A12, a granulocyte-derived agonist of both the receptor for advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR-4), is strongly up-regulated in KD. This study was undertaken to investigate the potential contributions of S100A12 to the pathogenesis of KD.

METHODS

Serum samples from patients with KD (n = 30) at different stages pre- and post-intravenous immunoglobulin (IVIG) treatment were analyzed for the expression of S100A12, cytokines, chemokines, and soluble markers of endothelial cell activation. Primary human coronary artery endothelial cells (HCAECs) were analyzed for responsiveness to direct stimulation with S100A12 or lipopolysaccharide (LPS), as assessed by real-time quantitative reverse transcription-polymerase chain reaction analysis of cytokine and endothelial cell adhesion molecule messenger RNA expression. Alternatively, HCAECs were cultured in conditioned medium obtained from primary human monocytes that were stimulated with LPS or S100A12 in the absence or presence of IVIG or cytokine antagonists.

RESULTS

In the serum of patients with KD, pretreatment S100A12 levels were associated with soluble vascular cell adhesion molecule 1 titers in the course of IVIG therapy (r_s = -0.6, P = 0.0003). Yet, HCAECs were not responsive to direct S100A12 stimulation, despite the presence of appropriate receptors (RAGE, TLR-4). HCAECs did, however, respond to supernatants obtained from S100A12-stimulated primary human monocytes, as evidenced by the gene expression of inflammatory cytokines and adhesion molecules. This response was strictly dependent on interleukin-1β (IL-1β) signaling (P < 0.001).

CONCLUSION

In its role as a highly expressed mediator of sterile inflammation in KD, S100A12 appears to activate HCAECs in an IL-1β-dependent manner. These data provide new mechanistic insights into the contributions of S100A12 and IL-1β to disease pathogenesis, and may therefore support current IL-1-targeting studies in the treatment of patients with KD.

MiR-590 Inhibits Endothelial Cell Apoptosis by Inactivating the TLR4/NF-κB Pathway in Atherosclerosis

PURPOSE

Previous study has well documented the anti-apoptotic effects of miR-590 on oxidized low-density lipoprotein (ox-LDL)-treated endothelial cells (ECs). However, the mechanism underlying the anti-apoptotic effects of miR-590 in ox-LDL-treated ECs remains to be further addressed.

MATERIALS AND METHODS

ApoE^-/- mice fed with a high-fat diet (HFD) and human aortic endothelial cells (HAECs) treated with ox-LDL were used as in vivo and in vitro models of atherosclerosis. The expressions of miR-590 and toll-like receptor 4 (TLR4) were detected by quantitative real-time PCR and Western blot, respectively. Atherosclerotic lesion analysis was performed using Evans blue and hematoxylin-eosin staining. Cell proliferation was assessed by MTT assay. Apoptosis was examined using flow cytometry analysis and Western blot analysis of Cleaved poly (ADP-ribose) polymerase (PARP) and Cleaved Caspase-3 levels. The effect of miR-590 on TLR4/nuclear factor kappa B (NF-κB) pathway was evaluated by Western blot. Binding between miR-590 and TLR4 was confirmed by luciferase reporter assay and Western blot.

RESULTS

miR-590 was downregulated in the aorta tissues from HFD-fed apoE^-/- mice and ox-LDL-treated HAECs. miR-590 overexpression inhibited atherosclerotic lesion in HFD-induced apoE^-/- mice and promoted proliferation and inhibited apoptosis of ox-LDL-treated HAECs. Additionally, TLR4 was identified as a direct target of miR-590 in ox-LDL-treated HAECs. Moreover, anti-miR-590 reversed TLR4 knockdown-mediated promotion of cell proliferation and suppression of apoptosis in ox-LDL-treated HAECs. miR-590 overexpression suppressed the TLR4/NF-κB pathway, and inhibition of the TLR4/NF-κB pathway promoted cell proliferation and impeded apoptosis in ox-LDL-treated HAECs.

CONCLUSION

miR-590 promoted proliferation and blocked ox-LDL-induced apoptosis in HAECs through inhibition of the TLR4/NF-κB pathway.

IL-1β/MMP9 activation in primary human vascular smooth muscle-like cells: Exploring the role of TNFα and P2X7

BACKGROUND

Vascular smooth muscle cells exhibit phenotypic plasticity in response to microenvironmental stimuli and contribute to vascular remodelling through mechanisms only partially understood. In atherosclerosis, P2X-purinoceptor7 (P2X7) has been related to interleukin-1β (IL-1β) and metalloproteinase 9 (MMP9). The hypoxia-inducible factor-1alpha (HIF1α) was associated to remodelling. Here the activation of IL-1β and MMP9 was studied in relationship to P2X7 and HIF1α in cells exploited from human carotid plaque and internal mammary artery.

METHODS AND RESULTS

Migrating cells expressed HIF1α-regulated canopy FGF-signalling regulator 2 and CD117, and led to primary cells with SMC-like phenotype (VSMC), P2X7⁺. We investigated in VSMC the effects of hypoxia, of treatment with tumour necrosis factor-α (TNFα) and/or with P2X7 antagonist, A740003. Quantitative RT-PCR showed that hypoxia unaffected IL-1β and down-regulated MMP9 mRNAs, without activating HIF1α. TNFα increased IL-1β mRNA via NLR Family Pyrin Domain-Containing 3, with production of proIL-1β but no rise of mature IL-1β. Zymography demonstrated that A740003 triggered MMP9 secretion from VSMC. Combination of A740003 with TNFα abrogated this effect. Combination was ineffective on IL-1β activation elicited by TNFα, but down-regulated HIF1α mRNA. A740003 induced the intracellular P2X7 aggregation and differently perturbed lysosome and mitochondria network compared to TNFα.

