The aorta can act as a site of naïve CD4+ T-cell priming

Aims: Aortic adaptive immunity plays a role in atherosclerosis; however, the precise mechanisms leading to T-cell activation in the arterial wall remain poorly understood. Methods and results: Here, we have identified naïve T cells in the aorta of wild-Type and T-cell receptor transgenic mice and we demonstrate that naïve T cells can be primed directly in the vessel wall with both kinetics and frequency of T-cell activation found to be similar to splenic and lymphoid T cells. Aortic homing of naïve T cells is regulated at least in part by the P-selectin glycosylated ligand-1 receptor. In experimental atherosclerosis the aorta supports CD4+ T-cell activation selectively driving Th1 polarization. By contrast, secondary lymphoid organs display Treg expansion. Conclusion: Our results demonstrate that the aorta can support T-cell priming and that naïve T cells traffic between the circulation and vessel wall. These data underpin the paradigm that local priming of T cells specific for plaque antigens contributes to atherosclerosis progression

D025 Phagocytosis is pivotal in the beneficial effect of bone marrow mononuclear cellsbased therapy for myocardial infarction

Cell-based therapy is a promising option for treatment of cardiovascular diseases. Based on experimental studies demonstrating that bone marrow-derived mononuclear cells (BMMNCs) improve the functional recovery after ischemia, clinical trials were initiated to address this new therapeutic concept. BMMNCs improve neovascularization of ischemic tissue by a broad repertoire of potential therapeutic actions. Whereas initial studies documented that the cells incorporate and differentiate to cardiovascular cells, other studies suggested that short-time paracrine mechanisms mediate the beneficial effects. Here, we hypothesized that BMMNCs have a phagocytic ability, and switch to a proangiogenic phenotype after engulfment of apoptotic cells. Activation of such angiogenic program may be pivotal in the beneficial effect of BMMNCs-based therapy. In vitro, wildtype (WT) BMMNCs ingestion of apoptotic cells upregulated the release of proangiogenic factors VEGF and HGF by 15- and 5-fold, respectively. In contrast, BMMNCs collected from mice deficient in MFG-E8, a protein that is required for attachment and engulfment of apoptotic cells by phagocytes, displayed lower phagocytic ability, leading to decrease in VEGF and HGF release. The capacity of BMMNCs to differentiate into cells with endothelial phenotype was similar in control and MFG-E8-deficient cells. In an in vivo model of mice myocardial infaction (MI), transplantation of WT BMMNCs increased fractionnal shortening (120 % of untreated control, p<0.05), 14 days after MI. Size of the infarct scar was reduced by 30 % (p<0.05 vs untreated control), and capillary density in the infarct border zone was raised by 10 % (p<0.05 vs untreated control) in the WT BMMNCs group. In contrast, transplantation of MFG-E8 deficient BMMNCs displayed no significant effect on cardiac function, infarct size or angiogenesis in the ischemic myocardium. Four days after MI, VEGF protein levels were raised by 1.4 fold in the myocardium of WT BMMNCs treated animals compared to untreated controls (p<0.05), while treatment with MFG-E8 deficient BMMNCs failed to raise VEGF levels. Taken together, these results suggest that phagocytosis of apoptotic cells reprograms BMMNCs into a proangiogenic phenotype. Hence, the therapeutic effect of transplanted BMMNCs depends, at least in part, on their phagocytic ability

D022 Natural CD4/CD25/Foxp3 regulatory t cells modulate post-ischemic inflammatory response: role in neovascularization

