Endothelial ERG alleviates cardiac fibrosis via blocking endothelin-1-dependent paracrine mechanism.

Cardiac endothelium communicates closely with adjacent cardiac cells by multiple cytokines and plays critical roles in regulating fibroblasts proliferation, activation, and collagen synthesis during cardiac fibrosis. E26 transformation-specific (ETS)-related gene (ERG) belongs to the ETS transcriptional factor family and is required for endothelial cells (ECs) homeostasis and cardiac development. This study aims at investigating the potential role and molecular basis of ERG in fibrotic remodeling within the adult heart. We observed that ERG was abundant in murine hearts, especially in cardiac ECs, but decreased during cardiac fibrosis. ERG knockdown within murine hearts caused spontaneously cardiac fibrosis and dysfunction, accompanied by the activation of multiple Smad-dependent and independent pathways. However, the direct silence of ERG in cardiac fibroblasts did not affect the expression of fibrotic markers. Intriguingly, ERG knockdown in human umbilical vein endothelial cells (HUVECs) promoted the secretion of endothelin-1 (ET-1), which subsequently accelerated the proliferation, phenotypic transition, and collagen synthesis of cardiac fibroblasts in a paracrine manner. Suppressing ET-1 with either a neutralizing antibody or a receptor blocker abolished ERG knockdown-mediated deleterious effect in vivo and in vitro. This pro-fibrotic effect was also negated by RGD (Arg-Gly-Asp)-peptide magnetic nanoparticles target delivery of ET-1 small interfering RNA to ECs in mice. More importantly, we proved that endothelial ERG overexpression notably prevented pressure overload-induced cardiac fibrosis. Collectively, endothelial ERG alleviates cardiac fibrosis via blocking ET-1-dependent paracrine mechanism and it functions as a candidate for treating cardiac fibrosis. • ERG is abundant in murine hearts, especially in cardiac ECs, but decreased during fibrotic remodeling. • ERG knockdown causes spontaneously cardiac fibrosis and dysfunction. • ERG silence in HUVECs promotes the secretion of endothelin-1, which in turn activates cardiac fibroblasts in a paracrine manner. • Endothelial ERG overexpression prevents pressure overload-induced cardiac fibrosis.

Fibronectin type III domain-containing 5 in cardiovascular and metabolic diseases: a promising biomarker and therapeutic target.

Cardiovascular and metabolic diseases are the leading causes of death and disability worldwide and impose a tremendous socioeconomic burden on individuals as well as the healthcare system. Fibronectin type III domain-containing 5 (FNDC5) is a widely distributed transmembrane glycoprotein that can be proteolytically cleaved and secreted as irisin to regulate glycolipid metabolism and cardiovascular homeostasis. In this review, we present the current knowledge on the predictive and therapeutic role of FNDC5 in a variety of cardiovascular and metabolic diseases, such as hypertension, atherosclerosis, ischemic heart disease, arrhythmia, metabolic cardiomyopathy, cardiac remodeling, heart failure, diabetes mellitus, and obesity.

Matrine attenuates pathological cardiac fibrosis via RPS5/p38 in mice.

Pathological cardiac fibrosis is a common feature in multiple cardiovascular diseases that contributes to the occurrence of heart failure and life-threatening arrhythmias. Our previous study demonstrated that matrine could attenuate doxorubicin-induced oxidative stress and cardiomyocyte apoptosis. In this study, we investigated the effect of matrine on cardiac fibrosis. Mice received aortic banding (AB) operation or continuous injection of isoprenaline (ISO) to generate pathological cardiac fibrosis and then were exposed to matrine lavage (200 mg·kg-1·d-1) or an equal volume of vehicle as the control. We found that matrine lavage significantly attenuated AB or ISO-induced fibrotic remodeling and cardiac dysfunction. We also showed that matrine (200 µmol/L) significantly inhibited the proliferation, migration, collagen production, and phenotypic transdifferentiation of cardiac fibroblasts. Mechanistically, matrine suppressed p38 activation in vivo and in vitro, and overexpression of constitutively active p38 completely abolished the protective effects of matrine. We also demonstrated that ribosomal protein S5 (RPS5) upregulation was responsible for matrine-mediated inhibition on p38 and fibrogenesis. More importantly, matrine was capable of ameliorating preexisting cardiac fibrosis in mice. In conclusion, matrine treatment attenuates cardiac fibrosis by regulating RPS5/p38 signaling in mice, and it might be a promising therapeutic agent for treating pathological cardiac fibrosis.

