Urocortin-2 suppression of p38-MAPK signaling as an additional mechanism for ischemic cardioprotection

Therapeutic knockdown of miR-320 improves deteriorated cardiac function in a pre-clinical model of non-ischemic diabetic heart disease

Non-ischemic diabetic heart disease (NiDHD) is characterized by diastolic dysfunction and decreased or preserved systolic function, eventually resulting in heart failure. Accelerated apoptotic cell death because of alteration of molecular signaling pathways due to dysregulation in microRNAs (miRNAs) plays a significant role in the development of NiDHD. Here, we aimed to determine the pathological role of cardiomyocyte-enriched pro-apoptotic miR-320 in the development of NiDHD. We identified a marked upregulation of miR-320 that was associated with downregulation of its target protein insulin growth factor-1 (IGF-1) in human right atrial appendage tissue in the late stages of cardiomyopathy in type 2 diabetic db/db mice and high-glucose-cultured human ventricular cardiomyocytes (AC-16 cells). In vitro knockdown of miR-320 in high-glucose-exposed AC-16 cells using locked nucleic acid (LNA) anti-miR-320 markedly reduced high-glucose-induced apoptosis by restoring IGF-1 and Bcl-2. Finally, in vivo knockdown of miR-320 in 24-week-old type 2 diabetic db/db mice reduced cardiomyocyte apoptosis and interstitial fibrosis while restoring vascular density. This resulted in partial recovery of the impaired diastolic and systolic function. Our study provides evidence that miR-320 is a late-responding miRNA that aggravates apoptosis and cardiac dysfunction in the diabetic heart, and that therapeutic knockdown of miR-320 is beneficial in partially restoring the deteriorated cardiac function.

Stage-specific regulation of signalling pathways to differentiate pluripotent stem cells to cardiomyocytes with ventricular lineage

Background

Pluripotent stem cells (PSCs) can be an ideal source of differentiation of cardiomyocytes in vitro and during transplantation to induce cardiac regeneration. However, differentiation of PSCs into a heterogeneous population is associated with an increased incidence of arrhythmia following transplantation. We aimed to design a protocol to drive PSCs to a ventricular lineage by regulating Wnt and retinoic acid (RA) signalling pathways.

Methods

Mouse embryonic stem cells were cultured either in monolayers or three-dimensional hanging drop method to form embryonic bodies (EBs) and exposed to different treatments acting on Wnt and retinoic acid signalling. Samples were collected at different time points to analyse cardiomyocyte-specific markers by RT-PCR, flow cytometry and immunofluorescence.

Results

Treatment of monolayer and EBs with Wnt and RA signalling pathways and ascorbic acid, as a cardiac programming enhancer, resulted in the formation of an immature non-contractile cardiac population that expressed many of the putative markers of cardiac differentiation. The population exhibited upregulation of ventricular specific markers while suppressing the expression of pro-atrial and pro-sinoatrial markers. Differentiation of EBs resulted in early foetal like non-contractile ventricular cardiomyocytes with an inherent propensity to contract when stimulated.

Conclusion

Our results provide the first evidence of in vitro differentiation that mimics the embryonic morphogenesis towards ventricular specific cardiomyocytes through regulation of Wnt and RA signalling pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02845-9.

Urocortin 2 promotes hypertrophy and enhances skeletal muscle function through cAMP and insulin/IGF-1 signaling pathways

Objective

Although it is well established that urocortin 2 (Ucn2), a peptide member of the corticotrophin releasing factor (CRF) family, and its specific corticotrophin-releasing factor 2 receptor (CRF2R) are highly expressed in skeletal muscle, the role of this peptide in the regulation of skeletal muscle mass and protein metabolism remains elusive.

Methods

To elucidate the mechanisms how Ucn2 directly controls protein metabolism in skeletal muscles of normal mice, we carried out genetic tools, physiological and molecular analyses of muscles in vivo and in vitro.

Results

Here, we demonstrated that Ucn2 overexpression activated cAMP signaling and promoted an expressive muscle hypertrophy associated with higher rates of protein synthesis and activation of Akt/mTOR and ERK1/2 signaling pathways. Furthermore, Ucn2 induced a decrease in mRNA levels of atrogin-1 and in autophagic flux inferred by an increase in the protein content of LC3-I, LC3-II and p62. Accordingly, Ucn2 reduced both the transcriptional activity of FoxO in vivo and the overall protein degradation in vitro through an inhibition of lysosomal proteolytic activity. In addition, we demonstrated that Ucn2 induced a fast-to-slow fiber type shift and improved fatigue muscle resistance, an effect that was completely blocked in muscles co-transfected with mitogen-activated protein kinase phosphatase 1 (MKP-1), but not with dominant-negative Akt mutant (Aktmt).

Conclusions

These data suggest that Ucn2 triggers an anabolic and anti-catabolic response in skeletal muscle of normal mice probably through the activation of cAMP cascade and participation of Akt and ERK1/2 signaling. These findings open new perspectives in the development of therapeutic strategies to cope with the loss of muscle mass.

