Low-tidal-volume prevent ventilation induced inflammation in a mouse model of sepsis

BACKGROUND AND GOAL OF THE STUDY

Pulmonary inflammation, increased vascular permeability, and pulmonary edema, occur in response to primary pulmonary infections like pneumonia but are also evident in endotoxemia or sepsis. Mechanical ventilation augments pre-existing lung injury and inflammation resulting from exposure to microbial products. The objective of this study was to test the hypothesis that low-tidal-volume prevent ventilation induced lung injury in sepsis.

MATERIALS AND METHODS

10-12-week-old male C57BL/6N-mice received an intraperitoneal (i.p.) injection with equipotent dosages of LPS, 1668-thioate, 1612-thioate, or PBS. 120 min after injection, mice were randomized to low- (LV, 7 ± 1 ml/kg) or high-tidal-volume (HV, 25 ± 1 ml/kg) ventilation. Hemodynamic and ventilatory parameters were recorded and inflammatory markers were analyzed form BAL that was generated after 90 minute ventilation.

RESULTS AND DISCUSSION

Arterial blood pressures declined during mechanical ventilation in all groups. pO₂ decreased in LPS injected and CO₂ increased in sham, LPS, and 1612-thioate administered mice at 45 min and in 1668-thioate injected mice after 90 minute LV ventilation compared to respective HV groups. BAL protein concentrations increased in HV ventilated and 1668- or 1612-thioat pre-treated mice. BAL TNF-α protein concentrations increased in both LPS- and 1668-thioate-injected and IL-1β protein concentrations only in LPS-injected and HV ventilated mice. Most notably, no increased protein concentrations were observed in any of the LV ventilated groups.

CONCLUSION

We conclude that low-tidal-volume ventilation may be a potential strategy for the prevention of ventilator induced lung injury in a murine model of systemic TLR agonist induced lung injury.

Improve hip fracture outcome in the elderly patient (iHOPE): a study protocol for a pragmatic, multicentre randomised controlled trial to test the efficacy of spinal versus general anaesthesia

INTRODUCTION

Hip fracture surgery is associated with high in-hospital and 30-day mortality rates and serious adverse patient outcomes. Evidence from randomised controlled trials regarding effectiveness of spinal versus general anaesthesia on patient-centred outcomes after hip fracture surgery is sparse.

METHODS AND ANALYSIS

The iHOPE study is a pragmatic national, multicentre, randomised controlled, open-label clinical trial with a two-arm parallel group design. In total, 1032 patients with hip fracture (>65 years) will be randomised in an intended 1:1 allocation ratio to receive spinal anaesthesia (n=516) or general anaesthesia (n=516). Outcome assessment will occur in a blinded manner after hospital discharge and inhospital. The primary endpoint will be assessed by telephone interview and comprises the time to the first occurring event of the binary composite outcome of all-cause mortality or new-onset serious cardiac and pulmonary complications within 30 postoperative days. In-hospital secondary endpoints, assessed via in-person interviews and medical record review, include mortality, perioperative adverse events, delirium, satisfaction, walking independently, length of hospital stay and discharge destination. Telephone interviews will be performed for long-term endpoints (all-cause mortality, independence in walking, chronic pain, ability to return home cognitive function and overall health and disability) at postoperative day 30±3, 180±45 and 365±60. ETHICS AND DISSEMINATION: iHOPE has been approved by the leading Ethics Committee of the Medical Faculty of the RWTH Aachen University on 14 March 2018 (EK 022/18). Approval from all other involved local Ethical Committees was subsequently requested and obtained. Study started in April 2018 with a total recruitment period of 24 months. iHOPE will be disseminated via presentations at national and international scientific meetings or conferences and publication in peer-reviewed international scientific journals.

TRIAL REGISTRATION NUMBER

DRKS00013644; Pre-results.

Synthetic CpG oligonucleotides induce a genetic profile ameliorating murine myocardial I/R injury

We previously demonstrated that pre‐conditioning with CpG oligonucleotide (ODN) 1668 induces quick up‐regulation of gene expression 3 hours post‐murine myocardial ischaemia/reperfusion (I/R) injury, terminating inflammatory processes that sustain I/R injury. Now, performing comprehensive microarray and biocomputational analyses, we sought to further enlighten the “black box” beyond these first 3 hours. C57BL/6 mice were pretreated with either CpG 1668 or with control ODN 1612, respectively. Sixteen hours later, myocardial ischaemia was induced for 1 hour in a closed‐chest model, followed by reperfusion for 24 hours. RNA was extracted from hearts, and labelled cDNA was hybridized to gene microarrays. Data analysis was performed with BRB ArrayTools and Ingenuity Pathway Analysis. Functional groups mediating restoration of cellular integrity were among the top up‐regulated categories. Genes known to influence cardiomyocyte survival were strongly induced 24 hours post‐I/R. In contrast, proinflammatory pathways were down‐regulated. Interleukin‐10, an upstream regulator, suppressed specifically selected proinflammatory target genes at 24 hours compared to 3 hours post‐I/R. The IL1 complex is supposed to be one regulator of a network increasing cardiovascular angiogenesis. The up‐regulation of numerous protective pathways and the suppression of proinflammatory activity are supposed to be the genetic correlate of the cardioprotective effects of CpG 1668 pre‐conditioning.

Decreased Secondary Lesion Growth and Attenuated Immune Response after Traumatic Brain Injury in Tlr2/4-/- Mice

Danger-associated molecular patterns are released by damaged cells and trigger neuroinflammation through activation of non-specific pattern recognition receptors, e.g., toll-like receptors (TLRs). Since the role of TLR2 and 4 after traumatic brain injury (TBI) is still unclear, we examined the outcome and the expression of pro-inflammatory mediators after experimental TBI in Tlr2/4^−/− and wild-type (WT) mice. Tlr2/4^−/− and WT mice were subjected to controlled cortical injury and contusion volume and brain edema formation were assessed 24 h thereafter. Expression of inflammatory markers in brain tissue was measured by quantitative PCR 15 min, 3 h, 6 h, 12 h, and 24 h after controlled cortical impact (CCI). Contusion volume was significantly attenuated in Tlr2/4^−/− mice (29.7 ± 0.7 mm³ as compared to 33.5 ± 0.8 mm³ in WT; p < 0.05) after CCI while brain edema was not affected. Only interleukin (IL)-1β gene expression was increased after CCI in the Tlr2/4^−/− relative to WT mice. Inducible nitric oxide synthetase, TNF, IL-6, and COX-2 were similar in injured WT and Tlr2/4^−/− mice, while the increase in high-mobility group box 1 was attenuated at 6 h. TLR2 and 4 are consequently shown to potentially promote secondary brain injury after experimental CCI via neuroinflammation and may therefore represent a novel therapeutic target for the treatment of TBI.

Tlr2 deficiency does not limit the development of left ventricular hypertrophy in a model of transverse aortic constriction induced pressure overload

Background

Toll-like receptors (TLRs) are involved in a variety of cardiovascular disorders, including septic cardiomyopathy, ischemia/reperfusion, heart failure, and cardiac hypertrophy. Previous research revealed that TLR4 promotes cardiac hypertrophy in vivo. Therefore, we investigated whether TLR2 is also involved in the development of cardiac hypertrophy.

