G-CSF during Escherichia coli versus Staphylococcus aureus pneumonia in rats has fundamentally different and opposite effects

In canine bacterial pneumonia circulating granulocyte counts determine outcome from donor cells

BACKGROUND

In experimental canine septic shock, depressed circulating granulocyte counts were associated with a poor outcome and increasing counts with prophylactic granulocyte colony-stimulating factor (G-CSF) improved outcome. Therapeutic G-CSF, in contrast, did not improve circulating counts or outcome, and therefore investigation was undertaken to determine whether transfusing granulocytes therapeutically would improve outcome.

STUDY DESIGN AND METHODS

Twenty-eight purpose-bred beagles underwent an intrabronchial Staphylococcus aureus challenge and 4 hours later were randomly assigned to granulocyte (40-100 × 109 cells) or plasma transfusion.

RESULTS

Granulocyte transfusion significantly expanded the low circulating counts for hours compared to septic controls but was not associated with significant mortality benefit (1/14, 7% vs. 2/14, 14%, respectively; p = 0.29). Septic animals with higher granulocyte count at 4 hours (median [interquartile range] of 3.81 3.39-5.05] vs. 1.77 [1.25-2.50]) had significantly increased survival independent of whether they were transfused with granulocytes. In a subgroup analysis, animals with higher circulating granulocyte counts receiving donor granulocytes had worsened lung injury compared to septic controls. Conversely, donor granulocytes decreased lung injury in septic animals with lower counts.

CONCLUSION

During bacterial pneumonia, circulating counts predict the outcome of transfusing granulocytes. With low but normal counts, transfusing granulocytes does not improve survival and injures the lung, whereas for animals with very low counts, but not absolute neutropenia, granulocyte transfusion improves lung function.

Antigen delivery to dendritic cells shapes human CD4+ and CD8+ T cell memory responses to Staphylococcus aureus

Intracellular persistence of Staphylococcus aureus favors bacterial spread and chronic infections. Here, we provide evidence for the existence of human CD4⁺ and CD8⁺ T cell memory against staphylococcal antigens. Notably, the latter could provide a missing link in our understanding of immune control of intracellular S. aureus. The analyses showed that pulsing of monocyte-derived dendritic cells (MoDC) with native staphylococcal protein antigens induced release of Th2-associated cytokines and mediators linked to T regulatory cell development (G-CSF, IL-2 and IL-10) from both CD4⁺ and CD8⁺ T cells, thus revealing a state of tolerance predominantly arising from preformed memory T cells. Furthermore, G-CSF was identified as a suppressor of CD8⁺ T cell-derived IFNγ secretion, thus confirming a tolerogenic role of this cytokine in the regulation of T cell responses to S. aureus. Nevertheless, delivery of in vitro transcribed mRNA-encoded staphylococcal antigens triggered Th1-biased responses, e.g. IFNγ and TNF release from both naïve and memory T cells. Collectively, our data highlight the potential of mRNA-adjuvanted antigen presentation to enable inflammatory responses, thus overriding the existing Th2/Treg-biased memory T cell response to native S. aureus antigens.

Staphylococcus aureus is deemed one of the most important nosocomial pathogens but, to date, there are no safe and protective vaccines. In this study we investigate the nature of the preformed T cell response to S. aureus antigens in healthy donors. Our data reveal that CD4⁺ and—so far not described—CD8⁺ T cell memory responses against native staphylococcal antigens exist but are skewed towards minimizing inflammation and promoting tolerance. The T cell response to staphylococcal antigens is characterized by the secretion of typical Th2 cytokines such as IL-5 and IL-13 and mediators associated with formation of T regulatory cells. Most importantly, G-CSF suppresses IFNγ release from pre-existent memory T cells. However, our data reveal that the use of mRNA-encoded antigens to trigger S. aureus-specific T cell responses bears the potential to override the tolerogenic bias. It favors TNF- and IFNγ-releasing T cells and may, thus, represent an innovative tool in prophylactic and therapeutic vaccine development.

Immunotherapy of Sepsis: Blind Alley or Call for Personalized Assessment?

Sepsis is the most frequent cause of death in noncoronary intensive care units. In the past 10 years, progress has been made in the early identification of septic patients and their treatment. These improvements in support and therapy mean that mortality is gradually decreasing, however, the rate of death from sepsis remains unacceptably high. Immunotherapy is not currently part of the routine treatment of sepsis. Despite experimental successes, the administration of agents to block the effect of sepsis mediators failed to show evidence for improved outcome in a multitude of clinical trials. The following survey summarizes the current knowledge and results of clinical trials on the immunotherapy of sepsis and describes the limitations of our knowledge of the pathogenesis of sepsis. Administration of immunomodulatory drugs should be linked to the current immune status assessed by both clinical and molecular patterns. Thus, a careful daily review of the patient's immune status needs to be introduced into routine clinical practice giving the opportunity for effective and tailored use of immunomodulatory therapy.

G-CSF maintains controlled neutrophil mobilization during acute inflammation by negatively regulating CXCR2 signaling

Luo et al. report that CXCR2 ligands are responsible for rapid neutrophil mobilization during early-stage acute inflammation and that G-CSF suppresses this mobilization by negatively regulating CXCR2-mediated intracellular signaling.

Cytokine-induced neutrophil mobilization from the bone marrow to circulation is a critical event in acute inflammation, but how it is accurately controlled remains poorly understood. In this study, we report that CXCR2 ligands are responsible for rapid neutrophil mobilization during early-stage acute inflammation. Nevertheless, although serum CXCR2 ligand concentrations increased during inflammation, neutrophil mobilization slowed after an initial acute fast phase, suggesting a suppression of neutrophil response to CXCR2 ligands after the acute phase. We demonstrate that granulocyte colony-stimulating factor (G-CSF), usually considered a prototypical neutrophil-mobilizing cytokine, was expressed later in the acute inflammatory response and unexpectedly impeded CXCR2-induced neutrophil mobilization by negatively regulating CXCR2-mediated intracellular signaling. Blocking G-CSF in vivo paradoxically elevated peripheral blood neutrophil counts in mice injected intraperitoneally with Escherichia coli and sequestered large numbers of neutrophils in the lungs, leading to sterile pulmonary inflammation. In a lipopolysaccharide-induced acute lung injury model, the homeostatic imbalance caused by G-CSF blockade enhanced neutrophil accumulation, edema, and inflammation in the lungs and ultimately led to significant lung damage. Thus, physiologically produced G-CSF not only acts as a neutrophil mobilizer at the relatively late stage of acute inflammation, but also prevents exaggerated neutrophil mobilization and the associated inflammation-induced tissue damage during early-phase infection and inflammation.

G-CSF drives a posttraumatic immune program that protects the host from infection

Traumatic injury is generally considered to have a suppressive effect on the immune system, resulting in increased susceptibility to infection. Paradoxically, we found that thermal injury to the skin induced a robust time-dependent protection of mice from a lethal Klebsiella pneumoniae pulmonary challenge. The protective response was neutrophil dependent and temporally associated with a systemic increase in neutrophils resulting from a reprioritization of hematopoiesis toward myeloid lineages. A prominent and specific activation of STAT3 in the bone marrow preceded the myeloid shift in that compartment, in association with durable increases in STAT3 activating serum cytokines G-CSF and IL-6. Neutralization of the postburn increase in serum G-CSF largely blocked STAT3 activation in marrow cells, reversing the hematopoietic changes and systemic neutrophilia. Daily administration of rG-CSF was sufficient to recapitulate the changes induced by injury including hematopoietic reprioritization and protection from pulmonary challenge with K. pneumoniae. Analysis of posttraumatic gene expression patterns in humans reveals that they are also consistent with a role for G-CSF as a switch that activates innate immune responses and suppresses adaptive immune responses. Our findings suggest that the G-CSF STAT3 axis constitutes a key protective mechanism induced by injury to reduce the risk for posttraumatic infection.