CD4+ and CD8+ T lymphocytes control revascularization after vascular occlusion. T cell activation is mediated by two major costimulatory signalings: the B7/CD28 and the CD40-CD40 ligand pathways. Interestingly, CD28 interactions with the structurally related ligands B7-1 and B7-2 are also required for the generation and homeostasis of CD4+CD25+ regulatory T cells (Treg), whichactively maintain immunological tolerance to self and nonself antigens. We hypothesized that naturally arising Treg modulate the immuno-inflammatory response to ischemic injury, and subsequently vessel growth.Ischemia was induced by right femoral artery ligation in CD28-deficient mice (n=10 per group). After 21 days of ischemia, CD28 deficiency showed a profound reduction in Treg number and upregulated post-ischemic inflammatory response and neovascularization. Similarly, injection of splenocytes isolated from CD28-/- mice in Rag1-/- mice with hindlimb ischemia increased angiographic score, foot perfusion, and capillary density by 2.2-, 2.3- and 1.1-fold, respectively, compared to PBS-injected Rag1-/- mice. These effects were associated with enhanced accumulation of CD3-positive T cells and Mac-3 positive macrophages in the ischemic leg of Rag1-/- mice treated with CD28-/- splenocytes. Interestingly, cotransfer of Treg with CD28-/- splenocytes in Rag1- /- mice abrogated activation of neovascularization induced by CD28-/- splenocytes. Inflammatory cells accumulation was also decreased in Rag1-/- transplanted with both Treg and CD28-/- splenocytes compared to mice receiving CD28-/- splenocytes only. In contrast, treatment of C57Bl/6 Wild-Type mice with an anti- CD25 antibody (PC61) markedly reduced endogenous Treg levels in blood and spleen. At day 14 of ischemia, inflammatory response and neovascularization were markedly increased in anti-CD25 treated Wild-Type mice compared to untreated mice. These results provide new insights into the immunoregulation of post-ischemic neovascularization

Structure of NaFeSiO4, NaFeSi2O6, and NaFeSi3O8 glasses and glass-ceramics

The crystallization of iron-containing sodium silicate phases holds particular importance, both in the management high-level nuclear wastes and in geosciences. Here, we study three asquenched glasses and their heat-treated chemical analogues, NaFeSiO4, NaFeSi2O6, and NaFeSi3O8 (with nominal stoichiometries from feldspathoid, pyroxene, and feldspar mineral groups – i.e., Si/Fe = 1, 2, and 3 respectively) – using a variety of techniques. Phase analyses revealed that as-quenched NaFeSiO4 cannot accommodate all Fe in the glass phase (some Fe crystallizes as Fe3O4), whereas as-quenched NaFeSi2O6 and NaFeSi3O8 form amorphous glasses upon quenching. NaFeSi2O6 glass is the only composition that crystallizes into its respective isochemical crystalline polymorph, i.e. aegirine, upon isothermal heat-treatment. As revealed by Mössbauer spectroscopy, iron is predominantly present as 4-coordinated Fe3+ in all glasses, though it is present as 6-coordinated Fe3+ in the aegirine crystals (NaFeSi2O6), as expected from crystallography. Thus, Fe can form the crystalline phases in which it is octahedrally coordinated, even though it is mostly tetrahedrally coordinated in the parent glasses. Thermal behavior, magnetic properties, iron redox state (including Fe K-edge X-ray absorption), and vibrational properties (Raman spectra) of the above compositions are discussed

From basic mechanisms to clinical applications in heart protection, new players in cardiovascular diseases and cardiac theranostics: meeting report from the third international symposium on "New frontiers in cardiovascular research"

In this meeting report, particularly addressing the topic of protection of the cardiovascular system from ischemia/reperfusion injury, highlights are presented that relate to conditioning strategies of the heart with respect to molecular mechanisms and outcome in patients' cohorts, the influence of co-morbidities and medications, as well as the contribution of innate immune reactions in cardioprotection. Moreover, developmental or systems biology approaches bear great potential in systematically uncovering unexpected components involved in ischemia-reperfusion injury or heart regeneration. Based on the characterization of particular platelet integrins, mitochondrial redox-linked proteins, or lipid-diol compounds in cardiovascular diseases, their targeting by newly developed theranostics and technologies opens new avenues for diagnosis and therapy of myocardial infarction to improve the patients' outcome

B lymphocytes trigger monocyte mobilization and impair heart function after acute myocardial infarction.

