Effects of PCSK9 Targeting: Alleviating Oxidation, Inflammation, and Atherosclerosis

Characterized as a chronic inflammatory disease of the large arteries, atherosclerosis is the primary cause of cardiovascular disease, the leading contributor of morbidity and mortality worldwide. Elevated plasma cholesterol levels and chronic inflammation within the arterial plaque are major mediators of plaque initiation, progression, and instability. In 2003, the protein PCSK9 (proprotein convertase subtilisin/kexin 9) was discovered to play a critical role in cholesterol regulation, thus becoming a key player in the mechanisms behind atherosclerotic plaque development. Emerging evidence suggests that PCSK9 could potentially have effects on atherosclerosis that are independent of cholesterol levels. The objective of this review was to discuss the role on PCSK9 in oxidation, inflammation, and atherosclerosis. This function activates proinflammatory cytokine production and affects oxidative modifications within atherosclerotic lesions, revealing its more significant role in atherosclerosis. Although a variety of evidence demonstrates that PCSK9 plays a role in atherosclerotic inflammation, the direct mechanism of involvement is still unknown, driving a gap in knowledge to such a predominant player in cardiovascular disease. Investigation of proteins structurally related to PCSK9 may interestingly be the link in unveiling the mechanistic role of this protein’s involvement in oxidation and inflammation. Importantly, the unique structure of PCSK9 bears structural homology to a one‐of‐a‐kind domain found in the metabolic protein resistin, which is responsible for many of the same inflammatory outcomes as PCSK9. Closing this gap in knowledge of PCSK9`s role in atherosclerotic oxidation and inflammation will provide fundamental information for understanding, preventing, and treating cardiovascular disease.

Oxidative Stress, Antioxidants and Hypertension

As a major cause of morbidity and mortality globally, hypertension remains a serious threat to global public health. Despite the availability of many antihypertensive medications, several hypertensive individuals are resistant to standard treatments, and are unable to control their blood pressure. Regulation of the renin-angiotensin-aldosterone system (RAAS) controlling blood pressure, activation of the immune system triggering inflammation and production of reactive oxygen species, leading to oxidative stress and redox-sensitive signaling, have been implicated in the pathogenesis of hypertension. Thus, besides standard antihypertensive medications, which lower arterial pressure, antioxidant medications were tested to improve antihypertensive treatment. We review and discuss the role of oxidative stress in the pathophysiology of hypertension and the potential use of antioxidants in the management of hypertension and its associated organ damage.

Cross-Talk of NADPH Oxidases and Inflammation in Obesity

Obesity is a major risk factor for cardiovascular and metabolic diseases. Multiple experimental and clinical studies have shown increased oxidative stress and inflammation linked to obesity. NADPH oxidases are major sources of reactive oxygen species in the cardiovascular system and in metabolically active cells and organs. An impaired balance due to the increased formation of reactive oxygen species and a reduced antioxidative capacity contributes to the pathophysiology of cardiovascular and metabolic diseases and is linked to inflammation as a major pathomechanism in cardiometabolic diseases. Non-alcoholic fatty liver disease is particularly characterized by increased oxidative stress and inflammation. In recent years, COVID-19 infections have also increased oxidative stress and inflammation in infected cells and tissues. Increasing evidence supports the idea of an increased risk for severe clinical complications of cardiometabolic diseases after COVID-19. In this review, we discuss the role of oxidative stress and inflammation in experimental models and clinical studies of obesity, cardiovascular diseases, COVID-19 infections and potential therapeutic strategies.

Regulation of endothelial function by cigarette smoke and next-generation tobacco and nicotine products

Cigarette smoking is the most important avoidable cardiovascular risk factor. It causes endothelial dysfunction and atherosclerosis and increases the risk of its severe clinical complications like coronary artery disease, myocardial infarction, stroke, and peripheral artery disease. Several next-generation tobacco and nicotine products have been developed to decrease some of the deleterious effects of regular tobacco smoking. This review article summarizes recent findings about the impact of cigarette smoking and next-generation tobacco and nicotine products on endothelial dysfunction. Both cigarette smoking and next-generation tobacco products lead to impaired endothelial function. Molecular mechanisms of endothelial dysfunction like oxidative stress, reduced nitric oxide availability, inflammation, increased monocyte adhesion, and cytotoxic effects of cigarette smoke and next-generation tobacco and nicotine products are highlighted. The potential impact of short- and long-term exposure to next-generation tobacco and nicotine products on the development of endothelial dysfunction and its clinical implications for cardiovascular diseases are discussed.

