Cardiac inflammation and innate immunity in septic shock: is there a role for toll-like receptors?

Extracellular HSP70 facilitated β-glucan induced trained immunity in macrophages to suppress sepsis via TLR2-NF-κB axis

Sepsis is a common systemic infectious disease followed by extremely high incidence and mortality with no effective treatment and clinical drugs. As a key mediator involved in infection and immunity, it has been reported that sepsis patients are accompanied by increased heat shock protein 70 (HSP70). Trained immunity is a novel innate immunity approach that can be activated by β-glucan to fight against sepsis. The mechanism of HSP70 activating trained macrophages against sepsis needs further elucidation. Trained immunity and sepsis models were established by β-glucan and LPS individually both in vivo and in vitro. We demonstrated that HSP70 was significantly upregulated in septic mice serum, and HSP70 could protect mice from sepsis by activating β-glucan-trained macrophages as an ideal secondary inducer via TLR2-NF-κB pathway. Additionally, the sepsis resistant effects of HSP70 could be blocked by its antibody. In summary, more than a molecular chaperone to maintain homeostasis, HSP70 could be an important trained immunity inducer to help the body fighting against sepsis, which provided new stimuli for trained immunity and novel therapeutic solutions for sepsis.

β-Glucan-conjugated anti-PD-L1 antibody enhances antitumor efficacy in preclinical mouse models

The use of immune checkpoint blockade (ICB) is a promising approach for clinical cancer treatment. However, most of cancer patients do not respond to anti-PD-1/PD-L1 antibody. In this study, we proposed a novel strategy of antibody-β-glucan conjugates (AGC) to enhance the antitumor immune response to ICB therapy. The AGC were constructed by conjugating an anti-PD-L1 antibody with a β-glucan via click chemistry. This design facilitates the delivery of β-glucan into the tumor microenvironment (TME). Furthermore, the bridging effect mediated by AGC can promote the interaction between tumor cells and dendritic cells (DCs), thereby enhancing immunotherapeutic benefits. In the MC38 tumor-bearing mouse model, AGC demonstrated powerful tumor suppression, achieving a tumor suppression rate of 86.7 %. Immunophenotyping, cytokine analysis, RNA sequencing, and FTY720-treated models were combined to elucidate the mechanism underlying AGC function. Compared with anti-PD-L1 antibody, AGC induced an earlier immune response, infiltration of DCs, and activation of preexisting T cells in the TME, with T cells predominantly proliferating locally rather than migrating from other organs. In conclusion, these data suggest that AGC could serve as a promising strategy to improve ICB therapy with prospects for clinical utilization.

Role of toll-like receptor-mediated pyroptosis in sepsis-induced cardiomyopathy

Sepsis, a life-threatening dysregulated status of the host response to infection, can cause multiorgan dysfunction and mortality. Sepsis places a heavy burden on the cardiovascular system due to the pathological imbalance of hyperinflammation and immune suppression. Myocardial injury and cardiac dysfunction caused by the aberrant host responses to pathogens can lead to cardiomyopathy, one of the most critical complications of sepsis. However, many questions about the specific mechanisms and characteristics of this complication remain to be answered. The causes of sepsis-induced cardiac dysfunction include abnormal cardiac perfusion, myocardial inhibitory substances, autonomic dysfunction, mitochondrial dysfunction, and calcium homeostasis dysregulation. The fight between the host and pathogens acts as the trigger for sepsis-induced cardiomyopathy. Pyroptosis, a form of programmed cell death, plays a critical role in the progress of sepsis. Toll-like receptors (TLRs) act as pattern recognition receptors and participate in innate immune pathways that recognize damage-associated molecular patterns as well as pathogen-associated molecular patterns to mediate pyroptosis. Notably, pyroptosis is tightly associated with cardiac dysfunction in sepsis and septic shock. In line with these observations, induction of TLR-mediated pyroptosis may be a promising therapeutic approach to treat sepsis-induced cardiomyopathy. This review focuses on the potential roles of TLR-mediated pyroptosis in sepsis-induced cardiomyopathy, to shed light on this promising therapeutic approach, thus helping to prevent and control septic shock caused by cardiovascular disorders and improve the prognosis of sepsis patients.

Effect of Pulse Indicator Continuous Cardiac Output Monitoring on Septic Shock Patients: A Meta-Analysis

Background

Septic shock (SS) is the most common severe syndrome in the Intensive Care Unit (ICU). Enhancing the monitoring of hemodynamic indexes in SS patients carries huge clinical implications for reducing patient mortality. Recently, pulse indicator continuous cardiac output (PICCO) has been widely used in clinical practice, but its advantages than central venous pressure (CVP) in guiding the treatment of SS patients remains to be refined. Therefore, this study is aimed at assessing the clinical effects of PICCO in the treatment of patients with SS.

Methods

The authors systematically searched several databases (PubMed, EMBASE, Cochrane Library, and China National Knowledge) between January 2001 and February 2021. When searching for relevant articles, the authors combined the following phrases describing the monitoring group (“pulse indicator continuous cardiac output,” “central venous pressure”) with the disease of interest as well as management (“SS,” “sepsis”). The outcomes were independently assessed by two reviewers who scored the articles for methodological quality using the Cochrane Collaboration's “risk of bias” tool. Forest plots, as well as sensitivity and bias analyses, were carried out for the included articles. The primary outcome measures were length of ICU stay, duration of mechanical ventilation, 28-day mortality, and fluid resuscitation volume.

Results

Ten studies comprising 350 cases monitored with PICCO and 373 cases monitored with traditional CVP were eventually identified. PICCO-monitored patients were observed to be significantly associated with shorter ICU stay than CVP-monitored patients (MD: −3.04, 95% CI: −4.74 to −1.34, P = 0.0005), shorter time of mechanical ventilation (MD: −1.84, 95% CI: −2.80 to −0.87, P = 0.0002), and lower 28-day mortality (RR: 0.67, 95% CI: 0.48 to 0.94, P = 0.02). The two groups showed no significant difference in subgroup analysis for fluid resuscitation volumes (P > 0.05).

Conclusion

PICCO monitoring technique can significantly improve the prognosis of SS patients, shorten the time of mechanical ventilation and ICU stay, and reduce the 28-day mortality, which has positive guiding significance for patients with SS. Given the limitations of the quantity and quality of included studies, further research is warranted to verify the conclusions.

