Acute lung injury (ALI) is a life-threatening disease without effective pharmacotherapies, so far. Forsythia suspensa is frequently used in the treatment of lung infection in traditional Chinese medicine. In search for natural anti-inflammatory components, the activity and the underlying mechanism of Forsythoside A (FA) from Forsythia suspensa were explored. In the present paper, BALB/c mice and murine RAW 264.7 cells were stimulated by LPS to establish inflammation models. Data showed that FA inhibited the production of TNF-α and IL-6 and the activation of STAT3 in LPS-stimulated RAW 264.7 cells. Additionally, FA increased the expression level of microRNA-124 (miR-124). Furthermore, the inhibitory effect of FA on STAT3 was counteracted by the treatment of miR-124 inhibitor. Critically, FA ameliorated LPS-induced ALI pathological damage, the increase in lung water content and inflammatory cytokine, cells infiltration and activation of the STAT3 signaling pathway in BALB/c mice. Meanwhile, FA up-regulated the expression of miR-124 in lungs, while administration with miR-124 inhibitor attenuated the protective effects of FA. Our results indicated that FA alleviates LPS-induced inflammation through up-regulating miR-124 in vitro and in vivo . These findings indicate the potential of FA and miR-124 in the treatment of ALI.

Acute respiratory distress syndrome (ARDS) is a severe condition with high morbidity and mortality and few interventions. The role of sympathetic stress in the pathogenesis of ARDS has attracted recent research attention. Blockade of α-2 or α2A-adrenoceptor (α 2A -AR) has been shown to attenuate lung injury induced by lipopolysaccharide (LPS) in rats. However, the mechanism is unclear. We confirmed the role of α 2A -AR in ARDS using knockout mice and alveolar macrophages following LPS stimulation to assess the underlying mechanisms. We found that α 2A -AR deficiency decreased the permeability of the alveolar capillary barrier in ARDS mice and suppressed lung inflammation by reducing inflammatory cell infiltration and the production of TNF-α, interleukin (IL)-6, and CXCL2/MIP-2. LPS stimulation decreased NF-κB activation in lung tissues of α 2A -AR deficient mice and increased norepinephrine concentrations. In vitro , we found that norepinephrine inhibited the production of TNF-α, IL-6, and CXCL2/MIP-2 and promoted the secretion of IL-10 from LPS-stimulated murine alveolar macrophages. Blockade of α 2A -AR by a specific antagonist further inhibited the production of TNF-α, IL-6, and IL-10. Furthermore, norepinephrine down-regulated NF-κB activation in stimulated alveolar macrophages. Altogether, these results suggest that α 2A -AR deficiency ameliorates lung injury by increasing norepinephrine concentrations in lung tissues and inhibiting the activation of alveolar macrophages.

Preeclampsia (PE) is regarded as a pregnancy-associated hypertension disorder that is related to excessive inflammatory responses. Although the gut microbiota (GM) and short-chain fatty acids (SCFAs) have been related to hypertension, their effects on PE remain unknown. We determined the GM abundance and faecal SCFA levels by 16S ribosomal RNA (rRNA) sequencing and gas chromatography, respectively, using faecal samples from 27 patients with severe PE and 36 healthy, pregnant control subjects. We found that patients with PE had significantly decreased GM diversity and altered GM abundance. At the phylum level, patients with PE exhibited decreased abundance of Firmicutes albeit increased abundance of Proteobacteria; at the genus level, patients with PE had lower abundance of Blautia, Eubacterium_rectale, Eubacterium_hallii, Streptococcus, Bifidobacterium, Collinsella, Alistipes , and Subdoligranulum , albeit higher abundance of Enterobacter and Escherichia_Shigella . The faecal levels of butyric and valeric acids were significantly decreased in patients with PE and significantly correlated with the above-mentioned differential GM abundance. We predicted significantly increased abundance of the lipopolysaccharide (LPS)-synthesis pathway and significantly decreased abundance of the G protein-coupled receptor (GPCR) pathway in patients with PE, based on phylogenetic reconstruction of unobserved states (PICRUSt). Finally, we evaluated the effects of oral butyrate on LPS-induced hypertension in pregnant rats. We found that butyrate significantly reduced the blood pressure (BP) in these rats. In summary, we provide the first evidence linking GM dysbiosis and reduced faecal SCFA to PE and demonstrate that butyrate can directly regulate BP in vivo , suggesting its potential as a therapeutic agent for PE.

