CXC chemokine ligand 12 (CXCL12) in atherosclerosis: An underlying therapeutic target

Disturbed shear stress promotes atherosclerosis through TRIM21-regulated MAPK6 degradation and consequent endothelial inflammation

RATIONALE

Coronary artery plaques often develop in regions subjected to disturbed shear stress (DSS), yet the mechanisms underlying this phenomenon remain poorly understood. Our study aimed to elucidate the unknown role of MAPK6 in shear stress and plaque formation.

METHODS

In vitro and in vivo experiments, RNA-seq, CO-IP and proteomic analysis, combined with single-cell RNA-seq datasets were used to reveal the upstream and downstream mechanisms involved. AAV-MAPK6, ApoE-/-MAPK6flox/floxTEKCre mice and the CXCL12 neutraligand were used to confirm the beneficial effects of MAPK6 against atherosclerosis.

RESULTS

Our study revealed a substantial decrease in MAPK6 protein levels in endothelial cells in response to DSS, both in vivo and in vitro, which was contingent on the binding of the ubiquitin ligase TRIM21 to MAPK6. Endothelium-specific MAPK6 overexpression exerts antiatherosclerotic effects in ApoE-/- mice, elucidating the unexplored role of MAPK6 in atherosclerosis. Comprehensive RNA-seq, integrated single-cell mapping and further experiments unveiled the involvement of MAPK6 in inflammation through the EGR1/CXCL12 axis. ApoE-/-MAPK6flox/floxTEKCre mice finally confirmed that conditional MAPK6 knockout resulted in endothelial inflammation and significant increases in plaque areas. Notably, these effects could be reversed through the neutralization of CXCL12.

CONCLUSIONS

Our study illuminates the advantages of MAPK6 in decelerating plaque progression, highlighting the potential of safeguarding MAPK6 as a novel therapeutic strategy against atherosclerosis.

KEY POINTS

Disturbed flow activates the ubiquitin‒proteasome degradation pathway of MAPK6 in endothelial cells, which is contingent on the binding of the ubiquitin ligase TRIM21 to MAPK6. Endothelial MAPK6 has an advantageous impact on decelerating plaque progression. MAPK6 regulates endothelial inflammation via the EGR1/CXCL12 axis.

Elucidating the role of chemokines in inflammaging associated atherosclerotic cardiovascular diseases

Age-related inflammation or inflammaging is a critical deciding factor of physiological homeostasis during aging. Cardiovascular diseases (CVDs) are exquisitely associated with aging and inflammation and are one of the leading causes of high mortality in the elderly population. Inflammaging comprises dysregulation of crosstalk between the vascular and cardiac tissues that deteriorates the vasculature network leading to development of atherosclerosis and atherosclerotic-associated CVDs in elderly populations. Leukocyte differentiation, migration and recruitment holds a crucial position in both inflammaging and atherosclerotic CVDs through relaying the activity of an intricate network of inflammation-associated protein-protein interactions. Among these interactions, small immunoproteins such as chemokines play a major role in the progression of inflammaging and atherosclerosis. Chemokines are actively involved in lymphocyte migration and severe inflammatory response at the site of injury. They relay their functions via chemokine-G protein-coupled receptors-glycosaminoglycan signaling axis and is a principal part for the detection of age-related atherosclerosis and related CVDs. This review focuses on highlighting the detailed intricacies of the effects of chemokine-receptor interaction and chemokine oligomerization on lymphocyte recruitment and its evident role in clinical manifestations of atherosclerosis and related CVDs. Further, the role of chemokine mediated signaling for formulating next-generation therapeutics against atherosclerosis has also been discussed.

Peripheral inflammatory response in people after acute ischaemic stroke and isolated spontaneous cervical artery dissection

The systemic inflammatory response following acute ischaemic stroke remains incompletely understood. We characterised the circulating inflammatory profile in 173 acute ischaemic stroke patients by measuring 65 cytokines and chemokines in plasma. Participants were grouped based on their inflammatory response, determined by high-sensitivity C-reactive protein levels in the acute phase. We compared stroke patients' profiles with 42 people experiencing spontaneous cervical artery dissection without stroke. Furthermore, variations in cytokine levels among stroke aetiologies were analysed. Follow-up samples were collected in a subgroup of ischaemic stroke patients at three and twelve months. Ischaemic stroke patients had elevated plasma levels of HGF and SDF-1α, and lower IL-4 levels, compared to spontaneous cervical artery dissection patients without stroke. Aetiology-subgroup analysis revealed reduced levels of nine cytokines/chemokines (HGF, SDF-1α, IL-2R, CD30, TNF-RII, IL-16, MIF, APRIL, SCF), and elevated levels of IL-4 and MIP-1β, in spontaneous cervical artery dissection (with or without ischaemic stroke as levels were comparable between both groups) compared to other aetiologies. The majority of cytokine/chemokine levels remained stable across the study period. Our research indicates that stroke due to large artery atherosclerosis, cardioembolism, and small vessel occlusion triggers a stronger inflammatory response than spontaneous cervical artery dissection.

Integrated systems biology approach identifies gene targets for endothelial dysfunction

Endothelial dysfunction (ED) is critical in the development and progression of cardiovascular (CV) disorders, yet effective therapeutic targets for ED remain elusive due to limited understanding of its underlying molecular mechanisms. To address this gap, we employed a systems biology approach to identify potential targets for ED. Our study combined multi omics data integration, with siRNA screening, high content imaging and network analysis to prioritise key ED genes and identify a pro- and anti-ED network. We found 26 genes that, upon silencing, exacerbated the ED phenotypes tested, and network propagation identified a pro-ED network enriched in functions associated with inflammatory responses. Conversely, 31 genes ameliorated ED phenotypes, pointing to potential ED targets, and the respective anti-ED network was enriched in hypoxia, angiogenesis and cancer-related processes. An independent screen with 17 drugs found general agreement with the trends from our siRNA screen and further highlighted DUSP1, IL6 and CCL2 as potential candidates for targeting ED. Overall, our results demonstrate the potential of integrated system biology approaches in discovering disease-specific candidate drug targets for endothelial dysfunction.

