OSMR deficiency aggravates pressure overload-induced cardiac hypertrophy by modulating macrophages and OSM/LIFR/STAT3 signalling.

BACKGROUND: Oncostatin M (OSM) is a secreted cytokine of the interleukin (IL)-6 family that induces biological effects by activating functional receptor complexes of the common signal transducing component glycoprotein 130 (gp130) and OSM receptor ß (OSMR) or leukaemia inhibitory factor receptor (LIFR), which are mainly involved in chronic inflammatory and cardiovascular diseases. The effect and underlying mechanism of OSM/OSMR/LIFR on the development of cardiac hypertrophy remains unclear. METHODS AND RESULTS: OSMR-knockout (OSMR-KO) mice were subjected to aortic banding (AB) surgery to establish a model of pressure overload-induced cardiac hypertrophy. Echocardiographic, histological, biochemical and immunological analyses of the myocardium and the adoptive transfer of bone marrow-derived macrophages (BMDMs) were conducted for in vivo studies. BMDMs were isolated and stimulated with lipopolysaccharide (LPS) for the in vitro study. OSMR deficiency aggravated cardiac hypertrophy, fibrotic remodelling and cardiac dysfunction after AB surgery in mice. Mechanistically, the loss of OSMR activated OSM/LIFR/STAT3 signalling and promoted a proresolving macrophage phenotype that exacerbated inflammation and impaired cardiac repair during remodelling. In addition, adoptive transfer of OSMR-KO BMDMs to WT mice after AB surgery resulted in a consistent hypertrophic phenotype. Moreover, knockdown of LIFR in myocardial tissue with Ad-shLIFR ameliorated the effects of OSMR deletion on the phenotype and STAT3 activation. CONCLUSIONS: OSMR deficiency aggravated pressure overload-induced cardiac hypertrophy by modulating macrophages and OSM/LIFR/STAT3 signalling, which provided evidence that OSMR might be an attractive target for treating pathological cardiac hypertrophy and heart failure.

The Physical and Psychological Effects of Personal Protective Equipment on Health Care Workers in Wuhan, China: A Cross-Sectional Survey Study.

INTRODUCTION: The purpose of this study was to rapidly quantify the safety measures regarding donning and doffing personal protective equipment, complaints of discomfort caused by wearing personal protective equipment, and the psychological perceptions of health care workers in hospitals in Wuhan, China, responding to the outbreak. METHODS: A cross-sectional online questionnaire design was used Data were collected from March 14, 2020, to March 16, 2020, in Wuhan, China. Descriptive statistics and χ2 analyses testing were used. RESULTS: Standard nosocomial infection training could significantly decrease the occurrence of infection (3.6% vs 13.0%, χ2 = 4.47, P < 0.05). Discomfort can be classified into 7 categories. Female sex (66.0% vs 50.5%, χ2 = 6.37), occupation (62.7% vs 30.8%, χ2 = 5.33), working at designated hospitals (44.8% vs 26.7%, χ2 = 5.17) or in intensive care units (70.4% vs 57.9%, χ2 = 3.88), and working in personal protective equipment for > 4 hours (62.2% vs 39.2%, χ2 = 9.17) led to more complaints about physical discomfort or increased occurrence of pressure sores (all P < 0.05). Psychologically, health care workers at designated hospitals (60.0% vs 42.1%, χ2 = 4.97) or intensive care units (55.9% vs 41.5%, χ2 = 4.40) (all P < 0.05) expressed different rates of pride. DISCUSSION: Active training on infection and protective equipment could reduce the infection risk. Working for long hours increased the occurrence of discomfort and skin erosion. Reducing the working hours and having adequate protective products and proper psychological interventions may be beneficial to relieve discomfort.

T-bet deficiency attenuates cardiac remodelling in rats.

