PLCE1 enhances mitochondrial dysfunction to promote GSDME-mediated pyroptosis in doxorubicin-induced cardiotoxicity

BACKGROUND

The therapeutic value and long-term application of doxorubicin (DOX) were hampered by its severe irreversible cardiotoxicity. Phospholipase C epsilon 1 (PLCE 1) was reported as a new member of the phospholipase C (PLC) family which controls the level of phosphoinositides in cells. Pyroptosis is a newly discovered inflammatory type of regulated cell death. Recent studies have consolidated that chemotherapeutic drugs lead to pyroptosis. Additionally, the phosphoinositide signaling system has remarkable effects on the execution of cell death. We aim to investigate the role of PLCE1 and the mechanism of pyroptosis from the context of DOX-induced cardiotoxicity.

METHODS

In the current study, in vitro and in vivo experiments were performed to dissect the underlying mechanism of cardiomyocyte pyroptosis during DOX-induced cardiac injury. The molecular mechanism of PLCE1 was identified by the human cardiomyocyte AC16 cell line and C57BL/6 mouse model.

RESULTS

The results here indicated that PLCE1 high expressed and pyroptotic cell death presented in cardiomyocytes after DOX application, which was negatively correlated to heart function. DOX-induced cell model disclosed pyroptosis mediated by Gasdermin E (GSDME) protein and involved in mitochondrial damage. Conversely, the deletion of PLCE1 ameliorated mitochondrial dysfunction by suppressing ROS accumulation and reversing mitochondrial membrane potential, and then increased cell viability effectively. More importantly, the in vivo experiment demonstrated that inhibition of PLCE1 reduced pyroptotic cell death and improved heart effect.

CONCLUSIONS

We discovered firstly that PLCE1 inhibition protected cardiomyocytes from DOX-induced pyroptotic injury and promoted cardiac function. This information offers a theoretical basis for promising therapy.

Helium Protects Against Lipopolysaccharide-Induced Cardiac Dysfunction in Mice via Suppressing Toll-Like Receptor 4-Nuclear Factor κB-Tumor Necrosis Factor-Alpha/ Interleukin-18 Signaling

The nonanesthetic noble gas helium (He) can protect many organs against ischemia and reperfusion injury, such as liver and heart. However, the role of He on cardiac dysfunction during sepsis is not clear. In this study, we established a lipopolysaccharide (LPS)-induced cardiac dysfunction mouse model to examine the influence of He on the impaired cardiac function, and further investigated the possible innate immune mechanisms that may be involved. LPS induced left ventricular dysfunction and cavity enlargement, as indicated by decreased percent ejection fraction, percent fractional shortening, left ventricular anterior wall thickness in systole, and left ventricular posterior wall thickness in systole, while increased left ventricular end-systolic diameter and left ventricular end-systolic volume. He improved the impaired left ventricular function and cavity enlargement in a dose-dependent manner, and it was beneficial at 1.0 mL/100 g. Mechanistically, He inhibited toll-like receptor 4 (TLR4) expression, reduced the phosphorylation of nuclear factor κB (NF-κB), and subsequently alleviated tumor necrosis factor-alpha (TNF-α) and interleukin-18 (IL-18) expression in heart. Therefore, He protects against LPS-induced cardiac dysfunction in mice partially via inhibiting myocardial TLR4-NF-κB-TNF-α/IL-18 signaling.

Disrupted eNOS activity and expression account for vasodilator dysfunction in different stage of sepsis

AIMS

Sepsis is a severe endothelial dysfunction syndrome. The role of endothelial nitric oxide synthase (eNOS) in endothelial dysfunction induced by sepsis is controversial. To explore the role of eNOS in vascular dysfunction.

MAIN METHODS

The effect of sepsis on vasodilation and eNOS levels was examined in septic mouse arteries and in cell models.

