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Phosphoinositide 3-kinase gamma/delta inhibition limits infarct size after myocardial ischemia/reperfusion injury.

ABSTRACT: Although phosphoinositide 3-kinases (PI3Ks) play beneficial pro-cell survival roles during tissue ischemia, some isoforms (gamma and delta) paradoxically contribute to the inflammation that damages these same tissues upon reperfusion. We therefore considered the possibility that selectively inhibiting proinflammatory PI3K isoforms during the reperfusion phase could ultimately limit overall tissue damage seen in ischemia/reperfusion injuries such as myocardial infarction. Panreactive and isoform-restricted PI3K inhibitors were identified by screening a novel chemical family; molecular modeling studies attributed isoform specificity based on rotational freedom of substituent groups. One compound (TG100-115) identified as a selective PI3K gamma/delta inhibitor potently inhibited edema and inflammation in response to multiple mediators known to participate in myocardial infarction, including vascular endothelial growth factor and platelet-activating factor; by contrast, endothelial cell mitogenesis, a repair process important to tissue survival after ischemic damage, was not disrupted. In rigorous animal MI models, TG100-115 provided potent cardioprotection, reducing infarct development and preserving myocardial function. Importantly, this was achieved when dosing well after myocardial reperfusion (up to 3 h after), the same time period when patients are most accessible for therapeutic intervention. In conclusion, by targeting pathologic events occurring relatively late in myocardial damage, we have identified a potential means of addressing an elusive clinical goal: meaningful cardioprotection in the postreperfusion time period.

SUBMITTER: Doukas J

PROVIDER: S-EPMC1702529 | biostudies-literature |

REPOSITORIES: biostudies-literature

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CaM Kinase II mediates maladaptive post-infarct remodeling but not acute myocardial ischemia/reperfusion injury

Project description:Calcium/calmodulin-dependent protein kinase II (CaMKII) was suggested to mediate ischemic myocardial injury and adverse cardiac remodeling. However, the specific functions of the CaMKII isoforms and splice variants in ischemia/reperfusion (I/R) injury have not been investigated yet. Thus, we studied the roles of the CaMKII isoforms and splice variants in I/R by the use of various CaMKII mutant mice. CaMKIIÎ´C was up-regulated already one day after I/R injury but surprisingly, acute I/R injury was neither affected in CaMKIIÎ´-deficient mice, CaMKIIÎ´-deficient mice in which the splice variants CaMKIIÎ´B and C were re-expressed nor in conditional CaMKIIÎ´/Î³ double-knockout mice (DKO). In contrast, 5 weeks after I/R, DKO mice were protected against extensive scar formation and cardiac dysfunction. Leukocyte infiltration was not altered one day but five days after I/R, explaining the late effects of CaMKII deletion on post-I/R remodeling. Other than reported before, we demonstrate that CaMKII is not critically involved in the immediate mechanisms that regulate acute I/R injury but in the process of post-infarct remodeling. We analysed 6 groups in total: 3 groups from wild-type control animals and 3 groups from CaMKII delta/gamma double-KO mice. Sham operated animals served as controls in both wild-type and KO animal groups. 2 different time points in ischia/reperfusion operated animals were investigated: 1 day and 5 days post-surgery.

2014-09-08 | E-GEOD-58486 | biostudies-arrayexpress

Cardiac Overexpression of S100A6 Attenuates Cardiomyocyte Apoptosis and Reduces Infarct Size After Myocardial Ischemia-Reperfusion.

Project description:Cardiomyocyte-specific transgenic mice overexpressing S100A6, a member of the family of EF-hand calcium-binding proteins, develop less cardiac hypertrophy, interstitial fibrosis, and myocyte apoptosis after permanent coronary ligation, findings that support S100A6 as a potential therapeutic target after acute myocardial infarction. Our purpose was to investigate S100A6 gene therapy for acute myocardial ischemia-reperfusion.We first performed in vitro studies to examine the effects of S100A6 overexpression and knockdown in rat neonatal cardiomyocytes. S100A6 overexpression improved calcium transients and protected against apoptosis induced by hypoxia-reoxygenation via enhanced calcineurin activity, whereas knockdown of S100A6 had detrimental effects. For in vivo studies, human S100A6 plasmid or empty plasmid was delivered to the left ventricular myocardium by ultrasound-targeted microbubble destruction in Fischer-344 rats 2 days prior to a 30-minute ligation of the left anterior descending coronary artery followed by reperfusion. Control animals received no therapy. Pretreatment with S100A6 gene therapy yielded a survival advantage compared to empty-plasmid and nontreated controls. S100A6-pretreated animals had reduced infarct size and improved left ventricular systolic function, with less myocyte apoptosis, attenuated cardiac hypertrophy, and less cardiac fibrosis.S100A6 overexpression by ultrasound-targeted microbubble destruction helps ameliorate myocardial ischemia-reperfusion, resulting in lower mortality and improved left ventricular systolic function post-ischemia-reperfusion via attenuation of apoptosis, reduction in cardiac hypertrophy, and reduced infarct size. Our results indicate that S100A6 is a potential therapeutic target for acute myocardial infarction.