CONCLUSIONS

Cells migration from human arteries leads to partially differentiated VSMC analogous to neointimal cells within atherosclerotic lesions. Down-regulated HIF1α in stimulated VSMC translates in resilience in atherosclerotic lesions. P2X7-independent partial activation of IL-1β elicited by TNFα underlines complexity of the cytokine secretion. Data also supported P2X7 as modulator of MMP9 secretion, important for atherosclerosis progression.

Urban particulate matter induces the expression of receptors for early and late adhesion molecules on human monocytes

Exposure to urban particulate matter (PM) is correlated with increases in the emergence of health services due to adverse events and deaths and is mainly related to cardiorespiratory complications. The translocation of particles from the lung into circulation has been proposed as a factor that may trigger systemic effects. Monocytes may be exposed to PM, and if the monocytes are activated, then they are likely to adhere to endothelial cells in a distant organ due to the expression of receptors for adhesion molecules. In the present study, we evaluated the expression of receptors for adhesion molecules (sLe^x, PSGL-1, LFA-1, VLA-4 and α_Vβ₃) in monocytes (U937 cells) exposed for 3 or 18 h to PM₁₀ (0.001, 0.003, 0.010, 0.030, 0.300, 3 or 30 µg/mL). Exposed cells were co-cultured with human endothelial cells that were naive or previously exposed to the same particles. When U937 cells were exposed to PM₁₀, similar levels of expression for early and late receptors for adhesion molecules were observed from 30 ng/mL as those induced by TNF-α. Cells exposed to particles at concentrations above 30 ng/mL were more adhesive to naive or exposed human endothelial cells. Taken together, our results suggest that it is plausible that activated monocytes may play a role in systemic effects induced by PM₁₀ due to the size distribution of the particles and the concentrations required to trigger the expression of receptors for adhesion molecules in monocytes.

The gut microbiota as a novel regulator of cardiovascular function and disease

The gut microbiome has emerged as a critical regulator of human physiology. Deleterious changes to the composition or number of gut bacteria, commonly referred to as gut dysbiosis, has been linked to the development and progression of numerous diet-related diseases, including cardiovascular disease (CVD). Most CVD risk factors, including aging, obesity, certain dietary patterns, and a sedentary lifestyle, have been shown to induce gut dysbiosis. Dysbiosis is associated with intestinal inflammation and reduced integrity of the gut barrier, which in turn increases circulating levels of bacterial structural components and microbial metabolites that may facilitate the development of CVD. The aim of the current review is to summarize the available data regarding the role of the gut microbiome in regulating CVD function and disease processes. Particular emphasis is placed on nutrition-related alterations in the microbiome, as well as the underlying cellular mechanisms by which the microbiome may alter CVD risk.

DC-SIGN and Toll-like receptor 4 mediate oxidized low-density lipoprotein-induced inflammatory responses in macrophages

The regulation of inflammatory responses by innate immune receptors is recognized as a crucial step in the development of atherosclerosis, although the precise molecular mechanisms remain to be elucidated. This study focused on illustrating the roles of dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN)- and Toll-like receptor 4 (TLR4)-regulated inflammatory responses in macrophages. We found that DC-SIGN expression levels were increased in macrophages of atherosclerotic plaques. Oxidized low-density lipoprotein (oxLDL) significantly enhanced DC-SIGN protein expression levels after a short-term exposure. Knockdown of DC-SIGN decreased expression and secretion of interleukin 1-β (IL1-β), monocyte chemo-attractant protein 1 (MCP-1), tumor necrosis factor-α (TNFα) and matrix metalloproteinase-9 (MMP-9). Immunofluorescence studies demonstrated that DC-SIGN and TLR4 co-localized in regions of the plaques. Moreover, DC-SIGN was co-expressed with TLR4 on the plasma membrane after oxLDL stimulation. The presence of an endogenous interaction and the results of the in vitro pull-down assays revealed that DC-SIGN binds directly with TLR4. We also present evidence that DC-SIGN mediates TLR4-regulated NFκB activation but not activation of p38 and JNK. Our results suggest an essential role of DC-SIGN/TLR4 signaling in macrophages in the pathogenesis of atherosclerosis.

Lipopolysaccharide induced vascular smooth muscle cells proliferation: A new potential therapeutic target for proliferative vascular diseases

Vascular smooth muscle cells (VSMCs) proliferation is involved in vascular atherosclerosis and restenosis. Recent studies have demonstrated that lipopolysaccharide (LPS) promotes VSMCs proliferation, but the signalling pathways which are involved are not completely understood. The purpose of this review was to summarize the existing knowledge of the role and molecular mechanisms involved in controlling VSMCs proliferation stimulated by LPS and mediated by toll-like receptor 4 (TLR4) signalling pathways. Moreover, the potential inhibitors of TLR4 signalling for VSMCs proliferation in proliferative vascular diseases are discussed.

SIRT1 regulates lipopolysaccharide-induced CD40 expression in renal medullary collecting duct cells by suppressing the TLR4-NF-κB signaling pathway

AIMS

Recent evidence indicates that sirtuin1 (SIRT1), an NAD⁺-dependent deacetylase, exerts a protective effect against inflammatory kidney injury by suppressing pro-inflammatory cytokines production. The co-stimulatory molecule, CD40, is expressed in a variety of inflammatory diseases in the kidney. Here, we aimed to investigate the potential effect of SIRT1 on CD40 expression induced by lipopolysaccharide (LPS) and to disclose the underlying mechanisms in renal inner medullary collecting duct (IMCD) cells.