KEY FINDINGS

In early sepsis mouse arteries, endothelium-dependent relaxation decreased and phosphorylation of the inhibitory Thr495 site in endothelial nitric oxide synthase increased. Mechanically, the phosphorylation of endothelial nitric oxide synthase at Thr497 in bovine aortic endothelial cells occurred in a protein kinase C-α dependent manner. In late sepsis, both nitric oxide-dependent relaxation responses and endothelial nitric oxide synthase levels were decreased in septic mice arteries. Endothelial nitric oxide synthase levels expression levels decreased in tumor necrosis factor-α-treated human umbilical vein endothelial cells and this could be prevented by the ubiquitin proteasome inhibitor (MG-132). MG-132 could reverse the decrease in endothelial nitric oxide synthase expression and improve nitric oxide-dependent vasodilator dysfunction in septic mice arteries.

SIGNIFICANCE

These data indicate that vasodilator dysfunction is induced by the increased phosphorylation of endothelial nitric oxide synthase in early sepsis and its degradation in late sepsis.

Kcnh2 mediates FAK/AKT-FOXO3A pathway to attenuate sepsis-induced cardiac dysfunction

Objectives

Myocardial dysfunction is a significant manifestation in sepsis, which results in high mortality. Even Kcnh2 has been hinted to associate with the pathological process, its involved signalling is still elusive.

Materials and methods

The caecal ligation puncture (CLP) surgery or lipopolysaccharide (LPS) injection was performed to induce septic cardiac dysfunction. Western blotting was used to determine KCNH2 expression. Cardiac function was examined by echocardiography 6 hours after CLP and LPS injection in Kcnh2 knockout (Kcnh2^+/‐) and NS1643 injection rats (n ≥ 6/group). Survival was monitored following CLP‐induced sepsis (n ≥ 8/group).

Results

Sepsis could downregulate KCNH2 level in the rat heart, as well as in LPS‐stimulated cardiomyocytes but not cardiac fibroblast. Defect of Kcnh2 (Kcnh2^+/‐) significantly aggravated septic cardiac dysfunction, exacerbated tissue damage and increased apoptosis under LPS challenge. Fractional shortening and ejection fraction values were significantly decreased in Kcnh2^+/‐ group than Kcnh2^+/+ group. Survival outcome in Kcnh2^+/‐ septic rats was markedly deteriorated, compared with Kcnh2^+/+ rats. Activated Kcnh2 with NS1643, however, resulted in opposite effects. Lack of Kcnh2 caused inhibition of FAK/AKT signalling, reflecting in an upregulation for FOXO3A and its downstream targets, which eventually induced cardiomyocyte apoptosis and heart tissue damage. Either activation of AKT by activator or knockdown of FOXO3A with si‐RNA remarkably attenuated the pathological manifestations that Kcnh2 defect mediated.

Conclusion

Kcnh2 plays a protection role in sepsis‐induced cardiac dysfunction (SCID) via regulating FAK/AKT‐FOXO3A to block LPS‐induced myocardium apoptosis, indicating a potential effect of the potassium channels in pathophysiology of SCID.

Extracellular SQSTM1 mediates bacterial septic death in mice through insulin receptor signalling

Sepsis is the most common cause of death for patients in intensive care worldwide due to a dysregulated host response to infection. Here, we investigate the role of sequestosome-1 (SQSTM1/p62), an autophagy receptor that functions as a regulator of innate immunity, in sepsis. We find that lipopolysaccharide elicits gasdermin D-dependent pyroptosis to enable passive SQSTM1 release from macrophages and monocytes, whereas transmembrane protein 173-dependent TANK-binding kinase 1 activation results in the phosphorylation of SQSTM1 at Ser403 and subsequent SQSTM1 secretion from macrophages and monocytes. Moreover, extracellular SQSTM1 binds to insulin receptor, which in turn activates a nuclear factor kappa B-dependent metabolic pathway, leading to aerobic glycolysis and polarization of macrophages. Intraperitoneal injection of anti-SQSTM1-neutralizing monoclonal antibodies or conditional depletion of Insr in myeloid cells using the Cre-loxP system protects mice from lethal sepsis (caecal ligation and puncture or infection by Escherichia coli or Streptococcus pneumoniae) and endotoxaemia. We also report that circulating SQSTM1 and the messenger RNA expression levels of SQSTM1 and INSR in peripheral blood mononuclear cells are related to the severity of sepsis in 40 patients. Thus, extracellular SQSTM1 has a pathological role in sepsis and could be targeted to develop therapies for sepsis.

