Toll-like receptor 5 deficiency attenuates interstitial cardiac fibrosis and dysfunction induced by pressure overload by inhibiting inflammation and the endothelial–mesenchymal transition

Pathophysiology in Brain Arteriovenous Malformations: Focus on Endothelial Dysfunctions and Endothelial-to-Mesenchymal Transition

Brain arteriovenous malformations (bAVMs) substantially increase the risk for intracerebral hemorrhage (ICH), which is associated with significant morbidity and mortality. However, the treatment options for bAVMs are severely limited, primarily relying on invasive methods that carry their own risks for intraoperative hemorrhage or even death. Currently, there are no pharmaceutical agents shown to treat this condition, primarily due to a poor understanding of bAVM pathophysiology. For the last decade, bAVM research has made significant advances, including the identification of novel genetic mutations and relevant signaling in bAVM development. However, bAVM pathophysiology is still largely unclear. Further investigation is required to understand the detailed cellular and molecular mechanisms involved, which will enable the development of safer and more effective treatment options. Endothelial cells (ECs), the cells that line the vascular lumen, are integral to the pathogenesis of bAVMs. Understanding the fundamental role of ECs in pathological conditions is crucial to unraveling bAVM pathophysiology. This review focuses on the current knowledge of bAVM-relevant signaling pathways and dysfunctions in ECs, particularly the endothelial-to-mesenchymal transition (EndMT).

Not just fibrotic: endothelial-derived TGFβ maintains contractile function and lymphatic muscle phenotype during homeostasis

Cell-cell communication within the lymphatic vasculature during homeostasis is incompletely detailed. Although many discoveries highlight the pathological roles of transforming growth factor-beta (TGFβ) in chronic vascular inflammation and associated fibrosis, only a small amount is known surrounding the role of TGFβ-signaling in homeostatic lymphatic function. Here, we discovered that pharmacological blockade of TGFβ receptor 1 (TGFβR1) negatively impacts rat mesenteric lymphatic vessel pumping, significantly reducing vessel contractility and surrounding lymphatic muscle coverage. We have identified mesenteric lymphatic endothelial cells themselves as a source of endogenous vascular TGFβ and that TGFβ production is significantly increased in these cells via activation of a number of functional pattern recognition receptors they express. We show that a continuous supply of TGFβ is essential to maintain the contractile phenotype of neighboring lymphatic muscle cells and support this conclusion through in vitro analysis of primary isolated lymphatic muscle cells that undergo synthetic differentiation during 2-D cell culture, a phenomenon that could be effectively rescued by supplementation with recombinant TGFβ. Finally, we demonstrate that lymphatic endothelial production of TGFβ is regulated, in part, by nitric oxide in a manner we propose is essential to counteract the pathological over-production of TGFβ. Taken together, these data highlight the essential role of homeostatic TGFβ signaling in the maintenance of lymphatic vascular function and highlight possible deleterious consequences of its inhibition.NEW & NOTEWORTHY The growth factor TGFβ is commonly associated with its pathological overproduction during tissue fibrosis rather than its homeostatic functions. We expose the lymphatic endothelium as a source of endogenous TGFβ, the impact of its production on the maintenance of surrounding lymphatic muscle cell phenotype, and internally regulated mechanisms of its production. Overall, these results highlight the intricate balance of TGFβ-signaling as an essential component of maintaining lymphatic contractile function.

Flagellin-Induced Immune Response in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Pathogen-associated molecular patterns (PAMPs) are involved in the pathogenesis of septic cardiomyopathy through a toll-like receptor (TLR)-mediated immune response. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) can reflect the innate immune abilities of cardiomyocytes. Therefore, hiPSC-CMs may provide an attractive tool with which to study PAMP-induced alterations in cardiomyocytes. HiPSC-CMs from two different healthy donors were exposed to the PAMP flagellin (FLA) at different doses and exposure times. Alterations in the expression levels of distinct inflammation-associated cytokines, intracellular inflammation pathways including TLR5 downstream signaling, reactive oxygen species levels and surface antigen composition were assessed using PCR, ELISA and FACS techniques. Higher doses of flagellin increased the expression levels of inflammation-associated cytokines like TNFα (p < 0.01) and downstream signaling molecules like caspase-8 (p < 0.05). TLR5 expression (p < 0.01) and TLR5 fluorescence proportion (p < 0.05) increased in hiPSC-CMs after prolonged FLA exposure. FLA-induced innate immune response processes in cardiomyocytes might be detectable with an hiPSC-CMs-based in vitro model.

Escherichia coli Promotes Endothelial to Mesenchymal Transformation of Liver Sinusoidal Endothelial Cells and Exacerbates Nonalcoholic Fatty Liver Disease Via Its Flagellin

BACKGROUND＆AIMS: Gut bacteria translocate into the liver through a disrupted gut vascular barrier, which is an early and common event in the development of nonalcoholic fatty liver disease (NAFLD). Liver sinusoidal endothelial cells (LSECs) are directly exposed to translocated gut microbiota in portal vein blood. Escherichia coli, a commensal gut bacterium with flagella, is markedly enriched in the gut microbiota of patients with NAFLD. However, the impact of E coli on NAFLD progression and its underlying mechanisms remains unclear.

METHODS

The abundance of E coli was analyzed by using 16S ribosomal RNA sequencing in a cohort of patients with NAFLD and healthy controls. The role of E coli was assessed in NAFLD mice after 16 weeks of administration, and the features of NAFLD were evaluated. Endothelial to mesenchymal transition (EndMT) in LSECs induced by E coli was analyzed through Western blotting and immunofluorescence.

RESULTS

The abundance of gut Enterobacteriaceae increased in NAFLD patients with severe fat deposition and fibrosis. Importantly, translocated E coli in the liver aggravated hepatic steatosis, inflammation, and fibrosis in NAFLD mice. Mechanistically, E coli induced EndMT in LSECs through the TLR5/MYD88/TWIST1 pathway during NAFLD development. The toll-like receptor 5 inhibitor attenuated E coli-induced EndMT in LSECs and liver injury in NAFLD mice. Interestingly, flagellin-deficient E coli promoted less EndMT in LSECs and liver injury in NAFLD mice.

CONCLUSIONS

E coli promoted the development of NAFLD and promoted EndMT in LSECs through toll-like receptor 5/nuclear factor kappa B-dependent activation of TWIST1 mediated by flagellin. Therapeutic interventions targeting E coli and/or flagellin may represent a promising candidate for NAFLD treatment.

Toll-like receptors in cardiac hypertrophy

Toll-like receptors (TLRs) are a family of pattern recognition receptors (PRRs) that can identify pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). TLRs play an important role in the innate immune response, leading to acute and chronic inflammation. Cardiac hypertrophy, an important cardiac remodeling phenotype during cardiovascular disease, contributes to the development of heart failure. In previous decades, many studies have reported that TLR-mediated inflammation was involved in the induction of myocardium hypertrophic remodeling, suggesting that targeting TLR signaling might be an effective strategy against pathological cardiac hypertrophy. Thus, it is necessary to study the mechanisms underlying TLR functions in cardiac hypertrophy. In this review, we summarized key findings of TLR signaling in cardiac hypertrophy.

