Toll-Like Receptor 4 Inhibition Improves Oxidative Stress and Mitochondrial Health in Isoproterenol-Induced Cardiac Hypertrophy in Rats

Clinical implications of septic cardiomyopathy: A narrative review

Sepsis is caused by the body's dysregulated response to infection, which can lead to multiorgan injury and death. Patients with sepsis may develop acute cardiac dysfunction, termed septic cardiomyopathy, which is a global but reversible dysfunction of both sides of the heart. This narrative review discusses the mechanistic changes in the heart during septic cardiomyopathy, its diagnosis, existing treatment options regarding severity and course, and emerging treatment approaches. Although no standardized definition for septic cardiomyopathy exists, it is described as a reversible myocardial dysfunction that typically resolves within 7 to 10 days. Septic cardiomyopathy is often diagnosed based on electrocardiography, cardiac magnetic resonance imaging, biomarkers, and direct invasive and noninvasive measures of cardiac output. Presently, the treatment of septic cardiomyopathy is similar to that of sepsis, primarily focusing on acute interventions. Treatments for cardiomyopathy often include angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and diuretics. However, because of profound hypotension in sepsis, many cardiomyopathy treatments are contraindicated in patients with septic cardiomyopathy. Substantial efforts have been made to study the pathophysiological mechanisms and diagnostic options; however, the lack of a uniform definition for septic cardiomyopathy is challenging for physicians when considering treatments. Another challenge for physicians is that the treatment for septic cardiomyopathy has only focused on acute intervention, whereas the treatment for other cardiomyopathies has been provided on a long-term basis. A better understanding of the underlying mechanisms of septic cardiomyopathy may contribute to the development of a unified definition of the condition and novel treatment options.

TLR4-A Pertinent Player in Radiation-Induced Heart Disease?

The heart is one of the organs that is sensitive to developing delayed adverse effects of ionizing radiation (IR) exposure. Radiation-induced heart disease (RIHD) occurs in cancer patients and cancer survivors, as a side effect of radiation therapy of the chest, with manifestation several years post-radiotherapy. Moreover, the continued threat of nuclear bombs or terrorist attacks puts deployed military service members at risk of exposure to total or partial body irradiation. Individuals who survive acute injury from IR will experience delayed adverse effects that include fibrosis and chronic dysfunction of organ systems such as the heart within months to years after radiation exposure. Toll-like receptor 4 (TLR4) is an innate immune receptor that is implicated in several cardiovascular diseases. Studies in preclinical models have established the role of TLR4 as a driver of inflammation and associated cardiac fibrosis and dysfunction using transgenic models. This review explores the relevance of the TLR4 signaling pathway in radiation-induced inflammation and oxidative stress in acute as well as late effects on the heart tissue and the potential for the development of TLR4 inhibitors as a therapeutic target to treat or alleviate RIHD.

Cardiomyocyte-specific deletion of TLR4 attenuates angiotensin II-induced hypertension and cardiac remodeling

Toll-like receptor 4 (TLR4) is an integral factor in the initiation of the innate immune response and plays an important role in cardiovascular diseases such as hypertension and myocardial infarction. Previous studies from our lab demonstrated that central TLR4 blockade reduced cardiac TLR4 expression, attenuated hypertension, and improved cardiac function. However, the contribution of cardiac specific TLR4 to the development of hypertension and cardiac remodeling is unknown. Therefore, we hypothesized that cardiomyocyte specific knockdown of TLR4 would have beneficial effects on hypertension, cardiac hypertrophy, and remodeling. To test this hypothesis, cardiomyocyte-specific TLR4 knockdown (cTLR4KO) mice were generated by crossing floxed TLR4 mice with Myh6-Cre mice, and subjected to angiotensin II (Ang II, 1 µg/kg/min or vehicle for 14 days) hypertension model. Blood pressure measurements using radio telemetry revealed no differences in baseline mean arterial pressure between control littermates and cTLR4KO mice (103 ± 2 vs. 105 ± 3 mmHg, p > 0.05). Ang II-induced hypertension (132 ± 2 vs. 151 ± 3 mmHg, p < 0.01) was attenuated and cardiac hypertrophy (heart/body weight; 4.7 vs. 5.8 mg/g, p < 0.01) was prevented in cTLR4KO mice when compared with control mice. In addition, the level of myocardial fibrosis was significantly reduced, and the cardiac function was improved in cTLR4KO mice infused with Ang II. Furthermore, cardiac inflammation, as evidenced by elevated gene expression of TNF, IL-6, and MCP-1 in the left ventricle, was attenuated in cTLR4KO mice infused with Ang II. Together, this data revealed a protective role for cardiomyocyte-specific deletion of TLR4 against Ang II-induced hypertension and cardiac dysfunction through inhibition of proinflammatory cytokines.

Beneficial effect of TLR4 blockade by a specific aptamer antagonist after acute myocardial infarction

Experimental evidence indicates that the control of the inflammatory response after myocardial infarction is a key strategy to reduce cardiac injury. Cellular damage after blood flow restoration in the heart promotes sterile inflammation through the release of molecules that activate pattern recognition receptors, among which TLR4 is the most prominent. Transient regulation of TLR4 activity has been considered one of the potential therapeutic interventions with greater projection towards the clinic. In this regard, the characterization of an aptamer (4FT) that acts as a selective antagonist for human TLR4 has been investigated in isolated macrophages from different species and in a rat model of cardiac ischemia/reperfusion (I/R). The binding kinetics and biological responses of murine and human macrophages treated with 4FT show great affinity and significant inhibition of TLR4 signaling including the NF-κB pathway and the LPS-dependent increase in the plasma membrane currents (Kv currents). In the rat model of I/R, administration of 4FT following reoxygenation shows amelioration of cardiac injury function and markers, a process that is significantly enhanced when the second dose of 4FT is administered 24 h after reperfusion of the heart. Parameters such as cardiac injury biomarkers, infiltration of circulating inflammatory cells, and the expression of genes associated with the inflammatory onset are significantly reduced. In addition, the expression of anti-inflammatory genes, such as IL-10, and pro-resolution molecules, such as resolvin D1 are enhanced after 4FT administration. These results indicate that targeting TLR4 with 4FT offers new therapeutic opportunities to prevent cardiac dysfunction after infarction.

Toll-like receptor-2 in cardiomyocytes and macrophages mediates isoproterenol-induced cardiac inflammation and remodeling

Heart failure (HF) is the leading cause of morbidity and mortality worldwide. Activation of the innate immune system initiates an inflammatory response during cardiac remodeling induced by isoproterenol (ISO). Here, we investigated whether Toll-like receptor-2 (TLR2) mediates ISO-induced inflammation, hypertrophy, and fibrosis. TLR2 was found to be increased in the heart tissues of mouse with HF under ISO challenge. Further, cardiomyocytes and macrophages were identified as the main cellular sources of the increased TLR2 levels in the model under ISO stimulation. The effect of TLR2 deficiency on ISO-induced cardiac remodeling was determined using TLR2 knockout mice and bone marrow transplantation models. In vitro studies involving ISO-treated cultured cardiomyocytes and macrophages showed that TLR2 knockdown significantly decreased ISO-induced cell inflammation and remodeling via MAPKs/NF-κB signaling. Mechanistically, ISO significantly increased the TLR2-MyD88 interaction in the above cells in a TLR1-dependent manner. Finally, DAMPs, such as HSP70 and fibronectin 1 (FN1), were found to be released from the cells under ISO stimulation, which further activated TLR1/2-Myd88 signaling and subsequently activated pro-inflammatory cytokine expression and cardiac remodeling. In summary, our findings suggest that TLR2 may be a target for the alleviation of chronic adrenergic stimulation-associated HF. In addition, this paper points out the possibility of TLR2 as a new target for heart failure under ISO stimulation.

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.