Inhibition of pulmonary nuclear factor kappa-B decreases the severity of acute Escherichia coli pneumonia but worsens prolonged pneumonia

Introduction

Nuclear factor (NF)-κB is central to the pathogenesis of inflammation in acute lung injury, but also to inflammation resolution and repair. We wished to determine whether overexpression of the NF-κB inhibitor IκBα could modulate the severity of acute and prolonged pneumonia-induced lung injury in a series of prospective randomized animal studies.

Methods

Adult male Sprague-Dawley rats were randomized to undergo intratracheal instillation of (a) 5 × 10⁹ adenoassociated virus (AAV) vectors encoding the IκBα transgene (5 × 10⁹ AAV-IκBα); (b) 1 × 10¹⁰ AAV-IκBα; (c) 5 × 10¹⁰ AAV-IκBα; or (d) vehicle alone. After intratracheal inoculation with Escherichia coli, the severity of the lung injury was measured in one series over a 4-hour period (acute pneumonia), and in a second series after 72 hours (prolonged pneumonia). Additional experiments examined the effects of IκBα and null-gene overexpression on E. coli-induced and sham pneumonia.

Results

In acute pneumonia, IκBα dose-dependently decreased lung injury, improving arterial oxygenation and lung static compliance, reducing alveolar protein leak and histologic injury, and decreasing alveolar IL-1β concentrations. Benefit was maximal at the intermediate (1 × 10¹⁰) IκBα vector dose; however, efficacy was diminished at the higher (5 × 10¹⁰) IκBα vector dose. In contrast, IκBα worsened prolonged pneumonia-induced lung injury, increased lung bacterial load, decreased lung compliance, and delayed resolution of the acute inflammatory response.

Conclusions

Inhibition of pulmonary NF-κB activity reduces early pneumonia-induced injury, but worsens injury and bacterial load during prolonged pneumonia.

Immunomodulators as adjuvants for vaccines and antimicrobial therapy

A highly effective strategy for combating infectious diseases is to enhance host defenses using immunomodulators, either preventatively, through vaccination, or therapeutically. The effectiveness of many vaccines currently in use is due in part to adjuvants, molecules that have little immunogenicity by themselves but which help enhance and appropriately skew the immune response to an antigen. The development of new vaccines necessitates the development of new types of adjuvants to ensure an appropriate immune response. Herein, we review commonly used vaccine adjuvants and discuss promising adjuvant candidates. We also discuss various other immunomodulators (namely cytokines, Toll-like receptor agonists, and host defense peptides) that are, or have potential to be, useful for antimicrobial therapies that exert their effects by boosting host immune responses rather than targeting pathogens directly.

Prevention, diagnosis, therapy and follow-up care of sepsis: 1st revision of S-2k guidelines of the German Sepsis Society (Deutsche Sepsis-Gesellschaft e.V. (DSG)) and the German Interdisciplinary Association of Intensive Care and Emergency Medicine (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin (DIVI))

Practice guidelines are systematically developed statements and recommendations that assist the physicians and patients in making decisions about appropriate health care measures for specific clinical circumstances taking into account specific national health care structures. The 1^st revision of the S-2k guideline of the German Sepsis Society in collaboration with 17 German medical scientific societies and one self-help group provides state-of-the-art information (results of controlled clinical trials and expert knowledge) on the effective and appropriate medical care (prevention, diagnosis, therapy and follow-up care) of critically ill patients with severe sepsis or septic shock. The guideline had been developed according to the “German Instrument for Methodological Guideline Appraisal” of the Association of the Scientific Medical Societies (AWMF). In view of the inevitable advancements in scientific knowledge and technical expertise, revisions, updates and amendments must be periodically initiated. The guideline recommendations may not be applied under all circumstances. It rests with the clinician to decide whether a certain recommendation should be adopted or not, taking into consideration the unique set of clinical facts presented in connection with each individual patient as well as the available resources.

Can we predict the effects of NF-kappaB inhibition in sepsis? Studies with parthenolide and ethyl pyruvate

BACKGROUND

Based partially on encouraging findings from preclinical models, interest has grown in therapeutic inhibition of NF-kappaB to limit inflammatory injury during sepsis. However, NF-kappaB also regulates protective responses, and predicting the net survival effects of such inhibition may be difficult.

OBJECTIVES

To highlight the caution necessary with this therapeutic approach, we review our investigations in a mouse sepsis model with parthenolide and ethyl pyruvate, two NF-kappaB inhibitors proposed for clinical study.

RESULTS

Consistent with published studies, parthenolide decreased NF-kappaB binding activity and inflammatory cytokine release from lipopolysaccharide (LPS) stimulated RAW 264.7 cells in vitro. In LPS-challenged mice (C57BL/6J), however, while both agents decreased lung and kidney NF-kappaB binding activity and plasma cytokines early (1-3 h), these measures were increased later (6-12 h) in patterns differing significantly over time. Furthermore, despite studying several doses of parthenolide (0.25-4.0 mg/kg) and ethyl pyruvate (0.1-100 mg/kg), each produced small but consistent decreases in survival which overall were significant (p < or = 0.04 for each agent).

CONCLUSION

While NF-kappaB inhibitors hold promise for inflammatory conditions such as sepsis, caution is necessary. Clear understanding of the net effects of NF-kappaB inhibitors on outcome will be necessary before such agents are used clinically.

Plasma granulocyte colony-stimulating factor levels correlate with clinical outcomes in patients with acute lung injury

OBJECTIVES

To evaluate the association between plasma granulocyte colony-stimulating factor (G-CSF) levels and clinical outcomes including mortality in patients with acute lung injury (ALI), and to determine whether lower tidal volume ventilation was associated with a more rapid decrease in plasma G-CSF over time in patients with ALI.

DESIGN

Retrospective measurement of G-CSF levels in plasma samples that were collected prospectively as part of a large multicenter clinical trial.

SETTING

Intensive care units in ten university centers.

PATIENTS

The study included 645 patients enrolled in the National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome Clinical Network trial of lower tidal volumes compared with traditional tidal volumes for ALI.

MEASUREMENTS AND MAIN RESULTS

Baseline plasma levels of G-CSF were associated with an increased risk of death and a decrease in ventilator-free days and organ failure-free days in multivariate analyses controlling for ventilation strategy, age, and sex (Odds ratio death 1.2/log10 increment G-CSF, 95% confidence interval 1.01 to 1.4). Stratification of G-CSF levels into quartiles revealed a strong association between the highest levels of G-CSF and an increased risk of death and decreased ventilator-free days and organ failure-free days in multivariate analyses controlling for ventilation strategy, Acute Physiology and Chronic Health Evaluation III score, Pao2/Fio2 ratio, creatinine, and platelet count (p < 0.05). Subgroup multivariate analysis of patients with sepsis as their risk factor for ALI revealed a U-shaped association between mortality and G-CSF levels such that risk increased linearly from the second through fourth (highest) quartiles, yet also increased in the first (lowest) quartile. G-CSF levels decreased over time in both tidal volume groups, and there was no statistical difference in the extent of decrease between ventilator strategies.

CONCLUSIONS

In patients with ALI, plasma G-CSF levels are associated with morbidity and mortality, but these levels are not influenced by tidal volume strategy. In patients with sepsis-related ALI, a bimodal association between baseline plasma G-CSF levels and subsequent morbidity and mortality from this disease was found.

Granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and other immunomodulatory therapies for the treatment of infectious diseases in solid organ transplant recipients

PURPOSE OF REVIEW

Infections continue to cause significant morbidity and mortality in SOT recipients despite major advances in immunosuppressive and antimicrobial regimens. Immunomodulatory cytokines provide a potential means to augment the host immune response to infection. This review will focus on cytokine therapy for the prophylaxis and treatment of infections in solid organ transplant recipients, and will speculate on the potential for further advances in the field.

