Myocardial Ischemia-reperfusion Injury In Mice Research Articles

MiR-219a-2 relieves myocardial ischemia-reperfusion injury by reducing calcium overload and cell apoptosis through HIF1α/ NMDAR pathway

ObjectiveDuring the process of myocardial ischemia-reperfusion injury (MIRI), the intracellular Ca2+ concentration ([Ca2+]i) continues to increase, leads to the cardiomyocyte apoptosis and eventually causes myocardial damage, while the upstream regulation mechanism of calcium overload is still unknown. This study focuses on the role of miR-219a-2 in MIRI and aims to elaborate its regulatory mechanism on calcium overload that occurs during MIRI. MethodsThe expression of miR-219a-2 was determined in the heart tissues of MIRI mice by qRT-PCR. The [Ca2+]i was measured by fluo-3 using a fluorescence microplate reader. The expression of hypoxiainducible factor 1α (HIF1α) and NR1, the obligatory subunit of N-methyl-d-aspartate receptor 1 (NMDAR), were measured by qRT-PCR and western blot. The luciferase reporter assay was used to confirm the interplay between miR-219a-2 and HIF1α and the interplay between HIF1α and NR1. The cell apoptosis was measured by the expression level of B-cell lymphoma 2 interacting mediator of cell death (Bim) and the number of TUNEL-positive cells. The myocardial infarct size of mice was measured by TTC/Evans Blue staining. ResultsMiR-219a-2 was down-regulated in the heart tissues of MIRI mice. miR-219a-2 overexpression decreased [Ca2+]i and the expression of HIF1α and NR1 in hypoxia/reoxygenation (H/R)-treated HL-1 cells. Then, the luciferase reporter assay showed that miR-219a-2 inhibited the transcription of HIF1α and HIF1α promoted the transcription of NR1. Both HIF1α overexpression and NMDAR function enhancement removed the inhibitory effect of miR-219a-2 on calcium overload and cell apoptosis in H/R-treated HL-1 cells. Finally, the overexpression of miR-219a-2 decreased Ca2+ concentration, cell apoptosis, and myocardial infarction size in MIRI mice, while the NMDAR function enhancer reversed the therapeutic effect of miR-219a-2. ConclusionMiR-219a-2 reducing NMDAR-mediated calcium overload via HIF1α/NR1 axis, thus alleviating cell apoptosis in MIRI.

High-loading Gα13-binding EXE peptide nanoparticles prevent thrombosis and protect mice from cardiac ischemia/reperfusion injury.

Inefficient delivery is a major obstacle to the development of peptide-based drugs targeting the intracellular compartment. We recently showed that selectively inhibiting integrin outside-in signaling using a peptide (mP6) derived from the Gα13-binding ExE motif within the integrin β3 cytoplasmic domain had antithrombotic effects. Here, we engineered lipid-stabilized, high-loading peptide nanoparticles (HLPN), in which a redesigned ExE peptide (M3mP6) constituted up to 70% of the total nanoparticle molarity, allowing efficient in vivo delivery. We observed that M3mP6 HLPN inhibited occlusive thrombosis more potently than a clopidogrel/aspirin combination without adverse effects on hemostasis in rodents. Furthermore, M3mP6 HLPN synergized with P2Y12 receptor inhibitors or the clopidogrel/aspirin combination in preventing thrombosis, without exacerbating hemorrhage. M3mP6 HLPN also inhibited intravascular coagulation more potently than the P2Y12 inhibitor cangrelor. Postischemia injection of M3mP6 HLPN protected the heart from myocardial ischemia-reperfusion injury in a mouse model. This study demonstrates an efficient in vivo peptide delivery strategy for a therapeutic that not only efficaciously prevented thrombosis with minimal bleeding risk but also protected from myocardial ischemia-reperfusion injury in mice.

