Persistent elevation of inflammatory cytokines predicts a poor outcome in ARDS. Plasma IL-1 beta and IL-6 levels are consistent and efficient predictors of outcome over time

Intradermal transfer of caspase-1 (CASP1) DNA into mouse dissects: role of CASP1 in interleukin-1beta associated skin inflammation and apoptotic cell death

Caspase-1 (CASP1) interleukin-1beta (IL-1beta) converting enzyme (ICE) has been cloned as a specific enzyme which activates the biologically inactive pro-form of IL-1beta into biological active IL-1beta. Based on the significant homology to Ced-3, Caenorhabditis elegans apoptotic gene and, proof of apoptotic activity of ICE in rat fibroblasts, ICE was renamed as CASP1. In contrast to in vitro functions, the in vivo significance of high expression of CASP1 in skin remains to be elucidated. We transferred plasmid DNA encoding murine CASP1 with beta-actin promoter into mouse skin. The CASP1 DNA-injected skin, but not skin injected with control plasmid without CASP1, developed localized erythema with subcutaneous nodules. The nodules were associated with marked inflammatory infiltrates. The apoptotic cells detected by the TUNEL method were distributed in and around the inflammatory foci. The plasma IL-1beta level of CASP1 DNA-injected mouse was elevated compared with that of the control DNA-injected mouse. These inflammatory reactions of CASP1 DNA-injected skin were suppressed by treatment with neutralizing anti-murine IL-1beta antibodies, but the TUNEL positive apoptotic cells were still detected. This study clearly demonstrate dual roles of CASP1 in causing IL-1beta associated granulomatous skin infiltration and inducing apoptotic cell death in vivo.

Cytokines IL-1beta, IL-6, and TNF-alpha enhance in vitro growth of bacteria

We have previously reported that in acute respiratory distress syndrome (ARDS), nonsurvivors have persistent elevation in pulmonary and circulating proinflammatory cytokine levels over time and a high rate of nosocomial infections antemortem. In these patients, none of the proven or suspected nosocomial infections caused a transient or sustained increase in plasma proinflammatory cytokine levels above preinfection values. We hypothesized that cytokines secreted by the host during ARDS may favor the growth of bacteria. We conducted an in vitro study of the growth of three bacteria clinically relevant in nosocomial infections, evaluating their in vitro response to various concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6. We found that all three bacterial species showed concentration-dependent growth enhancement when incubated with one or more tested cytokines and that blockade by specific neutralizing cytokine MoAb significantly inhibited cytokine-induced growth. When compared with control, the 6-h growth response (cfu/ml) was maximal with IL-1beta at 1,000 pg for Staphylococcus aureus (36 +/- 16 versus 377 +/- 16; p = 0.0001) and Acinetobacter spp. (317 +/- 1,147 versus 1,124 +/- 147; p = 0.002) and with IL-6 at 1,000 pg for Pseudomonas aeruginosa (99 +/- 50 versus 509 +/- 50; p = 0.009). The effects of cytokines were seen only with fresh isolates and were lost with passage in vitro on bacteriologic medium without added cytokines. In this study we provide additional evidence for a newly described pathogenetic mechanism for bacterial proliferation in the presence of exaggerated and protracted inflammation.

Elevated plasma endothelin-1 and cytokine levels in children with severe acute respiratory distress syndrome

We performed serial measurements of plasma endothelin-1 and cytokine levels (interleukin-1, interleukin-6, and tumor necrosis factor-alpha) in 23 children with severe acute respiratory distress syndrome during their first 7 days of disease. We report plasma endothelin-1 and interleukin-6 levels are increased in patients with acute respiratory distress syndrome, and that plasma endothelin-1 levels are significantly greater early in the clinical course of nonsurvivors than survivors. We conclude that plasma endothelin-1 levels are markedly increased in children with severe acute respiratory distress syndrome and speculate that high levels may serve as an early marker of poor outcome.

Mechanical ventilation affects local and systemic cytokines in an animal model of acute respiratory distress syndrome

We examined the hypothesis that injurious ventilatory strategies (large tidal volume [VT] and/or low positive end-expiratory pressure [PEEP]) would increase release of inflammatory mediators into the lung and into the systemic circulation in a lung injury model. Lung injury was induced in 40 anesthetized paralyzed Sprague-Dawley rats (350 +/- 2 g) by hydrochloric acid instillation (pH 1.5, 2.5 ml/kg). Rats were then randomized into five groups (n = 8): (1) high-volume zero PEEP (HVZP): VT, 16 ml/ kg; (2) high-volume PEEP (HVP): VT, 16 ml/kg, PEEP, 5 cm H2O; (3) low-volume zero PEEP (LVZP): VT, 9 ml/kg; (4) low-volume PEEP (LVP): VT, 9 ml/kg, PEEP, 5 cm H2O; (5) same settings as (4) plus a recruitment maneuver performed every hour (LVPR). Respiratory rate was adjusted to maintain normocapnia and fraction of inspired oxygen (FIO2) was 1. Cytokine concentrations (tumor necrosis factor-alpha [TNF-alpha] and macrophage inflammatory protein-2 [MIP-2]) were measured by ELISA. All animals in the LVZP group died before the end of the experiment. After 4 h of ventilation, the HVZP group had similar lung fluid TNF-alpha concentrations compared with the HVP group: 1,861 +/- 333 pg/ml versus 1,259 +/- 189 pg/ml; and much higher serum concentrations: 692 +/- 74 pg/ml versus 102 +/- 31 pg/ml (p < 0.05). An identical pattern was found for MIP-2. These results suggest that the particular ventilatory strategy can affect the release of cytokines into the systemic circulation, a finding that may have relevance for the development of multisystem organ failure.

Both Erk and p38 kinases are necessary for cytokine gene transcription

A critical feature of sepsis-induced acute lung injury is the release of cytokines from endotoxin (LPS)- stimulated alveolar macrophages (AM). LPS is also known to activate various members of the mitogen- activated protein kinase (MAPK) family in other types of cells. In this study, we evaluated whether multiple members of the MAPK family regulate cytokine gene expression in LPS-stimulated AM. We found that LPS activates both the extracellular signal-regulated kinase (Erk) and p38 kinases, and that this activation is augmented when the cells are cultured in serum. Inhibition of either the Erk (with PD98059) or p38 (with SB203580) kinase pathway resulted in only a partial reduction in cytokine (interleukin-6 and tumor necrosis factor) messenger RNA accumulation and cytokine release, whereas inhibition of both pathways simultaneously resulted in a decrease in cytokine gene expression to near-control levels. Nuclear run-on assays showed that the effect of these MAPK pathways on LPS-induced expression of the cytokine genes was attributable, at least in part, to regulation of gene transcription. These findings suggest that activation of both the Erk and p38 kinase pathways is necessary for optimal cytokine gene expression in LPS-stimulated human AM, and that the MAPK pathways play a critical role in the inflammatory response that occurs in sepsis-induced acute lung injury.

The laboratory-clinical interface: point-of-care testing

POC testing provides an opportunity for clinicians and laboratorians to work together to consider how best to serve the patients within an individual institution. Each health system has unique characteristics relative to patient population, as well as a unique laboratory structure. If physicians, nurses, laboratorians, and pathologists work collaboratively, the best interests of patients will be served. In some institutions that cater to specific patient groups, POC testing may offer clear and distinct advantages. In other institutions with sophisticated transport systems and established rapid response capabilities, the quality resulting from central laboratory testing may outweigh any advantages of bedside testing. Clearly, attention to regulatory issues, QC issues, the importance of proper documentation, proficiency testing, performance enhancement, and cost-effectiveness is requisite. As the technology for diagnostic testing advances through more microcomputerization, microchemistry, and enhanced test menus, the concept of POC testing will need perpetual revisiting. We hope that the information provided here will aid clinicians, laboratorians, and administrators in their quest to best serve their patients.

