Soluble CD40 Levels in Plasma Are Associated with Cardiovascular Disease and in Carotid Plaques with a Vulnerable Phenotype

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.

Costimulatory and Coinhibitory Immune Checkpoints in Atherosclerosis: Therapeutic Targets in Atherosclerosis?

The benefits of current state-of-the-art treatments to combat atherosclerotic cardiovascular disease (ASCVD) have stagnated. Treatments are mostly based on controlling cardiovascular risk factors, especially hyperlipidemia. Although the most recent advances with PCSK-9 inhibitors support the hyperlipidemia aspect of ASCVD, several lines of experimental evidence have outlined that atherosclerosis is also driven by inflammation. In the past years, phase 1, 2, and 3 clinical trials targeting inflammation to combat ASCVD have revealed that patients do tolerate such immune therapies, show decreases in inflammatory markers, and/or have reductions in cardiovascular endpoints. However, the search for the optimal anti-inflammatory or immune-modulating strategy and the stratification of patients who would benefit from such treatments and appropriate treatment regimens to combat ASCVD is only just beginning. In this review, we focus on immune checkpoint-based therapeutics (costimulation and coinhibition), many of which are already approved by the U.S. Food and Drug Administration for the treatment of cancer or autoimmune diseases, and discuss their use as a novel immunotherapeutic strategy to treat ASCVD.

Co-stimulators CD40-CD40L, a potential immune-therapy target for atherosclerosis: A review

The interaction between CD40 and CD40 ligand (CD40L) a crucial co-stimulatory signal for activating adaptive immune cells, has a noteworthy role in atherosclerosis. It is well-known that atherosclerosis is linked to immune inflammation in blood vessels. In atherosclerotic lesions, there is a multitude of proinflammatory cytokines, adhesion molecules, and collagen, as well as smooth muscle cells, macrophages, and T lymphocytes, particularly the binding of CD40 and CD40L. Therefore, research on inhibiting the CD40-CD40L system to prevent atherosclerosis has been ongoing for more than 30 years. However, it's essential to note that long-term direct suppression of CD40 or CD40L could potentially result in immunosuppression, emphasizing the critical role of the CD40-CD40L system in atherosclerosis. Thus, specifically targeting the CD40-CD40L interaction on particular cell types or their downstream signaling pathways may be a robust strategy for mitigating atherosclerosis, reducing potential side effects. This review aims to summarize the potential utility of the CD40-CD40L system as a viable therapeutic target for atherosclerosis.

Potential role of soluble CD40 receptor in chronic inflammatory diseases

The CD40 receptor and its ligand CD154 are widely expressed in various immune-competent cells. Interaction of CD154 with CD40 is essential for B-cell growth, differentiation, and immunoglobulin class switching. Many other immune-competent cells involved in innate and adaptive immunity communicate through this co-stimulatory ligand-receptor dyad. CD40-CD154 interaction is involved in the pathogenesis of numerous inflammatory and autoimmune diseases. While CD40 and CD154 are membrane-bound proteins, their soluble counterparts are generated by proteolytic cleavage or alternative splicing. This review summarises current knowledge about the impact of single nucleotide polymorphisms in the human CD40 gene and compensatory changes in the plasma level of the soluble CD40 receptor (sCD40) isoform in related pro-inflammatory diseases. It discusses regulation patterns of the disintegrin metalloprotease ADAM17 function leading to ectodomain shedding of transmembrane proteins, such as pro-inflammatory adhesion molecules or CD40. The role of sCD40 as a potential biomarker for chronic inflammatory diseases will also be discussed.

Sex-specific differences in cytokine signaling pathways in circulating monocytes of cardiovascular disease patients

BACKGROUND AND AIMS

This study aims to identify sex-specific transcriptional differences and signaling pathways in circulating monocytes contributing to cardiovascular disease.