6-Gingerol protects against cardiac remodeling by inhibiting the p38 mitogen-activated protein kinase pathway.

6-Gingerol, a pungent ingredient of ginger, has been reported to possess anti-inflammatory and antioxidant activities, but the effect of 6-gingerol on pressure overload-induced cardiac remodeling remains inconclusive. In this study, we investigated the effect of 6-gingerol on cardiac remodeling in in vivo and in vitro models, and to clarify the underlying mechanisms. C57BL/6 mice were subjected to transverse aortic constriction (TAC), and treated with 6-gingerol (20 mg/kg, ig) three times a week (1 week in advance and continued until the end of the experiment). 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 and cardiac fibroblasts were used to validate the protective effects of 6-gingerol in response to phenylephrine (PE) and transforming growth factor-ß (TGF-ß) challenge. We showed that 6-gingerol administration protected against pressure overload-induced cardiac hypertrophy, fibrosis, inflammation, and dysfunction in TAC mice. In the in vitro study, we showed that treatment with 6-gingerol (20 µM) blocked PE-induced-cardiomyocyte hypertrophy and TGF-ß-induced cardiac fibroblast activation. Furthermore, 6-gingerol treatment significantly decreased mitogen-activated protein kinase p38 (p38) phosphorylation in response to pressure overload in vivo and extracellular stimuli in vitro, which was upregulated in the absence of 6-gingerol treatment. Moreover, transfection with mitogen-activated protein kinase kinase 6 expressing adenoviruses (Ad-MKK6), which specifically activated p38, abolished the protective effects of 6-gingerol in both in vitro and in vivo models. In conclusion, 6-gingerol improves cardiac function and alleviates cardiac remodeling induced by pressure overload in a p38-dependent manner. The present study demonstrates that 6-gingerol is a promising agent for the intervention of pathological cardiac remodeling.

TLR9 deficiency alleviates doxorubicin-induced cardiotoxicity via the regulation of autophagy.

Doxorubicin is a commonly used anthracycline chemotherapeutic drug. Its application for treatment has been impeded by its cardiotoxicity as it is detrimental and fatal. DNA damage, cardiac inflammation, oxidative stress and cell death are the critical links in DOX-induced myocardial injury. Previous studies found that TLR9-related signalling pathways are associated with the inflammatory response of cardiac myocytes, mitochondrial dysfunction and cardiomyocyte death, but it remains unclear whether TLR9 could influence DOX-induced heart injury. Our current data imply that DOX-induced cardiotoxicity is ameliorated by TLR9 deficiency both in vivo and in vitro, manifested as improved cardiac function and reduced cardiomyocyte apoptosis and oxidative stress. Furthermore, the deletion of TLR9 rescued DOX-induced abnormal autophagy flux in vivo and in vitro. However, the inhibition of autophagy by 3-MA abolished the protective effects of TLR9 deletion on DOX-induced cardiotoxicity. Moreover, TLR9 ablation suppressed the activation of p38 MAPK during DOX administration and may promote autophagy via the TLR9-p38 MAPK signalling pathway. Our study suggests that the deletion of TLR9 exhibits a protective effect on doxorubicin-induced cardiotoxicity by enhancing p38-dependent autophagy. This finding could be used as a basis for the development of a prospective therapy against DOX-induced cardiotoxicity.

Combination treatment of perifosine and valsartan showed more efficiency in protecting against pressure overload induced mouse heart failure.

