Neutrophil extracellular traps: The core player in vascular complications of diabetes mellitus

NET-Related Gene as Potential Diagnostic Biomarkers for Diabetic Tubulointerstitial Injury

Background: Tubulointerstitial injury plays a pivotal role in the progression of diabetic kidney disease (DKD), yet the link between neutrophil extracellular traps (NETs) and diabetic tubulointerstitial injury is still unclear. Methods: We analyzed microarray data (GSE30122) from the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) associated with DKD's tubulointerstitial injury. Functional and pathway enrichment analyses were conducted to elucidate the involved biological processes (BP) and pathways. Weighted gene coexpression network analysis (WGCNA) identified modules associated with DKD. LASSO regression and random forest selected NET-related characteristic genes (NRGs) related to DKD tubulointerstitial injury. Results: Eight hundred ninety-eight DEGs were identified from the GSE30122 dataset. A significant module associated with diabetic tubulointerstitial injury overlapped with 15 NRGs. The hub genes, CASP1 and LYZ, were identified as potential biomarkers. Functional enrichment linked these genes with immune cell trafficking, metabolic alterations, and inflammatory responses. NRGs negatively correlated with glomerular filtration rate (GFR) in the Neph v5 database. Immunohistochemistry (IHC) validated increased NRGs in DKD tubulointerstitial injury. Conclusion: Our findings suggest that the CASP1 and LYZ genes may serve as potential diagnostic biomarkers for diabetic tubulointerstitial injury. Furthermore, NRGs involved in diabetic tubulointerstitial injury could emerge as prospective targets for the diagnosis and treatment of DKD.

The Standard-Dose Heparin-Warfarin Remedy Partially Resolves Thrombi in the Right Superior Pulmonary Vein and Left Atrium and Ameliorates Type 2 Diabetes Mellitus

Pulmonary vein thrombosis is common and underdiagnosed. Previously, we reported several cases of pulmonary vein thrombi (PVTs) using cardiac computed tomography (CT) and transesophageal echocardiography (TEE). We reported that warfarin and direct oral anticoagulants (DOACs) partially resolved PVTs; however, it is difficult to resolve all PVTs completely. Therefore, we evaluated the effects of standard-dose heparin-warfarin remedy on PVTs and left atrium (LA) thrombi using TEE and cardiac CT. A 64-year-old male with type 2 diabetes mellitus (T2DM) and hypertension was assessed for thrombi in the LA and pulmonary veins using TEE and 80-slice multidetector computed tomography (80-MDCT). After one month of standard-dose heparin-warfarin remedy, the patient's right superior pulmonary vein (RSPV) thrombi and expanded LA thrombi from the RSPV thrombi had partially resolved. The RSPV thrombi and the expanded LA thrombi from the RSPV thrombi were detected using cardiac CT and TEE; however, they were depicted as black areas on TEE. They periodically moved inward with the patient's heartbeats. Additionally, the standard-dose heparin-warfarin remedy ameliorated the patient's T2DM, and the remedy effect could be maintained for five months to some extent by administering a standard dose of warfarin. The standard-dose heparin-warfarin remedy can ameliorate not only T2DM but also diabetic complications such as diabetic nephropathy and gestational diabetes mellitus.

Changes in selected hematological parameters in patients with type 1 and type 2 diabetes: a systematic review and meta-analysis

Background

Diabetes mellitus is a chronic metabolic disorder that causes hyperglycemia and various life-threatening health problems. Although hematological parameters play a significant role in the progression and pathogenesis of diabetes, many studies have explored contradictory findings. Therefore, this evidence-based study aimed to determine the pooled mean difference of white blood cell and red blood cell parameters in diabetic patients in order to investigate hematological dysfunctions in type 1 and type 2 diabetes mellitus.

Methods

Articles were extensively searched in bibliographic databases (PubMed, Cochrane library, Scopus, Web of Science, PsycINFO, Embase, online archives and university repositories) using appropriate entry terms. For studies meeting the eligibility criteria, the first author's name, year of publication, study design and area, type of diabetes mellitus, sample size, and mean and standard deviation of hematological parameters were extracted using Microsoft Excel and exported to Stata 11 for meta-analysis. The pooled standardized mean difference (SMD) was determined using the random effects model, and heterogeneity was quantified using Higgins' I2 statistics. Egger's test and funnel plot were performed to measure bias. Furthermore, a sensitivity analysis was performed to determine the small study effect.

Results

Initially 39, 222 articles were identified. After screening of the entire methodology, 22 articles with 14,041 study participants (6,146 T2DM, 416 T1DM patients and 7,479 healthy controls) were included in this study. The pooled SMD in TLC (109/L) was 0.66 and -0.21, in T2DM and T1DM, respectively. Differences in absolute differential WBC counts for neutrophils, eosinophils, basophils, lymphocytes and monocytes in T2DM were 0.84, -1.59, 3.20, 0.36 and 0.26, respectively. The differences in relative differential counts (%) in T2DM were as follows: neutrophils: 1.31, eosinophils: -0.99, basophils: 0.34, lymphocytes: -0.19 and monocyte: -0.64. The SMD of differential counts of WBC (109/L) parameters; neutrophils, lymphocytes, monocytes and basophils in T1DM were -0.10, -0.69, 0.19, and -0.32, respectively. The pooled SMD in RBC parameters in T2DM were as follows: RBC: -0.57 (106/μL), Hb: -0.73 g/dL and HCT: -1.22%, Where as in T1DM RBC, Hb and HCT were -1.23 (106/μL), -0.80 g/dL and -0.29%, respectively.

Conclusion

Patients with T2DM had significantly increased TLC counts, absolute neutrophil, basophil, lymphocyte, monocyte counts and relative counts of neutrophils and basophils in comparison to controls. On the contrary, the absolute eosinophil count and relative lymphocyte, eosinophil and monocyte counts were decreased. In T1DM, WBC parameters were significantly decreased except monocytes. RBC parameters were found to be significantly decreased in T2DM patients. In T1DM, Hb and HCT were significantly decreased. However, there is no significant difference in RBC as compared with non-diabetic controls. The findings indicated a significant alteration of WBC and RBC parameters in both diabetic patients suggesting the considerable metabolic effect of diabetes on hematologic parameters.

Systematic review registration

https://www.crd.york.ac.uk/prospero/export_details_pdf.php, identifier [CRD42023413486].

Dying to Defend: Neutrophil Death Pathways and their Implications in Immunity

Neutrophils, accounting for ≈70% of human peripheral leukocytes, are key cells countering bacterial and fungal infections. Neutrophil homeostasis involves a balance between cell maturation, migration, aging, and eventual death. Neutrophils undergo different death pathways depending on their interactions with microbes and external environmental cues. Neutrophil death has significant physiological implications and leads to distinct immunological outcomes. This review discusses the multifarious neutrophil death pathways, including apoptosis, NETosis, pyroptosis, necroptosis, and ferroptosis, and outlines their effects on immune responses and disease progression. Understanding the multifaceted aspects of neutrophil death, the intersections among signaling pathways and ramifications of immunity will help facilitate the development of novel therapeutic methods.

