Proinflammatory phenotype of vascular smooth muscle cells: role of efficient Toll-like receptor 4 signaling

Current Progress in the Science of Novel Adjuvant Nano-Vaccine-Induced Protective Immune Responses

Vaccinations are vital as they protect us from various illness-causing agents. Despite all the advancements in vaccine-related research, developing improved and safer vaccines against devastating infectious diseases including Ebola, tuberculosis and acquired immune deficiency syndrome (AIDS) remains a significant challenge. In addition, some of the current human vaccines can cause adverse reactions in some individuals, which limits their use for massive vaccination program. Therefore, it is necessary to design optimal vaccine candidates that can elicit appropriate immune responses but do not induce side effects. Subunit vaccines are relatively safe for the vaccination of humans, but they are unable to trigger an optimal protective immune response without an adjuvant. Although different types of adjuvants have been used for the formulation of vaccines to fight pathogens that have high antigenic diversity, due to the toxicity and safety issues associated with human-specific adjuvants, there are only a few adjuvants that have been approved for the formulation of human vaccines. Recently, nanoparticles (NPs) have gain specific attention and are commonly used as adjuvants for vaccine development as well as for drug delivery due to their excellent immune modulation properties. This review will focus on the current state of adjuvants in vaccine development, the mechanisms of human-compatible adjuvants and future research directions. We hope this review will provide valuable information to discovery novel adjuvants and drug delivery systems for developing novel vaccines and treatments.

Vascular disease persistence in giant cell arteritis: are stromal cells neglected?

Giant cell arteritis (GCA), the most common systemic vasculitis, is characterised by aberrant interactions between infiltrating and resident cells of the vessel wall. Ageing and breach of tolerance are prerequisites for GCA development, resulting in dendritic and T-cell dysfunction. Inflammatory cytokines polarise T-cells, activate resident macrophages and synergistically enhance vascular inflammation, providing a loop of autoreactivity. These events originate in the adventitia, commonly regarded as the biological epicentre of the vessel wall, with additional recruitment of cells that infiltrate and migrate towards the intima. Thus, GCA-vessels exhibit infiltrates across the vascular layers, with various cytokines and growth factors amplifying the pathogenic process. These events activate ineffective repair mechanisms, where dysfunctional vascular smooth muscle cells and fibroblasts phenotypically shift along their lineage and colonise the intima. While high-dose glucocorticoids broadly suppress these inflammatory events, they cause well known deleterious effects. Despite the emerging targeted therapeutics, disease relapse remains common, affecting >50% of patients. This may reflect a discrepancy between systemic and local mediators of inflammation. Indeed, temporal arteries and aortas of GCA-patients can show immune-mediated abnormalities, despite the treatment induced clinical remission. The mechanisms of persistence of vascular disease in GCA remain elusive. Studies in other chronic inflammatory diseases point to the fibroblasts (and their lineage cells including myofibroblasts) as possible orchestrators or even effectors of disease chronicity through interactions with immune cells. Here, we critically review the contribution of immune and stromal cells to GCA pathogenesis and analyse the molecular mechanisms by which these would underpin the persistence of vascular disease.

Effect of reactive oxygen, nitrogen, and sulfur species on signaling pathways in atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which fats, lipids, cholesterol, calcium, proliferating smooth muscle cells, and immune cells accumulate in the intima of the large arteries, forming atherosclerotic plaques. A complex interplay of various vascular and immune cells takes place during the initiation and progression of atherosclerosis. Multiple reports indicate that tight control of reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) production is critical for maintaining vascular health. Unrestricted ROS and RNS generation may lead to activation of various inflammatory signaling pathways, facilitating atherosclerosis. Given these deleterious consequences, it is important to understand how ROS and RNS affect the signaling processes involved in atherogenesis. Conversely, RSS appears to exhibit an atheroprotective potential and can alleviate the deleterious effects of ROS and RNS. Herein, we review the literature describing the effects of ROS, RNS, and RSS on vascular smooth muscle cells, endothelial cells, and macrophages and focus on how changes in their production affect the initiation and progression of atherosclerosis. This review also discusses the contribution of ROS, RNS, and RSS in mediating various post-translational modifications, such as oxidation, nitrosylation, and sulfation, of the molecules involved in inflammatory signaling.

Modulation of Smooth Muscle Cell Phenotype for Translation of Tissue-Engineered Vascular Grafts

Translation of small-diameter tissue-engineered vascular grafts (TEVGs) for the treatment of coronary artery disease (CAD) remains an unfulfilled promise. This is largely due to the limited integration of TEVGs into the native vascular wall-a process hampered by the insufficient smooth muscle cell (SMC) infiltration and extracellular matrix deposition, and low vasoactivity. These processes can be promoted through the judicious modulation of the SMC toward a synthetic phenotype to promote remodeling and vascular integration; however, the expression of synthetic markers is often accompanied by a decrease in the expression of contractile proteins. Therefore, techniques that can precisely modulate the SMC phenotypical behavior could have the potential to advance the translation of TEVGs. In this review, we describe the phenotypic diversity of SMCs and the different environmental cues that allow the modulation of SMC gene expression. Furthermore, we describe the emerging biomaterial approaches to modulate the SMC phenotype in TEVG design and discuss the limitations of current techniques. In addition, we found that current studies in tissue engineering limit the analysis of the SMC phenotype to a few markers, which are often the characteristic of early differentiation only. This limited scope has reduced the potential of tissue engineering to modulate the SMC toward specific behaviors and applications. Therefore, we recommend using the techniques presented in this review, in addition to modern single-cell proteomics analysis techniques to comprehensively characterize the phenotypic modulation of SMCs. Expanding the holistic potential of SMC modulation presents a great opportunity to advance the translation of living conduits for CAD therapeutics.

Next-Generation Adjuvants: Applying Engineering Methods to Create and Evaluate Novel Immunological Responses

Adjuvants are a critical component of vaccines. Adjuvants typically target receptors that activate innate immune signaling pathways. Historically, adjuvant development has been laborious and slow, but has begun to accelerate over the past decade. Current adjuvant development consists of screening for an activating molecule, formulating lead molecules with an antigen, and testing this combination in an animal model. There are very few adjuvants approved for use in vaccines, however, as new candidates often fail due to poor clinical efficacy, intolerable side effects, or formulation limitations. Here, we consider new approaches using tools from engineering to improve next-generation adjuvant discovery and development. These approaches will create new immunological outcomes that will be evaluated with novel diagnostic tools. Potential improved immunological outcomes include reduced vaccine reactogenicity, tunable adaptive responses, and enhanced adjuvant delivery. Evaluations of these outcomes can leverage computational approaches to interpret "big data" obtained from experimentation. Applying engineering concepts and solutions will provide alternative perspectives, further accelerating the field of adjuvant discovery.

Aging of the Arterial System

Aging of the vascular system is associated with deep changes of the structural proprieties of the arterial wall. Arterial hypertension, diabetes mellitus, and chronic kidney disease are the major determinants for the loss of elasticity and reduced compliance of vascular wall. Arterial stiffness is a key parameter for assessing the elasticity of the arterial wall and can be easily evaluated with non-invasive methods, such as pulse wave velocity. Early assessment of vessel stiffness is critical because its alteration can precede clinical manifestation of cardiovascular disease. Although there is no specific pharmacological target for arterial stiffness, the treatment of its risk factors helps to improve the elasticity of the arterial wall.