The optimum strategy for heart failure (HF) treatment has yet to be elucidated. This study intended to test the benefit of a combination of valsartan (VAL) and perifosine (PER), a specific AKT inhibitor, in protecting against pressure overload induced mouse HF. Mouse were subjected to aortic banding (AB) surgery to establish HF models and then were given vehicle (HF), VAL (50 mg/kg/d), PER (30 mg/kg/d) or combination of VAL and PER for 4 weeks. Mouse with sham surgery treated with VEH were used for control (VEH). VAL or PER treatment could significantly alleviate mouse heart weight, attenuate cardiac fibrosis and improve cardiac function. The combination treatment of VAL and PER presented much better benefit compared with VAL or PER group respectively. PER treatment significantly inhibited AKT/GSK3ß/mTORC1 signaling. Besides the classic AT1 inhibition, VAL treatment significantly inhibited MAPK (ERK1/2) signaling. Furthermore, VAL and PER treatment could markedly prevent neonatal rat cardiomyocyte hypertrophy and the activation of neonatal rat cardiac fibroblast. Combination of VAL and PER also presented superior beneficial effects than single treatment of VAL or PER in vitro experiments respectively. This study presented that the combination of valsartan and PER may be a potential treatment for HF prevention.

In vitro antitumor activity of guttiferone-A in human breast cancer cells is mediated via apoptosis, mitochondrial mediated oxidative stress and reactive oxygen species production.

PURPOSE: Breast cancer is the second most frequently diagnosed cancer and is considered as the main cause of cancer related death in females. It is estimated that about one-third of women with breast cancer develop metastases and eventually die of this disease. The main treatment options for breast cancer include surgical interventions followed by chemotherapy, hormonotherapy or radiation. However, the side effects associated with the treatment of breast cancer negatively affects the quality of patient's life. In the present study a plant-derived compound, guttiferone- A, was evaluated for its anticancer activity against MCF-7 breast cancer cell line. METHODS: MTT assay was used to evaluate the cytotoxic effects while phase contrast microscopy was used to assess the effects of the compound on cell morphology. Effects on reactive oxygen species (ROS) and mitochondrial membrane potential were evaluated by flow cytometric analysis. RESULTS: It was observed that guttiferone-A reduced the cell viability of MCF-7 cancer cells in a dose-dependent manner. The IC50 for guttiferone-A was found to be 15 µM against MCF-7 cells. Moreover, guttiferone-A induced the production of high levels of ROS and caused significant reduction in the mitochondrial membrane potential. Additionally, guttiferone-A also induced apoptosis in MCF-7 cancer cells in a dose-dependent manner. CONCLUSION: Taken together, we conclude that guttiferone- A is a potential anticancer molecule and may prove to be a lead molecule in cancer drug discovery.

Nanowire-assisted electroporation via inducing cell destruction for inhibiting formation of VBNC bacteria: Comparison with chlorination.

The induction of viable but nonculturable (VBNC) bacteria with cellular integrity and low metabolic activity by chemical disinfection causes a significant underestimation of potential microbiological risks in drinking water. Herein, a physical Co3O4 nanowire-assisted electroporation (NW-EP) was developed to induce cell damage via the locally enhanced electric field over nanowire tips, potentially achieving effective inhibition of VBNC cells as compared with chemical chlorination (Cl2). NW-EP enabled over 5-log removal of culturable cell for various G+/G- bacteria under voltage of 1.0 V and hydraulic retention time of 180 s, and with ∼3-6 times lower energy consumption than Cl2. NW-EP also achieved much higher removals (∼84.6 % and 89.5 %) of viable Bacillus cereus (G+) and Acinetobacter schindleri (G-) via generating unrecoverable pores on cell wall and reversible/irreversible pores on cell membrane than Cl2 (∼28.6 % and 41.1 %) with insignificant cell damage. The residual VBNC bacteria with cell wall damage and membrane pore resealing exhibited gradual inactivation by osmotic stress, leading to ∼99.8 % cell inactivation after 24 h storage (∼59.4 % for Cl2). Characterizations of cell membrane integrity and cell morphology revealed that osmotic stress promoted cell membrane damage for the gradual inactivation of VBNC cells during storage. The excellent adaptability of NW-EP for controlling VBNC cells in DI, tap and lake waters suggested its promising application potentials for drinking water, such as design of an external device on household taps.