Expression and Function of the Chemokine Receptors CXCR1 and CXCR2 in Sepsis

Neutrophils (polymorphonuclear neutrophils; PMN) and a redundant system of chemotactic cytokines (chemokines) have been implicated in the pathogenesis of the acute respiratory distress syndrome in patients with sepsis. PMN express two cell surface receptors for the CXC chemokines, CXCR1 and CXCR2. We investigated the expression and function of these receptors in patients with severe sepsis. Compared with normal donors, CXCR2 surface expression was down-regulated by 50% on PMN from septic patients (p &lt; 0.005), while CXCR1 expression persisted. In vitro migratory responses to the CXCR1 ligand, IL-8, were similar in PMN from septic patients and normal donors. By contrast, the migratory response to the CXCR2 ligands, epithelial cell-derived neutrophil activator (ENA-78) and the growth-related oncogene proteins, was markedly suppressed in PMN from septic patients (p &lt; 0.05). Ab specific for CXCR1 blocked in vitro migration of PMN from septic patients to IL-8 (p &lt; 0.05), but not to FMLP. Thus, functionally significant down-regulation of CXCR2 occurs on PMN in septic patients. We conclude that in a complex milieu of multiple CXC chemokines, CXCR1 functions as the single dominant CXC chemokine receptor in patients with sepsis. These observations offer a potential strategy for attenuating adverse inflammation in sepsis while preserving host defenses mediated by bacteria-derived peptides such as FMLP.

The alveolar space is the site of intense inflammatory and profibrotic reactions in the early phase of acute respiratory distress syndrome

OBJECTIVES

To determine the concentrations of proinflammatory mediators, collagenases, and procollagen type III peptides in undiluted pulmonary edema fluids and in plasma obtained in patients with early acute respiratory distress syndrome (ARDS) and in control patients with hydrostatic lung edema; and to assess the relationship between these inflammatory and profibrotic markers.

DESIGN

A prospective, clinical study with measurements of inflammatory markers in pulmonary edema fluids and in paired plasma samples.

SETTING

A medical intensive care unit.

PATIENTS

Patients intubated with lung permeability (n = 23) and hydrostatic (n = 8) pulmonary edema were prospectively enrolled in the study. The severity of the disease at the time of intubation was assessed, using the Simplified Acute Physiological Score (SAPS) II and the Lung Injury Score (LIS).

INTERVENTIONS

Plasma and undiluted edema fluids were obtained at the time of intubation with pulmonary edema requiring mechanical ventilation; and in some patients, a second edema fluid sample was collected a few hours later.

MEASUREMENTS AND MAIN RESULTS

Proinflammatory activity, dependent on the presence of bioactive proinflammatory cytokines, interleukin (IL)-8, and neutrophil matrix metalloproteinase (MMP)-9 were significantly increased in ARDS fluids compared with plasma or control fluids from patients with congestive heart failure. In contrast, MMP-2, originating from lung cells other than phagocytes, was slightly increased in ARDS edema fluids compared with plasma, but similar to levels found in hydrostatic edema fluids. Proinflammatory activity was undetectable in plasma from ARDS patients. Levels of procollagen peptide III, a marker of collagen synthesis, were increased in permeability edema fluids compared with hydrostatic edema fluids or plasma, confirming that alveolar collagen synthesis begins very early and in parallel with acute inflammation in ARDS. Control patients with hydrostatic edema had similar SAPS II and LIS scores compared with ARDS patients.

CONCLUSIONS

These results strongly support the conclusion that during the early phase of ARDS, the lung is the site of an intense inflammatory process with sequential activation of cytokines, chemokines, and secretion of proteases, as well as concomitant collagen synthesis. The inflammation is mostly limited to the lung, with low levels of inflammatory mediators in the systemic circulation. Unlike clinical scoring systems (SAPS II and LIS), inflammatory markers differentiate patients with permeability and hydrostatic pulmonary edema.

Elevated cytokine concentrations in the nasopharyngeal and tracheal secretions of children with respiratory syncytial virus disease

BACKGROUND

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract disease in infants. The role of inflammatory mediators in the pathogenesis of RSV disease is not well-understood. The present study was designed (1) to determine whether RANTES (regulated on activation, normal T cell expressed and presumably secreted), macrophage-inflammatory protein-1-alpha (MIP-1-alpha), interleukin (IL)-6, IL-8 and IL-10 can be detected in respiratory secretions of children with RSV infection and (2) to assess whether the concentrations of these cytokines in respiratory secretions correlate with white blood cell (WBC) counts and RSV concentrations and with disease severity.

METHODS

During the 1996 to 1997 RSV season, we studied prospectively 14 intubated and 14 nonintubated children hospitalized with RSV disease. Nasal wash (NW) and tracheal aspirate (TA) samples were obtained from intubated patients on Hospital Days 1, 3 and 5. NW samples were obtained from nonintubated patients on hospital days 1 and 3. Seven healthy children undergoing elective surgery served as controls. All samples were analyzed for: (1) WBC and differential counts; (2) concentrations of RANTES, MIP-1-alpha, IL-6, IL-8 and IL-10; and (3) quantitative RSV cultures, except in control patients.

RESULTS

RANTES, MIP-1-alpha, IL-6, IL-8 and IL-10 were detected in NW and TA samples from all children with RSV infection. The concentrations of these cytokines in samples obtained from children with RSV infection were significantly greater than those in samples obtained from control children. NW WBC counts significantly correlated with NW RANTES, IL-6, IL-8 and IL-10 concentrations, whereas TA WBC counts significantly correlated with TA IL-6, IL-8, IL-10 and MIP-1-alpha concentrations. NW RSV concentrations correlated with NW WBC counts and with NW cytokine concentrations. Among children with RSV infection nonintubated patients had greater NW WBC counts and NW RANTES concentrations than intubated patients. TA RANTES, IL-8 and IL-10 concentrations inversely correlated with clinical markers of RSV disease severity.

CONCLUSION

The presence of cytokines in NW and TA samples of children with RSV infection suggests that they have a role in mediating the respiratory tract inflammation induced by RSV. These observations could have implications for designing new therapeutic strategies directed at immunomodulation of RSV disease.

Collagen deposition in a non-fibrotic lung granuloma model after nitric oxide inhibition

Recent studies support the concept that pulmonary granulomatous inflammation directed by interferon (IFN)-gamma, interleukin (IL)-12, and nitric oxide usually resolves in the absence of fibrosis. To determine whether nitric oxide participates in modulating the fibrotic response during the development of pulmonary granulomas in response to purified protein derivative (PPD), mice presensitized to PPD received daily intraperitoneal injections of N(G)-nitro-D-arginine-methyl ester (D-NAME), N(G)-nitro-L-arginine-methyl ester (L-NAME), or aminoguanidine after delivery of PPD-coated beads to the lungs. Eight days later, morphometric analysis of lung granulomas revealed that L-NAME-treated mice when challenged with PPD in vitro for 36 hours had the largest pulmonary granulomas and the greatest collagen deposition among the treated groups. In addition, equivalent numbers of dispersed lung cells from L-NAME- and aminoguanidine-treated mice produced significantly higher levels of IL-4, monocyte chemoattractant protein (MCP)-1, and macrophage inflammatory protein (MIP)-1alpha and significantly lower levels of eotaxin compared with D-NAME-treated mice. Cultures of dispersed lung cells from L-NAME-treated mice also produced significantly more IL-10 and less IL-12 compared with similar numbers of dispersed lung cells from D-NAME-treated mice. Cultures of isolated lung fibroblasts from L-NAME-treated mice expressed higher levels of C-C chemokine receptor 2 (CCR2) and CCR3 mRNA and contained less MCP-1 and eotaxin protein than a similar number of fibroblasts from D-NAME-treated mice. Thus, nitric oxide appears to regulate the deposition of extracellular matrix in lung granulomas through the modulation of the cytokine and chemokine profile of these lesions. Alterations in the cytokine, chemokine, and procollagen profile of this lesion may be a direct effect of nitric oxide on the pulmonary fibroblast and provide an important signal for regulating fibroblast activity during the evolution of chronic lung disease.