Targeting Toll-Like Receptors in Sepsis: From Bench to Clinical Trials

Significance: Sepsis is a critical clinical syndrome with life-threatening organ dysfunction induced by a dysregulated host response to infection. Despite decades of intensive research, sepsis remains a leading cause of in-hospital mortality with few specific treatments. Recent Advances: Toll-like receptors (TLRs) are a part of the innate immune system and play an important role in host defense against invading pathogens such as bacteria, virus, and fungi. Using a combination of genetically modified animal models and pharmacological agents, numerous preclinical studies during the past two decades have demonstrated that dysregulated TLR signaling may contribute to sepsis pathogenesis. However, many clinical trials targeting inflammation and innate immunity such as TLR4 have yielded mixed results. Critical Issues: Here we review various TLRs and the specific molecules these TLRs sense-both the pathogen-associated and host-derived stress molecules, and their converging signaling pathways. We critically analyze preclinical investigations into the role of TLRs in animal sepsis, the complexity of targeting TLRs for sepsis intervention, and the disappointing clinical trials of the TLR4 antagonist eritoran. Future Directions: Future sepsis treatments will depend on better understanding the complex biological mechanisms of sepsis pathogenesis, the high heterogeneity of septic humans as defined by clinical presentations and unique immunological biomarkers, and improved stratifications for targeted interventions.

Immune Modulating Antibody-Drug Conjugate (IM-ADC) for Cancer Immunotherapy

Antibody-drug conjugate (ADC) and immune checkpoint blockade (ICB) offer promising approaches for cancer treatment. Here, we describe an ADC constructed by conjugating anti-PD-L1 THIOMAB with a bifunctional immunomodulator D18 via a redox-cleavable linker. The resulting ADC HE-S2 not only triggers a potent antitumor immune response by blocking the PD-1/PD-L1 interaction and activating the Toll-like receptor 7/8 (TLR7/8) signaling pathway but also upregulates its targeted PD-L1 expression via epigenetic regulation and/or IFN-γ induction, thus conferring more sensitivity to the PD-1/PD-L1 blockade. We identify that ADC HE-S2 treatment could lead to more pronounced tumor suppression than the treatment of D18 in combination with the anti-PD-L1 antibody. Accordingly, this study provides a novel ADC strategy to enhance the antitumor immune response to ICB therapy.

The effect of lysophosphatidic acid on Toll-like receptor 4 expression and the nuclear factor-κB signaling pathway in THP-1 cells

Toll-like receptors (TLRs) are major receptors that mediate the innate immune and inflammatory responses, of which TLR4 has been found most closely related to human atherosclerosis. After ligands are polymerized and activated by TLR, the mitogen-activated protein kinase and nuclear factor-κB (NF-κB) pathways are activated, leading to promotion of NF-κB-regulated transcription of inflammatory factors, thus playing a role in the physiological and pathological processes in atherosclerosis. Oxidized lipoproteins or their components, oxidized lipids, have been confirmed as endogenous TLR receptors. Lysophosphatidic acid (LPA) is an active component of low-density lipoprotein that induces vascular endothelial lesions. However, the mechanism of the TLR4/NF-κB signaling system involved in LPA-induced atherosclerosis has not been fully elucidated. In this study, we investigated the effects of LPA on TLR4 expression, nuclear translocation of NF-κB p65 subunit, and changes in the cytokine tumor necrosis factor α (TNF-α) in human THP-1 cells. LPA upregulated expression of the TLR4 mRNA and protein in THP-1 cells in a dose- and time-dependent manner, induced NF-κB p65 activation synchronously in THP-1 cells, and increased TNF-α secretion. After TLR4 was blocked using TLR4 monoclonal antibody, NF-κB p65 expression and TNF-α secretion were inhibited significantly. These data suggest that LPA can significantly upregulate TLR4 expression and promote NF-κB activation and proinflammatory cytokine secretion in THP-1 cells; it is possible that the TLR4/NF-κB signaling pathway mediates the atherogenic effect of LPA.

Sitagliptin attenuates inflammatory responses in lipopolysaccharide-stimulated cardiomyocytes via nuclear factor-κB pathway inhibition

Glucagon-like peptide-1 (GLP-1) and GLP-1 receptors (GLP-1Rs) are responsible for glucose homeostasis, and have been shown to reduce inflammation in preclinical studies. The aim of the present study was to determine whether sitagliptin, an inhibitor of the enzyme dipeptidyl peptidase-4 (DPP-4), as a GLP-1 receptor agonist, exerts an anti-inflammatory effect on cardiomyoblasts during lipopolysaccharide (LPS) stimulation. Exposure to LPS increased the expression levels of tumor necrosis factor (TNF)-α, interleukin-6 (IL)-6 and IL-1β in H9c2 cells, and also resulted in elevations in cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression and nuclear factor-κB (NF-κB) nuclear translocation. Treatment with the DPP-4 inhibitor sitagliptin dose-dependently downregulated the mRNA levels of IL-6, COX-2 and iNOS in LPS-stimulated H9c2 cells. In addition, sitagliptin inhibited the increased protein expression of IL-6, TNF-α and IL-1β. NF-κB mRNA expression was reduced and its translocation to the nucleus was suppressed by treatment with sitagliptin. The present results demonstrated that sitagliptin exerts a beneficial effect on cardiomyoblasts exposed to LPS by inhibiting expression of inflammatory mediators and suppressing NF-κB activation. These findings indicate that the DPP-4 inhibitor sitagliptin may serve a function in cardiac remodeling attributed to sepsis-induced inflammation.

Synthesis and Evaluation of Conjugates of Novel TLR7 Inert Ligands as Self-Adjuvanting Immunopotentiators

During the design and synthesis of a series of 8-hydroxy-2-(2-methoxyethoxy)-adenine derivatives bearing various substituted -RCOOH groups at the 9-position, we identified a TLR7-inert ligand, which does not activate TLR7 signaling pathway. Of interest, the coupling of weakly immunogenic antigens via the -RCOOH group was able to significantly enhance the immunogenicity of the antigens. Herein, an inert ligand, 9-(3-carboxypropyl)-8-hydroxy-2-(2-methoxyethoxy)-adenine (5, GD2), was synthesized and conjugated to 5 different weakly immunogenic antigens (BSA, OVA, MSA, MG7, and thymosin). Compared with the GD2 and the potent agonist UC-1 V150, all conjugates demonstrated potent immunogenicity in vitro and in vivo. All conjugates induced prolonged increases, while UC-1 V150 showed a rapid decline in the levels of proinflammatory cytokines following initial increases. These data indicate that the immunostimulatory activity of TLR7-inert ligands could be amplified and prolonged by conjugation to antigens, thus broadening the potential therapeutic application of these agents.

