Myocyte-specific overexpressing HDAC4 promotes myocardial ischemia/reperfusion injury

Background

Histone deacetylases (HDACs) play a critical role in modulating myocardial protection and cardiomyocyte survivals. However, Specific HDAC isoforms in mediating myocardial ischemia/reperfusion injury remain currently unknown.

We used cardiomyocyte-specific overexpression of active HDAC4 to determine the functional role of activated HDAC4 in regulating myocardial ischemia and reperfusion in isovolumetric perfused hearts.

Methods

In this study, we created myocyte-specific active HDAC4 transgenic mice to examine the functional role of active HDAC4 in mediating myocardial I/R injury. Ventricular function was determined in the isovolumetric heart, and infarct size was determined using tetrazolium chloride staining.

Results

Myocyte-specific overexpressing activated HDAC4 in mice promoted myocardial I/R injury, as indicated by the increases in infarct size and reduction of ventricular functional recovery following I/R injury. Notably, active HDAC4 overexpression led to an increase in LC-3 and active caspase 3 and decrease in SOD-1 in myocardium. Delivery of chemical HDAC inhibitor attenuated the detrimental effects of active HDAC4 on I/R injury, revealing the pivotal role of active HDAC4 in response to myocardial I/R injury.

Conclusions

Taken together, these findings are the first to define that activated HDAC4 as a crucial regulator for myocardial ischemia and reperfusion injury.

Electronic supplementary material

The online version of this article (10.1186/s10020-018-0037-2) contains supplementary material, which is available to authorized users.

MicroRNA-125b Prevents Cardiac Dysfunction in Polymicrobial Sepsis by Targeting TRAF6-Mediated Nuclear Factor κB Activation and p53-Mediated Apoptotic Signaling

BACKGROUND

 This study examined the effect of microRNA-125b (miR-125b) on sepsis-induced cardiac dysfunction.

METHODS

 Mouse hearts were transfected with lentivirus expressing miR-125b (LmiR-125b) 7 days before cecal ligation and puncture (CLP)-induced sepsis. Cardiac function was examined by echocardiography before and 6 hours after CLP (n = 6/group). Survival was monitored following CLP-induced sepsis (n = 12/group).

RESULTS

 LmiR-125b transfection significantly attenuated cardiac dysfunction due to CLP-induced sepsis. Fractional shortening and ejection fraction values were significantly (P < .05) higher in the LmiR-125b-treated CLP group than in the untreated CLP group. Survival outcome in LmiR-125b-transfected septic mice was markedly improved, compared with mice with CLP-induced sepsis. Transfection of LmiR-125b into the heart significantly suppressed the expression of ICAM-1 and VCAM-1, decreased the accumulation of macrophages and neutrophils in the myocardium, and decreased serum levels of tumor necrosis factor α and interleukin 1β by targeting tumor necrosis factor receptor-associated factor 6 (TRAF6)-mediated nuclear factor κB (NF-κB) activation. In addition, sepsis-induced myocardial apoptosis was markedly attenuated by LmiR-125b transfection through suppression of p53, Bax, and Bak1 expression. In vitro transfection of endothelial cells with miR-125b mimics attenuate LPS-induced ICAM-1 and VCAM-1 expression by suppressing TRAF6 and NF-κB activation.

CONCLUSIONS

 Increased myocardial miR-125b expression attenuates sepsis-induced cardiac dysfunction and improves survival. miR-125b may be a target for septic cardiomyopathy.

Attenuation of Cardiac Dysfunction in Polymicrobial Sepsis by MicroRNA-146a Is Mediated via Targeting of IRAK1 and TRAF6 Expression

Cardiac dysfunction is a major consequence of sepsis/septic shock and contributes to the high mortality of sepsis. Innate and inflammatory responses mediated by TLRs play a critical role in sepsis-induced cardiac dysfunction. MicroRNA-146 (miR-146) was first identified as a negative regulator in innate immune and inflammatory responses induced by LPS. This study examined whether miR-146a will have a protective effect on sepsis-induced cardiac dysfunction. Lentivirus-expressing miR-146a (LmiR-146a) or lentivirus-expressing scrambled miR (LmiR-control) was delivered into the myocardium via the right carotid artery. Seven days after transfection, mice were subjected to cecal ligation and puncture (CLP). Untransfected mice were also subjected to CLP-induced sepsis. Cardiac function was examined by echocardiography before and 6 h after CLP. In vitro studies showed that increased miR-146a levels suppress LPS-induced IκBα phosphorylation and inflammatory cytokine production in both H9C2 cardiomyocytes and J774 macrophages. In vivo transfection of LmiR-146a attenuated sepsis-induced cardiac dysfunction. The values for percent ejection fraction and percent fractional shortening in LmiR-146a-transfected CLP mice were significantly greater than in untransfected CLP control. LmiR-146a transfection prevented sepsis-induced NF-κB activity, suppressed IRAK and TRAF6 expression in the myocardium, and attenuated sepsis-induced inflammatory cytokine production in both plasma and peritoneal fluid. In addition, LmiR-146a transfection decreased sepsis-induced infiltration of neutrophils and macrophages into the myocardium. LmiR-146a can also transfect macrophages in the periphery. We conclude that miR-146a attenuates sepsis-induced cardiac dysfunction by preventing NF-κB activation, inflammatory cell infiltration, and inflammatory cytokine production via targeting of IRAK and TRAF6 in both cardiomyocytes and inflammatory monocytic cells.

Poly (I:C) therapy decreases cerebral ischaemia/reperfusion injury via TLR3-mediated prevention of Fas/FADD interaction

Toll-like receptor (TLR)-mediated signalling plays a role in cerebral ischaemia/reperfusion (I/R) injury. Modulation of TLRs has been reported to protect against cerebral I/R injury. This study examined whether modulation of TLR3 with poly (I:C) will induce protection against cerebral I/R injury. Mice were treated with or without Poly (I:C) (n = 8/group) 1 hr prior to cerebral ischaemia (60 min.) followed by reperfusion (24 hrs). Poly (I:C) pre-treatment significantly reduced the infarct volume by 57.2% compared with untreated I/R mice. Therapeutic administration of Poly (I:C), administered 30 min. after cerebral ischaemia, markedly decreased infarct volume by 34.9%. However, Poly (I:C)-induced protection was lost in TLR3 knockout mice. In poly (I:C)-treated mice, there was less neuronal damage in the hippocampus compared with untreated I/R mice. Poly (I:C) treatment induced IRF3 phosphorylation, but it inhibited NF-κB activation in the brain. Poly (I:C) also decreased I/R-induced apoptosis by attenuation of Fas/FasL-mediated apoptotic signalling. In addition, Poly (I:C) treatment decreased microglial cell caspase-3 activity. In vitro data showed that Poly (I:C) prevented hypoxia/reoxygenation (H/R)-induced interaction between Fas and FADD as well as caspase-3 and -8 activation in microglial cells. Importantly, Poly (I:C) treatment induced co-association between TLR3 and Fas. Our data suggest that Poly (I:C) decreases in cerebral I/R injury via TLR3 which associates with Fas, thereby preventing the interaction of Fas and FADD, as well as microglial cell caspase-3 and -8 activities. We conclude that TLR3 modulation by Poly (I:C) could be a potential approach for protection against ischaemic stroke.

Cellular cardiomyoplasty: its past, present, and future

Cellular cardiomyoplasty is a cell therapy using stem cells or progenitor cells for myocardial regeneration to improve cardiac function and mitigate heart failure. Since we first published cellular cardiomyoplasty in 1989, this procedure became the innovative method to treat damaged myocardium other than heart transplantation. A significant improvement in cardiac function, metabolism, and perfusion is generally observed in experimental and clinical studies, but the improvement is mild and incomplete. Although safety, feasibility, and efficacy have been well documented for the procedure, the beneficial mechanisms remain unclear and optimization of the procedure requires further study. This chapter briefly reviews the stem cells used for cellular cardiomyoplasty and their clinical outcomes with possible improvements in future studies.