Low-Density Neutrophils Contribute to Subclinical Inflammation in Patients with Type 2 Diabetes

Type 2 diabetes (T2D) is characterized by low-grade inflammation. Low-density neutrophils (LDNs) represent normally less than 2% of total neutrophils but increase in multiple pathologies, releasing inflammatory cytokines and neutrophil extracellular traps (NETs). We assessed the count and role of high-density neutrophils (HDNs), LDNs, and NET-related activities in patients with T2D. HDNs and LDNs were purified by fluorescence-activated cell sorting (FACS) and counted by flow cytometry. Circulating inflammatory and NETs biomarkers were measured by ELISA (Enzyme Linked Immunosorbent Assay). NET formation was quantified by confocal microscopy. Neutrophil adhesion onto a human extracellular matrix (hECM) was assessed by optical microscopy. We recruited 22 healthy volunteers (HVs) and 18 patients with T2D. LDN counts in patients with diabetes were significantly higher (160%), along with circulating NETs biomarkers (citrullinated H3 histone (H3Cit), myeloperoxidase (MPO), and MPO-DNA (137%, 175%, and 69%, respectively) versus HV. Circulating interleukins (IL-6 and IL-8) and C-Reactive Protein (CRP) were significantly increased by 117%, 171%, and 79%, respectively, in patients compared to HVs. Isolated LDNs from patients expressed more H3Cit, MPO, and NETs, formed more NETs, and adhered more on hECM compared to LDNs from HVs. Patients with T2D present higher levels of circulating LDN- and NET-related biomarkers and associated pro-inflammatory activities.

Unveiling the Web: Exploring the Multifaceted Role of Neutrophil Extracellular Traps in Ocular Health and Disease

Neutrophil extracellular traps (NETs) play an essential role in antimicrobial defense. However, NETs have also been shown to promote and mediate a wide spectrum of diseases, including cancer, diabetes mellitus, cardiovascular diseases, and ocular diseases. Data regarding NETs in ocular diseases remain limited. In physiological conditions, NETs protect the eye from debris and cleave proinflammatory cytokines, including several interleukins. On the other hand, NETs play a role in corneal diseases, such as dry eye disease and ocular graft-versus-host disease, where they promote acinar atrophy and delayed wound healing. Additionally, NET levels positively correlate with increased severity of uveitis. NETs have also been described in the context of diabetic retinopathy. Although increased NET biomarkers are associated with an increased risk of the disease, NETs also assist in the elimination of pathological blood vessels and the regeneration of normal vessels. Targeting NET pathways for the treatment of ocular diseases has shown promising outcomes; however, more studies are still needed in this regard. In this article, we summarize the literature on the protective roles of NETs in the eye. Then, we describe their pathogenetic effects in ocular diseases, including those of the cornea, uvea, and retinal blood vessels. Finally, we describe the therapeutic implications of targeting NETs in such conditions.

Metformin reverses impaired osteogenesis due to hyperglycemia-induced neutrophil extracellular traps formation

Diabetic patients suffer from delayed fracture healing and impaired osteogenic function, but the underlying pathophysiological mechanisms are not fully understood. Neutrophil extracellular traps (NETs) formed by neutrophils in high glucose microenvironments affect the healing of wounds and other tissues. Some evidence supports that NETs may inhibit osteogenic processes in the microenvironment through sustained inflammatory activation. In this study, we observed that high glucose-induced NETs led to sustained inflammatory activation of macrophages. Pro-inflammatory NETs inhibited the osteogenic function of osteoblasts in vitro. A bone defect healing model based on diabetic rat animal models confirmed that bone healing was impaired in a high glucose environment, but this process could be reversed by DNase I, a NETs clearance agent. More importantly, the classic hypoglycemic drug metformin had a similar antagonistic effect as DNase I and could reverse the inhibitory effect of NETs on osteogenesis in a high-glucose environment. In summary, we found that NETs formation induced by high glucose microenvironment is a potential cause of osteogenic dysfunction in diabetic patients, and metformin can reverse this osteogenic disadvantage.

DNase based therapeutic approaches for the treatment of NETosis related inflammatory diseases

Neutrophils are the primary host innate immune cells defending against pathogens. One proposed mechanism by which neutrophils limit pathogen transmission is NETosis, which includes releasing the nuclear content into the cytosol by forming pores in the plasma membrane. The extrusion of cellular deoxyribonucleic acid (DNA) results in neutrophil extracellular traps (NETs) composed of nuclear DNA associated with histones and granule proteins. NETosis is driven by the enzyme PAD-4 (Peptidylarginine deiminase-4), which converts arginine into citrulline, leading to decondensation of chromatin, separation of DNA, and eventual extrusion. DNase is responsible for the breakdown of NETs. On the one hand, the release of DNase may interfere with the antibacterial effects of NETs; further, DNase may protect tissues from self-destruction caused by the increased release of NET under septic conditions. NETs in physiological quantities are expected to have a role in anti-infectious innate immune responses. In contrast, abnormally high concentrations of NETs in the body that are not adequately cleared by DNases can damage tissues and cause inflammation. Through several novel approaches, it is now possible to avoid the adverse effects caused by the continued release of NETs into the extracellular environment. In this review we have highlighted the basic mechanisms of NETosis, its significance in the pathogenesis of various inflammatory disorders, and the role of DNase enzyme with a focus on the possible function of nanotechnology in its management.

Immune Fingerprint in Diabetes: Ocular Surface and Retinal Inflammation

Diabetes is a prevalent global health issue associated with significant morbidity and mortality. Diabetic retinopathy (DR) is a well-known inflammatory, neurovascular complication of diabetes and a leading cause of preventable blindness in developed countries among working-age adults. However, the ocular surface components of diabetic eyes are also at risk of damage due to uncontrolled diabetes, which is often overlooked. Inflammatory changes in the corneas of diabetic patients indicate that inflammation plays a significant role in diabetic complications, much like in DR. The eye's immune privilege restricts immune and inflammatory responses, and the cornea and retina have a complex network of innate immune cells that maintain immune homeostasis. Nevertheless, low-grade inflammation in diabetes contributes to immune dysregulation. This article aims to provide an overview and discussion of how diabetes affects the ocular immune system's main components, immune-competent cells, and inflammatory mediators. By understanding these effects, potential interventions and treatments may be developed to improve the ocular health of diabetic patients.

NET Proteome in Established Type 1 Diabetes Is Enriched in Metabolic Proteins

BACKGROUND AND AIMS

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by a T-cell-mediated destruction of the pancreatic insulin-producing beta cells. A growing body of evidence suggests that abnormalities in neutrophils and neutrophil extracellular trap (NET) formation (NETosis) are associated with T1D pathophysiology. However, little information is available on whether these changes are primary neutrophil defects or related to the environmental signals encountered during active disease.

METHODS

In the present work, the NET proteome (NETome) of phorbol 12-myristate 13-acetate (PMA)- and ionomycin-stimulated neutrophils from people with established T1D compared to healthy controls (HC) was studied by proteomic analysis.

RESULTS

Levels of NETosis, in addition to plasma levels of pro-inflammatory cytokines and NET markers, were comparable between T1D and HC subjects. However, the T1D NETome was distinct from that of HC in response to both stimuli. Quantitative analysis revealed that the T1D NETome was enriched in proteins belonging to metabolic pathways (i.e., phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and UTP-glucose-1-phosphate uridylyltransferase). Complementary metabolic profiling revealed that the rate of extracellular acidification, an approximate measure for glycolysis, and mitochondrial respiration were similar between T1D and HC neutrophils in response to both stimuli.

CONCLUSION

The NETome of people with established T1D was enriched in metabolic proteins without an apparent alteration in the bio-energetic profile or dysregulated NETosis. This may reflect an adaptation mechanism employed by activated T1D neutrophils to avoid impaired glycolysis and consequently excessive or suboptimal NETosis, pivotal in innate immune defence and the resolution of inflammation.