Differential Nitrous oxide emission and microbiota succession in constructed wetlands induced by nitrogen forms.

Nitrous oxide (N2O) emission during the sewage treatment process is a serious environmental issue that requires attention. However, the N2O emission in constructed wetlands (CWs) as affected by different nitrogen forms in influents remain largely unknown. This study investigated the N2O emission profiles driven by microorganisms in CWs when exposed to two typical nitrogen sources (NH4+-N or NO3--N) along with different carbon source supply (COD/N ratios: 3, 6, and 9). The results showed that CWs receiving NO3--N caused a slight increase in total nitrogen removal (by up to 11.8 %). This increase was accomplished by an enrichment of key bacteria groups, including denitrifiers, dissimilatory nitrate reducers, and assimilatory nitrate reducers, which enhanced the stability of microbial interaction. Additionally, it led to a greater abundance of denitrification genes (e.g., nirK, norB, norC, and nosZ) as inferred from the database. Consequently, this led to a gradual increase in N2O emission from 66.51 to 486.77 ug-N/(m2·h) as the COD/N ratio increased in CWs. Conversely, in CWs receiving NH4+-N, an increasing influent COD/N ratio had a negative impact on nitrogen biotransformation. This resulted in fluctuating trend of N2O emissions, which decreased initially, followed by an increase at later stage (with values of 122.87, 44.00, and 148.59 ug-N/(m2·h)). Furthermore, NH4+-N in the aquatic improved the nitrogen uptake by plants and promoted the production of more root exudates. As a result, it adjusted the nitrogen-transforming function, ultimately reducing N2O emissions in CWs. This study highlights the divergence in microbiota succession and nitrogen transformation in CWs induced by nitrogen form and COD/N ratio, contributing to a better understanding of the microbial mechanisms of N2O emission in CWs with NH4+-N or NO3--N at different COD/N ratios.

The role of FERMT2 in the tumor microenvironment and immunotherapy in pan-cancer using comprehensive single-cell and bulk sequencing.

FERMT2 has been identified as a participant in integrin-linked kinase signaling pathways, influencing epithelial-mesenchymal transition and thereby affecting tumor initiation, progression, and invasion. While the character of FERMT2 in the tumor microenvironment (TME) as well as its implications for immunotherapy remain unclear. Thus, we conducted a comprehensive analysis to assess the prognostic significance of FERMT2 using Kaplan-Meier analysis. In addition, we employed enrichment analysis to uncover potential underlying molecular mechanisms. Using "Immunedeconv" package, we evaluated the immune characteristics of FERMT2 within TME. Furthermore, we determined the expression levels of FERMT2 in various cell types within TME, based on single-cell sequencing data. To confirm the co-expression of FERMT2 and markers of cancer-associated fibroblasts (CAFs), we performed multiplex immunofluorescence staining on tissue paraffin sections across various cancer types. Our analysis disclosed a significant correlation between elevated FERMT2 expression and unfavorable prognosis in specific cancer types. Furthermore, we identified a strong correlation between FERMT2 expression and diverse immune-related factors, including immune checkpoint molecules, immune cell infiltration, microsatellite instability (MSI), and tumor mutational burden (TMB). Additionally, there was a significant correlation between FERMT2 expression and immune-related pathways, particularly those associated with activating, migrating, and promoting the growth of fibroblasts in diverse cancer types. Interestingly, we observed consistent co-expression of FERMT2 in both malignant tumor cells and stromal cells, particularly within CAFs. Notably, our findings also indicated that FERMT2, in particular, exhibited elevated expression levels within tumor tissues and co-expressed with α-SMA in CAFs based on the multiplex immunofluorescence staining results.

Microbiota and genetic potential for reducing nitrous oxide emissions by biochar in constructed wetlands.