Previous studies have suggested the involvement of CD4 + T lymphocytes in cardiac remodelling. T-bet can direct Th1 lineage commitment. This study aimed to investigate the functional significance of T-bet in cardiac remodelling induced by pressure overload using T-bet global knockout rats. Increased T-bet levels were observed in rodent and human hypertrophied hearts. T-bet deficiency resulted in a less severe hypertrophic phenotype in rats. CD4 + T-lymphocyte reconstitution in T-bet-/- rats resulted in aggravated cardiac remodelling. T-cell homing molecule expression and cytokine secretion were altered in T-bet-deficient rat hearts. Administration of exogenous interferon-γ (IFN-γ) offset T-bet deficiency-mediated cardioprotection. Cardiomyocytes cultured in T-bet-/- CD4 + T-cell-conditioned media showed a reduced hypertrophic response after hypertrophic stimuli, which was abolished by an IFN-γ-neutralizing antibody. Taken together, our findings show that T-bet deficiency attenuates pressure overload-induced cardiac remodelling in rats. Specifically, targeting T-bet in T cells may be of great importance for the treatment of pathological cardiac remodelling and heart failure.

Evodiamine attenuates TGF-ß1-induced fibroblast activation and endothelial to mesenchymal transition.

The aim of this study is to investigate the effect of evodiamine on fibroblast activation in cardiac fibroblasts and endothelial to mesenchymal transition (EndMT) in human umbilical vein endothelial cells (HUVECs). Neonatal rat cardiac fibroblasts were stimulated with transforming growth factor beta 1 (TGF-ß1) to induce fibroblast activation. After co-cultured with evodiamine (5, 10 µM), the proliferation and pro-fibrotic proteins expression of cardiac fibroblasts were evaluated. HUVECs were also stimulated with TGF-ß1 to induce EndMT and treated with evodiamine (5, 10 µM) at the same time. The EndMT response in the HUVECs was evaluated as well as the capacity of the transitioned endothelial cells migrating to surrounding tissue. As a result, Evodiamine-blunted TGF-ß1 induced activation of cardiac fibroblast into myofibroblast as assessed by the decreased expressions of α-SMA. Furthermore, evodiamine reduced the increased protein expression of fibrosis markers in neonatal and adult rat cardiac fibroblasts induced by TGF-ß1. HUVECs stimulated with TGF-ß1 exhibited lower expression levels of CD31, CD34, and higher levels of α-SMA, vimentin than the control cells. This phenotype was eliminated in the HUVECs treated with both 5 and 10 µM evodiamine. Evodiamine significantly reduced the increase in migration ability that occurred in response to TGF-ß1 in HUVECs. In addition, the activation of Smad2, Smad3, ERK1/2, and Akt, and the nuclear translocation of Smad4 in both cardiac fibroblasts and HUVEC were blocked by evodiamine treatment. Thus, evodiamine could prevent cardiac fibroblasts from activation into myofibroblast and protect HUVEC against EndMT. These effects may be mediated by inhibition of the TGFß pathway in both cardiac fibroblasts and HUVECs.

Evodiamine Prevents Isoproterenol-Induced Cardiac Fibrosis by Regulating Endothelial-to-Mesenchymal Transition.