Methods

Tlr2 deficient and wild type mice were subjected to transverse aortic constriction (TAC) or sham operation procedure. Left ventricular, heart and lung weights as well as hemodynamic parameters were determined after 3, 14 or 28 days. Real-time RT PCR was used to evaluate left ventricular gene expression. Protein content was determined via ELISA.

Results

TAC increased systolic left ventricular pressure, contraction and relaxations velocities as well as the heart weight in both genotypes. Tlr2 deficiency significantly enhanced cardiac hypertrophy after 14 and 28 days of TAC. Left ventricular end-diastolic pressure and heart rate increased in Tlr2^−/− TAC mice only. Fourteen days of TAC led to a significant elevation of ANP, BNP, TGFβ and TLR4 mRNA levels in Tlr2^−/− left ventricular tissue.

Conclusion

These data suggest that Tlr2 deficiency may promote the development of cardiac hypertrophy and ventricular remodeling after transverse aortic constriction.

Antifungal antibiotics modulate the pro-inflammatory cytokine production and phagocytic activity of human monocytes in an in vitro sepsis model

AIMS

The incidence of secondary systemic fungal infections has sharply increased in bacterial septic patients. Antimycotics exhibit immunomodulatory properties, yet these effects are incompletely understood in secondary systemic fungal infections following bacterial sepsis. We investigated a model of systemic inflammation to determine whether antimycotics (liposomal amphotericin B (L-AMB), itraconazol (ITC), and anidulafungin (ANI)) modulate the gene and protein expression as well as the phagocytic activity of lipopolysaccharide (LPS)-stimulated human monocytes.

MAIN METHODS

THP-1 monocytes were incubated with L-AMB, ITC or ANI and LPS. Gene expression levels of cytokines (TNF-<alpha>, IL-1<beta>, IL-6, and IL-10) were measured after 2h, 6h, and 24h. Cytokine protein levels were evaluated after 24h and phagocytic activity was determined following co-incubation with Escherichia coli.

KEY FINDINGS

All antimycotics differentially modulated the gene and protein expression of cytokines in sepsis-like conditions. In the presence of LPS, we identified L-AMB as immunosuppressive, whereas ITC demonstrated pro-inflammatory properties. Both compounds induced remarkably less phagocytosis.

SIGNIFICANCE

Our study suggests that antimycotics routinely used in septic patients alter the immune response in sepsis-like conditions by modulating cytokine gene and protein expression levels and phagocytic activity. Future treatment strategies should consider the immune status of the host and apply antimycotics accordingly in bacterial septic patients with secondary fungal infections.

Postconditioning with a CpG containing oligodeoxynucleotide ameliorates myocardial infarction in a murine closed-chest model

AIMS

Toll-like receptor (TLR)9 ligand CpG-oligodeoxynucleotide (CpG-ODN) exerts preconditioning in myocardial ischemia/reperfusion. We hypothesized a postconditioning effect of CpG-ODN in a murine closed-chest model of myocardial infarction.

MATERIALS AND METHODS

C57BL/6 (12 weeks, male, WT) mice were instrumented at the left anterior descending artery, then allowed 5d of recovery before 30 min ischemia. Treatments comprised: 1) PBS: 250 μl phosphate buffer solution intraperitoneally 5 min before reperfusion and 2) IPC (ischemic postconditioning): 3 twenty-second reperfusion and occlusion episodes at the end of ischemia 3) CpG-ODN: 1668 thioate 0.2 μmol/kg BW intraperitoneally 5 min before reperfusion. Infarct size was assessed via triphenyltetrazolium chloride (TTC) staining after 2 and 24h reperfusion. Myocardial mRNA-expression of cytokines was measured using real-time PCR after 2h reperfusion. Phosphatidylinositol-3 kinase (PI3K)-inhibitor wortmannin was injected intraperitoneally in WT 15 min before postconditioning and PBS in each group. Cardiac function in WT was assessed with a left-ventricular pressure-volume catheter at 24h reperfusion.

KEY FINDINGS

Following 30 min ischemia and 2h reperfusion, infarct size was diminished by 90% in WT postconditioned with CpG-ODN (2.4 ± 1.55 IS/AAR%) and IPC (1.98 ± 1.03 IS/AAR%) compared to PBS mice (23.2 ± 3.97 IS/AAR%). Infarct size increased following 24h reperfusion but the differences remained robust. Expression of TNF-α and IL-10 was increased in CpG-ODN. Wortmannin abolished the postconditioning effect of CpG-ODN and IPC. Ejection fraction and preload-recruitable stroke work were significantly greater in CpG-ODN mice.

SIGNIFICANCE

CpG-ODN confers postconditioning via activation of TLR9. Cardiac function is preserved following CpG-ODN postconditioning. The PI3K -inhibitor wortmannin attenuates CpG-ODN postconditioning.

Antibiotics regulate the immune response in both presence and absence of lipopolysaccharide through modulation of Toll-like receptors, cytokine production and phagocytosis in vitro

The inflammatory response to pathogen-associated molecular patterns such as lipopolysaccharide (LPS) in sepsis is mediated via Toll-like receptors (TLRs). Since TLRs also trigger various immune functions, including phagocytosis, their modulation is a promising strategy in the treatment of sepsis. As antibiotics have immunomodulatory properties, this study examined the effect of commonly used classes of antibiotics on i) the expression of TLRs and cytokines and ii) the phagocytic activity under sepsis-like conditions in vitro. This was achieved by incubating THP-1 monocytes and peripheral blood mononuclear cells (PBMCs) obtained from patients after open-heart surgery with the addition of LPS and six key antibiotics (piperacillin, doxycycline, erythromycin, moxifloxacin or gentamicin). After 24h, mRNA levels of both cytokines (IL-1β, IL-6) and TLRs (1, 2, 4, and 6) were monitored and phagocytosis was determined following coincubation with Escherichia coli. Each antibiotic differentially regulated the gene expression of the investigated TLRs and cytokines in monocytes. Erythromycin, moxifloxacin and doxycyclin displayed the strongest effects and changed mRNA-levels of the investigated genes up to 5.6-fold. Consistent with this, antibiotics and, in particular, moxifloxacin, regulated the TLR-and cytokine expression in activated PBMCs obtained from patients after open-heart surgery. Furthermore, piperacillin, doxycyclin and moxifloxacin inhibited the phagocytic activity of monocytes. Our results suggest that antibiotics regulate the immune response by modulating TLR- and cytokine expression as well as phagocytosis under septic conditions. Moxifloxacin, doxycycline and erythromycin were shown to possess the strongest immunomodulatory effects and these antibiotic classes should be considered for future immunomodulatory studies in sepsis.