Effect of electroacupuncture pretreatment on differential expression profiles of myocardial long non-coding RNA and mRNA in mice with myocardial ischemia-reperfusion injury

To observe the effect of electroacupuncture (EA) pretreatment at "Neiguan" (PC6) on expression profiles of myocardial long non-coding RNAs (LncRNAs) and mRNAs in myocardial ischemia-reperfusion injury (MIRI) mice, so as to explore its mechanisms underlying prevention of MIRI via regulating LncRNA expression. C57BL/6 mice were randomly divided into sham, model, and EA groups (n=4 in each group). The MIRI model was established by occlusion of the anterior descending branch (ADB) of the left coronary artery for 30 min, followed by reperfusion for 24 h. In the sham group, the ADB was only threaded beneath the artery without ligation. EA was applied to bilateral PC6 for 30 min prior to ischemia induction. Surgery was performed within 30 min at the end of EA stimulation. The expression profiles of differentially expressed LncRNAs and mRNAs in the left ventricular myocardium were analyzed by using LncRNA microarray. There was a significant diffe-rence in the expression pattern of LncRNAs and mRNAs among the sham, model and EA groups. A total of 1 693 LncRNAs and 2 858 mRNAs between the model and sham groups, and 3 859 LncRNAs and 1 343 mRNAs between the EA and model groups were identified to be differentially expressed candidates. According to Venn intersection analysis, LncRNAs with opposite regulative orientations in the model and EA groups were screened and defined as EA-related LncRNAs. LncRNA-mRNA co-expression analysis and Gene Ontology enrichment analysis of the EA-related LncRNAs predicted their roles to regulating post-traumatic stress and repairing of myocardial cells. Meanwhile, the proteins' function encoded by EA-related mRNAs mainly involved post-traumatic stress and inflammatory regulation. EA pretreatment at PC6 acupoint can produce extensive regulation on myocardial LncRNAs and mRNAs in MIRI mice, suggesting an involvement of LncRNAs in EA pretreatment induced improvement of MIRI. These results may provide direction and molecular basis for subsequent in-depth studies to reveal the underlying mechanisms of EA pretreatment for MIRI.

Inhibition of miR-217 Protects Against Myocardial Ischemia–Reperfusion Injury Through Inactivating NF-κB and MAPK Pathways

Recent studies have demonstrated that miRNAs play a vital role in regulating myocardial ischemia/reperfusion injury (MIRI). MiR-217 has been proven to be implicated in cardiac diseases such as chronic heart failure and cardiac myxoma. However, the role of miR-217 in MIRI is not clear. A mouse MIRI model was established and the myocardial infarct size was evaluated by TTC staining. The expression level of miR-217 in I/R group was determined by real-time polymerase chain reaction. Subsequently, MIRI mice and H9C2 cells were administrated with miR-217 inhibitor in vivo and in vitro, respectively. The levels of TNF-α and IL-6 were measured by commercially available ELISA kits. Blood and cell samples were collected for the measurement of lactate dehydrogenase (LDH) level and caspase-3 activity. Cell viability was assessed with the CCK-8 assay. We then explored the detailed molecular mechanisms by TargetScan 7.1 database and further studies were performed to prove the prediction by dual-luciferase reporter assay. Larger stainless infarct areas were observed in the MIRI group, accompanied by inceased serum LDH activity, indicating the mouse MIRI model was successfully established. MiR-217 was up-regulated in MIRI mice and hypoxia/reoxygenation-treated H9C2 cells. MiR-217 knockdown alleviated the MIRI in MIRI mouse model, and also attenuated the myocardial hypoxia/reoxygenation injury in H9C2 cells. Moreover, dual specificity protein phosphatase 14 (DUSP14) was proved to be a target of miR-217. Besides, further study indicated that inhibition of miR-217 protected against MIRI through inactivating NF-κB and MAPK pathways via targeting DUSP14. MiR-217 inhibition protected against MIRI through inactivating NF-κB and MAPK pathways by targeting DUSP14. This study may provide valuable diagnostic and factors and therapeutic agents for MIRI.

Long non-coding RNA KCNQ1OT1/microRNA-204-5p/LGALS3 axis regulates myocardial ischemia/reperfusion injury in mice

Myocardial ischemia/reperfusion (IR) injury is one of the most prevalent cardiovascular diseases, known for its high mortality and morbidity worldwide. Based on pre-existing evidence, LGALS3 has been found to be closely associated with cardiac diseases. Hence, the objective of our study is to explore the potential function of KCNQ1OT1/microRNA-204-5p (miR-204-5p)/ LGALS3 axis on myocardial IR injury and the underlying mechanism. A myocardial IR injury mouse model was established in vivo and an in vitro cardiomyocyte model was induced by hypoxia/Reoxygenation exposure. Next, gain- and loss-of-function experiments were employed in order to measure the viability and apoptosis of cardiomyocytes and the area of ischemic infarct by CCK-8, TUNEL staining and Evans blue/TTC double staining. LGALS3 was found to be highly expressed in myocardial IR injury. The downregulation of LGALS3 resulted in the alleviation of myocardial IR injury in mouse models. In addition, KCNQ1OT1 could promote the LGALS3 expression by binding to miR-204-5p, which led to aggravated myocardial IR injury. In conclusion, KCNQ1OT1 binds to miR-204-5p to exacerbate myocardial IR injury in mice through the up-regulation of LGALS3, providing a novel insight for myocardial IR injury treatment.