Sexually dimorphic effects of SARM1 deletion on cardiac NAD+ metabolism and function

Nicotinamide adenine dinucleotide (NAD+) decline is repeatedly observed in heart disease and its risk factors. Although strategies promoting NAD+ synthesis to elevate NAD+ levels improve cardiac function, whether inhibition of NAD+ consumption can be therapeutic is less investigated. In this study, we examined the role of sterile-α and TIR motif containing 1 (SARM1) NAD+ hydrolase in mouse hearts, using global SARM1-knockout mice (KO). Cardiac function was assessed by echocardiography in male and female KO mice and wild-type (WT) controls. Hearts were collected for biochemical, histological, and molecular analyses. We found that the cardiac NAD+ pool was elevated in female KO mice, but only trended to increase in male KO mice. SARM1 deletion induced changes to a greater number of NAD+ metabolism transcripts in male mice than in female mice. Body weights, cardiac systolic and diastolic function, and geometry showed no changes in both male and female KO mice compared with WT counterparts. Male KO mice showed a small, but significant, elevation in cardiac collagen levels compared with WT counterparts, but no difference in collagen levels was detected in female mice. The increased collagen levels were associated with greater number of altered profibrotic and senescence-associated inflammatory genes in male KO mice, but not in female KO mice.NEW & NOTEWORTHY We examined the effects of SARM1 deletion on NAD+ pool, transcripts of NAD+ metabolism, and fibrotic pathway for the first time in mouse hearts. We observed the sexually dimorphic effects of SARM1 deletion. How these sex-dependent effects influence the outcomes of SARM1 deficiency in male and female mice in responses to cardiac stresses warrant further investigation. The elevation of cardiac NAD+ pool by SARM1 deletion provides evidence that targeting SARM1 may reverse disease-related NAD+ decline.

Anti-Diabetic Therapy, Heart Failure and Oxidative Stress: An Update

Diabetes mellitus (DM) and heart failure (HF) are two chronic disorders that affect millions worldwide. Hyperglycemia can induce excessive generation of highly reactive free radicals that promote oxidative stress and further exacerbate diabetes progression and its complications. Vascular dysfunction and damage to cellular proteins, membrane lipids and nucleic acids can stem from overproduction and/or insufficient removal of free radicals. The aim of this article is to review the literature regarding the use of antidiabetic drugs and their role in glycemic control in patients with heart failure and oxidative stress. Metformin exerts a minor benefit to these patients. Thiazolidinediones are not recommended in diabetic patients, as they increase the risk of HF. There is a lack of robust evidence on the use of meglinitides and acarbose. Insulin and dipeptidyl peptidase-4 (DPP-4) inhibitors may have a neutral cardiovascular effect on diabetic patients. The majority of current research focuses on sodium glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists. SGLT2 inhibitors induce positive cardiovascular effects in diabetic patients, leading to a reduction in cardiovascular mortality and HF hospitalization. GLP-1 receptor agonists may also be used in HF patients, but in the case of chronic kidney disease, SLGT2 inhibitors should be preferred.

Venetoclax Induces Cardiotoxicity through Modulation of Oxidative-Stress-Mediated Cardiac Inflammation and Apoptosis via NF-κB and BCL-2 Pathway

Cardiovascular damage induced by anticancer therapy has become the main health problem after tumor elimination. Venetoclax (VTX) is a promising novel agent that has been proven to have a high efficacy in multiple hematological diseases, especially acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL). Considering its mechanism of action, the possibility that VTX may cause cardiotoxicity cannot be ruled out. Therefore, this study was designed to investigate the toxic effect of VTX on the heart. Male Sprague-Dawley rats were randomly divided into three groups: control, low-dose VTX (50 mg/kg via oral gavage), and high-dose VTX (100 mg/kg via oral gavage). After 21 days, blood and tissue samples were collected for histopathological, biochemical, gene, and protein analyses. We demonstrated that VTX treatment resulted in cardiac damages as evidenced by major changes in histopathology and markedly elevated cardiac enzymes and hypertrophic genes markers. Moreover, we observed a drastic increase in oxidative stress, as well as inflammatory and apoptotic markers, with a remarkable decline in the levels of Bcl-2. To the best of our knowledge, this study is the first to report the cardiotoxic effect of VTX. Further experiments and future studies are strongly needed to comprehensively understand the cardiotoxic effect of VTX.

Circ-TLR4 promotes cardiac hypertrophy through recruiting FUS to stabilize TLR4 mRNA

BACKGROUND

Cardiac hypertrophy is an adaptive and compensatory mechanism preserving cardiac output during detrimental stimuli. Circular RNAs (circRNAs) have been illustrated to exert important implications in the pathogenesis of multiple cardiovascular diseases (CVD) including demonstrated cardiac hypertrophy. Toll-like receptor 4 (TLR4) has been previously reported to be a crucial regulator in inflammatory response and cardiac hypertrophy. However, the role of circular isoforms derived from TLR4 in cardiac hypertrophy remains unclear.

METHODS

Expression of circ-TLR4 and TLR4 in cardiomyocytes was detected by RT-qPCR. The indicators of cardiac hypertrophy responses, including cell surface area, atrial natriuretic factor (ANF), B-type natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC) were measured by immunofluorescence staining and western blot. RIP assay was used to validate the interaction between circ-TLR4 and TLR4.

RESULTS

Circ-TLR4 and TLR4 was up-regulated in cellular models of cardiac hypertrophy. Circ-TLR4 knockdown attenuated angiotensin II (Ang II)-induced hypertrophy responses in cardiomyocytes. Moreover, circ-TLR4 positively regulated TLR4 expression through recruiting FUS to stabilize TLR4 mRNA. Furthermore, TLR4 overexpression rescued the cardiac responses mediated by circ-TLR4 silencing.

CONCLUSION

Circ-TLR4 promotes cardiac hypertrophy through recruiting FUS to stabilize TLR4 mRNA.

Modified citrus pectin prevents isoproterenol-induced cardiac hypertrophy associated with p38 signalling and TLR4/JAK/STAT3 pathway

Modified citrus pectin (MCP) is a specific inhibitor of galectin-3 (Gal-3) that is regarded as a new biomarker of cardiac hypertrophy, but its effect is unclear. The aim of this study is to investigate the role and mechanism of MCP in isoproterenol (ISO)-induced cardiac hypertrophy. Rats were injected with ISO to induce cardiac hypertrophy and treated with MCP. Cardiac function was detected by ECG and echocardiography. Pathomorphological changes were evaluated by the haematoxylin eosin (H&E) and wheat germ agglutinin (WGA) staining. The hypertrophy-related genes for atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and β-myosin heavy chain (β-MHC), and the associated signal molecules were analysed by qRT-PCR and western blotting. The results show that MCP prevented cardiac hypertrophy and ameliorated cardiac dysfunction and structural disorder. MCP also decreased the levels of ANP, BNP, and β-MHC and inhibited the expression of Gal-3 and Toll-like receptor 4 (TLR4). Additionally, MCP blocked the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3), but it promoted the phosphorylation of p38. Thus, MCP prevented ISO-induced cardiac hypertrophy by activating p38 signalling and inhibiting the Gal-3/TLR4/JAK2/STAT3 pathway.

Catecholamine-induced cardiotoxicity: A critical element in the pathophysiology of stroke-induced heart injury

Cerebrovascular diseases such as ischemic stroke, brain hemorrhage, and subarachnoid hemorrhage provoke cardiac complications such as heart failure, neurogenic stress-related cardiomyopathy and Takotsubo cardiomyopathy. With regards to the pathophysiology of stroke-induced heart injury, several mechanisms have been postulated to contribute to this complex interaction between brain and heart, including damage from gut dysbiosis, immune and systematic inflammatory responses, microvesicle- and microRNA-mediated vascular injury and damage from a surge of catecholamines. All these cerebrovascular diseases may trigger pronounced catecholamine surges through diverse ways, including stimulation of hypothalamic-pituitary adrenal axis, dysregulation of autonomic system, and secretion of adrenocorticotropic hormone. Primary catecholamines involved in this pathophysiological response include norepinephrine (NE) and epinephrine. Both are important neurotransmitters that connect the nervous system with the heart, leading to cardiac damage via myocardial ischemia, calcium (Ca²⁺) overload, oxidative stress, and mitochondrial dysfunction. In this review, we will aim to summarize the molecular mechanisms behind catecholamine-induced cardiotoxicity including Ca²⁺ overload, oxidative stress, apoptosis, cardiac hypertrophy, interstitial fibrosis, and inflammation. In addition, we will focus on how synchronization among these pathways evokes cardiotoxicity.

