Myocardial fibrosis induced by exposure to subclinical lipopolysaccharide is associated with decreased miR-29c and enhanced NOX2 expression in mice

Cardioprotective effect of cedrol in an inflammation systemic model induced by lipopolysaccharide: Biochemical and histological verification

Introduction

Evidence declared lipopolysaccharide (LPS) initiates inflammatory responses by stimulating the abandon of cytokines, which may perturb organ function. On the other side, it has been suggested Cedrol has potential properties, including anti-inflammatory and anti-oxidative activities. Herein, this study was done to assess the protective effect of Cedrol against LPS-associated heart damage.

Methods

Thirty-five rats (200-250 g) were sorted into five groups, including control, LPS, LPS-Cedrol 7.5 mg/kg, LPS-Cedrol 15 mg/kg, and LPS-Cedrol 30 mg/kg groups. Cedrol was administrated through injected intra-peritoneally for two weeks. The heart tissues were removed and malondialdehyde (MDA) as a lipid peroxidation marker, superoxide dismutase (SOD), and catalase (CAT) as antioxidant markers were assessed. Furthermore, the interleukin (IL)-6 level in cardiac tissue was measured and Masson's trichrome methods were employed to appraise cardiac inflammation and fibrosis, respectively.

Results

Inflammation induced by LPS was significantly accompanied by myocardial fibrosis which was shown by Masson's trichrome staining (P<0.001). In addition, LPS administration enhanced the MDA level while it diminished the activity of anti-oxidant markers such as CAT and SOD (P<0.001 for all cases). In the histological results, Cedrol improved LPS-induced inflammation and cardiac fibrosis (P<0.01 to P<0.001). Cedrol also enhanced CAT and SOD activities, whereas declined MDA level in the cardiac tissue (P<0.01 to P<0.001).

Conclusion

The current findings proposed that the administration of Cedrol exerted a protective role in LPS-associated heart damage by reducing inflammation, cardiac fibrosis, and oxidative stress.

H3K27Me3 abundance increases fibrogenesis during endothelial-to-mesenchymal transition via the silencing of microRNA-29c

Objective

Endothelial-to-mesenchymal transition (EndMT) is a transdifferentiation process in which endothelial cells (ECs) adopt a mesenchymal-like phenotype. Over the past few years, it became clear that EndMT can contribute to several cardiovascular pathologies. However, the molecular pathways underlying the development of EndMT remain incompletely understood. Since the epigenetic enzyme Enhancer of Zeste Homolog 2 (EZH2) and its concomitant mark H3K27Me3 have been shown to be elevated in many cardiovascular diseases that associate with EndMT, we hypothesized that H3K27Me3 is a determinant for the susceptibility of EndMT.

Methods

To study the association between H3K27Me3 and EndMT, a knockdown model of EZH2 in human endothelial cells (HUVEC) was utilized to reduce H3K27Me3 abundance, followed by induction of EndMT using TGFβ1. The expression of molecular markers of EndMT and fibrogenesis were analysed.

Results

In cultured HUVECs, a reduction of H3K27Me3 abundance facilitates EndMT but mitigates fibrogenesis as shown by a decreased expression of collagen I and III. In HUVEC, H3K27Me3 abundance directly affects the expression of miR29c, a collagen-targeting miRNA. Additionally, knockdown of miR-29c in HUVEC with low H3K27Me3 abundance partly restored the expression of collagen I and III. Expectedly, in rats with perivascular fibrosis an increased abundance of H3K27Me3 associated with a decreased expression of miR-29c.

Conclusion

our data shows that endothelial fibrogenesis underlies an epigenetic regulatory pathway and we demonstrate that a decreased abundance of H3K27Me3 in ECs blunts fibrogenesis in part in a miR-29c dependent manner. Therefore, a reduction of H3K27Me3 could serve as a novel therapeutical strategy to mitigate fibrogenesis and may prove to be beneficial in fibrogenic diseases including atherosclerosis, cardiac fibrosis, and PAH.

Oral angiotensin-converting enzyme inhibitor captopril protects the heart from Porphyromonas gingivalis LPS-induced cardiac dysfunction in mice

