Sera from preeclampsia patients elicit symptoms of human disease in mice and provide a basis for an in vitro predictive assay

Early diagnosis and treatment of preeclampsia would significantly reduce maternal and fetal morbidity and mortality. However, its etiology and prediction have remained elusive. Based on the hypothesis that sera from patients with preeclampsia could function as a "blueprint" of causative factors, we describe a serum-based pregnancy-specific mouse model that closely mirrors the human condition as well as an in vitro predictive assay. We show that a single administration of human preeclampsia serum in pregnant IL-10-/- mice induced the full spectrum of preeclampsia-like symptoms, caused hypoxic injury in uteroplacental tissues, and elevated soluble fms-like tyrosine kinase 1 and soluble endoglin, markers thought to be related to the disease. The same serum sample(s) induced a partial preeclampsia phenotype in wild-type mice. Importantly, preeclampsia serum disrupted cross talk between trophoblasts and endothelial cells in an in vitro model of endovascular activity. Disruption of endovascular activity could be documented in serum samples as early as 12 to 14 weeks of gestation from patients who subsequently developed preeclampsia. These results indicate that preeclampsia patient sera can be used to understand the pregnancy-specific disease pathology in mice and can predict the disorder.

Maternal cigarette smoking during pregnancy is associated with downregulation of miR-16, miR-21, and miR-146a in the placenta

Maternal cigarette smoking during pregnancy is associated with poor fetal outcome and aberrant miRNA expression is associated with adverse pregnancy outcomes. In 25 human placentas, we analyzed the expression of four candidate miRNA previously implicated in growth and developmental processes: miR-16, miR-21, miR-146a, and miR-182, and used three immortalized placental cell lines to identify if specific components of cigarette smoke were responsible for alterations to miRNA expression. miR-16, miR-21, and miR-146a were significantly downregulated in cigarette smoke-exposed placentas compared to controls. TCL-1 cells exposed to both nicotine and benzo(a)pyrene exhibited significant, dose-dependent downregulation of miR-146a. These results suggest that miR-146a is particularly responsive to exposures, and that smoking may elicit some of its downstream effects through alteration of miRNA expression.

Inter-alpha inhibitor protein administration improves survival from neonatal sepsis in mice

Inter-alpha inhibitor proteins (IaIp) are serine proteases inhibitors that modulate endogenous protease activity and have been shown to improve survival in adult models of sepsis. We evaluated the effect of IaIp on survival and systemic responses to sepsis in neonatal mice. Sepsis was induced in 2-d-old mice with lipopolysaccharide (LPS), Escherichia coli, and group B Streptococci. Sepsis was associated with 75% mortality. IaIp, given by i.p. administration at doses between 15 and 45 mg/kg from 1 to 6 h after the onset of sepsis, improved survival to approximately 90% (p = 0.0159) in both LPS-induced sepsis and with live bacterial infections. The greatest effect was on reversal of hemorrhagic pneumonitis. The effects were dose and time dependent. Systemic cytokine profile and tissue histology were examined. Survival was compared in IL-10 knock out animals. Systemic cytokine levels including TNF-[alpha] and IL-10 were increased after induction of sepsis and modulated significantly after IaIp administration. Because the effect of IaIp was still demonstrable in IL-10 deficient mice, we conclude the beneficial effects of IaIp is because of suppression of proinflammatory cytokines such as TNF-[alpha] rather than augmentation of IL-10. IaIp may offer significant benefits as a therapeutic

Role of the L-amino acid transporter-1 (LAT-1) in mouse trophoblast cell invasion