Evodiamine, a major component of Evodia rutaecarpa, can protect the myocardium against injury induced by atherosclerosis and ischemia-reperfusion. However, the effect of evodiamine against cardiac fibrosis remains unclear. This study aims to investigate the possible effect and mechanism involved in the function of evodiamine on isoproterenol-induced cardiac fibrosis and endothelial-to-mesenchymal transition. Isoproterenol was used to induce cardiac fibrosis in mice, and evodiamine was gavaged simultaneously. After 14 days, cardiac function was accessed by echocardiography. The extent of cardiac fibrosis and hypertrophy was evaluated by pathological and molecular analyses. The extent of endothelial-to-mesenchymal transition was evaluated by the expression levels of CD31, CD34, α-smooth muscle actin, and vimentin by immunofluorescence staining and Western blot analysis. After 14 days, the heart weight/body weight ratio and heart weight/tibia length ratio revealed no significant difference between the isoproterenol group and the isoproterenol/evodiamine-treated groups, whereas the increased heart weight was reduced in the isoproterenol/evodiamine-treated groups. Echocardiography revealed that interventricular septal thickness and left ventricular posterior wall thickness at the end diastole decreased in the evodiamine-treated groups. Evodiamine reduced isoproterenol-induced cardiac fibrosis as accessed by normalization in collagen deposition and gene expression of hypertrophic and fibrotic markers. Evodiamine also prevented endothelial-to-mesenchymal transition as evidenced by the increased expression levels of CD31 and CD34, decreased expression levels of α-smooth muscle actin and vimentin, and increased microvascular density in the isoproterenol/evodiamine-treated mice hearts. Furthermore, isoproterenol-induced activation of transforming growth factor-ß1/Smad signal was also blunted by evodiamine. Therefore, evodiamine may prevent isoproterenol-induced cardiac fibrosis by regulating endothelial-to-mesenchymal transition, which is probably mediated by the blockage of the transforming growth factor-ß1/Smad pathway.

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

Vascular dysfunction, characterized by the endothelial-to-mesenchymal transition (EndMT), contributes to the development of cardiac fibrosis induced by pressure overload. Toll-like receptor (TLR)5 is a member of the TLR family that is expressed on not only immune cells but also nonimmune cells including cardiomyocytes and vascular endothelial cells. The level of TLR5 expression on endothelial cells is low under normal circumstances but is increased in response to stimuli such as pressure overload. The aim of this study was to investigate the importance of TLR5 in cardiac endothelial dysfunction during the development of cardiac fibrosis induced by pressure overload. Global TLR5-deficient mice and wild-type littermates underwent aortic banding (AB) for 8weeks to induce cardiac fibrosis, hypertrophy and dysfunction. The deficiency of TLR5 in this model exerted no basal effects but attenuated the cardiac fibrosis, hypertrophy and dysfunction induced by pressure overload. AB-induced endothelial TLR5 activation enhanced the development of cardiac fibrosis independent of cardiomyocyte hypertrophy and triggered left ventricular dysfunction. TLR5-deficient mice also exhibited ameliorated myocardial pro-inflammatory cytokine expression and macrophage infiltration and inhibited the EndMT, all of which contribute to the development of cardiac fibrosis. These findings suggest that TLR5 triggers inflammatory responses and promotes the EndMT, which may be an important mechanism underlying the promotion of cardiac fibrosis and left ventricular dysfunction during pressure overload.

OX40 regulates pressure overload-induced cardiac hypertrophy and remodelling via CD4+ T-cells.

OX40, which belongs to the tumour necrosis factor (TNF)-receptor family, is a costimulatory receptor that can potentiate T-cell receptor signalling on the surface of T-lymphocytes. The role of OX40 in non-immune systems, particularly the cardiovascular system, has not been defined. In the present study, we observed a noticeable increase in OX40 expression during cardiac remodelling in rodent heart. In the present study, cardiac hypertrophy was induced by aortic banding (AB) in OX40 knockout (KO) mice and wild-type (WT) mice. After 8 weeks, the OX40 KO mice showed significantly attenuated cardiac hypertrophy, fibrosis and inflammation as well as preserved cardiac function compared with the WT mice. Follow-up in vitro studies suggested that CD4+ T-lymphocyte proliferation and pro-inflammatory cytokine release were significantly decreased, whereas anti-inflammatory cytokine release was considerably increased in OX40 KO mice compared with WT mice as assessed by Cell Counting Kit-8 (CCK-8) assay and ELISA. Co-culturing neonatal rat cardiomyocytes with the activated supernatant of CD4+ T-lymphocytes from OX40 KO mice reduced the hypertrophy response. Interestingly, OX40 KO mice with reconstituted CD4+ T-lymphocytes presented deteriorated cardiac remodelling. Collectively, our data indicate that OX40 regulates cardiac remodelling via the modulation of CD4+ T-lymphocytes.

