Alessio Palini

Circulating CD4+CD25hiCD127lo Regulatory T-Cell Levels Do Not Reflect the Extent or Severity of Carotid and Coronary Atherosclerosis

Objective—Regulatory T (Treg) cells play a protective role in experimental atherosclerosis. In the present study, we investigated whether the levels of circulating Treg cells relate to the degree of atherosclerosis in carotid and coronary arteries. Methods and Results—We studied 2 distinct populations: (1) 113 subjects, selected from a free-living population (carotid study), in which we measured the intima-media thickness of the common carotid artery, as a surrogate marker of initial atherosclerosis; and (2) 75 controls and 125 patients with coronary artery disease (coronary study): 36 with chronic stable angina, 50 with non-ST-elevation acute coronary syndrome, 39 with ST-elevation acute myocardial infarction. Treg-cell levels were evaluated by flow cytometry (Treg cells identified as CD3+CD4+CD25highCD127low) and by mRNA expression of forkhead box P3 or of Treg-associated cytokine interleukin 10. In the carotid study, no correlation was observed between Treg-cell levels and intima-media thickness. No differences in Treg-cell levels were observed comparing rapid versus slow intima-media thickness progressors from a subgroup of patients (n=65), in which prospective data on 6-year intima-media thickness progression were available. In the coronary group, Treg-cell levels were not altered in chronic stable angina patients. In contrast, nonunivocal variations were observed in patients suffering an acute coronary syndrome (with a Treg-cell increase in ST-elevation acute myocardial infarction and a Treg-cell decrease in non-ST-elevation acute coronary syndrome patients). Conclusion—The results suggest that determination of circulating Treg-cell levels based on flow cytometry or mRNA assessment is not a useful indicator of the extent or severity of atherosclerosis.

Effector Memory T cells Are Associated With Atherosclerosis in Humans and Animal Models

Background— Adaptive T-cell response is promoted during atherogenesis and results in the differentiation of naïve CD4+T cells to effector and/or memory cells of specialized T-cell subsets. Aim of this work was to investigate the relationship between circulating CD4+T-cell subsets and atherosclerosis. Methods and Results— We analyzed 57 subsets of circulating CD4+T cells by 10-parameter/8-color polychromatic flow cytometry (markers: CD3/CD4/CD45RO/CD45RA/CCR7/CCR5/CXCR3/HLA-DR) in peripheral blood from 313 subjects derived from 2 independent cohorts. In the first cohort of subjects from a free-living population (n=183), effector memory T cells (TEM: CD3+CD4+CD45RA−CD45RO+CCR7− cells) were strongly related with intima-media thickness of the common carotid artery, even after adjustment for age (r=0.27; P<0.001). Of note, a significant correlation between TEM and low-density lipoproteins was observed. In the second cohort (n=130), TEM levels were significantly increased in patients with chronic stable angina or acute myocardial infarction compared with controls. HLA-DR+TEM were the TEM subpopulation with the strongest association with the atherosclerotic process (r=0.37; P<0.01). Finally, in animal models of atherosclerosis, TEM (identified as CD4+CD44+CD62L−) were significantly increased in low-density lipoprotein receptor and apolipoprotein E deficient mice compared with controls and were correlated with the extent of atherosclerotic lesions in the aortic root (r=0.56; P<0.01). Conclusions— Circulating TEM cells are associated with increased atherosclerosis and coronary artery disease in humans and in animal models and could represent a key CD4+T-cell subset related to the atherosclerotic process. (J Am Heart Assoc. 2012;1:27-41.)