Brain Natriuretic Peptide-Regulated Expression of Inflammatory Cytokines in Lipopolysaccharide (LPS)-Activated Macrophages via NF-κB and Mitogen Activated Protein Kinase (MAPK) Pathways

Background

This study aimed to investigate the effects of recombinant human brain natriuretic peptide (rhBNP) on IL-6, TNF-α, and IL-10 secretion in LPS-activated RAW 264.7 cells and human peripheral blood mononuclear cells (PBMCs) in vitro and to explore the related signaling pathways of the regulation mechanisms of BNP in systemic inflammatory response syndrome (SIRS).

Material/Methods

MTT assay was used to evaluate the effects of rhBNP on cell viabilities. Lipopolysaccharide (LPS) was used to induce inflammation response. The whole study was divided into 8 groups: Control, low, middle, and high concentrations of rhBNP, LPS, LPS with low, middle, and high concentrations of rhBNP. Levels of IL-6, TNF-α, and IL-10 were evaluated using the Cytometric Bead Array Kit and RT-PCR assay. Western blotting was used to test the effects of rhBNP on inflammation-related NF-κB and MAPK pathways.

Results

Except for the concentrations ≥1.6 ng/mL, all concentrations of rhBNP showed little effect on cell viabilities of RAW264.7 cells and PBMCs after 24 h and 48 h, suggesting a weak cytotoxicity to cells. Expression of IL-6 and TNF-α significantly increased and expression of IL-10 significantly decreased at protein and mRNA levels after LPS treatment, and these effects were strongly inhibited in a dose-dependent manner by pretreatment of rhBNP. Similarly, the LPS-induced increase of NF-κB and MAPK pathway phosphorylation levels were also significantly inhibited by rhBNP.

Conclusions

rhBNP can regulate expression of IL-6, TNF-α, and IL-10 in LPS-activated RAW 264.7 cells and PBMCs through inhibiting NF-κB and MAPK pathways. These results may reveal potential causes of the increase of BNP in SIRS and may provide an experimental basis for treatment of SIRS.

Protective effect of recombinant human brain natriuretic peptide on acute renal injury induced by endotoxin in canines

The objective of this study was to evaluate the protective effect of recombinant human brain natriuretic peptide (rhBNP) on endotoxin-induced acute kidney injury (AKI) in canine model of septic shock and its potential mechanisms. Dogs with endotoxin-induced septic shock were subjected to intravenous infusion of saline solution or rhBNP at the concentrations of 5 μg/kg (low-dose intervention group) or 10 μg/kg (high-dose intervention group). At 0, 2, 4, 8, and 12 h, the systemic vascular resistance index (SVRI) as well as serum levels of high mobility group box 1 protein (HMGB-1) and creatinine were measured, and kidney tissue samples were taken for histological examination. We have found that low and high doses of rhBNP could significantly reduce kidney tissue damage, such as tubular epithelial swelling and atrophy, and interstitial cell swelling in response to LPS injection in the dog sepsis models. rhBNP administration significantly reduced SVRI and serum levels of creatinine in dogs with LPS-induced sepsis in a dose-dependent manner, and attenuated the rise in the circulating HMGB-1. In conclusion, these findings suggest that rhBNP may exert dose-dependent protective effect on kidney tissue with endotoxin-induced injury, and this effect may be associated with the changes in blood levels of HMGB-1. rhBNP may be considered as therapeutic agents for treating sepsis-induced AKI.