Although angiotensin converting enzyme (ACE) inhibitors are considered useful for the treatment of human heart failure, some experimental failing-heart models have shown little beneficial effect of ACE inhibitors in animals with poor oral health, particularly periodontitis. In this study, we examined the effects of the ACE inhibitor captopril (Cap; 0.1 mg/mL in drinking water) on cardiac dysfunction in mice treated with Porphyromonas gingivalis lipopolysaccharide (PG-LPS) at a dose (0.8 mg/kg/day) equivalent to the circulating level in patients with periodontal disease. Mice were divided into four groups: 1) Control, 2) PG-LPS, 3) Cap, and 4) PG-LPS + Cap. After1 week, we evaluated cardiac function by echocardiography. The left ventricular ejection fraction was significantly decreased in PG-LPS-treated mice compared to the control (from 66 ± 1.8 to 59 ± 2.5%), while Cap ameliorated the dysfunction (63 ± 1.1%). The area of cardiac fibrosis was significantly increased (approximately 2.9-fold) and the number of apoptotic myocytes was significantly increased (approximately 5.6-fold) in the heart of PG-LPS-treated group versus the control, and these changes were suppressed by Cap. The impairment of cardiac function in PG-LPS-treated mice was associated with protein kinase C δ phosphorylation (Tyr-311), leading to upregulation of NADPH oxidase 4 and xanthine oxidase, and calmodulin kinase II phosphorylation (Thr-286) with increased phospholamban phosphorylation (Thr-17). These changes were also suppressed by Cap. Our results suggest that the renin-angiotensin system might play an important role in the development of cardiac diseases induced by PG-LPS.

Anti-inflammatory activity of carvacrol protects the heart from lipopolysaccharide-induced cardiac dysfunction by inhibiting pyroptosis via NLRP3/Caspase1/Gasdermin D signaling axis

AIMS

Lipopolysaccharide (LPS) is a well-known agent to induce septic conditions. Sepsis-induced cardiomyopathy has an overwhelming death rate. Carvacrol (CVL), a monoterpene phenol, has anti-inflammatory and antioxidant properties. The research aimed to investigate the effect of CVL on LPS-induced dysfunction in the heart. In this study, we evaluated the effect of CVL in LPS-stimulated H9c2 cardiomyoblast cells and Balb/c mice.

MAIN METHODS

LPS was used to induce septic conditions in H9c2 cardiomyoblast cells in vitro and in Balb/C mice. A survival study was conducted to assess the survival rate of mice after LPS and/or CVL treatment.

KEY FINDINGS

In vitro studies indicated that CVL inhibits reactive oxygen species (ROS) generation and abates pyroptosis mediated by NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in H9c2 cells. In mice, CVL intervention improved the survival rate in septic conditions. The CVL administration markedly improved the echocardiographic parameters and alleviated the LPS-induced reduction in the ejection fraction (%) and fraction shortening (%). The CVL intervention restored the myocardial antioxidants and histopathological alterations and decreased the pro-inflammatory cytokine contents in the heart. Further findings disclosed that CVL reduced the protein levels of NLRP3, apoptosis-associated speck-like protein (ASC), caspase 1, interleukin (IL)-18, IL-1β, and the pyroptosis-indicative protein, gasdermin-D (GSDMD) in the heart. The autophagy-indicative proteins, beclin 1, and p62, in the heart were also restored in the CVL-treated group.

SIGNIFICANCE

Altogether, our findings demonstrated that CVL has a beneficial effect and can be a potential molecule against sepsis-induced myocardial dysfunction.

Gut Molecules in Cardiometabolic Diseases: The Mechanisms behind the Story

Atherosclerotic cardiovascular disease is the most common cause of morbidity and mortality worldwide. Diabetes mellitus increases cardiovascular risk. Heart failure and atrial fibrillation are associated comorbidities that share the main cardiovascular risk factors. The use of incretin-based therapies promoted the idea that activation of alternative signaling pathways is effective in reducing the risk of atherosclerosis and heart failure. Gut-derived molecules, gut hormones, and gut microbiota metabolites showed both positive and detrimental effects in cardiometabolic disorders. Although inflammation plays a key role in cardiometabolic disorders, additional intracellular signaling pathways are involved and could explain the observed effects. Revealing the involved molecular mechanisms could provide novel therapeutic strategies and a better understanding of the relationship between the gut, metabolic syndrome, and cardiovascular diseases.

Gut microbiota and myocardial fibrosis

Myocardial fibrosis (MF) is a pathophysiological condition that accompanies various myocardial diseases and comprises a damaged myocardial matrix repair process. Although fibrosis plays a vital role in repair, it ultimately alters cardiac systolic and diastolic functions. The gut microbiota is a complex and dynamic ecosystem with billions of microorganisms that produce bioactive compounds that influence host health and disease progression. Intestinal microbiota has been shown to correlate with cardiovascular disease, and dysbiosis of the intestinal microbiota is involved in the development of MF. In this review, we discuss the role of intestinal microbiota in the process of MF, including alterations in microbiota composition and the effects of metabolites. We also discuss how diet and medicines can affect cardiac fibrosis by influencing the gut microbiota, and potential future therapies targeting the gut-heart axis. A healthy gut microbiota can prevent disease, but dysbiosis can lead to various symptoms, including the induction of heart disease. In this review, we discuss the relevance of the gut-heart axis and the multiple pathways by which gut microbiota may affect cardiac fibrosis, including inflammatory factors, immune cells, and gut microbiota metabolites, such as trimethylamine-N-oxide (TMAO) and short-chain fatty acids (SCFAs). Finally, we discuss the involvement of gut microbiota in the treatment of cardiac fibrosis, including drugs, fecal microbiota transplantation, and oral probiotics or prebiotics. With future studies on the relationship between the heart and gut microbiota, we hope to find better ways to improve MF through the gut-heart axis.