| S-EPMC5523770 | biostudies-other

CaM Kinase II mediates maladaptive post-infarct remodeling but not acute myocardial ischemia/reperfusion injury

Project description:Calcium/calmodulin-dependent protein kinase II (CaMKII) was suggested to mediate ischemic myocardial injury and adverse cardiac remodeling. However, the specific functions of the CaMKII isoforms and splice variants in ischemia/reperfusion (I/R) injury have not been investigated yet. Thus, we studied the roles of the CaMKII isoforms and splice variants in I/R by the use of various CaMKII mutant mice. CaMKIIδC was up-regulated already one day after I/R injury but surprisingly, acute I/R injury was neither affected in CaMKIIδ-deficient mice, CaMKIIδ-deficient mice in which the splice variants CaMKIIδB and C were re-expressed nor in conditional CaMKIIδ/γ double-knockout mice (DKO). In contrast, 5 weeks after I/R, DKO mice were protected against extensive scar formation and cardiac dysfunction. Leukocyte infiltration was not altered one day but five days after I/R, explaining the late effects of CaMKII deletion on post-I/R remodeling. Other than reported before, we demonstrate that CaMKII is not critically involved in the immediate mechanisms that regulate acute I/R injury but in the process of post-infarct remodeling.

2014-09-08 | GSE58486 | GEO

Hypercholesterolemia affects cardiac function, infarct size and inflammation in APOE*3-Leiden mice following myocardial ischemia-reperfusion injury.

Project description:BackgroundHypercholesterolemia is a major risk factor for ischemic heart disease including acute myocardial infarction. However, long-term effects of hypercholesterolemia in a rodent myocardial ischemia-reperfusion injury model are unknown. Therefore, the effects of diet-induced hypercholesterolemia on cardiac function and remodeling were investigated up to eight weeks after myocardial ischemia-reperfusion (MI-R) injury which was induced in either normocholesterolemic (NC-MI) or hypercholesterolemic (HC-MI) APOE*3-Leiden mice.MethodsLeft ventricular (LV) dimensions were serially assessed using parasternal long-axis echocardiography followed by LV pressure-volume measurements. Subsequently, infarct size and the inflammatory response were analyzed by histology and fluorescence-activated cell sorting (FACS) analysis.ResultsIntrinsic LV function eight weeks after MI-R was significantly impaired in HC-MI compared to NC-MI mice as assessed by end-systolic pressure, dP/dtMAX, and -dP/dtMIN. Paradoxically, infarct size was significantly decreased in HC-MI compared to NC-MI mice, accompanied by an increased wall thickness. Hypercholesterolemia caused a pre-ischemic peripheral monocytosis, in particular of Ly-6Chi monocytes whereas accumulation of macrophages in the ischemic-reperfused myocardium of HC-MI mice was decreased.ConclusionDiet-induced hypercholesterolemia caused impaired LV function eight weeks after MI-R injury despite a reduced post-ischemic infarct size. This was preceded by a pre-ischemic peripheral monocytosis, while there was a suppressed accumulation of inflammatory cells in the ischemic-reperfused myocardium after eight weeks. This experimental model using hypercholesterolemic APOE*3-Leiden mice exposed to MI-R seems suitable to study novel cardioprotective therapies in a more clinically relevant animal model.

| S-EPMC6570022 | biostudies-literature

Disrupting the EMMPRIN (CD147)-cyclophilin A interaction reduces infarct size and preserves systolic function after myocardial ischemia and reperfusion.