Novel roles for chemokines and fibroblasts in interstitial fibrosis

BACKGROUND

Regardless of its involvement in either wound healing or excessive fibrosis, the interstitial fibroblast can now be considered an important early participant in inflammatory responses. Although it is recognized that certain immune cells and proinflammatory mediators are intricately linked to fibrotic disease, little is presently known about the manner in which these mediators and cells are orchestrated to a fibrotic finale. Experimental studies have shown that interstitial fibroblasts are capable of participating in an inflammatory response by promoting direct fibroblast-to-immune cell communication and/or modulating the release of soluble mediators that are mutually recognized by both types of cells.

METHODS

Primary cultures of murine fibroblasts were recovered from either normal tissue or tissue undergoing a cell-mediated inflammatory response. These stromal cells were assessed for the expression of various cytokines and chemokines indicative of a type 1 or type 2 response. In addition, the fibroblasts were co-cultured with mononuclear cells to assess the cell-to-cell communication.

RESULTS

Fibroblasts recovered from different cell-mediated inflammatory responses demonstrated a dramatic alteration in their cytokine profile. Fibroblasts recovered from the type 2 immune response produced high levels of monocyte chemotactic protein-1 (MCP-1), as compared to the normal fibroblasts and fibroblasts recovered from the type 1 lesion. Mononuclear cells co-cultured with fibroblasts induced a contact-dependent expression of elevated levels of chemokines, especially the macrophage-derived MIP-1 alpha. Thus, both fibroblasts themselves and fibroblasts co-cultured with immune-inflammatory cells have the ability to participate in the maintenance of an inflammatory response via the expression of chemokines.

CONCLUSIONS

Our laboratory and others have addressed the role of chemotactic cytokines or chemokines in the fibrotic process, and have demonstrated that fibroblasts are capable of modulating the activation of various immune cells that have been implicated in fibrotic disease. In addition, the interstitial fibroblast is capable of regulating its own behavior within the interstitial environment via the expression of chemokines and chemokine receptors. Thus, novel strategies aimed at preventing fibrotic disease will likely need to address the early engagement of inflammatory cells by fibroblasts, and possibly modulate the ability of fibroblasts to generate and/or recognize profibrotic signals supplied by chemokines.

Procollagen types I and III aminoterminal propeptide levels during acute respiratory distress syndrome and in response to methylprednisolone treatment

Ineffective lung repair in patients with unresolving acute respiratory distress syndrome (ARDS) is accompanied by progressive fibroproliferation, inability to improve lung injury score (LIS), progressive multiple organ dysfunction syndrome (MODS), and an unfavorable outcome. Our aim was to investigate the relationship between fibrogenesis, pulmonary and extrapulmonary organ dysfunction, and outcome during the natural course of ARDS and in response to prolonged methylprednisolone treatment. We investigated 29 patients with ARDS. We obtained serial measurements of plasma and BAL procollagen aminoterminal propeptide type I (PINP) and type III (PIIINP) levels and components of the lung injury score (LIS) and MODS score. A reduction in LIS greater than one point from day 1 to day 7 of ARDS divided patients in improvers (group 1, n = 7) and nonimprovers (n = 22). Nonimprovers included those who were recruited (day 9 +/- 3 of ARDS) into a prospective, randomized, double-blind, placebo-controlled trial investigating prolonged methylprednisolone therapy in unresolving ARDS (group 2, n = 17), and those who died (all by day 10 of ARDS) prior to meeting eligibility criteria for the randomized trial (group 3, n = 5). On day 1 of ARDS, plasma PINP or PIIINP levels were elevated in all patients. By day 7 of ARDS, mean plasma PINP or PIIINP levels were unchanged in group 1 but increased significantly in group 2 (p = 0. 0002) and group 3 (p = 0.03). On day 7, patients with plasma PINP levels less than 100 ng/ml were 2.5 times more likely to survive (95% CI: 0.855-7.314), and patients with plasma PIIINP levels greater than 25 ng/ml were nine times more likely to die (95% CI: 1. 418-55.556). In group 2, patients taking placebo (n = 6) had no change in plasma PINP or PIIINP levels over time, while patients treated with methylprednisolone (n = 11) had a rapid and sustained reduction in mean plasma and bronchoalveolar lavage (BAL) PINP and PIIINP levels. By day 3 of treatment, mean plasma PINP and PIIINP levels (ng/ml) decreased from 100 +/- 9 to 45 +/- 8 (p = 0.0001) and 31 +/- 3 to 12 +/- 3 (p = 0.0008), respectively. After 8 to 15 d of methylprednisolone, mean BAL PINP and PIIINP levels (ng/ml) decreased from 63 +/- 25 to 6 +/- 23 (p = 0.002) and 42 +/- 5 to 10 +/- 3 (p = 0.003), respectively. Estimated partial correlation coefficients indicated that as plasma PINP and PIIINP levels decreased over the first 7 d of methylprednisolone treatment, positive end-expiratory pressure, creatinine, bilirubin, and temperature also decreased, while PaO2:FIO2 increased. In early ARDS, plasma PINP and PIIINP levels are elevated and continue to increase over time in those not improving. Among nonimprovers, those randomized to prolonged methylprednisolone treatment had a rapid and significant reduction in plasma and BAL aminoterminal propeptide levels and similar changes in lung injury and MODS scores. These findings provide additional evidence of an association between biological efficacy and physiologic response during prolonged methylprednisolone treatment of unresolving ARDS.

Interleukin-6 production in hemorrhagic shock is accompanied by neutrophil recruitment and lung injury

Hemorrhagic shock (HS) initiates an inflammatory cascade that includes the production of cytokines and recruitment of neutrophils (PMN) and may progress to organ failure, inducing acute respiratory distress syndrome (ARDS). To examine the hypothesis that interleukin-6 (IL-6) contributes to PMN infiltration and lung damage in HS, we examined the lungs of rats subjected to unresuscitated and resuscitated HS for the production of IL-6 and activation of Stat3. Using semiquantitative RT-PCR, we found a striking increase in IL-6 mRNA levels only in resuscitated HS, with peak levels observed 1 h after initiation of resuscitation. Increased IL-6 protein expression was localized to bronchial and alveolar cells. Electrophoretic mobility shift assay of protein extracts from shock lungs exhibited an increase in Stat3 activation with kinetics similar to IL-6 mRNA. In situ DNA binding assay determined Stat3 activation predominantly within alveoli. Intratracheal instillation of IL-6 alone into normal rats resulted in PMN infiltration into lung interstitium and alveoli, marked elevation of bronchoalveolar lavage cellularity, and increased wet-to-dry ratio. These findings indicate that IL-6 production and Stat3 activation occur early in HS and may contribute to PMN-mediated lung injury, including ARDS after HS.

Time course of immunological markers in patients with the systemic inflammatory response syndrome: evaluation of sCD14, sVCAM-1, sELAM-1, MIP-1 alpha and TGF-beta 2

BACKGROUND

The systemic inflammatory response syndrome (SIRS) is viewed as a system-wide inflammatory response. Up until now, no parameter has been available for predicting the development of septic shock. In the present study, we evaluated the usefulness of serum levels of CD14, vascular cells adhesion molecule-1 (VCAM-1), endothelial leucocyte adhesion molecule-1 (ELAM-1), macrophage inflammatory protein (MIP) 1 alpha and transforming growth factor beta 2 (TGF-beta 2) as early markers of outcome in patients with SIRS.