Cardiomyocyte-specific deletion of TLR4 attenuates angiotensin II-induced hypertension and cardiac remodeling

Toll-like receptor 4 (TLR4) is an integral factor in the initiation of the innate immune response and plays an important role in cardiovascular diseases such as hypertension and myocardial infarction. Previous studies from our lab demonstrated that central TLR4 blockade reduced cardiac TLR4 expression, attenuated hypertension, and improved cardiac function. However, the contribution of cardiac specific TLR4 to the development of hypertension and cardiac remodeling is unknown. Therefore, we hypothesized that cardiomyocyte specific knockdown of TLR4 would have beneficial effects on hypertension, cardiac hypertrophy, and remodeling. To test this hypothesis, cardiomyocyte-specific TLR4 knockdown (cTLR4KO) mice were generated by crossing floxed TLR4 mice with Myh6-Cre mice, and subjected to angiotensin II (Ang II, 1 µg/kg/min or vehicle for 14 days) hypertension model. Blood pressure measurements using radio telemetry revealed no differences in baseline mean arterial pressure between control littermates and cTLR4KO mice (103 ± 2 vs. 105 ± 3 mmHg, p > 0.05). Ang II-induced hypertension (132 ± 2 vs. 151 ± 3 mmHg, p < 0.01) was attenuated and cardiac hypertrophy (heart/body weight; 4.7 vs. 5.8 mg/g, p < 0.01) was prevented in cTLR4KO mice when compared with control mice. In addition, the level of myocardial fibrosis was significantly reduced, and the cardiac function was improved in cTLR4KO mice infused with Ang II. Furthermore, cardiac inflammation, as evidenced by elevated gene expression of TNF, IL-6, and MCP-1 in the left ventricle, was attenuated in cTLR4KO mice infused with Ang II. Together, this data revealed a protective role for cardiomyocyte-specific deletion of TLR4 against Ang II-induced hypertension and cardiac dysfunction through inhibition of proinflammatory cytokines.

Anastellin impacts on the processing of extracellular matrix fibronectin and stimulates release of cytokines from coronary artery smooth muscle cells

Anastellin, a recombinant protein fragment from the first type III module of fibronectin, mimics a partially unfolded intermediate implicated in the assembly of fibronectin fibrils. Anastellin influences the structure of fibronectin and initiates in vitro fibrillation, yielding "superfibronectin", a polymer with enhanced cell-adhesive properties. This ability is absent in an anastellin double mutant, L37AY40A. Here we demonstrate that both wild-type and L37AY40A anastellin affect fibronectin processing within the extracellular matrix (ECM) of smooth muscle cells. Fibronectin fibrils are diminished in the ECM from cells treated with anastellin, but are partially rescued by supplementation with plasma fibronectin in cell media. Proteomic analyses reveal that anastellin also impacts on the processing of other ECM proteins, with increased collagen and decreased laminin detected in media from cells exposed to wild-type anastellin. Moreover, both anastellin forms stimulate release of inflammatory cytokines, including interleukin 6. At the molecular level, L37AY40A does not exhibit major perturbations of structural features relative to wild-type anastellin, though the mutant showed differences in heparin binding characteristics. These findings indicate that wild-type and L37AY40A anastellin share similar molecular features but elicit slightly different, but partially overlapping, responses in smooth muscle cells resulting in altered secretion of cytokines and proteins involved in ECM processing.

Lipopolysaccharides and Cellular Senescence: Involvement in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the vascular walls related to aging. Thus far, the roles of cellular senescence and bacterial infection in the pathogenesis of atherosclerosis have been speculated to be independent of each other. Some types of macrophages, vascular endothelial cells, and vascular smooth muscle cells are in a senescent state at the sites of atherosclerotic lesions. Likewise, bacterial infections and accumulations of lipopolysaccharide (LPS), an outer-membrane component of Gram-negative bacteria, have also been observed in the atherosclerotic lesions of patients. This review introduces the integration of these two potential pathways in atherosclerosis. Previous studies have suggested that LPS directly induces cellular senescence in cultured monocytes/macrophages and vascular cells. In addition, LPS enhances the inflammatory properties (senescence-associated secretory phenotype [SASP]) of senescent endothelial cells. Thus, LPS derived from Gram-negative bacteria could exaggerate the pathogenesis of atherosclerosis by inducing and enhancing cellular senescence and the SASP-associated inflammatory properties of specific vascular cells in atherosclerotic lesions. This proposed mechanism can provide novel approaches to preventing and treating this common age-related disease.

The Multi-Functional Roles of CCR7 in Human Immunology and as a Promising Therapeutic Target for Cancer Therapeutics

An important hallmark of the human immune system is to provide adaptive immunity against pathogens but tolerance toward self-antigens. The CC-chemokine receptor 7 (CCR7) provides a significant contribution in guiding cells to and within lymphoid organs and is important for acquiring immunity and tolerance. The CCR7 holds great importance in establishing thymic architecture and function and naïve and regulatory T-cell homing in the lymph nodes. Similarly, the receptor is a key regulator in cancer cell migration and the movement of dendritic cells. This makes the CCR7 an important receptor as a drug and prognostic marker. In this review, we discussed several biological roles of the CCR7 and its importance as a drug and prognostic marker.

Magnesium supplementation reduces inflammation in rats with induced chronic kidney disease

BACKGROUND

Inflammation is a common feature in chronic kidney disease (CKD) that appears specifically associated with cardiovascular derangements in CKD patients. Observational studies have revealed a link between low Mg levels and inflammation. In this study, we hypothesize that Mg might have a modulatory effect on the inflammation induced under the uraemic milieu.

METHODS

In vivo studies were performed in a 5/6 nephrectomized rat model of CKD. Furthermore, a possible direct effect of Mg was addressed through in vitro studies with vascular smooth muscle cells (VSMCs).

RESULTS

Uraemic rats fed a normal (0.1%) Mg diet showed a systemic inflammatory response evidenced by the elevation in plasma of the pro-inflammatory cytokines TNF-α, IL-1β and IL-6, and GPx activity, a marker of oxidative stress. Importantly, an increased expression of these cytokines in the aortic tissue was also observed. In contrast, a dietary Mg supplementation (0.6%) greatly prevented the oxidative stress and the pro-inflammatory response. In vitro, in VSMCs cultured in a pro-inflammatory high phosphate medium, incubation with Mg 1.6 mM inhibited the increase in the production of ROS, the rise in the expression of TNF-α, IL-1β, IL-6 and IL-8 and the activation of NF-κB signalling that was observed in cells incubated with a normal (0.8 mM) Mg.

CONCLUSION

Mg supplementation reduced inflammation associated with CKD, exerting a direct effect on vascular cells. These findings support a possible beneficial effect of Mg supplementation along the clinical management of CKD patients.

Carbon Monoxide-Releasing Molecule-2 Ameliorates Particulate Matter-Induced Aorta Inflammation via Toll-Like Receptor/NADPH Oxidase/ROS/NF-κB/IL-6 Inhibition

Particulate matter (PM), a major air pollutant, may be associated with adverse cardiovascular effects. Reactive oxygen species- (ROS-) dependent proinflammatory cytokine production, such as interleukin-6 (IL-6), is a possible underlying mechanism. Carbon monoxide- (CO-) releasing molecule-2 (CORM-2) which liberates exogenous CO can exert many beneficial effects, particularly anti-inflammation and antioxidant effects. The purpose of this study was to explore the protective effects and underpinning mechanisms of CORM-2 on PM-induced aorta inflammation. Here, human aortic vascular smooth muscle cells (HASMCs) were utilized as in vitro models for the assessment of signaling pathways behind CORM-2 activities against PM-induced inflammatory responses, including Toll-like receptors (TLRs), NADPH oxidase, ROS, nuclear factor-kappa B (NF-κB), and IL-6. The modulation of monocyte adherence and HASMC migration, that are two critical cellular events of inflammatory process, along with their regulators, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and matrix metalloproteinase-2 (MMP-2) and MMP-9, in response to PM by CORM-2, were further evaluated. Finally, mice experiments under different conditions were conducted for the in vivo evaluation of CORM-2 benefits on the expression of inflammatory molecules including IL-6, ICAM-1, VCAM-1, MMP-2, and MMP-9. Our results found that PM could induce aorta inflammation in vitro and in vivo, as evidenced by the increase of IL-6 expression that was regulated by the TLR2 and TLR4/NADPH oxidase/ROS/NF-κB signaling pathway, thereby promoting ICAM-1- and VCAM-1-dependent monocyte adhesion and MMP-2- and MMP-9-dependent HASMC migration. Importantly, our experimental models demonstrated that CORM-2-liberated CO effectively inhibited the whole identified PM-induced inflammatory cascade in HASMCs and tissues. In conclusion, CORM-2 treatment may elicit multiple beneficial effects on inflammatory responses of aorta due to PM exposure, thereby providing therapeutic value in the context of inflammatory diseases of the cardiovascular system.