Identification and Predictive Value of Interleukin-6+ Interleukin-10+ and Interleukin-6− Interleukin-10+ Cytokine Patterns in ST-Elevation Acute Myocardial Infarction

Rationale: At the onset of ST-elevation acute myocardial infarction (STEMI), patients can present with very high circulating interleukin-6 (IL-6+) levels or very low-IL-6– levels. Objective: We compared these 2 groups of patients to understand whether it is possible to define specific STEMI phenotypes associated with outcome based on the cytokine response. Methods and Results: We compared 109 patients with STEMI in the top IL-6 level (median, 15.6 pg/mL; IL-6+ STEMI) with 96 in the bottom IL-6 level (median, 1.7 pg/mL; IL-6− STEMI) and 103 matched controls extracted from the multiethnic First Acute Myocardial Infarction study. We found minimal clinical differences between IL-6+ STEMI and IL-6− STEMI. We assessed the inflammatory profiles of the 2 STEMI groups and the controls by measuring 18 cytokines in blood samples. We exploited clustering analysis algorithms to infer the functional modules of interacting cytokines. IL-6+ STEMI patients were characterized by the activation of 2 modules of interacting signals comprising IL-10, IL-8, macrophage inflammatory protein-1&agr;, and C-reactive protein, and monocyte chemoattractant protein-1, macrophage inflammatory protein-1&bgr;, and monokine induced by interferon-&ggr;. IL-10 was increased both in IL-6+ STEMI and IL-6− STEMI patients compared with controls. IL-6+IL-10+ STEMI patients had an increased risk of systolic dysfunction at discharge and an increased risk of death at 6 months in comparison with IL-6−IL-10+ STEMI patients. We combined IL-10 and monokine induced by interferon-&ggr; (derived from the 2 identified cytokine modules) with IL-6 in a formula yielding a risk index that outperformed any single cytokine in the prediction of systolic dysfunction and death. Conclusions: We have identified a characteristic circulating inflammatory cytokine pattern in STEMI patients, which is not related to the extent of myocardial damage. The simultaneous elevation of IL-6 and IL-10 levels distinguishes STEMI patients with worse clinical outcomes from other STEMI patients. These observations could have potential implications for risk-oriented patient stratification and immune-modulating therapies.

Identification and Predictive Value of IL6(+)IL10(+) and IL6(-)IL10(+) Cytokine Patterns in ST-Elevation Acute Myocardial Infarction

Rationale: At the onset of ST-elevation acute myocardial infarction (STEMI), patients can present with very high circulating interleukin-6 (IL-6+) levels or very low-IL-6– levels. Objective: We compared these 2 groups of patients to understand whether it is possible to define specific STEMI phenotypes associated with outcome based on the cytokine response. Methods and Results: We compared 109 patients with STEMI in the top IL-6 level (median, 15.6 pg/mL; IL-6+ STEMI) with 96 in the bottom IL-6 level (median, 1.7 pg/mL; IL-6− STEMI) and 103 matched controls extracted from the multiethnic First Acute Myocardial Infarction study. We found minimal clinical differences between IL-6+ STEMI and IL-6− STEMI. We assessed the inflammatory profiles of the 2 STEMI groups and the controls by measuring 18 cytokines in blood samples. We exploited clustering analysis algorithms to infer the functional modules of interacting cytokines. IL-6+ STEMI patients were characterized by the activation of 2 modules of interacting signals comprising IL-10, IL-8, macrophage inflammatory protein-1&agr;, and C-reactive protein, and monocyte chemoattractant protein-1, macrophage inflammatory protein-1&bgr;, and monokine induced by interferon-&ggr;. IL-10 was increased both in IL-6+ STEMI and IL-6− STEMI patients compared with controls. IL-6+IL-10+ STEMI patients had an increased risk of systolic dysfunction at discharge and an increased risk of death at 6 months in comparison with IL-6−IL-10+ STEMI patients. We combined IL-10 and monokine induced by interferon-&ggr; (derived from the 2 identified cytokine modules) with IL-6 in a formula yielding a risk index that outperformed any single cytokine in the prediction of systolic dysfunction and death. Conclusions: We have identified a characteristic circulating inflammatory cytokine pattern in STEMI patients, which is not related to the extent of myocardial damage. The simultaneous elevation of IL-6 and IL-10 levels distinguishes STEMI patients with worse clinical outcomes from other STEMI patients. These observations could have potential implications for risk-oriented patient stratification and immune-modulating therapies.

