CD40L and Its Receptors in Atherothrombosis-An Update

Impact of statin therapy on CD40:CD40L signaling: mechanistic insights and therapeutic opportunities

Statins are widely utilized to reduce cholesterol levels, particularly in cardiovascular diseases. They interface with cholesterol synthesis by inhibiting the 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase enzyme. Besides their primary effect, statins demonstrate anti-inflammatory and immune-modulating properties in various diseases, highlighting the pleiotropic effect of these drugs. The CD40:CD40L signaling pathway is considered a prominent inflammatory pathway in multiple diseases, including autoimmune, inflammatory, and cardiovascular diseases. The findings from clinical trials and in vitro and in vivo studies suggest the potential anti-inflammatory effect of statins in modulating the CD40 signaling pathway and downstream inflammatory mediator. Accordingly, as its classic ligand, statins can suppress immune responses in autoimmune diseases by inhibiting CD40 expression and blocking its interaction with CD40L. Additionally, statins affect intracellular signaling and inhibit inflammatory mediator secretion in chronic inflammatory diseases like asthma and autoimmune disorders such as myasthenia gravis, multiple sclerosis, systemic lupus erymanthus, and cardiovascular diseases like atherosclerosis. However, it is essential to note that the anti-inflammatory effect of statins may vary depending on the specific type of statin used. In this study, we aim to explore the potential anti-inflammatory effects of statins in treating inflammatory diseases by examining their role in regulating immune responses, particularly their impact on the CD40:CD40L signaling pathway, through a comprehensive review of existing literature.

The Role of Platelet-Neutrophil Interactions in Driving Autoimmune Diseases

Platelets and neutrophils are among the most abundant cell types in peripheral blood. Beyond their traditional roles in thrombosis and haemostasis, they also play an active role in modulating immune responses. Current knowledge on the role of platelet-neutrophil interactions in the immune system has been rapidly expanding. Notably, circulating platelet-neutrophil complexes (PNCs) have been widely detected in various inflammatory diseases and infections, closely associated with inflammatory processes affecting multiple organs. These findings emphasise the critical role of platelet-neutrophil interactions in driving and sustaining inflammatory responses. In this review, we elucidate the mechanisms by which neutrophils and platelets physically interact, leading to mutual activation. Additionally, activated platelets release pro-inflammatory factors that further modulate neutrophil effector functions, enhancing their immune response capabilities. We highlight the role of platelets in promoting the formation of neutrophil extracellular traps (NETs), which, in turn, promote local platelet activation, thereby exacerbating the immune response and sustaining chronic inflammation. Furthermore, we review current evidence on the role of platelet-neutrophil interactions in common autoimmune diseases such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and rheumatoid arthritis (RA). Finally, we identify gaps in understanding the mechanisms of these interactions in the context of other autoimmune diseases and underscore the potential of targeting platelets and neutrophils as a therapeutic strategy for these conditions.

Systemic lupus erythematosus: pathogenesis and targeted therapy

Systemic lupus erythematosus (SLE) is a multifaceted autoimmune disorder characterized by dysregulated immune responses and autoantibody production, which affects multiple organs and varies in clinical presentation and disease severity. The development of SLE is intricate, encompassing dysregulation within the immune system, a collapse of immunological tolerance, genetic susceptibilities to the disease, and a variety of environmental factors that can act as triggers. This review provides a comprehensive discussion of the pathogenesis and treatment strategies of SLE and focuses on the progress and status of traditional and emerging treatment strategies for SLE. Traditional treatment strategies for SLE have mainly employed non-specific approaches, including cytotoxic and immunosuppressive drugs, antimalarials, glucocorticoids, and NSAIDs. These strategies are effective in mitigating the effects of the disease, but they are not a complete cure and are often accompanied by adverse reactions. Emerging targeted therapeutic drugs, on the other hand, aim to control and treat SLE by targeting B and T cells, inhibiting their activation and function, as well as the abnormal activation of the immune system. A deeper understanding of the pathogenesis of SLE and the exploration of new targeted treatment strategies are essential to advance the treatment of this complex autoimmune disease.

Implications of CD154 and Its Receptors in the Pathogenesis and Treatment of Systemic Lupus Erythematosus

CD154, also known as CD40 ligand, is a costimulatory molecule involved in humoral and adaptive immune responses upon pairing with its classical receptor, CD40. The CD154/CD40 dyad is a key participant in the pathogenesis of many autoimmune diseases, including systemic lupus erythematosus (SLE). In SLE, the major cells at play, T and B lymphocytes, are shown to overexpress CD154 and CD40, respectively. Subsequently, these cells and other CD40-positive cells engage in numerous effector functions contributing to SLE development. With the recent identification of additional receptors for CD154, all belonging to the integrin family, the role of CD154 in SLE is more complex and calls for deeper investigation into its biological significance. Many therapeutic strategies directed against the CD154/CD40 couple have been deployed for the treatment of SLE and proved efficient in animal models and human studies. However, the incidence of thromboembolic complications in patients treated with these anti-CD154/CD40 antibodies halted their further clinical assessments and called for another class of therapies targeting these molecules. Second-generation antibodies directed against CD154 or CD40 are showing promising results in the advanced stages of clinical testing. Our review presents a thorough description of CD154 and its receptors, CD40 and the integrin family members in SLE pathogenesis. All these elements of the CD154 system represent important therapeutic targets for the treatment of SLE.

Differential induction of donor-reactive Foxp3+ regulatory T cell via blockade of CD154 vs CD40

Recently published studies in both murine models and a meta-analysis of non-human primate renal transplant studies showed that anti-CD154 reagents conferred a significant survival advantage over CD40 blockers in both animal models and across multiple organs. Here we sought to compare the induction of donor-reactive forkhead box P3+-induced regulatory T cells (Foxp3+ iTreg) in mice treated with anti-CD154 versus anti-CD40 monoclonal antibodies (mAbs). Results indicated that while treatment with anti-CD154 mAb resulted in a significant increase in the frequency of donor-reactive CD4+ Foxp3+ iTreg following transplantation, treatment with anti-CD40 or Cd40 deficiency failed to recapitulate this result. Because we recently identified CD11b as an alternate receptor for CD154 during alloimmunity, we interrogated the role of CD154:CD11b interactions in the generation of Foxp3+ iTreg and found that blockade of CD11b in Cd40-/- recipients resulted in increased donor-reactive Foxp3+ iTreg as compared with CD40 deficiency alone. Mechanistically, CD154:CD11b inhibition decreased interleukin (IL)-1β from CD11b+ and CD11c+ dendritic cells, and blockade of IL-1β synergized with CD40 deficiency to promote Foxp3+ iTreg induction and prolong allograft survival. Taken together, these data provide a mechanistic basis for the observed inferiority of anti-CD40 blockers as compared with anti-CD154 mAb and illuminate an IL-1β-dependent mechanism by which CD154:CD11b interactions prevent the generation of donor-reactive Foxp3+ iTreg during transplantation.

Cross-Phenotype GWAS Supports Shared Genetic Susceptibility to Systemic Sclerosis and Primary Biliary Cholangitis

Objective

An increased risk of primary biliary cholangitis (PBC) has been reported in patients with systemic sclerosis (SSc). Our study aims to investigate the shared genetic susceptibility between the two disorders and to define candidate causal genes using cross-phenotype GWAS meta-analysis.

Methods

We performed cross-phenotype GWAS meta-analysis and colocalization analysis for SSc and PBC. We performed both genome-wide and locus-based analysis, including tissue and pathway enrichment analyses, fine-mapping, colocalization analyses with expression quantitative trait loci (eQTL) and protein quantitative trait loci (pQTL) datasets, and phenome-wide association studies (PheWAS). Finally, we used an integrative approach to prioritize candidate causal genes from the novel loci.

Results

We detected a strong genetic correlation between SSc and PBC (rg = 0.84, p = 1.7 × 10-6). In the cross-phenotype GWAS meta-analysis, we identified 44 non-HLA loci that reached genome-wide significance (p < 5 × 10-8). Evidence of shared causal variants between SSc and PBC was found for nine loci, five of which were novel. Integrating multiple sources of evidence, we prioritized CD40, ERAP1, PLD4, SPPL3, and CCDC113 as novel candidate causal genes. The CD40 risk locus colocalized with trans-pQTLs of multiple plasma proteins involved in B cell function.

Conclusion

Our study supports a strong shared genetic susceptibility between SSc and PBC. Through cross-phenotype analyses, we have prioritized several novel candidate causal genes and pathways for these disorders.

