Lipopolysaccharide induces cellular hypertrophy through calcineurin/NFAT-3 signaling pathway in H9c2 myocardiac cells

Enhanced IGF-IIRα Expression Exacerbates Lipopolysaccharide-Induced Cardiac Inflammation, Hypertrophy, and Apoptosis Through Calcineurin Activation

Cardiovascular disease is one of the leading causes of death worldwide and has a high prevalence. Insulin-like growth factor-II receptor α (IGF-IIRα) acts as a stress-inducible negative regulator. This study focused on the substantial impact of heightened expression of IGF-IIRα in cardiac myoblasts and its association with the exacerbation of cardiac dysfunction. Using lipopolysaccharide (LPS)-induced H9c2 cardiac myoblasts as a model for sepsis, we aimed to elucidate the molecular interactions between IGF-IIRα and LPS in exacerbating cardiac injury. Our findings demonstrated a synergistic induction of cardiac inflammation and hypertrophy by LPS stimulation and IGF-IIRα overexpression, leading to decreased cell survival. Excessive calcineurin activity, triggered by this combined condition, was identified as a key factor exacerbating the negative effects on cell survival. Cellular changes such as cell enlargement, disrupted actin filaments, and upregulation of hypertrophy-related and inflammation-related proteins contributed to the overall hypertrophic and inflammatory responses. Overexpression of IGF-IIRα also exacerbated apoptosis induced by LPS in H9c2 cardiac myoblasts. Inhibiting calcineurin in LPS-treated H9c2 cardiac myoblasts with IGF-IIRα overexpression effectively reversed the detrimental effects, reducing cell damage and mitigating apoptosis-related cardiac mechanisms. Our study suggests that under sepsis-like conditions in the heart with IGF-IIRα overexpression, hyperactivation of calcineurin worsens cardiac damage. Suppressing IGF-IIRα and calcineurin expression could be a potential intervention to alleviate the impact of the illness and improve cardiac function.

Cytochrome P450 1B1 is critical in the development of TNF-α, IL-6, and LPS-induced cellular hypertrophy

Heart failure (HF) is preceded by cellular hypertrophy (CeH) which alters expression of cytochrome P450 enzymes (CYPs) and arachidonic acid (AA) metabolism. Inflammation is involved in CeH pathophysiology, but mechanisms remain elusive. This study investigates the impacts of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and lipopolysaccharides (LPS) on the development of CeH and the role of CYP1B1. AC16 cells were treated with TNF-α, IL-6, and LPS in the presence and absence of CYP1B1-siRNA or resveratrol. mRNA and protein expression levels of CYP1B1 and hypertrophic markers were determined using PCR and Western blot analysis, respectively. CYP1B1 enzyme activity was determined, and AA metabolites were analyzed using liquid chromatography-tandem mass spectrometry. Our results show that TNF-α, IL-6, and LPS induce expression of hypertrophic markers, induce CYP1B1 expression, and enantioselectively modulate CYP1B1-mediated AA metabolism in favor of mid-chain HETEs. CYP1B1-siRNA or resveratrol ameliorated these effects. In conclusion, our results demonstrate the crucial role of CYP1B1 in TNF-α, IL-6, and LPS-induced CeH.

Review on the protective mechanism of astragaloside IV against cardiovascular diseases

Cardiovascular disease is a global health problem. Astragaloside IV (AS-IV) is a saponin compound extracted from the roots of the Chinese herb Astragalus. Over the past few decades, AS-IV has been shown to possess various pharmacological properties. It can protect the myocardium through antioxidative stress, anti-inflammatory effects, regulation of calcium homeostasis, improvement of myocardial energy metabolism, anti-apoptosis, anti-cardiomyocyte hypertrophy, anti-myocardial fibrosis, regulation of myocardial autophagy, and improvement of myocardial microcirculation. AS-IV exerts protective effects on blood vessels. For example, it can protect vascular endothelial cells through antioxidative stress and anti-inflammatory pathways, relax blood vessels, stabilize atherosclerotic plaques, and inhibit the proliferation and migration of vascular smooth muscle cells. Thus, the bioavailability of AS-IV is low. Toxicology indicates that AS-IV is safe, but should be used cautiously in pregnant women. In this paper, we review the mechanisms of AS-IV prevention and treatment of cardiovascular diseases in recent years to provide a reference for future research and drug development.

Putting human Tid-1 in context: an insight into its role in the cell and in different disease states

Background

Tumorous imaginal disc 1 (hTid-1) or DnaJ homolog subfamily A member 3 (DNAJA3), is a part of the heat shock protein (Hsp) 40 family and is predominantly found to reside in the mitochondria. hTid-1 has two mRNA splicing variants, hTid-1S and hTid-1L of 40 and 43 kDa respectively in the cytosol which are later processed upon import into the mitochondrial matrix. hTid-1 protein is a part of the DnaJ family of proteins which are co-chaperones and specificity factors for DnaK proteins of the Hsp70 family, and bind to Hsp70, thereby activating its ATPase activity. hTid-1 has been found to be critical for a lot of important cellular processes such as proliferation, differentiation, growth, survival, senescence, apoptosis, and movement and plays key roles in the embryo and skeletal muscle development.

Main body

hTid-1 participates in several protein–protein interactions in the cell, which mediate different processes such as proteasomal degradation and autophagy of the interacting protein partners. hTid-1 also functions as a co-chaperone and participates in interactions with several different viral oncoproteins. hTid-1 also plays a critical role in different human diseases such as different cancers, cardiomyopathies, and neurodegenerative disorders.

Conclusion

This review article is the first of its kind presenting consolidated information on the research findings of hTid-1 to date. This review suggests that the current knowledge of the role of hTid-1 in disorders like cancers, cardiomyopathies, and neurodegenerative diseases can be correlated with the findings of its protein–protein interactions that can provide a deep insight into the pathways by which hTid-1 affects disease pathogenesis and it can be stated that hTid-1 may serve as an important therapeutic target for these disorders.

Graphical Abstract

The Prevention Role of Theaflavin-3,3'-digallate in Angiotensin II Induced Pathological Cardiac Hypertrophy via CaN-NFAT Signal Pathway

Theaflavin-3,3'-digallate (TF3) is a representative theaflavin of black tea and is remarkable for the anti-coronary heart disease effect. As an adaptive response to heart failure, pathological cardiac hypertrophy (PCH) has attracted great interest. In this study, the PCH cell model was established with H9c2 cells by angiotensin II, and the prevention effect and mechanisms of TF3 were investigated. The results showed that the cell size and fetal gene mRNA level were significantly reduced as pretreated with TF3 at the concentration range of 1-10 μM, also the balance of the redox system was recovered by TF3 at the concentration of 10 μM. The intracellular Ca2+ level decreased, Calcineurin (CaN) expression was down-regulated and the p-NFATc3 expression was up-regulated. These results indicated that TF3 could inhibit the activation of the CaN-NFAT signal pathway to prevent PCH, and TF3 may be a potentially effective natural compound for PCH and heart failure.

Ginsenoside Rg1 attenuates mechanical stress-induced cardiac injury via calcium sensing receptor-related pathway

Background

Ginsenoside Rg1 (Rg1) has been well documented to be effective against various cardiovascular disease. The aim of this study is to evaluate the effect of Rg1 on mechanical stress-induced cardiac injury and its possible mechanism with a focus on the calcium sensing receptor (CaSR) signaling pathway.

Methods

Mechanical stress was implemented on rats through abdominal aortic constriction (AAC) procedure and on cardiomyocytes and cardiac fibroblasts by mechanical stretching with Bioflex Collagen I plates. The effects of Rg1 on cell hypertrophy, fibrosis, cardiac function, [Ca²⁺]_i, and the expression of CaSR and calcineurin (CaN) were assayed both on rat and cellular level.

Results

Rg1 alleviated cardiac hypertrophy and fibrosis, and improved cardiac decompensation induced by AAC in rat myocardial tissue and cultured cardiomyocytes and cardiac fibroblasts. Importantly, Rg1 treatment inhibited CaSR expression and increase of [Ca²⁺]_i, which similar to the CaSR inhibitor NPS2143. In addition, Rg1 treatment inhibited CaN and TGF-β1 pathways activation. Mechanistic analysis showed that the CaSR agonist GdCl₃ could not further increase the [Ca²⁺]_i and CaN pathway related protein expression induced by mechanical stretching in cultured cardiomyocytes. CsA, an inhibitor of CaN, inhibited cardiac hypertrophy, cardiac fibrosis, [Ca²⁺]_i and CaN signaling but had no effect on CaSR expression.

