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Roberto Bolli

Publications and source records attributed to Roberto Bolli.

At least 37 records · Page 2Linked to original sources
PubMed2005

Role of the protein kinase C-epsilon-Raf-1-MEK-1/2-p44/42 MAPK signaling cascade in the activation of signal transducers and activators of transcription 1 and 3 and induction of cyclooxygenase-2 after ischemic preconditioning.

BACKGROUND: Although Janus kinase (JAK)-mediated Tyr phosphorylation of signal transducers and activators of transcription (STAT) 1 and 3 is essential for the upregulation of cyclooxygenase-2 (COX-2) and the cardioprotection of late preconditioning (PC), the role of Ser phosphorylation of STAT1 and STAT3 in late PC and the upstream signaling mechanisms responsible for mediating Ser phosphorylation of STAT1 and STAT3 remain unknown. METHODS AND RESULTS: In mice preconditioned with six 4-minute coronary occlusion/4-minute reperfusion cycles, we found that (1) ischemic PC activates the Raf1-mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase kinase (MEK) 1/2-p44/42 MAPK signaling pathway, induces phosphorylation of STAT1 and STAT3 on the Ser-727 residue, and upregulates COX-2 expression; (2) pSer-STAT1 and pSer-STAT3 form complexes with pTyr-p44/42 MAPKs in preconditioned myocardium, supporting the concept that Ser phosphorylation of these 2 factors is mediated by activated p44/42 MAPKs; and (3) activation of the Raf-1-MEK-1/2-p44/42 MAPK-pSer-STAT1/3 pathway and induction of COX-2 during ischemic PC are dependent on protein kinase C (PKC)-epsilon activity, as determined by both pharmacological and genetic inhibition of PKCepsilon. CONCLUSIONS: To our knowledge, this is the first study to demonstrate that ischemic PC causes Ser phosphorylation of STAT1 and STAT3 and that this event is governed by PKCepsilon via a PKCepsilon-Raf1-MEK1/2-p44/42 MAPK pathway. Furthermore, this is the first report that COX-2 expression in the heart is controlled by PKCepsilon. Together with our previous findings, the present study implies that STAT-dependent transcription of the genes responsible for ischemic PC is modulated by a dual signaling mechanism that involves both JAK1/2 (Tyr phosphorylation) and PKCepsilon (Ser phosphorylation).

Alkaloids↗
PubMed2005

Late preconditioning induced by NO donors, adenosine A1 receptor agonists, and delta1-opioid receptor agonists is mediated by iNOS.

Although ischemia-induced late preconditioning (PC) is known to be mediated by inducible nitric oxide (NO) synthase (iNOS), the role of this enzyme in pharmacologically induced late PC remains unclear. We tested whether targeted disruption of the iNOS gene abrogates late PC elicited by three structurally different NO donors [diethylenetriamine/NO (DETA/NO), nitroglycerin (NTG), and S-nitroso-N-acetyl-penicillamine (SNAP)], an adenosine A1 receptor agonist [2-chloro-N6-cyclopentyladenosine (CCPA)], and a delta1-opioid receptor agonist (TAN-670). The mice were subjected to a 30-min coronary occlusion followed by 24 h of reperfusion. In iNOS knockout (iNOS-/-) mice, infarct size was similar to wild-type (WT) controls, indicating that iNOS does not modulate infarct size in the absence of PC. Pretreatment of WT mice with DETA/NO, NTG, SNAP, TAN-670, or CCPA 24 h before coronary occlusion markedly reduced infarct size. In iNOS-/- mice, however, the late PC effect elicited by DETA/NO, NTG, SNAP, TAN-670, and CCPA was completely abrogated. Furthermore, in WT mice pretreated with TAN-670 or CCPA, the selective iNOS inhibitor 1400W also abolished the delayed PC properties of these drugs; 1400W had no effect in WT mice. These data demonstrate that iNOS plays an obligatory role in NO donor-induced, adenosine A1 receptor agonist-induced, and delta1-opioid receptor agonist-induced late PC, underscoring the critical role of this enzyme as a common mediator of cardiac adaptations to stress.

Adenosine↗
PubMed2005

Myocardial regeneration by activation of multipotent cardiac stem cells in ischemic heart failure.