MicroRNA-374a protects against myocardial ischemia-reperfusion injury in mice by targeting the MAPK6 pathway

AimsClinical treatment strategies for patients with myocardial ischemia typically include coronary artery recanalization to restore myocardial blood supply. However, myocardial reperfusion insult often induces oxidative stress and inflammation, which further leads to apoptosis and necrosis of myocardial cells. Increasing evidence suggests that microRNAs (miRNAs) participate in the pathological and physiological processes associated with myocardial ischemia reperfusion. Main methodsIn this study, we established a myocardial H/R H9C2 cell model and a mouse I/R model to detect molecules implicated in myocardial I/R regulation and to determine the underlying signal transduction pathways. Key findingsHerein, we showed that the expression of miR-374a-5p decreased in a myocardial cell model (H9C2 cells) of hypoxia/reoxygenation (H/R) and mouse model of ischemia/reperfusion (I/R). Alternatively, overexpression of miR-374a-5p was found to ameliorate myocardial cell damage within both in vivo and in vitro models of ischemia. Further, mitogen-activated protein kinase 6 (MAPK6) was identified as a direct target of miR-374a-5p. Thus, by targeting MAPK6, miR-374a-5p was found to negatively regulate MAPK6 expression. However, up-regulation of MAPK6 functioned to inhibit the previously observed protective effect of miR-374a-5p in the H9C2 H/R model. SignificanceTaken together, our study suggests that miR-374a-5p may have protective effects against cardiac I/R injury in vivo, and H/R injury in vitro, thereby providing novel insights into the molecular mechanisms associated with ischemia/reperfusion injury and a potential novel therapeutic target.

RETRACTED: Protective effect of down-regulated microRNA-27a mediating high thoracic epidural block on myocardial ischemia-reperfusion injury in mice through regulating ABCA1 and NF-κB signaling pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. An Expression of Concern for this article was previously published while an investigation was conducted (see related editorial: https://doi.org/10.1016/j.biopha.2022.113812). This retraction notice supersedes the Expression of Concern published earlier. Concern was raised about the reliability of the heart images shown in Figure 1A, which appear to contain similar features to those found in other publications, as detailed here: https://pubpeer.com/publications/108A0BE9F52724D6879E23FAE7F361; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. Concerns over the provenance of the flow cytometry data in Figure 7A were also raised. The journal requested the corresponding author comment on these concerns and provide the associated raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Downregulated microRNA-330 suppresses left ventricular remodeling via the TGF-β1/Smad3 signaling pathway by targeting SRY in mice with myocardial ischemia-reperfusion injury.

microRNAs (miRs) are essential in the development of heart failure. The aim of this study is to investigate the effect of microRNA-330 (miR-330) on left ventricular remodeling via the TGF-β1/Smad3 signaling pathway by targeting the sex-determining region Y (SRY) in mice with myocardial ischemia-reperfusion injury (MIRI). Differentially expressed gene (DEG) in myocardial ischemia-reperfusion (IR) was screened out and the miR that targeted the DEG was also predicted and verified. A model of MIRI was established to detect the expression of miR-330, SRY, transforming growth factor-β (TGF-β1), and Sekelsky mothers against dpp3 (Smad3). To further investigate the role of miR-330 in MIRI with the involvement of SRY and TGF-β1/Smad3 signaling pathway, the modeled mice were treated with different mimic, inhibitor, or small interfering RNA (siRNA) to observe the changes of the related gene expression, as well as the myocardial infarction size and volume of myocardial collagen. SRY was screened out and verified as a target gene of miR-330. The MIRI mice showed enlarged myocardial infarction size, increased volume of myocardial collagen, increased expression of miR-330, TGF-β1 and Smad3, while decreased the expression of SRY. The MIRI mice treated with miR-330 inhibitor showed decreased myocardial infarction size, the volume of myocardial collagen, and expression of TGF-β1 and Smad3 but promoted expression of SRY. Our findings demonstrated that downregulated miR-330 could suppress left ventricular remodeling to inhibit the activation of the TGF-β1/Smad3 signaling pathway via negatively targeting of SRY in mice with MIRI. This can be a potential target in the strategy to attenuate patient suffering.