New insight into the composition of extracellular traps released by macrophages exposed to different types of inducers

Neutrophil extracellular trap (NET) release plays a key role in many chronic disease settings, including atherosclerosis. They are critical to innate immune defence, but also contribute to disease by promoting thrombosis and inflammation. Macrophages are known to release extracellular traps or "METs", but their composition and role in pathological processes are less well defined. In this study, we examined MET release from human THP-1 macrophages exposed to model inflammatory and pathogenic stimuli, including tumour necrosis factor α (TNFα), hypochlorous acid (HOCl) and nigericin. In each case, there was release of DNA from the macrophages, as visualized by fluorescence microscopy with the cell impermeable DNA binding dye SYTOX green, consistent with MET formation. Proteomic analysis on METs released from macrophages exposed to TNFα and nigericin reveals that they are composed of linker and core histones, together with a range of cytosolic and mitochondrial proteins. These include proteins involved in DNA binding, stress responses, cytoskeletal organisation, metabolism, inflammation, anti-microbial activity, and calcium binding. Quinone oxidoreductase in particular, was highly abundant in all METs but has not been reported previously in NETs. Moreover, there was an absence of proteases in METs in contrast to NETs. Some of the MET histones, contained post-translational modifications, including acetylation and methylation of Lys but not citrullination of Arg. These data provide new insight into the potential implications of MET formation in vivo and their contributions to immune defence and pathology.

Antioxidant Strategies to Modulate NETosis and the Release of Neutrophil Extracellular Traps during Chronic Inflammation

Extracellular traps are released by neutrophils and other immune cells as part of the innate immune response to combat pathogens. Neutrophil extracellular traps (NETs) consist of a mesh of DNA and histone proteins decorated with various anti-microbial granule proteins, such as elastase and myeloperoxidase (MPO). In addition to their role in innate immunity, NETs are also strongly linked with numerous pathological conditions, including atherosclerosis, sepsis and COVID-19. This has led to significant interest in developing strategies to inhibit NET release. In this study, we have examined the efficacy of different antioxidant approaches to selectively modulate the inflammatory release of NETs. PLB-985 neutrophil-like cells were shown to release NETs on exposure to phorbol myristate acetate (PMA), hypochlorous acid or nigericin, a bacterial peptide derived from Streptomyces hygroscopicus. Studies with the probe R19-S indicated that treatment of the PLB-985 cells with PMA, but not nigericin, resulted in the production of HOCl. Therefore, studies were extended to examine the efficacy of a range of antioxidant compounds that modulate HOCl production by MPO to prevent NETosis. It was shown that thiocyanate, selenocyanate and various nitroxides could prevent NETosis in PLB-985 neutrophils exposed to PMA and HOCl, but not nigericin. These results were confirmed in analogous experiments with freshly isolated primary human neutrophils. Taken together, these data provide new information regarding the utility of supplementation with MPO inhibitors and/or HOCl scavengers to prevent NET release, which could be important to more specifically target pathological NETosis in vivo.

Lower Circulating Cell-Free Mitochondrial DNA Is Associated with Heart Failure in Type 2 Diabetes Mellitus Patients

Cell-free nuclear (cf-nDNA) and mitochondrial (cf-mDNA) DNA are released from damaged cells in type 2 diabetes mellitus (T2DM) patients, contributing to adverse cardiac remodeling, vascular dysfunction, and inflammation. The purpose of this study was to correlate the presence and type of cf-DNAs with HF in T2DM patients. A total of 612 T2DM patients were prescreened by using a local database, and 240 patients (120 non-HF and 120 HF individuals) were ultimately selected. The collection of medical information, including both echocardiography and Doppler imagery, as well as the assessment of biochemistry parameters and the circulating biomarkers, were performed at baseline. The N-terminal brain natriuretic pro-peptide (NT-proBNP) and cf-nDNA/cf-mtDNA levels were measured via an ELISA kit and real-time quantitative PCR tests, respectively. We found that HF patients possessed significantly higher levels of cf-nDNA (9.9 ± 2.5 μmol/L vs. 5.4 ± 2.7 μmol/L; p = 0.04) and lower cf-mtDNA (15.7 ± 3.3 μmol/L vs. 30.4 ± 4.8 μmol/L; p = 0.001) than those without HF. The multivariate log regression showed that the discriminative potency of cf-nDNA >7.6 μmol/L (OR = 1.07; 95% CI = 1.03–1.12; p = 0.01) was higher that the NT-proBNP (odds ratio [OR] = 1.10; 95% confidence interval [CI] = 1.04–1.19; p = 0.001) for HF. In conclusion, we independently established that elevated levels of cf-nDNA, originating from NT-proBNP, were associated with HF in T2DM patients.

Neutrophil extracellular traps in autoimmune diseases: Analysis of the knowledge map

Introduction

Recent studies have shown much progress in the research of exosomes in AIDs. However, there is no bibliometric analysis in this research field. This study aimed to provide a bibliometrics review of the knowledge structure and research hotspots of neutrophil extracellular traps (NETs) in autoimmune diseases (AIDs).

Methods

Articles relevant to NETs in AIDs from 2010 to 2022 were retrieved through the Web of Science Core Collection (WoSCC) database. This bibliometric analysis was performed by VOSview, CiteSpace, and Scimago Graphica.

Results

A total of 289 papers analyzed in this research were from 493 organizations in 47 countries by 1537 authors. They were published in 133 journals and cited 20,180 citations from 2,465 journals. The number of annual publications in this field is growing steadily and rapidly, with the United States, China and Germany leading the research effort. Frontiers in Immunology and Journal of Immunology have significantly impacted research in this field. Kaplan, Mariana J, from the National Institutes of Health (The United States), has the most published articles, and Brinkmann, v, from Max Planck Institute for Infection Biology (Germany), is the most co-cited author. Systemic lupus erythematosus and rheumatoid arthritis are the leading topics in this field. The trend of clinical application in the future is the development of new therapies by controlling NETs in the progression of AIDs.

Conclusions

Our study summarized the research trends and developments of NETs in AIDs in recent years and would provide a reference for scholars in this field.

Methylglyoxal-Modified Human Serum Albumin Binds to Leukocyte Myeloperoxidase and Inhibits its Enzymatic Activity

Hyperglycemia in diabetes mellitus induces modification of proteins by glucose and its derivative methylglyoxal (MG). Neutrophils perform their bactericidal activity mainly via reactive halogen (RHS) and oxygen (ROS) species generation catalyzed by myeloperoxidase (MPO) stored in neutrophil azurophilic granules (AGs) and membrane NADPH oxidase, respectively. Herein, we study the binding of human serum albumin (HSA) modified with MG (HSA-MG) to MPO and its effects on MPO activity and release by neutrophils. Peroxidase activity of MPO was registered by oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, and chlorinating activity by decolorization of Celestine blue B dye. Binding of HSA-MG to MPO was studied by affinity chromatography, disc-electrophoresis, ligand Western blotting and enzyme-linked solid phase immunoassay using monoclonal antibodies (mAbs) to MPO. ROS and RHS generation were detected by lucigenin (Luc) and luminol (Lum) chemiluminescence (CL), respectively. Neutrophil degranulation was assessed by flow cytometry using fluorescent labeled antibodies to the marker proteins CD63 from AGs and CD11b from peroxidase-negative granules (PNGs). NETosis was assayed by quantifying DNA network-like structures (NET-like structures) in blood smears stained by Romanowsky. HSA-MG bound to MPO, giving a stable complex (Kd = 1.5 nM) and competing with mAbs, and non-competitively inhibited peroxidase and chlorinating MPO activity and induced degranulation of PNGs but not of AGs. HSA-MG enhanced Luc-CL per se or following PMA, unlike Lum-CL, and did not affect spontaneous or PMA-stimulated NETosis. Thus, HSA modified under hyperglycemia-like conditions stimulated NADPH oxidase of neutrophils but dampened their functions dependent on activity of MPO, with no effect on its release via degranulation or NETosis. This phenomenon could underlie the downregulation of bactericidal activity of MPO and neutrophils, and hence of innate immunity, giving rise to wound healing impairment and susceptibility to infection in patients with hyperglycemia.