Nobiletin attenuates cardiac dysfunction, oxidative stress, and inflammatory in streptozotocin: induced diabetic cardiomyopathy.

Diabetic cardiomyopathy, characterized by the presence of diastolic and/or systolic myocardial dysfunction, is one of the major causes of heart failure. Nobiletin, which is extracted from the fruit peel of citrus, is reported to possess anti-inflammatory, anti-oxidative, and hypolipidemic properties. The purpose of this study was to investigate whether nobiletin exerts the therapeutic effect on streptozotocin-induced diabetic cardiomyopathy (DCM) in mice. 80 experimental male C57BL mice were randomly assigned into four groups: sham + vehicle (VEH/SH), sham + nobiletin (NOB/SH), DCM + vehicle (VEH/DM), and DCM + nobiletin (NOB/DM). Nobiletin treatment ameliorated cardiac dysfunction in the DCM group, as shown by the result of echocardiography and hemodynamic measurements. Nobiletin treatment also blunted the mRNA expression of NADPH oxidase isoforms p67(phox), p22(phox), and p91(phox), and abated oxidative stress. Although administration of diabetic mice with nobiletin did not significantly effect the level of blood glucose, it decreased the TGF-ß1, CTGF, fibronectin, and collagen Iα expressions and blunted cardiac fibrosis. In addition, nobiletin inhibited the activation of c-Jun NH2-terminal kinase (JNK), P38, and NF-κB in the cardiac tissue of diabetic mice. Collectively, our study indicates that treatment with nobiletin mitigates cardiac dysfunction and interstitial fibrosis, and these beneficial of nobiletin may belong to the suppression of JNK, P38, and NF-κB signaling pathways.

Cathepsin B deficiency attenuates cardiac remodeling in response to pressure overload via TNF-α/ASK1/JNK pathway.

Cathepsin B (CTSB), a member of the lysosomal cathepsin family that is expressed in both murine and human hearts, was previously shown to participate in apoptosis, autophagy, and the progression of certain types of cancers. Recently, CTSB has been linked to myocardial infarction. Given that cathepsin L, another member of the lysosomal cathepsin family, ameliorates pathological cardiac hypertrophy, we hypothesized that CTSB plays a role in pressure overload-induced cardiac remodeling. Here we report that CTSB was upregulated in cardiomyocytes in response to hypertrophic stimuli both in vivo and in vitro. Moreover, knockout of CTSB attenuated pressure overload-induced cardiac hypertrophy, fibrosis, dysfunction, and apoptosis. Furthermore, the aortic banding-induced activation of TNF-α, apoptosis signal-regulating kinase 1 (ASK1), c-Jun NH2-terminal kinases (JNK), c-Jun, and release of cytochrome c was blunted by CTSB deficiency, which was further confirmed in in vitro studies induced by angiotensin II. In cardiomyocytes pretreatment with SP600125, a JNK inhibitor, suppressed the cardiomyocytes hypertrophy by inhibiting the ASK1/JNK pathway. Altogether, these data indicate that the CTSB protein functions as a necessary modulator of hypertrophic response by regulating TNF-α/ASK1/JNK signaling pathway involved in cardiac remodeling.

Oleanolic acid alleviated pressure overload-induced cardiac remodeling.