Prognostic significance of plasma SDF-1 in acute ischemic stroke patients with diabetes mellitus: the CATIS trial

BACKGROUND AND OBJECTIVES

Evidence on the associations between baseline stromal cell-derived factor (SDF)-1 and clinical outcomes in acute ischemic stroke patients is lacking. The present study aimed to examine the relationship between plasma SDF-1 levels and clinical outcomes based on a large multicenter study of the China Antihypertensive Trial in Acute Ischemic Stroke (CATIS).

METHODS

Secondary analysis was conducted among 3,255 participants from the CATIS trial with a baseline measurement of plasma SDF-1 levels. We evaluated the associations between plasma SDF-1 levels and one-year recurrent stroke, cardiovascular events, and all-cause mortality using Cox regression models. We further investigated the prognostic effect of SDF-1 on clinical outcomes in patients with different characteristics.

RESULTS

Higher plasma SDF-1 levels were not associated with recurrent stroke, cardiovascular events, and all-cause mortality at one-year after ischemic stroke (all P trend ≥ 0.05). There were significant interactions between plasma SDF-1 levels and history of diabetes mellitus on recurrent stroke (P = 0.005), cardiovascular events (P = 0.007) and all-cause mortality (P = 0.04) at one year. In patients with diabetes mellitus, plasma SDF-1 was significantly associated with an increased risk of recurrent stroke and cardiovascular events after adjustment for confounders. For example, 1-SD higher log-SDF-1 was associated with a hazard ratio (95% confidence interval) of 1.65 (1.18-2.32) for recurrent stroke and 1.47 (1.08-1.99) for the cardiovascular events, but not all-cause mortality 1.36 (0.96-1.93) at one year. However, there were no associations between plasma SDF-1 and clinical outcomes in patients without diabetes mellitus (all P > 0.05). The addition of plasma SDF-1 to the conventional risk factors model significantly improved the risk prediction of all outcomes. Similarly, findings between elevated SDF-1 levels and two-year outcomes were found only in patients with diabetes mellitus.

CONCLUSIONS

Elevated plasma SDF-1 was significantly associated with an increased risk of recurrent stroke and cardiovascular events only in ischemic patients with diabetes mellitus.

SFRP4 Reduces Atherosclerosis Plaque Formation in ApoE Deficient Mice

Secreted frizzled related protein 4 (SFRP4), a member of the SFRPs family, contributes to a significant function in metabolic and cardiovascular diseases. However, there is not enough evidence to prove the antiatherosclerosis effect of SFRP4 in ApoE knock-out (KO) mice. ApoE KO mice were fed a western diet and injected adenovirus (Ad)-SFRP4 through the tail vein for 12 weeks. Contrasted with the control cohort, the area of atherosclerotic plaque in ApoE KO mice overexpressing SFRP4 was reduced significantly. Plasma high-density lipoprotein cholesterol was elevated in the Ad-SFRP4 group. RNA sequence analysis indicated that there were 96 differentially expressed genes enriched in 10 signaling pathways in the mRNA profile of aortic atherosclerosis lesions. The analysis data also revealed the expression of a number of genes linked to metabolism, organism system, and human disease. In summary, our data demonstrates that SFRP4 could play an important role in improving atherosclerotic plaque formation in the aorta.

Recovery of systemic hyperinflammation in patients with severe SARS-CoV-2 infection

INTRODUCTION

Patients with cardiovascular disease (CVD) and acute SARS-CoV-2 infection might show an altered immune response during COVID-19.

MATERIAL AND METHODS

Twenty-three patients with CVD and SARS-CoV-2 infection were prospectively enrolled and received a cardiological assessment at study entry and during follow-up visit. Inclusion criteria of our study were age older than 18 years, presence of CVD, and acute SARS-CoV-2 infection. The median age of the patient cohort was 69 (IQR 55-79) years. 12 (52.2%) patients were men. Peripheral monocytes and chemokine/cytokine profiles were analysed.

RESULTS

Numbers of classical and non-classical monocytes were significantly decreased during acute SARS-CoV-2 infection compared to 3-month recovery. While classical monocytes reached the expected level in peripheral blood after 3 months, the number of non-classical monocytes remained significantly reduced.

DISCUSSION

All three monocyte subsets exhibited changes of established adhesion and activation markers. Interestingly, they also expressed higher levels of pro-inflammatory cytokines like macrophage migration inhibitory factor (MIF) at the time of recovery, although MIF was only slightly increased during the acute phase.

CONCLUSION

Changes of monocyte phenotypes and increased MIF expression after 3-month recovery from acute SARS-CoV-2 infection may indicate persistent, possibly long-lasting, pro-inflammatory monocyte function in CVD patients.

Tramadol regulates the activation of human platelets via Rac but not Rho/Rho-kinase

Tramadol is a useful analgesic which acts as a serotonin and noradrenaline reuptake inhibitor in addition to μ-opioid receptor agonist. Cytoplasmic serotonin modulates the small GTPase activity through serotonylation, which is closely related to the human platelet activation. We recently reported that the combination of subthreshold collagen and CXCL12 synergistically activates human platelets. We herein investigated the effect and the mechanism of tramadol on the synergistic effect. Tramadol attenuated the synergistically stimulated platelet aggregation (300 μM of tramadol, 64.3% decrease, p<0.05). Not morphine or reboxetine, but duloxetine, fluvoxamine and sertraline attenuated the synergistic effect of the combination on the platelet aggregation (30 μM of fluvoxamine, 67.3% decrease, p<0.05; 30 μM of sertraline, 67.8% decrease, p<0.05). The geranylgeranyltransferase inhibitor GGTI-286 attenuated the aggregation of synergistically stimulated platelet (50 μM of GGTI-286, 80.8% decrease, p<0.05), in which GTP-binding Rac was increased. The Rac1-GEF interaction inhibitor NSC23766 suppressed the platelet activation and the phosphorylation of p38 MAPK and HSP27 induced by the combination of collagen and CXCL12. Tramadol and fluvoxamine almost completely attenuated the levels of GTP-binding Rac and the phosphorylation of both p38 MAPK and HSP27 stimulated by the combination. Suppression of the platelet aggregation after the duloxetine administration was observed in 2 of 5 patients in pain clinic. These results suggest that tramadol negatively regulates the combination of subthreshold collagen and CXCL12-induced platelet activation via Rac upstream of p38 MAPK.

