Research Article
Abstract
Endothelial progenitor cell (EPC) transplantation has beneficial effects for therapeutic neovascularization; however, only a small proportion of injected cells home to the lesion and incorporate into the neocapillaries. Consequently, this type of cell therapy requires substantial improvement to be of clinical value. Erythropoietin-producing human hepatocellular carcinoma (Eph) receptors and their ephrin ligands are key regulators of vascular development. We postulated that activation of the EphB4/ephrin-B2 system may enhance EPC proangiogenic potential. In this report, we demonstrate in a nude mouse model of hind limb ischemia that EphB4 activation with an ephrin-B2–Fc chimeric protein increases the angiogenic potential of human EPCs. This effect was abolished by EphB4 siRNA, confirming that it is mediated by EphB4. EphB4 activation enhanced P selectin glycoprotein ligand-1 (PSGL-1) expression and EPC adhesion. Inhibition of PSGL-1 by siRNA reversed the proangiogenic and adhesive effects of EphB4 activation. Moreover, neutralizing antibodies to E selectin and P selectin blocked ephrin-B2–Fc–stimulated EPC adhesion properties. Thus, activation of EphB4 enhances EPC proangiogenic capacity through induction of PSGL-1 expression and adhesion to E selectin and P selectin. Therefore, activation of EphB4 is an innovative and potentially valuable therapeutic strategy for improving the recruitment of EPCs to sites of neovascularization and thereby the efficiency of cell-based proangiogenic therapy.
Authors
Philippe Foubert, Jean-Sébastien Silvestre, Boussad Souttou, Véronique Barateau, Coralie Martin, Téni G. Ebrahimian, Carole Leré-Déan, Jean Olivier Contreres, Eric Sulpice, Bernard I. Levy, Jean Plouët, Gérard Tobelem, Sophie Le Ricousse-Roussanne
Abstract
Initial immune responses to allergens may occur before birth, thereby modulating the subsequent development of atopy. This paradigm remains controversial, however, due to the inability to identify antigen-specific T cells in cord blood. The advent of MHC tetramers has revolutionized the detection of antigen-specific T cells. Tetramer staining of cord blood after CMV infection has demonstrated that effective CD8+ antigen-specific immune responses can follow intrauterine viral infections. We hypothesized that sensitization to antigens occurs in utero in humans. We studied cord blood B and T cell immune responses following vaccination against influenza during pregnancy. Anti-Fluzone and anti-matrix protein IgM antibodies were detected in 38.5% (27 of 70) and 40.0% (28 of 70), respectively, of cord blood specimens. Using MHC tetramers, HA-specific CD4+ T cells were detected among 25.0% (3 of 12) and 42.9% (6 of 14) of cord blood specimens possessing DRB1*0101 and DRB1*0401 HLA types, respectively, and were detected even when the DRB1 HLA type was inherited from the father. Matrix protein–specific CD8+ T cells were detected among 10.0% (2 of 20) of HLA-A*0201+ newborns. These results suggest that B and T cell immune responses occur in the fetus following vaccination against influenza and have important implications for determining when immune responses to environmental exposures begin.
Authors
Deepa Rastogi, Chaodong Wang, Xia Mao, Cynthia Lendor, Paul B. Rothman, Rachel L. Miller
Abstract
This study reports on what we believe are novel mechanism(s) of the vascular protective action of adiponectin. We used intravital microscopy to measure leukocyte-endothelium interactions in adiponectin-deficient (Ad–/–) mice and found that adiponectin deficiency was associated with a 2-fold increase in leukocyte rolling and a 5-fold increase in leukocyte adhesion in the microcirculation. Measurement of endothelial NO (eNO) revealed that adiponectin deficiency drastically reduced levels of eNO in the vascular wall. Immunohistochemistry demonstrated increased expression of E-selectin and VCAM-1 in the vascular endothelium of Ad–/– mice. Systemic administration of the recombinant globular adiponectin domain (gAd) to Ad–/– mice significantly attenuated leukocyte-endothelium interactions and adhesion molecule expression in addition to restoring physiologic levels of eNO. Importantly, prior administration of gAd also protected WT mice against TNF-α–induced leukocyte-endothelium interactions, indicating a pharmacologic action of gAd. Mechanistically, blockade of eNOS with Nω-nitro-l-arginine methyl ester (l-NAME) abolished the inhibitory effect of gAd on leukocyte adhesion, demonstrating the obligatory role of eNOS signaling in the antiinflammatory action of gAd. We believe this is the first demonstration that gAd protects the vasculature in vivo via increased NO bioavailability with suppression of leukocyte-endothelium interactions. Overall, we provide evidence that loss of adiponectin induces a primary state of endothelial dysfunction with increased leukocyte-endothelium adhesiveness.