Protective role of microRNA-374 against myocardial ischemia-reperfusion injury in mice following thoracic epidural anesthesia by downregulating dystrobrevin alpha-mediated Notch1 axis.

Ischemia-reperfusion (I/R) injury often leads to myocardial apoptosis and necrosis. Studies have demonstrated the role microRNAs (miRs) played in myocardial I/R injury. Thus, we established a myocardial I/R injury model and a thoracic epidural anesthesia (TEA) model in mice to explore whether microRNA-374 (miR-374) affects myocardial I/R injury. We collected myocardial tissues to evaluate whether TEA exerts a protection effect on myocardial tissues. In addition, the levels of miR-374, dystrobrevin alpha (DTNA), and the statue of the Notch1 axis were detected. Subsequently, cardiomyocytes extracted from TEA mice were treated to regulate their levels of miR-374 and DTNA. After that, cell viability, cell cycle distribution, and apoptosis of cardiomyocytes were assessed. This was followed by the detection of the myocardial infarction area. The mice models of myocardial I/R injury were associated with poorly expressed miR-374 and highly expressed DTNA. TEA was found to protect myocardial tissues against myocardial I/R injury by elevating miR-374 and reducing DTNA. Dual-luciferase reporter assay validated that DTNA was the target gene of miR-374. Cardiomyocytes with overexpressed miR-374 were shown to have downregulated DTNA levels and blocked Notch1 axis. Overexpressed miR-374 was also found to promote the viability and inhibit the apoptosis of cardiomyocytes, as well as to increase the number of cells arrested in the S phase. In accordance with this, the myocardial infarction area was decreased with the upregulated miR-347 and downregulated DTNA. Collectively, these results demonstrated that, by inhibiting the activity of DTNA-mediated Notch1 axis, miR-374 could protect against myocardial I/R injury in mice after TEA.

Chronic Kidney Disease Exacerbates Myocardial Ischemia Reperfusion Injury: Role of Endoplasmic Reticulum Stress-Mediated Apoptosis.

Chronic kidney disease (CKD) is known to exacerbate myocardial ischemia reperfusion (IR) injury. However, the underlying mechanisms are still not well understood. Despite various strategies for cardioprotection, limited studies have been focused on the prevention of CKD-induced myocardial susceptibility to IR injury. Here, we hypothesized that excessive endoplasmic reticulum (ER) stress-mediated apoptosis involved in myocardial IR injury in CKD mice and pretreatment with chemical ER chaperone rendered the heart resistant to myocardial IR injury in the setting of CKD. CKD was induced by 5/6 subtotal nephrectomy (SN) in mice, whereas sham-operated mice served as control (Sham). CKD significantly aggravated the cardiac injury after IR in SN group than Sham group as reflected by more severe cardiac dysfunction, increased myocardial infarct size and the ratio of myocardial apoptosis. The expression of ER stress-mediated apoptotic proteins (Bcl-2 associated X protein (Bax), glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), caspase-12) was markedly upregulated after IR injury in SN group than Sham group, whereas the expression of anti-apoptotic protein, Bcl-2, was obviously downregulated. In addition, the chemical ER chaperone sodium 4-phenylbutyrate (4PBA) pretreatment ameliorated cardiac dysfunction and lessened the infarct size and myocardial apoptosis after IR injury in mice with CKD. Taken together, these findings demonstrated that excessive activation of ER stress-mediated apoptosis pathway involved in the CKD-induced myocardial susceptibility to IR injury, and chemical ER chaperone 4PBA alleviated myocardial IR injury in mice with CKD.