Novel Targets for Hypertension Drug Discovery

PURPOSE OF REVIEW

Despite the availability of various medications and prescribing combination therapies, uncontrolled blood pressure and resistance are observed in more than 40% of patients. The purpose of this review is to discuss emerging novel approaches for the treatment of hypertension and propose future research and clinical directions.

RECENT FINDINGS

Hypertension is a common disease of the cardiovascular system which may arise solely or as a comorbidity of other disorders. It is a crucial risk factor for cardiovascular diseases such as coronary artery disease, myocardial infarction, congestive heart failure, renal failure, and stroke. The results from current literature regarding the novel approaches showed several targets that could be explored as potential therapeutic options. These include toll-like receptor 4, a critical regulator of angiotensin II-induced hypertension; protease-activated receptor 2, which promotes collagen deposition and inflammatory responses; chemerin, which causes metabolic and obesity-associated hypertension; apelin receptor; transient receptor potential melastatin; urotensin-II; and Tie2 receptor. This review discusses various targets and pathways that could be emerging pharmacological therapies for hypertension.

Pyroptosis is a critical immune-inflammatory response involved in atherosclerosis

Pyroptosis is a form of programmed cell death activated by various stimuli and is characterized by inflammasome assembly, membrane pore formation, and the secretion of inflammatory cytokines (IL-1β and IL-18). Atherosclerosis-related risk factors, including oxidized low-density lipoprotein (ox-LDL) and cholesterol crystals, have been shown to promote pyroptosis through several mechanisms that involve ion flux, ROS, endoplasmic reticulum stress, mitochondrial dysfunction, lysosomal rupture, Golgi function, autophagy, noncoding RNAs, post-translational modifications, and the expression of related molecules. Pyroptosis of endothelial cells, macrophages, and smooth muscle cells in the vascular wall can induce plaque instability and accelerate atherosclerosis progression. In this review, we focus on the pathogenesis, influence, and therapy of pyroptosis in atherosclerosis and provide novel ideas for suppressing pyroptosis and the progression of atherosclerosis.

Adipokines in vascular calcification

Adipose tissue (AT), a critical endocrine gland, is capable of producing and secreting abundant adipokines. Adipokines act on distant or adjacent organ tissues via paracrine, autocrine, and endocrine mechanism, which play attractive roles in the regulation of glycolipid metabolism and inflammatory response. Increasing evidence shows that adipokines can connect obesity with cardiovascular diseases by serving as promoters or inhibitors in vascular calcification. The chronic hypoxia in AT, caused by the adipocyte hypertrophy, is able to trigger imbalanced adipokine generation, which leads to apoptosis, osteogenic differentiation of vascular smooth muscle cells (VSMCs), vascular inflammation, and abnormal deposition of calcium and phosphorus in the vessel wall. The objectives of this review aim at providing a brief summary of the crucial influence of major adipokines on the formation and development of vascular calcification, which may contribute to better understanding these adipokines for establishing the appropriate therapeutic strategies to counteract obesity-associated vascular calcification.

Effect of EZH2 on pulmonary artery smooth muscle cell migration in pulmonary hypertension

Pulmonary hypertension (PH) is a life‑threatening disease that often involves vascular remodeling. Although pulmonary arterial smooth muscle cells (PASMCs) are the primary participants in vascular remodeling, their biological role is not entirely clear. The present study analyzed the role of enhancer of zeste homolog 2 (EZH2) in vascular remodeling of PH by investigating the behavior of PASMCs. The expression levels of EZH2 in PASMCs in chronic thromboembolic pulmonary hypertension (CTEPH), a type of PH, were detected. The role of EZH2 in PASMC migration was investigated by wound‑healing assay following overexpression and knockdown. Functional enrichment analysis of the whole‑genome expression profiles of PASMCs with EZH2 overexpression was performed using an mRNA Human Gene Expression Microarray. Quantitative (q)PCR was performed to confirm the results of the microarray. EZH2 expression levels increased in CTEPH cell models. The overexpression of EZH2 enhanced PASMC migration compared with control conditions. Functional enrichment analysis of the differentially expressed genes following EZH2 overexpression indicated a strong link between EZH2 and the immune inflammatory response and oxidoreductase activity in PASMCs. mRNA expression levels of superoxide dismutase 3 were verified by qPCR. The results suggested that EZH2 was involved in the migration of PASMCs in PH, and may serve as a potential target for the treatment of PH.

Extreme Diversity of the Human Vascular Mesenchymal Cell Landscape

Background Human mesenchymal cells are culprit factors in vascular (patho)physiology and are hallmarked by phenotypic and functional heterogeneity. At present, they are subdivided by classic umbrella terms, such as "fibroblasts," "myofibroblasts," "smooth muscle cells," "fibrocytes," "mesangial cells," and "pericytes." However, a discriminative marker-based subclassification has to date not been established. Methods and Results As a first effort toward a classification scheme, a systematic literature search was performed to identify the most commonly used phenotypical and functional protein markers for characterizing and classifying vascular mesenchymal cell subpopulation(s). We next applied immunohistochemistry and immunofluorescence to inventory the expression pattern of identified markers on human aorta specimens representing early, intermediate, and end stages of human atherosclerotic disease. Included markers comprise markers for mesenchymal lineage (vimentin, FSP-1 [fibroblast-specific protein-1]/S100A4, cluster of differentiation (CD) 90/thymocyte differentiation antigen 1, and FAP [fibroblast activation protein]), contractile/non-contractile phenotype (α-smooth muscle actin, smooth muscle myosin heavy chain, and nonmuscle myosin heavy chain), and auxiliary contractile markers (h1-Calponin, h-Caldesmon, Desmin, SM22α [smooth muscle protein 22α], non-muscle myosin heavy chain, smooth muscle myosin heavy chain, Smoothelin-B, α-Tropomyosin, and Telokin) or adhesion proteins (Paxillin and Vinculin). Vimentin classified as the most inclusive lineage marker. Subset markers did not separate along classic lines of smooth muscle cell, myofibroblast, or fibroblast, but showed clear temporal and spatial diversity. Strong indications were found for presence of stem cells/Endothelial-to-Mesenchymal cell Transition and fibrocytes in specific aspects of the human atherosclerotic process. Conclusions This systematic evaluation shows a highly diverse and dynamic landscape for the human vascular mesenchymal cell population that is not captured by the classic nomenclature. Our observations stress the need for a consensus multiparameter subclass designation along the lines of the cluster of differentiation classification for leucocytes.

The role of toll-like receptor 4 (TLR4) in cancer progression: A possible therapeutic target?

The toll-like receptor (TLR) family consists of vital receptors responsible for pattern recognition in innate immunity, making them the core proteins involved in pathogen detection and eliciting immune responses. The most studied member of this family, TLR4, has been the center of attention regarding its contributory role in many inflammatory diseases including sepsis shock and asthma. Notably, mounting pieces of evidence have proved that this receptor is aberrantly expressed on the tumor cells and the tumor microenvironment in a wide range of cancer types and it is highly associated with the initiation of tumorigenesis as well as tumor progression and drug resistance. Cancer therapy using TLR4 inhibitors has recently drawn scientists' attention, and the promising results of such studies may pave the way for more investigation in the foreseeable future. This review will introduce the key proteins of the TLR4 pathway and how they interact with major growth factors in the tumor microenvironment. Moreover, we will discuss the many aspects of tumor progression affected by the activation of this receptor and provide an overview of the recent therapeutic approaches using various TLR4 antagonists.