Previous study has demonstrated that oleanolic acid (OA) possessing the anti-inflammatory and anti-oxidant properties blunted high-glucose-induced diabetic cardiomyopathy and ameliorated experimental autoimmune myocarditis in mice. However, little is known about its effects on pressure overload-induced cardiac remodeling. Herein, we investigated the effect of OA on cardiac remodeling and underlying mechanism. Mice, subjected to aortic banding (AB), were randomly assigned into control group and experimental group. OA premixed in diets was administered to mice after 3 days of AB. Echocardiography and catheter-based measurements of hemodynamic parameters were performed after 8 weeks' treatment of OA. Histologic examination and molecular analyses were used to assess cardiac hypertrophy and tissue fibrosis. In addition, the inhibitory effects of OA on H9c2 cardiomyocytes and cardiac primary fibroblast responded to the stimulation of AngII were also investigated. OA ameliorated the systolic and diastolic dysfunction induced by pressure overload evidenced by echocardiography and catheter-based measurements. OA also decreased the mRNA expression of cardiac hypertrophy and fibrosis markers evidenced by RT-PCR. It has been shown in our study that pressure overload activated the phosphorylations of Akt, mTOR, p70s6k, S6, GSK3ß, and FoxO3a, and treatment of OA attenuated the phosphorylation of these proteins. In addition, hypertrophy of cardiomyocytes and fibrosis markers induced by AngII was inhibited by OA in vitro. Our findings uncover that OA suppressed AB-induced cardiac hypertrophy, partly by inhibiting the activity of Akt/mTOR pathway, and suggest that treatment of OA may have a benefit on retarding the progress of cardiac remodeling under long terms of pressure overload.

Disruption of tumor necrosis factor receptor associated factor 5 exacerbates pressure overload cardiac hypertrophy and fibrosis.

The cytoplasmic signaling protein tumor necrosis factor (TNF) receptor-associated factor 5 (TRAF5), which was identified as a signal transducer for members of the TNF receptor super-family, has been implicated in several biological functions in T/B lymphocytes and the innate immune response against viral infection. However, the role of TRAF5 in cardiac hypertrophy has not been reported. In the present study, we investigated the effect of TRAF5 on the development of pathological cardiac hypertrophy induced by transthoracic aorta constriction (TAC) and further explored the underlying molecular mechanisms. Cardiac hypertrophy and function were evaluated with echocardiography, hemodynamic measurements, pathological and molecular analyses. For the first time, we found that TRAF5 deficiency substantially aggravated cardiac hypertrophy, cardiac dysfunction and fibrosis in response to pressure overload after 4 weeks of TAC compared to wild-type (WT) mice. Moreover, the mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK)-extracellular signal-regulated kinases 1/2 (ERK1/2) signaling pathway was more activated in TRAF5-deficient mice than WT mice. In conclusion, our results suggest that as an intrinsic cardioprotective factor, TRAF5 plays a crucial role in the development of cardiac hypertrophy through the negative regulation of the MEK-ERK1/2 pathway. J. Cell. Biochem. 115: 349-358, 2014. © 2013 Wiley Periodicals, Inc.

Baicalein protects against cardiac hypertrophy through blocking MEK-ERK1/2 signaling.

Baicalein, a flavonoid present in the root of Scutellaria baicalensis, is well known for its antibacterial, antiviral, anti-inflammatory, antithrombotic, and antioxidant effects. Here we show that baicalein also attenuates cardiac hypertrophy. Aortic banding (AB) was performed to induce cardiac hypertrophy secondary to pressure overload in mice. Mouse chow containing 0.05% baicalein (dose: 100 mg/kg/day baicalein) was begun 1 week prior to surgery and continued for 8 weeks after surgery. Our data demonstrated that baicalein prevented cardiac hypertrophy and fibrosis induced by AB, as assessed by echocardiographic and hemodynamic parameters and by pathological and molecular analysis. The inhibitory action of baicalein on cardiac hypertrophy was mediated by effects on mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinases (ERK1/2) signaling and GATA-4 activation. In vitro studies performed in rat cardiac H9c2 cells confirmed that baicalein attenuated cardiomyocyte hypertrophy induced by angiotensin II, which was associated with inhibiting MEK-ERK1/2 signaling. In conclusion, our results suggest that baicalein has protective potential for targeting cardiac hypertrophy and fibrosis through suppression of MEK-ERK1/2 signaling. Baicalein warrants further research as a potential antihypertrophic agent that might be clinically useful to treat cardiac hypertrophy and heart failure.