METHODS

A group of 28 SIRS patients (13 survivors/15 non-survivors) was compared with a healthy control group and with patients with local inflammation. Blood samples were analysed on days 0, 4 and 7. Proinflammatory parameters such as sCD14, sVCAM-1, sELAM-1, MIP-1 alpha and anti-inflammatory parameters such as TGF-beta 2 were determined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

At the beginning, all evaluated proinflammatory immunological parameters with the exception of sVCAM-1 were significantly increased in patients with SIRS compared with the healthy control group. However, no significant difference could be observed for all immunological parameters comparing survivors and non-survivors, with the exception of interleukin (IL) 6 at day 7.

CONCLUSION

All evaluated proinflammatory parameters were increased in patients with SIRS during the course of the disease. However, the parameters have no correlation with outcome and prognosis of SIRS patients.

Upregulation of xanthine oxidase by lipopolysaccharide, interleukin-1, and hypoxia. Role in acute lung injury

LPS and selected cytokines upregulate xanthine dehydrogenase/xanthine oxidase (XDH/XO) in cellular systems. However, the effect of these factors on in vivo XDH/XO expression, and their contribution to lung injury, are poorly understood. Rats were exposed to normoxia or hypoxia for 24 h after treatment with LPS (1 mg/kg) and IL-1beta (100 microg/kg) or sterile saline. Lungs were then harvested for measurement of XDH/XO enzymatic activity and gene expression, and pulmonary edema was assessed by measurement of the wet/dry lung weight ratio (W/D). Although treatment with LPS + IL-1beta or hypoxia independently produced a 2-fold elevation (p < 0. 05 versus exposure to normoxia and treatment with saline) in lung XDH/XO activity and mRNA, the combination of LPS + IL-1beta and hypoxia caused a 4- and 3.5-fold increase in these values, respectively. XDH/XO protein expression was increased 2-fold by hypoxia alone and 1.3-fold by treatment with LPS + IL-1beta alone or combination treatment. Compared with normoxic lungs, W/D was significantly increased by exposure to hypoxia, LPS + IL-1beta, or combination treatment. This increase was prevented by treatment of the animals with tungsten, which abrogated lung XDH/XO activity. In conclusion, LPS, IL-1beta, and hypoxia significantly upregulate lung XDH/XO expression in vivo. The present data support a role for this enzyme in the pathogenesis of acute lung injury.

An analysis of interleukin-8, interleukin-6 and C-reactive protein serum concentrations to predict fever, gram-negative bacteremia and complicated infection in neutropenic cancer patients

A prospective study was performed to assess the potential value of interleukin (IL)-8, IL-6, and C-reactive protein (CRP) serum levels to predict fever, gram-negative bacteremia and complicated infection in neutropenic patients with cancer. Serum samples were obtained three times a week during 208 neutropenic episodes following cytotoxic chemotherapy. Fever of any cause developed during 104 out of 191 evaluable episodes. Serum levels of neither cytokine nor CRP were predictive of fever within more than 24 h before its onset. Unlike CRP, both IL-6 and IL-8 serum levels were significantly different between microbiologically documented infections and unexplained fevers. The highest values of IL-6 and IL-8 were observed in episodes of gram-negative bacteremia. Using receiver-operating-characteristic curves, the analysis of cytokine levels measured around the onset of fever indicated that IL-8 is potentially useful for predicting gram-negative bacteremia, with a high negative predictive value of > 90% and a moderate positive predictive value of 50% (sensitivity, 70%; specificity, 91%). In patients with persistent fever, predictions of further clinical complications, defined as prolonged fever of more than 7 days' duration, pneumonia, shock and/or death due to infection, were best predicted by IL-6. With an IL-6 cutoff value of 250 pg/ml in samples obtained 8 to 32 h after onset of fever, the positive predictive value was 92%, the negative predictive value 91% (sensitivity, 85%; specificity, 95%). The positive predictive value of IL-6 in samples obtained another 24 h later from patients still febrile remained > 90%, but the negative predictive value dropped to 47%. In any of the analyses, the predictive values of CRP levels were poor and inferior to either cytokine. These findings may have clinical value in identifying subgroups of patients requiring different therapeutic approaches.

Inflammatory mediators in bronchoalveolar lavage fluid and plasma in leukocytopenic patients with septic shock-induced acute respiratory distress syndrome

OBJECTIVES

The acute respiratory distress syndrome (ARDS) is a frequent complication of severe sepsis and a major cause of death in patients with hematologic malignancy during chemotherapy-induced leukocytopenia. Inflammatory mediators are important modulators of host response to injury and have been found to be increased in the bronchoalveolar lavage (BAL) fluid of nonleukocytopenic patients with ARDS. Since inflammatory cytokines in plasma of nonleukocytopenic patients seem to be efficient predictors of the course of ARDS, we examined this hypothesis in leukocytopenic patients with septic shock-induced ARDS.

DESIGN

Prospective, observational study.

SETTING

Intensive care unit (ICU) of a university hospital.

PATIENTS

Nineteen patients with leukocytopenia (white blood cell count of <1/nL) following cytoreductive chemotherapy for malignant disorders and severe sepsis with shock-induced ARDS (Murray score of >2.5).

INTERVENTIONS

BAL and plasma sampling and ICU management.

MEASUREMENTS AND MAIN RESULTS

The proinflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 were measured in the BAL aspirates and in plasma samples, both obtained within 18 hrs after onset of ARDS. Hemodynamic and oxygen metabolism data were measured immediately before plasma samples were taken and BAL was performed. Of the 19 patients studied, nine patients responded to ICU treatment (e.g., mechanical ventilation as indicated by PaO2/FIO2, FIO2, shunt volume, and course of pulmonary infiltrates), whereas ten patients did not respond. BAL cytokine concentrations were significantly increased in nonresponders in comparison with responding patients (TNF-alpha, p = .021; IL-6, p = .008; IL-8, p = .019). In contrast, we did not observe any differences between the groups in terms of plasma cytokine concentrations.

CONCLUSION

Determination of cytokine concentrations in BAL samples may be useful for evaluation of severity and course of ARDS in leukocytopenic patients, whereas measurement of plasma cytokines is not helpful.

Nutritional modulation of immunity and the inflammatory response

The metabolic derangements of the injured or stressed patient are governed by multiple factors that partially include the severity of insult, preexisting illnesses, available energy reserves, and appropriateness of intervention. The normal response to injury is further characterized by the release of proinflammatory and antiinflammatory mediators that exert potent effects on cellular and organ function. Although brief periods of starvation and catabolism are tolerable in otherwise healthy individuals, protracted nutritional deprivation can manifest as immunocompromise, irreversible organ injury, and late mortality. Moreover, patients with severe injuries or preexisting illnesses who exhibit exaggerated inflammatory responses may be further predisposed to such deleterious consequences following the insult. The optimal supply of appropriate nutrients and substrates in such circumstances has often been championed as a necessary means of restoring proper cellular metabolism, wound healing, immune competence, and proper organ function. However, much debate surrounds the present efficacy of nutritional therapy in modulating the immune response associated with injury and stress. This article seeks to assess the merits of nutritional therapeutics in the injured patient through available biological and clinical evidence.

Prognostic value of MIP-1 alpha, TGF-beta 2, sELAM-1, and sVCAM-1 in patients with gram-positive sepsis

The aim of the present study was to evaluate the potential prognostic value of MIP-1 alpha, TGF-beta 2, sELAM-1, and sVCAM-1 in patients with gram-positive sepsis. Twenty-eight patients with gram-positive sepsis were compared to 11 patients with gram-negative sepsis and 15 healthy volunteers. Sepsis was defined by the criteria of Bone et al. (Crit. Care Med. 21, 5447-5463, 1993) and by isolation of at least two positive blood cultures with gram-positive/gram-negative bacteria. Plasma samples for determination of the immunological parameters were collected daily. Analysis of cytokines and adhesion molecules was performed on days 0 (day of sepsis criteria fulfillment), 4, and 7 (or 1 day before death). In the gram-positive group 10 of 28 patients died; in the gram-negative group 4 of 11 died. Only sELAM-1 plasma concentrations were found to be a useful early parameter in predicting patients' outcome in gram-positive sepsis. sELAM-1 concentrations at the onset of the study (day 0) were significantly higher in the nonsurviving patients than those in the survivors. MIP-1 alpha levels were significantly higher only on days 4 and 7. With regard to the measured plasma concentrations we believe that MIP-1 alpha is not a useful parameter for predicting patients' prognosis. The increase of sVCAM-1 might play a role in the pathogenesis of gram-positive sepsis; however, it could not be relied upon as an early prognostic parameter. The potential role of TGF-beta 2 in the development of gram-positive sepsis could not evaluated in the present study, whereas routine measurements of TGF-beta 2 offered no additional prognostic information.