Inhibiting microRNA-144 abates oxidative stress and reduces apoptosis in hearts of streptozotocin-induced diabetic mice

INTRODUCTION

Hyperglycemia-induced reactive oxygen species (ROS) generation contributes to the development of diabetic cardiomyopathy. However, little is known about the role of microRNAs in the regulation of ROS formation and myocardial apoptosis in streptozotocin (STZ)-induced diabetic mice.

METHODS AND RESULTS

It was observed that microRNA-144 (miR-144) level was lower in heart tissues of STZ-induced diabetic mice. High glucose exposure also reduced miR-144 levels in cultured cardiomyocytes. Moreover, miR-144 modulated high glucose-induced oxidative stress in cultured cardiomyocytes by directly targeting nuclear factor-erythroid 2-related factor 2 (Nrf2), which was a central regulator of cellular response to oxidative stress. The miR-144 mimics aggravated high glucose-induced ROS formation and apoptosis in cardiomyocytes, which could be attenuated by treatment with Dh404, an activator of Nrf2. Meanwhile, inhibition of miR-144 suppressed ROS formation and apoptosis induced by high glucose in cultured cardiomyocytes. What was more important is that reduced myocardial oxidative stress and apoptosis and improved cardiac function were identified in STZ-induced diabetic mice when treated with miR-144 antagomir.

CONCLUSION

Although miR-144 cannot explain the increased oxidative stress in STZ, therapeutic interventions directed at decreasing miR-144 may help to decrease oxidative stress in these hearts. Inhibition of miR-144 might have clinical potential to abate oxidative stress as well as to reduce cardiomyocyte apoptosis and improve cardiac function in diabetic cardiomyopathy.

NADPH oxidase contributes to the left ventricular dysfunction induced by sinoaortic denervation in rats

The aim of this work was to investigate the role nicotinamide adenine dinucleotide phosphate (NADPH) oxidase on left ventricular dysfunction of rats submitted to sinoaortic denervation (SAD). Experiment 1: 8 weeks after SAD of rats, NADPH oxidase in left ventricles was assayed by Western blotting analysis. Experiment 2: Rats were subjected to SAD and received treatment with apocynin (an NADPH oxidase inhibitor, 30 mg/kg/day, intragastric administration) for 8 weeks; 8 weeks after SAD, Nox2 and Nox4 expressions and Rac1 activity of left ventricles were higher in SAD rats than those in sham-operated rats. Although treatment of SAD rats with apocynin did not affect blood pressure, blood pressure variability (BPV), and baroreflex function, it significantly attenuated left ventricular hypertrophy marked by reduced expression of atrial natriuretic factor and β-myosin heavy chain. Treatment of SAD rats with apocynin abated oxidative stress marked by reduced malondialdehyde formation and suppressed nuclear factor-kappa B (NFκB) activation; inflammation marked by reduced monocyte chemoattractant protein-1 expression and myeloperoxidase activity; attenuated endoplasmic reticulum stress marked by reduced expression of CCAAT-enhancer-binding protein homologous protein, chaperone-glucose-regulated protein 78, and X-box protein 1; and alleviated cardiac fibrosis marked by reduced mRNA levels of collagens I and III and transforming growth factor beta. In conclusion, exaggerated BPV induces chronic myocardial oxidative stress and thereby aggravates cardiac remodeling in rats. These data suggest a potential role of NADPH oxidases in the pathogenesis of cardiac dysfunction induced by exaggerated BPV.