Nicotinamide Adenine Dinucleotide Phosphate Oxidases in Glucose Homeostasis and Diabetes-Related Endothelial Cell Dysfunction

Oxidative stress within the vascular endothelium, due to excess generation of reactive oxygen species (ROS), is thought to be fundamental to the initiation and progression of the cardiovascular complications of type 2 diabetes mellitus. The term ROS encompasses a variety of chemical species including superoxide anion (O₂^•-), hydroxyl radical (OH^-) and hydrogen peroxide (H₂O₂). While constitutive generation of low concentrations of ROS are indispensable for normal cellular function, excess O₂^•- can result in irreversible tissue damage. Excess ROS generation is catalysed by xanthine oxidase, uncoupled nitric oxide synthases, the mitochondrial electron transport chain and the nicotinamide adenine dinucleotide phosphate (NADPH) oxidases. Amongst enzymatic sources of O₂^•- the Nox2 isoform of NADPH oxidase is thought to be critical to the oxidative stress found in type 2 diabetes mellitus. In contrast, the transcriptionally regulated Nox4 isoform, which generates H₂O₂, may fulfil a protective role and contribute to normal glucose homeostasis. This review describes the key roles of Nox2 and Nox4, as well as Nox1 and Nox5, in glucose homeostasis, endothelial function and oxidative stress, with a key focus on how they are regulated in health, and dysregulated in type 2 diabetes mellitus.

Role of the microRNA-29 family in myocardial fibrosis

Myocardial fibrosis (MF) is an inevitable pathological process in the terminal stage of many cardiovascular diseases, often leading to serious cardiac dysfunction and even death. Currently, microRNA-29 (miR-29) is thought to be a novel diagnostic and therapeutic target of MF. Understanding the underlying mechanisms of miR-29 that regulate MF will provide a new direction for MF therapy. In the present review, we concentrate on the underlying signaling pathway of miR-29 affecting MF and the crosstalk regulatory relationship among these pathways to illustrate the complex regulatory network of miR-29 in MF. Additionally, based on our mechanistic understanding, we summarize opportunities and challenges of miR-29-based MF diagnosis and therapy.

Cardamonin protects against lipopolysaccharide-induced myocardial contractile dysfunction in mice through Nrf2-regulated mechanism

In patients with sepsis, lipopolysaccharide (LPS) from the outer membrane of gram-negative bacteria triggers cardiac dysfunction and heart failure, but target therapy for septic cardiomyopathy remains unavailable. In this study we evaluated the beneficial effects of cardamonin (CAR), a flavone existing in Alpinia plant, on endotoxemia-induced cardiac dysfunction and the underlying mechanisms with focus on oxidative stress and apoptosis. Adult mice were exposed to LPS (4 mg/kg, i.p. for 6 h) prior to functional or biochemical assessments. CAR (20 mg/kg, p.o.) was administered to mice immediately prior to LPS challenge. We found that LPS challenge compromised cardiac contractile function, evidenced by compromised fractional shortening, peak shortening, maximal velocity of shortening/relengthening, enlarged LV end systolic diameter and prolonged relengthening in echocardiography, and induced apoptosis, overt oxidative stress (O2- production and reduced antioxidant defense) associated with inflammation, phosphorylation of NF-κB and cytosolic translocation of transcriptional factor Nrf2. These deteriorative effects were greatly attenuated or mitigated by CAR administration. However, H&E and Masson's trichrome staining analysis revealed that neither LPS challenge nor CAR administration significantly affected cardiomyocyte cross-sectional area and interstitial fibrosis. Mouse cardiomyocytes were treated with LPS (4 µg/mL) for 6 h in the absence or presence of CAR (10 μM) in vitro. We found that addition of CAR suppressed LPS-induced defect in cardiomyocyte shortening, which was nullified by the Nrf2 inhibitor ML-385 or the NF-κB activator prostratin. Taken together, our results suggest that CAR administration protects against LPS-induced cardiac contractile abnormality, oxidative stress, apoptosis, and inflammation through Nrf2- and NF-κB-dependent mechanism.

CD74 knockout protects against LPS-induced myocardial contractile dysfunction through AMPK-Skp2-SUV39H1-mediated demethylation of BCLB

BACKGROUND AND PURPOSE

Lipopolysaccharides (LPS), an outer membrane component of Gram-negative bacteria, triggers myocardial anomalies in sepsis. Recent findings indicated a role for inflammatory cytokine MIF and its receptor, CD74, in septic organ injury, although little is known of the role of MIF-CD74 in septic cardiomyopathy.