Activation of myocardial phosphoinositide-3-kinase p110α ameliorates cardiac dysfunction and improves survival in polymicrobial sepsis

Phosphoinositide-3-kinase (PI3K)/Akt dependent signaling has been shown to improve outcome in sepsis/septic shock. There is also ample evidence that PI3K/Akt dependent signaling plays a crucial role in maintaining normal cardiac function. We hypothesized that PI3K/Akt signaling may ameliorate septic shock by attenuating sepsis-induced cardiac dysfunction. Cardiac function and survival were evaluated in transgenic mice with cardiac myocyte specific expression of constitutively active PI3K isoform, p110α (caPI3K Tg). caPI3K Tg and wild type (WT) mice were subjected to cecal ligation/puncture (CLP) induced sepsis. Wild type CLP mice showed dramatic cardiac dysfunction at 6 hrs. Septic cardiomyopathy was significantly attenuated in caPI3K CLP mice. The time to 100% mortality was 46 hrs in WT CLP mice. In contrast, 80% of the caPI3K mice survived at 46 hrs after CLP (p<0.01) and 50% survived >30 days (p<0.01). Cardiac caPI3K expression prevented expression of an inflammatory phenotype in CLP sepsis. Organ neutrophil infiltration and lung apoptosis were also effectively inhibited by cardiac PI3k p110α expression. Cardiac high mobility group box–1 (HMGB-1) translocation was also inhibited by caPI3K p110α expression. We conclude that cardiac specific activation of PI3k/Akt dependent signaling can significantly modify the morbidity and mortality associated with sepsis. Our data also indicate that myocardial function/dysfunction plays a prominent role in the pathogenesis of sepsis and that maintenance of cardiac function during sepsis is essential. Finally, these data suggest that modulation of the PI3K/p110α signaling pathway may be beneficial in the prevention and/or management of septic cardiomyopathy and septic shock.

Transcription factor Phox2 upregulates expression of norepinephrine transporter and dopamine β-hydroxylase in adult rat brains

Degeneration of the noradrenergic locus coeruleus (LC) in aging and neurodegenerative diseases is well documented. Slowing or reversing this effect may have therapeutic implications. Phox2a and Phox2b are homeodomain transcriptional factors that function as determinants of the noradrenergic phenotype during embryogenesis. In the present study, recombinant lentiviral eGFP-Phox2a and -Phox2b (vPhox2a and vPhox2b) were constructed to study the effects of Phox2a/2b over-expression on dopamine β-hydroxylase (DBH) and norepinephrine transporter (NET) levels in central noradrenergic neurons. Microinjection of vPhox2 into the LC of adult rats significantly increased Phox2 mRNA levels in the LC region. Over-expression of either Phox2a or Phox2b in the LC was paralleled by significant increases in mRNA and protein levels of DBH and NET in the LC. Similar increases in DBH and NET protein levels were observed in the hippocampus following vPhox2 microinjection. In the frontal cortex, only NET protein levels were significantly increased by vPhox2 microinjection. Over-expression of Phox2 genes resulted in a significant increase in BrdU-positive cells in the hippocampal dentate gyrus. The present study demonstrates an upregulatory effect of Phox2a and Phox2b on the expression of DBH and NET in noradrenergic neurons of rat brains, an effect not previously shown in adult animals. Phox2 genes may play an important role in maintaining the function of the noradrenergic neurons after birth, and regulation of Phox2 gene expression may have therapeutic utility in aging or disorders involving degeneration of noradrenergic neurons.

TLR2 ligand induces protection against cerebral ischemia/reperfusion injury via activation of phosphoinositide 3-kinase/Akt signaling

This study examined the effect of TLR2 activation by its specific ligand, Pam3CSK4, on cerebral ischemia/reperfusion (I/R) injury. Mice (n = 8/group) were treated with Pam3CSK4 1 h before cerebral ischemia (60 min), followed by reperfusion (24 h). Pam3CSK4 was also given to the mice (n = 8) 30 min after ischemia. Infarct size was determined by triphenyltetrazolium chloride staining. The morphology of neurons in brain sections was examined by Nissl staining. Pam3CSK4 administration significantly reduced infarct size by 55.9% (p < 0.01) compared with untreated I/R mice. Therapeutic treatment with Pam3CSK4 also significantly reduced infarct size by 55.8%. Morphologic examination showed that there was less neuronal damage in the hippocampus of Pam3CSK4-treated mice compared with untreated cerebral I/R mice. Pam3CSK4 treatment increased the levels of Hsp27, Hsp70, and Bcl2, and decreased Bax levels and NF-κB-binding activity in the brain tissues. Administration of Pam3CSK4 significantly increased the levels of phospho-Akt/Akt and phospho-GSK-3β/GSK-3β compared with untreated I/R mice. More significantly, either TLR2 deficiency or PI3K inhibition with LY29004 abolished the protection by Pam3CSK4. These data demonstrate that activation of TLR2 by its ligand prevents focal cerebral ischemic damage through a TLR2/PI3K/Akt-dependent mechanism. Of greater significance, these data indicate that therapy with a TLR2-specific agonist during cerebral ischemia is effective in reducing injury.

Overexpression of vascular endothelial growth factor 165 (VEGF165) protects cardiomyocytes against doxorubicin-induced apoptosis

Doxorubicin (Dox) has been employed in cancer chemotherapy for a few decades. However its clinical application became restricted because of dose-dependent cardiomyopathy. Recent studies suggest that Dox-induced cardiomyocyte apoptosis is a primary cause of cardiac damage. Vascular endothelial growth factor (VEGF) is a major factor for endothelial cell survival and angiogenesis. We have previously shown that VEGF165 significantly attenuates oxidative stress-induced cardiomyocytes apoptosis. We hypothesized that VEGF165 will protect the cardiomyocytes from Dox-induced apoptosis. to evaluate our hypothesis, we transfected cardiomyocytes H9c2 with adenovirus expressing VEGF165 24 hours before the cells were challenged with Dox at a concentration of 2 µm. Cardiomyocyte apoptosis was evaluated by Annexin V-FITC staining and by Western blot detection of cleaved caspase-3. The hypothesis was confirmed, and the protective mechanisms involve the inhibition of death receptor-mediated apoptosis and up-regulation of the prosurvival Akt/Nf-κb/bcl-2 signaling pathway.

Glucan phosphate attenuates myocardial HMGB1 translocation in severe sepsis through inhibiting NF-κB activation

Myocardial dysfunction is a major consequence of septic shock and contributes to the high mortality of sepsis. High-mobility group box 1 (HMGB1) serves as a late mediator of lethality in sepsis. We have reported that glucan phosphate (GP) attenuates cardiac dysfunction and increases survival in cecal ligation and puncture (CLP)-induced septic mice. In the present study, we examined the effect of GP on HMGB1 translocation from the nucleus to the cytoplasm in the myocardium of septic mice. GP was administered to mice 1 h before induction of CLP. Sham-operated mice served as control. The levels of HMGB1, Toll-like receptor 4 (TLR4), and NF-κB binding activity were examined. In an in vitro study, H9C2 cardiomyoblasts were treated with lipopolysaccharide (LPS) in the presence or absence of GP. H9C2 cells were also transfected with Ad5-IκBα mutant, a super repressor of NF-κB activity, before LPS stimulation. CLP significantly increased the levels of HMGB1, TLR4, and NF-κB binding activity in the myocardium. In contrast, GP administration attenuated CLP-induced HMGB1 translocation from the nucleus to the cytoplasm and reduced CLP-induced increases in TLR4 and NF-κB activity in the myocardium. In vitro studies showed that GP prevented LPS-induced HMGB1 translocation and NF-κB binding activity. Blocking NF-κB binding activity by Ad5-IκBα attenuated LPS-induced HMGB1 translocation. GP administration also reduced the LPS-stimulated interaction of HMGB1 with TLR4. These data suggest that attenuation of HMGB1 translocation by GP is mediated through inhibition of NF-κB activation in CLP-induced sepsis and that activation of NF-κB is required for HMGB1 translocation.

