Thaliporphine ameliorates cardiac depression in endotoxemic rats through attenuating TLR4 signaling in the downstream of TAK-1 phosphorylation and NF-κB signaling

Salidroside ameliorates pathological cardiac hypertrophy via TLR4-TAK1-dependent signaling

Salidroside, a prominent active ingredient in traditional Chinese medicines, is garnering increased attention because of its unique pharmacological effects against ischemic heart disease via MAPK signaling, which plays a critical role in regulating the evolution of ventricular hypertrophy. However, the function of Salidroside on myocardial hypertrophy has not yet been elucidated. C57BL/6 mice were subjected to transverse aortic constriction (TAC), and treated with Salidroside (100 mg kg-1  day-1 ) by oral gavage for 3 weeks starting 1 week after surgery. Four weeks after TAC surgery, the mice were subjected to echocardiography and then sacrificed to harvest the hearts for analysis. For in vitro study, neonatal rat cardiomyocytes were used to validate the protective effects of Salidroside in response to Angiotensin II (Ang II, 1 μM) stimulation. Here, we proved that Salidroside dramatically inhibited hypertrophic reactions generated by pressure overload and isoproterenol (ISO) injection. Salidroside prevented the activation of the TAK1-JNK/p38 axis. Salidroside pretreatment of TAK1-inhibited cardiomyocytes shows no additional attenuation of Ang II-induced cardiomyocytes hypertrophy and signaling pathway activation. The overexpression of constitutively active TAK1 removed the protective effects of Salidroside on myocardial hypertrophy. TAC-induced increase of TLR4 protein expression was reduced considerably in the Salidroside treated mice. Transient transfection of small interfering RNA targeting TLR4 (siTLR4) in cardiomyocytes did not further decrease the activation of the TAK1/JNK-p38 axis. In conclusion, Salidroside functioned as a TLR4 inhibitor and displayed anti-hypertrophic action via the TAK1/JNK-p38 pathway.

Epoxyeicosatrienoic acids prevent cardiomyocytes against sepsis by A2AR-induced activation of PI3K and PPARγ

Although epoxyeicosatrienoic acids (EETs) have multiple protective effects against different diseases, whether they can improve the pathogenesis of lipopolysaccharide (LPS)-induced septic cardiac dysfunction remains unknown. We investigated the effects of EETs on the LPS-induced inflammatory response in myocardial dysfunction mice and H9c2 cardiac myocytes. Cardiac-specific CYP2J2 transgenic mice (Tr) showed improved cardiac function and reduced inflammation response after administration with LPS, while the protective effects were not observed in A_2A adenosine receptor (A_2AR/ADORA2A)-deficient mice (knockout/KO). In vitro, EETs prevented LPS-induced inflammation and apoptosis in the cardiomyocytes via A_2AR activation. Moreover, ZM241385 (A_2AR inhibitor) attenuated the cardioprotective properties of EETs. Further investigation demonstrated that A_2AR signal pathway activation partly regulated phosphatidylinositol 3-kinase (PI3K) and peroxisome proliferator-activated receptor-γ (PPARγ) expression. This is the first report on EETs exerting cardioprotective effects against LPS-induced cardiomyocyte injury via A_2AR activation.

Electroacupuncture Pretreatment as a Novel Avenue to Protect Heart against Ischemia and Reperfusion Injury

In recent years, the efficacy of electroacupuncture (EA) pretreatment generating ischemic tolerance mimicking ischemic pretreatment (IP) has been continuously confirmed, which was first found in the brain and then in the heart. Furthermore, researchers have observed the intensive cardioprotection impact of EA pretreatment on patients undergoing percutaneous coronary intervention (PCI) and heart valve replacement, indicating that EA pretreatment tends to be a valuable and advantageous avenue for preventing acute myocardial ischemia/reperfusion (I/R) injury or treatment of ischemic heart disease (IHD). In reality, the heart protection mechanism of EA pretreatment is robust and pleiotropic, of which the regulatory molecular pathways are involved in multichannel, multilevel, and multitarget, including energy metabolism, inflammatory response, calcium overload, oxidative stress, autophagy, and apoptosis. Through a growing number of clinical tests and basic experiments with animal models, researchers progressively explored the optimal acupoints and parameters, where EA pretreatment induced acute and delayed ischemic tolerance for myocardial protection. Thereby, this article aims to collect the relevant evidence on EA pretreatment against myocardial ischemia/reperfusion injury (MIRI) and summarize the mechanism of cardioprotection of EA pretreatment to provide ideas and methods for further clinical applications.