Interleukin-6 augments neutrophil cytotoxic potential via selective enhancement of elastase release

BACKGROUND

Interleukin-6 (IL-6) appears to be a reliable marker of disease severity in critically ill patients at risk for inflammatory organ injury such as ARDS and MOF. Debate continues, however, as to whether this pleiotropic cytokine acts principally as a proinflammatory or counterregulatory mediator. Because the polymorphonuclear leukocyte (PMN) is a central effector of inflammatory injury, defining the effects of IL-6 on mechanisms of PMN cytotoxicity may be revealing. Previous investigations of PMN release of reactive oxygen species demonstrate that IL-6 in concert with other mediators may augment cytotoxicity. We hypothesized that IL-6 alone increases PMN cytotoxic potential through selective enhancement of elastase release.

MATERIALS AND METHODS

Isolated human PMNs were incubated with IL-6 in the physiologic range observed in critically ill patients (0.1 to 100 ng/ml) for 10 to 30 min. Selected cells were then activated with fMLP (1 microM). Elastase release was measured by specific cleavage of AAPV-pNA and compared to untreated cells and cells activated with formyl-Met-Leu-Phe (fMLP; 1 microM) alone. To determine if changes in elastase release might be due to IL-6 induced generation of PAF, WEB 2347 (50 microM) was preincubated with selected cells for 20 min. Surface expression of beta 2 integrins was measured by flow cytometry after incubating with labeled antibodies to CD11b and CD18.

RESULTS

IL-6 alone at 100 ng/ml augmented basal elastase release by 116 +/- 41% within 10 min. Doses as low as 0.1 ng/ml stimulated elastase release when the incubation time was increased to 30 min. After 30 min of incubation, IL-6 at all doses examined augmented the elastase release of fMLP-activated cells (increases of 33 to 45%). WEB 2347 preincubation did not block augmentation of elastase release by IL-6 at 10 ng/ml. IL-6 had no effect on surface expression of beta 2 integrins at 10 ng/ml.

CONCLUSIONS

IL-6 alone enhances both basal and fMLP-stimulated elastase release by PMNs. This proinflammatory action on PMNs may help explain the observed correlation between circulating IL-6 levels and inflammatory organ injury.

Peripheral edema after esophagectomy

Patients who have undergone major surgery such as esophagectomy may develop peripheral edema in the immediate postoperative period, the cause of which is not fully understood. The purpose of this study was therefore to determine the mechanism of this phenomenon. Finger edema was measured as a marker for peripheral edema before and after esophagectomy in eight patients. Plasma interleukin-6 (IL-6) was also measured by an enzyme-linked immunosorbent assay. Finger edema markedly increased in the immediate postoperative period and remained significantly elevated until after postoperative day (POD) 3 compared to the preoperative value (P < 0.05). Plasma IL-6 also markedly increased in the immediate postoperative period and remained significantly elevated on POD 2 compared to the preoperative value (P < 0.05). The degree of finger edema highly correlated with the level of plasma IL-6 (r = 0.71, P = 0.0001). These findings indicate that peripheral edema after esophagectomy might be caused by a proinflammatory cytokine response.

Inflammatory cytokines in BAL fluid and pulmonary hemodynamics in high-altitude pulmonary edema

To evaluate the pathogenesis of high-altitude pulmonary edema (HAPE), we performed bronchoalveolar lavage (BAL) and pulmonary hemodynamic studies in seven patients with HAPE at its early stage. We measured cell counts, biochemical contents, and concentrations of pro-inflammatory cytokines including interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor (TNF)-alpha and of anti-inflammatory cytokines including IL-1 receptor antagonist (ra) and IL-10 in the BAL fluid (BALF). All patients showed increased counts for total cells, alveolar macrophages, neutrophils and lymphocytes, and markedly elevated concentrations of proteins, lactate dehydrogenase, IL-1beta, IL-6, IL-8, TNF-alpha and IL-1ra. The levels of IL-1alpha and IL-10 were not increased. Patients also showed pulmonary hypertension with normal wedge pressure. Both the driving pressure obtained as pulmonary arterial pressure minus wedge pressure and the PaO2 under room air were significantly correlated with the concentrations of IL-6 and TNF-alpha in the BALF. These findings suggest that the inflammatory cytokines play a role at the early stage of HAPE and might be related to pulmonary hypertension.

Fatal adenovirus infection associated with new genome type

The first fatal case caused by the new genome type 7i is described in an 8-month-old boy requiring long-term respiratory support who developed Reye's syndrome, acute respiratory distress, and bronchiolitis obliterans with fatal evolution. Adenovirus was detected in nasopharyngeal secretions and was persistently positive during hospitalization. IgM and IgG adenovirus antibody titers measured in serum by enzyme-linked immunoassay (EIA) were 1:32 and 1:800, respectively. Serum interleukins (IL) and interferons (IFN) measured by EIA were as follows: IL-2, 110 pg/ml; IL-6, 300 pg/ml; IL-8, 7,000 pg/ml; TNF-alpha, 35 pg/ml, IL-1 and IL-4 undetectable, IFN-alpha 2,200 pg/ml, and IFN-gamma 700 pg/ml. Virologic studies showed that adenovirus isolated belonged to subgenus B, and digestion of viral DNA with Bam HI, Sma I, Bgl II, and Hind III identified the isolate as belonging to genome type 7i. Autopsy showed bronchiolitis obliterans with diffuse alveolar damage and perivenular fatty degeneration with polymorphonuclear infiltrates in the periportal spaces. The difficulty in obtaining adequate oxygenation with minimization of iatrogenic oxygen injury is discussed.

Aerosolized antibiotics in mechanically ventilated patients: delivery and response

OBJECTIVES

To determine whether aerosolized antibiotics can be delivered efficiently to the lower respiratory tract in mechanically ventilated patients and to define possible clinical responses to these agents.

DESIGN

Prospective serial study with cases as their own control.

SETTING

A 10-bed respiratory care unit for patients with chronic respiratory failure in a tertiary university hospital.

PATIENTS

Ventilator dependent patients who are otherwise medically stable. All subjects had a tracheostomy in place, were colonized with gram-negative organisms, and produced purulent secretions which could be sampled daily.

INTERVENTIONS

Six patients received nine courses of nebulized therapy, which consisted of treatments every 8 hrs of gentamicin (80 mg) or amikacin (400 mg) for 14 to 21 days.