Project description:Inflammation and proteolysis crucially contribute to myocardial ischemia and reperfusion injury. The extracellular matrix metalloproteinase inducer EMMPRIN (CD147) and its ligand cyclophilin A (CyPA) may be involved in both processes. The aim of the study was to characterize the role of the CD147 and CyPA interplay in myocardial ischemia/reperfusion (I/R) injury.Immunohistochemistry showed enhanced expression of CD147 and CyPA in myocardial sections from human autopsies of patients who had died from acute myocardial infarction and from mice at 24 hours after I/R. At 24 hours and 7 days after I/R, the infarct size was reduced in CD147(+/-) mice vs CD147(+/+) mice (C57Bl/6), in mice (C57Bl/6) treated with monoclonal antibody anti-CD147 vs control monoclonal antibody, and in CyPA(-/-) mice vs CyPA(+/+) mice (129S6/SvEv), all of which are associated with reduced monocyte and neutrophil recruitment at 24 hours and with a preserved systolic function at 7 days. The combination of CyPA(-/-) mice with anti-CD147 treatment did not yield further protection compared with either inhibition strategy alone. In vitro, treatment with CyPA induced monocyte chemotaxis in a CD147- and phosphatidylinositol 3-kinase-dependent manner and induced monocyte rolling and adhesion to endothelium (human umbilical vein endothelial cells) under flow in a CD147-dependent manner.CD147 and its ligand CyPA are inflammatory mediators after myocardial ischemia and reperfusion and represent potential targets to prevent myocardial I/R injury.

| S-EPMC3113549 | biostudies-literature

Vagal nerve stimulation started just prior to reperfusion limits infarct size and no-reflow.

Project description:Vagal nerve stimulation (VNS) started prior to, or during, ischemia has been shown to reduce infarct size. Here, we investigated the effect of VNS when started just prior to, and continued during early, reperfusion on infarct size and no-reflow and studied the underlying mechanisms. For this purpose, swine (13 VNS, 10 sham) underwent 45 min mid-LAD occlusion followed by 120 min of reperfusion. VNS was started 5 min prior to reperfusion and continued until 15 min of reperfusion. Area at risk, area of no-reflow (% of infarct area) and infarct size (% of area at risk), circulating cytokines, and regional myocardial leukocyte influx were assessed after 120 min of reperfusion. VNS significantly reduced infarct size from 67 ± 2 % in sham to 54 ± 5 % and area of no-reflow from 54 ± 6 % in sham to 32 ± 6 %. These effects were accompanied by reductions in neutrophil (~40 %) and macrophage (~60 %) infiltration in the infarct area (all p < 0.05), whereas systemic circulating plasma levels of TNFα and IL6 were not affected. The degree of cardioprotection could not be explained by the VNS-induced bradycardia or the VNS-induced decrease in the double product of heart rate and left ventricular systolic pressure. In the presence of NO-synthase inhibitor LNNA, VNS no longer attenuated infarct size and area of no-reflow, which was paralleled by similarly unaffected regional leukocyte infiltration. In conclusion, VNS is a promising novel adjunctive therapy that limits reperfusion injury in a large animal model of acute myocardial infarction.

| S-EPMC4549380 | biostudies-literature

Annexin A5 reduces infarct size and improves cardiac function after myocardial ischemia-reperfusion injury by suppression of the cardiac inflammatory response.

Project description:Annexin A5 (AnxA5) is known to have anti-inflammatory and anti-apoptotic properties. Inflammation and apoptosis are key processes in post-ischemic cardiac remodeling. In this study, we investigated the effect of AnxA5 on left ventricular (LV) function and remodeling three weeks after myocardial ischemia-reperfusion (MI-R) injury in hypercholesterolemic ApoE*3-Leiden mice. Using a mouse model for MI-R injury, we demonstrate AnxA5 treatment resulted in a 27% reduction of contrast-enhanced MRI assessed infarct size (IS). End-diastolic and end-systolic volumes were decreased by 22% and 38%, respectively. LV ejection fraction was increased by 29% in the AnxA5 group compared to vehicle. Following AnxA5 treatment LV fibrous content after three weeks was reduced by 42%, which was accompanied by an increase in LV wall thickness of the infarcted area by 17%. Two days and three weeks after MI-R injury the number of cardiac macrophages was significantly reduced in both the infarct area and border zones following AnxA5 treatment compared to vehicle treatment. Finally, we found that AnxA5 stimulation leads to a reduction of IL-6 production in bone-marrow derived macrophages in vitro. AnxA5 treatment attenuates the post-ischemic inflammatory response and ameliorates LV remodeling which improves cardiac function three weeks after MI-R injury in hypercholesterolemic ApoE*3-Leiden mice.

| S-EPMC5928225 | biostudies-literature

CaM Kinase II mediates maladaptive post-infarct remodeling and pro-inflammatory chemoattractant signaling but not acute myocardial ischemia/reperfusion injury.