Fetuin-A excess expression amplifies lipid induced apoptosis and β-cell damage

Fetuin-A, a hepato-adipokine, is associated with lipid-mediated islet inflammation and inflicts β-cell death but the underlying mechanisms are still unclear. In an earlier report, it was shown that fetuin-A promotes lipid-induced insulin resistance by acting as an endogenous ligand of toll like receptor 4. Recently, we have also reported that β-cells secrete fetuin-A on stimulation by palmitate causing β-cell dysfunction. The aim of this study was twofold: (a) screening the role of fetuin-A in survival of murine β-cells, and (b) to validate the effect of fetuin-A release and lipid induced apoptosis in mouse insulinoma cell line MIN6. Excess of lipid and fetuin-A in circulation induced significant deterioration of islet histoarchitecture and impeded insulin secretion by 2.7 ± 0.5-folds in 20 weeks high fat diet mice. Administration of fetuin-A (0.7 mg/g) along with 4 weeks of HFD produced similar results as 20 weeks of high fat feeding. Treating high doses of palmitate alone (0.50 mM) as well as in combination with fetuin-A (100 µg/ml) for 24 h inflicted apoptosis in MIN6 through the mitochondrial pathway. Knockdown of fetuin-A gene partially inhibited palmitate inflicted apoptosis in MIN6 by 1.83 ± 0.25 times, however, fetuin-A when added in the medium caused re-emergence of apoptosis. Notably, apoptosis induced by palmitate conditioned media from MIN6, 3T3L1, and HepG2, was partially inhibited in fetuin-A KD MIN6. These results confirmed the critical role of circulatory fetuin-A and β-cell secreted fetuin-A in β-cell dysfunction and apoptosis under hyperlipidemic conditions.

Long non-coding RNAs in cardiac hypertrophy

Cardiac hypertrophy (CH) is generally considered adaptive responses that may occur after myocardial infarction, pressure overload, volume overload, inflammatory heart muscle disease, or idiopathic dilated cardiomyopathy, whereas long-term stimulation eventually leads to heart failure (HF). However, the current molecular mechanisms involved in CH are unclear. Recently, increasing evidences reveal that long non-coding RNAs (lncRNAs) play vital roles in CH. Different lncRNAs can promote or inhibit the pathological process of CH by different mechanisms, while the regulation of lncRNAs expression can improve CH. Thus, CH-related lncRNAs may become a novel field of research on CH.

Oxidative stress in cardiac hypertrophy: From molecular mechanisms to novel therapeutic targets

When faced with increased workload the heart undergoes remodelling, where it increases its muscle mass in an attempt to preserve normal function. This is referred to as cardiac hypertrophy and if sustained, can lead to impaired contractile function. Experimental evidence supports oxidative stress as a critical inducer of both genetic and acquired forms of cardiac hypertrophy, a finding which is reinforced by elevated levels of circulating oxidative stress markers in patients with cardiac hypertrophy. These observations formed the basis for using antioxidants as a therapeutic means to attenuate cardiac hypertrophy and improve clinical outcomes. However, the use of antioxidant therapies in the clinical setting has been associated with inconsistent results, despite antioxidants having been shown to exert protection in several animal models of cardiac hypertrophy. This has forced us to revaluate the mechanisms, both upstream and downstream of oxidative stress, where recent studies demonstrate that apart from conventional mediators of oxidative stress, metabolic disturbances, mitochondrial dysfunction and inflammation as well as dysregulated autophagy and protein homeostasis contribute to disease pathophysiology through mechanisms involving oxidative stress. Importantly, novel therapeutic targets have been identified to counteract oxidative stress and attenuate cardiac hypertrophy but more interestingly, the repurposing of drugs commonly used to treat metabolic disorders, hypertension, peripheral vascular disease, sleep disorders and arthritis have also been shown to improve cardiac function through suppression of oxidative stress. Here, we review the latest literature on these novel mechanisms and intervention strategies with the aim of better understanding the complexities of oxidative stress for more precise targeted therapeutic approaches to prevent cardiac hypertrophy.

Nutraceutical, Dietary, and Lifestyle Options for Prevention and Treatment of Ventricular Hypertrophy and Heart Failure

Although well documented drug therapies are available for the management of ventricular hypertrophy (VH) and heart failure (HF), most patients nonetheless experience a downhill course, and further therapeutic measures are needed. Nutraceutical, dietary, and lifestyle measures may have particular merit in this regard, as they are currently available, relatively safe and inexpensive, and can lend themselves to primary prevention as well. A consideration of the pathogenic mechanisms underlying the VH/HF syndrome suggests that measures which control oxidative and endoplasmic reticulum (ER) stress, that support effective nitric oxide and hydrogen sulfide bioactivity, that prevent a reduction in cardiomyocyte pH, and that boost the production of protective hormones, such as fibroblast growth factor 21 (FGF21), while suppressing fibroblast growth factor 23 (FGF23) and marinobufagenin, may have utility for preventing and controlling this syndrome. Agents considered in this essay include phycocyanobilin, N-acetylcysteine, lipoic acid, ferulic acid, zinc, selenium, ubiquinol, astaxanthin, melatonin, tauroursodeoxycholic acid, berberine, citrulline, high-dose folate, cocoa flavanols, hawthorn extract, dietary nitrate, high-dose biotin, soy isoflavones, taurine, carnitine, magnesium orotate, EPA-rich fish oil, glycine, and copper. The potential advantages of whole-food plant-based diets, moderation in salt intake, avoidance of phosphate additives, and regular exercise training and sauna sessions are also discussed. There should be considerable scope for the development of functional foods and supplements which make it more convenient and affordable for patients to consume complementary combinations of the agents discussed here. Research Strategy: Key word searching of PubMed was employed to locate the research papers whose findings are cited in this essay.

Key Player in Cardiac Hypertrophy, Emphasizing the Role of Toll-Like Receptor 4

Toll-like receptor 4 (TLR4), a key pattern recognition receptor, initiates the innate immune response and leads to chronic and acute inflammation. In the past decades, accumulating evidence has implicated TLR4-mediated inflammatory response in regulation of myocardium hypertrophic remodeling, indicating that regulation of the TLR4 signaling pathway may be an effective strategy for managing cardiac hypertrophy's pathophysiology. Given TLR4's significance, it is imperative to review the molecular mechanisms and roles underlying TLR4 signaling in cardiac hypertrophy. Here, we comprehensively review the current knowledge of TLR4-mediated inflammatory response and its interaction ligands and co-receptors, as well as activation of various intracellular signaling. We also describe the associated roles in promoting immune cell infiltration and inflammatory mediator secretion, that ultimately cause cardiac hypertrophy. Finally, we provide examples of some of the most promising drugs and new technologies that have the potential to attenuate TLR4-mediated inflammatory response and prevent or reverse the ominous cardiac hypertrophy outcomes.