MAIN METHODS

mRNA and protein expressions were identified by quantitative real-time PCR and Western blot respectively. Subcellular localization of SIRT1 and CD40 were respectively detected by immunofluorescence and immunohistochemical staining. Small-interfering RNA (siRNA) was carried out for mechanism study.

KEY FINDINGS

LPS reduced SIRT1 expression and up-regulated the expression of CD40, Toll-like receptor 4 (TLR4) and phospho-NF-κBp65 (p-NF-κBp65) in time- and concentration-dependent manners. Moreover, SIRT1 overexpression or activation by SRT1720 diminished the expression of CD40, TLR4 and p-NF-κBp65, which was reversed by SIRT1 siRNA or inhibitors Ex527 and sirtinol in LPS-stimulated IMCD cells. In addition, knockdown of TLR4 decreased the expression of CD40 and p-NF-κBp65 in IMCD cells exposed to LPS. Knockdown of NF-κBp65 or NF-κBp65 inhibition by pyrrolidine dithiocarbamate (PDTC) reduced LPS-induced CD40 expression in IMCD cells. Importantly, the inhibitory effect of SIRT1 on the expression of CD40 and p-NF-κBp65 was augmented by pre-treating with TLR4 siRNA.

SIGNIFICANCE

Our data indicate that SIRT1 inhibits LPS-induced CD40 expression in IMCD cells by suppressing the TLR4-NF-κB signaling pathway, which might provide novel insight into understanding the protective effect of SIRT1 in kidney.

The Anti-Inflammatory Actions of Exercise Training

The list of diseases with a known inflammatory etiology is growing. Cardiovascular disease, osteoporosis, diabetes, geriatric cachexia, and Alzheimer's disease have all been shown to be linked to or exacerbated by aberrantly regulated inflammatory processes. Nevertheless, there is mounting evidence that those who are physically active, or who become physically active, have a reduction in biomarkers associated with chronic inflammation. There was strong early consensus that exercise-induced reductions in inflammation were explained by body mass index or body fatness, but recent studies provide support for the contention that exercise has body fat-independent anti-inflammatory effects. With few exceptions, the anti-inflammatory effects of exercise appear to occur regardless of age or the presence of chronic diseases. What remains unclear are the mechanisms by which exercise training induces these anti-inflammatory effects, but there are several intriguing possibilities, including release of endogenous products, such as heat shock proteins; selective reduction of visceral adipose tissue mass or reducing infiltration of adipocytes by macrophages; shift in immune cell phenotype; cross-tolerizing effects; or exercise-induced shifts in accessory proteins of toll-like receptor signaling. However, future research endeavors are likely to uncover additional potential mechanisms, and it could be some time before functional mechanisms are made clear. In summary, the potential anti-inflammatory influences of exercise training may provide a low-cost, readily available, and effective treatment for low-grade systemic inflammation and could contribute significantly to the positive effects of exercise training on chronic disease.

TLR4-mediated IRAK1 activation induces TNF-α expression via JNK-dependent NF-κB activation in human bronchial epithelial cells

The purpose of this study was to identify the mechanism of lipopolysaccharide (LPS)-induced expression of tumor necrosis factor (TNF)-α in BEAS-2B. Toll-like receptor (TLR)4-specific siRNA was found to completely abolish the LPS-induced expression of MyD88 and TNF-α. There was enhanced binding of MyD88 with IRAK1 following LPS treatment, and MyD88- or IRAK1-specific siRNAs decreased the expression of TNF-α. In addition, IRAK1 siRNA downregulated the phosphorylation of PKCα, demonstrating that PKCα is a downstream effector of IRAK1. Inhibition of PKCα completely blocked the activation of AKT, whereas inhibition of AKT with a PI3K inhibitor prevented the LPS-induced expression of TNF-α. We found that AKT activated JNK, which then stimulated phosphorylation of Iκ-Bα, resulting in NF-κB activation. As expected, inhibition of NF-κB completely inhibited the expression of TNF-α. Taken together, our results suggest that LPS induces TNF-α expression by activating NF-κB via the PKCα/PI3K/AKT/JNK pathway, which is in turn dependent on MyD88/IRAK1.

Biological and Nutritional Properties of Palm Oil and Palmitic Acid: Effects on Health

A growing body of evidence highlights the close association between nutrition and human health. Fat is an essential macronutrient, and vegetable oils, such as palm oil, are widely used in the food industry and highly represented in the human diet. Palmitic acid, a saturated fatty acid, is the principal constituent of refined palm oil. In the last few decades, controversial studies have reported potential unhealthy effects of palm oil due to the high palmitic acid content. In this review we provide a concise and comprehensive update on the functional role of palm oil and palmitic acid in the development of obesity, type 2 diabetes mellitus, cardiovascular diseases and cancer. The atherogenic potential of palmitic acid and its stereospecific position in triacylglycerols are also discussed.