Obesity, Diabetes Mellitus, and Metabolic Syndrome: Review in the Era of COVID-19

Coronavirus disease 2019 (COVID-19), a novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now at pandemic levels leading to considerable morbidity and mortality throughout the globe. Patients with obesity, diabetes, and metabolic syndrome (MetS) are mainly susceptible and more probably to get severe side effects when affected by this virus. The pathophysiologic mechanisms for these notions have not been completely known. The pro-inflammatory milieu observed in patients with metabolic disruption could lead to COVID-19-mediated host immune dysregulation, such as immune dysfunction, severe inflammation, microvascular dysfunction, and thrombosis. The present review expresses the current knowledge regarding the influence of obesity, diabetes mellitus, and MetS on COVID-19 infection and severity, and their pathophysiological mechanisms.

Neutrophil extracellular traps in fungal infections: A seesaw battle in hosts

Fungal infections are a growing health care challenge. Neutrophils play a key role in defense against fungal infections. There are many effective ways for neutrophils to eliminate fungal invaders, such as phagocytosis, oxidative bursts, and the formation of extracellular traps. This process has received considerable attention and has made rapid progress since neutrophil extracellular traps (NETs) formation was described. Here, we describe the formation, induction, and function of NETs, as well as fungal strategies against NETs hunting. We highlight the effects of NETs on common fungal pathogens and how these pathogens survive.

Gene Biomarkers Related to Th17 Cells in Macular Edema of Diabetic Retinopathy: Cutting-Edge Comprehensive Bioinformatics Analysis and In Vivo Validation

Background

Previous studies have shown that T-helper 17 (Th17) cell-related cytokines are significantly increased in the vitreous of proliferative diabetic retinopathy (PDR), suggesting that Th17 cells play an important role in the inflammatory response of diabetic retinopathy (DR), but its cell infiltration and gene correlation in the retina of DR, especially in diabetic macular edema (DME), have not been studied.

Methods

The dataset GSE160306 was downloaded from the Gene Expression Omnibus (GEO) database, which contains 9 NPDR samples and 10 DME samples. ImmuCellAI algorithm was used to estimate the abundance of Th17 cells in 24 kinds of infiltrating immune cells. The differentially expressed Th17 related genes (DETh17RGs) between NPDR and DME were documented by difference analysis and correlation analysis. Through aggregate analyses such as gene ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment analysis, a protein-protein interaction (PPI) network was constructed to analyze the potential function of DETh17RGs. CytoHubba plug-in algorithm, Lasso regression analysis and support vector machine recursive feature elimination (SVM-RFE) were implemented to comprehensively identify Hub DETh17RGs. The expression archetypes of Hub DETh17RGs were further verified in several other independent datasets related to DR. The Th17RG score was defined as the genetic characterization of six Hub DETh17RGs using the GSVA sample score method, which was used to distinguish early and advanced diabetic nephropathy (DN) as well as normal and diabetic nephropathy. Finally, real-time quantitative PCR (qPCR) was implemented to verify the transcription levels of Hub DETh17RGs in the STZ-induced DR model mice (C57BL/6J).

Results

238 DETh17RGs were identified, of which 212 genes were positively correlated while only 26 genes were negatively correlated. Six genes (CD44, CDC42, TIMP1, BMP7, RHOC, FLT1) were identified as Hub DETh17RGs. Because DR and DN have a strong correlation in clinical practice, the verification of multiple independent datasets related to DR and DN proved that Hub DETh17RGs can not only distinguish PDR patients from normal people, but also distinguish DN patients from normal people. It can also identify the initial and advanced stages of the two diseases (NPDR vs DME, Early DN vs Advanced DN). Except for CDC42 and TIMP1, the qPCR transcription levels and trends of other Hub DETh17RGs in STZ-induced DR model mice were consistent with the human transcriptome level in this study.

Conclusion

This study will improve our understanding of Th17 cell-related molecular mechanisms in the progression of DME. At the same time, it also provides an updated basis for the molecular mechanism of Th17 cell crosstalk in the eye and kidney in diabetes.

The Role of Neutrophil Extracellular Traps in the Ocular System

Purpose: Neutrophils remain at the top of congenital and adaptive immune systems. The past 20 years witnessed a steep rise in the interest in neutrophil extracellular traps (NETs), which are a novel type of anti-pathogen mechanism coordinated with neutrophils. However, accumulating data revealed that excessive NETs in the host were associated with exacerbated inflammation, thrombosis, and autoimmunity. Increasing evidence found the participation of NETs in the pathophysiological process of many infectious and sterile diseases in the ocular system. Therefore, we discussed the role of neutrophil extracellular traps in the ocular system in this review.Methods: Articles were searched on PubMed, Embase and Web of science up to December 2021.Results: In this review, we exhibited the protective role of neutrophils patrolling the ocular surface from invading pathogens and their contribution to exacerbated inflammation and thrombogenesis in some ocular diseases. We also discussed the physiological and pathological processes of NET generation to identify novel biomarkers and therapeutic targets to interrupt immoderate NET formation and alleviate NET-induced harmful effects.Conclusions: Neutrophils and NETs are quite important for immune responses in the ocular system, while their negative effects on ocular tissue should also be emphasized, which could serve as novel biomarkers and potential therapeutic targets.

Extracellular Vesicles and Thrombogenicity in Atrial Fibrillation

Extracellular vesicles (EVs) are defined as a heterogenic group of lipid bilayer vesicular structures with a size in the range of 30–4000 nm that are released by all types of cultured cells. EVs derived from platelets, mononuclears, endothelial cells, and adipose tissue cells significantly increase in several cardiovascular diseases, including in atrial fibrillation (AF). EVs are engaged in cell-to-cell cooperation, endothelium integrity, inflammation, and immune response and are a cargo for several active molecules, such as regulatory peptides, receptors, growth factors, hormones, and lipids. Being transductors of the intercellular communication, EVs regulate angiogenesis, neovascularization, coagulation, and maintain tissue reparation. There is a large amount of evidence regarding the fact that AF is associated with elevated levels of EVs derived from platelets and mononuclears and a decreased number of EVs produced by endothelial cells. Moreover, some invasive procedures that are generally performed for the treatment of AF, i.e., pulmonary vein isolation, were found to be triggers for elevated levels of platelet and mononuclear EVs and, in turn, mediated the transient activation of the coagulation cascade. The review depicts the role of EVs in thrombogenicity in connection with a risk of thromboembolic complications, including ischemic stroke and systemic thromboembolism, in patients with various forms of AF.

CD8+T Cell-Related Gene Biomarkers in Macular Edema of Diabetic Retinopathy

BACKGROUND

CD8+T lymphocytes have a strong pro-inflammatory effect in all parts of the tissue, and some studies have demonstrated that its concentration in the vitreous increased significantly, suggesting that CD8+T cells play a pivotal role in the inflammatory response of diabetic retinopathy (DR). However, the infiltration of CD8+T cells in the DR retina, especially in diabetic macular edema (DME), and its related genes are still unclear.