Eph-Ephrin signalling mediates various cellular processes, including vasculogenesis, angiogenesis, cell migration, axon guidance, fluid homoeostasis and repair after injury. Although previous studies have demonstrated that stimulation of the EphA receptor induces increased vascular permeability and inflammatory response in lung injury, the detailed mechanisms of EphA2 signalling are unknown. In the present study, we evaluated the role of EphA2 signalling in mice with lipopolysaccharide (LPS)-induced lung injury. Acute LPS exposure significantly up-regulated EphA2 and EphrinA1 expression. Compared with LPS+IgG mice (IgG instillation after LPS exposure), LPS+EphA2 mAb mice [EphA2 monoclonal antibody (mAb) instillation posttreatment after LPS exposure] had attenuated lung injury and reduced cell counts and protein concentration of bronchoalveolar lavage fluid (BALF). EphA2 mAb posttreatment down-regulated the expression of phosphoinositide 3-kinases (PI3K) 110γ, phospho-Akt, phospho-NF-κB p65, phospho-Src and phospho-S6K in lung lysates. In addition, inhibiting the EphA2 receptor augmented the expression of E-cadherin, which is involved in cell–cell adhesion. Our study identified EphA2 receptor as an unrecognized modulator of several signalling pathways–including PI3K-Akt-NF-kB, Src-NF-κB, E-cadherin and mTOR–in LPS-induced lung injury. These results suggest that EphA2 receptor inhibitors may function as novel therapeutic agents for LPS-induced lung injury.

Platelets play an important role in the activation of coagulation. P2Y 12 receptor inhibition may be beneficial in inflammatory states. Prasugrel, a potent irreversible inhibitor of P2Y 12 receptor-induced platelet activation may reduce activation of coagulation in a human LPS (lipopolysaccharide) model. A double-blind, randomized, crossover trial with a minimum washout period of 6 weeks was performed. Sixteen subjects were randomly assigned to a treatment group that received prasugrel or placebo 2 h before infusion of a bolus of LPS (2 ng/kg of body weight), whereas four subjects were assigned to a control group receiving prasugrel or placebo without LPS. hcDNA (histone-complexed DNA), coagulation and platelet-specific parameters were measured by enzyme immunoassay. Leucocyte aggregate formation was analysed by flow cytometry, and thromboelastometry was performed. LPS infusion markedly activated coagulation. However, prasugrel did not reduce changes in prothrombin fragments 1 and 2 (F1+2), thrombin–antithrombin complexes, microparticle-associated tissue factor, CD40 ligand, P-selectin, platelet–leucocyte aggregation, hcDNA levels or the coagulation profile measured by thromboelastometry. hcDNA plasma levels increased approximately 6-fold after LPS infusion in both treatment groups, but not in the control groups. Potent irreversible P2Y 12 inhibition by prasugrel does not affect LPS-induced coagulation activation. The 6-fold increased hcDNA plasma levels after infusion of LPS indicates the formation of neutrophil extracellular traps during sterile inflammation.

