Ghrelin prevents doxorubicin-induced cardiotoxicity through TNF-alpha/NF-κB pathways and mitochondrial protective mechanisms

Role of Oxidative Stress and Inflammation in Doxorubicin-Induced Cardiotoxicity: A Brief Account

Cardiotoxicity is the main side effect of several chemotherapeutic drugs. Doxorubicin (Doxo) is one of the most used anthracyclines in the treatment of many tumors, but the development of acute and chronic cardiotoxicity limits its clinical usefulness. Different studies focused only on the effects of long-term Doxo administration, but recent data show that cardiomyocyte damage is an early event induced by Doxo after a single administration that can be followed by progressive functional decline, leading to overt heart failure. The knowledge of molecular mechanisms involved in the early stage of Doxo-induced cardiotoxicity is of paramount importance to treating and/or preventing it. This review aims to illustrate several mechanisms thought to underlie Doxo-induced cardiotoxicity, such as oxidative and nitrosative stress, inflammation, and mitochondrial dysfunction. Moreover, here we report data from both in vitro and in vivo studies indicating new therapeutic strategies to prevent Doxo-induced cardiotoxicity.

Leflunomide-induced cardiac injury in adult male mice and bioinformatic approach identifying Nrf2/NF-κb signaling interplay

Leflunomide (LFND) is an immunosuppressive and immunomodulatory disease-modifying antirheumatic drug (DMARD) that was approved for treating rheumatoid arthritis. LFND-induced cardiotoxicity was not fully investigated since its approval. We investigated the cardiac injury in male mice and identified the role of nuclear factor erythroid 2-related factor 2/nuclear factor-κ B (Nrf2/NF-κB) signaling. Male albino mice were assigned into five groups as control, vehicle, and LFND (2.5, 5, and 10 mg/kg). We investigated cardiac enzymes, histopathology, and the mRNA expression of Nrf2, NF-κB, BAX, and tumor necrosis factor-α (TNF-α). The bioinformatic study identified the interaction between LFND and Nrf2/NF-κB signaling; this was confirmed by amelioration in mRNA expression (0.5- to 0.34-fold decrease in Nrf2 and 2.6- to 4.61-fold increases in NF-κB genes) and increased (1.76- and 2.625-fold) serum creatine kinase (CK) and 1.38- and 2.33-fold increases in creatine kinase-MB (CK-MB). Histopathological results confirmed the dose-dependent effects of LFND on cardiac muscle structure in the form of cytoplasmic, nuclear, and vascular changes in addition to increased collagen deposits and apoptosis which were increased compared to controls especially with LFND 10 mg/kg. The current study elicits the dose-dependent cardiac injury induced by LFND administration and highlights, for the first time, dysregulation in Nrf2/NF-κB signaling.

Sex-related differences in delayed doxorubicin-induced cardiac dysfunction in C57BL/6 mice

Cancer survivors may experience long-term cardiovascular complications due to chemotherapeutic drugs such as doxorubicin (DOX). The exact mechanism of delayed DOX-induced cardiotoxicity has not been fully elucidated. Sex is an important risk factor for DOX-induced cardiotoxicity. In the current study, we identified sex differences in delayed DOX-induced cardiotoxicity and determined the underlying molecular determinants of the observed sexual dimorphism. Five-week-old male and female mice were administered intraperitoneal injections of DOX (4 mg/kg/week) or saline for 6 weeks. Echocardiography was performed 5 weeks after the last dose of DOX to evaluate cardiac function. Thereafter, mice were sacrificed and gene expression of markers of apoptosis, senescence, and inflammation was measured by PCR in hearts and livers. Proteomic profiling of the heart from both sexes was conducted to determine differentially expressed proteins (DEPs). Only DOX-treated male, but not female, mice demonstrated cardiac dysfunction, cardiac atrophy, and upregulated cardiac expression of Nppb and Myh7. No sex-related differences were observed in DOX-induced expression of most apoptotic, senescence, and pro-inflammatory markers. However, the gene expression of Trp53 was significantly reduced in hearts of DOX-treated female mice only. The anti-inflammatory marker Il-10 was significantly reduced in hearts of DOX-treated male mice only, while the pro-inflammatory marker Il-1α was significantly reduced in livers of DOX-treated female mice only. Gene expression of Tnf-α was reduced in hearts of both DOX-treated male and female mice. Proteomic analysis identified several DEPs after DOX treatment in a sex-specific manner, including anti-inflammatory acute phase proteins. This is the first study to assess sex-specific proteomic changes in a mouse model of delayed DOX-induced cardiotoxicity. Our proteomic analysis identified several sexually dimorphic DEPs, many of which are associated with the anti-inflammatory marker Il-10.

The Essential Strategies to Mitigate Cardiotoxicity Caused by Doxorubicin

The study of mechanisms underlying cardiotoxicity of doxorubicin and the development of strategies to mitigate doxorubicin-induced cardiotoxicity are the most relevant issues of modern cardio-oncology. This is due to the high prevalence of cancer in the population and the need for frequent use of highly effective chemotherapeutic agents, in particular anthracyclines, for optimal management of cancer patients. However, while being a potent agent to counteract cancer, doxorubicin also affects the cardiovascular systems of patients undergoing chemotherapy in a significant and unfavorable fashion. Consecutively reviewed in this article are risk factors and mechanisms of doxorubicin cardiotoxicity, and the essential strategies to mitigate cardiotoxic effects of doxorubicin treatment in cancer patients are discussed.

Promoting mitochondrial fusion in doxorubicin-induced cardiotoxicity: a novel therapeutic target for cardioprotection

Changes in mitochondrial dynamics have been recognized as being one of the mechanisms related to cardiotoxicity following a high cumulative dose of doxorubicin (DOX).  A mitochondrial division inhibitor (Mdivi-1) and fusion promoter (M1) have been shown to be cardioprotective in a variety of cardiovascular settings, however their anti-cardiotoxic efficacy against DOX therapy remains unclear.  We therefore investigated whether treatment with Mdivi-1 and M1 protect the heart against DOX-induced cardiotoxicity via mitochondria-targeted pathways.  Male Wistar rats (n=40) received DOX (3 mg/kg, 6 doses, n=32) or 3% DMSO in the normal saline solution (NSS) (n=8) as a control.  DOX-injected rats were given one of four treatments beginning with the first DOX injection via intraperitoneal injection: 1) 3% DMSO in NSS (n=8), 2) Mdivi-1 (1.2 mg/kg/day, n=8), 3) M1 (2 mg/kg/day, n=8), and 4) Mdivi-1+M1 (n=8) for 30 days.  Cardiac function, mitochondrial function, oxidative stress, myocardial injury, and protein expression associated with inflammation, autophagy, mitophagy, apoptosis and mitochondrial dynamics were determined.  DOX caused a significant deterioration in mitochondrial function and dynamic regulation, and an increase in markers of oxidative stress, inflammation, myocardial injury, apoptosis, autophagy, and mitophagy, resulting in impaired cardiac function.  Co-treatment of DOX with Mdivi-1, M1, or a combination of the two mitigated these detrimental effects of DOX.  These findings imply that either inhibiting fission or promoting fusion of mitochondria protects the heart from DOX-induced myocardial damage.  Modulation of mitochondrial dynamics could be a novel therapeutic target in alleviating DOX-induced cytotoxic effects without compromising its anti-cancer efficacy.

Saikosaponin D alleviates DOX-induced cardiac injury in vivo and in vitro

ABSTRACT

As a highly efficient anticancer agent, Doxorubicin (DOX) is used for various cancers' treatment, but DOX-induced oxidative damages contribute to a degenerative irreversible cardiac toxicity. Saikosaponin D (SSD), which is a triterpenoid saponin with many biological activities including anti-inflammatory effects and antioxidant properties, provides protection against pathologic cardiac remodeling and fibrosis. In present study, we investigated the work of SSD for DOX-induced cardiotoxicity and the involved mechanisms. We observed that DOX injection induced cardiac injury, malfunction and decreased survival rate. Besides, DOX treatment increased lactate dehydrogenase (LDH) leakage, cardiomyocyte apoptosis, myocardium fibrosis and decrease of cardiomyocytes' sizes. Meanwhile, all the effects were notably attenuated by SSD treatment. In vitro, we found that 1μM SSD could enhance the proliferation of H9c2 cells, and inhibit DOX-induced apoptosis. It was found that the levels of MDA and reactive oxygen species (ROS) were significantly reduced by improving the activities of the endogenous antioxidative enzymes including catalase (CAT), and glutathione peroxidase (GSH-Px). Furthermore, SSD treatment could downregulate the DOX-induced p38 phosphorylation. Our results suggested that SSD efficiently protected the cardiomyocytes from DOX-induced cardiotoxicity by inhibiting the excessive oxidative stress via p38 MAPK signaling pathway.

