Expression of platelet-bound stromal-cell derived factor-1 (SDF-1) and number of CD34+progenitor cells in patients with congestive heart failure

Construction of Immune-Related ceRNA Network in Dilated Cardiomyopathy: Based on Sex Differences

Background: Immune targeted therapy has become an attractive therapeutic approach for patients with dilated cardiomyopathy (DCM) recently. Genetic predisposition and gender play a critical role in immune-related responses of DCM. This study aimed to perform a bioinformatics analysis of molecular differences between male and female samples and identify immune-related ceRNA network in DCM.

Methods: The gene expression microarray and clinical features dataset of GSE19303 was downloaded from the GEO. The raw data were preprocessed, followed by identification of differentially expressed genes (DEGs) between male and female DCM samples. Crucial functions and pathway enrichment analysis of DEGs were investigated through GO analysis and KEGG pathway analysis, respectively. A lncRNA–miRNA–mRNA network was constructed and a central module was extracted from the ceRNA network.

Results: Compared with the female group, the male group benefits more from IA/IgG immunotherapy. Male patients of DCM had a significant positive correlation with the abundance of inflammatory cells (B cells, memory B cells, CD8⁺ Tem cells, and NK cells). Sex difference DEGs had a widespread impact on the signaling transduction, transcriptional regulation, and metabolism in DCM. Subsequently, we constructed an immune-related ceRNA network based on sex differences in DCM, including five lncRNAs, six miRNAs, and 29 mRNAs. Furthermore, we extracted a central module from the ceRNA network, including two lncRNAs (XIST and LINC00632), three miRNAs (miR-1-3p, miR-17-5p, and miR-22-3p), and six mRNAs (CBL, CXCL12, ESR1, IGF1R, IL6ST, and STC1). Among these DEGs, CBL, CXCL12, and IL6ST expression was considered to be associated with inflammatory cell infiltration in DCM.

Conclusions: The identified ceRNA network and their enriched pathways may provide genetic insights into the phenotypic diversity of female and male patients with DCM and may provide a basis for development of sex-related individualization of immunotherapy.

MiRNA126 - RGS16 - CXCL12 Cascade as a Potential Mechanism of Acute Exercise-Induced Precursor Cell Mobilization

Acute exercise enhances circulating stem and precursor cells (CPCs) in the peripheral blood. The responsible mechanisms and molecular pathways, however, have not been fully identified. The aim of the present study was to investigate a pathway related to elevated levels of apoptotic peripheral blood mononuclear cells (MNCs) and their secretome. An increased uptake of miRNA126 in MNCs was suggested to lead to reduced levels of RGS16 mRNA and, in turn, an enhanced translation and secretion of CXCL12. Eighteen healthy, young men underwent two identical incremental cycling exercises of which the first served as control while the second was preceded by a 7-day-long antioxidative supplementation. Blood samples were collected at baseline (−10min) and several time points after exercise (0, 30, 90, 180, and 270min). Relative concentrations of miRNA126 in MNCs and CXCL12 levels in plasma were determined at all time points while RGS16 mRNA was assessed in MNCs at baseline and 30min after exercise. CXCL12 increased after exercise and strongly correlated with CPC numbers. MiRNA126 increased 30min and, to a lesser extent, also 180 and 270min after exercise but only with supplementation. RGS16 mRNA decreased 30min after exercise independent of the intervention. The amount of RGS16 mRNA inversely correlated with levels of miRNA126, but not with plasma CXCL12. In conclusion, even though plasma CXCL12 correlated with CPC numbers, the increase in CXCL12 cannot be explained by the increased concentration of miRNA126 and lower RGS16 mRNA in MNCs that would have allowed for an enhanced translation of CXCL12.

Clinical Trial Registration: ClinicalTrials.gov, NCT03747913. Registered 20 November 2018, https://clinicaltrials.gov/ct2/show/NCT03747913.

Interleukin-17A Triggers the Release of Platelet-Derived Factors Driving Vascular Endothelial Cells toward a Pro-Angiogenic State

Platelets comprise a highly interactive immune cell subset of the circulatory system traditionally known for their unique haemostatic properties. Although platelets are considered as a vault of growth factors, cytokines and chemokines with pivotal role in vascular regeneration and angiogenesis, the exact mechanisms by which they influence vascular endothelial cells (ECs) function remain underappreciated. In the present study, we examined the role of human IL-17A/IL-17RA axis in platelet-mediated pro-angiogenic responses. We reveal that IL-17A receptor (IL-17RA) mRNA is present in platelets transcriptome and a profound increase is documented on the surface of activated platelets. By quantifying the protein levels of several factors, involved in angiogenesis, we identified that IL-17A/IL17RA axis selectively induces the release of vascular endothelial growth factor, interleukin -2 and -4, as well as monocyte chemoattractant protein -1 from treated platelets. However, IL-17A exerted no effect on the release of IL-10, an anti-inflammatory factor with potentially anti-angiogenic properties, from platelets. Treatment of human endothelial cell two-dimensional tubule networks or three-dimensional spheroid and mouse aortic ring structures with IL-17A-induced platelet releasate evoked pro-angiogenic responses of ECs. Our findings suggest that IL-17A may critically affect platelet release of pro-angiogenic factors driving ECs towards a pro-angiogenic state.