Correlations Between Serum CXCL9/12 and the Severity of Acute Ischemic Stroke, a Retrospective Observational Study

PURPOSE

This retrospective observational study was conducted to determine the correlations between serum CXCL9/12 and the severity of acute ischemic stroke (AIS).

METHODS

Total 138 patients with AIS were enrolled in the study. These patients underwent Brain CT on admission and blood samples were collected. Serum CXCL9 and CXCL12 were detected by ELISA assay. The correlations of serum CXCL9/12 with AIS was analyzed based on Oxfordshire Community Stroke Project (OCSP) classification, Trial of Org 10,172 in acute stroke treatment (TOAST) classification, National Institutes of Health Stroke Score (NIHSS) score, infarct volume, and modified Rankin scale (mRS) score.

RESULTS

Compared with the controls, patients with AIS had higher levels of serum CXCL9 and CXCL12. Logistic regression analysis determined that CXCL9 and CXCL12 were independent risk factors for AIS. In addition, the increased serum CXCL9 and CXCL12 were associated with TOAST classification, NIHSS score, and infarct volume. However, serum CXCL9 and CXCL12 were not associated with functional outcomes (mRS score). CXCL9 and CXCL12 both exhibited a high diagnostic value in AIS.

CONCLUSION

Serum CXCL9 and CXCL12 were elevated in patients with AIS, closely correlated with the severity of AIS.

Trans-interaction of risk loci 6p24.1 and 10q11.21 is associated with endothelial damage in coronary artery disease

BACKGROUND AND AIMS

Single nucleotide polymorphism rs6903956 has been identified as one of the genetic risk factors for coronary artery disease (CAD). However, rs6903956 lies in a non-coding locus on chromosome 6p24.1. We aim to interrogate the molecular basis of 6p24.1 containing rs6903956 risk alleles in endothelial disease biology.

METHODS AND RESULTS

We generated induced pluripotent stem cells (iPSCs) from CAD patients (AA risk genotype at rs6903956) and non-CAD subjects (GG non-risk genotype at rs6903956). CRISPR-Cas9-based deletions (Δ63-89bp) on 6p24.1, including both rs6903956 and a short tandem repeat variant rs140361069 in linkage disequilibrium, were performed to generate isogenic iPSC-derived endothelial cells. Edited CAD endothelial cells, with removal of 'A' risk alleles, exhibited a global transcriptional downregulation of pathways relating to abnormal vascular physiology and activated endothelial processes. A CXC chemokine ligand on chromosome 10q11.21, CXCL12, was uncovered as a potential effector gene in CAD endothelial cells. Underlying this effect was the preferential inter-chromosomal interaction of 6p24.1 risk locus to a weak promoter of CXCL12, confirmed by chromatin conformation capture assays on our iPSC-derived endothelial cells. Functionally, risk genotypes AA/AG at rs6903956 were associated significantly with elevated levels of circulating damaged endothelial cells in CAD patients. Circulating endothelial cells isolated from patients with risk genotypes AA/AG were also found to have 10 folds higher CXCL12 transcript copies/cell than those with non-risk genotype GG.

CONCLUSIONS

Our study reveals the trans-acting impact of 6p24.1 with another CAD locus on 10q11.21 and is associated with intensified endothelial injury.

Chemokine Homeostasis in Healthy Volunteers and during Pancreatic and Colorectal Tumor Growth in Murine Models

Chemokines are involved in the humoral regulation of body homeostasis. Changes in the blood level of chemokines were found in cancer, atherosclerosis, diabetes, and other systemic diseases. It is essential to distinguish the effects of co-morbid pathologies and cancer on the level of chemokines in the blood. We aimed to analyze, by multiplex cytometry, the levels of chemokines in the blood of healthy young volunteers as well as of intact mice and mice with CT26 colon and Pan02 pancreatic tumors. Two types of chemokines were identified both in human and murine plasmas: homeostatic ones, which were found in high concentrations (>100 pg/mL), and inducible ones, which can be undetectable or determined at very low levels (0−100 pg/mL). There was a high variability in the chemokine levels, both in healthy humans and mice. To analyze chemokine levels during tumor growth, C57BL/6 and BALB/c were inoculated with Pan02 or CT26 tumor cells, accordingly. The tumors significantly differed in the growth and the mortality of mice. However, the blood chemokine levels did not change in tumor-bearing mice until the very late stages. Taken collectively, blood chemokine level is highly variable and reflects in situ homeostasis. Care should be taken when considering chemokines as prognostic parameters or therapeutic targets in cancer.

Circulating Ageing Neutrophils as a Marker of Asymptomatic Polyvascular Atherosclerosis in Statin-Naïve Patients without Established Cardiovascular Disease

Background: Current data on the possible involvement of aging neutrophils in atherogenesis are limited. This study aimed to research the diagnostic value of aging neutrophils in their relation to subclinical atherosclerosis in statin-naïve patients without established atherosclerotic cardiovascular diseases (ASCVD). Methods: The study was carried out on 151 statin-naïve patients aged 40–64 years old without ASCVD. All patients underwent duplex scanning of the carotid arteries, lower limb arteries and abdominal aorta. Phenotyping and differentiation of neutrophil subpopulations were performed through flow cytometry (Navios 6/2, Beckman Coulter, USA). Results: The number of CD62L^loCXCR4^hi-neutrophils is known to be significantly higher in patients with subclinical atherosclerosis compared with patients without atherosclerosis (p = 0.006). An increase in the number of CD62L^loCXCR4^hi-neutrophils above cut-off values makes it possible to predict atherosclerosis in at least one vascular bed with sensitivity of 35.4–50.5% and specificity of 80.0–92.1%, in two vascular beds with sensitivity of 44.7–84.4% and specificity of 80.8–33.3%. Conclusion: In statin-naïve patients 40–64 years old without established ASCVD with subclinical atherosclerosis, there is an increase in circulating CD62L^loCXCR4^hi-neutrophils. It was also concluded that the increase in the number of circulating CD62L^loCXCR4^hi-neutrophils demonstrated moderate diagnostic efficiency (AUC 0.617–0.656) in relation to the detection of subclinical atherosclerosis, including polyvascular atherosclerosis.