Synthesis and immunoregulatory activities of conjugates of a Toll-like receptor 7 inert ligand

In the synthesis and modification of the analogs of an adenine type of Toll-like receptor (TLR) 7 agonists, we found a special compound, 9-propionyloxy-8-hydroxy-2-(2-methoxyethoxy)-adenine (6). It is a synthesized TLR7 inert ligand, which does not respond to TLR7 itself. However, it can be coupled with protein or peptide antigens via propionyloxy functional group to promote their immunogenicity significantly. The compound was covalently coupled to protein and peptide to get the conjugates. The inductivity of cytokine production by the conjugates was 872.4-fold compared with the unconjugated antigens in vitro by mouse splenocyte. These data show that the immunostimulatory activity of inert TLR7 ligand can be endowed, and the activity of antigens can be amplified by conjugation with various proteins and peptides, thus broadening the potential therapeutic application and reducing the risk of TLR7 agonists' side effects.

Association between Toll-like receptor 4 and interleukin 17 gene polymorphisms and colorectal cancer susceptibility in Northeast China

Limited studies about the effects of TLR 4 and IL17 polymorphisms (SNPs) on the risk of colorectal cancer (CRC) have yielded inconsistent results. Totally, 601 CRC patients and 627 controls were enrolled. Unconditional logistic regression was used to estimate the association between tagSNPs and susceptibility of CRC and the interactions effects of gene and environment on the risk of CRC. IL17 rs6973569 AG and AG/AA genotypes significantly decreased the risk of CRC compared with GG genotype (ORadjusted=0.72, 95% CI 0.55-0.94 and ORadjusted=0.74, 95 % CI 0.57-0.97). The haplotype G-T-G-C-A-G accounting for the largest proportion haplotypes increased the risk of CRC (OR=1.27, 95 % CI 1.06-1.53). However, G-C-C-T-A-G and G-C-G-C-A-G haplotypes decreased the susceptibility of CRC. Synergistic interactions between TLR 4 rs1927911 CT/TT and higher pungent food intake as well as IL17 rs6973569 AG/AA genotypes and higher intake of sausage food (ORi=1.72, 95% CI 1.04-2.84 and ORi=3.38, 95% CI 1.28-8.91) on the risk of CRC were observed. IL17 rs6973569 SNP might be an independent factor of susceptibility to CRC. TLR 4 haplotype of G-T-G-C-A-G may increase risk of CRC. Higher intake of pungent and sausage food synergistically interacted with TLR 4 and IL17 SNPs on the risk of CRC.

The differential diagnostic value of serum NT-proBNP in hospitalized patients of heart failure with pneumonia

Serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) is considered as an effective predictor for patients with heart failure (HF), while a strong body of evidence has found its utility in inflammatory diseases. It is difficult to differentiate HF and HF coexisting with other inflammations by measuring NT-proBNP. The aim of this study was to estimate the differential diagnostic performance of serum NT-proBNP in hospitalized HF patients with pneumonia. A prospective study was launched. Sixty nine HF patients, 51 HF patients complicated with pneumonia, and 38 patients with pneumonia were enrolled. Serum NT-proBNP levels were measured on Roche Elecsys. X-ray and the European Society of Cardiology (ESC) diagnostic principles were adopted to identify patients with pneumonia and HF, respectively. The diagnostic performance of NT-proBNP was assessed by ROC. Serum NT-proBNP [7,039(1,008-24,672) pg/ml] in patients of HF complicated with pneumonia was significantly higher than that in those of patients with single HF [3,147(616-24,062) pg/ml] or single pneumonia [911(98-3,812) pg/ml] (P < 0.0001). No correlation was found between the level of NT-proBNP and hospital stay. The area under ROC curve (AUC) of NT-proBNP for distinguishing patients of HF with pneumonia was 0.8082. At the level of 4,691 pg/ml, the optimal cutoff value, 74.5% sensitivity and 81.8% specificity of NT-proBNP were predicted. Evaluation of serum NT-proBNP is conducive for clinicians to identify patients of HF with pneumonia, but its poor efficacy in monitoring the curative therapy in this entire cohort is not recommended.

Toll-like receptor 9 promotes cardiac inflammation and heart failure during polymicrobial sepsis

Background. Aim was to elucidate the role of toll-like receptor 9 (TLR9) in cardiac inflammation and septic heart failure in a murine model of polymicrobial sepsis. Methods. Sepsis was induced via colon ascendens stent peritonitis (CASP) in C57BL/6 wild-type (WT) and TLR9-deficient (TLR9-D) mice. Bacterial load in the peritoneal cavity and cardiac expression of inflammatory mediators were determined at 6, 12, 18, 24, and 36 h. Eighteen hours after CASP cardiac function was monitored in vivo. Sarcomere length of isolated cardiomyocytes was measured at 0.5 to 10 Hz after incubation with heat-inactivated bacteria. Results. CASP led to continuous release of bacteria into the peritoneal cavity, an increase of cytokines, and differential regulation of receptors of innate immunity in the heart. Eighteen hours after CASP WT mice developed septic heart failure characterised by reduction of end-systolic pressure, stroke volume, cardiac output, and parameters of contractility. This coincided with reduced cardiomyocyte sarcomere shortening. TLR9 deficiency resulted in significant reduction of cardiac inflammation and a sustained heart function. This was consistent with reduced mortality in TLR9-D compared to WT mice. Conclusions. In polymicrobial sepsis TLR9 signalling is pivotal to cardiac inflammation and septic heart failure.

Toll-like receptor (TLR) 2 and TLR4 differentially regulate doxorubicin induced cardiomyopathy in mice

Recent evidence indicates that toll-like receptor (TLR) 2 and 4 are involved in the pathogenesis of dilated cardiomyopathy (DCM), but the exact mechanisms of their actions have not been elucidated. We explored the therapeutic potential of blocking TLRs in mice with established cardiomyopathy. Cardiomyopathy was generated by a single intraperitoneal injection of doxorubicin (10 mg/kg). Two weeks later, the mice were treated with TLR2 or TLR4 neutralizing antibody. Blocking TLR2, but not TLR4, activity not only reduced mortality, but also attenuated doxorubicin-induced cardiac dysfunction by 20% and inhibited myocardial fibrosis. To determine the differential effects of blocking TLR2 and TLR4 in chronic cardiomyopathy, mice were injected with doxorubicin (3.5 mg/kg) once a week for 8 weeks, followed by treatment with TLR2 or TLR4 neutralizing antibody for 40 days. Blocking TLR2 activity blunted cardiac dysfunction by 13% and inhibited cardiac fibrosis, which was associated with a significant suppression of myocardial inflammation. The underlying mechanism involved interrupting the interaction of TLR2 with its endogenous ligands, resulting in attenuation of inflammation and fibrosis. In contrast, blocking TLR4 exacerbated cardiac dysfunction and fibrosis by amplifying inflammation and suppressing autophagy. Our studies demonstrate that TLR2 and TLR4 play distinct roles in the progression of doxorubicin-induced DCM. TLR4 activity is crucial for the resolution of inflammation and cardiac fibrosis, while blocking TLR2 activity has therapeutic potential for the treatment of DCM.