A novel isoquinoline derivative exhibits anti-inflammatory properties and improves the outcomes of endotoxemia

BACKGROUND

Sepsis initiates an inflammatory response that causes widespread injury, and candidates for related myocardial depressant factors include cytokines and nitric oxide (NO). Nuclear factor kappa-B (NF-κB) stimulated by toll-like receptor 4 activation in sepsis mediates the transcription of multiple proinflammatory genes. These inflammatory mediators can cause myocardial dysfunction, which may deteriorate sepsis outcomes. To address this risk, we investigated the potential beneficial effects of a novel isoquinolines derivative, CYY054c, in LPS-induced inflammatory response leading to endotoxemia.

METHODS

The effects of CYY054c on cytokine and inflammatory-related protein production were evaluated in lipopolysaccharide (LPS)-stimulated macrophages. To determine whether CYY054c alleviates inflammatory storm-induced myocardial dysfunction in vivo, LPS was injected in rats, and cardiac function was measured by a pressure-volume loop.

RESULTS

CYY054c inhibited LPS-induced NF-κB expression in macrophages and reduced the release of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), as well as the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In the animal studies, CYY054c alleviated LPS-upregulated plasma TNF-α, IL-1β, IL-6, and NO concentrations, as well as cardiac monocyte chemotactic protein-1, iNOS, and COX-2 expression in rats, contributing to the improvement of cardiac function during endotoxemia.

CONCLUSIONS

The reduction of NF-κB-mediated inflammatory mediators and the maintenance of hemodynamic performance by CYY054c improved the outcomes during endotoxemia. CYY054c may be a potential therapeutic agent for sepsis.

Enterohemorrhagic Escherichia coli Tir inhibits TAK1 activation and mediates immune evasion

Many pathogens infect hosts through various immune evasion strategies. However, the molecular mechanisms by which pathogen proteins modulate and evade the host immune response remain unclear. Enterohemorrhagic Escherichia coli (EHEC) is a pathological strain that can induce mitogen-activated protein (MAP) kinase (Erk, Jnk and p38 MAPK) and NF-κB pathway activation and proinflammatory cytokine production, which then causes diarrheal diseases such as hemorrhagic colitis and hemolytic uremic syndrome. Transforming growth factor β-activated kinase-1 (TAK1) is a key regulator involved in distinct innate immune signalling pathways. Here we report that EHEC translocated intimin receptor (Tir) protein inhibits the expression of EHEC-induced proinflammatory cytokines by interacting with the host tyrosine phosphatase SHP-1, which is dependent on the phosphorylation of immunoreceptor tyrosine-based inhibition motifs (ITIMs). Mechanistically, the association of EHEC Tir with SHP-1 facilitated the recruitment of SHP-1 to TAK1 and inhibited TAK1 phosphorylation, which then negatively regulated K63-linked polyubiquitination of TAK1 and downstream signal transduction. Taken together, these results suggest that EHEC Tir negatively regulates proinflammatory responses by inhibiting the activation of TAK1, which is essential for immune evasion and could be a potential target for the treatment of bacterial infection.

Calcitonin Gene-Related Peptide Improves Hypoxia-Induced Inflammation and Apoptosis via Nitric Oxide in H9c2 Cardiomyoblast Cells

OBJECTIVES

The aim of this work was to investigate whether calcitonin gene-related peptide (CGRP) plays a protective role in cardiomyocytes against hypoxia-induced inflammation and apoptosis via an NO-mediated pathway.

METHODS

H9c2 cardiac cells were exposed to hypoxia for 2 h to establish a model of myocardial hypoxic-ischemic injury. The cells were pretreated with either CGRP or nitric oxide synthase (NOS) inhibitor (L-NAME) before being exposed to hypoxia for 30 min. Cell viability was analyzed using a cell counter kit 8 (CCK-8). The levels of IL-6 and TNF-α were determined by the corresponding enzyme-linked immunosorbent assay. The expression levels of several apoptosis proteins (p53, caspase-3, cytochrome C) and NOS were detected by Western blot assays. An NO kit was used to evaluate the production of NO.