Anti-atherogenic effects of statins: Impact on angiopoietin-2 release from endothelial cells

Beyond lipid lowering, statins are supposed to exert pleiotropic effects positively influencing the progression of atherosclerotic lesions. The development of such lesions is associated with increased release of angiopoietin-2 (Ang-2), an endothelial cell-specific protein growth factor stored in Weibel-Palade bodies (WPBs). The aim of our study was to examine whether statin pretreatment influences the release of Ang-2 from endothelial cells. Stimulation of HUVECs and HMVECs with PMA, thrombin or histamine resulted in significant release of Ang-2, as evidenced by ELISA. Pretreatment with simvastatin and mevastatin suppressed this release to basal level, while pravastatin had no effect. Simvastatin itself increased nitric oxide (NO, EC number 1.14.13.39) synthesis, measured by Griess reaction. Combining the statin pretreatment with the eNOS inhibitor L-NNA as well as bypassing the HMG-CoA reductase (EC number: 1.1.1.34) by adding mevalonic acid or geranyl pyrophosphate restored the exocytotic effect of PMA. Immunofluorescence microscopy showed that depletion of WPBs upon PMA stimulation ceased after pretreatment with simvastatin. This study demonstrates a potent suppressive effect of statins on the release of Ang-2 from endothelial cells. Regarding its harmful effects in the development of atherosclerotic lesions, our data provide further insight into the mechanisms of the anti-atherogenic potential of statins.

Pre-conditioning with synthetic CpG-oligonucleotides attenuates myocardial ischemia/reperfusion injury via IL-10 up-regulation

The aim of the study was to investigate whether pre-conditioning with CpG-oligodeoxynucleotides (CpG-ODN) may change cardiac ischemia/reperfusion (I/R)-dependent inflammation and modulates infarct size and cardiac performance. WT and TLR9-deficient mice were pre-treated with 1668-, 1612- and H154-thioate or D-Gal as control. Priming with 1668-thioate significantly induced inflammatory mediators in the serum and a concomitant increase of immune cells in the blood and spleen of WT mice. Furthermore, it induced myocardial pattern recognition receptors and pro-inflammatory cytokines peaking 2 h after priming and a continuous increase of IL-10. 16 h after pre-conditioning, myocardial ischemia was induced for 1 h. Infarct size determined after 24 h of I/R was reduced by 75 % due to pre-conditioning with 1668-thioate but not in the other groups. During reperfusion, cytokine expression in 1668-thioate primed mice increased further with IL-10 exceeding the other mediators by far. These changes were observed neither in animals pre-treated with 1612- or H154-thioate nor in TLR9-deficient mice. The 1668-thioate-dependent increase of IL-10 was further supported by results of a micro-array analysis 3 h after begin of reperfusion. Block of IL-10 signaling increased I/R size and prevented influence of priming. In the group pre-treated with 1668-thioate, cardiac function was preserved 24 h, 14 days and 28 days after I/R, whereas animals without pre-conditioning exhibited impaired heart function 24 h and 14 days after I/R. The excessive 1668-thioate-dependent IL-10 up-regulation during pre-conditioning and after I/R seems to be the key factor for reducing infarct size and improving cardiac function. This is in agreement with the finding that IL-10 block prevents cardioprotection by pre-conditioning.

A rare case of direct tumor extension to the right ventricle

We report the case of a 72-year-old woman with signs of pulmonary embolism and right heart failure. Echocardiographic imaging and computed tomography revealed a mass within the inferior vena cava reaching from the head of the pancreas to the right ventricle. From standard imaging procedures and clinical findings alone, differentiation of a cardiac thrombus from a metastatic tumor mass was difficult. After resection of the intravascular tumor, histopathologic analysis confirmed a metastasis of primary ductal pancreatic adenocarcinoma. This is a report of a case of mucinous adenocarcinoma of the pancreas reaching the heart by continuous intravascular spreading.

Priming with synthetic oligonucleotides attenuates pressure overload-induced inflammation and cardiac hypertrophy in mice

AIMS

Inflammation and Toll-like receptor (TLR) signalling have been linked to the development of cardiac hypertrophy following transverse aortic constriction (TAC). In the present study, we investigated whether pre-treatment with the synthetic TLR9 ligands 1668-thioate or 1612-thioate modulates the progression of TAC-induced cardiac inflammation and hypertrophy.

METHODS AND RESULTS

C57BL/6N-mice were pre-treated with 1668-thioate, 1612-thioate (0.25 nmol/g, i.p.), or phosphate-buffered saline 16 h prior to TAC or sham surgery. Heart-weight/body-weight ratio (HW/BW), cardiomyocyte cell size, cellular macrophage accumulation, myofibroblast differentiation, and collagen deposition were investigated for up to 28 days. Cardiac function was monitored using a pressure-volume catheter and M-mode echocardiography. Inflammatory gene expression in the heart was analysed via gene array, while the time course of mRNA expression of key inflammatory mediators was assessed via RT-qPCR. TAC increased the HW/BW ratio and cardiomyocyte cell size and induced macrophage accumulation, myofibroblast differentiation, and collagen deposition. These changes were accompanied by cardiac inflammation and a significant loss of left ventricular function. Pre-treatment with cytosine-phosphate-guanine (CpG)-containing 1668-thioate attenuated the inflammatory response, the progression of cardiac hypertrophy, and cardiac remodelling, which resulted in a prolonged preservation of left ventricular function. These changes were induced to a smaller extent by the use of the non-CG-containing oligodeoxynucleotide 1612-thioate.

CONCLUSION

Pre-treatment with 1668-thioate attenuated cardiac hypertrophy following pressure overload, possibly by modifying the hypertrophy-induced inflammatory response, thereby reducing cardiac growth and fibrosis as well as delaying loss of cardiac function.

Vascular dysfunction following polymicrobial sepsis: role of pattern recognition receptors

AIMS

Aim was to elucidate the specific role of pattern recognition receptors in vascular dysfunction during polymicrobial sepsis (colon ascendens stent peritonitis, CASP).

METHODS AND RESULTS

Vascular 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-α (TNFα), Interleukin (IL)-1β, 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-α 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.

CONCLUSIONS

Within 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.

Remote ischaemic preconditioning for heart surgery. The study design for a multi-center randomized double-blinded controlled clinical trial--the RIPHeart-Study

AIMS

Transient ischaemia of non-vital tissue has been shown to enhance the tolerance of remote organs to cope with a subsequent prolonged ischaemic event in a number of clinical conditions, a phenomenon known as remote ischaemic preconditioning (RIPC). However, there remains uncertainty about the efficacy of RIPC in patients undergoing cardiac surgery. The purpose of this report is to describe the design and methods used in the "Remote Ischaemic Preconditioning for Heart Surgery (RIPHeart)-Study".

METHODS

We are conducting a prospective, randomized, double-blind, multicentre, controlled trial including 2070 adult cardiac surgical patients. All types of surgery in which cardiopulmonary bypass is used will be included. Patients will be randomized either to the RIPC group receiving four 5 min cycles of transient upper limb ischaemia/reperfusion or to the control group receiving four cycles of blood pressure cuff inflation/deflation at a dummy arm. The primary endpoint is a composite outcome (all-cause mortality, non-fatal myocardial infarction, any new stroke, and/or acute renal failure) until hospital discharge.

CONCLUSION

The RIPHeart-Study is a multicentre trial to determine whether RIPC may improve clinical outcome in cardiac surgical patients.

The toll-like receptor 4-antagonist eritoran reduces murine cardiac hypertrophy

AIMS

Toll-like receptor 4 (TLR4) recognizes lipopolysaccharides and endogenous ligands released after organ injury. Deficiency of TLR4 attenuates the development of left ventricular hypertrophy after transverse aortic constriction (TAC) in mice. We hypothesized that application of the TLR4 antagonist eritoran may also reduce cardiac hypertrophy after TAC surgery.