Acute and long-term cardioprotective effects of the Traditional Chinese Medicine MLC901 against myocardial ischemia-reperfusion injury in mice

MLC901, a traditional Chinese medicine containing a cocktail of active molecules, both reduces cerebral infarction and improves recovery in patients with ischemic stroke. The aim of this study was to evaluate the acute and long-term benefits of MLC901 in ischemic and reperfused mouse hearts. Ex vivo, under physiological conditions, MLC901 did not show any modification in heart rate and contraction amplitude. However, upon an ischemic insult, MLC901 administration during reperfusion, improved coronary flow in perfused hearts. In vivo, MLC901 (4 µg/kg) intravenous injection 5 minutes before reperfusion provided a decrease in both infarct size (49.8%) and apoptosis (49.9%) after 1 hour of reperfusion. Akt and ERK1/2 survival pathways were significantly activated in the myocardium of those mice. In the 4-month clinical follow-up upon an additional continuous per os administration, MLC901 treatment decreased cardiac injury as revealed by a 45%-decrease in cTnI plasmatic concentrations and an improved cardiac performance assessed by echocardiography. A histological analysis revealed a 64%-decreased residual scar fibrosis and a 44%-increased vascular density in the infarct region. This paper demonstrates that MLC901 treatment was able to provide acute and long-term cardioprotective effects in a murine model of myocardial ischemia-reperfusion injury in vivo.

Role of hypoxia-inducible factor-1α in sevoflurane postconditioning-induced reduction of myocardial ischemia-reperfusion injury in mice

Objective To evaluate the role of hypoxia-inducible factor-1α(HIF-1α) in sevoflurane postconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in mice. Methods Forty pathogen-free healthy male C57 mice, aged 8 weeks, weighing 20-30 g, were assigned into 4 groups (n=10 each) using a random number table: sham operation group(group Sham), myocardial I/R group (group I/R), sevoflurane postconditioning group (group SPC) and HIF-1α inhibitor 2Me2 group (group 2Me2). Myocardial I/R was induced by occlusion of the left anterior descending branch of the coronary artery for 30 min followed by 120 min of reperfusion in pentobarbital sodium-anesthetized mice.In group SPC, 3% sevoflurane was inhaled for 15 min starting from the onset of reperfusion.In group 2Me2, 30% 2Me2 (30 mg/kg) was intraperitoneally injected at 30 min before ischemia.The mice were sacrificed at the end of reperfusion, and the hearts were removed for determination of the myocardial infarct size (using the Image J software) and expression of HIF-1α in the nucleus of cardiomyocytes (by Western blot). Results Compared with group Sham, the myocardial infarct size was significantly increased in I/R, SPC and 2Me2 groups, the expression of HIF-1α was significantly up-regulated in I/R and SPC groups, and the expression of HIF-1α was significantly down-regulated in group 2Me2 (P<0.05). Compared with group I/R, the myocardial infarct size was significantly decreased, and the expression of HIF-1α was up-regulated in group SPC, and the myocardial infarct size was significantly increased, and the expression of HIF-1α was down-regulated in group 2Me2 (P<0.05). Compared with group SPC, the myocardial infarct size was significantly increased, and the expression of HIF-1α was down-regulated in group 2Me2 (P<0.05). Conclusion The mechanism by which sevoflurane postconditioning reduces myocardial I/R injury is related to up-regulation of HIF-1α expression in mice. Key words: Hypoxia-inducible factor 1, alpha subunit; Anesthetics, inhalation; Myocardial reperfusion injury; Ischemic postconditioning

Glaucocalyxin A Ameliorates Myocardial Ischemia-Reperfusion Injury in Mice by Suppression of Microvascular Thrombosis.

BackgroundThe aim of this study was to evaluate the cardio-protective roles of glaucocalyxin A (GLA) in myocardial ischemia-reperfusion injury and to explore the underlying mechanism.Material/MethodsMyocardial ischemia-reperfusion in wild-type C57BL/6J mice was induced by transient ligation of the left anterior descending artery. GLA or vehicle (solvent) was administrated intraperitoneally to the mice before reperfusion started. After 24 h of myocardial reperfusion, ischemic size was revealed by Evans blue/TTC staining. Cardiac function was evaluated by echocardiography and microvascular thrombosis was assessed by immunofluorescence staining of affected heart tissue. We also measured the phosphorylation of AKT, ERK, P-GSK-3β, and cleaved caspase 3 in the myocardium.ResultsCompared to the solvent-treated control group, GLA administration significantly reduced infarct size (GLA 13.85±2.08% vs. Control 18.95±0.97%, p<0.05) and improved left ventricular ejection fraction (LVEF) (GLA 53.13±1.11% vs. Control 49.99±1.25%, p<0.05) and left ventricular fractional shortening (LVFS) (28.34±0.71% vs. Control 25.11±0.74%, p<0.05) in mice subjected to myocardial ischemia-reperfusion. GLA also attenuated microvascular thrombosis (P<0.05) and increased the phosphorylation of pro-survival kinase AKT (P<0.05) and GSK-3β (P<0.05) in the myocardium upon reperfusion injury.ConclusionsAdministration of GLA before reperfusion ameliorates myocardial ischemia-reperfusion injury in mice. The cardio-protective roles of GLA may be mediated through the attenuation of microvascular thrombosis.