METHODS

Download the GSE16036 dataset from the Gene Expression Omnibus (GEO) database. The ImmuCellAI program was performed to evaluate the abundance of 24 immune cells including CD8+T cells. The CD8+T cell-related genes (DECD8+TRGs) between non-proliferative diabetic retinopathy (NPDR) and DME were detected via difference analysis and correlation analysis. Enrichment analysis and protein-protein interaction (PPI) network mapping were implemented to explore the potential function of DECD8+TRGs. Lasso regression, support vector machine recursive feature elimination (SVM-RFE), CytoHubba plug-in and MCODE plug-in in Cytoscape software, and Weighted Gene Co-Expression Network Analysis (WGCNA) were performed to comprehensively analyze and obtain Hub DECD8+TRGs. Hub DECD8+TRGs expression patterns were further validated in other two DR-related independent datasets. The CD8+TRG score was defined as the genetic characterization of Hub DECD8+TRGs using the GSVA sample scoring method, which can be administered to distinguish early and advanced diabetic nephropathy (DN) as well as normal and DN. Finally, the transcription level of DECD8+TRGs in DR model mouse were verified by quantitative real-time PCR (qPCR).

RESULTS

A total of 371 DECD8+TRGs were identified, of which 294 genes were positively correlated and only 77 genes were negatively correlated. Eight genes (IKZF1, PTPRC, ITGB2, ITGAX, TLR7, LYN, CD74, SPI1) were recognized as Hub DECD8+TRGs. DR and DN, which have strong clinical correlation, have been proved to be associated with CD8+T cell-related hub genes by multiple independent data sets. Hub DECD8+TRGs can not only distinguish PDR from normal and DN from normal, but also play a role in the early and progressive stages of the two diseases (NPDR vs DME, Early DN vs Advanced DN). The qPCR transcription level and trend of Hub DECD8+TRGs in DR mouse model was basically the same as that in human transcriptome.

CONCLUSION

This study not only increases our understanding of the molecular mechanism of CD8+T cells in the progression of DME, but also expands people's cognitive vision of the molecular mechanism of crosstalk of CD8+T cells in the eyes and kidneys of patients with diabetes.

The Influence of Different Types of Diabetes on Vascular Complications

The final outcome of diabetes is chronic complications, of which vascular complications are the most serious, which is the main cause of death for diabetic patients and the direct cause of the increase in the cost of diabetes. Type 1 and type 2 diabetes are the main types of diabetes, and their pathogenesis is completely different. Type 1 diabetes is caused by genetics and immunity to destroy a large number of β cells, and insulin secretion is absolutely insufficient, which is more prone to microvascular complications. Type 2 diabetes is dominated by insulin resistance, leading to atherosclerosis, which is more likely to progress to macrovascular complications. This article explores the pathogenesis of two types of diabetes, analyzes the pathogenesis of different vascular complications, and tries to explain the different trends in the progression of different types of diabetes to vascular complications, in order to better prevent diabetes and its vascular complications.

The Emerging Role of Neutrophil Extracellular Traps in Arterial, Venous and Cancer-Associated Thrombosis

Neutrophils play a vital role in the formation of arterial, venous and cancer-related thrombosis. Recent studies have shown that in a process known as NETosis, neutrophils release proteins and enzymes complexed to DNA fibers, collectively called neutrophil extracellular traps (NETs). Although NETs were originally described as a way for the host to capture and kill bacteria, current knowledge indicates that NETs also play an important role in thrombosis. According to recent studies, the destruction of vascular microenvironmental homeostasis and excessive NET formation lead to pathological thrombosis. In vitro experiments have found that NETs provide skeletal support for platelets, red blood cells and procoagulant molecules to promote thrombosis. The protein components contained in NETs activate the endogenous coagulation pathway to promote thrombosis. Therefore, NETs play an important role in the formation of arterial thrombosis, venous thrombosis and cancer-related thrombosis. This review will systematically summarize and explain the study of NETs in thrombosis in animal models and in vivo experiments to provide new targets for thrombosis prevention and treatment.

A Review of Neutrophil Extracellular Traps (NETs) in Disease: Potential Anti-NETs Therapeutics

Activated neutrophils release neutrophil extracellular traps (NETs) in response to a variety of stimuli. NETosis is driven by protein-arginine deiminase type 4, with the release of intracellular granule components that function by capturing and destroying microbes, including viral, fungal, bacterial, and protozoal pathogens. The positive effects of pathogen control are countered by pro-inflammatory effects as demonstrated in a variety of diseases. Components of NETS are non-specific, and other than controlling microbes, they cause injury to surrounding tissue by themselves or by increasing the pro-inflammatory response. NETs can play a role in enhancement of the inflammation seen in autoimmune diseases including psoriasis, rheumatoid arthritis, and systemic lupus erythematosis. In addition, autoinflammatory diseases such as gout have been associated with NETosis. Inhibition of NETs may decrease the severity of many diseases improving survival. Herein, we describe NETosis in different diseases focusing on the detrimental effect of NETs and outline possible therapeutics that can be used to mitigate netosis. There is a need for more studies and clinical trials on these and other compounds that could prevent or destroy NETs, thereby decreasing damage to patients.

Lifestyle Intervention Improves Prothrombotic Coagulation Profile in Individuals at High Risk for Type 2 Diabetes

CONTEXT

Patients with obesity and insulin resistance are at higher risk for arterial and venous thrombosis due to a prothrombotic state.

OBJECTIVE

The present study addressed whether this is reversible by lifestyle intervention and elucidated potential underlying associations.

METHODS

A total of 100 individuals with impaired glucose tolerance or impaired fasting plasma glucose participated in a 1-year lifestyle intervention, including precise metabolic phenotyping and MRS-based determination of liver fat content as well as a comprehensive analysis of coagulation parameters before and after this intervention.

RESULTS

During the lifestyle intervention, significant reductions in coagulation factor activities (II, VII, VIII, IX, XI, and XII) were observed. Accordingly, prothrombin time (PT%) and activated partial thromboplastin time (aPTT) were slightly decreased and prolonged, respectively. Moreover, plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF), and also protein C and protein S decreased. Fibrinogen, antithrombin, D-dimer, and FXIII remained unchanged. Searching for potential regulators, especially weight loss, but also liver fat reduction, improved insulin sensitivity, and decreased low-grade inflammation were linked to favorable changes in hemostasis parameters. Independent of weight loss, liver fat reduction (FII, protein C, protein S, PAI-1, vWF), improved insulin sensitivity (protein S, PAI-1), and reduced low-grade inflammation (PT%, aPTT, FVIII/IX/XI/XII, vWF) were identified as single potential regulators.

CONCLUSION

Lifestyle intervention is able to improve a prothrombotic state in individuals at high risk for type 2 diabetes. Besides body weight, liver fat content, insulin sensitivity, and systemic low-grade inflammation are potential mechanisms for improvements in hemostasis and could represent future therapeutic targets.

