The P-selectin and PSGL-1 axis accelerates atherosclerosis via activation of dendritic cells by the TLR4 signaling pathway. Cell Death Dis. 2019;10:507. [PMID: 31263109 PMCID: PMC6602970 DOI: 10.1038/s41419-019-1736-5]

Current targeting strategies and advanced nanoplatforms for atherosclerosis therapy

Atherosclerosis is one of the major causes of death worldwide, and it is closely related to many cardiovascular diseases, such as stroke, myocardial infraction and angina. Although traditional surgical and pharmacological interventions can effectively retard or slow down the progression of atherosclerosis, it is very difficult to prevent or even reverse this disease. In recent years, with the rapid development of nanotechnology, various nanoagents have been designed and applied to different diseases including atherosclerosis. The unique atherosclerotic microenvironment with signature biological components allows nanoplatforms to distinguish atherosclerotic lesions from normal tissue and to approach plaques specifically. Based on the process of atherosclerotic plaque formation, this review summarises the nanodrug delivery strategies for atherosclerotic therapy, trying to provide help for researchers to understand the existing atherosclerosis management approaches as well as challenges and to reasonably design anti-atherosclerotic nanoplatforms.

Platelet-derived sTLT-1 is associated with platelet-mediated inflammation in coronary artery disease patients

The development of coronary artery disease (CAD) depends heavily on platelet activation, and inflammation plays a major role in all stages of atherosclerosis. Platelet-specific soluble triggering receptor expressed on myeloid cells like transcript 1 (sTLT-1) facilitate clot formation and have been linked to chronic inflammation. In this study, we explored the role of platelet-derived sTLT-1 in platelet-mediated inflammation in CAD patients. Plasma levels of sTLT-1 were measured using enzyme-linked immunosorbent assay in CAD patients (n = 163) and healthy controls (n = 99). Correlation analysis was performed to determine the circulatory sTLT-1 levels with platelet activation markers, immune cells, and inflammatory cytokines/chemokines. Increased plasma sTLT-1 levels were observed in CAD patients compared with those in healthy controls (p < 0.0001). A positive correlation was observed between sTLT-1 and platelet activation markers (P-selectin, PAC-1), CD14++ CD16- cells (classical monocytes), Natural killer T (NKT) cells, and platelet-immune cell aggregates with monocytes, neutrophils, dendritic cells, CD11c+ cells, and NKT cells. In contrast, a significant negative correlation was observed with CD8 cells. Furthermore, a significant positive correlation was observed between sTLT-1 and inflammatory markers (TNF-α, IL-1β, IL-2, IL-6, IL-12p70, IL-18, CXCL-12, and CCL-11). Logistic regression analysis identified sTLT-1 and triglycerides as predictors of CAD. Receiver operating characteristic curve (ROC) analysis showed that sTLT-1 had a higher sensitivity and specificity for predicting CAD. Our findings suggest that platelet activation induces the release of sTLT-1 into the circulation in CAD patients, which aggregates with immune cells and enhances inflammatory responses.

The effects of glycosylation modifications on monocyte recruitment and foam cell formation in atherosclerosis

The monocyte recruitment and foam cell formation have been intensively investigated in atherosclerosis. Nevertheless, as the study progressed, it was obvious that crucial molecules participated in the monocyte recruitment and the membrane proteins in macrophages exhibited substantial glycosylation modifications. These modifications can exert a significant influence on protein functions and may even impact the overall progression of diseases. This article provides a review of the effects of glycosylation modifications on monocyte recruitment and foam cell formation. By elaborating on these effects, we aim to understand the underlying mechanisms of atherogenesis further and to provide new insights into the future treatment of atherosclerosis.

Predictive biomarkers for the early detection and management of heart failure

Cardiovascular disease (CVD) is a serious public health concern whose incidence has been on a rise and is projected by the World Health Organization to be the leading global cause of mortality by 2030. Heart failure (HF) is a complicated syndrome resulting from various CVDs of heterogeneous etiologies and exhibits varying pathophysiology, including activation of inflammatory signaling cascade, apoptosis, fibrotic pathway, and neuro-humoral system, thereby leading to compromised cardiac function. During this process, several biomolecules involved in the onset and progression of HF are released into circulation. These circulating biomolecules could serve as unique biomarkers for the detection of subclinical changes and can be utilized for monitoring disease severity. Hence, it is imperative to identify these biomarkers to devise an early predictive strategy to stop the deterioration of cardiac function caused by these complex cellular events. Furthermore, measurement of multiple biomarkers allows clinicians to divide HF patients into sub-groups for treatment and management based on early health outcomes. The present article provides a comprehensive overview of current omics platform available for discovering biomarkers for HF management. Some of the existing and novel biomarkers for the early detection of HF with special reference to endothelial biology are also discussed.

Multiple exposures to low-dose ionizing radiation induced the initiation and progression of pro-atherosclerotic phenotypes in mice and vascular endothelial cell damage

OBJECTIVE

This study aimed to investigate the effects of low-dose radiation on the abdominal aorta of mice and vascular endothelial cells.