Reproducibility and research integrity: the role of scientists and institutions

Reproducibility and research integrity are essential tenets of every scientific study and discovery. They serve as proof that an established and documented work can be verified, repeated, and reproduced. New knowledge in the biomedical science is built on the shoulders of established and proven principles. Thus, scientists must be able to trust and build on the knowledge of their colleagues. Scientific innovation and research discoveries especially in the field of medicine has contributed to improving the lives of patients and increasing life expectancies. However, the growing concerns of failure to comply with good scientific principles has resulted in issues with research integrity and reproducibility. Poor reproducibility and integrity, therefore, may lead to ineffective interventions and applications. Here we comment on research reproducibility in basic medical and life sciences with regards to issues arising and outline the role of stakeholders such as research institutions and their employees in addressing this crisis.

Impact of exercise intensity on oxidative stress and selected metabolic markers in young adults in Ghana

Objective

This study aimed to evaluate the effect of different levels of exercise on markers of oxidative stress and selected metabolic parameters in Ghanaian young adults.

Results

Significant increases in a marker of oxidative stress malondialdehyde and antioxidants such as superoxide dismutase and uric acid were observed in the exercisers compared with the inactive group (p < 0.05). Total cholesterol and high density lipoprotein levels were significantly different (p < 0.05) between the two groups. Positive associations between exercise intensity, antioxidant concentration and malondialdehyde were observed within the exercise group for vigorous exercise with regards to uric acid, superoxide dismutase and malondialdehyde (r = 0.512, p = 0.004; r = 0.810, p = 0.001; r = 0.715, p = 0.001) respectively and moderate exercise vs malondialdehyde (r = 0.841, p = 0.001) compared to the inactive group. Exercise participants performed more vigorous exercise (p < 0.001), moderate exercise (p < 0.001) and more walking (p < 0.001) compared with the inactive group while the inactive group exhibited more sitting (p < 0.001). The study provides a first report on the risk associated with increase in oxidative stress and the importance of walking as a health promotion intervention among young Ghanaian adults.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3758-y) contains supplementary material, which is available to authorized users.

Chronic and moderate consumption of reduced-alcohol wine confers cardiac benefits in a rat model of pulmonary arterial hypertension

OBJECTIVES

In pulmonary arterial hypertension (PAH), right ventricular (RV) dysfunction develops via mechanisms involving oxidative stress. Moderate and chronic red wine (RW) consumption reduces oxidative stress and confers cardioprotection but its effect on PAH is unknown. We evaluated whether moderate and chronic consumption of reduced-alcohol RW (RARW) confers cardioprotection in a monocrotaline (MCT)-induced PAH rat model.

RESULTS

Rats were randomly grouped: control; MCT; RARW; MCT + RARW. Wine was diluted to mimic moderate intake for humans, and consumed from 7 days before, until 28 days after MCT-injection. Echocardiography measured pulmonary artery acceleration time (PAAT) and RV thickness. Conjugated dienes (CD), and thiobarbituric acid reactive substances (TBARS) concentrations were assessed. MCT induced RV thickness and decreased PAAT compared to controls [1.22 ± 0.09 mm vs 0.46 ± 0.02 mm and 14 ± 1 vs 23 ± 2 m/s, respectively (p < 0.001)]. Chronic RARW consumption limited MCT-induced RV hypertrophy and increased PAAT. CD and TBARS increased in MCT-treated animals compared to controls (672 ± 43 nmol/L vs 453 ± 35 nmol/L; p < 0.01 and 13 ± 2 µmol/L vs 4 ± 0.3 µmol/L; p < 0.01). RARW reduced MCT-induced CD (472 ± 27 nmol/L vs 672 ± 43 nmol/L; p < 0.01).

CONCLUSION

Chronic and moderate intake of RARW ameliorates MCT-induced PAH in rats, which may be partly attributable to reduction of lipid peroxidation.

