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Sustained, indolent immune injury of the vasculature of a heart transplant limits long-term graft and recipient survival. This injury is mitigated by a poorly characterized, maladaptive repair response. Vascular endothelial cells respond to proangiogenic cues in the embryo by differentiation to specialized phenotypes, associated with expression of apelin. In the adult, the role of developmental proangiogenic cues in repair of the established vasculature is largely unknown. We found that human and minor histocompatibility-mismatched donor mouse heart allografts with alloimmune-mediated vasculopathy upregulated expression of apelin in arteries and myocardial microvessels. In vivo, loss of donor heart expression of apelin facilitated graft immune cell infiltration, blunted vascular repair, and worsened occlusive vasculopathy in mice. In vitro, an apelin receptor agonist analog elicited endothelial nitric oxide synthase activation to promote endothelial monolayer wound repair and reduce immune cell adhesion. Thus, apelin acted as an autocrine growth cue to sustain vascular repair and mitigate the effects of immune injury. Treatment with an apelin receptor agonist after vasculopathy was established markedly reduced progression of arterial occlusion in mice. Together, these initial data identify proangiogenic apelin as a key mediator of coronary vascular repair and a pharmacotherapeutic target for immune-mediated injury of the coronary vasculature., Introduction Heart transplantation is the most effective treatment of end-stage heart failure to prolong life. Modern immune-suppression regimens blunt alloreactive immune responses against the transplant, but are nevertheless associated with [...]

FYVE domains are highly conserved protein modules that typically bind phosphatidylinositol 3-phosphate (PI3P) on the surface of early endosomes. Along with pleckstrin homology (PH) and phox homology (PX) domains, FYVE domains are the principal readers of the phosphoinositide (PI) code that mediate specific recognition of eukaryotic organelles. Of all the human FYVE domain containing proteins, those within the faciogenital dysplasia (Fgd) subfamily are particularly divergent and couple with GTPases to exert unique cellular functions. The subcellular distributions and functions of these evolutionarily conserved signal transducers, which also include Dbl homology (DH) and two PH domains, are discussed here to better understand the biological range of processes that such multidomain proteins engage in. Determinants of their various functions include specific multidomain architectures, posttranslational modifications including PIP stops that have been discovered in sorting nexins, PI recognition motifs, and phospholipid-binding surfaces as defined by the Membrane Optimal Docking Area (MODA) program. How these orchestrate Fgd function remains unclear but has implications for developmental diseases including Aarskog-Scott syndrome, which is also known as faciogenital dysplasia, and forms of cancer that are associated with mutations and amplifications of Fgd genes. Key words: Cdc42, Dbl, FYVE, Fgd, GEF, GTPase, PH, phosphoinositide, pleckstrin, cancer, faciogenital dysplasia, Aarskog-Scott syndrome, lipid signaling, membrane trafficking, MODA, PIP, Rho. Les domaines FYVE consistent en modules proteiques hautement conserves qui lient typiquement le phosphatidylinositol 3-phosphate (PI3P) a la surface des endosomes precoces. Avec les domaines homologues de la pleckstrine (PH) et de phox (PX), les domaines FYVE sont les principaux lecteurs du code des phosphoinositides (PI) qui medient la reconnaissance specifique des organites eucaryotes. De toutes les proteines humaines a domaine FYVE, celles qui appartiennent a la sous-famille Fgd (<< faciogenital dysplasia >>) sont particulierement divergentes et s'associent a des GTPases pour exercer des fonctions cellulaires uniques. Les distributions subcellulaires et les fonctions de ces transducteurs de signaux conserves dans l'evolution, qui comprennent aussi les proteines a domaines d'homologie a Dbl (DH) et a deux domaines PH, sont discutees ici afin de mieux comprendre le spectre biologique des processus dans lesquels de telles proteines a domaines multiples sont engagees. Les determinants de leurs diverses fonctions comprennent des architectures multidomaines specifiques, des modifications post-traductionnelles dont les << PIP stops >> decouverts chez les sorting nexins, des motifs de reconnaissance du PI et des surfaces de liaison des phospholipides tels que definis par le programme << Membrane Optimal Docking Area >> (MODA). L'on ignore encore comment ils orchestrent les fonctions des Fgd, mais ils sont impliques dans des maladies developpementales comme le syndrome Aarskog-Scott, connu aussi sous l'appellation de dysplasie faciogenitale, et dans des cancers associes a des mutations et des amplifications des genes Fgd. [Traduit par la Redaction] Mots-cles : Cdc42, Dbl, FYVE, Fgd, GEF, GTPase, PH, phosphoinositide, pleckstrine, cancer, dysplasie faciogenitale, syndrome Aarskog-Scott, signalisation lipidique, trafic membranaire, MODA, PIP, Rho., Phosphoinositide code Stimulation and differentiation of cells involve dramatic alterations of phosphorylation patterns in proteins, lipids, and nucleotides. Defining how these molecular events converge to change cellular behaviour remains a [...]