NOD2 deletion promotes cardiac hypertrophy and fibrosis induced by pressure overload.

Nucleotide-binding oligomerization domain-2 (NOD2, also designated CARD15), a member of the NOD-leucine-rich repeat (LRR) protein family (also called the CATERPILLAR family), is upregulated in atheroma lesions and has an important role in regulating the intracellular recognition of bacterial components by immune cells. However, the effect of NOD2 on cardiac hypertrophy induced by a pathological stimulus has not been determined. Here, we investigated the effects of NOD2 deficiency on cardiac hypertrophy induced by aortic banding (AB) in mice. Cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. NOD2 expression was upregulated in cardiomyocytes after aortic banding surgery in wild-type (WT) mice. NOD2 deficiency promoted cardiac hypertrophy and fibrosis 4 weeks after AB. Further, the enhanced activation of TLR4 and the MAPKs, NF-κB and TGF-ß/Smad pathways were found in NOD2-knockout (KO) mice compared with WT mice. Our results suggest that NOD2 attenuates cardiac hypertrophy and fibrosis via regulation of multiple pathways.

Interferon regulatory factor 3 is a negative regulator of pathological cardiac hypertrophy.

Interferon regulatory factor (IRF) 3, a member of the highly conserved IRF family transcription factors, plays a pivotal role in innate immune response, apoptosis, and oncogenesis. Recent studies have implicated IRF3 in a wide range of host defense. However, whether IRF3 induces defensive responses to hypertrophic stresses such as biomechanical stress and neurohumoral factors remains unclear. Herein, we employed an IRF3-deficient mouse model, cardiac-specific IRF3-overexpression mouse model and isolated cardiomyocytes to investigate the role of IRF3 in cardiac hypertrophy induced by aortic banding (AB) or isoproterenol (ISO). The extent of cardiac hypertrophy was quantitated by echocardiography as well as by pathological and molecular analysis. Our results demonstrate that IRF3 deficiency profoundly exacerbated cardiac hypertrophy, whereas overexpression of IRF3 in the heart significantly blunted pathological cardiac remodeling induced by pressure overload. Similar results were also observed in cultured cardiomyocytes upon the treatment with ISO. Mechanistically, we discovered that IRF3 interacted with ERK2 and thereby inhibited the ERK1/2 signaling. Furthermore, inactivation of ERK1/2 by U0126 offset the IRF3-deficient-mediated hypertrophic response induced by aortic banding. Altogether, these data demonstrate that IRF3 plays a protective role in AB-induced hypertrophic response by inactivating ERK1/2 in the heart. Therefore, IRF3 could be a new target for the prevention and therapy of cardiac hypertrophy and failure.

Regulator of G protein signaling 5 protects against cardiac hypertrophy and fibrosis during biomechanical stress of pressure overload.

The development of cardiac hypertrophy in response to increased hemodynamic load and neurohormonal stress is initially a compensatory response that may eventually lead to ventricular dilation and heart failure. Regulator of G protein signaling 5 (Rgs5) is a negative regulator of G protein-mediated signaling by inactivating Galphaq and Galphai, which mediate actions of most known vasoconstrictors. Previous studies have demonstrated that Rgs5 expresses among various cell types within mature heart and showed high levels of Rgs5 mRNA in monkey and human heart tissue by Northern blot analysis. However, the critical role of Rgs5 on cardiac remodeling remains unclear. To specifically determine the role of Rgs5 in pathological cardiac remodeling, we used transgenic mice with cardiac-specific overexpression of human Rgs5 gene and Rgs5-/- mice. Our results demonstrated that the transgenic mice were resistant to cardiac hypertrophy and fibrosis through inhibition of MEK-ERK1/2 signaling, whereas the Rgs5-/- mice displayed the opposite phenotype in response to pressure overload. These studies indicate that Rgs5 protein is a crucial component of the signaling pathway involved in cardiac remodeling and heart failure.