Increasing fat content from 20 to 45 wt% in a complex diet induces lower endotoxemia in parallel with an increased number of intestinal goblet cells in mice

The impacts of high-fat diets (HFDs) on the onset of metabolic endotoxemia and low-grade inflammation are well established in rodent models. However, the dose-effect of dietary lipid intakes on these parameters is not known. We hypothesized that increasing dietary lipid amounts could be linked to parallel increases of endotoxemia, low-grade inflammation, and metabolic and intestinal alterations. Six-week-old male C57BL/6J mice were fed a low-fat diet (LFD, 2.6 wt% of lipids), a moderate HFD (mHFD, 22 wt% of lipids), or a very HFD (vHFD, 45 wt% of lipids) formulated mainly using chow ingredients and milk fat. After 12 weeks, white adipose tissues, liver, intestine, distal colon contents, and plasma were collected. Only vHFD mice significantly increased body weight and fat mass vs LFD mice. This was associated with increases of plasma concentrations of triglycerides, leptin and adiponectin, and liver lipids. No such differences were observed between LFD and mHFD mice. However, mHFD developed metabolic endotoxemia and inflammation, unlike vHFD mice. In turn, vHFD mice showed more goblet cells in all intestine segments vs both other groups and a decrease of Bacteroides-Prevotella in their microbiota vs LFD mice. Finally, mHFD mice colon exhibited a decrease in lactobacilli and in the levels of occludin phosphorylation. Altogether, using complex HFD, no associations were observed between dietary lipid amounts and the magnitude of endotoxemia, inflammation, and physiological alterations developed. These results reveal the impact of the diet composition on intestinal goblet cells and mucus coat, bringing new insights about further consequences on HFD-induced metabolic disorders.

Toll-like receptor 4 mediates inflammatory cytokine secretion in smooth muscle cells induced by oxidized low-density lipoprotein

Oxidized low-density lipoprotein (oxLDL)-regulated secretion of inflammatory cytokines in smooth muscle cells (SMCs) is regarded as an important step in the progression of atherosclerosis; however, its underlying mechanism remains unclear. This study investigated the role of toll-like receptor 4 (TLR4) in oxLDL-induced expression of inflammatory cytokines in SMCs both in vivo and in vitro. We found that the levels of TLR4, interleukin 1-β (IL1-β), tumor necrosis factor-α (TNFα), monocyte chemoattractant protein 1 (MCP-1) and matrix metalloproteinase-2 (MMP-2) expression were increased in the SMCs of atherosclerotic plaques in patients with femoral artery stenosis. In cultured primary arterial SMCs from wild type mice, oxLDL caused dose- and time-dependent increase in the expression levels of TLR4 and cytokines. These effects were significantly weakened in arterial SMCs derived from TLR4 knockout mice (TLR4-/-). Moreover, the secretion of inflammatory cytokines was blocked by TLR4-specific antibodies in primary SMCs. Ox-LDL induced activation of p38 and NFκB was also inhibited in TLR4-/- primary SMCs or when treated with TLR4-specific antibodies. These results demonstrated that TLR4 is a crucial mediator in oxLDL-induced inflammatory cytokine expression and secretion, and p38 and NFκB activation.

Polymorphisms of the LTA gene may contribute to the risk of myocardial infarction: a meta-analysis

Objective

The lymphotoxin-α (LTA), as one of the mediators of inflammation, may play an important role in the pathogenesis of myocardial infarction (MI). Genetic association studies (GAS) that have investigated the association between three common polymorphisms (A252G, G10A and C804A) of the LTA gene and susceptibility to MI have produced contradictory and inconclusive results. The aim of this meta-analysis is to provide a relatively comprehensive account of the association of these polymorphisms with susceptibility to MI.

Methods

A literature search for eligible GAS published before October 15, 2013 was conducted in the PubMed, Embase, Web of Science, Cochrane Library, and CNKI (China National Knowledge Infrastructure) databases. We performed a meta-analysis of fifteen case-control studies with a total of 22,549 MI patients and 16,105 healthy controls.

Results

For LTA A252G, a borderline significant overall association was found, indicating that GG genotype may confer an increased susceptibility to MI compared to AA and AG genotypes. Based on an ethnicity stratification analysis, a significant association was observed in Asians, but not in Caucasians. For LTA G10A, no significant overall association was found. However, subgroup analysis based on ethnicity suggested that the 10A allele may confer a significant increased susceptibility to MI only in Asian populations. For LTA C804A, the combined results revealed a significantly increased susceptibility to MI for carriers of the 804A allele in both overall analysis and stratified analyses.

Conclusion

This meta-analysis shows that LTA C804A may be associated with an increased susceptibility to MI, whereas LTA A252G and G10A may confer a significant increased susceptibility to MI only in Asians. Thus, these polymorphisms of the LTA gene can probably be used with other genetic markers together to identify individuals at high susceptibility to MI especially in Asians.

CD14 contributes to warm hepatic ischemia-reperfusion injury in mice

INTRODUCTION

Ischemia/reperfusion (I/R) of the liver contributes to the pathobiology of liver injury in transplantation, liver surgery, and hemorrhagic shock. Ischemia/reperfusion induces an inflammatory response that is driven, in part, by Toll-like receptor 4 (TLR) signaling. CD14 is known to participate in the function of TLR4. We hypothesized that CD14 would be involved in the pathobiology of warm hepatic I/R.

METHODS

Using a 70% liver inflow inclusion model, CD14 knockout and wild-type (WT) mice were subjected to 1-h warm ischemia followed by reperfusion. CD14 mRNA, circulating transaminase, interleukin 6, soluble CD14, and high-mobility group box 1 (HMGB1) levels were measured. CD14 neutralizing antibody or isotype control antibody was given before ischemia or reperfusion for CD14 blockade in WT mice. Recombinant HMGB1 was given before reperfusion in some experiments to test if liver injury worsens.