•

Ucn2 overexpression promotes muscle growth due to an increase in protein synthesis.

•

Ucn2 inhibits FoxO activity and autophagic-lysosomal system.

•

Ucn2-induced skeletal muscle phenotype is dependent on Akt and ERK1/2.

•

Ucn2 induces a fast-to-slow fiber type shift and improves fatigue resistance.

•

The increase in muscle fatigue resistance is dependent on ERK1/2.

Neuroprotective Effects of Alpinia oxyphylla Miq against Mitochondria-Related Apoptosis by the Interactions between Upregulated p38 MAPK Signaling and Downregulated JNK Signaling in the Subacute Phase of Cerebral Ischemia-Reperfusion in Rats

Apoptosis in the penumbra region is the major cell death mechanism occurring during ischemia–reperfusion injury’s early phase. Here, we evaluated how the Alpinia oxyphylla Miq (AOM) affects mitochondria-related apoptosis 3 days after transient middle cerebral artery occlusion (MCAo) and examined the mechanisms underlying the regulation of MAPK-mediated mitochondria-related apoptotic signaling in the peri-infarct cortex in rats. The rats were administered the AOM extract intraperitoneally at doses of 0.2[Formula: see text]g/kg (AOM-0.2[Formula: see text]g), 0.4[Formula: see text]g/kg (AOM-0.4[Formula: see text]g), or 0.8[Formula: see text]g/kg (AOM-0.8[Formula: see text]g) at MCAo initiation. The AOM-0.4[Formula: see text]g and AOM-0.8[Formula: see text]g significantly ameliorated apoptotic cell death and considerably downregulated cytochrome c (cyto c) and cleaved caspase-3 immunoreactivity 3 days after reperfusion. Simultaneously, they significantly downregulated cytosolic p-JNK/JNK, cathepsin B/actin, cyto c/actin, Smac/DIABLO/actin, cleaved caspase-3/actin, and AIF/actin and mitochondrial p53/HSP60 and Bax/HSP60 fractions but upregulated cytosolic p-p38 MAPK/p38 MAPK, p-p90RSK/actin, p-Bad/Bad, p-CREB/actin, and XIAP/actin and cytosolic and mitochondrial Bcl-2/Bax and Bcl-xL/Bax fractions in the peri-infarct cortex. Pretreatment with SB203580 — a p38 MAPK inhibitor — completely abrogated the effects of AOM-0.8[Formula: see text]g on the aforementioned protein expression, whereas treatment with SP600125 — a JNK inhibitor — exerted protective effects similar to those of AOM-0.8[Formula: see text]g. Treatment with 0.4 or 0.8[Formula: see text]g/kg AOM has neuroprotective effects against mitochondria-related apoptosis by suppressing cyto c, Smac/DIABLO, and AIF release from the mitochondria to cytosol. The anti-mitochondria related apoptotic effects of the AOM extract are attributable to the interactions between upregulated p38 MAPK/p90RSK-mediated p-Bad and CREB signaling and downregulated JNK/cathepsin B-mediated Bax and p53 signaling in the peri-infarct cortex 3 days after transient MCAo.

Urocortin Role in Ischemia Cardioprotection and the Adverse Cardiac Remodeling

Despite the considerable progress in strategies of myocardial protection, ischemic heart diseases (IHD) and consequent heart failure (HF) remain the main cause of mortality worldwide. Several procedures are used routinely to guarantee the prompt and successful reestablishment of blood flow to preserve the myocardial viability of infarcted hearts from ischemia injuries. However, ischemic heart reperfusion/revascularization triggers additional damages that occur when oxygen-rich blood re-enters the vulnerable myocardial tissue, which is a phenomenon known as ischemia and reperfusion (I/R) syndrome. Complications of I/R injuries provoke the adverse cardiac remodeling, involving inflammation, mishandling of Ca²⁺ homeostasis, apoptotic genes activation, cardiac myocytes loss, etc., which often progress toward HF. Therefore, there is an urgent need to develop new cardioprotective therapies for IHD and HF. Compelling evidence from animal studies and pilot clinical trials in HF patients suggest that urocortin (Ucn) isoforms, which are peptides associated with stress and belonging to the corticotropin releasing factor family, have promising potential to improve cardiovascular functions by targeting many signaling pathways at different molecular levels. This review highlights the current knowledge on the role of urocortin isoforms in cardioprotection, focusing on its acute and long-term effects.

