Inhibition of reactive oxygen species generation attenuates TLR4-mediated proinflammatory and proliferative phenotype of vascular smooth muscle cells

Potential applications of components of aged garlic extract in mitigating pro-inflammatory gene expression linked to human diseases (Review)

In the present review, simple approaches for the screening and characterization of natural compound agents that alter pro-inflammatory gene expression are described, with a particular focus on aged garlic extract (AGE), which has been the subject of several investigations that have supported its potential application as an anti-inflammatory agent. Additionally, evidence regarding the possible effects and mechanisms of action of two major AGE components, S-allyl cysteine (SAC) and S-1-propenyl-l-cysteine (S1PC), is reviewed. The proposed molecular targets of SAC and S1PC are IKKβ kinase, the Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2 complex, peroxisome proliferator-activated receptor-γ, histone deacetylase and toll-like receptor 4 (TLR4). Targeting these molecules causes a marked reduction in NF-κB activity accompanied by a notable decrease in the transcription of NF-κB-regulated genes. Another main objective of the present review was to discuss the possibility that AGE and its bioactive components could be employed in the treatment of several human pathologies that are characterized by a hyperinflammatory state resulting from dysregulation of the TLR4 and NF-κB pathways. SAC is of interest in the treatment of lung pathologies, neurological diseases, osteoarthritis, muscular atrophy, cardiovascular diseases, diabetes and cancer. Additionally, the anti-oxidative activities of AGE, SAC and S1PC are compatible with their employment in the treatment of diseases characterized by oxidative stress, such as sickle cell disease and β-thalassemia.

Phytochemistry and Anti-Inflammatory and Antioxidant Activities of Cinnamomum osmophloeum and Its Bioactive Constituents: A Review

Cinnamomum osmophloeum, commonly known as indigenous cinnamon, is a tree species native to Taiwan's hardwood forests. It has been extensively investigated for its chemical composition and bioactivities. Several reports have shown that C. osmophloeum leaves are rich in aromatic oils, which are grouped into various chemotypes based on their major constituents. Components of the volatile oils included phenylpropanoids, monoterpenoids, sesquiterpenoids, phenols, coumarins, and other miscellaneous compounds. In addition, other secondary metabolites previously identified in this species included flavonol glycosides, phenolic acids, lignans, proanthocyanidins, and cyclopropanoids. C. osmophloeum is widely recognized for its medicinal and industrial applications, particularly its essential oils. In general, essential oils exhibit remarkable anti-inflammatory and antioxidant actions, enabling them to modulate key inflammatory mediators and neutralize free radicals. This review explored the phytochemical composition of the essential oils and extracts from C. osmophloeum as well as therapeutic potential of this species, focusing on the action mechanisms and clinical potential. We hope that this review will contribute to a better understanding of the biological effects of this plant and its potential applications in the management of conditions associated with inflammation and oxidative stress.

Diverse roles of SARS-CoV-2 Spike and Nucleocapsid proteins in EndMT stimulation through the TGF-β-MRTF axis inhibited by aspirin

BACKGROUND

The SARS-CoV-2 virus causes severe COVID-19 in one-fifth of patients. In addition to high mortality, infection may induce respiratory failure and cardiovascular complications associated with inflammation. Acute or prolonged inflammation results in organ fibrosis, the cause of which might be endothelial disorders arising during the endothelial-mesenchymal transition (EndMT).

METHODS

HUVECs and HMEC-1 cells were stimulated with SARS-CoV-2 S (Spike) and N (Nucleocapsid) proteins, and EndMT induction was evaluated by studying specific protein markers via Western blotting. Wound healing and tube formation assays were employed to assess the potential of SARS-CoV-2 to stimulate changes in cell behaviour. MRTF nuclear translocation, ROS generation, TLR4 inhibitors, TGF-β-neutralizing antibodies, and inhibitors of the TGF-β-dependent pathway were used to investigate the role of the TGF-β-MRTF signalling axis in SARS-CoV-2-dependent EndMT stimulation.

RESULTS

Both viral proteins stimulate myofibroblast trans-differentiation. However, the N protein is more effective at EndMT induction. The TGF-β-MRTF pathway plays a critical role in this process. The N protein preferentially favours action through TGF-β2, whose secretion is induced through TLR4-ROS action. TGF-β2 stimulates MRTF-A and MRTF-B nuclear translocation and strongly regulates EndMT. In contrast, the Spike protein stimulates TGF-β1 secretion as a result of ACE2 downregulation. TGF-β1 induces only MRTF-B, which, in turn, weakly regulates EndMT. Furthermore, aspirin, a common nonsteroidal anti-inflammatory drug, might prevent and reverse SARS-CoV-2-dependent EndMT induction through TGF-β-MRTF pathway deregulation.

CONCLUSION

The reported study revealed that SARS-CoV-2 infection induces EndMT. Moreover, it was demonstrated for the first time at the molecular level that the intensity of the EndMT triggered by SARS-CoV-2 infection may vary and depend on the viral protein involved. The N protein acts through TLR4-ROS-TGF-β2-MRTF-A/B, whereas the S protein acts through ACE2-TGF-β1-MRTF-B. Furthermore, we identified aspirin as a potential anti-fibrotic drug for treating patients with SARS-CoV-2 infection.

The Role of NRF2 in Cerebrovascular Protection: Implications for Vascular Cognitive Impairment and Dementia (VCID)

Vascular cognitive impairment and dementia (VCID) represents a broad spectrum of cognitive decline secondary to cerebral vascular aging and injury. It is the second most common type of dementia, and the prevalence continues to increase. Nuclear factor erythroid 2-related factor 2 (NRF2) is enriched in the cerebral vasculature and has diverse roles in metabolic balance, mitochondrial stabilization, redox balance, and anti-inflammation. In this review, we first briefly introduce cerebrovascular aging in VCID and the NRF2 pathway. We then extensively discuss the effects of NRF2 activation in cerebrovascular components such as endothelial cells, vascular smooth muscle cells, pericytes, and perivascular macrophages. Finally, we summarize the clinical potential of NRF2 activators in VCID.

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.

Hyaluronic acid and proteoglycan link protein 1 suppresses platelet‑derived growth factor-BB-induced proliferation, migration, and phenotypic switching of vascular smooth muscle cells

The development of atherosclerotic cardiovascular disease is associated with the phenotypic switching of vascular smooth muscle cells (SMCs) from a contractile to a synthetic state, leading to cell migration and proliferation. Platelet‑derived growth factor‑BB (PDGF‑BB) modulates this de-differentiation by initiating a number of biological processes. In this study, we show that gene expression of hyaluronic acid (HA) and proteoglycan link protein 1 (HAPLN1) was upregulated during differentiation of human aortic SMCs (HASMCs) into a contractile state, but downregulated upon during PDGF-BB-induced dedifferentiation. This is the first study showing that the treatment of HASMCs with full-length recombinant human HAPLN1 (rhHAPLN1) significantly reversed PDGF-BB-induced decrease in the protein levels of contractile markers (SM22α, α-SMA, calponin, and SM-MHC), and inhibited the proliferation and migration of HASMCs induced by PDGF-BB. Furthermore, our results show that rhHAPLN1 significantly inhibited the phosphorylation of FAK, AKT, STAT3, p38 MAPK and Raf mediated by the binding of PDGF-BB to PDGFRβ. Together, these results indicated that rhHAPLN1 can suppress the PDGF-BB-stimulated phenotypic switching and subsequent de-differentiation of HASMCs, highlighting its potential as a novel therapeutic target for atherosclerosis and other vascular diseases. [BMB Reports 2023; 56(8): 445-450].