Conclusion

The activation of CaN pathway and the increase of [Ca²⁺]_i mediated by CaSR are involved in cardiac hypertrophy and fibrosis, that may be the target of cardioprotection of Rg1 against myocardial injury.

Helium Protects Against Lipopolysaccharide-Induced Cardiac Dysfunction in Mice via Suppressing Toll-Like Receptor 4-Nuclear Factor κB-Tumor Necrosis Factor-Alpha/ Interleukin-18 Signaling

The nonanesthetic noble gas helium (He) can protect many organs against ischemia and reperfusion injury, such as liver and heart. However, the role of He on cardiac dysfunction during sepsis is not clear. In this study, we established a lipopolysaccharide (LPS)-induced cardiac dysfunction mouse model to examine the influence of He on the impaired cardiac function, and further investigated the possible innate immune mechanisms that may be involved. LPS induced left ventricular dysfunction and cavity enlargement, as indicated by decreased percent ejection fraction, percent fractional shortening, left ventricular anterior wall thickness in systole, and left ventricular posterior wall thickness in systole, while increased left ventricular end-systolic diameter and left ventricular end-systolic volume. He improved the impaired left ventricular function and cavity enlargement in a dose-dependent manner, and it was beneficial at 1.0 mL/100 g. Mechanistically, He inhibited toll-like receptor 4 (TLR4) expression, reduced the phosphorylation of nuclear factor κB (NF-κB), and subsequently alleviated tumor necrosis factor-alpha (TNF-α) and interleukin-18 (IL-18) expression in heart. Therefore, He protects against LPS-induced cardiac dysfunction in mice partially via inhibiting myocardial TLR4-NF-κB-TNF-α/IL-18 signaling.

Sulfated N-acetylglucosamino-glucuronopyranosyl-arabinopyranan from seafood Amphioctopus neglectus attenuates angiotensin-II prompted cardiac hypertrophy

Angiotensin converting enzyme (ACE) is a multifunctional enzyme involved in translation of angiotensin-I (Ang^I) to vasoconstrictor angiotensin-II (Ang^II). A sulfated N-acetylglucosamino-glucuronopyranosyl-arabinopyranan characterized as poly-[(2-methoxy-β-arabinopyranosyl)-(1 → 3)-(β-glucurono)-(1 → 4)-(2-acetamido-2-deoxy-3,6-di-O-sulfonato-β-glucopyranose)] was purified and reported first time from the edible portion of Amphioctopus neglectus and evaluated for various pharmacological properties. The polysaccharide exhibited potential ACE attenuation property (IC₅₀ 0.11 mg mL^-1), whereas molecular docking simulations displayed its efficient binding at the ACE active site with lesser inhibitory constant (K_i) of 17.36 nM and binding energy (-10.59 kcal mol^-1). The in-vitro analysis showed that the studied polysacharide attenuated Ang^II prompted cardiac hypertrophy at 50 μg mL^-1 in the cardiomyoblast cells, whereas 48% reduction in cellular surface area with extended viability could be correlated with anti-hypertrophic properties of the studied polysaccharide. The sulfated N-acetylglucosamino-glucuronopyranosyl-arabinopyranan purified from A. neglectus could function as a prospective functional lead against the pathophysiological conditions leading to hypertension.

Calcium inhibitor inhibits high glucose‑induced hypertrophy of H9C2 cells

The aim of the present study was to explore whether the hypertrophy of H9C2 cardiomyocytes was induced by high glucose, to investigate whether the calcium channel inhibitor (Norvasc) could inhibit this process and to clarify the possible signaling pathways. The morphology of H9C2 cells was observed under an optical microscope, and the cell surface area was measured by Image Pro Plus 6.1 software. Furthermore, fluorescence spectrophotometry was used to detect intracellular calcium concentration ([Ca²⁺]i). ELISA was performed to detect calcineurin (CaN) activity; reverse transcription-quantitative PCR and western blotting were performed to detect the mRNA and protein expression levels of CaN Aβ subunit (CnAβ), nuclear factor of activated T cells 3 (NFAT3) and β type myosin heavy chain (β-MHC). Cell size was increased with the increase in glucose concentration of culture medium at 48 and 72 h, respectively, and decreased with the addition of Norvasc compared with those without Norvasc (P<0.05). There was no significant difference in cell size with the addition of Norvasc compared with cells cultured with 5 mM glucose (P>0.05). The average [Ca²⁺]i activity of single cells in the 48- and 72-h culture groups treated with 50 mM glucose was significantly higher than cells treated with 5 mM glucose (P<0.05); and the fluorescent value of average [Ca²⁺]i activity of single cells was lower, following the addition of Norvasc than that without Norvasc (P<0.05). CaN activity in the 48- and 72-h culture group treated with 50 mM glucose was markedly higher than that treated with 5 mM glucose, and the activity of CaN notably decreased with the addition of Norvasc compared with those without Norvasc. The mRNA and protein expression levels of CnAβ, NFAT3 and β-MHC in the 48- and 72-h culture groups treated with 50 mM glucose were all significantly higher than those treated with 5 mM glucose (P<0.05). The mRNA and protein expression of CnAβ, NFAT3 and β-MHC cultured with 50 mM glucose were significantly decreased following the addition of Norvasc (P<0.05). Thus, the calcium channel inhibitor Norvasc may inhibit high glucose-induced hypertrophy of H9C2 cardiomyocytes by inhibiting the Ca²⁺-CaN-NFAT3 signaling pathway.

Repurposing an old drug for new use: Niclosamide in psoriasis-like skin inflammation

Drug discovery is an onerous, extremely expensive, and time-consuming process. Instead, drug repurposing is an attractive strategy for exploiting novel indications for a drug beyond its original use. The untapped potential of drug repurposing compensates the barriers associated with the drug discovery pipeline. Psoriasis is an autoimmune skin disease, where hyperproliferation of keratinocytes and exaggerated immune responses are the important hallmarks of the disease. Extensive in vitro and preclinical research has demonstrated that niclosamide was found to exert potent anticancer and anti-inflammatory properties by targeting STAT3, p65 NF-κB, and NFATc-1 signaling paradigm with minimal host toxicity. From the disease perspective, the static intracellular molecular network in both cancer and psoriasis share overlapping pathological features in terms of hyperproliferation and chronic inflammation, which is mediated by the aforementioned signaling cascade. The plausible mechanistic relevance has prompted us to investigate the implementation of niclosamide for repositioning in psoriasis. Our in vitro and in vivo findings suggest that niclosamide inhibits keratinocytes hyperproliferation by reactive oxygen species-mediated apoptosis through the loss of mitochondrial membrane potential, cell cycle arrest at Sub G1 phase, and DNA fragmentation. Furthermore, niclosamide treatment resulted in abrogation of lipopolysaccharide-induced inflammatory cytokine levels in murine macrophages. Additionally, our results provided a preclinical rationale in imiquimod (IMQ)-induced BALB/c mouse model, where niclosamide diligently mitigated the IMQ-induced epidermal hyperplasia and inflammation by downregulating STAT3, p65 NF-κB, and NFATc-1 transcription factors along with Akt, Ki-67, and ICAM-1 protein expression.

H2 Protects Against Lipopolysaccharide-Induced Cardiac Dysfunction via Blocking TLR4-Mediated Cytokines Expression

Background and Purpose: Septic cardiomyopathy, which is one of the features of multi-organ dysfunction in sepsis, is characterized by ventricular dilatation, reduced ventricular contractility, and reduction in ejection fraction and, if severe, can lead to death. To date, there is no specific therapy that exists, and its treatment represents a large unmet clinical need. Herein, we investigated the effects and underlying anti-inflammatory mechanisms of hydrogen gas in the setting of lipopolysaccharide (LPS)-induced cardiomyocytes injury.

Experimental Approach: Hydrogen gas was intraperitoneally injected to mice in LPS plus hydrogen group and hydrogen group for 4 days. On fourth, LPS was given by intraperitoneal injection to mice in LPS group and to mice in LPS plus hydrogen group. In addition, H9c2 cardiomyocytes were treated with hydrogen-rich medium for 30 min before LPS. The transthoracic echocardiography was performed at 6 h post‐LPS to assess left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD), left ventricular ejection fraction (EF%), fractional shortening (FS%), left ventricular mass average weight (LV mass AW), and LV mass AW (Corrected). The histological and morphological analyses of left ventricular were performed by hematoxylin and eosin (H&E) staining and Masson’s trichrome staining. The mRNA levels of ANP and BNP were examined by PCR in vitro. The expression of cytokines were assayed by Enzyme Linked Immunosorbent Assay (ELISA) and PCR. Moreover, Western blotting was performed to examine the expression of TLR4, the activation of ERK1/2, p38, JNK, and the expression of NF-κB in nucleus after 6 h of LPS challenge in vivo and in vitro.

