Role of redox signaling and poly (adenosine diphosphate-ribose) polymerase activation in vascular smooth muscle cell growth inhibition by nitric oxide and peroxynitrite

Therapeutic potential of dietary flavonoid hyperoside against non-communicable diseases: targeting underlying properties of diseases

Non-communicable diseases (NCDs) are a global epidemic with diverse pathogenesis. Among them, oxidative stress and inflammation are the most fundamental co-morbid features. Therefore, multi-targets and multi-pathways therapies with significant anti-oxidant and anti-inflammatory activities are potential effective measures for preventing and treating NCDs. The flavonol glycoside compound hyperoside (Hyp) is widely found in a variety of fruits, vegetables, beverages, and medicinal plants and has various health benefits, especially excellent anti-oxidant and anti-inflammatory properties targeting nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB) signaling pathways. In this review, we summarize the pathogenesis associated with oxidative stress and inflammation in NCDs and the biological activity and therapeutic potential of Hyp. Our findings reveal that the anti-oxidant and anti-inflammatory activities regulated by Hyp are associated with numerous biological mechanisms, including positive regulation of mitochondrial function, apoptosis, autophagy, and higher-level biological damage activities. Hyp is thought to be beneficial against organ injuries, cancer, depression, diabetes, and osteoporosis, and is a potent anti-NCDs agent. Additionally, the sources, bioavailability, pharmacy, and safety of Hyp have been established, highlighting the potential to develop Hyp into dietary supplements and nutraceuticals.

The Etiology and Molecular Mechanism Underlying Smooth Muscle Phenotype Switching in Intimal Hyperplasia of Vein Graft and the Regulatory Role of microRNAs

Mounting evidence suggests that the phenotypic transformation of venous smooth muscle cells (SMCs) from differentiated (contractile) to dedifferentiated (proliferative and migratory) phenotypes causes excessive proliferation and further migration to the intima leading to intimal hyperplasia, which represents one of the key pathophysiological mechanisms of vein graft restenosis. In recent years, numerous miRNAs have been identified as specific phenotypic regulators of vascular SMCs (VSMCs), which play a vital role in intimal hyperplasia in vein grafts. The review sought to provide a comprehensive overview of the etiology of intimal hyperplasia, factors affecting the phenotypic transformation of VSMCs in vein graft, and molecular mechanisms of miRNAs involved in SMCs phenotypic modulation in intimal hyperplasia of vein graft reported in recent years.

PARPs in lipid metabolism and related diseases

PARPs and tankyrases (TNKS) represent a family of 17 proteins. PARPs and tankyrases were originally identified as DNA repair factors, nevertheless, recent advances have shed light on their role in lipid metabolism. To date, PARP1, PARP2, PARP3, tankyrases, PARP9, PARP10, PARP14 were reported to have multi-pronged connections to lipid metabolism. The activity of PARP enzymes is fine-tuned by a set of cholesterol-based compounds as oxidized cholesterol derivatives, steroid hormones or bile acids. In turn, PARPs modulate several key processes of lipid homeostasis (lipotoxicity, fatty acid and steroid biosynthesis, lipoprotein homeostasis, fatty acid oxidation, etc.). PARPs are also cofactors of lipid-responsive nuclear receptors and transcription factors through which PARPs regulate lipid metabolism and lipid homeostasis. PARP activation often represents a disruptive signal to (lipid) metabolism, and PARP-dependent changes to lipid metabolism have pathophysiological role in the development of hyperlipidemia, obesity, alcoholic and non-alcoholic fatty liver disease, type II diabetes and its complications, atherosclerosis, cardiovascular aging and skin pathologies, just to name a few. In this synopsis we will review the evidence supporting the beneficial effects of pharmacological PARP inhibitors in these diseases/pathologies and propose repurposing PARP inhibitors already available for the treatment of various malignancies.

