Tumour necrosis factor in bronchopulmonary secretions of patients with adult respiratory distress syndrome

Simvastatin attenuates inflammatory process on LPS-induced acute lung injury in mice

Acute lung injury (ALI) is a disease of high prevalence and is characterized by the excessive production of inflammatory mediators in the lungs of people sick. Inflammation is the major characteristic of ALI and studies report that inhibition of inflammatory cytokines could be an alternative treatment. Statins such as Simvastatin (SV) are known to their use for cholesterol reduction but also for inflammatory and immunoregulatory processes. In this study, we evaluated the effects of SV on LPS-induced alveolar macrophages and in ALI mice model. Our study has demonstrated the protective effects of SV on LPS-activated alveolar macrophages RAW 264.7 and LPS-induced ALI in mice. SV treatment significantly inhibited the alveolar macrophages activation by decreasing the iNOS, IL-1β, and IL-6 gene expression in vitro and in vivo. The treatment also decreased the inflammatory cells migration and the cytokines gene expression. Our findings suggest that SV can act as an anti-inflammatory agent for acute lung injury.

Effects of tocilizumab and dexamethasone on the downregulation of proinflammatory cytokines and upregulation of antioxidants in the lungs in oleic acid-induced ARDS

Background

Acute respiratory distress syndrome (ARDS) is a life-threatening disease caused by the induction of inflammatory cytokines and chemokines in the lungs. There is a dearth of drug applications that can be used to prevent cytokine storms in ARDS treatment. This study was designed to investigate the effects of tocilizumab and dexamethasone on oxidative stress, antioxidant parameters, and cytokine storms in acute lung injury caused by oleic acid in rats.

Methods

Adult male rats were divided into five groups: the CN (healthy rats, n = 6), OA (oleic acid administration, n = 6), OA + TCZ-2 (oleic acid and tocilizumab at 2 mg/kg, n = 6), OA + TCZ-4 (oleic acid and tocilizumab at 4 mg/kg, n = 6), and OA + DEX-10 (oleic acid and dexamethasone at 10 mg/kg, n = 6) groups. All animals were euthanized after treatment for histopathological, immunohistochemical, biochemical, PCR, and SEM analyses.

Results

Expressions of TNF-α, IL-1β, IL-6, and IL-8 cytokines in rats with acute lung injury induced by oleic acid were downregulated in the TCZ and DEX groups compared to the OA group (P < 0.05). The MDA level in lung tissues was statistically lower in the OA + TCZ-4 group compared to the OA group. It was further determined that SOD, GSH, and CAT levels were decreased in the OA group and increased in the TCZ and DEX groups (P < 0.05). Histopathological findings such as thickening of the alveoli, hyperemia, and peribronchial cell infiltration were found to be similar when lung tissues of the TCZ and DEX groups were compared to the control group. With SEM imaging of the lung tissues, it was found that the alveolar lining layer had become indistinct in the OA, OA + TCZ-2, and OA + TCZ-4 groups.

Conclusions

In this model of acute lung injury caused by oleic acid, tocilizumab and dexamethasone were effective in preventing cytokine storms by downregulating the expression of proinflammatory cytokines including TNF-α, IL-1β, IL-6, and IL-8. Against the downregulation of antioxidant parameters such as SOD and GSH in the lung tissues caused by oleic acid, tocilizumab and dexamethasone upregulated them and showed protective effects against cell damage.

Evaluation of cytokine response to extracorporeal membrane oxygenation

RATIONALE

Increased cytokine response is common in patients receiving extracorporeal life support and is often a poor prognostic indicator. There is interest in using adjunctive cytokine adsorption technologies to reduce inflammatory burden, However, it is debated whether extracorporeal membrane oxygenation (ECMO) itself provides therapeutic benefit beyond gas exchange. Thus, we sought to characterize the inflammatory profile of ECMO in the first 72-96 h of and quantify its effect on cytokine levels in a case series of patients undergoing ECMO.

METHODS

Eight patients initiating ECMO were studied. Of these, we measured cytokines pre- and post-oxygenator over 96 h. Comparisons of cytokine levels were made across the oxygenator and over time.

RESULTS

The average age of patients was 64.3 years with 62% being male. Centrally cannulated patients had higher IL-6 levels (820.43 vs. 6907.53 pg/ml, p < 0.03), whereas peripherally cannulated patients had higher IL-12p70 levels (7.73 vs. 2.59 pg/ml, p < 0.05). Cytokine levels on day one included IL-12p70 (4.17 ± 2.56), IL-6 (4971.23 ± 8569.88), TNF (undetected), IL-8 (346.68 ± 670.18), IL-1B (undetected), and IL-10 (72.27 ± 87.9). Cytokine levels increased over 96 h; however, no significant differences were appreciated despite blood product transfusion. On day 3, IL-12p70 levels were significantly lower post-oxygenator (p < 0.05).

CONCLUSION

The inflammatory profile of ECMO does not change significantly over the early course of illness when accounting for transfusion. However, the decrease in IL-12p70 specifically at day 3 of ECMO may indicate adsorption of specific inflammatory markers by the oxygenator although the clinical significance of this is still unknown. Further investigation of the oxygenator on cytokine response is warranted.

Reevaluation of Lung Injury in TNF-Induced Shock: The Role of the Acid Sphingomyelinase

Tumor necrosis factor (TNF) is a well-known mediator of sepsis. In many cases, sepsis results in multiple organ injury including the lung with acute respiratory distress syndrome (ARDS). More than 20-year-old studies have suggested that TNF may be directly responsible for organ injury during sepsis. However, these old studies are inconclusive, because they relied on human rather than conspecific TNF, which was contaminated with endotoxin in most studies. In this study, we characterized the direct effects of intravenous murine endotoxin-free TNF on cardiovascular functions and organ injury in mice with a particular focus on the lungs. Because of the relevance of the acid sphingomyelinase in sepsis, ARDS, and caspase-independent cell death, we also included acid sphingomyelinase-deficient (ASM^−/−) mice. ASM^−/− and wild-type (WT) mice received 50 μg endotoxin-free murine TNF intravenously alone or in combination with the pan-caspase inhibitor carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone (zVAD) and were ventilated at low tidal volume while lung mechanics were followed. Blood pressure was stabilized by intra-arterial fluid support, and body temperature was kept at 37°C to delay lethal shock and to allow investigation of blood gases, lung histopathology, proinflammatory mediators, and microvascular permeability 6 hours after TNF application. Besides the lungs, also the kidneys and liver were examined. TNF elicited the release of inflammatory mediators and a high mortality rate, but failed to injure the lungs, kidneys, or liver of healthy mice significantly within 6 hours. Mortality in WT mice was most likely due to sepsis-like shock, as indicated by metabolic acidosis, high procalcitonin levels, and cardiovascular failure. ASM^−/− mice were protected from TNF-induced hypotension and reflex tachycardia and also from mortality. In WT mice, intravenous exogenous TNF does not cause organ injury but induces a systemic inflammatory response with cardiovascular failure, in which the ASM plays a role.

Soluble programmed cell death receptor-1 (sPD-1): a potential biomarker with anti-inflammatory properties in human and experimental acute respiratory distress syndrome (ARDS)

Background

Acute respiratory distress syndrome (ARDS) remains a common organ dysfunction in the critically ill patient. Mechanisms for its development have focused on immune mediated causes, aspects of our understanding are not complete, and we lack biomarkers.

Design, setting, and subjects

Blood and bronchial alveolar lavage fluid (BAL) from humans (n = 10–13) with ARDS and controls (n = 5–10) as well as a murine model of ARDS (n = 5–6) with controls (n = 6–7) were studied.

Methods

ARDS was induced in mice by hemorrhagic shock (day 1) followed by poly-microbial sepsis (day 2). Samples were then collected on the third day after the animals were euthanized. Ex vivo experiments used splenocytes from animals with ARDS cultured with and without soluble programmed death receptor-1 (sPD-1).