The denitrification process in constructed wetlands (CWs) is responsible for most of the nitrous oxide (N2O) emissions, which is an undesired impact on the ecology of sewage treatment systems. This study compared three types of CWs filled with gravel (CW-B), gravel mixed with natural pyrite (CW-BF), or biochar (CW-BC) to investigate their impact on microbiota and genetic potential for N2O generation during denitrification under varying chemical oxygen demand (COD) to nitrate (NO3--N) ratios. The results showed that natural pyrite and biochar were superior in enhancing COD (90.6-91.2 %) and NO3--N removal (90.0-93.5 %) in CWs with a COD/NO3--N ratio of 9. The accumulation of NO2--N during the denitrification process was the primary cause of N2O emission, with the fluxes ranging from 95.6-472.0 µg/(m2·h) in CW-B, 92.9-400 µg/(m2·h) in CW-BF, and 54.0-293.3 µg/(m2·h) in CW-BC. The addition of biochar significantly reduced N2O emissions during denitrification, while natural pyrite had a lesser inhibitory effect on N2O emissions. The three types of substrates also influenced the structure of microbiota in the biofilm, with natural pyrite enriched nitrogen transformation microorganisms, especially for denitrifiers. Notably, biochar significantly enhanced the abundance of nosZ and the ratio of nosZ/(norB + norC), which are critical factors in reducing N2O emissions from CWs. Overall, the results suggest that the biochar-induced changes in microbiota and genetic potential during denitrification play a significant role in preventing N2O production in CWs, especially when treating sewage with a relatively high COD/NO3--N ratio.

[Relationship between the mutation of leptin receptor gene and tumorigenesis of breast cancer].

OBJECTIVE: The aim of this study was to investigate the relationship of the mutations of leptin receptor gene exon 4, exon 6, exon9, and exon20 with the tumorigenesis of breast cancer. METHODS: Genomic DNA was extracted from breast cancer tissues of 155 patients, benign lesions of 56 patients and normal tissues and blood samples from 100 health control subjects. The leptin receptor genes were assayed with polymerase chain reaction (PCR) amplification and direct sequence analysis. RESULTS: Nucleotide substitutions no mutations were found at exon 4, and nucleotide substitutions occurred at codon 1029 in exon 9, no significant difference among the three groups (P = 0.574). The nucleotide substitutions at codon 668 in exon 6 resulted in Gln223Arg polymorphisms. The occurring frequencies of GG, GA, AA in breast cancer, breast benign lesions tissues and health tissues control group were 70.9% and 17.4%, 12.3%; 80.4%, 14.3% and 5.4%; and 81.0%, 16.0%, and 3.0%, respectively. Alleles of G and A in the three groups were 79.1% and 20.8%, 87.5% and 12.5%, and 89.0% and 11.0%, respectively. Compared the Gln223Arg genotype with the three allele groups, there were significant differences (χ(2) = 16.11, P < 0.005 and χ(2) = 11.41, P < 0.01), respectively. The nucleotide substitutions at codon 3057 in exon 20 resulted in Pro1019Pro polymorphisms. The occurrence frequencies of GG, GA, AA in the breast cancer, benign disease and health control groups were 11.6%, 30.3% and 56.1%; 32.1%, 44.0% and 28.5%; and 32.0%, 45.0% And 23.0%, respectively. Alleles of G and A in the three groups were 26.8% and 73.2%, 51.8% and 48.2%, and 54.5% and 45.5%, respectively. There are significant differences among the three groups (χ(2) = 6.56, P < 0.03 and χ(2) = 5.45, P < 0.05), respectively. Nucleotide substitutions occurred at relatively high frequencies at exon 6 and exon 20 in obese and overweight breast cancer patients compared with those in normal weight breast cancer patients, there were significant differences (P < 0.05 and P < 0.01). CONCLUSIONS: Our findings show that there is no relationship between the variations of leptin receptor gene exon 9 and tumorigenesis of breast cancer. The variation rate of leptin receptor gene exon 6 and exon 20 are significantly increased in the obese and overweight breast cancer patients.

Fabrication of polypyrrole nanowire arrays-modified electrode for point-of-use water disinfection via low-voltage electroporation.