Hyaluronic acid and proteoglycan link protein 1 suppresses platelet‑derived growth factor-BB-induced proliferation, migration, and phenotypic switching of vascular smooth muscle cells

The development of atherosclerotic cardiovascular disease is associated with the phenotypic switching of vascular smooth muscle cells (SMCs) from a contractile to a synthetic state, leading to cell migration and proliferation. Platelet‑derived growth factor‑BB (PDGF‑BB) modulates this de-differentiation by initiating a number of biological processes. In this study, we show that gene expression of hyaluronic acid (HA) and proteoglycan link protein 1 (HAPLN1) was upregulated during differentiation of human aortic SMCs (HASMCs) into a contractile state, but downregulated upon during PDGF-BB-induced dedifferentiation. This is the first study showing that the treatment of HASMCs with full-length recombinant human HAPLN1 (rhHAPLN1) significantly reversed PDGF-BB-induced decrease in the protein levels of contractile markers (SM22α, α-SMA, calponin, and SM-MHC), and inhibited the proliferation and migration of HASMCs induced by PDGF-BB. Furthermore, our results show that rhHAPLN1 significantly inhibited the phosphorylation of FAK, AKT, STAT3, p38 MAPK and Raf mediated by the binding of PDGF-BB to PDGFRβ. Together, these results indicated that rhHAPLN1 can suppress the PDGF-BB-stimulated phenotypic switching and subsequent de-differentiation of HASMCs, highlighting its potential as a novel therapeutic target for atherosclerosis and other vascular diseases. [BMB Reports 2023; 56(8): 445-450].

Sulfasalazine induces autophagy inhibiting neointimal hyperplasia following carotid artery injuries in mice

Background: Neointimal hyperplasia (NH) is a crucial pathophysiological feature in vascular transplant and in-stent restenosis. Excessive proliferation and migration of vascular smooth muscle cells (VSMCs) play important roles in neointimal hyperplasia. This study aims to explore the potentialities and mechanism of sulfasalazine (SSZ) in the prevention of restenosis. Methods: Sulfasalazine was encapsulated in nanoparticles made of poly (lactic-co-glycolic acid) (PLGA). In vivo, carotid ligation injury was induced in mice to induce Neointimal hyperplasia, with or without sulfasalazine containing nanoparticles (NP-SSZ) treatment. After 4 weeks, the arteries were collected for histology, immunofluorescence, Western blotting (WB) and qRT-PCR. In vitro, vascular smooth muscle cells were treated with TNF-α to induce cell proliferation and migration, followed by SSZ or vehicle treatment. WB was performed to further explore its mechanism. Results: The ratio of intima to media thickness (I/M) was increased after ligation injury on day 28, while the ratio was significantly reduced in the NP-SSZ treatment group. The dual positive nuclei of Ki-67 and α-SMA were 47.83% ± 9.15%, whereas only 29.83% ± 5.98% in the NP-SSZ-treated group (p < 0.05). Both MMP-2 and MMP-9 were decreased in the NP-SSZ treatment group (p < 0.05, p < 0.05, respectively) compared to the control group. The levels of the targeted inflammatory genes (TNF-α, VCAM-1, ICAM-1, MCP-1) were lower in the NP-SSZ treatment group compared with the control group. In vitro, the proliferating cell nuclear antigen (PCNA) expression was significantly decreased in the SSZ treatment group. The cell viability of VSMCs was markedly increased in the TNF-α treatment group, whereas sulfasalazine treatment inhibited this effect. LC3 II and P62 protein expression were higher in the SSZ group than in the vehicle group both in vitro and in vivo. The phosphorylation of NF-kB (p-NF-kB) and the phosphorylation of mTOR (p-mTOR) were decreased in the TNF-α+ SSZ group, whereas the P62 and LC3 II expression levels were increased. However, the expression level of p-mTOR, P62, and LC3 II was reversed after co-treatment with the agonist of mTOR MHY1485, whereas the p-NF-kB expression level was unchanged. Conclusion: sulfasalazine inhibited vascular smooth muscle cells proliferation and migration in vitro and Neointimal hyperplasia in vivo through NF-kB/mTOR-mediated autophagy.

Arterial remodeling: the role of mitochondrial metabolism in vascular smooth muscle cells

Arterial remodeling is a common pathological basis of cardiovascular diseases such as atherosclerosis, vascular restenosis, hypertension, pulmonary hypertension, aortic dissection, and aneurysm. Vascular smooth muscle cells (VSMCs) are not only the main cellular components in the middle layer of the arterial wall but also the main cells involved in arterial remodeling. Dedifferentiated VSMCs lose their contractile properties and are converted to a synthetic, secretory, proliferative, and migratory phenotype, playing key roles in the pathogenesis of arterial remodeling. As mitochondria are the main site of biological oxidation and energy transformation in eukaryotic cells, mitochondrial numbers and function are very important in maintaining the metabolic processes in VSMCs. Mitochondrial dysfunction and oxidative stress are novel triggers of the phenotypic transformation of VSMCs, leading to the onset and development of arterial remodeling. Therefore, pharmacological measures that alleviate mitochondrial dysfunction reverse arterial remodeling by ameliorating VSMCs metabolic dysfunction and phenotypic transformation, providing new options for the treatment of cardiovascular diseases related to arterial remodeling. This review summarizes the relationship between mitochondrial dysfunction and cardiovascular diseases associated with arterial remodeling and then discusses the potential mechanism by which mitochondrial dysfunction participates in pathological arterial remodeling. Furthermore, maintaining or improving mitochondrial function may be a new intervention strategy to prevent the progression of arterial remodeling.

Vascular smooth muscle cell dysfunction in neurodegeneration

Vascular smooth muscle cells (VSMCs) are the key moderators of cerebrovascular dynamics in response to the brain's oxygen and nutrient demands. Crucially, VSMCs may provide a sensitive biomarker for neurodegenerative pathologies where vasculature is compromised. An increasing body of research suggests that VSMCs have remarkable plasticity and their pathophysiology may play a key role in the complex process of neurodegeneration. Furthermore, extrinsic risk factors, including environmental conditions and traumatic events can impact vascular function through changes in VSMC morphology. VSMC dysfunction can be characterised at the molecular level both preclinically, and clinically ex vivo. However the identification of VSMC dysfunction in living individuals is important to understand changes in vascular function at the onset and progression of neurological disorders such as dementia, Alzheimer's disease, and Parkinson's disease. A promising technique to identify changes in the state of cerebral smooth muscle is cerebrovascular reactivity (CVR) which reflects the intrinsic dynamic response of blood vessels in the brain to vasoactive stimuli in order to modulate regional cerebral blood flow (CBF). In this work, we review the role of VSMCs in the most common neurodegenerative disorders and identify physiological systems that may contribute to VSMC dysfunction. The evidence collected here identifies VSMC dysfunction as a strong candidate for novel therapeutics to combat the development and progression of neurodegeneration, and highlights the need for more research on the role of VSMCs and cerebrovascular dynamics in healthy and diseased states.

Ginsenoside Rh1 Inhibits Angiotensin II-Induced Vascular Smooth Muscle Cell Migration and Proliferation through Suppression of the ROS-Mediated ERK1/2/p90RSK/KLF4 Signaling Pathway

Vascular smooth muscle cell (VSMC) proliferation and migration play key roles in the progression of atherosclerosis and restenosis. A variety of ginsenosides exert various cardiovascular benefits. However, whether and how ginsenoside Rh1 (Rh1) inhibits VSMC dysfunction remain unclear. Here, we investigated the inhibitory effects of Rh1 on rat aortic smooth muscle cell (RASMC) migration and proliferation induced by angiotensin II (Ang II) and the underlying mechanisms. Cell proliferation and migration were evaluated using sulforhodamine B and wound-healing assay. The molecular mechanisms were investigated using Western blotting, quantitative reverse-transcription polymerase chain reaction analysis, immunofluorescence staining, and luciferase assay. Reactive oxygen species (ROS) production was measured using dihydroethidium and MitoSOX staining. We found that Rh1 dose-dependently suppressed Ang II-induced cell proliferation and migration. Concomitantly, Ang II increased protein levels of osteopontin, vimentin, MMP2, MMP9, PCNA, and cyclin D1, while these were reduced by Rh1 pretreatment. Notably, Ang II enhanced both the protein expression and promoter activity of KLF4, a key regulator of phenotypic switching, whereas pretreatment with Rh1 reversed these effects. Mechanistically, the effects of Rh1 on VSMC proliferation and migration were found to be associated with inhibition of ERK1/2/p90RSK signaling. Furthermore, the inhibitory effects of Rh1 were accompanied by inhibition of ROS production. In conclusion, Rh1 inhibited the Ang II-induced migration and proliferation of RASMCs by suppressing the ROS-mediated ERK1/2/p90RSK signaling pathway.