METHODS AND RESULTS

A catheter was implanted into the jugular vein of C57BL/6 mice to allow repeated administration of eritoran (5 mg/kg body weight) or placebo. Three days after TAC or sham surgery, heart weights were determined and cardiac tissue underwent mRNA and protein quantification. The TAC placebo group exhibited a significant increase in left ventricular weight, left ventricular weight/tibia length, and left ventricular/body weight ratio compared with the sham and TAC eritoran groups. Natriuretic peptide mRNA was elevated significantly only in TAC placebo mice. Transverse aortic constriction surgery led to a distinct increase in interleukin (IL)-1β and IL-6 mRNA and protein expression in the placebo but not the eritoran group. In contrast, IL-10 was significantly increased in both eritoran groups independent from TAC. Matrix metalloproteinase zymographic activity was highest in TAC placebo animals.

CONCLUSION

Application of the TLR4 antagonist eritoran attenuates the development of cardiac hypertrophy possibly by a reduction in inflammatory and increase in anti-inflammatory cytokines.

[Traumatic tricuspid valve insufficiency with right-to-left shunt: bridging using extracorporeal venovenous membrane oxygenation]

The case of a young male motor vehicle driver is reported who suffered multiple trauma in a car accident with pulmonary and cardiac contusions. In the course of severe pneumonia and traumatic tricuspid valve insufficiency a right-to-left shunt with refractory hypoxemia developed across a pre-existing atrial septal defect (ASD). The patient could be successfully treated by the combination of extracorporeal membrane oxygenation for bridging, interventional ASD occlusion and in the long-term by operative reconstruction of the tricuspid valve.

Bacterial DNA induces myocardial inflammation and reduces cardiomyocyte contractility: role of toll-like receptor 9

AIMS

Myocardial function is severely compromised during sepsis. Several underlying mechanisms have been proposed. The innate immune system, i.e. toll-like receptor (TLR) 2 and 4, significantly contributes to cardiac dysfunction. Little is known regarding TLR9 and its pathogenic ligand bacterial DNA in the myocardium. We therefore studied the role of TLR9 in myocardial inflammation and cardiac contractility.

METHODS AND RESULTS

Wild-type (WT, C57BL/6) and TLR9-deficient (TLR9-D) mice and isolated cardiomyocytes were challenged with synthetic bacterial DNA (CpG-ODN). Myocardial contractility as well as markers of inflammation/signalling were determined. Isolated cardiomyocytes incorporated fluorescence-marked CpG-ODN. In WT mice, CpG-ODN caused a robust response in hearts demonstrated by increased levels of tumour necrosis factor (TNF-alpha), interleukin (IL)-1beta, IL-6, inducible nitric oxide synthase (iNOS), and nuclear factor kappaB activity. This inflammatory response was absent in TLR9-D mice. Under similar conditions, contractility measurements of isolated ventricular cardiomyocytes demonstrated a TLR9-dependent loss of sarcomeric shortening after CpG-ODN exposure. This observation was iNOS dependent as the application of a specific iNOS inhibitor reversed sarcomeric shortening to normal levels.

CONCLUSION

Our data suggest that bacterial DNA contributes to myocardial cytokine production and loss of cardiomyocyte contractility via TLR9.

CpG oligonucleotide activates Toll-like receptor 9 and causes lung inflammation in vivo

Background

Bacterial DNA containing motifs of unmethylated CpG dinucleotides (CpG-ODN) initiate an innate immune response mediated by the pattern recognition receptor Toll-like receptor 9 (TLR9). This leads in particular to the expression of proinflammatory mediators such as tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β). TLR9 is expressed in human and murine pulmonary tissue and induction of proinflammatory mediators has been linked to the development of acute lung injury. Therefore, the hypothesis was tested whether CpG-ODN administration induces an inflammatory response in the lung via TLR9 in vivo.

Methods

Wild-type (WT) and TLR9-deficient (TLR9-D) mice received CpG-ODN intraperitoneally (1668-Thioat, 1 nmol/g BW) and were observed for up to 6 hrs. Lung tissue and plasma samples were taken and various inflammatory markers were measured.

Results

In WT mice, CpG-ODN induced a strong activation of pulmonary NFκB as well as a significant increase in pulmonary TNF-α and IL-1β mRNA/protein. In addition, cytokine serum levels were significantly elevated in WT mice. Increased pulmonary content of lung myeloperoxidase (MPO) was documented in WT mice following application of CpG-ODN. Bronchoalveolar lavage (BAL) revealed that CpG-ODN stimulation significantly increased total cell number as well as neutrophil count in WT animals. In contrast, the CpG-ODN-induced inflammatory response was abolished in TLR9-D mice.

Conclusion

This study suggests that bacterial CpG-ODN causes lung inflammation via TLR9.

Induction of p53 by GKLF is essential for inhibition of proliferation of vascular smooth muscle cells

Proliferation of vascular smooth muscle cells (VSMC) plays an important role in the pathogenesis of atherosclerosis and restenosis. Recent studies have demonstrated that the transcription factor gut-enriched Krüppel-like factor (GKLF, KLF4) is involved in redox-sensitive growth arrest of VSMC. We investigated the role of GKLF in VSMC proliferation and differentiation and the potentially important interaction with the tumor suppressor gene p53. Cultured rat aortic VSMC were transfected with GKLF sense and antisense constructs by electroporation. GKLF enhanced the mRNA expression of the differentiation marker SM22-alpha, but had no effect on the expression of alpha-smooth muscle actin (real-time RT-PCR, Western blot). Overexpression of GKLF significantly reduced VSMC proliferation (cell count, BrdU FACS analysis). Because p53 is essential for proliferation processes, the effect of GKLF on p53 gene expression was investigated. GKLF overexpression led to an enhanced p53 promoter activity and increased p53 mRNA and protein expression (luciferase reporter assay, real-time PCR, Western blot). Consistently, GKLF overexpression induced an enhanced expression of the p53 target genes p21(WAF1/Cip1) and Mdm2. Co-transfection experiments revealed that the growth arrest induced by GKLF sense transfection was completely abolished by co-transfection of p53 antisense constructs, whereas the reduced proliferation exerted by p53 sense transfection was not inhibited by GKLF antisense transfection, suggesting that p53 induction is essential for the interference of GKLF with VSMC proliferation. Finally, stimulation of VSMC with hydroxyl radicals increased expression of GKLF and p53 and reduced cell proliferation. The transcription factor GKLF induces inhibition of proliferation of VSMC which is mechanistically linked to a GKLF-induced enhancement of the expression of the tumor suppressor gene p53.

Toll-like receptor 9 expression in murine and human adrenal glands and possible implications during inflammation

CONTEXT

Sepsis is a leading cause of death in the Western world and can be associated with failure of the hypothalamic-pituitary-adrenal axis. A coordinated response of the adrenal and immune system is of vital importance for survival during sepsis. Within the immune response, Toll-like receptors (TLRs) play a crucial role by recognizing pathogen-associated molecules such as bacterial DNA. TLR-9 can detect motifs of unmethylated cytosine-phosphate-guanine (CpG) dinucleotides (CpG-DNA) being present in bacterial DNA.