Toll-like receptors and myocardial inflammation

Toll-like receptors (TLRs) are a member of the innate immune system. TLRs detect invading pathogens through the pathogen-associated molecular patterns (PAMPs) recognition and play an essential role in the host defense. TLRs can also sense a large number of endogenous molecules with the damage-associated molecular patterns (DAMPs) that are produced under various injurious conditions. Animal studies of the last decade have demonstrated that TLR signaling contributes to the pathogenesis of the critical cardiac conditions, where myocardial inflammation plays a prominent role, such as ischemic myocardial injury, myocarditis, and septic cardiomyopathy. This paper reviews the animal data on (1) TLRs, TLR ligands, and the signal transduction system and (2) the important role of TLR signaling in these critical cardiac conditions.

Toll-like receptor 4 signaling confers cardiac protection against ischemic injury via inducible nitric oxide synthase- and soluble guanylate cyclase-dependent mechanisms

BACKGROUND

Prior administration of a small dose of lipopolysaccharide confers a cardiac protection against ischemia-reperfusion injury. However, the signaling mechanisms that control the protection are incompletely understood. We tested the hypothesis that Toll-like receptor 4 (TLR4) mediates the ability of lipopolysaccharide to protect against cardiac ischemia-reperfusion injury through distinct intracellular pathways involving myeloid differentiation factor 88 (MyD88), TIR-domain-containing adaptor protein-inducing interferon-β-mediated transcription factor (Trif), inducible nitric oxide synthase (iNOS), and soluble guanylate cyclase (sGC).

METHODS

Wild-type mice and genetically modified mice, that is TLR4-deficient (TLR4(-def)), TLR2 knockout (TLR2(-/-)), MyD88(-/-), Trif(-/-), iNOS(-/-), and sGCα1(-/-), were treated with normal saline or 0.1 mg/kg lipopolysaccharide intraperitoneally. Twenty-four hours later, isolated hearts were perfused in a Langendorff apparatus and subsequently subjected to 30 min global ischemia and reperfusion for as long as 60 min. Left ventricular function and myocardial infarction sizes were examined.

RESULTS

Compared with saline-treated mice, lipopolysaccharide-treated mice had markedly improved left ventricular developed pressure and dP/dt(max) (P < 0.01) and reduced myocardial infarction sizes (37.2 ± 3.4% vs. 19.8 ± 4.9%, P < 0.01) after ischemia-reperfusion. The cardiac protective effect of lipopolysaccharide was abolished in the TLR4(-def) and MyD88(-/-) mice but remained intact in TLR2(-/-) or Trif(-/-) mice. iNOS(-/-) mice or wild-type mice treated with the iNOS inhibitor 1400W failed to respond to the TLR4-induced nitric oxide production and were not protected by the lipopolysaccharide preconditioning. Although sGCα(1)(-/-) mice had robust nitric oxide production in response to lipopolysaccharide, they were not protected by the TLR4-elicited cardiac protection.

CONCLUSIONS

TLR4 activation confers a potent cardiac protection against ischemia-reperfusion injury via a MyD88-dependent, but Trif-independent, mechanism. iNOS/sGC are essential for the TLR4-induced cardiac protection.

TNFα in myocardial ischemia/reperfusion, remodeling and heart failure

TNFα is crucially involved in the pathogenesis and progression of myocardial ischemia/reperfusion injury and heart failure. The formation and release of TNFα and its downstream signal transduction cascade following activation of its two receptor subtypes are characterized. Myocardial TNFα and TNF receptor activation have an ambivalent role in myocardial ischemia/reperfusion injury and protection from it. Excessive TNFα expression and subsequent cardiomyocyte TNF receptor type 1 stimulation induce contractile dysfunction, hypertrophy, fibrosis and cell death, while a lower TNFα concentration and subsequent cardiomyocyte TNF receptor type 2 stimulation are protective. Apart from its concentration and receptor subtype, the myocardial action of TNFα depends on the duration of its exposure and its localization. While detrimental during sustained ischemia, TNFα contributes to ischemic preconditioning protection, no matter whether it is the first, second or third window of protection, and both TNF receptors are involved in the protective signal transduction cascade. Finally, the available clinical attempts to antagonize TNFα in cardiovascular disease, notably heart failure, are critically discussed.

[Effects of Chinese herbal medicine Dusuqing Granule on toll-like receptor 4 signaling in multiple organ injury induced by bacterial pneumonia in aged rats]

OBJECTIVE

To study the protective mechanism of Dusuqing Granule, a compound Chinese herbal medicine, on the senile multiple organ injury caused by bacterial pneumonia by observing the expression changes of molecules related to toll-like receptor 4 (TLR4) signaling.

METHODS

A total of 55 male Sprague-Dawley aged rats were divided into control group, untreated group, Dusuqing group and lomefloxacin group. There were 25 rats in the untreated group and 10 rats in each of the other three groups. Multiple organ injury in a rat model of pneumonia was induced by injection of Klebsiella pneumoniae through tracheal intubation. By means of immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR), examinations were made on mRNA expressions of lipopolysaccharide-binding protein (LBP), CD14, TLR4 and interleukin-1 receptor-associated kinase-1 (IRAK-1) in the tissues of the lung, heart and small intestine, and also on the protein expressions of TLR4, tumor necrosis factor receptor-associated factor 6 (TRAF6) and nuclear factor-κB (NF-κB).

RESULTS

Expressions of LBP, CD14, TLR4 and IRAK-1 mRNAs in the tissues of the lung, heart and small intestine in the untreated group were stronger than those in the control group (P<0.01 or Plt;0.05). The protein expressions of TLR4, TRAF6 and NF-κB were increased dramatically in the untreated group as compared with the control group (Plt;0.01 or Plt;0.05). Compared with the untreated group, the expressions of LBP, CD14, TLR4 and IRAK-1 mRNAs in the tissues of the lung, heart and small intestine in the Dusuqing group were weakened significantly (Plt;0.01 or Plt;0.05). Meanwhile, the protein expressions of TLR4, TRAF6 and NF-κB were decreased markedly in the Dusuqing group (Plt;0.01 or Plt;0.05).