In this study, we tested whether the human heart possesses a cardiac stem cell (CSC) pool that promotes regeneration after infarction. For this purpose, CSC growth and senescence were measured in 20 hearts with acute infarcts, 20 hearts with end-stage postinfarction cardiomyopathy, and 12 control hearts. CSC number increased markedly in acute and, to a lesser extent, in chronic infarcts. CSC growth correlated with the increase in telomerase-competent dividing CSCs from 1.5% in controls to 28% in acute infarcts and 14% in chronic infarcts. The CSC mitotic index increased 29-fold in acute and 14-fold in chronic infarcts. CSCs committed to the myocyte, smooth muscle, and endothelial cell lineages increased approximately 85-fold in acute infarcts and approximately 25-fold in chronic infarcts. However, p16(INK4a)-p53-positive senescent CSCs also increased and were 10%, 18%, and 40% in controls, acute infarcts, and chronic infarcts, respectively. Old CSCs had short telomeres and apoptosis involved 0.3%, 3.8%, and 9.6% of CSCs in controls, acute infarcts, and chronic infarcts, respectively. These variables reduced the number of functionally competent CSCs from approximately 26,000/cm3 of viable myocardium in acute to approximately 7,000/cm3 in chronic infarcts, respectively. In seven acute infarcts, foci of spontaneous myocardial regeneration that did not involve cell fusion were identified. In conclusion, the human heart possesses a CSC compartment, and CSC activation occurs in response to ischemic injury. The loss of functionally competent CSCs in chronic ischemic cardiomyopathy may underlie the progressive functional deterioration and the onset of terminal failure.

Apoptosis↗
PubMed2005

Delayed preconditioning-mimetic actions of nitroglycerin in patients undergoing exercise tolerance tests.

BACKGROUND: Nitroglycerin (NTG) induces delayed preconditioning (PC)-mimetic effects in animal models and in humans during coronary angioplasty. We tested the hypothesis that NTG mitigates ischemia and enhances functional capacity during an exercise tolerance test (ETT) in patients with coronary artery disease. METHODS AND RESULTS: Twenty-eight patients with stable angina and ischemia documented by a stress test were randomized in a double-masked, crossover design to receive a titrated intravenous infusion of NTG or normal saline over 4 hours. At 24 to 28 hours after study medication infusion, each patient underwent 2 ETTs separated by a 1-week washout period. Compared with control patients, pretreatment with NTG was associated with a dose-dependent increase in exercise duration averaging 40 seconds (412+/-19 versus 372+/-24 seconds, P=0.014) and an improvement in ECG manifestations of ischemia, as shown by a decrease in maximal ST-segment depression (1.84+/-0.14 versus 1.63+/-0.13 mm, P=0.011), sum of ST-segment depressions in 12 leads (7.64+/-1.01 versus 6.61+/-0.83 mm, P=0.027), and time to resolution of ST-segment depression (229+/-30 versus 207+/-28 s, P=0.018). These benefits occurred despite an increase in myocardial workload after NTG, as indicated by a higher peak rate-pressure product (24 492+/-1054 versus 22 536+/-1019 mm Hg/min, P=0.015). CONCLUSIONS: NTG produces a late PC-mimetic effect that mitigates the ECG manifestations of ischemia during exercise and improves exercise capacity. To our knowledge, this is the first study to demonstrate that NTG can alleviate exercise-induced ischemia 24 hours after its administration, long after the hemodynamic effects have subsided. The finding that nitrate-induced late PC ameliorates a common manifestation of coronary artery disease has potentially significant implications for the management of this disorder and for the design of clinical trials.

Aged↗
PubMed2005

Proapoptotic effects of caspase-1/interleukin-converting enzyme dominate in myocardial ischemia.