OBJECTIVE

We investigated whether TLR-9 is expressed in human and murine adrenal glands and whether its activation is associated with an adrenal response.

DESIGN

Human fetal and adult adrenal glands; wild-type, C57BL/6 and TLR-9 deficient (TLR-9-/-) mice; and in vitro cell line models were used in the study.

SETTING

The study took place at a university hospital.

RESULTS

TLR-9 is expressed in human and murine adrenal glands, as well as in in vitro cell lines (Y-1 and NCI-H295R cells). CpG-oligodeoxynucleotide challenge caused a 3-fold increase in plasma levels of corticosterone in wild-type mice. This effect was not observed in TLR-9-/- mice. Furthermore, CpG-oligodeoxynucleotide challenge resulted in a strong release of several inflammatory cytokines, such as TNF-alpha, and IL-1beta, -6, -10, and -12 in vivo as well as in vitro. Again, this effect was not present in TLR-9-/- mice.

CONCLUSIONS

TLR-9 is present in both murine and human adrenal glands. TLR-9 stimulation led to a corticosterone and inflammatory cytokine response. TLR-9 may play a role in the regulation of the hypothalamic-pituitary-adrenal axis during conditions in which bacterial DNA is present.

Role of Toll-like receptor 4 for the pathogenesis of acute lung injury in Gram-negative sepsis

BACKGROUND AND OBJECTIVE

Proinflammatory cytokines as well as nitric oxide (NO) play a major role in mediating the response to lipopolysaccharide (LPS). The present study tested the hypothesis that LPS induces proinflammatory cytokines in the lung via the Toll-like receptor 4 (TLR4)/CD14 signalling cascade.

METHODS

Control mice and TLR4-deficient (TLR4-D) mice were used to test TLR4-mediated effects of LPS. Both strains received either Escherichia coli LPS (20 mg kg-1 intraperitoneal) or saline and their lungs were collected at different time points. Pulmonary nuclear factor kappaB (NFkappaB) activation was investigated with electromobility shift assay. mRNA expression of inflammatory mediators and their corresponding receptors were detected with Ribonuclease Protection Assay. Protein expression was detected by ELISA and western blotting. Inducible NO synthase (iNOS) expression was monitored by RT-PCR and iNOS activity by conversion of l-arginine to citrulline. Immune cells were sampled by bronchoalveolar lavage (BAL) and classified.

RESULTS

LPS application induced CD14-, but not TLR4 protein expression in control mice. Activation of pulmonary NFkappaB was observed within 60 min in control, but not in TLR4-D mice. Six hours of LPS administration induced a significant increase in pulmonary tumour necrosis factor alpha-, interleukin-1beta- and interleukin-6 mRNA and protein expression in control mice compared to TLR4-D mice. Furthermore, LPS induced a significantly higher increase of the iNOS expression and catalytic activity in control mice than in TLR4-D mice. BAL revealed an increase in total cell count in all LPS treated mice.

CONCLUSION

Our findings suggest that TLR4 plays a key role for regulating the expression of relevant cytokines within the lung during endotoxic shock.

Toll-like receptor 4 modulates myocardial ischaemia-reperfusion injury: Role of matrix metalloproteinases

Toll-like receptor 4 (TLR4) mediates innate immune responses following endotoxemia and myocardial ischaemia-reperfusion (I/R) injury. Pre-treatment with the major TLR4 ligand lipopolysaccharide (LPS) reduces infarct size. Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) play a crucial role in endotoxemia possibly also determining I/R injury.

AIMS

We investigated the influence of TLR4 on infarct size and assessed the influence of MMP and TIMP regulation on I/R injury.

METHODS

Left anterior descending artery (LAD) occlusion was performed on wild-type (C3H/HeN) and TLR4-deficient (C3H/HeJ) mice. Animals were stimulated with LPS (1 mg/kg) or PBS 16 h ahead of 60 min LAD ligation. After 24 h of reperfusion, triphenyltetrazolium chloride staining was performed and infarct size was measured by planimetry. MMP- and TIMP-mRNA expression were determined by RPA after 3 h of reperfusion. MMP zymographic activity was monitored 6 h after occlusion.

RESULTS

TLR4-deficient mice and LPS-treated wild-type mice showed significantly reduced infarct areas. LPS-stimulation significantly increased the overall MMP/TIMP mRNA expression ratio due to elevated MMP-3, -8, -9, and TIMP-1 in wild-type mice. I/R overall reduced the MMP/TIMP ratio due to increased MMP-1, TIMP-1, and -3 mRNA expression.

CONCLUSIONS

LPS pre-treatment and TLR4-deficiency led to a decreased infarct size. However, infarct area and MMP/TIMP ratio were not correlated. This means that in TLR4-deficient mice MMP/TIMP ratios are not determining the infarct size.

Myocardial injury modulates the innate immune system and changes myocardial sensitivity

OBJECTIVE

Transverse aortic constriction (TAC) results in a transient increase of proinflammatory cytokines, which return to baseline levels within 3 d. In contrast to cytokine baseline levels, the myocardium remains capable to respond even stronger to a new stimulus. As the molecular mechanisms for this phenomenon are unknown, we tested whether TAC modulates the innate immune system in mice and changes the inflammatory reaction to a new stimulus.

METHODS

Following 3 d of TAC or sham-operation procedure (SOP), LPS (20 mg/kg) or PBS (control) were administered intraperitoneal for 10 min as well as for 6 h. Hemodynamic parameters were recorded to measure the effects of TAC and LPS. After TAC/SOP alone CD14 expression was monitored and after additional 6 h of LPS/PBS the expression of CD14, TLR4 and proinflammatory cytokines were determined by western-blot, ELISA and RNase protection assay, respectively. Following TAC/SOP and 10 min of LPS/PBS, NFkappaB activation was investigated by EMSA.

RESULTS

TAC induced cardiac hypertrophy and elevated blood pressure. LPS application led to hypotension and other symptoms of sepsis. CD14 expression increased after TAC alone and even further after additional LPS challenge. However, we did not detect changes of TLR4 expression. Also NFkappaB activation increased after LPS challenge higher in the TAC than in the SOP group. LPS-stimulation induced also higher cytokine expression in the TAC than in the SOP group.

CONCLUSION

TAC modulates innate immunity by regulating the expression of CD14 and changes the myocardial tissue to respond more powerful to LPS.