Still ∼10% of world's population has no sustainable access to centralized water supply system, causing millions of deaths annually by waterborne diseases. Here, we develop polypyrrole nanowire arrays (PPyNWs)-modified electrodes by polymerization of pyrrole on graphite felt for point-of-use water disinfection via low-voltage electroporation. A flow-through mode is specially applied to alleviate diffusion barrier of pyrrole in the porous graphite felt for uniform PPyNWs growth. The flow-through disinfection device using the optimized PPyNWs electrode achieves above 4-log removal for model virus (MS2) and gram-positive/negative bacteria (E. faecalis and E. coli) at applied voltage of 1.0 V and fluxes below 1000 and 2500 L/m2/h. Electroporation is recognized as the dominant disinfection mechanism by using square-wave alternating voltage of ±1.0 V to eliminate the electrochemical reactions. In-situ sampling experiments reveal that anode acts as the main disinfection function due to its electric field attraction with negatively charged E. coli cells. The live/dead baclight staining experiments indicate an adsorption-desorption process of E. coli cells on anode, and the adsorption-desorption balance determines the disinfection abilities of PPyNWs anode. Under 1.0 V and 2000 L/m2/h, the disinfection device enables above 4-log E. coli removal in tap water within 7-day operation with energy consumption below 20 mJ/L, suggesting its sound application potential for point-of-use water disinfection.

Cardiomyocyte-Specific RIP2 Overexpression Exacerbated Pathologic Remodeling and Contributed to Spontaneous Cardiac Hypertrophy.

This study aimed to investigate the role and mechanisms of Receptor interacting protein kinase 2 (RIP2) in pressure overload-induced cardiac remodeling. Human failing or healthy donor hearts were collected for detecting RIP2 expression. RIP2 cardiomyocyte-specific overexpression, RIP2 global knockout, or wild-type mice were subjected to sham or aortic banding (AB) surgery to establish pressure overload-induced cardiac remodeling in vivo. Phenylephrine (PE)-treated neonatal rat cardiomyocytes (NRCMs) were used for further investigation in vitro. The expression of RIP2 was significantly upregulated in failing human heart, mouse remodeling heart, and Ang II-treated NRCMs. RIP2 overexpression obviously aggravated pressure overload-induced cardiac remodeling. Mechanistically, RIP2 overexpression significantly increased the phosphorylation of TAK1, P38, and JNK1/2 and enhanced IκBα/p65 signaling pathway. Inhibiting TAK1 activity by specific inhibitor completely prevented cardiac remodeling induced by RIP2 overexpression. This study further confirmed that RIP2 overexpression in NRCM could exacerbate PE-induced NRCM hypertrophy and TAK1 silence by specific siRNA could completely rescue RIP2 overexpression-mediated cardiomyocyte hypertrophy. Moreover, this study showed that RIP2 could bind to TAK1 in HEK293 cells, and PE could promote their interaction in NRCM. Surprisingly, we found that RIP2 overexpression caused spontaneous cardiac remodeling at the age of 12 and 18 months, which confirmed the powerful deterioration of RIP2 overexpression. Finally, we indicated that RIP2 global knockout attenuated pressure overload-induced cardiac remodeling via reducing TAK1/JNK1/2/P38 and IκBα/p65 signaling pathways. Taken together, RIP2-mediated activation of TAK1/P38/JNK1/2 and IκBα/p65 signaling pathways played a pivotal role in pressure overload-induced cardiac remodeling and spontaneous cardiac remodeling induced by RIP2 overexpression, and RIP2 inhibition might be a potential strategy for preventing cardiac remodeling.

Critical roles of macrophages in pressure overload-induced cardiac remodeling.

Macrophages are integral components of the mammalian heart that show extensive expansion in response to various internal or external stimuli. After the onset of sustained pressure overload (PO), the accumulation of cardiac macrophages through local macrophage proliferation and monocyte migration has profound effects on the transition to cardiac hypertrophy and remodeling. In this review, we describe the heterogeneity and diversity of cardiac macrophages and summarize the current understanding of the important roles of macrophages in PO-induced cardiac remodeling. In addition, the possible mechanisms involved in macrophage modulation are also described. Finally, considering the significant effects of cardiac macrophages, we highlight their emerging role as therapeutic targets for alleviating pathological cardiac remodeling after PO.