Authors
Raogo Ouedraogo, Yulan Gong, Brett Berzins, Xiandong Wu, Kalyankar Mahadev, Kelly Hough, Lawrence Chan, Barry J. Goldstein, Rosario Scalia
Abstract
Activation of the transcription factor NF-κB/Rel has been shown to be involved in inflammatory disease. Here we studied the role of RelA/p65, the main transactivating subunit, during acute pancreatitis using a Cre-loxP strategy. Selective truncation of the rela gene in pancreatic exocrine cells led to both severe injury of the acinar cells and systemic complications including lung and liver damage. Our data demonstrated that expression and induction of the protective pancreas-specific acute phase protein pancreatitis-associated protein 1 (PAP1) depended on RelA/p65. Lentiviral gene transfer of PAP1 cDNA reduced the extent of necrosis and infiltration in the pancreata of mice with selective truncation of RelA/p65. These results provide in vivo evidence for RelA/p65 protection of acinar cell death via upregulation of PAP1. Moreover, our data underscore the pancreas-specific role of NF-κB/Rel and suggest multidimensional roles of NF-κB/Rel in different cells and contexts during inflammation.
Authors
Hana Algül, Matthias Treiber, Marina Lesina, Hassan Nakhai, Dieter Saur, Fabian Geisler, Alexander Pfeifer, Stephan Paxian, Roland M. Schmid
Abstract
In recent years, the transient receptor potential melastatin member 8 (TRPM8) channel has emerged as a promising prognostic marker and putative therapeutic target in prostate cancer (PCa). However, the mechanisms of prostate-specific regulation and functional evolution of TRPM8 during PCa progression remain unclear. Here we show, for the first time to our knowledge, that only secretory mature differentiated human prostate primary epithelial (PrPE) luminal cells expressed functional plasma membrane TRPM8 (PMTRPM8) channels. Moreover, PCa epithelial cells obtained from in situ PCa were characterized by a significantly stronger PMTRPM8-mediated current than that in normal cells. This PMTRPM8 activity was abolished in dedifferentiated PrPE cells that had lost their luminal secretory phenotype. However, we found that in contrast to PMTRPM8, endoplasmic reticulum TRPM8 (ERTRPM8) retained its function as an ER Ca2+ release channel, independent of cell differentiation. We hypothesize that the constitutive activity of ERTRPM8 may result from the expression of a truncated TRPM8 splice variant. Our study provides insight into the role of TRPM8 in PCa progression and suggests that TRPM8 is a potentially attractive target for therapeutic intervention: specific inhibition of either ERTRPM8 or PMTRPM8 may be useful, depending on the stage and androgen sensitivity of the targeted PCa.
Authors
Gabriel Bidaux, Matthieu Flourakis, Stéphanie Thebault, Alexander Zholos, Benjamin Beck, Dimitra Gkika, Morad Roudbaraki, Jean-Louis Bonnal, Brigitte Mauroy, Yaroslav Shuba, Roman Skryma, Natalia Prevarskaya
Abstract
Circulating resistin stimulates endogenous glucose production (GP). Here, we report that bi-directional changes in hypothalamic resistin action have dramatic effects on GP and proinflammatory cytokine expression in the liver. The infusion of either resistin or an active cysteine mutant in the third cerebral ventricle (icv) or in the mediobasal hypothalamus stimulated GP independent of changes in circulating levels of glucoregulatory hormones. Conversely, central antagonism of resistin action markedly diminished the ability of circulating resistin to enhance GP. We also report that centrally mediated mechanisms partially control resistin-induced expression of TNF-α, IL-6, and SOCS-3 in the liver. These results unveil what we believe to be a novel site of action of resistin on GP and inflammation and suggest that hypothalamic resistin action can contribute to hyperglycemia in type 2 diabetes mellitus.
Authors
Evan D. Muse, Tony K.T. Lam, Philipp E. Scherer, Luciano Rossetti
Abstract
The ileal mucosa of Crohn disease (CD) patients is abnormally colonized by adherent-invasive E. coli (AIEC) that are able to adhere to and invade intestinal epithelial cells. Here, we show that CD-associated AIEC strains adhere to the brush border of primary ileal enterocytes isolated from CD patients but not controls without inflammatory bowel disease. AIEC adhesion is dependent on type 1 pili expression on the bacterial surface and on carcinoembryonic antigen–related cell adhesion molecule 6 (CEACAM6) expression on the apical surface of ileal epithelial cells. We report also that CEACAM6 acts as a receptor for AIEC adhesion and is abnormally expressed by ileal epithelial cells in CD patients. In addition, our in vitro studies show that there is increased CEACAM6 expression in cultured intestinal epithelial cells after IFN-γ or TNF-α stimulation and after infection with AIEC bacteria, indicating that AIEC can promote its own colonization in CD patients.