Toll-like receptor 4, nitric oxide, and myocardial depression in endotoxemia

The molecular mechanisms that mediate gram-negative sepsis-associated myocardial dysfunction remain elusive. Myocardial expression of inflammatory mediators is Toll-like receptor 4 (TLR4) dependent. However, it remains to be elucidated whether TLR4, expressed on cardiac myocytes, mediates impairment of cardiac contractility after lipopolysaccharide (LPS) application. Cardiac myocyte contractility, measured as sarcomere shortening of isolated cardiac myocytes from C3H/HeJ (with nonfunctional TLR4) and C3H/HeN (control), were recorded at stimulation frequencies between 0.5 and 10 Hz and after incubation with 1 and 10 mug/mL LPS for up to 8 h. Control cells treated with LPS were investigated with and without a competitive LPS inhibitor (E5564) and a specific inducible nitric oxide synthase (iNOS) inhibitor S-methylisothiourea. In control mice, LPS reduced sarcomere shortening amplitude and prolonged duration of relaxation, whereas sarcomere shortening of C3H/HeJ cells was insensitive to LPS. NFkappaB and iNOS were upregulated after LPS application in control mice compared with C3H/HeJ. Inhibition of TLR4 by E5564 as well as inhibition of iNOS prevented the influence of LPS on contractile activity in control myocytes. LPS-dependent suppression of cardiac myocyte contractility was significantly blunted in C3H/HeJ mice. Competitive inhibition of functional TLR4 with E5564 protects cardiac myocyte contractility against LPS. These findings suggest that TLR4, expressed on cardiac myocytes, contributes to sepsis-induced myocardial dysfunction. E5564, currently under investigation in two clinical phase II trials, seems to be a new therapeutic option for the treatment of myocardial dysfunction in sepsis associated with endotoxemia.

Toll-like receptor 4 plays a crucial role in the immune-adrenal response to systemic inflammatory response syndrome

Sepsis and septic shock are leading killers in the noncoronary intensive care unit, and they remain worldwide health concerns. The initial host defense against bacterial infections involves Toll-like receptors (TLRs), which detect and respond to microbial ligands. In addition, a coordinated response of the adrenal and immune systems is crucial for survival during severe inflammation. Previously, we demonstrated a link between the innate immune system and the endocrine stress response involving TLR-2. Like TLR-2, TLR-4 is also expressed in human and mouse adrenals. In the present work, by using a low dose of LPS to mimic systemic inflammatory response syndrome, we have revealed marked cellular alterations in adrenocortical tissue and an impaired adrenal corticosterone response in TLR-4-/- mice. Our findings demonstrate that TLR-4 is a key mediator in the crosstalks between the innate immune system and the endocrine stress response. Furthermore, TLR polymorphisms could contribute to the underlying mechanisms of impaired adrenal stress response in patients with bacterial sepsis.

Myotrophin/V-1 does not act as an extracellular signal to induce myocyte hypertrophy

The myotrophin/V-1 protein was originally found to be elevated in failing heart tissues and was described as an exogenously acting hypertrophy-inducing factor. However, several studies have proposed only intracellular functions for this protein. We investigated whether this protein is an exogenously acting hypertrophy-inducing trophin or an intracellular nuclear factor of kappa B (NFkappaB) regulatory protein. In the current report, immunofluorescence and cell fractionation studies showed that myotrophin is present only in the cytoplasm and is not actively released into the extracellular environment in response to hypertrophy-inducing stimuli. Moreover, in response to ischemia/reperfusion injury, an active release of myotrophin from adult rat myocardium was not observed. Furthermore, protein synthesis studies in rat neonatal myocytes indicated that exogenous myotrophin did not induce hypertrophy. On the other hand, myotrophin stimulates the generation of NFkappaB dimers in vitro and thus regulates the NFkappaB-mediated transcription in cardiac myocytes. Taken together, these studies suggest that myotrophin is a strictly cytosolic protein that regulates the NFkappaB-mediated transcriptional process.

Myocardial cytokine gene expression is higher in aortic stenosis than in idiopathic dilated cardiomyopathy

OBJECTIVE

To investigate cytokine gene expression in patients with aortic valve stenosis (AS) and with idiopathic dilated cardiomyopathy (DCM), and to correlate wall stress with myocardial proinflammatory cytokine gene expression.

METHODS

Human left ventricular (LV) myocardial biopsies were obtained for subsequent reverse transcription polymerase chain reaction of tumour necrosis factor alpha (TNFalpha), interleukin (IL)-1beta, and IL-6 mRNA. The study population consisted of 24 patients with AS and 10 patients with idiopathic DCM.

RESULTS

Patients with AS had a larger ejection fraction (56 (5) v 37 (4)%, p < 0.01), smaller LV end diastolic volumes (146 (11) v 267 (21) ml, p < 0.01), and lower end systolic wall stress (44 (7) v 112 (11) kdyn/cm2, p < 0.001). Upregulation of TNFalpha, IL-1beta, and IL-6 gene expression was detected in both groups. However, TNFalpha gene expression was significantly higher in AS than in DCM (p = 0.009). No correlation was found between haemodynamic parameters and TNFalpha gene expression. In patients with AS there was a strong inverse relation between circulating TNFalpha and TNFalpha gene expression (r = -0.685, p = 0.014), between circulating TNFalpha and IL-1beta gene expression (r = -0.664, p = 0.018), and between soluble TNF receptor 2 and TNFalpha gene expression (r = -0.685, p = 0.020). Myocardial gene expression of TNFalpha was significantly higher in patients with well compensated AS than in patients with decompensated AS (p = 0.017). Similarly, patients with decompensated DCM were characterised by significantly lower TNFalpha gene expression than were patients with well compensated DCM (p = 0.011).

CONCLUSION

TNFalpha gene expression is significantly higher in patients with pressure overload than in normal hearts, in patients with idiopathic DCM, and in patients with compensated versus decompensated heart failure. Secondly, in patients with AS proinflammatory cytokine gene expression did not affect systolic performance. The higher TNFalpha gene expression in patients with compensated heart failure suggests that cytokine gene expression has an adaptive role in the early phase of LV remodelling.

Inactivation of Ets 1 transcription factor by a specific decoy strategy reduces rat C6 glioma cell proliferation and mmp-9 expression

Malignant gliomas represent the most aggressive tumours of the central nervous system and are characterised by both extensive proliferation and invasive growth. Matrix degrading proteases called matrix metalloproteinases (MMPs), particularly MMP-9, play a crucial role in glioma infiltration. The activity of these enzymes is regulated at different levels. In this regard, the control of transcriptional activity by specific transcription factors is believed to be very important. In the present study, we examined whether rat C6 glioma cells express the Ets 1 transcription factor and whether inhibition of Ets 1 by a specific decoy strategy affects C6 glioma cell proliferation and mmp-9 expression. We found that C6 glioma cells express Ets 1 and can efficiently be transfected with an Ets 1-specific decoy oligodesoxynucleotide (ODN). This ODN significantly reduces cell proliferation and mmp-9 expression, the latter in a dose-dependent manner. We conclude that inhibition of transcription factors, which play a role for glioma development and progression such as Ets 1 by specific decoy approaches, might represent useful tools for experimental therapeutic strategies against malignant gliomas.

Functional significance of inflammatory mediators in a murine model of resuscitated hemorrhagic shock

The mechanisms that underlie the development of myocardial dysfunction after resuscitated hemorrhagic shock (HS) are not known. Recent studies suggest that systemic activation of inflammatory mediators may contribute to cellular dysfunction and/or cell death in various organs, including the heart. However, the precise role that inflammatory mediators play in the heart in the setting of resuscitated HS is not known. Accordingly, the purpose of the present study was to use a well-defined murine model of resuscitated HS to characterize the functional significance of inflammatory mediators in the heart in vivo. Mice were subjected to sham operation or resuscitated HS. Left ventricular (LV) function was assessed by two-dimensional echocardiography 6 h after resuscitation. Myocardial TNF, IL-1β, and IL-6 proteins were measured 1 and 6 h after resuscitation. To determine the role of TNF in HS-induced LV dysfunction, mice were treated with a soluble TNF receptor antagonist (etanercept) before HS or at the time of resuscitation. LV fractional shortening was significantly depressed ( P < 0.05) in resuscitated HS mice (28 ± 1.5%) compared with sham controls (35.8 ± 1.0%). TNF and IL-1β levels were significantly increased ( P < 0.05) in resuscitated HS mice. Pretreatment with etanercept abrogated resuscitated HS-induced LV dysfunction, whereas treatment at the time of resuscitation significantly attenuated, but did not abrogate, LV dysfunction. Together, these data suggest that TNF plays a critical upstream role in resuscitated HS-induced LV dysfunction; however, once the deleterious consequences of reperfusion injury are initiated, TNF contributes to, but is not necessary for, the development of LV dysfunction.