The role of blood CXCL12 level in prognosis of coronary artery disease: A meta-analysis

Objective

The role of C-X-C motif chemokine 12 (CXCL12) in atherosclerotic cardiovascular diseases (ASCVDs) has emerged as one of the research hotspots in recent years. Studies reported that the higher blood CXCL12 level was associated with increased major adverse cardiovascular events (MACEs), but the results were inconsistent. The objective of this study was to clarify the prognostic value of the blood CXCL12 level in patients with coronary artery disease (CAD) through meta-analysis.

Methods

All related studies about the association between the blood CXCL12 level and the prognosis of CAD were comprehensively searched and screened according to inclusion criteria and exclusion criteria. The quality of the included literature was evaluated using the Newcastle-Ottawa Scale (NOS). The heterogeneity test was conducted, and the pooled hazard risk (HR) or the odds ratio (OR) with a 95% confidence interval (CI) was calculated using the fixed-effect or random-effects model accordingly. Publication bias was evaluated using Begg's funnel plot and Egger's test. Sensitivity analysis and subgroup analysis were also conducted.

Results

A total of 12 original studies with 2,959 CAD subjects were included in the final data combination. The pooled data indicated a significant association between higher CXCL12 levels and MACEs both in univariate analysis (HR 5.23, 95% CI 2.48–11.04) and multivariate analysis (HR 2.53, 95% CI 2.03–3.16) in the CXCL12 level as the category variable group. In the CXCL12 level as the continuous variable group, the result also indicated that the higher CXCL12 level significantly predicted future MACEs (multivariate OR 1.55, 95% CI 1.02–2.35). Subgroup analysis of the CXCL12 level as the category variable group found significant associations in all acute coronary syndrome (ACS) (univariate HR 9.72, 95% CI 4.69–20.15; multivariate HR 2.47, 95% CI 1.79–3.40), non-ACS (univariate HR 2.73, 95% CI 1.65–4.54; multivariate HR 3.49, 95% CI 1.66–7.33), Asian (univariate HR 7.43, 95% CI 1.70–32.49; multivariate HR 2.21, 95% CI 1.71–2.85), Caucasian (univariate HR 3.90, 95% CI 2.73–5.57; multivariate HR 3.87, 95% CI 2.48–6.04), short-term (univariate HR 9.36, 95% CI 4.10–21.37; multivariate HR 2.72, 95% CI 1.97–3.76), and long-term (univariate HR 2.86, 95% CI 1.62–5.04; multivariate HR 2.38, 95% CI 1.76–3.22) subgroups. Subgroup analysis of the CXCL12 level as the continuous variable group found significant associations in non-ACS (multivariate OR 1.53, 95% CI 1.23–1.92), Caucasian (multivariate OR 3.83, 95% CI 1.44–10.19), and long-term (multivariate OR 1.62, 95% CI 1.37–1.93) subgroups, but not in ACS (multivariate OR 1.36, 95% CI 0.67–2.75), Asian (multivariate OR 1.40, 95% CI 0.91–2.14), and short-term (multivariate OR 1.16, 95% CI 0.28–4.76) subgroups. No significant publication bias was found in this meta-analysis.

Conclusion

The higher blood CXCL12 level is associated with increased MACEs in patients with CAD, and the blood CXCL12 level may serve as an important prognostic index for CAD. Integrating the blood CXCL12 level into CAD risk assessment tools may provide more comprehensive messages for evaluating and managing patients with CAD.

Macrophage-Specific IGF-1 Overexpression Reduces CXCL12 Chemokine Levels and Suppresses Atherosclerotic Burden in Apoe-Deficient Mice

OBJECTIVE

IGF-1 (insulin-like growth factor 1) exerts pleiotropic effects including promotion of cellular growth, differentiation, survival, and anabolism. We have shown that systemic IGF-1 administration reduced atherosclerosis in Apoe^-/- (apolipoprotein E deficient) mice, and this effect was associated with a reduction in lesional macrophages and a decreased number of foam cells in the plaque. Almost all cell types secrete IGF-1, but the effect of macrophage-derived IGF-1 on the pathogenesis of atherosclerosis is poorly understood. We hypothesized that macrophage-derived IGF-1 will reduce atherosclerosis. Approach and Results: We created macrophage-specific IGF-1 overexpressing mice on an Apoe^-/- background. Macrophage-specific IGF-1 overexpression reduced plaque macrophages, foam cells, and atherosclerotic burden and promoted features of stable atherosclerotic plaque. Macrophage-specific IGF1 mice had a reduction in monocyte infiltration into plaque, decreased expression of CXCL12 (CXC chemokine ligand 12), and upregulation of ABCA1 (ATP-binding cassette transporter 1), a cholesterol efflux regulator, in atherosclerotic plaque and in peritoneal macrophages. IGF-1 prevented oxidized lipid-induced CXCL12 upregulation and foam cell formation in cultured THP-1 macrophages and increased lipid efflux. We also found an increase in cholesterol efflux in macrophage-specific IGF1-derived peritoneal macrophages.

CONCLUSIONS

Macrophage IGF-1 overexpression reduced atherosclerotic burden and increased features of plaque stability, likely via a reduction in CXCL12-mediated monocyte recruitment and an increase in ABCA1-dependent macrophage lipid efflux.