Protective effects of ghrelin against oxidative stress, inducible nitric oxide synthase and inflammation in a mouse model of myocardial ischemia/reperfusion injury via the HMGB1 and TLR4/NF-κB pathway.

The present study aimed to investigate the protective effects of ghrelin against oxidative stress, inducible nitric oxide synthase (iNOS) and inflammation in a mouse model of myocardial ischemia/reperfusion injury (MIRI). In addition, the study aimed to determine its underlying mechanisms. A mouse model of MIRI was used invivo, in order to ascertain the protective effects of ghrelin on MIRI. Commercial kits were used to measure the serum levels of creatine kinase (CK) and lactate dehydrogenase (LDH) in MIRI mice. Furthermore, Evan's Blue-triphenyltetrazolium chloride solution was used to analyze the protective effects of ghrelin against infarct size in MIRI mice. The underlying mechanisms were determined by measuring MIRI-induced tumor necrosis factor (TNF)‑α, interleukin (IL)‑6, superoxide dismutase (SOD), glutathione (GSH), GSH-peroxidase (GSH‑PX), malondialdehyde (MDA) and caspase‑3/caspase‑9 activities, and iNOS, high mobility group box1 (HMGB1), Toll‑like receptor4 (TLR4) and nuclear factor (NF)‑κB protein expression in MIRI mice. The results demonstrated that MIRI led to an increase in infarct size; CK, LDH, TNF‑α, IL‑6, MDA, caspase‑3 and caspase-9 serum levels; and iNOS protein expression. MIRI resulted in inhibition of SOD, FSH and GSH‑PX levels. Conversely, these alterations were significantly inhibited following treatment with ghrelin. In addition, the protective effects of ghrelin against MIRI suppressed HMGB1, TLR4 and NF‑κB protein expression in MIRI mice. The present study revealed that ghrelin exerted protective effects against oxidative stress, iNOS and inflammation in MIRI mice via the HMGB1/TLR4/NF-κB pathway.

Helix B Surface Peptide Protects against Acute Myocardial Ischemia-Reperfusion Injury via the RISK and SAFE Pathways in a Mouse Model

Objective: This study explores the effects of helix B surface peptide (HBSP) on myocardial infarct size (IS), cardiac function, cardiomyocyte apoptosis and oxidative stress damage in mouse hearts subjected to myocardial ischemia-reperfusion injury (MIRI) and also the mechanisms underlying the effects. Method: Male adult mice were subjected to 45 min of ischemia followed by 2 h of reperfusion; 5 min before the reperfusion, they were treated with HBSP or vehicle. MIRI-induced IS, cardiomyocyte apoptosis and cardiac functional impairment were determined and compared. Western blot analysis was then conducted to elucidate the mechanism of HBSP after treatment. Results: HBSP administration before reperfusion significantly reduced the myocardial IS, decreased cardiomyocyte apoptosis, reduced the activities of superoxide dismutase and malondialdehyde and partially preserved heart function. As demonstrated by the Western blot analysis, HBSP after treatment upregulated Akt/GSK-3β/ERK and STAT-3 phosphorylation; these inhibitors, in turn, weakened the beneficial effects of HBSP. Conclusion: HBSP plays a protective role in MIRI in mice by inhibiting cardiomyocyte apoptosis, reducing the MIRI-induced IS, oxidative stress and improving the heart function after MIRI. The mechanism underlying these effects of HBSP is related to the activation of the RISK (reperfusion injury salvage kinase, Akt/GSK-3β/ERK) and SAFE (STAT-3) pathways.