Poorly Differentiated Hepatocellular Carcinoma Cells Avoid Apoptosis by Interacting with T Cells via CD40-CD40 Ligand Linkage

Hepatocellular carcinoma (HCC) is associated with increased soluble CD40 levels. This study aimed to investigate CD40's role in liver tumor progression. CD40 levels were examined in HCC patient tissues and various HCC cell lines, and their interaction with CD4+T cells was studied. RNA sequencing analysis was performed to explore the mechanisms of CD40 induction. Poorly differentiated HCC tumor tissues exhibited high membrane-bound CD40 expression, in contrast to nontumor areas. Poorly differentiated HCC cell lines showed high expression of membrane-bound CD40 with low CD40 promoter methylation, which was the opposite of that observed in the well-differentiated HCC cell lines. Solely modulating CD40 expression in HCC cells exerted no direct consequences on cell growth or appearance. Interestingly, the human hepatoma cell line HLF co-cultured with activated (CD40 ligand+) CD4+ T cells had increased CD40 levels and a modest 3.2% dead cells. The percentage of dead cells increased to 10.9% and underwent preneutralizing CD40 condition, whereas preblocking both CD40 and integrin α5β1 concomitantly caused only 1.9% cell death. RNA sequencing of co-cultured HLFs with activated CD4+ T cells revealed the up-regulation of interferon and immune-response pathways. Increased interferon-γ levels in the activated T-cell media stimulated the Janus kinase/signal transducer and activator of transcription 3 pathway, resulting in increased CD40 expression in HLF. Collectively, CD40 expression in poorly differentiated HCC cells prevented cell death by interacting with CD40 ligand in activated T cells. Targeting CD40 may represent a promising anticancer therapy.

Genetically predicted inflammatory proteins and the risk of atrial fibrillation: a bidirectional Mendelian randomization study

Purpose

The causal associations between inflammatory factors and atrial fibrillation (AF) remained unclear. We aimed to investigate whether genetically predicted inflammatory proteins are related to the risk of AF, and vice versa.

Methods

A bidirectional two-sample Mendelian randomization study was performed. The genetic variation of 91 inflammatory proteins were derived from genome-wide association study (GWAS) data of European ancestry (n = 14,824). Summary statistics for AF were obtained from a published meta-analysis study (n = 1,030,836) and the FinnGen study (n = 261,395).

Results

Genetically predicted fibroblast growth factor 5 (FGF5) was significantly positively associated with risk of AF [[odds ratio (OR): 1.07; 95% CI: 1.04-1.10; P < 0.01], and CD40l receptor was significantly negatively associated with risk of AF (OR: 0.95; 95% CI: 0.92-0.98; P = 0.02) in the meta-analysis study. In the FinnGen study, similar results were observed in FGF5 (OR: 1.11; 95% CI: 1.06-1.16; P < 0.01) and CD40l receptor (OR: 0.93; 95% CI: 0.89-0.97; P = 0.03) for AF. In the FinnGen study, TNF-beta was significantly positively associated with risk of AF (OR: 1.05; 95% CI: 1.02-1.09; P = 0.03) and leukemia inhibitory factor receptor was significantly negatively associated with risk of AF (OR: 0.86; 95% CI: 0.80-0.91; P = 0.001). The causal effect of AF on inflammatory proteins was not observed.

Conclusion

Our study suggested that FGF5 and CD40l receptor have a potential causal association with AF, and targeting these factors may help in the treatment of AF.

Causality of genetically proxied immunophenotypes on cardiovascular diseases: a Mendelian randomization study

Background

Cardiovascular diseases (CVDs) stand as the foremost global cause of mortality, prompting a growing interest in using the potential of immune cells for heart injury treatment. This study aims to assess the causal association between immune cells and CVDs.

Methods

A total of 731 immune cells were derived from a previously published genome-wide association study (GWAS), which included approximately 22 million genetic variants among 3,757 individuals of Sardinian ancestry. Genetic associations with atrial fibrillation (AF), heart failure, coronary artery disease, myocardial infarction and stroke were extracted from large-scale GWAS. A two-sample Mendelian randomization (MR) analysis was used to assess the causal association between immune cells and CVDs. Replication MR analysis based on FinnGen dataset and meta-analysis are sequentially conducted to validate causal relationships.

Results

Collectively, genetically predicted 4 immune cell traits were associated with AF and 5 immune cell traits were associated with stroke. Increased levels of IgD- CD38dim absolute count were associated with a higher susceptibility to AF, while increased expression of CD14+ CD16+ monocytes, CD62L on CD62L+ myeloid dendritic cells, and CD16 on CD14- CD16+ monocytes were linked to a decreased susceptibility to AF. Additionally, an elevated susceptibility to stroke was linked to an increase in the percentage of CD39+ resting Tregs and heightened CD27 expression on IgD- CD38+ cells. Conversely, a decreased susceptibility to stroke was associated with increased CD40 expression on monocytes, particularly on CD14+ CD16+ and CD14+ CD16- monocytes, with the latter two showing the most compelling evidence.

Conclusion

This study identified several immune cell traits that have a causal relationship with CVDs, thus confirming that immune cells play an important role in the pathogenesis of these diseases.

Platelet biology and function: plaque erosion vs. rupture

The leading cause of heart disease in developed countries is coronary atherosclerosis, which is not simply a result of ageing but a chronic inflammatory process that can lead to acute clinical events upon atherosclerotic plaque rupture or erosion and arterial thrombus formation. The composition and location of atherosclerotic plaques determine the phenotype of the lesion and whether it is more likely to rupture or to erode. Although plaque rupture and erosion both initiate platelet activation on the exposed vascular surface, the contribution of platelets to thrombus formation differs between the two phenotypes. In this review, plaque phenotype is discussed in relation to thrombus composition, and an overview of important mediators (haemodynamics, matrix components, and soluble factors) in plaque-induced platelet activation is given. As thrombus formation on disrupted plaques does not necessarily result in complete vessel occlusion, plaque healing can occur. Therefore, the latest findings on plaque healing and the potential role of platelets in this process are summarized. Finally, the clinical need for more effective antithrombotic agents is highlighted.

In vitro immune evaluation of adenoviral vector-based platform for infectious diseases

New prophylactic vaccine platforms are imperative to combat respiratory infections. The efficacy of T and B memory cell-mediated protection, generated through the adenoviral vector, was tested to assess the effectiveness of the new adenoviral-based platforms for infectious diseases. A combination of adenovirus AdV1 (adjuvant), armed with costimulatory ligands (ICOSL and CD40L), and rRBD (antigen: recombinant nonglycosylated spike protein rRBD) was used to promote the differentiation of T and B lymphocytes. Adenovirus AdV2 (adjuvant), without ligands, in combination with rRBD, served as a control. In vitro T-cell responses to the AdV1+rRBD combination revealed that CD8+ platform-specific T-cells increased (37.2 ± 0.7% vs. 23.1 ± 2.1%), and T-cells acted against SARS-CoV-2 via CD8+TEMRA (50.0 ± 1.3% vs. 36.0 ± 3.2%). Memory B cells were induced after treatment with either AdV1+rRBD (84.1 ± 0.8% vs. 82.3 ± 0.4%) or rRBD (94.6 ± 0.3% vs. 82.3 ± 0.4%). Class-switching from IgM and IgD to isotype IgG following induction with rRBD+Ab was observed. RNA-seq profiling identified gene expression patterns related to T helper cell differentiation that protect against pathogens. The analysis determined signaling pathways controlling the induction of protective immunity, including the MAPK cascade, adipocytokine, cAMP, TNF, and Toll-like receptor signaling pathway. The AdV1+rRBD formulation induced IL-6, IL-8, and TNF. RNA-seq of the VERO E6 cell line showed differences in the apoptosis gene expression stimulated with the platforms vs. mock. In conclusion, AdV1+rRBD effectively generates T and B memory cell-mediated protection, presenting promising results in producing CD8+ platform-specific T cells and isotype-switched IgG memory B cells. The platform induces protective immunity by controlling the Th1, Th2, and Th17 cell differentiation gene expression patterns. Further studies are required to confirm its effectiveness.

CD40-CD40 ligand interaction between periodontal ligament cells and cementoblasts enhances periodontal tissue remodeling in response to mechanical stress

OBJECTIVE

We analyzed the localization and expression of Cluster of differentiation 40 ligand (CD40L) in murine periodontal tissue applied with the orthodontic force to determine the CD40L-expressing cells under mechanical stress. Furthermore, we investigated whether CD40-CD40L interaction played an important role in transducing mechanical stress between periodontal ligament (PDL) cells and cementoblasts and remodeling the periodontal tissue for its homeostasis.

BACKGROUND

PDL is a complex tissue that contains heterogeneous cell populations and is constantly exposed to mechanical stress, such as occlusal force. CD40 is expressed on PDL cells and upregulated under mechanical stress. However, whether its ligand, CD40L, is upregulated in periodontal tissue in response to mechanical stress, and which functions the CD40-CD40L interaction induces by converting the force to biological functions between the cement-PDL complex, are not fully understood.

METHODS

The orthodontic treatment was applied to the first molars at the left side of the upper maxillae of mice using a nickel-titanium closed-coil spring. Immunohistochemistry was performed to analyze the localization of CD40L in the periodontal tissue under the orthodontic force. Human cementoblasts (HCEM) and human PDL cells were stretched in vitro and analyzed CD40L and CD40 protein expression using flow cytometry. A GFP-expressing CD40L plasmid vector was transfected into HCEM (CD40L-HCEM). CD40L-HCEM was co-cultured with human PDL cells with higher alkaline phosphatase (ALP) activity (hPDS) or lower ALP (hPDF). After co-culturing, cell viability and proliferation were analyzed by propidium iodide (PI) staining and bromodeoxyuridine (BrdU) assay. Furthermore, the mRNA expression of cytodifferentiation- and extracellular matrix (ECM)-related genes was analyzed by real-time PCR.