TLR2 ligands induce cardioprotection against ischaemia/reperfusion injury through a PI3K/Akt-dependent mechanism

AIMS

Toll-like receptor (TLR)-mediated signalling pathways have been implicated in myocardial ischaemia/reperfusion (I/R) injury. Activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway protects the myocardium from ischaemic injury. We hypothesized that the modulation of TLR2 would induce cardioprotection against I/R injury via activation of the PI3K/Akt signalling.

METHODS AND RESULTS

Mice were treated with TLR2 ligands, peptidoglycan (PGN) or Pam3CSK4, respectively, 1 h before the hearts were subjected to ischaemia (1 h), followed by reperfusion (4 h). Infarct size was determined by triphenyltetrazolium chloride staining. Cardiac function and haemodynamic performance were evaluated. Infarct size was significantly reduced in PGN- or Pam3CSK4-treated mice compared with untreated I/R mice. Administration of TLR2 ligands improved cardiac function following I/R. PGN treatment increased the levels of phospho-Akt and phospho-GSK-3beta (glycogen synthase kinase-3beta), compared with untreated I/R hearts. PGN stimulation increased TLR2 tyrosine phosphorylation and association of the p85 subunit of PI3K with TLR2. To investigate the role of PI3K/Akt signalling in PGN-induced cardioprotection, we administered the PI3K inhibitor, Wortmannin, to the mice 15 min before PGN treatment. We also administered PGN to kinase-deficient Akt (kdAkt) transgenic mice 1 h before myocardial I/R. Both PI3K inhibition and kdAkt mice abolished the cardioprotection induced by PGN. To examine the role of TLR2 in PGN-induced cardioprotection, we administrated PGN to TLR2 knockout mice 1 h before the hearts were subjected to I/R. PGN-induced cardioprotection was lost in TLR2-deficient mice.

CONCLUSION

These results demonstrate that TLR2 ligands induced cardioprotection, which is mediated through a TLR2/PI3K/Akt-dependent mechanism.

TLR2 ligands attenuate cardiac dysfunction in polymicrobial sepsis via a phosphoinositide 3-kinase-dependent mechanism

Myocardial dysfunction is a major consequence of septic shock and contributes to the high mortality of sepsis. In the present study, we examined the effect of Toll-like receptor 2 (TLR2) ligands, peptidoglycan (PGN), and Pam3CSK4 (Pam3) on cardiac function in cecal ligation and puncture (CLP)-induced sepsis in mice. We also investigated whether the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway is involved in the effect of TLR2 ligands on cardiac function in CLP mice. PGN was administered to C57B6/L mice 1 h before the induction of CLP. Sham surgically operated mice served as a control. Cardiac function indexes (rate of change in left ventricular pressure, stroke work, cardiac output, and ejection fraction) were examined by a microconductance pressure catheter. Cardiac function was significantly decreased 6 h after CLP-induced sepsis compared with sham-operated control. In contrast, PGN administration attenuated CLP-induced cardiac dysfunction. Importantly, the therapeutic treatment with Pam3 1 h after CLP also significantly attenuated cardiac dysfunction in CLP mice. However, the beneficial effect of TLR2 ligands on cardiac dysfunction in CLP-mice was abolished in TLR2-deficient mice. PGN administration significantly increased the levels of phospho-Akt and phospho-GSK-3beta in the myocardium compared with the levels in untreated CLP mice. PI3K inhibition abolished the PGN-induced attenuation of cardiac dysfunction in CLP mice. In conclusion, these data demonstrate that the administration of TLR2 ligands, PGN, or Pam3 attenuates cardiac dysfunction in septic mice via a TLR2/PI3K-dependent mechanism. More significantly, Pam3 therapeutic treatment will have a potential clinical relevance.

Cellular cardiomyoplasty: what have we learned?

Restoring blood flow, improving perfusion, reducing clinical symptoms, and augmenting ventricular function are the goals after acute myocardial infarction. Other than cardiac transplantation, no standard clinical procedure is available to restore damaged myocardium. Since we first reported cellular cardiomyoplasty in 1989, successful outcomes have been confirmed by experimental and clinical studies, but definitive long-term efficacy requires large-scale placebo-controlled double-blind randomized trials. On meta-analysis, stem cell-treated groups had significantly improved left ventricular ejection fraction, reduced infarct scar size, and decreased left ventricular end-systolic volume. Fewer myocardial infarctions, deaths, readmissions for heart failure, and repeat revascularizations were additional benefits. Encouraging clinical findings have been reported using satellite or bone marrow stem cells, but understanding of the benefit mechanisms demands additional studies. Adult mammalian ventricular myocardium lacks adequate regeneration capability, and cellular cardiomyoplasty offers a new way to overcome this; the poor retention and engraftment rate and high apoptotic rate of the implanted stem cells limit outcomes. The ideal type and number of cells, optimal timing of cell therapy, and ideal cell delivery method depend on determining the beneficial mechanisms. Cellular cardiomyoplasty has progressed rapidly in the last decade. A critical review may help us to better plan the future direction.

Differential roles of TLR2 and TLR4 in acute focal cerebral ischemia/reperfusion injury in mice

Recent studies have shown that Toll-like receptors (TLRs) are involved in cerebral ischemia/reperfusion (I/R) injury. This study was to investigate the role of TLR2 and TLR4 in acute focal cerebral I/R injury. Cerebral infarct size, neurological function and mortality were evaluated. NFsmall ka, CyrillicB binding activity, phosphorylation of Ismall ka, CyrillicBalpha, Akt and ERK1/2 were examined in ischemic cerebral tissue by EMSA and Western blots. Compared to wild type (WT) mice, in TLR4 knockout (TLR4KO) mice, brain infarct size was decreased (2.6+/-1.18% vs 11.6+/-1.97% of whole cerebral volume, p<0.05) and neurological function was maintained (7.3+/-0.79 vs 4.7+/-0.68, p<0.05). However, compared to TLR4KO mice, TLR2 knockout (TLR2KO) mice showed higher mortality (38.2% vs 13.0%, p<0.05), decreased neurological function (2.9+/-0.53 vs 7.3+/-0.79, p<0.05) and increased brain infarct size (19.1+/-1.33% vs 2.6+/-1.18%, p<0.05). NFsmall ka, CyrillicB activation and Ismall ka, CyrillicBalpha phosphorylation were attenuated in TLR4KO mice (1.09+/-0.02 and 1.2+/-0.04) compared to TLR2KO mice (1.31+/-0.02 and 2.2+/-0.32) after cerebral ischemia. Compared to TLR4KO mice, in TLR2KO mice, the phosphorylation of Akt (0.2+/-0.03 vs 0.9+/-0.16, p<0.05) and ERK1/2 (0.8+/-0.06 vs 1.3+/-0.17) evoked by cerebral I/R was attenuated. The present study demonstrates that TLR2 and TLR4 play differential roles in acute cerebral I/R injury. Specifically, TLR4 contributes to cerebral I/R injury, while TLR2 appears to be neuroprotective by enhancing the activation of protective signaling in response to cerebral I/R.

