β-arrestin 2 attenuates cardiac dysfunction in polymicrobial sepsis through gp130 and p38.
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ABSTRACT:
SUBMITTER: Yan H
PROVIDER: S-EPMC5147748 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Cardiac dysfunction is correlated with detrimental prognosis of sepsis and contributes to a high risk of mortality. After an initial hyperinflammatory reaction, most patients enter a protracted state of immunosuppression (late sepsis) that alters both innate and adaptive immunity. The changes of cardiac function in late sepsis are not yet known. MicroRNA-155 (miR-155) is previously found to play important roles in both regulations of immune activation and cardiac function. In this study, C57BL/6 mice were operated to develop into early and late sepsis phases, and miR-155 mimic was injected through the tail vein 48 h after cecal ligation and puncture (CLP). The effect of miR-155 on CLP-induced cardiac dysfunction was explored in late sepsis. We found that increased expression of miR-155 in the myocardium protected against cardiac dysfunction in late sepsis evidenced by attenuating sepsis-reduced cardiac output and enhancing left ventricular systolic function. We also observed that miR-155 markedly reduced the infiltration of macrophages and neutrophils into the myocardium and attenuated the inflammatory response via suppression of JNK signaling pathway. Moreover, overexpression of β-arrestin 2 (Arrb2) exacerbated the mice mortality and immunosuppression in late sepsis. Furthermore, transfection of miR-155 mimic reduced Arrb2 expression, and then restored immunocompetence and improved survival in late septic mice. We conclude that increased miR-155 expression through systemic administration of miR-155 mimic attenuates cardiac dysfunction and improves late sepsis survival by targeting JNK associated inflammatory signaling and Arrb2 mediated immunosuppression.
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Project description:The development of cardiac dysfunction caused by microbial infection predicts high mortality in sepsis patients. Specialized pro-resolving mediators (SPMs) mediate resolution of inflammation in many inflammatory diseases, and are differentially expressed in plasma of sepsis patients. Here, we investigated whether the levels of SPMs are altered in the murine septic heart following polymicrobial sepsis-induced cardiac dysfunction. Ten weeks-old male C57BL/6 mice were subjected to polymicrobial sepsis induced by cecal ligation and puncture (CLP), which is a clinically relevant sepsis model receiving analgesics, antibiotics, and fluid resuscitation. CLP caused a significant systolic dysfunction assessed by echocardiography. The hearts were subjected to LC-MS/MS based lipid mediator profiling. Many SPMs were significantly reduced in septic hearts, among which RvE1 had a ~93-fold reduction. Treatment of CLP mice with synthetic RvE1 (1 μg/mouse i.v.) at 1 h after CLP increased peritoneal macrophages number, particularly MHC II- macrophages. RvE1 reduced pro-inflammatory gene expression (interleukin-1β, interleukin-6, and CCL2) in lipopolysaccharide-stimulated bone marrow-derived macrophages (BMDMs) in vitro. RvE1 attenuated cardiac dysfunction in septic mice and increased cardiac phosphorylated Akt; decreased cardiac phosphorylated IκB kinase α/β, nuclear translocation of the NF-κB subunit p65, extracellular signal-regulated kinase 1/2, and c-Jun amino-terminal kinases 1/2. Most notably, RvE1 treatment reduced peritoneal bacterial load and promoted phagocytosis activity of BMDMs. In conclusion, cardiac SPMs, particularly RvE1, are substantially reduced in mice with polymicrobial sepsis. Delayed therapeutic administration of RvE1 to mice with polymicrobial sepsis attenuates the cardiac dysfunction through modulating immuno-inflammatory responses. In addition to the above effects, the ability to enhance bacterial clearance makes RvE1 an ideal therapeutic to reduce the sequalae of polymicrobial sepsis.