RESULTS

Pretreatment of H9c2 cardiac cells with CGRP for 30 min prior to exposure to hypoxia markedly improved cell viability (83.57 ± 3.21 vs. 62.83 ± 8.30%, p < 0.001); the same effect was observed following pretreatment with the NOS inhibitor L-NAME (89.34 ± 5.95 vs. 75.01 ± 5.61%, p < 0.01). Pretreatment with CGRP also significantly attenuated the inflammatory responses induced by hypoxia, as evidenced by decreases of the levels of both IL-6 (193.21 ± 13.54 vs. 293.38 ± 56.49%, p < 0.001) and TNF-α (207.71 ± 44.27 vs. 281.46 ± 64.88%, p < 0.001). Additionally, CGRP significantly decreased the hypoxia-induced overexpression of the apoptotic proteins (p53: 0.27 ± 0.10 vs. 0.87 ± 0.30, p < 0.001; caspase-3: 0.65 ± 0.15 vs. 0.98 ± 0.26, p < 0.001; cytochrome C: 1.51 ± 0.39 vs. 2.80 ± 0.69, p < 0.001) and enhanced the expression of both endothelial NOS (eNOS; 0.59 ± 0.24 vs. 0.37 ± 0.14, p < 0.05) and phosphorylated eNOS (0.60 ± 0.13 vs. 0.40 ± 0.07, p < 0.05). Furthermore, the application of both L-NAME and CGRP attenuated the hypoxia-induced expression of inducible NOS (iNOS; p < 0.05) and enhanced a hypoxia-mediated decrease in NO (p < 0.01). Interestingly, the expression levels of cell apoptosis (p < 0.05), iNOS and eNOS (p < 0.05) were decreased with L-NAME and CGRP cotreatment following 2 h of acute hypoxia, but the apoptotic factors (p < 0.05) were increased compared with only CGRP pretreatment.

CONCLUSION

CGRP protects cardiomyocytes from hypoxia-induced inflammation and apoptosis by modulating NO production.

Verbascoside down-regulates some pro-inflammatory signal transduction pathways by increasing the activity of tyrosine phosphatase SHP-1 in the U937 cell line

Polyphenols are the major components of many traditional herbal remedies, which exhibit several beneficial effects including anti-inflammation and antioxidant properties. Src homology region 2 domain-containing phosphatase-1 (SHP-1) is a redox sensitive protein tyrosine phosphatase that negatively influences downstream signalling molecules, such as mitogen-activated protein kinases, thereby inhibiting inflammatory signalling induced by lipopolysaccharide (LPS). Because a role of transforming growth factor β-activated kinase-1 (TAK1) in the upstream regulation of JNK molecule has been well demonstrated, we conjectured that SHP-1 could mediate the anti-inflammatory effect of verbascoside through the regulation of TAK-1/JNK/AP-1 signalling in the U937 cell line. Our results demonstrate that verbascoside increased the phosphorylation of SHP-1, by attenuating the activation of TAK-1/JNK/AP-1 signalling. This leads to a reduction in the expression and activity of both COX and NOS. Moreover, SHP-1 depletion deletes verbascoside inhibitory effects on pro-inflammatory molecules induced by LPS. Our data confirm that SHP-1 plays a critical role in restoring the physiological mechanisms of inducible proteins such as COX2 and iNOS, and that the down-regulation of TAK-1/JNK/AP-1 signalling by targeting SHP-1 should be considered as a new therapeutic strategy for the treatment of inflammatory diseases.