EXPERIMENTAL APPROACH

This study evaluated the impact of CD74 ablation on endotoxaemia-induced cardiac anomalies. Echocardiographic, cardiomyocyte contractile and intracellular Ca2+ properties were examined.

KEY RESULTS

Our data revealed compromised cardiac function (lower fractional shortening, enlarged LV end systolic diameter, decreased peak shortening, maximal velocity of shortening/relengthening, prolonged duration of relengthening and intracellular Ca2+ mishandling) and ultrastructural derangement associated with inflammation, O2 - production, apoptosis, excess autophagy, phosphorylation of AMPK and JNK and dampened mTOR phosphorylation. These effects were attenuated or mitigated by CD74 knockout. LPS challenge also down-regulated Skp2, an F-box component of Skp1/Cullin/F-box protein-type ubiquitin ligase, while up-regulating that of SUV39H1 and H3K9 methylation of the Bcl2 protein BCLB. These effects were reversed by CD74 ablation. In vitro study revealed that LPS facilitated GFP-LC3B formation and cardiomyocyte defects. These effects were prevented by CD74 ablation. Interestingly, the AMPK activator AICAR, the autophagy inducer rapamycin and the demethylation inhibitor difenoconazole inhibited the effects of CD74 ablation against LPS-induced cardiac dysfunction, while the SUV39H1 inhibitor chaetocin or methylation inhibitor 5-AzaC ameliorated LPS-induced GFP-LC3B formation and cardiomyocyte contractile dysfunction.

CONCLUSION AND IMPLICATIONS

Our data suggested that CD74 ablation protected against LPS-induced cardiac anomalies, O2 - production, inflammation and apoptosis through suppression of autophagy in a Skp2-SUV39H1-mediated mechanism.

Characterization of a novel protein identified by proteomics analysis as a modulator of inflammatory networks in amphioxus

Inflammatory response is an innate host defense mechanism, and its regulation is essential for the host to get rid of harm by the excessive reactions. We first utilized proteomics approach to identify amphioxus humoral fluid proteins in response to LPS-induced inflammation. A total of 26 differentially expressed proteins, mainly involved in energy metabolism and cytoskeleton rearrangement processes, were identified between LPS-treated and control animals. Furthermore, we found a single uncharacterized protein (termed BjIM1) out of the most up-regulated ones, and examined its role in the regulation of immune and inflammatory responses. BjIM1 is predominantly expressed in the hepatic caecum, and its promoter sequence includes many binding sites for immune-relevant transcription factors. Importantly, recombinant BjIM1 (rBjIM1) is able to inhibit LPS-induced up-regulation of TLR pathway genes, such as MyD88, IKK, NF-κB1, Rel, p38, JNK and AP-1, indicating that BjIM1 may negatively regulate the TLR signaling pathway in amphioxus. Moreover, rBjIM1 also modulates the expression of genes involved in the interaction network of inflammation, energy metabolism and cytoskeleton rearrangement, including SIRT1, Rac1 and NOX2, in the LPS-induced inflammatory response in amphioxus. Collectively, our studies suggest that BjIM1 is an uncharacterized protein functioning as a modulator of inflammatory networks in amphioxus.

Alisol B 23-Acetate Ameliorates Lipopolysaccharide-Induced Cardiac Dysfunction by Suppressing Toll-Like Receptor 4 (TLR4)/NADPH Oxidase 2 (NOX2) Signaling Pathway

Background

Cardiac dysfunction during endotoxemia is a major cause of cardiovascular disease with high morbidity and mortality. Alisol B 23-acetate (AB23A) is a triterpenoid extracted from the Rhizoma Alismatis, a kind of traditional Chinese medicine, exhibits anti-inflammatory activity on endotoxemia. This investigation aimed to uncover the protective effects of AB23A against sepsis-induced cardiac dysfunction.

Material/Methods

Adult male C57BL/6 mice received lipopolysaccharide (LPS) (20 mg/kg intravenous) stimulation, with or without pre-treatment of AB23A (10 mg/kg, 20 mg/kg, or 40 mg/kg). Histopathological staining and cardiac function were performed 4 hours after LPS stimulation. Then the levels of interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α were monitored with enzyme-linked immunosorbent assay (ELISA). In addition, H9C2 cells were treated with LPS (5 μg/mL) with or without pre-treated with AB23A (0.1 μM, 1 μM, or 10 μM), and the production of reactive oxygen species (ROS) was detected by DCFH-DA combined with flow cytometry. The expression of Toll-like receptor 4 (TLR4), NADPH oxidase 2 (NOX2), NOX4, P38, p-P38, extracellular-signal-regulated kinase (ERK), and p-ERK were assessed by western blotting.