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Project description:Septic cardiomyopathy is a life-threatening organ dysfunction caused by sepsis. Ribonuclease 1 (RNase 1) belongs to a group of host-defense peptides that specifically cleave extracellular RNA (eRNA). The activity of RNase 1 is inhibited by ribonuclease-inhibitor 1 (RNH1). However, the role of RNase 1 in septic cardiomyopathy and associated cardiac apoptosis is completely unknown. Here, we show that sepsis resulted in a significant increase in RNH1 and eRNA serum levels compared with those of healthy subjects. Treatment with RNase 1 resulted in a significant decrease of apoptosis, induced by the intrinsic pathway, and TNF expression in murine cardiomyocytes exposed to either necrotic cardiomyocytes or serum of septic patients for 16 hours. Additionally, treatment of septic mice with RNase 1 resulted in a reduction in cardiac apoptosis, TNF expression, and septic cardiomyopathy. These data demonstrate that eRNA plays a crucial role in the pathophysiology of the organ (cardiac) dysfunction in sepsis and that RNase and RNH1 may be new therapeutic targets and/or strategies to reduce the cardiac injury and dysfunction caused by sepsis.
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Project description:?-Arrestin-1 (?Arr1), a scaffolding protein critical in G-protein coupled receptor desensitization has more recently been found to be important in the pathogenesis of various inflammatory diseases. We sought to understand the role of ?Arr1 in sepsis pathogenesis using a mouse model of polymicrobial sepsis. Although in previous studies we established that ?Arr1 deficiency protects mice from endotoxemia, here we demonstrate that the absence of ?Arr1 remarkably renders mice more susceptible to mortality in polymicrobial sepsis. In accordance with the mortality pattern, early production of inflammatory mediators was markedly enhanced in ?Arr1 knockout mice systemically and locally in various organs. In addition, enhanced inflammation in the heart was associated with increased NF?B activation. Compared to these effects, immune cell infiltration, thymic apoptosis, and immune suppression during polymicrobial sepsis were unaffected by a deficiency of ?Arr1. Additionally, enhanced inflammation and consequent higher mortality were not observed in heterozygous mice, suggesting that one allele of ?Arr1 was sufficient for this protective negative regulatory role. We further demonstrate that, unexpectedly, ?Arr1 in nonhematopoietic cells is critical and sufficient for inhibiting sepsis-induced inflammation, whereas hematopoietic ?Arr1 is likely redundant. Taken together, our results reveal a novel and previously unrecognized negative regulatory role of the nonhematopoietic ?Arr1 in sepsis-induced inflammation.
| S-EPMC4116700 | biostudies-literature
Project description:Patients with CKD requiring dialysis have a higher risk of sepsis and a 100-fold higher mortality rate than the general population with sepsis. The severity of cardiac dysfunction predicts mortality in patients with sepsis. Here, we investigated the effect of preexisting CKD on cardiac function in mice with sepsis and whether inhibition of I?B kinase (IKK) reduces the cardiac dysfunction in CKD sepsis. Male C57BL/6 mice underwent 5/6 nephrectomy, and 8 weeks later, they were subjected to LPS (2 mg/kg) or sepsis by cecal ligation and puncture (CLP). Compared with sham operation, nephrectomy resulted in significant increases in urea and creatinine levels, a small (P<0.05) reduction in ejection fraction (echocardiography), and increases in the cardiac levels of phosphorylated I?B?, Akt, and extracellular signal-regulated kinase 1/2; nuclear translocation of the NF-?B subunit p65; and inducible nitric oxide synthase (iNOS) expression. When subjected to LPS or CLP, compared with sham-operated controls, CKD mice exhibited exacerbation of cardiac dysfunction and lung inflammation, greater increases in levels of plasma cytokines (TNF-?, IL-1?, IL-6, and IL-10), and greater increases in the cardiac levels of phosphorylated IKK?/? and I?B?, nuclear translocation of p65, and iNOS expression. Treatment of CKD mice with an IKK inhibitor (IKK 16; 1 mg/kg) 1 hour after CLP or LPS administration attenuated these effects. Thus, preexisting CKD aggravates the cardiac dysfunction caused by sepsis or endotoxemia in mice; this effect may be caused by increased cardiac NF-?B activation and iNOS expression.