Sulfiredoxin-1 Inhibits PDGF-BB-Induced Vascular Smooth Muscle Cell Proliferation and Migration by Enhancing the Activation of Nrf2/ARE Signaling

Sulfiredoxin1 (Srxn1), an endogenous antioxidant protein, is involved in cardiovascular diseases. In this study, we aimed to investigate the role of Srxn1 in VSMCs and its molecular mechanism. The murine vascular smooth muscle cells MOVAS were treated with different doses of platelet-derived growth factor-BB (PDGF-BB); then, Srxn1 expression was detected using reverse transcription-quantitative polymerase chain reaction and western blot analysis. MTT and wound healing assay were used to examine the effect of Srxn1 on MOVAS cell proliferation and migration. Reactive oxygen species (ROS) production, malondialdehyde (MDA) level, and superoxide dismutase (SOD) activity in MOVAS cells were detected using corresponding commercial kits. Moreover, the expression of proliferating cell nuclear antigen (PCNA), matrix metalloproteinase 2 (MMP-2), and nuclear factor erythroid-2-related factor 2 (Nrf2) /antioxidant response element (ARE) signaling-related proteins was detected using western blot analysis. In our study, PDGF-BB dose-dependently increased Srxn1 expression in MOVAS cells, and Srxn1 expression was increased with time dependence in PDGF-BB-treated MOVAS cells. The knockdown of Srxn1 increased PDGF-BB-induced the proliferation, migration, ROS production, MDA level, and the protein expression of PCNA and MMP-2, as well as decreased SOD activity and the expression of Nrf2/ARE signaling-related proteins in PDGF-BB-stimulated MOVAS cells. However, the overexpression of Srxn1 showed the opposite results to those of knockdown of Srxn1. Moreover, the inhibitory effects of Srxn1 overexpression on PDGF-BB induced proliferation, migration, ROS production, and MDA level and the promotion of Srxn1 overexpression on PDGF-BB induced SOD activity were partially reversed by the knockdown of Nrf2. Srxn1 inhibited PDGF-BB-induced proliferation, migration, and oxidative stress through activating Nrf2/ARE signaling.

Mechanical programming of arterial smooth muscle cells in health and ageing

Arterial smooth muscle cells (ASMCs), the predominant cell type within the arterial wall, detect and respond to external mechanical forces. These forces can be derived from blood flow (i.e. pressure and stretch) or from the supporting extracellular matrix (i.e. stiffness and topography). The healthy arterial wall is elastic, allowing the artery to change shape in response to changes in blood pressure, a property known as arterial compliance. As we age, the mechanical forces applied to ASMCs change; blood pressure and arterial wall rigidity increase and result in a reduction in arterial compliance. These changes in mechanical environment enhance ASMC contractility and promote disease-associated changes in ASMC phenotype. For mechanical stimuli to programme ASMCs, forces must influence the cell's load-bearing apparatus, the cytoskeleton. Comprised of an interconnected network of actin filaments, microtubules and intermediate filaments, each cytoskeletal component has distinct mechanical properties that enable ASMCs to respond to changes within the mechanical environment whilst maintaining cell integrity. In this review, we discuss how mechanically driven cytoskeletal reorganisation programmes ASMC function and phenotypic switching.

Molecular Action of Hydroxytyrosol in Attenuation of Intimal Hyperplasia: A Scoping Review

Objective: Hydroxytyrosol (HT), a polyphenol of olive plant is well known for its antioxidant, anti-inflammatory and anti-atherogenic properties. The aim of this systematic search is to highlight the scientific evidence evaluating molecular efficiency of HT in halting the progression of intimal hyperplasia (IH), which is a clinical condition arises from endothelial inflammation. Methods: A systematic search was performed through PubMed, Web of Science and Scopus, based on pre-set keywords which are Hydroxytyrosol OR 3,4-dihydroxyphenylethanol, AND Intimal hyperplasia OR Neointimal hyperplasia OR Endothelial OR Smooth muscles. Eighteen in vitro and three in vitro and in vivo studies were selected based on a pre-set inclusion and exclusion criteria. Results: Based on evidence gathered, HT was found to upregulate PI3K/AKT/mTOR pathways and supresses inflammatory factors and mediators such as IL-1β, IL-6, E-selectin, P-selectin, VCAM-1, and ICAM-1 in endothelial vascularization and functioning. Two studies revealed HT disrupted vascular smooth muscle cells (SMC) cell cycle by dephosphorylating ERK1/2 and AKT pathways. Therefore, HT was proven to promote endothelization and inhibit vascular SMCs migration thus hampering IH development. However, none of these studies described the effect of HT collectively in both vascular endothelial cells (EC) and SMCs in IH ex vivo model. Conclusions: Evidence from this concise review provides an insight on HT regulation of molecular pathways in reendothelization and inhibition of VSMCs migration. Henceforth, we propose effect of HT on IH prevention could be further elucidated through in vivo and ex vivo model.

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.

ROS systems are a new integrated network for sensing homeostasis and alarming stresses in organelle metabolic processes

Reactive oxygen species (ROS) are critical for the progression of cardiovascular diseases, inflammations and tumors. However, the mechanisms of how ROS sense metabolic stress, regulate metabolic pathways and initiate proliferation, inflammation and cell death responses remain poorly characterized. In this analytic review, we concluded that: 1) Based on different features and functions, eleven types of ROS can be classified into seven functional groups: metabolic stress-sensing, chemical connecting, organelle communication, stress branch-out, inflammasome-activating, dual functions and triple functions ROS. 2) Among the ROS generation systems, mitochondria consume the most amount of oxygen; and nine types of ROS are generated; thus, mitochondrial ROS systems serve as the central hub for connecting ROS with inflammasome activation, trained immunity and immunometabolic pathways. 3) Increased nuclear ROS production significantly promotes cell death in comparison to that in other organelles. Nuclear ROS systems serve as a convergent hub and decision-makers to connect unbearable and alarming metabolic stresses to inflammation and cell death. 4) Balanced ROS levels indicate physiological homeostasis of various metabolic processes in subcellular organelles and cytosol, while imbalanced ROS levels present alarms for pathological organelle stresses in metabolic processes. Based on these analyses, we propose a working model that ROS systems are a new integrated network for sensing homeostasis and alarming stress in metabolic processes in various subcellular organelles. Our model provides novel insights on the roles of the ROS systems in bridging metabolic stress to inflammation, cell death and tumorigenesis; and provide novel therapeutic targets for treating those diseases. (Word count: 246).

lncRNA KCNQ1OT1 Suppresses the Inflammation and Proliferation of Vascular Smooth Muscle Cells through IκBa in Intimal Hyperplasia

Inflammation and proliferation of vascular smooth muscle cells (VSMCs) are the key events in intimal hyperplasia. This study aimed to explore the mechanism by which long non-coding RNA (lncRNA) KCNQ1OT1 affects VSMC inflammation and proliferation in this context. A vein graft (VG) model was established in mice to introduce intimal hyperplasia. Isolated normal VSMCs were induced with platelet-derived growth factor type BB (PDGF-BB), and the cell proliferation, migration, and secretion of inflammatory factors were determined. The results showed that KCNQ1OT1 was downregulated in the VSMCs from mice with intimal hyperplasia and in the PDGF-BB-treated VSMCs, and such downregulation of KCNQ1OT1 resulted from the increased methylation level in the KCNQ1OT1 promoter. Overexpressing KCNQ1OT1 suppressed PDFG-BB-induced VSMC proliferation, migration, and secretion of inflammatory factors. In VSMCs, KCNQ1OT1 bound to the nuclear transcription factor kappa Ba (IκBa) protein and increased the cellular IκBa level by reducing phosphorylation and promoting ubiquitination of the IκBa protein. Meanwhile, KCNQ1OT1 promoted the expression of IκBa by sponging miR-221. The effects of KCNQ1OT1 knockdown on promoting VSMC proliferation, migration, and secretion of inflammatory factors were abolished by IκBa overexpression. The roles of KCNQ1OT1 in reducing the intimal area and inhibiting IκBa expression were proved in the VG mouse model after KCNQ1OT1 overexpression. In conclusion, KCNQ1OT1 attenuated intimal hyperplasia by suppressing the inflammation and proliferation of VSMCs, in which the mechanism upregulated IκBa expression by binding to the IκBa protein and sponging miR-221.