Demonstration of the protective effect of ghrelin in the livers of rats with cisplatin toxicity

Despite the various and newly developed chemotherapeutic agents in recent years, cisplatin is still used very frequently as a chemotherapeutic agent, even though cisplatin has toxic effects on many organs. The aim of our study is to show whether ghrelin reduces the liver toxicity of cisplatin in the rat model. Twenty-eight male Sprague Dawley albino mature rats were chosen to be utilized in the study. Group 1 rats (n = 7) were taken as the control group, and no medication was given to them. Group 2 rats (n = 7) received 5 mg/kg/day cisplatin and 1 ml/kg/day of 0.9% NaCl, Group 3 rats (n = 7) received 5 mg/kg/day cisplatin and 10 ng/kg/day ghrelin, Group 4 rats (n = 7) received 5 mg/kg/day cisplatin and 20 ng/kg/day ghrelin for 3 days. Glutathione, malondialdehyde (MDA), superoxide dismutase (SOD), plasma alanine aminotransferase (ALT) levels, and liver biopsy results were measured in rats. It was determined that, especially in the high-dose group, the MDA, plasma ALT, and SOD levels increased less in the ghrelin group as compared to the cisplatin group, and the glutathione level decreased slightly with a low dose of ghrelin, while it increased with a higher dose. In histopathological examination, it was determined that the toxic effect of cisplatin on the liver was reduced with a low dose of ghrelin, and its histopathological appearance was similar to normal liver tissue when given a high dose of ghrelin. These findings show that ghrelin, especially in high doses, can be used to reduce the toxic effect of cisplatin.

Temporal changes and prognostic value of plasma ghrelin level in patients with acute heart failure: a prospective study

BACKGROUND

Plasma ghrelin levels can be elevated in patients with acute heart failure (AHF). This study aimed to analyze the temporal changes and prognostic value of ghrelin levels in patients with AHF.

METHODS

This prospective study included patients with AHF at the Cardiology Department, Weifang People's Hospital (May 2018-October 2019), and age- and sex-matched healthy controls. Plasma ghrelin levels were measured. Multivariable logistic regression and receiver operating characteristic (ROC) curve analyses were used to evaluate whether ghrelin levels could predict major cardiac adverse events (MACEs) during a 1-year follow-up.

RESULTS

Finally, 92 patients with AHF and 50 healthy controls were enrolled. Ghrelin levels were higher in patients with AHF at 1, 3, 12, and 24 h compared with controls (all P < 0.01). Ghrelin levels in the AHF group were higher at 3 and 12 h than at 1 and 24 h (P < 0.001). Ghrelin level at 3 h in patients with AHF was negatively correlated with the left ventricular end-diastolic diameter and left ventricular ejection fraction (both P < 0.05). MACEs occurred in 48 patients with AHF. Ghrelin levels were higher in the MACE group than in the non-MACE group at 1 (P = 0.011) and 3 h (P = 0.034). Multivariable regression showed that ghrelin level at 3 h was independently associated with MACEs [OR = 0.629, 95% confidence interval (CI): 0.515-0.742, P = 0.010], but the area under the ROC curve was only 0.629 (95% CI 0.515-0.742).

CONCLUSIONS

Plasma ghrelin levels are elevated in AHF and patients with MACEs during follow-up.

Acylated Ghrelin Attenuates l-Thyroxin-induced Cardiac Damage in Rats by Antioxidant and Anti-inflammatory Effects and Downregulating Components of the Cardiac Renin-angiotensin System

ABSTRACT

This study investigated the protective effect of acylated ghrelin (AG) against l-thyroxin (l-Thy)-induced cardiac damage in rats and examined possible mechanisms. Male rats were divided into five intervention groups of 12 rats/group: control, control + AG, l-Thy, l-Thy + AG, and l-Thy + AG + [D-Lys3]-GHRP-6 (AG antagonist). l-Thy significantly reduced the levels of AG and des-acyl ghrelin and the AG to des-acyl ghrelin ratio. Administration of AG to l-Thy-treated rats reduced cardiac weights and levels of reactive oxygen species and preserved the function and structure of the left ventricle. In addition, AG also reduced the protein levels of cleaved caspase-3 and cytochrome c and prevented mitochondrial permeability transition pore opening. In the left ventricle of both control + AG-treated and l-Thy + AG-treated rats, AG significantly increased left ventricular levels of manganese superoxide dismutase (SOD2), total glutathione (GSH), and Bcl2. It also reduced the levels of malondialdehyde, tumor necrosis factor-α (TNF-α), interleukin-6, and Bax and the nuclear activity of nuclear factor-kappa B. Concomitantly, in both treated groups, AG reduced the mRNA and protein levels of NADPH oxidase 1, angiotensin (Ang) II type 1 receptor, and Ang-converting enzyme 2. All the beneficial effects of AG in l-Thy-treated rats were prevented by the coadministration of [D-Lys3]-GHRP-6, a selective growth hormone secretagogue receptor subtype 1a antagonist. In conclusion, AG protects against hyperthyroidism-induced cardiac hypertrophy and damage, which is mainly due to its antioxidant and anti-inflammatory potentials and requires the activation of GHS-R1a.

Structural Characterization and Immunomodulatory Activity of a Novel Polysaccharide From Lycopi Herba

Lycopi Herba has been broadly used as a traditional medicinal herb in Asia due to its ability to strengthen immunity. However, it is still obscure for its material basis and underlying mechanisms. Polysaccharide, as one of the most important components of most natural herbs, usually contributes to the immunomodulatory ability of herbs. Here, we aimed to detect polysaccharides from Lycopi Herba and examine their potential immunomodulatory activity. A novel polysaccharide (LHPW) was extracted from Lycopi Herba and purified by DEAE-52 cellulose chromatography and G-100 sephadex. According to physicochemical methods and monosaccharide composition analysis, LHPW was mainly composed of galactose, glucose, fructose, and arabinose. NMR and methylation analyses indicated that LHPW was a neutral polysaccharide with a backbone containing →3,6)-β-D-Galp-(1→, →4)-β-D-Galp-(1→ and →4)-α-D-Glcp-(1→, with the branches of →1)-β-D-Fruf-(2→ and →6)-α-D-Galp-(1→. Immunological tests indicated that LHPW could activate macrophage RAW264.7 and promote splenocyte proliferation. This study discovered a novel polysaccharide from Lycopi Herba and showed it was a potential immunomodulator.

The role of tumor necrosis factor in triggering activation of natural killer cell, multi-organ mitochondrial dysfunction and hypertension during pregnancy

Pre-eclampsia (PE) is a hypertensive disorder of pregnancy associated with chronic inflammation, mitochondrial (mt) dysfunction and fetal demise. Natural Killer cells (NK cells) are critical for the innate immune response against tumors or infection by disrupting cellular mt function and causing cell death. Although NK cells can be stimulated by Tumor necrosis factor alpha (TNF-α), we don't know the role of TNF-α on NK cell mediated mt dysfunction during PE. Our objective was to determine if mechanisms of TNF-α induced hypertension included activation of NK cells and multi-organ mt dysfunction during pregnancy. Pregnant rats were divided into 2 groups: normal pregnant (NP) (n = 18) and NP + TNF-α (n = 18). On gestational day 14, TNF-α (50 ng/ml) was infused via mini-osmotic pump and on day 18, carotid artery catheters were inserted. Blood pressure (MAP) and samples were collected on day 19. TNF-α increased MAP (109 ± 2 vs 100 ± 2, p < 0.05), circulating cytolytic NK cells (0.771 ± 0.328 vs.0.008 ± 0.003% gated, <0.05) and fetal reabsorptions compared to NP rats. Moreover, TNF-α caused mtROS in the placenta (12976 ± 7038 vs 176.9 ± 68.04% fold, p < 0.05) and in the kidney (2191 ± 1027 vs 816 ± 454.7% fold, p < 0.05) compared to NP rats. TNF-α induced hypertension is associated fetal demise, activation of NK cells and multi-organ mt dysfunction which could be mechanisms for fetal demise and hypertension. Understanding of the mechanisms by which TNF-α causes pathology is important for the use of anti-TNF-α therapeutic agents in pregnancies complicated by PE.