LAT-1 (L-type amino acid transporter 1) is a system L, Na(+)-independent amino acid transporter responsible for transport of large neutral amino acids. Dysregulated expression of LAT-1 is characteristic of many primary human cancers and it's over expression is related to tumor invasion. LAT-1 is highly expressed in the trophoblast giant cells (TGCs) at the time of implantation. Since trophoblast giant cells are highly invasive during the process of endometrial implantation and placentation, LAT-1 may play a role in the invasive phenotype. Our objectives were to identify the effects of increased and decreased LAT-1 expression on mouse trophoblast invasion. We therefore examined the role of amino acid deprivation, pharmacologic blockade specific to leucine transport and gene silencing (siRNA) on LAT-1 expression and trophoblast cell invasion. We utilized mouse primary trophoblast stem (TS) cells. LAT-1 mRNA expression was quantified by real time qPCR, protein by Western blotting and cell invasion was measured in Transwell plates through Matrigel. Amino acid transport using uptake of tritiated leucine. Under limited leucine availability and/or pharmacologic blockage, LAT-1 gene expression was significantly increased, p<0.05. This was associated with a 3-fold increase in cell invasion, p<0.05. In contrast, following siRNA-mediated gene silencing decreased LAT-1 expression (both mRNA and protein) was associated with decreased cell invasion and decreased leucine uptake, p<0.05. Upregulation of LAT-1 gene expression via limited amino acid availability or following pharmacologic blockade of transport leads to an increase in mouse trophoblast stem cell invasiveness. Downregulation of LAT-1 expression via genetic silencing leads to inhibition of invasiveness. These results demonstrate that LAT-1 plays an important role in trophoblast invasion.

Effect of disruption of Akt-1 of lin(-)c-kit(+) stem cells on myocardial performance in infarcted heart

AIMS

We have demonstrated an important role of bone marrow-derived stem cells in preservation of myocardial function. We investigated whether Akt-1 of lin(-)c-kit(+) stem cells preserves ventricular function following myocardial infarction (MI).

METHODS AND RESULTS

Isolated lin(-)c-kit(+) cells were conjugated with anti-c-kit heteroconjugated to anti-vascular cell adhesion molecule to facilitate the attachment of stem cells into damaged tissues. Female severe combined immunodeficient mice were used as recipients. MI was created by ligation of the left descending artery. After 48 h, animals were divided into four groups: (i) sham (n = 5): animals underwent thoracotomy without MI; (ii) MI (n = 5): animals underwent MI and received medium; (iii) MI + wild-type (Wt) stem cells (n = 6): MI animals received 5 x 10(5) Wt lin(-)c-kit(+) stem cells; (iv) MI + Akt-1(-/-) stem cells (n = 6): MI animals received 5 x 10(5) Akt-1(-/-) lin(-)c-kit(+) stem cells. Two weeks later, left ventricular function was measured in the Langendorff mode. The peripheral administration of Wt armed stem cells into MI animals restored ventricular function, which was absent in animals receiving Akt-1(-/-) cells. Real-time PCR indicates a decrease in SRY3, a Y chromosome marker in hearts receiving Akt-1(-/-) cells. An increase in angiogenic response was demonstrated in hearts receiving Wt stem cells but not Akt-1(-/-) stem cells.

CONCLUSION

Our results demonstrate that the peripheral administration of Wt lin(-)c-kit(+) stem cells restores ventricular function and promotes angiogenic response following MI. These benefits were abrogated in MI mice receiving Akt-1(-/-) stem cells, suggesting the pivotal role of Akt-1 in mediating stem cells to protect MI hearts.

Seven-month developmental outcomes of very low birth weight infants enrolled in a randomized controlled trial of delayed versus immediate cord clamping

OBJECTIVE

The results from our previous trial revealed that infants with delayed cord clamping (DCC) had significantly lesser intraventricular hemorrhage (IVH) and late-onset sepsis (LOS) than infants with immediate cord clamping (ICC). A priori, we hypothesized that infants with DCC would have better motor function by 7 months corrected age.

STUDY DESIGN

Infants between 24 and 31 weeks were randomized to ICC or DCC and follow-up evaluation was completed at 7 months corrected age.

RESULT

We found no differences in the Bayley Scales of Infant Development (BSID) scores between the DCC and ICC groups. However, a regression model of effects of DCC on motor scores controlling for gestational age, IVH, bronchopulmonary dysplasia, sepsis and male gender suggested higher motor scores of male infants with DCC.

CONCLUSION

DCC at birth seems to be protective of very low birth weight male infants against motor disability at 7 months corrected age.