Results

Levels of sPD-1 are increased in both the serum (11,429.3 pg/mL(SD 2133.3) vs. 8061.4(SD 4187.8), p = 0.036) and bronchial alveolar lavage (BAL) fluid (6,311.1 pg/mL(SD 3758.0) vs. 90.7 pg/mL(SD 202.8), p = 0.002) of humans with ARDS. Similar results are seen in the serum (9396.1 pg/mL(SD 1546.0) vs. 3464.5 pg/mL(SD 2511.8), p = 0.001) and BAL fluid (2891.7 pg/mL(SD 868.1) vs. 1385.9 pg/mL(SD 927.8), p = 0.012) of mice. sPD-1 levels in murine blood (AUC = 1(1–1), p = 0.006), murine BAL fluid (AUC = 0.905(0.717–1.093), p = 0.015), and human BAL (AUC = 1(1–1), p = 0.001) fluid predicted ARDS. To assess the importance of sPD-1 in ARDS, ex vivo experiments were undertaken. BAL fluid from mice with ARDS dampens the TNF-α production compared to cells cultured with BAL lacking sPD-1 (2.7 pg/mL(SD 3.8) vs. 52.38 pg/mL(SD 25.1), p = 0.002).

Conclusions

This suggests sPD-1 is elevated in critical illness and may represent a potential biomarker for ARDS. In addition, sPD-1 has an anti-inflammatory mechanism in conditions of marked stress and aids in the resolution of severe inflammation. sPD-1 could be used to not only diagnose ARDS, but may be a potential therapy.

Src Family Kinases Modulate the Loss of Endothelial Barrier Function in Response to TNF-α: Crosstalk with p38 Signaling

Activation of Src Family Kinase (SFK) signaling is required for the increase in endothelial permeability induced by a variety of cytokines and growth factors. However, we previously demonstrated that activation of endogenous SFKs by expression of dominant negative C-terminal Src Kinase (DN-Csk) is not sufficient to decrease endothelial adherens junction integrity. Basal SFK activity has been observed in normal venular endothelia and was not associated with increased basal permeability. The basal SFK activity however was found to contribute to increased sensitivity of the venular endothelium to inflammatory mediator-induced leakage. How SFK activation achieves this is still not well understood. Here, we show that SFK activation renders human dermal microvascular endothelial cells susceptible to low doses of TNF-α. Treatment of DN-Csk-expressing cells with 50 pg/ml TNF-α induced a loss of TEER as well as drastic changes in the actin cytoskeleton and focal adhesion proteins. This synergistic effect was independent of ROCK or NF-κB activity. TNF-α-induced p38 signaling was required for the synergistic effect on barrier function, and activation of the p38 MAPK alone was also able to induce changes in permeability only in monolayers with active SFKs. These results suggest that the activation of endogenous levels of SFK renders the endothelial barrier more susceptible to low, physiologic doses of TNF-α through activation of p38 which leads to a loss of endothelial tight junctions.

Invited review: Compartmentalization of the inflammatory response in sepsis and SIRS

Sepsis and systemic inflammatory response syndrome (SIRS) are associated with an exacerbated production of both pro- and anti-inflammatory mediators that are mainly produced within tissues. Although a systemic process, the pathophysiological events differ from organ to organ, and from organ to peripheral blood, leading to the concept of compartmentalization. The nature of the insult ( e.g. burn, hemorrhage, trauma, peritonitis), the cellular composition of each compartment ( e.g . nature of phagocytes, nature of endothelial cells), and its micro-environment ( e.g. local presence of granulocyte-macrophage colony stimulating factor [GM-CSF] in the lungs, low levels of arginine in the liver, release of endotoxin from the gut), and leukocyte recruitment, have a great influence on local inflammation and on tissue injury. High levels of pro-inflammatory mediators ( e.g. interleukin-1 [IL-1], tumor necrosis factor [TNF], gamma interferon [IFN-γ], high mobility group protein-1 [HMGB1], macrophage migration inhibitory factor [MIF]) produced locally and released into the blood stream initiate remote organ injury as a consequence of an organ cross-talk. The inflammatory response within the tissues is greatly influenced by the local delivery of neuromediators by the cholinergic and sympathetic neurons. Acetylcholine and epinephrine contribute with IL-10 and other mediators to the anti-inflammatory compensatory response initiated to dampen the inflammatory process. Unfortunately, this regulatory response leads to an altered immune status of leukocytes that can increase the susceptibility to further infection. Again, the nature of the insult, the nature of the leukocytes, the presence of circulating microbial components, and the nature of the triggering agent employed to trigger cells, greatly influence the immune status of the leukocytes that may differ from one compartment to another. While anti-inflammatory mediators predominate within the blood stream to avoid igniting new inflammatory foci, their presence within tissues may not always be sufficient to prevent the initiation of a deleterious inflammatory response in the different compartments.

Pulmonary Expression of Tumor Necrosis Factor Alpha, Interleukin-1 Beta, and Interleukin-8 in the Acute Phase of Bovine Pneumonic Pasteurellosis

Inflammatory cytokines are suspected to contribute to the pathogenesis of bovine pneumonic pasteurellosis (BPP) through neutrophil recruitment, leukocyte activation, and the induction of a broad array of soluble inflammatory mediators. An in vivo experimental model of BPP was used to characterize the pulmonary expression kinetics of tumor necrosis factor alpha (TNFα), interleukin-1 beta (IL-1β), and interleukin-8 (IL-8) genes and proteins during the acute phase of disease development. Cytokine expression in bronchoalveolar lavage (BAL) fluid, BAL cells, and pneumonic lung parenchyma was quantitated by northern blot analysis, enzyme-linked immunosorbent assay (ELISA), and in situ hybridization at 2, 4, 8, 16, and 24 hours after endobronchial inoculation of Pasteurella (Mannheimia) haemolytica. Expression of TNFα, IL-1β, and IL-8 was significantly increased in the airways and lung lesions of infected calves as compared with mock-infected controls. Although kinetic patterns varied, peak levels of cytokine mRNA occurred within 8 hours postinfection (PI), and peak cytokine concentrations occurred within 16 hours PI. In all samples, IL-8 was expressed to the greatest extent and TNFα was least expressed. Expression of TNFα was restricted to alveolar macrophages. Alveolar and interstitial macrophages produced IL-1β and IL-8 in the first 4 hours; bronchial and bronchiolar epithelial cells were also significant sources of IL-8 during this period. By 8 hours PI, neutrophils were the dominant source of both IL-1β and IL-8. These findings demonstrate a spatial and temporal association between pulmonary expression of inflammatory cytokines and acute lung pathology, supporting the hypothesis that cytokines contribute to inflammatory lung injury in BPP.

Inhibition of Acute Lung Injury by TNFR-Fc through Regulation of an Inflammation-Oxidative Stress Pathway

Background

Acute lung injury (ALI), characterized by disruption of the lung alveolar-capillary membrane barrier and resultant pulmonary edema, and associated with a proteinaceous alveolar exudate, is a leading cause of morbidity and mortality. Currently, inflammation-oxidative stress interaction between TNF-α and NF-κB was identified as a key pathway of ALI. We hypothesized that a TNFR-Fc fusion protein would have beneficial effects in experimental ALI, and sought to test this idea in mice by blocking TNF-α.

Methods and Results

Intratracheal instillation of lipopolysaccharide (LPS) into the lungs of ALI mice led to histiocyte apoptosis, and detection of serum and bronchoalveolar lavage fluid (BALF) cytokines, feedback between NF-κB and TNF-α, lung albumin leakage, lung damage, IκB kinase (IKK) and NF-κB activation, I-κB degradation, and oxidative injury. LPS administration raised pulmonary inflammation as reflected by increased inflammatory cytokines, alveoli protein concentration, and ALI scores. IKK is phosphorylated following LPS challenge, leading to I-κB degradation and NF-κB p65 phosphorylation. Furthermore, NF-κB is translocated into the nucleus and up-regulates TNF-α gene transcription. Infusion of TNFR-Fc 24h before LPS challenge significantly abrogated the increase of inflammatory cytokines, especially serum TNF-α concentration, as well as pulmonary alveoli protein levels, and diminished IKK and NF-κB activation and I-κB degradation. The nuclear translocation of NF-κB was inhibited, following by down-regulation of TNF-α gene transcription. In addition, LPS intratracheal instillation induced marked oxidative damage, such as a decrease in total anti-oxidation products and an increase in malondialdehyde (MDA), as well as up-regulation of oxidation enzymes. Histologic analysis and apoptosis scores revealed that the extent of tissue lesions was significantly reduced, but not abrogated, by TNF-α blockade.