Cardiomyocyte-specific Peli1 contributes to the pressure overload-induced cardiac fibrosis through miR-494-3p-dependent exosomal communication

Cardiac fibrosis is an essential pathological process in pressure overload (PO)-induced heart failure. Recently, myocyte-fibroblast communication is proven to be critical in heart failure, in which, pathological growth of cardiomyocytes (CMs) may promote fibrosis via miRNAs-containing exosomes (Exos). Peli1 regulates the activation of NF-κB and AP-1, which has been demonstrated to engage in miRNA transcription in cardiomyocytes. Therefore, we hypothesized that Peli1 in CMs regulates the activation of cardiac fibroblasts (CFs) through an exosomal miRNA-mediated paracrine mechanism, thereby promoting cardiac fibrosis. We found that CM-conditional deletion of Peli1 improved PO-induced cardiac fibrosis. Moreover, Exos from mechanical stretch (MS)-induced WT CMs (WT MS-Exos) promote activation of CFs, Peli1^-/- MS-Exos reversed it. Furthermore, miRNA microarray and qPCR analysis showed that miR-494-3p was increased in WT MS-Exos while being down regulated in Peli1^-/- MS-Exos. Mechanistically, Peli1 promoted miR-494-3p expression via NF-κB/AP-1 in CMs, and then miR-494-3p induced CFs activation by inhibiting PTEN and amplifying the phosphorylation of AKT, SMAD2/3, and ERK. Collectively, our study suggests that CMs Peli1 contributes to myocardial fibrosis via CMs-derived miR-494-3p-enriched exosomes under PO, and provides a potential exosomal miRNA-based therapy for cardiac fibrosis.

LRRK2 deficiency protects the heart against myocardial infarction injury in mice via the P53/HMGB1 pathway

LRRK2 is a Ser/Thr kinase with multiple functional domains. Studies have shown that LRRK2 mutations are closely related to hereditary Parkinson's disease. However, its role in cardiovascular disease, especially in myocardial infarction, is unclear. The aim of this study was to explore the functional role of LRRK2 in myocardial infarction. Wild-type and LRRK2-knockout mice were subjected to coronary artery ligation (left anterior descending) to establish a myocardial infarction model. Neonatal rat cardiomyocytes were subjected to hypoxia to induce hypoxic injury in vitro. We found increased LRRK2 expression levels in the infarct periphery in mouse hearts and hypoxic cardiomyocytes. LRRK2-deficient mice exhibited decreased death rates and reduced infarction areas compared to wild-type controls 14 days after infarction. LRRK2-deficient mice showed reduced left ventricular fibrosis and inflammatory responses, as well as improved cardiac function. In the in vitro study, LRRK2 silencing decreased cleaved caspase-3 activity, reduced cardiomyocyte apoptosis, and diminished hypoxia-induced inflammation. However, LRRK2 overexpression enhanced cleaved caspase-3 activity, increased the number of apoptotic cardiomyocytes, and caused remarkable hypoxia-induced inflammation. When examining the underlying mechanisms, we found that hypoxia increased HIFα expression, which enhanced LRRK2 expression. LRRK2 induced high expression of HMGB1 via P53. When HMGB1 was blocked using an anti-HMGB1 antibody, the deleterious effects caused by LRRK2 overexpression following hypoxia were inhibited in cardiomyocytes. In summary, LRRK2 deficiency protects the heart against myocardial infarction injury. The mechanism underlying this effect involves the P53-HMGB1 pathway.

Tumor Necrosis Factor-α-Induced Protein 8-Like 2 Ameliorates Cardiac Hypertrophy by Targeting TLR4 in Macrophages

Background

Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2), a novel immunoregulatory protein, has been reported to regulate inflammation and apoptosis. The role of TIPE2 in cardiovascular disease, especially cardiac hypertrophy, has not been elucidated. Thus, the aim of the present study was to explore the role of TIPE2 in cardiac hypertrophy.

Methods

Mice were subjected to aortic banding (AB) to induce an adverse hypertrophic model. To overexpress TIPE2, mice were injected with a lentiviral vector expressing TIPE2. Echocardiographic and hemodynamic analyses were used to evaluate cardiac function. Neonatal rat cardiomyocytes (NRCMs) and mouse peritoneal macrophages (MPMs) were isolated and stimulated with angiotensin II. NRCMs and MPM were also cocultured and stimulated with angiotensin II. Cells were transfected with Lenti-TIPE2 to overexpress TIPE2.

Results

TIPE2 expression levels were downregulated in hypertrophic mouse hearts and in macrophages in heart tissue. TIPE2 overexpression attenuated pressure overload-induced cardiac hypertrophy, fibrosis, and cardiac dysfunction. Moreover, we found that TIPE2 overexpression in neonatal cardiomyocytes did not relieve the angiotensin II-induced hypertrophic response in vitro. Furthermore, TIPE2 overexpression downregulated TLR4 and NF-κB signaling in macrophages but not in cardiomyocytes, which led to diminished inflammation in macrophages and consequently reduced the activation of hypertrophic Akt signaling in cardiomyocytes. TLR4 inhibition by TAK-242 did not enhance the antihypertrophic effect of TIPE2 overexpression.

Conclusions

The present study indicated that TIPE2 represses macrophage activation by targeting TLR4, subsequently inhibiting cardiac hypertrophy.

Suppression of ADAM8 attenuates angiotensin II-induced cardiac fibrosis and endothelial-mesenchymal transition via inhibiting TGF-β1/Smad2/Smad3 pathways

Endothelial-to-mesenchymal transition (EndMT) is involved in cardiac fibrosis induced by angiotensin II (Ang II). A disintegrin and metalloproteinase 8 (ADAM8), a member of ADAMs family, participates in cell adhesion, proteolysis and various signaling. However, its effects on the development of cardiac fibrosis remain completely unknown. This study aimed to reveal whether ADAM8 aggravates cardiac fibrosis induced by Ang II in vivo and in vitro. The C57BL/6J mice or cardiac endothelial cells were subjected to Ang II infusion to induce fibrosis. The results showed that systolic blood pressure and diastolic blood pressure were significantly increased under Ang II infusion, and ADAM8 was up-regulated. ADAM8 inhibition attenuated Ang II-induced cardiac dysfunction. ADAM8 knockdown suppressed Ang II-induced cardiac fibrosis as evidenced by the down-regulation of CTGF, collagen I, and collagen III. In addition, the endothelial marker (VE-cadherin) was decreased, whilst mesenchymal markers (α-SMA and FSP1) were increased following Ang II infusion. However, ADAM8 repression inhibited Ang II-induced EndMT. Moreover, ADAM8 silencing repressed the activation of TGF-β1/Smad2/Smad3 pathways. Consistent with the results in vivo, we also found the inhibitory effects of ADAM8 inhibition on EndMT in vitro. All data suggest that ADAM8 promotes Ang II-induced cardiac fibrosis and EndMT via activating TGF-β1/Smad2/Smad3 pathways.

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

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

Leucine-rich repeat kinase-2 deficiency protected against cardiac remodelling in mice via regulating autophagy formation and degradation

•

LRRK2 deficiency protected cardiac remodelling induced by pressure overload

•

LRRK2 deficiency preserved cardiac function by regulating both autophagosome formation and degradation.

•

LRRK2 regulates autophagosome formation by regulating Bcl2 and Beclin1 interaction.

•

LRRK2 regulates autophagosome fusion by interacting with Rab7.

•

LRRK2 may become a target of new therapeutic methods for treating heart failure.