Fetal effects of psychoactive drugs

Psychoactive drug use by pregnant women has the potential to effect fetal development; the effects are often thought to be drug-specific and gestational age dependent. This article describes the effects of three drugs with similar molecular targets that involve monoaminergic transmitter systems: cocaine, methamphetamine, and selective serotonin re-uptake inhibitors (SSRIs) used to treat maternal depression during pregnancy. We propose a possible common epigenetic mechanism for their potential effects on the developing child. We suggest that exposure to these substances acts as a stressor that affects fetal programming, disrupts fetal placental monoamine transporter expression and alters neuroendocrine and neurotransmitter system development. We also discuss neurobehavioral techniques that may be useful in the early detection of the effects of in utero drug exposure.

Aging and environmental exposures alter tissue-specific DNA methylation dependent upon CpG island context

Epigenetic control of gene transcription is critical for normal human development and cellular differentiation. While alterations of epigenetic marks such as DNA methylation have been linked to cancers and many other human diseases, interindividual epigenetic variations in normal tissues due to aging, environmental factors, or innate susceptibility are poorly characterized. The plasticity, tissue-specific nature, and variability of gene expression are related to epigenomic states that vary across individuals. Thus, population-based investigations are needed to further our understanding of the fundamental dynamics of normal individual epigenomes. We analyzed 217 non-pathologic human tissues from 10 anatomic sites at 1,413 autosomal CpG loci associated with 773 genes to investigate tissue-specific differences in DNA methylation and to discern how aging and exposures contribute to normal variation in methylation. Methylation profile classes derived from unsupervised modeling were significantly associated with age (P<0.0001) and were significant predictors of tissue origin (P<0.0001). In solid tissues (n = 119) we found striking, highly significant CpG island–dependent correlations between age and methylation; loci in CpG islands gained methylation with age, loci not in CpG islands lost methylation with age (P<0.001), and this pattern was consistent across tissues and in an analysis of blood-derived DNA. Our data clearly demonstrate age- and exposure-related differences in tissue-specific methylation and significant age-associated methylation patterns which are CpG island context-dependent. This work provides novel insight into the role of aging and the environment in susceptibility to diseases such as cancer and critically informs the field of epigenomics by providing evidence of epigenetic dysregulation by age-related methylation alterations. Collectively we reveal key issues to consider both in the construction of reference and disease-related epigenomes and in the interpretation of potentially pathologically important alterations.

The causes and extent of tissue-specific interindividual variation in human epigenomes are underappreciated and, hence, poorly characterized. We surveyed over 200 carefully annotated human tissue samples from ten anatosites at 1,413 CpGs for methylation alterations to appraise the nature of phenotypically, and hence potentially clinically important epigenomic alterations. Within tissue types, across individuals, we found variation in methylation that was significantly related to aging and environmental exposures such as tobacco smoking. Individual variation in age- and exposure-related methylation may significantly contribute to increased susceptibility to several diseases. As the NIH–funded HapMap project is critically contributing to annotating the human reference genome defining normal genetic variability, our work raises key issues to consider in the construction of reference epigenomes. It is well recognized that understanding genetic variation is essential to understanding disease. Our work, and the known interplay of epigenetics and genetics, makes it equally clear that a more complete characterization of epigenetic variation and its sources must be accomplished to reach the goal of a complete understanding of disease. Additional research is absolutely necessary to define the mechanisms controlling epigenomic variation. We have begun to lay the foundations for essential normal tissue controls for comparison to diseased tissue, which will allow the identification of the most crucial disease-related alterations and provide more robust targets for novel treatments.

Adrenal Epinephrine and the Regulation of Pulmonary Surfactant Release in Neonatal Rabbits

Adrenergic mechanisms influence surfactant metabolism; however the nature and importance of catechol-mediated regulation is unclear. We designed experiments to assess the role of endogenous adrenal epinephrine (E) synthesis in neonatal alveolar surfactant release. We administered the experimental adrenal epinephrine synthesis inhibitor SKF 29661 to pregnant rabbits to reduce fetal adrenal E content. Surfactant release was measured as total alveolar phosphatidylcholine (PC) content recovered by a thorough alveolar wash performed on animals sacrificed at birth and at 1 h of age. At a maternal dose of 100 mg/kg/day, SKF 29661 caused a 57% reduction in fetal adrenal E content (p less than .01), which was associated with a 40% reduction in alveolar PC at birth and a 23% reduction in alveolar PC at 1 h of age (p less than .01). Moreover, adrenal E correlated positively with total alveolar PC content (p less than .001). These results suggest that in the neonatal period, the ability of the fetal adrenal gland to synthesize E for secretion plays a role in the regulation of pulmonary surfactant release.