RESULTS

There was an upregulation of CD14 mRNA in reperfused livers together with increased soluble CD14 levels in the circulation. Compared with WT control mice, CD14 knockout mice had much lower alanine aminotransferase and interleukin 6 levels at 6 and 24 h following I/R, and much less liver necrosis by histology. TUNEL (terminal deoxynucleotidyl-transferase dUTP nick end labeling) staining displayed less apoptosis at 24 h in the absence of CD14. CD14 blockage by neutralizing antibody also attenuated liver injury and the inflammatory response in C57BL/6 mice following I/R, but did not provide additional protection to TLR4 mutant C3H/Hej mice. CD14 deficiency did not change circulating HMGB1 levels following I/R (6 h). A dose of recombinant HMGB1, which worsened hepatic injury when given before reperfusion in WT mice, did not increase liver damage in CD14-deficient mice.

CONCLUSIONS

CD14 is actively involved in hepatic I/R injury. Its deficiency or blockade ischemia attenuates liver injury and inflammatory response. CD14 mediates liver damage and inflammatory responses in the setting of warm hepatic I/R in mice.

The gut microbiome, kidney disease, and targeted interventions

The human gut harbors >100 trillion microbial cells, which influence the nutrition, metabolism, physiology, and immune function of the host. Here, we review the quantitative and qualitative changes in gut microbiota of patients with CKD that lead to disturbance of this symbiotic relationship, how this may contribute to the progression of CKD, and targeted interventions to re-establish symbiosis. Endotoxin derived from gut bacteria incites a powerful inflammatory response in the host organism. Furthermore, protein fermentation by gut microbiota generates myriad toxic metabolites, including p-cresol and indoxyl sulfate. Disruption of gut barrier function in CKD allows translocation of endotoxin and bacterial metabolites to the systemic circulation, which contributes to uremic toxicity, inflammation, progression of CKD, and associated cardiovascular disease. Several targeted interventions that aim to re-establish intestinal symbiosis, neutralize bacterial endotoxins, or adsorb gut-derived uremic toxins have been developed. Indeed, animal and human studies suggest that prebiotics and probiotics may have therapeutic roles in maintaining a metabolically-balanced gut microbiota and reducing progression of CKD and uremia-associated complications. We propose that further research should focus on using this highly efficient metabolic machinery to alleviate uremic symptoms.

Saturated fatty acid palmitate aggravates neointima formation by promoting smooth muscle phenotypic modulation

OBJECTIVE

Obesity is a major risk factor of atherosclerotic cardiovascular disease. Circulating free fatty acid levels are known to be elevated in obese individuals and, along with dietary saturated fatty acids, are known to associate with cardiovascular events. However, little is known about the molecular mechanisms by which free fatty acids are linked to cardiovascular disease.

APPROACH AND RESULTS

We found that administration of palmitate, a major saturated free fatty acid, to mice markedly aggravated neointima formation induced by carotid artery ligation and that the neointima primarily consisted of phenotypically modulated smooth muscle cells (SMCs). In cultured SMCs, palmitate-induced phenotypic modulation was characterized by downregulation of SMC differentiation markers, such as SM α-actin and SM-myosin heavy chain, and upregulation of mediators involved in inflammation and remodeling of the vessel wall, such as platelet-derived growth factor B and matrix metalloproteinases. We also found that palmitate induced the expression of proinflammatory genes via a novel toll-like receptor 4/myeloid differentiation primary response 88/nuclear factor-κB/NADPH oxidase 1/reactive oxygen species signaling pathway: nuclear factor-κB was activated by palmitate via toll-like receptor 4 and its adapter, MyD88, and once active, it transactivated Nox1, encoding NADPH oxidase 1, a major reactive oxygen species generator in SMCs. Pharmacological inhibition and small interfering RNA-mediated knockdown of the components of this signaling pathway mitigated the palmitate-induced upregulation of proinflammatory genes. More importantly, Myd88 knockout mice were resistant to palmitate-induced exacerbation of neointima formation.

CONCLUSIONS

Palmitate seems to promote neointima formation by inducing inflammatory phenotypes in SMCs.

CD14 directs adventitial macrophage precursor recruitment: role in early abdominal aortic aneurysm formation

Background

Recruitment of macrophage precursors to the adventitia plays a key role in the pathogenesis of abdominal aortic aneurysms (AAAs), but molecular mechanisms remain undefined. The innate immune signaling molecule CD14 was reported to be upregulated in adventitial macrophages in a murine model of AAA and in monocytes cocultured with aortic adventitial fibroblasts (AoAf) in vitro, concurrent with increased interleukin‐6 (IL‐6) expression. We hypothesized that CD14 plays a crucial role in adventitial macrophage precursor recruitment early during AAA formation.

Methods and Results

CD14^−/− mice were resistant to AAA formation induced by 2 different AAA induction models: aortic elastase infusion and systemic angiotensin II (AngII) infusion. CD14 gene deletion led to reduced aortic macrophage infiltration and diminished elastin degradation. Adventitial monocyte binding to AngII‐infused aorta in vitro was dependent on CD14, and incubation of human acute monocytic leukemia cell line‐1 (THP‐1) monocytes with IL‐6 or conditioned medium from perivascular adipose tissue (PVAT) upregulated CD14 expression. Conditioned medium from AoAf and PVAT induced CD14‐dependent monocyte chemotaxis, which was potentiated by IL‐6. CD14 expression in aorta and plasma CD14 levels were increased in AAA patients compared with controls.