METHODS

Wild-type and tumor-bearing mice were exposed to 15 sessions of low-dose irradiation, resulting in cumulative radiation doses of 187.5, 375, and 750 mGy. The effect on the cardiovascular system was assessed. Immunohistochemistry analyzed protein expressions of PAPP-A, CD62, P65, and COX-2 in the abdominal aorta. Microarray technology, Gene Ontology analysis, and pathway enrichment analysis evaluated gene expression changes in endothelial cells exposed to 375 mGy X-ray. Cell viability was assessed using the Cell Counting Kit 8 assay. Immunofluorescence staining measured γ-H2AX levels, and real-time polymerase chain reaction quantified mRNA levels of interleukin-6 (IL-6), ICAM-1, and Cx43.

RESULTS

Hematoxylin and eosin staining revealed thickening of the inner membranes and irregular arrangement of smooth muscle cells in the media membrane at 375 and 750 mGy. Inflammation was observed in the inner membranes at 750 mGy, with a clear inflammatory response in the hearts of tumor-bearing mice. Immunohistochemistry indicated increased levels of PAPP-A, P65, and COX-2 post-irradiation. Microarray analysis showed 425 up-regulated and 235 down-regulated genes, associated with processes like endothelial cell-cell adhesion, IL-6, and NF-κB signaling. Cell Counting Kit 8 assay results indicated inhibited viability at 750 mGy in EA.hy926 cells. Immunofluorescence staining demonstrated a dose-dependent increase in γ-H2AX foci. Reverse transcription quantitative PCR results showed increased expression of IL6, ICAM-1, and Cx43 in EA.hy926 cells post 750 mGy X-ray exposure.

CONCLUSION

Repeated low-dose ionizing radiation exposures triggered the development of pro-atherosclerotic phenotypes in mice and damage to vascular endothelial cells.

Quercetin inhibits the activity and function of dendritic cells through the TLR4/IRAK4/NF-κB signalling pathway

Introduction

To investigate the inhibitory effect of quercetin (QUE) on dendritic cells (DCs) through the toll-like receptor 4/interleukin-1 receptor-associated kinase 4/nuclear factor kappa-B (TLR4/IRAK4/NF-κB) signalling pathway.

Material and methods

CCK-8 and apoptosis assays were performed to determine the optimal concentration and action time of QUE to inhibit DCs. Protein extracts from treated DCs were used for Western blotting experiments to determine the relative expression levels of TLR4, IRAK4, and NF-κB p65 proteins. Changes in the ratio of CD86 and CD11c positive cells on the DCs surface were detected using flow cytometry. The molecular docking technique was used to analyse the binding site and free energy of QUE and IRAK4.

Results

CCK-8 and apoptosis assays suggested that QUE inhibited the activity and function of DCs in a time-dose-dependent manner. The results of Western blotting suggested that the relative expression levels of TLR4, IRAK4, and NF-κB p65 proteins were increased in the lipopolysaccharide (LPS) group compared with the normal control group, and the relative expression of the above proteins was decreased after treatment with QUE and IRAK4-IN-4. The results of flow cytometry suggested that LPS increased the expression of CD86 and CD11c on the surface of DCs, and QUE and IRAK4-IN-4 decreased the expression of CD86 and CD11c induced by LPS. Molecular docking results showed that the binding sites of QUE and IRAK4 were stable, with the minimum binding energies comparable to that of IRAK4-IN-4.

Conclusions

Quercetin may inhibit the activity and function of DCs through the TLR4/IRAK4/NF-κB signalling pathway, and IRAK4 may be its target.

Inflammatory and Prothrombotic Biomarkers Contribute to the Persistence of Sequelae in Recovered COVID-19 Patients

The presence of long COVID (LC) following SARS-CoV-2 infection is a common condition that affects the quality of life of patients and represents a diagnostic challenge due to the diversity of symptoms that may coexist. We still do not have accurate information regarding the pathophysiological pathways that generate the presence of LC, and so it is important to know the inflammatory and immunothrombotic biomarker profiles and their implications in order to characterize risk subgroups and establish early therapeutic strategies. We performed the determination of inflammatory and immunothrombotic biomarkers in volunteers with previous diagnoses of SARS-CoV-2. The inflammatory biomarkers were analyzed in plasma by flow cytometry, and we analyzed the von Willebrand factor (vWF) in the plasma samples using ELISA. The clinical variables and the presence or absence of long COVID symptoms were then analyzed. IL-6, sCD40L, p-Selectin, PSGL-1, PAI-1, tPA, D-Dimer, TF, and Factor IX levels were elevated in the groups with LC, especially in the subgroup of patients with metabolic syndrome (MetS). VWF levels were found to be increased in patients with sequelae and MetS. Our results confirmed the persistence of an active immunothrombotic state, and so it is important to identify the population at risk in order to provide adequate clinical follow-up.