Nitrosative Stress and Its Association with Cardiometabolic Disorders

Reactive nitrogen species (RNS) are formed when there is an abnormal increase in the level of nitric oxide (NO) produced by the inducible nitric oxide synthase (iNOS) and/or by the uncoupled endothelial nitric oxide synthase (eNOS). The presence of high concentrations of superoxide anions (O₂⁻) is also necessary for their formation. RNS react three times faster than O₂⁻ with other molecules and have a longer mean half life. They cause irreversible damage to cell membranes, proteins, mitochondria, the endoplasmic reticulum, nucleic acids and enzymes, altering their activity and leading to necrosis and to cell death. Although nitrogen species are important in the redox imbalance, this review focuses on the alterations caused by the RNS in the cellular redox system that are associated with cardiometabolic diseases. Currently, nitrosative stress (NSS) is implied in the pathogenesis of many diseases. The mechanisms that produce damage remain poorly understood. In this paper, we summarize the current knowledge on the participation of NSS in the pathology of cardiometabolic diseases and their possible mechanisms of action. This information might be useful for the future proposal of anti-NSS therapies for cardiometabolic diseases.

L-sepiapterin restores SLE serum-induced markers of endothelial function in endothelial cells

OBJECTIVE

SLE serves as an independent risk factor` for endothelial dysfunction (ED) not explained by Framingham risk factors. We sought to understand the development of SLE-induced ED on a cellular level in order to develop strategies aimed at reversing cellular abnormalities. This study assessed the impact of SLE patient serum on endothelial nitric oxide synthase (eNOS), nitric oxide (NO) production and functional changes in the cell.

METHODS

Human umbilical vein endothelial cells (HUVECs) cultured in serum of either SLE (n=25) or healthy patients (n=14) or endothelial basal medium 2 (EBM-2) culture media supplemented with fetal bovine serum with or without L-sepiapterin were used for our studies. We applied the fluorescent probe DAF-FM diacetate for intracellular NO detection using flow cytometry. Total RNA isolates were analysed using reverse transcription PCR for eNOS mRNA expression. Oxygen consumption rate was determined using seahorse analysis. Neutrophil adhesion and migration were determined using a calcein AM microscopy assay.

RESULTS

The mRNA expression of eNOS was increased in SLE cultured HUVECs compared with healthy control (p<0.05). The SLE eNOS mRNA level correlated with SLE patient age (p=0.008); however, this trend was not observed with healthy patients. SLE serum reduced NO production in HUVECs compared with EBM-2 cultured cells (p<0.05). Co-treatment of endothelial cells with L-sepiapterin preserved HUVEC capacity to produce NO in SLE conditions (p<0.01). SLE serum enhanced neutrophil migration (p<0.01) but not neutrophil adhesion compared with healthy controls. The bioenergetic health index was not different.

CONCLUSIONS

SLE likely causes disruption of endothelial cell eNOS function and NO modulated pathways.

Optimizing endothelial cell functionalization for cell therapy of vascular proliferative disease using a direct contact co-culture system

Increased susceptibility to thrombosis, neoatherosclerosis, and restenosis due to incomplete regrowth of the protective endothelial layer remains a critical limitation of the interventional strategies currently used clinically to relieve atherosclerotic obstruction. Rapid recovery of endothelium holds promise for both preventing the thrombotic events and reducing post-angioplasty restenosis, providing the rationale for developing cell delivery strategies for accelerating arterial reendothelialization. The successful translation of experimental cell therapies into clinically viable treatment modalities for restoring vascular endothelium critically depends on identifying strategies for enhancing the functionality of endothelial cells (EC) derived from high cardiovascular risk patients, the target group for the majority of angioplasty procedures. Enhancing EC-associated nitric oxide (NO) synthesis by inducing overexpression of NO synthase (NOS) has shown promise as a way of increasing paracrine activity and restoring function of EC. In the present study, we developed a direct contact co-culture approach compatible with highly labile effectors, such as NO, and applied it for determining the effect of EC functionalization via NOS gene transfer on the growth of co-cultured arterial smooth muscle cells (A10 cell line) exhibiting the defining characteristics of neointimal cells. Bovine aortic endothelial cells magnetically transduced with inducible NOS-encoding adenovirus (Ad) formulated in zinc oleate-based magnetic nanoparticles (MNP[_iNOSAd]) strongly suppressed growth of proliferating A10 and attenuated the stimulatory effect of a potent mitogen, platelet-derived growth factor (PDGF-BB), whereas EC functionalization with free _iNOSAd or MNP formulated with a different isoform of the enzyme, endothelial NOS, was associated with lower levels of NO synthesis and less pronounced antiproliferative activity toward co-cultured A10 cells. These results show feasibility of applying magnetically facilitated gene transfer to potentiate therapeutically relevant effects of EC for targeted cell therapy of restenosis. The direct contact co-culture methodology provides a sensitive and reliable tool with potential utility for a variety of biomedical applications.