Conclusions

These findings link CD14 innate immune signaling via a novel IL‐6 amplification loop to adventitial macrophage precursor recruitment in the pathogenesis of AAA.

Oil composition of high-fat diet affects metabolic inflammation differently in connection with endotoxin receptors in mice

Low-grade inflammation observed in obesity is a risk factor for cardiovascular disease. Recent studies revealed that this would be linked to gut-derived endotoxemia during fat digestion in high-fat diets, but nothing is known about the effect of lipid composition. The study was designed to test the impact of oil composition of high-fat diets on endotoxin metabolism and inflammation in mice. C57/Bl6 mice were fed for 8 wk with chow or isocaloric isolipidic diets enriched with oils differing in fatty acid composition: milk fat, palm oil, rapeseed oil, or sunflower oil. In vitro, adipocytes (3T3-L1) were stimulated or not with lipopolysaccharide (LPS; endotoxin) and incubated with different fatty acids. In mice, the palm group presented the highest level of IL-6 in plasma (P < 0.01) together with the highest expression in adipose tissue of IL-1β and of LPS-sensing TLR4 and CD14 (P < 0.05). The higher inflammation in the palm group was correlated with a greater ratio of LPS-binding protein (LBP)/sCD14 in plasma (P < 0.05). The rapeseed group resulted in higher sCD14 than the palm group, which was associated with lower inflammation in both plasma and adipose tissue despite higher plasma endotoxemia. Taken together, our results reveal that the palm oil-based diet resulted in the most active transport of LPS toward tissues via high LBP and low sCD14 and the greatest inflammatory outcomes. In contrast, a rapeseed oil-based diet seemed to result in an endotoxin metabolism driven toward less inflammatory pathways. This shows that dietary fat composition can contribute to modulate the onset of low-grade inflammation through the quality of endotoxin receptors.

The vascular repair process after injury of the carotid artery is regulated by IL-1RI and MyD88 signalling

AIM

The aim of this study was to determine whether innate immune signalling influences the vascular repair process in response to mechanical injury of arteries in mice.

METHODS AND RESULTS

A non-obstructive collar was introduced around the carotid artery of MyD88-deficient mice, and neointima formation was compared with that observed in MyD88-competent mice. MyD88-deficient mice are characterized by impaired signal transduction from interleukin (IL)-1/IL-18 receptors and most Toll-like receptors (TLRs). The vascular response to injury was severely impaired in MyD88-deficient mice as neointima formation was not different from sham-operated mice, whereas MyD88-competent mice displayed robust neointima formation. Furthermore, infiltration of CD68-positive leucocytes was dependent on MyD88. During the early response to injury, 3 days after collar placement, a transient increase in the expression of TLR4 on vascular smooth muscle cells was observed. To determine the relative importance of IL-1 receptor and TLR4 activation in the vascular response to injury, mice were injected with blocking antibodies to these receptors prior to the collar placement. Neointima formation was reduced by 80% in mice administered IL-1RI blocking antibodies compared with mice given a control antibody, whereas administration of TLR4 blocking antibodies was without effect.

CONCLUSION

These results show that inhibition of MyD88- or IL-1 receptor signalling reduces neointima formation in response to vascular injury and could offer therapeutic options for reducing clinical complications of excessive smooth muscle cell proliferation, such as that observed in in-stent restenosis.

Low level bacterial endotoxin activates two distinct signaling pathways in human peripheral blood mononuclear cells

BACKGROUND

Bacterial endotoxin, long recognized as a potent pro-inflammatory mediator in acute infectious processes, has more recently been identified as a risk factor for atherosclerosis and other cardiovascular diseases. When endotoxin enters the bloodstream, one of the first cells activated is the circulating monocyte, which exhibits a wide range of pro-inflammatory responses.

METHODS

We studied the effect of low doses of E. coli LPS on IL-8 release and superoxide formation by freshly isolated human peripheral blood mononuclear cells (PBMC).

RESULTS

IL-8 release was consistently detectable at 10 pg/ml of endotoxin, reaching a maximum at 1 ng/ml, and was exclusively produced by monocytes; the lymphocytes neither produced IL-8, nor affected monocyte IL-8 release. Superoxide production was detectable at 30 pg/ml of endotoxin, reaching a maximum at 3 ng/ml. Peak respiratory burst activity was seen at 15-20 min, and superoxide levels returned to baseline by 1 h. IL-8 release was dependent on both membrane-associated CD14 (mCD14) and Toll-like receptor 4 (TLR4. Superoxide production was dependent on the presence of LBP, but was not significantly affected by a blocking antibody to TLR4. Moreover, treatment with lovastatin inhibited LPS-dependent IL-8 release and superoxide production.

CONCLUSIONS

These findings suggest that IL-8 release and the respiratory burst are regulated by distinct endotoxin-dependent signaling pathways in PBMC in low level of endotoxin exposure. Selectively modulating these pathways could lead to new approaches to treat chronic inflammatory diseases, such as atherosclerosis, while preserving the capacity of monocytes to respond to acute bacterial infections.

Lipopolysaccharide (LPS) induction of nitric oxide synthase-2 and cyclooxygenase-2 is impaired in fructose overloaded rats

AIMS

Fructose (F) overload in rats induces metabolic dysfunctions that resemble the human metabolic syndrome. In this paper, we aimed to investigate the response of F overload rats to lipopolysaccharide (LPS) challenge in terms of nitric oxide (NO) production and prostanoids (PR) release.

