Davide Flego

Effect of Remote Ischemic Preconditioning on Platelet Activation Induced by Coronary Procedures

In this study, we aim to assess whether remote ischemic preconditioning (RIPC) reduces platelet activation during coronary angiography (CA) and/or percutaneous coronary interventions. We studied 30 patients who underwent CA because of a suspect of stable angina. Patients were randomized to RIPC (3 short episodes of forearm ischemia) or sham RIPC (controls) before the procedure. Blood samples were collected at baseline, at the end of the procedure, and 24 hours later. Monocyte-platelet aggregate (MPA) formation and platelet CD41 in the MPA gate and CD41 and CD62 expression in the platelet gate were assessed by flow cytometry, in the absence and in the presence of adenosine diphosphate (ADP) stimulation. A significant increase in platelet activation occurred during the invasive procedure in controls, which persisted at 24 hours. However, compared with controls, RIPC group showed no or a lower increase in platelet variables, including MPA formation (p <0.0001) and CD41 (p = 0.002) in the MPA gate and CD41 (p <0.0001) and CD62 (p = 0.002) in the platelet gate. ADP increased platelet activation at baseline, but did not further increase platelet reactivity during the invasive procedure in either groups. Percutaneous coronary interventions, performed in 10 patients (6 in the RIPC group and 4 in controls), did not have any further significant effect on platelet activation and reactivity compared with CA alone. In conclusion, RIPC reduces platelet activation occurring during CA. In contrast, no effects were observed on platelet response to ADP stimulation, probably related to the administration of an ADP antagonist in all patients.

Matrix metalloproteinase-9 might affect adaptive immunity in non-ST segment elevation acute coronary syndromes by increasing CD31 cleavage on CD4+ T-cells

Abstract Aims In patients with acute coronary syndrome (ACS), the higher activity of effector T-cells suggests that mechanisms involving adaptive immunity dysregulation might play a role in coronary instability. The shedding of the functional CD31 domain 1–5 leads to uncontrolled lymphocyte activation. In experimental models, matrix metalloproteinase-9 (MMP-9) has been implicated in endothelial CD31 cleavage. Interestingly, higher serum levels of MMP-9 have been observed in ACS. We aim to investigate the mechanisms underlying CD31 dysregulation in ACS. Methods and results To assess CD31 cleavage on CD4+ T-cells, we analysed by flow cytometry CD4+ T-cells of 30 ACS, 25 stable angina (SA) patients, and 28 controls (CTRL) using two different CD31 antibodies that specifically recognize domain 1–5 or the non-functional membrane-proximal domain 6. The ratio between the domains was significantly lower in ACS than in SA and CTRL (Pu2009=u20090.002 ACS vs. SA; Pu2009=u20090.002 ACS vs. CTRL). After stimulation with anti-CD3/CD28, the 1–5/6 domain ratio was significantly lower in ACS than in SA (Pu2009=u20090.005). ELISA of supernatants obtained from T-cell receptor-stimulated CD4+ T-cells showed higher production of MMP-9 in ACS than in SA (Pu2009<u20090.001). CD31 domain 1–5 expression in activated CD4+ T-cells from ACS patients increased after treatment with a specific MMP-9 inhibitor (Pu2009=u20090.042). Conclusion Our study suggest that enhanced MMP-9 release plays a key role in determining the cleavage and shedding of the functional CD31 domain 1–5 in CD4+ T-cells of ACS patients. This mechanism might represent an important therapeutic target to modulate T-cell dysregulation in ACS.

Alterations of Hyaluronan Metabolism in Acute Coronary Syndrome: Implications for Plaque Erosion