Third pathophysiology of prenatal cocaine exposure

The pathophysiology of the effects of cocaine on fetal development has been described along 2 major pathways: neurochemical effects and vasoconstrictive effects. Following a summary of these effects, we suggest a 'third pathophysiology' in which altered fetal programming affects the acute and long-term adverse effects of in utero cocaine exposure. We describe how cocaine as a stressor alters the expression of key candidate genes, increasing exposure to catecholamines and fetal cortisol-altering neuroendocrine (hypothalamic-pituitary-adrenal axis) activity, leading to infant behavioral dysregulation, poor behavioral control and emotion regulation during childhood and phenotypes that confer vulnerability to substance use in adolescence. This model is discussed in relation to follow-up studies of the effects of in utero cocaine exposure and maturational changes in brain development.

The role of inter-alpha inhibitor proteins in the diagnosis of neonatal sepsis

We evaluated Inter-alpha inhibitor proteins (IaIp) as a diagnostic marker in neonatal sepsis. Samples were collected from 573 neonates who were examined for suspected sepsis. IaIp level was significantly lower in the septic group (121+/-71 mg/L) than in the non-septic group (322+/-91 mg/L). The optimal cutoff value with the receiver operating characteristic curve was <or= 177 mg/L (sensitivity, 89.5%; specificity, 99%; positive predictive value, 95%; negative predictive value, 98%) with area under the curve of 0.94. IaIp is a more reliable diagnostic marker for neonatal sepsis than other available tests.

Evidence for participation of uterine natural killer cells in the mechanisms responsible for spontaneous preterm labor and delivery

OBJECTIVE

The purpose of this study was to determine in a mouse model whether uterine natural killer (uNK) cell cytotoxic activation induces infection/inflammation-associated preterm labor and delivery.

STUDY DESIGN

Wild type or interleukin (IL)-10(-/-) mice were injected intraperitoneally with lipopolysaccharide on gestational day 14. Mice were either killed for collection of uteroplacental tissue, spleen, and serum or allowed to deliver. Uteroplacental tissue was used for histology and characterization of uNK cells.

RESULTS

Low-dose lipopolysaccharide treatment triggered preterm labor and delivery in IL-10(-/-), but not wild type mice, in a manner independent of progesterone levels. Preterm labor and delivery in IL-10(-/-) mice was associated with an increased number and placental infiltration of cytotoxic uNK cells and placental cell death. Depletion of NK cells or tumor necrosis factor (TNF)-alpha neutralization in these mice restored term delivery. Furthermore, TNF-alpha neutralization prevented uNK cell infiltration and placental cell apoptosis.

CONCLUSION

The uNK cell-TNF-alpha-IL-10 axis plays an important role in the genesis of infection/inflammation-induced preterm labor/delivery.

LAT-1 expression in pre- and post-implantation embryos and placenta

OBJECTIVES

LAT-1 (L-type amino acid transporter 1) is a system L, Na(+)-independent amino acid transporter responsible for transport of large neutral amino acids. Dysregulated expression of LAT-1 is characteristic of many primary human cancers and is related to tumor invasion. Primary rat hepatocytes in culture increase LAT-1 mRNA in response to amino acid depletion. Transformed hepatic cell lines demonstrate constitutive expression of LAT-1. These observations suggest that LAT-1 expression confers a growth and survival advantage under limited amino acid availability. LAT-1 is highly expressed in the placenta. It has been shown previously that amino acids are fundamental regulators of cell function and energy metabolism in pre-implantation embryos. Our objectives were to analyze qualitatively and quantitatively LAT-1 expression in pre-implantation stages of mouse embryo development and to identify cell types expressing LAT-1 in post-implantation stages.

METHODS

LAT-1 was quantified by real-time qPCR. Localization of expression was by laser capture microdissection, in situ hybridization and immunohistochemistry.