Secondary infections due to post-sepsis immunosuppression are a major cause of death in patients with sepsis. Repetitive inoculation of increasing doses of lipopolysaccharide (LPS) into mice mimics the immunosuppression associated with sepsis. Myeloid-derived suppressor cells (MDSCs, Gr-1 + CD11b + ) are considered a major component of the immunosuppressive network, interfering with T-cell responses in many pathological conditions. We used LPS-immunosuppressed (IS) mice to address whether MDSCs acquired their suppressive ability in the bone marrow (BM) and whether they could migrate to lymph nodes (LNs) to exert their suppressive function. Our results showed that Gr-1 + CD11b + cells of IS mice already had the potential to inhibit T-cell proliferation in the BM. Moreover, soluble factors present in the BM from IS mice were responsible for inducing this inhibitory ability in control BM cells. In addition, migration of Gr-1 + CD11b + to LNs in vivo was maximal when cells obtained from the BM of IS mice were inoculated into an IS context. In this regard, we found chemoattractant activity in cell-free LN extracts (LNEs) from IS mice and an increased expression of the LN-homing chemokine receptor C–C chemokine receptor type 7 (CCR7) in IS BM Gr-1 + CD11b + cells. These results indicate that Gr-1 + CD11b + cells found in BM from IS mice acquire their suppressive activity in the same niche where they are generated, and migrate to LNs to exert their inhibitory role. A better understanding of MDSC generation and/or regulation of factors able to induce their inhibitory function may provide new and more effective tools for the treatment of sepsis-associated immunosuppression.

During sepsis, endothelial barrier dysfunction contributes to cardiovascular failure, mainly through the release of oxidative metabolites by penetrant leukocytes. We reported the non-muscular isoform of myosin light chain kinase (nmMLCK) playing a pivotal role in endotoxin shock injury associated with oxidative and nitrative stresses, and vascular hyporeactivity. The present study was aimed at understanding the molecular mechanism of lipopolysaccharide (LPS)-induced vascular alterations as well as studying a probable functional association of nmMLCK with nuclear factor κ-light-chain enhancer of activated B cells (NF-κB). Aortic rings from mice were exposed in vitro to LPS and, then, vascular reactivity was measured. Human aortic endothelial cells (HAoECs) were incubated with LPS, and interaction of nmMLCK with NF-κB was analysed. We provide evidence that nmMLCK deletion prevents vascular hyporeactivity induced by in vitro LPS treatment but not endothelial dysfunction in the aorta. Deletion of nmMLCK inhibits LPS-induced NF-κB activation and increases nitric oxide (NO) release via induction of inducible NO synthase (iNOS) within the vascular wall. Also, removal of endothelium prevented both NF-κB and iNOS expression in aortic rings. Among the proinflammatory factors released by LPS-treated endothelial cells, interleukin-6 accounts for the induction of iNOS on smooth muscle cells in response to LPS. Of particular interest is the demonstration that, in HAoECs, LPS-induced NF-κB activation occurs via increased MLCK activity sensitive to the MLCK inhibitor, ML-7, and physical interactions between nmMLCK and NF-κB. We report for the first time on NF-κB as a novel partner of nmMLCK within endothelial cells. The present study demonstrates a pivotal role of nmMLCK in vascular inflammatory pathologies.

Skeletal muscle atrophy induced during sepsis syndrome produced by endotoxin in the form of LPS (lipopolysaccharide), is a pathological condition characterized by the loss of strength and muscle mass, an increase in MHC (myosin heavy chain) degradation, and an increase in the expression of atrogin-1 and MuRF-1 (muscle-specific RING-finger protein 1), two ubiquitin E3 ligases belonging to the ubiquitin–proteasome system. Ang-(1–7) [Angiotensin-(1–7)], through its Mas receptor, has beneficial effects in skeletal muscle. We evaluated in vivo the role of Ang-(1–7) and Mas receptor on the muscle wasting induced by LPS injection into C57BL/10J mice. In vitro studies were performed in murine C2C12 myotubes and isolated myofibres from EDL (extensor digitorum longus) muscle. In addition, the participation of p38 MAPK (mitogen-activated protein kinase) in the Ang-(1–7) effect on the LPS-induced muscle atrophy was evaluated. Our results show that Ang-(1–7) prevents the decrease in the diameter of myofibres and myotubes, the decrease in muscle strength, the diminution in MHC levels and the induction of atrogin-1 and MuRF-1 expression, all of which are induced by LPS. These effects were reversed by using A779, a Mas antagonist. Ang-(1–7) exerts these anti-atrophic effects at least in part by inhibiting the LPS-dependent activation of p38 MAPK both in vitro and in vivo . We have demonstrated for the first time that Ang-(1–7) counteracts the skeletal muscle atrophy induced by endotoxin through a mechanism dependent on the Mas receptor that involves a decrease in p38 MAPK phosphorylation. The present study indicates that Ang-(1–7) is a novel molecule with a potential therapeutic use to improve muscle wasting during endotoxin-induced sepsis syndrome.