Toll-like receptor 2 mediates Staphylococcus aureus-induced myocardial dysfunction and cytokine production in the heart

BACKGROUND

Staphylococcus aureus sepsis is associated with significant myocardial dysfunction. Toll-like receptor 2 (TLR2) mediates the inflammatory response to S aureus and may trigger an innate immune response in the heart. We hypothesized that a TLR2 deficiency would attenuate S aureus-induced cardiac proinflammatory mediator production and the development of cardiac dysfunction.

METHODS AND RESULTS

Wild-type and TLR2-deficient (TLR2D) mice were studied. S aureus challenge significantly increased tumor necrosis factor, interleukin-1beta, and nitric oxide expression in hearts of wild-type mice. This response was significantly blunted in TLR2D mice. Hearts from TLR2D mice had impaired S aureus-induced activation of interleukin-1 receptor-associated kinase, c-Jun NH2 terminal kinase, nuclear factor-kappaB, and activator protein-1. Moreover, hearts from TLR2D mice were protected against S aureus-induced contractile dysfunction.

CONCLUSIONS

These results show for the first time that TLR2 signaling contributes to the loss of myocardial contractility and cytokine production in the heart during S aureus sepsis.

[Cytokines and heart failure]

Chronic heart failure is a major cause for mortality and morbidity in western civilizations. Previous hypothesises regarding the pathogenesis of chronic heart failure did not sufficiently explain the aetiology and the progression of the disease. However, it has been shown that a group of peptides called cytokines are expressed during chronic heart failure and that cytokines might play an important role for the pathogenesis. The expression of cytokines can be modulated from specific ACE-inhibitors as well as from different beta-blockers and angiotensin type 1 antagonists. Numerous investigations have shown that cytokines depress left ventricular function and can be responsible for different characteristics of chronic heart failure. The present article resumes experimental and clinical investigations and recent pharmacologic attempts for the treatment of chronic heart failure. The previous results demonstrate the importance to further investigate anti-inflammatory approaches to treat chronic heart failure.

The Role of Innate Immune Responses in the Heart in Health and Disease

The ability of the myocardium to successfully adapt to environmental stress ultimately determines whether the heart will decompensate and fail, or whether it will maintain preserved function. Despite the importance of the myocardial response to environmental stress, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. The present review summarizes recent experimental material that suggests that the heart possesses a germ-line encoded "innate" stress response that is activated in response to diverse forms of tissue injury. The extant literature suggests that this innate stress response plays an important role in initiating and integrating homeostatic responses within the heart. Nonetheless, as will be discussed further herein, these inflammatory mediators all have the potential to produce cardiac decompensation when expressed at sufficiently high concentrations.

Nuclear Factor-κB Protects the Adult Cardiac Myocyte Against Ischemia-Induced Apoptosis in a Murine Model of Acute Myocardial Infarction

Background— Previous studies have shown that tumor necrosis factor (TNF) confers cytoprotective responses in cardiac myocytes. However, the mechanisms for the cytoprotective effects of TNF remain unknown. Given that TNF signals through nuclear factor κB (NF-κB) and given that NF-κB mediates cytoprotective responses, we asked whether NF-κB activation conferred cytoprotective responses in acute myocardial ischemia/infarction.

Methods and Results— We examined infarct size and the prevalence of apoptosis in transgenic mice harboring cardiac-restricted expression of a mutated IκBα protein (IκBαΔN) that prevents nuclear translocation of NF-κB in cardiac myocytes. Triphenyltetrazolium chloride staining showed that infarct size was ≈50% greater ( P <0.02) in the IκBαΔN mice compared with littermate controls at 24 hours. The prevalence of cardiac myocyte apoptosis was significantly greater ( P <0.008) in the IκBαΔN mice compared with the littermate control mice 3 and 6 hours after left anterior descending occlusion. To explore the mechanism for these findings, we examined protein levels of c-IAP1, c-IAP2, and Bcl-2 as well as manganese superoxide dismutase and c-Jun NH2-terminal kinase activity. These studies showed that protein levels of c-IAP1 and Bcl-2 were significantly lower in the IκBαΔN mice, whereas there was no change in c-IAP2 levels, manganese superoxide dismutase, or c-Jun NH2-terminal kinase activity.

Conclusions— Transgenic mice with a defect in activation of NF-κB have increased susceptibility to tissue injury after acute left anterior descending occlusion. These studies suggest that the cytoprotective effects of NF-κB are mediated, at least in part, by Bcl-2 or c-IAP1.

Gender differences in the expression of heat shock proteins: the effect of estrogen

The heat shock proteins (HSPs) are an important family of endogenous, protective proteins that are found in all tissues. In the heart, HSP72, the inducible form of HSP70, has been the most intensely studied. It is well established that HSP72 is induced with ischemia and is cardioprotective. Overexpression of other HSPs also is protective against cardiac injury. Recently, we observed that 17beta-estradiol increases levels of HSPs in male rat cardiac myocytes. We hypothesized that there were gender differences in HSP72 expression in the heart secondary to estrogen. To test this hypothesis, we examined cardiac levels of HSP72 by ELISA in male and female Sprague-Dawley rats. In addition, three other HSPs were assessed by Western blot (HSP27, HSP60, and HSP90). To determine whether estrogen status affected HSP72 expression in other muscles or tissues, two other muscle tissues, slow twitch muscle (soleus muscle) and fast twitch muscle (gastrocnemius muscle), were studied as well as two other organs, the kidney and liver. Because HSP72 is cardioprotective, and females are known to have less cardiovascular disease premenopause, the effects of ovariectomy were examined. We report that female Sprague-Dawley rat hearts have twice as much HSP72 as male hearts. Ovariectomy reduced the level of HSP72 in female hearts, and this could be prevented by estrogen replacement therapy. These data show that the expression of cardiac HSP72 is greater in female rats than in male rats, due to upregulation by estrogen.

Development of murine ischemic cardiomyopathy is associated with a transient inflammatory reaction and depends on reactive oxygen species

We examined the effects of daily repetitive brief (15 min) myocardial ischemia and reperfusion (I/R) in WT C57BL6 and extracellular superoxide dismutase (EC-SOD)-overexpressing mice. In the absence of myocardial necrosis, I/R resulted in persistent fibrosis in ischemic areas of C57/BL6 mice associated with persistent global and segmental anterior wall dysfunction. The I/R protocol induced chemokines (peak 3 days) followed sequentially by infiltration of macrophages and myofibroblasts (5 days). Fibrosis peaked at 7 days and was stable at 28 days despite regression of the chemokine and cellular response. Discontinuation of I/R at 7 or 28 days led to regression of fibrosis and ventricular dysfunction. In contrast, the EC-SOD mice developed markedly less chemokine induction, cell response, and fibrosis, with no ventricular dysfunction. Reversible fibrosis and ventricular dysfunction are features of human hibernating myocardium. The reduction of the cellular and functional response in EC-SOD mice suggests a role for reactive O(2) in the pathogenesis of ischemic cardiomyopathy.