Toll-like receptor 5 deficiency diminishes doxorubicin-induced acute cardiotoxicity in mice.

Rationale: Clinical application of doxorubicin (DOX) is limited by its toxic cardiovascular side effects. Our previous study found that toll-like receptor (TLR) 5 deficiency attenuated cardiac fibrosis in mice. However, the role of TLR5 in DOX-induced cardiotoxicity remains unclear. Methods: To further investigate this, TLR5-deficient mice were subjected to a single intraperitoneal injection of DOX to mimic an acute model. Results: Here, we reported that TLR5 expression was markedly increased in response to DOX injection. Moreover, TLR5 deficiency exerted potent protective effects against DOX-related cardiac injury, whereas activation of TLR5 by flagellin exacerbated DOX injection-induced cardiotoxicity. Mechanistically, the effects of TLR5 were largely attributed to direct interaction with spleen tyrosine kinase to activate NADPH oxidase (NOX) 2, increasing the production of superoxide and subsequent activation of p38. The toxic effects of TLR5 activation in DOX-related acute cardiac injury were abolished by NOX2 deficiency in mice. Our further study showed that neutralizing antibody-mediated TLR5 depletion also attenuated DOX-induced acute cardiotoxicity. Conclusion: These findings suggest that TLR5 deficiency attenuates DOX-induced cardiotoxicity in mice, and targeting TLR5 may provide feasible therapies for DOX-induced acute cardiotoxicity.

FNDC5 alleviates oxidative stress and cardiomyocyte apoptosis in doxorubicin-induced cardiotoxicity via activating AKT.

Oxidative stress and cardiomyocyte apoptosis play critical roles in doxorubicin (DOX)-induced cardiotoxicity. Previous studies indicated that fibronectin type III domain-containing 5 (FNDC5) and its cleaved form, irisin, could preserve mitochondrial function and attenuate oxidative damage as well as cell apoptosis, however, its role in DOX-induced cardiotoxicity remains unknown. Our present study aimed to investigate the role and underlying mechanism of FNDC5 on oxidative stress and cardiomyocyte apoptosis in DOX-induced cardiotoxicity. Cardiomyocyte-specific FNDC5 overexpression was achieved using an adeno-associated virus system, and then the mice were exposed to a single intraperitoneal injection of DOX (15 mg/kg) to generate DOX-induced cardiotoxicity. Herein, we found that FNDC5 expression was downregulated in DOX-treated murine hearts and cardiomyocytes. Fndc5 deficiency resulted in increased oxidative damage and apoptosis in H9C2 cells under basal conditions, imitating the phenotype of DOX-induced cardiomyopathy in vitro, conversely, FNDC5 overexpression or irisin treatment alleviated DOX-induced oxidative stress and cardiomyocyte apoptosis in vivo and in vitro. Mechanistically, we identified that FNDC5/Irisin activated AKT/mTOR signaling and decreased DOX-induced cardiomyocyte apoptosis, and moreover, we provided direct evidence that the anti-oxidant effect of FNDC5/Irisin was mediated by the AKT/GSK3ß/FYN/Nrf2 axis in an mTOR-independent manner. And we also demonstrated that heat shock protein 20 was responsible for the activation of AKT caused by FNDC5/Irisin. In line with the data in acute model, we also found that FNDC5/Irisin exerted beneficial effects in chronic model of DOX-induced cardiotoxicity (5 mg/kg, i.p., once a week for three times, the total cumulative dose is 15 mg/kg) in mice. Based on these findings, we supposed that FNDC5/Irisin was a potential therapeutic agent against DOX-induced cardiotoxicity.

The Roles of Noncardiomyocytes in Cardiac Remodeling.