Tolerogenic dendritic cells and TLR4/IRAK4/NF-κB signaling pathway in allergic rhinitis

Dendritic cells (DCs), central participants in the allergic immune response, can capture and present allergens leading to allergic inflammation in the immunopathogenesis of allergic rhinitis (AR). In addition to initiating antigen-specific immune responses, DCs induce tolerance and modulate immune homeostasis. As a special type of DCs, tolerogenic DCs (tolDCs) achieve immune tolerance mainly by suppressing effector T cell responses and inducing regulatory T cells (Tregs). TolDCs suppress allergic inflammation by modulating immune tolerance, thereby reducing symptoms of AR. Activation of the TLR4/IRAK4/NF-κB signaling pathway contributes to the release of inflammatory cytokines, and inhibitors of this signaling pathway induce the production of tolDCs to alleviate allergic inflammatory responses. This review focuses on the relationship between tolDCs and TLR4/IRAK4/NF-κB signaling pathway with AR.

Pro-inflammation and pro-atherosclerotic responses to short-term air pollution exposure associated with alterations in sphingolipid ceramides and neutrophil extracellular traps

Air pollution has been associated with the development of atherosclerosis; however, the pathophysiological mechanisms underlying pro-atherosclerotic effects of air pollution exposure remain unclear. We conducted a prospective panel study in Beijing and recruited 152 participants with four monthly visits from September 2019 to January 2020. Linear mixed-effect models were applied to estimate the associations linking short-term air pollution exposure to biomarkers relevant to ceramide metabolism, pro-inflammation (neutrophil extracellular traps formation and systemic inflammation) and pro-atherosclerotic responses (endothelial stimulation, plaque instability, coagulation activation, and elevated blood pressure). We further explored whether ceramides and inflammatory indicators could mediate the alterations in the profiles of pro-atherosclerotic responses. We found that significant increases in levels of circulating ceramides of 9.7% (95% CIs: 0.7, 19.5) to 96.9% (95% CIs: 23.1, 214.9) were associated with interquartile range increases in moving averages of ambient air pollutant metrics, including fine particulate matter (PM2.5), black carbon, particles in size fractions of 100-560 nm, nitrogen dioxide, carbon monoxide and sulfur dioxide at prior up to 7 days. Higher air pollution levels were also associated with activated neutrophils (increases in citrullinated histone H3, neutrophil elastase, double-stranded DNA, and myeloperoxidase) and exacerbation of pro-atherosclerotic responses (e.g., increases in vascular endothelial growth factor, lipoprotein-associated phospholipase A2, matrix metalloproteinase-8, P-selectin, and blood pressure). Mediation analyses further showed that dysregulated ceramide metabolism and potentiated inflammation could mediate PM2.5-associated pro-atherosclerotic responses. Our findings extend the understanding on potential mechanisms of air pollution-associated atherosclerosis, and suggest the significance of reducing air pollution as priority in urban environments.

Plasma protein signatures for high on-treatment platelet reactivity to aspirin and clopidogrel in peripheral artery disease

BACKGROUND

A significant proportion of patients with peripheral artery disease (PAD) displays a poor response to aspirin and/or the platelet P2Y12 receptor antagonist clopidogrel. This phenomenon is reflected by high on-treatment platelet reactivity (HTPR) in platelet function assays in vitro and is associated with an increased risk of adverse cardiovascular events.

OBJECTIVE

This study aimed to elucidate specific plasma protein signatures associated with HTPR to aspirin and clopidogrel in PAD patients.

METHODS AND RESULTS

Based on targeted plasma proteomics, 184 proteins from two cardiovascular Olink panels were measured in 105 PAD patients. VerifyNow ASPI- and P2Y12-test values were transformed to a continuous variable representing HTPR as a spectrum instead of cut-off level-defined HTPR. Using the Boruta random forest algorithm, the importance of 3 plasma proteins for HTPR in the aspirin, six in clopidogrel and 10 in the pooled group (clopidogrel or aspirin) was confirmed. Network analysis demonstrated clusters with CD84, SLAMF7, IL1RN and THBD for clopidogrel and with F2R, SELPLG, HAVCR1, THBD, PECAM1, TNFRSF10B, MERTK and ADM for the pooled group. F2R, TNFRSF10B and ADM were higher expressed in Fontaine III patients compared to Fontaine II, suggesting their relation with PAD severity.

CONCLUSIONS

A plasma protein signature, including eight targets involved in proatherogenic dysfunction of blood cell-vasculature interaction, coagulation and cell death, is associated with HTPR (aspirin and/or clopidogrel) in PAD. This may serve as important systems-based determinants of poor platelet responsiveness to aspirin and/or clopidogrel in PAD and other cardiovascular diseases and may contribute to identify novel treatment strategies.