RESULTS

Immunohistochemistry demonstrated that CD40L was induced on the cells present at the cementum surface in periodontal tissue at the tension side under the orthodontic treatment in mice. The flow cytometry showed that the in vitro-stretching force upregulated CD40L protein expression on HCEM and CD40 protein expression on human PDL cells. Co-culturing CD40L-HCEM with hPDF enhanced cell viability and proliferation but did not alter the gene expression related to cytodifferentiation and ECM. In contrast, co-culturing CD40L-HCEM with hPDS upregulated cytodifferentiation- and ECM-related genes but did not affect cell viability and proliferation.

CONCLUSION

We revealed that in response to a stretching force, CD40L expression was induced on cementoblasts. CD40L on cementoblasts may interact with CD40 on heterogeneous PDL cells at the necessary time and location, inducing cell viability, proliferation, and cytodifferentiation, maintaining periodontal tissue remodeling and homeostasis.

Immunotherapeutic approaches for systemic lupus erythematosus: early overview and future potential

Systemic lupus erythematosus (SLE) is a complex autoimmune disease. Current SLE therapies include immunosuppressants, antimalarial drugs, non-steroidal anti-inflammatory drugs (NSAIDs), and corticosteroids, but these treatments can cause substantial toxicities to organs and may not be effective for all patients. In recent years, significant progress has been made in the treatment of SLE using immunotherapy, including Benlysta and Saphnelo. These advances in immunotherapy hold promise for SLE patients, providing new therapeutic options that may offer better clinical benefit and effectiveness. Simultaneously, several new biological therapies focusing on cytokines, peptides, targeted antibodies, and cell-based approaches are under clinical evaluation and have shown immense potential for the treatment of SLE. However, the complexity of SLE immunopathogenesis and disease heterogeneity present significant challenges in the development of effective immunological therapies. This review aims to discuss past experiences and understanding of diverse immunological targeting therapies for SLE and highlight future perspectives for the development of novel immunological therapies.

Elevated circulating inflammatory biomarker levels in the SIRT1-NF-κB-sCD40L pathway in patients with acute myocardial infarction: a case-control study

BACKGROUND

Inflammation plays a key role in atherosclerosis development and progression. However, the role of novel inflammatory biomarker pathways, namely the SIRT1-NF-κB-sCD40L, in the etiopathogenesis of human atherosclerosis remains undefined. This study was designed to evaluate the changes and clinical implications of these inflammatory mediators in the plasma of patients with acute myocardial infarction (AMI).

METHODS

The peripheral arterial blood of 88 participants (68 patients with AMI and 20 age-matched controls), was drawn prior to performing coronary angiography (CAG). The SIRT1, NF-κB, and sCD40L plasma levels were quantified using ELISA. Spearman's analysis was used to evaluate the correlation between the three inflammatory markers, while Pearson's test assessed their potential correlation with cardiac troponin T (TNT) levels. Sensitivity, specificity, and area under the ROC curve (AUC) were calculated as measures of diagnostic accuracy.

RESULTS

Patients with AMI showed higher levels of circulating SIRT1, NF-κB, and sCD40L compared to the age-matched controls (p < 0.05). However, the plasma concentrations of these three inflammatory mediators did not differ between the ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) patients. Additionally, in patients with AMI, the SIRT1 level was positively correlated with NF-κB and sCD40L levels (p < 0.001). Likewise, the levels of SIRT1, NF-κB and sCD40L were positively correlated with TNT levels (p < 0.001). More importantly, the ROC analysis showed that the diagnostic accuracy of AMI was significantly higher when NF-κB or sCD40L level was used in combination with TNT levels (p < 0.05).

CONCLUSIONS

The levels of the circulating inflammatory biomarkers, including SIRT1, NF-κB, and sCD40L, were significantly elevated in patients with AMI. These novel biomarkers can improve the diagnostic accuracy of AMI when combined with TNT.KEY MESSAGESAMI is a potentially lethal CAD and is the leading cause of mortality and morbidity worldwide. Inflammation plays a key role in atherosclerosis development and progression. The levels of the circulating novel inflammatory biomarkers, including SIRT1, NF-κB, and sCD40L, were significantly elevated in patients with AMI.The SIRT1 level was positively correlated with NF-κB and sCD40L levels in patients with AMI.The levels of SIRT1, NF-κB and sCD40L were positively correlated with TNT levels.The ROC analysis showed that the diagnostic accuracy of AMI was significantly higher when NF-κB or sCD40L level was used in combination with TNT levels.SIRT1/NF-κB/sCD40L axis inhibition is a potential new target for AMI treatment.

Novel peptide inhibitors targeting CD40 and CD40L interaction: A potential for atherosclerosis therapy

Atherosclerosis is a chronic inflammatory disease characterized by plaque build-up in the arteries, leading to the obstruction of blood flow. Macrophages are the primary immune cells found in the atherosclerotic lesions and are directly involved in atherosclerosis progression. Macrophages are derived from extravasating blood monocytes. The monocytic CD40 receptor is important for monocyte recruitment on the endothelium expressing the CD40 ligand (CD40L). Thus, targeting monocyte/macrophage interaction with the endothelium by inhibiting CD40-CD40L interaction may be a promising strategy for attenuating atherosclerosis. Monoclonal antibodies have been used against this target but shows various complications. We used an array of computer-aided drug discovery tools and molecular docking approaches to design a therapeutic inhibitory peptide that could efficiently bind to the critical residues (82Y, 84D, and 86N) on the CD40 receptor essential for the receptor's binding to CD40L. The initial screen identified a parent peptide with a high binding affinity to CD40, but the peptide exhibited a positive hepatotoxicity score. We then designed several novel peptidomimetic derivatives with higher binding affinities to CD40, good physicochemical properties, and negative hepatotoxicity as compared to the parent peptide. Furthermore, we conducted molecular dynamics simulations for both the apo and complexed forms of the receptor with ligand, and screened peptides to evaluate their stability. The designed peptidomimetic derivatives are promising therapeutics targeting the CD40-CD40L interaction and may potentially be used to attenuate atherosclerosis.

CD40 Ligand-CD40 Interaction Is an Intermediary between Inflammation and Angiogenesis in Proliferative Diabetic Retinopathy

We aimed to investigate the role of the CD40-CD40 ligand (CD40L) pathway in inflammation-mediated angiogenesis in proliferative diabetic retinopathy (PDR). We analyzed vitreous fluids and epiretinal fibrovascular membranes from PDR and nondiabetic patients, cultures of human retinal microvascular endothelial cells (HRMECs) and Müller glial cells and rat retinas with ELISA, immunohistochemistry, flow cytometry and Western blot analysis. Functional tests included measurement of blood-retinal barrier breakdown, in vitro angiogenesis and assessment of monocyte-HRMEC adherence. CD40L and CD40 levels were significantly increased in PDR vitreous samples. We demonstrated CD40L and CD40 expression in vascular endothelial cells, leukocytes and myofibroblasts in epiretinal membranes. Intravitreal administration of soluble (s)CD40L in normal rats significantly increased retinal vascular permeability and induced significant upregulation of phospho-ERK1/2, VEGF, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). sCD40L induced upregulation of VEGF, MMP-9, MCP-1 and HMGB1 in cultured Müller cells and phospo-ERK1/2, p65 subunit of NF-ĸB, VCAM-1 and VEGF in cultured HRMECS. TNF-α induced significant upregulation of CD40 in HRMECs and Müller cells and VEGF induced significant upregulation of CD40 in HRMECs. sCD40L induced proliferation and migration of HRMECs. We provide experimental evidence supporting the involvement of the CD40L-CD40 pathway and how it regulates inflammatory angiogenesis in PDR.

Role of the CD40-CD40 Ligand Pathway in Cardiovascular Events, Neurological Alterations, and Other Clinical Complications of Chronic Hemodialysis Patients: Protective Role of Adsorptive Membranes

Despite the recent advances in dialysis technology, mortality rate of chronic uremic patients still remains excessively high: of note, in comparison to age- and sex-matched healthy controls, this frail population shows a higher incidence of infections, cancer, cognitive decline, and, in particular, major adverse cardiovascular events (MACE) that represent nowadays the first cause of mortality. Several traditional and nontraditional factors contribute to this increased risk for MACE and accelerated cellular senescence: among these, inflammation has been shown to play a key role. The costimulatory pathway CD40-CD40 Ligand (CD40L) is harmfully activated during inflammation and uremia-associated clinical complications: in particular, the soluble form of CD40L (sCD40L) can bind to the CD40 receptor triggering a cascade of detrimental pathways in immune and nonimmune cells. In this narrative review, we summarize the current concepts of the biological role of the CD40-CD40L pathway in uremia-associated organ dysfunction, focusing on the above-described main causes of mortality. Moreover, we discuss the interaction of the CD40-CD40L pathway with extracellular vesicles, microparticles recently identified as new uremic toxins. The biological effects of sCD40L in MACE, cognitive decline, infections, and cancer will be also briefly commented. Last, based on recent studies and ongoing clinical trials, we herein describe the modulatory activity of adsorptive dialysis membranes in polymethylmethacrylate on CD40-CD40L detrimental activation.