Biomechanical signal communication in vascular smooth muscle cells

Biomechanical stresses are closely associated with cardiovascular development and diseases. In vivo, vascular smooth muscle cells are constantly stimulated by biomechanical factors caused by increased blood pressure leading to the non-specific activation of cell transmembrane proteins. Thus, various intracellular signal molecules are simultaneously activated via signaling cascades, which are closely related to alterations in the differentiation, phenotype, inflammation, migration, pyroptosis, calcification, proliferation, and apoptosis of vascular smooth muscle cells. Meanwhile, mechanical stress-induced miRNAs and epigenetics modification on vascular smooth muscle cells play critical roles as well. Eventually, the overall pathophysiology of the cells is altered, resulting in the development of many major clinical diseases, including hypertension, atherosclerosis, grafted venous atherosclerosis, and aneurysm, among others. In this paper, important advances in mechanical signal communication in vascular smooth muscle cells are reviewed.

Lipopolysaccharide exposure modulates the contractile and migratory phenotypes of vascular smooth muscle cells

INTRODUCTION

Sepsis survivors are at higher risk for cardiovascular events. Lipopolysaccharide (LPS) activates Toll-like receptor 4 (TLR4) in sepsis. Activation of TLR4 modulates vascular smooth muscle cells (VSMCs) phenotype and contributes to cardiovascular changes after sepsis.

AIM

Investigate changes in VSMCs phenotype caused by LPS-induced TLR4 activation.

METHODS

Rat VSMCs were incubated with LPS. Two incubation conditions were used in cell contraction and migration assays: acute stimulation - LPS stimulus was initiated at the beginning of the assay and maintained throughout; and preconditioning - LPS stimulation was applied prior to the assay then discontinued. Nitric oxide (NO) production, mRNA expression of cytokines and phenotype markers, and interleukin (IL)-6 production were evaluated.

KEY FINDINGS

LPS increased gene expression of IL-1β, IL-6, TNFα and MCP-1 (p < .001), of secretory phenotype markers collagen and vimentin (p < .0479) and of the contractile marker smooth muscle 22α (SM22α) (p = .0067). LPS exposure increased IL-6 secretion after 24 and 48 h (p < .0001), and NO at 8 and 24 h (p < .0249) via inducible nitric oxide synthase (iNOS), as demonstrated by a decrease in NO after incubation with aminoguanidine. Acute stimulation with LPS reduced migration and contraction in a NO-dependent manner, while preconditioning with LPS increased both in an IL-6-dependent manner.

SIGNIFICANCE

LPS affects VSMCs by modulating their secretory, contractile and migratory phenotypes. LPS acute stimulation of VSMCs promoted a NO-dependent reduction in migration and contraction, while preconditioning with LPS promoted IL-6-dependent increases in migration and contraction, evidencing that VSMCs can present phenotype modifications that persist after sepsis, thereby contributing to postsepsis cardiovascular events.

Vascular smooth muscle-MAPK14 is required for neointimal hyperplasia by suppressing VSMC differentiation and inducing proliferation and inflammation

Injury-induced stenosis is a serious vascular complication. We previously reported that p38α (MAPK14), a redox-regulated p38MAPK family member was a negative regulator of the VSMC contractile phenotype in vitro. Here we evaluated the function of VSMC-MAPK14 in vivo in injury-induced neointima hyperplasia and the underlying mechanism using an inducible SMC-MAPK14 knockout mouse line (iSMC-MAPK14^-/-). We show that MAPK14 expression and activity were induced in VSMCs after carotid artery ligation injury in mice and ex vivo cultured human saphenous veins. While the vasculature from iSMC-MAPK14^-/- mice was indistinguishable from wildtype littermate controls at baseline, these mice exhibited reduced neointima formation following carotid artery ligation injury. Concomitantly, there was an increased VSMC contractile protein expression in the injured vessels and a decrease in proliferating cells. Blockade of MAPK14 through a selective inhibitor suppressed, while activation of MAPK14 by forced expression of an upstream MAPK14 kinase promoted VSMC proliferation in cultured VSMCs. Genome wide RNA array combined with VSMC lineage tracing studies uncovered that vascular injury evoked robust inflammatory responses including the activation of proinflammatory gene expression and accumulation of CD45 positive inflammatory cells, which were attenuated in iSMC-MAPK14^-/- mice. Using multiple pharmacological and molecular approaches to manipulate MAPK14 pathway, we further confirmed the critical role of MAPK14 in activating proinflammatory gene expression in cultured VSMCs, which occurs in a p65/NFkB-dependent pathway. Finally, we found that NOX4 contributes to MAPK14 suppression of the VSMC contractile phenotype. Our results revealed that VSMC-MAPK14 is required for injury-induced neointima formation, likely through suppressing VSMC differentiation and promoting VSMC proliferation and inflammation. Our study will provide mechanistic insights into therapeutic strategies for mitigation of vascular stenosis.

Immune cells and vasa vasorum in the tunica media of atherosclerotic coronary arteries

In coronary artery disease (CAD), the disruption of the tunica media immune privilege manifests as increased leukocyte infiltration and the formation of vasa vasorum. We aimed to characterize the immune privilege status of the tunica media in human coronary arteries (CAs) with atherosclerotic plaques, by comparing the abundance and composition of immune-cell infiltrates within the individual arterial-wall layers, and by evaluating vasa vasorum neovascularization of the tunica media. The tissue samples were obtained from 36 symptomatic patients with diffuse CAD (aged 60-72 years) who underwent coronary endarterectomy. T and B cells, macrophages and endothelial cells in the CAs were detected by immunohistochemistry. Morphological analysis of CAs showed significant atherosclerotic changes in all specimens. In the media, we observed damage and loss of smooth muscle cells, destruction of the extracellular matrix architecture, and fibrosis. There were 43.3% of immune cells in the intima, 50% in the adventitia, and 6.7% in the media. In the media, 51.1% of the immune cells were T cells (p ˂ 0.001 compared to B cells and macrophages; ANOVA, Scheffe post hoc analysis), 23.5% were B cells, and 25.4% were macrophages. The number of vasa vasorum in the media was 1 in 38.9% of CAs, 2-3 in 36.1%, and ≥4 in 25% of CAs. Our results indicate that, in atherosclerotic CAs, the immune privilege of the media is disrupted by the infiltration of T and B cells, macrophages, and the presence of vasa vasorum.

Integrin beta3 regulates clonality and fate of smooth muscle-derived atherosclerotic plaque cells

Smooth muscle cells (SMCs) play a key role in atherogenesis. However, mechanisms regulating expansion and fate of pre-existing SMCs in atherosclerotic plaques remain poorly defined. Here we show that multiple SMC progenitors mix to form the aorta during development. In contrast, during atherogenesis, a single SMC gives rise to the smooth muscle-derived cells that initially coat the cap of atherosclerotic plaques. Subsequently, highly proliferative cap cells invade the plaque core, comprising the majority of plaque cells. Reduction of integrin β3 (Itgb3) levels in SMCs induces toll-like receptor 4 expression and thereby enhances Cd36 levels and cholesterol-induced transdifferentiation to a macrophage-like phenotype. Global Itgb3 deletion or transplantation of Itgb3^(−/−) bone marrow results in recruitment of multiple pre-existing SMCs into plaques. Conditioned medium from Itgb3-silenced macrophages enhances SMC proliferation and migration. Together, our results suggest SMC contribution to atherogenesis is regulated by integrin β3-mediated pathways in both SMCs and bone marrow-derived cells.

Smooth muscle cells (SMCs) invade atherosclerotic lesions and expand, contributing to plaque progression. Here Misra et al. show that SMC-derived plaque cells come from a single SMC and integrin β3 in SMCs and macrophages regulate the fate, expansion and migration of SMCs during plaque formation.