Platelet-monocyte aggregates: molecular mediators of thromboinflammation

Platelets, key facilitators of primary hemostasis and thrombosis, have emerged as crucial cellular mediators of innate immunity and inflammation. Exemplified by their ability to alter the phenotype and function of monocytes, activated platelets bind to circulating monocytes to form monocyte-platelet aggregates (MPA). The platelet-monocyte axis has emerged as a key mechanism connecting thrombosis and inflammation. MPA are elevated across the spectrum of inflammatory and autoimmune disorders, including cardiovascular disease, systemic lupus erythematosus (SLE), and COVID-19, and are positively associated with disease severity. These clinical disorders are all characterized by an increased risk of thromboembolic complications. Intriguingly, monocytes in contact with platelets become proinflammatory and procoagulant, highlighting that this interaction is a central element of thromboinflammation.

The role of protein glycosylation in the occurrence and outcome of acute ischemic stroke

Acute ischemic stroke (AIS) is a serious and life-threatening disease worldwide. Despite thrombolysis or endovascular thrombectomy, a sizeable fraction of patients with AIS have adverse clinical outcomes. In addition, existing secondary prevention strategies with antiplatelet and anticoagulant drugs therapy are not able to adequately decrease the risk of ischemic stroke recurrence. Thus, exploring novel mechanisms for doing so represents an urgent need for the prevention and treatment of AIS. Recent studies have discovered that protein glycosylation plays a critical role in the occurrence and outcome of AIS. As a common co- and post-translational modification, protein glycosylation participates in a wide variety of physiological and pathological processes by regulating the activity and function of proteins or enzymes. Protein glycosylation is involved in two causes of cerebral emboli in ischemic stroke: atherosclerosis and atrial fibrillation. Following ischemic stroke, the level of brain protein glycosylation becomes dynamically regulated, which significantly affects stroke outcome through influencing inflammatory response, excitotoxicity, neuronal apoptosis, and blood-brain barrier disruption. Drugs targeting glycosylation in the occurrence and progression of stroke may represent a novel therapeutic idea. In this review, we focus on possible perspectives about how glycosylation affects the occurrence and outcome of AIS. We then propose the potential of glycosylation as a therapeutic drug target and prognostic marker for AIS patients in the future.

Discovery of four plasmatic biomarkers potentially predicting cardiovascular outcome in peripheral artery disease

Peripheral artery disease (PAD) patients have an increased cardiovascular risk despite pharmacological treatment strategies. Biomarker research improving risk stratification only focused on known atherothrombotic pathways, but unexplored pathways might play more important roles. To explore the association between a broad cardiovascular biomarker set and cardiovascular risk in PAD. 120 PAD outpatients were enrolled in this observational cohort study. Patients were followed for one year in which the composite endpoint (myocardial infarction, coronary revascularization, stroke, acute limb ischemia and mortality) was assessed. Patient data and blood samples were collected upon inclusion, and citrated platelet-poor plasma was used to analyze 184 biomarkers in Olink Cardiovascular panel II and III using a proximity extension assay. Fifteen patients reached the composite endpoint. These patients had more prior strokes and higher serum creatinine levels. Multivariate analysis revealed increased plasma levels of protease-activated receptor 1 (PAR1), galectin-9 (Gal-9), tumor necrosis factor receptor superfamily member 11A (TNFRSF11A) and interleukin 6 (IL-6) to be most predictive for cardiovascular events and mortality. Positive regulation of acute inflammatory responses and leukocyte chemotaxis were identified as involved biological processes. This study identified IL-6, PAR1, Gal-9, TNFRSF11A as potent predictors for cardiovascular events and mortality in PAD, and potential drug development targets.

Genistein promotes M1 macrophage apoptosis and reduces inflammatory response by disrupting miR-21/TIPE2 pathway

Cardiovascular diseases are a major cause of mortality, and vascular injury, a common pathological basis of cardiovascular disease, is deeply correlated with macrophage apoptosis and inflammatory response. Genistein, a type of phytoestrogen, exerts cardiovascular protective activities, but the underlying mechanism has not been fully elucidated. In this study, RAW264.7 cells were treated with genistein, lipopolysaccharide (LPS), nuclear factor-kappa B (NF-κB) inhibitor, and/or protein kinase B (AKT) agonist to determine the role of genistein in apoptosis and inflammation in LPS-stimulated cells. Simultaneously, high fat diet-fed C57BL/6 mice were administered genistein to evaluate the function of genistein on LPS-induced cardiovascular injury mouse model. Here, we demonstrated that LPS obviously increased apoptosis resistance and inflammatory response of macrophages by promoting miR-21 expression, and miR-21 downregulated tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) expression by targeting the coding region. Genistein reduced miR-21 expression by inhibiting NF-κB, then blocked toll-like receptor 4 (TLR4) pathway and AKT phosphorylation dependent on TIPE2, resulting in inhibition of LPS. Our research suggests that miR-21/TIPE2 pathway is involved in M1 macrophage apoptosis and inflammatory response, and genistein inhibits the progression of LPS-induced cardiovascular injury at the epigenetic level via regulating the promoter region of Vmp1 by NF-κB.