Activation of toll like receptor 4 (TLR4) promotes cardiomyocyte apoptosis through SIRT2 dependent p53 deacetylation

Cardiomyocyte inflammation followed by apoptosis and fibrosis is an important mediator for development and progression of heart failure. Activation of toll-like receptor 4 (TLR4), an important regulator of inflammation, causes the progression of cardiac hypertrophy and injury. However, the precise mechanism of TLR4-mediated adverse cardiac outcomes is still elusive. The present study was designed to find the role of TLR4 in cardiac fibrosis and apoptosis, and molecular mechanism thereof. Rats were treated with TLR4 agonist (LPS 12.5 μg/kg/day) through osmotic pump for 14 days. To simulate the condition in vitro, H9c2 cells were treated with LPS (1 μg/ml). Similarly, H9c2 cells were transfected with TLR4 and SIRT2 c-DNA clone for overexpression. Myocardial oxidative stress, inflammation, fibrosis and mitochondrial parameters were evaluated both in vitro and in vivo. Cardiac inflammation after LPS treatment was confirmed by increased TNF-α and IL-6 expression in rat heart. There was a marked increase in oxidative stress as observed by increased TBARS and decreased endogenous antioxidants (GSH and catalase), along with mitochondrial dysfunction as measured by mitochondrial complex activity in LPS-treated rat hearts. Histopathological examination showed the presence of cardiac fibrosis after LPS treatment. Protein expression of nuclear p53 and cleaved caspase-7/caspase-9 was significantly increased in LPS treated heart. Similar to in vivo study, nuclear translocation of p53, mitochondrial dysfunction and cellular apoptosis were observed in H9c2 cells treated with LPS. Our data also indicate that decreased expression of SIRT2 was associated with increased acetylation of p53 after LPS treatment. In conclusion, TLR4 activation in rats promotes cardiac inflammation, mitochondrial dysfunction, apoptosis and fibrosis. p53 and caspase 7/caspase 9 were found to play an important role in TLR4-mediated apoptosis. Our data suggest that, reducing TLR4 mediated fibrosis and apoptosis could be a novel approach in the treatment of heart failure, keeping in the view the major role played by TLR4 in cardiac inflammation.

Arbutin Attenuates Isoproterenol-Induced Cardiac Hypertrophy by Inhibiting TLR-4/NF-κB Pathway in Mice

Arbutin is a glycoside reported for its anti-oxidant, anti-inflammatory and anti-tumor properties. However, the cardioprotective effect of Arbutin is not well established. The study aims to understand the effect of arbutin on isoproterenol (ISO)-induced cardiac hypertrophy in mice. The animals were pretreated with Arbutin for a week and ISO was administered for 10 days and then sacrificed. Cardiac injury markers such as creatinine kinase and lactate dehydrogenase concentrations were measured in the serum. The mRNA expression of cardiac hypertrophy markers namely atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were measured using qRT-PCR. The levels of pro-inflammatory cytokines TNF-α and IL-6 were quantified by ELISA in isolated tissues and serum. Other tissue anti-oxidant parameters such as GST, GSH, SOD and TBARS were also measured. TUNEL assay was performed to detect apoptosis. Histology studies were performed using H & E and Masson trichome staining. Immunoblot analysis was used to quantify the protein expression of TLR-4 and NF-κB. ISO-alone-treated group showed significant increase in CK-MB, LDH along with increase in hypertrophic markers ANP and BNP, TNF-α and IL-6 levels in serum and tissues and increased cardiomyocyte apoptosis. Anti-oxidant parameters were significantly decreased and TLR-4 and NF-κB protein expression was found to be upregulated in comparison to the control group. Pretreatment with Arbutin-exhibited significant inhibition of TLR-4/NF-κB pathway with decreased levels of pro-inflammatory cytokines and enhanced myocardial anti-oxidant status. Our study demonstrated that pretreatment with Arbutin exhibits marked protective effects on ISO-induced cardiac hypertrophy in mice. Thus, Arbutin may be used as potential pharmacological interventions in the management of cardiac hypertrophy.

G6PD, bond by miR-24, regulates mitochondrial dysfunction and oxidative stress in phenylephrine-induced hypertrophic cardiomyocytes

AIMS

Pathological cardiac hypertrophy (CH) is one of the main risk factors for heart failure and cardiac death. Mitochondrial dysfunction and oxidative stress often occur in hypertrophic cardiomyocytes. It was recently proposed that deficiency or decreased activity of glucose-6-phosphate dehydrogenase (G6PD) may be related to the development of CH. This study aimed to investigate the expression of G6PD in CH and its regulatory role in mitochondrial dysfunction and oxidative stress of CH cells.

MAIN METHODS

Phenylephrine (PE) was used to create an in vitro model of CH. Using RT-qPCR and western blotting, the expression levels of target mRNAs and proteins were measured. ELISA assays and commercial kits based on spectrophotometry or colorimetry were used to measure mitochondrial function and oxidative stress. TargetScan and luciferase reporter gene assays were utilized for combination prediction and validation. CCK-8 and TUNEL kit were used to determine cell viability and apoptosis.

KEY FINDINGS

The results showed that G6PD overexpression attenuated the decreases of mitochondrial respiration, ATP, ATP synthetase and mitochondrial membrane potential induced by PE, as well as the increases of LDH release and apoptosis. Besides, PE elevated ROS activity, NO and MDA contents, and reduced SOD, CAT levels and cell viability. These effects were hindered by G6PD overexpression. MiR-24 was found to directly bind to G6PD at the motif of CUGAGCC and regulated its expression, furtherly, influenced the G6PD-mediated mitochondrial dysfunction and oxidative stress of CH cells.

SIGNIFICANCE

Generally, our study demonstrated that miR-24/G6PD regulates mitochondrial dysfunction and oxidative stress in CH cells, representing a new sight for CH therapy.

Mitochondrial Dysfunction in Diabetic Cardiomyopathy: The Possible Therapeutic Roles of Phenolic Acids

As the powerhouse of the cells, mitochondria play a very important role in ensuring that cells continue to function. Mitochondrial dysfunction is one of the main factors contributing to the development of cardiomyopathy in diabetes mellitus. In early development of diabetic cardiomyopathy (DCM), patients present with myocardial fibrosis, dysfunctional remodeling and diastolic dysfunction, which later develop into systolic dysfunction and eventually heart failure. Cardiac mitochondrial dysfunction has been implicated in the development and progression of DCM. Thus, it is important to develop novel therapeutics in order to prevent the progression of DCM, especially by targeting mitochondrial dysfunction. To date, a number of studies have reported the potential of phenolic acids in exerting the cardioprotective effect by combating mitochondrial dysfunction, implicating its potential to be adopted in DCM therapies. Therefore, the aim of this review is to provide a concise overview of mitochondrial dysfunction in the development of DCM and the potential role of phenolic acids in combating cardiac mitochondrial dysfunction. Such information can be used for future development of phenolic acids as means of treating DCM by alleviating the cardiac mitochondrial dysfunction.

Plants as Sources of Anti-Inflammatory Agents

Plants represent the main source of molecules for the development of new drugs, which intensifies the interest of transnational industries in searching for substances obtained from plant sources, especially since the vast majority of species have not yet been studied chemically or biologically, particularly concerning anti-inflammatory action. Anti-inflammatory drugs can interfere in the pathophysiological process of inflammation, to minimize tissue damage and provide greater comfort to the patient. Therefore, it is important to note that due to the existence of a large number of species available for research, the successful development of new naturally occurring anti-inflammatory drugs depends mainly on a multidisciplinary effort to find new molecules. Although many review articles have been published in this regard, the majority presented the subject from a limited regional perspective. Thus, the current article presents highlights from the published literature on plants as sources of anti-inflammatory agents.