Conclusion

Treatment with LPS alone increased inflammation and oxidative stress in ALI mice, while administration of TNFR-Fc 24h before LPS challenge broke the feedback between NF-κB and TNF-α, resulting in decreased pulmonary inflammation/oxidative damage and tissue destruction. These results suggest a potential role for TNF-α therapy to treat clinical ALI.

Activation of EP4 receptors prevents endotoxin-induced neutrophil infiltration into the airways and enhances microvascular barrier function

BACKGROUND AND PURPOSE

Pulmonary vascular dysfunction is a key event in acute lung injury. We recently demonstrated that PGE₂ , via activation of E-prostanoid (EP)₄ receptors, strongly enhances microvascular barrier function in vitro. The aim of this study was to investigate the beneficial effects of concomitant EP₄ receptor activation in murine models of acute pulmonary inflammation.

EXPERIMENTAL APPROACH

Pulmonary inflammation in male BALB/c mice was induced by LPS (20 μg per mouse intranasally) or oleic acid (0.15 μL·g^-1 , i.v^. ). In-vitro, endothelial barrier function was determined by measuring electrical impedance.

KEY RESULTS

PGE₂ activation of EP₄ receptors reduced neutrophil infiltration, pulmonary vascular leakage and TNF-α concentration in bronchoalveolar lavage fluid from LPS-induced pulmonary inflammation. Similarly, pulmonary vascular hyperpermeability induced by oleic acid was counteracted by EP₄ receptor activation. In lung function assays, the EP₄ agonist ONO AE1-329 restored the increased resistance and reduced compliance upon methacholine challenge in mice treated with LPS or oleic acid. In agreement with these findings, EP₄ receptor activation increased the in vitro vascular barrier function of human and mouse pulmonary microvascular endothelial cells and diminished the barrier disruption induced by LPS. The EP₂ agonist ONO AE1-259 likewise reversed LPS-induced lung dysfunction without enhancing vascular barrier function.

CONCLUSION AND IMPLICATIONS

Our results show that activation of the EP₄ receptor strengthens the microvascular barrier function and thereby ameliorates the pathology of acute lung inflammation, including neutrophil infiltration, vascular oedema formation and airway dysfunction. This suggests a potential benefit for EP₄ agonists in acute pulmonary inflammation.

Two cases of acute respiratory distress syndrome resulting from adult-onset Still's disease

Abstract Adult-onset Still's disease (AOSD) is a systemic inflammatory disorder of unknown origin. Acute respiratory distress syndrome (ARDS) is a rare complication of AOSD, with only nine cases having been reported in the literature. Here, we describe two cases of AOSD complicated with ARDS that were successfully treated with immunosuppressive therapy, including corticosteroids. Although ARDS is a life-threatening complication in AOSD, early commencement of high-dose corticosteroids and mechanical ventilation improve the prognosis.

A critical role for phosphatidylinositol (3,4,5)-trisphosphate-dependent Rac exchanger 1 in endothelial junction disruption and vascular hyperpermeability

RATIONALE

The small GTPase Rac is critical to vascular endothelial functions, yet its regulation in endothelial cells remains unclear. Understanding the upstream pathway may delineate Rac activation mechanisms and its role in maintaining vascular endothelial barrier integrity.

OBJECTIVE

By investigating phosphatidylinositol (3,4,5)-trisphosphate-dependent Rac exchanger 1 (P-Rex1), one of the Rac-specific guanine nucleotide exchange factors previously known for G protein-coupled receptor signaling, we sought to determine whether Rac-guanine nucleotide exchange factor is nodal for signal integration and potential target for drug intervention.

METHODS AND RESULTS

Using gene deletion and small interference RNA silencing approach, we investigated the role of P-Rex1 in human lung microvascular endothelial cells. Tumor necrosis factor α (TNF-α) exposure led to disruption of endothelial junctions, and silencing P-Rex1 protected junction integrity. TNF-α stimulated Rac activation and reactive oxygen species production in a P-Rex1-dependent manner. Removal of P-Rex1 significantly reduced intercellular adhesion molecule-1 expression, polymorphonuclear leukocyte transendothelial migration, and leukocyte sequestration in TNF-α-challenged mouse lungs. The P-Rex1 knockout mice were also refractory to lung vascular hyperpermeability and edema in a lipopolysaccharide-induced sepsis model.

CONCLUSIONS

These results demonstrate for the first time that P-Rex1 expressed in endothelial cells is activated downstream of TNF-α, which is not a G protein-coupled receptor agonist. Our data identify P-Rex1 as a critical mediator of vascular barrier disruption. Targeting P-Rex1 may effectively protect against TNF-α- and lipopolysaccharide-induced endothelial junction disruption and vascular hyperpermeability.

Sevoflurane reduces severity of acute lung injury possibly by impairing formation of alveolar oedema

Pulmonary oedema is a hallmark of acute lung injury (ALI), consisting of various degrees of water and proteins. Physiologically, sodium enters through apical sodium channels (ENaC) and is extruded basolaterally by a sodium-potassium-adenosine-triphosphatase pump (Na(+) /K(+) -ATPase). Water follows to maintain iso-osmolar conditions and to keep alveoli dry. We postulated that the volatile anaesthetic sevoflurane would impact oedema resolution positively in an in-vitro and in-vivo model of ALI. Alveolar epithelial type II cells (AECII) and mixed alveolar epithelial cells (mAEC) were stimulated with 20 µg/ml lipopolysaccharide (LPS) and co-exposed to sevoflurane for 8 h. In-vitro active sodium transport via ENaC and Na(+) /K(+) -ATPase was determined, assessing (22) sodium and (86) rubidium influx, respectively. Intratracheally applied LPS (150 µg) was used for the ALI in rats under sevoflurane or propofol anaesthesia (8 h). Oxygenation index (PaO(2) /FiO(2) ) was calculated and lung oedema assessed determining lung wet/dry ratio. In AECII LPS decreased activity of ENaC and Na(+) /K(+) -ATPase by 17·4% ± 13·3% standard deviation and 16·2% ± 13·1%, respectively. These effects were reversible in the presence of sevoflurane. Significant better oxygenation was observed with an increase of PaO(2) /FiO(2) from 189 ± 142 mmHg to 454 ± 25 mmHg after 8 h in the sevoflurane/LPS compared to the propofol/LPS group. The wet/dry ratio in sevoflurane/LPS was reduced by 21·6% ± 2·3% in comparison to propofol/LPS-treated animals. Sevoflurane has a stimulating effect on ENaC and Na(+) /K(+) -ATPase in vitro in LPS-injured AECII. In-vivo experiments, however, give strong evidence that sevoflurane does not affect water reabsorption and oedema resolution, but possibly oedema formation.

Mechanisms of indirect acute lung injury: a novel role for the coinhibitory receptor, programmed death-1

OBJECTIVE

To determine the contribution of programmed death receptor (PD)-1 in the morbidity and mortality associated with the development of indirect-acute lung injury.

BACKGROUND

The immune cell interaction(s) leading to indirect-acute lung injury are not completely understood. In this respect, we have recently shown that the murine cell surface coinhibitory receptor, PD-1, has a role in septic morbidity/mortality that is mediated in part through the effects on the innate immune arm. However, it is not know if PD-1 has a role in the development of indirect-acute lung injury and how this may be mediated at a cellular level.

METHODS

PD-1 -/- mice were used in a murine model of indirect-acute lung injury (hemorrhagic shock followed 24 hours after with cecal ligation and puncture-septic challenge) and compared to wild type controls. Groups were initially compared for survival and subsequently for markers of pulmonary inflammation, influx of lymphocytes and neutrophils, and expression of PD-1 and its ligand-PD-L1. In addition, peripheral blood leukocytes of patients with indirect-acute lung injury were examined to assess changes in cellular PD-1 expression relative to mortality.