DFMG reverses proliferation and migration of vascular smooth muscle cells induced by co-culture with injured vascular endothelial cells via suppression of the TLR4-mediated signaling pathway

7-Difluoromethoxy-5,4′-dimethoxy-genistein (DFMG) is a novel chemical compound synthesized using genistein. Previous studies have indicated that DFMG can reverse the apoptosis of vascular endothelial cells (VECs) by regulating the mitochondrial apoptosis pathway. The present study aimed to investigate the activity and molecular mechanism underlying DFMG-mediated protection of vascular smooth muscle cell (VSMCs) using a non-contact co-culture model established by using Transwell insert. Secretion of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured by ELISA. Proliferation and migration of VSMCs were assessed using a Cell Counting kit-8 and wound healing assays, respectively. Toll-like receptor 4 (TLR4) mRNA and protein levels were detected by reverse transcription-quantitative polymerase chain reaction and western blotting analyses, respectively. In the present study, lysophosphatidylcholine (LPC) significantly increased the secretion of IL-6 and TNF-α in VECs. VECs treated with LPC markedly increased proliferation and migration of VSMCs, which were inhibited by DFMG. Transfection of either TLR4 short hairpin RNA (shRNA) or TLR4 cDNA in VECs inhibited and increased proliferation and migration of VSMCs, respectively. Furthermore, transfection of VECs with TLR4 shRNA suppressed the proliferation and migration of VSMCs induced by co-culture with injured VECs, which was further enhanced by treatment with DFMG. By contrast, transfection of VECs with TLR4 cDNA enhanced proliferation and migration of VSMCs and this effect was inhibited by treatment with DFMG. Taken together, the results of the present study demonstrated that DFMG can reverse proliferation and migration of VSMCs induced by co-culture with injured VECs via suppression of the TLR4-mediated signaling pathway.

Apelin/APJ system: A critical regulator of vascular smooth muscle cell

APJ, an orphan G protein-coupled receptor, is first identified through homology cloning in 1993. Apelin is endogenous ligand of APJ extracted from bovine stomach tissue in 1998. Apelin/APJ system is widely expressed in many kinds of cells such as endothelial cells, cardiomyocytes, especially vascular smooth muscle cell. Vascular smooth muscle cell (VSMC), an integral part of the vascular wall, takes part in many normal physiological processes. Our experiment firstly finds that apelin/APJ system enhances VSMC proliferation by ERK1/2-cyclin D1 signal pathway. Accumulating studies also show that apelin/APJ system plays a pivotal role in mediating the function of VSMC. In this paper, we review the exact role of apelin/APJ system in VSMC, including induction of proliferation and migration, enhance of contraction and relaxation, inhibition of calcification. Furthermore, we discuss the role of apelin/APJ system in vascular diseases, such as atherosclerosis, hypertension, and chronic kidney disease (CKD) from the point of VSMC. Above all, apelin/APJ system is a promising target for managing vascular disease.

Toll-like receptor expression patterns in the rat uterus during post partum involution

Toll-like receptors (TLRs) belong to a family of pathogen recognition receptors and play critical roles in detecting and responding to invading pathogens. TLR expression could be significant because, in the uterus, the reproductive tract is an important site of exposure to and infection by pathogens during the post partum involution period. To clarify the expression and localisation patterns of TLRs in the rat uterus on Days 1, 3, 5 and 10 post partum (PP1, PP3, PP5 and PP10 respectively), immunohistochemistry and western blotting were used to analyse TLR1-7, TLR9 and TLR10. The immunohistochemistry results indicated that TLR1-7, TLR9 and TLR10 were localised in both the cytoplasm and nuclei of luminal and glandular epithelium, stromal fibroblasts and myometrial cells in the rat uterus. In the luminal epithelium, TLR4-7 were also found in lateral membranes, whereas TLR10 was present in apical membranes. Western blot analysis revealed that the expression of TLR proteins increased with the number of days post partum, reaching a maximum on PP10, although levels did not differ significantly from those on PP1 (P>0.05). These findings confirm that TLR1-7, TLR9 and TLR10 are constitutively expressed in uterine cells and that localisation pattern of TLRs in the endometrium varies with structural changes in the uterus on different days of involution. These results suggest that TLRs may play a role in uterine repair and remodelling during physiological involution.

High phosphate induces a pro-inflammatory response by vascular smooth muscle cells and modulation by vitamin D derivatives

In chronic kidney disease patients, high phosphate (HP) levels are associated with cardiovascular disease, the major cause of morbidity and mortality. Since serum phosphate has been independently correlated with inflammation, the present study aimed to investigate an independent direct effect of HP as a pro-inflammatory factor in VSMCs. A possible modulatory effect of vitamin D (VitD) was also investigated. The study was performed in an in vitro model of human aortic smooth muscle cells (HASMCs). Incubation of cells in an HP (3.3 mM) medium caused an increased expression of the pro-inflammatory mediators intercellular adhesion molecule 1 (ICAM-1), interleukins (ILs) IL-1β, IL-6, IL-8 and tumour necrosis factor α (TNF-α) (not corroborated at the protein levels for ICAM-1), as well as an increase in reactive oxygen/nitrogen species (ROS/RNS) production. This was accompanied by the activation of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) signalling as demonstrated by the increase in the nuclear translocation of nuclear factor κ-light-chain-enhancer of activated B cells protein 65 (p65-NF-κΒ) assessed by Western blotting and confocal microscopy. Since all these events were attenuated by an antioxidant pre-incubation with the radical scavenger Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), it is suggested that the inflammatory response is upstream mediated by the ROS/RNS-induced activation of NF-κΒ. Addition of paricalcitol (PC) 3·10−8 M to cells in HP prevented the phosphate induced ROS/RNS increase, the activation of NF-κΒ and the cytokine up-regulation. A bimodal effect was observed, however, for different calcitriol (CTR) concentrations, 10−10 and 10−12 M attenuated but 10−8 M stimulated this phosphate induced pro-oxidative and pro-inflammatory response. Therefore, these findings provide novel mechanisms whereby HP may directly favour vascular dysfunctions and new insights into the protective effects exerted by VitD derivatives.

Palmitate induces VSMC apoptosis via toll like receptor (TLR)4/ROS/p53 pathway

BACKGROUND AND AIMS

Toll-like receptor 4 (TLR4) has been implicated in vascular inflammation, as well as in the pathogenesis of atherosclerosis and diabetes. Vascular smooth muscle cell (VSMC) apoptosis has been shown to induce plaque vulnerability in atherosclerosis. Previous studies reported that palmitate induced apoptosis in VSMCs; however, the role of TLR4 in palmitate-induced apoptosis in VSMCs has not yet been defined. In this study, we investigated whether or not palmitate-induced apoptosis depended on the activation of the TLR4 pathway.

METHODS

VSMCs were treated with or without palmitate, CRISPR/Cas9z-mediated genome editing methods were used to deplete TLR4 expression, while NADPH oxidase inhibitors were used to inhibit reactive oxygen species (ROS) generation. Cell apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, ROS was measured using the 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) method, the mRNA and protein expression levels of caspase 3, caspase 9, BCL-2 and p53 were studied by real-time polymerase chain reaction (RT-PCR) and ELISA.

RESULTS

Palmitate significantly promotes VSMC apoptosis, ROS generation, and expression of caspase 3, caspase 9 and p53; while NADPH oxidase inhibitor pretreatment markedly attenuated these effects. Moreover, knockdown of TLR4 significantly blocked palmitate-induced ROS generation and VSMC apoptosis accompanied by inhibition of caspase 3, caspase 9, p53 expression and restoration of BCL-2 expression.

CONCLUSIONS

Our results suggest that palmitate-induced apoptosis depends on the activation of the TLR4/ROS/p53 signaling pathway, and that TLR4 may be a potential therapeutic target for the prevention and treatment of atherosclerosis.

Lipopolysaccharide-binding protein is associated with arterial stiffness in patients with type 2 diabetes: a cross-sectional study

BACKGROUND

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase reactant that mediates immune responses triggered by LPS. Recent evidence indicates the association of circulating LBP levels with obesity, diabetes, and cardiovascular diseases. In this study, we aimed to investigate the relationship between serum LBP levels and arterial stiffness in patients with type 2 diabetes.

METHODS

A total of 196 patients with type 2 diabetes, including 101 men and 95 women, were enrolled in this cross-sectional study. Fasting serum LBP levels were determined by enzyme-linked immunosorbent assay. Arterial stiffness was assessed by measuring the aortic pulse wave velocity (PWV).