Key Results: LPS induced cardiac dysfunction; hydrogen therapy improved cardiac function after LPS challenge. Furthermore, pretreatment with hydrogen resulted in cardioprotection during septic cardiomyopathy via inhibiting the expression of pro-inflammatory cytokines TNFα, IL-1β, and IL-18; suppressing the phosphorylation of ERK1/2, p38, and JNK; and reducing the nuclear translocation of NF-κB and the expression of TLR4 by LPS.

Conclusion and Implications: Hydrogen therapy prevents LPS-induced cardiac dysfunction in part via downregulation of TLR4-mediated pro-inflammatory cytokines expression.

Lipopolysaccharide-induced DNA damage response activates nuclear factor κB signalling pathway via GATA4 in dental pulp cells

AIM

To investigate the role of GATA-binding protein 4 (GATA4) in the inflammatory response induced by DNA double-strand breaks (DSBs) in human dental pulp cells (hDPCs).

METHODOLOGY

Lipopolysaccharide (LPS) was used for stimulating inflammation in dental pulp tissue in vivo and hDPCs in vitro. Expression levels of GATA4 and γ-H2A.X (a marker for DSBs) were detected at different stages of pulpitis in a rat model and human pulp tissues by immunohistochemistry. Real-time quantitative polymerase chain reaction and Western blot were performed to assess expression of GATA4 and γ-H2A.X and the activation of nuclear factor κB (NF-κB) in hDPCs stimulated by LPS. The comet assay was used for detecting the extent of DSBs in hDPCs. Immunocytochemistry and Western blot were utilized to evaluate expression of γ-H2A.X and GATA4 and activation of NF-κB in hDPCs pre-treated with inhibitors of DNA damage response or transfected with GATA4 small interfering RNA before the treatment of LPS. Data were analysed statistically using one-way anova or Kruskal-Wallis tests.

RESULTS

The expression of GATA4 and activation of DNA damage response and NF-κB in inflamed pulp tissue and LPS-treated hDPCs were identified. Significantly decreased expression of GATA4 and significantly decreased inflammatory processes in hDPCs were demonstrated via suppression of DNA damage response (P < 0.05). In GATA4-knockdown cells, the expression of γ-H2A.X did not change, but nuclear translocation of p65 was significantly suppressed (P < 0.05) upon induction by LPS.

CONCLUSIONS

Lipopolysaccharide-induced DSBs activated the NF-κB signalling pathway in hDPCs, and GATA4 acts as a positive moderator of the progress. The involvement of GATA4 in this pathology may serve as a therapeutic target in pulpitis.

Tid1-S attenuates LPS-induced cardiac hypertrophy and apoptosis through ER-a mediated modulation of p-PI3K/p-Akt signaling cascade

Myocardial dysfunction is clinically relevant? repercussion that follows sepsis. Tid 1 protein has been implicated in many biological process. However, the role of Tid 1 in lipopolysaccharide (LPS)-induced cardiomyocyte hypertrophy and apoptosis remains elusive. In the current research endeavor, we have elucidated the role of Tid1-S on LPS-induced cardiac hypertrophy and apoptosis. Interestingly, we found that overexpression of Tid1-S suppressed TLR-4, NFATc3, and BNP protein expression which eventually led to inhibition of LPS-induced cardiac hypertrophy. Moreover, Tid1-S overexpression attenuated cellular apoptosis and activated survival proteins p-PI3K and p^ser473 Akt. Besides this, Tid1-S overexpression enhanced ER-a protein expression. Collectively, our data suggest that Tid1-S plausibly enhance ER-a protein and further activate p-PI3K and p ^ser473 Akt survival protein expression; which thereby led to attenuation of LPS-induced apoptosis in cardiomyoblast cells. Interestingly, our data suggest that Tid1-S is involved in attenuation of cardiomyoblast cells damages induced by LPS.

ERK1/2 mediates the lipopolysaccharide-induced upregulation of FGF-2, uPA, MMP-2, MMP-9 and cellular migration in cardiac fibroblasts

Myocardial fibrosis is a critical event during septic shock. Upregulation in the fibrosis signaling cascade proteins such as fibroblast growth factor (FGF), urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA) and activation of matrix metalloproteinases (MMPs) are widely associated with the development of myocardial infarction, dilated cardiomyopathy, cardiac fibrosis and heart failure. However, evidences suggest that the common upstream mediators of fibrosis cascade play little role in cardiac fibrosis induced by LPS; further, it is unknown if LPS directly triggers the expressions and/or activity of FGF-2, uPA, tPA, MMP-2 and MMP-9 in cardiac fibroblasts. In the present study, we treated primary cultures of cardiac fibroblasts with LPS to explore whether LPS upregulates FGF-2, uPA, tPA, MMP-2, MMP-9 and enhance cellular migration. Further the precise molecular and cellular mechanisms behind these LPS induced responses were identified. Inhibition assays on MAPKs using U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor), CsA (calcineurin inhibitor) and QNZ (NFκB inhibitor) show that LPS-induced upregulation of FGF-2, uPA, MMP-2 and MMP-9 in cardiac fibroblasts was mediated through ERK1/2 signaling. Collectively, our results provide a link between LPS-induced cardiac dysfunction and ERK1/2 signaling pathway and thereby implies ERK1/2 as a possible target to regulate LPS induced upregulation of FGF-2, uPA, MMP-2, MMP-9 and cellular migration in cardiac fibroblasts.

Luteolin suppresses lipopolysaccharide‑induced cardiomyocyte hypertrophy and autophagy in vitro

Luteolin (LTL) serves essential roles in a wide variety of biological processes. Lipopolysaccharide (LPS) can lead to myocardial hypertrophy and autophagy. However, the roles of LTL on LPS-induced cardiomyocyte hypertrophy and autophagy in rat cardiomyocytes have not yet been fully elucidated. In the present study, the morphology of cultured rat cardiomyocytes was observed under an inverted microscope. Cell viability was detected by MTT assay. α-Actinin and microtubule-associated protein 1 light chain 3 (LC3) expression levels were measured by immunofluorescence assay. In addition, the expression levels of atrial natriuretic peptide/brain natriuretic peptide (ANP/BNP), LC3, and autophagy- and Wnt signaling pathway-associated genes were analyzed by reverse transcription-quantitative polymerase chain reaction or western blot assays. The results indicated that LTL increased the cell viability of cardiomyocytes treated with LPS. LTL decreased the expression of cardiac hypertrophy associated markers (ANP and BNP). LTL decreased α-actinin and LC3 expression levels in LPS-treated cardiomyocytes. It was also demonstrated that LTL suppressed the mRNA and protein expression levels of LPS-mediated autophagy and Wnt signaling pathway-associated genes. In addition, it was demonstrated that silencing of β-catenin inhibited LPS-induced cardiomyocyte hypertrophy and the formation of autophagosomes. Thus, the present study suggested that LTL protected against LPS-induced cardiomyocyte hypertrophy and autophagy in rat cardiomyocytes.

[Mitochondrial aldehyde dehydrogenase 2 protects against high glucose-induced injury in neonatal rat cardiomyocytes by regulating CaN-NFAT3 signaling pathway]

OBJECTIVE

To investigate whether CaN-NFAT3 pathway mediates the protective effects of aldehyde dehydrogenase (ALDH) 2 in high glucose-treated neonatal rat ventricular myocytes.

METHODS

The ventricular myocytes were isolated from the heart of neonatal (within 3 days) SD rats by enzyme digestion and cultured in the presence of 5-Brdu. After reaching confluence, the cultured ventricular myocytes were identified using immunofluorescence assay for α-SA protein. The cells were then cultured in either normal (5 mmol/L) or high glucose (30 mmol/L) medium in the presence of ALDH2 agonist Alda-1, ALDH 2 inhibitor Daidzin, or Alda-1 and NFAT3 inhibitor (11R-VIVIT). Fluorescent probe and ELISA were used to detect intracellular Ca²⁺ concentration and CaN content, respectively; ALDH2, CaN and NFAT3 protein expressions in the cells were detected using Western blotting.