PLCγ1-PKCγ signaling-mediated Hsp90α plasma membrane translocation facilitates tumor metastasis

The 90-kDa heat shock protein (Hsp90α) has been identified on the surface of cancer cells, and is implicated in tumor invasion and metastasis, suggesting that it is a potentially important target for tumor therapy. However, the regulatory mechanism of Hsp90α plasma membrane translocation during tumor invasion remains poorly understood. Here, we show that Hsp90α plasma membrane expression is selectively upregulated upon epidermal growth factor (EGF) stimulation, which is a process independent of the extracellular matrix. Abrogation of EGF-mediated activation of phospholipase (PLCγ1) by its siRNA or inhibitor prevents the accumulation of Hsp90α at cell protrusions. Inhibition of the downstream effectors of PLCγ1, including Ca(2+) and protein kinase C (PKCγ), also blocks the membrane translocation of Hsp90α, while activation of PKCγ leads to increased levels of cell-surface Hsp90α. Moreover, overexpression of PKCγ increases extracellular vesicle release, on which Hsp90α is present. Furthermore, activation or overexpression of PKCγ promotes tumor cell motility in vitro and tumor metastasis in vivo, whereas a specific neutralizing monoclonal antibody against Hsp90α inhibits such effects, demonstrating that PKCγ-induced Hsp90α translocation is required for tumor metastasis. Taken together, our study provides a mechanistic basis for the role for the PLCγ1-PKCγ pathway in regulating Hsp90α plasma membrane translocation, which facilitates tumor cell motility and promotes tumor metastasis.

Myocyte signalling in leucocyte recruitment to the heart

Myocardial damage, by different noxious causes, triggers an inflammatory reaction driving post-injury repair mechanisms and chronic remodelling processes that are largely detrimental to cardiac function. Cardiomyocytes have recently emerged as key players in orchestrating this inflammatory response. Injured cardiomyocytes release damage-associated molecular pattern molecules, such as high-mobility group box 1 (HMGB1), DNA fragments, heat shock proteins, and matricellular proteins, which instruct surrounding healthy cadiomyocytes to produce inflammatory mediators. These mediators, mainly interleukin (IL)-1β, IL-6, macrophage chemoattractant protein (MCP)-1, and tumour necrosis factor α (TNF-α), in turn activate versatile signalling networks within surviving cardiomyocytes and trigger leucocyte activation and recruitment. In this review, we will focus on recently characterized signalling pathways activated in cardiomyocytes that mediate inflammatory responses during myocardial infarction, hypertensive heart disease, and myocarditis.

In vivo epithelial wound repair requires mobilization of endogenous intracellular and extracellular calcium

We report that a localized intracellular and extracellular Ca(2+) mobilization occurs at the site of microscopic epithelial damage in vivo and is required to mediate tissue repair. Intravital confocal/two-photon microscopy continuously imaged the surgically exposed stomach mucosa of anesthetized mice while photodamage of gastric epithelial surface cells created a microscopic lesion that healed within 15 min. Transgenic mice with an intracellular Ca(2+)-sensitive protein (yellow cameleon 3.0) report that intracellular Ca(2+) selectively increases in restituting gastric epithelial cells adjacent to the damaged cells. Pretreatment with U-73122, indomethacin, 2-aminoethoxydiphenylborane, or verapamil inhibits repair of the damage and also inhibits the intracellular Ca(2+) increase. Confocal imaging of Fura-Red dye in luminal superfusate shows a localized extracellular Ca(2+) increase at the gastric surface adjacent to the damage that temporally follows intracellular Ca(2+) mobilization. Indomethacin and verapamil also inhibit the luminal Ca(2+) increase. Intracellular Ca(2+) chelation (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/acetoxymethyl ester, BAPTA/AM) fully inhibits intracellular and luminal Ca(2+) increases, whereas luminal calcium chelation (N-(2-hydroxyetheyl)-ethylendiamin-N,N,N'-triacetic acid trisodium, HEDTA) blocks the increase of luminal Ca(2+) and unevenly inhibits late-phase intracellular Ca(2+) mobilization. Both modes of Ca(2+) chelation slow gastric repair. In plasma membrane Ca-ATPase 1(+/-) mice, but not plasma membrane Ca-ATPase 4(-/-) mice, there is slowed epithelial repair and a diminished gastric surface Ca(2+) increase. We conclude that endogenous Ca(2+), mobilized by signaling pathways and transmembrane Ca(2+) transport, causes increased Ca(2+) levels at the epithelial damage site that are essential to gastric epithelial cell restitution in vivo.