Results

AB23A improved the survival rate and ameliorated myocardial injury, decreased inflammatory infiltration and the level of IL-6, IL-1β, and TNF-α in the LPS-stimulated mouse model. Moreover, AB23A inhibited the ROS production in LPS-treated H9C2 cells. In addition, AB23A suppressed the levels of TLR4 and NOX2 as well as the activation levels of P38 and ERK both in vivo and in vitro.

Conclusions

AB23A reduced LPS-induced myocardial dysfunction by inhibiting inflammation and ROS production through the TLR4/NOX2 pathway.

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.

Lipopolysaccharide Activates Toll-Like Receptor 4 and Prevents Cardiac Fibroblast-to-Myofibroblast Differentiation

Bacterial lipopolysaccharide (LPS) is a known ligand of Toll-like receptor 4 (TLR4) which is expressed in cardiac fibroblasts (CF). Differentiation of CF to cardiac myofibroblasts (CMF) is induced by transforming growth factor-β1 (TGF-β1), increasing alpha-smooth muscle actin (α-SMA) expression. In endothelial cells, an antagonist effect between LPS-induced signaling and canonical TGF-β1 signaling was described; however, it has not been studied whether in CF and CMF the expression of α-SMA induced by TGF-β1 is antagonized by LPS and the mechanism involved. In adult rat CF and CMF, α-SMA, ERK1/2, Akt, NF-κβ, Smad3, and Smad7 protein levels were determined by western blot, TGF-β isoforms by ELISA, and α-SMA stress fibers by immunocytochemistry. CF and CMF secrete the three TGF-β isoforms, and the secretion levels of TGF-β2 was affected by LPS treatment. In CF, LPS treatment decreased the protein levels of α-SMA, and this effect was prevented by TAK-242 (TLR4 inhibitor) and LY294002 (Akt inhibitor), but not by BAY 11-7082 (NF-κβ inhibitor) and PD98059 (ERK1/2 inhibitor). TGF-β1 increased α-SMA protein levels in CF, and LPS prevented partially this effect. In addition, in CMF α-SMA protein levels were decreased by LPS treatment, which was abolished by TAK-242. Finally, in CF LPS decreased the p-Smad3 phosphorylation and increased the Smad7 protein levels. LPS treatment prevents the CF-to-CMF differentiation and reverses the CMF phenotype induced by TGF-β1, through decreasing p-Smad3 and increasing Smad7 protein levels.

Extracellular matrix remodeling and cardiac fibrosis

Cardiac fibrosis, characterized by excessive deposition of extracellular matrix (ECM) proteins in the myocardium, distorts the architecture of the myocardium, facilitates the progression of arrhythmia and cardiac dysfunction, and influences the clinical course and outcome in patients with heart failure. This review describes the composition and homeostasis in normal cardiac interstitial matrix and introduces cellular and molecular mechanisms involved in cardiac fibrosis. We also characterize the ECM alteration in the fibrotic response under diverse cardiac pathological conditions and depict the role of matricellular proteins in the pathogenesis of cardiac fibrosis. Moreover, the diagnosis of cardiac fibrosis based on imaging and biomarker detection and the therapeutic strategies are addressed. Understanding the comprehensive molecules and pathways involved in ECM homeostasis and remodeling may provide important novel potential targets for preventing and treating cardiac fibrosis.

Pro-inflammatory hepatic macrophages generate ROS through NADPH oxidase 2 via endocytosis of monomeric TLR4-MD2 complex

Reactive oxygen species (ROS) contribute to the development of non-alcoholic fatty liver disease. ROS generation by infiltrating macrophages involves multiple mechanisms, including Toll-like receptor 4 (TLR4)-mediated NADPH oxidase (NOX) activation. Here, we show that palmitate-stimulated CD11b⁺F4/80^low hepatic infiltrating macrophages, but not CD11b⁺F4/80^high Kupffer cells, generate ROS via dynamin-mediated endocytosis of TLR4 and NOX2, independently from MyD88 and TRIF. We demonstrate that differently from LPS-mediated dimerization of the TLR4–MD2 complex, palmitate binds a monomeric TLR4–MD2 complex that triggers endocytosis, ROS generation and increases pro-interleukin-1β expression in macrophages. Palmitate-induced ROS generation in human CD68^lowCD14^high macrophages is strongly suppressed by inhibition of dynamin. Furthermore, Nox2-deficient mice are protected against high-fat diet-induced hepatic steatosis and insulin resistance. Therefore, endocytosis of TLR4 and NOX2 into macrophages might be a novel therapeutic target for non-alcoholic fatty liver disease.

Reactive species of oxygen promote the development of hepatic steatosis. Here, Kim et al. demonstrate that palmitate stimulates macrophage infiltration and increases oxidative stress during steatosis by binding to the TLR4–MD2 complex, which results in the activation of NOX2.