Putative anti-inflammatory, antioxidant, and anti-apoptotic roles of the natural tissue guardian methyl palmitate against isoproterenol-induced myocardial injury in rats

Background

Myocardial injury is considered as a worldwide main cause of morbidity and mortality. The present study aimed to investigate the probable cardioprotective activity of the naturally occurring endogenous fatty acid ester methyl palmitate (MP) against isoproterenol (ISO)-induced myocardial injury in rats and the possible underlying molecular mechanisms. The study was carried out in two consecutive sets of experiments; the first set screened the cardioprotective dose of MP in ISO-intoxicated rats. In the second set, forty male Sprague Dawley rats received either MP (150 mg/kg, p.o) three times/week for 2 weeks and/or 2 consecutive doses of ISO separated by 24 h (85 mg/kg, s.c) on the 13th and 14th days. Different cardiotoxicity and oxidative stress markers were assessed. Furthermore, endothelial nitric oxide synthase (eNOS) levels were determined. For detection of apoptosis, Bax, Bcl-2, and caspase 3 were estimated. To assess inflammation, toll-like receptor 4 (TLR-4) and tumor necrosis factor-alpha (TNF-α) were measured using ELISA. Meanwhile, nuclear factor kappa B (NF-kB) and cyclooxygenase-2 (COX-2) were detected immunohistochemically.

Results

Pretreatment with MP significantly ameliorated the cardiotoxicity and oxidative stress markers. It also markedly elevated eNOS content, decreased apoptotic marker expression, and mitigated TLR-4 activation and other inflammatory markers. Electrocardiography and histopathological examination also confirmed the cardioprotective effect of MP.

Conclusion

The findings of this study indicated that MP possesses a potent cardioprotective activity against ISO-induced myocardial injury through its significant antioxidant, anti-apoptotic, anti-inflammatory, and vasodilatation activities.

Graphical abstract

Liraglutide attenuates gefitinib-induced cardiotoxicity and promotes cardioprotection through the regulation of MAPK/NF-κB signaling pathways

Gefitinib is an effective treatment for patients with locally advanced non-small cell lung cancer. However, it is associated with cardiotoxicity that can limit its clinical use. Liraglutide, a glucagon-like peptide 1 receptor agonist, showed potent cardioprotective effects with the mechanism is yet to be elucidated. Therefore, this study aimed to determine the efficiency of liraglutide in protecting the heart from damage induced by gefitinib. Adult male Wistar rats were randomly divided into control group, liraglutide group (200 µg/kg by i.p. injection), gefitinib group (30 mg/kg orally) and liraglutide plus gefitinib group. After 28 days, blood and tissue samples were collected for histopathological, biochemical, gene and protein analysis. We demonstrated that gefitinib treatment (30 mg/kg) resulted in cardiac damage as evidenced by histopathological studies. Furthermore, serum Creatine kinase-MB (CK-MB), N-terminal pro B-type natriuretic peptide (NT-proBNP) and cardiac Troponin-I (cTnI) were markedly elevated in gefitinib group. Pretreatment with liraglutide (200 µg/kg), however, restored the elevation in serum markers and diminished gefitinib-induced cardiac damage. Moreover, liraglutide improved the gene and protein levels of anti-oxidant (superoxide dismutase) and decreased the oxidative stress marker (NF-κB). Mechanistically, liraglutide offered protection through upregulation of the survival kinases (ERK1/2 and Akt) and downregulation of stress-activated kinases (JNK and P38). In this study, we provide evidence that liraglutide protects the heart from gefitinib-induced cardiac damage through its anti-oxidant property and through the activation of survival kinases.

Left ventricular hypertrophy is associated with overexpression of HSP60, TLR2, and TLR4 in the myocardium

Left ventricular hypertrophy is a common adaptive response to increased cardiac workload. Cardiomyocytes growth and increase in contractile force are conditioned by sufficient energy production, which implies appropriate mitochondrial function. The 60 kDa heat shock protein (HSP60) is a chaperone essential for mitochondrial proteostasis, but when translocates from mitochondria, it can also act as a potent inflammatory mediator binding to toll-like receptors (TLRs). In this study, we aimed to compare the expression pattern of HSP60, TLR2, and TLR4 in hypertrophic vs non-hypertrophic, normal human myocardium. We further examined whether HSP60 in situ binds to TLRs in hypertrophic myocardial tissue. In addition, expression of activated downstream targets of TLR 2/4 pathways was also evaluated.For this purpose, immunohistochemical expression analyses were performed on myocardial tissue samples obtained during the autopsy of human subjects in which left ventricular hypertrophy was the only cardiopathological finding and had died from sudden cardiac death, as well as from the subjects without any cardiac pathology, that died by unnatural death (accident or suicide). Double immunofluorescence was used to examine HSP60 translocation, while proximity ligation assay (PLA) was performed to assess HSP60 and TLRs interactions.Hypertrophic myocardium showed significantly higher expression of HSP60, TLR2, and TLR4 compared to normal myocardium. Furthermore, in hypertrophic cardiomyocytes, we found membrane translocation of HSP60 and signs of HSP60/TLR interactions.Conclusion: The obtained data point to an important supportive role of HSP60 in adaptive cardiomyocytes growth, while concomitant induction of TLR2 and TLR4 candidates HSP60-TLRs interactions as an early events during pathogenesis of secondary complications consequently to the left ventricular hypertrophy.

Musa balbisiana Fruit Rich in Polyphenols Attenuates Isoproterenol-Induced Cardiac Hypertrophy in Rats via Inhibition of Inflammation and Oxidative Stress

Musa balbisiana Colla (Family: Musaceae), commonly known as banana and native to India and other parts of Asia, is very rich in nutritional value and has strong antioxidant potential. In the present study, we have developed Musa balbisiana (MB) fruit pulp powder and evaluated its cardioprotective effect in cardiac hypertrophy, which is often associated with inflammation and oxidative stress. An ultra-high-pressure liquid chromatography-mass spectrometer (UPLC-MS/MS) has been used for the detection and systematic characterization of the phenolic compounds present in Musa balbisiana fruit pulp. The cardioprotective effect of MB was evaluated in a rat model of isoproterenol- (ISO-) induced cardiac hypertrophy by subcutaneous administration of isoproterenol (5 mg/kg⁻¹/day⁻¹), delivered through an alzet minipump for 14 days. Oral administration of MB fruit pulp powder (200 mg/kg/day) significantly (p < 0.001) decreased heart weight/tail length ratio and cardiac hypertrophy markers like ANP, BNP, β-MHC, and collagen-1 gene expression. MB also attenuated ISO-induced cardiac inflammation and oxidative stress. The in vivo data were further confirmed in vitro in H9c2 cells where the antihypertrophic and anti-inflammatory effect of the aqueous extract of MB was observed in the presence of ISO and lipopolysaccharide (LPS), respectively. This study strongly suggests that supplementation of dried Musa balbisiana fruit powder can be useful for the prevention of cardiac hypertrophy via the inhibition of inflammation and oxidative stress.

TLR (Toll-Like Receptor) 4 Antagonism Prevents Left Ventricular Hypertrophy and Dysfunction Caused by Neonatal Hyperoxia Exposure in Rats

Preterm birth is associated with proinflammatory conditions and alterations in adult cardiac shape and function. Neonatal exposure to high oxygen, a rat model of prematurity-related conditions, leads to cardiac remodeling, fibrosis, and dysfunction. TLR (Toll-like receptor) 4 signaling is a critical link between oxidative stress, inflammation, and the pathogenesis of cardiovascular diseases. The current study sought to investigate the role of TLR4 signaling in neonatal oxygen-induced cardiomyopathy. Male Sprague-Dawley pups were kept in 80% oxygen or room air from day 3 to 10 of life and treated with TLR4 antagonist lipopolysaccharide from the photosynthetic bacterium Rhodobacter sphaeroides(LPS-RS) or saline. Echocardiography was performed at 4, 7, and 12 weeks. At 12 weeks, intraarterial blood pressure was measured before euthanization for histological and biochemical analyses. At day 10, cardiac TLR4, Il (interleukin) 18, and Il1β expression were increased in oxygen-exposed compared with room air controls. At 4 weeks, compared with room air-saline, saline-, but not LPS-RS treated-, oxygen-exposed animals, exhibited increased left ventricle mass index, reduced ejection fraction, and cardiac output index. Findings were similar at 7 and 12 weeks. LPS-RS did not influence echocardiography in 12 weeks room air animals. Systolic blood pressure was higher in saline- but not LPS-RS treated-oxygen-exposed animals compared with room air-saline and -LPS-RS controls. LPS-RS prevented cardiac fibrosis and cardiomyocytes hypertrophy, the increased TLR4, Myd88, and Il18 gene expression, TRIF expression, and CD68+ macrophages infiltration associated with neonatal oxygen exposure, without impact in room air rats. This study indicates that neonatal exposure to high oxygen programs TLR4 activation, which contributes to cardiac remodeling and dysfunction.