The Vascular Function of Resistance Arteries Depends on NADPH Oxidase 4 and Is Exacerbated by Perivascular Adipose Tissue

The NADPH oxidase NOX4 that releases H2O2 can mediate vasoprotective mechanisms under pathophysiological conditions in conductive arteries. However, the role of NOX4 in resistance arteries and in perivascular adipose tissue is not well understood. We hypothesized that NOX4 is of functional importance in resistance arteries and perivascular adipose tissue under dyslipidemia conditions. We detected elevated NOX4 expression in murine and human vessels under dyslipidemia. Diminishing Nox4 under these conditions led to endothelial dysfunction in resistance arteries. The mesenteric arteries of Nox4-/-/Ldlr-/- mice revealed decreased eNos mRNA expression. Inhibition of eNOS in those vessels did not affect vascular function, while in Ldlr-/- mice endothelial function was significantly altered. Anticontractile properties of perivascular adipose tissue at resistance arteries were diminished in Nox4-/-/Ldlr-/- compared with Ldlr-/- mice. In addition, the presence of perivascular adipose tissue further worsened endothelial dysfunction in mesenteric arteries under dyslipidemia conditions. Perivascular adipose tissue from mesenteric arteries revealed a higher expression of markers of white adipocytes compared to markers of beige/brown adipocytes. Among those white adipocyte markers, leptin was significantly less expressed in perivascular adipose tissue from Nox4-/-/Ldlr-/- mice compared with Ldlr-/- mice. Furthermore, in human perivascular adipose tissue with a profound pattern of white adipocyte marker genes, we detected a correlation of NOX4 and LEP expression. In addition, incubating arterial vessels with leptin induced nitrite release, indicating increased eNOS activity. In humans, a higher expression of leptin in perivascular adipose tissue correlated with eNOS expression in the corresponding left internal mammary artery. In conclusion, vascular function of resistance arteries was dependent on Nox4-derived H2O2, especially under dyslipidemia conditions. Perivascular adipose tissue of the mesenteric arteries with white adipose tissue characteristics further aggravated endothelial function through reduced leptin-eNOS signaling.

NADPH oxidase 4 has a crucial impact on the microcirculation of hypercholesteremic LDL receptor deficient mice

Introduction

NADPH oxidase (NOX) 4-generated H2O2 has anti-atherosclerotic properties in conduit arteries like the aorta and carotids. However, the role of NOX4 on vascular function of small resistance arteries and blood pressure in a mouse model of familial hypercholesterolemia is unknown.

Purpose

We evaluated whether NOX4-generated H2O2 might play a role in perivascular adipose tissue of the thoracic aorta (tPVAT) and small resistance arteries on vascular function in a mouse model of familial hypercholesterolemia.

Methods

Aortic segments and mesenteric arteries from 26-week-old Ldlr−/− and Nox4−/− / Ldlr−/− mice were analysed by Mulvany myograph. In addition, vascular contraction and relaxation was analysed in the presence of L-NAME and catalase. Analysis of mRNA expression was performed in murine and human tissue by quantitative real-time PCR. Blood pressure was detected by tail cuff method in conscious, trained mice.

Results

Loss of NOX4 led to severe endothelial dysfunction in mesenteric arteries of Ldlr−/− mice. Blocking of NO synthases with L-NAME led to decreased endothelial relaxation in Ldlr−/− mice at the level of Nox4−/− / Ldlr−/− mice. However, incubation with L-NAME did not worsen the established endothelial dysfunction of the mesenteric arteries from Nox4−/− / Ldlr−/− mice. These results are strikingly different from the aorta, where inhibition of NO synthases led to a similarly impaired endothelial relaxation in both mouse strains. We detected a similar eNOS expression in the aorta of Ldlr−/− and Nox4−/− / Ldlr−/−, but a reduced eNOS expression in the mesenteric arteries of Nox4−/− / Ldlr−/− mice. H2O2 can induce eNOS expression. Therefore, we analysed the vascular function after catalase incubation and again found a significant reduction of endothelial function in the mesenteric arteries of Ldlr−/− mice. Finally, we analysed blood pressure of these mice and did not observe differences in systolic blood pressure, despite significant differences in endothelial function of resistant arteries.