CONCLUSION

Dusuqing Granule is effective in suppressing toll-like receptor signal transduction activation and reducing the secretion of cytokines and inflammatory mediators, which can further reduce the organ tissue injury. Dusuqing Granule can decrease the levels of TLR signal transduction activation including the targets LBP, CD-14, TLR4, IRAK-1, TRAF6 and NF-κB, which is different from the special inhibitor that acts only on some segments.

Genetic predisposition to Helicobacter pylori-induced gastric precancerous conditions

Gastric cancer is the most common malignancy of the gastrointestinal tract in East Asian populations and the second most frequent cause of cancer-related mortality in the world. While previous studies have investigated the genetic factors involved in gastric carcinogenesis, there still exist relatively few studies that have investigated the genetic traits associated with the risk of gastric precancerous conditions. In this paper we will review the biology and genetic polymorphisms involved in the genesis of gastric precancerous conditions reported to date and discuss the future prospects of this field of study. The associations of gastric precancerous conditions with polymorphisms in the cytotoxin-associated gene A-related genes (e.g. PTPN11 G/A at intron 3, rs2301756), those in the genes involved in host immunity against Helicobacter pylori (H. pylori) infection (e.g. TLR4 +3725G/C, rs11536889) or polymorphisms of the genes essential for the development/ differentiation of the gastric epithelial cells (e.g. RUNX3 T/A polymorphism at intron 3, rs760805) have been reported to date. Genetic epidemiological studies of the associations between H. pylori-induced gastric precancerous conditions and other gene polymorphisms in these pathways as well as polymorphisms of the genes involved in other pathways like oxidative DNA damage repair pathways would provide useful evidence for the individualized prevention of these H. pylori-induced gastric precancerous conditions.

Genetic traits for the persistence of Helicobacter pylori infection

Helicobacter pylori infection elevates the risk of gastric diseases, including peptic ulcer and gastric cancer. Persistent infection is the first step to induce H. pylori-induced multistage diseases. Although the roles of genetic traits on persistent infection have not yet been elucidated, some individuals escape from persistent infection. Possible favorable conditions for H. pylori seem to be low acid secretion, reduced innate immune responses, and easier binding to gastric epithelial cells. IL-1β and TNF-α inhibit acid secretion. The genetic polymorphisms associated with both molecules have the potential to be the genetic traits underlying persistent infection. Functional polymorphisms associated with innate immune responses could also be involved with the genetic traits, but no polymorphisms with consistent associations have been identified so far. The polymorphisms associated with molecules for adhesion to epithelial cells are candidates of genetic traits, but more research is needed.

Molecular or pharmacologic inhibition of the CD14 signaling pathway protects against burn-related myocardial inflammation and dysfunction

Signaling through toll-like receptor 4 (TLR4) plays an obligate role in burn-related myocardial dysfunction. We hypothesized that signaling through CD14, a cellular receptor for endotoxin that lacks a transmembrane domain but is coupled to TLR4, also plays a role in postburn myocardial inflammation and dysfunction. Burn covering 40% total body surface area (or sham burn for controls) was produced in wild-type (WT) and CD14 knockout (KO) as well as vehicle-treated and geldanamycin-treated WT mice (1 microg/g body weight) to inhibit CD14 signaling. Groups included (1) WT shams, (2) CD14 KO sham, (3) WT burns, (4) CD14 KO burns, (5) vehicle-treated WT shams, (6) geldanamycin-treated WT shams, (7) vehicle-treated WT burns, and (8) geldanamycin-treated WT burns. Twenty-four hours after burn, cardiac function (Langendorff) and cardiomyocyte secretion of inflammatory cytokines TNF-alpha, IL-1 beta, and IL-6 (in pg/mL; 5 x 10(4) myocytes) were studied in all groups. Relative to sham WT controls, burn trauma in increased cardiac myocyte secretion of inflammatory cytokines (TNF-alpha, IL-1 beta, and IL-6 rose from 59 +/- 10 to 171 +/- 8; 6 +/- 0.2 to 78 +/- 1; and 88 +/- 3 to 170 +/- 12 pg/mL, respectively; P < 0.05) and produced robust cardiac contractile dysfunction (left ventricular pressure and +dP/dt fell from 105 +/- 4 to 73 +/- 5 mmHg and 2,400 +/- 73 to 1,803 +/- 90 mmHg/s; P < 0.05). Inability to signal through the CD14/TLR4 pathway (induced by CD14/KO or inhibition of CD14 expression by administration of geldanamycin) attenuated TNF-alpha, IL-1 beta, and IL-6 production in response to burn injury and improved postburn myocardial contractile function. Our data suggest that signaling through the CD14 pathway plays an obligate role in cardiac inflammation/dysfunction which occurs after major burn injury.

Transgenic zebrafish reporter lines reveal conserved Toll-like receptor signaling potential in embryonic myeloid leukocytes and adult immune cell lineages

The immune response of a host to an invading pathogen is dependent on the capacity of its immune cell compartment to recognize highly conserved pathogen components using an ancient class of pattern recognition receptors known as Toll-like receptors (TLRs). Initiation of TLR-mediated signaling results in the induction of proinflammatory cytokines that help govern the scale and duration of any ensuing response. Specificity for TLR signaling is, in part, a result of the differential recruitment of intracellular adaptor molecules. Of these, MyD88 is required for the majority of TLR signaling. Zebrafish have been shown to possess TLRs and adaptor molecules throughout early development, including MyD88, strongly suggesting conservation of this ancient defense mechanism. However, information about which embryonic cells/tissues possess this conserved signaling potential is lacking. To help define which embryonic cells, in particular, those of the innate immune system, have the potential for MyD88-dependent, TLR-mediated signaling, we generated transgenic reporter lines using regulatory elements of the myd88 gene to drive the fluorescent reporters enhanced GFP and Discosoma red fluorescent protein 2 within live zebrafish. These lines possess fluorescently marked cells/tissues consistent with endogenous myd88 expression, including a subset of myeloid leukocytes. These innate immune cells were confirmed to express other TLR adaptors including Mal, trif, and Sarm. Live wound-healing and infection assays validated the potential of these myd88-expressing leukocytes to participate in immune responses. These lines will provide a valuable resource for further resolving the contribution of MyD88 to early vertebrate immunity.