TM-1-1DP exerts protective effect against myocardial ischemia reperfusion injury via AKT-eNOS pathway

Coronary heart disease remains a leading cause of death in the world. The demand on targeting therapy to reduce myocardial ischemia/reperfusion (I/R) injury is still urgent. The pathogenesis of I/R-induced myocardial injury is complicated. Reactive oxygen species (ROS) generation and inflammatory response activation participate in the development of I/R injury. Cell death occurs and finally leads to myocardial infarction. A newly phenolic aporphine alkaloid derivative, TM-1-1DP, was synthesized in our team. We aimed to investigate the effect of novel compound on myocardial I/R injury. Rats were subjected to 1-h coronary artery occlusion and followed by 2-h reperfusion. Adult rat cardimoycyte was isolated for the cell study, and H2O2 was added into culture medium to induce ROS stress. As compared to the sham group, TM-1-1DP-treated rats had better cardiac performance in association with less infarct size and cardiac injury markers after myocardial I/R. The protective effect is associated with the inhibition of inflammatory response, cell death-related pathway (caspase-3 and TNF-α), and the activation of AKT-eNOS pathway. The finding was further coincided with the cell study. TM-1-1DP treatment significantly alleviated ROS production and improved cell viability in cardiomyocyte after H2O2 exposure. The action of TM-1-1DP is via a nitric oxide (NO)-dependent manner, since NOS inhibitor, L-NAME, abolished the protective effect. We provide a new insight into this therapeutic potential for phenolic aporphine alkaloid in myocardial I/R.

Caffeic acid phenethyl amide ameliorates ischemia/reperfusion injury and cardiac dysfunction in streptozotocin-induced diabetic rats

BACKGROUND

Caffeic acid phenethyl ester (CAPE) has been shown to protect the heart against ischemia/reperfusion (I/R) injury by various mechanisms including its antioxidant effect. In this study, we evaluated the protective effects of a CAPE analog with more structural stability in plasma, caffeic acid phenethyl amide (CAPA), on I/R injury in streptozotocin (STZ)-induced type 1 diabetic rats.

METHODS

Type 1 diabetes mellitus was induced in Sprague-Dawley rats by a single intravenous injection of 60 mg/kg STZ. To produce the I/R injury, the left anterior descending coronary artery was occluded for 45 minutes, followed by 2 hours of reperfusion. CAPA was pretreated intraperitoneally 30 minutes before reperfusion. An analog devoid of the antioxidant property of CAPA, dimethoxyl CAPA (dmCAPA), and a nitric oxide synthase (NOS) inhibitor (Nω-nitro-l-arginine methyl ester [l-NAME]) were used to evaluate the mechanism involved in the reduction of the infarct size following CAPA-treatment. Finally, the cardioprotective effect of chronic treatment of CAPA was analyzed in diabetic rats.

RESULTS

Compared to the control group, CAPA administration (3 and 15 mg/kg) significantly reduced the myocardial infarct size after I/R, while dmCAPA (15 mg/kg) had no cardioprotective effect. Interestingly, pretreatment with a NOS inhibitor, (L-NAME, 3 mg/kg) eliminated the effect of CAPA on myocardial infarction. Additionally, a 4-week CAPA treatment (1 mg/kg, orally, once daily) started 4 weeks after STZ-induction could effectively decrease the infarct size and ameliorate the cardiac dysfunction by pressure-volume loop analysis in STZ-induced diabetic animals.

CONCLUSIONS

CAPA, which is structurally similar to CAPE, exerts cardioprotective activity in I/R injury through its antioxidant property and by preserving nitric oxide levels. On the other hand, chronic CAPA treatment could also ameliorate cardiac dysfunction in diabetic animals.

DPP4 deficiency preserved cardiac function in abdominal aortic banding rats

Dipeptidyl peptidase-4 (DPP4) enzyme inhibition has been reported to increase plasma glucagon-like peptide-1 (GLP-1) level for controlling postprandial glucose concentration. A prominent GLP-1 level in DPP4-deficient rats contributed to the resistance of endotoxemia and myocardial infarction. DPP4 deficiency also increased the capability against H₂O₂-induced stress in cardiomyocyte. However, long term effect of loss DPP4 activity on cardiac performance remained unclear. We used abdominal aortic banding (AAB) to induce pressure overload in wild-type and DPP4-deficient rats, and investigated the progression of heart failure. Cardiac histology and function were determined. Blood sample was collected for the plasma biochemical marker measurement. Heart weight to body weight ratio increased 1.2-fold after 6 weeks of AAB surgery. Cardiac function was compensated against pressure overload after 6 weeks of AAB surgery, but progressed to deterioration after 10 weeks of AAB surgery. AAB induced cardiac dysfunction was alleviated in DPP4-deficient rats. DPP4 activity increased significantly in wild-type rats after 10 weeks of AAB surgery, but remained unchanged in DPP4-deficient rats. In contrast, GLP-1 concentration was elevated by AAB after 6 weeks of surgery in DPP4-deficient rats, and remained high after 10 weeks of surgery. Ang II level markedly increased after 6 weeks of AAB surgery, but were less in DPP4-deficient rats. Massive collagen deposits in wild-type rat hearts appeared after 10 weeks of AAB surgery, which were alleviated in DPP4-deficient rats. Long term deficiency of DPP4 activity improved cardiac performance against pressure overload in rat, which may be attributed to a great quantity of GLP-1 accumulation during AAB.