Molecular mechanisms of anthracycline cardiovascular toxicity

Anthracyclines are effective chemotherapeutic agents, commonly used in the treatment of a variety of hematologic malignancies and solid tumors. However, their use is associated with a significant risk of cardiovascular toxicities and may result in cardiomyopathy and heart failure. Cardiomyocyte toxicity occurs via multiple molecular mechanisms, including topoisomerase II-mediated DNA double-strand breaks and reactive oxygen species (ROS) formation via effects on the mitochondrial electron transport chain, NADPH oxidases (NOXs), and nitric oxide synthases (NOSs). Excess ROS may cause mitochondrial dysfunction, endoplasmic reticulum stress, calcium release, and DNA damage, which may result in cardiomyocyte dysfunction or cell death. These pathophysiologic mechanisms cause tissue-level manifestations, including characteristic histopathologic changes (myocyte vacuolization, myofibrillar loss, and cell death), atrophy and fibrosis, and organ-level manifestations including cardiac contractile dysfunction and vascular dysfunction. In addition, these mechanisms are relevant to current and emerging strategies to diagnose, prevent, and treat anthracycline-induced cardiomyopathy. This review details the established and emerging data regarding the molecular mechanisms of anthracycline-induced cardiovascular toxicity.

Doxorubicin-induced cardiotoxicity: An update on the molecular mechanism and novel therapeutic strategies for effective management

Doxorubicin (Dox) is a secondary metabolite of the mutated strain of Streptomyces peucetius var. Caesius and belongs to the anthracyclines family. The anti-cancer activity of Dox is mainly exerted through the DNA intercalation and inhibiting topoisomerase II enzyme in fast-proliferating tumors. However, Dox causes cumulative and dose-dependent cardiotoxicity, which results in increased risks of mortality among cancer patients and thus limiting its wide clinical applications. There are several mechanisms has been proposed for doxorubicin-induced cardiotoxicity and oxidative stress, free radical generation and apoptosis are most widely reported. Apart from this, other mechanisms are also involved in Dox-induced cardiotoxicity such as impaired mitochondrial function, a perturbation in iron regulatory protein, disruption of Ca²⁺ homeostasis, autophagy, the release of nitric oxide and inflammatory mediators and altered gene and protein expression that involved apoptosis. Dox also causes downregulation of DNA methyltransferase 1 (DNMT1) enzyme activity which leads to a reduction in the DNA methylation process. This hypomethylation causes dysregulation in the mitochondrial genes like peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1-alpha (PGC-1α), nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM) unit in the heart. Apart from DNA methylation, Dox treatment also alters the micro RNAs levels and histone deacetylase (HDAC) activity. Therefore, in the current review, we have provided a detailed update on the current understanding of the pathological mechanisms behind the well-known Dox-induced cardiotoxicity. Further, we have provided some of the most plausible pharmacological strategies which have been tested against Dox-induced cardiotoxicity.

Salmon acyl-ghrelin increases food intake and reduces doxorubicin-induced myocardial apoptosis in rats, likely by anti-oxidative activity

We had reported that orally administered ghrelin-containing salmon stomach extract prevents doxorubicin (DOX)-induced cardiotoxicity. In this study, we investigated the binding affinity of salmon ghrelin to rat ghrelin receptor and the cardioprotective effects of subcutaneous (sc) injected synthetic salmon ghrelin in rats with DOX-induced acute heart failure in order to clarify the potential efficacy of salmon ghrelin. Intracellular calcium mobilization assay was performed on rat GHS-R1a-expressing CHO cells to reveal ghrelin activity. Rats were divided into five groups; the normal control (I), and toxic control (II) groups were given saline (sc, twice daily), and the salmon acyl-ghrelin (sAG) (III), salmon unacylated-ghrelin (sUAG) (IV), and rat acyl-ghrelin (rAG) (V) groups were given corresponding synthetic ghrelins (sc, twice daily), respectively. After seven days of treatment, DOX (20 mg/kg BW) or saline was administered to the corresponding groups by intraperitoneal injection. The toxic control group was the negative control group for the DOX-induced cardiotoxicity groups. While sAG displayed similar affinity to rAG upon application to GHS-R1a-expressing cells, and also decreased DOX-induced apoptosis and increased food intake, sUAG did not. Both sAG and rAG improved DOX-induced deterioration, showing anti-oxidative activity. The anti-oxidative activity of sAG might contribute to the protective effects on cardiomyocytes. The results also suggest that, similar to rAG, sAG is a potent protectant against DOX-induced cardiotoxicity and a potential functional component in orally administered ghrelin-containing salmon stomach extract, which prevented DOX-induced cardiotoxicity in our previous study.

Heal the heart through gut (hormone) ghrelin: a potential player to combat heart failure

Ghrelin, a small peptide hormone (28 aa), secreted mainly by X/A-like cells of gastric mucosa, is also locally produced in cardiomyocytes. Being an orexigenic factor (appetite stimulant), it promotes release of growth hormone (GH) and exerts diverse physiological functions, viz. regulation of energy balance, glucose, and/or fat metabolism for body weight maintenance. Interestingly, administration of exogenous ghrelin significantly improves cardiac functions in CVD patients as well as experimental animal models of heart failure. Ghrelin ameliorates pathophysiological condition of the heart in myocardial infarction, cardiac hypertrophy, fibrosis, cachexia, and ischemia reperfusion injury. This peptide also exerts significant impact at the level of vasculature leading to lowering high blood pressure and reversal of endothelial dysfunction and atherosclerosis. However, the molecular mechanism of actions elucidating the healing effects of ghrelin on the cardiovascular system is still a matter of conjecture. Some experimental data indicate its beneficial effects via complex cellular cross talks between autonomic nervous system and cardiovascular cells, some other suggest more direct receptor-mediated molecular actions via autophagy or ionotropic regulation and interfering with apoptotic and inflammatory pathways of cardiomyocytes and vascular endothelial cells. Here, in this review, we summarise available recent data to encourage more research to find the missing links of unknown ghrelin receptor-mediated pathways as we see ghrelin as a future novel therapy in cardiovascular protection.

Doxorubicin‑induced oxidative and nitrosative stress: Mitochondrial connexin 43 is at the crossroads

Oxidative stress is widely accepted as a key factor of doxorubicin (Doxo)-induced cardiotoxicity. There is evidence to indicate that nitrosative stress is involved in this process, and that Doxo interacts by amplifying cell damage. Mitochondrial connexin 43 (mitoCx43) can confer cardioprotective effects through the reduction of mitochondrial reactive oxygen species production during Doxo-induced cardiotoxicity. The present study aimed to evaluate the involvement of mitoCx43 in Doxo-induced nitrosative stress. Rat H9c2 cardiomyoblasts were treated with Doxo in the absence or presence of radicicol, an inhibitor of Hsp90, the molecular chaperone involved in Cx43 translocation to the mitochondria that underlies its role in cardioprotection. FACS analysis and RT-qPCR revealed that Doxo increased superoxide dismutase, and catalase gene and protein expression. As shown by hypodiploid nuclei and confirmed by western blot analysis, Doxo increased caspase 9 expression and reduced procaspase 3 levels, which induced cell death. Moreover, a significant increase in the activation of the NF-κB signaling pathway was observed. It is well known that the increased expression of inducible nitric oxide synthase results in nitric oxide overproduction, which then rapidly reacts with hydrogen peroxide or superoxide generated by the mitochondria, to form highly reactive and harmful peroxynitrite, which ultimately induces nitrotyrosine formation. Herein, these interactions were confirmed and increased effects were observed in the presence of radicicol. On the whole, the data of the present study indicate that an interplay between oxidative and nitrosative stress is involved in Doxo-induced cardiotoxicity, and that both aspects are responsible for the induction of apoptosis. Furthermore, it is demonstrated that the mechanisms that further increase mitochondrial super-oxide generation (e.g., the inhibition of Cx43 translocation into the mitochondria) significantly accelerate the occurrence of cell death.

Acylated Ghrelin Protects the Hearts of Rats from Doxorubicin-Induced Fas/FasL Apoptosis by Stimulating SERCA2a Mediated by Activation of PKA and Akt

This study investigated if the cardioprotective effect of acylated ghrelin (AG) against doxorubicin (DOX)-induced cardiac toxicity in rats involves inhibition of Fas/FasL-mediated cell death. It also investigated if such an effect is mediated by restoring Ca⁺² homeostasis from the aspect of stimulation of SERCA2a receptors. Adult male Wistar rats were divided into 4 groups (20 rats/each) as control, control + AG, DOX, and DOX + AG. AG was co-administered to all rats consecutively for 35 days. In addition, isolated cardiomyocytes were cultured and treated with AG in the presence or absence of DOX with or without pre-incubation with [D-Lys3]-GHRP-6 (a AG receptor antagonist), VIII (]an Akt inhibitor), or KT-5720 (a PKA inhibitor). AG increased LVSP, dp/dt_max, and dp/dt_min in both control and DOX-treated animals and improved cardiac ultrastructural changes in DOX-treated rats. It also inhibited ROS in control rats and lowered LVEDP, intracellular levels of ROS and Ca²⁺, and activity of calcineurin in LVs of DOX-treated rats. Concomitantly, it inhibited LV NFAT-4 nuclear translocation and downregulated their protein levels of Fas and FasL. Mechanistically, in control or DOX-treated hearts or cells, AG upregulated the levels of SERCA2a and increased the activities of PKA and Akt, leading to increase phosphorylation of phospholamban at Ser¹⁶ and Thr¹⁷. All these effects were abolished by D-Lys3-GHRP-6, VIII, or KT-5720 and were independent of food intake or GH/IGF-1. In conclusion, AG cardioprotection against DOX involves inhibition of extrinsic cell death and restoring normal Ca⁺² homeostasis.