Neutrophil Extracellular Traps Affecting Cardiovascular Health in Infectious and Inflammatory Diseases

Neutrophil extracellular traps (NETs) are web-like structures of decondensed extracellular chromatin fibers and neutrophil granule proteins released by neutrophils. NETs participate in host immune defense by entrapping pathogens. They are pro-inflammatory in function, and they act as an initiator of vascular coagulopathies by providing a platform for the attachment of various coagulatory proteins. NETs are diverse in their ability to alter physiological and pathological processes including infection and inflammation. In this review, we will summarize recent findings on the role of NETs in bacterial/viral infections associated with vascular inflammation, thrombosis, atherosclerosis and autoimmune disorders. Understanding the complex role of NETs in bridging infection and chronic inflammation as well as discussing important questions related to their contribution to pathologies outlined above may pave the way for future research on therapeutic targeting of NETs applicable to specific infections and inflammatory disorders.

Towards Goals to Refine Prophylactic and Therapeutic Strategies Against COVID-19 Linked to Aging and Metabolic Syndrome

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gave rise to the coronavirus disease 2019 (COVID-19) pandemic. A strong correlation has been demonstrated between worse COVID-19 outcomes, aging, and metabolic syndrome (MetS), which is primarily derived from obesity-induced systemic chronic low-grade inflammation with numerous complications, including type 2 diabetes mellitus (T2DM). The majority of COVID-19 deaths occurs in people over the age of 65. Individuals with MetS are inclined to manifest adverse disease consequences and mortality from COVID-19. In this review, we examine the prevalence and molecular mechanisms underlying enhanced risk of COVID-19 in elderly people and individuals with MetS. Subsequently, we discuss current progresses in treating COVID-19, including the development of new COVID-19 vaccines and antivirals, towards goals to elaborate prophylactic and therapeutic treatment options in this vulnerable population.

A Bittersweet Response to Infection in Diabetes; Targeting Neutrophils to Modify Inflammation and Improve Host Immunity

Chronic and recurrent infections occur commonly in both type 1 and type 2 diabetes (T1D, T2D) and increase patient morbidity and mortality. Neutrophils are professional phagocytes of the innate immune system that are critical in pathogen handling. Neutrophil responses to infection are dysregulated in diabetes, predominantly mediated by persistent hyperglycaemia; the chief biochemical abnormality in T1D and T2D. Therapeutically enhancing host immunity in diabetes to improve infection resolution is an expanding area of research. Individuals with diabetes are also at an increased risk of severe coronavirus disease 2019 (COVID-19), highlighting the need for re-invigorated and urgent focus on this field. The aim of this review is to explore the breadth of previous literature investigating neutrophil function in both T1D and T2D, in order to understand the complex neutrophil phenotype present in this disease and also to focus on the development of new therapies to improve aberrant neutrophil function in diabetes. Existing literature illustrates a dual neutrophil dysfunction in diabetes. Key pathogen handling mechanisms of neutrophil recruitment, chemotaxis, phagocytosis and intracellular reactive oxygen species (ROS) production are decreased in diabetes, weakening the immune response to infection. However, pro-inflammatory neutrophil pathways, mainly neutrophil extracellular trap (NET) formation, extracellular ROS generation and pro-inflammatory cytokine generation, are significantly upregulated, causing damage to the host and perpetuating inflammation. Reducing these proinflammatory outputs therapeutically is emerging as a credible strategy to improve infection resolution in diabetes, and also more recently COVID-19. Future research needs to drive forward the exploration of novel treatments to improve infection resolution in T1D and T2D to improve patient morbidity and mortality.

Coronary Vasculitis

The term coronary “artery vasculitis” is used for a diverse group of diseases with a wide spectrum of manifestations and severity. Clinical manifestations may include pericarditis or myocarditis due to involvement of the coronary microvasculature, stenosis, aneurysm, or spontaneous dissection of large coronaries, or vascular thrombosis. As compared to common atherosclerosis, patients with coronary artery vasculitis are younger and often have a more rapid disease progression. Several clinical entities have been associated with coronary artery vasculitis, including Kawasaki’s disease, Takayasu’s arteritis, polyarteritis nodosa, ANCA-associated vasculitis, giant-cell arteritis, and more recently a Kawasaki-like syndrome associated with SARS-COV-2 infection. This review will provide a short description of these conditions, their diagnosis and therapy for use by the practicing cardiologist.

Histamine triggers the formation of neutrophil extracellular traps via NADPH oxidase, ERK and p38 pathways

Histamine plays a central role in various allergic diseases, such as allergic asthma and allergic rhinitis. Neutrophil extracellular traps (NETs) formation is a novel effector mechanism of neutrophils to defend against various stimuli. In this present study, we aimed to investigate the role of histamine on bovine NET formation, and examined its preliminary molecular mechanisms. Cell Counting Kit-8 (CCK8) and Lactate dehydrogenase assays showed that histamine had no significant influence on PMNs (polymorphonuclear leukocytes) viability. Confocal microscopy analyses identified NET structures by co-localizing the main components of NETs, and NET quantification revealed that histamine-triggered NETs were released in a dose-dependent manner. Furthermore, we found reactive oxygen species (ROS) production, phosphorylated extracellular signal-regulated kinase (ERK) and p38 proteins were significantly elevated in histamine-challenged PMNs. By applying functional inhibitors of nicotinamide adenine dinucleotide phosphate-oxidase (NADPH oxidase), ERK and p38, histamine-triggered NETs were markedly reduced, indicating their importance in histamine-triggered NET formation. Our findings described histamine-triggered NET formation, and revealed its potential molecular mechanisms via NADPH oxidase, ERK and p38 pathways. This is the first study to depict histamine-triggered NET formation, which could provide a new insight into histamine-related diseases.

Innate Immune Cells and Hypertension: Neutrophils and Neutrophil Extracellular Traps (NETs)

Uncontrolled immune system activation amplifies end-organ injury in hypertension. Nonetheless, the exact mechanisms initiating this exacerbated inflammatory response, thereby contributing to further increases in blood pressure (BP), are still being revealed. While participation of lymphoid-derived immune cells has been well described in the hypertension literature, the mechanisms by which myeloid-derived innate immune cells contribute to T cell activation, and subsequent BP elevation, remains an active area of investigation. In this article, we critically analyze the literature to understand how monocytes, macrophages, dendritic cells, and polymorphonuclear leukocytes, including mast cells, eosinophils, basophils, and neutrophils, contribute to hypertension and hypertension-associated end-organ injury. The most abundant leukocytes, neutrophils, are indisputably increased in hypertension. However, it is unknown how (and why) they switch from critical first responders of the innate immune system, and homeostatic regulators of BP, to tissue-damaging, pro-hypertensive mediators. We propose that myeloperoxidase-derived pro-oxidants, neutrophil elastase, neutrophil extracellular traps (NETs), and interactions with other innate and adaptive immune cells are novel mechanisms that could contribute to the inflammatory cascade in hypertension. We further posit that the gut microbiota serves as a set point for neutropoiesis and their function. Finally, given that hypertension appears to be a key risk factor for morbidity and mortality in COVID-19 patients, we put forth evidence that neutrophils and NETs cause cardiovascular injury post-coronavirus infection, and thus may be proposed as an intriguing therapeutic target for high-risk individuals. © 2021 American Physiological Society. Compr Physiol 11:1575-1589, 2021.