RECENT FINDINGS

In kidney and liver transplant recipients, granulocyte colony-stimulating factor (G-CSF) has been used successfully to reverse ganciclovir-induced neutropenia or cytomegalovirus-induced neutropenia. Although G-CSF also reversed corticosteroid-induced suppression of the neutrophil respiratory burst in vitro, prophylactic G-CSF failed to reduce infections or mortality in nonneutropenic solid organ transplant recipients. Published clinical experience with granulocyte-macrophage colony-stimulating factor (GM-CSF) in this population has been limited to case reports and a small case series, whereas the use of macrophage colony-stimulating factor (M-CSF) or interferon-gamma (IFN-gamma) has not been systematically investigated in controlled clinical trials.

SUMMARY

Despite encouraging results in vitro and in preclinical models, immunomodulatory cytokines have not met expectations when administered to SOT recipients. Nonetheless, the principle of selective enhancement of innate immunity for the prevention and treatment of infections in this patient population has promise and warrants further study.

Hypercapnic acidosis attenuates severe acute bacterial pneumonia-induced lung injury by a neutrophil-independent mechanism

OBJECTIVE

Deliberate induction of hypercapnic acidosis protects against lung injury after nonseptic lung injury. In contrast, concerns exist regarding the effects of hypercapnic acidosis in the setting of severe pulmonary sepsis. The potential for the effects of hypercapnic acidosis to be neutrophil-mediated remains to be determined. We investigated whether hypercapnic acidosis--induced by adding CO2 to inspired gas--would protect against severe acute lung injury induced by pulmonary Escherichia coli instillation and the role of neutrophils in mediating this effect.

DESIGN

Prospective randomized animal study.

SETTING

University Research Laboratory.

SUBJECTS

Adult male Sprague-Dawley rats.

INTERVENTIONS

In series 1, after induction of anesthesia and tracheostomy placement, animals were randomized to normocapnia (FICO2 0.00, n = 12) or hypercapnic acidosis (FICO2 0.05, n = 12). E. coli (0.5-3.0 x 10(15) colony-forming units) was instilled intratracheally and the animals were ventilated for 6 hrs to allow a severe acute lung injury to evolve. In series 2, animals were randomized to neutrophil depletion or nondepletion before bacterial instillation, in a three-group design: normocapnia alone (Normo + polymorphonuclear neutrophils [PMN], n = 9), normocapnia with neutrophil depletion (Normo - PMN, n = 9), or hypercapnic acidosis with neutrophil depletion (hypercapnic acidosis - PMN, n = 9). After intratracheal E. coli administration these animals were also ventilated for 6 hrs.

RESULTS

Hypercapnic acidosis protected against evolving pneumonia-induced acute lung injury, attenuating the increase in airway pressure, and the decrement in lung compliance and arterial PO2. However, hypercapnic acidosis did not reduce histologic injury. Hypercapnic acidosis also protected against evolving pneumonia-induced acute lung injury in the presence of neutrophil depletion, reducing both physiologic and histologic indices of lung injury.

CONCLUSIONS

Hypercapnic acidosis reduces indices of intratracheal E. coli induced lung injury by a mechanism that seems to be neutrophil-independent.

Comparison of virulence in community-associated methicillin-resistant Staphylococcus aureus pulsotypes USA300 and USA400 in a rat model of pneumonia

BACKGROUND

The predominant genetic background of community-associated methicillin-resistant Staphylococcus aureus has transitioned from USA400 to USA300 in most US communities. The explanation for this shift is unclear. We hypothesized that USA300 must be more pathogenic--specifically, that USA300 would have increased virulence when compared with USA400 in an animal model.

METHODS

Rats were inoculated intratracheally with 1 of 6 S. aureus isolates from the USA300 and USA400 backgrounds. We assessed mortality, in vivo bacterial growth, and histopathology. We assessed the in vitro expression of capsule and of selected genes believed to be important in virulence in S. aureus, including agr, saeRS, sarA, alpha-toxin (hla), and Panton-Valentine leukocidin (pvl).

RESULTS

USA300 isolates were more lethal, produced more severe pneumonia, and had higher in vivo bacterial density in the lung than did USA400 isolates. In vitro expression of agr, saeRS, sarA, hla, and pvl were greater in USA300 isolates. USA300 isolates were unencapsulated, whereas 2 of 3 USA400 isolates produced capsule.

CONCLUSIONS

USA300 isolates were more virulent than USA400 isolates in a model of necrotizing pneumonia. The explanation for this is unclear, but it likely results from increased expression of S. aureus regulatory systems (e.g., agr, saeRS, and sarA) and the resultant upregulation of key virulence factors including alpha-toxin and PVL.

G-CSF induction early in uropathogenic Escherichia coli infection of the urinary tract modulates host immunity

Uropathogenic Escherichia coli (UPEC), the causative agent of approximately 85% of urinary tract infections (UTI), is a major health concern primarily affecting women. During infection, neutrophils infiltrate the bladder, but the mechanism of recruitment is not well understood. Here, we investigated the role of UPEC-induced cytokine production in neutrophil recruitment and UTI progression. We first examined the kinetics of cytokine expression during UPEC infection of the bladder, and their contribution to neutrophil recruitment. We found that UPEC infection induces expression of several pro-inflammatory cytokines including granulocyte colony-stimulating factor (G-CSF, CSF-3), not previously known to be involved in the host response to UTI. G-CSF induces neutrophil emigration from the bone marrow; these cells are thought to be critical for bacterial clearance during infection. Upon neutralization of G-CSF during UPEC infection, we found fewer circulating neutrophils, decreased neutrophil infiltration into the bladder and, paradoxically, a decreased bacterial burden in the bladder. However, depletion of G-CSF resulted in a corresponding increase in macrophage-activating cytokines, such as monocyte chemotactic protein-1 (MCP-1, CCL-2) and Il-1beta, which may be key in host response to UPEC infection, potentially resolving the paradoxical decreased bacterial burden. Thus, G-CSF acts in a previously unrecognized role to modulate the host inflammatory response during UPEC infection.

CYLD is a crucial negative regulator of innate immune response in Escherichia coli pneumonia

Bacteraemic pneumonia is a common cause of sepsis in critically ill patients today and is characterized by dysregulation of inflammation. The genetic factors predisposing to bacteraemic pneumonia are not yet fully understood. Innate immunity is pivotal for host defence against invading bacteria, and nuclear factor-kappa B (NF-kappaB) is central to bacteria-induced inflammation and immune responses. The deubiquitinating enzyme CYLD has been identified as a key negative regulator for NF-kappaB. In the present study, we investigated the role of CYLD in innate immune response in Escherichia coli pneumonia. Upon E. coli inoculation, Cyld(-/-) mice were hypersusceptible to E. coli pneumonia with higher mortality. Innate immune response to E. coli was enhanced in Cyld(-/-) cells and mice. Cyld(-/-) cells exhibited enhanced NF-kappaB activation upon E. coli inoculation, and the enhanced NF-kappaB activation by E. coli was abolished by perturbing IkappaB kinase (IKK) signalling. Furthermore, IKK inhibitor rescued Cyld(-/-) mice from lethal infection during E. coli pneumonia along with reduced inflammation. Taken together, these data showed that CYLD acts as a crucial negative regulator for E. coli pneumonia by negatively regulating NF-kappaB. These findings provide novel insight into the regulation of bacteraemic pneumonia and related diseases and may help develop novel therapeutic strategies for these diseases.