An engineered non-erythropoietic erythropoietin-derived peptide, ARA290, attenuates doxorubicin induced genotoxicity and oxidative stress

Erythropoietin (EPO) applies anti-inflammatory, anti-apoptotic, anti-oxidant and cytoprotective effects besides its hematopoietic action. A nonhematopoietic peptide engineered from EPO, ARA 290, interacts selectively with the innate repair receptor and has similar possessions. ARA290 mediates tissue protection without hematopoietic side-effects of EPO which limit its clinical application. Doxorubicin (DOX) is the broad-spectrum chemotherapeutic agent, but its use is limited by the development of nonspecific toxicity on noncancerous tissues especially in cardiac cells. Mechanisms behind the DOX-induced toxicities are enhanced level of oxidative damage, inflammation and apoptosis. In the present study, we have investigated whether ARA290 acts as a chemoprotective agent modulating the cytotoxicity, genotoxicity and oxidative stress induced in vitro by DOX. The genoprotective effect of ARA290 on DOX-induced toxicity in three cell line (HepG2, HGF & Stem cell) were assessed. Cells were treated with ARA290 (50-400 nM) and DOX (1 μM) in pretreatment condition. Cytotoxicity was evaluated using the MTT assay, genoprotective effect of ARA290 were evaluated using the micronucleus test and comet assay. AR290 significantly reduced the percentage of DNA in tail and the frequency of micronuclei induced by DOX. Besides, DOX impaired anti-oxidant defense enzyme activities and induced inflammation and apoptotic cell death. ARA290 markedly attenuated DOX induced oxidative stress and protected against DOX induced inflammation and apoptotic cell death. This result proposes that ARA290 can act as a protective agent, reducing DOX-induced DNA damage and oxidative stress, and it is possible that this protection could also extend to cardiac cells.

Biocompatibility assessment of Fe3O4 nanoparticles using Saccharomyces cerevisiae as a model organism

Using Saccharomyces cerevisiae as an experimental model, the potential toxicological effects of Fe₃O₄ nanoparticles (Fe₃O₄-NPs) were investigated following exposure to 0-600 mg/L for 24 h. Results revealed that cell proliferation was significantly inhibited by Fe₃O₄-NPs with an IC₅₀ value of 326.66 mg/L. Mortality showed a concentration-dependent increase, and the highest concentration in this study (600 mg/L) resulted in 22.30% mortality. In addition, Effects on proliferation and mortality were accounted for Fe₃O₄-NPs rather than iron ion released from Fe₃O₄-NPs. Scanning and transmission electron microscope observation showed that Fe₃O₄-NPs extensively attached on the cell surfaces, causing cells to deform and shrink. Moreover, Fe₃O₄-NPs could be internalized in S. cerevisiae cells via endocytosis and then be distributed in cytoplasm and vesicles. The data of uptake kinetics demonstrated that the maximal accumulation (4.898 mg/g) was reached at 15 h. Besides, percentage of late apoptosis/necrosis was observably increased (p < 0.01) at 600 mg/L (15.80%), and the expression levels of apoptosis-related genes (SOD, Yca1 and Nuc1) were dramatically increased following exposure to Fe₃O₄-NPs for 24 h. As expected, mitochondrial transmembrane potential was significantly decreased (p < 0.01) at 50-600 mg/L, and biomarkers of oxidative stress (ROS, CAT and SOD) were also markedly changed following exposure. Altogether, the combined results so far indicated Fe₃O₄-NPs could induce S. cerevisiae cell apoptosis that mediated by mitochondrial impairment and oxidative stress.

Panax ginseng Total Protein Facilitates Recovery from Dexamethasone-Induced Muscle Atrophy through the Activation of Glucose Consumption in C2C12 Myotubes

Background

The clinical anti-inflammatory drug dexamethasone (DEX) can cause many side effects such as muscle atrophy for long-term use. Muscle atrophy induced by DEX may be caused by decrease of glucose consumption. Panax ginseng C.A. Meyer was previously considered to be an antiatrophic agent for glucocorticoid- (GC-) treated therapies. As one of the main components, it remains unclear whether ginseng total protein (GP) facilitates recovery from muscle atrophy induced by DEX.

Methods

In this study, GP was extracted and purified with Sephadex-G50. C2C12 myoblasts was induced with 2% horse serum to differentiate into C2C12 myotubes. Cell viability was analyzed by the MTT assay, and Ca²⁺ concentration was analyzed by a flow cytometer. The release of lactic dehydrogenase (LDH) and the glucose consumption were analyzed by spectrophotometry. The phosphorylation of AMP-activated protein kinase (AMPK), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt) and the expression of glucose transporter 4 (GLUT4) were analyzed by Western blotting. The phosphorylation of AS160 was quantified by Immunofluorescence staining.

Results

We found that GP increased cell viability and increased myotube diameter in high-dose DEX-treated C2C12 myotubes for 24 h, but this activity was not found in the enzymatic hydrolyzed GP group. GP reduced muscle atrophy by decreasing the expression of key proteins such as muscle RING-finger protein-1 and muscle atrophy F-box, reducing the Ca²⁺ concentration, and decreasing the release of LDH in DEX-injured C2C12 myotubes. Moreover, GP improved glucose consumption and increased the phosphorylation of AMPK, PI3K, Akt, and AS160 and the expression of GLUT4 in DEX-treated C2C12 myotubes.

Conclusion

The results of this study suggest that GP has effects on recovering DEX-induced muscle atrophy and cell injury, which may improve glucose consumption via the AMPK and PI3K/Akt pathways in high-dose DEX-treated C2C12 myotubes. This study provides in vitro mechanistic insights into the recovery of muscle atrophy with GP treatment.

Resveratrol alleviates inflammatory injury and enhances the apoptosis of fibroblast‑like synoviocytes via mitochondrial dysfunction and ER stress in rats with adjuvant arthritis

Resveratrol, a bioactive compound predominantly found in grapes and red wine, provides a wide range of properties that are beneficial for health, including anticancer and anti-inflammatory activities. Previously published studies have addressed the potential therapeutic effects of resveratrol on rheumatoid arthritis (RA); however, the subcellular mechanism remains to be fully elucidated. In the present study, the therapeutic effects of resveratrol on adjuvant arthritis (AA) in Sprague-Dawley rats were investigated, and the mechanisms of resveratrol-induced apoptosis in fibroblast-like synoviocytes (FLSs) were further examined. Based on the findings, resveratrol treatment over a 12-day period led to a reduction in paw swelling and arthritis scores at the macroscopic level, and an attenuation of inflammatory cell infiltration and synovial hyperplasia, upon a histopathological examination of the AA rats. Furthermore, the administration of resveratrol triggered decreases in the expression of interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor-α (TNF-α) and an increase in the expression of IL-10, alleviating inflammatory injury in AA rats in a dose-dependent manner. In addition, resveratrol was revealed to induce the apoptosis of FLSs when administered with 5 µM H₂O₂ as determined by elevated levels of Bax, caspase-3, caspase-12 and C/EBP-homologous protein, and the downregulation of B-cell lymphoma 2 (Bcl-2), suggesting that resveratrol is able to induce apoptosis in FLSs via the mitochondrial pathway and endoplasmic reticulum (ER) stress in a milieu containing 5 µM H₂O₂. Furthermore, JC-1 was used as a fluorescent probe to detect the mitochondrial membrane potential (Δψm), and resveratrol was shown to reduce the Δψm in FLSs in the presence of 5 µM H₂O₂. However, resveratrol was not able to trigger intracellular calcium overload, although it did suppress ATP- and thapsigargin-induced calcium release from the ER. In conclusion, the present study revealed that resveratrol was able to alleviate inflammatory injury in AA rats, triggering the apoptosis of FLSs via the mitochondrial pathway and ER stress. These results provide a theoretical basis for future treatments using resveratrol for RA.