Causal associations between CD40/CD40L and aortic diseases: A mendelian randomization study

Background: CD40 and CD40L have been reported as associated with aortic dissection (AD) and aortic aneurysm (AA), but the causality of the associations has not been established yet. Methods: We conducted a two-sample Mendelian randomization (MR) study to assess the causal inference between CD40/CD40L and aortic diseases including AD and AA. The instrumental variables (IVs) for CD40 and CD40L were selected from a high-quality protein quantitative trait loci dataset released by a genomic study involving 30,931 individuals of European ancestry. The genome-wide association studies summary statistics for AD and AA were from the FinnGen Release 7, with 288638 controls for all outcomes of interests, 680 cases for AD and 6,092 cases for AA, also from European ancestry. For AA subtypes, there were 5,881 cases of thoracic AA (TAA) and 2,434 cases of abdominal AA (AAA) respectively. Inverse-variance weighted and Wald ratio were applied for calculating causal estimates. Horizontal pleiotropy and heterogeneity were assessed using MR-Egger regression analysis and Cochran Q test, respectively. Leave-one-out analyses were further performed. Results: Three single-nucleotide polymorphisms (SNPs) for CD40 and one SNP for CD40L were selected as IVs. We found genetic proxied CD40 levels inversely associated with the risk of AD (odds ratio [OR]: 0.777, 95% confidence interval [CI]: 0.618-0.978, p = 0.031) and AA (OR: 0.905, 95% CI: 0.837-0.978, p = 0.012), consistent across TAA (both p < 0.050). There were trends of increased risks of AD and AA in the presence of CD40L while not reaching statistical significance. No significant horizontal pleiotropy or heterogeneity was observed. Conclusion: Our MR study provides evidence supporting the causal association between CD40 and the reduced risks of both AD and AA.

Role of CD40(L)-TRAF signaling in inflammation and resolution-a double-edged sword

Cardiovascular diseases (CVD) and cardiovascular risk factors are the leading cause of death in the world today. According to the Global Burden of Disease Study, hypertension together with ischemic heart and cerebrovascular diseases is responsible for approximately 40% of all deaths worldwide. The major pathomechanism underlying almost all CVD is atherosclerosis, an inflammatory disorder of the vascular system. Recent large-scale clinical trials demonstrated that inflammation itself is an independent cardiovascular risk factor. Specific anti-inflammatory therapy could decrease cardiovascular mortality in patients with atherosclerosis (increased markers of inflammation). Inflammation, however, can also be beneficial by conferring so-called resolution, a process that contributes to clearing damaged tissue from cell debris upon cell death and thereby represents an essential step for recovery from, e.g., ischemia/reperfusion damage. Based on these considerations, the present review highlights features of the detrimental inflammatory reactions as well as of the beneficial process of immune cell-triggered resolution. In this context, we discuss the polarization of macrophages to either M1 or M2 phenotype and critically assess the role of the CD40L-CD40-TRAF signaling cascade in atherosclerosis and its potential link to resolution. As CD40L can bind to different cellular receptors, it can initiate a broad range of inflammatory processes that may be detrimental or beneficial. Likewise, the signaling of CD40L downstream of CD40 is mainly determined by activation of TRAF1-6 pathways that again can be detrimental or beneficial. Accordingly, CD40(L)-based therapies may be Janus-faced and require sophisticated fine-tuning in order to promote cardioprotection.

Activation and regulation of alloreactive T cell immunity in solid organ transplantation

Transplantation is the only curative treatment for patients with kidney failure but it poses unique immunological challenges that must be overcome to prevent allograft rejection and ensure long-term graft survival. Alloreactive T cells are important contributors to graft rejection, and a clearer understanding of the mechanisms by which these cells recognize donor antigens - through direct, indirect or semi-direct pathways - will facilitate their therapeutic targeting. Post-T cell priming rejection responses can also be modified by targeting pathways that regulate T cell trafficking, survival cytokines or innate immune activation. Moreover, the quantity and quality of donor-reactive memory T cells crucially shape alloimmune responses. Of note, many fundamental concepts in transplant immunology have been derived from models of infection. However, the programmed differentiation of allograft-specific T cell responses is probably distinct from that of pathogen-elicited responses, owing to the dearth of pathogen-derived innate immune activation in the transplantation setting. Understanding the fundamental (and potentially unique) immunological pathways that lead to allograft rejection is therefore a prerequisite for the rational development of therapeutics that promote transplantation tolerance.

Myeloid CD40 deficiency reduces atherosclerosis by impairing macrophages' transition into a pro-inflammatory state

AIMS

CD40 and its ligand, CD40L, play a critical role in driving atherosclerotic plaque development. Disrupted CD40-signaling reduces experimental atherosclerosis and induces a favourable stable plaque phenotype. We recently showed that small molecule-based inhibition of CD40-TNF Receptor Associated Factor-6 interactions attenuates atherosclerosis in hyperlipidaemic mice via macrophage-driven mechanisms. The present study aims to detail the function of myeloid CD40 in atherosclerosis using myeloid-specific CD40-deficient mice.

METHOD AND RESULTS

Cd40flox/flox and LysM-cre Cd40flox/flox mice on an Apoe-/- background were generated (CD40wt and CD40mac-/-, respectively). Atherosclerotic lesion size, as well as plaque macrophage content, were reduced in CD40mac-/- compared to CD40wt mice and their plaques displayed a reduction in necrotic core size. Transcriptomics analysis of the CD40mac-/- atherosclerotic aorta revealed downregulated pathways of immune pathways and inflammatory responses.Loss of CD40 in macrophages changed the representation of aortic macrophage subsets. Mass cytometry analysis revealed a higher content of a subset of alternative or resident-like CD206 + CD209b- macrophages in the atherosclerotic aorta of CD40mac-/- compared to CD40wt mice. RNA-sequencing of bone marrow-derived macrophages (BMDMs) of CD40mac-/- mice demonstrated upregulation of genes associated with alternatively activated macrophages (including Folr2, Thbs1, Sdc1 and Tns1).

CONCLUSIONS

We here show that absence of CD40 signalling in myeloid cells reduces atherosclerosis and limits systemic inflammation by preventing a shift in macrophage polarization towards pro-inflammatory states. Our study confirms the merit of macrophage-targeted inhibition of CD40 as a valuable therapeutic strategy to combat atherosclerosis.

CD40-CD40L in Neurological Disease

Immune-inflammatory conditions in the central nervous system (CNS) rely on molecular and cellular interactions which are homeostatically maintained to protect neural tissue from harm. The CD40–CD40L interaction upregulates key proinflammatory molecules, a function best understood in the context of infection, during which B-cells are activated via CD40 signaling to produce antibodies. However, the role of CD40 in neurological disease of non-infectious etiology is unclear. We review the role of CD40–CD40L in traumatic brain injury, Alzheimer’s Disease, Parkinson’s Disease, stroke, epilepsy, nerve injury, multiple sclerosis, ALS, myasthenia gravis and brain tumors. We also highlight therapeutic advancements targeting the CD40 system to either attenuate the neuroinflammatory response or leverage the downstream effects of CD40 signaling for direct tumor cell lysis.

The Role of Tumor Necrosis Factor Associated Factors (TRAFs) in Vascular Inflammation and Atherosclerosis

TNF receptor associated factors (TRAFs) represent a family of cytoplasmic signaling adaptor proteins that regulate, bundle, and transduce inflammatory signals downstream of TNF- (TNF-Rs), interleukin (IL)-1-, Toll-like- (TLRs), and IL-17 receptors. TRAFs play a pivotal role in regulating cell survival and immune cell function and are fundamental regulators of acute and chronic inflammation. Lately, the inhibition of inflammation by anti-cytokine therapy has emerged as novel treatment strategy in patients with atherosclerosis. Likewise, growing evidence from preclinical experiments proposes TRAFs as potent modulators of inflammation in atherosclerosis and vascular inflammation. Yet, TRAFs show a highly complex interplay between different TRAF-family members with partially opposing and overlapping functions that are determined by the level of cellular expression, concomitant signaling events, and the context of the disease. Therefore, inhibition of specific TRAFs may be beneficial in one condition and harmful in others. Here, we carefully discuss the cellular expression and signaling events of TRAFs and evaluate their role in vascular inflammation and atherosclerosis. We also highlight metabolic effects of TRAFs and discuss the development of TRAF-based therapeutics in the future.

Correlation between Insulin Resistance with Soluble CD40 Ligand and Plasminogen Activator Inhibitor-1 Plasma in Pre-diabetic Patients

BACKGROUND: The main condition of pre-diabetes is insulin resistance that can lead to a prothrombotic state. AIM: This study aims to correlate insulin resistance with soluble CD40 ligand (sCD40L) and plasminogen activator inhibitor-1 (PAI-1) plasma in pre-diabetic patients. METHODS: This study is an analytic observational study with a cross-sectional approach. HOMA-IR assessed insulin resistance, and prothrombotic factors were assessed by PAI-1 and soluble CD40L. PAI-1 and sCD40L were examined by ELISA. These indicators were assessed on 30 pre-diabetic patients. RESULTS: Thirty subjects included in this study with a mean age of 31.47 (5.03) years old, consist of 19 (63%) men and 11 (37%) women. The mean HOMA-IR was 3.69 (1.12), PAI-1 was 10.25 (3.72) ng/mL, and the PAI-1 levels were increased (>8.4 ng/mL) in 70% of the subjects. The mean of sCD40L levels was 4495.7 (1136.3) pg/ml, and sCD40L levels were increased (>4000 pg/ml) in 63% of subject. There was a significant correlation between HOMA-IR levels and sCD40L (r = 0.636, p < 0.05) and between of HOMA-IR and PAI-1 (r = 0.742, p < 0.05). Moderate correlation was found between sCD40L levels and plasma PAI-1 (r = 0.592, p < 0.05) in pre-diabetic patient. The correlation between three variables was HOMA-IR had a significant effect on PAI-1 levels through sCD40L (t = 2.010, p < 0.05, structure loading factor = 0.286). CONCLUSION: Insulin resistance has a strong and significant correlation with sCD40L and PAI-1 levels in pre-diabetic patients.

