Oxidative Stress in Neutrophils: Implications for Diabetic Cardiovascular Complications

Redox regulation of platelet function and thrombosis

Platelets are well-known players in several cardiovascular diseases such as atherosclerosis and venous thrombosis. There is increasing evidence demonstrating that reactive oxygen species (ROS) are generated within activated platelets. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is a major source of ROS generation in platelets. Ligand binding to platelet receptor glycoprotein (GP) VI stimulates intracellular ROS generation consisting of a spleen tyrosine kinase-independent production involving NOX activation and a following spleen tyrosine kinase-dependent generation. In addition to GPVI, stimulation of platelet thrombin receptors (protease-activated receptors [PARs]) can also trigger NOX-derived ROS production. Our recent study found that mitochondria-derived ROS production can be induced by engagement of thrombin receptors but not by GPVI, indicating that mitochondria are another source of PAR-dependent ROS generation apart from NOX. However, mitochondria are not involved in GPVI-dependent ROS generation. Once generated, the intracellular ROS are also involved in modulating platelet function and thrombus formation; therefore, the site-specific targeting of ROS production or clearance of excess ROS within platelets is a potential intervention and treatment option for thrombotic events. In this review, we will summarize the signaling pathways involving regulation of platelet ROS production and their role in platelet function and thrombosis, with a focus on GPVI- and PAR-dependent platelet responses.

An update on chronic complications of diabetes mellitus: from molecular mechanisms to therapeutic strategies with a focus on metabolic memory

Diabetes mellitus, a chronic metabolic disease, often leads to numerous chronic complications, significantly contributing to global morbidity and mortality rates. High glucose levels trigger epigenetic modifications linked to pathophysiological processes like inflammation, immunity, oxidative stress, mitochondrial dysfunction, senescence and various kinds of cell death. Despite glycemic control, transient hyperglycemia can persistently harm organs, tissues, and cells, a latent effect termed "metabolic memory" that contributes to chronic diabetic complications. Understanding metabolic memory's mechanisms could offer a new approach to mitigating these complications. However, key molecules and networks underlying metabolic memory remain incompletely understood. This review traces the history of metabolic memory research, highlights its key features, discusses recent molecules involved in its mechanisms, and summarizes confirmed and potential therapeutic compounds. Additionally, we outline in vitro and in vivo models of metabolic memory. We hope this work will inform future research on metabolic memory's regulatory mechanisms and facilitate the development of effective therapeutic compounds to prevent diabetic complications.

Assessing the combined impact of fatty liver-induced TGF-β1 and LPS-activated macrophages in fibrosis through a novel 3D serial section methodology

Non-alcoholic steatohepatitis (NASH), caused by fat buildup, can lead to liver inflammation and damage. Elucidation of the spatial distribution of fibrotic tissue in the fatty liver in NASH can be immensely useful to understand its pathogenesis. Thus, we developed a novel serial section-3D (SS3D) technique that combines high-resolution image acquisition with 3D construction software, which enabled highly detailed analysis of the mouse liver and extraction and quantification of stained tissues. Moreover, we studied the underexplored mechanism of fibrosis progression in the fatty liver in NASH by subjecting the mice to a high-fat diet (HFD), followed by lipopolysaccharide (LPS) administration. The HFD/LPS (+) group showed extensive fibrosis compared with control; additionally, the area of these fibrotic regions in the HFD/LPS (+) group was almost double that of control using our SS3D technique. LPS administration led to an increase in Tnfα and Il1β mRNA expression and the number of macrophages in the liver. On the other hand, transforming growth factor-β1 (Tgfβ1) mRNA increased in HFD group compared to that of control group without LPS-administration. In addition, COL1A1 levels increased in hepatic stellate cell (HSC)-like XL-2 cells when treated with recombinant TGF-β1, which attenuated with recombinant latency-associated protein (rLAP). This attenuation was rescued with LPS-activated macrophages. Therefore, we demonstrated that fatty liver produced "latent-form" of TGF-β1, which activated by macrophages via inflammatory cytokines such as TNFα and IL1β, resulting in activation of HSCs leading to the production of COL1A1. Moreover, we established the effectiveness of our SS3D technique in creating 3D images of fibrotic tissue, which can be used to study other diseases as well.