Caspase-1/interleukin-converting enzyme (ICE) is a cysteine protease traditionally considered to have importance as an inflammatory mediator, but not as an apoptotic effector. Because of the dual functions of this caspase, the pathophysiological impact of its reported upregulation in hypertrophy and heart failure is not known. Here, the consequences of increased myocardial expression of procaspase-1 were examined on the normal and ischemically injured heart. In unstressed mouse hearts with a 30-fold increase in procaspase-1 content, unprocessed procaspase-1 was well tolerated, without detectable pathology. Cardiomyocyte processing and activation of caspase-1 and caspase-3 occurred after administration of endotoxin or with transient myocardial ischemia. In post-ischemic hearts, procaspase-1 overexpression was associated with strikingly increased cardiac myocyte apoptosis in the peri- and noninfarct regions and with 50% larger myocardial infarctions. Tissue culture studies revealed that procaspase-1 processing/activation is stimulated by hypoxia, and that caspase-1 acts in synergy with hypoxia to stimulate caspase-3 mediated apoptosis without activating upstream caspases. These data demonstrate that the proapoptotic effects of caspase-1 can significantly impact the myocardial response to ischemia and suggest that conditions in which procaspase-1 in the heart is increased may predispose to apoptotic myocardial injury under conditions of physiological stress.

Animals↗
PubMed2005

Cardiac stem cells delivered intravascularly traverse the vessel barrier, regenerate infarcted myocardium, and improve cardiac function.

The ability of cardiac stem cells (CSCs) to promote myocardial repair under clinically relevant conditions (i.e., when delivered intravascularly after reperfusion) is unknown. Thus, rats were subjected to a 90-min coronary occlusion; at 4 h after reperfusion, CSCs were delivered to the coronary arteries via a catheter positioned into the aortic root. Echocardiographic analysis showed that injection of CSCs attenuated the increase in left ventricular (LV) end-diastolic dimensions and impairment in LV systolic performance at 5 weeks after myocardial infarction. Pathologic analysis showed that treated hearts exhibited a smaller increase in LV chamber diameter and volume and a higher wall thickness-to-chamber radius ratio and LV mass-to-chamber volume ratio. CSCs induced myocardial regeneration, decreasing infarct size by 29%. A diploid DNA content and only two chromosomes 12 were found in new cardiomyocytes, indicating that cell fusion did not contribute to tissue reconstitution. In conclusion, intravascular injection of CSCs after reperfusion limits infarct size, attenuates LV remodeling, and ameliorates LV function. This study demonstrates that CSCs are effective when delivered in a clinically relevant manner, a clear prerequisite for clinical translation, and that these beneficial effects are independent of cell fusion. The results establish CSCs as candidates for cardiac regeneration and support an approach in which the heart's own stem cells could be collected, expanded, and stored for subsequent therapeutic repair.

Animals↗
PubMed2005

Adult bone marrow-derived cells: regenerative potential, plasticity, and tissue commitment.

Reconstitution of infarcted myocardium with functional new cardiomyocytes and vessels, a goal that only a few years ago would have been regarded as extravagant, is now actively pursued in numerous laboratories and clinical centers. Several recent studies in animals as well as humans have shown that transplantation of adult bone marrow-derived cells (BMCs) can improve left ventricular function and halt adverse remodeling after myocardial infarction. Differentiation of adult BMCs into cells of cardiac and vascular lineages has been proposed as a mechanism underlying these benefits and, indeed, differentiation of adult BMCs into cells of non-hematopoietic lineages, including cells of brain, skeletal muscle, heart, liver, and other organs, has been documented repeatedly both in vitro and in vivo. These results are in contrast with conventional definitions and dogma, according to which adult tissue-specific stem cells exhibit only restricted differentiation potential. Thus, these recent studies have sparked intense debate over the ability of adult BMCs to differentiate into non-hematopoietic tissues, and the regeneration of myocardium by differentiation of adult BMCs remains highly controversial. Because of the enormous clinical implications of BMC-mediated cardiac repair, numerous laboratories are currently addressing the feasibility of cardiac regeneration with BMCs and deciphering the mechanism underlying the beneficial effects. The purpose of this review is to critically examine the available evidence regarding the ability of adult BMCs to regenerate non-hematopoietic tissues and their utility in therapeutic cardiac regeneration.

Animals↗
PubMed2005

Myocardial aging--a stem cell problem.