The effects of rosuvastatin on lipid-lowering, inflammatory, antioxidant and fibrinolytics blood biomarkers are influenced by Val16Ala superoxide dismutase manganese-dependent gene polymorphism

Rosuvastatin is a cholesterol-lowering drug that also attenuates the inflammatory process and oxidative stress via the reduction of superoxide anion production. Superoxide anions are metabolized by manganese-dependent superoxide dismutase (MnSOD or SOD2) in the mitochondria. In humans, there is a gene polymorphism where a change of alanine (Ala) to valine (Val) occurs at the 16th amino acid (Ala16Val-SOD2). The VV genotype has been associated with the risk of developing several metabolic diseases, such as hypercholesterolemia. Thus, to further explore this phenomenon, this study investigated the influence of the Val16Ala-SOD2 polymorphism on the lipid profile and inflammatory and fibrinolytic biomarkers of 122 hypercholesterolemic patients undergoing the first pharmacological cholesterol-lowering therapy who were treated with 20 mg rosuvastatin for 120 days. The findings indicate that the VV patients who present a low-efficiency SOD2 enzyme exhibit an attenuated response to rosuvastatin compared with the A-allele patients. The effect of rosuvastatin on inflammatory and fibrinolytic biomarkers was also less intense in the VV patients. These results suggest some pharmacogenetic effects of Val16Ala-SOD2 in hypercholesterolemia treatment.

Long-term effect of PROLI/NO on cellular proliferation and phenotype after arterial injury

Vascular interventions are associated with high failure rates from restenosis secondary to negative remodeling and neointimal hyperplasia. Periadventitial delivery of nitric oxide (NO) inhibits neointimal hyperplasia, preserving lumen patency. With the development of new localized delivery vehicles, NO-based therapies remain a promising therapeutic avenue for the prevention of restenosis. While the time course of events during neointimal development has been well established, a full characterization of the impact of NO donors on the cells that comprise the arterial wall has not been performed. Thus, the aim of our study was to perform a detailed assessment of proliferation, cellularity, inflammation, and phenotypic cellular modulation in injured arteries treated with the short-lived NO donor, PROLI/NO. PROLI/NO provided durable inhibition of neointimal hyperplasia for 6 months after arterial injury. PROLI/NO inhibited proliferation and cellularity in the media and intima at all of the time points studied. However, PROLI/NO caused an increase in adventitial proliferation at 2 weeks, resulting in increased cellularity at 2 and 8 weeks compared to injury alone. PROLI/NO promoted local protein S-nitrosation and increased local tyrosine nitration, without measurable systemic effects. PROLI/NO predominantly inhibited contractile smooth muscle cells in the intima and media, and had little to no effect on vascular smooth muscle cells or myofibroblasts in the adventitia. Finally, PROLI/NO caused a delayed and decreased leukocyte infiltration response after injury. Our results show that a short-lived NO donor exerts durable effects on proliferation, phenotype modulation, and inflammation that result in long-term inhibition of neointimal hyperplasia.