Immune Checkpoint Therapies and Atherosclerosis: Mechanisms and Clinical Implications: JACC State-of-the-Art Review

Immune checkpoint inhibitor therapy has revolutionized the treatment of advanced malignancies in recent years. Numerous reports have detailed the myriad of possible adverse inflammatory effects of immune checkpoint therapies, including within the cardiovascular system. However, these reports have been largely limited to myocarditis. The critical role of inflammation and adaptive immunity in atherosclerosis has been well characterized in preclinical studies, and several emerging clinical studies indicate a potential role of immune checkpoint targeting therapies in the development and exacerbation of atherosclerosis. In this review, we provide an overview of the role of T-cell immunity in atherogenesis and describe the molecular effects and clinical associations of both approved and investigational immune checkpoint therapy on atherosclerosis. We also highlight the role of cholesterol metabolism in oncogenesis and discuss the implications of these associations on future treatment and monitoring of atherosclerotic cardiovascular disease in the oncologic population receiving immune checkpoint therapy.

Role of CD39 in COVID-19 Severity: Dysregulation of Purinergic Signaling and Thromboinflammation

CD39/NTPDase1 has emerged as an important molecule that contributes to maintain inflammatory and coagulatory homeostasis. Various studies have hypothesized the possible role of CD39 in COVID-19 pathophysiology since no confirmatory data shed light in this regard. Therefore, we aimed to quantify CD39 expression on COVID-19 patients exploring its association with severity clinical parameters and ICU admission, while unraveling the role of purinergic signaling on thromboinflammation in COVID-19 patients. We selected a prospective cohort of patients hospitalized due to severe COVID-19 pneumonia (n=75), a historical cohort of Influenza A pneumonia patients (n=18) and sex/age-matched healthy controls (n=30). CD39 was overexpressed in COVID-19 patients’ plasma and immune cell subsets and related to hypoxemia. Plasma soluble form of CD39 (sCD39) was related to length of hospital stay and independently associated with intensive care unit admission (adjusted odds ratio 1.04, 95%CI 1.0-1.08, p=0.038), with a net reclassification index of 0.229 (0.118-0.287; p=0.036). COVID-19 patients showed extracellular accumulation of adenosine nucleotides (ATP and ADP), resulting in systemic inflammation and pro-coagulant state, as a consequence of purinergic pathway dysregulation. Interestingly, we found that COVID-19 plasma caused platelet activation, which was successfully blocked by the P2Y₁₂ receptor inhibitor, ticagrelor. Therefore, sCD39 is suggested as a promising biomarker for COVID-19 severity. As a conclusion, our study indicates that CD39 overexpression in COVID-19 patients could be indicating purinergic signaling dysregulation, which might be at the basis of COVID-19 thromboinflammation disorder.

Immune Mechanisms of Plaque Instability

Inflammation crucially drives atherosclerosis from disease initiation to the emergence of clinical complications. Targeting pivotal inflammatory pathways without compromising the host defense could compliment therapy with lipid-lowering agents, anti-hypertensive treatment, and lifestyle interventions to address the substantial residual cardiovascular risk that remains beyond classical risk factor control. Detailed understanding of the intricate immune mechanisms that propel plaque instability and disruption is indispensable for the development of novel therapeutic concepts. In this review, we provide an overview on the role of key immune cells in plaque inception and progression, and discuss recently identified maladaptive immune phenomena that contribute to plaque destabilization, including epigenetically programmed trained immunity in myeloid cells, pathogenic conversion of autoreactive regulatory T-cells and expansion of altered leukocytes due to clonal hematopoiesis. From a more global perspective, the article discusses how systemic crises such as acute mental stress or infection abruptly raise plaque vulnerability and summarizes recent advances in understanding the increased cardiovascular risk associated with COVID-19 disease. Stepping outside the box, we highlight the role of gut dysbiosis in atherosclerosis progression and plaque vulnerability. The emerging differential role of the immune system in plaque rupture and plaque erosion as well as the limitations of animal models in studying plaque disruption are reviewed.

Comprehensive phenotyping of human platelets by single-cell cytometry

Platelets are small anucleate blood cells that contribute to hemostasis, immunity, and inflammation. Circulating platelets are heterogeneous in size, age, receptor expression, and reactivity. They inherit many features from megakaryocytes and are further modified on exposure to bioactive substances in the bloodstream. Among these substances, prothrombotic agonists, vasodilators, and bloodborne pathogens modulate platelet phenotypes via distinct signaling cascades. The ability of platelets to respond to (patho)physiologic signals is incompletely understood but likely depends on their repertoire of surface receptors, which may partition them into discrete subsets with specialized functions and divergent abilities. The single-cell resolution of flow and mass cytometry is ideal for immunophenotyping and allows the identification of platelet subsets in remarkable detail. In this report, we describe the surface markers and gating strategies needed for the comprehensive characterization of platelets.

Anti-inflammatory Strategies in Atherosclerosis

Atherosclerotic vascular disease and its related complications are the major cause of mortality in Western societies. Atherosclerosis is a chronic inflammatory disease of the arterial wall triggered by traditional and nontraditional risk factors and mediated by inflammatory and immune responses. Recent clinical trials provided compelling evidence corroborating that atherosclerosis is an inflammatory disease and demonstrated efficacy of anti-inflammatory interventions in reducing cardiovascular events and mortality. Traditional risk factors drive vascular inflammation, further justifying the instrumental role of intensified risk factor management in attenuating and preventing atherosclerotic disease and complications. Promising therapeutic approaches specifically related to inhibition of inflammation span traditional anti-inflammatory drugs, specific immunomodulation, and development of vaccination against atherosclerotic disease. Here, we review the inflammatory component in atherogenesis, the available evidence from clinical trials evaluating efficacy of therapeutic anti-inflammatory interventions in patients with high cardiovascular risk, and discuss potential future targets for anti-inflammatory or immune modulatory treatment in atherosclerotic cardiovascular disease.

Treatment of Cardiovascular Disease in Rheumatoid Arthritis: A Complex Challenge with Increased Atherosclerotic Risk

Rheumatoid arthritis (RA) carries significant risk for atherosclerotic cardiovascular disease (ASCVD). Traditional ASCVD risk factors fail to account for this accelerated atherosclerosis. Shared inflammatory pathways are fundamental in the pathogenesis of both diseases. Considering the impact of RA in increasing cardiovascular morbidity and mortality, the characterization of therapies encompassing both RA and ASCVD management merit high priority. Despite little progress, several drugs discussed here promote remission and or lower rheumatoid disease activity while simultaneously conferring some level of atheroprotection. Methotrexate, a widely used disease-modifying drug used in RA, is associated with significant reduction in cardiovascular adverse events. MTX promotes cholesterol efflux from macrophages, upregulates free radical scavenging and improves endothelial function. Likewise, the sulfonamide drug sulfasalazine positively impacts the lipid profile by increasing HDL-C, and its use in RA has been correlated with reduced risk of myocardial infraction. In the biologic class, inhibitors of TNF-α and IL-6 contribute to improvements in endothelial function and promote anti-atherogenic properties of HDL-C, respectively. The immunosuppressant hydroxychloroquine positively affects insulin sensitization and the lipid profile. While no individual therapy has elicited optimal atheroprotection, further investigation of combination therapies are ongoing.

CD40-CD154: A perspective from type 2 immunity

The interaction between CD40 and CD154 (CD40 ligand) is central in immunology, participating in CD4⁺ T cell priming by dendritic cells (DC), CD4⁺ T cell help to B cells and classical macrophage activation by CD4⁺ T cells. However, its role in the Th2 side of immunology including helminth infection remains incompletely understood. Contrary to viral and bacterial stimuli, helminth products usually do not cause CD40 up-regulation in DC, and exogenous CD40 ligation drives Th2-biased systems towards Th1. On the other hand, CD40 and CD154 are necessary for induction of most Th2 responses. We attempt to reconcile these observations, mainly by proposing that (i) CD40 up-regulation in DC in Th2 systems is mostly induced by alarmins, (ii) the Th2 to Th1 shift induced by exogenous CD40 ligation is related to the capacity of such ligation to enhance IL-12 production by myeloid cells, and (iii) signals elicited by endogenous CD154 available in Th2 contexts and by exogenous CD40 ligation are probably different. We stress that CD40-CD154 is important beyond cognate cellular interactions. In such a context, we argue that the proliferation response of B-cells to IL-4 plus CD154 reflects a Th2-specific mechanism for polyclonal B-cell amplification and IgE production at infection sites. Finally, we argue that CD154 is a general immune activation signal across immune polarization including Th2, and propose that competition for CD154 at tissue sites may provide negative feedback on response induction at each site.