[8]-Gingerol exerts anti-myocardial ischemic effects in rats via modulation of the MAPK signaling pathway and L-type Ca2+ channels

Myocardial ischemia (MI) remains the leading cause of mortality worldwide. Therefore, it is urgent to seek the treatment to protect the heart. [8]‐Gingerol (8‐Gin), one of the most active ingredients in ginger, has antioxidant, cardiotonic, and cardiovascular protective properties. The present study elucidated the cardioprotection effects and underlying mechanisms of 8‐Gin in isoproterenol (ISO)‐induced MI. ISO (85 mg/kg/d) was subcutaneously injected for 2 consecutive days to induce acute MI model in rats. Electrocardiography, oxidative stress levels, calcium concentrations, and apoptosis degree were observed. The effects of 8‐Gin on L‐type Ca²⁺ current (I_Ca‐L), contraction, and Ca²⁺ transients were monitored in rat myocytes via patch‐clamp and IonOptix detection systems. 8‐Gin decreased J‐point elevation and heart rate and improved pathological heart damage. Moreover, 8‐Gin reduced the levels of CK, LDH, and MDA, ROS production, and calcium concentrations in myocardial tissue, while increased the activities of SOD, CAT, and GSH. In addition, 8‐Gin down‐regulated Caspase‐3 and Bax expressions, while up‐regulated Bcl‐2 expression. 8‐Gin produced a marked decrease in the expression of p38, JNK, and ERK1/2 proteins. 8‐Gin inhibited I_Ca‐L, cell contraction, and Ca²⁺ transients in isolated rat myocytes. The results indicate that 8‐Gin could exert anti‐myocardial ischemic effects, which may be associated with oxidative stress reduction, cardiomyocytes apoptosis inhibition through MAPK signaling pathway, and Ca²⁺ homeostasis regulation via I_Ca‐L modulation.

miR-451 on Myocardial Ischemia-Reperfusion in Rats by Regulating AMPK Signaling Pathway

Myocardial infarction is the main cause of death in patients with coronary heart disease. At present, the main method to treat cardiovascular disease is perfusion therapy. Myocardial ischemia-reperfusion will inevitably lead to reperfusion injury, which is also a major problem in the treatment of cardiovascular diseases. It has been reported that mir-451 in microRNA family participates in the protection of myocardial ischemia-reperfusion by regulating AMPK. The aim of this study was to investigate the effect of mir-451 on myocardial ischemia-reperfusion in rats by regulating AMPK signaling pathway. Sixty adult male rats were selected to establish myocardial ischemia-reperfusion animal model by ligating and loosening coronary artery. The expression level of mir-451 was regulated by injection of mir-451 virus vector and antibody, and the effect of increased or decreased mir-451 expression level on the activity of AMPK signaling pathway was detected. The myocardial infarct area and apoptosis rate of myocardial tissue were detected after 75 min ischemia-reperfusion. The results showed that when the expression level of mir-451 decreased by 15.7%, the activity index of AMPK signaling pathway was increased by 18.3%, the infarct area was reduced by 22.4%, and the apoptosis rate of myocardial cells was decreased by 25.2%. At the same time, the pathological structure of myocardial tissue was improved. Therefore, mir-451 is an inhibitor gene of AMPK signaling pathway. Reducing the expression of mir-451 can enhance the activity of AMPK signal pathway, and the increase of AMPK signal pathway activity is beneficial to reduce myocardial ischemia-reperfusion injury.

Modification of ischemia/reperfusion induced infarct size by ischemic preconditioning in hypertrophied hearts

This study examined the effects of ischemic preconditioning (IP) on the ischemia/reperfusion (I/R) induced injury in normal and hypertrophied hearts. Cardiac hypertrophy in rabbits was induced by L-thyroxine (0.5 mg/kg/day for 16 days). Hearts with or without IP (3 cycles of 5 min ischemia and 10 min reperfusion) were subjected to I/R (60 min ischemia followed by 60 min reperfusion). IP reduced the I/R-induced infarct size from 68% to 24% and 57% to 33% in the normal and hypertrophied hearts, respectively. Leakage of creatine phosphokinase in the perfusate from the hypertrophied hearts due to I/R was markedly less than that form the normal hearts; IP prevented these changes. Although IP augmented the increase in phosphorylated p38-mitogen-activated protein kinase (p38-MAPK) content due to I/R, this effect was less in the hypertrophied than in the normal heart. These results suggest that reduced cardioprotection by IP of the I/R-induced injury in hypertrophied hearts may be due to reduced activation of p38-MAPK in comparison with normal hearts.

Exercise Regulates MicroRNAs to Preserve Coronary and Cardiac Function in the Diabetic Heart

RATIONALE

Diabetic heart disease (DHD) is a debilitating manifestation of type 2 diabetes mellitus. Exercise has been proposed as a potential therapy for DHD, although the effectiveness of exercise in preventing or reversing the progression of DHD remains controversial. Cardiac function is critically dependent on the preservation of coronary vascular function.

OBJECTIVE

We aimed to elucidate the effectiveness and mechanisms by which exercise facilitates coronary and cardiac-protection during the onset and progression of DHD.