RESULTS

Our results show increasing mRNA levels of LAT-1 as the embryo develops from zygote to blastocyst with highest levels at hatching blastocyst. Expression studies of LAT-1 on microdissected samples from developing mouse placenta show highest levels of LAT-1 mRNA in trophoblast giant cells (TGCs) at the time of implantation (E7.5), followed by maternal decidua, ectoplacental cone and epiblast. At later stages of development (E9.5 and E11.5) no differential expression of LAT-1 was observed. In situ hybridization and immunohistochemistry also showed differential expression of LAT-1 mRNA and protein, respectively, with darkest staining in TGCs at E7.5. By E9.5 and E11.5 mRNA expression was no longer preferentially localized to TGCs, hybridization was equal across the different cell types and regions. LAT-1 protein expression, however, still showed highest intensity of staining in TGCs at E9.5 and E11.5.

CONCLUSIONS

Since trophoblast giant cells are invasive cells that displace and phagocytose the uterine epithelial cells, these data suggest that LAT-1 may play a role in the invasive phenotype. The mechanism of LAT-1 regulation during placentation, therefore, might provide valuable clues to its role in tumor progression and invasion.

Beta-adrenergic receptor mediated protection against doxorubicin-induced apoptosis in cardiomyocytes: the impact of high ambient glucose

Recent studies have demonstrated that the beta2-adrenergic receptor (beta2AR)-Galphai signaling pathway exerts a cardiac antiapoptotic effect. The goals of this study were to determine the intracellular signaling factors involved in beta2AR-mediated protection against doxorubicin-induced apoptosis in H9c2 cardiomyocyte and explore the impact of high ambient glucose on the antiapoptotic effect. Under physiological glucose environment (100 mg/dl), beta2AR stimulation prevented doxorubicin-induced apoptosis, which was attenuated by cotreatment with wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor, or transfection of a dominant-negative Akt. Inhibition of Src kinase with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d] pyrimidine or cSrc small interfering RNA 32 also attenuated the antiapoptotic effect. Inhibition of platelet-derived growth factor receptor (PDGFR) with AG1296 reversed the beta2AR-induced antiapoptotic effect. Transfection of an active Src cDNA (Y529F) alone was sufficient to render the cells resistant to apoptosis, and the resistance was blocked by wortmannin. Transfection of an active PI3K minigene (iSH2-p110) alone also induced resistance to apoptosis, and the resistance was reversed by an Akt-inhibitor but not by AG1296. High ambient glucose (450 mg/dl) caused two major effects: 1) it significantly reduced betaAR-induced PDGFR phosphorylation, Src kinase activity, and activation of PI3K signaling pathway; and 2) it partially attenuated beta2AR-induced antiapoptotic effect. These data provide in vitro evidence supporting a signaling cascade by which beta2AR exerts a protective effect against doxorubicin-induced apoptosis via sequential involvement of Galphai, Gbetagamma, Src, PDGFR, PI3K, and Akt. High ambient glucose significantly attenuates beta2AR-mediated cardioprotection by suppressing factors involved in this cascade including PDGFR, Src, and PI3K/Akt.

Fate and effects of adult bone marrow cells in lungs of normoxic and hyperoxic newborn mice

Cell-based therapy in adult lung injury models is associated with highly variable donor cell engraftment and epithelial reconstitution. The role of marrow-derived cell therapy in neonatal lung injury is largely unknown. In this study, we determined the fate and effects of adult bone marrow cells in a model of neonatal lung injury. Wild-type mice placed in a normoxic or hyperoxic (95% O(2)) environment received bone marrow cells from animals expressing green fluorescent protein (GFP) at Postnatal Day (P)5. Controls received vehicle buffer. Lungs were analyzed between Post-Transplantation (TPX) Day 2 and Week 8. The volume of GFP-immunoreactive donor cells, monitored by stereologic volumetry, remained constant between Post-TPX Weeks 1 and 8 and was similar in normoxic and hyperoxia-exposed recipients. Virtually all marrow-derived cells showed colocalization of GFP and the pan-macrophage marker, F4/80, by double immunofluorescence studies. Epithelial transdifferentiation was not seen. Marrow cell administration had adverse effects on somatic growth and alveolarization in normoxic mice, while no effects were discerned in hyperoxia-exposed recipients. Reexposure of marrow-treated animals to hyperoxia at P66 resulted in significant expansion of the donor-derived macrophage population. In conclusion, intranasal administration of unfractionated bone marrow cells to newborn mice does not achieve epithelial reconstitution, but establishes persistent alveolar macrophage chimerism. The predominantly adverse effects of marrow treatment in newborn lungs are likely due to macrophage-associated paracrine effects. While this model and route of cell therapy may not achieve epithelial reconstitution, the role of selected stem cell populations and/or alternate routes of administration for cell-based therapy in injured newborn lungs deserve further investigation.