MEASUREMENTS AND MAIN RESULTS

Doses to the lung were measured using radiolabeled aerosols and antibiotic concentrations in sputum. The response was assessed by a) changes in the volume of respiratory secretions; b) effect on bacterial cultures; and c) changes in the inflammatory cells and mediators of inflammation of the respiratory secretions (interleukin-1beta [IL-1beta], tumor necrosis factor-alpha [TNF-alpha], soluble intercellular adhesion molecule-1 [sICAM-1], and human leukocyte elastase). On average, patients inhaled 35.4 +/- 5.08% (SD) of the initial drug placed in the nebulizer (neb-charge). Of this neb-charge, 9.50 +/- 2.78% was found on the respirator tubing and tracheostomy tube and 21.9 +/- 7.15% was actually deposited in the lungs. The remainder of the neb-charge was sequestered in the nebulizer or exhaled. Trough sputum concentrations averaged 4.3 +/- 3.2 microg/mL/mg neb-charge (range 234 to 520 microg/mL) and increased to 16.6 +/- 8.1 microg/mL/mg neb-charge (range 1005 to 5839 microg/mL) immediately after therapy (p = .011). Serum concentrations were undetectable in most determinations except for a single patient who was in renal failure (8.7 microg/mL amikacin). Treatment caused a significant reduction in the volume of secretions (p = .002). Weekly cultures revealed eradication of Pseudomonas species, Serratia marcescens, and Enterobacter aerogenes in most of the trials. Before antibiotic treatment, concentrations of IL-1beta were higher than those reported in acute respiratory distress syndrome. Throughout the duration of the study, IL-1beta correlated significantly with the absolute number of macrophages, neutrophils, and lymphocytes, respectively (r2 = .55, p = .002; r2 = .50, p < .0004, r2 = .36, p = .005). TNF-alpha concentrations correlated with lymphocytes and neutrophils, respectively (r2 =.27, p = .013, r2 = .21, p = .033). sICAM-1 concentrations increased two-fold (p < .001) during treatment and then returned to baseline. The volume of secretions was related to neutrophil and IL-1beta concentrations, respectively (r2 = .25, p = .008, r2= .35, p = .006).

CONCLUSIONS

Nebulizer delivery of aerosolized aminoglycosides is efficient and predictable. In our clinical model, aerosolized antibiotics can make a significant impact on respiratory secretions. Their efficacy in treatment of critically ill patients remains to be determined.

High frequency oscillatory ventilation attenuates the activation of alveolar macrophages and neutrophils in lung injury

BACKGROUND: Recent investigations have shown that leukocyte activation is involved in the pathogenesis of ventilator-associated lung injury. This study was designed to investigate whether the inflammatory responses and deterioration of oxygenation in ventilator-associated lung injury are attenuated by high-frequency oscillatory ventilation (HFO). We analyzed the effects of HFO compared with conventional mechanical ventilation (CMV) on the activation of pulmonary macrophages and neutrophils in 10 female rabbits. RESULTS: After surfactant depletion, the rabbits were ventilated by CMV or HFO at the same mean airway pressure. Surfactant-depletion followed by 4 h mechanical ventilation hindered pulmonary oxygenation in both groups. Impairment of oxygenation was less severe in the HFO group than in the CMV group. In the HFO group the infiltration of granulocytes into alveolar spaces occurred more readily than in the CMV group. Compared with CMV, HFO resulted in greater attenuation of beta2-integrin expression, not only on granulocytes, but also on macrophages. CONCLUSIONS: In the surfactant-depleted lung, the activation of leukocytes was attenuated by HFO. Reduced inflammatory response correlated with decreased impairment of oxygenation. HFO may reduce lung injury via the attenuation of pulmonary inflammation.

Role of CD18-ICAM-1 in the entrapment of stimulated leukocytes in alveolar capillaries of perfused rat lungs

This study aimed to examine the behavior of stimulated leukocytes in the pulmonary microcirculation. The leukocyte-endothelium interaction was visualized under physiological shear rates in perfused rat lungs using high-speed confocal laser video microscopy. Leukocytes labeled with carboxyfluorescein were stimulated with cytokine-induced neutrophil chemoattractant (CINC/gro), which caused L-selectin shedding and inverse upregulation of CD18. Neither unstimulated nor stimulated leukocytes exhibited rolling in either pulmonary arterioles or venules, whereas both were sequestered in capillaries. Approximately 50% of stimulated leukocytes showed a transient cessation of movement in pulmonary capillaries. The CINC/ gro stimulation, which inhibited leukocyte rolling and adhesion to mesenteric venules, reduced leukocyte velocity and increased leukocytes in pulmonary capillaries. Pretreatment with monoclonal antibodies against intercellular adhesion molecule-1 (ICAM-1) or CD18 attenuated these changes. Confocal microfluorography revealed constitutive expression of ICAM-1 not only in venules but also abundantly in capillary networks. These results suggest that selectin-independent, CD18-ICAM-1-dependent capillary sequestration is one of the major mechanisms by which activated leukocytes accumulate in the lungs.

The systemic inflammatory response in the development of ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is the most frequent occurring infection among mechanically ventilated patients. The clinical presentation of VAP ranges from relatively benign to a severe illness with septic shock. The influence of VAP on patient outcome has not been elucidated and its effects on the inflammatory response of the host are unknown. In a case-control study, the systemic inflammatory response was investigated in patients developing VAP as compared with control patients matched on duration of mechanical ventilation and underlying diseases. Patients developing VAP (n = 42) were matched to a single control (without VAP), who was matched on seven variables. VAP was diagnosed with bronchoscopic techniques. The inflammatory response, reflected by circulating levels of interleukin-6 (IL-6) and interleukin-8 (IL-8), was determined on the day of diagnosis (or day of matching for controls), 4 and 2 d before diagnosis, and 2 d after diagnosis. The development of VAP was not associated with an increase in circulating levels of IL-6 or IL-8. Among patients in which VAP was associated with a clinical presentation of severe sepsis or septic shock (n = 10), IL-6 and IL-8 levels increased and were higher than in the corresponding controls. Moreover, 60% of cases with severe sepsis or septic shock died as compared with 20% of their matched controls (p = 0.06). Mortality rates were similar in patients with uncomplicated VAP and their matched controls (25% and 34%, respectively). High circulating levels of IL-6 and IL-8 were associated with higher mortality rates. The clinical picture of VAP can be subdivided into different types, ranging from uncomplicated to an infection associated with severe sepsis or septic shock, elevated circulating levels of IL-6 and IL-8, and an increased mortality rate.

Anti-interleukin-8 monoclonal antibody reduces free radical production and improves hemodynamics and survival rate in endotoxic shock in rabbits

BACKGROUND

Although high levels of interleukin-8 (IL-8) have been found in patients with sepsis and a monoclonal antibody (MoAb) against IL-8 has been successfully used in some animal models of inflammation, no specific therapeutic agent against IL-8 has been tested for the treatment of sepsis. We studied the effects of a MoAb against IL-8 in the treatment of endotoxic shock with a prospective randomized rabbit endotoxic shock model.

METHODS

Twenty New Zealand white rabbits were anesthetized and divided into four groups: normal, anti-IL-8, control-Ab, and lipopolysaccharide (LPS). Anti-IL-8 and control-Ab groups received a MoAb (immunoglobulin G, 3 mg/kg) 5 minutes before the LPS injection. All groups, except the normal group, received a continuous 20-minute infusion of LPS (500 micrograms/kg). The normal group received NaCl (0.9%) rather than LPS.

RESULTS

The 7-day survival rates were 100% for normal group, 80% for anti-IL-8 group, 40% for control-Ab group, and 0% for LPS group. Compared with the LPS group, anti-IL-8 rabbits had a smaller decrease in mean arterial blood pressure (p < 0.05) and increased urinary volume (p < 0.05). Anti-IL-8 rabbits had lower plasmatic levels of IL-1 beta, less free radical production (p < 0.05), and a higher survival rate (p < 0.01).

CONCLUSIONS

IL-8 plays a significant role in endotoxic shock, and IL-8 blockage results in attenuation of the hypotensive and tachypneic effects of LPS, reduced free radical production, and an increased survival rate after lethal endotoxic shock.

Infections and the inflammatory response in acute respiratory distress syndrome

STUDY OBJECTIVE

Systemic inflammatory response syndrome (SIRS) and infections are frequently associated with the development and progression of acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS). We investigated, at onset and during the progression of ARDS, the relationships among (1) clinical variables and biological markers of SIRS, (2) infections defined by strict criteria, and (3) patient outcome. Biological markers of SIRS included serial measurements of inflammatory cytokines (IC)-tumor necrosis factor-alpha (TNF-alpha) and interleukins (IL) 1 beta, 2, 4, 6, and 8-in plasma and BAL fluid.