Introduction

Leucine-rich repetitive kinase-2 (LRRK2) is a Parkinson's disease-related gene that also participates in many inflammatory diseases. However, the functional role of LRRK2 in cardiovascular disease is not clear.

Objective

In this study, we aimed to elucidate the role of LRRK2 in cardiac remodelling under pressure overload.

Methods

Aortic banding surgery was performed to induce cardiac remodelling in a LRRK2 knockout mouse model. A cardiomyocyte remodelling model was established by phenylephrine (PE) stimulation in neonatal rat cardiomyocytes.

Results

LRRK2 was upregulated in remodelled mouse hearts and cardiomyocytes. Cardiac hypertrophy, fibrosis and dysfunction were ameliorated in LRRK2 knockout mice. LRRK2 silencing protected against the PE-induced cardiomyocyte hypertrophic response, while LRRK2 over-expression worsened the PE-induced hypertrophic response in cardiomyocytes. Decreased autophagy was observed in remodelled cardiomyocytes, whereas LRRK2 silencing increased autophagy levels and LRRK2 overexpression reduced autophagy levels. The autophagy inhibitors 3-MA, bafilomycin and chloroquine reversed the protective effects of LRRK2 deficiency. The autophagy activator rapamycin reversed the deleterious effects of LRRK2 overexpression. We found that LRRK2 inhibited Bcl-2 phosphorylation, thus decreasing the phosphorylation of Beclin1. The protective effects of LRRK2 knockout were partly counteracted by Beclin1(+/−) in vivo and Beclin1 silencing in vitro. We also observed an interaction between LRRK2 and Rab7, an autolysosome degradation-associated protein, which caused Rab7 downregulation. Rab7 knockdown almost completely reversed LRRK2 silencing-induced protection of cardiomyocytes

Conclusion

LRRK2 deficiency protected against cardiac remodelling under pressure overload by increasing Bcl-2/Beclin1 and Rab7-regulated autophagy levels in the heart.

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

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

PGAM1 deficiency ameliorates myocardial infarction remodeling by targeting TGF-β via the suppression of inflammation, apoptosis and fibrosis

Myocardial ischemia-reperfusion (MIR) represents critical challenge for the treatment of acute myocardial infarction diseases. Presently, identifying the molecular basis revealing MIR progression is scientifically essential and may provide effective therapeutic strategies. Phosphoglycerate mutase 1 (PGAM1) is a key aerobic glycolysis enzyme, and exhibits critical role in mediating several biological events, such as energy production and inflammation. However, whether PGAM1 can affect MIR is unknown. Here we showed that PGAM1 levels were increased in murine ischemic hearts. Mice with cardiac knockout of PGAM1 were resistant to MIR-induced heart injury, evidenced by the markedly reduced infarct volume, improved cardiac function and histological alterations in cardiac sections. In addition, inflammatory response, apoptosis and fibrosis in hearts of mice with MIR operation were significantly alleviated by the cardiac deletion of PGAM1. Mechanistically, the activation of nuclear transcription factor κB (NF-κB), p38, c-Jun NH2-terminal kinase (JNK) and transforming growth factor β (TGF-β) signaling pathways were effectively abrogated in MI-operated mice with specific knockout of PGAM1 in hearts. The potential of PGAM1 suppression to inhibit inflammatory response, apoptosis and fibrosis were verified in the isolated cardiomyocytes and fibroblasts treated with oxygen-glucose deprivation reperfusion (OGDR) and TGF-β, respectively. Importantly, PGAM1 directly interacted with TGF-β to subsequently mediate inflammation, apoptosis and collagen accumulation, thereby achieving its anti-MIR action. Collectively, these findings demonstrated that PGAM1 was a positive regulator of myocardial infarction remodeling due to its promotional modulation of TGF-β signaling, indicating that PGAM1 may be a promising therapeutic target for MIR treatment.

Candidate rejuvenating factor GDF11 and tissue fibrosis: friend or foe?

Growth differentiation factor 11 (GDF11 or bone morphogenetic protein 11, BMP11) belongs to the transforming growth factor-β superfamily and is closely related to other family member-myostatin (also known as GDF8). GDF11 was firstly identified in 2004 due to its ability to rejuvenate the function of multiple organs in old mice. However, in the past few years, the heralded rejuvenating effects of GDF11 have been seriously questioned by many studies that do not support the idea that restoring levels of GDF11 in aging improves overall organ structure and function. Moreover, with increasing controversies, several other studies described the involvement of GDF11 in fibrotic processes in various organ setups. This review paper focuses on the GDF11 and its pro- or anti-fibrotic actions in major organs and tissues, with the goal to summarize our knowledge on its emerging role in regulating the progression of fibrosis in different pathological conditions, and to guide upcoming research efforts.

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

Rationale: Clinical application of doxorubicin (DOX) is limited by its toxic cardiovascular side effects. Our previous study found that toll-like receptor (TLR) 5 deficiency attenuated cardiac fibrosis in mice. However, the role of TLR5 in DOX-induced cardiotoxicity remains unclear.

Methods: To further investigate this, TLR5-deficient mice were subjected to a single intraperitoneal injection of DOX to mimic an acute model.

Results: Here, we reported that TLR5 expression was markedly increased in response to DOX injection. Moreover, TLR5 deficiency exerted potent protective effects against DOX-related cardiac injury, whereas activation of TLR5 by flagellin exacerbated DOX injection-induced cardiotoxicity. Mechanistically, the effects of TLR5 were largely attributed to direct interaction with spleen tyrosine kinase to activate NADPH oxidase (NOX) 2, increasing the production of superoxide and subsequent activation of p38. The toxic effects of TLR5 activation in DOX-related acute cardiac injury were abolished by NOX2 deficiency in mice. Our further study showed that neutralizing antibody-mediated TLR5 depletion also attenuated DOX-induced acute cardiotoxicity.

Conclusion: These findings suggest that TLR5 deficiency attenuates DOX-induced cardiotoxicity in mice, and targeting TLR5 may provide feasible therapies for DOX-induced acute cardiotoxicity.

Selective deletion of MyD88 signaling in α-SMA positive cells ameliorates experimental intestinal fibrosis via post-transcriptional regulation

Intestinal fibrosis leading to strictures remains a significant clinical problem in inflammatory bowel diseases (IBD). The role of bacterial components in activating intestinal mesenchymal cells and driving fibrogenesis is largely unexplored. Tamoxifen-inducible α-SMA promoter Cre mice crossed with floxed MyD88 mice were subjected to chronic dextran sodium sulfate colitis. MyD88 was deleted prior to or after induction of colitis. Human intestinal myofibroblasts (HIMF) were exposed to various bacterial components and assessed for fibronectin (FN) and collagen I (Col1) production. RNA sequencing was performed. Post-transcriptional regulation was assessed by polysome profiling assay. Selective deletion of MyD88 in α-SMA-positive cells prior to, but not after induction of, experimental colitis decreased the degree of intestinal fibrosis. HIMF selectively responded to flagellin with enhanced FN or Col1 protein production in a MyD88-dependent manner. RNA sequencing suggested minimal transcriptional changes induced by flagellin in HIMF. Polysome profiling revealed higher proportions of FN and Col1 mRNA in the actively translated fractions of flagellin exposed HIMF, which was mediated by eIF2 alpha and 4EBP1. In conclusion, selectivity of flagellin-induced ECM secretion in HIMF is post-transcriptionally regulated. The results may represent a novel and targetable link between the gut microbiota and intestinal fibrogenesis.