METHODS AND RESULTS

Diabetic db/db and nondiabetic mice, with or without underlying cardiac dysfunction (16 and 8 weeks old, respectively) were subjected to either moderate-intensity exercise or high-intensity exercise for 8 weeks. Subsequently, synchrotron microangiography, immunohistochemistry, Western blot, and real-time polymerase chain reaction were used to assess time-dependent changes in cardiac and coronary structure and function associated with diabetes mellitus and exercise and determine whether these changes reflect the observed changes in cardiac-enriched and vascular-enriched microRNAs (miRNAs). We show that, if exercise is initiated from 8 weeks of age, both moderate-intensity exercise and high-intensity exercise prevented the onset of coronary and cardiac dysfunction, apoptosis, fibrosis, microvascular rarefaction, and disruption of miRNA signaling, as seen in the nonexercised diabetic mice. Conversely, the cardiovascular benefits of moderate-intensity exercise were absent if the exercise was initiated after the diabetic mice had already established cardiac dysfunction (ie, from 16 weeks of age). The experimental silencing or upregulation of miRNA-126 activity suggests the mechanism underpinning the cardiovascular benefits of exercise were mediated, at least in part, through tissue-specific miRNAs.

CONCLUSIONS

Our findings provide the first experimental evidence for the critical importance of early exercise intervention in ameliorating the onset and progression of DHD. Our results also suggest that the beneficial effects of exercise are mediated through the normalization of cardiovascular-enriched miRNAs, which are dysregulated in DHD.

The Role of IL-33 in Experimental Heart Transplantation

Interleukin-33 (IL-33) is a member of the IL-1 family of proteins that are produced by a variety of cell types in multiple tissues. Under conditions of cell injury or death, IL-33 is passively released from the nucleus and acts as an "alarmin" upon binding to its specific receptor ST2, which leads to proinflammatory or anti-inflammatory effects depending on the pathological environment. To date, numerous studies have investigated the roles of IL-33 in human and murine models of diseases of the nervous system, digestive system, pulmonary system, as well as other organs and systems, including solid organ transplantation. With graft rejection and ischemia-reperfusion injury being the most common causes of grafted organ failure or dysfunction, researchers have begun to investigate the role of IL-33 in the immune-related mechanisms of graft tolerance and rejection using heart transplantation models. In the present review, we summarize the identified roles of IL-33 as well as the corresponding mechanisms by which IL-33 acts within the progression of graft rejection after heart transplantation in animal models.

MicroRNA-221 Is Cardioprotective and Anti-fibrotic in a Rat Model of Myocardial Infarction

Reduced myocardial miR-221 expression is associated with severe cardiac fibrosis in heart failure patients. We aimed to demonstrate its mechanisms in cardioprotection and remodeling following myocardial infarction (MI). Using in vitro hypoxia and reoxygenation (H/R) of H9c2 and rat cardiac fibroblast (cFB) models, we found that miR-221 protects H9c2 through combined anti-apoptotic and anti-autophagic effects and cFB via anti-autophagic effects alone in H/R. It inhibits myofibroblast (myoFB) activation as indicated by lowering α-smooth muscle actin (α-SMA) expression, gel contraction, and collagen synthesis (Sircol assay). In vivo, following left coronary artery ligation (MI), rats were treated with miR-221 mimics (intravenous [i.v.], 1 mg/kg). With treatment, miR-221 increased by ∼15-fold in infarct and peri-infarct zones at day 2 post-MI. At days 7 and 30 post-MI, miR-221 reduced infarct size, fibrosis, and α-SMA⁺ cells in both infarct and remote myocardium. Left ventricle (LV) function was preserved as indicated by ejection fraction, infarct thickness, LV developed pressure, ±dP/dt, and end diastolic pressure. We demonstrated the anti-apoptotic and anti-autophagic effects were due to combined mechanisms of direct targeting on Bak1 and P53 and inhibition of phosphorylation at Ser46 and direct targeting on Ddit4, respectively. miR-221 enhances cardiomyocyte survival and protects cardiac function post-MI. It enhances cFB survival yet inhibits their activation, thus reducing adverse cardiac fibrosis.

Human Mesenchymal Stem Cell-derived Exosomes Reduce Ischemia/Reperfusion Injury by the Inhibitions of Apoptosis and Autophagy

Background:

Human mesenchymal stem cell-derived exosomes (hMSC-Exo) have been shown to reduce ischemia/reperfusion injury (I/R) in multiple models. I/R-induced apoptosis or autophagy play important roles in cell death. However, little or no reports demonstrate any roles of hMSC-Exo in this regards. Objective: To test the hypothesis that the inhibition of I/R-induced apoptosis and autophagy play a pivotal role in the cardioprotection of hMSC-Exo.