| S-EPMC5198262 | biostudies-literature
Project description:Aims: Cardiac dysfunction can be a fatal complication during severe sepsis. The migration of neutrophils is significantly impaired during severe sepsis. We sought to determine the role of trimetazidine (TMZ) in regulation of neutrophil migration to the heart in a mouse model of sepsis and endotoxemia, and to identify the mechanism whereby TMZ confers a survival advantage. Methods and Results: C57/BL6 mice were (1) injected with LPS followed by 24-h TMZ administration, or (2) treated with TMZ (20 mg/kg/day) for 1 week post cecal ligation and puncture (CLP) operation. Echocardiography and Millar system detection showed that TMZ alleviated cardiac dysfunction and histological staining showed the failure of neutrophils migration to heart in both LPS- and CLP-induced mice. Bone marrow transplantation revealed that TMZ-pretreated bone marrow cells improved LPS- and CLP-induced myocardial dysfunction and enhanced neutrophil recruitment in heart. In CXCL2-mediated chemotaxis assays, TMZ increased neutrophils migration via AMPK/Nrf2-dependent up-regulation of CXCR2 and inhibition of GRK2. Furthermore, using luciferase reporter gene and chromatin immunoprecipitation assays, we found that TMZ promoted the binding of the Nrf2 and CXCR2 promoter regions directly. Application of CXCR2 inhibitor completely reversed the protective effects of TMZ in vivo. Co-culture of neutrophils and cardiomyocytes further validated that TMZ decreased LPS-induced cardiomyocyte pyroptosis by targeting neutrophils. Conclusion: Our findings suggested TMZ as a potential therapeutic agent for septic or endotoxemia associated cardiac dysfunction in mice. STUDY HIGHLIGHTS What is the current knowledge on the topic? Migration of neutrophils is significantly impaired during severe sepsis, but the underlying mechanisms remain unknown. What question did this study address? The effects of TMZ on cardiac dysfunction via neutrophils migration. What this study adds to our knowledge TMZ attenuated LPS-induced cardiomyocyte pyroptosis and cardiac dysfunction by promoting neutrophils recruitment to the heart tissues via CXCR2. How this might change clinical pharmacology or translational science Our findings suggested TMZ as a potential therapeutic agent for septic cardiac dysfunction.
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Project description:AimsAim was to elucidate the specific role of pattern recognition receptors in vascular dysfunction during polymicrobial sepsis (colon ascendens stent peritonitis, CASP).Methods and resultsVascular contractility of C57BL/6 (wildtype) mice and mice deficient for Toll-like receptor 2/4/9 (TLR2-D, TLR4-D, TLR9-D) or CD14 (CD14-D) was measured 18 h following CASP. mRNA expression of pro- (Tumor Necrosis Factor-? (TNF?), Interleukin (IL)-1?, IL-6) and anti-inflammatory cytokines (IL-10) and of vascular inducible NO-Synthase (iNOS) was determined using RT-qPCR. Wildtype mice exhibited a significant loss of vascular contractility after CASP. This was aggravated in TLR2-D mice, blunted in TLR4-D animals and abolished in TLR9-D and CD14-D animals. TNF-? expression was significantly up-regulated after CASP in wildtype and TLR2-D animals, but not in mice deficient for TLR4, -9 or CD14. iNOS was significantly up-regulated in TLR2-D animals only. TLR2-D animals showed significantly higher levels of TLR4, -9 and CD14. Application of H154-ODN, a TLR9 antagonist, attenuated CASP-induced cytokine release and vascular dysfunction in wildtype mice.ConclusionsWithin our model, CD14 and TLR9 play a decisive role for the development of vascular dysfunction and thus can be effectively antagonized using H154-ODN. TLR2-D animals are more prone to polymicrobial sepsis, presumably due to up-regulation of TLR4, 9 and CD14.