Membrane IgE Binds and Activates FcεRI in an Antigen-Independent Manner

Interaction of secretory IgE with FcεRI is the prerequisite for allergen-driven cellular responses, fundamental events in immediate and chronic allergic manifestations. Previous studies reported the binding of soluble FcεRIα to membrane IgE exposed on B cells. In this study, the functional interaction between human membrane IgE and human FcεRI is presented. Four different IgE versions were expressed in mouse B cell lines, namely: a truncation at the Cε2-Cε3 junction of membrane IgE isoform long, membrane IgE isoform long (without Igα/Igβ BCR accessory proteins), and both εBCRs (containing membrane IgE isoforms short and long). All membrane IgE versions activated a rat basophilic leukemia cell line transfected with human FcεRI, as detected by measuring the release of both preformed and newly synthesized mediators. The interaction led also to Ca2+ responses in the basophil cell line, while membrane IgE-FcεRI complexes were detected by immunoprecipitation. FcεRI activation by membrane IgE occurs in an Ag-independent manner. Noteworthily, human peripheral blood basophils and monocytes also were activated upon contact with cells bearing membrane IgE. In humans, the presence of FcεRI in several cellular entities suggests a possible membrane IgE-FcεRI-driven cell-cell dialogue, with likely implications for IgE homeostasis in physiology and pathology.

The combination of marker gene swapping and fluorescence-activated cell sorting improves the efficiency of recombinant modified vaccinia virus Ankara vaccine production for human use.

Modified vaccinia virus Ankara (MVA) is employed as a human vaccine vector for the high expression of heterologous genes and the lack of replication in mammalian cells. This study demonstrates that cells infected by recombinant viruses can be obtained by fluorescence-activated cell sorting. Recombinant viruses are generated by a swapping event between a red fluorescent protein gene in the acceptor virus and a plasmid cassette coding for both a green fluorescent marker and a transgene. To prevent the carry-over of parental virus, due to superinfection of the cells harbouring recombinant viruses, the sorting is performed on cells infected at low m.o.i. in the presence of a reversible inhibitor of viral particle release. Terminal dilution cloning is then used to isolate both green and marker-free recombinant viruses, which can be identified by whole-plate fluoroimaging. The differential visualization of all the viral types involved allows a stepwise monitoring of all recombinations and leads to a straightforward and efficient flow cytometry-based cell sorting purification protocol. As an example of the efficacy of this sorting procedure, the construction of rMVAs coding for the rat nuclear protein HMGB1 and H5N1 influenza A virus hemagglutinin is reported. The entire recombinant MVA production process is carried out in serum-free media employing primary chicken embryo fibroblasts (CEF), which are certified for the preparation of human vaccines. This rMVA production method is faster, simpler and more reliable than any other available procedure for obtaining safe vaccine stocks for human use.

Endothelial Progenitor Cells Carrying Monocyte Markers Are Selectively Abnormal in Type 1 Diabetic Patients With Early Retinopathy

Endothelial progenitor cells (EPCs) enter the systemic circulation in response to cues related to vascular damage and need for neovascularization. Thus, EPCs could become readily accessible informers of vascular status and enable the survey of vascular pathologies during preclinical stages. To identify EPC changes with biomarker potential, we investigated whether discrete EPC abnormalities were associated with early nonproliferative diabetic retinopathy (NPDR). Two EPC subtypes with different functions have been characterized to date—one solely committed to the endothelial lineage and the other carrying both endothelial and monocytic markers. We found that only the latter, colony-forming units (CFU)-Hill cells, manifested abnormalities in type 1 diabetic patients with NPDR compared with control subjects. The abnormalities consisted in an increased number of colonies formed in vitro and downregulation of the molecules that facilitate homing at sites of vascular injury. The abnormalities were absent in type 1 diabetic patients free of retinopathy and other complications, despite long diabetes duration, but were detected in some of the patients without clinical retinopathy after short diabetes duration. CFU-Hill cells are potential informers of diabetic microangiopathy but may be preempted from carrying out reparative functions if the molecular abnormalities compromise interactions with the damaged vascular wall.