Biomarkers in patients with myocardial fibrosis

Myocardial fibrosis is observed in many cardiovascular diseases including hypertension, heart failure and cardiomyopathy. Myocardial fibrosis has been proved to be reversible and treatable only under timely intervention, which makes early detection and assessment of fibrosis crucial. Aside from tissue biopsy as the gold standard for the diagnosis of myocardial fibrosis, circulating biomarkers have been adopted as noninvasive assessment of this lesion. Dysregulated collagen deposition is thought to be the major cause of myocardial fibrosis. Collagens, procollagens, TGF-β, TIMP, galectin-3, and microRNAs are thought to be indicators of myocardial fibrosis. In this review, we summarize the molecules that are frequently used as biomarkers in diagnosis of cardiac fibrosis. Mechanisms of fibrosis that they take part in are also introduced.

Periodontal-induced chronic inflammation triggers macrophage secretion of Ccl12 to inhibit fibroblast-mediated cardiac wound healing

Chronic inflammatory diseases, such as periodontal disease, associate with adverse wound healing in response to myocardial infarction (MI). The goal of this study was to elucidate the molecular basis for impaired cardiac wound healing in the setting of periodontal-induced chronic inflammation. Causal network analysis of 168 inflammatory and extracellular matrix genes revealed that chronic inflammation induced by a subseptic dose of Porphyromonas gingivalis lipopolysaccharide (LPS) exacerbated infarct expression of the proinflammatory cytokine Ccl12. Ccl12 prevented initiation of the reparative response by prolonging inflammation and inhibiting fibroblast conversion to myofibroblasts, resulting in diminished scar formation. Macrophage secretion of Ccl12 directly impaired fibronectin and collagen deposition and indirectly stimulated collagen degradation through upregulation of matrix metalloproteinase-2. In post-MI patients, circulating LPS levels strongly associated with the Ccl12 homologue monocyte chemotactic protein 1 (MCP-1). Patients with LPS levels ≥ 1 endotoxin units (EU)/ml (subseptic endotoxemia) at the time of hospitalization had increased end diastolic and systolic dimensions compared with post-MI patients with < 1 EU/ml, indicating that low yet pathological concentrations of circulating LPS adversely impact post-MI left ventricle (LV) remodeling by increasing MCP-1. Our study provides the first evidence to our knowledge that chronic inflammation inhibits reparative fibroblast activation and generates an unfavorable cardiac-healing environment through Ccl12-dependent mechanisms.

Effect of Angiotensin-converting Enzyme Inhibitor on Cardiac Fibrosis and Oxidative Stress Status in Lipopolysaccharide-induced Inflammation Model in Rats

Background:

Renin-angiotensin (Ang)-aldosterone system not only plays a key role in the regulation of circulatory homeostasis, but also it acts as a powerful pro-inflammatory mediator. The aim of this study was to evaluate the effect of captopril (Cap), a known Ang-converting enzyme inhibitor, on inflammation-induced cardiac fibrosis, and heart oxidative stress status in lipopolysaccharide (LPS)-induced inflammation in male rats.

Methods:

Fifty male rats were randomly divided into five groups control, LPS (1 mg/kg/day), LPS + Cap 10 mg/kg, LPS + Cap 50 mg/kg and LPS + Cap 100 mg/kg. After 2 weeks, blood samples were taken, and hearts were harvested for evaluation of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and nitric oxide metabolite in serum and tissue hemogenate, histopathology (hematoxylin and eosin and Masson's trichrome) and oxidative stress status.

Results:

Serum IL-6 and TNF-α concentration were higher in LPS group compared to control and Cap reduced them, significantly. Heart TNF-α and IL-6 contents in LPS group were significantly higher than control (P < 0.05). The administration of Cap significantly decreased inflammatory markers level to control (P < 0.05). The higher levels of malondialdehyde and lower antioxidative markers (total thiol, superoxide dismutase, and catalase) in the heart were observed in LPS group and treatment by Cap improved them, dose-dependently. Histopathological study revealed cardiac fibrosis and more collagen content in LPS group which significantly improved by Cap treatment.

Conclusions:

Treatment by Cap reduced cardiac fibrosis possibly through improving oxidative stress status, and it can be considered to increase cardiac compliance in this condition.

Experimental, Systems, and Computational Approaches to Understanding the MicroRNA-Mediated Reparative Potential of Cardiac Progenitor Cell-Derived Exosomes From Pediatric Patients

RATIONALE

Studies have demonstrated that exosomes can repair cardiac tissue post-myocardial infarction and recapitulate the benefits of cellular therapy.

OBJECTIVE

We evaluated the role of donor age and hypoxia of human pediatric cardiac progenitor cell (CPC)-derived exosomes in a rat model of ischemia-reperfusion injury.