PTX3 Predicts Myocardial Damage and Fibrosis in Duchenne Muscular Dystrophy

Pentraxin 3 (PTX3) is a main component of the innate immune system by inducing complement pathway activation, acting as an inflammatory mediator, coordinating the functions of macrophages/dendritic cells and promoting apoptosis/necrosis. Additionally, it has been found in fibrotic regions co-localizing with collagen. In this work, we wanted to investigate the predictive role of PTX3 in myocardial damage and fibrosis of Duchenne muscular dystrophy (DMD). DMD is an X-linked recessive disease caused by mutations of the dystrophin gene that affects muscular functions and strength and accompanying dilated cardiomyopathy. Here, we expound the correlation of PTX3 cardiac expression with age and Toll-like receptors (TLRs)/interleukin-1 receptor (IL-1R)-MyD88 inflammatory markers and its modulation by the so-called alarmins IL-33, high-mobility group box 1 (HMGB1), and S100β. These findings suggest that cardiac levels of PTX3 might have prognostic value and potential in guiding therapy for DMD cardiomyopathy.

CTRP12 Ameliorated Lipopolysaccharide-Induced Cardiomyocyte Injury

C1q/tumor necrosis factor (TNF)-related protein 12 (CTRP12) is a secretory protein that participates in the regulation of glucose and lipid metabolism in obesity and diabetes. Its role in cardiovascular disease, particularly sepsis-induced cardiac injury, is unclear. Here, we stimulated cardiomyocytes with lipopolysaccharide (LPS) to establish an in vitro cardiomyocyte injury model and CTRP12 was overexpressed with an adenovirus delivery system. Overexpression of CTRP12 reduced the transcription and release of pro-inflammatory cytokines from LPS-stimulated cardiomyocytes, including TNFα, interleukin-1 (IL-1), and IL-6. Reactive oxygen species (ROS) level increased and the oxidation/redox system was disturbed in LPS-stimulated cardiomyocytes, as evident from the decrease in superoxide dismutase activity and an increase in reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and malondialdehyde level. CTRP12 overexpression decreased the increasing level of ROS and ameliorated the unbalance in the oxidation/redox system in LPS-stimulated cardiomyocytes. The viability of cardiomyocytes decreased after LPS stimulation, and the cells underwent apoptosis. CTRP12-overexpressing cardiomyocytes showed a decrease in the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive cells, and the ratio of B cell lymphoma (Bcl)-1/Bax in these cells was recovered. In comparison with the control group, LPS-stimulated cardiomyocytes showed reduced expression of nuclear factor E2-related factor 2 (NRF2), while CTRP12-overexpressing cardiomyocytes showed elevated NRF2 expression. Small-interfering RNA-mediated silencing of NRF2 expression in cardiomyocytes resulted in the inhibition of the protective effects of CTRP12. Thus, CTRP12 ameliorated injury in LPS-stimulated cardiomyocytes in an NRF2-dependent manner.

Endothelial Dysfunction in Obesity-Induced Inflammation: Molecular Mechanisms and Clinical Implications

Obesity is characterized by the excessive deposition of fat that may interfere with the normal metabolic process of the body. It is a chronic condition associated with various metabolic syndromes, whose prevalence is grossly increasing, and affects both children and adults. Accumulation of excessive macronutrients on the adipose tissues promotes the secretion and release of inflammatory mediators, including interleukin-6 (IL-6), interleukin 1β, tumor necrotic factor-α (TNF-α), leptin, and stimulation of monocyte chemoattractant protein-1 (MCP-1), which subsequently reduce the production of adiponectin thereby initiating a proinflammatory state. During obesity, adipose tissue synthesizes and releases a large number of hormones and cytokines that alter the metabolic processes, with a profound influence on endothelial dysfunction, a situation associated with the formation of atherosclerotic plaque. Endothelial cells respond to inflammation and stimulation of MCP-1, which is described as the activation of adhesion molecules leading to proliferation and transmigration of leukocytes, which facilitates their increase in atherogenic and thromboembolic potentials. Endothelial dysfunction forms the cornerstone of this discussion, as it has been considered as the initiator in the progression of cardiovascular diseases in obesity. Overexpression of proinflammatory cytokines with subsequent reduction of anti-inflammatory markers in obesity, is considered to be the link between obesity-induced inflammation and endothelial dysfunction. Inhibition of inflammatory mechanisms and management and control of obesity can assist in reducing the risks associated with cardiovascular complications.

A cathelicidin-related antimicrobial peptide suppresses cardiac hypertrophy induced by pressure overload by regulating IGFR1/PI3K/AKT and TLR9/AMPKα

Cathelicidin-related antimicrobial peptide (CRAMP), an antimicrobial peptide, was reported to protect against myocardial ischemia/reperfusion injury. However, the effect of CRAMP on pressure overload-induced cardiac hypertrophy was unknown. This study explored the role of CRAMP on cardiac hypertrophy. A cardiac hypertrophy mouse model was induced by aortic banding surgery. Seven days after surgery, mice were given mCRAMP by intraperitoneal injection (8 mg/kg/d) for 7 weeks. Cardiac hypertrophy was evaluated by the hypertrophic response and fibrosis level as well as cardiac function. Mice were also injected with AAV9-shCRAMP to knockdown CRAMP in the mouse heart. CRAMP levels first increased and then reduced in the remodeling heart, as well as in angiotensin II-stimulated endothelial cells but not in cardiomyocytes and fibroblasts. mCRAMP protected against the pressure overload-induced cardiac remodeling process, while CRAMP knockdown accelerated this process. mCRAMP reduced the inflammatory response and oxidative stress in the hypertrophic heart, while mCRAMP deficiency deteriorated the pressure overload-induced inflammatory response and oxidative stress. mCRAMP inhibited the angiotensin II-stimulated hypertrophic response and oxidative stress in neonatal rat cardiomyocytes, but mCRAMP did not help the angiotensin II-induced inflammatory response and oxidative stress in endothelial cells. Mechanistically, we found that mCRAMP suppressed the cardiac hypertrophic response by activating the IGFR1/PI3K/AKT pathway via directly binding to IGFR1. AKT knockout mice completely reversed the anti-hypertrophic effect of mCRAMP but not its anti-oxidative effect. We also found that mCRAMP ameliorated cardiac oxidative stress by activating the TLR9/AMPKa pathway. This was confirmed by a TLR9 knockout mouse experiment, in which a TLR9 knockout partly reversed the anti-hypertrophic effect of mCRAMP and completely counteracted the anti-oxidative effect of mCRAMP. In summary, mCRAMP protected against pressure overload-induced cardiac hypertrophy by activating both the IGFR1/PI3K/AKT and TLR9/AMPKa pathways in cardiomyocytes.

Interleukin-9 Aggravates Isoproterenol-Induced Heart Failure by Activating Signal Transducer and Activator of Transcription 3 Signalling

BACKGROUND

Previous studies have demonstrated that inflammation is closely related to the occurrence and development of heart failure (HF). As an inflammation-related cytokine, interleukin (IL)-9 has been reported to be involved in the development of cardiovascular diseases. However, the role of IL-9 in HF in response to isoproterenol (ISO) stimulation has barely been explored. Thus, this study aimed to investigate whether IL-9 participates in HF and the possible associated mechanisms.