Gastrodin protects against cardiac hypertrophy and fibrosis.

Phenolic glucoside gastrodin (Gas), which is a main component extracted from the Chinese herbs Gastrodia elata Bl, is a well-known natural calcium antagonist with antioxidant and anti-inflammatory functions. It has long been used clinically for treatment of cardiovascular and cerebrovascular diseases. Previous studies have shown that gastrodin possesses comprehensive pharmacological functions. However, very little is known about whether gastrodin has protective role on cardiac hypertrophy. The aim of this study was to determine whether gastrodin attenuates pressure overload-induced cardiac hypertrophy in mice and to clarify the underlying molecular mechanisms. Our data demonstrated that gastrodin prevented cardiac hypertrophy induced by aortic banding (AB), as assessed by heart weight/body weight and lung weight/body weight ratios, echocardiographic parameters, and gene expression of hypertrophic markers. The inhibitory effect of gastrodin on cardiac hypertrophy is mediated by ERK1/2 signaling and GATA-4 activation. Further studies showed that gastrodin attenuated fibrosis and collagen synthesis through abrogating ERK1/2 signaling pathway. Therefore, these findings indicated that gastrodin, which is a potentially safe and inexpensive therapy for clinical use, has protective potential in targeting cardiac hypertrophy and fibrosis through suppression of ERK1/2 signaling.

HSP75 protects against cardiac hypertrophy and fibrosis.

Cardiac hypertrophy, a major determinant of heart failure, is associated with heat shock proteins (HSPs). HSP75 has been reported to protect against environmental stresses; however, its roles in cardiac hypertrophy remain unclear. Here, we generated cardiac-specific inducible HSP75 transgenic mice (TG) and cardiac hypertrophy was developed at 4 weeks after aortic banding in TG mice and wild-type littermates. The results revealed that overexpression of HSP75 prevented cardiac hypertrophy and fibrosis as assessed by heart weight/body weight ratio, heart weight/tibia length ratio, echocardiographic and hemodynamic parameters, cardiomyocyte width, left ventricular collagen volume, and gene expression of hypertrophic markers. Further studies showed that overexpression of HSP75 inhibited the activation of TAK/P38, JNK, and AKT signaling pathways. Thus, HSP75 likely reduces the hypertrophy and fibrosis induced by pressure overload through blocking TAK/P38, JNK, and AKT signaling pathways.

The Role of Cold Inducible RNA-Binding Protein in Cardiac Physiology and Diseases.

Cold-inducible RNA-binding protein (CIRP) is an intracellular stress-response protein that can respond to various stress conditions by changing its expression and regulating mRNA stability. As an RNA-binding protein, CIRP modulates gene expression at the post-transcriptional level, including those genes involved in DNA repair, cellular redox metabolism, circadian rhythms, telomere maintenance, and cell survival. CIRP is expressed in a large variety of tissues, including testis, brain, lung, kidney, liver, stomach, bone marrow, and heart. Recent studies have observed the important role of CIRP in cardiac physiology and diseases. CIRP regulates cardiac electrophysiological properties such as the repolarization of cardiomyocytes, the susceptibility of atrial fibrillation, and the function of the sinoatrial node in response to stress. CIRP has also been suggested to protect cardiomyocytes from apoptosis under various stress conditions, including heart failure, high glucose conditions, as well as during extended heart preservation under hypothermic conditions. This review summarizes the findings of CIRP investigations in cardiac physiology and diseases and the underlying molecular mechanism.

Liquiritin Attenuates Lipopolysaccharides-Induced Cardiomyocyte Injury via an AMP-Activated Protein Kinase-Dependent Signaling Pathway.