Co-delivery of DOX and PDTC by pH-sensitive nanoparticles to overcome multidrug resistance in breast cancer

Chemotherapeutic drugs have a series of limitations in the conventional clinical treatments, mainly including serious adverse effects and multidrug resistance (MDR). Herein, we developed a pH-sensitive polymeric nanoparticle with using poly(ortho ester urethanes) copolymers for co-delivering doxorubicin (DOX) and pyrrolidinedithiocarbamate (PDTC) to settle these problems. Dual-drug-loaded nanoparticles were nano-sized (˜220 nm) with the spherical morphology and excellent physiological stability. Both drugs both could be quickly released in the mild acidic conditions due to the cleavage of ortho ester bonds. Monolayer cultured cells (2D) and multicellular spheroids (3D) experiments proved that PDTC could reverse multidrug resistance (MDR), improve intracellular drugs accumulation and enhance tumor penetration by down-regulating the expression of P-gp, then resulting in higher DOX-induced cytotoxicity and apoptosis in MCF-7 and MCF-7/ADR cells. Besides, in vivo experiments further demonstrated that co-encapsulated nanoparticles had higher DOX accumulation and superiorer tumor growth inhibition (TGI 82.9%) than free drugs or single-drug-loaded nanoparticles on MCF-7/ADR bearing-mice. Accordingly, the pH-sensitive co-delivery systems possess a promising potential to overcome MDR in cancer therapy.

Acylated ghrelin prevents doxorubicin-induced cardiac intrinsic cell death and fibrosis in rats by restoring IL-6/JAK2/STAT3 signaling pathway and inhibition of STAT1

This study investigated if JAK/STAT signaling pathway mediates doxorubicin (DOX)-induced cell death and fibrosis in left ventricles (LVs) of rats and examined if acylated ghrelin affords protection by modulating this pathway. Male rats (120 ± 5 g) were divided into 6 groups (10 rats each) as follows: control; control + AG (10 ng/kg, s.c.); DOX (an accumulative dose 15 mg/kg, i.p.); DOX + AG, DOX + AG + AG490, a JAK2 inhibitor (5 mg/kg, i.p.); and DOX + AG + [D-Lys3]-GHRP-6; an AG receptor antagonist (3.75 mg/kg, i.p.). All treatments were carried out for 35 days. In rats' LVs, DOX significantly impaired the systolic and diastolic functions, enhanced levels of ROS and MDA, reduced levels of GSH and Bcl-2, and increased mRNA and protein levels of collagen I/III and TGF-β and cleaved caspase-3. In addition, although DOX did not affect JAK1 or JAK2 activity, it significantly increased protein levels of IL-6, decreased STAT3 and p-STAT3 (Tyr701&Ser727), and increased STAT1 and p-STAT1 (Tyr701&Ser727) levels, with a concomitant decrease in ERK1/2 activity and an increase in P38 activity. However, without affecting IL-6 and JAK1/2, AG reversed all of the observed alterations with a significant increase in the levels and activities of JAK2. Similar effects of AG were also seen in control rats. Interestingly, all the beneficial effects afforded by AG were abolished by AG490 and AG + [D-Lys3]-GHRP-6. In conclusion, DOX-induced cardiac toxicity involves stimulation of IL-6, P38, and STAT1 signaling levels whereas the protective effect afforded by AG involves the activation of ERK1/2 and JAK2/STAT3 and inhibition of STAT1.

Protective effect of ghrelin against tilmicosin-induced left ventricular dysfunction in rats

This study was conducted to investigate the possible protective effects of ghrelin against tilmicosin-induced acute ventricular dysfunction in rats. Forty adult male Sprague Dawley rats were randomly divided into 4 equal groups: control, ghrelin, tilmicosin, and ghrelin + tilmicosin. The left ventricular structural and functional parameters together with cardiac biomarker levels were evaluated. The results showed that tilmicosin treatment alone significantly decreased the left ventricular fractional shortening, left ventricular ejection fraction, left ventricular stroke volume, and cardiac output when compared with control group. In addition, tilmicosin led to a significant increase in left ventricular internal dimension in systole and left ventricular fractional end-systolic volume. At the same time, serum lactate dehydrogenase, creatine kinase, and creatine kinase-myocardial B fraction levels were significantly increased in tilmicosin-treated group when compared with control group. However, ghrelin pretreatment significantly prevented the left ventricular internal dimension in systole, left ventricular fractional end-systolic volume, left ventricular stroke volume, left ventricular ejection fraction, left ventricular fractional shortening, and cardiac output changes caused by tilmicosin. Moreover, ghrelin pretreatment could reduce significantly serum lactate dehydrogenase, creatine kinase, and creatine kinase-myocardial B fraction levels. These data indicated that ghrelin treatment may provide a protective effect against tilmicosin-induced left ventricular systolic dysfunction.

[Ghrelin Physiology and Pathophysiology: Focus on the Cardiovascular System]

Ghrelin is a multifunctional peptide hormone, mainly synthesized by P / D1 cells of the stomach fundus mucosa. Its basic effect, which is realized via GHS-R1 α receptor in the arcuate and the ventromedial nucleuses of hypothalamus, is stimulation of the synthesis of pituitary hormones. Ghrelin is involved in control of appetite and energy balance, regulation of carbohydrate and lipid metabolism, cell proliferation and apoptosis, as well as modulation of functioning of gastrointestinal, cardiovascular, pulmonary and immune systems. It was found that cardiomyocytes are able to synthesize ghrelin. High concentrations of GHS-R1α in the heart and major blood vessels evidence for its possible participation in functioning of cardiovascular system. Ghrelin inhibits apoptosis of cardiomyocytes and endothelial cells, and improves the functioning of the left ventricle (LV) after injury of ischemia-reperfusion mechanism. In rats with heart failure (HF) ghrelin improves LV function and attenuates development of cardiac cachexia. In addition, ghrelin exerts vasodilatory effects in humans, improves cardiac function and reduces peripheral vascular resistance in patients with chronic HF. The review contains of the predictive value of ghrelin in the development and prevention of cardiovascular disease.

Apurinic/apyrimidinic endonuclease/redox factor 1 (APE1) alleviates myocardial hypoxia-reoxygenation injury by inhibiting oxidative stress and ameliorating mitochondrial dysfunction

Oxidative stress and mitochondrial dysfunction are considered to be activators of apoptosis and serve a pivotal role in the pathogenesis of myocardial ischemia-reperfusion (MI/R) injury. Apurinic/apyrimidinic endonuclease/redox factor 1 (APE1) is a multifunctional protein that processes the cellular response to DNA damage and oxidative stress. Little is known about the role of APE1 in the pathogenesis of MI/R injury. The aim of the present study was to investigate the effects of APE1 on hypoxia-reoxygenation (H/R)-induced H9c2 cardiomyocyte injury and the underlying mechanism responsible. It was demonstrated that H/R decreased cell viability and increased lactic dehydrogenase (LDH) release, as well as reducing APE1 expression in H9c2 cells. However, APE1 overexpression induced by transfection with APE1-expressing lentivirus significantly increased H9c2 cell viability, decreased LDH release, decreased apoptosis and reduced caspase-3 activity in H/R-treated H9c2 cells. APE1 overexpression ameliorated the H/R-induced increases in reactive oxygen species and NAPDH oxidase expression, as well as the decreases in superoxide dismutase activity and glutathione expression. Furthermore, APE1 overexpression increased mitochondrial membrane potential and ATP production, stabilized electron transport chain activity (as illustrated by increased NADH-ubiquinone oxidoreductase, succinate dehydrogenase, coenzyme Q-cytochrome c oxidoreductase and cytochrome c oxidase activities) and decreased the ratio of B-cell lymphoma 2-associated X protein/B-cell lymphoma 2 in H/R, improving mitochondrial dysfunction. In conclusion, the results of the present study suggest that APE1 alleviates H/R-induced injury in H9c2 cells by attenuating oxidative stress and ameliorating mitochondrial dysfunction. APE1 may therefore be used as an effective treatment for MI/R injury.

Fusobacterium nucleatum promotes chemoresistance to 5-fluorouracil by upregulation of BIRC3 expression in colorectal cancer

Background

Emerging evidence suggests a potential relationship between gut microbiota and the host response to chemotherapeutic drugs including 5-fluorouracil (5-Fu). Fusobacterium nucleatum (Fn) has been linked to the initiation and progression of colorectal cancer (CRC). Unfortunately, little was known about the relationship between Fn infection and chemotherapeutic efficacy. Here, we investigate the potential relationship between Fn infection and chemotherapeutic efficacy of 5-Fu in CRC.

Methods

Differentially expressed genes of CRC cell lines induced by Fn infection were analyzed based on a whole genome microarray analysis Then, we explored the relationship between upregulation of BIRC3 induced by Fn infection and chemoresistance to 5-Fu in vitro and in vivo. Furthermore, we dissected the mechanisms involved in Fn-induced BIRC3 expression. Finally, we investigated the clinical relevance of Fn infection, BIRC3 protein expression and chemoresistance to 5-Fu treatment in CRC patients.