Abstract 12972: Ultrasound of the Spleen Reduces Myocardial Ischemia-Reperfusion Injury by Stimulating a Splenic Anti-inflammatory Pathway

Background: Accumulating evidence now shows that a cardio-splenic axis plays critical role in post-ischemic reperfusion injury of the heart. Here, we tested a nonpharmacologic, noninvasive, ultrasound-based treatment of the spleen to reduce myocardial ischemia-reperfusion injury in mice. Methods and Results: C57BL6 (B6) mice and IL-10 Knockout (KO) mice underwent 40 min of LAD occlusion followed by 60 min of reperfusion. Ultrasound of the spleen (US-treated, US-T) versus ultrasound of the liver (US-control, US-C) was performed 24 hours before LAD occlusion. The TTC &amp; Blue staining results showed that risk regions of all groups were identical. US-treated mice had significantly smaller myocardial infarct size than the US-control mice (p&lt;0.05). In B6 mice, splenectomy (SPLX) performed 30 min before ischemia reduced infarct size. Acute adoptive transfer of splenocytes (SPAT) from US-control B6 mice performed 25 min before ischemia significantly exacerbated the infarct size in SPLX mice. However, SPAT of the US-treated splenocytes abrogated this exacerbation of the infarct size (Figure). Western blot analysis showed that ultrasound significantly increased the splenic phosphorylation Akt levels at 24 hours after US treatment. Furthermore, splenic ultrasound failed to protect the myocardial ischemia-reperfusion injury in IL-10 KO mice. Conclusions: These results suggested that an ultrasound-based treatment could have therapeutic potential for attenuation of post-ischemic myocardial reperfusion injury, possibly by stimulating a splenic anti-inflammatory effect via an Akt-IL-10 Pathway.

TNF-α antagonism ameliorates myocardial ischemia-reperfusion injury in mice by upregulating adiponectin.

Tumor necrosis factor-α (TNF-α) antagonism alleviates myocardial ischemia-reperfusion (MI/R) injury. However, the mechanisms by which the downstream mediators of TNF-α change after acute antagonism during MI/R remain unclear. Adiponectin (APN) exerts anti-ischemic effects, but it is downregulated during MI/R. This study was conducted to investigate whether TNF-α is responsible for the decrease of APN, and whether antagonizing TNF-α affects MI/R injury by increasing APN. Male adult wild-type (WT), APN knockout (APN KO) mice, and those with cardiac knockdowns of APN receptors via siRNA injection were subjected to 30 min of MI followed by reperfusion. The TNF-α antagonist etanercept or globular domain of APN (gAD) was injected 10 min before reperfusion. Etanercept ameliorated MI/R injury in WT mice as evidenced by improved cardiac function, and reduced infarct size and cardiomyocyte apoptosis. APN concentrations were augmented in response to etanercept, followed by an increase in AMP-activated protein kinase phosphorylation. Etanercept still increased cardiac function and reduced infarct size and apoptosis in both APN KO and APN receptors knockdown mice. However, its potential was significantly weakened in these mice compared with the WT mice. TNF-α is responsible for the decrease in APN during MI/R. The cardioprotective effects of TNF-α neutralization are partially due to the upregulation of APN. The results provide more insight into the TNF-α-mediated signaling effects during MI/R and support the need for clinical trials to validate the efficacy of acute TNF-α antagonism in the treatment of MI/R injury.

Study on attenuate and synergistic mechanism between Aconiti Lateralis Praeparata Radix and Glycyrrhizae Radix for toxicity reduction based on metabonomic of MI-RI mouse cardiomyocytes

Sini decoction (SND), a classical traditional Chinese medicine emergency formula recorded in Shanghan Lun (Treatise on Febrile Diseases), which is composed of Aconiti Lateralis Preparata Radix, Glycyrrhizae Preparata Radix and Zingiberis Rhizoma. Modern clinical and pharmacological researches have shown that SND can protect the myocardium effectively during myocardial ischemia reperfusion injury (MI-RI). A myocardial ischemia reperfusion injury model of H9c2 cardiomyocytes in vitro has been established. Four groups, control group, MI-RI Model group, SND group and SND without Glycyrrhizae Radix group, were arranged. The livability, the level of LDH and CK activity in H9c2 cardiomyocytes in different groups were tested. By combining with principal components analysis (PCA), partial least squares discriminant analysis (PLS-DA), orthogonal partial least squares projection of latent structures-discriminant analysis (OPLS-DA), 17 biomarkers in extracellular fluid were identified and 15 of them were related to the pathway of biological processes. The results showed that the attenuate and synergistic mechanism between Aconiti Lateralis Praeparata Radix and Glycyrrhizae Radix for toxicity reduction was related with the glycolysis, lipid metabolism, citrate cycle and nitrogen metabolism of amino acids metabolism. The study proved the effect on H9c2 cardiomyocyte treated by MI-RI injury both SND group and SND without Glycyrrhizae Radix group, and compared with the SND without Glycyrrhizae Radix, the protective effect of myocardial ischemia reperfusion injury model of H9c2 cardiomyocyte from SND was stronger.