RESULTS

Compared with cells cultured in normal glucose, the cells exposed to high glucose showed a significantly decreased expression of ALDH2 protein (P &lt; 0.05) and increased expressions of CaN (P &lt; 0.05) and NFAT3 proteins with also increased intracellular CaN and Ca²⁺ concentrations (P &lt; 0.01). Alda-1 treatment significantly lowered Ca²⁺ concentration (P &lt; 0.05), intracellular CaN content (P &lt; 0.01), and CaN and NFAT3 protein expressions (P &lt; 0.05), and increased ALDH2 protein expression (P &lt; 0.05) in high glucose- exposed cells; Daidzin treatment significantly increased Ca²⁺ concentration (P &lt; 0.01) and intracellular CaN content (P &lt; 0.05) in the exposed cells. Compared with Alda-1 alone, treatment of the high glucose-exposed cells with both Alda-1 and 11R-VIVIT did not produce significant changes in the expression of ALDH2 protein (P&gt;0.05) but significantly reduced the expression of NFAT3 protein (P &lt; 0.05).

CONCLUSIONS

Mitochondrial ALDH2 protects neonatal rat cardiomyocytes against high glucose-induced injury possibly by negatively regulating Ca²⁺-CaN-NFAT3 signaling pathway.

17β-Estradiol and/or estrogen receptor alpha signaling blocks protein phosphatase 1 mediated ISO induced cardiac hypertrophy

Earlier studies have shown that estrogen possess protective function against the development of pathological cardiac hypertrophy. However, the molecular mechanisms of estrogens (E2) protective effect are poorly understood. Additionally, abnormal activation of β-adrenergic signaling have been implicated in the development of pathological cardiac remodeling. However, the role of serine/threonine protein phosphatase 1 (PP1) in pathological cardiac remodeling under the influence of β-adrenergic signaling have been sparsely investigated. In this study, we assessed the downstream effects of abnormal activation of PP1 upon isoproterenol (ISO) induced pathological cardiac changes. We found that pre-treatment of 17β-estradiol (E2), tet-on estrogen receptor-α, or both significantly inhibited ISO-induced increase in cell size, hypertrophy marker gene expression and cytosolic calcium accumulation in H9c2 cells. Additionally, treatment with estrogen receptor inhibitor (ICI) reversed those effects, implicating role of E2 in inhibiting pathological cardiac remodeling. However, specific inhibition of ERα using melatonin, reduced ISO-induced PP1c expression and enhanced the level of ser-16 phosphorylated phospholamban (PLB), responsible for regulation of sarcoplasmic reticulum Ca²⁺-ATPase (SERCA) activity. Furthermore, hypertrophic effect caused by overexpression of PP1cα was reduced by treatment with specific inhibitor of ERα. Collectively, we found that estrogen and estrogen receptor-α have protective effect against pathological cardiac changes by suppressing PP1 expression and its downstream signaling pathway, which further needs to be elucidated.

Poly(ADP-ribose) polymerase 1 inhibition protects cardiomyocytes from inflammation and apoptosis in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is characterized by structural alterations such as cardiomyocyte hypertrophy, necrosis and focal fibrosis. Poly(ADP-ribose) polymerase 1 (PARP-1) is a nuclear enzyme which can be activated by DNA damage and plays a critical role in various diseases. We hypothesized that PARP-1 may play an important role in DCM and that its inhibition may protect cardiomyocytes from inflammation and apoptosis in DCM. H9c2 cardiomyocytes were treated with normal glucose, mannitol or high glucose (HG). Male C57BL/6 mice or PARP-1−/− mice were treated with streptozotocin (STZ) by intraperitoneal injection for 5 consecutive days to induce diabetes. In vitro, HG stimulation induced oxidative stress and DNA damage and increased PARP-1 expression and activity. Compared with the control, pretreatment with PARP-1 siRNA significantly reduced HG-induced inflammatory response, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 secretion, and intercellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase (iNOS) expression. PARP-1 inhibition reduced HG-induced cardiomyocyte apoptosis through downregulation of cleaved caspases and activation of IGF-1R/Akt pathway. In vivo, hyperglycemia increased the protein expression of nitrotyrosine and PARP-1 as well as PARP-1 activity. PARP-1 gene deletion significantly improved cardiac dysfunction and reduced inflammatory response and apoptosis. This work demonstrated the critical role of PARP-1 in diabetic heart injury, and suggested that PARP-1 inhibition may be a feasible strategy for the treatment of DCM.

E2/ER β inhibit ISO-induced cardiac cellular hypertrophy by suppressing Ca2+-calcineurin signaling

Cardiovascular incidences are markedly higher in men than in pre-menstrual women. However, this advantage in women declines with aging and therefore can be correlated with the sex hormone 17β-Estradiol (E2) which is reported to protect heart cells by acting though estrogen receptors (ERs). In this study we have determined the effect of E2/ERβ against ISO induced cellular hypertrophy in H9c2 cardiomyoblast cells. The results confirm that ISO induced cardiac-hypertrophy by elevating the levels of hypertrophy associated proteins, ANP and BNP and further by upregulating p-CaMKII, calcineurin, p-GATA4 and NFATc3 which was correlated with a significant enlargement of the H9c2 cardiomyoblast. However, overexpression of ERβ and/or administration of E2 inhibited ISO-induced hypertrophy in H9c2 cells. In addition, E2/ERβ also inhibited ISO-induced NFATc3 translocation, and reduced the protein level of downstream marker, BNP. Furthermore, by testing with the calcineurin inhibitor (CsA), it was confirmed that calcineurin acted as a key mediator for the anti-hypertrophic effect of E2/ERβ. In cells treated with calcium blocker (BATPA), the inhibitory effect of E2/ERβ on ISO-induced Ca²⁺ influx and hypertrophic effects were totally blocked suggesting that E2/ERβ inhibited calcineurin activity to activate I-1 protein and suppress PP1, then induce PLB protein phosphorylation and activation, resulting in Ca²⁺ reuptake into sarcoplasmic reticulum through SR Ca²⁺ cycling modification. In conclusion, E2/ERβ suppresses the Ca²⁺ influx and calcineurin activity induced by ISO to enhance the PLB protein activity and SR Ca²⁺ cycling.

Increased β-catenin accumulation and nuclear translocation are associated with concentric hypertrophy in cardiomyocytes

Defective Wnt/β-Catenin signaling, activated under various pathological conditions, can result in cardiac and vascular abnormalities. In the present study, the possible role of β-catenin over expression during cardiac hypertrophy was investigated. Ten samples from hearts of human patients with acute infarction, and granulation tissue from 20 patients and 10 from normal ones were collected in order to investigate roles of β-catenin in cardiac hypertrophy. H9c2 cardiomyoblast cells and Wistar rat primary neonatal cardiomyocytes were overexpressed with β-catenin. Expression levels of β-catenin protein were increased in human acute infarction tissues and rat hypertension heart tissues. Overexpression of this transcription factor induced actin filament formation and increased hypertrophic marker protein levels via MAPK pathway. In addition, β-catenin overexpression also resulted in increased elevation of NFATc3 and p-GATA4. Therefore, acute infarction resulted in β-catenin overexpression mediated hypertrophy in cardiomyocytes regulated through MAPK pathway.

Disequilibrium in the CD8+CD28+/CD8+CD28- T Lymphocyte Balance Is Related to Prognosis in Rats with Trinitrobenzenesulfonic Acid-Induced Colitis

PURPOSE

The CD8⁺CD28⁺/CD8⁺CD28^- T lymphocyte balance is vital for human ulcerative colitis (UC) but has not been defined in experimental colitis. This investigation will try to identify the changes that occur in the CD8⁺CD28⁺/CD8⁺CD28^- T lymphocyte balance during the progression of trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats.

METHODS

The frequencies of blood CD8⁺CD28⁺ and CD8⁺CD28^- T lymphocytes were detected in the rats belonging to the normal, model, and treated groups on five days using flow cytometry. The treated rats were administered with mesalazine and were euthanized after a 14-day treatment, as were the normal and model rats. The sensitivity and specificity of the CD8⁺CD28⁺/CD8⁺CD28^- T lymphocyte balance in diagnosing early colitis were analyzed by receiver operating characteristics (ROC) curves. The frequencies of CD8⁺CD28⁺ and CD8⁺CD28^- T lymphocytes in the colon tissue were tested via immunofluorescence. ELISA was used to measure the levels of the cytokines. Immunohistochemistry and Western blotting were used to detect the colonic expression of JAK3, STAT6, NFATc2, and GATA3.

RESULTS

We found that the ratio of CD8⁺CD28⁺/CD8⁺CD28^- T lymphocytes decreased, as did the level of interleukin-7, but not IL-12p40, IL-13, or IL-15, in the blood; however, the ratio increased along with JAK3, STAT6, NFATc2, and GATA3 in the colon of the rats with colitis. The changes were effectively reversed through the administration of mesalazine for 13 days. Surprisingly, the balance in the blood could sensitively distinguish rats with early colitis from normal rats.