Deficiency of Endothelial CD40 Induces a Stable Plaque Phenotype and Limits Inflammatory Cell Recruitment to Atherosclerotic Lesions in Mice

OBJECTIVES

The co-stimulatory CD40L-CD40 dyad exerts a critical role in atherosclerosis by modulating leukocyte accumulation into developing atherosclerotic plaques. The requirement for cell-type specific expression of both molecules, however, remains elusive. Here, we evaluate the contribution of CD40 expressed on endothelial cells (ECs) in a mouse model of atherosclerosis.

METHODS AND RESULTS

Atherosclerotic plaques of apolipoprotein E-deficient (Apoe -/- ) mice and humans displayed increased expression of CD40 on ECs compared with controls. To interrogate the role of CD40 on ECs in atherosclerosis, we induced EC-specific (BmxCreERT2-driven) deficiency of CD40 in Apoe -/- mice. After feeding a chow diet for 25 weeks, EC-specific deletion of CD40 (iEC-CD40) ameliorated plaque lipid deposition and lesional macrophage accumulation but increased intimal smooth muscle cell and collagen content, while atherosclerotic lesion size did not change. Leukocyte adhesion to the vessel wall was impaired in iEC-CD40-deficient mice as demonstrated by intravital microscopy. In accord, expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) in the vascular endothelium declined after deletion of CD40. In vitro, antibody-mediated inhibition of human endothelial CD40 significantly abated monocyte adhesion on ECs.

CONCLUSION

Endothelial deficiency of CD40 in mice promotes structural features associated with a stable plaque phenotype in humans and decreases leukocyte adhesion. These results suggest that endothelial-expressed CD40 contributes to inflammatory cell migration and consecutive plaque formation in atherogenesis.

CD40L modulates transcriptional signatures of neutrophils in the bone marrow associated with development and trafficking

Neutrophils are produced in the BM in a process called granulopoiesis, in which progenitor cells sequentially develop into mature neutrophils. During the developmental process, which is finely regulated by distinct transcription factors, neutrophils acquire the ability to exit the BM, properly distribute throughout the body, and migrate to infection sites. Previous studies have demonstrated that CD40 ligand (CD40L) influences hematopoiesis and granulopoiesis. Here, we investigate the effect of CD40L on neutrophil development and trafficking by performing functional and transcriptome analyses. We found that CD40L signaling plays an essential role in the early stages of neutrophil generation and development in the BM. Moreover, CD40L modulates transcriptional signatures, indicating that this molecule enables neutrophils to traffic throughout the body and to migrate in response to inflammatory signals. Thus, our study provides insights into the complex relationships between CD40L signaling and granulopoiesis, and it suggests a potentially novel and nonredundant role of CD40L signaling in neutrophil development and function.

Single Dose of N-Acetylcysteine in Local Anesthesia Increases Expression of HIF1α, MAPK1, TGFβ1 and Growth Factors in Rat Wound Healing

In this study, we aimed to investigate the influence of N-acetylcysteine (NAC) on the gene expression profile, neoangiogenesis, neutrophils and macrophages in a rat model of incisional wounds. Before creating wounds on the backs of 24 Sprague-Dawley rats, intradermal injections were made. Lidocaine-epinephrin solutions were supplemented with 0.015%, 0.03% or 0.045% solutions of NAC, or nothing (control group). Scars were harvested on the 3rd, 7th, 14th and 60th day post-surgery. We performed immunohistochemical staining in order to visualize macrophages (anti-CD68), neutrophils (anti-MPO) and newly formed blood vessels (anti-CD31). Additionally, RT-qPCR was used to measure the relative expression of 88 genes involved in the wound healing process. On the 14th day, the number of cells stained with anti-CD68 and anti-CD31 antibodies was significantly larger in the tissues treated with 0.03% NAC compared with the control. Among the selected genes, 52 were upregulated and six were downregulated at different time points. Interestingly, NAC exerted a significant effect on the expression of 45 genes 60 days after its administration. In summation, a 0.03% NAC addition to the pre-incisional anesthetic solution improves neovasculature and increases the macrophages' concentration at the wound site on the 14th day, as well as altering the expression of numerous genes that are responsible for the regenerative processes.

Integrative analysis of key candidate genes and signaling pathways in acute coronary syndrome related to obstructive sleep apnea by bioinformatics

Although obstructive sleep apnea (OSA) has been clinically reported to be associated with acute coronary syndrome (ACS), the pathogenesis between the two is unclear. Herein, we analyzed and screened out the prospective molecular marker. To explore the candidate genes, as well as signaling cascades involved in ACS related to OSA, we extracted the integrated differentially expressed genes (DEGs) from the intersection of genes from the Gene Expression Omnibus (GEO) cohorts and text mining, followed by enrichment of the matching cell signal cascade through DAVID analysis. Moreover, the MCODE of Cytoscape software was employed to uncover the protein-protein interaction (PPI) network and the matching hub gene. A total of 17 and 56 integrated human DEGs in unstable angina (UA) and myocardial infarction (MI) group associated with OSAs that met the criteria of |log2 fold change (FC)|≥ 1, adjusted P < 0.05, respectively, were uncovered. After PPI network construction, the top five hub genes associated with UA were extracted, including APP, MAPK3, MMP9, CD40 and CD40LG, whereas those associated with MI were PPARG, MAPK1, MMP9, AGT, and TGFB1. The establishment of the aforementioned candidate key genes, as well as the enriched signaling cascades, provides promising molecular marker for OSA-related ACS, which will to provide a certain predictive value for the occurrence of ACS in OSA patients in the future.

C4b-binding protein α-chain enhances antitumor immunity by facilitating the accumulation of tumor-infiltrating lymphocytes in the tumor microenvironment in pancreatic cancer

Background

Recent studies indicate that complement plays pivotal roles in promoting or suppressing cancer progression. We have previously identified C4b-binding protein α-chain (C4BPA) as a serum biomarker for the early detection of pancreatic ductal adenocarcinoma (PDAC). However, its mechanism of action remains unclear. Here, we elucidated the functional roles of C4BPA in PDAC cells and the tumor microenvironment.

Methods

We assessed stromal C4BPA, the C4BPA binding partner CD40, and the number of CD8⁺ tumor-infiltrating lymphocytes in resected human PDAC tissues via immunohistochemical staining. The biological functions of C4BPA were investigated in peripheral blood mononuclear cells (PBMCs) and human PDAC cell lines. Mouse C4BPA (mC4BPA) peptide, which is composed of 30 amino acids from the C-terminus and binds to CD40, was designed for further in vitro and in vivo experiments. In a preclinical experiment, we assessed the efficacy of gemcitabine plus nab-paclitaxel (GnP), dual immune checkpoint blockades (ICBs), and mC4BPA peptide in a mouse orthotopic transplantation model.

Results

Immunohistochemical analysis revealed that high stromal C4BPA and CD40 was associated with favorable PDAC prognosis (P=0.0005). Stromal C4BPA strongly correlated with the number of CD8⁺ tumor-infiltrating lymphocytes (P=0.001). In in vitro experiments, flow cytometry revealed that recombinant human C4BPA (rhC4BPA) stimulation increased CD4⁺ and CD8⁺ T cell numbers in PBMCs. rhC4BPA also promoted the proliferation of CD40-expressing PDAC cells. By contrast, combined treatment with gemcitabine and rhC4BPA increased PDAC cell apoptosis rate. mC4BPA peptide increased the number of murine T lymphocytes in vitro and the number of CD8⁺ tumor-infiltrating lymphocytes surrounding PDAC tumors in vivo. In a preclinical study, GnP/ICBs/mC4BPA peptide treatment, but not GnP treatment, led to the accumulation of a greater number of CD8⁺ T cells in the periphery of PDAC tumors and to greater tumor regression than did control treatment.

Conclusions

These findings demonstrate that the combination of GnP therapy with C4BPA inhibits PDAC progression by promoting antitumor T cell accumulation in the tumor microenvironment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02019-0.

Cell-specific and divergent roles of the CD40L-CD40 axis in atherosclerotic vascular disease

Atherosclerosis is a major underlying cause of cardiovascular disease. Previous studies showed that inhibition of the co-stimulatory CD40 ligand (CD40L)-CD40 signaling axis profoundly attenuates atherosclerosis. As CD40L exerts multiple functions depending on the cell-cell interactions involved, we sought to investigate the function of the most relevant CD40L-expressing cell types in atherosclerosis: T cells and platelets. Atherosclerosis-prone mice with a CD40L-deficiency in CD4⁺ T cells display impaired Th1 polarization, as reflected by reduced interferon-γ production, and smaller atherosclerotic plaques containing fewer T-cells, smaller necrotic cores, an increased number of smooth muscle cells and thicker fibrous caps. Mice with a corresponding CD40-deficiency in CD11c⁺ dendritic cells phenocopy these findings, suggesting that the T cell-dendritic cell CD40L-CD40 axis is crucial in atherogenesis. Accordingly, sCD40L/sCD40 and interferon-γ concentrations in carotid plaques and plasma are positively correlated in patients with cerebrovascular disease. Platelet-specific deficiency of CD40L does not affect atherogenesis but ameliorates atherothrombosis. Our results establish divergent and cell-specific roles of CD40L-CD40 in atherosclerosis, which has implications for therapeutic strategies targeting this pathway.