This review questions the old paradigm that describes the heart as a post-mitotic organ and introduces the notion of the heart as a self-renewing organ regulated by a compartment of multipotent cardiac stem cells (CSCs) capable of regenerating myocytes and coronary vessels throughout life. Because of this dramatic change in cardiac biology, the objective is to provide an alternative perspective of the aging process of the heart and stimulate research in an area that pertains to all of us without exception. The recent explosion of the field of stem cell biology, with the recognition that the possibility exists for extrinsic and intrinsic regeneration of myocytes and coronary vessels, necessitates reevaluation of cardiac homeostasis and myocardial aging. From birth to senescence, the mammalian heart is composed of non-dividing and dividing cells. Loss of telomeric DNA is minimal in fetal and neonatal myocardium but rather significant in the senescent heart. Aging affects the growth and differentiation potential of CSCs interfering not only with their ability to sustain physiological cell turnover but also with their capacity to adapt to increases in pressure and volume loads. The recognition of factors enhancing the activation of the CSC pool, their mobilization, and translocation, however, suggests that the detrimental effects of aging on the heart might be prevented or reversed by local stimulation of CSCs or the intramyocardial delivery of CSCs following their expansion and rejuvenation in vitro. CSC therapy may become, perhaps, a novel strategy for the devastating problem of heart failure in the old population.

Aging↗
PubMed2005

Cardiac preconditioning during percutaneous coronary interventions.

Ischemic preconditioning (PC) is a polygenic defensive cellular adaptive phenomenon of the heart to ischemic stress, whereby the heart changes its phenotype to become more resistant to subsequent ischemia. Early and late of PC represent two chronologically and pathophysiologically distinct phases of this phenomenon, which can be recruited pharmacologically. We represent a post hoc analysis examining the late PC-mimetic effects of nitroglycerin (NTG) on peri-procedural myocardial necrosis during percutaneous coronary intervention (PCI). A group of 66 patients presenting with angina were randomized, 24 h prior to a scheduled PCI for single obstructive CAD, to a 4 h pretreatment with intravenous NTG or saline. Measurements of electrocardiographic ST-segment shifts, echocardiographic regional wall motion and angina scores demonstrated that NTG pre-treatment preconditioned the heart by rendering it resistant to ischemia during balloon inflations. NTG-pretreated patients exhibited trends towards lower average peak CK (131.1 vs. 188.6 U/L, P = 0.38) and CK-MB levels (7.1 vs. 12.6 ng/ml, P = 0.40). NTG, however, had no significant impact on the incidence of post-procedural MI or any cardiac enzyme elevation. The exploitation of ischemic and pharmacological PC may prove a useful strategy to confer cardioprotection during high-risk PCI and is worth exploring.

Adenosine↗
PubMed2005

Short-term caloric restriction improves ischemic tolerance independent of opening of ATP-sensitive K+ channels in both young and aged hearts.

Ischemic tolerance decreases with aging and the cardioprotective effect of ischemic preconditioning (IPC) is impaired in aged animals. Although lifelong caloric restriction (CR) profoundly affects the physiological and pathophysiological modifications induced by aging and markedly increases life span in several species, it is unclear whether short-term CR affects ischemic tolerance and IPC in aged hearts. Six-month-old (Y) and 24-month-old (O) Fischer 344 male rats were randomly divided into two groups; AL rats were fed ad libitum, whereas CR rats were fed 90% of the caloric intake of AL for 2 weeks followed by 65% of the caloric intake for 2 weeks. Isolated perfused hearts were subjected to 25 min of ischemia followed by 30 min of reperfusion with or without IPC. The recovery of LV function after reperfusion improved with IPC in ALY but not in ALO. CR improved the recovery of LV function in both CRY and CRO but the cardioprotective effect of IPC was not additive to that of CR. Neither 5-hydroxydecanoate nor glibenclamide abrogated the protective effect of CR in either CRY or CRO. The recovery of myocardial high-energy phosphates after reperfusion was better with CR in both generations. There was no difference in myocardial expression levels of AMP-activated kinase (AMPK) but AMPK-alpha phosphorylated at Thr172 increased with CR in both Y and O. In conclusion, short-term CR improves myocardial ischemic tolerance independent of the opening of KATP channels in both Y and O. CR-induced cardioprotection is associated with an increase in activated AMPK.

AMP-Activated Protein Kinases↗
PubMed2004

Prostacyclin attenuates oxidative damage of myocytes by opening mitochondrial ATP-sensitive K+ channels via the EP3 receptor.