CONCLUSION

These data show that increase in CD8⁺CD28⁺ T cells in blood and decrease in CD8⁺CD28^- T cells in colon are associated with experimental colitis.

The Emerging Roles of the Calcineurin-Nuclear Factor of Activated T-Lymphocytes Pathway in Nervous System Functions and Diseases

The ongoing epidemics of metabolic diseases and increase in the older population have increased the incidences of neurodegenerative diseases. Evidence from murine and cell line models has implicated calcineurin-nuclear factor of activated T-lymphocytes (NFAT) signaling pathway, a Ca²⁺/calmodulin-dependent major proinflammatory pathway, in the pathogenesis of these diseases. Neurotoxins such as amyloid-β, tau protein, and α-synuclein trigger abnormal calcineurin/NFAT signaling activities. Additionally increased activities of endogenous regulators of calcineurin like plasma membrane Ca²⁺-ATPase (PMCA) and regulator of calcineurin 1 (RCAN1) also cause neuronal and glial loss and related functional alterations, in neurodegenerative diseases, psychotic disorders, epilepsy, and traumatic brain and spinal cord injuries. Treatment with calcineurin/NFAT inhibitors induces some degree of neuroprotection and decreased reactive gliosis in the central and peripheral nervous system. In this paper, we summarize and discuss the current understanding of the roles of calcineurin/NFAT signaling in physiology and pathologies of the adult and developing nervous system, with an emphasis on recent reports and cutting-edge findings. Calcineurin/NFAT signaling is known for its critical roles in the developing and adult nervous system. Its role in physiological and pathological processes is still controversial. However, available data suggest that its beneficial and detrimental effects are context-dependent. In view of recent reports calcineurin/NFAT signaling is likely to serve as a potential therapeutic target for neurodegenerative diseases and conditions. This review further highlights the need to characterize better all factors determining the outcome of calcineurin/NFAT signaling in diseases and the downstream targets mediating the beneficial and detrimental effects.

Tropisetron inhibits high glucose-induced calcineurin/NFAT hypertrophic pathway in H9c2 myocardial cells

OBJECTIVES

Cardiomyocyte hypertrophy is an important structural feature of diabetic cardiomyopathy. Calcineurin/nuclear factor of activated T-cell (NFAT) pathway plays a central role in the pathogenesis of cardiac hypertrophy. The purpose of this study was to investigate the effects of tropisetron, a novel calcineurin inhibitor, on high glucose (HG)-induced cardiomyocyte hypertrophy and its underlying mechanism.

METHODS

H9c2 myocardial cells were treated with tropisetron or cyclosporine A 1 h before exposure to HG for 48 h.

KEY FINDINGS

Exposure to HG resulted in enhanced cell size, protein content and atrial natriuretic peptide (ANP) protein expression. HG significantly increased Ca(2+) level, calcineurin expression and nuclear translocation of NFATc4. Both tropisetron and cyclosporine A markedly prevented the hypertrophic characteristic features, calcineurin overexpression and nuclear localization of NFATc4 while intracellular Ca(2+) was not affected.

CONCLUSION

Our results showed that tropisetron may have protective effects against HG-induced cardiomyocyte hypertrophy. The mechanism responsible for this beneficial effect seems to be, at least in part, blockade of calcineurin/NFAT signalling pathway.

Na(+)/H (+) exchanger isoform 1 induced osteopontin expression in cardiomyocytes involves NFAT3/Gata4

Osteopontin (OPN), a multifunctional glycophosphoprotein, has been reported to contribute to the development and progression of cardiac remodeling and hypertrophy. Cardiac-specific OPN knockout mice were protected against hypertrophy and fibrosis mediated by Ang II. Recently, transgenic mice expressing the active form of the Na(+)/H(+) exchanger isoform 1 (NHE1) developed spontaneous hypertrophy in association with elevated levels of OPN. The mechanism by which active NHE1 induces OPN expression and contributes to the hypertrophic response remains unclear. To validate whether expression of the active form of NHE1 induces OPN, cardiomyocytes were stimulated with Ang II, a known inducer of both OPN and NHE1. Ang II induced hypertrophy and increased OPN protein expression (151.6 ± 28.19 %, P < 0.01) and NHE1 activity in H9c2 cardiomyoblasts. Ang II-induced hypertrophy and OPN protein expression were regressed in the presence of an NHE1 inhibitor, EMD 87580, or a calcineurin inhibitor, FK506. In addition, our results indicated that activation of NHE1-induced NFAT3 translocation into the nucleus and a significant activation of the transcription factor Gata4 (NHE1: 149 ± 28 % of control, P < 0.05). NHE1-induced activation of Gata4 was inhibited by FK506. In summary, our results suggest that activation of NHE1 induces hypertrophy through the activation of NFAT3/Gata4 and OPN expression.

Hyperphosphate-Induced Myocardial Hypertrophy through the GATA-4/NFAT-3 Signaling Pathway Is Attenuated by ERK Inhibitor Treatment

BACKGROUND/AIMS

Numerous epidemiological studies have associated elevated serum phosphorus levels with cardiovascular disease and the risk of death in the general population as well as in chronic kidney disease (CKD) and dialysis patients. In this study, we explored whether elevated phosphate conditions induce cardiac hypertrophy and attempted to identify the molecular and cellular mechanisms in the hypertrophic response.

METHODS

H9c2 myocardial cells were incubated in high-phosphate conditions to induce hypertrophy. Pathological hypertrophic responses were measured in terms of cell size, arrangement of actin filaments, and hypertrophy markers such as atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in myocardial cells. Several transcriptional factors involved in cardiac hypertrophy development were measured to investigate the molecular pathways involved in elevated phosphate-induced cardiac hypertrophy.

RESULTS

High-phosphate conditions induced cellular hypertrophy, marked by increased cell size, reorganization of actin filaments, and upregulation of both ANP and BNP in H9c2 cells. Both upstream calcineurin and downstream transcription factors, including GATA-4 and NFAT-3, were significantly increased under hyperphosphate conditions. Moreover, both MEK1/2 and ERK1/2 expression increased significantly, and cellular hypertrophy was markedly attenuated by U0126, an ERK1/2 inhibitor.

CONCLUSIONS

These results suggest that hyperphosphate conditions induce myocardial hypertrophy through the ERK signaling pathway in H9c2 cells. Our findings provide a link between the hyperphosphate-induced response and the ERK/NFAT-3 signaling pathway that mediates the development of cardiac hypertrophy. In view of the potent and selective activity of the ERK inhibitor U0126, this agent warrants further investigation as a candidate for preventing hyperphosphate-induced cardiac hypertrophy in CKD and dialysis patients.

Inhibition of JNK phosphorylation by a novel curcumin analog prevents high glucose-induced inflammation and apoptosis in cardiomyocytes and the development of diabetic cardiomyopathy

Hyperglycemia-induced inflammation and apoptosis have important roles in the pathogenesis of diabetic cardiomyopathy. We recently found that a novel curcumin derivative, C66, is able to reduce the high glucose (HG)-induced inflammatory response. This study was designed to investigate the protective effects on diabetic cardiomyopathy and its underlying mechanisms. Pretreatment with C66 significantly reduced HG-induced overexpression of inflammatory cytokines via inactivation of nuclear factor-κB in both H9c2 cells and neonatal cardiomyocytes. Furthermore, we showed that the inhibition of Jun NH2-terminal kinase (JNK) phosphorylation contributed to the protection of C66 from inflammation and cell apoptosis, which was validated by the use of SP600125 and dominant-negative JNK. The molecular docking and kinase activity assay confirmed direct binding of C66 to and inhibition of JNK. In mice with type 1 diabetes, the administration of C66 or SP600125 at 5 mg/kg significantly decreased the levels of plasma and cardiac tumor necrosis factor-α, accompanied by decreasing cardiac apoptosis, and, finally, improved histological abnormalities, fibrosis, and cardiac dysfunction without affecting hyperglycemia. Thus, this work demonstrated the therapeutic potential of the JNK-targeting compound C66 for the treatment of diabetic cardiomyopathy. Importantly, we indicated a critical role of JNK in diabetic heart injury, and suggested that JNK inhibition may be a feasible strategy for treating diabetic cardiomyopathy.