Nitric oxide-eluting nanocomposite for cardiovascular implants

Cardiovascular implants must resist thrombosis and intimal hyperplasia, but they are prone to such patency limiting conditions during graft implantation and prior to endothelialisation. Nitric oxide (NO) released from the endothelium has a complex protective role in the cardiovascular system, and this study has addressed: (1) in situ NO release profiles from S-nitrosothiols ((S-Nitroso-N-acetylpenicillamine (SNAP) and (S-Nitrosoglutathione (GSNO)) incorporated into polyhedral oligomeric silsesquioxanepoly(carbonate-urea)urethane (POSS-PCU) coronary artery bypass grafts (CABG) in a physiological pulsatile flow, and (2) the determination of their interaction with endothelial progenitor cells (EPCs), smooth muscle cells, platelets, whole blood kinetics. It was found that 1, 2, and 3 wt% SNAP/GSNO incorporated into POSS-PCU-CABG successfully eluted NO, but optimal elution was evident with 2 %-SNAP-POSS-PCU. NO release determined under static conditions using the Griess assay, and in situ measurements under pulsatile flow using amperometric probe was found to differ, thus confirming the significance of monitoring NO-elution under haemodynamic conditions. 2 %-SNAP-POSS-PCU demonstrated anti-thrombogenic kinetics through thromboelastography measurements, while metabolic activity using Alamar Blue™ assay and scanning electron microscopy demonstrated greater adhesion of EPCs and reduced adhesion of platelets.

Endothelial NO and O₂·⁻ production rates differentially regulate oxidative, nitroxidative, and nitrosative stress in the microcirculation

Endothelial dysfunction causes an imbalance in endothelial NO and O₂·⁻ production rates and increased peroxynitrite formation. Peroxynitrite and its decomposition products cause multiple deleterious effects including tyrosine nitration of proteins, superoxide dismutase (SOD) inactivation, and tissue damage. Studies have shown that peroxynitrite formation during endothelial dysfunction is strongly dependent on the NO and O₂·⁻ production rates. Previous experimental and modeling studies examining the role of NO and O₂·⁻ production imbalance on peroxynitrite formation showed different results in biological and synthetic systems. However, there is a lack of quantitative information about the formation and biological relevance of peroxynitrite under oxidative, nitroxidative, and nitrosative stress conditions in the microcirculation. We developed a computational biotransport model to examine the role of endothelial NO and O₂·⁻ production on the complex biochemical NO and O₂·⁻ interactions in the microcirculation. We also modeled the effect of variability in SOD expression and activity during oxidative stress. The results showed that peroxynitrite concentration increased with increase in either O₂·⁻ to NO or NO to O₂·⁻ production rate ratio (QO₂·⁻/QNO or QNO/QO₂·⁻, respectively). The peroxynitrite concentrations were similar for both production rate ratios, indicating that peroxynitrite-related nitroxidative and nitrosative stresses may be similar in endothelial dysfunction or inducible NO synthase (iNOS)-induced NO production. The endothelial peroxynitrite concentration increased with increase in both QO₂·⁻/QNO and QNO/QO₂·⁻ ratios at SOD concentrations of 0.1-100 μM. The absence of SOD may not mitigate the extent of peroxynitrite-mediated toxicity, as we predicted an insignificant increase in peroxynitrite levels beyond QO₂·⁻/QNO and QNO/QO₂·⁻ ratios of 1. The results support the experimental observations of biological systems and show that peroxynitrite formation increases with increase in either NO or O₂·⁻ production, and excess NO production from iNOS or from NO donors during oxidative stress conditions does not reduce the extent of peroxynitrite mediated toxicity.