Defining the activity of pro-reparative extracellular vesicles in wound healing based on miRNA payloads and cell type-specific lineage mapping

Small extracellular vesicles (EVs) are released by cells and deliver biologically active payloads to coordinate the response of multiple cell types in cutaneous wound healing. Here we used a cutaneous injury model as a donor of pro-reparative EVs to treat recipient diabetic obese mice, a model of impaired wound healing. We established a functional screen for microRNAs (miRNAs) that increased the pro-reparative activity of EVs and identified a down-regulation of miR-425-5p in EVs in vivo and in vitro associated with the regulation of adiponectin. We tested a cell type-specific reporter of a tetraspanin CD9 fusion with GFP to lineage map the release of EVs from macrophages in the wound bed, based on the expression of miR-425-5p in macrophage-derived EVs and the abundance of macrophages in EV donor sites. Analysis of different promoters demonstrated that EV release under the control of a macrophage-specific promoter was most abundant and that these EVs were internalized by dermal fibroblasts. These findings suggested that pro-reparative EVs deliver miRNAs, such as miR-425-5p, that stimulate the expression of adiponectin that has insulin-sensitizing properties. We propose that EVs promote intercellular signaling between cell layers in the skin to resolve inflammation, induce proliferation of basal keratinocytes, and accelerate wound closure.

Elevated neutrophil-lymphocyte ratio is associated with high rates of ICU mortality, length of stay, and invasive mechanical ventilation in critically ill patients with COVID-19 : NRL and severe COVID-19

Neutrophil and lymphocyte ratio (NLR) has emerged as a complementary marker in intensive care. This study aimed to associate high NLR values with mortality as the primary outcome, and length of stay and need for invasive mechanical ventilation as secondary outcomes, in critically ill patients with COVID-19. A cross-sectional study encompassing 189 critically ill patients with COVID-19 was performed. The receiver operating characteristic curve was used to identify the best NLR cutoff value for ICU mortality (≥ 10.6). An NLR ≥ 10.6, compared with an NLR < 10.6, was associated with higher odds of ICU mortality (odds ratio [OR], 2.77; 95% confidence interval [CI], 1.24-6.18), ICU length of stay ≥ 14 days (OR, 3.56; 95% CI, 1.01-12.5), and need for invasive mechanical ventilation (OR, 5.39; 95% CI, 1.96-14.81) in the fully adjusted model (age, sex, kidney dysfunction, diabetes, obesity, hypertension, deep vein thrombosis, antibiotics, anticoagulants, antivirals, corticoids, neuromuscular blockers, and vasoactive drugs). In conclusion, elevated NLR is associated with high rates of mortality, length of stay, and need for invasive mechanical ventilation in critically ill patients with COVID-19.

The association between a novel inflammatory biomarker, systemic inflammatory response index and the risk of diabetic cardiovascular complications

BACKGROUND AND AIM

Systemic inflammatory response index (SIRI) is a novel inflammatory biomarker. The relationship between SIRI and the risk of diabetic cardiovascular complications is still unclear. The purpose of our study was to address the correlation between SIRI and the risk of cardiovascular diseases (CVD) in diabetes mellitus (DM) patients.

METHODS AND RESULTS

A total of 8759 individuals were selected from the National Health and Nutrition Examination Survey (NHANES) (2015-2020) in our study. Comparing with control (n = 6446) and pre-DM (n = 350) individuals, the DM patients (n = 1963) show the higher SIRI level (all P < 0.001) and prevalence of CVD (all P < 0.001). Furthermore, in a fully adjusted model, we observed the increase of tertiles of SIRI was a risk factor for CVD in DM patients (the middle tertile: 1.80, 95% CI: 1.13-3.13; the highest tertile: 1.91, 95% CI: 1.03-3.22; all P < 0.05), while the relationship between hypersensitive CRP (hs-CRP) and the risk of diabetic cardiovascular complications was not observed (all P > 0.05). Furthermore, the SIRI tertiles-CVD association was significant strongly in patients with high body mass index (BMI; >24 kg/m²) than in those with a low BMI (≤24 kg/m², P for interaction = 0.045). Using restricted cubic splines, we observed a dose-response relation between lg SIRI and the risk of CVD in DM patients.