METHODS AND RESULTS

Human CPCs from the right atrial appendages from children of different ages undergoing cardiac surgery for congenital heart defects were isolated and cultured under hypoxic or normoxic conditions. Exosomes were isolated from the culture-conditioned media and delivered to athymic rats after ischemia-reperfusion injury. Echocardiography at day 3 post-myocardial infarction suggested statistically improved function in neonatal hypoxic and neonatal normoxic groups compared with saline-treated controls. At 28 days post-myocardial infarction, exosomes derived from neonatal normoxia, neonatal hypoxia, infant hypoxia, and child hypoxia significantly improved cardiac function compared with those from saline-treated controls. Staining showed decreased fibrosis and improved angiogenesis in hypoxic groups compared with controls. Finally, using sequencing data, a computational model was generated to link microRNA levels to specific outcomes.

CONCLUSIONS

CPC exosomes derived from neonates improved cardiac function independent of culture oxygen levels, whereas CPC exosomes from older children were not reparative unless subjected to hypoxic conditions. Cardiac functional improvements were associated with increased angiogenesis, reduced fibrosis, and improved hypertrophy, resulting in improved cardiac function; however, mechanisms for normoxic neonatal CPC exosomes improved function independent of those mechanisms. This is the first study of its kind demonstrating that donor age and oxygen content in the microenvironment significantly alter the efficacy of human CPC-derived exosomes.

Salvianolic acid B induced upregulation of miR-30a protects cardiac myocytes from ischemia/reperfusion injury

BACKGROUND

MicroRNAs (miRNAs) are a novel class of powerful, endogenous regulators of gene expression. This study was designed to ascertain if miR-30a is involved in the cardioprotective actions of salvianolic acid B (Sal B) against myocardial ischemia-reperfusion (I-R) injury through suppression of autophagy.

METHODS

Murine myocardial cells that had undergone primary culture were induced by I-R and incubated with Sal B (25, 50, 100 μM) in the presence of a miR-30a mimic or miR-30a inhibitor. Expression of miR-30a, beclin-1, LC3-II and p-Akt protein, cell viability, and lactic acid dehydrogenase (LDH) release were assessed.

RESULTS

miR-30a expression was down-regulated remarkably in I-R cells, and this suppression could be reversed by Sal B in a dose-dependent manner. Sal B repressed autophagy in I-R myocardial cells. Sal B improved cell viability and reduced the rate of LDH leakage, which suggested that autophagy suppression was beneficial for cell survival. Knockdown of miR-30a with a miR-30a inhibitor could reverse the anti-autophagy effect of Sal B against I-R injury. Furthermore, we confirmed that Sal B has a protective role in miR-30a-mediated autophagy through the PI3K/Akt signaling pathway, which was abrogated by the PI3K inhibitor LY294002.

CONCLUSIONS

These data suggest that miR-30a is involved in Sal B-mediated cardioprotection against I-R injury through the PI3K/Akt signaling pathway.

AMPK in cardiac fibrosis and repair: Actions beyond metabolic regulation

Fibrosis is a general term encompassing a plethora of pathologies that span all systems and is marked by increased deposition of collagen. Injury of variable etiology gives rise to complex cascades involving several cell-types and molecular signals, leading to the excessive accumulation of extracellular matrix that promotes fibrosis and eventually leads to organ failure. Cardiac fibrosis is a dynamic process associated notably with ischemia, hypertrophy, volume- and pressure-overload, aging and diabetes mellitus. It has profoundly deleterious consequences on the normal architecture and functioning of the myocardium and is associated with considerable mortality and morbidity. The AMP-activated protein kinase (AMPK) is a ubiquitously expressed cellular energy sensor and an essential component of the adaptive response to cardiomyocyte stress that occurs during ischemia. Nevertheless, its actions extend well beyond its energy-regulating role and it appears to possess an essential role in regulating fibrosis of the myocardium. In this review paper, we will summarize the main elements and crucial players of cardiac fibrosis. In addition, we will provide an overview of the diverse roles of AMPK in the heart and discuss in detail its implication in cardiac fibrosis. Lastly, we will highlight the recently published literature concerning AMPK-targeting current therapy and novel strategies aiming to attenuate fibrosis.

miR-29c regulates NAV3 protein expression in a transgenic mouse model of Alzheimer's disease

The microRNA-29 family (miRNA-29s) has three mature members, miR-29a, miR-29b and miR-29c, which have been implicated in the regulation of the pathogenesis of Alzheimer's disease (AD). The miR-29 family members exhibit differential regulation in various diseases and different subcellular distribution. In the present study, we initially investigated differential expression of miR-29c in the hippocampus and the frontal cortex of the young APPswe/PSΔE9 mouse brain, accompanied by inverse expression of neurone navigator 3 (NAV3), a regulator of axon guidance. We observed that miR-29c directly mediated downregulation of NAV3 protein expression in vitro. The mouse NAV3 mRNA has a functional miR-29c binding site in the 3' UTR, which localized in the position between 830-836 bp of 3'UTR region, slightly different from human NAV3 mRNA binding site. These observations suggest that miR-29c may be involved in neurodegenerative processes by regulating NAV3 expression in the young AD mouse.