Acute myocardial infarction is a severe ischemic disease responsible for heart failure and sudden death. Here, we show that after acute myocardial infarction in mice, mature B lymphocytes selectively produce Ccl7 and induce Ly6C(hi) monocyte mobilization and recruitment to the heart, leading to enhanced tissue injury and deterioration of myocardial function. Genetic (Baff receptor deficiency) or antibody-mediated (CD20- or Baff-specific antibody) depletion of mature B lymphocytes impeded Ccl7 production and monocyte mobilization, limited myocardial injury and improved heart function. These effects were recapitulated in mice with B cell-selective Ccl7 deficiency. We also show that high circulating concentrations of CCL7 and BAFF in patients with acute myocardial infarction predict increased risk of death or recurrent myocardial infarction. This work identifies a crucial interaction between mature B lymphocytes and monocytes after acute myocardial ischemia and identifies new therapeutic targets for acute myocardial infarction.This work was supported by Inserm, British Heart Foundation (Z.M.), European Research Council (Z.M.), Fondation Coeur et Recherche (Z.M., T.S., N.D.), Fondation pour la Recherche Medicale (J.S.S.), European Union Seven Framework programme TOLERAGE (Z.M.), Fondation Leducq transatlantic network (C.J.B., D.T., A.T., J.S.S., Z.M.), National Institutes of Health grants AI56363 and AI057157, and a grant from The Lymphoma Research Foundation (T.F.T).This is the author accepted manuscript. The final version is available from Nature Publishing Group at http://dx.doi.org/10.1038/nm.3284

Angiogenesis in the infarcted myocardium.

SIGNIFICANCE: Proangiogenic therapy appeared a promising strategy for the treatment of patients with acute myocardial infarction (MI), as de novo formation of microvessels, has the potential to salvage ischemic myocardium at early stages after MI, and is also essential to prevent the transition to heart failure through the control of cardiomyocyte hypertrophy and contractility. RECENT ADVANCES: Exciting preclinical studies evaluating proangiogenic therapies for MI have prompted the initiation of numerous clinical trials based on protein or gene transfer delivery of growth factors and administration of stem/progenitor cells, mainly from bone marrow origin. Nonetheless, these clinical trials showed mixed results in patients with acute MI. CRITICAL ISSUES: Even though methodological caveats, such as way of delivery for angiogenic growth factors (e.g., protein vs. gene transfer) and stem/progenitor cells or isolation/culture procedure for regenerative cells might partially explain the failure of such trials, it appears that delivery of a single growth factor or cell type does not support angiogenesis sufficiently to promote cardiac repair. FUTURE DIRECTIONS: Optimization of proangiogenic therapies might include stimulation of both angiogenesis and vessel maturation and/or the use of additional sources of stem/progenitor cells, such as cardiac progenitor cells. Experimental unraveling of the mechanisms of angiogenesis, vessel maturation, and endothelial cell/cardiomyocyte cross talk in the ischemic heart, analysis of emerging pathways, as well as a better understanding of how cardiovascular risk factors impact endogenous and therapeutically stimulated angiogenesis, would undoubtedly pave the way for the development of novel and hopefully efficient angiogenesis targeting therapeutics for the treatment of acute MI

Angiogenesis in the infarcted myocardium.

SIGNIFICANCE: Proangiogenic therapy appeared a promising strategy for the treatment of patients with acute myocardial infarction (MI), as de novo formation of microvessels, has the potential to salvage ischemic myocardium at early stages after MI, and is also essential to prevent the transition to heart failure through the control of cardiomyocyte hypertrophy and contractility. RECENT ADVANCES: Exciting preclinical studies evaluating proangiogenic therapies for MI have prompted the initiation of numerous clinical trials based on protein or gene transfer delivery of growth factors and administration of stem/progenitor cells, mainly from bone marrow origin. Nonetheless, these clinical trials showed mixed results in patients with acute MI. CRITICAL ISSUES: Even though methodological caveats, such as way of delivery for angiogenic growth factors (e.g., protein vs. gene transfer) and stem/progenitor cells or isolation/culture procedure for regenerative cells might partially explain the failure of such trials, it appears that delivery of a single growth factor or cell type does not support angiogenesis sufficiently to promote cardiac repair. FUTURE DIRECTIONS: Optimization of proangiogenic therapies might include stimulation of both angiogenesis and vessel maturation and/or the use of additional sources of stem/progenitor cells, such as cardiac progenitor cells. Experimental unraveling of the mechanisms of angiogenesis, vessel maturation, and endothelial cell/cardiomyocyte cross talk in the ischemic heart, analysis of emerging pathways, as well as a better understanding of how cardiovascular risk factors impact endogenous and therapeutically stimulated angiogenesis, would undoubtedly pave the way for the development of novel and hopefully efficient angiogenesis targeting therapeutics for the treatment of acute MI