Animal models with a high predictive value for human trials are needed to develop novel human-specific therapeutics for respiratory diseases. The aim of the present study was to examine lung-function parameters in marmoset monkeys ( Callithrix jacchus ) that can be used to detect pharmacologically or provocation-induced AHR (airway hyper-responsiveness). Therefore a custom-made lung-function device that allows application of defined aerosol doses during measurement was developed. It was hypothesized that LPS (lipopolysaccharide)-challenged marmosets show AHR compared with non-challenged healthy subjects. Invasive plethysmography was performed in 12 anaesthetized orotracheally intubated and spontaneously breathing marmosets. Pulmonary data of R L (lung resistance), C dyn (dynamic compliance), EF 50 (mid-expiratory flow), P oes (oesophageal pressure), MV (minute volume), respiratory frequency ( f ) and V T (tidal volume) were collected. Measurements were conducted under baseline conditions and under MCh (methacholine)-induced bronchoconstriction. The measurement was repeated with the same group of animals after induction of an acute lung inflammation by intratracheal application of LPS. PDs (provocative doses) of MCh to achieve a certain increase in R L were significantly lower after LPS administration. AHR was demonstrated in the LPS treated compared with the naïve animals. The recorded lung-function data provide ground for pre-clinical efficacy and safety testing of anti-inflammatory substances in the common marmoset, a new translational NHP (non-human primate) model for LPS-induced lung inflammation.

Pro-inflammatory cytokines, chemokines and ROS (reactive oxygen species) are excessively produced in endotoxaemia. However, attempting to inhibit all of these inflammatory signalling pathways at the same time in order to prevent endotoxaemia is difficult. In a previous study we observed that activation of P2X 7 receptors elicited the release of IL (interleukin)-1β from LPS (lipopolysaccharide)-incubated vessels. In the present study, we hypothesize that P2X 7 receptor activation is the initial event leading to vascular dysfunction following LPS treatment. LPS-induced decreases in MAP (mean arterial pressure) and pressor responses to NE (noradrenaline) were attenuated in P2X 7 KO (P2X 7 -knockout) mice. Hyporeactivity in response to PE (phenylephrine) in isolated mesenteric arteries by LPS treatment was also observed in C57BL/6 [WT (wild-type)] mice, which was prevented by IL1ra (IL-1 receptor antagonist), L -NAME ( N G -nitro- L -arginine methyl ester) and indomethacin and in P2X 7 KO mice. In addition, treatment with IL1ra plus L -NAME produced an additive inhibition of LPS-induced vascular hyporeactivity, suggesting different signalling pathways between IL-1β and NOS (NO synthase). LPS-induced plasma levels of IL-1β, TNFα (tumour necrosis factor α), IL-10, vascular eNOS (endothelial NOS) and COX2 (cyclo-oxygenase 2) protein expression, as determined by ELISA and Western blot, observed in WT mice were inhibited by IL1ra and in P2X 7 KO mice. These results suggest that P2X 7 receptor activation involves an initial upstream mechanism of LPS-induced vascular dysfunction, which is associated with IL-1β-mediated eNOS, COX2 activation and TNFα release.