Toll-like receptor 4-mediated respiratory syncytial virus disease and lung transcriptomics in differentially susceptible inbred mouse strains

Respiratory syncytial virus (RSV) causes severe lower respiratory tract disease in infants, young children, and susceptible adults. The pathogenesis of RSV disease is not fully understood, although toll-like receptor 4 (TLR4)-related innate immune response is known to play a role. The present study was designed to determine TLR4-mediated disease phenotypes and lung transcriptomics and to elucidate transcriptional mechanisms underlying differential RSV susceptibility in inbred strains of mice. Dominant negative Tlr4 mutant (C3H/HeJ, HeJ, Tlr4^Lps-d) and its wild-type (C3H/HeOuJ, OuJ, Tlr4^Lps-n) mice and five genetically diverse, differentially responsive strains bearing the wild-type Tlr4^Lps-n allele were infected with RSV. Bronchoalveolar lavage, histopathology, and genome-wide transcriptomics were used to characterize the pulmonary response to RSV. RSV-induced lung neutrophilia [1 day postinfection (pi)], epithelial proliferation (1 day pi), and lymphocytic infiltration (5 days pi) were significantly lower in HeJ compared with OuJ mice. Pulmonary RSV expression was also significantly suppressed in HeJ than in OuJ. Upregulation of immune/inflammatory (Cxcl3, Saa1) and heat shock protein (Hspa1a, Hsph1) genes was characteristic of OuJ mice, while cell cycle and cell death/survival genes were modulated in HeJ mice following RSV infection. Strain-specific transcriptomics suggested virus-responsive (Oasl1, Irg1, Mx1) and epidermal differentiation complex (Krt4, Lce3a) genes may contribute to TLR4-independent defense against RSV in resistant strains including C57BL/6J. The data indicate that TLR4 contributes to pulmonary RSV pathogenesis and activation of cellular immunity, the inflammasome complex, and vascular damage underlies it. Distinct transcriptomics in differentially responsive Tlr4-wild-type strains provide new insights into the mechanism of RSV disease and potential therapeutic targets.

A novel CD147 inhibitor, SP-8356, reduces neointimal hyperplasia and arterial stiffness in a rat model of partial carotid artery ligation

Background

Neointimal hyperplasia and its related arterial stiffness are the crucial pathophysiological features in atherosclerosis and in-stent restenosis. Cluster of differentiation 147 (CD147), a member of the immunoglobulin super family that induces the expression of matrix metalloproteinase-9 (MMP-9) by dimerization, may play important roles in neointimal hyperplasia and may therefore be an effective target for the treatment of this condition. Here, we investigated whether a novel CD147 inhibitor SP-8356 ((1S,5R)-4-(3,4-dihydroxy-5-methoxystyryl)-6,6-dimethylbicyclo[3.1.1]hept-3-en-2-one) reduces neointimal hyperplasia and arterial stiffness in a rat model of partial carotid artery ligation.

Methods

Neointimal hyperplasia was induced in Sprague–Dawley rats by partial ligation of the right carotid artery combined with a high fat diet and vitamin D injection. Rats were subdivided into vehicle, SP-8356 (50 mg/kg), and rosuvastatin (10 mg/kg) groups. The drugs were administrated via intraperitoneal injections for 4 weeks. The elasticity of blood vessels was assessed by measuring pulse wave velocity using Doppler ultrasonography before sacrifice. Histomolecular analysis was carried out on harvested carotid arteries.

Results

SP-8356 significantly reduced MMP activity by inhibiting CD147 dimerization. SP-8356 reduced neointimal hyperplasia and prevented the deterioration of vascular elasticity. SP-8356 had a greater inhibitory effect on neointimal hyperplasia than did rosuvastatin. Furthermore, rosuvastatin did not improve vascular elasticity. SP-8356 increased the expression of smooth muscle myosin heavy chain (SM-MHC), but decreased the expression of collagen type III and MMP-9 in the neointimal region. In contrast to SP-8356, rosuvastatin did not alter the expression of SM-MHC or MMP-9.

Conclusions

The ability of SP-8356 to reduce neointimal hyperplasia and improve arterial stiffness in affected carotid artery suggests that SP-8356 could be a promising therapeutic drug for vascular remodeling disorders involving neointimal hyperplasia and arterial stiffness.

Deregulation of TLR4 signaling pathway characterizes Bicuspid Aortic valve syndrome

Bicuspid aortic valve (BAV) disease is recognized to be a syndrome with a complex and multifaceted pathophysiology. Its progression is modulated by diverse evolutionary conserved pathways, such as Notch-1 pathway. Emerging evidence is also highlighting the key role of TLR4 signaling pathway in the aortic valve pathologies and their related complications, such as sporadic ascending aorta aneurysms (AAA). Consistent with these observations, we aimed to evaluate the role of TLR4 pathway in both BAV disease and its common complication, such as AAA. To this aim, 70 subjects with BAV (M/F 50/20; mean age: 58.8 ± 14.8 years) and 70 subjects with tricuspid aortic valve (TAV) (M/F 35/35; mean age: 69.1 ± 12.8 years), with and without AAA were enrolled. Plasma assessment, tissue and gene expression evaluations were performed. Consistent with data obtained in the previous study on immune clonotypic T and B altered responses, we found reduced levels of systemic TNF-α, IL-1, IL-6, IL-17 cytokines in BAV cases, either in the presence or absence of AAA, than TAV cases (p < 0.0001 by ANOVA test). Interestingly, we also detected reduced levels of s-TLR4 in BAV cases with or without AAA in comparison to the two groups of TAV subjects (p < 0.0001 by ANOVA test). These results may suggest a deregulation in the activity or in the expression of TLR4 signaling pathway in all BAV cases. Portrait of these data is, indeed, the significantly decreased gene expression of inflammatory cytokines and TLR4, in both normal and aneurysmatic tissue samples, from BAV with AAA than TAV with AAA. In conclusion, our study demonstrates that subjects with BAV display a significant deregulation of TLR4 signaling pathway paralleled by a deregulation of Notch-1 pathway, as previously showed. This data suggests that the crosstalk between the Notch-1 and TLR4 signaling pathways may play a crucial role in both physiological embryological development, and homeostasis and functionality of aortic valve in adult life.

Wall shear stress promotes intimal hyperplasia through the paracrine H2O2-mediated NOX-AKT-SVV axis

AIMS

Oscillatory wall shear stress (WSS)-linked oxidative stress promotes intimal hyperplasia (IH) development, but the underlying mechanisms are not completely understood.

MATERIALS AND METHODS

We used an in vivo rabbit carotid arterial stenosis model representing different levels of WSS and found that WSS was increased at 1 month with 50% stenosis and was accompanied by VSMCs proliferation and interstitial collagen accumulation. Increased WSS promoted the expression of NOX, AKT, and survivin (SVV) and the proliferation/migration of VSMCs and reduced apoptosis.

KEY FINDINGS

Our in vitro study suggested that H₂O₂ promoted proliferation and migration while suppressing apoptosis in cultured human umbilical vascular endothelial cells.

SIGNIFICANCE

We demonstrated that the elevation of WSS promotes VSMC proliferation and migration through the H₂O₂-mediated NOX-AKT-SVV axis, thereby accelerating IH development.

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

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

Sessile Innate Immune Cells

In this chapter, sessile cells of the innate immune system are briefly introduced. Defined as cells equipped with diverse pattern recognition molecules capable of detecting MAMPs and DAMPs, they encompass cells such as epithelial cells, fibroblasts, vascular cells, chondrocytes, osteoblasts, and adipocytes. Located at the body surfaces, epithelial cells represent the first line of innate immune defense against invading microbial pathogens. They are significant contributors to innate mucosal immunity and generate various antimicrobial defense mechanisms. Also, epithelial cells critically contribute to tissue repair via the phenomenon of re-epithelialization. Fibroblasts operate as classical sentinel cells of the innate immune system dedicated to responding to MAMPs and DAMPs emitted upon any tissue injury. Typically, fibroblasts synthesize most of the extracellular matrix of connective tissues, thereby playing a crucial role in tissue repair processes. Vascular cells of the innate immune system represent an evolutionarily developed first-line defense against any inciting insult hitting the vessel walls from the luminal side including bacteria, viruses, microbial toxins, and chemical noxa such as nicotine. Upon such insults and following recognition of MAMPs and DAMPs, vascular cells react with an innate immune response to create an acute inflammatory milieu in the vessel wall aimed at curing the vascular injury concerned. Chondrocytes, osteoblasts, and osteoclasts represent other vital cells of the skeletal system acting as cells of the innate immune system in its wider sense. These cells mediate injury-promoted DAMP-induced inflammatory and regenerative processes specific for the skeletal systems. Finally, adipocytes are regarded as highly active cells of the innate immune system. As white, brown, and beige adipocytes, they operate as a dynamic metabolic organ that can secrete certain bioactive molecules which have endocrine, paracrine, and autocrine actions.