MAIN METHODS

NO blood steady-state concentration was monitored through the detection of nitrosyl-hemoglobin complexes (NO-Hb) by electronic spin resonance. Production of 6-keto PGF(1)α, PGE(2), PGF(2)α and TXB(2) was measured in aorta and mesenteric beds by HPLC. Western blot analysis was used to examine the changes in the expression levels of NOS-2 and COX-2 in aorta.

KEY FINDINGS

Our results showed that increases in NO circulating steady-state concentration and PR production by aorta and mesenteric beds 6h after LPS administration were significantly attenuated in F overload rats with respect to control animals. Oxidative stress parameters were equally affected in the presence or absence of the F treatment. Aorta protein levels of NOS-2 and COX-2, two enzymes inducible by LPS, were significantly lower in F overload rats with respect to control rats at the end of the treatment (-39% and -61% for NOS-2 and COX-2 respectively).

SIGNIFICANCE

These results suggest that the metabolic alterations established by 15 weeks of F overload should affect the response to LPS challenge due to an attenuation in the induction of NOS-2 and COX-2. This effect would be one of the components contributing to abnormalities in the course of the inflammatory response in other conditions associated to insulin resistance, such as diabetes.

Gut microbiota, lipopolysaccharides, and innate immunity in the pathogenesis of obesity and cardiovascular risk

Compelling evidence supports the concepts that gut microbiota actively promotes weight gain and fat accumulation and sustains, indirectly, a condition of low-grade inflammation, thus enhancing the cardiovascular risk. Fewer Bacteroidetes and more Firmicutes seem to characterize the gut microbiota of obese people as compared with that of lean individuals. This difference translates into an increased efficiency of microbiota of obese individuals in harvesting energy from otherwise indigestible carbohydrates. Furthermore, the microbiota also seems able to favor fat accumulation. Indeed, studies performed in germ-free animals have demonstrated that conventionalization of sterile intestine with gut microbiota is associated with an enhanced expression of various lipogenic genes in different tissues, i.e., hepatic, adipose, and muscle tissues. Finally, the microbiota favors systemic exposure to the lipopolysaccharides (LPSs), large glycolipids derived from the outer membrane of Gram-negative bacteria. LPSs can cause a condition of "metabolic endotoxemia" characterized by low-grade inflammation, insulin resistance, and augmented cardiovascular risk. LPSs are a powerful trigger for the innate immune system response. Upon binding to the Toll-like receptor 4 and its coreceptors, LPSs trigger a cascade of responses ultimately resulting in the release of proinflammatory molecules that interfere with modulation of glucose and insulin metabolism, promote development and rupture of the atherosclerotic plaque, and favor progression of fatty liver disease to steatohepatitis. This review gives a comprehensive breakdown of the interaction among gut microbiota, LPSs, and the innate immune system in the development of obesity and promotion of an individual's cardiovascular risk.

Role of toll-like receptor 4 in intimal foam cell accumulation in apolipoprotein E-deficient mice

OBJECTIVE

Atherosclerosis encompasses a conspicuously maladaptive inflammatory response that might involve innate immunity. Here, we compared the role of Toll-like receptor 4 (TLR4) with that of TLR2 in intimal foam cell accumulation and inflammation in apolipoprotein E (ApoE) knockout (KO) mice in vivo and determined potential mechanisms of upstream activation and downstream action.

METHODS AND RESULTS

We measured lipid accumulation and gene expression in the lesion-prone lesser curvature of the aortic arch. TLR4 deficiency reduced intimal lipid by ≈75% in ApoE KO mice, despite unaltered total serum cholesterol and triglyceride levels, whereas TLR2 deficiency reduced it by ≈45%. TLR4 deficiency prevented the increased interleukin-1α (IL-1α) and monocyte chemoattractant protein-1 mRNA levels seen within lesional tissue, and it also lowered serum IL-1α levels. Smooth muscle cells (SMC) were present within the intima of the lesser curvature of the aortic arch at this early lesion stage, and they enveloped and permeated nascent lesions, which consisted of focal clusters of foam cells. Cholesterol enrichment of SMC in vitro stimulated acyl-coenzyme A:cholesterol acyltransferase-1 mRNA expression, cytoplasmic cholesterol ester accumulation, and monocyte chemoattractant protein-1 mRNA and protein expression in a TLR4-dependent manner.

CONCLUSIONS

TLR4 contributes to early-stage intimal foam cell accumulation at lesion-prone aortic sites in ApoE KO mice, as does TLR2 to a lesser extent. Intimal SMC surround and penetrate early lesions, where TLR4 signaling within them may influence lesion progression.

Isolation and characterization of mesenchymal stem cells from the sub-amniotic human umbilical cord lining membrane

The use of human stem cells (SCs) is a promising novel approach for the treatment of many diseases and injuries. Umbilical cord and amniotic membrane represent good sources for SCs, because they are abundant sources and there are less ethical issues unlike embryonic SCs. We aimed to isolate and characterize adult SCs from the subamnion region of the umbilical cord/amniotic membrane. Because mesenchymal stem cells (MSCs) are thought to show less immunogenicity, we first focused on the characterization of MSCs. Significant expression of typical SC-specific markers, such as SSEA-4, Oct-4, and Nanog was observed. Subamniotic MSCs did not lose the expression of Oct-4 and Nanog after freeze-thawing. Cell surface expression of MSC markers (CD73 and CD105) was confirmed by flow cytometry, and cells also differentiated into adipogenic, osteogenic, and chondrogenic lineages. On the other hand, typical embryonic SC-specific markers were not expressed and the cells also did not grow in soft agar. Thus, the subamniotic MSCs are distinct from embryonic SCs and do not show tumorigenicity in vitro. The cord lining membrane (subamniotic) MSCs isolated by our method maintain typical characteristics of MSCs in vitro, but also showed several specific features.