Joint production of prime/boost pairs of Fowlpox Virus and Modified Vaccinia Ankara recombinants carrying the same transgene

Pairs of recombinant MVA (Modified Vaccinia Ankara) and FPV (Fowlpox Virus) expressing the same transgene are reasonable candidates for prime/boost regimens, because cross-reacting immune responses between the two vectors, both non-replicative in mammalian hosts, are very limited. The acceptor virus FPD-Red, a derivative of FPV, carrying a red fluorescent protein gene flanked by the homology regions of MVA deletion III, was constructed. The same MVA Transfer Plasmid Green, designed to insert transgenes into the MVA deletion III locus, can therefore be used to transfer transgenes into both acceptor viruses MVA-Red and FPD-Red with the described recently Red-to-Green gene swapping method. Cells infected by either recombinant virus can be sorted differentially by a simple and reliable FACS-based purification protocol. The procedure is carried out in primary chick embryo fibroblasts grown in serum-free media and was applied to the production of three rMVA/rFPV pairs expressing the H5N1 avian influenza antigens M1, M2 and NP. The viral genes were human codon-optimized and expressed at high levels in both chick and mammalian cells. Both single-step and multiple-step growth analyses showed no significant differences in growth due to the transgenes in either rMVA or rFPV derivatives.

Endothelial Progenitor Cells And Response To Ranibizumab In Age-related Macular Degeneration

Background: Choroidal neovascularization (CNV) is the main cause of vision loss in age-related macular degeneration (AMD). In experimental CNV, endothelial progenitor cells (EPCs) contribute to the formation of new vessels. The aim of this study was to investigate whether the behavior of EPCs in patients with AMD supports a role for EPCs in human CNV. Methods: The number of circulating EPCs that are considered pure endothelial precursors and EPCs with monocytic characteristics, and the plasma levels of regulatory cytokines were evaluated in 23 patients with AMD with active CNV and 20 matched controls. In the patients, this profile was re-evaluated after ranibizumab. Results: When compared with controls, the patients with AMD showed a lower number of both EPC types (P = 0.03) and higher plasma levels (P = 0.03) of stromal cell–derived factor 1. Three monthly injections of ranibizumab returned to control levels the number of circulating EPCs considered pure endothelial precursors and of stromal cell–derived factor 1, but not of monocytic EPCs. Conclusion: The observations indicate responsiveness of circulating EPCs to the CNV process in AMD. They suggest the hypothesis that increased stromal cell–derived factor 1 production at the CNV site (reflected in higher plasma levels) recruits EPCs from the circulation, and that antivascular endothelial growth factor therapy selectively decreases the recruitment of cells to be incorporated into new vessels.

Carotid artery plaque uptake of 11C-PK11195 inversely correlates with circulating monocytes and classical CD14++CD16− monocytes expressing HLA-DR

Background We explored the relation between blood concentrations of monocyte/lymphocyte subsets and carotid artery plaque macrophage content, measured by positron emission tomography (PET) with 11C-PK11195. Methods and results In 9 patients with carotid plaques we performed 11C-PK11195-PET/computed tomography angiography imaging and measurement of absolute concentrations and frequencies of circulating monocytes and T-cell subsets. Plaque standardized uptake value (SUV) for 11C-PK11195 was negatively correlated with concentrations of total monocytes (r = −0.58, p = 0.05) and CD14++CD16−HLA-DR+ classical subset (r = −0.82, p = 0.005). These correlations hold true also in relation to plaque target to background ratio. No correlation was observed between plaque SUV and CD3+T lymphocytes, CD4+T lymphocytes nor with activated CD3+CD4+T cells expressing HLA-DR. Conclusions We first demonstrated a reduction in the absolute concentration of monocytes and particularly in classical monocytes expressing HLA-DR in the presence of an increased uptake of 11C-PK11195 in carotid plaques. The present work, despite being a pilot study comprising only a small number of subjects provides new insights in the search for specific cellular biomarkers with potential diagnostic and prognostic value in patients with a known carotid plaque.