Temporally controlled overexpression of cardiac-specific PI3Kalpha induces enhanced myocardial contractility--a new transgenic model

The phosphatidylinositol 3-kinase (PI3K) signaling pathway regulates multiple cellular processes including cell survival/apoptosis and growth. In the cardiac context, PI3Kalpha plays important roles in cardiac growth. We have shown that cardiac PI3K activity is highly regulated during development, with the highest levels found during the fetal-neonatal transition period and the lowest levels in the adult. There is a close relationship between cardiomyocyte proliferation and cardiac PI3K activity. In adult transgenic mice, however, the prolonged constitutive activation of PI3Kalpha in the heart results in hypertrophy. To develop a strategy to allow temporally controlled overexpression of cardiac PI3Kalpha, we engineered a tetracycline (tet) transactivator tet-off controlled transgenic mouse line with a conditional overexpression of a cardiac-specific fusion protein of the SH2 domain of p85 and p110alpha. Cardiac PI3K activity and Akt phosphorylation were significantly increased in adult mice after transgene induction following the removal of doxycycline for 2 wk. The heart weight-to-body weight ratio was not changed, and there were no signs of cardiomyopathy. The overexpression of PI3Kalpha resulted in increased left ventricular (LV) developed pressure and the maximal and minimal positive values of the first derivative of LV pressure, but not heart rate, as assessed in Langendorff hearts. Mice overexpressing PI3Kalpha also had increases in the levels of Ca(2+)-regulating proteins, including the L-type Ca(2+) channels, ryanodine receptors, and sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a. Thus the temporally controlled overexpression of cardiac PI3Kalpha does not induce hypertrophy or cardiomyopathy but results in increased contractility, probably via the increased expression of multiple Ca(2+)-regulating proteins. These distinct phenotypes suggest a fundamental difference between transgenic mice with temporal or prolonged activation of cardiac PI3Kalpha.

Forced expression of the cell cycle inhibitor p57Kip2 in cardiomyocytes attenuates ischemia-reperfusion injury in the mouse heart

Background

Myocardial hypoxic-ischemic injury is the cause of significant morbidity and mortality worldwide. The cardiomyocyte response to hypoxic-ischemic injury is known to include changes in cell cycle regulators. The cyclin-dependent kinase inhibitor p57^Kip2 is involved in cell cycle control, differentiation, stress signaling and apoptosis. In contrast to other cyclin-dependent kinase inhibitors, p57^Kip2 expression diminishes during postnatal life and is reactivated in the adult heart under conditions of cardiac stress. Overexpression of p57^Kip2 has been previously shown to prevent apoptotic cell death in vitro by inhibiting stress-activated kinases. Therefore, we hypothesized that p57^Kip2 has a protective role in cardiomyocytes under hypoxic conditions. To investigate this hypothesis, we created a transgenic mouse (R26loxpTA-p57^k/+) that expresses p57^Kip2 specifically in cardiac tissue under the ventricular cardiomyocyte promoter Mlc2v.

Results

Transgenic mice with cardiac specific overexpression of p57^Kip2 are viable, fertile and normally active and their hearts are morphologically indistinguishable from the control hearts and have similar heart weight/body weight ratio. The baseline functional parameters, including left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), LVdp/dt_max, heart rate (HR) and rate pressure product (RPR) were not significantly different between the different groups as assessed by the Langendorff perfused heart preparation. However, after subjecting the heart ex vivo to 30 minutes of ischemia-reperfusion injury, the p57^Kip2 overexpressing hearts demonstrated preserved cardiac function compared to control mice with higher left ventricular developed pressure (63 ± 15 vs 30 ± 6 mmHg, p = 0.05), rate pressure product (22.8 ± 4.86 vs 10.4 ± 2.1 × 10³bpm × mmHg, p < 0.05) and coronary flow (3.5 ± 0.5 vs 2.38 ± 0.24 ml/min, p <0.05).