METHODS

We prospectively studied two groups of ARDS patients: 34 patients treated conventionally (group 1) and nine patients who received glucocorticoid rescue treatment for unresolving ARDS (group 2). Individual SIRS criteria and SIRS composite score were recorded daily for all patients. Plasma IC levels were measured by enzyme-linked immunosorbent assay on days 1, 2, 3, 5, 7, 10, and 12 of ARDS and every third day thereafter while patients received mechanical ventilation. Unless contraindicated, bilateral BAL was performed on day 1, weekly, and when ventilator-associated pneumonia was suspected. Patients were closely monitored for the development of nosocomial infections (NIs).

RESULTS

ICU mortality was similar among patients with and without sepsis on admission (54% vs 40%; p < 0.45). Among patients with sepsis-induced ARDS, mortality was higher in those who subsequently developed NIs (71% vs 18%; p < 0.05). At the onset of ARDS, plasma TNF-alpha, IL-1 beta, IL-6, and IL-8 levels were significantly higher (p < 0.0001) in nonsurvivors (NS) and in those with sepsis (p < 0.0001). The NS group, contrary to survivors (S), had persistently elevated plasma IC levels over time. In 17 patients, 36 definitive NIs (17 in group 1 and 19 in group 2) were diagnosed by strict criteria. No definitive or presumed NIs caused an increase in plasma IC levels above patients' preinfection baseline. Daily SIRS components and SIRS composite scores were similar among S and NS and among patients with and without sepsis-induced ARDS, were unaffected by the development of NI, and did not correlate with plasma IC levels.

CONCLUSIONS

Sepsis as a precipitating cause of ARDS was associated with higher plasma IC levels. However, NIs were not associated with an increase in SIRS composite scores, individual SIRS criteria, or plasma IC levels above patients' preinfection baseline. SIRS composite scores over time were similar in S and NS. SIRS criteria, including fever, were found to be nonspecific for NI. Irrespective of etiology of ARDS, plasma IC levels, but not clinical criteria, correlated with patient outcome. These findings suggest that final outcome in patients with ARDS is related to the magnitude and duration of the host inflammatory response and is independent of the precipitating cause of ARDS or the development of intercurrent NIs.

TNF-alpha in smoke inhalation lung injury

Adult respiratory distress syndrome is a major cause of morbidity in fire victims. Tumor necrosis factor-alpha(TNF-alpha) is edematogenic and has been associated with the etiology of other forms of adult respiratory distress syndrome. In the sheep lymph fistula model, we measured TNF-alpha after 48 (n = 7) or 128 (n = 3) breaths of cotton smoke and compared this with sham controls (n = 5) or controls in which left atrial pressure was elevated to 20 mmHg (n = 5) to increase lymph flow in the absence of inflammation. Smoke induced a rise in lymph flow and pulmonary arterial pressure with either no fall in lymph-to-plasma protein ratio (128 breaths) or a modest fall in lymph-to-plasma protein ratio (48 breaths), consistent with a change in microvascular permeability as well as a rise in microvascular pressure. Lymph concentration of TNF-alpha fell in both groups, although lymph flux (concentration x flow) transiently rose in both. In neither case did TNF-alpha flux exceed that induced by left atrial pressure elevation. TNF-alpha was detectable in only one out of five sheep in alveolar lavage. Thus, by utilizing a sensitive and specific radioimmunoassay, we were unable to demonstrate a role for TNF-alpha in smoke-induced microvascular lung injury in sheep.

Inhibition by interleukin-1 beta and tumor necrosis factor-alpha of the insulin-like growth factor I messenger ribonucleic acid response to growth hormone in rat hepatocyte primary culture

The cytokines are the putative mediators of the catabolic reaction that accompanies infection and trauma. Evidence suggests that their catabolic actions are indirect and potentially mediated through changes in hormonal axis such as the hypothalamo-pituitary-adrenal axis. Insulin-like growth factor I (IGF-I) is a GH-dependent growth factor that regulates the protein metabolism. To determine whether cytokines can directly inhibit the production of IGF-I by the liver, we investigated the regulation of IGF-I gene expression by interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha (10 ng/ml) in a model of rat primary cultured hepatocytes. Hepatocytes were isolated by liver collagenase perfusion and cultured on Matrigel 48 h before experiments. Each experiment was performed in at least three different animals. In the absence of GH, IL-1 beta and TNF-alpha did not affect the IGF-I messenger RNA (mRNA) basal levels, whereas IL-6 increased it by a factor of 2.5 after 24 h (P < 0.05). GH (500 ng/ml) alone stimulated the IGF-I gene expression markedly (5-to 10-fold increase) after 24 h (P < 0.001). IL-1 beta, and TNF-alpha to a lesser extent, dramatically inhibited the IGF-I mRNA response to GH (IL-1 beta: -82%, P < 0.001 and TNF-alpha: -47%, P < 0.01). The half-maximal inhibition of the IGF-I mRNA response to GH was observed for a concentration of IL-1 beta between 0.1 and 1 ng/ml. Moreover, IL-1 beta abolished the IL-6-induced IGF-I mRNA response. In contrast, IL-6 did not impair the IGF-I mRNA response to GH. To determine the potential role of the GH receptor (GHR) and the GH-binding protein (GHBP) in this GH resistance, we assessed the GHR and GHBP mRNAs response to these cytokines. GH alone did not affect the GHR/GHBP mRNA levels. IL-1 beta markedly decreased the GHR and GHBP mRNA levels (respectively, -68% and -60%, P < 0.05). Neither TNF-alpha nor IL-6 affected the GHR/GHBP gene expression. In conclusion, our results show that IL-1 beta, and TNF-alpha to a lesser extent, blunt the IGF-I mRNA response to GH. The resistance to GH induced by IL-1 beta might be mediated by a decrease of GH receptors, as suggested by the marked reduction of GHR mRNA. These findings suggest that decreased circulating IGF-I, in response to infection and trauma, may be caused by a direct effect of cytokines at the hepatocyte level.

The effect of LPS on cytokine synthesis and lung neutrophil influx after hepatic ischemia/reperfusion injury in the rat

OBJECTIVE

To determine if cytokine responses and lung injury induced by intravenous (i.v.) lipopolysaccharide (LPS) at 4 hr were enhanced in rats that had been previously subjected to 30 min of total liver ischemia (Pringle's maneuver) followed by 24 hr or 3 days of reperfusion.

BACKGROUND

Many patients with liver trauma require occlusion of hepatic blood flow to control hemorrhage and facilitate repair. A significant number of these patients subsequently develop the systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction (MOD) characterized by the release of cytokines and tissue neutrophil influx. Macrophages, including Kupffer cells, may be activated by ischemic injury and dysregulation of their response to LPS may contribute to the development of SIRS and acute respiratory distress syndrome.

METHODS

Adult male Sprague-Dawley rats were randomly divided into six groups: three groups received total hepatic ischemia for 30 min and three groups had a sham procedure. Twenty-four hours or 3 days after hepatic ischemia/reperfusion injury, rats were treated with LPS (5 mg/kg) or saline and monitored for 4 hr. We collected serum, bronchoalveolar lavage (BAL) fluid, and lung tissue.

RESULTS

Serum and BAL cytokine concentrations were significantly increased by i.v. LPS; however, hepatic ischemia/reperfusion injury 24 hr or 3 days before iv LPS ameliorated this cytokine response. The LPS-induced pulmonary neutrophil influx and histopathological changes were similar in sham and hepatic ischemia/reperfusion-injured groups.

CONCLUSIONS

Hepatic ischemia/reperfusion injury significantly attenuated the serum and BAL cytokine concentrations, but did not change pulmonary neutrophil influx or histopathological alterations in response to i.v. LPS.