Methods:

Myoblast H9c2 cells and isolated rat hearts underwent hypoxia/re-oxygenate (H/R) or ischemia/ reperfusion (I/R) respectively. H9c2 were treated with 1.0 μg/ml Exo, in comparison with 3-MA or rapamycin (Rapa), a known anti- or pro-autophagic agent respectively. Hearts were treated with 0.5, 1.0 and 2.0 μg/ml Exo for 20 min in the beginning of reperfusion. Cell viability, WST assay, LDH release, Annexin-V staining apoptosis assay and GFP-LC3 labeled autophagosomes formation, cardiac function and Western blot were measured.

Results:

Exo significantly reduced H/R injury as indicated by increased cell viability and reduced LDH and apoptosis. 3-MA, while Rapa, showed increased or decreased protective effects. Rapa-induced injury was partially blocked by Exo. Exo decreased LC3-II/I ratio and increased p62, inhibited autophagosome formation, an indication of autophagy inhibition. In isolated heart, Exo increased cardiac functional recovery and reduced LDH release in I/R. Bcl-2 was significantly upregulated by Exo but not 3-MA. Exo downregulated Traf6 and upregulated mTORC1/p-4eBP1.

Conclusion:

Exo reduce I/R-induced apoptosis and autophagy. Up-regulation of Bcl-2 is the cross-talk between these two processes. The down-regulation of Traf6 and activation of mTORC1 are additional mechanisms in the inhibition of apoptosis and autophagy.

Changes in Musculoskeletal System and Metabolism in Osteoporotic Rats Treated With Urocortin

Objective: In aging population, postmenopausal osteoporosis and decline of musculoskeletal function, referred to as "frailty syndrome" lead to loss of bone and muscle, causing falls, and fall-related injuries. To limit the impact of this portentous duo, simultaneous treatment of both is needed. Urocortin (UCN) has been reported to improve osteoporotic bone properties while its effect on muscle has not been addressed yet. Design and Methods: We aimed to investigate the effect of urocortin in vivo on skeletal muscle structure in osteopenic rats. Sixty Sprague-Dawley rats were divided into five groups: four were ovariectomized (OVX) and one underwent sham operation (SHAM). One ovariectomized group was left untreated (OVX), while one was treated with urocortin s.c. in 3 μg/kg body weight (bw) (OVX+UCN low), one with 30 μg/kg (OVX+UCN high), while one group was treated with estradiol orally (OVX+E: 0.2 mg/kg bw), each for 35 days. Mm. gastrocnemius, longissimus, and soleus were isolated and capillary density as well as diameters of type I and II fibers were measured. In addition, we examined the effect of UCN on tibia using biomechanical, micro-CT and ashing analysis and investigated the blood serum. Results: We demonstrated a positive effect of UCN on M. soleus, in which fiber diameter was positively influenced. The biomechanical and structural parameters of bone were not changed in UCN treated rats. The higher cholesterol, glucose and triglyceride levels in the "UCN high" group raise concern about this treatment. Conclusions: Our results portray urocortin as a substance that can be assessed for future therapeutic treatments of estrogen deficiency. New and Noteworthy: Urocortin has a positive effect on M. soleus (diameter). Urocortin raises serum cholesterol and triglyceride levels. Bone tissue was not affected by UCN.

Urocortin-2 improves right ventricular function and attenuates pulmonary arterial hypertension

Aims

Pulmonary arterial hypertension (PAH) is a devastating disease and treatment options are limited. Urocortin-2 (Ucn-2) has shown promising therapeutic effects in experimental and clinical left ventricular heart failure (HF). Our aim was to analyse the expression of Ucn-2 in human and experimental PAH, and to investigate the effects of human Ucn-2 (hUcn-2) administration in rats with monocrotaline (MCT)-induced pulmonary hypertension (PH).

Methods and results

Tissue samples were collected from patients with and without PAH and from rats with MCT-induced PH. hUcn-2 (5 μg/kg, bi-daily, i.p., for 10 days) or vehicle was administered to male wistar rats subjected to MCT injection or to pulmonary artery banding (PAB) to induce right ventricular (RV) overload without PAH. Expression of Ucn-2 and its receptor was increased in the RV of patients and rats with PAH. hUcn-2 treatment reduced PAH in MCT rats, resulting in decreased morbidity, improved exercise capacity and attenuated pulmonary arterial and RV remodelling and dysfunction. Additionally, RV gene expression of hypertrophy and failure signalling pathways were attenuated. hUcn-2 treatment also attenuated PAB-induced RV hypertrophy.

Conclusions

Ucn-2 levels are altered in human and experimental PAH. hUcn-2 treatment attenuates PAH and RV dysfunction in MCT-induced PH, has direct anti-remodelling effects on the pressure-overloaded RV, and improves pulmonary vascular function.