RESULTS

The mean values of serum LBP and aortic PWV were 18.2 μg/mL and 1194 cm/s, respectively. Serum LBP levels were positively correlated with body mass index, triglycerides, high-sensitivity C-reactive protein, and insulin resistance index and were negatively correlated with high-density lipoprotein cholesterol. They were, however, not significantly correlated with aortic PWV in univariate analyses. Multivariate analysis revealed that serum LBP levels were independently and positively associated with aortic PWV (β = 0.135, p = 0.026) after adjusting for age, sex, body mass index, albumin, high-sensitivity C-reactive protein, and other cardiovascular risk factors. Further analyses revealed that the impact of serum LBP levels on aortic PWV was modified by sex, and the association between serum LBP levels and aortic PWV was found to be significant only in men.

CONCLUSIONS

Serum LBP levels are associated with arterial stiffness, independent of obesity and traditional cardiovascular risk factors, especially in men with type 2 diabetes. This study indicates a potential role of the LPS/LBP-induced innate immunity in the development and progression of arterial stiffness in type 2 diabetes.

Mesenchymal Stromal Cells and Toll-Like Receptor Priming: A Critical Review

Mesenchymal Stromal Cells (MSCs) are potential cellular candidates for several immunotherapy purposes. Their multilineage potential and immunomodulatory properties make them interesting tools for the treatment of various immunological diseases. However, depending on the local microenvironment, diverse biological functions of MSCs can be modulated. Indeed, during infections such as obtained following TLR-agonist engagement (called as TLR priming), the phenotype, multilineage potential, hematopoietic support and immunomodulatory capacity of MSCs can present critical changes, which could further affect their therapeutic potential. Thus, for appropriate clinical application of MSCs, it is important to well know and understand these effects in particular during infectious episodes and to find the suitable experimental settings to study that. Pre-stimulation of MSCs with a specific TLR ligand may serve as an effective priming step to modulate one of its function to achieve a desired therapeutic issue.

Impaired Ca(2+) Homeostasis and Decreased Orai1 Expression Modulates Arterial Hyporeactivity to Vasoconstrictors During Endotoxemia

We hypothesized that SIRS/endotoxemia-associated hyporesponsiveness to vasoconstrictors is mediated by smaller increases in intracellular Ca(2+) levels due to reduced signaling via the STIM/Orai. Male Wistar rats were injected either with saline or bacterial LPS (i.p.; 10 mg/kg), and experiments were performed 24 h later. LPS-injected rats exhibited decreased systolic blood pressure, increased heart rate, neutrophils' migration into the peritoneal cavity, and elevated alanine aminotransferase levels. Additionally, second-order mesenteric arteries from endotoxemic rats displayed hyporeactivity to contractile agents such as phenylephrine and potassium chloride; decreased contractile responses to Ca(2+); reduced contraction during Ca(2+) loading; and smaller intracellular Ca(2+) stores. Decreased Orai1, but not STIM1, expression was found in resistance mesenteric arteries from LPS-treated rats. Additionally, cultured vascular smooth muscle cell (VSMC) treated with LPS resulted in increased TLR-4 expression, but Myd-88 and STIM-1 expression were not changed. Our data suggest that in endotoxemia, Ca(2+) homeostasis is disrupted in VSMC, with decreased Ca(2+) influx, smaller concentrations of Ca(2+) in the sarcoplasmic reticulum, and decreased activation of Orai1. Abnormal Ca(2+) handling contributes to LPS-associated vascular hyporeactivity.

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.

Toll-Like Receptor 4 Activation Contributes to Diabetic Bladder Dysfunction in a Murine Model of Type 1 Diabetes

Diabetic bladder dysfunction (DBD) is a common urological complication of diabetes. Innate immune system activation via Toll-like receptor 4 (TLR4) leads to inflammation and oxidative stress and was implicated in diabetes pathophysiology. We hypothesized that bladder hypertrophy and hypercontractility in DBD is mediated by TLR4 activation. Wild-type (WT) and TLR4 knockout (TLR4KO) mice were made diabetic by streptozotocin (STZ) treatment, and bladder contractile function and TLR4 pathway expression were evaluated. Immunohistochemistry confirmed the expression of TLR4 in human and mouse bladder. Recombinant high-mobility group box protein 1 (HMGB1) increased bladder TLR4 and MyD88 expression and enhanced contractile response to electrical field stimulation. Bladder expression of TLR4 and MyD88 and serum expression of HMGB1 were increased in STZ compared with control mice. Carbachol (CCh)-mediated contraction was increased in bladders from STZ mice, and TLR4 inhibitor CLI-095 attenuated this increase. Induction of diabetes by STZ in WT mice increased bladder weight and contractile responses to CCh and to electrical field stimulation. TLR4KO mice were not protected from STZ-induced diabetes; however, despite levels of hyperglycemia similar to those of WT STZ mice, TLR4KO STZ mice were protected from diabetes-induced bladder hypertrophy and hypercontractility. These data suggest that TLR4 activation during diabetes mediates DBD-associated bladder hypertrophy and hypercontractility.

Electrosprayed Montelukast/poly (lactic-co-glycolic acid) particle based coating: A new therapeutic approach towards the prevention of in-stent restenosis

Drug-eluting stents (DESs), have shown promising results in prevention of in-stent restenosis after percutaneous coronary intervention (PCI). The elevated level of leukotrienes (LTs) detected in injured arteries after PCI, together with the potential role of LTs in inflammatory cascades and structural alterations in arterial wall provides the rationale for development of therapeutic strategies for prevention of in-stent restenosis using LTs receptor antagonists. Montelukast (MK) is a selective cysLT1 receptor antagonist, with anti-inflammatory and anti-proliferative properties, which has been used for treatment of various diseases. Here, we report on the fabrication of MK/PLGA particles by electrospraying, aiming towards the development of particle based coating of DESs. The electrosprayed particles incorporated with 3% and 6% w/w MK exhibited fairly spherical shape with smooth surfaces and narrow size distribution. Sustained release of MK for up to 40days was obtained for both formulations, with higher initial burst release and drug release rate for the particles with higher drug loading. The LTD4 induced proliferation and migration of human coronary artery smooth muscle cells (HCASMCs) by 35% and 85%, respectively, which was substantially antagonized using MK incorporated particles. Nevertheless, MK antagonism preserved the normal proliferation and migration of human coronary artery endothelial cells (HCAECs). Moreover, MK antagonism inhibited the LTD4 induced phenotypic transition of HCASMCs from contractile to synthetic type. The electrosprayed MK-PLGA particles can be employed as a coating for DESs to inhibit the formation of neointimal hyperplasia responsible for in-stent restenosis, yet preserve the healing rate of the stented vessel.

STATEMENT OF SIGNIFICANT

Montelukast (MK) is a selective cysLT1 receptor antagonist, with anti-inflammatory and anti-proliferative properties. The LTD4 induced proliferation and migration of human coronary artery smooth muscle cells by 35% and 85%, respectively, which was substantially antagonized using MK incorporated particles. MK antagonism preserved the normal proliferation and migration of human coronary artery endothelial cells. The MK antagonism inhibited the phenotypic transition of human coronary artery smooth muscle cells from contractile to synthetic one induced by LTD4. The electrosprayed MK-PLGA particles can be employed as coating for DESs to inhibit formation of neointimal hyperplasia, responsible for in-stent restenosis.

Toll-like Receptors in the Vascular System: Sensing the Dangers Within

Toll-like receptors (TLRs) are components of the innate immune system that respond to exogenous infectious ligands (pathogen-associated molecular patterns, PAMPs) and endogenous molecules that are released during host tissue injury/death (damage-associated molecular patterns, DAMPs). Interaction of TLRs with their ligands leads to activation of downstream signaling pathways that induce an immune response by producing inflammatory cytokines, type I interferons (IFN), and other inflammatory mediators. TLR activation affects vascular function and remodeling, and these molecular events prime antigen-specific adaptive immune responses. Despite the presence of TLRs in vascular cells, the exact mechanisms whereby TLR signaling affects the function of vascular tissues are largely unknown. Cardiovascular diseases are considered chronic inflammatory conditions, and accumulating data show that TLRs and the innate immune system play a determinant role in the initiation and development of cardiovascular diseases. This evidence unfolds a possibility that targeting TLRs and the innate immune system may be a novel therapeutic goal for these conditions. TLR inhibitors and agonists are already in clinical trials for inflammatory conditions such as asthma, cancer, and autoimmune diseases, but their study in the context of cardiovascular diseases is in its infancy. In this article, we review the current knowledge of TLR signaling in the cardiovascular system with an emphasis on atherosclerosis, hypertension, and cerebrovascular injury. Furthermore, we address the therapeutic potential of TLR as pharmacological targets in cardiovascular disease and consider intriguing research questions for future study.