Results

BIRC3 was the most upregulated gene induced by Fn infection via the TLR4/NF-κB pathway in CRC cells; Fn infection reduced the chemosensitivity of CRC cells to 5-Fu through upregulation of BIRC3 in vitro and in vivo. High Fn abundance correlated with chemoresistance in advanced CRC patients who received standard 5-Fu-based adjuvant chemotherapy after radical surgery.

Conclusions

Our evidence suggests that Fn and BIRC3 may serve as promising therapeutic targets for reducing chemoresistance to 5-Fu treatment in advanced CRC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0985-y) contains supplementary material, which is available to authorized users.

A β-glucan from Durvillaea Antarctica has immunomodulatory effects on RAW264.7 macrophages via toll-like receptor 4

We studied the mechanisms underlying the immunostimulatory effects of aβ-1,3/1,6-glucan (BG136) from Durvillaea Antarctica. Our data showed that BG136 promoted the activation of MAPKs and NF-κB signaling pathways and cytokines production. BG136 did not increase MCP-1 or NO production or phosphorylation of NF-κB and MAPK in TLR4 siRNA knockdown cells, indicating that BG136 activates macrophages through TLR4. Flow cytometry analysis and confocal experiment showed that BG136 bound to TLR4 expressed on RAW264.7 macrophage cells surface. The affinity of BG136 for TLR4 was determined using Surface Plasmon Resonance (SPR) (KD: 4.51 × 10-6M). Altogether, our results showed that BG136 activates RAW264.7 cells by binding to TLR4 and then triggering TLR4-mediated signaling pathways to promote cytokines secretion.

Mitochondria-Targeting Small Molecules Effectively Prevent Cardiotoxicity Induced by Doxorubicin

Doxorubicin (Dox) is a chemotherapeutic agent widely used for the treatment of numerous cancers. However, the clinical use of Dox is limited by its unwanted cardiotoxicity. Mitochondrial dysfunction has been associated with Dox-induced cardiotoxicity. To mitigate Dox-related cardiotoxicity, considerable successful examples of a variety of small molecules that target mitochondria to modulate Dox-induced cardiotoxicity have appeared in recent years. Here, we review the related literatures and discuss the evidence showing that mitochondria-targeting small molecules are promising cardioprotective agents against Dox-induced cardiac events.

Cationic Organochalcogen with Monomer/Excimer Emissions for Dual-Color Live Cell Imaging and Cell Damage Diagnosis

Studies on the development of fluorescent organic molecules with different emission colors for imaging of organelles and their biomedical application are gaining lots of focus recently. Here, we report two cationic organochalcogens 1 and 2, both of which exhibit very weak green emission (Φ₁ = 0.12%; Φ₂ = 0.09%) in dilute solution as monomers, but remarkably enhanced green emission upon interaction with nucleic acids and large red-shifted emission in aggregate state by the formation of excimers at high concentration. More interestingly, the monomer emission and excimer-like emission can be used for dual color imaging of different organelles. Upon passively diffusing into cells, both probes selectively stain nucleoli with strong green emission upon 488 nm excitation, whereas upon 405 nm excitation, a completely different stain pattern by staining lysosomes (for 1) or mitochondria (for 2) with distinct red emission is observed because of the highly concentrated accumulation in these organelles. Studies on the mechanism of the accumulation in lysosomes (for 1) or mitochondria (for 2) found that the accumulations of the probes are dependent on the membrane permeabilization, which make the probes have great potential in diagnosing cell damage by sensing lysosomal or mitochondrial membrane permeabilization. The study is demonstrative, for the first time, of two cationic molecules for dual-color imaging nucleoli and lysosomes (1)/mitochondria (2) simultaneously in live cell based on monomer and excimer-like emission, respectively, and more importantly, for diagnosing cell damage.

Dihydrodiosgenin protects against experimental acute pancreatitis and associated lung injury through mitochondrial protection and PI3Kγ/Akt inhibition

BACKGROUND AND PURPOSE

Acute pancreatitis (AP) is a painful and distressing disorder of the exocrine pancreas with no specific treatment. Diosgenyl saponins extracted from from Dioscorea zingiberensis C. H. Wright have been reported to protect against experimental models of AP. Diosgenin, or its derivatives are anti-inflammatory in various conditions. However, the effects of diosgenin and its spiroacetal ring opened analogue, dihydrodiosgenin (Dydio), on AP have not been determined.

EXPERIMENTAL APPROACH

Effects of diosgenin and Dydio on sodium taurocholate hydrate (Tauro)-induced necrosis were tested, using freshly isolated murine pancreatic acinar cells. Effects of Dydio on mitochondrial dysfunction in response to Tauro, cholecystokinin-8 and palmitoleic acid ethyl ester were also assessed. Dydio (5 or 10 mg·kg^-1 ) was administered after the induction in vivo of Tauro-induced AP (Wistar rats), caerulein-induced AP and palmitoleic acid plus ethanol-induced AP (Balb/c mice). Pancreatitis was assessed biochemically and histologically. Activation of pancreatic PI3Kγ/Akt was measured by immunoblotting.

KEY RESULTS

Dydio inhibited Tauro-induced activation of the necrotic cell death pathway and prevented pancreatitis stimuli-induced mitochondrial dysfunction. Therapeutic administration of Dydio ameliorated biochemical and histopathological responses in all three models of AP through pancreatic mitochondrial protection and PI3Kγ/Akt inactivation. Moreover, Dydio improved pancreatitis-associated acute lung injury through preventing excessive inflammatory responses.

CONCLUSION AND IMPLICATIONS

These data provide in vitro and in vivo mechanistic evidence that the diosgenin analogue, Dydio could be potential treatment for AP. Further medicinal optimization of diosgenin and its analogue might be a useful strategy for identifying lead candidates for inflammatory diseases.

Characterization and immunological activity of polysaccharides from Ixeris polycephala

A water-soluble polysaccharide, named KMCP, was isolated and purified from edible plant Ixeris polycephala by using DEAE-52 cellulose chromatography. Its structure was determined by chemical analysis, methylation analysis, and NMR analysis, coupled with characterization by scanning electron spectroscopy (SEM). The resulting data indicated that KMCP was an arabinogalactan, with an average molecular weight of 1.95×10⁶Da, which was mainly composed of arabinose and galactose in a relative molar ratio of 28.1% and 70.3%, respectively. The structure of KMPC was characterized as 72.5% of (1→4)-β-Galp residues interspersed with 27.5% of (1→4,6)-β-Galp residues in the main chain, and the branches were composed of (1→5)-α-Araf moieties or α-Araf (1→5) α-Araf (1→disaccharide moieties attached at O-6 of the (1→4,6)-β-Galp residues. KMCP was revealed to be capable of exhibiting macrophage-mediated innate immune responses via enhancing phagocytosis of macrophages and increasing production of NO, activating NF-κB signaling pathway and promoting the mice spleen cells proliferation in a dose-dependent manner within the test concentrations (10.0-200.0μg/mL). These results suggested that KMCP could potentially be an effective and safe immunomodulator valuable to be utilized in pharmacological fields or in the development of functional foods.

Oroxylum indicum root bark extract prevents doxorubicin-induced cardiac damage by restoring redox balance

BACKGROUND

Oroxylum indicum Vent., a Dasamula plant used in Ayurveda possesses antioxidant properties.

OBJECTIVES

To evaluate the cardioprotective effect of 70% methanolic extract of O. indicum Vent. root bark (OIM) against doxorubicin induced cardiomyopathy in female Sprague Dawley rats.

MATERIALS AND METHODS

Cardiotoxicity was induced by intra-peritoneal injection of doxorubicin 30 mg/kg body weight (b.w.) for 4 consecutive days after a ten-day pre-treatment of animals with OIM at 200 mg/kg b.w. and 400 mg/kg b.w (p.o.). Drug treatment continued up to day 14. Probucol, orally administered at a dose of 20 mg/kg b.w. served as standard. ECG was recorded. The animals were sacrificed on day 15 and comparative analysis of serum marker levels of creatine phosphokinase (CPK), lactate dehydrogenase (LDH), Serum Glutamate Oxaloacetate Transaminase (SGOT), Serum Glutamate Pyruvate Transaminase (SGPT), tissue antioxidant status based on Superoxide Dismutase (SOD), Glutathione Peroxidase (GPx), reduced Glutathione (GSH) and lipid peroxidation (LPO) was carried out. Histopathological examination was carried out using hematoxylin-eosin staining.