Neutrophil Extracellular Traps and Their Implications in Cardiovascular and Inflammatory Disease

Neutrophils are primary effector cells of innate immunity and fight infection by phagocytosis and degranulation. Activated neutrophils also release neutrophil extracellular traps (NETs) in response to a variety of stimuli. These NETs are net-like complexes composed of cell-free DNA, histones and neutrophil granule proteins. Besides the evolutionarily conserved mechanism to capture and eliminate pathogens, NETs are also associated with pathophysiological processes of various diseases. Here, we elucidate the mechanisms of NET formation and their different implications in disease. We focused on autoinflammatory and cardiovascular disorders as the leading cause of death. Neutrophil extracellular traps are not only present in various cardiovascular diseases but play an essential role in atherosclerotic plaque formation, arterial and venous thrombosis, as well as in the development and progression of abdominal aortic aneurysms. Furthermore, NETosis can be considered as a source of autoantigens and maintains an inflammatory milieu promoting autoimmune diseases. Indeed, there is further need for research into the balance between NET induction, inhibition, and degradation in order to pharmacologically target NETs and their compounds without impairing the patient’s immune defense. This review may be of interest to both basic scientists and clinicians to stimulate translational research and innovative clinical approaches.

Chalcones as Modulators of Neutrophil Oxidative Burst under Physiological and High Glucose Conditions

Several epidemiological studies indicate that neutrophils, under hyperglycemic conditions, are involved in the perpetuation of the inflammatory status, a characteristic of diabetes mellitus, leading to the production of prodigious quantities of reactive species and the release of neutrophil extracellular traps (NETs). Accordingly, our aim was to study the ability of a panel of 25 structurally related chalcones to modulate human neutrophil oxidative burst and the production of NETs under physiological and high glucose conditions. In general, all chalcones presented similar effects under physiological and high glucose conditions. 2',4-Dihydroxy-3-methoxychalcone (3), here studied for the first time, was the most active (IC₅₀ ≤ 5 μM) on the inhibition of neutrophil oxidative burst, showing the importance of the presence of hydroxy substituents at the C-2' and C-4 positions of the A and B rings, respectively, and a 3-methoxy substituent at B ring of the chalcone scaffold. In the present experimental conditions, NETs release only occurred under high glucose levels. The pentahydroxylated chalcone 1 was the only one that was able to modulate the NETs release. This study provided important considerations about the chalcones' scaffold and their modulatory effect on human neutrophil activities at physiological and high glucose conditions, evidencing their potential use as complementary antidiabetic agents.

Human CD8+ T Cells Release Extracellular Traps Co-Localized With Cytotoxic Vesicles That Are Associated With Lesion Progression and Severity in Human Leishmaniasis

Cell death plays a fundamental role in mounting protective and pathogenic immunity. Etosis is a cell death mechanism defined by the release of extracellular traps (ETs), which can foster inflammation and exert microbicidal activity. While etosis is often associated with innate cells, recent studies showed that B cells and CD4+ T cells can release ETs. Here we investigate whether CD8+ T cells can also release ETs, which might be related to cytotoxicity and tissue pathology. To these ends, we first employed an in vitro system stimulating human CD8+ T cells isolated from healthy volunteers with anti-CD3/anti-CD28. Using time-frame video, confocal and electron microscopy, we demonstrate that human CD8+ T cells release ETs upon stimulation (herein LETs – lymphocyte extracellular traps), which display unique morphology and functional characteristics. CD8+ T cell-derived LETs form long strands that co-localize with CD107a, a marker of vesicles containing cytotoxic granules. In addition, these structures connect the LET-releasing cell to other neighboring cells, often resulting in cell death. After demonstrating the release of LETs by human CD8+ T cells in vitro, we went on to study the occurrence of CD8-derived LETs in a human disease setting. Thus, we evaluated the occurrence of CD8-derived LETs in lesions from patients with human tegumentary leishmaniasis, where CD8+ T cells play a key role in mediating pathology. In addition, we evaluated the association of these structures with the intensity of the inflammatory infiltrate in early and late cutaneous, as well as in mucosal leishmaniasis lesions. We demonstrated that progression and severity of debilitating and mutilating forms of human tegumentary leishmaniasis are associated with the frequency of CD8+ T cells in etosis, as well as the occurrence of CD8-derived LETs carrying CD107a+ vesicles in the lesions. We propose that CD8+ T cell derived LETs may serve as a tool for delivering cytotoxic vesicles to distant target cells, providing insights into mechanisms of CD8+ T cell mediated pathology.

Metabolic Syndrome and COVID 19: Endocrine-Immune-Vascular Interactions Shapes Clinical Course

The ongoing coronavirus disease 2019 (COVID-19) pandemic is caused by the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Individuals with metabolic syndrome are at increased risk for poor disease outcomes and mortality from COVID-19. The pathophysiologic mechanisms for these observations have not been fully elucidated. A critical interaction between SARS-CoV-2 and the angiotensin-converting enzyme 2 (ACE2) facilitates viral entry into the host cell. ACE2 is expressed in pancreatic islets, vascular endothelium, and adipose tissue, and the SARS-CoV-2 -ACE2 interaction in these tissues, along with other factors, governs the spectrum and the severity of clinical manifestations among COVID-19 patients with metabolic syndrome. Moreover, the pro-inflammatory milieu observed in patients with metabolic syndrome may contribute toward COVID-19-mediated host immune dysregulation, including suboptimal immune responses, hyperinflammation, microvascular dysfunction, and thrombosis. This review describes the spectrum of clinical features, the likely pathophysiologic mechanisms, and potential implications for the management of metabolic syndrome in COVID-19 patients.

COVID-19-associated vasculitis and vasculopathy

The COVID-19 pandemic now totaling 13,000,000 cases and over 571,000 deaths has continued to teach the medical, scientific and lay communities about viral infectious disease in the modern era. Among the many lessons learned for the medical community is the potential for transmissibility and host infectivity of the SARS–CoV-2 virus. Moreover, it has become clear that the virus can affect any organ including the circulatory system, directly via either tissue tropism or indirectly stemming from inflammatory responses in the form of innate immunity, leukocyte debris such as cell-free DNA and histones and RNA viral particles. The following review considers COVID-19-associated vasculitis and vasculopathy as a defining feature of a virus-induced systemic disease with acute, subacute and potential chronic health implications.

Extracellular Vesicles and MicroRNA: Putative Role in Diagnosis and Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is a complex, progressive, and heterogenous retinal degenerative disease associated with diabetes duration. It is characterized by glial, neural, and microvascular dysfunction, being the blood-retinal barrier (BRB) breakdown a hallmark of the early stages. In advanced stages, there is formation of new blood vessels, which are fragile and prone to leaking. This disease, if left untreated, may result in severe vision loss and eventually legal blindness. Although there are some available treatment options for DR, most of them are targeted to the advanced stages of the disease, have some adverse effects, and many patients do not adequately respond to the treatment, which demands further research. Oxidative stress and low-grade inflammation are closely associated processes that play a critical role in the development of DR. Retinal cells communicate with each other or with another one, using cell junctions, adhesion contacts, and secreted soluble factors that can act in neighboring or long-distance cells. Another mechanism of cell communication is via secreted extracellular vesicles (EVs), through exchange of material. Here, we review the current knowledge on deregulation of cell-to-cell communication through EVs, discussing the changes in miRNA expression profiling in body fluids and their role in the development of DR. Thereafter, current and promising therapeutic agents for preventing the progression of DR will be discussed.

Neutrophil Extracellular Traps: Signaling Properties and Disease Relevance

Neutrophil extracellular traps (NETs) are characterized as extracellular DNA fibers comprised of histone and cytoplasmic granule proteins. NETs were first described as a form of innate response against pathogen invasion, which can capture pathogens, degrade bacterial toxic factors, and kill bacteria. Additionally, NETs also provide a scaffold for protein and cell binding. Protein binding to NETs further activate the coagulation system which participates in thrombosis. In addition, NETs also can damage the tissues due to the proteins they carry. Many studies have suggested that the excessive formation of NETs may contribute to a range of diseases, including thrombosis, atherosclerosis, autoimmune diseases, and sepsis. In this review, we describe the structure and components of NETs, models of NET formation, and detection methods. We also discuss the molecular mechanism of NET formation and their disease relevance. Modulation of NET formation may provide a new route for the prevention and treatment of releated human diseases.