Acute toll-like receptor 4 activation impairs rat renal microvascular autoregulatory behaviour

AIM

Little is known about how toll-like receptor 4 (TLR4) influences the renal microvasculature. We hypothesized that acute TLR4 stimulation with lipopolysaccharide (LPS) impairs afferent arteriole autoregulatory behaviour, partially through reactive oxygen species (ROS).

METHODS

We assessed afferent arteriole autoregulatory behaviour after LPS treatment (1 mg kg^-1 ; i.p.) using the in vitro blood-perfused juxtamedullary nephron preparation. Autoregulatory behaviour was assessed by measuring diameter responses to stepwise changes in renal perfusion pressure. TLR4 expression was assessed by immunofluorescence, immunohistochemistry and Western blot analysis in the renal cortex and vasculature.

RESULTS

Baseline arteriole diameter at 100 mmHg averaged 15.2 ± 1.2 μm and 12.2 ± 1.0 μm for control and LPS groups (P < 0.05) respectively. When perfusion pressure was increased in 15 mmHg increments from 65 to 170 mmHg, arteriole diameter in control kidneys decreased significantly to 69 ± 6% of baseline diameter. In the LPS-treated group, arteriole diameter remained essentially unchanged (103 ± 9% of baseline), indicating impaired autoregulatory behaviour. Pre-treatment with anti-TLR4 antibody or the TLR4 antagonist, LPS-RS, preserved autoregulatory behaviour during LPS treatment. P2 receptor reactivity was normal in control and LPS-treated rats. Pre-treatment with Losartan (angiotensin type 1 receptor blocker; (AT₁ ) 2 mg kg^-1 ; i.p.) increased baseline afferent arteriole diameter but did not preserve autoregulatory behaviour in LPS-treated rats. Acute exposure to Tempol (10^-3 mol L^-1 ), a superoxide dismutase mimetic, restored pressure-mediated vasoconstriction in kidneys from LPS-treated rats.

CONCLUSION

These data demonstrate that TLR4 activation impairs afferent arteriole autoregulatory behaviour, partially through ROS, but independently of P2 and AT₁ receptor activation.

Age-related Impairment of Vascular Structure and Functions

Among age-related diseases, cardiovascular and cerebrovascular diseases are major causes of death. Vascular dysfunction is a key characteristic of these diseases wherein age is an independent and essential risk factor. The present work will review morphological alterations of aging vessels in-depth, which includes the discussion of age-related microvessel loss and changes to vasculature involving the capillary basement membrane, intima, media, and adventitia as well as the accompanying vascular dysfunctions arising from these alterations.

Toll-like receptor-4 signaling pathway in aorta aging and diseases: "its double nature"

Recent advances in the field of innate immunity have revealed a complex role of innate immune signaling pathways in both tissue homeostasis and disease. Among them, the Toll-like receptor 4 (TLR-4) pathways has been linked to various pathophysiological conditions, such as cardiovascular diseases (CVDs). This has been interrogated by developing multiple laboratory tools that have shown in animal models and clinical conditions, the involvement of the TLR-4 signaling pathway in the pathophysiology of different CVDs, such as atherosclerosis, ischemic heart disease, heart failure, ischemia-reperfusion injury and aorta aneurysm. Among these, aorta aneurysm, a very complex pathological condition with uncertain etiology and fatal complications (i.e. dissection and rupture), has been associated with the occurrence of high risk cardiovascular conditions, including thrombosis and embolism. In this review, we discuss the possible role of TLR-4 signaling pathway in the development of aorta aneurysm, considering the emerging evidence from ongoing investigations. Our message is that emphasizing the role of TLR-4 signaling pathway in aorta aneurysm may serve as a starting point for future studies, leading to a better understanding of the pathophysiological basis and perhaps the effective treatment of this difficult human disease.

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.

Toll-like receptor 4 mediates vascular remodeling in hyperhomocysteinemia

Although hyperhomocysteinemia (HHcy) is known to promote downstream pro-inflammatory cytokine elevation, the precise mechanism is still unknown. One of the possible receptors that could have significant attention in the field of hypertension is toll-like receptor 4 (TLR-4). TLR-4 is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. Its mutation can attenuate the effects of HHcy-mediated vascular inflammation and mitochondria- dependent cell death that suppresses hypertension. In this review, we observed that HHcy induces vascular remodeling through immunological adaptation, promoting inflammatory cytokine up-regulation (IL-1β, IL-6, TNF-α) and initiation of mitochondrial dysfunction leading to cell death and chronic vascular inflammation. The literature suggests that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death inducing peripheral vascular remodeling. In the previous studies, we have characterized the role of TLR-4 mutation in attenuating vascular remodeling in hyperhomocysteinemia. This review includes, but is not limited to, the physiological synergistic aspects of the downstream elevation of cytokines found within the vascular inflammatory cascade. These events subsequently induce mitochondrial dysfunction defined by excessive mitochondrial fission and mitochondrial apoptosis contributing to vascular remodeling followed by hypertension.

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.

Apocynin inhibits Toll-like receptor-4-mediated activation of NF-κB by suppressing the Akt and mTOR pathways

Microbial product lipopolysaccharide has been shown to be involved in the pathogenesis of inflammatory skin diseases. Apocynin has demonstrated to have an anti-inflammatory effect. However, the effect of apocynin on the Toll-like receptor-4-dependent activation of Akt, mammalian target of rapamycin (mTOR), and nuclear factor (NF)-κB pathway, which is involved in productions of inflammatory mediators in keratinocytes, has not been studied. Using human keratinocytes, we investigated the effect of apocynin on the inflammatory mediator production in relation to the Toll-like receptor-4-mediated-Akt/mTOR and NF-κB pathways, which regulates the transcription genes involved in immune and inflammatory responses. Apocynin, Akt inhibitor SH-5, Bay 11-7085 and N-acetylcysteine each attenuated the lipopolysaccharide-induced production of cytokines, PGE₂, and chemokines, changes in the levels of Toll-like receptor-4, p-Akt, mTOR, and NF-κB, and production of reactive oxygen species in keratinocytes. The results show that apocynin appears to attenuate the lipopolysaccharide-stimulated production of inflammatory mediators in keratinocytes by suppressing the Toll-like receptor-4-mediated activation of the Akt, mTOR, and NF-κB pathways. The effect of apocynin appears to be attributed to its inhibitory effect on the production of reactive oxygen species. Apocynin appears to attenuate the microbial product-mediated inflammatory skin diseases.

Thiamylal sodium increased inflammation and the proliferation of vascular smooth muscle cells

Background

Thiamylal sodium is a common anesthetic barbiturate prepared in alkaline solution for clinical use. There is no previously reported study on the effects of barbiturates on the inflammation and proliferation of vascular smooth muscle cells (VSMCs). Here, we examined the effects of clinical-grade thiamylal sodium solution (TSS) on the inflammation and proliferation of rat VSMCs.

Methods

Expression levels of interleukin (IL)-1α, IL-1β, IL-6, and toll-like receptors in rat VSMCs were detected by quantitative reverse transcription-polymerase chain reaction and microarray analyses. The production of IL-6 by cultured VSMCs or ex vivo-cultured rat aortic segments was detected in supernatants by enzyme-linked immunosorbent assay. VSMC proliferation and viability were determined by the water-soluble tetrazolium-1 assay and trypan blue staining, respectively.