Differential gene expression profiles in peripheral blood in Northeast Chinese Han people with acute myocardial infarction

This study aimed to use gene chips to investigate differential gene expression profiles in the occurrence and development of acute myocardial infarction (AMI). The study included 12 AMI patients and 12 healthy individuals. Total mRNA of peripheral bloodwas extracted and reversed-transcribed to cDNA for microarray analysis. After establishing two pools with three subjects each (3 AMI patients and 3 healthy individuals), the remaining samples were used for RT-qPCR to confirm the microarray data. From the microarray results, seven genes were randomly selected for RT-qPCR. RT-qPCR results were analyzed by the 2^-ΔΔCt method. Microarray analysis showed that 228 genes were up- regulated and 271 were down-regulated (p ≤ 0.05, |logFC| > 1). Gene ontology showed that these genes belong to 128 cellular components, 521 biological processes, and 151 molecular functions. KEGG pathway analysis showed that these genes are involved in 107 gene pathways. RT-qPCR results for the seven genes showed expression levels consistent with those obtained by microarray. Thus, microarray data could be used to select the pathogenic genes for AMI. Investigating the abnormal expression of these differentially expressed genes might suggest efficient strategies for the prevention, diagnosis, and treatment of AMI.

Febuxostat Modulates MAPK/NF-κBp65/TNF-α Signaling in Cardiac Ischemia-Reperfusion Injury

Xanthine oxidase and xanthine dehydrogenase have been implicated in producing myocardial damage following reperfusion of an occluded coronary artery. We investigated and compared the effect of febuxostat and allopurinol in an experimental model of ischemia-reperfusion (IR) injury with a focus on the signaling pathways involved. Male Wistar rats were orally administered vehicle (CMC) once daily (sham and IR + control), febuxostat (10 mg/kg/day; FEB10 + IR), or allopurinol (100 mg/kg/day; ALL100 + IR) for 14 days. On the 15th day, the IR-control and treatment groups were subjected to one-stage left anterior descending (LAD) coronary artery ligation for 45 minutes followed by a 60-minute reperfusion. Febuxostat and allopurinol pretreatment significantly improved cardiac function and maintained morphological alterations. They also attenuated oxidative stress and apoptosis by suppressing the expression of proapoptotic proteins (Bax and caspase-3), reducing TUNEL-positive cells, and increasing the level of antiapoptotic proteins (Bcl-2). The MAPK-based molecular mechanism revealed suppression of active JNK and p38 proteins concomitant with the rise in ERK1/ERK2, a prosurvival kinase. Additionally, a reduction in the level of inflammatory markers (TNF-α, IL-6, and NF-κB) was also observed. The changes observed with febuxostat were remarkable in comparison with those observed with allopurinol. Febuxostat protects relatively better against IR injury than allopurinol by suppressing inflammation and apoptosis mediating the MAPK/NF-κBp65/TNF-α pathway.

Protective roles of bioactive peptides during ischemia-reperfusion injury: From bench to bedside

Ischemia-reperfusion (I/R) is a well-known pathological condition which may lead to disability and mortality. I/R injury remains an unresolved and complicated situation in a number of clinical conditions, such as cardiac arrest with successful reanimation, as well as ischemic events in brain and heart. Peptides have many attractive advantages which make them suitable candidate drugs in treating I/R injury, such as low toxicity and immunogenicity, good solubility property, distinct tissue distribution pattern, and favorable pharmacokinetic profile. An increasing number of studies indicate that peptides could protect against I/R injury in many different organs and tissues. Peptides also face several therapeutic challenges that limit their clinical application. In this review, we present the mechanisms of action of peptides in reducing I/R injury, as well as further discuss modification strategies to improve the functional properties of bioactive peptides.

Molecular Pathways Involved in the Amelioration of Myocardial Injury in Diabetic Rats by Kaempferol

There is growing evidence that chronic hyperglycemia leads to the formation of advanced glycation end products (AGEs) which exerts its effect via interaction with the receptor for advanced glycation end products (RAGE). AGE-RAGE activation results in oxidative stress and inflammation. It is well known that this mechanism is involved in the pathogenesis of cardiovascular disease in diabetes. Kaempferol, a dietary flavonoid, is known to possess antioxidant, anti-apoptotic, and anti-inflammatory activities. However, little is known about the effect of kaempferol on myocardial ischemia-reperfusion (IR) injury in diabetic rats. Diabetes was induced in male albino Wistar rats using streptozotocin (70 mg/kg; i.p.), and rats with glucose level >250 mg/dL were considered as diabetic. Diabetic rats were treated with vehicle (2 mL/kg; i.p.) and kaempferol (20 mg/kg; i.p.) daily for a period of 28 days and on the 28th day, ischemia was produced by one-stage ligation of the left anterior descending coronary artery for 45 min followed by reperfusion for 60 min. After completion of surgery, rats were sacrificed and the heart tissue was processed for biochemical, morphological, and molecular studies. Kaempferol pretreatment significantly reduced hyperglycemia, maintained hemodynamic function, suppressed AGE-RAGE axis activation, normalized oxidative stress, and preserved morphological alterations. In addition, there was decreased level of inflammatory markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and NF-κB), inhibition of active c-Jun N-terminal kinase (JNK) and p38 proteins, and activation of Extracellular signal regulated kinase 1/2 (ERK1/2) a prosurvival kinase. Furthermore, it also attenuated apoptosis by reducing the expression of pro-apoptotic proteins (Bax and Caspase-3), Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells, and increasing the level of anti-apoptotic protein (Bcl-2). In conclusion, kaempferol attenuated myocardial ischemia-reperfusion injury in diabetic rats by reducing AGE-RAGE/ mitogen activated protein kinase (MAPK) induced oxidative stress and inflammation.