Validation of CDr15 as a new dye for detecting neutrophil extracellular trap

Neutrophil extracellular trap (NET) is one of the first-line defenses against microbes. Under certain circumstances, however, it also plays an aggravating factor in diverse inflammation-related diseases including cancers and vascular diseases. Our aim is to develop a new method to detect NET in cells and tissues using a DNA-specific fluorescence probe CDr15. CDr15 was characterized to be impermeable to the cell membranes and to emit a strong fluorescence in association with extracellular DNAs in NET. Due to these properties, CDr15 was successfully shown to quantify NETs in vitro and to be applicable for real-time monitoring NET formation in PMA-stimulated neutrophils. Even in formaldehyde-fixed tumor specimens, CDr15 could detect NETs spreading around cancer cells. Compared with DAPI and SYTOX DNA dyes, CDr15 showed a lower level of background fluorescence and a higher specificity in NET detection. Based on these results, we propose CDr15 as a novel marker of NET to be applicable in experimental and clinical studies.

Extracellular Endothelial Cell-Derived Vesicles: Emerging Role in Cardiac and Vascular Remodeling in Heart Failure

Extracellular vesicles play a pivotal role in numerous physiological (immune response, cell-to-cell cooperation, angiogenesis) and pathological (reparation, inflammation, thrombosis/coagulation, atherosclerosis, endothelial dysfunction) processes. The development of heart failure is strongly associated with endothelial dysfunction, microvascular inflammation, alteration in tissue repair, and cardiac and vascular remodeling. It has been postulated that activated endothelial cell-derived vesicles are not just transfer forms of several active molecules (such as regulatory peptides, coagulation factors, growth factors, active molecules, hormones that are embedded onto angiogenesis, tissue reparation, proliferation, and even prevention from ischemia/hypoxia), but are instead involved in direct myocardial and vascular damage due to regulation of epigenetic responses of the tissue. These responses are controlled by several factors, such as micro-RNAs, that are transferred inside extracellular vesicles from mother cells to acceptor cells and are transductors of epigenetic signals. Finally, it is not a uniform opinion whether different phenotypes of heart failure are the result of altered cardiac and vascular reparation due to certain epigenetic responses, which are yielded by co-morbidities, such as diabetes mellitus and obesity. The aim of the review is to summarize knowledge regarding the role of various types of extracellular endothelial cell-derived vesicles in the regulation of cardiac and vascular remodeling in heart failure.

The influence of hyperglycemia on neutrophil extracellular trap formation and endothelial glycocalyx damage in a mouse model of type 2 diabetes

OBJECTIVES

Hyperglycemia induces vascular dysfunction that is thought to be initiated by neutrophils. Neutrophil activation produces endothelial injury by pathways that include NETosis, a type of specific cell death. In this study, we investigated the effects of hyperglycemia on neutrophil activation, cell death, NETosis, and endothelial glycocalyx damage using a mouse diabetes model.

METHODS

We used db/db mice as a type 2 diabetes model, and C57BL/6 mice were the controls. At 5, 8, and 12 weeks of age, the proportion of CD11b⁺ granulocytes/monocytes, neutrophil extracellular trap (NET)-forming granulocytes/monocytes, and damaged and nonviable granulocytes/monocytes was analyzed. In addition, serum levels of high mobility group box 1, histone H3, and glycocalyx components that included syndecan-1 and hyaluronan were measured.

RESULTS

In diabetic mice, we observed an increased proportion of CD11b⁺ granulocytes/monocytes. The proportion of NET-forming granulocytes/monocytes increased from the early stages of the experiments. The proportions of damaged and nonviable granulocytes/monocytes increased over time. In the 12-week-old diabetic mice, serum histone H3 levels increased. Circulating levels of syndecan-1 and hyaluronan decreased over time and were lower in diabetic mice.

CONCLUSION

Neutrophil activation and cell death induce endothelial glycocalyx damage, and NET formation also participates in the mechanisms of vascular injury in type 2 diabetes.

Activation of Factor XII and Kallikrein-Kinin System Combined with Neutrophil Extracellular Trap Formation in Diabetic Retinopathy

BACKGROUND

In diabetic retinopathy (DR), neutrophil extracellular traps (NET) and kallikrein-kinin system are considered as contributing factors. However, the detail activation mechanisms has not been fully understood. Since the NET could provide negative-charged surface for factor XII activation and the activated factor XII (XIIa) can initiate kallikrein-kinin system, this study investigated whether patients with DR show activation of NET, factor XII and kallikrein-kinin system.

METHODS

The markers related to NET (DNA-histone complex) and kallikrein-kinin system (high-molecular-weight kininogen, prekallikrein, bradykinin) and factor XIIa were measured in 253 patients with diabetes. To access ex vivo effect of glucose, DNA-histone complex and factor XIIa were measured in whole blood stimulated by glucose.

RESULTS

The circulating level of DNA-histone complex and factor XIIa were significantly higher in patients with DR than those without DR. In logistic regression analysis, DNA-histone complex, factor XIIa, and high-molecular-weight kininogen were the risk factors of DR. In recursive partitioning analysis, among patients with diabetes duration less than 10 years, patients with high level of DNA-histone complex (>426 AU) showed high risk of DR. In ex vivo experiment, glucose significantly elevated both DNA-histone complex and factor XIIa.

CONCLUSION

Our findings suggest that activation of factor XII and kallikrein-kinin system combined with NET formation actively occur in patients with DR and circulating levels of DNA-histone complex, factor XIIa and HMWK can be potential biomarkers to estimate the risk of DR. Strategies against factor XII activation may be beneficial to inhibit DR.

Proteomic analysis of peripheral blood polymorphonuclear cells (PBMCs) reveals alteration of neutrophil extracellular trap (NET) components in uncontrolled diabetes

Neutrophils have been thought to play a major role in inflammation and diabetic complications especially in poor glycemic control patients as demonstrated by their aberrant inflammatory markers. The aim of the present study was to compare neutrophil proteome profiles between diabetic patients with good glycemic control and those with poor glycemic control to see whether there might be any differences that could be related to the cause of complications which are found more commonly in the latter. Using 2-dimensional gel electrophoresis (2-DE) followed by quadrupole time of flight mass spectrometry (Q-TOF MS) and/or tandem mass spectrometry (MS/MS), we identified 35 differentially expressed proteins, some of which were protein components of neutrophil extracellular traps (NETs), in the poor glycemic control group compared to the good glycemic control group. The observed alterations of protein components of NETs included downregulation of myeloperoxidase, azurocidin (CAP37), and S100A9; and upregulation of the glycolytic enzymes transketolase and alpha-enolase. Manganese superoxide dismutase (MnSOD), functioning in cellular response and defense, was also found downregulated in the poor control group. Most of the glycolysis-related proteins were downregulated in the good control group but upregulated in the poor control group, including phosphoglycerate kinase 1 (PGK1) and L-lactate dehydrogenase B chain (LDHB). The findings of this study demonstrate the dysregulation of protein components of NETs in neutrophils in patients with poorly controlled diabetes. More specifically, these findings suggest association between NETs and inflammation in diabetes and provide further insights into the role of neutrophils in the complications of poorly controlled diabetes.