Markers for predicting the development of acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a relatively common, inflammatory lung disorder that is associated with major morbidity and high mortality. The pathogenesis of ARDS is complex, and unfortunately, the development of ARDS in an individual patient is difficult to anticipate. In this chapter, we outline the rationale for why accurately predicting the development of ARDS would be valuable. We also review the accumulated data on approaches for predicting ARDS and discuss the potential difficulties in establishing predictive markers.

Serum MIP-1 alpha and IL-8 in septic patients

We studied blood MIP-1 alpha and IL-8 in 38 septic patients and 5 healthy volunteers. Both chemokines were undetectable in the healthy volunteers. In sepsis, serum MIP-1 alpha was detected in 45% of the patients and Il-8 in 84%. The levels of MIP-1 alpha, but not of IL-8, correlated with CRP, IL-6 and TNF alpha levels. Complications, including various organ failures and mortality, showed no correlation with serum MIP-1 alpha levels. In contrast, we found increased levels of serum IL-8 in septic patients with disseminated intravascular coagulation, central nervous system (CNS) dysfunction or renal failure, and the mortality rate was higher in the IL-8 detectable group than in the IL-8 undetectable group (50% vs 0%, p < 0.05). In conclusion, the production of both MIP-1 alpha and IL-8 was increased and initially detectable levels of circulating IL-8 predicted high mortality in sepsis.

OBJECTIVE

To determine the significance of the C-C chemokine MIP-1 alpha and the C-X-C chemokine IL-8 in sepsis.

DESIGN

Prospective study.

SETTING

Clinical investigation, emergency department and general intensive care unit of university hospital.

PATIENTS AND PARTICIPANTS

38 septic patients and 5 healthy volunteers were studied. Sepsis was diagnosed following the criteria formulated by ACCP/SCCM.

INTERVENTIONS

10-20 ml of blood was drawn from each patient at the time of initial diagnosis of sepsis.

MEASUREMENTS AND RESULTS

MIP-1 alpha and IL-8 were determined by sandwich ELISA. Both chemokines were undetectable in the healthy volunteers. In sepsis, serum MIP-1 alpha was detected in 45% of the patients and IL-8 was detected in 84%. The levels of MIP-1 alpha, but not of IL-8, correlated with CRP, IL-6 and TNF alpha levels. Complications, including various organ failures and mortality, showed no correlation with serum MIP-1 alpha levels. In contrast, we found increased levels of serum IL-8 in patients with disseminated intravascular coagulation (DIC) (p < 0.05), central nervous system (CNS) dysfunction (p < 0.05), renal failure (p < 0.01) and the mortality rates were higher in the IL-8 detectable group than in the IL-8 undetectable group (50% vs 0%, p < 0.05).

CONCLUSIONS

The production of MIP-1 alpha and IL-8 was increased in sepsis. Furthermore, an initially detectable level of circulating IL-8, but not MIP-1 alpha, predicted a high mortality in sepsis diagnosed according to the ACCP/SCCM criteria.

Interleukin-6 in the injured patient. Marker of injury or mediator of inflammation?

OBJECTIVE

The effects of interleukin (IL)-6 in the injured patient are examined in an attempt to clarify the potential pathophysiologic role of IL-6 in the response to injury.

SUMMARY BACKGROUND DATA

Interleukin-6 is an integral cytokine mediator of the acute phase response to injury and infection. However, prolonged and excessive elevations of circulating IL-6 levels in patients after trauma, burns, and elective surgery have been associated with complications and mortality. The mechanistic role of IL-6 in mediating these effects is unclear.

METHODS

A review of current literature is performed to summarize the origins, mechanisms of action, and biologic effects of IL-6 and to characterize the IL-6 response to injury.

RESULTS

Interleukin-6 is a multifunctional cytokine expressed by a variety of cells after a multitude of stimuli, under complex regulatory control mechanisms. The IL-6 response to injury is uniquely consistent and related to the magnitude of the insult. Moreover, the early postinjury IL-6 response correlates with complications as well as mortality.

CONCLUSIONS

Interleukin-6 appears to play an active role in the postinjury immune response, making it an attractive therapeutic target in attempts to control hyperinflammatory provoked organ injury.

Inhibitory effects of interleukin-6 on release of PGI2 by cultured human pulmonary artery smooth muscle cells

We evaluated the effect of interleukin-6 (IL-6) on the production of prostacyclin (PGI2) by cultured human pulmonary artery smooth muscle cells (HPASMC). Incubation of these cells for up to 48 h with IL-6 led to a dose- and time-dependent decrease in the concentration of PGI2 in the culture medium. The incubation of HPASMC with 10 micrograms/ml of lipopolysaccharide (LPS), 200 U/ml of IL-1 beta, or 500 U/ml of TNF alpha for 24 hr significantly increased the concentration of PGI2 in the medium. However, the addition of IL-6 to a medium containing LPS, IL-1 beta, or TNF alpha significantly inhibited the stimulatory effect of those substances on PGI2 production. Such inhibition was closely related to the concentration of IL-6. IL-6 may counteract the roles of LPS and of other cytokines on the regulation of pulmonary vascular tension in endotoxin- and cytokine-mediated disorders such as sepsis and the acute respiratory distress syndrome (ARDS).

Current concepts of sepsis and acute lung injury

Acute respiratory distress syndrome continues to be a vexing clinical problem with no specific therapy. Epidemiologic and basic sciences have advanced our understanding of the clinical syndrome and have brought us to the brink of effective intervention strategies. This article carefully examines the current state of knowledge, with reference to acute lung injury and current efforts, to arrive at effective pharmacologic approaches.

Different pattern of local and systemic release of proinflammatory and anti-inflammatory mediators in severely injured patients with chest trauma

BACKGROUND

Excessive release of proinflammatory cytokines has been involved in pathogenesis of acute respiratory distress syndrome.

DESIGN

Since injured patients with chest trauma reveal a high risk for posttraumatic acute respiratory distress syndrome, local and systemic release of proinflammatory cytokines and their naturally occurring inhibitors were determined in the early posttraumatic period.

MATERIALS AND METHODS

Proinflammatory and anti-inflammatory mediators were measured in plasma and bronchoalveolar lavage fluid (BALF) from 16 patients with multiple injuries including severe chest injury (Injury Severity Score of 34.4 +/- 2.3 points) and compared with healthy volunteers (n = 17).

RESULTS

Tumor necrosis factor-alpha was detectable neither in plasma nor in BALF. Interleukin-1beta and interleukin-8 were significantly increased in BALF from injured patients, while plasma levels were similar in both groups. Soluble tumor necrosis factor receptors p55 and p75 and interleukin-1ra were markedly elevated in plasma (p < or = 0.01) and BALF (p < or = 0.001) from injured patients compared with controls.

CONCLUSION

Highly increased concentrations of proinflammatory cytokines in BALF, but not in circulation, indicate a strong local inflammatory response early after multiple injuries combined with chest injury rather than severe systemic inflammation. In contrast, anti-inflammatory mechanisms seem to be activated locally and systemically.

Acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a serious and complex clinical problem that often threatens the lives of patients. Emerging clinical data suggest that the survival of patients with this disorder may have improved during the last two decades, presumably because of advances in supportive medical care. Among the supportive therapies used to treat patients with ARDS, none is more complex than mechanical ventilation. New strategies for administering mechanical ventilation to patients with ARDS may reduce the occurrence of iatrogenic volotrauma and oxygen toxicity, accounting in part for the recently observed improvements in patient survival. Prevention and cure of ARDS have remained elusive goals because of the lack of specific therapies directed against the known pathogenic factors. Ongoing investigations are aimed at identifying specific therapies to interrupt the mechanisms of inflammation and lung injury responsible for this syndrome. Until such therapies become available, clinicians caring for patients with ARDS should attempt to minimize additional morbidity and mortality resulting from nosocomial infections and iatrogenic injuries.