The Combination of Three Components Derived from Sheng MaiSan Protects Myocardial Ischemic Diseases and Inhibits Oxidative Stress via Modulating MAPKs and JAK2-STAT3 Signaling Pathways Based on Bioinformatics Approach

GRS is a drug combination of three components including ginsenoside Rb1, ruscogenin and schisandrin. It derived from the well-known TCM formula Sheng MaiSan, a widely used traditional Chinese medicine for the treatment of cardiovascular diseases in clinic. The present study illuminates its underlying mechanisms against myocardial ischemic diseases based on the combined methods of bioinformatic prediction and experimental verification. A protein database was established through constructing the drug-protein network. And the target-pathway interaction network clustered the potential signaling pathways and targets of GRS in treatment of myocardial ischemic diseases. Several target proteins, such as NFKB1, STAT3 and MAPK14, were identified as the candidate key proteins, and MAPKs and JAK-STAT signaling pathway were suggested as the most related pathways, which were in accordance with the gene ontology analysis. Then, the predictive results were further validated and we found that GRS treatment alleviated hypoxia/reoxygenation (H/R)-induced cardiomyocytes injury via suppression of MDA levels and ROS generation, and potential mechanisms might related to the suppression of activation of MAPKs and JAK2-STAT3 signaling pathways. Conclusively, our results offer the evidence that GRS attenuates myocardial ischemia injury via regulating oxidative stress and MAPKs and JAK2-STAT3 signaling pathways, which supplied some new insights for its prevention and treatment of myocardial ischemia diseases.

Kaempferol Attenuates Myocardial Ischemic Injury via Inhibition of MAPK Signaling Pathway in Experimental Model of Myocardial Ischemia-Reperfusion Injury

Kaempferol (KMP), a dietary flavonoid, has antioxidant, anti-inflammatory, and antiapoptotic effects. Hence, we investigated the effect of KMP in ischemia-reperfusion (IR) model of myocardial injury in rats. We studied male albino Wistar rats that were divided into sham, IR-control, KMP-20 + IR, and KMP 20 per se groups. KMP (20 mg/kg; i.p.) was administered daily to rats for the period of 15 days, and, on the 15th day, ischemia was produced by one-stage ligation of left anterior descending coronary artery for 45 min followed by reperfusion for 60 min. After completion of surgery, rats were sacrificed; heart was removed and processed for biochemical, morphological, and molecular studies. KMP pretreatment significantly ameliorated IR injury by maintaining cardiac function, normalizing oxidative stress, and preserving morphological alterations. Furthermore, there was a decrease in the level of inflammatory markers (TNF-α, IL-6, and NFκB), inhibition of active JNK and p38 proteins, and activation of ERK1/ERK2, a prosurvival kinase. Additionally, it also attenuated apoptosis by reducing the expression of proapoptotic proteins (Bax and Caspase-3), TUNEL positive cells, and increased level of antiapoptotic proteins (Bcl-2). In conclusion, KMP protected against IR injury by attenuating inflammation and apoptosis through the modulation of MAPK pathway.

Urocortin-1 Mediated Cardioprotection Involves XIAP and CD40-Ligand Recovery: Role of EPAC2 and ERK1/2

Aims

Urocortin-1 (Ucn-1) is an endogenous peptide that protects heart from ischemia and reperfusion (I/R) injuries. Ucn-1 is known to prevent cardiac cell death, but its role in the transcription of specific genes related to survival signaling pathway has not been fully defined. The aim of this study was to investigate the molecular signaling implicated in the improvement of cardiac myocytes survival induced by Ucn-1.

Methods and Results

Ucn-1 administration before ischemia and at the onset of reperfusion, in rat hearts perfused in Langendorff system, fully recovered heart contractility and other hemodynamic parameters. Ucn-1 enhanced cell viability and decreased lactate dehydrogenase (LDH) release in adult cardiac myocytes subjected to simulated I/R. Annexin V-FITC/PI staining indicated that Ucn-1 promoted cell survival and decreased cell necrosis through Epac2 (exchange protein directly activated by cAMP) and ERK1/2 (extracellular signal–regulated kinases 1/2) activation. We determined that Ucn-1 shifted cell death from necrosis to apoptosis and activated caspases 9 and 3/7. Furthermore, mini-array, RT-qPCR and protein analyses of apoptotic genes showed that Ucn-1 upregulated the expression of CD40lg, Xiap and BAD in cells undergoing I/R, involving Epac2 and ERK1/2 activation.