Lymphocyte recruitment to sites of inflammation involves a bidirectional series of cues between the endothelial cell (EC) and the leukocyte that culminate in lymphocyte migration into the tissue. Remodeling of the EC F-actin cytoskeleton has been observed after leukocyte adhesion, but the signals to the EC remain poorly defined. We studied the dependence of peripheral blood lymphocyte transendothelial migration (TEM) through an EC monolayer in vitro on EC phosphatidylinositol 3-kinase (PI 3-kinase) activity. Lymphocytes were perfused over cytokine-activated EC using a parallel-plate laminar flow chamber. Inhibition of EC PI 3-kinase activity using LY-294002 or wortmannin decreased lymphocyte TEM (48 [+ or -] 6 or 34 [+ or -] 7%, respectively, vs. control; mean [+ or -] SE; P < 0.05). Similarly, EC knockdown of the p85[alpha] regulatory subunit of PI 3-kinase decreased lymphocyte transmigration. Treatment of EC with jasplakinolide to inhibit EC F-actin remodeling also decreased lymphocyte TEM to 24 [+ or -] 10% vs. control (P < 0.05). EC PI 3-kinase inhibition did not change the strength of lymphocyte adhesion to the EC or formation of the EC 'docking structure' after intercellular adhesion molecule-1 ligation, whereas this was inhibited by jasplakinolide treatment. A similar fraction of lymphocytes migrated on control or LY-294002-treated EC and localized to interendothelial junctions. However, lymphocytes failed to extend processes below the level of vascular endothelial (VE)-cadherin on LY-294002-treated EC. Together these observations indicate that EC PI 3-kinase activity and F-actin remodeling are required during lymphocyte diapedesis and identify a PI 3-kinase-dependent step following initial separation of the VE-cadherin barrier. T lymphocyte; cell motility; adherens junctions; cytoskeleton; F-actin

Analysis of atrial rhythm is important in the treatment and management of patients with atrial fibrillation. Several algorithms exist for extracting the atrial signal from the electrocardiogram (ECG) in atrial fibrillation, but there are few reports on how well these techniques are able to recover the atrial signal. We assessed and compared three algorithms for extracting the atrial signal from the 12-lead ECG. The 12-lead ECGs of 30 patients in atrial fibrillation were analyzed. Atrial activity was extracted by three algorithms, Spatiotemporal QRST cancellation (STC), principal component analysis (PCA), and independent component analysis (ICA). The amplitude and frequency characteristics of the extracted atrial signals were compared between algorithms and against reference data. Mean (standard deviation) amplitude of QRST segments of VI was 0.99 (0.54) mV, compared to 0.18 (0.11) mV (STC), 0.19 (0.13) mV (PCA), and 0.29 (0.22) mV (ICA). Hence, for all algorithms there were significant reductions in the amplitude of the ventricular activity compared with that in VI. Reference atrial signal amplitude in VI was 0.18 (0.11) mV, compared to 0.17 (0.10) mV (STC), 0.12 (0.09) mV (PCA), and 0.18 (0.13) mV (ICA) in the extracted atrial signals. PCA tended to attenuate the atrial signal in these segments. There were no significant differences for any of the algorithms when comparing the amplitude of the reference atrial signal with that of the extracted atrial signals in segments in which ventricular activity had been removed. There were no significant differences between algorithms in the frequency characteristics of the extracted atrial signals. There were discrepancies in amplitude and frequency characteristics of the atrial signal in only a few cases resulting from notable residual ventricular activity for PCA and ICA algorithms. In conclusion, the extracted atrial signals from these algorithms exhibit very similar amplitude and frequency characteristics. Users of these algorithms should be observant of residual ventricular activities which can affect the analysis of the fibrillatory waveform in clinical practice. Index Terms--Atrial fibrillation, atrial signal, comparative study, independent component analysis, principal component analysis, spatiotemporal QRST cancellation.

Split-thickness pig skin was transplanted on severe combined immunodeficient mice so that pig dermal microvessels spontaneously inosculated with mouse microvessels and functioned to perfuse the grafts. Pig endothelial cells in the healed grafts constitutively expressed class I and class II major histocompatibility complex molecules. Major histocompatibility complex molecule expression could be further increased by intradermal injection of pig interferon-[Gamma] (IFN-[Gamma]) but not human IFN-[Gamma] or tumor necrosis factor. Grafts injected with pig IFN-[Gamma] also developed a sparse infiltrate of mouse neutrophils and eosinophils without evidence of injury. Introduction of human peripheral blood mononuclear cells into the animals by intraperitoneal inoculation resulted in sparse perivascular mononuclear cell infiltrates in the grafts confined to the pig dermis. Injection of pig skin grafts on mice that received human peripheral blood mononuclear cells with pig IFN-[Gamma] (but not human IFN-[Gamma] or heat-inactivated pig IFN-[Gamma]) induced human CD[4.sup.+] and CD[8.sup.+] T cells and macrophages to more extensively infiltrate the pig skin grafts and injure pig dermal microvessels. These findings suggest that human T cell-mediated rejection of xenotransplanted pig organs may be prevented if cellular sources of pig interferon (e.g., passenger lymphocytes) are eliminated from the graft.

A chimeric model of allogenic T lymphocyte-induced human microvascular injury in severe-combined immunodeficient mice engrafted with human skin proposes that T cells infiltrate and mediate the dermal microvessel damage in mice reconstituted with allogenic human lymphocytes. Vascular cell adhesion molecule 1 brings the T cells to the injured area of the skin while alloantigen initiates the activity of these cells.