Local oxidative and nitrosative stress increases in the microcirculation during leukocytes-endothelial cell interactions

Leukocyte-endothelial cell interactions and leukocyte activation are important factors for vascular diseases including nephropathy, retinopathy and angiopathy. In addition, endothelial cell dysfunction is reported in vascular disease condition. Endothelial dysfunction is characterized by increased superoxide (O₂^•−) production from endothelium and reduction in NO bioavailability. Experimental studies have suggested a possible role for leukocyte-endothelial cell interaction in the vessel NO and peroxynitrite levels and their role in vascular disorders in the arterial side of microcirculation. However, anti-adhesion therapies for preventing leukocyte-endothelial cell interaction related vascular disorders showed limited success. The endothelial dysfunction related changes in vessel NO and peroxynitrite levels, leukocyte-endothelial cell interaction and leukocyte activation are not completely understood in vascular disorders. The objective of this study was to investigate the role of endothelial dysfunction extent, leukocyte-endothelial interaction, leukocyte activation and superoxide dismutase therapy on the transport and interactions of NO, O₂^•− and peroxynitrite in the microcirculation. We developed a biotransport model of NO, O₂^•− and peroxynitrite in the arteriolar microcirculation and incorporated leukocytes-endothelial cell interactions. The concentration profiles of NO, O₂^•− and peroxynitrite within blood vessel and leukocytes are presented at multiple levels of endothelial oxidative stress with leukocyte activation and increased superoxide dismutase accounted for in certain cases. The results showed that the maximum concentrations of NO decreased ∼0.6 fold, O₂^•− increased ∼27 fold and peroxynitrite increased ∼30 fold in the endothelial and smooth muscle region in severe oxidative stress condition as compared to that of normal physiologic conditions. The results show that the onset of endothelial oxidative stress can cause an increase in O₂^•− and peroxynitrite concentration in the lumen. The increased O₂^•− and peroxynitrite can cause leukocytes priming through peroxynitrite and leukocytes activation through secondary stimuli of O₂^•− in bloodstream without endothelial interaction. This finding supports that leukocyte rolling/adhesion and activation are independent events.

Collateral circulation: past and present

Following an arterial occlusion outward remodeling of pre-existent inter-connecting arterioles occurs by proliferation of vascular smooth muscle and endothelial cells. This is initiated by deformation of the endothelial cells through increased pulsatile fluid shear stress (FSS) caused by the steep pressure gradient between the high pre-occlusive and the very low post-occlusive pressure regions that are interconnected by collateral vessels. Shear stress leads to the activation and expression of all NOS isoforms and NO production, followed by endothelial VEGF secretion, which induces MCP-1 synthesis in endothelium and in the smooth muscle of the media. This leads to attraction and activation of monocytes and T-cells into the adventitial space (peripheral collateral vessels) or attachment of these cells to the endothelium (coronary collaterals). Mononuclear cells produce proteases and growth factors to digest the extra-cellular scaffold and allow motility and provide space for the new cells. They also produce NO from iNOS, which is essential for arteriogenesis. The bulk of new tissue production is carried by the smooth muscles of the media, which transform their phenotype from a contractile into a synthetic and proliferative one. Important roles are played by actin binding proteins like ABRA, cofilin, and thymosin beta 4 which determine actin polymerization and maturation. Integrins and connexins are markedly up-regulated. A key role in this concerted action which leads to a 2-to-20 fold increase in vascular diameter, depending on species size (mouse versus human) are the transcription factors AP-1, egr-1, carp, ets, by the Rho pathway and by the Mitogen Activated Kinases ERK-1 and -2. In spite of the enormous increase in tissue mass (up to 50-fold) the degree of functional restoration of blood flow capacity is incomplete and ends at 30% of maximal conductance (coronary) and 40% in the vascular periphery. The process of arteriogenesis can be drastically stimulated by increases in FSS (arterio-venous fistulas) and can be completely blocked by inhibition of NO production, by pharmacological blockade of VEGF-A and by the inhibition of the Rho-pathway. Pharmacological stimulation of arteriogenesis, important for the treatment of arterial occlusive diseases, seems feasible with NO donors.