RESULTS

PD-1 -/- mice showed improved survival compared to wild type controls. In the mouse lung, CD4+, CD11c+, and Gr-1+ cells showed increased PD-1 expression in response to indirect-acute lung injury. However, although the rise in bronchial alveolar lavage fluid protein concentrations, lung IL-6, and lung MCP-1 were similar between PD-1 -/- and wild type animals subjected to indirect acute lung injury, the PD-1 -/- animals that were subjected to shock/septic challenge had reduced CD4:CD8 ratios, TNF-α levels, MPO activity, and Caspase 3 levels in the lung. Comparatively, we observed that humans, who survived their acute lung injury, had significantly lower expression of PD-1 on T cells.

CONCLUSIONS

PD-1 expression contributes to mortality after the induction of indirect-acute lung injury and this seems to be associated with modifications in the cellular and cytokine profiles in the lung.

Surfactant administration prior to one lung ventilation: physiological and inflammatory correlates in a piglet model

OBJECTIVES

To test the hypothesis that surfactant, when given prophylactically during one lung ventilation (OLV), improves physiological stability and reduces inflammation.

METHODS

Prospective controlled animal study. After 30 min of mechanical ventilation, surfactant was administered to the left lung of the treatment group. Right lung mechanical ventilation continued for 3 hr, after which the left lung was unblocked. Bilateral mechanical ventilation was continued for 30 min thereafter. Physiological parameters and biomarkers of inflammation in plasma, lung tissue homogenates, and bronchoalveolar lavage (BAL) were measured.

MEASUREMENTS AND MAIN RESULTS

Oxygenation improved in the surfactant group, reaching statistical significance at 3 hr of OLV and again after 30 min of bilateral mechanical ventilation following the OLV. Plasma levels of interleukin (IL)-1 β, IL-6, and tumor necrosis factor (TNF)-α showed a trend for reduction. The lung homogenates from the ventilated lungs had significantly lower levels of IL-1 β (P < 0.01) and IL-6 (P < 0.01). The BAL specimen showed an overall reduction in the cytokine levels; IL-1 β was significantly lower in the ventilated lungs (P < 0.01).

CONCLUSIONS

Surfactant administration improves oxygenation and decreases inflammation, as evidenced by a decrease in several inflammatory cytokines both in the plasma and lungs of a piglet model of OLV.

HMGB1 induces human lung endothelial cell cytoskeletal rearrangement and barrier disruption

Acute lung injury (ALI) results from loss of alveolar-capillary barrier integrity and the evolution of high-permeability pulmonary edema resulting in alveolar flooding and significant morbidity and mortality. HMGB1 is a late mediator of sepsis which uniquely participates in the evolution of sepsis and sepsis-induced ALI. The molecular events by which HMGB1 contributes to ALI remain poorly characterized. We characterized the role of HMGB1 in endothelial cell (EC) cytoskeletal rearrangement and vascular permeability, events essential to paracellular gap formation and barrier dysfunction characteristic of ALI. Initial experiments demonstrated HMGB1-mediated dose-dependent (5-20 μg/ml) decreases in transendothelial cell electrical resistance (TER) in the human pulmonary artery EC, a reflection of loss of barrier integrity. Furthermore, HMGB1 produced dose-dependent increases in paracellular gap formation in concert with loss of peripheral organized actin fibers, dissociation of cell-cell junctional cadherins, and the development of central stress fibers, a phenotypic change associated with increased contractile activity and increased EC permeability. Using siRNA strategies directed against known HMGB1 receptors (RAGE, TLR2, TLR4), we systematically determined that the receptor for advanced glycation end products (RAGE) is the primary receptor signaling HMGB1-induced TER decreases and paracellular gap formation via p38 MAP kinase activation and phosphorylation of the actin-binding protein, Hsp27. These studies add to the understanding of HMGB1-induced inflammatory events and vascular barrier disruption and offer the potential for clinical intervention in sepsis-induced ALI.

Tumor necrosis factor alpha -308 gene locus promoter polymorphism: an analysis of association with health and disease

Tumor necrosis factor-alpha (TNF-alpha) is a potent immunomediator and proinflammatory cytokine that has been implicated in the pathogenesis of a large number of human diseases. The location of its gene within major histocompatibility complex and biological activities has raised the possibility that polymorphisms within this locus may contribute to the pathogenesis of wide range of autoimmune and infectious diseases. For example, a bi-allelic single nucleotide substitution of G (TNFA1 allele) with A (TNFA2 allele) polymorphism at -308 nucleotides upstream from the transcription initiation site in the TNF-alpha promoter is associated with elevated TNF-alpha levels and disease susceptibilities. However, it is still unclear whether TNF-alpha -308 polymorphism plays a part in the disease process, in particular whether it could affect transcription factor binding and in turn influence TNF-alpha transcription and synthesis. Several studies have suggested that TNFA2 allele is significantly linked with the high TNF-alpha-producing autoimmune MHC haplotype HLA-A1, B8, DR3, with elevated serum TNF-alpha levels and a more severe outcome in diseases. This review discusses the genetics of the TNF-alpha -308 polymorphism in selected major diseases and evaluates its common role in health and disease.

Bovine herpesvirus type 1 infection of bovine bronchial epithelial cells increases neutrophil adhesion and activation

Respiratory infection of cattle with bovine herpesvirus type 1 (BHV-1) predisposes cattle to secondary pneumonia with Mannheimia haemolytica as part of the bovine respiratory disease complex (BRD). One cell type that has received limited investigation for its role in the inflammation that accompanies BRD is the respiratory epithelial cell. In the present study we investigated mechanisms by which BHV-1 infection of respiratory epithelial cells contributes to the recruitment and activation of bovine polymorphonuclear neutrophils (PMNs) in vitro. Primary cultures of bovine bronchial epithelial (BBE) cells were infected with BHV-1 and assessed for cytokine expression by real-time PCR. We found that BHV-1 infection elicits a rapid IL-1, IL-8 and TNF-alpha mRNA response by BBE cells. Bovine PMNs exhibited greater adherence to BHV-1 infected BBE cells than uninfected cells. The increased adherence was significantly reduced by the addition of an anti-IL-1beta antibody or human soluble TNF-alpha receptor (sTNF-alphaR). Pre-incubation of bovine PMNs with conditioned media from BHV-1 infected BBE cells increased PMN migration, which was inhibited by addition of an anti-IL-1beta antibody, sTNF-alphaR, or an IL-8 peptide inhibitor. Conditioned media from BHV-1 infected BBE cells activated bovine PMNs in vitro as demonstrated by PMN shape change, production of reactive oxygen species and degranulation. PMNs also exhibited increased LFA-1 expression and susceptibility to M. haemolytica LKT following incubation with BHV-1 infected BBE cell conditioned media. Our results suggest that BHV-1 infection of BBE cells triggers cytokine expression that contributes to the recruitment and activation of neutrophils, and amplifies the detrimental effects of M. haemolytica LKT.

Anti-tumour necrosis factor-alpha therapy in heart failure: future directions

The elevated level of tumour necrosis factor-alpha (TNF-alpha) in patients with heart failure has triggered interest in investigating the role of TNF-alpha in the pathogenesis of heart failure. Both clinical and experimental evidence has suggested that high levels of TNF-alpha occur in heart failure and lead to progression of left ventricular dysfunction. In addition, it has been documented that inhibition of TNF-alpha reverses its deleterious effects in heart failure. A number of clinical trials have been initiated to investigate the effect of anti-TNF-alpha therapy in patients with heart failure. The discouraging results of recent clinical trials of anti-TNF-alpha therapy in patients with heart failure have raised a number of questions about the role of TNF-alpha in heart failure. The present review critically analyzes the reasons of failure of anti-TNF-alpha therapy in heart failure. Moreover the potential approaches for the development of new anti-TNF-alpha therapy has been discussed which may open new vista of the management of heart failure.