RESULTS

ECG records of OIM treated animals showed normal pattern, in comparison to the control with ST depression and arrhythmia in cardiogram. Tissue antioxidant profile (SOD, GSH and GPx) was significantly (p < 0.01) elevated in the cardiac tissue of treated group in dose-dependent manner; lipid peroxidation level was found to decrease with treatment. Comparative analysis of serum markers - CPK, LDH, SGOT and SGPT - among untreated control, standard and extract treated groups revealed that OIM extract at 400 mg/kg b.w. dose significantly reduced the levels (p < 0.01). Histological analysis revealed normal myocardial architecture in OIM treated groups. HPTLC fingerprint of OIM revealed 8 bands and detected the presence of chrysin, apigenin and quercetin.

CONCLUSION

O. indicum root bark shows marked cardio-protective activity, possibly due to the presence of antioxidant compounds acting synergistically.

Ghrelin alleviates paclitaxel-induced peripheral neuropathy by reducing oxidative stress and enhancing mitochondrial anti-oxidant functions in mice

Paclitaxel is an effective chemotherapeutic agent, but has some treatment-limiting adverse effects that markedly decrease patients' quality of life. Peripheral neuropathy is one of these, and no treatment for it has been established yet. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, is secreted from the stomach and has widespread effects on multiple systems. We investigated the pharmacological potential of ghrelin in preventing paclitaxel-induced peripheral neuropathy using wild-type mice, ghrelin-null mice, and growth hormone secretagogue receptor-null mice. In wild-type mice, ghrelin administration alleviated mechanical and thermal hypersensitivity, and partially prevented neuronal loss of small unmyelinated intraepidermal nerve fibers but not large myelinated nerve fibers. Moreover, ghrelin administration decreased plasma oxidative and nitrosative stress and increased the expression of uncoupling protein 2 (UCP2) and superoxide dismutase 2 (SOD2) in the dorsal root ganglia, which are mitochondrial antioxidant proteins, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a regulator of mitochondrial number. Both ghrelin-null mice and growth hormone secretagogue receptor-null mice developed more severe nerve injuries than wild-type mice. Our results suggest that ghrelin administration exerts a protective effect against paclitaxel-induced neuropathy by reducing oxidative stress and enhancing mitochondrial anti-oxidant functions, and that endogenous ghrelin has a neuroprotective effect that is mediated by ghrelin/growth hormone secretagogue receptor signaling. Ghrelin could be a promising therapeutic agent for the management of this intractable disease.

Anti-Inflammatory Effects of a Mytilus coruscus α-d-Glucan (MP-A) in Activated Macrophage Cells via TLR4/NF-κB/MAPK Pathway Inhibition

The hard-shelled mussel (Mytilus coruscus) has been used as Chinese traditional medicine for thousands of years; however, to date the ingredients responsible for the various beneficial health outcomes attributed to Mytilus coruscus are still unclear. An α-d-Glucan, called MP-A, was isolated from Mytilus coruscus, and observed to exert anti-inflammatory activity in THP-1 human macrophage cells. Specifically, we showed that MP-A treatment inhibited the production of inflammatory markers, including TNF-α, NO, and PGE2, inducible NOS (iNOS), and cyclooxygenase-2 (COX-2), in LPS-activated THP-1 cells. It was also shown to enhance phagocytosis in the analyzed cells, but to severely inhibit the phosphorylation of mitogen-activated protein kinases (MAPKs) and the nuclear translocation of NF-κB P65. Finally, MP-A was found to exhibit a high binding affinity for the cell surface receptor TLR4, but a low affinity for TLR2 and dectin-1, via surface plasmon resonance (SPR) analysis. The study indicates that MP-A suppresses LPS-induced TNF-α, NO and PEG2 production via TLR4/NF-κB/MAPK pathway inhibition, and suggests that MP-A may be a promising therapeutic candidate for diseases associated with TNF-α, NO, and/or PEG2 overproduction.

Obestatin Plays Beneficial Role in Cardiomyocyte Injury Induced by Ischemia-Reperfusion In Vivo and In Vitro

BACKGROUND Obestatin, primarily recognized as a peptide within the gastrointestinal system, has been shown to benefit the cardiovascular system. We designed this experiment to study the protective role and underlying mechanism of obestatin against ischemia-reperfusion(I/R) injury in myocardial cells. MATERIAL AND METHODS In an In vivo experiment, LAD was ligated for 0.5 h and then opened for reperfusion with obestatin for 24 h. Then, the infarction area was shown with TTC staining, and inflammation factors in serum were analyzed by qRT-PCR. In primary cultured cardiomyocytes, we measured the level of LDH, MDA, GSH, and SOD. Finally, we assessed cells apoptosis using flow cytometry and detected the concentrations of caspase-3, Bax, and Bcl-2 using Western blot analysis. RESULTS TTC staining showed that in the 3 obestatin groups, the infarct area became smaller with the increase of obestatin concentration. Obestatin also inhibited LDH expression in rat serum and decreased mRNA levels of TNF-α, IL-6, ICAM-1, and iNOS in rat cardiomyocytes after reperfusion. In primary cultured cardiomyocytes, obestatin decreased LDH content and increased GSH level after I/R injury. Obestatin was also found to antagonize the apoptosis of cardiomyocytes in a dose-dependent manner. Western blot analysis showed that obestatin downregulated the expression of caspase-3 and Bax and upregulated the expression of Bcl-2. CONCLUSIONS Obestatin can protect cardiomyocyte from I/R-induced injury in vitro and in vivo. This beneficial effect is closely related with its properties of anti-inflammation, anti-cytotoxicity, and anti-apoptosis. The protective effect of obestatin might be associated with activation of Bcl-2 and inhibition of caspase-3 and Bax.

Ghrelin and the Cardiovascular System

Ghrelin is a small peptide released primarily from the stomach. It is a potent stimulator of growth hormone secretion from the pituitary gland and is well known for its regulation of metabolism and appetite. There is also a strong relationship between ghrelin and the cardiovascular system. Ghrelin receptors are present throughout the heart and vasculature and have been linked with molecular pathways, including, but not limited to, the regulation of intracellular calcium concentration, inhibition of proapoptotic cascades, and protection against oxidative damage. Ghrelin shows robust cardioprotective effects including enhancing endothelial and vascular function, preventing atherosclerosis, inhibiting sympathetic drive, and decreasing blood pressure. After myocardial infarction, exogenous administration of ghrelin preserves cardiac function, reduces the incidence of fatal arrhythmias, and attenuates apoptosis and ventricular remodeling, leading to improvements in heart failure. It ameliorates cachexia in end-stage congestive heart failure patients and has shown clinical benefit in pulmonary hypertension. Nonetheless, since ghrelin's discovery is relatively recent, there remains a substantial amount of research needed to fully understand its clinical significance in cardiovascular disease.

Rutin attenuates doxorubicin-induced cardiotoxicity via regulating autophagy and apoptosis

Doxorubicin as anticancer agent can cause dose-dependent cardiotoxicity and heart failure in the long term. Rutin as a polyphenolic flavonoid has been illustrated to protect hearts from diverse cardiovascular diseases. Its function is known to be related to its antioxidant and antiinflammatory activity which may regulate multiple cellular signal pathways. However, the role of rutin on doxorubicin-induced cardiotoxicity has yet to be discovered. In this study, we explored the protective role of rutin on doxorubicin-induced heart failure and elucidated the potential mechanisms of protective effects of rutin against cardiomyocyte death. We analyzed cardiac tissues at the time point of 8weeks after doxorubicin treatment. The results by echocardiography, TUNEL staining, Masson's trichrome staining as well as Western blot analysis revealed that doxorubicin induced remarkable cardiac dysfunction and cardiotoxicity in mice hearts and cardiomyocytes, which were alleviated by rutin treatment. Western blot analysis indicated that the underlying mechanisms included inhibition excessive autophagy and apoptosis mediated by Akt activation. Collectively, our findings suggest that suppression of autophagy and apoptosis by administration of rutin could attenuate doxorubicin-induced cardiotoxicity, which enhances our knowledge to explore new drugs and strategies for combating this devastating side effect induced by doxorubicin. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren & Megan Yingmei Zhang.

Doxorubicin-Induced Systemic Inflammation Is Driven by Upregulation of Toll-Like Receptor TLR4 and Endotoxin Leakage

Doxorubicin is one of the most effective chemotherapeutic agents used for cancer treatment, but it causes systemic inflammation and serious multiorgan side effects in many patients. In this study, we report that upregulation of the proinflammatory Toll-like receptor TLR4 in macrophages by doxorubicin is an important step in generating its toxic side effects. In patient serum, doxorubicin treatment resulted in leakage of endotoxin and inflammatory cytokines into circulation. In mice, doxorubicin damaged the intestinal epithelium, which also resulted in leakage of endotoxin from the gut flora into circulation. Concurrently, doxorubicin increased TLR4 expression in macrophages both in vitro and in vivo, which further enhanced the sensitivity of these cells to endotoxin. Either depletion of gut microorganisms or blockage of TLR4 signaling effectively decreased doxorubicin-induced toxicity. Taken together, our findings suggest that doxorubicin-triggered leakage of endotoxin into the circulation, in tandem with enhanced TLR4 signaling, is a candidate mechanism underlying doxorubicin-induced systemic inflammation. Our study provides new insights for devising relevant strategies to minimize the adverse effects of chemotherapeutic agents such as doxorubicin, which may extend its clinical uses to eradicate cancer cells. Cancer Res; 76(22); 6631-42. ©2016 AACR.