Follicular helper T cells: potential therapeutic targets in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease with joint and systemic inflammation that is accompanied by the production of autoantibodies, such as rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies. Follicular helper T (Tfh) cells, which are a subset of CD4+ T cells, facilitate germinal center (GC) reactions by providing signals required for high-affinity antibody production and the generation of long-lived antibody-secreting plasma cells. Uncontrolled expansion of Tfh cells is observed in various systemic autoimmune diseases. Particularly, the frequencies of circulating Tfh-like (cTfh-like) cells, their subtypes and synovial-infiltrated T helper cells correlate with disease activity in RA patients. Therefore, reducing autoantibody production and restricting excessive Tfh cell responses are ideal ways to control RA pathogenesis. The present review summarizes current knowledge of the involvement of Tfh cells in RA pathogenesis and highlights the potential of these cells as therapeutic targets.

The Role of the Proteasome in Platelet Function

Platelets are megakaryocyte-derived acellular fragments prepped to maintain primary hemostasis and thrombosis by preserving vascular integrity. Although they lack nuclei, platelets harbor functional genomic mediators that bolster platelet activity in a signal-specific manner by performing limited de novo protein synthesis. Furthermore, despite their limited protein synthesis, platelets are equipped with multiple protein degradation mechanisms, such as the proteasome. In nucleated cells, the functions of the proteasome are well established and primarily include proteostasis among a myriad of other signaling processes. However, the role of proteasome-mediated protein degradation in platelets remains elusive. In this review article, we recapitulate the developing literature on the functions of the proteasome in platelets, discussing its emerging regulatory role in platelet viability and function and highlighting how its functional coupling with the transcription factor NF-κB constitutes a novel potential therapeutic target in atherothrombotic diseases.

The associations between red cell distribution width and plasma proteins in a general population

BACKGROUND

High red cell distribution width (RDW) has been increasingly recognized as a risk factor for cardiovascular diseases (CVDs), but the underlying mechanisms remain unknown. Our aim was to explore the associations between RDW and plasma proteins implicated in the pathogenesis of CVD using a targeted proteomics panel.

METHODS

RDW and 88 plasma proteins were measured in a population-based cohort study (n = 4726), Malmö Diet and Cancer-Cardiovascular Cohort (MDC-CC). A random 2/3 of the cohort was used as discovery sample and remaining 1/3 was used for replication. Multiple linear regression was used to assess the associations between RDW and plasma proteins, with adjustments for age, sex, and other potential confounders. Proteins with Bonferroni-corrected significant associations with RDW in the discovery sub-cohort were validated in the replication cohort.

RESULTS

Thirteen of 88 plasma proteins had significant associations with RDW in the discovery sample, after multivariate adjustments. Eleven of them were also significant in the replication sample, including SIR2-like protein 2 (SIRT2), stem cell factor (SCF, inversely), melusin (ITGB1BP2), growth differentiation factor-15 (GDF-15), matrix metalloproteinase-7 (MMP-7), hepatocyte growth factor (HGF), chitinase-3-like protein 1 (CHI3L1), interleukin-8 (IL-8), CD40 ligand (CD40-L), urokinase plasminogen activator surface receptor (U-PAR) and matrix metalloproteinase-3 (MMP-3).

CONCLUSIONS

Several proteins from this targeted proteomics panel were associated with RDW in this cohort. These proteins could potentially be linked to the increased cardiovascular risk in individuals with high RDW.

Expression of mRNA TNFα and level of protein TNFα after exposure sCD40L in bone marrow mononuclear cells of myelodysplastic syndromes

Background

Cytopenia is the primary phenomenon in myelodysplastic syndrome (MDS) amidst hypercellular bone marrow. The soluble CD40 ligand (sCD40L) is considered as a cytokine that can trigger synthesis of tumor necrosis factor α (TNFα) that promotes apoptosis. The objective of this study is to prove that recombinant human sCD40L (rh-sCD40L) exposure on bone marrow mononuclear cells (BMMC) MDS increases TNFα expression at mRNA level and at protein level.

Methods

BMMC from MDS patients whom diagnosed and classified using the WHO 2008 criteria, were exposed to rh-sCD40L and antiCD40L. The expressions of TNFα mRNAs were quantified by qRT-PCR, level of TNFα were measured using the ELISA method.

Results

Exposure of rh-sCD40L significantly increased the expression of TNFα mRNA. The similar exposure also significantly increased the level of TNFα compared to controls. TNFα mRNA expression on BMMC in MDS samples exposed to rh-sCD40L is 3.32 times compared to TNFα mRNA expression without exposure. level of TNFα in supernatant media exposed to rh-sCD40L in MDS samples was higher than that of control samples which were 44.44 and 4.85 pg/mL, P=0.018.

Conclusions

The sCD40L plays a role in increasing the synthesis of TNFα in mRNA level and protein level in BMMC MDS.

Agonistic CD40 Antibodies in Cancer Treatment

Simple Summary

CD40 is a costimulatory molecule that is key for the activation of antigen-presenting cells and other innate immune cells. It plays an important role in anti-tumor immunity, and agonists of CD40 have been shown to eliminate tumors in both pre-clinical and clinical settings, alone and in combination with other treatment modalities. Here we assess the expression of CD40 and associations with other mediators of immunity in a variety of tumor types and review the potential of CD40 agonists for cancer treatment, given the promise of enhancing the interplay between innate and adaptive immunity.

Abstract

CD40 is expressed on a variety of antigen-presenting cells. Stimulation of CD40 results in inflammation by upregulation of other costimulatory molecules, increased antigen presentation, maturation (licensing) of dendritic cells, and activation of CD8+ T cells. Here we analyzed gene expression data from The Cancer Genome Atlas in melanoma, renal cell carcinoma, and pancreatic adenocarcinoma and found correlations between CD40 and several genes involved in antigen presentation and T cell function, supporting further exploration of CD40 agonists to treat cancer. Agonist CD40 antibodies have induced anti-tumor effects in several tumor models and the effect has been more pronounced when used in combination with other treatments (immune checkpoint inhibition, chemotherapy, and colony-stimulating factor 1 receptor inhibition). The reduction in tumor growth and ability to reprogram the tumor microenvironment in preclinical models lays the foundation for clinical development of agonistic CD40 antibodies (APX005M, ChiLob7/4, ADC-1013, SEA-CD40, selicrelumab, and CDX-1140) that are currently being evaluated in early phase clinical trials. In this article, we focus on CD40 expression and immunity in cancer, agonistic human CD40 antibodies, and their pre-clinical and clinical development. With the broad pro-inflammatory effects of CD40 and its ligand on dendritic cells and macrophages, and downstream B and T cell activation, agonists of this pathway may enhance the anti-tumor activity of other systemic therapies.

Effects and Side Effects of Platelet Transfusion

Aside from their canonical role in hemostasis, it is increasingly recognized that platelets have inflammatory functions and can regulate both adaptive and innate immune responses. The main topic this review aims to cover is the proinflammatory effects and side effects of platelet transfusion. Platelets prepared for transfusion are subject to stress injury upon collection, preparation, and storage. With these types of stress, they undergo morphologic, metabolic, and functional modulations which are likely to induce platelet activation and the release of biological response modifiers (BRMs). As a consequence, platelet concentrates (PCs) accumulate BRMs during processing and storage, and these BRMs are ultimately transfused alongside platelets. It has been shown that BRMs present in PCs can induce immune responses and posttransfusion reactions in the transfusion recipient. Several recent reports within the transfusion literature have investigated the concept of platelets as immune cells. Nevertheless, current and future investigations will face the challenge of encompassing the immunological role of platelets in the scope of transfusion.

ApoB-Specific CD4+ T Cells in Mouse and Human Atherosclerosis

Atherosclerosis is a chronic inflammatory condition of the arterial wall that leads to the formation of vessel-occluding plaques within the subintimal space of middle-sized and larger arteries. While traditionally understood as a myeloid-driven lipid-storage disease, growing evidence suggests that the accumulation of low-density lipoprotein cholesterol (LDL-C) ignites an autoimmune response with CD4+ T-helper (TH) cells that recognize self-peptides from Apolipoprotein B (ApoB), the core protein of LDL-C. These autoreactive CD4+ T cells home to the atherosclerotic plaque, clonally expand, instruct other cells in the plaque, and induce clinical plaque instability. Recent developments in detecting antigen-specific cells at the single cell level have demonstrated that ApoB-reactive CD4+ T cells exist in humans and mice. Their phenotypes and functions deviate from classical immunological concepts of distinct and terminally differentiated TH immunity. Instead, ApoB-specific CD4+ T cells have a highly plastic phenotype, can acquire several, partially opposing and mixed transcriptional programs simultaneously, and transit from one TH subset into another over time. In this review, we highlight adaptive immune mechanisms in atherosclerosis with a focus on CD4+ T cells, introduce novel technologies to detect ApoB-specific CD4+ T cells at the single cell level, and discuss the potential impact of ApoB-driven autoimmunity in atherosclerosis.