Cardiac remodeling is a common characteristic of almost all forms of heart disease, including cardiac infarction, valvular diseases, hypertension, arrhythmia, dilated cardiomyopathy and other conditions. It is not merely a simple outcome induced by an increase in the workload of cardiomyocytes (CMs). The remodeling process is accompanied by abnormalities of cardiac structure as well as disturbance of cardiac function, and emerging evidence suggests that a wide range of cells in the heart participate in the initiation and development of cardiac remodeling. Other than CMs, there are numerous noncardiomyocytes (non-CMs) that regulate the process of cardiac remodeling, such as cardiac fibroblasts and immune cells (including macrophages, lymphocytes, neutrophils, and mast cells). In this review, we summarize recent knowledge regarding the definition and significant effects of various non-CMs in the pathogenesis of cardiac remodeling, with a particular emphasis on the involved signaling mechanisms. In addition, we discuss the properties of non-CMs, which serve as targets of many cardiovascular drugs that reduce adverse cardiac remodeling.

Meteorin-like protein attenuates doxorubicin-induced cardiotoxicity via activating cAMP/PKA/SIRT1 pathway.

Meteorin-like (METRNL) protein is a newly identified myokine that functions to modulate energy expenditure and inflammation in adipose tissue. Herein, we aim to investigate the potential role and molecular basis of METRNL in doxorubicin (DOX)-induced cardiotoxicity. METRNL was found to be abundantly expressed in cardiac muscle under physiological conditions that was decreased upon DOX exposure. Cardiac-specific overexpression of METRNL by adeno-associated virus serotype 9 markedly improved oxidative stress, apoptosis, cardiac dysfunction and survival status in DOX-treated mice. Conversely, knocking down endogenous METRNL by an intramyocardial injection of adenovirus exacerbated DOX-induced cardiotoxicity and death. Meanwhile, METRNL overexpression attenuated, while METRNL silence promoted oxidative damage and apoptosis in DOX-treated H9C2 cells. Systemic METRNL depletion by a neutralizing antibody aggravated DOX-related cardiac injury and dysfunction in vivo, which were notably alleviated by METRNL overexpression within the cardiomyocytes. Besides, we detected robust METRNL secretion from isolated rodent hearts and cardiomyocytes, but to a less extent in those with DOX treatment. And the beneficial effects of METRNL in H9C2 cells disappeared after the incubation with a METRNL neutralizing antibody. Mechanistically, METRNL activated SIRT1 via the cAMP/PKA pathway, and its antioxidant and antiapoptotic capacities were blocked by SIRT1 deficiency. More importantly, METRNL did not affect the tumor-killing action of DOX in 4T1 breast cancer cells and tumor-bearing mice. Collectively, cardiac-derived METRNL activates SIRT1 via cAMP/PKA signaling axis in an autocrine manner, which ultimately improves DOX-elicited oxidative stress, apoptosis and cardiac dysfunction. Targeting METRNL may provide a novel therapeutic strategy for the prevention of DOX-associated cardiotoxicity.

Corosolic acid attenuates cardiac fibrosis following myocardial infarction in mice.

Corosolic acid (CRA) is a pentacyclic triterpenoid isolated from Lagerstroemia speciosa. The aim of the present study was to determine whether CRA reduces cardiac remodelling following myocardial infarction (MI) and to elucidate the underlying mechanisms. C57BL/6J mice were randomly divided into control (PBS­treated) or CRA­treated groups. After 14 days of pre­treatment, the mice were subjected to either sham surgery or permanent ligation of the left anterior descending artery. Following surgery, all animals were treated with PBS or CRA (10 or 20 mg/kg/day) for 4 weeks. After 4 weeks, echocardiographic, haemodynamic, gravimetric, histological and biochemical analyses were conducted. The results revealed that, upon MI, mice with CRA treatment exhibited decreased mortality rates, improved ventricular function and attenuated cardiac fibrosis compared with those in control mice. Furthermore, CRA treatment resulted in reduced oxidative stress, inflammation and apoptosis, as well as inhibited the transforming growth factor ß1/Smad signalling pathway activation in cardiac tissue. In vitro studies further indicated that inhibition of AMP­activated protein kinase α (AMPKα) reversed the protective effect of CRA. In conclusion, the study revealed that CRA attenuated MI­induced cardiac fibrosis and dysfunction through modulation of inflammation and oxidative stress associated with AMPKα.