Protective effect of Boerhaavia diffusa L. against mitochondrial dysfunction in angiotensin II induced hypertrophy in H9c2 cardiomyoblast cells

Mitochondrial dysfunction plays a critical role in the development of cardiac hypertrophy and heart failure. So mitochondria are emerging as one of the important druggable targets in the management of cardiac hypertrophy and other associated complications. In the present study, effects of ethanolic extract of Boerhaavia diffusa (BDE), a green leafy vegetable against mitochondrial dysfunction in angiotensin II (Ang II) induced hypertrophy in H9c2 cardiomyoblasts was evaluated. H9c2 cells challenged with Ang II exhibited pathological hypertrophic responses and mitochondrial dysfunction which was evident from increment in cell volume (49.09±1.13%), protein content (55.17±1.19%), LDH leakage (58.74±1.87%), increased intracellular ROS production (26.25±0.91%), mitochondrial superoxide generation (65.06±2.27%), alteration in mitochondrial transmembrane potential (ΔΨm), opening of mitochondrial permeability transition pore (mPTP) and mitochondrial swelling. In addition, activities of mitochondrial respiratory chain complexes (I-IV), aconitase, NADPH oxidase, thioredoxin reductase, oxygen consumption rate and calcium homeostasis were evaluated. Treatment with BDE significantly prevented the generation of intracellular ROS and mitochondrial superoxide radicals and protected the mitochondria by preventing dissipation of ΔΨm, opening of mPTP, mitochondrial swelling and enhanced the activities of respiratory chain complexes and oxygen consumption rate in H9c2 cells. Activities of aconitase and thioredoxin reductase which was lowered (33.77±0.68% & 45.81±0.71% respectively) due to hypertrophy, were increased in BDE treated cells (P≤0.05). Moreover, BDE also reduced the intracellular calcium overload in Ang II treated cells. Overall results revealed the protective effects of B. diffusa against mitochondrial dysfunction in hypertrophy in H9c2 cells and the present findings may shed new light on the therapeutic potential of B. diffusa in addition to its nutraceutical potentials.

Protective effects of the polyphenol sesamin on allergen-induced T(H)2 responses and airway inflammation in mice

Allergic asthma is a lifelong airway condition that affects people of all ages. In recent decades, asthma prevalence continues to increase globally, with an estimated number of 250,000 annual deaths attributed to the disease. Although inhaled corticosteroids and β-adrenergic receptor agonists are the primary therapeutic avenues that effectively reduce asthma symptoms, profound side effects may occur in patients with long-term treatments. Therefore, development of new therapeutic strategies is needed as alternative or supplement to current asthma treatments. Sesamin is a natural polyphenolic compound with strong anti-oxidative effects. Several studies have reported that sesamin is effective in preventing hypertension, thrombotic tendency, and neuroinflammation. However, it is still unknown whether sesamin can reduce asthma-induced allergic inflammation and airway hyperresponsiveness (AHR). Our study has revealed that sesamin exhibited significant anti-inflammatory effects in ovalbumin (OVA)-induced murine asthma model. We found that treatments with sesamin after OVA sensitization and challenge significantly decreased expression levels of interleukin-4 (IL-4), IL-5, IL-13, and serum IgE. The numbers of total inflammatory cells and eosinophils in BALF were also reduced in the sesamin-treated animals. Histological results demonstrated that sesamin attenuated OVA-induced eosinophil infiltration, airway goblet cell hyperplasia, mucus occlusion, and MUC5AC expression in the lung tissue. Mice administered with sesamin showed limited increases in AHR compared with mice receiving vehicle after OVA challenge. OVA increased phosphorylation levels of IκB-α and nuclear expression levels of NF-κB, both of which were reversed by sesamin treatments. These data indicate that sesamin is effective in treating allergic asthma responses induced by OVA in mice.

Role of cytochrome P450-mediated arachidonic acid metabolites in the pathogenesis of cardiac hypertrophy

A plethora of studies have demonstrated the expression of cytochrome P450 (CYP) and soluble epoxide hydrolase (sEH) enzymes in the heart and other cardiovascular tissues. In addition, the expression of these enzymes is altered during several cardiovascular diseases (CVDs), including cardiac hypertrophy (CH). The alteration in CYP and sEH expression results in derailed CYP-mediated arachidonic acid (AA) metabolism. In animal models of CH, it has been reported that there is an increase in 20-hydroxyeicosatetraenoic acid (20-HETE) and a decrease in epoxyeicosatrienoic acids (EETs). Further, inhibiting 20-HETE production by CYP ω-hydroxylase inhibitors and increasing EET stability by sEH inhibitors have been proven to protect against CH as well as other CVDs. Therefore, CYP-mediated AA metabolites 20-HETE and EETs are potential key players in the pathogenesis of CH. Some studies have investigated the molecular mechanisms by which these metabolites mediate their effects on cardiomyocytes and vasculature leading to pathological CH. Activation of several intracellular signaling cascades, such as nuclear factor of activated T cells, nuclear factor kappa B, mitogen-activated protein kinases, Rho-kinases, Gp130/signal transducer and activator of transcription, extracellular matrix degradation, apoptotic cascades, inflammatory cytokines, and oxidative stress, has been linked to the pathogenesis of CH. In this review, we discuss how 20-HETE and EETs can affect these signaling pathways to result in, or protect from, CH, respectively. However, further understanding of these metabolites and their effects on intracellular cascades will be required to assess their potential translation to therapeutic approaches for the prevention and/or treatment of CH and heart failure.

Signal regulatory protein-α protects against cardiac hypertrophy via the disruption of toll-like receptor 4 signaling

Signal regulatory protein-α (SIRPA/SIRPα) is a transmembrane protein that is expressed in various tissues, including the heart. Previous studies have demonstrated that SIRPA is involved in multiple biological processes, including macrophage multinucleation, skeletal muscle differentiation, neuronal survival, protection against diabetes mellitus, and negative regulation of immune cells. However, the role of SIRPA in cardiac hypertrophy remains unknown. To examine the role of SIRPA in pathological cardiac hypertrophy, we used SIRPA knockout mice and transgenic mice that overexpressed mouse SIRPA in the heart. Cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. We observed downregulation of SIRPA expression in dilated cardiomyopathy human hearts and in animal hearts after aortic banding surgery. Accordingly, SIRPA(-/-) mice displayed augmented cardiac hypertrophy, which was accompanied by increased cardiac fibrosis and reduced contractile function, as compared with SIRPA(+/+) mice 4 weeks after aortic banding. In contrast, transgenic mice with the cardiac-specific SIRPA overexpression exhibited the opposite phenotype in response to pressure overload. Likewise, SIRPA protected against angiotensin II-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we revealed that SIRPA-mediated protection during cardiac hypertrophy involved inhibition of the Toll-like receptor 4/nuclear factor-κB signaling axis. Furthermore, we demonstrated that the disruption of Toll-like receptor 4 rescued the adverse effects of SIRPA deficiency on pressure overload-triggered cardiac remodeling. Thus, our results identify that SIRPA plays a protective role in cardiac hypertrophy through negative regulation of the Toll-like receptor 4/nuclear factor-κB pathway.

Atomic force microscopy observation of lipopolysaccharide-induced cardiomyocyte cytoskeleton reorganization

We applied atomic force microscopy (AFM) to observe lipopolysaccharide (LPS)-induced intracellular cytoskeleton reorganization in primary cardiomyocytes from neonatal mouse. The nonionic detergent Triton X-100 was used to remove the membrane, soluble proteins, and organelles from the cell. The remaining cytoskeleton can then be directly visualized by AFM. Using three-dimensional technique of AFM, we were able to quantify the changes of cytoskeleton by the "density" and total "volume" of the cytoskeleton fibers. Compared to the control group, the density of cytoskeleton was remarkably decreased and the volume of cytoskeleton was significantly increased after LPS treatment, which suggests that LPS may induce the cytoskeleton reorganization and change the cardiomyocyte morphology.