The expression and functions of toll-like receptors in atherosclerosis

Inflammation drives atherosclerosis. Both immune and resident vascular cell types are involved in the development of atherosclerotic lesions. The phenotype and function of these cells are key in determining the development of lesions. Toll-like receptors are the most characterised innate immune receptors and are responsible for the recognition of exogenous conserved motifs on pathogens, and, potentially, some endogenous molecules. Both endogenous and exogenous TLR agonists may be present in atherosclerotic plaques. Engagement of toll-like receptors on immune and resident vascular cells can affect atherogenesis as signalling downstream of these receptors can elicit proinflammatory cytokine release, lipid uptake, and foam cell formation and activate cells of the adaptive immune system. In this paper, we will describe the expression of TLRs on immune and resident vascular cells, highlight the TLR ligands that may act through TLRs on these cells, and discuss the consequences of TLR activation in atherosclerosis.

Lipopolysaccharide, CD14 and Toll-like receptors: an emerging link between innate immunity and atherosclerotic disease

Atherosclerosis and its clinical complications are now understood to be an inflammatory syndrome in which an ongoing systemic inflammatory response is combined with the accumulation of immune cells in the atherosclerotic plaque. Both arms of the immune system, innate and adaptive, have been implicated in contributing to essentially all stages of atherosclerosis, from initiation to progression and, ultimately, atherothrombotic complications. Innate immunity is the first line of defense against invading microorganisms. The recognition units of the innate immune system are designed to respond to molecular patterns shared by a variety of infectious microorganisms, such as bacterial lipopolysaccharide. Numerous basic and clinical studies have provided evidence that responsiveness to lipopolysaccharide may be correlated to the risk of atherosclerotic disease. The molecular basis of this connection appears to lie in Toll-like receptors that are expressed on cells of the innate immune system, bind to lipopolysaccharide, and thus determine the strength of antibacterial immune responses in the host. Variations in the function of Toll-like receptors and their signaling pathways are now suspected to play a critical role in determining the risk of atherosclerosis. This review summarizes recent research advances exploring the role of innate immunity, particularly lipopolysaccharide, CD14 and Toll-like receptors, in the initiation and development of atherosclerotic disease.

Toll like receptor 4 in atherosclerosis and plaque destabilization

The immune system plays a pivotal role in initiation and progression of atherosclerosis. Monocytes and T-lymphocytes are the first cells to enter the damaged endothelium. Differentiation of monocytes into macrophages and ingestion of lipids by these macrophages turning them into foam cells is a crucial step in the development of a fatty streak, the first sign of atherosclerosis. In recent years there has been accumulating evidence for the involvement of Toll like receptor 4, a pattern recognition receptor of the innate immune system, in the pathogenesis of atherosclerosis. Different cell types present in the atherosclerotic plaque express TLR4 and several pro-atherogenic ligands have been shown to activate TLR4. The innate immune system and the TLR signaling cascade may play an important role not only in the pathogenesis of atherosclerosis, but also in plaque destabilization. In this review, we discuss the role of TLR4 in the pathogenesis of atherosclerosis and vulnerable plaque development.

Molecular pathways mediating differential responses to lipopolysaccharide between human and baboon arterial endothelial cells

1. Vascular inflammation plays a critical role in atherogenesis. Previously, we showed that baboon arterial endothelial cells (BAEC) were hyporesponsive to lipopolysaccharide (LPS) compared with human arterial endothelial cells (HAEC). 2. In the present study, we investigated mechanisms underlying differential responses between HAEC and BAEC to tumour necrosis factor (TNF)-alpha and LPS. 3. Both HAEC and BAEC responded similarly to TNF-alpha. However, BAEC showed retarded responses to LPS in expression of E-selectin, intercellular adhesion molecule-1, monocyte chemotactic protein-1 and interleukin-8 (P < 0.05). These changes were confirmed at the mRNA level. Tumour necrosis factor-alpha activated nuclear factor-kappaB members such as p50, p52, p65, c-rel and RelB in both HAEC and BAEC. In contrast, LPS activated p50 and p65 only in HAEC. Using microarray assays, we found that TNF receptor-associated factor 2 (TRAF-2), TNF receptor superfamily, member 1A-associated via death domain (TRADD) and nuclear factors such as nuclear factor of kappa in B-cells inhibitor, alpha (NFKBIA) and nuclear factor of kappa in B-cells inhibitor, beta (NFKBIB) were upregulated by LPS only in HAEC. Although the baseline expression of Toll-like receptor (TLR) 4 was low in both HAEC and BAEC, TNF-alpha activated TLR4 expression in both cell types. Although LPS increased TLR4 expression only in HAEC, human and baboon peripheral blood mononuclear cells exhibited similar TLR4 expression and response to LPS. Transfecting BAEC with TLR4/myeloid differentiation protein-2 overexpression vector conferred BAEC responsiveness to LPS. 4. The findings of the present study indicate that an altered TLR4 system may be responsible for the resistance of baboon endothelial cells to LPS. Given the importance of TLR4 in human immune responses and vascular diseases, the natural resistance of baboons to LPS/TLR4-initiated inflammation could make the baboon a valuable animal model in which to study how inflammation affects atherogenesis.