Discovery of new MD2 inhibitor from chalcone derivatives with anti-inflammatory effects in LPS-induced acute lung injury

Acute lung injury (ALI) is a life-threatening acute inflammatory disease with limited options available for therapy. Myeloid differentiation protein 2, a co-receptor of TLR4, is absolutely required for TLR4 sense LPS, and represents an attractive target for treating severe inflammatory diseases. In this study, we designed and synthesized 31 chalcone derivatives that contain the moiety of (E)-4-phenylbut-3-en-2-one, which we consider the core structure of current MD2 inhibitors. We first evaluated the anti-inflammatory activities of these compounds in MPMs. For the most active compound 20, we confirmed that it is a specific MD2 inhibitor through a series of biochemical experiments and elucidated that it binds to the hydrophobic pocket of MD2 via hydrogen bonds with Arg⁹⁰ and Tyr¹⁰² residues. Compound 20 also blocked the LPS-induced activation of TLR4/MD2 -downstream pro-inflammatory MAPKs/NF-κB signaling pathways. In a rat model with ALI induced by intracheal LPS instillation, administration with compound 20 exhibited significant protective effect against ALI, accompanied by the inhibition of TLR4/MD2 complex formation in lung tissues. Taken together, the results of this study suggest the specific MD2 inhibitor from chalcone derivatives we identified is a potential candidate for treating acute inflammatory diseases.

Adh enhances Actinobacillus pleuropneumoniae pathogenicity by binding to OR5M11 and activating p38 which induces apoptosis of PAMs and IL-8 release

Members of the Trimeric Autotransporter Adhesin (TAA) family play a crucial role in the adhesion of Gram-negative pathogens to host cells, but the immunopathogenesis of TAAs remains unknown. Our previous studies demonstrated that Adh from Actinobacillus pleuropneumoniae (A. pleuropneumoniae) is required for full bacterial pathogenicity. Alveolar macrophages are the first line of defense against respiratory infections. This study compared the interactions between porcine alveolar macrophages (PAMs) and wild-type A. pleuropneumoniae (5b WT) or an Adh-deletion strain (5b ΔAdh) via gene microarray, immunoprecipitation and other technologies. We found that Adh was shown to interact with the PAMs membrane protein OR5M11, an olfactory receptor, resulting in the high-level secretion of IL-8 by activation of p38 MAPK signaling pathway. Subsequently, PAMs apoptosis via the activation of the Fax and Bax signaling pathways was observed, followed by activation of caspases 8, 9, and 3. The immunological pathogenic roles of Adh were also confirmed in both murine and piglets infectious models in vivo. These results identify a novel immunological strategy for TAAs to boost the pathogenicity of A. pleuropneumoniae. Together, these datas reveal the high versatility of the Adh protein as a virulence factor and provide novel insight into the immunological pathogenic role of TAAs.

Effects of ghrelin on protein expression of antioxidative enzymes and iNOS in the rat liver

INTRODUCTION

We investigated the effects of ghrelin on protein expression of the liver antioxidant enzymes superoxide dismutases (SODs), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), nuclear factor κB (NFκB) and inducible nitric oxide synthase (iNOS). Furthermore, we aimed to investigate whether extracellular regulated protein kinase (ERK1/2) and protein kinase B (Akt) are involved in ghrelin-regulated liver antioxidant enzymes and iNOS protein expression.

MATERIAL AND METHODS

Male Wistar rats were treated with ghrelin (0.3 nmol/5 µl) injected into the lateral cerebral ventricle every 24 h for 5 days, and 2 h after the last treatment the animals were sacrificed and the liver excised. The Western blot method was used to determine expression of antioxidant enzymes, iNOS, phosphorylation of Akt, ERK1/2 and nuclear factor κB (NFκB) subunits 50 and 65.

RESULTS

There was significantly higher protein expression of CuZnSOD (p < 0.001), MnSOD (p < 0.001), CAT (p < 0.001), GPx, (p < 0.001), and GR (p < 0.01) in the liver isolated from ghrelin-treated animals compared with control animals. In contrast, ghrelin significantly (p < 0.01) reduced protein expression of iNOS. In addition, phosphorylation of NFκB subunits p65 and p50 was significantly (p < 0.001 for p65; p < 0.05 for p50) reduced by ghrelin when compared with controls. Phosphorylation of ERK1/2 and of Akt was significantly higher in ghrelin-treated than in control animals (p < 0.05 for ERK1/2; p < 0.01 for Akt).

CONCLUSIONS

The results show that activation of Akt and ERK1/2 is involved in ghrelin-mediated regulation of protein expression of antioxidant enzymes and iNOS in the rat liver.

Upregulation and nuclear translocation of testicular ghrelin protects differentiating spermatogonia from ionizing radiation injury

Proper control of apoptotic signaling is important for maintenance of testicular homeostasis after ionizing radiation (IR). Herein, we challenged the hypothesis that ghrelin, a pleiotropic modulator, is potentially involved in IR-induced germ cell injury. Lower body exposure to 2 Gy of IR induced a notable increase of ghrelin expression in the nuclear of differentiating spermatogonia at defined stages, with an impairment in the Leydig cells (LCs)-expressing ghrelin. Unexpectedly, inhibition of the ghrelin pathway by intraperitoneal injection of a specific GHS-R1α antagonist enhanced spermatogonia elimination by apoptosis during the early recovery following IR, and thereafter resulted in impaired male fertility, suggesting that the anti-apoptotic effects of evoked ghrelin, although transient along testicular IR injury, have a profound influence on the post-injury recovery. In addition, inhibition of ghrelin signaling resulted in a significant increase in the intratesticular testosterone (T) level at the end of 21 days after IR, which should stimulate the spermatogenic recovery from surviving spermatogonia to a certain extent during the late stage. We further demonstrated that the upregulation and nuclear trafficking of ghrelin, elaborately regulated by IR-elicited antioxidant system in spermatogonia, may act through a p53-dependent mechanism. The elicitation of ghrelin expression by IR stress, the regulation of ghrelin expression by IR-induced oxidative stress and the interaction between p53 and ghrelin signaling during IR injury were confirmed in cultured spermatogonia. Hence, our results represent the first evidence in support of a radioprotective role of ghrelin in the differentiating spermatogonia. The acutely, delicate regulation of local-produced ghrelin appears to be a fine-tune mechanism modulating the balance between testicular homeostasis and early IR injury.

Ghrelin inhibits doxorubicin cardiotoxicity by inhibiting excessive autophagy through AMPK and p38-MAPK

Doxorubicin (DOX) is a wide spectrum antitumor drug, but its clinical application is limited by the cardiotoxicity. Ghrelin, a multi-functional peptide hormone with metabolic regulation in energy homeostasis, plays important roles in cardiovascular protection. Now, the underlying mechanisms of ghrelin against DOX-induced cardiomyocyte apoptosis and atrophy are still not clear. In the present study, we revealed an autophagy-dependent mechanism involved in ghrelin's protection against DOX-induced cardiomyocyte death and size decrease. We observed that DOX insult induced remarkable mortality and cardiac dysfunction in mice, and increase in LDH leakage, cardiomyocyte apoptosis and decrease in cell viability and size in mouse hearts and H9c2 cell cultures, which were effectively improved by ghrelin supplement. We further observed that the strong autophagy stirred by DOX exposure was paralleling with the serious apoptosis and size decrease in cardiomyocytes. Ghrelin, like an autophagy inhibitor, 3-MA, inhibited the DOX-induced autophagy and attenuated cardiomyocyte apoptosis and size decrease. Furthermore, ghrelin significantly reduced the intercellular oxidative stress level, a strong autophagy trigger, partly by augmenting the expression and activities of the endogenous anti-oxidative enzymes. After the further investigation in the post signaling pathways of ghrelin receptors in H9c2 cells, including ERK, p38/MAPK, JNK, AMPK and Akt, we observed that ghrelin supplement only reduced the DOX-activated AMPK and augmented the DOX-down regulated p38-MAPK and mTOR phosphorylation. Our results indicated that ghrelin effectively improved the cardiomyocyte survival and size maintenance by suppressing the excessive autophagy through both ROS inhibition and mTOR induction through suppressing AMPK activity and stimulating p38-MAPK activity.