METHODS AND RESULTS

We generated sex-biased gene expression signatures by comparing male versus female monocytes of coronary artery disease (CAD) patients (n = 450) from the Center for Translational Molecular Medicine-Circulating Cells Cohort. Gene set enrichment analysis demonstrated that monocytes from female CAD patients carry stronger chemotaxis and migratory signature than those from males. We then inferred cytokine signaling activities based on CytoSig database of 51 cytokine and growth factor regulation profiles. Monocytes from females feature a higher activation level of EGF, IFN1, VEGF, GM-CSF, and CD40L pathways, whereas IL-4, INS, and HMGB1 signaling was seen to be more activated in males. These sex differences were not observed in healthy subjects, as shown for an independent monocyte cohort of healthy subjects (GSE56034, n = 485). More pronounced GM-CSF signaling in monocytes of female CAD patients was confirmed by the significant enrichment of GM-CSF-activated monocyte signature in females. As we show these effects were not due to increased plasma levels of the corresponding ligands, sex-intrinsic differences in monocyte signaling regulation are suggested. Consistently, regulatory network analysis revealed jun-B as a shared transcription factor activated in all female-specific pathways except IFN1 but suppressed in male-activated IL-4.

CONCLUSIONS

We observed overt CAD-specific sex differences in monocyte transcriptional profiles and cytokine- or growth factor-induced responses, which provide insights into underlying mechanisms of sex differences in CVD.

Stratification of Patients with Coronary Artery Disease by Circulating Cytokines Profile: A Pilot Study

Coronary artery disease (CAD) is a long-term inflammatory process, with atherosclerosis as its underlying pathophysiological mechanism. Endothelial dysfunction is the first step towards atherosclerosis, where damaged endothelial cells release large amounts of pro-inflammatory cytokines and mediators, thus promoting vascular inflammation and disease progression. However, the correlation between serum cytokines and CAD severity remains to be defined. Serum samples from patients performing cardiac computed tomography for suspected CAD (n = 75) were analyzed with a multiplex bead-based immunoassay panel for simultaneous assessment of the concentration of 11 cytokines using flow cytometric technology. The analysis showed statistically significant increases in sRAGE, CCL2_MCP1, FLT1, and IL6 levels in CAD patients compared with healthy subjects and a gradual increase trend towards a more severe form of the disease for most cytokines (e.g., sCD40L, FLT1, sRAGE, CCL2-MCP1, TNFα). Lastly, we explored the performance of cytokines in predicting the diagnosis of CAD and found that an increase in IL6 levels will increase the odds of being non-obstructive CAD-positive. In contrast, an increase in CCL2-MCP1 or FLT1 levels will increase the probability of being obstructive CAD-positive. These results suggest that the combination of serum cytokines may contribute to the not-invasive stratification risk for patients with suspected CAD.

Ferroptosis: A potential target of macrophages in plaque vulnerability

Plaque vulnerability has been the subject of several recent studies aimed at reducing the risk of stroke and carotid artery stenosis. Atherosclerotic plaque development is a complex process involving inflammation mediated by macrophages. Plaques become more vulnerable when the equilibrium between macrophage recruitment and clearance is disturbed. Lipoperoxides, which are affected by iron levels in cells, are responsible for the cell death seen in ferroptosis. Ferroptosis results from lipoperoxide-induced mitochondrial membrane toxicity. Atherosclerosis in ApoE(-/-) mice is reduced when ferroptosis is inhibited and iron intake is limited. Single-cell sequencing revealed that a ferroptosis-related gene was substantially expressed in atherosclerosis-modeled macrophages. Since ferroptosis can be regulated, it offers hope as a non-invasive method of treating carotid plaque. In this study, we discuss the role of ferroptosis in atherosclerotic plaque vulnerability, including its mechanism, regulation, and potential future research directions.

Ectodomain Shedding by ADAM17 Increases the Release of Soluble CD40 from Human Endothelial Cells under Pro-Inflammatory Conditions

BACKGROUND

Homozygosity for the C allele of the -1T>C single nucleotide polymorphism (SNP) of the CD40 gene (rs1883832) is associated with susceptibility to coronary heart disease (CHD), enhanced CD40 expression, and shedding. The disintegrin metalloprotease ADAM17 can cleave various cell surface proteins. This study investigates an association between ADAM17-mediated CD40 shedding and inflammation in CC genotype human endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVEC) carrying the CC genotype were stimulated with soluble CD40 ligand (sCD40L) or tumor necrosis factor-α (TNFα). Messenger RNA and protein expression were determined with standard methods. Levels of high sensitive c-reactive protein (hs-CRP), interleukin-6 (IL-6), and sCD40 in plasma samples from patients with CHD were assessed using ELISA.