Results

TSS increased expression of IL-1α, IL-6, and TLR4 in VSMCs in a dose-dependent manner, and reduced IL-1β expression. Ex vivo TSS stimulation of rat aorta also increased IL-6. Low concentrations of TSS enhanced VSMC proliferation, while high concentrations reduced both cell proliferation and viability. Expression of IL-1 receptor antagonist, which regulates cell proliferation, was not increased by TSS stimulation. Exposure of cells to the TSS additive, sodium carbonate, resulted in significant upregulation of IL-1α and IL-6 mRNA levels, to a greater extent than TSS.

Conclusions

TSS-induced proinflammatory cytokine production by VSMCs is caused by sodium carbonate. However, pure thiamylal sodium has an anti-inflammatory effect in VSMCs. TSS exposure to VSMCs may promote vascular inflammation, leading to the progression of atherosclerosis or in-stent restenosis, resulting in vessel bypass graft failure.

Toll-like receptor 4 signaling has a critical role in Porphyromonas gingivalis-accelerated neointimal formation after arterial injury in mice

Recently, we reported that a periodontopathic pathogen, Porphyromonas gingivalis (P. gingivalis), infection induced neointimal hyperplasia with enhanced expression of monocyte chemoattractant protein (MCP)-1 after arterial injury in wild-type mice. Toll-like receptor (TLR) 4 is known to be a key receptor for virulence factors of P. gingivalis. The aim of this study is to assess the hypothesis that TLR4 has a critical role in periodontopathic bacteria-induced neointimal formation after an arterial injury. Wild-type and TLR4-deficient mice were used in this study. The femoral arteries were injured, and P. gingivalis or vehicle was injected subcutaneously once per week. Fourteen days after arterial injury, murine femoral arteries were obtained for histopathological and immunohistochemical analyses. The anti-P. gingivalis IgG levels in P. gingivalis-infected groups were significantly increased compared with the anti-P. gingivalis IgG levels of the corresponding non-infected groups in both wild-type and TLR4-deficient mice. TLR4 deficiency negated P. gingivalis-induced neointimal formation compared with that observed in wild-type mice and reduced the number of MCP-1 positive cells in the neointimal area. We conclude that P. gingivalis infection may promote neointimal formation after an arterial injury through TLR4 signaling.

PPARγ Inhibits VSMC Proliferation and Migration via Attenuating Oxidative Stress through Upregulating UCP2

Increasing evidence showed that abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are common event in the pathophysiology of many vascular diseases, including atherosclerosis and restenosis after angioplasty. Among the underlying mechanisms, oxidative stress is one of the principal contributors to the proliferation and migration of VSMCs. Oxidative stress occurs as a result of persistent production of reactive oxygen species (ROS). Recently, the protective effects of peroxisome proliferator-activated receptor γ (PPARγ) against oxidative stress/ROS in other cell types provide new insights to inhibit the suggests that PPARγ may regulate VSMCs function. However, it remains unclear whether activation of PPARγ can attenuate oxidative stress and further inhibit VSMC proliferation and migration. In this study, we therefore investigated the effect of PPARγ on inhibiting VSMC oxidative stress and the capability of proliferation and migration, and the potential role of mitochondrial uncoupling protein 2 (UCP2) in oxidative stress. It was found that platelet derived growth factor-BB (PDGF-BB) induced VSMC proliferation and migration as well as ROS production; PPARγ inhibited PDGF-BB-induced VSMC proliferation, migration and oxidative stress; PPARγ activation upregulated UCP2 expression in VSMCs; PPARγ inhibited PDGF-BB-induced ROS in VSMCs by upregulating UCP2 expression; PPARγ ameliorated injury-induced oxidative stress and intimal hyperplasia (IH) in UCP2-dependent manner. In conclusion, our study provides evidence that activation of PPARγ can attenuate ROS and VSMC proliferation and migration by upregulating UCP2 expression, and thus inhibit IH following carotid injury. These findings suggest PPARγ may represent a prospective target for the prevention and treatment of IH-associated vascular diseases.

Toll-like receptors 2 and 4 mediate hyperglycemia induced macrovascular aortic endothelial cell inflammation and perturbation of the endothelial glycocalyx

OBJECTIVES

Hyperglycemia-induced inflammation is central to the vascular complications in diabetes. Toll-like receptors (TLRs) are key players in regulating inflammatory responses. There are sparse data on the role of TLR2 and TLR4 in regulating human macrovascular aortic endothelial cells (HMAECs) inflammation and glycocalyx dysfunction under hyperglycemia. We examined the role of TLR2/4 in the above dysfunctions in HMAEC under high glucose (HG) conditions.

METHODS

HMAECs were treated with high or normal glucose and TLR-2, TLR-4, MyD88, IRF3, TRIF, nuclear NF-κB p65, IL-8, IL-1β, TNF-α, MCP-1, ICAM-1, sVCAM-1, monocyte adhesion to HMAECs, heparan sulfate and hyaluronic acid were measured.

RESULTS

HG upregulated TLR2 and TLR4 mRNA and protein and increased both MyD88 and non-MyD88 pathways, NF-κB p65, inflammatory biomediators, and monocyte adhesion to HMAECs. Heparan sulfate protein expression was reduced and hyaluronic acid secretion was increased on HG exposure. Inhibition of TLR2 and TLR4 signaling by inhibitory peptides and knockdown of TLR-2 and TLR-4 gene expression by siRNA attenuated HG induced inflammation, leukocyte adhesion and glycocalyx dysfunction. An increase in ROS paralleled the increase in TLR-2/4 and antioxidants treatment reduced TLR-2/4 expression and downstream inflammatory biomediators.

CONCLUSION

Thus hyperglycemia induces HMAEC inflammation and glycocalyx dysfunction through TLR-2/4 pathway activation via increased ROS.

Toll-like receptors mediating vascular malfunction: Lessons from receptor subtypes

Toll-like receptors (TLR) are a subfamily of pattern recognition receptors (PRR) implicated in a variety of vascular abnormalities. However, the pathophysiological role and the interplay between different TLR-mediated innate and adaptive immune responses during the development of vascular diseases remain largely unspecified. TLR are widely distributed in both immune and nonimmune cells in the blood vessel wall. The expressions and locations of TLR are dynamically regulated in response to distinct molecular patterns derived from pathogens or damaged host cells. As a result, the outcome of TLR signaling is agonist- and cell type-dependent. A better understanding of discrete TLR signaling pathways in the vasculature will provide unprecedented opportunities for the discovery of novel therapies in many inflammatory vascular diseases. The present brief review discusses the role of individual TLR in controlling cellular functions of the vascular system, by focusing on the inflammatory responses within the blood vessel wall which contribute to the development of hypertension and atherosclerosis.

Mechanical stretch-induced vascular hypertrophy occurs through modulation of leptin synthesis-mediated ROS formation and GATA-4 nuclear translocation

Background: Obesity and hypertension are associated with increased leptin production contributing to cardiovascular remodeling. Mechanisms involving mechanical stretch-induced leptin production and the cross talk between signaling pathways leading to vascular remodeling have not been fully elucidated.

Methods and Results: Rat portal vein (RPV) organ culture was used to investigate the effect of mechanical stretch on leptin protein expression in vascular smooth muscle cells (VSMCs). Moreover, the involvement of reactive oxygen species (ROS), the RhoA/ROCK pathway, actin cytoskeleton dynamics and the transcriptional factor GATA-4 activation in mechanical stretch-induced vascular remodeling were investigated. Stretching the RPV for 1 or 24 h significantly increased leptin protein level and ROS formation in VSMCs, which was prevented by 1 h pretreatment with the ROCK inhibitor Y-27632 and the actin cytoskeleton depolymerization agent cytochalasin D. Moreover, Western blotting and immunohistochemistry revealed that mechanical stretch or treatment with 3.1 nmol/L leptin for 24 h significantly increased actin polymerization, as reflected by an increase in the F-actin to G-actin ratio. Increases in blood vessels’ wet weight and [³H]-leucine incorporation following a 24 h treatment with conditioned media from cultured stretched RPVs indicated RPV hypertrophy. This effect was prevented by 1 h pretreatment with anti-leptin antibody, indicating leptin’s crucial role in promoting VSMC hypertrophy. As an index of GATA-4 activation, GATA-4 nuclear translocation was assessed by immunohistochemistry method. Pretreating VSMC with leptin for 1 h significantly activated GATA-4 nuclear translocation, which was potently attenuated by the NADPH oxidase inhibitor apocynin, Y-27632, and cytochalasin D.