Preconditioning with a TLR2 specific ligand increases resistance to cerebral ischemia/reperfusion injury

The brain's resistance to ischemic injury can be transiently augmented by prior exposure to a sub-lethal stress stimulus, i.e. preconditioning. It has been reported that Toll-like receptors (TLRs) are involved in the preconditioning-induced protective effect against ischemic brain injury. In this study, we investigated the effect of preconditioning with a TLR2 specific ligand, Pam3CSK4, on focal cerebral ischemia/reperfusion (I/R) injury in mice. Pam3CSK4 was administered systemically 24 h before the mice were subjected to focal cerebral ischemia (1 h) followed by reperfusion. Cerebral infarct size was determined, blood brain barrier (BBB) permeability was evaluated, and expression of tight-junction proteins were examined after focal cerebral I/R. Results showed that pre-treatment with Pam3CSK significantly reduced brain infarct size (1.9+/-0.5% vs 9.4+/-2.2%) compared with the untreated I/R group. Pam3CSK4 pre-treatment also significantly reduced acute mortality (4.3% vs 24.2%), preserved neurological function (8.22+/-0.64 vs 3.91+/-0.57), and attenuated brain edema (84.61+/-0.08% vs 85.29+/-0.09%) after cerebral I/R. In addition, Pam3CSK4 pre-treatment preserved BBB function as evidenced by decreased leakage of serum albumin (0.528+/-0.026 vs 0.771+/-0.059) and Evans Blue (9.23+/-0.72 microg/mg vs 12.56+/-0.65 microg/mg) into brain tissue. Pam3CSK4 pre-treatment also attenuated the loss of the tight junction protein occludin in response to brain I/R injury. These results suggest that TLR2 is a new target of ischemic preconditioning in the brain and preconditioning with a TLR2 specific ligand will protect the brain from I/R injury.

Lipopolysaccharide-induced myocardial protection against ischaemia/reperfusion injury is mediated through a PI3K/Akt-dependent mechanism

AIMS

The ability of lipopolysaccharide (LPS) pre-treatment to induce cardioprotection following ischaemia/reperfusion (I/R) has been well documented; however, the mechanisms have not been fully elucidated. LPS is a Toll-like receptor 4 (TLR4) ligand. Recent evidence indicates that there is cross-talk between the TLR and phosphoinositide 3-kinase/Akt (PI3K/Akt) signalling pathways. We hypothesized that activation of PI3K/Akt signalling plays a critical role in LPS-induced cardioprotection.

METHODS AND RESULTS

To evaluate this hypothesis, we pre-treated mice with LPS 24 h before the hearts were subjected to ischaemia (45 min) and reperfusion (4 h). We examined activation of the PI3K/Akt/GSK-3beta signalling pathway. The effect of PI3K/Akt inhibition on LPS-induced cardioprotection was also evaluated. LPS pre-treatment significantly reduced infarct size (71.25%) compared with the untreated group (9.3+/-1.58 vs. 32.3+/-2.92%, P<0.01). Cardiac myocyte apoptosis and caspase-3 activity in LPS-pre-treated mice were significantly reduced following I/R. LPS pre-treatment significantly increased the levels of phospho-Akt, phospho-GSK-3beta, and heat shock protein 27 in the myocardium. Pharmacological inhibition of PI3K by LY294002 or genetic modulation employing kinase-defective Akt transgenic mice abolished the cardioprotection induced by LPS.

CONCLUSION

These results indicate that LPS-induced cardioprotection in I/R injury is mediated through a PI3K/Akt-dependent mechanism.

Activation of Toll-like receptor 4 signaling contributes to hippocampal neuronal death following global cerebral ischemia/reperfusion

Toll-like receptors (TLRs) play a critical role in the induction of innate immune responses which have been implicated in neuronal death induced by global cerebral ischemia/reperfusion (GCI/R). The present study investigated the role and mechanisms-of-action of TLR4 signaling in ischemia-induced hippocampal neuronal death. Neuronal damage, activation of the TLR4 signaling pathway, expression of pro-inflammatory cytokines and activation of the PI3K/Akt signaling pathway in the hippocampal formation (HF) were assessed in wild type (WT) mice and TLR4 knockout (TLR4(-/-)) mice after GCI/R. GCI/R increased expression of TLR4 protein in the hippocampal formation (HF) and other brain structures in WT mice. Phosphorylation of the inhibitor of kappa B (p-IkappaB) as well as activation of nuclear factor kappa B (NFkappaB) increased in the HF of WT mice. In contrast, there were lower levels of p-IkappaB and NFkappaB binding activity in TLR4(-/-) mice subjected to GCI/R. Pro-inflammatory cytokine expression was also decreased, while phosphorylation of Akt and GSK3beta were increased in the HF of TLR4(-/-) mice after GCI/R. These changes correlated with decreased neuronal death/apoptosis in TLR4(-/-) mice following GCI/R. These data suggest that activation of TLR4 signaling contributes to ischemia-induced hippocampal neuronal death. In addition, these data suggest that modulation of TLR4 signaling may attenuate ischemic injury in hippocampal neurons.

Protection against myocardial ischemia/reperfusion injury in TLR4-deficient mice is mediated through a phosphoinositide 3-kinase-dependent mechanism

TLRs play a critical role in the induction of innate and adaptive immunity. However, TLRs have also been reported to mediate the pathophysiology of organ damage following ischemia/reperfusion (I/R) injury. We have reported that TLR4(-/-) mice show decreased myocardial injury following I/R; however, the protective mechanisms have not been elucidated. We examined the role of the PI3K/Akt signaling pathway in TLR4(-/-) cardioprotection following I/R injury. TLR4(-/-) and age-matched wild-type (WT) mice were subjected to myocardial ischemia for 45 min, followed by reperfusion for 4 h. Pharmacologic inhibitors of PI3K (wortmannin or LY294002) were administered 1 h before myocardial I/R. Myocardial infarct size/area at risk was reduced by 51.2% in TLR4(-/-) vs WT mice. Cardiac myocyte apoptosis was also increased in WT vs TLR4(-/-) mice following I/R. Pharmacologic blockade of PI3K abrogated myocardial protection in TLR4(-/-) mice following I/R. Specifically, heart infarct size/area at risk was increased by 98% in wortmannin and 101% in LY294002-treated TLR4(-/-) mice, when compared with control TLR4(-/-) mice. These data indicate that protection against myocardial I/R injury in TLR4(-/-) mice is mediated through a PI3K/Akt-dependent mechanism. The mechanisms by which PI3K/Akt are increased in the TLR4(-/-) myocardium may involve increased phosphorylation/inactivation of myocardial phosphatase and tensin homolog deleted on chromosome 10 as well as increased phosphorylation/inactivation of myocardial glycogen synthase kinase-3beta. These data implicate innate immune signaling pathways in the pathology of acute myocardial I/R injury. These data also suggest that modulation of TLR4/PI3K/Akt-dependent signaling pathways may be a viable strategy for reducing myocardial I/R injury.

Microvasculature of the urinary bladder of the dog: a study using vascular corrosion casting

The urinary bladder is an unusual organ in that its normal function includes filling and emptying with alternating changes in internal pressure. Although fluctuations in blood flow to the bladder wall are known to accompany these changes, detailed descriptions of the bladder microvasculature are sparse. The present study uses vascular corrosion casting and scanning electron microscopy to describe the three-dimensional anatomy of the microvasculature of the urinary bladder of the dog. Specialized features of that microvasculature, including collateral circulation, vessel folding, vessel orientation, the presence of valves and sphincters, and mucosal capillary density, that may enhance and control blood flow during normal bladder function, are described and discussed.

Glucan phosphate attenuates cardiac dysfunction and inhibits cardiac MIF expression and apoptosis in septic mice

Myocardial dysfunction is a major consequence of septic shock and contributes to the high mortality of sepsis. We have previously reported that glucan phosphate (GP) significantly increased survival in a murine model of cecal ligation and puncture (CLP)-induced sepsis. In the present study, we examined the effect of GP on cardiac dysfunction in CLP-induced septic mice. GP was administered to ICR/HSD mice 1 h before induction of CLP. Sham surgically operated mice served as control. Cardiac function was significantly decreased 6 h after CLP-induced sepsis compared with sham control. In contrast, GP administration prevented CLP-induced cardiac dysfunction. Macrophage migration inhibitory factor (MIF) has been implicated as a major factor in cardiomyocyte apoptosis and cardiac dysfunction during septic shock. CLP increased myocardial MIF expression by 88.3% ( P < 0.05) and cardiomyocyte apoptosis by 7.8-fold ( P < 0.05) compared with sham control. GP administration, however, prevented CLP-increased MIF expression and decreased cardiomyocyte apoptosis by 51.2% ( P < 0.05) compared with untreated CLP mice. GP also prevented sepsis-caused decreases in phospho-Akt, phospho-GSK-3β, and Bcl-2 levels in the myocardium of septic mice. These data suggest that GP treatment attenuates cardiovascular dysfunction in fulminating sepsis. GP administration also activates the phosphoinositide 3-kinase/Akt pathway, decreases myocardial MIF expression, and reduces cardiomyocyte apoptosis.