Altered pharmacology in the Intensive Care Unit patient

Critically ill patients, not infrequently present alterations of physiological parameters that determine the success/failure of therapeutic interventions as well as the final outcome. Sepsis and polytrauma are two of the most common and complex syndromes occurring in Intensive Care Unit (ICU) and affect drug absorption, disposition, metabolism and elimination. Pharmacological management of ICU patients requires consideration of the unique pharmacokinetics associated with these clinical conditions and the likely occurrence of drug interaction. Rational adjustment in drug choice and dosing contributes to the appropriateness of treatment of those patients.

Targeting TRAFs for Therapeutic Intervention

TNF-receptor associated factors (TRAFs) are the molecules that upon engagement of the TNF-receptor (TNFR) by a TNF-family ligand come first in contact with the activated TNFR, initially acting as docking molecules for kinases and other effector proteins that are recruited to the activated receptor. TRAFs later regulate the subcellular relocalization of the receptor-ligand complex and finally they modulate the extent of the response by controlling the degradation of key proteins in the pathway. In this chapter, we review the involvement of different TRAF family members in the etiology of a variety of pathologies and address the question of whether the use of TNFR-mimic-peptides or small molecule modulators targeting TRAFs might be suitable for therapeutic intervention, discussing the advantages and disadvantages of this strategy.

Selective impairment of nuclear factor-kappaB-dependent gene transcription in adult cardiomyocytes: relevance for the regulation of the inflammatory response in the heart

The ability of neonatal and adult cardiomyocytes to activate the nuclear factor (NF)-kappaB pathway in response to lipopolysaccharide and interleukin-1beta challenge has been investigated and compared with that of peritoneal macrophages. The activation of the IkappaB kinase and the phosphorylation and degradation of IkappaBalpha and IkappaBbeta was much lower in adult cardiomyocytes than in the neonatal counterparts and macrophages. This restricted activation of the NF-kappaB pathway resulted in a significant reduction in the time of nuclear activation of NF-kappaB, as deduced by electrophoretic mobility shift assays and in the transcription of target genes, such as IkappaBalpha, cyclooxygenase-2 (COX-2) and nitric-oxide synthase-2 (NOS-2). Studies on chromatin immunoprecipitation showed binding of NF-kappaB proteins to the regulatory kappaB sites identified in the promoters of the IkappaBalpha, COX-2, and NOS-2 genes in macrophages and, to a lower extent, in neonatal cardiomyocytes. The binding to these kappaB sites in adult cardiomyocytes was observed only in the IkappaBalpha promoter and was minimal or absent in the COX-2 and NOS-2 promoters, respectively, suggesting a restricted activation of NF-kappaB-regulated genes in these cells. These data indicate that the function of the NF-kappaB pathway in adult cardiomyocytes is limited in time, which results in the expression of a reduced number of genes and provides a functional explanation for the absence of NOS-2 inducibility in these cells under proinflammatory conditions.

Toll-like receptor 4 deficiency: smaller infarcts, but no gain in function

Backgound

It has been reported that Toll-like receptor 4 (TLR4) deficiency reduces infarct size after myocardial ischemia/reperfusion (MI/R). However, measurement of MI/R injury was limited and did not include cardiac function. In a chronic closed-chest model we assessed whether cardiac function is preserved in TLR4-deficient mice (C3H/HeJ) following MI/R, and whether myocardial and systemic cytokine expression differed compared to wild type (WT).

Results

Infarct size (IS) in C3H/HeJ assessed by TTC staining after 60 min ischemia and 24h reperfusion was significantly smaller than in WT. Despite a smaller infarct size, echocardiography showed no functional difference between C3H/HeJ and WT. Left-ventricular developed pressure measured with a left-ventricular catheter was lower in C3H/HeJ (63.0 ± 4.2 mmHg vs. 77.9 ± 1.7 mmHg in WT, p < 0.05). Serum cytokine levels and myocardial IL-6 were higher in WT than in C3H/HeJ (p < 0.05). C3H/HeJ MI/R showed increased myocardial IL-1β and IL-6 expression compared to their respective shams (p < 0.05), indicating TLR4-independent cytokine activation due to MI/R.

Conclusion

These results demonstrate that, although a mutant TLR4 signaling cascade reduces myocardial IS and serum cytokine levels, it does not preserve myocardial function. The change in inflammatory response, secondary to a non-functional TLR-4 receptor, may contribute to the observed dichotomy between infarct size and function in the TLR-4 mutant mouse.

Immunotherapeutic activity of a conjugate of a Toll-like receptor 7 ligand

The immunotherapeutic activity of Toll-like receptor (TLR) activators has been difficult to exploit because of side effects related to the release and systemic dispersion of proinflammatory cytokines. To overcome this barrier, we have synthesized a versatile TLR7 agonist, 4-[6-amino-8-hydroxy-2-(2-methoxyethoxy)purin-9-ylmethyl]benzaldehyde (UC-1V150), bearing a free aldehyde that could be coupled to many different auxiliary chemical entities through a linker molecule with a hydrazine or amino group without any loss of activity. UC-1V150 was covalently coupled to mouse serum albumin (MSA) at a 5:1 molar ratio to yield a stable molecule with a characteristically altered UV spectrum. Compared with the unconjugated TLR7 agonist, the UC-1V150/MSA was a 10- to 100-fold more potent inducer of cytokine production in vitro by mouse bone marrow-derived macrophage and human peripheral blood mononuclear cells. When administrated to the lung, the conjugate induced a prolonged local release of cytokines at levels 10-fold or more higher than those found in serum. Under the same conditions, the untethered TLR7 ligand induced quick systemic cytokine release with resultant toxicity. In addition, two pulmonary infectious disease models were investigated wherein mice were pretreated with the conjugate and then challenged with either Bacillus anthracis spores or H1N1 influenza A virus. Significant delay in mortality was observed in both disease models with UC-1V150/MSA-pretreated mice, indicating the potential usefulness of the conjugate as a localized and targeted immunotherapeutic agent.