TNF-alpha increases tyrosine phosphorylation of vascular endothelial cadherin and opens the paracellular pathway through fyn activation in human lung endothelia

Tumor necrosis factor (TNF)-alpha is a key mediator of sepsis-associated multiorgan failure, including the acute respiratory distress syndrome. We examined the role of protein tyrosine phosphorylation in TNF-alpha-induced pulmonary vascular permeability. Postconfluent human lung microvascular and pulmonary artery endothelial cell (EC) monolayers exposed to human recombinant TNF-alpha displayed a dose- and time-dependent increase in transendothelial [(14)C]albumin flux in the absence of EC injury. TNF-alpha also increased tyrosine phosphorylation of EC proteins, and several substrates were identified as the zonula adherens proteins vascular endothelial (VE)-cadherin, and beta-catenin, gamma-catenin, and p120 catenin (p120(ctn)). Prior protein tyrosine kinase (PTK) inhibition protected against the TNF-alpha effect. TNF-alpha activated multiple PTKs, including src family PTKs. Prior PTK inhibition with the src-selective agents PP1 and PP2 each protected against approximately 60% of the TNF-alpha-induced increment in [(14)C]albumin flux. PP2 also blocked TNF-alpha-induced tyrosine phosphorylation of VE-cadherin, gamma-catenin, and p120(ctn). To identify which src family kinase(s) was required for TNF-alpha-induced vascular permeability, small interfering RNA (siRNA) targeting each of the three src family PTKs expressed in human EC, c-src, fyn, and yes, were introduced into the barrier function assay. Only fyn siRNA protected against the TNF-alpha effect, whereas the c-src and yes siRNAs did not. These combined data suggest that TNF-alpha regulates the pulmonary vascular endothelial paracellular pathway, in part, through fyn activation.

Signaling Mechanisms Regulating Endothelial Permeability

The microvascular endothelial cell monolayer localized at the critical interface between the blood and vessel wall has the vital functions of regulating tissue fluid balance and supplying the essential nutrients needed for the survival of the organism. The endothelial cell is an exquisite “sensor” that responds to diverse signals generated in the blood, subendothelium, and interacting cells. The endothelial cell is able to dynamically regulate its paracellular and transcellular pathways for transport of plasma proteins, solutes, and liquid. The semipermeable characteristic of the endothelium (which distinguishes it from the epithelium) is crucial for establishing the transendothelial protein gradient (the colloid osmotic gradient) required for tissue fluid homeostasis. Interendothelial junctions comprise a complex array of proteins in series with the extracellular matrix constituents and serve to limit the transport of albumin and other plasma proteins by the paracellular pathway. This pathway is highly regulated by the activation of specific extrinsic and intrinsic signaling pathways. Recent evidence has also highlighted the importance of the heretofore enigmatic transcellular pathway in mediating albumin transport via transcytosis. Caveolae, the vesicular carriers filled with receptor-bound and unbound free solutes, have been shown to shuttle between the vascular and extravascular spaces depositing their contents outside the cell. This review summarizes and analyzes the recent data from genetic, physiological, cellular, and morphological studies that have addressed the signaling mechanisms involved in the regulation of both the paracellular and transcellular transport pathways.

Contribution of TNF-alpha converting enzyme and proteinase-3 to TNF-alpha processing in human alveolar macrophages

Membrane-associated TNF-alpha cleavage is required to yield the 17.5-kD soluble product. This process is poorly understood in human cells, and no studies have related this process to the alveolar macrophage (AM). TNF-alpha-converting enzyme (TACE) is known to cleave TNF at the Ala-76-Val-77 site. We have evaluated the expression, regulation, and catalytic function of TACE in healthy human AMs. TACE was detected on the surface of AMs using flow cytometry. TACE protein can be upregulated by LPS (P = 0.036) and IFN-gamma. LPS-induced expression is downregulated by IL-10 (P = 0.04) and TNF-alpha. TACE regulation was observed at the mRNA level. TACE catalytic activity as assessed by cleavage of glutathione S-transferase-proTNF fusion protein correlates significantly with TACE protein expression (P = 0.04). However, cleavage and soluble TNF-alpha release by AMs was inhibited by matrix metalloproteinase and serine protease inhibitors, suggesting a role for a serine protease in this process. We confirmed the presence of proteinase-3 (PR-3) on the AM surface that was functionally capable of TNF cleavage. PR-3 mRNA expression was not found in AMs. However, we determined that PR-3 from neutrophil supernatants could bind to the AM membrane, suggesting that AM-derived PR-3 is from an exogenous source, which is important in the context of inflammation.

Aspiration pneumonitis primes the host for an exaggerated inflammatory response during pneumonia

OBJECTIVE

Nosocomial pneumonia is a feared complication in the critically ill patient. Aspiration pneumonitis is frequently complicated by infections. The objective of this study was to determine the influence of aspiration pneumonitis on the host response to a common nosocomial respiratory pathogen.

DESIGN

Controlled, in vivo laboratory study.

SETTING

Research laboratory of a health sciences university.

SUBJECTS

Female C57Bl/6 mice.

INTERVENTIONS

Mice received hydrochloric acid or saline intratracheally followed 16 hrs later by Klebsiella pneumoniae.

MEASUREMENTS AND MAIN RESULTS

Hydrochloric acid induced a mild aspiration pneumonitis. Nonetheless, hydrochloric acid aspiration resulted in a markedly increased inflammatory response in the lung on infection with K. pneumoniae. This enhanced inflammatory reaction was accompanied by a greatly increased outgrowth of K. pneumoniae in lungs of mice previously exposed to hydrochloric acid. Preexisting aspiration pneumonitis also triggered mouse lungs in vivo and alveolar macrophages ex vivo for enhanced release of proinflammatory mediators on stimulation with Klebsiella lipopolysaccharide. Inhibition of tumor necrosis factor-alpha resulted in an increased inflammatory reaction and enhanced bacterial outgrowth in mice with primary K. pneumoniae pneumonia, whereas it had no effect in mice with preexisting aspiration pneumonitis.

CONCLUSIONS

These data indicate a) that aspiration pneumonitis renders the host more susceptible to respiratory tract infection with K. pneumoniae, concurrently priming the lung for an exaggerated inflammatory response; and b) that although tumor necrosis factor-alpha plays a major role in the host response to primary infection, it does not affect lung inflammation or defense after aspiration pneumonitis.

JTE-607, a cytokine release blocker, attenuates acid aspiration-induced lung injury in rats

The present study was designed to clarify the effects of (-)-ethyl N-[3,5-dichloro-2-hydroxy-4-[2-(4-methyl-piperazin-1-yl)ethoxy]benzoyl]-l-phenylalaninate dihydrochloride (JTE-607), a novel multiple cytokine inhibitor, on hydrochloric acid (HCl) aspiration lung injury in rats. HCl (0.1 N, 2 ml kg(-1)) was instilled into male Sprague-Dawley rats that were pretreated with or without JTE-607 (30 or 75 mg kg(-1) h(-1)). As a control, normal saline (2 ml kg(-1)) was instilled in rats. All the animals were anesthetized with intraperitoneally injected pentobarbital sodium (40 mg kg(-1)). Bronchoalveolar lavage was performed 5 h (h) after HCl or normal saline instillation. In bronchoalveolar lavage fluid, the increases in total nuclear cell counts, neutrophil counts, optical density at 412 nm as an indication of pulmonary hemorrhage, concentrations of albumin, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and cytokine-induced neutrophil chemoattractant induced by HCl instillation were significantly reduced by JTE-607 pretreatment. The level of expression of tumor necrosis factor-alpha and interleukin-6 mRNA in lung tissue was analyzed. The mean expression level of tumor necrosis factor-alpha and interleukin-6 mRNA in the JTE-607 group was lower than that in the HCl and NS groups. The wet-to-dry weight ratio was also determined, and JTE-607 at the dose of 75 mg kg(-1) h(-1) significantly attenuated the increased wet-to-dry weight ratio induced by HCl. These results suggest that JTE-607 can inhibit the production of inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-6 and cytokine-induced neutrophil chemoattractant and attenuate acid-induced lung injury in rats. This agent might be therapeutically useful for lung injury.