Attenuation of cardiac hypertrophy by inhibiting both mTOR and NFkappaB activation in vivo

A role for the PI3K/Akt/mTOR pathway in cardiac hypertrophy has been well documented. We reported that NFkappaB activation is needed for cardiac hypertrophy in vivo. To investigate whether both NFkappaB activation and PI3K/Akt/mTOR signaling participate in the development of cardiac hypertrophy, two models of cardiac hypertrophy, namely, induction in caAkt-transgenic mice and by aortic banding in mice, were employed. Rapamycin (2 mg/kg/daily), an inhibitor of the mammalian target of rapamycin, and the antioxidant pyrrolidine dithiocarbamate (PDTC; 120 mg/kg/daily), which can inhibit NFkappaB activation, were administered to caAkt mice at 8 weeks of age for 2 weeks. Both rapamycin and PDTC were also administered to the mice immediately after aortic banding for 2 weeks. Administration of either rapamycin or PDTC separately or together to caAkt mice reduced the ratio of heart weight/body weight by 21.54, 32.68, and 42.07% compared with untreated caAkt mice. PDTC administration significantly reduced cardiac NFkappaB activation by 46.67% and rapamycin significantly decreased the levels of p70S6K by 34.20% compared with untreated caAkt mice. Similar results were observed in aortic-banding-induced cardiac hypertrophy in mice. Our results suggest that both NFkappaB activation and the PI3K/Akt signaling pathway participate in the development of cardiac hypertrophy in vivo.

Blocking the MyD88-dependent pathway protects the myocardium from ischemia/reperfusion injury in rat hearts

We examined whether blocking the MyD88 mediated pathway could protect myocardium from ischemia/reperfusion (I/R) injury by transfecting Ad5-dnMyD88 into the myocardium of rats (n=8) 3 days before the hearts were subjected to ischemia (45min) and reperfusion (4h). Ad5-GFP served as control (n=8). One group of rats was (n=8) subjected to I/R without transfection. Transfection of Ad5-dnMyD88 significantly reduced infarct size by 53.6% compared with the I/R group (15.1+/-3.02 vs 32.5+/-2.59) while transfection of Ad5-GFP did not affect I/R induced myocardial injury (35.4+/-2.59 vs 32.5+/-2.59). Transfection of Ad5-dnMyD88 significantly inhibited I/R-enhanced NFkappaB activity by 50% and increased the levels of phospho-Akt by 35.6% and BCL-2 by 81%, respectively. Cardiac myocyte apoptosis after I/R was significantly reduced by 59% in the Ad5-dnMyD88 group. The results demonstrate that both inhibition of the NFkappaB activation pathway and activation of the Akt signaling pathway may be responsible for the protective effect of transfection of dominant negative MyD88.

Blockade of MyD88 attenuates cardiac hypertrophy and decreases cardiac myocyte apoptosis in pressure overload-induced cardiac hypertrophy in vivo

In this study, we evaluated whether blocking myeloid differentiation factor-88 (MyD88) could decrease cardiac myocyte apoptosis following pressure overload. Adenovirus expressing dominant negative MyD88 (Ad5-dnMyD88) or Ad5-green fluorescent protein (GFP) (Ad5-GFP) was transfected into rat hearts (n = 8/group) immediately followed by aortic banding for 3 wk. One group of rats (n = 8) was subjected to aortic banding for 3 wk without transfection. Sham surgical operation (n = 8) served as control. The ratios of heart weight to body weight (HW/BW) and heart weight to tibia length (HW/TL) were calculated. Cardiomyocyte size was examined by FITC-labeled wheat germ agglutinin staining of membranes. Cardiac myocyte apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, and myocardial interstitial fibrosis was examined by Masson's Trichrome staining. Aortic banding significantly increased the HW/BW by 41.0% (0.44 +/- 0.013 vs. 0.31 +/- 0.008), HW/TL by 47.2% (42.7 +/- 1.30 vs. 29.0 +/- 0.69), cardiac myocyte size by 49.6%, and cardiac myocyte apoptosis by 11.5%, and myocardial fibrosis and decreased cardiac function compared with sham controls. Transfection of Ad5-dnMyD88 significantly reduced the HW/BW by 18.2% (0.36 +/- 0.006 vs. 0.44 +/- 0.013) and HW/TL by 22.3% (33.2 +/- 0.95 vs. 42.7 +/- 1.30) and decreased cardiomyocyte size by 56.8%, cardiac myocyte apoptosis by 76.2%, as well as fibrosis, and improved cardiac function compared with aortic-banded group. Our results suggest that MyD88 is an important component in the Toll-like receptor-4-mediated nuclear factor-kappaB activation pathway that contributes to the development of cardiac hypertrophy. Blockade of MyD88 significantly reduced cardiac hypertrophy, cardiac myocyte apoptosis, and improved cardiac function in vivo.

Reduced cardiac hypertrophy in toll-like receptor 4-deficient mice following pressure overload

OBJECTIVE

We have previously demonstrated that nuclear factor kappa B (NFkappaB) activation is needed for the development of cardiac hypertrophy in vivo. NFkappaB is a downstream transcription factor in the Toll-like receptor (TLR)-mediated signaling pathway; therefore, we investigated a role of TLR4 in cardiac hypertrophy in vivo.

METHODS

TLR4-deficient mice (C.C3H-Tlr4(lps-d), n = 6), wild-type (WT) genetic background mice (BALB/c, n = 6), TLR4-deleted strain (C57BL/10ScCr, n = 8), and WT controls (C57BL/10ScSn, n = 8) were subjected to aortic banding for 2 weeks. Age-matched surgically operated mice served as controls. In a separate experiment, rapamycin (2 mg/kg, daily) was administered to TLR4-deficient mice and WT mice immediately following aortic banding. The ratio of heart weight/body weight (HW/BW) was calculated, and cardiac myocyte size was examined by FITC-labeled wheat germ agglutinin staining of membranes. NFkappaB binding activity and the levels of phospho-p70S6K in the myocardium were also examined.

RESULTS

Aortic banding significantly increased the ratio of HW/BW by 33.9% (0.601 +/- 0.026 vs. 0.449 +/- 0.004) and cell size by 68.4% in WT mice and by 10.00% (0.543 +/- 0.011 vs. 0.495 +/- 0.005) and by 11.8% in TLR4-deficient mice, respectively, compared with respective sham controls. NFkappaB binding activity and phospho-p70S6K levels were increased by 182.6% and 115.2% in aortic-banded WT mice and by 78.0% and 162.0% in aortic-banded TLR4-deficient mice compared with respective sham controls. In rapamycin-treated aortic-banded mice, the ratio of HW/BW was increased by 18.0% in WT mice and by 3.5% in TLR4-deficient mice compared with respective sham controls.

CONCLUSION

Our results demonstrate that TLR4 is a novel receptor contributing to the development of cardiac hypertrophy in vivo and that both the TLR4-mediated pathway and PI3K/Akt/mTOR signaling are involved in the development of cardiac hypertrophy in vivo.