GALNT4 primes monocytes adhesion and transmigration by regulating O-Glycosylation of PSGL-1 in atherosclerosis

Atherosclerosis is a major underlying cause of cardiovascular disease. Genome wide association studies have predicted that GalNAc-T4 (GALNT4), which responsible for initiating step of mucin-type O-glycosylation, plays a causal role in the susceptibility to cardiovascular diseases, whereas the precise mechanism remains obscure. Thus, we sought to determine the role and mechanism of GALNT4 in atherosclerosis. Firstly, we found the expression of GALNT4 and protein O-glycosylation were both increased in plaque as atherosclerosis progressed in ApoE-/- mice by immunohistochemistry. And the expression of GALNT4 was also increased in human monocytes treated with ACS (acute coronary syndrome) sera and subjected to LPS and ox-LDL in vitro. Moreover, silencing expression of GALNT4 by shRNA lentivirus alleviated atherosclerotic plaque formation and monocyte/macrophage infiltration in ApoE-/- mice. Functional investigations demonstrate that GALNT4 knockdown inhibited P-selectin-induced activation of β2 integrin on the surface of monocytes, decreased monocytes adhesion under flow condition with P-selectin stimulation, as well as suppressed monocytes transmigration triggered by monocyte chemotactic protein- 1(MCP-1). In contrast, GALNT4 overexpression enhanced monocytes adhesion and transmigration. Furthermore, Vicia Villosa Lectin (VVL) pull down and PSGL-1 immunoprecipitation assays showed that GALNT4 overexpression increased O-Glycosylation of PSGL-1 and P-selectin induce phosphorylation of Akt/mTOR and IκBα/NFκB on monocytes. Conversely, knockdown of GALNT4 decreased VVL binding and attenuated the activation of Akt/mTOR and IκBα/NFκB. Additionally, mTOR inhibitor rapamycin blocked these effects of GALNT4 overexpression on monocytes. Collectively, GALNT4 catalyzed PSGL-1 O-glycosylation that involved in P-selectin induced monocytes adhesion and transmigration via Akt/mTOR and NFκB pathway. Thus, GALNT4 may be a potential therapeutic target for atherosclerosis.

New Insights of CCR7 Signaling in Dendritic Cell Migration and Inflammatory Diseases

CCR7, collaborated with its ligands CCL19 and CCL21, controls extensive migratory events in the immune system. CCR7-bearing dendritic cells can swarm into T-cell zones in lymph nodes, initiating the antigen presentation and T-cell response. Abnormal expression of CCR7 in dendritic cells will cause a series of inflammatory diseases due to the chaotic dendritic cell trafficking. In this review, we take an in-depth look at the structural–functional domains of CCR7 and CCR7-bearing dendritic cell trajectory to lymph nodes. Then, we summarize the regulatory network of CCR7, including transcriptional regulation, translational and posttranslational regulation, internalization, desensitization, and recycling. Furthermore, the potential strategies of targeting the CCR7 network to regulate dendritic cell migration and to deal with inflammatory diseases are integrated, which not only emphasizes the possibility of CCR7 to be a potential target of immunotherapy but also has an implication on the homing of dendritic cells to benefit inflammatory diseases.

Endocan: A Key Player of Cardiovascular Disease

Endothelial dysfunction is considered to be an early change in atherosclerosis. Endocan, also known as endothelial cell specific molecule-1, is a soluble proteoglycan mainly secreted by endothelial cells. Inflammatory factors such as IL-1β and TNF-α can up regulate the expression of endocan and then affect the expression of cell adhesion molecules, such as ICAM-1 and VCAM-1, which play an important role in promoting leukocyte migration and inflammatory response. Elevated plasma levels of endocan may reflect endothelial activation and dysfunction, and is considered to be a potential immuno-inflammatory marker that may be related to cardiovascular disease. In the case of hypertension, diabetes, angina pectoris and acute myocardial infarction, the increase or decrease of serum endocan levels is of great significance. Here, we reviewed the current research on endocan, and emphasis its possible clinical value as a prognostic marker of cardiovascular disease. Endocan may be a useful biomarker for the prognosis of cardiovascular disease, but more research is needed on its mechanism of action.

[Patterns of immunological reactions in the pathogenesis of chronic heart failure: review]

The immune system is essential for maintaining the homeostasis. At present, there is convincing evidence for participation of the immune system in the pathogenesis of cardiovascular pathology, including the final step of cardiovascular continuum, heart failure. Objective difficulties in understanding subtle processes of loss of the normal cardiac structure and function are based on the diversity of pathogenetic factors of development and progression of chronic heart failure (CHF) and the involvement of most organs and body systems. Russian and international scientists actively study issues of immune homeostasis, including the efficacy of current immune therapy. At the same time, available reports are largely uncompiled and reflect isolated parts of the immunopathogenesis of cardiovascular diseases. This review focuses on comprehensive elucidation of major patterns of immune processes in the CHF pathogenesis to form an integral view of the problem under study.