CONCLUSIONS

The elevated SIRI was independently associated with the increased risk of CVD in the DM population with a high BMI (>24 kg/m²), and its clinical value is greater than hs-CRP.

Cardiovascular complications of diabetes: role of non-coding RNAs in the crosstalk between immune and cardiovascular systems

Diabetes mellitus, a group of metabolic disorders characterized by high levels of blood glucose caused by insulin defect or impairment, is a major risk factor for cardiovascular diseases and related mortality. Patients with diabetes experience a state of chronic or intermittent hyperglycemia resulting in damage to the vasculature, leading to micro- and macro-vascular diseases. These conditions are associated with low-grade chronic inflammation and accelerated atherosclerosis. Several classes of leukocytes have been implicated in diabetic cardiovascular impairment. Although the molecular pathways through which diabetes elicits an inflammatory response have attracted significant attention, how they contribute to altering cardiovascular homeostasis is still incompletely understood. In this respect, non-coding RNAs (ncRNAs) are a still largely under-investigated class of transcripts that may play a fundamental role. This review article gathers the current knowledge on the function of ncRNAs in the crosstalk between immune and cardiovascular cells in the context of diabetic complications, highlighting the influence of biological sex in such mechanisms and exploring the potential role of ncRNAs as biomarkers and targets for treatments. The discussion closes by offering an overview of the ncRNAs involved in the increased cardiovascular risk suffered by patients with diabetes facing Sars-CoV-2 infection.

NETs-Induced Thrombosis Impacts on Cardiovascular and Chronic Kidney Disease

Arterial and venous thrombosis constitute a major source of morbidity and mortality worldwide. Association between thrombotic complications and cardiovascular and other chronic inflammatory diseases are well described. Inflammation and subsequent initiation of thrombotic events, termed immunothrombosis, also receive growing attention but are still incompletely understood. Nevertheless, the clinical relevance of aberrant immunothrombosis, referred to as thromboinflammation, is evident by an increased risk of thrombosis and cardiovascular events in patients with inflammatory or infectious diseases. Proinflammatory mediators released from platelets, complement activation, and the formation of NETs (neutrophil extracellular traps) initiate and foster immunothrombosis. In this review, we highlight and discuss prominent and emerging interrelationships and functions between NETs and other mediators in immunothrombosis in cardiovascular disease. Also, with patients with chronic kidney disease suffering from increased cardiovascular and thrombotic risk, we summarize current knowledge on neutrophil phenotype, function, and NET formation in chronic kidney disease. In addition, we elaborate on therapeutic targeting of NETs-induced immunothrombosis. A better understanding of the functional relevance of antithrombotic mediators which do not increase bleeding risk may provide opportunities for successful therapeutic interventions to reduce thrombotic risk beyond current treatment options.

Modified Signaling of Membrane Formyl Peptide Receptors in NADPH-Oxidase Regulation in Obesity-Resistant Mice

The signaling of membrane receptors is modified in obesity characterized by low-grade inflammation. The obesity-resistant state of organisms is poorly understood. We analyzed the generation of reactive oxygen species (ROS) initiated though membrane formyl peptide receptors (Fpr1, Fpr2) in bone-marrow granulocytes of obesity-resistant mice (ORM). A chemiluminescence assay was used to assess NADPH-oxidase-related intensity of ROS generation. ORM were chosen from animals that received high-fat diets and had metric body parameters as controls (standard diet). High spontaneous ROS production was observed in ORM cells. The EC50 for responses to bacterial or mitochondrial peptide N-formyl-MLF was higher in ORM with and without inflammation vs. the same control groups, indicating an insignificant role of high-affinity Fpr1. Increased responses to synthetic peptide WKYMVM (Fpr2 agonist) were observed in controls with acute inflammation, but they were similar in other groups. Fpr2 was possibly partially inactivated in ORM owing to the inflammatory state. Weakened Fpr1 and Fpr2 signaling via MAPKs was revealed in ORM using specific inhibitors for p38, ERK1/2, and JNK. P38 signaling via Fpr2 was lower in ORM with inflammation. Thus, a high-fat diet modified FPRs' role and suppressed MAPK signaling in NADPH-oxidase regulation in ORM. This result can be useful to understand the immunological features of obesity resistance.