BACKGROUNDnSuperficial erosion currently causes at least one-third of acute coronary syndromes (ACS), and its incidence is increasing. Yet, the underlying mechanisms in humans are still largely unknown.nnnOBJECTIVESnThe authors sought to assess the role of hyaluronan (HA) metabolism in ACS.nnnMETHODSnPeripheral blood mononuclear cells were collected from ACS (nxa0=xa066), stable angina (SA) (nxa0=xa055), and control (CTRL) patients (nxa0=xa045). The authors evaluated: 1) gene expression of hyaluronidase 2 (HYAL2) (enzyme degrading high-molecular-weight HA to its proinflammatory 20-kDa isoform) and of CD44v1, CD44v4, and CD44v6 splicing variants of HA receptor; and 2) HYAL2 and CD44 protein expression. Moreover, they compared HYAL2 and CD44 gene expression in ACS patients with plaque erosion (intact fibrous cap and thrombus) and in ACS patients with plaque rupture, identified by optical coherence tomography analysis.nnnRESULTSnGene expression of HYAL2, CD44v1, and CD44v6 were significantly higher in ACS as compared with SA (pxa0=xa00.003, pxa0< 0.001, and pxa0=xa00.033, respectively) and CTRL subjects (pxa0< 0.001, pxa0< 0.001, and pxa0=xa00.009, respectively). HYAL2 protein expression was significantly higher in ACS than in SA (pxa0=xa00.017) and CTRL (pxa0=xa00.032), whereas no differences were found in CD44 protein expression. HYAL2 and CD44v6 gene expression was significantly higher in patients with plaque erosion than in those with plaque rupture (pxa0=xa00.015 and pxa0=xa00.029, respectively).nnnCONCLUSIONSnHYAL2 and CD44v6 splicing variants seem to play an important role in ACS, in particular when associated with plaque erosion. After further validation, HYAL2 might represent a potentially useful biomarker forxa0thexa0noninvasive identification of this mechanism of coronary instability.

Correlation between CD4+CD28null T lymphocytes, regulatory T cells and plaque rupture: An Optical Coherence Tomography study in Acute Coronary Syndromes

BACKGROUNDnA sizeable proportion of patients with Acute Coronary Syndromes (ACS) shows a unique adaptive immune system profile, associated to a worse outcome, characterized by higher CD4+CD28null T-cells, lower regulatory T-cells (Treg) and increased CD4+CD28null/Treg ratio. We sought to investigate the correlation between CD4+CD28null T-cells, Treg, CD4+CD28null/Treg ratio and plaque phenotype as assessed by Optical Coherence Tomography (OCT).nnnMETHODSnPeripheral blood mononuclear cells (PBMC) were collected from 30 Non-ST Elevation Myocardial Infarction (NSTEMI) patients, sub-grouped according to OCT analysis of culprit lesions into two cohorts: Ruptured Fibrous Cap (NSTEMI-RFC, nu202f=u202f12) and Intact Fibrous Cap (NSTEMI-IFC, nu202f=u202f18). Stable Angina patients (SA, nu202f=u202f18) were used as controls. We examined the frequency of CD4+CD28null and Treg (defined as CD4+CD25highCD127lowFoxp3+ T-cells) by flow-cytometry.nnnRESULTSnCD4+CD28null frequency (median, range) was significantly higher in NSTEMI-RFC patients (17.3%, 12.5-33.8) as compared with NSTEMI-IFC (3.8%, 0.3-14.1) and SA (3%, 0.6-17.7) (Pu202f<u202f0.001 for all comparisons). We also found a higher CD4+CD28null/Treg ratio in NSTEMI-RFC patients (6.6%, 3.7-13.9) than in NSTEMI-IFC (1.6%, 0.3-5.2) and SA (1.2%, 0.3-8.7) (Pu202f<u202f0.001 for all comparisons). Finally, there was an inverse correlation between CD4+CD28null/Treg ratio and cap-thickness (Ru202f=u202f-0.44; Pu202f=u202f0.002).nnnCONCLUSIONnPatients with NSTEMI presenting with RFC as culprit lesion at OCT evaluation have a specific perturbation of adaptive immunity, mostly involving CD4+CD28null T- cells and Tregs, as compared with patients with IFC and SA. This specific imbalance of T-cells might play a key role in fibrous cap thinning, predisposing atherosclerotic plaque to rupture.

HYALURONIC ACID, HYALURONIDASE-2 AND ACUTE CORONARY SYNDROMES: POSSIBLE CORRELATION WITH PLAQUE EROSION

Background: A recent experimental model of plaque instability suggests that endothelial activation and the exposure of the extracellular matrix are involved in the inflammatory process of plaque erosion. These data, together with the notion of an intense immunostaining on eroded autoptic coronary

Response to Letter Regarding Article, “Allergic Inflammation Is Associated With Coronary Instability and a Worse Clinical Outcome After Acute Myocardial Infarction”

We thank Cervellin et al1 for their interesting comments on our article on allergic inflammation in acute coronary syndromes.2 Kounis et al3 described allergic inflammation to be responsible for acute coronary syndromes, during conditions associated with mast cell activation, including allergic or hypersensitivity and anaphylactic insults. Indeed, eosinophils and mast cells play a key role in the late phase of an allergic response, releasing allergic mediators responsible for coronary vasoconstriction …