Platelets Boost Recruitment of CD133+ Bone Marrow Stem Cells to Endothelium and the Rodent Liver-The Role of P-Selectin/PSGL-1 Interactions

We previously demonstrated that clinical administration of mobilized CD133⁺ bone marrow stem cells (BMSC) accelerates hepatic regeneration. Here, we investigated the potential of platelets to modulate CD133⁺BMSC homing to hepatic endothelial cells and sequestration to warm ischemic livers. Modulatory effects of platelets on the adhesion of CD133⁺BMSC to human and mouse liver-sinusoidal- and micro- endothelial cells (EC) respectively were evaluated in in vitro co-culture systems. CD133⁺BMSC adhesion to all types of EC were increased in the presence of platelets under shear stress. This platelet effect was mostly diminished by antagonization of P-selectin and its ligand P-Selectin-Glyco-Ligand-1 (PSGL-1). Inhibition of PECAM-1 as well as SDF-1 receptor CXCR4 had no such effect. In a model of the isolated reperfused rat liver subsequent to warm ischemia, the co-infusion of platelets augmented CD133⁺BMSC homing to the injured liver with heightened transmigration towards the extra sinusoidal space when compared to perfusion conditions without platelets. Extravascular co-localization of CD133⁺BMSC with hepatocytes was confirmed by confocal microscopy. We demonstrated an enhancing effect of platelets on CD133⁺BMSC homing to and transmigrating along hepatic EC putatively depending on PSGL-1 and P-selectin. Our insights suggest a new mechanism of platelets to augment stem cell dependent hepatic repair.

CXCL12 in Patients with Chronic Kidney Disease and Healthy Controls: Relationships to Ambulatory 24-Hour Blood Pressure and Echocardiographic Measures

BACKGROUND/AIMS

Chronic kidney disease is a pro-inflammatory condition where the interplay between different regulatory pathways and immune cells mediates an unfavorable remodeling of the vascular wall and myocardial hypertrophy. These mechanisms include the action of CXCL12. The aim of this study is to evaluate the association between serum CXCL12 with left ventricular hypertrophy (LVH) and blood pressure control in chronic kidney disease (CKD) patients.

METHODS

This single-center observational study involved 90 stable CKD stage 1-5 patients (including 33 renal transplant recipients) and 25 healthy age- and sex-matched control subjects. CXCL12 was quantified by ELISA. 24-h ambulatory blood pressure monitoring was performed in 90 patients and 25 healthy controls. Left ventricular mass index (LVMI) was calculated based on the transthoracic echocardiography measurements in 27 patients out of the CKD population and in the whole control group.

RESULTS

CXCL12 correlated significantly with LVMI by multivariate regression analysis (coefficient B = 0.33, p = 0.02) together with age (B = 0.30, p = 0.03) and gender (B = 0.41, p = 0.003). A positive correlation was observed between CXCL12 and average 24-h systolic blood pressure (SBP) (rho = 0.35, p = 0.001), daytime SBP (rho = 0.35, p = 0.001), and nocturnal SBP (rho = 0.30, p = 0.002). Nocturnal hypertension was frequent (46% of CKD patients).

CONCLUSIONS

The results of our study point towards a link between CXCL12 and LVH as well as blood pressure control among patients with CKD, supporting the thesis that CXCL12 may be regarded as a new potential uremic toxin.

SDF-1α/CXCR4 Signaling in Lipid Rafts Induces Platelet Aggregation via PI3 Kinase-Dependent Akt Phosphorylation

Stromal cell-derived factor-1α (SDF-1α)-induced platelet aggregation is mediated through its G protein-coupled receptor CXCR4 and phosphatidylinositol 3 kinase (PI3K). Here, we demonstrate that SDF-1α induces phosphorylation of Akt at Thr308 and Ser473 in human platelets. SDF-1α-induced platelet aggregation and Akt phosphorylation are inhibited by pretreatment with the CXCR4 antagonist AMD3100 or the PI3K inhibitor LY294002. SDF-1α also induces the phosphorylation of PDK1 at Ser241 (an upstream activator of Akt), GSK3β at Ser9 (a downstream substrate of Akt), and myosin light chain at Ser19 (a downstream element of the Akt signaling pathway). SDF-1α-induced platelet aggregation is inhibited by pretreatment with the Akt inhibitor MK-2206 in a dose-dependent manner. Furthermore, SDF-1α-induced platelet aggregation and Akt phosphorylation are inhibited by pretreatment with the raft-disrupting agent methyl-β-cyclodextrin. Sucrose density gradient analysis shows that 35% of CXCR4, 93% of the heterotrimeric G proteins Gαi-1, 91% of Gαi-2, 50% of Gβ and 4.0% of PI3Kβ, and 4.5% of Akt2 are localized in the detergent-resistant membrane raft fraction. These findings suggest that SDF-1α/CXCR4 signaling in lipid rafts induces platelet aggregation via PI3K-dependent Akt phosphorylation.