OA (osteoarthritis) is a degenerative condition associated with obesity. A number of metabolic explanations have been proposed to explain the association between obesity and OA in non-weight-bearing joints; however, none of these hypotheses have been demonstrated empirically. In the present Hypothesis article, we recognize that obesity is associated with compromised gut mucosa, translocation of microbiota and raised serum LPS (lipopolysaccharide). The consequent activation of the innate immune response leads to increased serum titres of inflammatory mediators in obese patients, with both local and systemic markers of inflammation associated with onset and progression of OA. Furthermore, a number of workers have shown that articular cartilage repair is impaired by a range of inflammatory mediators, both in vitro and in vivo . We propose that metabolic endotoxaemia, caused by impaired gastric mucosa and low-grade chronic inflammation, may contribute to the onset and progression of OA in obese patients. This may account for the association between obesity and OA at non-weight-bearing joints which cannot be explained by biomechanical factors.

It has been suggested that Type 2 diabetes may, in part, be precipitated or accelerated by an acute-phase reaction as part of the innate immune response, in which large amounts of cytokines are released from adipose tissue, creating a low-grade inflammatory milieu. There is also firm evidence that atherosclerosis is an immune-mediated inflammatory disease. Therefore it is reasonable to imply that low-grade inflammation is an important pathogenetic factor in atherosclerosis and cardiovascular events in patients with Type 2 diabetes. Over the last few years, there have been a lot of promising clinical markers proposed to link inflammation and atherosclerosis. Of these markers, hs-CRP (high-sensitivity C-reactive protein) might be a prognostic marker for further cardiovascular events, although this has been refuted recently. In this issue of Clinical Science , Castoldi and co-workers have demonstrated that, in patients with Type 2 diabetes categorized into low (<1.0 mg/l), medium (1.0–3.0 mg/l) and high (>3.0 mg/l) hs-CRP groups, serum levels of hs-CRP correlated with lipopolysaccharide-stimulated release of interleukin-1β and interleukin-6 in whole blood. This finding may indicate that low-grade inflammatory activity might influence cytokine production in these patients.

Diabetes mellitus accelerates atherosclerotic processes, and it is known that inflammation plays a key role in atherosclerosis. The aim of the present study was to evaluate in patients with Type 2 diabetes whether serum levels of CRP (C-reactive protein) are associated with cytokine production in whole blood. A total of 89 outpatients with Type 2 diabetes were enrolled, and blood pressure, body mass index, fasting blood glucose, glycated haemoglobin, cholesterol, triacylglycerols (triglycerides) and hs-CRP (high-sensitivity CRP) were measured. IL-6 (interleukin-6), IL-1β (interleukin-1β) and TNF-α (tumour necrosis factor-α) were measured before and after 24 h of incubation of whole blood with LPS (lipopolysaccharide) or saline. The basal values of IL-1β, IL-6 and TNF-α were low and were not significantly related to hs-CRP levels. A univariate analysis showed that the level of IL-1β and IL-6, obtained after 24 h of incubation of whole blood with LPS, increased significantly with increasing levels of hs-CRP and, after adjusting for potential confounders, IL-1β still remained statistically significant. In our sample of patients with Type 2 diabetes, there was no association between serum hs-CRP levels and basal levels of IL-6, IL-1β and TNF-α. Conversely, a significant association was observed between serum hs-CRP levels and IL-1β and IL-6 production after 24 h of incubation of whole blood with LPS. In conclusion, our data suggest that patients with Type 2 diabetes and high hs-CRP levels may have an enhanced reactivity in response to specific stimuli that produce different interleukins, with possible implications in inflammatory atherosclerotic processes.