Calcineurin inhibitors cyclosporine A and tacrolimus induce vascular inflammation and endothelial activation through TLR4 signaling

The introduction of the calcineurin inhibitors (CNIs) cyclosporine and tacrolimus greatly reduced the rate of allograft rejection, although their chronic use is marred by a range of side effects, among them vascular toxicity. In transplant patients, it is proved that innate immunity promotes vascular injury triggered by ischemia-reperfusion damage, atherosclerosis and hypertension. We hypothesized that activation of the innate immunity and inflammation may contribute to CNI toxicity, therefore we investigated whether TLR4 mediates toxic responses of CNIs in the vasculature. Cyclosporine and tacrolimus increased the production of proinflammatory cytokines and endothelial activation markers in cultured murine endothelial and vascular smooth muscle cells as well as in ex vivo cultures of murine aortas. CNI-induced proinflammatory events were prevented by pharmacological inhibition of TLR4. Moreover, CNIs were unable to induce inflammation and endothelial activation in aortas from TLR4^−/− mice. CNI-induced cytokine and adhesion molecules synthesis in endothelial cells occurred even in the absence of calcineurin, although its expression was required for maximal effect through upregulation of TLR4 signaling. CNI-induced TLR4 activity increased O₂⁻/ROS production and NF-κB-regulated synthesis of proinflammatory factors in cultured as well as aortic endothelial and VSMCs. These data provide new insight into the mechanisms associated with CNI vascular inflammation.

IRAK1 mediates TLR4-induced ABCA1 downregulation and lipid accumulation in VSMCs

The activation of Toll-like receptor 4 (TLR4) signaling has an important role in promoting lipid accumulation and pro-inflammatory effects in vascular smooth muscle cells (VSMCs), which facilitate atherosclerosis development and progression. Previous studies have demonstrated that excess lipid accumulation in VSMCs is due to an inhibition of the expression of ATP-binding cassette transporter A1 (ABCA1), an important molecular mediator of lipid efflux from VSMCs. However, the underlying molecular mechanisms of this process are unclear. The purpose of this study was to disclose the underlying molecular mechanisms of TLR4 signaling in regulating ABCA1 expression. Primary cultured VSMCs were stimulated with 50 μg/ml oxidized low-density lipoprotein (oxLDL). We determined that enhancing TLR4 signaling using oxLDL significantly downregulated ABCA1 expression and induced lipid accumulation in VSMCs. However, TLR4 knockout significantly rescued oxLDL-induced ABCA1 downregulation and lipid accumulation. In addition, IL-1R-associated kinase 1 (IRAK1) was involved in the effects of TLR4 signaling on ABCA1 expression and lipid accumulation. Silencing IRAK1 expression using a specific siRNA reversed TLR4-induced ABCA1 downregulation and lipid accumulation in vitro. These results were further confirmed by our in vivo experiments. We determined that enhancing TLR4 signaling by administering a 12-week-long high-fat diet (HFD) to mice significantly increased IRAK1 expression, which downregulated ABCA1 expression and induced lipid accumulation. In addition, TLR4 knockout in vivo reversed the effects of the HFD on IRAK1 and ABCA1 expression, as well as on lipid accumulation. In conclusion, IRAK1 is involved in TLR4-mediated downregulation of ABCA1 expression and lipid accumulation in VSMCs.

Vascular smooth muscle cell in atherosclerosis

Vascular smooth muscle cells (VSMCs) exhibit phenotypic and functional plasticity in order to respond to vascular injury. In case of the vessel damage, VSMCs are able to switch from the quiescent 'contractile' phenotype to the 'proinflammatory' phenotype. This change is accompanied by decrease in expression of smooth muscle (SM)-specific markers responsible for SM contraction and production of proinflammatory mediators that modulate induction of proliferation and chemotaxis. Indeed, activated VSMCs could efficiently proliferate and migrate contributing to the vascular wall repair. However, in chronic inflammation that occurs in atherosclerosis, arterial VSMCs become aberrantly regulated and this leads to increased VSMC dedifferentiation and extracellular matrix formation in plaque areas. Proatherosclerotic switch in VSMC phenotype is a complex and multistep mechanism that may be induced by a variety of proinflammatory stimuli and hemodynamic alterations. Disturbances in hemodynamic forces could initiate the proinflammatory switch in VSMC phenotype even in pre-clinical stages of atherosclerosis. Proinflammatory signals play a crucial role in further dedifferentiation of VSMCs in affected vessels and propagation of pathological vascular remodelling.

The microRNAs Let7c and miR21 are recognized by neuronal Toll-like receptor 7 to restrict dendritic growth of neurons

Inflammatory responses are known to play critical roles in the regulation of neurodevelopment and neurodegeneration. Although microglial cells are recognized as professional immune cells in brains, recent evidence suggests that neurons also express important receptors and regulators of innate immunity, including Toll-like receptor 7 (TLR7), which is a receptor for single-stranded RNAs (ssRNAs). Here, we report that neuronal TLR7 recognizes endogenous ligands such as the miRNAs Let7c and miR21 and plays a negative role in controlling neuronal growth in a cell-autonomous manner. We show here that hippocampal CA1 neurons in Tlr7(-/Y) mice had more complex dendritic arbors compared with those of wild-type littermates at postnatal (P) day 7, but not at P21. This observation strengthens a role of TLR7 in restricting neuronal growth during development. In cultured neurons, transient knockdown of Tlr7 promoted axonal and dendritic growth, supporting the cell-autonomous effect of TLR7 on neuronal growth. We observed perceptible levels of Let7c and miR21 in the exosomes of the neuronal cultures as well as in developing brains. Treatment with Let7c and miR21 restricted dendritic growth of wild-type neurons but not Tlr7(-/-) neurons. Our study suggests that neuronal TLR7 is activated by endogenous ligands and thus regulates neuronal morphology. Neuronal innate immune responses may influence neurodevelopment and neurodegeneration through the regulation of neuronal morphology.

Sparstolonin B suppresses rat vascular smooth muscle cell proliferation, migration, inflammatory response and lipid accumulation

Vascular smooth muscle cells (VSMCs) play a crucial role in atherosclerotic lesion formation. Sparstolonin B (SsnB) is a TLR2/TLR4 antagonist that inhibits inflammatory responses in multiple cell types. Herein, we investigated if SsnB inhibited VSMC proliferation, migration, inflammatory response and lipid accumulation. We found that SsnB suppressed VSMC proliferation and migration induced by PDGF. SsnB significantly suppressed the expression of MCP-1, TNFα and IL-6 in VSMCs stimulated by either lipopolysaccharide (LPS) or PDGF. Erk1/2 and Akt signaling pathways, which are responsible for the VSMC inflammatory response, were activated by LPS or PDGF stimulation, and SsnB significantly inhibited their activation. SsnB also substantially suppressed the intracellular cholesterol accumulation in VSMCs loaded with acetylated LDL. Mechanistically, SsnB remarkably repressed LPS-induced up-regulation of CD36, which is responsible for lipid uptake, and dramatically reversed LPS-induced inhibition of ABCA1, which promotes the efflux of intracellular free cholesterol. In conclusion, our results indicate that SsnB significantly inhibits VSMC proliferation, migration, inflammatory responses and lipid accumulation. Along with the previously reported anti-inflammatory activities of SsnB on macrophages and vascular endothelial cells, our data strongly suggest that SsnB may be developed as a new anti-atherogenic therapy.