Boerhaavia diffusa L. attenuates angiotensin II-induced hypertrophy in H9c2 cardiac myoblast cells via modulating oxidative stress and down-regulating NF-κβ and transforming growth factor β1

The present study evaluated the antihypertrophic potential of the ethanolic extract of Boerhaavia diffusa (BDE), a well-known edible cardiotonic plant reported in Ayurveda against angiotensin II-induced hypertrophy in H9c2 cardiac myoblast cells. Markers of hypertrophy such as cell size, protein content and the concentrations of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) were analysed for the confirmation of hypertrophy induction. Angiotensin II (100 nM) caused an increase in cell volume (69·26 (SD 1·21)%),protein content (48·48 (SD 1·64)%), ANP (81·90 (SD 1·22)%) and BNP (108·57 (SD 1·47)%). BDE treatment significantly reduced cell volume, protein content and the concentrations of ANP and BNP (P#0·05) in H9c2 cells. The activity of various antioxidant enzymes and the concentration of reduced glutathione, which was lowered due to hypertrophy, were increased in BDE-treated cells. The BDE treatment also reduced intracellular reactive oxygen species generation, lipid peroxidation and protein carbonyls in cells. In addition,the expression patterns of NF-kb and transforming growth factor b1 were found to be increased during hypertrophy, and their expressions were reduced on BDE treatment. In vitro chemical assays showed that BDE inhibits angiotensin-converting enzyme and xanthine oxidase in a dose-dependent manner with an estimated 50% effective concentration (EC50) value of 166·12 (SD 2·42) and 60·05 (SD 1·54) mg/ml,respectively. The overall results clearly indicate the therapeutic potential of B. diffusa against cardiac hypertrophy, in addition to its nutritional qualities.

Trypanosoma cruzi infection and endothelin-1 cooperatively activate pathogenic inflammatory pathways in cardiomyocytes

Trypanosoma cruzi, the causative agent of Chagas' disease, induces multiple responses in the heart, a critical organ of infection and pathology in the host. Among diverse factors, eicosanoids and the vasoactive peptide endothelin-1 (ET-1) have been implicated in the pathogenesis of chronic chagasic cardiomyopathy. In the present study, we found that T. cruzi infection in mice induces myocardial gene expression of cyclooxygenase-2 (Cox2) and thromboxane synthase (Tbxas1) as well as endothelin-1 (Edn1) and atrial natriuretic peptide (Nppa). T. cruzi infection and ET-1 cooperatively activated the Ca²⁺/calcineurin (Cn)/nuclear factor of activated T cells (NFAT) signaling pathway in atrial myocytes, leading to COX-2 protein expression and increased eicosanoid (prostaglandins E₂ and F_2α, thromboxane A₂) release. Moreover, T. cruzi infection of ET-1-stimulated cardiomyocytes resulted in significantly enhanced production of atrial natriuretic peptide (ANP), a prognostic marker for impairment in cardiac function of chagasic patients. Our findings support an important role for the Ca²⁺/Cn/NFAT cascade in T. cruzi-mediated myocardial production of inflammatory mediators and may help define novel therapeutic targets.

Chronic cardiomyopathy is the most common and severe manifestation of human Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi. Among diverse inflammation-promoting moieties, eicosanoids and the vasoactive peptide endothelin-1 (ET-1) have been implicated in its pathogenesis. Nevertheless, the link between these two factors has not yet been identified. In the present study, we found that T. cruzi infection induces gene expression of ET-1 and eicosanoid-forming enzymes in the heart of infected mice. We also demonstrated that HL-1 atrial myocytes respond to ET-1 stimulus and T. cruzi infection by induction of cyclooxygenase-2 through activation of the Ca²⁺/calcineurin/NFAT intracellular signaling pathway. Moreover, the cooperation between T. cruzi and ET-1 leads to overproduction of eicosanoids (prostaglandins E₂ and F_2α, thromboxane A₂) and the pro-hypertrophic atrial natriuretic peptide. Our results support an important role for NFAT in T. cruzi plus ET-1-dependent induction of key agents of pathogenesis in chronic chagasic cardiomyopathy. Identification of the Ca²⁺/calcineurin/NFAT cascade as mediator of cardiovascular pathology in Chagas' disease advances our understanding of host-parasite interrelationship and may help define novel potential targets for therapeutic interventions to ameliorate or prevent cardiomyopathy during chronic T. cruzi infection.

Transcriptional effects of E3 ligase atrogin-1/MAFbx on apoptosis, hypertrophy and inflammation in neonatal rat cardiomyocytes

Atrogin-1/MAFbx is an ubiquitin E3 ligase that regulates myocardial structure and function through the ubiquitin-dependent protein modification. However, little is known about the effect of atrogin-1 activation on the gene expression changes in cardiomyocytes. Neonatal rat cardiomyocytes were infected with adenovirus atrogin-1 (Ad-atrogin-1) or GFP control (Ad-GFP) for 24 hours. The gene expression profiles were compared with microarray analysis. 314 genes were identified as differentially expressed by overexpression of atrogin-1, of which 222 were up-regulated and 92 were down-regulated. Atrogin-1 overexpression significantly modulated the expression of genes in 30 main functional categories, most genes clustered around the regulation of cell death, proliferation, inflammation, metabolism and cardiomyoctye structure and function. Moreover, overexpression of atrogin-1 significantly inhibited cardiomyocyte survival, hypertrophy and inflammation under basal condition or in response to lipopolysaccharide (LPS). In contrast, knockdown of atrogin-1 by siRNA had opposite effects. The mechanisms underlying these effects were associated with inhibition of MAPK (ERK1/2, JNK1/2 and p38) and NF-κB signaling pathways. In conclusion, the present microarray analysis reveals previously unappreciated atrogin-1 regulation of genes that could contribute to the effects of atrogin-1 on cardiomyocyte survival, hypertrophy and inflammation in response to endotoxin, and may provide novel insight into how atrogin-1 modulates the programming of cardiac muscle gene expression.

Regulation of sarco(endo)plasmic reticulum Ca2+-ATPase and calsequestrin gene expression in the heart

The precise control of Ca2+levels during the contraction–relaxation cycle in cardiac myocytes is extremely important for normal beat-to-beat contractile activity. The sarcoplasmic reticulum (SR) plays a key role controlling calcium concentration in the cytosol. The SR Ca2+-ATPase (SERCA2) transports Ca2+inside the SR lumen during relaxation of the cardiac myocyte. Calsequestrin (Casq2) is the main protein in the SR lumen, functioning as a Ca2+buffer and participating in Ca2+release by interacting with the ryanodine receptor 2 (RyR2) Ca2+-release channel. Alterations in normal Ca2+handling significantly contribute to the contractile dysfunction observed in cardiac hypertrophy and in heart failure. Transcriptional regulation of the SERCA2 gene has been extensively studied and some of the mechanisms regulating its expression have been elucidated. Overexpression of Sp1 factor in cardiac hypertrophy downregulates SERCA2 gene expression and increased levels of thyroid hormone up-regulates its transcription. Other hormones such norepinephrine, angiotensin II, endothelin-1, parathyroid hormone, prostaglandin-F2α, as well the cytokines tumor necrosis factor-α and interleukin-6 also downregulate SERCA2 expression. Calcium acting through the calcineurin–NFAT (nuclear factor of activated T cells) pathway has been suggested to regulate SERCA2 and CASQ2 gene expression. This review focuses on the current knowledge regarding transcriptional regulation of SERCA2 and CASQ2 genes in the normal and pathologic heart.

High-mobility group box 1 induces calcineurin-mediated cell hypertrophy in neonatal rat ventricular myocytes

Cardiac hypertrophy is an independent predictor of cardiovascular morbidity and mortality. In recent years, evidences suggest that high-mobility group box 1 (HMGB1) protein, an inflammatory cytokine, participates in cardiac remodeling; however, the involvement of HMGB1 in the pathogenesis of cardiac hypertrophy remains unknown. The aim of this study was to investigate whether HMGB1 is sufficient to induce cardiomyocyte hypertrophy and to identify the possible mechanisms underlying the hypertrophic response. Cardiomyocytes isolated from 1-day-old Sprague-Dawley rats were treated with recombinant HMGB1, at concentrations ranging from 50 ng/mL to 200 ng/mL. After 24 hours, cardiomyocytes were processed for the evaluation of atrial natriuretic peptide (ANP) and calcineurin A expression. Western blot and real-time RT-PCR was used to detect protein and mRNA expression levels, respectively. The activity of calcineurin was also evaluated using a biochemical enzyme assay. HMGB1 induced cardiomyocyte hypertrophy, characterized by enhanced expression of ANP, and increased protein synthesis. Meanwhile, increased calcineurin activity and calcineurin A protein expression were observed in cardiomyocytes preconditioned with HMGB1. Furthermore, cyclosporin A pretreatment partially inhibited the HMGB1-induced cardiomyocyte hypertrophy. Our findings suggest that HMGB1 leads to cardiac hypertrophy, at least in part through activating calcineurin.