To measure actin/myosin protein breakdown, the 24 h excretion of N τ -methylhistidine (3MH) is used. However, in mice, this method is invalid. Therefore we have developed a liquid chromatography-MS technique to measure the tracer/tracee ratio and concentration of 3MH in plasma, enabling an in vivo primed constant infusion protocol with a deuterated stable isotope of 3MH. We tested this model by giving a primed constant infusion of L -[3-methyl- 2 H 3 ]histidine, L -[phenyl- 2 H 5 ]phenylalanine and L -[phenyl- 2 H 2 ]tyrosine to three anaesthetized experimental groups: mice receiving saline intraperitoneally (i.p.) (CON), mice receiving saline i.p. and starved for 9 h (STA), and mice receiving lipopolysaccharide i.p. and starved for 9 h (STA + LPS). The contribution of myofibrillar to total protein breakdown was significantly lower in the STA group than the CON group (30±4% and 54±14% respectively; P <0.05), and was significantly higher in the STA + LPS group than the STA group (52±7% and 30±4% respectively; P <0.05). Whole-body myofibrillar protein breakdown, total protein breakdown, protein synthesis and net protein breakdown were not different between the groups. We conclude that this in vivo primed constant stable isotope-infusion protocol can give valuable information about the role of actin/myosin protein breakdown in mice.

Levels of the endothelium-derived vasoconstrictor endothelin (ET)-1 and the vasodilator nitric oxide (NO) are markedly increased in endotoxic shock, although the pathophysiological role of ET-1 and its relation to NO under septic conditions remains obscure. To delineate the roles of ET-1 and the ET receptors, and the NO/inducible NO synthase (iNOS) system in endotoxic shock, we examined the gene expression of ET-1, ET receptors A and B (ETA and ETB) and iNOS in the heart and the liver of a rat endotoxic shock model, and we studied the effects of ET receptor antagonists on haemodynamics, survival rate and expression of ET-1, ET receptors and iNOS. Administration of bacterial lipopolysaccharide (LPS) into rats caused a profound hypotension with resultant death. However, these effects were blocked by a non-selective ETA/ETB receptor antagonist (TAK044), but not by an ETA-selective antagonist (BQ123). Injection of LPS caused a marked elevation in the plasma levels of both ET-1 and NO, which were not affected by treatment with either ET receptor antagonist. Administration of LPS caused increases in levels of ET-1, ETB and iNOS mRNA in the heart and the liver, whereas ETA mRNA expression was markedly downregulated in these organs. These results suggest that ET receptor subtype genes are differentially regulated in major organs from endotoxic shock rats, and that non-selective ET receptor antagonists ameliorate endotoxin-induced hypotension and death irrespective of iNOS-derived NO.

Glutamine has beneficial effects on enterocytes and the immune system in sepsis, but its effects on hepatic metabolism remain unknown. The aim of the present study was to determine the effects of glutamine on hepatocyte energy metabolism under conditions of neonatal endotoxaemia. Suckling Wistar rats were injected intraperitoneally with 200 μ g/kg lipopolysaccharide. Oxygen consumption was measured polarographically in hepatocytes respiring on either palmitate (0.5mM) or palmitate plus glutamine (10mM). Total hepatocyte oxygen consumption was similar in hepatocytes from control and endotoxic rats, but this was due to a decrease in intramitochondrial and an increase in extramitochondrial oxygen consumption in the cells from endotoxic animals. The addition of glutamine to hepatocytes from endotoxic rats restored intramitochondrial oxygen consumption to control levels. Although glutamine did not reverse the inhibition of the thermogenic proton leak observed in endotoxaemia, it significantly increased oxygen consumption due to mitochondrial ATP synthesis ( P = 0.03). Glutamine significantly increased the hepatocyte ATP/ADP ratio ( P = 0.02 compared with hepatocytes from endotoxic rats). Electron microscopy revealed morphological damage to the mitochondria of hepatocytes from endotoxic rats, and a return to a normal appearance with the addition of glutamine. We conclude that glutamine reverses the inhibition of mitochondrial metabolism that is observed in endotoxaemia. The effect is primarily at the level of ATP synthesis.