Role of GALNT4 in protecting against cardiac hypertrophy through ASK1 signaling pathway

Pathological myocardial hypertrophy is regulated by multiple pathways. However, its underlying pathogenesis has not been fully explored. The goal of this work was to elucidate the function of polypeptide N-acetylgalactosaminyltransferase 4 (GALNT4) in myocardial hypertrophy and its underlying mechanism of action. We illustrated that GALNT4 was upregulated in the models of hypertrophy. Two cardiac hypertrophy models were established through partial transection of the aorta in GALNT4-knockout (GALNT4-KO) mice and adeno-associated virus 9-GALNT4 (AAV9-GALNT4) mice. The GALNT4-KO mice demonstrated accelerated cardiac hypertrophy, dysfunction, and fibrosis, whereas the opposite phenotype was observed in AAV9-GALNT4 mice. Similarly, GALNT4 overexpression mitigated the degree of phenylephrine-induced cardiomyocyte hypertrophy in vitro whereas GALNT4 knockdown aggravated the hypertrophy. In terms of mechanism, GALNT4 deficiency increased the phosphorylation and activation of ASK1 and its downstream targets (JNK and p38), whereas GALNT4 overexpression inhibited activation of the ASK1 pathway. Furthermore, we demonstrated that GALNT4 can directly bind to ASK1 inhibiting its N-terminally mediated dimerization and the subsequent phosphorylation of ASK1. Finally, an ASK1 inhibitor (iASK1) was able to reverse the effects of GALNT4 in vitro. In summary, GALNT4 may serve as a new regulatory factor and therapeutic target by blocking the activation of the ASK1 signaling cascade.

Donor BMSC-derived small extracellular vesicles relieve acute rejection post-renal allograft through transmitting Loc108349490 to dendritic cells

Bone marrow-derived mesenchymal stem cell (BMSC)-derived small extracellular vesicles (sEVs) are potent candidates for the suppression of acute rejection post-renal allograft and have been reported to halt dendritic cells (DCs) maturation. However, whether BMSC-derived sEVs mitigate acute rejection post-renal allograft by targeting DCs is still unclear. In this study, donor BMSC-derived sEVs (sEVs) relieved the inflammatory response and suppressed mature DCs (mDCs) location in kidney grafts, and increased regulatory T (Treg) cell population in the spleens of the rats that underwent kidney allograft. In lipopolysaccharide (LPS)-stimulated immature DCs (imDCs), sEVs suppressed the maturation and migration of DCs and inactivated toll-like receptor 4 (TLR4) signaling. Compared with LPS-treated imDCs, imDCs treated with LPS+sEVs promoted CD4+ T cells differentiated toward Treg cells. Subsequently, we found that Loc108349490, a long non-coding RNA (lncRNA) abundant in sEVs, mediated the inhibitory effect of sEVs on DC maturation and migration by promoting TLR4 ubiquitination. In rats that underwent an allograft, Loc108349490 deficiency weakened the therapeutic effect of sEVs on acute rejection. The present study firstly found that sEVs alleviated acute rejection post-renal allograft by transferring lncRNA to DCs and screened out the functional lncRNA loaded in sEVs was Loc108349490.

Biomaterial and cellular implants:foreign surfaces where immunity and coagulation meet

Exposure of blood to a foreign surface in the form of a diagnostic or therapeutic biomaterial device or implanted cells or tissues, elicits an immediate, evolutionarily conserved thrombo-inflammatory response by the host. Primarily designed to protect against invading organisms following an injury, this innate response features instantaneous activation of several blood-borne, highly interactive and well-orchestrated cascades and cellular events that limit bleeding, destroy and eliminate the foreign substance/cells, and promote healing and a return to homeostasis via delicately balanced regenerative processes. In the setting of blood-contacting synthetic or natural biomaterials and implantation of foreign cells/tissues, innate responses are robust, albeit highly context-specific. Unfortunately, they tend to be less than adequately regulated by the host's natural anti-coagulant/anti-inflammatory pathways, thereby jeopardizing the functional integrity of the device, as well as the health of the host. Strategies to achieve biocompatibility with a sustained return to homeostasis, particularly while the device remains in situ and functional, continue to elude scientists and clinicians. In this review, some of the complex mechanisms by which biomaterials and cellular transplants provide a "hub" for activation and amplification of coagulation and immunity - thrombo-inflammation - will be discussed, with a view toward the development of innovative means of overcoming the innate challenges.

Platelet Phagocytosis via P-selectin Glycoprotein Ligand 1 and Accumulation of Microparticles in Systemic Sclerosis

OBJECTIVE

It is unclear why activated platelets and platelet-derived microparticles (MPs) accumulate in the blood of patients with systemic sclerosis (SSc). This study was undertaken to investigate whether defective phagocytosis might contribute to MP accumulation in the blood of patients with SSc.