METHODS

Chronic ISO infusion was used to establish an HF model, and the IL-9 levels in mice and isolated cardiomyocytes were measured. In addition, ISO-treated mice received an injection of recombinant mouse IL-9 (rIL-9) or an antimouse IL-9 neutralizing monoclonal antibody (mAb) to investigate the effects of IL-9 on cardiac function, hypertrophy, and fibrosis.

RESULTS

IL-9 levels were significantly increased in mice and isolated cardiomyocytes after ISO treatment. Treatment with rIL-9 resulted in aggravated cardiac dysfunction and amplified cardiac hypertrophy and fibrosis, whereas treatment with the anti-IL-9 neutralizing mAb ameliorated cardiac dysfunction and reduced cardiac hypertrophy and fibrosis in ISO-treated mice. In addition, ISO infusion-induced cardiac inflammation and cardiomyocyte apoptosis was aggravated by rIL-9 but prevented by the anti-IL-9 mAb. IL-9 did not activate signal transducer and activator of transcription (STAT)1 or STAT5 but induced STAT3 phosphorylation in ISO-induced HF. Moreover, S31-201, a specific STAT3 inhibitor, nearly abolished rIL-9-induced increases in cardiac dysfunction, hypertrophy, and fibrosis in response to ISO stimulation.

CONCLUSIONS

IL-9 aggravated cardiac dysfunction and amplified cardiac hypertrophy and fibrosis in the ISO-induced HF model by activating STAT3 signalling. These data indicate that blocking IL-9 may be an attractive pharmacotherapeutic strategy for the treatment of cardiac hypertrophy and fibrosis induced by chronic β-adrenergic receptor activation to limit the progression of HF.

Research Progress of Mechanisms and Drug Therapy For Atherosclerosis on Toll-Like Receptor Pathway

Recent reports have established atherosclerosis (AS) as a major factor in the pathogenetic process of cardiovascular diseases such as ischemic stroke and coronary heart disease. Although the possible pathogenesis of AS remains to be elucidated, a large number of investigations strongly suggest that the inhibition of toll-like receptors (TLRs) alleviates the severity of AS to some extent by suppressing vascular inflammation and the formation of atherosclerotic plaques. As pattern recognition receptors, TLRs occupy a vital position in innate immunity, mediating various signaling pathways in infective and sterile inflammation. This review summarizes the available data on the research progress of AS and the latest antiatherosclerotic drugs associated with TLR pathway.

The role of toll-like receptors in myocardial toxicity induced by doxorubicin

Doxorubicin is an effective antitumor drug commonly used in the treatment of a wide variety of cancers. However, doxorubicin may cause cardiac toxicity, which can cause congestive heart failure in severe cases, and this seriously limits its clinical application. It is believed that doxorubicin promotes the formation of reactive oxygen species, inducing oxidative stress, and at the same time, reduces the content of antioxidant substances in cardiac tissues, causing adverse effects. Toll-like receptors (TLRs) are biomolecules expressed on the surfaces of macrophages, dendritic cells, and epithelial cells that can recognize various types of pathogen-related or damage-related molecular patterns. In recent years, a large number of studies have confirmed that TLRs play important roles in the cardiac toxicity induced by doxorubicin. This review aimed to explore the role of TLRs in the cardiac toxicity induced by doxorubicin and provide possible solutions.

Role of TLR5 in inflammation and tissue damage after intestinal ischemia-reperfusion injury

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury is a life-threatening complication that leads to inflammation and remote organ damage. However, the underlying mechanism is not yet fully understood. Toll-like receptor 5 (TLR5) is highly expressed in mucosa and recognizes flagellin, the main component of the bacterial flagella. Here, we investigated the role of TLR5 in inflammation and tissue damage after intestinal I/R injury using TLR5-deficient mice.

METHODS AND RESULTS

Intestinal levels of TLR5 mRNA and flagellin protein were elevated in wild-type mice subjected to intestinal I/R. Although TLR5 deficiency had no effect on intestinal flagellin levels, it significantly attenuated intestinal injury and inflammatory responses after intestinal I/R. TLR5 deficiency also markedly improved survival in mice after intestinal I/R injury. In wild-type mice, intestinal I/R injury induced remote organ damage, particularly in the lung, which was attenuated by TLR5 deficiency. Furthermore, TLR5 deficiency prevented lung inflammatory responses and vascular permeability after intestinal I/R injury.

CONCLUSION

These findings demonstrate a novel role of TLR5 and provide new insights into the mechanism underlying inflammation and tissue damage after intestinal I/R injury.

miR-222 inhibits cardiac fibrosis in diabetic mice heart via regulating Wnt/β-catenin-mediated endothelium to mesenchymal transition

miR-222 participates in many cardiovascular diseases, but its effect on cardiac remodeling induced by diabetes is unclear. This study evaluated the functional role of miR-222 in cardiac fibrosis in diabetic mice. Streptozotocin (STZ) was used to establish a type 1 diabetic mouse model. After 10 weeks of STZ injection, mice were intravenously injected with Ad-miR-222 to induce the overexpression of miR-222. miR-222 overexpression reduced cardiac fibrosis and improved cardiac function in diabetic mice. Mechanistically, miR-222 inhibited the endothelium to mesenchymal transition (EndMT) in diabetic mouse hearts. Mouse heart fibroblasts and endothelial cells were isolated and cultured with high glucose (HG). An miR-222 mimic did not affect HG-induced fibroblast activation and function but did suppress the HG-induced EndMT process. The antagonism of miR-222 by antagomir inhibited HG-induced EndMT. miR-222 regulated the promoter region of β-catenin, thus negatively regulating the Wnt/β-catenin pathway, which was confirmed by β-catenin siRNA. Taken together, our results indicated that miR-222 inhibited cardiac fibrosis in diabetic mice via negatively regulating Wnt/β-catenin-mediated EndMT.

The Glp-1 Analog Liraglutide Protects Against Angiotensin II and Pressure Overload-Induced Cardiac Hypertrophy via PI3K/Akt1 and AMPKa Signaling

The Glp-1 analog, liraglutide (Lir), has been shown to reduce infarct size and improve cardiac function after myocardial ischemia in rodents with or without diabetes. However, the effect of Lir on angiotensin II (AngII) and pressure overload induced cardiac hypertrophy in nondiabetic mice and the underlying mechanisms are unclear. The aim of this study was to investigate the effect of Lir on cardiac hypertrophy induced by AngII infusion and pressure overload and to explore its possible mechanism. Mice were subjected to AngII as well as thoracic aorta coarctation (TAC) to induce a cardiac hypertrophy model. Mice were daily injected with either liraglutide or saline for 2 weeks after AngII infusion. Mice were also subjected to either liraglutide or saline for 25 days after TAC surgery. Neonatal rat cardiomyocytes and human AC cell lines were stimulated with AngII to induce a cardiomyocytes hypertrophy model. The results indicated Lir significantly inhibited cardiac hypertrophy and fibrosis and improved cardiac function in both the AngII and pressure overload induced model. The in vitro study showed that Lir inhibits AngII induced cell hypertrophy. Mechanistically, Lir directly suppressing the activation of PI3K/Akt1 and stimulated AMPKα signaling pathways in cardiomyocytes, which was confirmed by use of an mTOR activator (MHY1485), overexpression of constitutively active Akt, and the knockdown of AMPKa2 expression. Moreover, the protective effects of Lir were lost in AMPKa2 knockout mice. Taken together, Lir inhibits AngII and pressure overload induced cardiac remodeling via regulating PI3K/Akt1 and AMPKα signaling.