Conclusions

Our data indicate that Ucn-1 efficiently protected hearts from I/R damage by increasing the cell survival and stimulated apoptotic genes, CD40lg, Xiap and BAD, overexpression through the activation of Epac2 and ERK1/2.

The Protective Role of Interleukin-33 in Myocardial Ischemia and Reperfusion Is Associated with Decreased HMGB1 Expression and Up-Regulation of the P38 MAPK Signaling Pathway

Interleukin-33 (IL-33) plays a protective role in myocardial ischemia and reperfusion (I/R) injury, but the underlying mechanism was not fully elucidated. The present study was designed to investigate whether IL-33 protects against myocardial I/R injury by regulating both P38 mitogen-activated-protein kinase (P38 MAPK), which is involved in one of the downstream signaling pathways of IL-33, and high mobility group box protein 1 (HMGB1), a late pro-inflammatory cytokine. Myocardial I/R injury increased the level of IL-33 and its induced receptor (sST) in myocardial tissue. Compared with the I/R group, the IL-33 group had significantly lower cardiac injury (lower serum creatine kinase (CK), lactate dehydrogenase (LDH), and cTnI levels and myocardial infarct size), a suppressed inflammatory response in myocardial tissue (lower expression of HMGB1, IL-6, TNF-α and INF-γ) and less myocardial apoptosis (much higher Bcl-2/Bax ratio and lower cleaved caspase-3 expression). Moreover, IL-33 activated the P38 MAPK signaling pathway (up-regulating P-P38 expression) in myocardial tissue, and SB230580 partially attenuated the anti-inflammatory and anti-apoptosis effects of IL-33. These findings indicated that IL-33 protects against myocardial I/R injury by inhibiting inflammatory responses and myocardial apoptosis, which may be associated with the HMGB1 and P38 MAPK signaling pathways.

Discovery of Potential Therapeutic miRNA Targets in Cardiac Ischemia-Reperfusion Injury

BACKGROUND

A highly efficient approach to select microRNA (miRNA) targets is a key to develop a miRNA-based therapeutic approach to cardiac ischemia-reperfusion (I/R). To reverse the change induced by disease, I/R in this case, is the traditional strategy to develop therapeutic drugs. However, examples show that it will not always serve the purpose. In this study, we demonstrate an additional approach of selecting miRNA targets with therapeutic potential following cues from cardioprotection-induced changes rather than by reversing disease-induced changes in cardiac I/R.

METHODS

Isolated perfused rat hearts subjected to I/R were treated with 50 μmol/L sodium hydrosulfide (NaHS) or 10 nmol/L urocortin 2 (UCN2). Cardiac miRNA regulations were determined by miRNA array. Functional screening of selected miRNA mimics, assessed by WST (2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt) activity and lactate dehydrogenase (LDH) release, was performed in H9c2 and neonatal rat ventricular myocytes (NRVMs) with hypoxia/reoxygenation. RNA-induced silencing complex (RISC)-loaded miRNAs caused by mimic transfection were quantified following argonaute-2 immunoprecipitation. Gene regulations of 1 selected miRNA were determined by quantitative polymerase chain reaction and Western blot.

RESULTS

Treatment with NaHS and UCN2 significantly improved cardiac function and reduced LDH release. The miRNA array indicated a panel of commonly up- and downregulated miRNAs. Among them, 10 upregulated miRNAs with antiapoptotic and antiautophagy potentials were selected for further screening. Mimics of miRNA-221, -150, and -206 were protective in both H9c2 and NRVM. RISC-loaded miRNAs were up by ∼20-fold above. To further prove the feasibility of this approach, miRNA-221 was studied. It reduced I/R-induced caspase 3/7 activity and LC3-II (microtubule-associated protein 1 light chain 3). Measuring genes predicted to regulate apoptosis and autophagy, miRNA-221 mimic decreased Ddit4, TP53inp1, and p27 at both messenger RNA (mRNA) and protein levels, and reduced mRNA of Bak1 and Puma and proteins of Bim and Bmf.

CONCLUSION

Mimicking miRNA changes caused by cardioprotective agents, combined with functional screening, enables investigators to efficiently identify novel miRNAs with therapeutic potential in cardiac I/R.

Urocortin 2 in cardiovascular health and disease

Urocortin (Ucn)-2 - corticotropin-releasing hormone receptor 2 signaling has favorable effects in the cardiovascular system, including coronary vasodilatation, with increased coronary blood flow and conductance and augmented cardiac contractility and output, as well as protection against ischemia/reperfusion injury. Indeed, several animal studies have confirmed the salutary therapeutic effects of Ucn-2 in chronic heart failure, with improvements in cardiac performance and animal survival. In addition, recent clinical trials have demonstrated the benefits of Ucn-2 in patients with stable chronic heart failure on optimal medical therapy.