Excessive neutrophil extracellular trap formation induced by Porphyromonas gingivalis lipopolysaccharide exacerbates inflammatory responses in high glucose microenvironment

Introduction

Neutrophil extracellular trap (NET) is a novel defense strategy of neutrophils and found to be induced by Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) or high glucose. The aim of this study was to investigate the roles and mechanisms of NET formation in high glucose inflammatory microenvironment.

Methods

NETs induced by 1 μg/ml P. gingivalis LPS and/or 25 mM glucose were visualized using a fluorescence microscopy and the levels of extracellular DNA were determined by a microplate reader. The bactericidal efficiency of NETs was assessed by quantifying the survival P. gingivalis in neutrophils. The levels of NLRP3 and IL-1β in THP-1 derived-macrophages, and the expressions of p-PKC βII, p-MEK1/2, p-ERK1/2, ORAI1 and ORAI2 in neutrophils were detected by Western blot. Moreover, levels of intracellular Ca2+ and reactive oxygen species (ROS) in neutrophils were explored by flow cytometry.

Results

P. gingivalis LPS enhanced the formation of NETs and increased the levels of extracellular DNA in high glucose microenvironment (p < 0.05). Compared with normal glucose inflammatory microenvironment, quantities of extra- and intracellular viable P. gingivalis in neutrophils exposed to NETs induced in high glucose inflammatory one were increased (p < 0.05) and the expressions of NLRP3 and IL-1β were dramatically increased in macrophages co-cultured with NETs from high glucose inflammatory microenvironment (p < 0.05). In addition, levels of ROS, intracellular Ca²⁺, p-PKC βII, p-MEK1/2, p-ERK1/2, ORAI1 and ORAI2 were increased in neutrophils stimulated with both high glucose and P. gingivalis LPS compared with the single stimulus groups (p < 0.05).

Discussion

In high glucose inflammatory microenvironment, formation of NETs was enhanced via oxidative stress, which failed to reverse the decreased bactericidal capacity in high glucose microenvironment, and instead aggravated the subsequent inflammatory responses.

Lipid Peroxidation Linking Diabetes and Cancer: The Importance of 4-Hydroxynonenal

Significance: It is commonly believed that diabetes mellitus may be associated with cancer. Hence, diabetic patients are at higher risk for hepatocellular carcinoma, pancreatic cancer, colorectal cancer, and breast cancer, but the mechanisms that may link these two severe diseases are not well understood. Recent Advances: A number of factors have been suggested to promote tumorigenesis in diabetic patients, including insulin resistance, hyperglycemia, dyslipidemia, inflammation, and elevated insulin-like growth factor-1 (IGF-1), which may also promote pro-oxidants, and thereby alter redox homeostasis. The consequent oxidative stress associated with lipid peroxidation appears to be a possible pathogenic link between cancer and diabetes. Critical Issues: Having summarized the above aspects of diabetes and cancer pathology, we propose that the major bioactive product of oxidative degradation of polyunsaturated fatty acids (PUFAs), the reactive aldehyde 4-hydroxynonenal (4-HNE), which is also considered a second messenger of free radicals, may be the key pathogenic factor linking diabetes and cancer. Future Directions: Because the bioactivities of 4-HNE are cell-type and concentration-dependent, are often associated with inflammation, and are involved in signaling processes that regulate antioxidant activities, proliferation, differentiation, and apoptosis, we believe that further research in this direction could reveal options for better control of diabetes and cancer. Controlling the production of 4-HNE to avoid its cytotoxicity to normal but not cancer cells while preventing its diabetogenic activities could be an important aspect of modern integrative biomedicine. Antioxid. Redox Signal. 37, 1222-1233.