Endothelial to Mesenchymal Transition: Role in Physiology and in the Pathogenesis of Human Diseases

Numerous studies have demonstrated that endothelial cells are capable of undergoing endothelial to mesenchymal transition (EndMT), a newly recognized type of cellular transdifferentiation. EndMT is a complex biological process in which endothelial cells adopt a mesenchymal phenotype displaying typical mesenchymal cell morphology and functions, including the acquisition of cellular motility and contractile properties. Endothelial cells undergoing EndMT lose the expression of endothelial cell-specific proteins such as CD31/platelet-endothelial cell adhesion molecule, von Willebrand factor, and vascular-endothelial cadherin and initiate the expression of mesenchymal cell-specific genes and the production of their encoded proteins including α-smooth muscle actin, extra domain A fibronectin, N-cadherin, vimentin, fibroblast specific protein-1, also known as S100A4 protein, and fibrillar type I and type III collagens. Transforming growth factor-β1 is considered the main EndMT inducer. However, EndMT involves numerous molecular and signaling pathways that are triggered and modulated by multiple and often redundant mechanisms depending on the specific cellular context and on the physiological or pathological status of the cells. EndMT participates in highly important embryonic development processes, as well as in the pathogenesis of numerous genetically determined and acquired human diseases including malignant, vascular, inflammatory, and fibrotic disorders. Despite intensive investigation, many aspects of EndMT remain to be elucidated. The identification of molecules and regulatory pathways involved in EndMT and the discovery of specific EndMT inhibitors should provide novel therapeutic approaches for various human disorders mediated by EndMT.

Innate Immune Signaling and Its Role in Metabolic and Cardiovascular Diseases

The innate immune system is an evolutionarily conserved system that senses and defends against infection and irritation. Innate immune signaling is a complex cascade that quickly recognizes infectious threats through multiple germline-encoded cell surface or cytoplasmic receptors and transmits signals for the deployment of proper countermeasures through adaptors, kinases, and transcription factors, resulting in the production of cytokines. As the first response of the innate immune system to pathogenic signals, inflammatory responses must be rapid and specific to establish a physical barrier against the spread of infection and must subsequently be terminated once the pathogens have been cleared. Long-lasting and low-grade chronic inflammation is a distinguishing feature of type 2 diabetes and cardiovascular diseases, which are currently major public health problems. Cardiometabolic stress-induced inflammatory responses activate innate immune signaling, which directly contributes to the development of cardiometabolic diseases. Additionally, although the innate immune elements are highly conserved in higher-order jawed vertebrates, lower-grade jawless vertebrates lack several transcription factors and inflammatory cytokine genes downstream of the Toll-like receptors (TLRs) and retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) pathways, suggesting that innate immune signaling components may additionally function in an immune-independent way. Notably, recent studies from our group and others have revealed that innate immune signaling can function as a vital regulator of cardiometabolic homeostasis independent of its immune function. Therefore, further investigation of innate immune signaling in cardiometabolic systems may facilitate the discovery of new strategies to manage the initiation and progression of cardiometabolic disorders, leading to better treatments for these diseases. In this review, we summarize the current progress in innate immune signaling studies and the regulatory function of innate immunity in cardiometabolic diseases. Notably, we highlight the immune-independent effects of innate immune signaling components on the development of cardiometabolic disorders.

Cell Type-Specific Roles of NF-κB Linking Inflammation and Thrombosis

The transcription factor NF-κB is a central mediator of inflammation with multiple links to thrombotic processes. In this review, we focus on the role of NF-κB signaling in cell types within the vasculature and the circulation that are involved in thrombo-inflammatory processes. All these cells express NF-κB, which mediates important functions in cellular interactions, cell survival and differentiation, as well as expression of cytokines, chemokines, and coagulation factors. Even platelets, as anucleated cells, contain NF-κB family members and their corresponding signaling molecules, which are involved in platelet activation, as well as secondary feedback circuits. The response of endothelial cells to inflammation and NF-κB activation is characterized by the induction of adhesion molecules promoting binding and transmigration of leukocytes, while simultaneously increasing their thrombogenic potential. Paracrine signaling from endothelial cells activates NF-κB in vascular smooth muscle cells and causes a phenotypic switch to a “synthetic” state associated with a decrease in contractile proteins. Monocytes react to inflammatory situations with enforced expression of tissue factor and after differentiation to macrophages with altered polarization. Neutrophils respond with an extension of their life span—and upon full activation they can expel their DNA thereby forming so-called neutrophil extracellular traps (NETs), which exert antibacterial functions, but also induce a strong coagulatory response. This may cause formation of microthrombi that are important for the immobilization of pathogens, a process designated as immunothrombosis. However, deregulation of the complex cellular links between inflammation and thrombosis by unrestrained NET formation or the loss of the endothelial layer due to mechanical rupture or erosion can result in rapid activation and aggregation of platelets and the manifestation of thrombo-inflammatory diseases. Sepsis is an important example of such a disorder caused by a dysregulated host response to infection finally leading to severe coagulopathies. NF-κB is critically involved in these pathophysiological processes as it induces both inflammatory and thrombotic responses.

The protective effect of high mobility group protein HMGA2 in pressure overload-induced cardiac remodeling

High mobility group protein AT-hook 2 (HMGA2), an architectural transcription factor, has previously been reported to play an essential role in regulating the expression of many genes through architectural remodeling processes. However, the effects of HMGA2 on cardiovascular disease, especial cardiac remodeling, is unclear. This study was aimed at investigating the functional role of HMGA2 in pressure overload-induced cardiac remodeling. Mice that were subjected to aortic banding (AB) for 8 weeks developed myocardial hypertrophy and cardiac dysfunction, which were associated with altered expression of HMGA2. Cardiac-specific expression of the human HMGA2 gene in mice with an adeno-related virus 9 delivery system ameliorated cardiac remodeling and improve cardiac function in response to pressure overload by activating PPARγ/NRF2 signaling. Knockdown of HMGA2 by AAV9-shHMGA2 accelerated cardiac remodeling after 1 weeks of AB surgery. Additionally, knockdown of heart PPARγ largely abolished HMGA2 overexpression-mediated cardioprotection. HMGA2-mediated cardiomyocyte protection was largely abrogated by knocking down NRF2 and inhibiting PPARγ in cardiomyocytes. PPARγ activation was mediated by C/EBPβ, which directly interacted with HMGA2. Knocking down C/EBPβ offset the effects of HMGA2 on PPARγ activation and cardioprotection. These findings show that the overexpression of HMGA2 ameliorates the remodeling response to pressure overload, and they also imply that the upregulation of HMGA2 may become a treatment strategy in cardiac pathologies.