Prostacyclin (PGI2) and the PGE family alleviate myocardial ischemia-reperfusion injury and limit oxidative damage. The cardioprotective effects of PGI2 have been traditionally ascribed to activation of IP receptors. Recent advances in prostanoid research have revealed that PGI2 can bind not only to IP, but also to EP, receptors, suggesting cross talk between PGI2 and PGEs. The mechanism(s) whereby PGI2 protects myocytes from oxidative damage and the specific receptors involved remain unknown. Thus fresh isolated adult rat myocytes were exposed to 200 microM H2O2 with or without carbaprostacyclin (cPGI2), IP-selective agonists, and ONO-AE-248 (an EP3-selective agonist). Cell viability was assessed by trypan blue exclusion after 30 min of H2O2 superfusion. cPGI2 and ONO-AE-248 significantly improved cell survival during H2O2 superfusion; IP-selective agonists did not. The protective effect of cPGI2 and ONO-AE-248 was completely abrogated by pretreatment with 5-hydroxydecanoate or glibenclamide. In the second series of experiments, the mitochondrial ATP-sensitive K+ (K(ATP)) channel opener diazoxide (Dx) reversibly oxidized flavoproteins in control myocytes. Exposure to prostanoid analogs alone had no effect on flavoprotein fluorescence. A second application of Dx in the presence of cPGI2 or ONO-AE-248 significantly increased flavoprotein fluorescence compared with Dx alone, but IP-selective agonists did not. This study demonstrates that PGI2 analogs protect cardiac myocytes from oxidative stress mainly via activation of EP3. The data also indicate that activation of EP3 receptors primes the opening of mitochondrial K(ATP) channels and that this mechanism is essential for EP3-dependent protection.

Adenosine Triphosphate↗
PubMed2004

Administration of a CO-releasing molecule induces late preconditioning against myocardial infarction.

Mounting evidence suggests that carbon monoxide (CO) exerts powerful cytoprotective actions. CO-releasing molecules (CORMs) offer an effective means of delivering CO to tissues in vivo. The goal of the present study was to determine whether a water-soluble CORM, tricarbonylchloro(glycinato)ruthenium(II) (CORM-3), induces delayed protection against myocardial infarction 24 h later and to explore the duration of this protection. Mice received a 60-min i.v. infusion of CORM-3 or inactive CORM-3 (which does not release CO) and then, 24, 72, or 120 h later, underwent a 30-min coronary occlusion followed by 24 h of reperfusion. Pretreatment with CORM-3 24 h prior to coronary occlusion markedly reduced infarct size (24.8% +/- 2.9% of the risk region vs. 43.8% +/- 4.4% with inactive CORM-3). The infarct-sparing effect of CORM-3 was still evident 72 h after administration of the CO donor (20.4% +/- 3.7% of the risk region vs. 41.9% +/- 2.5% with inactive CORM-3) but was no longer apparent at 120 h. Both at 24 and 72 h, the protective effects of CORM-3 were equivalent to those afforded by the late phase of ischemic preconditioning (PC; 27.0% +/- 2.9% and 30.3% +/- 3.9% of the risk region, respectively). We conclude that the novel CO-releasing compound, CORM-3, induces delayed protection against myocardial infarction which is similar to that afforded by the late phase of ischemic PC, and that this salubrious effect is sustained for 72 h. To our knowledge, this is the first report that exposure to CO causes the heart to shift to a preconditioned phenotype. In addition, this study provides the first evidence that the cardioprotective actions of ischemic PC persist for 72 h in the mouse.

Animals↗
PubMed2004

Cells expressing early cardiac markers reside in the bone marrow and are mobilized into the peripheral blood after myocardial infarction.

The concept that bone marrow (BM)-derived cells participate in cardiac regeneration remains highly controversial and the identity of the specific cell type(s) involved remains unknown. In this study, we report that the postnatal BM contains a mobile pool of cells that express early cardiac lineage markers (Nkx2.5/Csx, GATA-4, and MEF2C). These cells are present in significant amounts in BM harvested from young mice but their abundance decreases with age; in addition, the responsiveness of these cells to gradients of motomorphogens SDF-1, HGF, and LIF changes with age. FACS analysis, combined with analysis of early cardiac markers at the mRNA and protein levels, revealed that cells expressing these markers reside in the nonadherent, nonhematopoietic CXCR4+/Sca-1+/lin-/CD45- mononuclear cell (MNC) fraction in mice and in the CXCR4+/CD34+/AC133+/CD45- BMMNC fraction in humans. These cells are mobilized into the peripheral blood after myocardial infarction and chemoattracted to the infarcted myocardium in an SDF-1-CXCR4-, HGF-c-Met-, and LIF-LIF-R-dependent manner. To our knowledge, this is the first demonstration that the postnatal BM harbors a nonhematopoietic population of cells that express markers for cardiac differentiation. We propose that these potential cardiac progenitors may account for the myocardial regenerative effects of BM. The present findings provide a novel paradigm that could reconcile current controversies and a rationale for investigating the use of BM-derived cardiac progenitors for myocardial regeneration.