Inflammation and the acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a clinical syndrome of non-cardiogenic pulmonary oedema associated with bilateral pulmonary infiltrates, stiff lungs and refractory hypoxaemia. ARDS is characterized by an explosive acute inflammatory response in the lung parenchyma, leading to alveolar oedema, decreased lung compliance and, ultimately, hypoxaemia. Although our understanding of the causes and pathophysiology of ARDS has increased, the mortality rate remains in the range of 30-50%. No major advances in pharmacological therapy have been achieved. Mechanical ventilation is the main therapeutic intervention in the management of ARDS. The only approach that has been shown to reduce the inflammatory response and mortality is the use of lung-protective ventilatory strategy with a low tidal volume and high positive-end expiratory pressure. This chapter will review the current state of the literature on the pathogenesis of ARDS and ventilatory and pharmacotherapy approaches to its management.

Cytokine-mediated inflammation in acute lung injury

Clinical acute lung injury (ALI) is a major cause of acute respiratory failure in critically ill patients. There is considerable experimental and clinical evidence that pro- and anti-inflammatory cytokines play a major role in the pathogenesis of inflammatory-induced lung injury from sepsis, pneumonia, aspiration, and shock. A recent multi-center clinical trial found that a lung-protective ventilatory strategy reduces mortality by 22% in patients with ALI. Interestingly, this protective ventilatory strategy was associated with a marked reduction in the number of neutrophils and the concentration of pro-inflammatory cytokines released into the airspaces of the injured lung. Further research is needed to establish the contribution of cytokines to both the pathogenesis and resolution of ALI.

Burn injury and pulmonary sepsis: development of a clinically relevant model

BACKGROUND

Despite improvements in the early resuscitation of the critically injured, mortality from multiple organ failure has remained stable, with the lung often the first organ to fail. Early intubation and mechanical ventilation predispose patients to the development of pneumonia and respiratory failure. Our objective was to establish a murine model of combined injury, consisting of burn/trauma and pulmonary sepsis with reproducible end-organ responses and mortality.

METHODS

Male B6D2F1 mice were divided into four groups: burn/infection (BI), burn (B), infection (I), and sham (S). Burned animals had a full-thickness 15% dorsal scald burn. BI and I groups were inoculated intratracheally with Pseudomonas aeruginosa (3-5 x 103 colony-forming units). S and B animals received saline intratracheally. All animals were resuscitated with 2 mL of intraperitoneal saline. Mortality was recorded at 24, 48, and 72 hours. Bacterial sepsis was confirmed by tissue Gram's stain of the lungs and positive organ and blood cultures for Pseudomonas aeruginosa. Femoral bone marrow cells were collected at 72 hours from surviving animals. Clonogenic potential was assessed by response to macrophage (M) colony-stimulating factor (CSF) and granulocyte-macrophage (GM) CSF in a soft agar assay and the data were represented as colonies per femur. Isolated alveolar macrophages and whole lung tissue were assayed for levels of the inflammatory cytokines tumor necrosis factor-alpha and interleukin-6.

RESULTS

Mortality at 72 hours was 30% in BI, 12% in I, and <10% in B and S groups. Pneumonia was documented in all infected animals at 24 hours by Gram's stain and positive tissue cultures for Pseudomonas aeruginosa. Systemic sepsis as confirmed by blood, and remote organ cultures was seen in BI animals only. Significantly increased responsiveness to M-CSF stimulations was noted in all groups (BI, 8,291 +/- 1,402 colonies/femur; B, 6,357 +/- 806 colonies/femur; and I, 8,054 +/- 1,112 colonies/femur; p < 0.05) relative to sham (3,369 +/- 883 colonies/femur, p < 0.05). Maximal responsiveness to GM-CSF stimulation was noted in the BI group (11,932 +/- 982 colonies/femur, p < 0.05), and similar GM responsiveness was noted in all other groups (B, 7,135 +/- 548 colonies/femur; I, 7,023 +/- 810 colonies/femur; and S, 6,829 +/- 1,439 colonies/femur). Alveolar macrophage release of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-6 increased in all animals, but the magnitude of increase was not proportional to the strength of the inciting stimulus.

CONCLUSION

Although minimal perturbations were seen after burn or pulmonary infection alone, the combined insult of burn and pulmonary sepsis resulted in statistically significant hematopoietic changes with increased monocytopoiesis. Only the combined injury resulted in systemic sepsis and significantly increased mortality. We have developed a clinically relevant model of trauma and pulmonary sepsis that will allow further clarification of the inflammatory response after injury and infection.

Stress-activated cytokines and the heart: from adaptation to maladaptation

The ability of the myocardium to successfully compensate for and adapt to environmental stress ultimately determines whether the heart will decompensate and fail or maintain preserved function. Despite the importance of the myocardial response to environmental stress, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. In the present review we summarize recent experimental material suggesting that the cytokines expressed within the myocardium in response to environmental injury, namely tumor necrosis factor (TNF), interleukin-1 (IL-1), and the interleukin-6 (IL-6) family, play an important role in initiating and integrating homeostatic responses. However, these stress-activated cytokines all have the potential to produce cardiac decompensation when expressed at sufficiently high concentrations. Accordingly, the theme to emerge from this review is that the short-term expression of stress-activated cytokines within the heart may be an adaptive response to stress, whereas long-term expression of these molecules may be frankly maladaptive by producing cardiac decompensation.

Cytokines in depression and heart failure

OBJECTIVE

There is a convincing body of evidence linking depression, cardiovascular disease, and mortality. There is also growing evidence that depression is a risk factor for congestive heart failure (CHF) and that CHF patients with major depression have higher rates of mortality and repeat hospitalizations. Currently there are no proposed neurobiological or neuroimmune mechanisms for the comorbidity of heart failure and depression.

METHODS

This review focuses on the recent literature about the role of cytokines in CHF and depression as separate conditions. This review also attempts to identify the overlapping immunological mechanisms that have a potential for future research in the pathophysiology of comorbid depression and CHF.

RESULTS

Results of current studies suggest that cytokines exert deleterious effects on the heart and that soluble tumor necrosis factor (TNF) receptor 2 leads to reversal of the cardiotoxic effects of TNF, although the clinical significance of this is unclear. Major depression has been associated with alteration of various aspects of the innate immune system, including cellular components (such as microphages, neutrophils, and natural killer cells) and soluble mediators (such as acute-phase reaction proteins and cytokines). It is inconclusive whether antidepressants have immunoregulatory effects.

CONCLUSIONS

The literature has not yet addressed the role of cytokines in comorbid depression and CHF. But cytokines may provide a new avenue in understanding brain-body interaction in depression and heart failure.

The effect of tumor necrosis factor-alpha on microvascular permeability in an isolated, perfused lung

This study examines the hypotheses that TNF-alpha causes a dose-dependent increase in the microvascular permeability of ex vivo buffer perfused lungs that is quantitatively similar to that caused by lipopolysaccharide (LPS) or thromboxane A2 (TxA2). We also postulated that TNF-alpha potentiates the effect of interleukin-1beta (IL-1beta) or TxA2 receptor activation on pulmonary microvascular permeability. Lungs harvested from Wistar rats were perfused ex vivo with Krebs-Henseleit buffer containing 0, 10, 100, or 1000 ng/mL recombinant rat TNF-alpha. Twenty minutes later pulmonary microvascular permeability was determined by measuring the capillary filtration coefficient (Kf) using a gravimetric technique. The effect of TNF-alpha (100 ng/mL) on pulmonary Kf was compared with that of lungs exposed to LPS (400 microg/mL; E. coli 0111:B4) or a TxA2 receptor agonist (U-46619; 7 x 10(-8)). In other experiments, perfused lungs were exposed to TNF-alpha plus IL-1beta (1 ng/mL) or TNF-alpha plus U-46619 after which Kf was measured. Exposure of ex vivo buffer perfused lungs to 10-1000 ng/mL TNF-alpha had no effect on Kf whereas LPS and U-46619 was associated with a two- and six-fold increase in Kf, respectively (P < 0.05). The Kf of lungs exposed to TNF-alpha plus IL-1 was similar to that of lungs exposed to TNF-alpha alone. Lastly, the Kf of lungs exposed to TNF-alpha plus U-46619 was not different than that of lungs exposed to U-46619 alone. In conclusion, TNF-alpha at least when administered for a relatively brief period of time does not affect microvascular permeability in an isolated, buffer-perfused lung model.