[Diagnosis and therapy of sepsis]

A recent survey conducted by the publicly funded Competence Network Sepsis (Sep- Net) reveals that severe sepsis and/or septic shock occurs in 75,000 inhabitants (110 out of 100,000) and sepsis in 79,000 inhabitants (116 out of 100,000) in Germany annually. This illness is responsible for approx. 60,000 deaths and ranges as the third most frequent cause of death after acute myocardial infarction. Direct costs for the intensive care of patients with severe sepsis alone amount to approx. 1.77 billion euros, which means that about 30% of the budget in intensive care is used to treat severe sepsis. However, until now German guidelines for the diagnosis and therapy of severe sepsis did not exist. Therefore, the German Sepsis Society initiated the development of guidelines which are based on international recommendations by the International Sepsis Forum (ISF) and the Surviving Sepsis Campaign (SSC) and take into account the structure and organisation of the German health care system. Priority was given to the following guideline topics: a) diagnosis, b) prevention, c) causative therapy, d) supportive therapy, e) adjunctive therapy. The guidelines development process was carefully planned and strictly adhered to according to the requirements of the Working Group of Scientific Medical Societies (AWMF).

Prostacyclin in sepsis: A systematic review

According to current literature, infective processes greatly modify both vascular hemodynamics and anti-oxidant properties of affected tissues, causing a change in homeostasis that regulates the correct functioning of all cells responsible for the physiological and metabolic balance of various organs. As a consequence, the response to the infection that has caused the change is also likely to be weaker and, in the case of septic shock, ineffective. In this review, we will take into consideration these mechanisms and then focus on a group of vasodilator drugs (prostacyclin and its analogs) which, though have been used for over 20 years mainly to treat obstructive vascular diseases, have such hemodynamic and anti-inflammatory properties which prevent homeostatic changes. It is obvious that prostacyclin does not definitively have anti-infective characteristics; however, in association with anti-infective drugs (antibiotics, etc.), the effectiveness of the latter appears improved, at least in some circumstances. Similarly, the fact that prostacyclin and its analogs have a cytoprotective effect on the liver and reduce the ischemia-reperfusion damage following liver transplant is not a novelty and evidence that they improve hepatic hemodynamics suggests their use in those pathologies characterized by possible reduced perfusion or ascertained ischemia of the liver.

[Diagnosis and therapy of sepsis. Guidelines of the German Sepsis Society Inc. and the German Interdisciplinary Society for Intensive and Emergency Medicine]

A recent survey conducted by the publicly funded Competence Network Sepsis (SepNet) reveals that severe sepsis and/or septic shock occurs in 75,000 inhabitants (110 out of 100,000) and sepsis in 79,000 inhabitants (116 out of 100,000) in Germany annually. This illness is responsible for approximately 60,000 deaths and ranges as the third most frequent cause of death after acute myocardial infarction. Direct costs for the intensive care of patients with severe sepsis alone amount to approximately 1.77 billion euros, which means that about 30% of the budget in intensive care is used to treat severe sepsis. However, until now German guidelines for the diagnosis and therapy of severe sepsis did not exist. Therefore, the German Sepsis Society initiated the development of guidelines which are based on international recommendations by the International Sepsis Forum (ISF) and the Surviving Sepsis Campaign (SSC) and take into account the structure and organization of the German health care system. Priority was given to the following guideline topics: a) diagnosis, b) prevention, c) causative therapy, d) supportive therapy, e) adjunctive therapy. The guidelines development process was carefully planned and strictly adhered to the requirements of the Working Group of Scientific Medical Societies (AWMF).

Neutrophil apoptosis, activation and anti-inflammatory cytokine response in granulocyte colony-stimulating factor-treated patients with community-acquired pneumonia

BACKGROUND

Despite antibiotic treatment, the mortality of severe community-acquired pneumonia (CAP), especially in patients with severe comorbidity, remains high. Innate defense mechanisms including polymorphonuclear neutrophil (PMN) activation and survival, orchestrated by cytokines, are primarily responsible for the elimination of bacterial organisms from the alveolus.

OBJECTIVES

The aim of this study was to evaluate the effect of granulocyte colony-stimulating factor (G-CSF) on PMN activation, apoptosis and cytokine response in patients with CAP.

METHODS

Patients received a single dose of G-CSF (1 x 300 or 480 microg s.c.) prior to standard antibiotic treatment (n=8) or standard treatment only (n=8). Apoptosis rate and expression of CD11b, CD66b, CD64 and CD114 surface molecules on systemic PMN were assessed using fluorescence-activated cell sorter analysis. Levels of the interleukin-1 receptor antagonist (IL-1 RA), the soluble tumor necrosis factor receptor inhibitor (sTNF-p55) and G-CSF were measured by ELISA.

RESULTS

In the treatment group, 12 h after G-CSF application, neutrophil count increased, neutrophil activation marker CD11b was stimulated (CD11b: 48.6+/-9.7 vs. 71.2+/-17.7, p<0.01), neutrophil apoptosis decreased (apoptosis: 1.36+/-0.27 vs. 0.2+/-0.12%, p <.01) and the concentration of IL-1RA and sTNF-p55 increased (IL-1RA 136.4+/-72.2 vs. 340.1+/-194.6 ng/ml, p<0.01; sTNF-p55,382+/-4,243 vs. 632+/-4,714 ng/ml, p<0.01; control group nonsignificant). These effects were not seen in the control group.

CONCLUSIONS

The application of a single dose of G-CSF in patients with CAP caused a prolonged survival and increased activation of neutrophils combined with a sustained release of anti-inflammatory cytokines.

Hypercapnic acidosis does not modulate the severity of bacterial pneumonia-induced lung injury

OBJECTIVE

Deliberate induction of hypercapnic acidosis protects against lung injury after ischemia-reperfusion, endotoxin-induced, and ventilation-induced lung injury. The efficacy of hypercapnic acidosis in bacterial lung infection, a common cause of acute respiratory distress syndrome, is not known. Furthermore, its effect may differ depending on the presence or absence of antibiotic therapy. We investigated whether hypercapnic acidosis-induced by adding CO2 to inspired gas-would protect against acute lung injury induced by pulmonary Escherichia coli instillation in an in vivo model in the presence and absence of effective antibiotic therapy.

DESIGN

Prospective randomized animal study.

SETTING

University research laboratory.

SUBJECTS

Adult male Wistar-Kyoto rats.

INTERVENTIONS

The animals were anesthetized and ventilated. In series 1, rats were administered intravenous ceftriaxone (100 mg x kg) and randomized to normocapnia (Normocapnia-ABx; Fico2 0.00, n = 10) or hypercapnia (Hypercapnia-ABx; Fico2 0.05, n = 10) groups. E. coli (8.4 x 10 colony forming units) was instilled intratracheally. Series 2 animals did not receive antibiotics. They were randomized to normocapnia (Normocapnia, n = 10) or hypercapnia (Hypercapnia, n = 10) groups, and intratracheal E. coli was administered. All animals were ventilated for 6 hrs.

MEASUREMENTS AND MAIN RESULTS

In series 1, there were no differences between Hypercapnia-ABx and Normocapnia-ABx groups with regard to: (a-a)o2 gradient (mean +/- sem; 215 +/- 13 vs. 252 +/- 22 mm Hg), Pao2, bronchoalveolar lavage neutrophil count, static lung compliance, or histologic injury. Lung bacterial yield was not different between the groups. In series 2, in the absence of antibiotic therapy, there were no differences between Hypercapnia and Normocapnia groups in: (a-a)o2 gradient (mean +/- sem, 345 +/- 25 vs. 332 +/- 23 mm Hg), systemic Pao2, bronchoalveolar lavage neutrophil count, or static lung compliance. Lung bacterial yield was not altered by hypercapnia in either series 1 or 2.

CONCLUSIONS

We conclude that hypercapnic acidosis did not alter the magnitude of the lung injury induced by intratracheal E. coli instillation in the presence or absence of antibiotics.