Blood-based microRNA signatures differentiate various forms of cardiac hypertrophy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is caused by mutations in different structural genes and induces pathological hypertrophy with sudden cardiac death as a possible consequence. HCM can be separated into hypertrophic non-obstructive and obstructive cardiomyopathy (HNCM/HOCM) with different clinical treatment approaches. We here distinguished between HNCM, HOCM, cardiac amyloidosis and aortic stenosis by using microRNA profiling and investigated potential interactions between circulating miRNA levels and the most common mutations in MYH7and MYBPC3 genes.

METHODS

Our study included 4 different groups: 23 patients with HNCM, 28 patients with HOCM, 47 patients with aortic stenosis and 22 healthy controls. Based on previous findings, 8 different cardiovascular known microRNAs (miR-1, miR-21, miR-29a, miR-29b, miR-29c, miR-133a, miR-155 and miR-499) were studied in serum of all patients and compared with clinically available patient data.

RESULTS

We found miR-29a levels to be increased in patients with HOCM and correlating markers of cardiac hypertrophy. This was not the case in HNCM patients. In contrast, we identified miR-29c to be upregulated in aortic stenosis but not the other patient groups. ROC curve analysis of miR-29a/c distinguished between HOCM patients and aortic stenosis patients. MiR-29a and miR-155 levels discriminated HNCM patients from patients with senile cardiac amyloidosis. MiR-29a increased mainly in HOCM patients with a mutation in MYH7, whereas miR-155 was decreased in hypertrophic cardiomyopathy patients with a mutation in MYBPC3.

CONCLUSION

We demonstrated that miR-29a and miR-29c show a specific signature to distinguish between aortic stenosis, hypertrophic non-obstructive and obstructive cardiomyopathies and thus could be developed into clinically useful biomarkers.

Evaluation of miR-29c inhibits endotheliocyte migration and angiogenesis of human endothelial cells by suppressing the insulin like growth factor 1

MicroRNAs, a class of 22-nucleotide non-coding RNAs, modulate gene expression by associating with the 3'-untranslated regions (3'- UTRs) of messenger RNAs (mRNAs). Although multiple miRNAs are known to be regulated during angiogenesis, their individual roles in blood vessel development are still not fully understood. Herein, we investigate the role of miR-29c in regulating cell cycle and angiogenic phenotype of endothelial cells. The results showed that IGF-1 is highly expressed and down-regulated by miR-29c in human umbilical vein endothelial cells (HUVEC). Consistent with this preliminary finding, introduction of exogenous miR-29c or miR-29c inhibitor alters cell cycle progression, proliferation and tube formation of HUVEC, respectively. Furthermore, by using luciferase reporter assay, we find that the expression of IGF-1, a suppressor transcription factor, is directly regulated by miR-29c through 3'-UTR. In addition, we show that the selective inhibition of PI3K/AKT pathway prior to miR-29c stimulation prevents the expression of angiogenesis suppressor miRNAs that are family and cluster specific. As a conclusion, we find that miR-29c plays a significant role in regulating cell cycle, proliferation and angiogenic properties of HUVECs. This function is likely mediated through IGF-1 proteins at the post-transcriptional level. As a novel molecular target, miR-29c may have a potential value in the treatment of angiogenesis-associated diseases, such as cardiovascular diseases and cancers.

Evaluation of miR-29c inhibits endotheliocyte migration and angiogenesis of human endothelial cells by suppressing the insulin like growth factor 1

MicroRNAs, a class of 22-nucleotide non-coding RNAs, modulate gene expression by associating with the 3'-untranslated regions (3'-UTRs) of messenger RNAs (mRNAs). Although multiple miRNAs are known to be regulated during angiogenesis, their individual roles in blood vessel development are still not fully understood. Herein, we investigate the role of miR-29c in regulating cell cycle and angiogenic phenotype of endothelial cells. The results showed that IGF-1 is highly expressed and down-regulated by miR-29c in human umbilical vein endothelial cells (HUVEC). Consistent with this preliminary finding, introduction of exogenous miR-29c or miR-29c inhibitor alters cell cycle progression, proliferation and tube formation of HUVEC, respectively. Furthermore, by using luciferase reporter assay, we find that the expression of IGF-1, a suppressor transcription factor, is directly regulated by miR-29c through 3'-UTR. In addition, we show that the selective inhibition of PI3K/AKT pathway prior to miR-29c stimulation prevents the expression of angiogenesis suppressor miRNAs that are family and cluster specific. As a conclusion, we find that miR-29c plays a significant role in regulating cell cycle, proliferation and angiogenic properties of HUVECs. This function is likely mediated through IGF-1 proteins at the post-transcriptional level. As a novel molecular target, miR-29c may have a potential value in the treatment of angiogenesis-associated diseases, such as cardiovascular diseases and cancers.