METHODS

Blood samples were obtained from a total of 81 subjects, including 25 patients with SSc and 26 patients with stable coronary artery disease (CAD). Thirty sex- and age-matched healthy volunteers served as controls. Studies were also conducted in NSG mice, in which the tail vein of the mice was injected with MPs, and samples of the lung parenchyma were obtained for analysis of the pulmonary microvasculature. Tissue samples from human subjects and from mice were assessed by flow cytometry and immunochemical analyses for determination of platelet-neutrophil interactions, phagocytosis, levels and distribution of P-selectin, P-selectin glycoprotein ligand 1 (PSGL-1), and HMGB1 on platelets and MPs, and concentration of byproducts of neutrophil extracellular trap (NET) generation/catabolism.

RESULTS

Activated P-selectin+ platelets and platelet-derived HMGB1+ MPs accumulated in the blood of SSc patients but not in the blood of healthy controls. Patients with CAD, a vasculopathy independent of systemic inflammation, had fewer P-selectin+ platelets and a negligible number of MPs. The expression of the receptor for P-selectin, PSGL-1, in neutrophils from SSc patients was significantly decreased, raising the possibility that phagocytes in SSc do not recognize activated platelets, leading to a failure of phagocytosis and continued neutrophil release of MPs. As evidence of this process, activated platelets were not detected in the neutrophils from SSc patients, whereas they were consistently present in the neutrophils from patients with CAD. HMGB1+ MPs elicited generation of NETs, which were only detected in the plasma of SSc patients. In mice, P-selectin-PSGL-1 interaction resulted in platelet phagocytosis in vitro and influenced the ability of MPs to elicit NETs, endothelial activation, and migration of leukocytes through the pulmonary microvasculature.

CONCLUSION

The clearance of activated platelets via PSGL-1 limits the undesirable effects of MP-elicited neutrophil activation. This balance is disrupted in patients with SSc. Its reconstitution might curb vascular inflammation and prevent fibrosis.

CLEC-2 Prevents Accumulation and Retention of Inflammatory Macrophages During Murine Peritonitis

Platelets play a key role in the development, progression and resolution of the inflammatory response during sterile inflammation and infection, although the mechanism is not well understood. Here we show that platelet CLEC-2 reduces tissue inflammation by regulating inflammatory macrophage activation and trafficking from the inflamed tissues. The immune regulatory function of CLEC-2 depends on the expression of its ligand, podoplanin, upregulated on inflammatory macrophages and is independent of platelet activation and secretion. Mechanistically, platelet CLEC-2 and also recombinant CLEC-2-Fc accelerates actin rearrangement and macrophage migration by increasing the expression of podoplanin and CD44, and their interaction with the ERM proteins. During ongoing inflammation, induced by lipopolysaccharide, treatment with rCLEC-2-Fc induces the rapid emigration of peritoneal inflammatory macrophages to mesenteric lymph nodes, thus reducing the accumulation of inflammatory macrophages in the inflamed peritoneum. This is associated with a significant decrease in pro-inflammatory cytokine, TNF-α and an increase in levels of immunosuppressive, IL-10 in the peritoneum. Increased podoplanin expression and actin remodelling favour macrophage migration towards CCL21, a soluble ligand for podoplanin and chemoattractant secreted by lymph node lymphatic endothelial cells. Macrophage efflux to draining lymph nodes induces T cell priming. In conclusion, we show that platelet CLEC-2 reduces the inflammatory phenotype of macrophages and their accumulation, leading to diminished tissue inflammation. These immunomodulatory functions of CLEC-2 are a novel strategy to reduce tissue inflammation and could be therapeutically exploited through rCLEC-2-Fc, to limit the progression to chronic inflammation.

Biological drug and drug delivery-mediated immunotherapy

The initiation and development of major inflammatory diseases, i.e., cancer, vascular inflammation, and some autoimmune diseases are closely linked to the immune system. Biologics-based immunotherapy is exerting a critical role against these diseases, whereas the usage of the immunomodulators is always limited by various factors such as susceptibility to digestion by enzymes in vivo, poor penetration across biological barriers, and rapid clearance by the reticuloendothelial system. Drug delivery strategies are potent to promote their delivery. Herein, we reviewed the potential targets for immunotherapy against the major inflammatory diseases, discussed the biologics and drug delivery systems involved in the immunotherapy, particularly highlighted the approved therapy tactics, and finally offer perspectives in this field.

Glycans and Glycan-Binding Proteins as Regulators and Potential Targets in Leukocyte Recruitment

Leukocyte recruitment is a highly controlled cascade of interactions between proteins expressed by the endothelium and circulating leukocytes. The involvement of glycans and glycan-binding proteins in the leukocyte recruitment cascade has been well-characterised. However, our understanding of these interactions and their regulation has expanded substantially in recent years to include novel lectins and regulatory pathways. In this review, we discuss the role of glycans and glycan-binding proteins, mediating the interactions between endothelium and leukocytes both directly and indirectly. We also highlight recent findings of key enzymes involved in glycosylation which affect leukocyte recruitment. Finally, we investigate the potential of glycans and glycan binding proteins as therapeutic targets to modulate leukocyte recruitment and transmigration in inflammation.