Aged↗
PubMed2004

Overexpression of mitogen-activated protein kinase kinase 6 in the heart improves functional recovery from ischemia in vitro and protects against myocardial infarction in vivo.

The mitogen-activated protein kinases (MAPK) have been the subject of many studies to identify signaling pathways that promote cell survival or death. In cultured cardiac myocytes, p38 MAPK promotes cell survival or death depending on whether it is activated by mitogen-activated protein kinase kinase 6 (MKK6) or MKK3, respectively. The objectives of the current study were to examine the effects of MKK6-mediated p38 activation in the heart in vivo. Accordingly, we generated transgenic (TG) mice that overexpress wild type MKK6 in a cardiac-restricted manner. Although p38 was about 17-fold more active in TG than non-transgenic (NTG) mouse hearts, TG mouse hearts were morphologically and functionally similar to those of NTG littermates. However, upon transient ischemia followed by reperfusion, the MKK6 TG mouse hearts exhibited significantly better functional recovery and less injury than NTG mouse hearts. Because MKK6 increases levels of the protective small heat shock protein, alpha B-crystallin (alpha BC), in cultured cardiac myocytes, we examined alpha BC levels in the mouse hearts. The level of alpha BC was 2-fold higher in MKK6 TG than NTG mouse hearts. Moreover, ischemia followed by reperfusion induced a 6.4-fold increase in alpha BC levels in the mitochondrial fractions of TG mouse hearts but no increase in alpha BC levels in any of the other fractions analyzed. These alterations in alpha BC expression and localization suggest possible mechanisms of cardioprotection in MKK6 TG mouse hearts.

Animals↗
PubMed2004

IL-6 plays an obligatory role in late preconditioning via JAK-STAT signaling and upregulation of iNOS and COX-2.

OBJECTIVE: We sought to determine whether interleukin (IL)-6 modulates myocardial infarction or the late phase of preconditioning (PC). METHODS: Wild-type and IL-6(-/-) mice underwent a 30-min coronary occlusion followed by 24 h of reperfusion with or without six cycles of coronary occlusion/reperfusion 24 h earlier. Myocardial IL-6 protein expression, activation of Janus kinase (JAK) 1 and JAK2, and signal transducers and activators of transcription (STAT) 1 and STAT3 after ischemic PC protocol were examined. The expression of the inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 was determined 24 h after the PC ischemia. RESULTS: In preconditioned wild-type mice, infarct size was reduced from 60.5+/-2.6% of the risk region to 33.5+/-3.6%, indicating a late PC effect. In nonpreconditioned IL-6(-/-) mice, infarct size was similar to that observed in wild-type mice (59.9+/-3.8%), indicating that the deletion of IL-6 has no effect on infarct size. However, in preconditioned IL-6(-/-) mice, infarct size was not reduced (65.1+/-3.1%), indicating that the infarct-sparing effect was completely abrogated. Ischemic PC increased the expression of IL-6 in the cytoplasm of cardiomyocytes in the ischemic/reperfused zone. In IL-6(-/-) mice, the ischemic PC-induced activation of JAK1 and JAK2 and STAT1 and STAT3 was significantly reduced, and the increase in iNOS and COX-2 protein expression 24 h after the PC ischemia was markedly attenuated. CONCLUSION: IL-6 does not modulate myocardial infarct size in naïve myocardium. However, following a PC stimulus, IL-6 is obligatorily required for the activation of the JAK-STAT pathway, the ensuing upregulation of iNOS and COX-2 (co-mediators of late PC), and the development of a cardioprotective phenotype.

Animals↗