Perflurooctanoic acid induces developmental cardiotoxicity in chicken embryos and hatchlings

Perfluorooctanoic acid (PFOA) is a widespread environmental contaminant that is detectable in serum of the general U.S. population. PFOA is a known developmental toxicant that induces mortality in mammalian embryos and is thought to induce toxicity via interaction with the peroxisome proliferator activated receptor alpha (PPARα). As the cardiovascular system is crucial for embryonic survival, PFOA-induced effects on the heart may partially explain embryonic mortality. To assess impacts of PFOA exposure on the developing heart in an avian model, we used histopathology and immunohistochemical staining for myosin to assess morphological alterations in 19-day-old chicken embryo hearts after PFOA exposure. Additionally, echocardiography and cardiac myofibril ATPase activity assays were used to assess functional alterations in 1-day-old hatchling chickens following developmental PFOA exposure. Overall thinning and thinning of a dense layer of myosin in the right ventricular wall were observed in PFOA-exposed chicken embryo hearts. Alteration of multiple cardiac structural and functional parameters, including left ventricular wall thickness, left ventricular volume, heart rate, stroke volume, and ejection fraction were detected with echocardiography in the exposed hatchling chickens. Assessment of ATPase activity indicated that the ratio of cardiac myofibril calcium-independent ATPase activity to calcium-dependent ATPase activity was not affected, which suggests that developmental PFOA exposure may not affect cardiac energetics. In summary, structural and functional characteristics of the heart appear to be developmental targets of PFOA, possibly at the level of cardiomyocytes. Additional studies will investigate mechanisms of PFOA-induced developmental cardiotoxicity.

Carthamus tinctorius L. prevents LPS-induced TNFalpha signaling activation and cell apoptosis through JNK1/2-NFkappaB pathway inhibition in H9c2 cardiomyoblast cells

AIM OF THE STUDY

Severe and potentially fatal hypotension and cardiac contractile dysfunction are common symptoms in patients with sepsis. In our previous study, we found that estradiol and estrogen-receptor alpha have cardio-protective effects in myocardial cells exposed to LPS. Estradiol supplementation has been shown to induce breast and cervical cancers. Flos Carthami, the flower of Carthamus tinctorius L. (Compositae) is an important traditional Chinese medicine used for the treatment of heart disease and inflammation, and therefore might be a potential alternative to Estradiol in the prevention of heart damage. This study investigated the effect of Flos Carthami (FC(EtOH)) ethanolic extract on LPS-induced apoptosis in H9c2 cardiomyoblast cells.

MATERIALS AND METHODS

H9c2 cells induced apoptosis with LPS administration (1 microg/mL). H9c2 cells were divided into five groups: Control, LPS (1 microg/mL), and three FC(EtOH) (31.25, 62.5,and 125 microg/mL). We detected apoptosis using MTT, LDH, TUNEL assay. JC-1 staining and Western blot were used to detect pro-apoptosis proteins, anti-apoptosis proteins, MAPK proteins (JNK, ERK, and P38), and NFkappaB expression.

RESULTS

FC(EtOH) (62.5 microg/mL) inhibited LPS-induced apoptosis by suppressing JNK1/2 activity, which resulted in the reduction of both IkappaB degradation and NFkappaB activation. In addition, FC(EtOH) led to the activation of anti-apoptotic proteins, Bcl-2 and Bcl-xL, the stabilization of the mitochondria membrane and the down-regulation of extrinsic and intrinsic pro-apoptotic proteins, such as TNFalpha, active caspase-8, t-Bid, Bax, active caspases-9, and -3.

CONCLUSIONS

Carthamus tinctorius L. possesses the ability to suppress JNK activity and inhibit LPS-induced TNFalpha activation and apoptosis in H9c2 cardiomyoblast cells. Carthamus tinctorius L could potentially serve as a cardio-protective agent against LPS-induced apoptosis.

2,3,7,8-Tetrachlorodibenzo-p-dioxin and beta-naphthoflavone induce cellular hypertrophy in H9c2 cells by an aryl hydrocarbon receptor-dependant mechanism

Cigarette smoke is a major risk factor for cardiovascular diseases. It contains thousands of compounds that activate the aryl hydrocarbon receptor (AhR). In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most potent AhR ligand, has been shown to cause cardiotoxic effects in several in vivo models. Although induction of CYP1 family is the most important effect of AhR activation, the role of CYP1 induction in mediating the cardiotoxic effect of TCDD is usually overlooked. Therefore, we investigated whether AhR activation causes a hypertrophic effect in H9c2 cells and we related this effect to changes in CYP gene expression. In the current study, the cardiac derived H9c2 cells were treated with two AhR ligands, TCDD and beta-naphthoflavone (BNF), for 24 and 48h. The expression of the hypertrophic markers, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), and several CYP genes were measured by real-time PCR. Treatment of H9c2 cells with TCDD or BNF for 24h caused a significant induction of CYP1A1, CYP1B1, and CYP4A1; however, there was no change in the expression of other genes. On the other hand, treatment of the cells with TCDD or BNF for 48h caused a significant induction of the hypertrophic markers, ANP and BNP, and several CYP genes such as CYP1A1, CYP1B1, CYP2E1, CYP2J3, and CYP4F4 parallel to a significant increase in the cell surface area. Neither TCDD nor BNF increased the oxidative stress in H9c2 cells at all concentrations tested. Interestingly, resveratrol, an AhR antagonist, protected the cells from TCDD-induced hypertrophy. In conclusion, AhR ligands caused a hypertrophic effect in H9c2 cells which was associated with induction of several CYP genes which can be prevented by resveratrol.

Liver X receptors are negative regulators of cardiac hypertrophy via suppressing NF-kappaB signalling

AIMS

Nuclear factor-kappaB (NF-kappaB) plays a critical role in cell growth and inflammation during the progression of cardiac hypertrophy and heart failure. Several members of nuclear receptor superfamily, including liver X receptors (LXRalpha and LXRbeta), have been shown to suppress inflammatory responses, but little is known about their effects in cardiomyocytes.

METHODS AND RESULTS

We investigated LXR expression patterns in pressure overload-induced hypertrophic hearts and the hypertrophic growth of the LXRalpha-deficient hearts from mice (C57/B6) in response to pressure overload. The underlying mechanisms were also explored using cultured myocytes. We found that cardiac expression of LXRalpha was upregulated in pressure overload-induced left ventricular hypertrophy in mice. Transverse aorta coarctation-induced left ventricular hypertrophy was exacerbated in LXRalpha-null mice relative to control mice. A synthetic LXR ligand, T1317, suppressed cardiomyocyte hypertrophy in response to angiotensin II and lipopolysaccharide treatments. In addition, LXR activation suppressed NF-kappaB signalling and the expression of associated inflammatory factors. Overexpression of constitutively active LXRalpha and beta in cultured myocytes suppressed NF-kappaB activity.

CONCLUSION

LXRs are negative regulators of cardiac growth and inflammation via suppressing NF-kappaB signalling in cardiomyocytes. This should provide new insights into novel therapeutic targets for treating cardiac hypertrophy and heart failure.

Lipopolysaccharide upregulates uPA, MMP-2 and MMP-9 via ERK1/2 signaling in H9c2 cardiomyoblast cells

Upregulation of urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA), and matrix metallopeptidases (MMPs) is associated with the development of myocardial infarction (MI), dilated cardiomyopathy, cardiac fibrosis, and heart failure (HF). Evidences suggest that lipopolysaccharide (LPS) participates in the inflammatory response in the cardiovascular system; however, it is unknown if LPS is sufficient to upregulate expressions and/or activity of uPA, tPA, MMP-2, and MMP-9 in myocardial cells. In this study, we treated H9c2 cardiomyoblasts with LPS to explore whether LPS upregulates uPA, tPA, MMP-2, and MMP-9, and further to identify the precise molecular and cellular mechanisms behind this upregulatory responses. Here, we show that LPS challenge increased the protein levels of uPA, MMP-2 and MMP-9, and induced the activity of MMP-2 and MMP-9 in H9c2 cardiomyoblasts. However, LPS showed no effects on the expression of tissue inhibitor of metalloproteinase-1, -2, -3, and -4 (TIMP-1, -2, -3, and -4). After administration of inhibitors including U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor), CsA (calcineurin inhibitor), and QNZ (NFkappaB inhibitor), the LPS-upregulated expression and/or activity of uPA, MMP-2, and MMP-9 in H9c2 cardiomyoblasts are markedly inhibited only by ERK1/2 inhibitors, U0126. Collectively, these results suggest that LPS upregulates the expression and/or activity of uPA, MMP-2, and MMP-9 through ERK1/2 signaling pathway in H9c2 cardiomyoblasts. Our findings further provide a link between the LPS-induced cardiac dysfunction and the ERK1/2 signaling pathway that mediates the upregulation of uPA, MMP-2 and MMP-9.