THE USE OF IMMUNOCOMPROMISED ANIMALS AS MODELS FOR HUMAN SEPTIC SHOCK

Although it is generally understood that no single animal model truly reflects human sepsis, the study of sepsis in immunocompromised animals is highly relevant to human sepsis research. The majority of patients with severe sepsis have significant underlying diseases that may alter innate immune defenses, disrupt microbial clearance mechanisms, and complicate the pathophysiology of human sepsis. Septic shock itself has significant effects upon the innate and adaptive host immune responses that may contribute to a state of sepsis-induced immune dysregulation. A number of animal models of sepsis displaying an array of immunocompromised states are now available. Most of these systems are small animal models with genetically defined defects of immune defenses or acquired defects from receipt of immunosuppressive or myeloablative agents. Greater emphasis should be placed on preclinical models of immunocompromised animals in the future to assess the potential clinical utility of novel drugs for human septic shock.

Effect of recombinant murine granulocyte colony-stimulating factor with or without fluoroquinolone therapy on mixed-infection abscesses in mice

The aim of the study was to determine if immunomodulation of host defense with recombinant murine granulocyte colony-stimulating factor (G-CSF) improves the efficacy of trovafloxacin or moxifloxacin in abscesses containing Bacillus fragilis ATCC 23745 and different Escherichia coli strains varying in virulence. Treatment of mice inoculated with 10(7) CFU B. fragilis and 10(5) CFU low-virulence E. coli with either trovafloxacin (150 mg/kg/day every 24 hours, days 3 to 7) or moxifloxacin (96 mg/kg/day every 12 hours, days 3 to 7), significantly reduced the number of B. fragilis to 6.9 +/- 0.35 and 5.8 +/- 0.10 and that of E. coli to 4.9 +/- 0.09 and 4.2 +/- 0.07 log CFU/abscess for trovafloxacin and moxifloxacin, respectively, compared to controls (B. fragilis 8.7 and E. coli 7.4 log CFU/abscess) on day 8. Also, moxifloxacin was more potent than trovafloxacin. Addition of G-CSF prophylaxis (1 mug once on day -1) or therapy (1 mug/day on days 3 to 7) to fluoroquinolone treatment did not improve the efficacy of fluoroquinolone therapy alone. The effect of moxifloxacin with or without G-CSF prophylaxis on abscesses with a virulent hemolytic E. coli strain was also studied. In moxifloxacin-treated mice, 75% survived infection compared to 10% of controls. Combining moxifloxacin with G-CSF prophylaxis significantly decreased survival (30%) compared to moxifloxacin alone. In addition, G-CSF prophylaxis resulted in a threefold (E. coli) to 100-fold (B. fragilis) increased outgrowth in the abscesses of surviving mice. In conclusion, the addition of G-CSF to a fluoroquinolone is not advisable since, depending on the virulence of the E. coli strains, this might detrimentally influence the outcome of therapy.

Effect of Granulocyte-Monocyte Colony-Stimulating Factor Therapy on Leukocyte Function and Clearance of Serious Infection in Nonneutropenic Patients

STUDY OBJECTIVE

Impaired leukocyte function in patients with serious infections may increase mortality. Granulocyte-monocyte colony-stimulating factor (GM-CSF) broadly activates peripheral monocytes and neutrophils. We performed a clinical trial of GM-CSF in septic, hemodynamically stable patients to see whether GM-CSF treatment improved leukocyte function and mortality.

DESIGN

Randomized, unblinded, placebo-controlled, prospective study.

SETTING

A 600-bed academic tertiary care center with a 120-bed ICU census with a high proportion of immunocompromised, solid-organ transplant recipients.

PATIENTS

Forty adult patients with infections meeting the criteria for the systemic inflammatory response syndrome but without hemodynamic instability or shock.

INTERVENTIONS

Patients with sepsis and a documented infection were randomized to a 72-h infusion of GM-CSF (125 microg/m2) or placebo.

MEASUREMENTS AND MAIN RESULTS

GM-CSF infusion caused the up-regulation of the beta2-integrin adhesion molecule CD11b and the appearance of the activated ("sticky" or "avid") form of the molecule on circulating neutrophils and monocytes. CD11b density and avidity increases in response to the administration of tumor necrosis factor-alpha were blunted prior to treatment in these patients with serious infection. GM-CSF partially repaired this blunted response on both monocytes and neutrophils. It also caused the down-regulation of the adhesion molecule L-selectin on neutrophils and the up-regulation of human leukocyte antigen on monocytes. These changes were consistent with a broad activation of the circulating leukocyte pool. Although mortality and organ failure scores were similar in both groups, infection resolved significantly more often in patients receiving GM-CSF.

CONCLUSIONS

GM-CSF infusion up-regulated the functional markers of inflammation on circulating neutrophils and monocytes and was associated with both the clinical and microbiological resolution of infection. There was no detectable exacerbation of sepsis-related organ failure or other deleterious side effects with the administration of this proinflammatory agent to patients with serious infections.

Granulocyte colony-stimulating factor has differing effects comparing intravascular versus extravascular models of sepsis

BACKGROUND

Previously, neutrophil stimulation with granulocyte colony-stimulating factor (G-CSF) pretreatment increased survival rates in canines challenged with intraperitoneal or intrabronchial Escherichia coli and in rats challenged with intrabronchial Staphylococcus aureus. We investigated whether G-CSF pretreatment would be beneficial with intravascular challenge in these models.

METHODS

Animals were randomized to G-CSF or placebo pretreatment followed by intravenous E. coli challenge in canines (n = 24) or intravenous or intrabronchial S. aureus challenge in rats (n = 273). All animals were treated with antibiotics.

RESULTS

In canines, G-CSF before intravenous E. coli did not decrease mortality rates (7 of 12 [58%] G-CSF vs. 5 of 12 [42%] controls), which contrasted with prior reductions during extravascular infection (10 of 35 [29%] G-CSF vs. 37 of 65 [57%] controls). Consistent with the present and previously published studies in canines, in rats, G-CSF decreased mortality rates with intrabronchial S. aureus (22 of 90 [24%] G-CSF vs. 26 of 51 [51%] controls, p = 0.009) but did not decrease them with intravenous infection (34 of 67 [50%] G-CSF vs. 27 of 65 [42%] controls, p = 0.2) in patterns that were very different (p = 0.005 for the effects of G-CSF with intravascular vs. intrabronchial S. aureus).

CONCLUSION

In contrast to extravascular infection, sepsis with intravascular E. coli in canines and S. aureus in rats may not provide a compartmentalized nidus of bacteria on which G-CSF-stimulated neutrophils can exert a beneficial antimicrobial effect. Extrapolated clinically, a proinflammatory agent like G-CSF may be most beneficial with sepsis related primarily to a compartmentalized extravascular site of infection.

Effect of granulocyte colony-stimulating factor in experimental methicillin resistant Staphylococcus aureus sepsis

Background

Methicillin resistant Staphylococcus aureus (MRSA) is the leading pathogenic cause of nosocomial infections, especially in bacteraemia and sepsis. The essential therapy for MRSA infection is glycopeptides. Therapeutic failure can be seen with this therapy and the mortality is still high. The aim of this study was to evaluate the additional effect of G-CSF on the traditional antibiotic treatment in an experimental MRSA sepsis.

Methods

Experimental sepsis was performed in mice by intraperitoneal injection of MRSA isolate. Inoculum dose was estimated as 6 × 10⁹/ml. Mice were randomised for the study into four group; control group (not receive any therapy), G-CSF group (1000 ng/daily, subcutaneously for 3 d), antibiotic group (vancomycin 25 or 50 mg/kg intraperitoneally every 12 hours for 7 d), and vancomycin+G-CSF group (at the same concentrations and duration). Autopsy was done within one hour after mice died. If mice was still alive at the end of seventh day, they were sacrificed, and autopsy was done. In all groups, the effect of G-CSF therapy on the survival, the number of the MRSA colonies in the lung, liver, heart, spleen, and peritoneal cultures, the histopathology of the lung, liver, heart and spleen was investigated.