Gaseous Hydrogen Sulfide Protects against Myocardial Ischemia-Reperfusion Injury in Mice Partially Independent from Hypometabolism

BackgroundIschemia-reperfusion injury (IRI) is a major cause of cardiac damage following various pathological processes. Gaseous hydrogen sulfide (H2S) is protective during IRI by inducing a hypometabolic state in mice which is associated with anti-apoptotic, anti-inflammatory and antioxidant properties. We investigated whether gaseous H2S administration is protective in cardiac IRI and whether non-hypometabolic concentrations of H2S have similar protective properties.MethodsMale C57BL/6 mice received a 0, 10, or 100 ppm H2S-N2 mixture starting 30 minutes prior to ischemia until 5 minutes pre-reperfusion. IRI was inflicted by temporary ligation of the left coronary artery for 30 minutes. High-resolution respirometry equipment was used to assess CO2-production and blood pressure was measured using internal transmitters. The effects of H2S were assessed by histological and molecular analysis.ResultsTreatment with 100 ppm H2S decreased CO2-production by 72%, blood pressure by 14% and heart rate by 25%, while treatment with 10 ppm H2S had no effects. At day 1 of reperfusion 10 ppm H2S showed no effect on necrosis, while treatment with 100 ppm H2S reduced necrosis by 62% (p<0.05). Seven days post-reperfusion, both 10 ppm (p<0.01) and 100 ppm (p<0.05) H2S showed a reduction in fibrosis compared to IRI animals. Both 10 ppm and 100 ppm H2S reduced granulocyte-influx by 43% (p<0.05) and 60% (p<0.001), respectively. At 7 days post-reperfusion both 10 and 100 ppm H2S reduced expression of fibronectin by 63% (p<0.05) and 67% (p<0.01) and ANP by 84% and 63% (p<0.05), respectively.ConclusionsGaseous administration of H2S is protective when administered during a cardiac ischemic insult. Although hypometabolism is restricted to small animals, we now showed that low non-hypometabolic concentrations of H2S also have protective properties in IRI. Since IRI is a frequent cause of myocardial damage during percutaneous coronary intervention and cardiac transplantation, H2S treatment might lead to novel therapeutical modalities.

Abstract 15: Remote Ischemic Preconditioning Confers Late Protection Against Myocardial Ischemia-Reperfusion Injury in Mice by Upregulating Interleukin-10

Remote ischemic preconditioning (RIPC) induces a prolonged late phase of multi-organ protection against ischemia-reperfusion (IR) injury. In the present study, we tested the hypothesis that RIPC confers late protection against myocardial IR injury by upregulating expression of IL-10. Mice were exposed to lower limb RIPC or sham leg ischemia. After 24 h, mice with RIPC demonstrated decreased myocardial infarct size and improved cardiac contractility following 30-min ischemia and 120-min reperfusion (I-30/R-120), accompanied by increased phosphorylation of Akt and eNOS in the heart. These effects of RIPC were completely blocked by anti-IL-10 receptor antibodies. Moreover, in IL-10 KO mice, RIPC was no longer able to provide cardioprotection against IR injury. IL-10 receptors were expressed in cardiomyocytes under basal conditions. Stimulation with exogenous IL-10 increased Akt phosphorylation and decreased myocardial infarct size after I-30/R-120 in isolated perfused hearts. Wildtype mice with RIPC demonstrated increased plasma IL-10 levels, while in the preconditioned gastrocnemius muscle, the phosphatase PTEN was inactivated and expression of IL-10 was increased through Stat3. Myocyte-specific PTEN inactivation led to increased Stat3 phosphorylation and IL-10 protein expression in the gastrocnemius muscle. Taken together, these results suggest that RIPC induces late protection against myocardial IR injury by increasing expression of IL-10 in the remote muscle, followed by release of IL-10 into the circulation, and activation of protective signaling pathways in the heart. This study provides a scientific basis for the use of RIPC to confer systemic protection against IR injury.