Conclusion: Our results demonstrate that ROS formation, RhoA/ROCK pathway, and GATA-4 activation play a pivotal role in mechanical stretch-induced leptin synthesis leading to VSMC remodeling.

MiR-31 modulates coelomocytes ROS production via targeting p105 in Vibrio splendidus challenged sea cucumber Apostichopus japonicus in vitro and in vivo

MiR-31 is a critical regulator of gene expression in many pathogenic processes in vertebrates. In this study, we identified p105 as a novel target of miR-31 in Apostichopus japonicus and investigated their regulatory roles in vitro and in vivo. The negative expression profiles between miR-31 and Ajp105 were detected in both LPS-exposed primary coelomocytes and Vibrio splendidus-challenged sea cucumber. Co-infection miR-31 mimics significantly depressed the expression of Ajp105 and increased ROS production in vitro. In contrast, miR-31 inhibitor significantly elevated the expression of Ajp105 and decreased ROS level. Consistently, miR-31 over-expression or Ajp105 silencing in vivo both greatly promoted ROS accumulation. Taken together, our findings confirmed that miR-31 could modulate respiratory burst via targeting Ajp105 during sea cucumber pathological development.

Involvement of interleukin-1 receptor-associated kinase-1 in vascular smooth muscle cell proliferation and neointimal formation after rat carotid injury

OBJECTIVE

Reduced frequency of atherosclerotic plaques is observed in interleukin-1 receptor-associated kinase-1 (IRAK1)-deficient mice; however, the underlying mechanism is not clear. Therefore, this study investigate the role of IRAK1 in vascular smooth muscle cell proliferation and neointimal hyperplasia.

APPROACH AND RESULTS

Stimulation of rat primary vascular smooth muscle cells with fetal bovine serum (10%) or platelet-derived growth factor-BB (20 ng/mL) for 15 minutes to 24 hours induced a time-dependent increase in IRAK1 and extracellular signal-regulated kinase (ERK) activation, proliferating cell nuclear antigen upregulation and p27Kip1 downregulation as assessed by Western blotting. Inhibitors of ERK pathway (U0126, 10 μmol/L), IRAK (IRAK1/4, 3 μmol/L), protein kinase C (PKC; Ro-31-8220, 1 μmol/L), siRNA of toll-like receptor-4 (200 nmol/L), and PKC-ε (200 nmol/L) significantly attenuated these changes. Platelet-derived growth factor induced endogenous IRAK-ERK-PKC-ε association in a toll-like receptor-4 and PKC-ε-dependent manner. A time-dependent increase in IRAK1 and ERK activation was observed after 15 minutes, 30 minutes, 1 hour, 6 hours, 12 hours, and 24 hours of carotid balloon injury in rats. Balloon injury induced endogenous IRAK-ERK-PKC-ε interaction. Perivascular application of IRAK1/4 inhibitor (100 μmol/L), U0126 (100 μmol/L), and IRAK1 siRNA (220 and 360 nmol/L) in pluronic gel abrogated balloon injury-induced ERK phosphorylation, activation, and p27Kip1 downregulation. Hematoxylin and eosin staining and immunohistochemistry of proliferating cell nuclear antigen and smooth muscle actin demonstrated that balloon injury-induced intimal thickening and neointimal vascular smooth muscle cell proliferation were significantly abrogated in the presence of IRAK1/4 inhibitor, IRAK1 siRNA, and U0126.

CONCLUSIONS

IRAK1 mediates vascular smooth muscle cell proliferation and neointimal hyperplasia by regulating PKC-ε-IRAK1-ERK axis.

Low levels of lipopolysaccharide modulate mitochondrial oxygen consumption in skeletal muscle

OBJECTIVE

We have previously demonstrated that activation of toll-like receptor 4 (TLR4) in skeletal muscle results in an increased reliance on glucose as an energy source and a concomitant decrease in fatty acid oxidation under basal conditions. Herein, we examined the effects of lipopolysaccharide (LPS), the primary ligand for TLR4, on mitochondrial oxygen consumption in skeletal muscle cell culture and mitochondria isolated from rodent skeletal muscle.

MATERIALS/METHODS

Skeletal muscle cell cultures were exposed to LPS and oxygen consumption was assessed using a Seahorse Bioscience extracellular flux analyzer. Mice were also exposed to LPS and oxygen consumption was assessed in mitochondria isolated from skeletal muscle.

RESULTS

Acute LPS exposure resulted in significant reductions in Carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP)-stimulated maximal respiration (state 3u) and increased oligomycin induced state 4 (state 4O) respiration in C2C12 and human primary myotubes. These findings were observed in conjunction with increased mRNA of uncoupling protein 3 (UCP3), superoxide dismutase 2 (SOD2), and pyruvate dehydrogenase activity. The LPS-mediated changes in substrate oxidation and maximal mitochondrial respiration were prevented in the presence of the antioxidants N-acetylcysteine and catalase, suggesting a potential role of reactive oxygen species in mediating these effects. Mitochondria isolated from red gastrocnemius and quadriceps femoris muscle from mice injected with LPS also demonstrated reduced respiratory control ratio (RCR), and ADP- and FCCP-stimulated respiration.

CONCLUSION

LPS exposure in skeletal muscle alters mitochondrial oxygen consumption and substrate preference, which is absent when antioxidants are present.

Ligustrazine attenuates the platelet-derived growth factor-BB-induced proliferation and migration of vascular smooth muscle cells by interrupting extracellular signal-regulated kinase and P38 mitogen-activated protein kinase pathways

The abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) leads to intimal thickening of the aorta and is, therefore, important in the development of arteriosclerosis. As a result, the use of antiproliferative and antimigratory agents for VSMCs offers promise for the treatment of vascular disorders. Although several studies have demonstrated that ligustrazine may be used to treat heart and blood vessel diseases, the detailed mechanism underlying its actions remain to be elucidated. In the present study, the inhibitory effect of ligustrazine on platelet-derived growth factor (PDGF)-BB-stimulated VSMC proliferation and migration, and the underlying mechanisms were investigated. The findings demonstrated that ligustrazine significantly inhibited PDGF-BB-stimulated VSMC proliferation. VSMCs dedifferentiated into a proliferative phenotype under PDGF-BB stimulation, which was effectively reversed by the administration of ligustrazine. In addition, ligustrazine also downregulated the production of nitric oxide and cyclic guanine monophosphate, induced by PDGF-BB. Additionally, ligustrazine significantly inhibited PDGF-BB-stimulated VSMC migration. Mechanistic investigation indicated that the upregulation of cell cycle-associated proteins and the activation of the extracellular signal-regulated kinase (ERK) and P38 mitogen-activated protein kinase (MAPK) signaling induced by PDGF-BB was suppressed by the administration of ligustrazine. In conclusion, the present study, demonstrated for the first time, to the best of our knowledge, that ligustrazine downregulated PDGF-BB-induced VSMC proliferation and migration partly, at least, through inhibiting the activation of the ERK and P38 MAPK signaling.

Effects of apocynin, an NADPH oxidase inhibitor, on levels of ADMA, MPO, iNOS and TLR4 induced by myocardial ischemia reperfusion

PURPOSE

In this study, the effects of apocynin, an NADPH oxidase inhibitor, on the levels of inducible nitric oxide synthase (iNOS) and the toll-like receptor 4 (TLR4), which are inflammatory mediators in myocardial ischemia-reperfusion (MIR) injury, and myeloperoxidase (MPO), which is the indicator of neutrophil infiltration and the endogenous nitric oxide synthase inhibitor asymmetric dimethyl arginine (ADMA) increasing with oxidative stress were investigated.

METHODS

MIR injury was accomplished by the application of occlusion for 30 minutes and reperfusion for 120 minutes in the left anterior descending artery (LAD). In the study, 21 Sprague-Dawley male rats were divided into three groups: a sham group (n = 7); a MIR group (n = 7); and a MIR + apocynin treatment group (n = 7, before the procedure, an intraperitoneal administration of 10 mg/kg of apocynin for 15 days). After reperfusion, iNOS, TLR4, MPO and ADMA levels in myocardial tissue were measured by ELISA.