Angiopoietin-1 inhibits doxorubicin-induced human umbilical vein endothelial cell death by modulating fas expression and via the PI3K/Akt pathway

Angiopoietin-1 (Ang-1) is essential for the maturation of blood vessels during vasculogenesis. Besides angiogenesis, recent publications indicate that Ang-1 is also a potent survival factor for endothelial cells; however, the mechanisms by which pathways remain elusive. Doxorubicin (DOX) is a powerful anticancer drug, but its use is severely restricted by its cardiotoxicity. The authors report here that Ang-1 inhibits DOX-induced cell death in human umbilical vein endothelial cells (HUVECs). Interestingly, the DOX-induced up-regulation in Fas (CD95/APO-1) and Fas ligand expression could be blocked by Ang-1, indicating a pivotal role of Ang-1 in DOX-induced Fas and Fas ligand expression. In addition, the prevention of cell death in this model system seems to be dependent on the activation of phosphatidylinositol 3-kinase (PI3K)/Akt, as Ang-1 fails to inhibit DOX-induced cell death while PI3K/Akt pathway was blocked by the PI3K inhibitor LY294002. Moreover, Ang-1 inhibits DOX-induced up-regulation of p53 through PI3K/Akt. Therefore, Ang-1 is a potent inhibitor for DOX-induced cell death through Fas and PI3K/Akt-mediated pathways.

NF-κB activation is required for the development of cardiac hypertrophy in vivo

In the present study, we examined whether NF-κB activation is required for cardiac hypertrophy in vivo. Cardiac hypertrophy in rats was induced by aortic banding for 1, 3, and 5 days and 1–6 wk, and age-matched sham-operated rats served as controls. In a separate group of rats, an IκB-α dominant negative mutant (IκB-αM), a superrepressor of NF-κB activation, or pyrrolidinedithiocarbamate (PDTC), an antioxidant that can inhibit NF-κB activation, was administered to aortic-banded rats for 3 wk. The heart weight-to-body weight ratio was significantly increased at 5 days after aortic banding, peaked at 4 wk, and remained elevated at 6 wk compared with age-matched sham controls. Atrial natriuretic peptide and brain natriuretic peptide mRNA expressions were significantly increased after 1 wk of aortic banding, reached a maximum between 2 and 3 wk, and remained increased at 6 wk compared with age-matched sham controls. NF-κB activity was significantly increased at 1 day, reached a peak at 3 wk, and remained elevated at 6 wk, and IKK-β activity was significantly increased at 1 day, peaked at 5 days, and then decreased but remained elevated at 6 wk after aortic banding compared with age-matched sham controls. Inhibiting NF-κB activation in vivo by cardiac transfection of IκB-αM or by PDTC treatment significantly attenuated the development of cardiac hypertrophy in vivo with a concomitant decrease in NF-κB activity. Our results suggest that NF-κB activation is required for the development of cardiac hypertrophy in vivo and that NF-κB could be an important target for inhibiting the development of cardiac hypertrophy in vivo.

Modulating Toll-like receptor mediated signaling by (1-->3)-beta-D-glucan rapidly induces cardioprotection

OBJECTIVE

Immune and inflammatory signaling pathways, initiated by the innate response, are involved in myocardial ischemia/reperfusion (I/R) injury. Toll-like receptor (TLR) mediated MyD88-dependent NFkappaB pathways play a role in the induction of innate immunity. We have reported that glucan phosphate (GP) improved survival in experimental sepsis, which correlated with decreased tissue NFkappaB activation. In the present study, we report that GP rapidly induced cardioprotection against I/R injury in vivo.

METHODS

Sprague-Dawley rats were pretreated with GP (40 mg/kg, i.p) 1 h before 45 min of ligation of the left anterior descending coronary followed by reperfusion for 4 and 24 h. Infarction size was examined by triphenyltetrazolium chloride (TTC) staining. NFkappaB activation was analyzed by electrophoretic mobility shift assay (EMSA). IkappaB kinase-beta (IKKbeta), IL-1 receptor-associated kinase (IRAK) and Phosphoinositide 3-kinase (PI3K) activities were determined by kinase assay with appropriate substrates. Association of TLR4 with MyD88 or with PI3K p85 was assessed by immunoprecipitation with anti-TLR4 followed by immunoblotting with anti-MyD88 or anti-p85.

RESULTS

GP treatment reduced infarct size by 47% in rat hearts subjected to reperfusion for 4 h and by 50% following reperfusion for 24 h. The same protective effect was observed when GP was administrated 5 min after initiation of ischemia. The mechanisms of GP induced cardioprotection involve decreased association of TLR4 with MyD88, inhibition of I/R induced IRAK and IKKbeta activity and decreased NFkappaB activity. In addition, GP increased TLR4 phosphotyrosine, resulting in increasing PI3K/Akt activity in the myocardium, which correlated with decreased cardiac myocyte apoptosis following I/R.

CONCLUSION

The results suggest that activation of the TLR mediated MyD88-dependent NFkappaB signaling pathway may play an important role in myocardial I/R injury, while stimulation of the PI3K/Akt signaling could serve a protective role. The data indicates that GP treatment shifts the TLR mediated activation signal in I/R from a predominantly NFkappaB pathway to a predominant PI3K/Akt signaling pathway.

Clinical cellular cardiomyoplasty: technical considerations

Three patients, all with a history of coronary heart disease, underwent coronary artery bypass grafting and implantation of autologous satellite cells. Satellite cells were isolated from muscle biopsies of the right vastus lateralis muscle after enzymatic treatment. While the heart was still under hypothermic cardioplegia, 4 mL of cell suspension divided into approximately 40 doses was injected into the ventricular wall of the ischemic area. Less than 5 minutes were required to complete the cell implantation. All patients survived the procedure, without obvious arrhythmia, had an uneventful recovery, and were discharged from the hospital. At 3 to 4 months follow-up examination, increased left ventricular ejection fraction, decreased left ventricular diastolic diameter, as well as improved ventricular wall thickness and perfusion at the satellite cell implantation sites were observed. Our experience indicated the safety and early benefit of cellular cardiomyoplasty using autologous satellite cells.

Cellular cardiomyoplasty for a patient with heart failure

BACKGROUND

A 73-year-old man with a history of myocardial infarction and hypertension for 5 years suffered heart failure (NYHA III-IV).

METHODS

2D echo indicated hypokinesia at septal, left ventricular anterior wall and apical regions. Coronary angiograms demonstrated 60% stenosis in distal left main and 99% stenosis in proximal and distal left anterior descending coronary arteries (LAD). Both proximal artery and middle left circumflex coronary artery (LC) had 90% stenosis, and diffuse stenosis of right coronary artery (RC) was found. Myocardial perfusion imaging using 99mTc-MIBI indicated defective perfusion of left ventricular apex, anterior wall and septal region and severe reduced perfusion of posterior inferior wall. Myocardial metabolic activities (18F-deoxyglucose) also showed comparable reductions. After exposing the heart, LAD, LC, and RC were all completely occluded and bypass procedure could not be completed. Autologous satellite cells were implanted without any complication and the patient had an uneventful recovery.

RESULTS

During the first 2 months, he remained in heart failure, and by the third month, he gradually improved and reached NYHA II. At fifth month after the procedure, significant increased ejection fraction (37.1-48.6%) and wall movement with modest reduction of left ventricular systolic diameter (48-45 mm) were observed. Imaging with 18F-deoxyglucose showed dramatic improvement in myocardial metabolic activity with similar improvement in myocardial perfusion (99mTc-MIBI).

CONCLUSION

This is the first successful case of cellular cardiomyoplasty without any conjunctional procedure for patient with severe coronary heart disease and heart failure.

Cellular cardiomyoplasty: a preliminary clinical report

BACKGROUND

Cellular cardiomyoplasty is the method of transplanting myogenic cells into injured myocardium to restore the lost heart muscle cells and to improve ventricular function.

METHOD

Three patients, all with a history of coronary heart disease, underwent coronary artery bypass grafting and implantation of autologous satellite cells. A muscle biopsy of 2-4 g from the right vastus lateralis muscle was obtained for satellite cell (myogenic stem cell from skeletal muscle) isolation and proliferation before implanted into the donor's heart. The cells were suspended in serum-free medium and injected into 30-40 sites at and around the ischemic areas just before reversing the hypothermic cardioplegia to eliminate arrhythmia and to improve retention. After recovery, each patient was maintained at the intensive care unit for 3-4 days with ECG monitoring before transferring to the patient floor.