Recruitment of functionally active heart beta2-adrenoceptors in the initial phase of endotoxic shock in pithed rats

A supersensitivity of the beta-adrenoceptor-mediated chronotropic response has been demonstrated in atria isolated from rats subjected to septic shock. Our study was undertaken to investigate whether bacterial endotoxin/LPS affects the increase in heart rate induced by beta-adrenoceptor agonists in the rat also in vivo. In pithed and vagotomized rats, the nonselective beta-adrenoceptor agonist isoprenaline (0.05-0.15 nmol/kg) and agonists at the high- and low-affinity state of beta1-adrenoceptors, that is, prenalterol (0.3-3 nmol/kg) and (+/-)-4-[3-[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,3-dihydro-2H-benzimidazole-2-one (CGP 12177; 3-6 nmol/kg), respectively, and at beta2-adrenoceptors, that is, fenoterol (1-5 nmol/kg), increased heart rate by 50 to 60 beats/min. Administration of LPS (0.4, 1, and 1.5 mg/kg), under continuous infusion of vasopressin, dose-dependently amplified the chronotropic response to isoprenaline, prenalterol, and fenoterol (by 80%, 50%, and 100%, respectively) but not to CGP 12177. The beta2-adrenoceptor antagonist erythro-(+/-)-1-(7-methylindan-4-yloxy)-3-isopropylaminobutan-2-ol (ICI 118551 0.1 mumol/kg) did not affect the chronotropic responses of isoprenaline, fenoterol, and prenalterol under non-endotoxic conditions, but abolished the potentiation of tachycardia produced by LPS (1.5 mg/kg). The beta1-adrenoceptor antagonist (+/-)-2-hydroxy-5-[2-[[2-hydroxy-3-[4-[1-methyl-4-(trifluoromethyl)-1H-imidazol-2-yl]-phenoxy]propyl]-amino]ethoxy]-benzamide CGP 20712A; 0.1 mumol/kg almost completely reduced the chronotropic effects of isoprenaline, fenoterol, and prenalterol both in control rats and in animals exposed to LPS (1.5 mg/kg). We conclude that LPS sensitizes cardiac beta-adrenoceptors by recruiting functionally active beta2-adrenoceptors, but the amplification of tachycardia occurs only when both beta1- and beta2-adrenoceptors are concomitantly activated. The pithed rat may serve as a model to examine the beta-adrenoceptor supersensitivity in vivo.

Mannose binding lectin and soluble Toll-like receptor 2 in heart failure following acute myocardial infarction

BACKGROUND

To determine the relationship between markers of innate immunity and clinical outcomes in patients with heart failure (HF) after acute myocardial infarction (AMI). Atherogenesis and HF is associated with the altered control of inflammation by innate immune defenses that include pattern-recognition molecules such as Toll-like receptors (TLRs) and mannose-binding lectin (MBL).

METHODS AND RESULTS

We assessed circulating levels, and relationships with adverse outcomes of MBL and sTLR2 levels in 234 patients with AMI complicated with HF. Blood was sampled at baseline (median 3 days after AMI), 1 month, 1 year, and 2 years. For comparison, we also measured MBL and sTLR2 levels in 20 age- and sex-matched healthy controls. Patients with post-MI HF had markedly decreased serum levels of sTLR2 at baseline that increased during follow-up, but did not reach the concentrations present in healthy controls. In contrast, serum MBL levels were initially normal in patients with post-MI HF, but decreased during follow-up, and MBL levels measured 1 month after the index infarct were inversely associated with a higher incidence of reinfarction.

CONCLUSION

These findings suggest that circulating levels of MBL and sTLR2 may reflect different aspects of the innate immune response and further suggest the involvement of innate immunity responses in the pathogenesis of post-MI HF.

Genetic factors involved in the development of Helicobacter pylori-related gastric cancer

Developmental process to gastric cancer by Helicobacter pylori infection consists of three steps: (1) H. pylori infection; (2) gastric atrophy development; and (3) carcinogenesis. In each step, genetic traits may influence the process, interacting with lifestyle. In the step of H. pylori infection, two lines of genetic polymorphisms were assumed: one influencing gastric acid inhibition interacting with smoking, and the other concerning innate immune response attenuation. The former includes functional polymorphisms of IL-1B (C-31T or tightly linked T-511C), and TNF-A (T-1031C and C-857T), and the latter possibly includes NQO1 C609T. In the step to gastric atrophy, polymorphisms pertaining to the signal transduction from cytotoxin-associated gene A (PTPN11 A/G at intron 3) and to T-cell responses (IL-2 T-330G and IL-13 C-1111T) were hypothesized. There are a limited number of epidemiological genotype studies on the final step of literal carcinogenesis, potentially interacting with smoking, a low vegetable and fruit intake, and salty foods, the well-documented risk factors. In past case-control studies on the associations between genotype and gastric cancer risk, the cases consisted of H. pylori-related and unrelated gastric cancer patients and the controls consisted of individuals including the uninfected (H. pylori unexposed and exposed) and the infected with and without gastric atrophy. Accordingly, it was not clear whether the observed risk was for H. pylori-related or -unrelated gastric cancer, nor which step was involved in the observed associations even when nearly all cases were H. pylori-related. In order to elucidate the genetic traits of H. pylori-related gastric cancer, stepwise evaluation will be required.

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.

Pivotal role of gp91phox-containing NADH oxidase in lipopolysaccharide-induced tumor necrosis factor-alpha expression and myocardial depression

BACKGROUND

Lipopolysaccharide (LPS) induces cardiomyocyte tumor necrosis factor-alpha (TNF-alpha) production, which is responsible for myocardial depression during sepsis. The aim of this study was to investigate the role of gp91phox-containing NADH oxidase signaling in cardiomyocyte TNF-alpha expression and myocardial dysfunction induced by LPS.

METHODS AND RESULTS

In cultured mouse neonatal cardiomyocytes, LPS increased NADH oxidase (gp91phox subunit) expression and superoxide generation. Deficiency of gp91phox or inhibition of NADH oxidase blocked TNF-alpha expression stimulated by LPS. TNF-alpha induction was also inhibited by tempol, N-acetylcysteine, or 1,3-dimethyl-2-thiourea. NADH oxidase activation by LPS increased ERK1/2 and p38 phosphorylation, and inhibition of ERK1/2 and p38 phosphorylation blocked the effect of NADH oxidase on TNF-alpha expression. Isolated mouse hearts were perfused with LPS (5 microg/mL) alone or in the presence of apocynin for 1 hour. Myocardial TNF-alpha production was decreased in gp91phox-deficient or apocynin-treated hearts compared with those of wild type (P<0.05). To investigate the role of gp91phox-containing NADH oxidase in endotoxemia, mice were treated with LPS (4 mg/kg IP) for 4 and 24 hours, and their heart function was measured with a Langendorff system. Deficiency of gp91phox significantly attenuated LPS-induced myocardial depression (P<0.05).