Authors
Nicolas Barnich, Frédéric A. Carvalho, Anne-Lise Glasser, Claude Darcha, Peter Jantscheff, Matthieu Allez, Harald Peeters, Gilles Bommelaer, Pierre Desreumaux, Jean-Frédéric Colombel, Arlette Darfeuille-Michaud
Abstract
Increased fat deposition in skeletal muscle is associated with insulin resistance. However, exercise increases both intramyocellular fat stores and insulin sensitivity, a phenomenon referred to as “the athlete’s paradox”. In this study, we provide evidence that augmenting triglyceride synthesis in skeletal muscle is intrinsically connected with increased insulin sensitivity. Exercise increased diacylglycerol (DAG) acyltransferase (DGAT) activity in skeletal muscle. Channeling fatty acid substrates into TG resulted in decreased DAG and ceramide levels. Transgenic overexpression of DGAT1 in mouse skeletal muscle replicated these findings and protected mice against high-fat diet–induced insulin resistance. Moreover, in isolated muscle, DGAT1 deficiency exacerbated insulin resistance caused by fatty acids, whereas DGAT1 overexpression mitigated the detrimental effect of fatty acids. The heightened insulin sensitivity in the transgenic mice was associated with attenuated fat-induced activation of DAG-responsive PKCs and the stress mediator JNK1. Consistent with these changes, serine phosphorylation of insulin receptor substrate 1 was reduced, and Akt activation and glucose 4 membrane translocation were increased. In conclusion, upregulation of DGAT1 in skeletal muscle is sufficient to recreate the athlete’s paradox and illustrates a mechanism of exercise-induced enhancement of muscle insulin sensitivity. Thus, increasing muscle DGAT activity may offer a new approach to prevent and treat insulin resistance and type 2 diabetes mellitus.
Authors
Li Liu, Yiying Zhang, Nancy Chen, Xiaojing Shi, Bonny Tsang, Yi-Hao Yu
Abstract
Fatty acid oversupply is a key mediator of skeletal muscle insulin resistance in obesity, primarily via accumulation of fatty acid metabolites and activation of proinflammatory pathways. Herein, we demonstrate that fatty acid–induced insulin resistance in humans is completely prevented the day after 1 session of endurance exercise. Because skeletal muscle is the primary site for systemic glucose disposal and is highly susceptible to impaired insulin action by elevated fatty acid availability, we obtained skeletal muscle samples to investigate possible mechanisms mediating this protective effect of exercise. Prevention of fatty acid–induced insulin resistance after exercise accompanied enhanced skeletal muscle protein expression of key lipogenic enzymes and an increase in muscle triglyceride synthesis. Partitioning more fatty acids toward triglyceride synthesis within muscle reduced the accumulation of fatty acid metabolites and suppressed the proinflammatory response in skeletal muscle, as evidenced by decreased phosphorylation and activation of JNK and increased abundance of inhibitor of NF-κB α (IκB-α) and IκB-β. We believe this is the first study to demonstrate that 1 session of exercise completely reverses fatty acid–induced insulin resistance in humans. Reversal of insulin resistance accompanied enhanced lipogenic capacity within skeletal muscle, reduced accumulation of highly bioactive fatty acid metabolites, and suppressed activation of proinflammatory pathways known to impair insulin action.
Authors
Simon Schenk, Jeffrey F. Horowitz
Abstract
Single gene mutations in β integrins can account for functional defects of individual cells of the hematopoietic system. In humans, mutations in β2 integrin lead to leukocyte adhesion deficiency (LAD) syndrome and mutations in β3 integrin cause the bleeding disorder Glanzmann thrombasthenia. However, multiple defects in blood cells involving various β integrins (β1, β2, and β3) occur simultaneously in patients with the recently described LAD type III (LAD-III). Here we show that the product of a single gene, Ca2+ and diacylglycerol-regulated guanine nucleotide exchange factor I (CalDAG-GEFI), controlled the activation of all 3 integrins in the hematopoietic system. Neutrophils from CalDAG-GEFI–/– mice exhibited strong defects in Rap1 and β1 and β2 integrin activation while maintaining normal calcium flux, degranulation, and ROS generation. Neutrophils from CalDAG-GEFI–deficient mice failed to adhere firmly to stimulated venules and to migrate into sites of inflammation. Furthermore, CalDAG-GEFI regulated the activation of β1 and β3 integrins in platelets, and CalDAG-GEFI deficiency caused complete inhibition of arterial thrombus formation in mice. Thus, mice engineered to lack CalDAG-GEFI have a combination of defects in leukocyte and platelet functions similar to that of LAD-III patients.
Authors
Wolfgang Bergmeier, Tobias Goerge, Hong-Wei Wang, Jill R. Crittenden, Andrew C.W. Baldwin, Stephen M. Cifuni, David E. Housman, Ann M. Graybiel, Denisa D. Wagner
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