Sp1-induced LncRNA CTBP1-AS2 is a novel regulator in cardiomyocyte hypertrophy by interacting with FUS to stabilize TLR4

Cardiomyocyte hypertrophy is a heart response adapting to increasing cardiac load. Prolonged cardiomyocyte hypertrophy indicates a higher risk of heart failure or even cardiac death. Long noncoding RNAs have been largely reported to modulate human diseases. CTPB1-AS2 is a newly discovered lncRNA reported as an oncogene in papillary thyroid cancer, but its function in cardiomyocyte hypertrophy has never been probed. Toll-like receptor 4 (TLR4) is recognized to play important roles in cardiomyocyte hypertrophy. The present study aimed to investigate the role of CTBP1-AS2 in cardiomyocyte hypertrophy. First, we discovered the low expression of CTBP1-AS2 in normal heart tissues in GETx database. Then, we established cardiomyocyte hypertrophy models on mice and cardiomyocytes through transverse aortic constriction surgery and Ang II treatment. We revealed the up-regulation of CTBP1-AS2 and TLR4 in cardiomyocyte hypertrophy models. Also, we confirmed the positive correlation between CTBP1-AS2 and TLR4 expressions in cardiomyocyte hypertrophy tissues. Loss-of-function assays confirmed that inhibiting CTBP1-AS2 attenuated the Ang II-induced cardiomyocyte hypertrophy. Mechanism research showed that CTBP1-AS2 stabilized TLR4 mRNA by recruiting FUS. Rescue assays certified that CTBP1-AS2 regulated cardiomyocyte hypertrophy through TLR4. Finally, we found Sp1 as an upstream activator for CTBP1-AS2 expression. In conclusion, our study uncovered CTBP1-AS2 as a novel regulator of cardiomyocyte hypertrophy through regulating TLR4, providing a new potential treatment target for cardiomyocyte hypertrophy.

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

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

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

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

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

Effects of Levosimendan on Inflammation and Oxidative Stress Pathways in a Lipopolysaccharide-Stimulated Human Endothelial Cell Model

Levosimendan is a myocardial Ca²⁺ sensitizer and opener of ATP-dependent potassium channels with inotropic, vasodilating, and cardioprotective properties. It was originally developed for the treatment of acute decompensated heart failure, but its complex mechanism of action means that it could also play a role in organ protection in response to infection. Using an in vitro approach, we explored whether levosimendan administration influenced cell responses to lipopolysaccharide (LPS). Primary human umbilical vein endothelial cells were stimulated with 1 µg/ml LPS from Escherichia coli (E. coli). Cells were treated with levosimendan at 0, 0.1, 1, or 10 µM 3 hr later. Samples were taken 24 hr after treatment to measure cell necrosis, apoptosis, pro-inflammatory mediators (interleukin 6 [IL-6] and toll-like receptor 4 [TLR4]), and oxidative stress (total reactive oxygen species/reactive nitrogen species [ROS/RNS]). Levosimendan at 1 and 10 µM protected against LPS-induced endothelial cell death and reduced TLR4 expression (p < .05). All doses reduced levels of IL-6 and ROS/RNS (p < .05). Findings suggest that levosimendan may exert protective effects against endothelial cell death in this model via attenuation of inflammation and oxidative stress pathways. Future studies might explore the potential beneficial role of levosimendan in modulating molecular mechanisms triggered by infections.

Unveiling the Interplay between the TLR4/MD2 Complex and HSP70 in the Human Cardiovascular System: A Computational Approach

While precise mechanisms underlying cardiovascular diseases (CVDs) are still not fully understood, previous studies suggest that the innate immune system, through Toll-like receptor 4 (TLR4), plays a crucial part in the pathways leading to these diseases, mainly because of its interplay with endogenous molecules. The Heat-shock protein 70 family (HSP70-70kDa) is of particular interest in cardiovascular tissues as it may have dual effects when interacting with TLR4 pathways. Although the hypothesis of the HSP70 family members acting as TLR4 ligands is becoming widely accepted, to date no co-crystal structure of this complex is available and it is still unknown whether this process requires the co-adaptor MD2. In this study, we aimed at investigating the interplay between the TLR4/MD2 complex and HSP70 family members in the human cardiovascular system through transcriptomic data analysis and at proposing a putative interaction model between these proteins. We report compelling evidence of correlated expression levels between TLR4 and MD2 with HSP70 cognate family members, especially in heart tissue. In our molecular docking simulations, we found that HSP70 in the ATP-bound state presents a better docking score towards the TLR4/MD2 complex compared to the ADP-bound state (-22.60 vs. -10.29 kcal/mol, respectively). Additionally, we show via a proximity ligation assay for HSP70 and TLR4, that cells stimulated with ATP have higher formation of fluorescent spots and that MD2 might be required for the complexation of these proteins. The insights provided by our computational approach are potential scaffolds for future in vivo studies investigating the interplay between the TLR4/MD2 complex and HSP70 family members in the cardiovascular system.

Vitamin D Deficiency in Rats Causes Cardiac Dysfunction by Inducing Myocardial Insulin Resistance

SCOPE

Cause-effect relationship between vitamin D deficiency and cardiometabolic abnormalities remains undefined. The aim is to investigate the role of vitamin D deficiency in cardiac failure, through possible involvement in myocardial insulin signaling.

METHODS AND RESULTS

Male SD rats (n = 6) are fed a normal diet (Con), vitamin D-deficient diet [Con(-)], or high-fat, high fructose diet (HFHFrD) for 20 weeks. Cardiac hypertrophy and fetal gene program are confirmed in Con(-) group. Cardiac dysfunction is assessed by echocardiography. Elevated renin, TGF-β and collagen-1α mRNAs, p-ERK1/2, and perivascular fibrosis indicate cardiac remodeling in Con(-) group. Increased serum insulin, triglycerides, and blood pressure, and decreased glucose tolerance and HDL cholesterol are observed in Con(-) rats. Decreased p-Akt/Akt, GLUT4, SOD2, and catalase, and increased NF-κB, TNF-α, and IL-6 are observed in Con(-) hearts. In H9c2 cells, calcitriol attenuates palmitate-induced insulin resistance. VDR-silenced H9c2 cells show reduced Akt phosphorylation, GLUT4 translocation, and 2-NBDG uptake. Findings in Con(-) and HFHFrD groups are comparable.

CONCLUSION

Vitamin D deficiency in rats mimic high-fat-, high-fructose-induced metabolic syndrome and cardiac dysfunction. This study demonstrates that vitamin D deficiency is an independent risk factor for heart failure, at least in part, through induction of myocardial insulin resistance.