The role of tumor necrosis factor in cardiac disease

Tumor necrosis factor (TNF) is a proinflammatory cytokine that can produce widespread deleterious effects when expressed in large amounts. It is produced in the heart by both cardiac myocytes and resident macrophages under conditions of cardiac stress, and is thought to be responsible for many of the untoward manifestations of cardiac disease. This article discusses the role of TNF in heart disease and some potential therapeutic modalities that can influence the cytokine activity. The results of controlled studies would suggest that TNF inhibition does not influence the clinical course of patients with heart failure.

Ibuprofen attenuates early lung injury in endotoxemic, neutropenic rats

The objective of our study was to determine the role of ibuprofen in protecting neutropenic rats from cardiopulmonary injury due to endotoxemia. We hypothesized that ibuprofen would offer pulmonary protection by altering cytokine production. Neutropenic rats received E. coli lipopolysaccharide (LPS) alone or ibuprofen and LPS. After 4 h, arterial blood gases, heart rate and blood pressure were measured. Blood and bronchoalveolar lavage fluid (BALF) were collected for TNF- alpha and MIP-2 concentrations. Lung tissue for iNOS mRNA and myeloperoxidase were obtained. The ibuprofen group had decreased heart rate and better oxygenation. Ibuprofen suppressed TNF- alpha and MIP-2 production in blood and MIP-2 concentrations in BALF. Lung mRNA for iNOS was higher in the ibuprofen group. Neutrophil infiltration in the lung was similar in both groups. Ibuprofen attenuated cardiopulmonary dysfunction by decreasing the early cytokine response. The balance of vasodilator to vasoconstrictor production in the lung may favor vasodilation as shown by increased iNOS mRNA and suppression of thromboxane.

High tumour necrosis factor-alpha levels are associated with exercise intolerance and neurohormonal activation in chronic heart failure patients

Immune activation plays an important role in the progression of chronic heart failure (CHF). We sought to investigate whether different degrees of tumor necrosis factor-alpha (TNF-alpha) activation are associated with exercise intolerance, neurohormonal activation and alterations in muscle mass and function in patients with CHF without cardiac cachexia. Patients were divided into quartiles according to their TNF levels (first quartile: 0.98-4.90 pg/ml, second quartile: 5.00-6.60 pg/ml; third quartile 6.80-9.00 pg/ml; fourth quartile 9.80-32.00 pg/ml). Patients underwent cardiopulmonary exercise testing, quadriceps muscle strength test, quadriceps fatigue test, and assessment of thigh muscle and fat cross-sectional area (CSA) by computerized tomography scanning. Patients in the highest TNF quartile had the lowest peak oxygen consumption [13.1 (+/-4.1) ml/kg/min vs 18.1 (+/-5.3), 18.8 (+/-4.8) and 18.7 (+/-5.6) ml/kg/min, P<0.01] the greatest relation of ventilation and dioxide production (VE/VCO(2)) slope (P<0.05) and the most elevated catecholamine levels (P<0.05) compared to patients in the first three quartiles. Patients with the lowest TNF levels had preserved thigh muscle size and quadriceps strength. Strength/muscle CSA was similar in the four groups. Muscle strength during fatigue testing was significantly lower in the fourth quartile (P=0.01) compared with the other three groups. In CHF patients only the highest levels of TNF are associated with poor functional status and neurohormonal activation. This group of patients may represent the appropriate target population for TNF antagonism.

Differential effect of MLC kinase in TNF-alpha-induced endothelial cell apoptosis and barrier dysfunction

Tumor necrosis factor (TNF)-alpha is released in acute inflammatory lung syndromes linked to the extensive vascular dysfunction associated with increased permeability and endothelial cell apoptosis. TNF-alpha induced significant decreases in transcellular electrical resistance across pulmonary endothelial cell monolayers, reflecting vascular barrier dysfunction (beginning at 4 h and persisting for 48 h). TNF-alpha also triggered endothelial cell apoptosis beginning at 4 h, which was attenuated by the caspase inhibitor Z-Val-Ala-Asp-fluoromethylketone. Exploring the involvement of the actomyosin cytoskeleton in these important endothelial cell responses, we determined that TNF-alpha significantly increased myosin light chain (MLC) phosphorylation, with prominent stress fiber and paracellular gap formation, which paralleled the onset of decreases in transcellular electrical resistance and enhanced apoptosis. Reductions in MLC phosphorylation by the inhibition of either MLC kinase (ML-7, cholera toxin) or Rho kinase (Y-27632) dramatically attenuated TNF-alpha-induced stress fiber formation, indexes of apoptosis, and caspase-8 activity but not TNF-alpha-induced barrier dysfunction. These studies indicate a central role for the endothelial cell cytoskeleton in TNF-alpha-mediated apoptosis, whereas TNF-alpha-induced vascular permeability appears to evolve independently of contractile tension generation.

Exposure to febrile temperature modifies endothelial cell response to tumor necrosis factor-alpha

Fever is an important regulator of inflammation that modifies expression and bioactivity of cytokines, including tumor necrosis factor (TNF)-alpha. Pulmonary vascular endothelium is an important target of TNF-alpha during the systemic inflammatory response. In this study, we analyzed the effect of a febrile range temperature (39.5 degrees C) on TNF-alpha-stimulated changes in endothelial barrier function, capacity for neutrophil binding and transendothelial migration (TEM), and cytokine secretion in human pulmonary artery endothelial cells (EC). Permeability for [(14)C]BSA tracer was increased by treatment with TNF-alpha, and this effect was augmented by incubating EC at 39.5 degrees C. Treating EC with 2. 5 U/ml TNF-alpha stimulated an increase in subsequent neutrophil adherence and TEM. Incubating EC at 39.5 degrees C caused a 30% increase in TEM but did not modify the enhancement of neutrophil adherence or TEM by TNF-alpha treatment. Analysis of cytokine expression in EC cultures exposed to TNF-alpha at either 37 degrees or 39.5 degrees C revealed three patterns of temperature and TNF-alpha responsiveness. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-8 were not detectable in untreated EC but were increased after TNF-alpha exposure, and this increase was enhanced at 39.5 degrees C. IL-6 expression was also increased with TNF-alpha exposure, but IL-6 expression was lower in 39.5 degrees C EC cultures. Transforming growth factor-beta(1) was constitutively expressed, and its expression was not influenced either by TNF-alpha or exposure to 39.5 degrees C. These data demonstrate that clinically relevant shifts in body temperature might cause important changes in the effects of proinflammatory cytokines on the endothelium.

Mediators and mechanisms of acute lung injury

Since last reviewed in this forum, there have been remarkable advances in our understanding of the acute inflammatory process and how it contributes to the development of ALI. As stated in the beginning of this article, it is not possible to even begin to review all the specific advances that have been made. Instead, the author has focused on concepts that have emerged and improved our ability to study the pathogenesis of ARDS. These include the recognition that patients at risk for and with ARDS represent a heterogeneous population, that mediators or markers of inflammation cannot be considered in isolation, that a balance between proinflammatory mediators and inflammatory modulators may be important, and that there are several genetic factors that could contribute to the susceptibility for the development of ARDS. Hopefully these concepts can be expanded and clarified so that the next review of this topic can report on successful therapeutic interventions for the prevention and the treatment of ARDS.