Background: Liquiritin (LIQ) is a traditional Chinese medicine that has been reported to regulate inflammation, oxidative stress and cell apoptosis. However, the beneficial effects of LIQ in lipopolysaccharides (LPS)-induced septic cardiomyopathy (SCM) has not been reported. The primary goal of this study was to investigate the effects of LIQ in LPS-induced SCM model. Methods: Mice were pre-treated with LIQ for 7 days before they were injected with LPS (10 mg/kg) for inducing SCM model. Echocardiographic analysis was used to evaluate cardiac function after 12 h of LPS injection. Thereafter, mice were sacrificed to collect hearts for molecular and histopathologic assays by RT-PCR, western-blots, immunohistochemical and terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) staining analysis respectively. AMPKα2 knockout (AMPKα2-/-) mice were used to elucidate the mechanism of LIQ Neonatal rat cardiomyocytes (NRCMs) treated with or without LPS were used to further investigate the roles and mechanisms of LIQ in vitro experiments. Results: LIQ administration attenuated LPS-induced mouse cardiac dysfunction and reduced mortality, based upon the restoration of EF, FS, LVEDs, heart rate, dp/dt max and dp/dt min deteriorated by LPS treatment. LIQ treatment also reduced mRNA expression of TNFα, IL-6 and IL-1ß, inhibited inflammatory cell migration, suppressed cardiac oxidative stress and apoptosis, and improved metabolism. Mechanistically, LIQ enhanced the phosphorylation of AMP-activated protein kinase α2 (AMPKα2) and decreased the phosphorylation of mTORC1, IκBα and NFκB/p65. Importantly, the beneficial roles of LIQ were not observed in AMPKα2 knockout model, nor were they observed in vitro model after inhibiting AMPK activity with an AMPK inhibitor. Conclusion: We have demonstrated that LIQ exerts its protective effects in an SCM model induced by LPS administration. LIQ reduced inflammation, oxidative stress, apoptosis and metabolic alterations via regulating AMPKα2 dependent signaling pathway. Thus, LIQ might be a potential treatment or adjuvant for SCM treatment.

Efficacy and Safety of Leflunomide for Refractory COVID-19: A Pilot Study.

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may persist in patients with coronavirus disease 2019 (COVID-19) despite receiving standard care. Methods: In this pilot study of hospitalized adult patients (≥18 years of age), with radiologically confirmed pneumonia who were SARS-CoV-2 positive for more than 28 days despite standard care, were assigned to receive standard of care (SOC, grp I) or leflunomide + SOC (grp 2). After 2 weeks, grp 1 and grp 2 patients who continued to be SARS-CoV-2-positive received leflunomide for 14 days while continuing SOC. The primary outcomes were the rate of and time to SARS-CoV-2 clearance and the 14-day and 30-day hospital discharge rate. Results: 12 patients were enrolled in grp 1 and 15 patients were in grp 2. The 14 days SARS-CoV-2 viral clearance rate was 80.0% (12/15) for grp 2 patients receiving leflunomide vs. 16.7% for grp 1 patients (2/12) (p = 0.002). By day 14, the median time to SARS-CoV-2 clearance was 6.0 days (range 1-12, IQR 1-12) for grp 2 patients. In grp 1, two patients converted to viral negative on days 1 and 6 (p = 0.002). The 14-day discharge rate was 73.3% (11/15) for the grp 2 vs. 8.3% (1/12) for grp 1 (p = 0.001). The 30 days discharge rate was 100% (15/15) for the grp 2 vs. 66.7% (8/12) for grp 1. No severe adverse events or deaths were reported. Conclusion: Leflunomide may improve the SARS-CoV-2 clearance rate and discharge rate in patients with refractory COVID-19. The tolerability of the 14-28 days course of treatment with leflunomide is acceptable. These preliminary observations need to be verified by a large sample size and randomized controlled trial.