Role and implications of the CXCL12/CXCR4/CXCR7 axis in atherosclerosis: still a debate

Atherosclerosis is one of the leading causes of mortality and morbidity worldwide. Chemokines and their receptors are implicated in the pathogenesis of atherosclerosis. CXCL12 is a member of the chemokine family exerting a myriad role in atherosclerosis through its classical CXCR4 and atypical ACKR3 (CXCR7) receptors. The modulatory and regulatory functional spectrum of CXCL12/CXCR4/ACKR3 axis in atherosclerosis spans from proatherogenic, prothrombotic and proinflammatory to atheroprotective, plaque stabilizer and dyslipidemia rectifier. This diverse continuum is executed in a wide range of biological units including endothelial cells (ECs), progenitor cells, macrophages, monocytes, platelets, lymphocytes, neutrophils and vascular smooth muscle cells (VSMCs) through complex heterogeneous and homogenous coupling of CXCR4 and ACKR3 receptors, employing different downstream signalling pathways, which often cross-talk among themselves and with other signalling interactomes. Hence, a better understanding of this structural and functional heterogeneity and complex phenomenon involving CXCL12/CXCR4/ACKR3 axis in atherosclerosis would not only help in formulation of novel therapeutics, but also in elucidation of the CXCL12 ligand and its receptors, as possible diagnostic and prognostic biomarkers.Key messagesThe role of CXCL12 per se is proatherogenic in atherosclerosis development and progression.The CXCL12 receptors, CXCR4 and ACKR3 perform both proatherogenic and athero-protective functions in various cell typesDue to functional heterogeneity and cross talk of CXCR4 and ACKR3 at receptor level and downstream pathways, regional boosting with specific temporal and spatial modulators of CXCL12, CXCR4 and ACKR3 need to be explored.

The potential targets in immunotherapy of atherosclerosis

Cardiovascular disease is the most common cause of death, which has the highest mortality rate worldwide. Although a diverse range of inflammatory diseases can affect the cardiovascular system, however, heart failure and stroke occur due to atherosclerosis. Atherosclerosis is a chronic autoinflammatory disease of small to large vessels in which different immune mediators are involved in lipid plaque formation and inflammatory vascular remodeling process. A better understanding of the pathophysiology of atherosclerosis may lead to uncovering immunomodulatory therapies. Despite present diagnostic and therapeutic methods, the lack of immunotherapy in the prevention and treatment of atherosclerosis is perceptible. In this review, we will discuss the promising immunological-based therapeutics and novel preventive approaches for atherosclerosis. This study could provide new insights into a better perception of targeted therapeutic pathways and biological therapies.

lncRNA MEG3 aggravated neuropathic pain and astrocyte overaction through mediating miR-130a-5p/CXCL12/CXCR4 axis

OBJECTIVE

Long non-coding RNAs (lncRNAs) exert a critical function in mediating neuropathic pain (NP). MEG3, a novel lncRNA, contributes to astrocyte activation and inflammation. However, its role in NP remains unclear.

METHODS

The chronic constriction injury (CCI) method was employed to construct an NP rat model. Astrocyte activation was induced by lipopolysaccharide (LPS). The profiles of MEG3, microRNA (miR)-130a-5p, CXC motif chemokine receptor 12 (CXCL12)/CXC motif chemokine receptor 4 (CXCR4), and the Rac1/NF-κB pathway in CCI rats' spinal cord tissues and astrocytes were monitored by reverse transcription-quantitative PCR (RT-qPCR) and western blot (WB). Pain scores of CCI rats were assessed. Enzyme-linked immunosorbent assay (ELISA) was adopted to monitor neuroinflammation alteration. The glial fibrillary acidic protein (GFAP)-labeled astrocytes were tested by immunohistochemistry (IHC). Bioinformatics, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) were utilized to verify the molecular mechanism between MEG3 and miR-130a-3p.

RESULTS

MEG3, CXCL12 and CXCR4 were overexpressed and miR-130a-5p was knocked down in CCI rats and LPS-induced astrocytes. Up-regulating MEG3 aggravated NP, enhanced inflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor (TNF)-α, and interleukin-6 (IL-6) expression and release in CCI rats and LPS-induced astrocytes. Up-regulating miR-130-5p repressed LPS-induced inflammation in astrocytes. AS verified by the dual-luciferase reporter assay and RIP assay, MEG3 sponged miR-130a-5p as a competitive endogenous RNA (ceRNA). What's more, miR-130a-5p up-regulation weakened the MEG3-induced proinflammatory effects on LPS-induced astrocytes.

CONCLUSIONS

MEG3 aggravates NP and astrocyte activation via the miR-130a-5p/CXCL12/CXCR4 axis, which is a potential therapeutic target for NP.

Cardiovascular disease related circulating biomarkers and cancer incidence and mortality: is there an association?

AIMS

Recent studies suggest an association between cardiovascular disease (CVD) and cancer incidence/mortality, but the pathophysiological mechanisms underlying these associations are unclear. We aimed to examine biomarkers previously associated with CVD and study their association with incident cancer and cancer-related death in a prospective cohort study.

METHODS AND RESULTS

We used a proteomic platform to measure 71 cardiovascular biomarkers among 5,032 participants in the Framingham Heart Study who were free of cancer at baseline. We used multivariable-adjusted Cox models to examine the association of circulating protein biomarkers with risk of cancer incidence and mortality. To account for multiple testing, we set a 2-sided false discovery rate (FDR Q-value) <0.05.Growth differentiation factor-15 (GDF15; also known as macrophage inhibitory cytokine-1 [MIC1])) was associated with increased risk of incident cancer (hazards ratio [HR] per 1 standard deviation increment 1.31, 95% CI 1.17-1.47), incident gastrointestinal cancer (HR 1.85, 95% CI 1.37-2.50), incident colorectal cancer (HR 1.94, 95% CI 1.29-2.91) and cancer-related death (HR 2.15, 95% CI 1.72-2.70). Stromal cell-derived factor-1 (SFD1) showed an inverse association with cancer-related death (HR 0.75, 95% CI 0.65-0.86). Fibroblast growth factor-23 (FGF23) showed an association with colorectal cancer (HR 1.55, 95% CI 1.20-2.00), and granulin (GRN) was associated with hematologic cancer (HR 1.61, 95% CI 1.30-1.99). Other circulating biomarkers of inflammation, immune activation, metabolism, and fibrosis showed suggestive associations with future cancer diagnosis.