Results

One hundred and six mice were used. There were no significant differences in survival rates and bacterial eradication in G-CSF group compared with control group, and also in antibiotic +G-CSF group compared with antibiotic alone group. These parameters were all significantly different in antibiotic alone group compared with control group. Histopathologically, inflammation of the lung and liver were significantly reduced in vancomycin (25 mg/kg)+G-CSF and vancomycin (50 mg/kg)+G-CSF subgroups, respectively (p < 0.01). The histopathological inflammation of the other organs was not significantly different in antibiotic+G-CSF group compared with antibiotic group and, also G-CSF group compared with control group.

Conclusion

G-CSF treatment had no additional effect on survival and bacterial eradication in MRSA sepsis in nonneutropenic mice; and only a little effect on histopathology. G-CSF treatment is very expensive, likewise glycopeptides. The more interest in infection control measures, and prevent the spread of MRSA infections is more rational.

Increased arteriovenous carboxyhemoglobin differences in patients with inflammatory pulmonary diseases

PURPOSE

Exhaled carbon monoxide and arterial blood carboxyhemoglobin concentrations increase in inflammatory pulmonary diseases. The present study was undertaken to elucidate whether arteriovenous carboxyhemoglobin (a-vHb-CO) concentration differences are also useful to define the site of inflammation, either in the lung or organs other than the lung.

MATERIALS AND METHODS

We examined concentrations of carboxyhemoglobin in both arterial and peripheral venous blood and exhaled carbon monoxide in patients with acute pulmonary inflammation including bronchial asthma (n = 18) and pneumonia (n = 33), and those in patients with extrapulmonary inflammatory diseases, including acute pyelonephritis (n = 28) and active rheumatoid arthritis (n = 16).

RESULTS

The values of carboxyhemoglobin in both arterial and peripheral venous blood were significantly higher in patients with pulmonary and extrapulmonary inflammation compared with those in control subjects (n = 22). Furthermore, a-vHb-CO differences in patients with inflammatory pulmonary diseases were higher than those in patients with acute pyelonephritis and patients with rheumatoid arthritis, and than those in control subjects. The a-vHb-CO differences correlated with the WBC count of peripheral venous blood in patients with pneumonia. In patients with bronchial asthma, the a-vHb-CO differences inversely correlated with FEV(1), although they did not correlate with WBC count of peripheral venous blood. The a-vHb-CO differences in patients with acute pyelonephritis were higher than those in patients with active rheumatoid arthritis.

CONCLUSION

The present study suggests that a-vHb-CO differences may be a useful means to define the site of inflammation, either in the lung or organs other than the lung, in patients with a fever of unknown origin. The large a-vHb-CO differences may be caused by carbon monoxide production in pulmonary inflammation.

Is there a place for granulocyte colony-stimulating factor in non-neutropenic critically ill patients?

Immunoparalysis, characterised by impairments in neutrophil and monocyte/macrophage function, is common in critically ill patients. The theoretical ability of granulocyte colony-stimulating factor (G-CSF) to improve the functions of both neutrophils and monocytes/macrophages provides a rationale for G-CSF therapy in non-neutropenic critically ill patients with infection or a high risk of nosocomial infection. The expression of the receptors that mediate G-CSF effects in neutrophils and monocytes/macrophages is regulated by bacterial products, cytokines and endogenous G-CSF levels, accounting for the variables effects of G-CSF on the neutrophil functions of critically ill patients. This variability should be taken into account when designing studies on the use of G-CSF in ICU-patients. Studies are still needed to identify the subset of patients who may benefit from G-CSF therapy.

Experimental models of pulmonary infection

Experimental models of pulmonary infection are being discussed, focused on various aspects of good experimental design, such as choice of animal species and infecting strain, and route of infection/inoculation techniques (intranasal inoculation, aerosol inoculation, and direct instillation into the lower respiratory tract). In addition, parameters to monitor pulmonary infection are being reviewed such as general clinical signs, pulmonary-associated signs, complication of the pulmonary infection, mortality rate, and parameters after dissection of animals. Examples of pulmonary infection models caused by bacteria, fungi, viruses or parasites in experimental animals with intact or impaired host defense mechanisms are shortly summarized including key-references.

Effect of interleukin-8 and granulocyte colony-stimulating factor on priming and activation of bovine neutrophils

Neutrophils are important effector cells in innate and acquired immunity, but the magnitude and character of their phagocytic and bactericidal responses depend on cues derived from mediators in the local microenvironment. This study investigated the effect of bovine interleukin-8 (IL-8) and granulocyte colony-stimulating factor (G-CSF) on priming and activation of bovine neutrophils in vitro and in vivo. Neutrophils were isolated from blood and cultured for up to 18 h, with or without cytokines, and then Mannheimia haemolytica-induced oxidative burst and phagocytosis of Staphylococcus aureus were measured by flow cytometry. Neither IL-8 nor G-CSF directly triggered an oxidative burst, but incubation with these cytokines for 18 h primed neutrophils for a greater oxidative burst triggered by M. haemolytica and for enhanced uptake of S. aureus. The maximal response was observed when neutrophils were incubated with both cytokines together, at concentrations of 200 ng/ml for G-CSF and 400 ng/ml for IL-8. The IL-8-induced priming effect was reduced by treatment with a neutralizing antibody to IL-8, and was not attributed to endotoxin contamination. Instillation of IL-8 into the lung using a bronchoscope induced neutrophil recruitment within 18 h. Neutrophils from IL-8-treated lung showed dose-dependent enhancement of the oxidative burst triggered by M. haemolytica. Histologically, neutrophils filled alveoli and bronchioles, and scattered macrophages contained neutrophils with morphological features of apoptosis. Thus, prolonged in vitro or in vivo exposure to IL-8 and/or G-CSF enhances the subsequent oxidative burst and phagocytic responses of bovine neutrophils.

Bactericidal activity response of blood neutrophils from critically ill patients to in vitro granulocyte colony-stimulating factor stimulation

OBJECTIVE

Neutrophil function impairment is common in nonneutropenic critically ill patients. Whether granulocyte colony-stimulating factor (G-CSF) may be useful for preventing nosocomial infection in these patients is debated. The response of blood neutrophils from critically ill patients to G-CSF was investigated in vitro.

DESIGN AND SETTING

Prospective study, laboratory investigation in two intensive care units.

PATIENTS

52 critically ill patients without immunosuppression.

MEASUREMENTS

Neutrophils obtained from 52 patients on the 5th day of their intensive care unit stay were incubated with and without G-CSF (1, 10, 100 ng/ml). Reactive oxygen species (ROS) release and bactericidal activity against Staphylococcus aureus and Pseudomonas aeruginosa were evaluated. Plasma cytokines (interleukin 10, tumor necrosis factor alpha, and G-CSF) were measured.

RESULTS

Median values (25th-75th percentiles) indicated no stimulatory effect of G-CSF on neutrophil bactericidal activity against either organism: S. aureus, 100% (95-109) of the unstimulated condition with 1 ng/ml G-CSF, and P. aeruginosa, 102% (98-109) with 1 ng/ml G-CSF. However, wide interindividual variability was found, ranging from marked inhibition to marked stimulation. Similar variability was found for ROS release. No correlations were found between ROS release and bactericidal activities against either bacterial strain. Inhibition of neutrophil bactericidal activity by G-CSF was associated with significantly higher plasma interleukin 10 concentrations. Plasma G-CSF levels were significantly higher in patients whose neutrophil bactericidal activity was unresponsive to G-CSF, suggesting G-CSF receptor downregulation.