Project description:CaMKII was suggested to mediate ischemic myocardial injury and adverse cardiac remodeling. Here, we investigated the roles of different CaMKII isoforms and splice variants in ischemia/reperfusion (I/R) injury by the use of new genetic CaMKII mouse models. Although CaMKIIδC was upregulated 1 day after I/R injury, cardiac damage 1 day after I/R was neither affected in CaMKIIδ-deficient mice, CaMKIIδ-deficient mice in which the splice variants CaMKIIδB and C were re-expressed, nor in cardiomyocyte-specific CaMKIIδ/γ double knockout mice (DKO). In contrast, 5 weeks after I/R, DKO mice were protected against extensive scar formation and cardiac dysfunction, which was associated with reduced leukocyte infiltration and attenuated expression of members of the chemokine (C-C motif) ligand family, in particular CCL3 (macrophage inflammatory protein-1α, MIP-1α). Intriguingly, CaMKII was sufficient and required to induce CCL3 expression in isolated cardiomyocytes, indicating a cardiomyocyte autonomous effect. We propose that CaMKII-dependent chemoattractant signaling explains the effects on post-I/R remodeling. Taken together, we demonstrate that CaMKII is not critically involved in acute I/R-induced damage but in the process of post-infarct remodeling and inflammatory processes.

| S-EPMC4287929 | biostudies-literature

NO-independent stimulation or activation of soluble guanylyl cyclase during early reperfusion limits infarct size.

Project description:AimsGuanylyl cyclase-cyclic guanosine monophosphate signalling plays an important role in endogenous cardioprotective signalling. The aim was to assess the potential of direct pharmacological activation and stimulation of soluble guanylyl cyclase, targeting different redox states of the enzyme, to limit myocardial necrosis during early reperfusion.Methods and resultsRat isolated hearts were subjected to reversible left coronary artery occlusion (ischaemia-reperfusion) and infarct size was assessed by the tetrazolium staining technique. Administration during early reperfusion of BAY 41-2272, an NO-independent, haem-dependent stimulator of soluble guanylyl cyclase targeting the reduced state, or BAY 60-2770, an NO-independent, haem-independent activator targeting the oxidized state, significantly limited infarct size. Inhibition of NO synthesis did not abrogate this protection, but exogenous perfusion of NO with BAY 41-2272 produced a synergistic effect. The haem site oxidiser, ODQ abrogated the protection afforded by BAY 41-2272 but potentiated the protection afforded by BAY 60-2770. Targeting both the reduced and oxidized forms of sGC together did not afford additive protection.ConclusionsTargeting either reduced or oxidized forms of sGC during early reperfusion affords cardioprotection, providing support for the concept that direct sGC manipulation at reperfusion has therapeutic potential for the management of acute myocardial infarction.

| S-EPMC3896250 | biostudies-literature

?-Lipoic acid reduces infarct size and preserves cardiac function in rat myocardial ischemia/reperfusion injury through activation of PI3K/Akt/Nrf2 pathway.

Project description:BackgroundThe present study investigates the effects and mechanisms of ?-Lipoic acid (LA) on myocardial infarct size, cardiac function and cardiomyocyte apoptosis in rat hearts subjected to in vivo myocardial ischemia/reperfusion (MI/R) injury.Methodology/principal findingsMale adult rats underwent 30 minutes of ischemia followed by 3, 24, or 72 h of reperfusion. Animals were pretreated with LA or vehicle before coronary artery ligation. The level of MI/R- induced LDH and CK release, infarct size, cardiomyocyte apoptosis and cardiac functional impairment were examined and compared. Western blot analysis was performed to elucidate the mechanism of LA pretreatment. The level of inflammatory cytokine TNF-? released to serum and accumulated in injured myocardium as well as neutrophil accumulation in injured myocardium were also examined after MI/R injury. Our results reveal that LA administration significantly reduced LDH and CK release, attenuated myocardial infarct size, decreased cardiomyocytes apoptosis, and partially preserved heart function. Western blot analysis showed that LA pretreatment up-regulated Akt phosphorylation and Nrf2 nuclear translocation while producing no impact on p38MAPK activation or nitric oxide (NO) production. LA pretreatment also increased expression of HO-1, a major target of Nrf2. LA treatment inhibited neutrophil accumulation and release of TNF-?. Moreover, PI3K inhibition abolished the beneficial effects of LA.Conclusions/significanceThis study indicates that LA attenuates cardiac dysfunction by reducing cardiomyoctyes necrosis, apoptosis and inflammation after MI/R. LA exerts its action by activating the PI3K/Akt pathway as well as subsequent Nrf2 nuclear translocation and induction of cytoprotective genes such as HO-1.

| S-EPMC3591314 | biostudies-literature

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