CONCLUSION

We observed several significant associations between circulating CVD biomarkers and cancer, supporting the idea that shared biological pathways underlie both diseases. Further investigations of specific mechanisms that lead to both CVD and cancer are warranted.

TRANSLATIONAL PERSPECTIVE

In our prospective cohort study, baseline levels of biomarkers previously associated with CVD were found to be associated with future development of cancer. In particular, GDF15 was associated with increased risk of cancer incidence and mortality, including gastrointestinal and colorectal cancers; SDF1 was inversely associated with cancer-related death, and FGF23 and GRN were associated with increased risk of colorectal and hematologic cancers, respectively. Other biomarkers of inflammation, immune activation, metabolism, and fibrosis showed suggestive associations. These results suggest potential shared biological pathways that underlie both development of cancer and CVD.

C-C Motif Chemokine 8 promotes angiogenesis in vascular endothelial cells

OBJECTIVES

Angiogenesis is an important progress associated with several pathological situations. Several chemokines have been reported to act as regulators of angiogenesis. The current study aimed to find whether C-C Motif Chemokine 8 is involved in angiogenesis regulation.

METHODS

To verify whether C-C Motif Chemokine 8 is related to angiogenesis in plaques, carotid plaques were collected from patients with severe carotid stenosis and analysed using CD31 immunohistochemistry and real-time PCR. To further clarify the relation between C-C Motif Chemokine 8 and angiogenesis, human umbilical vein endothelium cells and human dermal microvascular endothelial cells were treated with C-C Motif Chemokine 8 in the presence or absence of C-C motif chemokine receptor 2-Ab and extracellular regulated MAP kinase 1/2 inhibition (FR180204). Proliferation and migration of human umbilical vein endothelium cells and human dermal microvascular endothelial cells were examined with Cell Counting Kit-8 and Transwell chamber assay, respectively. In vitro angiogenesis stimulated by C-C Motif Chemokine 8 was examined using tube formation assay. Ex vivo and in vivo angiogenesis were assessed by mice aortic ring assay and Matrigel plug assay, respectively. C-C motif chemokine receptors of human umbilical vein endothelium cells were examined with real-time PCR, and C-C motif chemokine receptor 1, C-C motif chemokine receptor 2, extracellular regulated MAP kinase 1/2 and phosphorylation-extracellular regulated MAP kinase 1/2 were examined with western blotting assay.

RESULTS

C-C Motif Chemokine 8 was increased in carotid plaques with severe angiogenesis in both RNA and protein level. C-C Motif Chemokine 8 (5 ng/ml) weakly increased human umbilical vein endothelium cell proliferation, but not on human dermal microvascular endothelial cells. Migration and tube formation could be induced by C-C Motif Chemokine 8 in both human umbilical vein endothelium cells and human dermal microvascular endothelial cells. In mice aortic ring assay and Matrigel plug assay, C-C Motif Chemokine 8 could promote angiogenesis compared to vehicle groups. Phosphorylation of extracellular regulated MAP kinase 1/2 was increased with C-C Motif Chemokine 8 stimulation. The migration and tube formation promoted by C-C Motif Chemokine 8 could be largely blocked by C-C motif chemokine receptor 2-Ab or extracellular regulated MAP kinase 1/2 inhibition (FR180204).

CONCLUSIONS

C-C Motif Chemokine 8 could promote both in vitro and in vivo angiogenesis. C-C motif chemokine receptor 2 played an important role in the activation of C-C Motif Chemokine 8 and extracellular regulated MAP kinase 1/2 signalling pathway was involved in this mechanism.

Association of SDF1 and MMP12 with Atherosclerosis and Inflammation: Clinical and Experimental Study

BACKGROUND

Atherosclerosis is the main etiology of cardiovascular diseases (CVD), associated to systemic inflammation. Matrix metalloproteinases (MMPs) are related to atherosclerosis progression through the SDF1/CXCR4 axis promoting macrophages recruitment within the vascular wall. The goal was to assess new circulatory inflammatory markers in relation to atherosclerosis.

METHODS

Measurement of SDF1, MMP12 and CRP in blood samples of 298 prospective patients with cardiovascular risk. To explore atherosclerosis progression, CXCR4/SDF1 axis and MMP12 expression were determined by RT-qPCR and by immunohistochemistry in the aorta of accelerated and delayed atherosclerosis mice models (Apoe-/- and Apoe-/-Mmp10-/-).

RESULTS

SDF1, MMP12 and CRP were elevated in patients with clinical atherosclerosis, but after controlling by confounding factors, only SDF1 and CRP remained increased. Having high levels of both biomarkers showed 2.8-fold increased risk of presenting clinical atherosclerosis (p = 0.022). Patients with elevated SDF1, MMP12 and CRP showed increased risk of death in follow-up (HR = 3.2, 95%CI: 1.5-7.0, p = 0.004). Gene and protein expression of CXCR4 and MMP12 were increased in aortas from Apoe-/- mice.

CONCLUSIONS

The combination of high circulating SDF1, MMP12 and CRP identified patients with particular inflammatory cardiovascular risk and increased mortality. SDF1/CXCR4 axis and MMP12 involvement in atherosclerosis development suggests that they could be possible atherosclerotic targets.

Hsa_circ_0004831 downregulation is partially responsible for atorvastatinalleviated human umbilical vein endothelial cell injuries induced by ox-LDL through targeting the miR-182-5p/CXCL12 axis

BACKGROUND

The dysfunction and injury of human umbilical vein endothelial cells (HUVECs) are key events of atherosclerosis (AS). Atorvastatin (ATV) has been shown to play a protective role on endothelial cells. However, the associated molecular mechanisms remain not fully illustrated.