Inhibition of BRD4 attenuates transverse aortic constriction- and TGF-β-induced endothelial-mesenchymal transition and cardiac fibrosis

Cardiac fibrosis (CF), a process characterized by potentiated proliferation of cardiac fibroblasts and excessive secretion and deposition of extracellular matrix (ECM) from the cells, contributes strongly to the pathogenesis of a series of cardiovascular (CV) diseases, including AMI, heart failure and atrial fibrillation. Endothelial-mesenchymal transition (EndMT), one of the sources of transformed cardiac fibroblasts, has been reported as a key factor involved in CF. However, the molecular basis of EndMT has not been thoroughly elucidated to date. At the posttranscriptional level, of the three epigenetic regulators, writer and eraser are reported to be involved in EndMT, but the role of reader in the process is still unknown. In this study, we aimed to explore the role of Bromodomain-containing protein 4 (BRD4), an acetyl-lysine reader protein, in EndMT-induced CF and related mechanisms. We found that BRD4 was upregulated in endothelial cells (ECs) in the pressure-overload mouse heart and that its functional inhibitor JQ1 potently attenuated the TAC-induced CF and preserved cardiac function. In umbilical vein endothelial cells (HUVECs) and mouse aortic endothelial cells (MAECs), bothJQ1 and shRNA-mediated silencing of BRD4 blocked TGF-β-induced EC migration, EndMT and ECM synthesis and preserved the EC sprouting behavior, possibly through the downregulation of a group of transcription factors specific for EndMT (Snail, Twist and Slug), the Smads pathway and TGF-β receptor I. In the absence of TGF-β stimulation, ectopic expression of BRD4 alone could facilitate EndMT, accelerate migration and increase the synthesis of ECM. In vivo, JQ1 also attenuated TAC-induced EndMT and CF, which was consistent with JQ1's intracellular mechanisms of action. Our results showed that BRD4 plays a critical role in EndMT-induced CF and that targeting BRD4 might be a novel therapeutic option for CF.

Hemoglobin targets for the anemia in patients with dialysis-dependent chronic kidney disease: a meta-analysis of randomized, controlled trials

BACKGROUND

Anemia is extremely common among dialysis patients and underlies some of the symptoms associated with reduced kidney function, including fatigue, depression, reduced exercise tolerance, and dyspnea.

OBJECTIVES

A clearer cognition of the prognosistic impact of hemoglobin (Hb) or hematocrit (Hct) target for the outcomes of dialysis patients is urgent. This article aims to establish the suitable hemoglobin in order to provide clinical guidance.

METHODS

MEDLINE, EmBase, the Cochrane Library and other databases were searched with both MeSH terms and keywords to gather randomized controlled trials that assessed all-cause mortality, cardiovascular events, fistula thrombosis, infectious diseases and transfusion among dialysis-dependent patients using erythropoiesis-stimulating agents. The meta-analysis was accomplished via Revman 5.3 version.

FINDINGS

Totally, nine eligible studies were included, with study subjects involving 3228 patients. There was a significantly higher risk of fistula thrombosis without heterogeneity (RR 1.34, 95% CI 1.15-1.55; p < 0.05) in the higher Hb target group than in the lower Hb target group in the fixed effects model. However, no significant difference was found in all-cause mortality in the fixed effects model (RR 1.09, 95% CI 0.93-1.27; p = 0.30), cardiovascular events (RR 0.77, 95% CI 0.31-1.92; p = 0.58), infectious diseases (RR 0.69, 95% CI 0.24-1.96; p = 0.49) and transfusion (RR 0.92, 95% CI 0.42-1.99; p = 0.82) in the random effects model between the higher Hb target group and the lower Hb target group.

DISCUSSION

The results favor lower Hb target. To target lower Hb target when treating dialysis patients with anemia may decrease the risk of fistula thrombosis without increasing the risk of death, cardiovascular events, infectious diseases and transfusion.

Saikosaponin A Protects From Pressure Overload-Induced Cardiac Fibrosis via Inhibiting Fibroblast Activation or Endothelial Cell EndMT

Saikosaponin A (SSA) is a triterpenoid saponin with many pharmacological activities, including anti-inflammatory and antioxidant effects. The effect of SSA on cardiac remodeling and fibrosis, however, remains unclear. Aortic banding surgery was used to establish a mouse cardiac remodeling and fibrosis model. Mice were subjected to an intraperitoneal (i.p.) injection of SSA (5 mg/kg/d or 40 mg/kg/d) 2 weeks after surgery for 28 days. As a result, SSA had limited effect on cardiac hypertrophy but decreased cardiac fibrosis remarkably. Neonatal rat cardiomyocytes were isolated and cultured with SSA (1 and 30 μM). Both 1 and 30 μM SSA reduced atrial natriuretic peptide transcription induced by angiotensin II. Adult mouse cardiac fibroblasts were isolated and cultured with SSA (1, 3, 10 and 30 μM). Only 10 and 30 μM SSA ameliorated transforming growth factor β (TGFβ)-induced fibroblast activation and function. Mouse heart endothelial cells were isolated and stimulated with TGFβ and cocultured with SSA (1, 3, 10 and 30 μM). Only 1 and 3 μM SSA ameliorated TGFβ-induced endothelium-mesenchymal transition (EndMT). Consistently, only the 5 mg/kg/d treatment relieved pressure overload-induced EndMT in vivo. Furthermore, we found that high dosages of SSA (10 and 30 μM) inhibited the TGFβ/smad pathway in fibroblasts, while low dosages of SSA (1 and 3 μM) inhibited the Wnt/β-catenin pathway in endothelial cells. The Smad pathway activator SRI-011381 eliminated SSA (30 μM)-induced protective effects on fibroblasts. The Wnt pathway activator WAY-262611 eliminated SSA (1 μM)-induced protective effects on endothelial cells. In summary, this study indicates the potential application of SSA in the treatment of myocardial fibrosis in cardiac fibrosis, with different target effects associated with different dosages.

Cardiac fibrosis: new insights into the pathogenesis

Cardiac fibrosis is defined as the imbalance of extracellular matrix (ECM) production and degradation, thus contributing to cardiac dysfunction in many cardiac pathophysiologic conditions. This review discusses specific markers and origin of cardiac fibroblasts (CFs), and the underlying mechanism involved in the development of cardiac fibrosis. Currently, there are no CFs-specific molecular markers. Most studies use co-labelling with panels of antibodies that can recognize CFs. Origin of fibroblasts is heterogeneous. After fibrotic stimuli, the levels of myocardial pro-fibrotic growth factors and cytokines are increased. These pro-fibrotic growth factors and cytokines bind to its receptors and then trigger the activation of signaling pathway and transcriptional factors via Smad-dependent or Smad independent-manners. These fibrosis-related transcriptional factors regulate gene expression that are involved in the fibrosis to amplify the fibrotic response. Understanding the mechanisms responsible for initiation, progression, and amplification of cardiac fibrosis are of great clinical significance to find drugs that can prevent the progression of cardiac fibrosis.

LAZ3 protects cardiac remodeling in diabetic cardiomyopathy via regulating miR-21/PPARa signaling

Diabetes contributes to cardiovascular complications and the pathogenesis of cardiac remodeling that can lead to heart failure. We aimed to evaluate the functional role of LAZ3 in diabetic cardiomyopathy (DCM). Streptozotocin (STZ) was used to induce a diabetic mouse model. Three months after induction, the mice were subjected to retro-orbital venous plexus injection of adeno-associated virus 9 (AAV9) that overexpressed LAZ3. Six weeks after the infection, mouse hearts were removed to assess the degree of cardiac remodeling. LAZ3 was down-regulated in the diabetic mouse hearts and high glucose stimulated cardiomyocytes. Knock-down of LAZ3 in cardiomyocytes with LAZ3 siRNA reduced cell viability, increased the inflammatory response and induced oxidative stress and cell apoptosis. Overexpression of LAZ3 by infection with adeno-associated virus (AAV9)-LAZ3 protected against an inflammatory response, oxidative stress and cell apoptosis in both a high glucose stimulated in vitro study and diabetic mouse hearts. We found that LAZ3 increased the activation of PPARa, which increased PGC-1a activation and subsequently augmented NRF2 expression and nuclear translocation. This outcome was confirmed by NRF2 siRNA and a PPARa activator, since NRF2 siRNA abrogated the protective effects of LAZ3 overexpression, while the PPARa activator reversed the deteriorating phenotype of LAZ3 knock-down in both the in vitro and vivo study. Furthermore, LAZ3 decreased miR-21 expression, which resulted in PPARa activation, NRF2 expression and nuclear translocation. In conclusion, LAZ3 protects against cardiac remodeling in DCM by decreasing miR-21, thus regulating PPARa/NRF2 signaling.