Affinity Purification of Tumor Necrosis Factor-α Expressed in Raji Cells by Produced scFv Antibody Coupled CNBr-Activated Sepharose

PURPOSE

Recombinant tumor necrosis factor-alpha (TNF-α) has been utilized as an antineoplastic agent for the treatment of patients with melanoma and sarcoma. It targets tumor cell antigens by impressing tumor-associated vessels. Protein purification with affinity chromatography has been widely used in the downstream processing of pharmaceutical-grade proteins.

METHODS

In this study, we examined the potential of our produced anti-TNF-α scFv fragments for purification of TNF-α produced by Raji cells. The Raji cells were induced by lipopolysaccharides (LPS) to express TNF-α. Western blotting and Fluorescence-activated cell sorting (FACS) flow cytometry analyses were used to evaluate the TNF-α expression. The anti-TNF-α scFv selected from antibody phage display library was coupled to CNBr-activated sepharose 4B beads used for affinity purification of expressed TNF-α and the purity of the protein was assessed by SDS-PAGE.

RESULTS

Western blot and FACS flow cytometry analyses showed the successful expression of TNF-α with Raji cells. SDS-PAGE analysis showed the performance of scFv for purification of TNF-α protein with purity over 95%.

CONCLUSION

These findings confirm not only the potential of the produced scFv antibody fragments but also this highly pure recombinant TNF-α protein can be applied for various in vitro and in vivo applications.

Changes in the inositol lipid signal system and effects on the secretion of TNF-α by macrophages in severely scalded mice

AIM

In order to study the mechanism of abnormal macrophage (Mϕ) function in pro-inflammatory cytokine changes after burn, the inositol lipid signal system and its role in tumour necrosis factor-alpha (TNF-α) secretion by peritoneal Mϕs was observed in severely scalded mice.

METHODS

Eighteen percent total body surface area (TBSA) full-thickness scalded mice were used as animal model in this experiment. Peritoneal Mϕs stimulated by lipopolysaccharide in vitro were collected at different time intervals (0, 2, 6, 12, 24 and 48 after burn hour (PBH)), The activities of phosphatidylinositol-phospholipase C (PI-PLC), inositol-1, 4,5, -triphosphate (IP(3)), protein kinase C (PKC), diacylglycerol (DAG) and TNF-α and the level of Ca(2+) concentration in peritoneal Mϕs were measured, and the effects of specific PKC inhibitor H-7 and calmodulin antagonist W-7 on the production of TNF-α were also observed.

RESULTS

After scald, increased activities of TNF-α and PLC of Mϕ were observed and peaked at 12 PBH. The activities of DAG and IP(3) and the concentration of Ca(2+) were markedly increased and reached their peaks at 24 PBH simultaneously. Membrane PKC activity was up-regulated after scald and showed a positive correlation with the change of DAG (r=0.83, P<0.05). There was also positive correlation between IP(3) and Ca(2+) activity (r=0.946, P<0.01). When 12 PBH was chosen as the time point for in vitro intervention with the pre-treatment by H-7, both membrane PKC and TNF-α activity decreased significantly. There was no obvious change of TNF-α activity with the application of W-7.

CONCLUSIONS

These results indicated that the abnormal activity of TNF-α of Mϕs might be regulated by the inositol lipid signal system following severe burn. The DAG-PKC signal pathway showed closer relationship than IP(3)-Ca(2+) in TNF-α production and could be the optimal target in the prevention and treatment of the systemic inflammatory response syndrome.

Atrial natriuretic peptide alleviates cardiovascular and metabolic disorders in a rat endotoxemia model: a possible role for its anti-inflammatory properties

BACKGROUND

Atrial natriuretic peptide (ANP) plays important roles in the regulation of cardiovascular and renal homeostasis. Furthermore, several studies have shown that ANP may have anti-inflammatory activities. We hypothesized that ANP may alleviate cardiovascular and/or metabolic disorders in rats with lipopolysaccharide (LPS)-induced endotoxemia.