Myocardial Ischemia Induces SDF-1α Release in Cardiac Surgery Patients

In the present observational study, we measured serum levels of the chemokine stromal cell-derived factor-1α (SDF-1α) in 100 patients undergoing cardiac surgery with cardiopulmonary bypass at seven distinct time points including preoperative values, myocardial ischemia, reperfusion, and the postoperative course. Myocardial ischemia triggered a marked increase of SDF-1α serum levels whereas cardiac reperfusion had no significant influence. Perioperative SDF-1α serum levels were influenced by patients' characteristics (e.g., age, gender, aspirin intake). In an explorative analysis, we observed an inverse association between SDF-1α serum levels and the incidence of organ dysfunction. In conclusion, time of myocardial ischemia was identified as the key stimulus for a significant upregulation of SDF-1α, indicating its role as a marker of myocardial injury. The inverse association between SDF-1α levels and organ dysfunction association encourages further studies to evaluate its organoprotective properties in cardiac surgery patients.

Circulating Endothelial Progenitor Cells: Potential Biomarkers for Idiopathic Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) remains the most frequent cause of cardiac transplant and thus results in an enormous cost burden for health care systems worldwide. Although DCM is thought to be induced mainly by genetic and/or environmental factors, the cause is unknown in the majority of cases, giving rise to the term idiopathic DCM. Marked cardiac endothelial changes are associated with disease progression and outcome, and there are ongoing efforts to identify biomarkers that have diagnostic and prognostic value. Here, we discuss the potential and the limitations of circulating endothelial progenitor cells (EPCs) as minimally invasive serological biomarkers for DCM. In this context, it is essential to further evaluate their clinical utility independently of other variable factors that can also affect EPC levels such as age, gender, lifestyles, and treatments. To that end, large multicenter studies and standardized instrument settings, reagents, and sample preparation protocols are needed to confirm this.

Stromal cell-derived factor 1α (SDF-1α): A marker of disease burden in patients with atrial fibrillation

OBJECTIVES

Stromal cell-derived factor 1a (SDF-1α), is a chemokine and is able to home hematopoietic progenitor cells to injured areas of heart tissue for structural repair. Previous studies have found increased levels of SDF-1α in several cardiac diseases, but only few studies have investigated SDF-1α in patients with atrial fibrillation (AF). We aimed to test SDF-1α in a large cohort of patients with AF and its role as a prognostic marker.

DESIGN

Between January 1st 2008 to December 1st 2012, 290 patients with ECG documented AF were enrolled from the in- and outpatient clinics at the Department of Cardiology, Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark. Plasma levels of SDF-1α were measured using ELISA technique. Clinical data were registered and patient follow-up was conducted.

RESULTS

Patients with permanent AF had significantly higher SDF-1α levels (2199.5 pg/ml) than the patients with paroxysmal AF (1982.0 pg/ml) and persistent AF (1906.0 pg/ml), p < 0.0005. Higher SDF-1α level was associated with longer time spent in the hospital per readmission, p < 0.05.

CONCLUSION

In AF patients, a higher SDF-1α level was found in patients with a more progressive state of arrhythmia and was associated with longer hospitalizations. These findings suggest that SDF-1α could prove valuable in risk stratification and evaluating the disease burden in AF patients.

Platelet surface expression of stromal cell-derived factor-1 receptors CXCR4 and CXCR7 is associated with clinical outcomes in patients with coronary artery disease

BACKGROUND

Surface expression of stromal cell-derived factor-1 (SDF-1, CXCL12) on platelets is enhanced during ischemic events and plays an important role in peripheral homing of stem cells and myocardial repair mechanisms. SDF-1 effects are mediated through CXCR4 and CXCR7. Both CXCR4 and CXCR7 are surface expressed on human platelets and to a higher degree in patients with coronary artery disease (CAD) compared with healthy controls. In this study, we investigated the prognostic role of platelet CXCR4- and CXCR7 surface expression in patients with symptomatic CAD.

METHODS AND RESULTS

In a cohort study, platelet surface expression of CXCR4 and CXCR7 was measured by using flow cytometry in 284 patients with symptomatic CAD at the time of percutaneous coronary intervention (PCI). The primary combined end point was defined as all-cause death and/or myocardial infarction (MI) during 12-month follow-up. Secondary end points were defined as the single events of all-cause death and MI. We found significant differences of CXCR4 values in patients who developed a combined end point compared with event-free patients (mean MFIAUTHOR: Please define MFI at first use. 3.17 vs. 3.44, 95% confidence interval [CI] 0.09-0.45) and in patients who subsequently died (mean MFI 3.10 vs. 3.42, 95% CI 0.09-0.56). In multivariate Cox regression analysis, lower platelet CXCR4 levels were independently and significantly associated with all-cause mortality (hazard ratio 0.24, 95% CI 0.07-0.87) and the primary combined end point of all-cause death and/or MI (hazard ratio 0.30, 95% CI 0.13-0.72).

CONCLUSION

These findings highlight a potential prognostic value of platelet expression CXCR4 on clinical outcomes in patients with CAD.