The present studies determined the effects of extracellular pH (pH o ) on the production of tumour necrosis factor-α (TNF-α) in the macrophage-like cell lines RAW 246.7 and J774 A.1. The cells were activated with lipopolysaccharide (LPS) at pH o 5.5, 6.5 or 7.4. TNF-α gene transcription was monitored by Northern blot analysis. Synthesis of the cytokine was monitored by ELISA measurements of the TNF-α content of cell-conditioned media (extracellularly released TNF-α) and cell lysates (cytosolic TNF-α). The magnitude of the TNF-α response differed markedly between the two cell lines. RAW cells were more responsive to LPS than were J774 cells. However, the effects of pH o on TNF-α production were similar in the two cell lines. TNF-α gene transcription was insensitive to experimental pH o . The pH o had no effect on the abundance of TNF-α mRNA at 2, 4 or 18 h. Nonetheless, synthesis of TNF-α was affected significantly by pH o . The TNF-α contents of cell-conditioned medium and cell lysate at 18 h were reduced progressively at lower pH o values. The data indicate that pH o alters TNF-α production in RAW and J774 cells at a post-transcriptional level. These findings suggest that pH o influences the phenotypic responses of macrophages to activating stimuli and modifies the role that macrophages play in inflammatory and immune actions.

The aim of the present study was to establish whether gastro-intestinal (GI) complaints observed during and after ultra-endurance exercise are related to gut ischaemia-associated leakage of endotoxins [lipopolysaccharide (LPS)] into the circulation and associated cytokine production. Therefore we collected blood samples from 29 athletes before, immediately after, and 1, 2 and 16 h after a long-distance triathlon for measurement of LPS, tumour necrosis factor-α and interleukin-6 (IL-6). As the cytokine response would trigger an acute-phase response, characteristic variables of these responses were also measured, along with creatine kinase (CK) to obtain an indicator of muscle damage. There was a high incidence (93% of all participants) of GI symptoms; 45% reported severe complaints and 7% of the participants abandoned the race because of severe GI distress. Mild endotoxaemia (5–15 pg/ml) was evident in 68% of the athletes immediately after the race, as also indicated by a reduction in IgG anti-LPS levels. In addition, we observed production of IL-6 (27–fold increase immediately after the race), leading to an acute-phase response (20-fold increase in C-reactive protein and 12% decrease in pre-albumin 16 h after the race). The extent of endotoxaemia was not correlated with the GI complaints or the IL-6 response, but did show a correlation with the elevation in C-reactive protein ( r s 0.389; P = 0.037). Creatine kinase levels were increased significantly immediately post-race, and increased further in the follow-up period. Creatine kinase levels did not correlate with those of either IL-6 or C-reactive protein. It is therefore concluded that LPS does enter the circulation after ultra-endurance exercise and may, together with muscle damage, be responsible for the increased cytokine response and hence GI complaints in these athletes.

1. As lipopolysaccharide is a major stimulator of neutrophil responses during Gram-negative bacterial infections, we studied its effect on the membrane expression of neutral endopeptidase 24.11/CD10 on neutrophils in a model of endotoxaemia in vitro. Lipopolysaccharide added to human whole-blood induced a marked and sustained CD10/neutral endopeptidase upregulation that was already detectable at 0.1 ng/ml and was maximal at a lipopolysaccharide concentration of 10 ng/ml. 2. We observed that neither tumour necrosis factor-α nor any newly synthesized protein was involved in the upregulation observed after 1 h incubation with 10 ng/ml lipopolysaccharide. 3. We further studied whether the lipopolysaccharide-induced CD10/neutral endopeptidase upregulation was mediated by lipopolysaccharide binding to the neutrophil CD14 receptor. Incubation of whole blood with an anti-CD14 monoclonal antibody before the addition of 0.1 ng/ml or 0.5 ng/ml lipopolysaccharide resulted in complete inhibition of CD10/neutral endopeptidase upregulation. In contrast, at a lipopolysaccharide concentration of 10 ng/ml, the anti-CD14 monoclonal antibody had an incomplete blocking effect. 4. The differential requirement for the CD14 receptor, depending on the lipopolysaccharide dose, was confirmed by the study of a patient suffering from paroxysmal nocturnal haemoglobinuria (in whom a complete defect in neutrophil CD14 expression was previously documented) . 5. We finally confirmed these results using purified neutrophils, demonstrating that lipopolysaccharide-induced CD10/neutral endopeptidase upregulation depends on direct interaction with neutrophil CD14.