Targeting Platelet in Atherosclerosis Plaque Formation: Current Knowledge and Future Perspectives

Besides their role in hemostasis and thrombosis, it has become increasingly clear that platelets are also involved in many other pathological processes of the vascular system, such as atherosclerotic plaque formation. Atherosclerosis is a chronic vascular inflammatory disease, which preferentially develops at sites under disturbed blood flow with low speeds and chaotic directions. Hyperglycemia, hyperlipidemia, and hypertension are all risk factors for atherosclerosis. When the vascular microenvironment changes, platelets can respond quickly to interact with endothelial cells and leukocytes, participating in atherosclerosis. This review discusses the important roles of platelets in the plaque formation under pro-atherogenic factors. Specifically, we discussed the platelet behaviors under disturbed flow, hyperglycemia, and hyperlipidemia conditions. We also summarized the molecular mechanisms involved in vascular inflammation during atherogenesis based on platelet receptors and secretion of inflammatory factors. Finally, we highlighted the studies of platelet migration in atherogenesis. In general, we elaborated an atherogenic role of platelets and the aspects that should be further studied in the future.

P-selectin glycoprotein ligand 1 deficiency prevents development of acute pancreatitis by attenuating leukocyte infiltration

BACKGROUND

Acute pancreatitis (AP) is rapid-onset pancreatic inflammation that causes local and systemic inflammatory response syndrome (SIRS) with high morbidity and mortality, but no approved therapies are currently available. P-selectin glycoprotein ligand 1 (PSGL-1) is a transmembrane glycoprotein to initiate inflammatory responses. We hypothesized that PSGL-1 may be involved in the development of AP and would be a new target for the treatment of AP.

AIM

To investigate the role and mechanism of PSGL-1 in the development of AP.

METHODS

The PSGL-1 expression on leukocytes was detected in peripheral blood of AP patients and volunteers. Pancreatic injury, inflammatory cytokines expression, and inflammatory cell infiltration was measured in AP mouse models induced with PSGL-1 knockout (PSGL-1^-/-) and wild-type (PSGL-1^+/+) mice. Leukocyte-endothelial cell adhesion was measured in a peripheral blood mononuclear cell (PBMC)-endothelial cell coculture system.

RESULTS

The expression of PSGL-1 on monocytes and neutrophils was significantly increased in AP patients. Compared with PSGL-1^+/+ mice, PSGL-1^-/- AP mice induced by caerulein exhibited lower serum amylase, less Interleukin-1beta (IL-1beta) and Interleukin-6 (IL-6) expression, less neutrophil and macrophage infiltration, and reduced peripheral neutrophil and monocyte accounts. PSGL-1 deficiency alleviated leukocyte-endothelial cell adhesion via IL-6 but not IL-1beta.

CONCLUSION

PSGL-1 deficiency effectively inhibits the development of AP by preventing leukocyte-endothelial cell adhesion via IL-6 stimulation and may become a potential therapeutic target for treating AP.

Platelets and Complement Cross-Talk in Early Atherogenesis

Atherosclerosis remains a ubiquitous and serious threat to human health. The initial formation of the atherosclerotic lesion (atheroma) is driven by pro-inflammatory signaling involving monocytes and vascular endothelial cells; later stages of the disease involve rupture of well-established atherosclerotic plaques, thrombosis, and blood vessel occlusion. While the central role of platelets in thrombosis is undisputed, platelets exhibit pro-inflammatory activities, and contribute to early-stage atheroma formation. Platelets also engage components of the complement system, an essential element of innate immunity that contributes to vascular inflammation. Here we provide an overview of the complex interplay between platelets and the complement system, with a focus on how the crosstalk between them may impact on the initiation of atheroma formation.

Immune-Mediated Inflammation in Vulnerable Atherosclerotic Plaques

Atherosclerosis is a chronic long-lasting vascular disease leading to myocardial infarction and stroke. Vulnerable atherosclerotic (AS) plaques are responsible for these life-threatening clinical endpoints. To more successfully work against atherosclerosis, improvements in early diagnosis and treatment of AS plaque lesions are required. Vulnerable AS plaques are frequently undetectable by conventional imaging because they are non-stenotic. Although blood biomarkers like lipids, C-reactive protein, interleukin-6, troponins, and natriuretic peptides are in pathological ranges, these markers are insufficient in detecting the critical perpetuation of AS anteceding endpoints. Thus, chances to treat the patient in a preventive way are wasted. It is now time to solve this dilemma because clear results indicate a benefit of anti-inflammatory therapy per se without modification of blood lipids (CANTOS Trial, NCT01327846). This fact identifies modulation of immune-mediated inflammation as a new promising point of action for the eradication of fatal atherosclerotic endpoints.