Conclusion

These data suggest that forced cardiac expression of p57^Kip2 does not affect myocardial growth, differentiation and baseline function but attenuates injury from ischemia-reperfusion in the adult mouse heart.

Targeting human CD34+ hematopoietic stem cells with anti-CD45 x anti-myosin light-chain bispecific antibody preserves cardiac function in myocardial infarction

We have previously shown that targeting human CD34(+) hematopoietic stem cells (HSC) with a bispecific antibody (BiAb) directed against myosin light chain (MLC) increases delivery of cells to the injured hearts and improves cardiac performance in the nude rat. In this study, we have sought to validate our previous observations and to perform more detailed determination of ventricular function in immunocompetent mice with myocardial infarction (MI) that were treated with armed CD34(+) HSC. We examined whether armed CD34(+) HSC would target the injured heart following MI and restore ventricular function in vitro. MI was created by ligation of the left anterior descending artery. After 48 h, adult ICR mice received either 0.5 x 10(6) human CD34(+) HSC armed with anti-CD45 x anti-MLC BiAb or an equal volume of medium through a single tail vein injection. Two weeks after stem cell administration, ventricular function of hearts from mice receiving armed CD34(+) HSC was significantly greater compared with the same parameters from control mice. Immunohistochemistry confirmed the accumulation of CD34(+) HSC in MI hearts infused with stem cells. Angiogenesis was significantly enhanced in CD34(+) HSC-treated heart as determined by vascular density per area. Furthermore, histopathological examination revealed that the retained cardiac function observed in CD34(+) HSC-treated mice was associated with decreased ventricular fibrosis. These results suggest that peripheral administration of armed CD34(+) HSC results in localization of CD34(+) HSC to injured myocardium and restores myocardial function.

Inhibition of histone deacetylases triggers pharmacologic preconditioning effects against myocardial ischemic injury

OBJECTIVES

Recent evidence has demonstrated the importance of histone deacetylases (HDAC) in the control of hypertrophic responses in the heart. However, it remains unknown whether inhibition of HDACs plays a role in myocardial ischemia and reperfusion (I/R) injury. We hypothesize that HDAC inhibition triggers preconditioning-like effects against I/R injury.

METHODS AND RESULTS

Isolated mouse hearts were perfused with 3 cycles of 5-minute infusion and 5-minute washout of 50 nM of trichostatin A (TSA), a potent inhibitor of HDACs to mimic early pharmacologic preconditioning. This was followed by 30 min of ischemia and 30 min of reperfusion. In addition, mice were treated with saline or TSA (0.1 mg/kg, i.p.) to investigate delayed pharmacologic preconditioning. Twenty-four hours later, the hearts were subjected to I/R. Ventricular function and infarct size were measured, and HDAC 3, 4 and 5 were assessed by Western blot and immunofluorescence. HDAC and p38 mitogen-activated protein kinase activities were determined. TSA produced marked improvements in post-ischemic ventricular function recovery and a reduction in infarct size in both early and delayed preconditioning. Cardioprotection elicited by TSA was abrogated by SB203580, an inhibitor of p38. HDAC 3, 4 and 5 proteins were detected in mouse myocardium. TSA treatments resulted in a significant inhibition of HDAC activity. HDAC inhibition caused a dramatic increase in phosphorylation of p38 and p38 activity. Notably, HDAC inhibition also resulted in remarkable acetylation of p38 at lysine residues.

CONCLUSION

These results suggest that inhibition of HDACs triggers pharmacologic preconditioning to protect the ischemic heart, which involves p38 activation.