Expression of interleukin-18 in the lung after endotoxemia or hemorrhage-induced acute lung injury

Hemorrhage and endotoxemia are important risk factors for the development of acute lung injury. Interleukin (IL)-18 is a recently described cytokine released in its mature, active form after pro-IL-18 is cleaved by the IL-1 converting enzyme (ICE). IL-18 has multiple immunomodulating properties, including induction of interferon-gamma (IFN-gamma), IL-1beta, tumor necrosis factor-alpha, and intercellular adhesion molecule-1. To examine the possible involvement of IL-18 in acute lung injury, we examined its expression, as well as that of IFN-gamma, IL-12, and ICE, using murine hemorrhage or endotoxemia models. The amounts of IL-18 messenger RNA (mRNA) increased in the lung after hemorrhage or endotoxemia. However, only endotoxemia was associated with elevations in lung and plasma concentrations of IL-18 protein. ICE expression was increased in the lungs after endotoxemia but not after hemorrhage. Although IFN-gamma expression increased in the lungs after hemorrhage or endotoxemia, elevations in lung IL-12 mRNA levels were found only after endotoxemia. These results indicate that hemorrhage and endotoxemia induce different patterns of immunomodulatory cytokine expression in the lungs. In particular, differences in the expression of ICE after hemorrhage or endotoxemia may affect generation of the active forms of downstream cytokines, including IL-18. IFN-gamma expression in the lungs after hemorrhage appears to occur through a pathway independent of IL-12 and IL-18. IL-18 may play a role in modulating the development of acute lung injury after endotoxemia but not after hemorrhage.

Acute lung injury and acute respiratory distress syndrome in sepsis and septic shock

Sepsis remains the leading cause of ARDS, and ARDS is still an often fatal condition. With our expanding knowledge of the pathobiologic mechanisms and the relationship between these two entities, early recognition, treatment, and prevention of sepsis may prevent or hasten recovery from ARDS. Understanding the biologic markers involved in the complex inflammatory response of sepsis and acute lung injury offers the possibility of future investigations to target treatment based on these mediators.

Role of tumour necrosis factor-alpha in the progression of heart failure: therapeutic implications

The experimental and clinical evidence that demonstrates the effect of various cytokines, and in particular tumour necrosis factor (TNF)alpha, in patients with heart failure continues to accumulate. It is well established that increased levels of TNFalpha appear in the circulation of patients with heart failure and that the levels may have prognostic significance. Also, increased circulating TNFalpha levels may be responsible for the decreased expression of myocardial TNF receptors observed in failing myocardium. Along with these clinical data, it has been clearly demonstrated that increased levels of TNFalpha lead to cardiomyopathy and eventually death in experimental animals. Therefore, it is reasonable to assume that the increased levels of TNFalpha in patients with heart failure may be detrimental to cardiac function. The hypothesis that TNFalpha contributes to the pathogenesis of heart failure has recently been tested at the clinical level. The results of specific TNFalpha antagonism in patients with symptomatic heart failure demonstrate that anti-TNFalpha therapy is well tolerated and may be effective. This hypothesis is currently being tested in a large randomised, multicentre study that is expected to be complete within the next 2 years. Perhaps the most important aspect of the evolving research into the role of cytokines in heart failure is that the recognition of activation of inflammatory mediators provides new targets for therapeutic intervention.

Experimental study of “Tong Xia” purgative method in ameliorating lung injury in acute necrotizing pancreatitis

AIM: To investigate the role of tumor necrosis factor (TNF) in lung injury during acute necrotizing pancreatitis (ANP), and the therapeutic ef fect of “Tong Xia” purgative method in minimizing the severity of lung injury.

METHODS: Fourteen canines were randomly divided into 3 groups: the “Tong Xia” treatment group (n = 5) using Dachengqitang; saline control group (n = 5), and the sham operation group (n = 4). TNF activity in serum and in bronchoalveolar lavage fluid (BALF), the serum endotoxin levels were meas ured, and the severity of lung injury evaluated.

RESULTS: Elevation of TNF activity was more prominent in BALF than in serum. TNF activity in serum at 6 and 12 h and in BALF was significantly decreased in the “Tong Xia” treatment group than in the saline control one (q = 21.11, q = 12.07, q = 9.03, respectively, P < 0.01) and the lung injury was significantly alleviated at 12 h as compared with that in the saline group, manifested as amelioration of the lung wet/dry weight ratio, decrease in protein concentration and neutrophils count in BALF, and improvement of pulmonary inflammatory changes. A positive correlation was demonstrated between serum TNF activity and endotoxin level.

CONCLUSION: Hypersecretion of TNF is shown to be one of the majo r causes of lung injury during ANP; “Tong Xia” purgative method could allevia te the degree of lung injury mediated by TNF.

Comparison of systemic cytokine levels in patients with acute respiratory distress syndrome, severe pneumonia, and controls

BACKGROUND

The inflammatory response has been widely investigated in patients with acute respiratory distress syndrome (ARDS) and pneumonia. Studies investigating the diagnostic values of serum cytokine levels have yielded conflicting results and only little information is available for the differential diagnosis between ARDS and pneumonia.

METHODS

Clinical and physiological data, serum concentrations of tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6, and quantitative cultures of lower respiratory tract specimens were obtained from 46 patients with ARDS and 20 with severe pneumonia within 24 hours of the onset of the disease and from 10 control subjects with no inflammatory lung disease. Cytokine concentrations were compared between groups and determinants in addition to the diagnosis were tested.

RESULTS

Serum TNF-alpha levels were significantly higher in ARDS patients (67 (57) pg/ml) than in patients with severe pneumonia (35 (20) pg/ml; p = 0.031) or controls (17 (8) pg/ml; p = 0.007). For IL-1beta and IL-6 the observed differences were not statistically significant between patients with ARDS (IL-1beta: 34 (65) pg/ml; IL-6: 712 (1058) pg/ml), those with severe pneumonia (IL-1beta: 3 (4) pg/ml, p = 0.071; IL-6: 834 (1165) pg/ml, p = 1.0), and controls (IL-1beta: 6 (11) pg/ml, p = 0.359; IL-6: 94 (110) pg/ml, p = 0.262). TNF-alpha (standardised coefficient beta = 0.410, p<0.001) and IL-1beta (standardised coefficient beta = 0.311, p = 0.006) were most strongly associated with the degree of lung injury, even when the diagnostic group was included in the statistical model.

CONCLUSIONS

Serum TNF-alpha levels were higher in patients with ARDS than in those with severe pneumonia or in control subjects. Multivariate results suggest that the levels of systemic TNF-alpha and IL-1beta reflect the severity of the lung injury rather than the diagnosis.

Increased expression of functionally active membrane-associated tumor necrosis factor in acute respiratory distress syndrome

Membrane-associated tumor necrosis factor (mTNF) has recently been shown to induce inflammatory cellular responses previously attributed to the soluble form. The present study measures for the first time the expression and function of mTNF on the surface of alveolar macrophages (AMs) to determine whether it is associated with the development of acute respiratory distress syndrome (ARDS). TNF expression was determined by flow cytometry, and the function of mTNF on the surface of AMs was determined by an in vitro cytotoxicity assay. Tumor necrosis factor (TNF)-alpha bioactivity was measured by bioassay. Soluble TNF receptor (TNFR) protein and messenger RNA (mRNA) expression were measured by enzyme-linked immunosorbent assay and reverse transcriptase/polymerase chain reaction, respectively. Increased detection of mTNF was observed on the surface of AMs derived from subjects with ARDS (mean percentage increase in fluorescence 22.30 +/- 3.50% for subjects with ARDS compared with 7.09 +/- 1.70% for At Risk subjects [P < 0.003]). mTNF cytotoxicity in the bioassay positively correlated with the mTNF expression determined by flow cytometry (r(2) = 0.97). Although there was increased mTNF expression and cytotoxic function in ARDS, there was no significant increase in soluble TNF expression in the bronchoalveolar lavage fluid or the AM supernatants. Lower levels of CD120b-soluble TNFR were detected in the AM supernatants derived from subjects with ARDS compared with At Risk (mean 0.264 +/- 0.058 versus 0.593 +/- 0.143 ng/ml, respectively [P < 0.05]). By contrast, there was increased CD120b mRNA expression in AMs derived from subjects with ARDS (P < 0.03), suggesting that increased surface expression of this receptor may be important in mediating the signal of mTNF. These data demonstrate for the first time the presence of functionally active mTNF on the surface of AMs in ARDS and highlight a potential mechanism for TNF-mediated lung injury.