METHODS

In rats anesthetized with pentobarbital, LPS was injected and ANP was continuously infused at 0.15 µg/kg/min. Mean arterial pressure and pulse rate were monitored hourly, and arterial blood gases were analyzed before LPS injection and at 1, 4, and 6 hours after LPS injection. The expression in the rat left ventricle of mRNAs encoding nitric oxide synthase 2 and 3 (iNOS, eNOS), heme oxygenase 1 and 2 (HO-1, 2), tumor necrosis factor α (TNFα), and interleukin (IL)-1β was measured with the real-time reverse transcriptase-polymerase chain reaction.

RESULTS

LPS increased the expression of TNFα, IL-1β, iNOS, and HO-1, which was inhibited by infusion of ANP. Furthermore, the LPS-induced decrease in mean arterial pressure was attenuated, and the acid-base imbalance caused by increased lactate production was improved 6 hours after the administration of ANP.

CONCLUSIONS

Our results suggest that continuous infusion of ANP counteracts the cardiovascular and metabolic disorders associated with endotoxemia, possibly via anti-inflammatory mechanisms.

Nitric oxide and calcium signaling regulate myocardial tumor necrosis factor-α expression and cardiac function in sepsis

Myocardial tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, is a critical inducer of myocardial dysfunction in sepsis. The purpose of this review is to summarize the mechanisms through which TNF-alpha production is regulated in cardiomyocytes in response to lipopolysaccharide (LPS), a key pathogen-associated molecular pattern (PAMP) in sepsis. These mechanisms include Nox2-containing NAD(P)H oxidase, phospholipase C (PLC)gamma1, and Ca2+ signaling pathways. Activation of these pathways increases TNF-alpha expression via activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). Conversely, activation of c-Jun NH2-terminal kinase 1 (JNK1) negatively regulates TNF-alpha production through inhibition of ERK1/2 and p38 MAPK activity. Interestingly, endothelial nitric oxide synthase (eNOS) promotes TNF-alpha expression by enhancing p38 MAPK activation, whereas neuronal NOS (nNOS) inhibits TNF-alpha production by reducing Ca2+-dependent ERK1/2 activity. Therefore, the JNK1 and nNOS inhibitory pathways represent a "brake" that limits myocardial TNF-alpha expression in sepsis. Further understanding of these signal transduction mechanisms may lead to novel pharmacological therapies in sepsis.

In Vitro Effects of the Reduced Form of Coenzyme Q(10) on Secretion Levels of TNF-alpha and Chemokines in Response to LPS in the Human Monocytic Cell Line THP-1

Ubiquinol-10 (QH₂), the reduced form of Coenzyme Q₁₀ (CoQ₁₀) serves as a potent antioxidant of lipid membranes. Because many antioxidants reveal potent anti-inflammatory effects, the influence of QH₂ on lipopolysaccharide (LPS)-induced pro-inflammatory cytokines and chemokines were determined in the human monocytic cell line THP-1. Stimulation of cells with LPS resulted in a distinct release of Tumour necrosis factor-alpha (TNF-α), Macrophage inflammatory protein-1 alpha (MIP-1α), Regulated upon activation, normal T cell expressed and secreted (RANTES) and Monocyte chemotattractant protein-1 (MCP-1). The LPS-induced responses were significantly decreased by pre-incubation of cells with QH₂ to 60.27 ± 9.3% (p = 0.0009), 48.13 ± 6.93% (p = 0.0007) and 74.36 ± 7.25% (p = 0.008) for TNF-α, MIP-1α and RANTES, respectively. In conclusion, our results indicate anti-inflammatory effects of the reduced form of CoQ₁₀ on various proinflammatory cytokines and chemokines in vitro.