A novel signaling pathway for β-adrenergic receptor-mediated activation of phosphoinositide 3-kinase in H9c2 cardiomyocytes

Stimulation of cardiac β-adrenergic receptors (β-AR) activates both the Gs- and Gi-coupled signaling cascades, including the phosphoinositide 3 kinase (PI3K) pathway, that have important physiological implications. Multiple isoforms of PI3K exist in the heart. The goals of this study were to examine the intracellular signaling pathways linking β-AR to PI3K and to identify the PI3K isoform mediating this transactivation in a cardiac context. Acute β-AR stimulation with isoproterenol resulted in increased tyrosine kinase-associated PI3K activity and phosphorylation of Akt and p70S6K in H9c2 cardiomyocytes. Cotreatment with ICI-118,551, but not CGP-20712, abolished the increase in PI3K activity, suggesting a β2-AR-mediated event. PI3K activation was also abrogated by cotreatment with pertussis toxin, 4-amino-5-(4-chlorophenyl)-7-( t-butyl)pyrazolol[3,4-d]pyrimidine (PP2, a selective Src-family tyrosine kinases inhibitor), or AG-1296 [selective platelet-derived growth factor receptor (PDGFR) inhibitor] but not with an inhibitor for protein kinase A, protein kinase C, Ras, adenylyl cyclase, epidermal growth factor receptor, or insulin-like growth factor-1 receptor. β-AR stimulation induced an increase in tyrosine phosphorylation of PDGFR, which was abolished by inhibition of Src either by PP2 or small interfering RNA. Moreover, H9c2 cardiomyocytes stably transfected with a vector expressing a Gβγ sequestrant peptide derived from the COOH-terminus of β-AR kinase-1 failed to activate PI3K after β-AR stimulation, suggesting Gβγ is required for the transactivation. Furthermore, acute β-AR stimulation in vivo resulted in increases in PDGFR-associated PI3K and PI3Kα isoform activities but not the activities of other isoforms (PI3Kβ, -δ, -γ) in adult mouse heart. Taken together, these data provide in vitro and in vivo evidence for a novel mechanism of β-AR-mediated transactivation of cardiac PI3Kα via sequential involvement of Gαi/Gβγ, Src, and PDGFR.

A novel phosphoinositide 3-kinase-dependent pathway for angiotensin II/AT-1 receptor-mediated induction of collagen synthesis in MES-13 mesangial cells

Chronic activation of the angiotensin II (ANG II) type 1 receptor (AT-1R) is critical in the development of chronic kidney disease. ANG II activates mesangial cells (MCs) and stimulates the synthesis of extracellular matrix components. To determine the molecular mechanisms underlying the induction of MC collagen, a mouse mesangial cell line MES-13 was employed. ANG II treatment induced an increase in collagen synthesis, which was abrogated by co-treatment with losartan (an AT-1R antagonist), wortmannin (a phosphoinositide 3-kinase (PI3K) inhibitor), an Akt inhibitor, and stable transfection of dominant negative-Akt1. ANG II induced a significant increase in PI3K activity, which was abolished by co-treatment with losartan or 2',5'-dideoxyadenosine (2',5'-DOA, an adenylyl cyclase inhibitor) but not by PD123319 (an AT-2R antagonist) or H89 (a protein kinase A (PKA) inhibitor). The Epac (exchange protein directly activated by cAMP)-specific cAMP analog, 8-pHPT-2'-O-Me-cAMP, significantly increased PI3K activity, whereas a PKA-specific analog, 6-benzoyladenosine-cAMP, showed no effect. The ANG II-induced increase in PI3K activity was also blocked by co-treatment with PP2, an Src inhibitor, or AG1478, an epidermal growth factor receptor (EGFR) antagonist. ANG II induced phosphorylation of Akt and p70S6K and EGFR, which was abrogated by knockdown of c-Src by small interference RNA. Knockdown of Src also effectively abolished ANG II-induced collagen synthesis. Conversely, stable transfection of a constitutively active Src mutant enhanced basal PI3K activity and collagen production, which was abrogated by AG1478 but not by 2',5'-DOA. Moreover, acute treatment with ANG II significantly increased Src activity, which was abrogated with co-treatment of 2',5'-DOA. Taken together, these results suggest that ANG II induces collagen synthesis in MCs by activating the ANG II/AT-1R-EGFR-PI3K pathway. This transactivation is dependent on cAMP/Epac but not on PKA. Src kinase plays a pivotal role in this signaling pathway between cAMP and EGFR. This is the first demonstration that an AT1R-PI3K/Akt crosstalk, along with transactivation of EGFR, mediates ANG II-induced collagen synthesis in MCs.