Toll like receptor-2 regulates production of glial-derived neurotrophic factors in murine intestinal smooth muscle cells

Gut microbiota-innate immunity axis is emerging as a key player to guarantee the structural and functional integrity of the enteric nervous system (ENS). Alterations in the composition of the gut microbiota, derangement in signaling of innate immune receptors such as Toll-like receptors (TLRs), and modifications in the neurochemical coding of the ENS have been associated with a variety of gastrointestinal disorders. Indeed, TLR2 activation by microbial products controls the ENS structure and regulates intestinal neuromuscular function. However, the cellular populations and the molecular mechanisms shaping the plasticity of enteric neurons in response to gut microbes are largely unexplored. In this study, smooth muscle cells (SMCs), enteric glial cells (EGCs) and macrophages/dendritic cells (MΦ/DCs) were isolated and cultured from the ileal longitudinal muscle layer of wild-type (WT) and Toll-like receptor-2 deficient (TLR2(-/-)) mice. Quantification of mRNA levels of neurotrophins at baseline and following stimulation with TLR ligands was performed by RT-PCR. To determine the role of neurotrophins in supporting the neuronal phenotype, we performed co-culture experiments of enteric neurons with the conditioned media of cells isolated from the longitudinal muscle layer of WT or TLR2(-/-) mice. The neuronal phenotype was investigated evaluating the expression of βIII-tubulin, HuC/D, and nNOS by immunocytochemistry. As detected by semi-quantitative RT-PCR, SMCs expressed mRNA coding TLR1-9. Among the tested cell populations, un-stimulated SMCs were the most prominent sources of neurotrophins. Stimulation with TLR2, TLR4, TLR5 and TLR9 ligands further increased Gdnf, Ngf, Bdnf and Lif mRNA levels in SMCs. Enteric neurons isolated from TLR2(-/-) mice exhibited smaller ganglia, fewer HuC/D(+ve) and nNOS(+ve) neurons and shorter βIII-tubulin axonal networks as compared to neurons cultured from WT mice. The co-culture with the conditioned media from WT-SMCs but not with those from WT-EGCs or WT-MΦ/DCs corrected the altered neuronal phenotype of TLR2(-/-) mice. Supplementation of TLR2(-/-) neuronal cultures with GDNF recapitulated the WT-SMC co-culture effect whereas the knockdown of GDNF expression in WT-SMCs using shRNA interference abolished the effect on TLR2(-/-) neurons. These data revealed that by exploiting the repertoire of TLRs to decode gut-microbial signals, intestinal SMCs elaborate a cocktail of neurotrophic factors that in turn supports neuronal phenotype. In this view, the SMCs represent an attractive target for novel therapeutic strategies.

Inflammatory and immune responses in the arterial media

Inflammatory arterial diseases differentially affect the compartments of the vessel wall. The intima and adventitia are commonly involved by the disease process, with luminal and microvascular endothelial cells playing a critical role in the recruitment and activation of leukocytes. In contrast, the avascular media is often spared by immune-mediated disorders. Surprisingly, vascular smooth muscle cells (VSMCs), the predominant and often exclusive cell type of the media, are capable of robust proinflammatory responses to diverse stressors. The multiple cytokines and chemokines produced within the media can profoundly affect macrophage and T cell function, thus amplifying and shaping innate and adaptive immune responses. On the other hand, VSMCs and the extracellular matrix that they produce also display significant anti-inflammatory properties. The balance between the pro- and anti-inflammatory effects of VSMCs and their extracellular matrix versus the strength of the inciting immunologic events determines the pattern of medial pathology. Limitations on the extent of medial infiltration and injury, defined as medial immunoprivilege, are typically seen in arteriosclerotic diseases, such as atherosclerosis and transplant vasculopathy. Conversely, breakdown of medial immunoprivilege that manifests as more intense leukocytic infiltrates, loss of VSMCs, and destruction of the extracellular matrix architecture is a general feature of certain aneurysmal diseases and vasculitides. In this review, we consider the inflammatory and immune functions of VSMCs and how they may lead to medial immunoprivilege or medial inflammation in arterial diseases.

Lipopolysaccharide stimulation improves the odontoblastic differentiation of human dental pulp cells

Lipopolysaccharide (LPS) is one of the causative agents of pulpitis and previous studies have demonstrated that the LPS stimulation of human aortic valve interstitial cells induces inflammatory mediators and the gene expression of osteogenic factors. Therefore, in the present study, it was hypothesized that LPS affects the odontoblastic differentiation of human dental pulp cells (hDPCs). In order to investigate this, an in vitro study using hDPCs was performed. Increased alkaline phosphatase (ALP) activity was observed in the hDPCs treated with LPS, which was more marked when the cells were costimulated with odontogenic induction medium (OM). LPS also appeared to increase the gene expression levels of dentin sialophosphoprotein and dentin matrix protein‑1 and the protein expression level of dental sialoprotein in the hDPCs, particularly in combination with OM. In addition, the size and the number of nodules formed in the hDPCs exposed to OM and LPS were increased compared to those stimulated by OM alone. To determine the role of nuclear factor κB (NF‑κB) during the LPS‑induced odontoblastic differentiation of hDPCs, immunofluorescence was performed. The nuclear translocation of NF‑κB, induced by LPS was confirmed, suggesting its involvement in the LPS‑induced increase in odontoblastic differentiation of hDPCs. In conclusion, there may be an association between LPS stimulation, with or without OM, and odontoblastic differentiation.

Statins meditate anti-atherosclerotic action in smooth muscle cells by peroxisome proliferator-activated receptor-γ activation

The peroxisome proliferator-activated receptor-γ (PPARγ) is an important regulator of lipid and glucose metabolism, and its activation is reported to suppress the progression of atherosclerosis. We have reported that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) activate PPARγ in macrophages. However, it is not yet known whether statins activate PPARγ in other vascular cells. In the present study, we investigated whether statins activate PPARγ in smooth muscle cells (SMCs) and endothelial cells (ECs) and thus mediate anti-atherosclerotic effects. Human aortic SMCs (HASMCs) and human umbilical vein ECs (HUVECs) were used in this study. Fluvastatin and pitavastatin activated PPARγ in HASMCs, but not in HUVECs. Statins induced cyclooxygenase-2 (COX-2) expression in HASMCs, but not in HUVECs. Moreover, treatment with COX-2-siRNA abrogated statin-mediated PPARγ activation in HASMCs. Statins suppressed migration and proliferation of HASMCs, and inhibited lipopolysaccharide-induced expression of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in HASMCs. These effects of statins were abrogated by treatment with PPARγ-siRNA. Treatment with statins suppressed atherosclerotic lesion formation in Apoe(-/-) mice. In addition, transcriptional activity of PPARγ and CD36 expression were increased, and the expression of MCP-1 and TNF-α was decreased, in the aorta of statin-treated Apoe(-/-) mice. In conclusion, statins mediate anti-atherogenic effects through PPARγ activation in SMCs. These effects of statins on SMCs may be beneficial for the prevention of atherosclerosis.

Role of vascular smooth muscle cell in the inflammation of atherosclerosis

Atherosclerosis is a pathologic process occurring within the artery, in which many cell types, including T cell, macrophages, endothelial cells, and smooth muscle cells, interact, and cause chronic inflammation, in response to various inner- or outer-cellular stimuli. Atherosclerosis is characterized by a complex interaction of inflammation, lipid deposition, vascular smooth muscle cell proliferation, endothelial dysfunction, and extracellular matrix remodeling, which will result in the formation of an intimal plaque. Although the regulation and function of vascular smooth muscle cells are important in the progression of atherosclerosis, the roles of smooth muscle cells in regulating vascular inflammation are rarely focused upon, compared to those of endothelial cells or inflammatory cells. Therefore, in this review, we will discuss here how smooth muscle cells contribute or regulate the inflammatory reaction in the progression of atherosclerosis, especially in the context of the activation of various membrane receptors, and how they may regulate vascular inflammation.