TanshinoneIIA Alleviates Inflammatory Response and Directs Macrophage Polarization in Lipopolysaccharide-Stimulated RAW264.7 Cells

TanshinoneIIA (TanIIA) has been demonstrated to possess numerous biological effects. However, the specific effect of TanIIA on macrophage polarization has not been reported. In this study, it was revealed that TanIIA might play a pivotal role in macrophage polarization. As our results indicated, cell morphology was changed in RAW264.7 cells which were treated with LPS or LPS/TanIIA (0.1 μM, 1 μM, 10 μM). Subsequently, pro-inflammatory cytokine TNF-α and anti-inflammatory cytokine IL-10 were measured by ELISA kits. Furthermore, TanIIA enhanced the expression of M2 macrophage markers (Arg1 and FIZZ1) and decreased the expression of markers associated with M1 macrophage polarization (iNOS and IL-1β). Increased expression of CD206 was also detected by flow cytometry in TanIIA-treated groups. Mechanistically, it was revealed that TanIIA modulated macrophage polarization by ameliorating mitochondrial function and regulating TLR4-HMGB1/CEBP-β pathway. In addition, increased expression of miR-155 was observed in RAW264.7 cells incubated with LPS and were effectively inhibited by TanIIA. Taken together, it was suggested that TanIIA inhibits inflammatory response and promotes macrophage polarization toward an M2 phenotype, which provides new evidence for the anti-inflammation activity of TanIIA.

Down-regulation of miR-200c attenuates AngII-induced cardiac hypertrophy via targeting the MLCK-mediated pathway

Background

MicroRNAs (miRNAs) have been shown to commonly contribute to cardiac hypertrophy (CH). The aim of this study was to test the hypothesis that miR‐200c plays an important role in the progression of CH by targeting myosin light chain kinase (MLCK/MYLK).

Methods and results

Cardiac hypertrophy was induced by aortic banding (AB) in rats. Cellular hypertrophy in neonatal rat cardiomyocytes (NCMs) was induced by AngII treatment. Echocardiography, histology and molecular measurements were used to assess the results of the experiments. The levels of apoptosis and reactive oxygen species (ROS) were also measured. Quantitative real‐time PCR (qRT‐PCR) and Western blotting were used to measure mRNA and protein levels respectively. The present results showed that miR‐200c expression was increased in response to CH both in vivo and in vitro. The down‐regulation of miRNA‐200c by a specific inhibitor markedly ameliorated CH resulting from AngII treatment, and the mRNA levels of atrial natriuretic peptide, brain natriuretic peptide and β‐myosin heavy chain were simultaneously decreased. Notably, minimal apoptosis and ROS accumulation were identified in AngII‐induced hypertrophic cardiomyocytes. Conversely, the up‐regulation of miR‐200c using specific mimics reversed these effects. Mechanistic investigations demonstrated that the MLCK gene is a direct target of miR‐200c; an increase in miR‐200c levels led to a decrease in the expression of MLCK and its downstream effector, p‐MLC2, while miR‐200c inhibition increased the expression of these proteins. Furthermore, inhibiting MLCK impaired the anti‐hypertrophic effects contributions produced by the knockdown of miR‐200c.

Conclusion

Our studies suggest that miR‐200c may serve as a potential therapeutic target that could delay hypertrophy. We have also uncovered a relationship between miR‐200c and MLCK, identifying MLCK as a direct mediator of miR‐200c.

Protective Effect of Hesperidin Against Sepsis-Induced Lung Injury by Inducing the Heat-Stable Protein 70 (Hsp70)/Toll-Like Receptor 4 (TLR4)/ Myeloid Differentiation Primary Response 88 (MyD88) Pathway

Background

Sepsis-induced lung injury is associated with high mortality. The present investigation evaluated the protective effect of hesperidin against sepsis-induced lung injury and also postulates the possible mechanism of its action.

Material/Methods

Lung injury was induced by sepsis in all animals, in which sepsis was produced by cecal ligation and puncture (CLP). Animals were treated with hesperidin 10 and 20 mg/kg i.v. 30 min after the surgery. Oxygenation index and lung injury score were determined and levels of pro-inflammatory mediators and markers of oxidative stress were also estimated in the lung tissues. Moreover, expression of caspase-3, B-cell lymphoma (Bcl-2), Toll-like receptor 4 (TLR4), heat-stable protein 70 (Hsp70) and myeloid differentiation primary response 88 (MyD88) protein was estimated by Western blot assay and immunofluorescence assay.

Results

Hesperidin attenuated the partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio and lung injury score in CLP-induced lung injury mice. There was a significant (p<0.01) decrease in the level of pro-inflammatory mediators in the lung tissue of CLP-induced lung injury mice. Moreover, markers of oxidative stress were attenuated in the hesperidin-treated group. Treatment with hesperidin attenuated the expression of caspase-3, Bcl-2, TLR4, Hsp70, and MyD88 protein in the lung tissue of CLP-induced lung injury mice.

Conclusions

Hesperidin protects against lung injury by attenuating the Hsp70/TLR4/MyD88 pathway in CLP-induced lung injury mice.

Subterminal hydroxyeicosatetraenoic acids: Crucial lipid mediators in normal physiology and disease states

Cytochrome P450 (P450) enzymes are superfamily of monooxygenases that hold the utmost diversity of substrate structures and catalytic reaction forms amongst all other enzymes. P450 enzymes metabolize arachidonic acid (AA) to a wide array of biologically active lipid mediators. P450-mediated AA metabolites have a significant role in normal physiological and pathophysiological conditions, hence they could be promising therapeutic targets in different disease states. P450 monooxygenases mediate the (ω-n)-hydroxylation reactions, which involve the introduction of a hydroxyl group to the carbon skeleton of AA, forming subterminal hydroxyeicosatetraenoic acids (HETEs). In the current review, we specified different P450 isozymes implicated in the formation of subterminal HETEs in varied tissues. In addition, we focused on the role of subterminal HETEs namely 19-HETE, 16-HETE, 17-HETE and 18-HETE in different organs, importantly the kidneys, heart, liver and brain. Furthermore, we highlighted their role in hypertension, acute coronary syndrome, diabetic retinopathy, non-alcoholic fatty liver disease, ischemic stroke as well as inflammatory diseases. Since each member of subterminal HETEs exist as R and S enantiomer, we addressed the issue of stereoselectivity related to the formation and differential effects of these enantiomers. In conclusion, elucidation of different roles of subterminal HETEs in normal and disease states leads to identification of novel therapeutic targets and development of new therapeutic modalities in different disease states.

Mechanistic insights to the cardioprotective effect of blueberry nutraceutical extract in isoprenaline-induced cardiac hypertrophy

BACKGROUND

Lowbush blueberry extract (Vaccinium angustifolium) is abundant with polyphenols (such as chlorogenic acid) with high antioxidant profile. It has received great interest due to its protective role in many disorders such as heart diseases and neurological disorders.

HYPOTHESIS

We hypothesized that blueberry leaf extract might have a protective effect against cardiac hypertrophy via suppressing oxidative stress, inflammation and fibrosis.

METHOD

Blueberry leaf nutraceutical extract was administered orally to male albino rats at three different doses (25, 50 and 100 mg/kg/day of the extract, equivalent to 3.4, 6.8 and 13.6 mg of chlorogenic acid, respectively) once daily for 28 consecutive days against a dose of isoprenaline (ISO) (5 mg/kg) for 14 days.

RESULTS

The results indicated that isoprenaline induced significant myocardial damage, characterized by conduction abnormalities, increased heart-to-body weight ratio, increased serum CKMB, AST, c-TnI and LDH. Pretreatment with blueberry extract at a dose of 50 mg/kg/day (equivalent to 6.8 mg chlorogenic acid) protected against ISO-induced ECG changes, leakage of cardiac enzymes and histopathological changes. Also, ISO caused significant glutathione depletion, lipid peroxidation and reduction in activities of antioxidant catalase enzyme. These effects were prevented by pretreatment with blueberry extract. Additionally, ISO elicited inflammatory effects by increasing the expression of NF-κB, COX-2, TNF-α and IL-6 while pretreatment with blueberry extract significantly inhibited these inflammatory responses. Furthermore, ISO induced fibrosis by increasing the level of TGF-β while pretreatment with blueberry extract significantly reduced it.

CONCLUSION

These findings indicate that blueberry leaf extract possessed a potent protective effect against ISO-induced cardiac hypertrophy via suppressing oxidative stress, inflammation and fibrosis.