1. Sepsis is associated with marked changes in cardiac muscle protein synthesis. Such changes may be the result of altered transcription of specific myofibrillar protein mRNAs. 2. In order to investigate myofibrillar protein gene expression, a rat model of sepsis was used. Adult rats were given a single sub-lethal dose of lipopolysaccharide by the intraperitoneal route. At various times thereafter, rats were killed and ventricular muscle was removed. RNA was extracted and transferred to nylon membranes. Changes in expression of mRNA for α- and β-myosin heavy chain, α-actin, cardiac troponin C and carbonic anhydrase III were detected by Northern hybridization. 3. After treatment with lipopolysaccharide, mRNA for β-myosin heavy chain increased to 260% of control values at 24 h and reached a maximum of 310% at 48 h. α-Myosin heavy chain mRNA levels fell to 72% of control values at 24 h. mRNA levels for α-actin, cardiac troponin C and carbonic anhydrase III remained unchanged. 4. In order to investigate the role of tumour necrosis factor-α in this process, some rats were pretreated with monoclonal antibody against tumour necrosis factor-α before receiving lipopolysaccharide. Such animals showed an absence of tumour necrosis factor-α bioactivity in plasma, but changes in myocardial protein mRNA levels were no different from those seen in animals receiving lipopolysaccharide alone. 5. The reduction in protein synthesis in cardiac muscle in sepsis does not appear to be the result of reduced expression of genes for structural or soluble muscle protein. Rather there is a paradoxical increase in β-myosin heavy chain expression, which may represent a protective mechanism. Tumour necrosis factor-α does not appear to be involved in the mediation of these changes.

1. To investigate the role of endothelin in Gram-negative bacteraemia and the possible involvement of tumour necrosis factor-α in its pathophysiology, we measured plasma and tissue (lung, kidney and spleen) immunoreactive endothelin levels in Gram-negative bacteraemic mice, with and without passive immunization by anti-(tumour necrosis factor-α) antibody. 2. Plasma immunoreactive endothelin levels were greatly increased after the Escherichia coli injection. Pre-treatment with anti-(tumour necrosis factor-α) antibody did not suppress elevated plasma immunoreactive endothelin levels ( P > 0.1). 3. Lung tissue immunoreactive endothelin levels in mice were increased 16 h after the E. coli injection and were not affected by prior passive immunization with anti-(tumour necrosis factor-α) antibody. Immunoreactive endothelin in spleen and kidney was undetectable (< 34 fmol/g wet weight). 4. Injection of rMu tumour necrosis factor-α into mice did not increase plasma immunoreactive endothelin levels. 5. Antibody to endothelin given 30 min after a 90% lethal dose challenge with E. coli did not affect mortality. 6. We conclude that the rise in plasma and tissue endothelin that occurs in Gram-negative bacteraemia is independent of tumour necrosis factor-α.

1. An antibactericidal factor in the serum of patients with urinary-tract infection could be partially purified by absorbing the serum with the homologous organism and treating the absorption complex with a weak acid buffer. 2. Material obtained in this way contained mainly immunoglobulin G. 3. Lipopolysaccharide extracted from the homologous organism was as effective as whole bacterial cells in removing the factor from patient's serum.