RESULTS

All patients survived the procedure with an uneventful recovery and were discharged from the hospital. At 3-4 months follow-up examination, increased left ventricular ejection fraction of 11% (35-46%), 5.4% (40-45.4%) and 1% (40-41%) and decreased left ventricular diastolic diameter of 4, 2 and 9 mm were observed for the patients, respectively. Arrhythmia was not detected during the follow-up evaluation by ECG. Improved perfusion (99mTC-MIBI) and increased metabolic activity (18F-deoxyglucose) were found at the sites of satellite cell implantation. Significant increase of wall thickness and movement at the areas of cell injection was also observed using 2D-echo.

CONCLUSION

Cellular cardiomyoplasty using autologous satellite cells is a safe procedure with encouraging beneficial outcomes in patients.

Early activation of IKKbeta during in vivo myocardial ischemia

We have demonstrated that in vitro brief ischemia activates nuclear factor (NF)-kappaB in rat myocardium. We report in vivo ischemia-reperfusion (I/R)-induced NF-kappaB activation, IkappaB kinase -beta (IKKbeta) activity, and IkappaBalpha phosphorylation and degradation in rat myocardium. Rat hearts were subjected to occlusion of the coronary artery for up to 45 min or occlusion for 15 min followed by reperfusion for up to 3 h. Cytoplasmic and nuclear proteins were isolated from ischemic and nonischemic areas of each heart. NF-kappaB activation was increased in the ischemic area (680%) after 10 min of ischemia and in the nonischemic area (350%) after 15 min of ischemia and remained elevated during prolonged ischemia and reperfusion. IKKbeta activity was markedly increased in ischemic (1,800%) and nonischemic (860%) areas, and phosphorylated IkappaBalpha levels were significantly elevated in ischemic (180%) and nonischemic (280%) areas at 5 min of ischemia and further increased after reperfusion. IkappaBalpha levels were decreased in the ischemic (45%) and nonischemic (36%) areas after 10 min of ischemia and remained low in the ischemic area during prolonged ischemia and reperfusion. The results suggest that in vivo I/R rapidly induces IKKbeta activity and increases IkappaBalpha phosphorylation and degradation, resulting in NF-kappaB activation in the myocardium.

Adenosine prevents activation of transcription factor NF-kappa B and enhances activator protein-1 binding activity in ischemic rat heart

BACKGROUND

Adenosine prevents myocardial TNF-alpha production induced by ischemia/reperfusion, but the mechanisms are poorly understood. Transcription factors NF-kappa B and AP-1 have been implicated in the regulation of a variety of inducible gene expressions in response to oxidative stress and cellular defense. The effects of adenosine on NF-kappa B and AP-1 activation have not been clearly defined. This study demonstrated differential effects of adenosine on NF-kappa B and AP-1 nuclear binding activity in ischemic myocardium.

METHODS

Isolated working rat hearts were subjected to 0, 1, 2, 3, 4, 5, 7.5, 10, 15, and 30 minutes of ischemia, with 4 to 6 hearts for each time point with and without adenosine (100 mumol/L). NF-kappa B and AP-1 binding activity in the nucleus were analyzed by electrophoretic mobility shift assay (EMSA). I kappa B alpha levels in the cytoplasm were measured by Western blot analysis. TNF-alpha mRNA levels were determined by RT-PCR.

RESULTS

NF-kappa B binding activity in the nucleus significantly increased after 4 minutes of ischemia and remained to 30 minutes. The levels of I kappa B alpha protein in the cytoplasm markedly decreased after 4, 5, 7.5, and 10 minutes of ischemia. TNF-alpha mRNA levels peaked after 10 minutes of ischemia. AP-1 DNA binding activity was induced and persisted during all ischemic periods. Adenosine significantly inhibited NK-kappa B binding activity in the nucleus, markedly prevented the loss of I kappa B alpha proteins from the cytoplasm, and concomitantly down-regulated TNF-alpha mRNA expression, but enhanced AP-1 binding activity in the nucleus of ischemic myocardium.

CONCLUSIONS

Adenosine modulation of NF-kappa B activation may be the cellular molecular mechanism of down-regulation of TNF-alpha mRNA expression. The cardioprotective properties of adenosine may be involved in the differential modulation of NF-kappa B and AP-1 activation during myocardial ischemia.

Lipid hydroperoxides inhibit nitric oxide production in RAW264.7 macrophages

The effects of oxidatively modified low density lipoprotein (oxLDL) on atherogenesis may be partly mediated by alterations in the production of nitric oxide (NO) by vascular cells. Lipid hydroperoxides (LOOH) and lysophosphatidylcholine (lysoPC) are the major primary products of LDL oxidation. The purpose of this study was to characterize the effects of oxLDL, LOOH and lysoPC on NO production and the expression of inducible nitric oxide synthase (iNOS) gene in lipopolysaccharide (LPS) stimulated macrophages. LDL was oxidized using an azo-initiator 2,2'-azobis (2-amidinopropane) HCl (ABAP) and octadecadienoic acid was oxidized by lipoxygenase to generate 13-hydroperoxyl octadecadienoic acid (13-HPODE). Our study showed that oxLDL markedly decreased the production of NO, the levels of iNOS protein and iNOS mRNA in LPS stimulated macrophages. The inhibition potential of oxLDL on NO production and iNOS gene expression depended on the levels of LOOH formed in oxLDL and was not due to oxLDL cytotoxicity. Furthermore, 13-HPODE markedly reduced NO production and iNOS protein levels, whereas lysoPC showed only slight reduction. The effects of 13-HPODE and lysoPC did not require an acetylated LDL carrier. Our results suggest that 13-HPODE is a much more potent inhibitor of NO production and iNOS gene expression than lysoPC in LPS stimulated RAW264.7 macrophages.

Early activation of transcription factor NF-kappaB during ischemia in perfused rat heart

The transcription factor nuclear factor kappaB (NF-kappaB) regulates multiple immediate-early gene expressions involved in immune and inflammatory responses and cellular defenses. Ischemia-reperfusion induces many immediate-early gene expressions, but little is known about the NF-kappaB activation in myocardium during ischemia and reperfusion. This study demonstrated that ischemia alone rapidly induced NF-kappaB activation in the myocardium of isolated working rat hearts. Electrophoretic mobility shift assay showed that NF-kappaB binding activity significantly increased in the nucleus after 5 min of ischemia and remained elevated for up to 30 min. Western blot analysis suggested that the levels of inhibitory IkappaBalpha protein in the cytoplasm became markedly decreased at 4, 5, 7.5, and 10 min of ischemia but were gradually restored following 10 min of ischemia. Reduction of IkappaBalpha protein in the cytoplasm by ischemia resulted in NF-kappaB translocation to the nucleus. Northern blot hybridization showed that IkappaBalpha mRNA levels were not significantly elevated during myocardial ischemia. Pyrrolidine dithiocarbamate, an antioxidant, significantly inhibited the loss of IkappaBalpha protein from the cytoplasm and prevented NF-kappaB binding activity in the nucleus. Reperfusion following short periods of ischemia augmented NF-kappaB binding activity in the nucleus induced by ischemia. The results suggest that early activation of NF-kappaB induced by ischemia in the myocardium could be a signal mechanism for controlling and regulating immediate-early gene expression during ischemia-reperfusion.

Ketoprofen tissue permeation in swine following cathodic iontophoresis

BACKGROUND AND PURPOSE

Pharmacokinetic assessment of drug tissue permeation following iontophoresis is limited. The depth of ketoprofen tissue permeation following cathodic iontophoresis (4 mA, 40 minutes) and the stereoselectivity of drug delivery were examined in this study.

SUBJECTS

Ketoprofen (750 mg) was iontophoresed onto one porcine medial thigh, with passive drug permeation conducted on the other thigh.