Pitavastatin ameliorates myocardial damage by preventing inflammation and collagen deposition via reduced free radical generation in isoproterenol-induced cardiomyopathy

Pitavastatin inhibits 3 hydroxy 3 methyl glutaryl coenzyme A (HMGCoA) reductase enzyme, preventing cholesterol synthesis along with elevating high density apolipoprotein A1 (Apo-A1). The present study was designed to evaluate cardioprotective potential of pitavastatin at 1 mg/kg/day and 3 mg/kg/day dose for 14 days in low dose isoproterenol (ISO) (5 mg/kg/day for 7 consecutive days) induced myocardial damage. ISO administration induced significant reduction in endogenous antioxidant enzymes like reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and raised thiobarbituric acid reactive substances (TBARS) indicating activated lipid peroxidation. Along with this, a significant increase in level of cardiac injury biomarkers vie, creatine kinase (CK-MB), lactate dehydrogenase (LDH), aspartate amino transferase (AST), tumor necrosis factor (TNF-α) and transforming growth factor (TGF-β) as well as brain natriuretic peptide (BNP). Histological examination also revealed marked myocardial tissue damage in ISO treated rats. However, pretreatment with pitavastatin (3 mg/kg/day) significantly maintained nearly normal levels of cardiac biomarkers and oxidant antioxidant status as well as lipid peroxidation in ISO induced MI rats. Cardiac histological assessment and infarct size assessment also showed marked reduction in myocardial architecture alteration including infarct size as well as collagen deposition by pitavastatin that strongly supported biochemical findings. These observations strongly corroborate that pitavastatin prevents myocardial damages via up regulation of endogenous oxidants along with its hypocholesterolemic activity.

Immuno-Spin Trapping-Based Detection of Oxidative Modifications in Cardiomyocytes and Coronary Endothelium in the Progression of Heart Failure in Tgαq*44 Mice

Recent studies suggest both beneficial and detrimental role of increased reactive oxygen species and oxidative stress in heart failure (HF). However, it is not clear at which stage oxidative stress and oxidative modifications occur in the endothelium in relation to cardiomyocytes in non-ischemic HF. Furthermore, most methods used to date to study oxidative stress are either non-specific or require tissue homogenization. In this study, we used immuno-spin trapping (IST) technique with fluorescent microscopy-based detection of DMPO nitrone adducts to localize and quantify oxidative modifications of the hearts from Tgαq*44 mice; a murine model of HF driven by cardiomyocyte-specific overexpression of Gαq* protein. Tgαq*44 mice and age-matched FVB controls at early, transition, and late stages of HF progression were injected with DMPO in vivo and analyzed ex vivo for DMPO nitrone adducts signals. Progressive oxidative modifications in cardiomyocytes, as evidenced by the elevation of DMPO nitrone adducts, were detected in hearts from 10- to 16-month-old, but not in 8-month-old Tgαq*44 mice, as compared with age-matched FVB mice. The DMPO nitrone adducts were detected in left and right ventricle, septum, and papillary muscle. Surprisingly, significant elevation of DMPO nitrone adducts was also present in the coronary endothelium both in large arteries and in microcirculation simultaneously, as in cardiomyocytes, starting from 10-month-old Tgαq*44 mice. On the other hand, superoxide production in heart homogenates was elevated already in 6-month-old Tgαq*44 mice and progressively increased to high levels in 14-month-old Tgαq*44 mice, while the enzymatic activity of catalase, glutathione reductase, and glutathione peroxidase was all elevated as early as in 4-month-old Tgαq*44 mice and stayed at a similar level in 14-month-old Tgαq*44. In summary, this study demonstrates that IST represents a unique method that allows to quantify oxidative modifications in cardiomyocytes and coronary endothelium in the heart. In Tgαq*44 mice with slowly developing HF, driven by cardiomyocyte-specific overexpression of Gαq* protein, an increase in superoxide production, despite compensatory activation of antioxidative mechanisms, results in the development of oxidative modifications not only in cardiomyocytes but also in coronary endothelium, at the transition phase of HF, before the end-stage disease.

Ablation of toll-like receptor 4 attenuates aging-induced myocardial remodeling and contractile dysfunction through NCoRI-HDAC1-mediated regulation of autophagy

Aging is usually accompanied with overt structural and functional changes as well as suppressed autophagy in the heart although the precise regulatory mechanisms are somewhat unknown. Here we evaluated the role of the innate proinflammatory mediator toll-like receptor 4 (TLR4) in cardiac aging and the underlying mechanism with a focus on autophagy. Cardiac geometry and function were monitored in young or old wild-type (WT) and TLR4 knockout (TLR4^-/-) mice using echocardiography, IonOptix® edge-detection and fura-2 techniques. Levels of autophagy and mitophagy, nuclear receptor corepressor 1 (NCoR1) and histone deacetylase I (HDAC1) were examined using western blot. Transmission electronic microscopy (TEM) was employed to monitor myocardial ultrastructure. Our results revealed that TLR4 ablation alleviated advanced aging (24 months)-induced changes in myocardial remodeling (increased heart weight, chamber size, cardiomyocyte cross-sectional area), contractile function and intracellular Ca²⁺ handling as well as autophagy and mitophagy [Beclin-1, Atg5, LC3B, PTEN-induced putative kinase 1 (PINK1), Parkin and p62]. Aging downregulated levels of NCoR1 and HDAC1 as well as their interaction, the effects were significantly attenuated or negated by TLR4 ablation. Advanced aging disturbed myocardial ultrastructure as evidenced by loss of myofilament alignment and swollen mitochondria, which was obliterated by TLR4 ablation. Moreover, aging suppressed autophagy (GFP-LC3B puncta) in neonatal mouse cardiomyocytes, the effect of which was negated by the TLR4 inhibitor CLI-095. Inhibition of HDCA1 using apicidin cancelled off CLI095-induced beneficial response of GFP-LC3B puncta against aging. Our data collectively indicate a role for TLR4-mediated autophagy in cardiac remodeling and contractile dysfunction in aging through a HDAC1-NCoR1-dependent mechanism.

RETRACTED: LncRNA myocardial infarction-associated transcript (MIAT) contributed to cardiac hypertrophy by regulating TLR4 via miR-93

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief after concerns were raised about the article on PubPeer (https://pubpeer.com/publications/88E67BAC524E92069B2AA3474D2BB8?utm_source=Chrome&utm_medium=BrowserExtension&utm_campaign=Chrome). In addition the editor found more issues in some Western Blot figures. 1. Bands of figure 1C ANF 30min , 60min, 12h, 24h are identical to those in Fig 4C ANF control, AngII, AngII+si-NC and AngII+si-MAT 2. Beta-actin bands of Fig 1C are identical to those in Fig 4C, but blots represent different experimental conditions/samples. 3. Bands in Fig 6 D AngII and AngII+mir-NC show similarities with these of AngII+mir-93 and AngII+mir93+vector (band shapes and irregularities appear identical) After several attempts to reach out to the corresponding author, no response was provided. The manipulation of images casts doubts on all the data, and accordingly also the conclusions based on that data, in this publication. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

AMPK and cardiac remodelling

Cardiac remodelling is generally accepted as a critical process in the progression of heart failure. Myocyte hypertrophy, inflammatory responses and cardiac fibrosis are the main pathological changes associated with cardiac remodelling. AMP-activated protein kinase (AMPK) is known as an energy sensor and a regulator of cardiac metabolism under normal and ischaemic conditions. Additionally, AMPK has been shown to play roles in cardiac remodelling extending well beyond metabolic regulation. In this review, we discuss the currently defined roles of AMPK in cardiac remodelling and summarize the effects of AMPK on cardiac hypertrophy, inflammatory responses and fibrosis and the molecular mechanisms underlying these effects. In addition, we discuss some pharmacological activators of AMPK that are promising treatments for cardiac remodelling.