METHODS

HUVECs were treated with oxidized low-density lipoprotein (ox-LDL) to mimic the pathological conditions of endothelial cell injury in AS. Cell injuries were assessed according to cell viability, cell apoptosis, cycle progression, oxidative stress and inflammatory responses using CCK-8 assay, flow cytometry assay or commercial kits. The expression of hsa_circ_0004831, miR-182-5p, and C-X-C motif chemokine 12 (CXCL12) mRNA was examined using quantitative real-time PCR (qPCR). The expression of CXCL12 protein was quantitated by western blot. The predicted target relationship between miR-182-5p and hsa_circ_0004831 or CXCL12 was verified by pull-down assay, dual-luciferase reporter assay or RIP assay.

RESULTS

The expression of hsa_circ_0004831 was upregulated by ox-LDL but downregulated by ATV in HUVECs. ATV promoted cell viability and cell cycle progression but inhibited apoptosis, oxidative stress and inflammation in ox-LDL-treated HUVECs, while the role of ATV was partially reversed by hsa_circ_0004831 overexpression. MiR-182-5p was targeted by hsa_circ_0004831, and hsa_circ_0004831 overexpression-restored apoptosis, oxidative stress and inflammation were blocked by miR-182-5p restoration. Further, CXCL12 was targeted by miR-182-5p, and miR-182-5p inhibition-stimulated apoptosis, oxidative stress and inflammation were lessened by CXCL12 knockdown.

CONCLUSION

Hsa_circ_0004831-targeted miR-182-5p/CXCL12 regulatory network is one of the pathways by which ATV protects against ox-LDL-induced endothelial injuries.

Chemokine Therapy in Cats With Experimental Renal Fibrosis and in a Kidney Disease Pilot Study

Background: Chronic tubulointerstitial fibrosis is a common final pathway leading to end stage kidney disease in cats and has no effective treatment. The use of cell-based molecules to treat kidney fibrosis may be a promising approach. The objectives were to test the effects of intra-renal chemokine CXCL12 injection in a pre-clinical cat model of unilateral ischemia/reperfusion (I/R)-induced kidney fibrosis and then, within a clinical pilot study, test the safety/feasibility of CXCL12 injection in cats that might have early chronic kidney disease (CKD). Methods: Pre-clinical: Thirty cats received intra-renal injection of 100, 200, or 400 ng of recombinant human CXCL12, or sterile saline, into the I/R kidney 70 days post-injury, or were non-injured, non-injected controls (n = 6/group). Kidney collagen content was quantified 4 months post-treatment using Masson's Trichrome and Picrosirius Red (PSR) stained tissues. In a separate study (n = 2) exploring short-term effects of CXCL12, 200 ng CXCL12 was injected into I/R kidneys and then harvested either 30 min (n = 1) or 1 month (n = 1) post-injection. Kidney concentrations of CXCL12, matrix metalloproteinase 1 (MMP-1), and lysyl oxidase-like enzyme 2 (LOXL-2) were quantified via ELISA. Clinical Pilot: 14 client-owned cats with potential early kidney disease received a single-treatment, bilateral intra-renal injection of 200 ng CXCL12 (n = 7), or received no injection (n = 7). Blood/urine samples were collected monthly for 9 months to assess renal function and CKD staging. Results: Pre-clinical: I/R increased the affected kidney collagen content, which both mid and high doses of CXCL12 restored to normal (ps < 0.05 vs. untreated). I/R increased collagen fiber width, which both mid and high doses of CXCL12 restored to normal (p < 0.001 vs. untreated). Early changes in kidney MMP-1, associated with collagen breakdown, and subsequent decreases in LOXL-2, associated with collagen cross-linking, in response to CXCL12 treatment may contribute to these findings. Clinical Pilot: Bilateral intra-renal injection of CXCL12 using ultrasound guidance in cats with CKD was feasible and safe in a general practice clinical setting with no obvious side effects noted during the 9-month follow-up period. Conclusions: Intra-renal injection of CXCL12 may prove to be an effective treatment for kidney fibrosis in cats with CKD. Additional mechanistic and clinical evaluations are needed.

Synergistic effect of collagen and CXCL12 in the low doses on human platelet activation

CXCL12, also known as stromal cell-derived factor-1, is a chemokine classified into CXC families, which exerts its function by binding to specific receptors called CXCR4 and CXCR7. Human platelets express CXCR4 and CXCR7 on the plasma membrane. It has been reported that CXCL12 potentiates to induce platelet aggregation in cooperation with agonists including collagen. However, the precise roles and mechanisms of CXCL12 in human platelet activation are not fully elucidated. In the present study, we investigated the effect of simultaneous stimulation with low doses of collagen and CXCL12 on the activation of human platelets. The simultaneous stimulation with collagen and CXCL12 induced the secretion of platelet-derived growth factor (PDGF)-AB and the release of soluble CD40 ligand (sCD40L) from human platelets in addition to their aggregation, despite the fact that the simultaneous stimulation with thrombin receptor-activating peptide (TRAP) or adenosine diphosphate (ADP), and CXCL12 had little effects on the platelet aggregation. The agonist of Glycoprotein (GP) Ⅵ convulxin and CXCL12 also induced platelet aggregation synergistically. The monoclonal antibody against CXCR4 but not CXCR7 suppressed the platelet aggregation induced by simultaneous stimulation with collagen and CXCL12. The phosphorylation of p38 mitogen-activated protein kinase (MAPK), but not p44/p42 MAPK, was induced by the simultaneous stimulation. In addition, the simultaneous stimulation with collagen and CXCL12 induced the phosphorylation of HSP27 and the subsequent release of phosphorylated-HSP27 from human platelets. SB203580, a specific inhibitor of p38 MAPK, attenuated the platelet aggregation, the phosphorylation of p38 MAPK and HSP27, the PDGF-AB secretion, the sCD40L release and the phosphorylated-HSP27 release induced by the simultaneous stimulation with collagen and CXCL12. These results strongly suggest that collagen and CXCL12 in low doses synergistically act to induce PDGF-AB secretion, sCD40L release and phosphorylated-HSP27 release from activated human platelets via p38 MAPK activation.