Conclusion

NOX4 protects against severe endothelial dysfunction in the mesenteric artery in a model of hypercholesterolemia.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Ghanaian-German postgraduate training scholarship program (DAAD)

NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia-Complementing Prostacyclin

Aim: The primary endothelial NADPH oxidase isoform 4 (NOX4) is notably induced during hypoxia, with emerging evidence suggesting its vasoprotective role through H2O2 production. Therefore, we aimed to elucidate NOX4's significance in endothelial function under hypoxia. Methods: Human vessels, in addition to murine vessels from Nox4-/- mice, were explored. On a functional level, Mulvany myograph experiments were performed. To obtain mechanistical insights, human endothelial cells were cultured under hypoxia with inhibitors of hypoxia-inducible factors. Additionally, endothelial cells were cultured under combined hypoxia and laminar shear stress conditions. Results: In human occluded vessels, NOX4 expression strongly correlated with prostaglandin I2 synthase (PTGIS). Hypoxia significantly elevated NOX4 and PTGIS expression and activity in human endothelial cells. Inhibition of prolyl hydroxylase domain (PHD) enzymes, which stabilize hypoxia-inducible factors (HIFs), increased NOX4 and PTGIS expression even under normoxic conditions. NOX4 mRNA expression was reduced by HIF1a inhibition, while PTGIS mRNA expression was only affected by the inhibition of HIF2a under hypoxia. Endothelial function assessments revealed hypoxia-induced endothelial dysfunction in mesenteric arteries from wild-type mice. Mesenteric arteries from Nox4-/- mice exhibited an altered endothelial function under hypoxia, most prominent in the presence of cyclooxygenase inhibitor diclofenac to exclude the impact of prostacyclin. Restored protective laminar shear stress, as it might occur after thrombolysis, angioplasty, or stenting, attenuated the hypoxic response in endothelial cells, reducing HIF1a expression and its target NOX4 while enhancing eNOS expression. Conclusions: Hypoxia strongly induces NOX4 and PTGIS, with a close correlation between both factors in occluded, hypoxic human vessels. This relationship ensured endothelium-dependent vasodilation under hypoxic conditions. Protective laminar blood flow restores eNOS expression and mitigates the hypoxic response on NOX4 and PTGIS.

Plant homeodomain-finger protein 5A: A key player in cancer progression

PHF5A is a member of the zinc-finger proteins. To advance knowledge on their role in carcinogenesis, data from experimental studies, animal models and clinical studies in different tumorigenesis have been reviewed. Furthermore, PHF5A as an oncogenic function, is frequently high expressed in tumor cells and a potential prognostic marker for different cancers. PHF5A is implicated in the regulation of cancer cell proliferation, invasion, migration and metastasis. Knockdown of PHF5A prevented the invasion and metastasis of tumor cells. Here, the role of PHF5A in different cancers and their possible mechanism in relation to recent literature is reviewed and discussed. There is an open promising perspective to their therapeutic management for different cancer types.

Interleukin-4 and its receptor alpha in paediatric uncomplicated malaria patients from a Ghanaian case-control study

OBJECTIVES

This study investigated gene polymorphisms in the interleukin-4 (IL-4) and its receptor alpha (IL-4Rα) gene regions in human hosts with uncomplicated malaria.

DATA DESCRIPTION

Blood samples were obtained from a case-control study conducted at the Sogakope district hospital in the Volta region of Ghana. Thick blood films were made and used to detect the presence and levels of parasitaemia in the patient samples. Genotyping of IL-4 (150 C/T) and the IL-4Rα (Pro-478-Ser) polymorphisms in the promoter regions and receptor gene was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) after DNA extraction. The data are useful in determining genetic polymorphisms (allele and genotypic frequencies) of IL-4 and its alpha receptor. In addition, they are useful when comparing levels of parasite density and haematological parameters between genotypic variants of IL-4 and IL-4Rα. These data contribute to our understanding of the genetic basis of malaria susceptibility, particularly in the population of the Volta region of Ghana.

Impact of blood perilipin A levels on obesity and metabolic health

OBJECTIVE

Perilipin A is a common protein that coats lipid surfaces preventing them from being exposed to oxidative damage. Researchers have found little consistency in the relationship between perilipin A levels in the blood and body fat. This study was a cross-sectional observational that looked at circulating perilipin A levels and how they relate to metabolic health.

RESULTS

The participants in this study were 86 individuals with a mean age of 45.5 ± 1.2 years. Multiple clinical and metabolic indicators (age, weight, BMI, total body fat mass, triglyceride, and HOMA-IR) were shown to be inversely associated with perilipin A levels (rho = - 0.32, - 0.37, - 0.40, - 0.45, - 0.33 and - 0.29; p < 0.05 respectively). Obese persons were almost six times more likely than non-obese individuals to have lower perilipin A levels (odds ratio = 6.22, CI = 2.35-11.50, p < 0.001). Our findings underscore the important role of perilipin A proteins in metabolic health.