Inflammatory Cell Recruitment in Cardiovascular Disease

Atherosclerosis, the main underlying pathology for myocardial infarction and stroke, is a chronic inflammatory disease of middle-sized to large arteries that is initiated and maintained by leukocytes infiltrating into the subendothelial space. It is now clear that the accumulation of pro-inflammatory leukocytes drives progression of atherosclerosis, its clinical complications, and directly modulates tissue-healing in the infarcted heart after myocardial infarction. This inflammatory response is orchestrated by multiple soluble mediators that enhance inflammation systemically and locally, as well as by a multitude of partially tissue-specific molecules that regulate homing, adhesion, and transmigration of leukocytes. While numerous experimental studies in the mouse have refined our understanding of leukocyte accumulation from a conceptual perspective, only a few anti-leukocyte therapies have been directly validated in humans. Lack of tissue-tropism of targeted factors required for leukocyte accumulation and unspecific inhibition strategies remain the major challenges to ultimately translate therapies that modulate leukocytes accumulation into clinical practice. Here, we carefully describe receptor and ligand pairs that guide leukocyte accumulation into the atherosclerotic plaque and the infarcted myocardium, and comment on potential future medical therapies.

Inflammatory Markers Related to Innate and Adaptive Immunity in Atherosclerosis: Implications for Disease Prediction and Prospective Therapeutics

Several lines of evidence have linked a dysregulated inflammatory setting to the pathogenesis of atherosclerosis, which is a form of chronic vascular inflammation. Various inflammatory biomarkers have been associated with inflammation and are recognized as potential tools to monitor the progression of atherosclerosis. A well-studied inflammatory marker in the context of cardiovascular diseases is C-reactive protein (CRP) or, more accurately, highly sensitive-CRP (hs-CRP), which has been established as an inflammatory biomarker for atherosclerotic events. In addition, a growing body of investigations has attempted to disclose the potential of inflammatory cytokines, enzymes, and genetic polymorphisms related to innate and adaptive immunity as biomarkers for predicting the development of atherosclerosis. In this review article, we clarify both traditional and novel inflammatory biomarkers related to components of the innate and adaptive immune system that may mirror the progression or phases of atherosclerotic inflammation/lesions. Furthermore, the contribution of the inflammatory biomarkers in developing potential therapeutics against atherosclerotic treatment will be discussed.

Functional association of a CD40 gene single-nucleotide polymorphism with the pathogenesis of coronary heart disease

AIMS

Endothelial dysfunction is a major contributor to the pathogenesis of atherosclerosis. CD40-CD40 ligand interactions confer a pro-inflammatory phenotype to endothelial cells (ECs). Recently, a thymine to cytosine transition (-1T>C) in the Kozak sequence of the CD40 gene (rs1883832) has been associated with coronary heart disease (CHD) in an Asian population. As there are no reports yet regarding its role in other ethnic groups, this study determines if the -1T>C single-nucleotide polymorphism (SNP) could be a risk factor for CHD in Caucasians by performing an association study and elucidates its functional consequence in cultured ECs.

METHODS AND RESULTS

Molecular and biochemical techniques, cell adhesion assays were used for genotype-stratified human EC characterization. SNP distribution in Caucasians was examined in a hospital-based case-control CHD study and serum levels of soluble CD40 (sCD40) were quantified by ELISA. The SNP in the CD40 gene affected baseline CD40 protein abundance on ECs. There was a genotype-dependent difference in CD40-mediated expression of pro-inflammatory genes. Monocyte adhesion was highest on the surface of cells homozygous for the C allele. Homozygosity for the C allele was associated with significant 2.32-fold higher odds of developing CHD as compared to TT genotype carriers. sCD40 plasma levels were genotype-dependently elevated in CHD patients, indicating a possible prognostic value.

CONCLUSION

The C allele of the CD40 SNP provokes a pro-inflammatory EC phenotype, compensated by an enhanced CD40 shedding to neutralize excess CD40 ligand. Homozygosity for the C allele is the cause for a genetic susceptibility to atherosclerosis and its sequelae.

Soluble CD40 ligand expression in stable atherosclerosis: A systematic review and meta-analysis

BACKGROUND AND AIMS

The role of inflammation in atherosclerosis development and expression in different arterial territories is unclear. Soluble CD40 ligand (sCD40L) mediates inflammation and atherogenesis. Through a systematic review and meta-analysis, we assessed whether sCD40L was dysregulated in stable atherosclerosis, irrespective of the diseased arterial territory, and whether this dysregulation differed according to the specific territory.

METHODS

Systematic literature searches were performed in MEDLINE, Cochrane Library, Web of Science, and Embase for studies reporting circulating sCD40L levels in individuals with and without stable atherosclerosis. sCD40L levels were compared using random-effects meta-analysis, weighted by the inverse variance method (study protocol: PROSPERO CRD42020181392).

RESULTS

Fifty-four studies (59 estimates) including 7705 patients and 7841 controls were analyzed. sCD40L levels were found to be increased in patients with atherosclerosis, irrespective of the territory (standardized mean difference [SMD] 0.43, 95% CI 0.29-0.57; 59 estimates; χ² heterogeneity p < 0.001; I² = 92%). SMD was greatest in carotid atherosclerosis (SMD 0.58, 95% CI 0.30-0.86; 17 estimates), followed by coronary (SMD 0.43, 95% CI 0.24-0.62; 33 estimates), lower extremity (SMD 0.26, 95% CI -0.02-0.54; 7 estimates), and renal atherosclerosis (SMD -0.07, 95% CI -2.77-2.64; 2 estimates) (χ² heterogeneity p < 0.001; I² ≥ 80% for all). Subgroup analysis revealed that sCD40L levels were increased in clinical, but not subclinical, atherosclerosis.

CONCLUSIONS

sCD40L levels were increased in stable atherosclerosis, particularly in the carotid and coronary territories. These novel data support sCD40L as a marker of systemic atherosclerosis, possibly with differential roles in specific territories.

CD40/CD40L and Related Signaling Pathways in Cardiovascular Health and Disease-The Pros and Cons for Cardioprotection

The CD40-CD40 ligand (CD40L) dyad represents a scientific and clinical field that has raised many controversies in the past and cannot be clearly defined as being an either beneficial or harmful pathway. Being crucially involved in physiological immunological processes as well as pathological inflammatory reactions, the signaling pathway has been recognized as a key player in the development of both autoimmune and cardiovascular disease. Even though the possibilities of a therapeutic approach to the dyad were recognized decades ago, due to unfortunate events, detailed in this review, pharmacological treatment targeting the dyad, especially in patients suffering from atherosclerosis, is not available. Despite the recent advances in the treatment of classical cardiovascular risk factors, such as arterial hypertension and diabetes mellitus, the treatment of the associated low-grade inflammation that accounts for the progression of atherosclerosis is still challenging. Low-grade inflammation can be detected in a significant portion of patients that suffer from cardiovascular disease and it is therefore imperative to develop new therapeutic strategies in order to combat this driver of atherosclerosis. Of note, established cardiovascular drugs such as angiotensin-converting enzyme inhibitors or statins have proven beneficial cardiovascular effects that are also related to their pleiotropic immunomodulatory properties. In this review, we will discuss the setbacks encountered as well as new avenues discovered on the path to a different, inflammation-centered approach for the treatment of cardiovascular disease with the CD40-CD40L axis as a central therapeutic target.

Endothelial dysfunction in neuroprogressive disorders-causes and suggested treatments

BACKGROUND

Potential routes whereby systemic inflammation, oxidative stress and mitochondrial dysfunction may drive the development of endothelial dysfunction and atherosclerosis, even in an environment of low cholesterol, are examined.

MAIN TEXT

Key molecular players involved in the regulation of endothelial cell function are described, including PECAM-1, VE-cadherin, VEGFRs, SFK, Rho GEF TRIO, RAC-1, ITAM, SHP-2, MAPK/ERK, STAT-3, NF-κB, PI3K/AKT, eNOS, nitric oxide, miRNAs, KLF-4 and KLF-2. The key roles of platelet activation, xanthene oxidase and myeloperoxidase in the genesis of endothelial cell dysfunction and activation are detailed. The following roles of circulating reactive oxygen species (ROS), reactive nitrogen species and pro-inflammatory cytokines in the development of endothelial cell dysfunction are then described: paracrine signalling by circulating hydrogen peroxide, inhibition of eNOS and increased levels of mitochondrial ROS, including compromised mitochondrial dynamics, loss of calcium ion homeostasis and inactivation of SIRT-1-mediated signalling pathways. Next, loss of cellular redox homeostasis is considered, including further aspects of the roles of hydrogen peroxide signalling, the pathological consequences of elevated NF-κB, compromised S-nitrosylation and the development of hypernitrosylation and increased transcription of atherogenic miRNAs. These molecular aspects are then applied to neuroprogressive disorders by considering the following potential generators of endothelial dysfunction and activation in major depressive disorder, bipolar disorder and schizophrenia: NF-κB; platelet activation; atherogenic miRs; myeloperoxidase; xanthene oxidase and uric acid; and inflammation, oxidative stress, nitrosative stress and mitochondrial dysfunction.

CONCLUSIONS

Finally, on the basis of the above molecular mechanisms, details are given of potential treatment options for mitigating endothelial cell dysfunction and activation in neuroprogressive disorders.