METHODS

Skin, subcutaneous fascia, and muscle biopsies from the drug delivery sites were harvested and stored separately, and the "R" and "S" ketoprofen enantiomers were determined. Results. Iontophoretic and passive applications yielded equivalent total ketoprofen concentrations in the skin and fascia. In contrast, multivariate analysis demonstrated that the ketoprofen concentration in the first centimeter of muscle following iontophoresis was greater than the drug concentration in the deeper underlying muscle layers and greater than that delivered to any muscle layer following passive delivery. No transcutaneous stereoselective delivery) of ketoprofen was detected.

CONCLUSION AND DISCUSSION

Compared with passive delivery, iontophoresis enhances nonstereoselective ketoprofen permeation into the fascia-muscle interface. With delivery to deeper tissue sites, however, there is no apparent enhancement over passive application.

Therapeutic modification of nuclear factor kappa B binding activity and tumor necrosis factor-alpha gene expression during acute biliary pancreatitis

The role of cytokines has been well documented in the pathogenesis of acute pancreatitis. Antibodies against specific cytokines have been used to treat pancreatitis, with mixed results. The transcription factor nuclear factor (NF)-kappa B is a pleiotropic regulator of many genes involved in stress and inflammatory responses. The aim of this study was to prevent the NF-kappa B binding activity and tumor necrosis factor (TNF)-alpha gene overexpression as a possible therapeutic intervention for acute pancreatitis. Reversible acute biliary pancreatitis was induced in male Sprague Dawley rats as established in this laboratory. The animals were sacrificed at 0, 5, 15, 30 min and 1, 2, 3, 4, 6, 8, 10, 12, and 24 hours after the induction of pancreatitis. NF-kappa B binding activity was determined by electrophoretic mobility shift assay, and TNF-alpha gene expression was assayed by reverse transcription-PCR. NF-kappa B binding activity was markedly higher around 4 hours and persisted up to 24 hours after pancreatitis induction in animals with acute pancreatitis, whereas TNF-alpha mRNA levels peaked at 24 hours. When amobarbital (to block NF-kappa B activation) was given (60 mg/kg body weight, I.P.) 3 hours before induction of pancreatitis, the activation of NF-kappa B and the overexpression of TNF-alpha gene was prevented, with significantly decreased severity of pancreatitis as assessed by amylase and clinical recovery. We conclude that 1) preventing the activation of NF-kappa B eliminates the induced overexpression of inflammatory cytokines (TNF-alpha) in acute pancreatitis, 2) such intervention correlates with clinical improvement in pancreatitis, and 3) this genetic modification offers a possible therapeutic intervention in acute pancreatitis.

A new animal model of reversible acute pancreatitis

Numerous animal models of acute pancreatitis are utilized to assess pathophysiologic events and to evaluate therapeutic options. However, none of the small animal models simulates reversible biliary pancreatitis with long-term follow-up (weeks). The present study was designed to create a reversible model of acute biliary pancreatitis in small experimental animals. Male Sprague-Dawley rats were subjected to laparotomy, and the common bile duct was dissected free at its junction to the duodenum. Experimental animals had a polypropylene tie occluder passed around the common bile duct and brought out through a separate stab wound in the abdominal wall. The duct was occluded for 24 hr; the blockage was then relieved and the tie withdrawn from the animal. Sham-operative animals had similar surgical procedures but without the occluder. Serum amylase values on Days 1 and 2 following surgery were significantly increased in the experimental group, but were not different from those of control animals on Day 3 or 4, suggesting reversibility of this biliary pancreatitis model. Likewise, serum bilirubin levels were increased in the experimental group on Days 1 and 2. Histologic analysis revealed edema, zymogen degranulation, inflammatory infiltration, vacuolization of acinar cells, and focal areas of fat and parenchymal necrosis in the experimental group. Only mild edema was observed in the sham-operative controls due to surgical manipulation. Pancreatic tissues obtained at 1 week postinduction of pancreatitis showed near total destruction of the architecture and dissolution of zymogen granules; in contrast, histology at the 3rd week showed almost normal-appearing pancreas with return of zymogen granules, suggesting recovery from the acute pancreatitis. This reproducible and reversible model of acute pancreatitis in the rat will provide for further studies in the pathogenesis of pancreatitis and its therapeutic interventions.

Cellular cardiomyoplasty: myocardial regeneration with satellite cell implantation

BACKGROUND

Damaged skeletal muscle is able to regenerate because of the presence of satellite cells, which are undifferentiated myoblasts. In contrast, destruction of cardiac myocytes is associated with an irreversible loss of myocardium and replacement with scar tissue, because it lacks stem cells. We tested the hypothesis that skeletal muscle satellite cells implanted into injured myocardium can differentiate into cardiac muscle fibers and thus repair damaged heart muscle.

METHODS

Two series of canine studies were performed. In the first series (n = 26), satellite cells were isolated from skeletal muscle, cultured, and labeled with tritiated thymidine. The cells were implanted into acutely cryoinjured myocardium and the specimens harvested 4 to 18 weeks later. In the second series (n = 20), satellite cells in culture were labeled with lacZ reporter gene, which encodes production of Escherichia coli beta-galactosidase. Four to 6 weeks later, beta-galactosidase activity was studied using X-Gal stain.

RESULTS

New striated muscles were found in the first series of experiments at the site of implantation, within a dense scar created by cryoinjury. These muscles showed histologic evidence of intercalated discs and centrally located nuclei, similar to those seen in cardiac muscle fibers. Tritiated thymidine radioactivity was not identified clearly, presumably due to dilutional effect as the stem cells replicated repeatedly. In the second series, histochemical studies of reporter gene-labeled and implanted satellite cells revealed the presence of beta-galactosidase within the cells at the implant site, which confirmed the survival of implanted cells.

CONCLUSIONS

Our data are consistent with the hypothesis of milieu-influenced differentiation of satellite cells into cardiac-like muscle cells. Confirmation of these findings and its functional capabilities could have important clinical implications.

Myocardial regeneration. Transplanting satellite cells into damaged myocardium

Millions of Americans suffer from chronic heart failure. Despite treatments with heart transplantation, cardiomyoplasty, and artificial assist devices, an ideal therapy is yet to be found. Since 1988, we have studied the transplantation of myogenic stem cells from skeletal muscle into injured myocardium in the hope that these cells would multiply and differentiate, thereby improving the function of the failing heart. We have achieved 2 goals thus far: the 1st was improving the culture technique to obtain high yield and purity of the satellite cells; the 2nd was successfully implanting cultured satellite cells in dog hearts and later identifying them as new myocardium. We share our findings here to encourage more study in this promising area.

Third place winner of the Conrad Jobst Award in the gold medal paper competition. Prevention of spinal cord dysfunction in a new model of spinal cord ischemia

Paraplegia or paraparesis caused by temporary cross-clamping of the aorta is a devastating sequela in patients after surgery of the thoracoabdominal aorta. No effective clinical method is available to protect the spinal cord from ischemic reperfusion injury. A small animal (rat) model of spinal cord ischemia is established to better understand the pathophysiological events and to evaluate potential treatments. Eighty-one male Sprague-Dawley rats weighing 300 g to 350 g were used for model development (45) and treatment evaluation (36). The heparinized and anesthetized rat was supported by a respirator following tracheostomy. The thoracic aorta was cannulated via the left carotid artery for post-clamping intra-aortic treatment solution administration. After thoracotomy, the aorta was freed and temporarily clamped just distal to the left subclavian artery and just proximal to the diaphragm for different time intervals: 0, 5, 10, 15, 20, 25, 30, 35, and 40 minutes (five animals per group). The motor function of the lower extremities postoperatively showed consistent impairment after 30 minutes clamping (5/5 rats were paralyzed), and this time interval was used for treatment evaluation. For each treatment, six animals per group were used, and direct local intra-aortic infusion of physiologic solution (2 mL) at different temperatures with or without buffer substances was given immediately after double cross-clamp to protect the ischemic spinal cord. Arterial blood (2 mL) was infused in the control group. The data indicate that the addition of HCO3-(20 mM) to the hypothermic (15 degrees C) solution offered complete protection of the spinal cord from ischemic injury.(ABSTRACT TRUNCATED AT 250 WORDS)