CD14-deficient mice are protected against lipopolysaccharide-induced cardiac inflammation and left ventricular dysfunction

BACKGROUND

The molecular mechanisms responsible for sepsis-induced myocardial dysfunction remain undefined. CD14 mediates the inflammatory response to lipopolysaccharide (LPS) in various organs including the heart. In this study we investigated the role of CD14 in LPS-induced myocardial dysfunction in vivo.

METHODS AND RESULTS

Wild-type and CD14-deficient (CD14-D) mice were challenged with Escherichia coli LPS. Myocardial tumor necrosis factor, interleukin-1beta (IL-1beta), and NOS2 induction was measured before and 6 hours after LPS challenge. Echocardiographic parameters of left ventricular function were measured before and 6 hours after LPS administration. LPS challenge induced a significant increase in myocardial tumor necrosis factor and IL-1beta mRNA and protein expression in wild-type mice. In contrast, mRNA and protein levels for TNF and IL-1beta were significantly blunted in CD14-D mice. An increase in NOS2 protein was noted within 6 hours of LPS provocation only in the hearts of wild-type mice. This was associated with an increase in ventricular cGMP levels. Activation of nuclear factor-kappaB was observed within 30 minutes of LPS in the hearts of wild-type mice but not in CD14-D mice. In wild-type mice, LPS significantly decreased left ventricular fractional shortening, velocity of circumferential shortening, and dP/dt(max). LPS-treated CD14-D mice maintained normal cardiac function.

CONCLUSIONS

These results suggest that CD14 is important in mediating the proinflammatory response induced by LPS in the heart and that CD14 is necessary for the development of left ventricular dysfunction during LPS-induced shock in vivo.

Myotrophin/V-1, a protein up-regulated in the failing human heart and in postnatal cerebellum, converts NFkappa B p50-p65 heterodimers to p50-p50 and p65-p65 homodimers

Myotrophin/V-1 is a cytosolic protein found at elevated levels in failing human hearts and in postnatal cerebellum. We have previously shown that it disrupts nuclear factor of kappaB (NFkappaB)-DNA complexes in vitro. In this study, we demonstrated that in HeLa cells native myotrophin/V-1 is predominantly present in the cytoplasm and translocates to the nucleus during sustained NFkappaB activation. Three-dimensional alignment studies indicate that myotrophin/V-1 resembles a truncated IkappaBalpha without the signal response domain (SRD) and PEST domains. Co-immunoprecipitation studies reveal that myotrophin/V-1 interacts with NFkappaB proteins in vitro; however, it remains physically associated only with p65 and c-Rel proteins in vivo during NFkappaB activation. In vitro studies indicate that myotrophin/V-1 can promote the formation of p50-p50 homodimers from monomeric p50 proteins and can convert the preformed p50-p65 heterodimers into p50-p50 and p65-p65 homodimers. Furthermore, adenovirus-mediated overexpression of myotrophin/V-1 resulted in elevated levels of both p50-p50 and p65-p65 homodimers exceeding the levels of p50-p65 heterodimers compared with Adbetagal-infected cells, where the levels of p50-p65 heterodimers exceeded the levels of p50-p50 and p65-p65 homodimers. Thus, overexpression of myotrophin/V-1 during NFkappaB activation resulted in a qualitative shift by quantitatively reducing the level of transactivating heterodimers while elevating the levels of repressive p50-p50 homodimers. Correspondingly, overexpression of myotrophin/V-1 resulted in significantly reduced kappaB-luciferase reporter activity. Because myotrophin/V-1 is found at elevated levels during NFkappaB activation in postnatal cerebellum and in failing human hearts, this study cumulatively suggests that myotrophin/V-1 is a regulatory protein for modulating the levels of activated NFkappaB dimers during this period.

Escherichia coli LPS-induced LV dysfunction: role of toll-like receptor-4 in the adult heart

The precise molecular mechanisms responsible for sepsis-induced myocardial dysfunction remain undefined. Toll-like receptor-4 (TLR-4) engages lipopolysaccharide (LPS) and activates signaling pathways leading to the expression of proinflammatory cytokines implicated in myocardial dysfunction. We determined whether TLR-4 was necessary for LPS-induced myocardial dysfunction in vivo. The effects of LPS on left ventricular (LV) function were studied in mice with defective TLR-4 signaling (C3H/HeJ, TLR-4 deficient) and wild-type mice (C3HeB/FeJ). Mice (n = 5/group) were injected with LPS or diluent, and LV function was examined by using two-dimensional echocardiography and conductance catheters. LPS significantly decreased all indexes of LV function in wild-type mice when compared with controls; LV function was not depressed in the LPS-treated TLR-4-deficient mice relative to controls. LPS increased myocardial nitric oxide synthase-2 expression and cGMP only in wild-type mice. This study suggests that TLR-4 mediates the LV dysfunction that occurs in LPS-induced shock. Therefore, TLR-4 might be a therapeutic target for attenuating the effects of LPS on the heart.

Load-dependent and -independent regulation of proinflammatory cytokine and cytokine receptor gene expression in the adult mammalian heart

BACKGROUND

Although previous studies have examined the effects of acute hemodynamic pressure overload on proinflammatory cytokine gene expression, the effects of sustained hemodynamic overloading have not been examined.

METHODS AND RESULTS

Sustained hemodynamic pressure overloading was produced in mice by transverse constriction of the aorta. Proinflammatory cytokine and cytokine receptor gene expression were determined by ribonuclease protection assays (RPA) at 6 hours and at 3, 7, 14 and 35 days after banding. M-mode echocardiography was used to assess left ventricular structure and function at identical time points. RPA showed that tumor necrosis factor (TNF), interleukin (IL)-1beta, and IL-6 mRNA levels were maximal at 6 hours and returned to baseline levels within 72 hours. There was a significant increase in IL-1RII and IL-6Ralpha receptor mRNA levels after overloading but no significant increase in TNFR1, TNFR2, IL-1RI, or gp130 mRNA levels. The transient increase in expression of proinflammatory cytokine gene expression was not explained by changes in left ventricular loading conditions, left ventricular wall stress, desensitization of proinflammatory genes, or decreased nuclear factor-kappaB activation. It is interesting that transverse constriction of the aorta provoked an increase in the expression of tristetraprolin, a homeostatic zinc finger protein that is known to destabilize TNF mRNA.

CONCLUSION

Sustained hemodynamic overloading provokes a transient increase in proinflammatory cytokine and cytokine receptor gene expression; however, the decrease in proinflammatory cytokine gene expression occurred in the absence of changes in loading conditions, suggesting that the expression of proinflammatory cytokines in the heart is regulated, at least in part, by load-dependent and load-independent mechanisms.