RESULTS

ADAM17 surface abundance was elevated following stimulation with CD40L and TNFα just as its regulator iRhom2. Inhibition of ADAM17 prevented TNFα-induced sCD40 and soluble vascular cell adhesion molecule-1 release into the conditioned medium and reinforced CD40 surface abundance. Secondary to inhibition of ADAM17, stimulation with CD40L or TNFα upregulated monocyte chemoattractant protein-1 mRNA and protein. Levels of sCD40 and the inflammatory biomarkers hs-CRP and IL-6 were positively correlated in the plasma of patients with CHD.

CONCLUSIONS

We provide a mechanism by which membrane-bound CD40 is shed from the endothelial cell surface by ADAM17, boosting sCD40 formation and limiting downstream CD40 signaling. Soluble CD40 may represent a robust biomarker for CHD, especially in conjunction with homozygosity for the C allele of the -1T>C SNP of the CD40 gene.

Vulnerable Atherosclerotic Plaque: Is There a Molecular Signature?

Atherosclerosis and its clinical manifestations, coronary and cerebral artery diseases, are the most common cause of death worldwide. The main pathophysiological mechanism for these complications is the rupture of vulnerable atherosclerotic plaques and subsequent thrombosis. Pathological studies of the vulnerable lesions showed that more frequently, plaques rich in lipids and with a high level of inflammation, responsible for mild or moderate stenosis, are more prone to rupture, leading to acute events. Identifying the vulnerable plaques helps to stratify patients at risk of developing acute vascular events. Traditional imaging methods based on plaque appearance and size are not reliable in prediction the risk of rupture. Intravascular imaging is a novel technique able to identify vulnerable lesions, but it is invasive and an operator-dependent technique. This review aims to summarize the current data from literature regarding the main biomarkers involved in the attempt to diagnose vulnerable atherosclerotic lesions. These biomarkers could be the base for risk stratification and development of the new therapeutic drugs in the treatment of patients with vulnerable atherosclerotic plaques.

Clonal haematopoiesis is associated with higher mortality in patients with cardiogenic shock

AIMS

Cardiogenic shock (CS) with variable systemic inflammation may be responsible for the patient heterogeneity and the exceedingly high mortality rate. Cardiovascular events have been associated with clonal haematopoiesis (CH) where specific gene mutations in hematopoietic stem cells lead to clonal expansion and the development of inflammation. This study aims to assess the prevalence of CH and its association with survival in a population of CS patients in a quaternary center.

METHODS

We compared the frequency of CH mutations among 341 CS patients and 345 ambulatory heart failure (HF) matched for age, sex, ejection fraction, and HF aetiology. The association of CH with survival and levels of circulating inflammatory cytokines was analysed.

RESULTS

We detected 266 CH mutations in 149 of 686 (22%) patients. CS patients had a higher prevalence of CH-related mutations than HF patients (OR 1.5; 95% CI 1.0-2.1, P=0.02) and was associated with decreased survival (30-days: HR 2.7; 95% CI 1.3-5.7, P=0.006; 90-days: HR 2.2; 95% CI 1.3-3.9, P=0.003; and 3-years: HR 1.7; 95% CI 1.1-2.8, P=0.01). TET2 or ASXL1 mutations were associated with lower survival in CS patients at all-time points (P≤0.03). CS patients with TET2 mutations had higher circulating levels of SCD40L, IFNγ, IL-4, and TNFα (P≤0.04), while those with ASXL1 mutations had decreased levels of CCL7 (P=0.03).

CONCLUSIONS

CS patients have high frequency of CH, notably mutations in TET2 and ASXL1. This was associated with reduced survival and dysregulation of circulating inflammatory cytokines in those CS patients with CH. This article is protected by copyright. All rights reserved.

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.