The effect of EMPAgliflozin on markers of inflammation in patients with concomitant type 2 diabetes mellitus and Coronary ARtery Disease: the EMPA-CARD randomized controlled trial

Systemic inflammation and oxidative burden in patients with type 2 diabetes mellitus (T2DM) causes deleterious cardiovascular outcomes. We sought to investigate the clinical antioxidative and anti-inflammatory effects of empagliflozin. Platelet function, oxidant and antioxidant biomarkers and pro-inflammatory agents at baseline and at 26 weeks were measured. A total of 95 patients (41.05% male, mean age 62.85 ± 7.91 years, mean HbA_1c 7.89 ± 0.96%) with concomitant T2DM and coronary artery disease (CAD) were randomized (1:1) to receive empagliflozin (10 mg/daily) or placebo. Patients treated with empagliflozin had lower levels of interleukin 6 (IL-6) (adjusted difference (adiff): - 1.06 pg/mL, 95% CI - 1.80; - 0.32, P = 0.006), interleukin 1β (IL-1β) and high-sensitive C-reactive protein (Hs-CRP) (adiff: - 4.58 pg/mL and - 2.86 mg/L; P = 0.32 and 0.003, respectively) compared to placebo. There were elevations in super oxidase dismutase (SOD) activity, glutathione (GSHr), and total antioxidant capacity (TAC) with empagliflozin (adiff: 3.7 U/mL, 0.57 muM, and 124.08 mmol/L, 95% CI 1.36; 6.05, 0.19; 0.95, and 47.98; 200.18, P = 0.002, 0.004, and 0.002, respectively). While reactive oxygen species (ROS) improved significantly (adiff: - 342.51, 95% CI - 474.23; - 210.79, P < 0.001), the changes in catalase activity (CAT), malondialdehyde (MDA), or protein carbonyl groups (PCG) were not significant. Moreover, the P-selectin antigen expression on platelet surface was significantly reduced (adiff: - 8.81, 95% CI - 14.87; - 2.75, P = 0.005). Markers of glycemic status (fasting blood glucose, HbA_1c, and HOMA-IR (homeostatic model assessment for insulin resistance) significantly improved (P < 0.001). Among patients with T2DM and CAD, 6-month treatment with empagliflozin can mitigate inflammation, platelet activity and oxidative stress and is associated with clinical cardiovascular benefits.Trial Registration Iranian Registry of Clinical Trials. www.IRCT.ir , Identifier: IRCT20190412043247N2. Registration Date: 6/13/2020. Registration timing: prospective.

Skin Microhemodynamics and Mechanisms of Its Regulation in Type 2 Diabetes Mellitus

The review presents modern ideas about peripheral microhemodynamics, approaches to the ana-lysis of skin blood flow oscillations and their diagnostic significance. Disorders of skin microhemodynamics in type 2 diabetes mellitus (DM) and the possibility of their interpretation from the standpoint of external and internal interactions between systems of skin blood flow regulation, based on a comparison of couplings in normal and pathological conditions, including models of pathologies on animals, are considered. The factors and mechanisms of vasomotor regulation, among them receptors and signaling events in endothelial and smooth muscle cells considered as models of microvessels are discussed. Attention was drawn to the disturbance of Ca2+-dependent regulation of coupling between vascular cells and NO-dependent regulation of vasodilation in diabetes mellitus. The main mechanisms of insulin resistance in type 2 DM are considered to be a defect in the number of insulin receptors and impaired signal transduction from the receptor to phosphatidylinositol-3-kinase and downstream targets. Reactive oxygen species plays an important role in vascular dysfunction in hyperglycemia. It is assumed that the considered molecular and cellular mechanisms of microhemodynamics regulation are involved in the formation of skin blood flow oscillations. Parameters of skin blood microcirculation can be used as diagnostic and prognostic markers for assessing the state of the body.

A dual Keap1 and p47phox inhibitor Ginsenoside Rb1 ameliorates high glucose/ox-LDL-induced endothelial cell injury and atherosclerosis