PD-1/PD-L1 in cardiovascular disease

The PD-1/PD-L1 coinhibitory pathway has critical roles in the immune response and autoimmunity via the regulation of T cell activity. Excessive activity and high expression of this pathway suppresses the function of T cells and immunity. Recent research has indicated that tumour cells express high levels of PD-L1, which has an immunosuppressive effect and can result in treatment failure. Anti-PD-L1 or anti-PD-1 agents have well-established beneficial effects on mortality and quality of life in cancer patients. Based on the regulatory effects and therapeutic value of the PD-1/PD-L1 pathway in malignant disorders, we propose that it also regulates cell immunity and in CHD and atherosclerosis. Low expression level of PD-1/ PD-L1 or anti-PD-1/PD-L1 therapy accelerates the immune processes in CHD and aggravates disease according to numerous studies. A few studies have provided strong evidence that changes in the expression levels of PD-1 or PD-L1 can alter the degree of inflammation and the state of coronary plaques in atherosclerosis. In this review, we summarise the alterations of the PD-1/PD-L1 pathway and discuss its role in CHD.

Limb functional recovery is impaired in fibroblast growth factor-2 (FGF2) deficient mice despite chronic ischaemia-induced vascular growth

FGF2 is a potent stimulator of vascular growth; however, even with a deficiency of FGF2 (Fgf2-/-), developmental vessel growth or ischaemia-induced revascularization still transpires. It remains to be elucidated as to what function, if any, FGF2 has during ischaemic injury. Wildtype (WT) or Fgf2-/- mice were subjected to hindlimb ischaemia for up to 42 days. Limb function, vascular growth, inflammatory- and angiogenesis-related proteins, and inflammatory cell infiltration were assessed in sham and ischaemic limbs at various timepoints. Recovery of ischaemic limb function was delayed in Fgf2-/- mice. Yet, vascular growth response to ischaemia was similar between WT and Fgf2-/- hindlimbs. Several angiogenesis- and inflammatory-related proteins (MCP-1, CXCL16, MMPs and PAI-1) were increased in Fgf2-/- ischaemic muscle. Neutrophil or monocyte recruitment/infiltration was elevated in Fgf2-/- ischaemic muscle. In summary, our study indicates that loss of FGF2 induces a pro-inflammatory microenvironment in skeletal muscle which exacerbates ischaemic injury and delays functional limb use.

Foam cells promote atherosclerosis progression by releasing CXCL12

BACKGROUND

Atherosclerosis (AS) is a chronic inflammatory disease that contributes to multiple cardiovascular diseases (CVDs), and foam cell formation plays important roles in the progression of AS. There is an urgent need to identify new molecular targets for treating AS, and thereby improve the quality of life and reduce the financial burden of individuals with CVD.

METHODS

An in vitro model of AS was generated by treating THP-1 cells and human aortic vascular smooth muscle cells (HA-VSMCs) with oxidized low-density lipoproteins (ox-LDLs). HA-VSMC proliferation and foam cell formation were detected by the MTT assay and Oil Red O staining. C-X-C motif chemokine 12 (CXCL12) expression was suppressed by siRNA. An AS rat model was established by feeding rats a high-fat diet and vitamin D2 for 3 weeks. Histopathology examinations were conducted by Hematoxylin and Eosin (H&E) staining and the levels ionized calcium-binding adapter molecule 1 (IBA1) and α smooth muscle actin (α-SMA) expression were determined by ELISA assays and immunohistochemistry.

RESULTS

An in vitro model of AS was established with THP-1 cells. CXCL12 expression in the model THP-1 cells was significantly increased when compared with its expression in control cells. Suppression of CXCL12 expression reduced the progression of AS in the cell model. Moreover, CXCL12 promoted AS in the in vivo rat model.

CONCLUSION

Our results suggest that CXCL12 plays an important role in promoting the progression of AS. Furthermore, inhibition of CXCL12 might suppress the development of AS by inhibiting HA-VSMC proliferation and their transformation to foam cells.

CXCL12 promotes atherosclerosis by downregulating ABCA1 expression via the CXCR4/GSK3β/β-cateninT120/TCF21 pathway

CXC chemokine ligand 12 (CXCL12) is a member of the CXC chemokine family and mainly acts on cell chemotaxis. CXCL12 also elicits a proatherogenic role, but the molecular mechanisms have not been fully defined yet. We aimed to reveal if and how CXCL12 promoted atherosclerosis via regulating lipid metabolism. In vitro, our data showed that CXCL12 could reduce ABCA1 expression, and it mediated cholesterol efflux from THP-1-derived macrophages to apoA-I. Data from the luciferase reporter gene and chromatin immunoprecipitation assays revealed that transcription factor 21 (TCF21) stimulated the transcription of ABCA1 via binding to its promoter region, which was repressed by CXCL12. We found that CXCL12 increased the levels of phosphorylated glycogen synthase kinase 3β (GSK3β) and the phosphorylation of β-catenin at the Thr120 position. Inactivation of GSK3β or β-catenin increased the expression of TCF21 and ABCA1. Further, knockdown or inhibition of CXC chemokine receptor 4 (CXCR4) blocked the effects of CXCL12 on TCF21 and ABCA1 expression and the phosphorylation of GSK3β and β-catenin. In vivo, the overexpression of CXCL12 in Apoe^-/- mice via lentivirus enlarged the atherosclerotic lesion area and increased macrophage infiltration in atherosclerotic plaques. We further found that the overexpression of CXCL12 reduced the efficiency of reverse cholesterol transport and plasma HDL-C levels, decreased ABCA1 expression in the aorta and mouse peritoneal macrophages (MPMs), and suppressed cholesterol efflux from MPMs to apoA-I in Apoe^-/- mice. Collectively, these findings suggest that CXCL12 interacts with CXCR4 and then activates the GSK-3β/β-catenin^T120/TCF21 signaling pathway to inhibit ABCA1-dependent cholesterol efflux from macrophages and aggravate atherosclerosis. Targeting CXCL12 may be a novel and promising strategy for the prevention and treatment of atherosclerotic cardiovascular diseases.