TNF-α neutralization improves experimental hepatopulmonary syndrome in rats

BACKGROUND/AIM

TNF-α is increased in hepatopulmonary syndrome (HPS). Pentoxifylline (PTX) mitigated experimental HPS through the inhibition of TNF-α. However, PTX has pleiotropic effects besides the inhibition of TNF-α. This study is to neutralize TNF-α with specific monoclonal antibody to TNF-α (TNF-α McAb) to investigate the effect of TNF-α on HPS.

MATERIALS AND METHODS

Hepatopulmonary syndrome was induced by common bile duct ligation (CBDL); controls were sham operated. The endpoints were 1, 2, 3, 4 and 5 weeks after surgery. (99m) Technetium-macroaggregated albumin (Tc-MAA) was to evaluate intrapulmonary arteriovenous shunts; Portal venous pressure, cardiac output and mean blood pressure (MAP) were also measured. Serum was for Alanine transaminase (ALT), endotoxin, TNF-α and nitric oxide (NO) measurements, liver for histology, lung for histology and iNOS, PI3K/Akt expression assay.

RESULTS

Portal vein pressure was significantly elevated and MAP decreased in CBDL rats. Tc-MAA was mainly located in lung and very weak in brain in sham group and mainly in brain of CBDL rats. TNF-α McAb significantly decreased the radioactivity in the brain, reduced cardiac output, increased MAP and systemic vascular resistance (SVR) in CBDL animals. Serum ALT, endotoxin, TNF-α and NO were significantly increased. TNF-α McAb significantly decreased these serum indices in CBDL rats. TNF-α McAb significantly alleviated liver damage, decreased alveolar-arterial gradient and inhibited iNOS, PI3K/Akt and p-Akt expression in lung tissue. Furthermore, TNF-α McAb significantly attenuated the inflammatory response in lung.

CONCLUSION

TNF-α McAb improves HPS in cirrhotic rats; this effect is likely mediated through the inhibition of TNF-α PI3K/Akt-NO pathway.

Thaliporphine preserves cardiac function of endotoxemic rabbits by both directly and indirectly attenuating NFκB signaling pathway

Cardiac depression in sepsis is associated with the increased morbidity and mortality. Although myofilaments damage, autonomic dysfunction, and apoptosis play roles in sepsis-induced myocardial dysfunction, the underlying mechanism is not clear. All of these possible factors are related to NFκB signaling, which plays the main role in sepsis signaling. Thaliporphine was determined to possess anti-inflammatory and cardioprotective activity by suppressing NFκB signaling in rodents. The purpose of this study is to further prove this protective effect in larger septic animals, and try to find the underlying mechanisms. The systolic and diastolic functions were evaluated in vivo by pressure-volume analysis at different preloads. Both preload-dependent and -independent hemodynamic parameters were performed. Inflammatory factors of whole blood and serum samples were analyzed. Several sepsis-related signaling pathways were also determined at protein level. Changes detected by conductance catheter showed Thaliporphine could recover impaired left ventricular systolic function after 4 hours LPS injection. It could also reverse the LPS induced steeper EDPVR and gentler ESPVR, thus improve Ees, Ea, and PRSW. Thaliporphine may exert this protective effect by decreasing TNFα and caspase3 dependent cell apoptosis, which was consistent with the decreased serum cTnI and LDH concentration. Thaliporphine could protect sepsis-associated myocardial dysfunction in both preload-dependent and -independent ways. It may exert these protective effects by both increase of "good"-PI3K/Akt/mTOR and decrease of "bad"-p38/NFκB pathways, which followed by diminishing TNFα and caspase3 dependent cell apoptosis.