RESULTS

While myocardial TLR4, MPO and ADMA levels increased in the MIR group, these parameters were found to be decreased significantly in the group treated with apocynin. Although iNOS levels showed an increase in the MIR group compared to the sham group and a reduction in the MIR+apocynin group, there was no statistically significant difference between the groups.

DISCUSSION

In our study, the effect of the treatment of apocynin in MIR on ADMA, MPO, iNOS and TLR4 levels in myocardial tissue was shown for the first time. It is thought that apocynin treatment may show a protective effect in MIR injury by affecting oxidative stress (ADMA) and inflammatory parameters (iNOS, MPO).

Astragaloside IV inhibits platelet-derived growth factor-BB-stimulated proliferation and migration of vascular smooth muscle cells via the inhibition of p38 MAPK signaling

Astragaloside IV (AS-IV), the major active component extracted from Astragalus membranaceus, has been demonstrated to exhibit protective effects on the cardiovascular, immune, digestive and nervous systems; thus, has been widely used in traditional Chinese medicine. Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) is closely associated with the initiation and progression of cardiovascular diseases, including atherosclerosis and restenosis. However, the effects of AS-IV on VSMCs remain unknown. For the first time, the present study demonstrated that AS-IV markedly suppressed platelet-derived growth factor (PDGF)-BB-stimulated cellular proliferation and migration of HDMEC-a human dermal VSMCs (HDVSMCs). Further investigation into the underlying molecular mechanisms demonstrated that the administration of AS-IV attenuated the PDGF-BB-stimulated switch of HDVSMCs into a proliferative phenotype. Furthermore, AS-IV inhibited the PDGF-BB-induced expression of cell cycle-associated proteins, as well as the upregulation of matrix metalloproteinase (MMP)2, but not MMP9. In addition, AS-IV was shown to downregulate the activation of p38 mitogen-activated protein kinase (MAPK) signaling induced by PDGF-BB in HDVSMCs. Therefore, the observations of the present study indicate that AS-IV inhibits PDGF-BB-stimulated VSMC proliferation and migration, possibly by inhibiting the activation of the p38 MAPK signaling pathway. Thus, AS-IV may be useful for the treatment of vascular diseases.

Toll-like receptor 4 upregulation by angiotensin II contributes to hypertension and vascular dysfunction through reactive oxygen species production

Hypertension is considered as a low-grade inflammatory disease, with adaptive immunity being an important mediator of this pathology. TLR4 may have a role in the development of several cardiovascular diseases; however, little is known about its participation in hypertension. We aimed to investigate whether TLR4 activation due to increased activity of the renin-angiotensin system (RAS) contributes to hypertension and its associated endothelial dysfunction. For this, we used aortic segments from Wistar rats treated with a non-specific IgG (1 µg/day) and SHRs treated with losartan (15 mg/kg·day), the non-specific IgG or the neutralizing antibody anti-TLR4 (1 µg/day), as well as cultured vascular smooth muscle cells (VSMC) from Wistar and SHRs. TLR4 mRNA levels were greater in the VSMC and aortas from SHRs compared with Wistar rats; losartan treatment reduced those levels in the SHRs. Treatment of the SHRs with the anti-TLR4 antibody: 1) reduced the increased blood pressure, heart rate and phenylephrine-induced contraction while it improved the impaired acetylcholine-induced relaxation; 2) increased the potentiation of phenylephrine contraction after endothelium removal; and 3) abolished the inhibitory effects of tiron, apocynin and catalase on the phenylephrine-induced response as well as its enhancing effect of acetylcholine-induced relaxation. In SHR VSMCs, angiotensin II increased TLR4 mRNA levels, and losartan reduced that increase. CLI-095, a TLR4 inhibitor, mitigated the increases in NAD(P)H oxidase activity, superoxide anion production, migration and proliferation that were induced by angiotensin II. In conclusion, TLR4 pathway activation due to increased RAS activity is involved in hypertension, and by inducing oxidative stress, this pathway contributes to the endothelial dysfunction associated with this pathology. These results suggest that TLR4 and innate immunity may play a role in hypertension and its associated end-organ damage.

NADPH oxidase 1, a novel molecular source of ROS in hippocampal neuronal death in vascular dementia

AIMS

Chronic cerebral hypoperfusion (CCH) is a common pathological factor that contributes to neurodegenerative diseases such as vascular dementia (VaD). Although oxidative stress has been strongly implicated in the pathogenesis of VaD, the molecular mechanism underlying the selective vulnerability of hippocampal neurons to oxidative damage remains unknown. We assessed whether the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) complex, a specialized superoxide generation system, plays a role in VaD by permanent ligation of bilateral common carotid arteries in rats.

RESULTS

Male Wistar rats (10 weeks of age) were subjected to bilateral occlusion of the common carotid arteries (two-vessel occlusion [2VO]). Nox1 expression gradually increased in hippocampal neurons, starting at 1 week after 2VO and for approximately 15 weeks after 2VO. The levels of superoxide, DNA oxidation, and neuronal death in the CA1 subfield of the hippocampus, as well as consequential cognitive impairment, were increased in 2VO rats. Both inhibition of Nox by apocynin, a putative Nox inhibitor, and adeno-associated virus-mediated Nox1 knockdown significantly reduced 2VO-induced reactive oxygen species generation, oxidative DNA damage, hippocampal neuronal degeneration, and cognitive impairment.

INNOVATION AND CONCLUSION

We provided evidence that neuronal Nox1 is activated in the hippocampus under CCH, causing oxidative stress and consequential hippocampal neuronal death and cognitive impairment. This evidence implies that Nox1-mediated oxidative stress plays an important role in neuronal cell death and cognitive dysfunction in VaD. Nox1 may serve as a potential therapeutic target for VaD.

The oxygen-rich postnatal environment induces cardiomyocyte cell-cycle arrest through DNA damage response

The mammalian heart has a remarkable regenerative capacity for a short period of time after birth, after which the majority of cardiomyocytes permanently exit cell cycle. We sought to determine the primary postnatal event that results in cardiomyocyte cell-cycle arrest. We hypothesized that transition to the oxygen-rich postnatal environment is the upstream signal that results in cell-cycle arrest of cardiomyocytes. Here, we show that reactive oxygen species (ROS), oxidative DNA damage, and DNA damage response (DDR) markers significantly increase in the heart during the first postnatal week. Intriguingly, postnatal hypoxemia, ROS scavenging, or inhibition of DDR all prolong the postnatal proliferative window of cardiomyocytes, whereas hyperoxemia and ROS generators shorten it. These findings uncover a protective mechanism that mediates cardiomyocyte cell-cycle arrest in exchange for utilization of oxygen-dependent aerobic metabolism. Reduction of mitochondrial-dependent oxidative stress should be an important component of cardiomyocyte proliferation-based therapeutic approaches.

Engineering biodegradable polyester elastomers with antioxidant properties to attenuate oxidative stress in tissues

Oxidative stress plays an important role in the limited biological compatibility of many biomaterials due to inflammation, as well as in various pathologies including atherosclerosis and restenosis as a result of vascular interventions. Engineering antioxidant properties into a material is therefore a potential avenue to improve the biocompatibility of materials, as well as to locally attenuate oxidative stress-related pathologies. Moreover, biodegradable polymers that have antioxidant properties built into their backbone structure have high relative antioxidant content and may provide prolonged, continuous attenuation of oxidative stress while the polymer or its degradation products are present. In this report, we describe the synthesis of poly(1,8-octanediol-co-citrate-co-ascorbate) (POCA), a citric-acid based biodegradable elastomer with native, intrinsic antioxidant properties. The in vitro antioxidant activity of POCA as well as its effects on vascular cells in vitro and in vivo were studied. Antioxidant properties investigated included scavenging of free radicals, iron chelation and the inhibition of lipid peroxidation. POCA reduced reactive oxygen species generation in cells after an oxidative challenge and protected cells from oxidative stress-induced cell death. Importantly, POCA antioxidant properties remained present upon degradation. Vascular cells cultured on POCA showed high viability, and POCA selectively inhibited smooth muscle cell proliferation, while supporting endothelial cell proliferation. Finally, preliminary data on POCA-coated ePTFE grafts showed reduced intimal hyperplasia when compared to standard ePTFE grafts. This biodegradable, intrinsically antioxidant polymer may be useful for tissue engineering application where oxidative stress is a concern.