CONCLUSIONS

The effect of G-CSF on in vitro neutrophil bactericidal activity varied widely, depending on endogenous levels of G-CSF and was not predictable based on severity scores.

Exacerbation with granulocyte colony-stimulating factor of prior acute lung injury during neutropenia recovery in rats

OBJECTIVE

Neutropenia recovery may be associated with an increased risk of respiratory function deterioration. A history of pneumonia complicating neutropenia has been identified as the leading cause of adult respiratory distress syndrome during neutropenia recovery in patients receiving anticancer chemotherapy, suggesting that neutropenia recovery may worsen prior lung injury.

DESIGN

Controlled animal study.

SETTING

Research laboratory of an academic institution.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

We studied the effect of recovery from cyclophosphamide-induced neutropenia on endotoxin (lipopolysaccharide)- or hydrochloric acid-induced acute lung injury in rats. We also studied the effects of adding granulocyte colony-stimulating factor.

MEASUREMENTS AND MAIN RESULTS

Compared with noncyclophosphamide-treated rats, rats undergoing neutropenia recovery had a higher wet/dry lung weight ratio after hydrochloric acid-induced but not lipopolysaccharide-induced acute lung injury. Granulocyte colony-stimulating factor significantly increased both alveolar cell recruitment (bronchoalveolar lavage fluid counts) and pulmonary edema (wet/dry lung ratio) in both acute lung injury models during neutropenia recovery. Furthermore, in an experiment in hydrochloric acid-instilled rats, exacerbation by granulocyte colony-stimulating factor of hydrochloric acid-induced acute lung injury was inhibited by lidocaine, which prevents adhesion of neutrophils to endothelial cells. Tumor necrosis factor-alpha and interleukin-1 beta concentrations in supernatants of lipopolysaccharide-stimulated alveolar macrophages from rats undergoing neutropenia recovery with granulocyte colony-stimulating factor treatment were significantly increased compared with rats undergoing neutropenia recovery without granulocyte colony-stimulating factor.

CONCLUSION

Neutropenia recovery can worsen acute lung injury, and this effect is exacerbated by granulocyte colony-stimulating factor.

Induction and regulation of endogenous granulocyte colony-stimulating factor formation

Granulocyte colony-stimulating factor (G-CSF) is one of the most prominent endogenous proteins in broad clinical use. While its biological and clinical effects are relatively well studied, little is known about its endogenous formation in health and disease. However, such knowledge is crucial to decide in which situations G-CSF should be applied efficiently in the clinic, ie. when endogenous production does not suffice. The dramatic changes induced by G-CSF in the differential blood cell count are directly immunomodulatory, strengthening the innate defence by multiplying neutrophilic granulocytes. A multitude of further immunomodulatory effects contribute to the regulation of the concerted host defence. In this review, following a short introduction into the biology of G-CSF, the available data on endogenous formation in a number of animal models and human diseases is compiled. The cellular sources and inducers of G-CSF formation are reviewed and the regulation of G-CSF expression on both the transcriptional and translational level are discussed. The emerging understanding of the role and regulation of endogenous G-CSF formation opens up possibilities to define therapeutic windows as well as targets for diagnostics or drug development. Lastly, the modulation of G-CSF formation by various pharmacological agents alerts to putative side effects of these drug treatments.

Exacerbation by granulocyte colony-stimulating factor of prior acute lung injury: implication of neutrophils

OBJECTIVE

Granulocyte colony-stimulating factor is widely prescribed to hasten recovery from cancer chemotherapy-induced neutropenia and has been reported to induce pulmonary toxicity. However, circumstances and mechanisms of this toxicity remain poorly known.

DESIGN

To reproduce a routine situation in cancer patients receiving chemotherapy, we investigated the mechanisms underlying granulocyte colony-stimulating factor-induced exacerbation of alpha-naphthylthiourea-related pulmonary edema.

SETTING

Laboratory research unit.

SUBJECTS

Male specific-pathogen-free Sprague-Dawley rats.

INTERVENTIONS

The effects of granulocyte colony-stimulating factor given alone or after alpha-naphthylthiourea used to induce acute lung injury were investigated.

MEASUREMENTS AND MAIN RESULTS

Lung injury was assessed based on neutrophil sequestration (myeloperoxidase activity in lung tissue) and influx into alveolar spaces (bronchoalveolar lavage fluid cell quantification) and on edema formation (wet/dry lung weight ratio) and alveolar protein concentration into bronchoalveolar lavage fluid. Tumor necrosis factor-alpha and interleukin-1beta were measured in serum, lung homogenates, and isolated alveolar macrophage supernatants. In control rats, granulocyte colony-stimulating factor (25 microg/kg) significantly elevated circulating neutrophil counts without producing alveolar recruitment or pulmonary edema. alpha-Naphthylthiourea significantly increased the wet/dry lung weight ratio (4.68 +/- 0.04 vs. 4.38 +/- 0.07 in controls, p=.04) and induced alveolar protein leakage. Adding granulocyte colony-stimulating factor to alpha-naphthylthiourea exacerbated pulmonary edema, causing neutrophil sequestration in pulmonary vessels, significantly increasing lung myeloperoxidase activity (12.7 +/- 2.0 mOD/min/g vs. 1.1 +/- 0.4 mOD/min/g with alpha-naphthylthiourea alone; p<.0001), and increasing proinflammatory cytokine secretion. alpha-Naphthylthiourea-related pulmonary edema was not exacerbated by granulocyte colony-stimulating factor during cyclophosphamide-induced neutropenia or after lidocaine, which antagonizes neutrophil adhesion to endothelial cells. Tumor necrosis factor-alpha and interleukin-1beta concentrations in alveolar macrophage supernatants and lung homogenates were significantly higher with alpha-naphthylthiourea + granulocyte colony-stimulating factor than with either agent alone, and anti-tumor necrosis factor-alpha antibodies abolished granulocyte colony-stimulating factor-related exacerbation of alpha-naphthylthiourea-induced pulmonary edema. In rats with cyclophosphamide-induced neutropenia, tumor necrosis factor-alpha concentrations in alveolar macrophage supernatants and lung homogenates were significantly decreased compared with rats without neutropenia.

CONCLUSION

Granulocyte colony-stimulating factor-related pulmonary toxicity may involve migration of neutrophils to vascular spaces, adhesion of neutrophils to previously injured endothelial cells, and potentiation of proinflammatory cytokine expression.

Increased blood carboxyhaemoglobin concentrations in inflammatory pulmonary diseases

BACKGROUND

Exhaled carbon monoxide has been reported to increase in inflammatory pulmonary diseases and to be correlated with blood carboxyhaemoglobin (Hb-CO) concentration. A study was undertaken to determine whether arterial blood Hb-CO increases in patients with inflammatory pulmonary diseases.

METHODS

The Hb-CO concentration in arterial blood was measured with a spectrophotometer in 34 normal control subjects, 24 patients with bronchial asthma, 52 patients with pneumonia, and 21 patients with idiopathic pulmonary fibrosis (IPF).