| S-EPMC3436884 | biostudies-literature
Project description:BackgroundToll-like receptors (TLRs) play a role in the pathophysiology of sepsis and multiple organ failure. This study examined the effect of CpG oligodeoxynucleotide (CpG-ODN), the TLR9 ligand, on polymicrobial sepsis-induced cardiac dysfunction.MethodsMale C57BL/6 mice were treated with CpG-ODN, control CpG-ODN (control-ODN), or inhibitory CpG-ODN (iCpG-ODN) 1 hour prior to cecal ligation and puncture (CLP)-induced sepsis. Mice that underwent sham surgery served as sham controls. Cardiac function was examined by echocardiography before and 6 hours after CLP.ResultsCardiac function was significantly decreased 6 hours after CLP. CpG-ODN prevented CLP-induced cardiac dysfunction, as evidenced by maintenance of the ejection fraction and fractional shortening. Control-ODN or iCpG-ODN did not alter CLP-induced cardiac dysfunction. CpG-ODN significantly attenuated CLP-induced myocardial apoptosis and increased myocardial Akt and extracellular-signal-related kinase (ERK) phosphorylation levels following CLP. In vitro experiments demonstrated that CpG-ODN promotes an association between TLR9 and Ras, resulting in Akt and ERK phosphorylation. Inhibition of phosphoinositide 3-kinase (PI3K) by Ly294002 or inhibition of ERK by U0126 in vivo abolished CpG-ODN attenuation of CLP-induced cardiac dysfunction.ConclusionsCpG-ODN prevents CLP-induced cardiac dysfunction, in part through activation of PI3K/Akt and ERK signaling. Modulation of TLR9 could be an effective approach for treatment of cardiovascular dysfunction in patients with sepsis or septic shock.
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Project description:Obesity is a well-known public health issue around the world. Sepsis is a lethal clinical syndrome that causes multiorgan failure. Obesity may aggravate inflammation in septic patients. Glutamine (GLN) is a nutrient with immune regulatory and anti-inflammatory properties. Since sepsis is a common contributing factor for acute kidney injury (AKI), this study investigated the effects of GLN administration on sepsis-induced inflammation and AKI in obese mice. A high-fat diet which consists of 60% of calories from fat was provided for 10 weeks to induce obesity in the mice. Then, the obese mice were subdivided into sepsis with saline (SS) or GLN (SG) groups. Cecal ligation and puncture (CLP) was performed to produce sepsis. The SS group was intravenously injected with saline while the SG group was administered GLN one or two doses after CLP. Obese mice with sepsis were sacrificed at 12, 24, or 48 h post-CLP. Results revealed that sepsis resulted in upregulated high-mobility group box protein-1 pathway-associated gene expression in obese mice. Also, expressions of macrophage/neutrophil infiltration markers and inflammatory cytokines in kidneys were elevated. Obese mice treated with GLN after sepsis reversed the depletion of plasma GLN, reduced production of lipid peroxides, and downregulated macrophage/neutrophil infiltration and the inflammatory-associated pathway whereas tight junction gene expression increased in the kidneys. These findings suggest that intravenously administered GLN to obese mice after sepsis alleviated inflammation and attenuated AKI. This model may have clinical application to obese patients with a risk for infection in abdominal surgery.
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Project description:There is limited evidence that the tissue-protective effects of erythropoietin are mediated by a heterocomplex of the erythropoietin receptor and the ?-common receptor ('tissue-protective receptor'), which is pharmacologically distinct from the 'classical' erythropoietin receptor homodimer that is responsible for erythropoiesis. However, the role of the ?-common receptor and/or erythropoietin in sepsis-induced cardiac dysfunction (a well known, serious complication of sepsis) is unknown. Here we report for the first time that the ?-common receptor is essential for the improvements in the impaired systolic contractility afforded by erythropoietin in experimental sepsis. Cardiac function was assessed in vivo (echocardiography) and ex vivo (Langendorff-perfused heart) in wild-type and ?-common receptor knockout mice, that were subjected to lipopolysaccharide (9 mg/kg body weight; young mice) for 16-18 hours or cecal ligation and puncture (aged mice) for 24 hours. Mice received erythropoietin (1000 IU/kg body weight) 1 hour after lipopolysaccharide or cecal ligation and puncture. Erythropoietin reduced the impaired systolic contractility (in vivo and ex vivo) caused by endotoxemia or sepsis in young as well as old wild-type mice in a ?-common-receptor-dependent fashion. Activation by erythropoietin of the ?-common receptor also resulted in the activation of well-known survival pathways (Akt and endothelial nitric oxide synthase) and inhibition of pro-inflammatory pathways (glycogen synthase kinase-3?, nuclear factor-?B and interleukin-1?). All the above pleiotropic effects of erythropoietin were lost in ?-common receptor knockout mice. Erythropoietin attenuates the impaired systolic contractility associated with sepsis by activation of the ?-common receptor, which, in turn, results in activation of survival pathways and inhibition of inflammation.
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