Rosmarinic acid attenuates cardiac fibrosis following long-term pressure overload via AMPKα/Smad3 signaling

Agonists of peroxisome proliferator-activated receptor gamma (PPAR-γ) can activate 5' AMP-activated protein kinase alpha (AMPKα) and exert cardioprotective effects. A previous study has demonstrated that rosmarinic acid (RA) can activate PPAR-γ, but its effect on cardiac remodeling remains largely unknown. Our study aimed to investigate the effect of RA on cardiac remodeling and to clarify the underlying mechanism. Mice were subjected to aortic banding to generate pressure overload induced cardiac remodeling and then were orally administered RA (100 mg/kg/day) for 7 weeks beginning 1 week after surgery. The morphological examination, echocardiography, and molecular markers were used to evaluate the effects of RA. To ascertain whether the beneficial effect of RA on cardiac fibrosis was mediated by AMPKα, AMPKα2 knockout mice were used. Neonatal rat cardiomyocytes and fibroblasts were separated and cultured to validate the protective effect of RA in vitro. RA-treated mice exhibited a similar hypertrophic response as mice without RA treatment, but had an attenuated fibrotic response and improved cardiac function after pressure overload. Activated AMPKα was essential for the anti-fibrotic effect of RA via inhibiting the phosphorylation and nuclear translocation of Smad3 in vivo and in vitro, and AMPKα deficiency abolished RA-mediated protective effects. Small interfering RNA against Ppar-γ (siPpar-γ) and GW9662, a specific antagonist of PPAR-γ, abolished RA-mediated AMPKα phosphorylation and alleviation of fibrotic response in vitro. RA attenuated cardiac fibrosis following long-term pressure overload via AMPKα/Smad3 signaling and PPAR-γ was required for the activation of AMPKα. RA might be a promising therapeutic agent against cardiac fibrosis.

The expression of Toll-like receptor 5 in preterm histologic chorioamnionitis

Spontaneous preterm birth is often caused by chorioamnionitis. Toll-like receptors (TLRs) have a role in the response of the innate immune system. The role of TLR5 in chorioamnionitis remains unclear: however, TLR5 was reported to have a significantly stronger effect on the induction of interleukin (IL)-6 when compared with other TLRs in amniotic epithelial cells. The aim of this study was to investigate TLR5 expression in placentas with preterm histologic chorioamnionitis (HCA). The expression levels of TLR5 were evaluated in the amnions, chorions, deciduae and villi with and without HCA using immunohistochemistry. The co-localization of IL-6 or IL-8 with TLR5 was examined by immunofluorescence. The production of IL-6 was examined in primary tissue cultured fetal membranes treated with and without the TLR5 agonist. The protein expression of TLR5 was significantly increased in amnions with HCA (p<0.05) and showed a trend toward an increase in chorions with HCA, whereas no significant difference was detected in the villi and decidua. TLR5 co-localized with IL-6 and IL-8 in amnions and chorions. IL-6 showed a significant increase (p<0.05) with the TLR5 agonist. These results suggest that TLR5 plays a role in the pathogenesis of preterm HCA and IL-6 production.

Mechanisms contributing to cardiac remodelling

Cardiac remodelling is classified as physiological (in response to growth, exercise and pregnancy) or pathological (in response to inflammation, ischaemia, ischaemia/reperfusion (I/R) injury, biomechanical stress, excess neurohormonal activation and excess afterload). Physiological remodelling of the heart is characterized by a fine-tuned and orchestrated process of beneficial adaptations. Pathological cardiac remodelling is the process of structural and functional changes in the left ventricle (LV) in response to internal or external cardiovascular damage or influence by pathogenic risk factors, and is a precursor of clinical heart failure (HF). Pathological remodelling is associated with fibrosis, inflammation and cellular dysfunction (e.g. abnormal cardiomyocyte/non-cardiomyocyte interactions, oxidative stress, endoplasmic reticulum (ER) stress, autophagy alterations, impairment of metabolism and signalling pathways), leading to HF. This review describes the key molecular and cellular responses involved in pathological cardiac remodelling.

NOD2 promotes endothelial-to-mesenchymal transition of glomerular endothelial cells via MEK/ERK signaling pathway in diabetic nephropathy

Endothelial-to-mesenchymal transition (EndMT) of glomerular vascular endothelial cells (GEnCs) is now considered to play a critical role in diabetic nephropathy (DN). NOD2 is newly discovered to be closely related to DN renal injury. However, the relationship between NOD2 and EndMT of GEnCs has never been reported. In the present study, we found that NOD2 over-expression was positively correlated with the severity of DN injury in human renal biopsy samples. Immunohistochemical staining of DN renal slices showed gradual absence of endothelial character and gain of mesenchymal character, both of which were associated with NOD2 over-expression. In high glucose stimulated GEnCs, NOD2 was increased. What's more, over-expression and activation of NOD2 could both promote EndMT of GEnCs. On the other hand, silencing of NOD2 markedly attenuated EndMT induced by high glucose. Mechanically, we further found that MEK/ERK signaling pathway was involved in NOD2-regulated EndMT. Collectively, our results indicate that NOD2 has a regulatory role in EndMT via activation of MEK/ERK in high glucose-treated GEnCs. Targeting this pathway is a promising strategy for intervention of DN endothelial dysfunction.

DNMT1 and HDAC2 Cooperate to Facilitate Aberrant Promoter Methylation in Inorganic Phosphate-Induced Endothelial-Mesenchymal Transition

While phosphorus in the form of inorganic or organic phosphate is critically involved in most cellular functions, high plasma levels of inorganic phosphate levels have emerged as independent risk factor for cardiac fibrosis, cardiovascular morbidity and decreased life-expectancy. While the link of high phosphate and cardiovascular disease is commonly explained by direct cellular effects of phospho-regulatory hormones, we here explored the possibility of inorganic phosphate directly eliciting biological responses in cells. We demonstrate that human coronary endothelial cells (HCAEC) undergo an endothelial-mesenchymal transition (EndMT) when exposed to high phosphate. We further demonstrate that such EndMT is initiated by recruitment of aberrantly phosphorylated DNMT1 to the RASAL1 CpG island promoter by HDAC2, causing aberrant promoter methylation and transcriptional suppression, ultimately leading to increased Ras-GTP activity and activation of common EndMT regulators Twist and Snail. Our studies provide a novel aspect for known adverse effects of high phosphate levels, as eukaryotic cells are commonly believed to have lost phosphate-sensing mechanisms of prokaryotes during evolution, rendering them insensitive to extracellular inorganic orthophosphate. In addition, our studies provide novel insights into the mechanisms underlying specific targeting of select genes in context of fibrogenesis.