RESULTS

The mean (SE) Hb-CO concentrations in patients with bronchial asthma during exacerbations (n=24, 1.05 (0.05)%), with pneumonia at the onset of illness (n=52, 1.08 (0.06)%), and with IPF (n=21, 1.03 (0.09)%) were significantly higher than those in control subjects (n=34, 0.60 (0.07)%) (mean difference 0.45% (95% confidence interval (CI) 0.23 to 0.67), p<0.01 in patients with bronchial asthma, mean difference 0.48% (95% CI 0.35 to 0.60), p<0.0001 in patients with pneumonia, and mean difference 0.43% (95% CI 0.26 to 0.61) p<0.001 in patients with IPF). In 20 patients with bronchial asthma the Hb-CO concentration decreased after 3 weeks of treatment with oral glucocorticoids (p<0.001). In 20 patients with pneumonia the Hb-CO concentration had decreased after 3 weeks when patients showed evidence of clinical improvement (p<0.001). The values of C-reactive protein (CRP), an acute phase protein, correlated with Hb-CO concentrations in patients with pneumonia (r=0.74, p<0.0001) and in those with IPF (r=0.46, p<0.01). In patients with bronchial asthma changes in Hb-CO concentrations were significantly correlated with those in forced expiratory volume in 1 second (FEV(1)) after 3 weeks (r=0.67, p<0.01). Exhaled carbon monoxide (CO) concentrations were correlated with Hb-CO concentrations (n=33, r=0.80, p<0.0001).

CONCLUSIONS

Hb-CO concentrations are increased in inflammatory pulmonary diseases including bronchial asthma, pneumonia, and IPF. Measurement of arterial Hb-CO may be a useful means of monitoring pulmonary inflammation.

Cytokine modulation in sepsis and septic shock

Sepsis and septic shock are a major cause of morbidity and mortality in patients admitted to the intensive care unit. Since the introduction of antibiotic therapy, the mortality associated with sepsis has remained within the 30- 50% range. Sepsis constitutes the systemic response to infection. This response encompasses both pro-inflammatory and anti-inflammatory phases that are marked by the sequential generation of pro- and anti-inflammatory cytokines. Among the most important pro-inflammatory cytokines are TNF-alpha and IL-1beta. The pro-inflammatory effects of such cytokines are inhibited by soluble receptors/receptor antagonists and anti-inflammatory cytokines including IL-10 and transforming growth factor-beta. Modulation of the activity of both pro- and anti-inflammatory cytokines to improve outcome in patients with sepsis has been subject of multiple clinical studies. This review will examine clinical trials evaluating several strategies for blocking or attenuating TNF-alpha and IL-1beta activity. This review will also survey the current state of experimental therapies involving IL-10, transforming growth factor-beta, granulocyte colony-stimulating factor and IFN-phi. Finally, newer developments related to less known cytokines such as macrophage migration inhibitory factor and high mobility group 1 protein will be evaluated.

Acute G-CSF therapy is not protective during lethal E. coli sepsis

We investigated whether decreases in circulating polymorphonuclear neutrophils (PMN) during lethal Escherichia coli (E. coli) sepsis in canines are related to insufficient host granulocyte colony-stimulating factor (G-CSF). Two-year-old purpose-bred beagles had intraperitoneal E. coli-infected or -noninfected fibrin clots surgically placed. By 10 to 12 h following clot, both infected survivors and nonsurvivors had marked increases (P = 0.001) in serum G-CSF levels (mean peak G-CSF ng/ml +/- SE, 1,931 +/- 364 and 2,779 +/- 681, respectively) compared with noninfected controls (134 +/- 79), which decreased at 24 to 48 h. Despite increases in G-CSF, infected clot placement caused delayed (P = 0.06) increases in PMN (mean +/- SE change from baseline in cells x 10(3)/mm(3) at 24 and 48 h) in survivors (+3.9 +/- 3.9 and +13.8 +/- 3.6) compared with noninfected controls (+13.1 +/- 2.8 and +9.1 +/- 2.5). Furthermore, infected nonsurvivors had decreases in PMN (-1.4 +/- 1.0 and -1.1 +/- 2.3, P = 0.006 compared with the other groups). We next investigated whether administration of G-CSF immediately after clot placement and continued for 96 h to produce more rapid and prolonged high levels of G-CSF after infection would alter PMN levels. Although G-CSF caused large increases in PMN compared with control protein from 2 to 48 h following clot in noninfected controls, it caused much smaller increases in infected survivors and decreases in infected nonsurvivors (P = 0.03 for the ordered effect of G-CSF comparing the three groups). Thus insufficient host G-CSF is unlikely the cause of decreased circulating PMN in this canine model of sepsis. Other factors associated with sepsis either alone or in combination with G-CSF itself may reduce increases or cause decreases in circulating PMN.

Anti-tumor necrosis factor therapy in sepsis: update on clinical trials and lessons learned

OBJECTIVE

Tumor necrosis factor (TNF) is an important mediator involved in the pathogenesis of sepsis. We review clinical studies investigating the efficacy of anti-TNF therapy in decreasing mortality rates in septic patients.

DATA SOURCES

We conducted a computerized bibliographic search of randomized, clinical, multicenter trials studying the effects of anti-TNF therapy in the treatment of sepsis. We included all primary studies, reviewed all published meta-analyses, and contacted primary investigators of multicenter trials where necessary.

DATA SYNTHESIS

Almost all randomized studies targeting TNF during sepsis show a small, albeit nonsignificant, benefit in decreasing mortality. Strategies using monoclonal antibodies are more effective than are strategies using TNF receptor proteins. Analysis of randomized multicenter trials shows a small but significant benefit with anti-TNF therapeutic strategies. Furthermore, a recent study in 2634 septic patients using a murine anti-TNF antibody shows a 3.6% significant benefit in reducing mortality.

CONCLUSIONS

Anti-TNF strategies are only partially effective in patients with sepsis. Although individual studies show small, nonsignificant benefits, analysis of all trial data as well as data from a recent trial in a large population of septic patients show that anti-TNF strategies may confer a small survival benefit. Better characterization of patients and a more multimodal approach by concomitantly targeting other mediators involved in sepsis may be helpful in enlarging the clinical benefit of anti-TNF therapy.

Granulocyte-macrophage colony-stimulating factor amplifies lipopolysaccharide-induced bronchoconstriction by a neutrophil- and cyclooxygenase 2-dependent mechanism

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is used to ameliorate neutropenia in patients after antineoplastic treatment. It has also been suggested as an adjunct treatment in septic patients; however, the recruitment and priming of leukocytes by GM-CSF bears the hazard of a hyperinflammatory response. In particular, the role of GM-CSF in pulmonary functions in septic lungs is still unclear. Therefore, we pretreated rats in vivo with GM-CSF (50 microg/kg, intravenous) and assessed the pulmonary functions of their subsequently prepared isolated perfused lungs when exposed to subtoxic concentrations of lipopolysaccharide (LPS, 2 microg/ml). These lungs showed enhanced expression of cyclooxygenase 2 (COX-2), a significant increase in thromboxane (TX) and tumor necrosis factor (TNF) release into the venous perfusate, and bronchoconstriction. COX-2 inhibition or blocking of the TX receptor abolished the GM-CSF/LPS-induced bronchoconstriction, but not the TNF release. Neutralizing antibodies against TNF did not prevent GM-CSF/LPS-induced bronchoconstriction. After GM-CSF pretreatment, massive neutrophil invasion into the lung occurred. Neutropenic rats were protected against GM-CSF/ LPS-induced lung injury. Similar results were obtained in rats pretreated with G-CSF instead of GM-CSF. We conclude that GM-CSF pretreatment exacerbates pulmonary injury by low-dose LPS via COX-2 expression, TX release, and bronchoconstriction by initiating neutrophil invasion and activation.

Nosocomial or Healthcare Facility-Related Pneumonia in Adults

Nosocomial or hospital-acquired pneumonia (HAP) is a dynamic disease with multiple etiologic agents and a changing natural history. The emergence and spread of multidrug-resistant bacterial pathogens is a current concern. Because of the parallels between HAP and pneumonia occurring in patients in subacute or chronic care facilities, we suggest the use of a more inclusive term for these patients: healthcare facility-related pneumonia. This article focuses on current controversies in the pathogenesis, diagnosis, management, and prevention of bacterial HAP in adults. We endorse early, appropriate antibiotic therapy based on disease severity and the use of strategies to prevent infection, improve patient outcome, and reduce hospital costs.