CONCLUSIONS

gp91phox-Containing NADH oxidase is pivotal in LPS-induced TNF-alpha expression and cardiac depression. Effects of NADH oxidase activation are mediated by ERK1/2 and p38 MAPK pathway. The present results suggest that gp91phox-containing NADH oxidase may represent a potential therapeutic target for myocardial dysfunction in sepsis.

Bone marrow-derived cells contribute to contractile dysfunction in endotoxic shock

How infection precipitates depressed contractility is incompletely understood but may involve the immune, nervous, and endocrine systems as well as the heart itself. In this study, we examined the role of Toll-like receptor 4 (TLR4) in LPS-induced myocardial contractile depression. Eighteen hours following endotoxin challenge, we compared contractile responses in hearts from wild-type (WT) and TLR4-deficient mice using modified Langendorff preparations. Unlike hearts from WT mice, TLR4-deficient hearts did not reveal significant contractile dysfunction following LPS administration, as measured by decreased responses in maximal left ventricular pressure, +dP/d tmax, and −dP/d tmaxin ex vivo Langendorff preparations. These findings indicate a requirement for TLR4 in LPS-induced contractile depression. To determine the contribution of bone marrow-derived TLR4 function to LPS-induced myocardial dysfunction, we generated TLR4 chimeras using adoptive transfer between histocompatible mouse strains: either TLR4-deficient mice with TLR4+/+ bone marrow-derived cells or TLR4+/+ animals lacking TLR4 in their hematopoietic cells. We then compared the contractile responses of engrafted animals after LPS challenges. Engraftment of TLR4-deficient mice with WT marrow restored sensitivity to the myocardial depressant effects of LPS in TLR4-deficient hearts ( P < 0.05). Inactivation of bone marrow-derived TLR4 function, via transplantation of WT mice with TLR4−/− marrow, however, did not protect against the depressant effect of endotoxin. These findings indicate that bone marrow-derived TLR4 activity is sufficient to confer sensitivity to mice lacking TLR4 in all other tissues. However, because inactivation of marrow-derived TLR4 function alone does not protect against endotoxin-triggered contractile dysfunction, TLR4 function in other tissues may also contribute to this response.

Nitric oxide and cyclic GMP increase the expression of matrix metalloproteinase-9 in vascular smooth muscle

Interactions and possible cross talk between inducible nitricoxide synthase (iNOS), cyclooxygenase-2 (COX-2) and matrix metalloproteinase-9 (MMP-9), were studied in rat aortic vascular smooth muscle cells stimulated with bacterial lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), and phorbol 12-myristate13-acetate (PMA). The expression and activity of iNOS, COX-2, and MMP-9 were characterized at the transcriptional, protein, and enzyme activity levels. The NOS inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME) was used to investigate the effects of NO on COX-2 and MMP-9 at the transcriptional level. The measurements of mRNAs for these enzymes using real-time polymerase chain reaction (PCR) showed that COX-2 mRNA was up-regulated 2.3-fold, whereas MMP-9 mRNA up-regulation was 11.7-fold in the presence of LPS, IFN-gamma, and PMA. Real-time PCR results indicated that L-NAME exerted an inhibitory effect on COX-2 and MMP-9 mRNA synthesis. Both superoxide dismutase (SOD) and the SOD mimetic Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride (MnTMPyP) did not modify significantly the up-regulation of these enzymes, indicating that neither superoxide nor peroxynitrite are involved in this mechanism. Furthermore, NO-mediated up-regulation of MMP-9 was cGMP-dependent since 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase, blocked, in a concentration-dependent manner, the increased expression of MMP-9, an effect reversed by 8-bromo-cGMP, a soluble analog of cGMP. Our findings suggest that NO and cGMP are necessary to up-regulate the expression of MMP-9.

TNF-receptor-associated factors as targets for drug development

TNF-receptor-associated factors (TRAFs) are the bottleneck of the TNF-receptor (TNF-R) family signal transduction. They integrate the signalling from many members of the TNF-R family and initiate intracellular signalling cascades aimed at the activation of NF-kappaB and c-jun, the reprogramming of gene expression and the control of cell death. Deregulation of these pathways is the cause of several autoimmune and inflammatory diseases. The specificity and interaction of the members of the TRAF family with the TNF-R entails the recognition of just a 4 - 6 amino acid motif in the cytosolic region of the receptor, suitable as an attractive target for drug discovery. This review summarises the current knowledge on TRAFs and discusses the pros and cons of their application as targets for drug discovery.

Dissecting mechanisms of innate and acquired immunity in myocarditis

Inflammation underlies the pathogenesis of some of the most common cardiovascular diseases. Myocarditis is a relevant clinical cause of heart failure, but also provides an excellent laboratory model to study the mechanisms of inflammation leading to heart failure. The availability of different inbred mouse strains for inducing myocarditis using viral or myosin as triggers provides an excellent platform for investigation. The recent use of genetically manipulated mouse models of transgenic overexpression or knockout or knockin targets have provided opportunity to pinpoint specific pathways underlying myocarditis. These pathways include the involvement of both innate and acquired immunity, as well as the role of viral receptors in disease phenotype. These different models also permit the evaluation of therapeutic strategies of candidates for clinical development.

New concepts in sepsis

An estimated 750,000 cases of severe sepsis occur annually in the United States, and the mortality rate is about 30%. As a condition that disproportionately affects the elderly and is related to invasive and immunosuppressive healthcare, increases in the frequency of sepsis are anticipated. The complex pathophysiology of sepsis encompasses the interplay of pro- and anti-inflammatory mediators, activated circulating and resident inflammatory cells, disrupted coagulation, endothelial activation and injury, vasodilatation and vascular hyporesponsiveness to vasoactive mediators, cardiac dysfunction, and cellular dysoxia. Current management of severe sepsis includes eradication of infection through source control and antimicrobial therapy, aggressive and targeted shock resuscitation that includes fluid administration, correction of anemia, vasopressor support, modest inotropic therapy, infusion of human recombinant activated protein C to selected patients, and compulsive supportive care to manage organ dysfunction and to avoid complications.

Toll-like receptors as potential therapeutic targets for multiple diseases

The family of Toll-like receptors (TLRs) is receiving considerable attention as potential regulators and controllers of the immune response through their ability to recognize pathogen-associated molecular patterns. The discovery that endogenous ligands, as well as microbial components, are recognized by TLRs, and that small-molecular-mass synthetic compounds activate TLRs, raised interest in these receptors as potential targets for the development of new therapies for multiple diseases. In this review, we discuss the current and future use of TLR agonists or antagonists in chronic inflammatory diseases and highlight potential problems that are associated with such approaches.