Oxidative stress is a vital contributor to the development and progression of diabetes-accelerated atherosclerosis. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a well-known molecule that participates in cellular defense against oxidative stress. Utilizing luciferase reporter assay from 379 natural products, we reported here that Ginsenoside Rb1 played a dual role in inhibiting Kelch-like ECH-associated protein 1 (Keap1) and p47^phox luciferase reporter activities. In endothelial cells (ECs), Rb1 pretreatment enhanced cell viability, reduced oxidative stress, inflammation, endothelial-mesenchymal transition (EndMT), and apoptosis, as well as ameliorated mitochondrial quality following oxidized low-density lipoprotein (ox-LDL) plus high glucose (HG) challenge. Rb1 directly bound to Keap1 and promoted its ubiquitination and proteasomal degradation dependent on lysine residues (K108, K323, and K551) by recruiting the E3 ligase synovial apoptosis inhibitor 1 (SYVN1), leading to Nrf2 dissociation from Keap1, Nrf2 nuclear translocation, Nrf2/PGC-1α complex formation. We further identified that Rb1 could bind to p47^phox and reduce its phosphorylation and membrane translocation, thereby disrupting the assembly of the NOX2 complex. Importantly, Rb1-mediated preservation of cytoplasmic p47^phox stabilized and contributed to Nrf2 activation. Additionally, we revealed that Rb1 reduced aortic atherosclerotic plaque formation along with reductions in oxidative stress and inflammatory response in streptozotocin (STZ)-induced ApoE^-/- mice, but not in ApoE^-/- mice with deficiency of Nrf2 and PGC-1α. Collectively, we demonstrated that Rb1, which directly targeted Keap1 and p47^phox in ECs, may be an attractive candidate for the treatment of atherosclerosis in diabetes.

Hematopoietic progenitor cell liabilities and alarmins S100A8/A9-related inflammaging associate with frailty and predict poor cardiovascular outcomes in older adults

Frailty affects the physical, cognitive, and social domains exposing older adults to an increased risk of cardiovascular disease and death. The mechanisms linking frailty and cardiovascular outcomes are mostly unknown. Here, we studied the association of abundance (flow cytometry) and gene expression profile (RNAseq) of stem/progenitor cells (HSPCs) and molecular markers of inflammaging (ELISA) with the cardiorespiratory phenotype and prospective adverse events of individuals classified according to levels of frailty. Two cohorts of older adults were enrolled in the study. In a cohort of pre-frail 35 individuals (average age: 75 years), a physical frailty score above the median identified subjects with initial alterations in cardiorespiratory function. RNA sequencing revealed S100A8/A9 upregulation in HSPCs from the bone marrow (>10-fold) and peripheral blood (>200-fold) of individuals with greater physical frailty. Moreover higher frailty was associated with increased alarmins S100A8/A9 and inflammatory cytokines in peripheral blood. We then studied a cohort of 104 more frail individuals (average age: 81 years) with multidomain health deficits. Reduced levels of circulating HSPCs and increased S100A8/A9 concentrations were independently associated with the frailty index. Remarkably, low HSPCs and high S100A8/A9 simultaneously predicted major adverse cardiovascular events at 1-year follow-up after adjustment for age and frailty index. In conclusion, inflammaging characterized by alarmin and pro-inflammatory cytokines in pre-frail individuals is mirrored by the pauperization of HSPCs in frail older people with comorbidities. S100A8/A9 is upregulated within HSPCs, identifying a phenotype that associates with poor cardiovascular outcomes.

Association of Admission Blood Glucose Level with All-Cause Mortality According to Age in Patients with Community Acquired Pneumonia

Objective

To assess the impact of blood glucose levels on the prognosis of patients with community-acquired pneumonia (CAP) who were elderly or middle-aged.

Methods

From January 1, 2018, to December 31, 2020, patients with CAP (≥45 years) were retrospectively enrolled in this observational study. They were stratified by age (45-64 or ≥65 years) and blood glucose level (≥11.1 or <11.1 mmol/l). The effect of admission blood glucose on 28-day mortality was assessed with the Cox proportional hazards model, adjusted for demographic factors and comorbidity.

Results

Among 1656 patients with CAP, increased blood glucose (HR=2.08, 95% CI: 1.38-3.49; P<0.01) and advanced age (HR=2.76, 95% CI: 1.65-3.77; P<0.01) were significantly associated with a higher risk of 28-day mortality, after controlling for potential confounding factors. The strength of the association of blood glucose level with 28-day mortality decreased with age (P=0.01 for the interaction) as the adjusted HRs for death were 4.48 (95% CI: 1.40-13.65; P<0.01) for middle-age patients 45-64 years and 1.52 (95% CI: 1.09-2.17; P=0.05) for elderly patients ≥65 years.

Conclusion

The association of blood glucose level upon admission for CAP with all-cause mortality was stronger at younger ages.