Granulocyte-macrophage colony-stimulating factor induces activation and restores respiratory burst activity in monocytes from septic patients

Combination of GM CSF and carbapenem is superior to carbapenem monotherapy in difficult-to-treat spontaneous bacterial peritonitis: A randomized controlled trial

BACKGROUND

Patients with cirrhosis and treatment non-responsive spontaneous bacterial peritonitis (SBP) have high mortality. We aimed to investigate whether GM-CSF can improve SBP response rates.

PATIENTS AND METHODS

In this open-label RCT, 131 cirrhosis patients with difficult-to-treat SBP (DTT SBP) were randomized to receive meropenem alone (1 g IV thrice daily for 5 days) (MERO Group, n = 66) or in combination with GM-CSF (1.5 mcg/Kg daily IV till resolution or till 5d) (MEROGM Group, n = 65). The primary end-point was SBP early-response (reduction in absolute neutrophil count (ANC) by >25% after 48 h). Secondary end-points included SBP resolution at day 5.

RESULTS

Patients in MEROGM group in comparison to MERO group had higher SBP early-response (60% vs. 31.8%; p = .001) and SBP resolution rates (55.4% vs. 24.2%; p = .0003). Patients in the combination arm also had better resolution of pneumonia {8/17 (47.05%) vs. 2/19 (10.5%), p = .02} and lower incidence of new-onset AKI (15.4% vs. 31.8%, p = .02), HE (18.5% vs. 34.8%, p = .04) and infections (21.5% vs. 37.9%, p = .05). In comparison to MERO group, 7-day survival was higher in MEROGM group (89.2% vs. 78.7%, p = .03), though the 28-day survival was comparable (78.4% vs. 71.2%; p = .66). None of the patients developed treatment-related severe adverse effects requiring discontinuation of therapy.

CONCLUSIONS

The addition of GM-CSF to meropenem significantly improves response rates in DTT SBP patients within 48 h. Early use of GMCSF modulates host immune response, and enhances antibiotic response with higher SBP resolution. The use of GMCSF needs to be considered in combating difficult SBP in cirrhosis patients.

Immunosenescence: A Critical Factor Associated With Organ Injury After Sepsis

Progressive immune dysfunction associated with aging is known as immunosenescence. The age-related deterioration of immune function is accompanied by chronic inflammation and microenvironment changes. Immunosenescence can affect both innate and acquired immunity. Sepsis is a systemic inflammatory response that affects parenchymal organs, such as the respiratory system, cardiovascular system, liver, urinary system, and central nervous system, according to the sequential organ failure assessment (SOFA). The initial immune response is characterized by an excess release of inflammatory factors, followed by persistent immune paralysis. Moreover, immunosenescence was found to complement the severity of the immune disorder following sepsis. Furthermore, the immune characteristics associated with sepsis include lymphocytopenia, thymus degeneration, and immunosuppressive cell proliferation, which are very similar to the characteristics of immunosenescence. Therefore, an in-depth understanding of immunosenescence after sepsis and its subsequent effects on the organs may contribute to the development of promising therapeutic strategies. This paper focuses on the characteristics of immunosenescence after sepsis and rigorously analyzes the possible underlying mechanism of action. Based on several recent studies, we summarized the relationship between immunosenescence and sepsis-related organs. We believe that the association between immunosenescence and parenchymal organs might be able to explain the delayed consequences associated with sepsis.

Namilumab or infliximab compared with standard of care in hospitalised patients with COVID-19 (CATALYST): a randomised, multicentre, multi-arm, multistage, open-label, adaptive, phase 2, proof-of-concept trial

BACKGROUND

Dysregulated inflammation is associated with poor outcomes in COVID-19. We aimed to assess the efficacy of namilumab (a granulocyte-macrophage colony stimulating factor inhibitor) and infliximab (a tumour necrosis factor inhibitor) in hospitalised patients with COVID-19, to prioritise agents for phase 3 trials.

METHODS

In this randomised, multicentre, multi-arm, multistage, parallel-group, open-label, adaptive, phase 2, proof-of-concept trial (CATALYST), we recruited patients (aged ≥16 years) admitted to hospital with COVID-19 pneumonia and C-reactive protein (CRP) concentrations of 40 mg/L or greater, at nine hospitals in the UK. Participants were randomly assigned with equal probability to usual care or usual care plus a single intravenous dose of namilumab (150 mg) or infliximab (5 mg/kg). Randomisation was stratified by care location within the hospital (ward vs intensive care unit [ICU]). Patients and investigators were not masked to treatment allocation. The primary endpoint was improvement in inflammation, measured by CRP concentration over time, analysed using Bayesian multilevel models. This trial is now complete and is registered with ISRCTN, 40580903.

FINDINGS

Between June 15, 2020, and Feb 18, 2021, we screened 299 patients and 146 were enrolled and randomly assigned to usual care (n=54), namilumab (n=57), or infliximab (n=35). For the primary outcome, 45 patients in the usual care group were compared with 52 in the namilumab group, and 29 in the usual care group were compared with 28 in the infliximab group. The probabilities that the interventions were superior to usual care alone in reducing CRP concentration over time were 97% for namilumab and 15% for infliximab; the point estimates for treatment-time interactions were -0·09 (95% CI -0·19 to 0·00) for namilumab and 0·06 (-0·05 to 0·17) for infliximab. 134 adverse events occurred in 30 (55%) of 55 patients in the namilumab group compared with 145 in 29 (54%) of 54 in the usual care group. 102 adverse events occurred in 20 (69%) of 29 patients in the infliximab group compared with 112 in 17 (50%) of 34 in the usual care group. Death occurred in six (11%) patients in the namilumab group compared with ten (19%) in the usual care group, and in four (14%) in the infliximab group compared with five (15%) in the usual care group.

INTERPRETATION

Namilumab, but not infliximab, showed proof-of-concept evidence for reduction in inflammation-as measured by CRP concentration-in hospitalised patients with COVID-19 pneumonia. Namilumab should be prioritised for further investigation in COVID-19.

FUNDING

Medical Research Council.

Malaria Pigment Hemozoin Impairs GM-CSF Receptor Expression and Function by 4-Hydroxynonenal

Malarial pigment hemozoin (HZ) generates the lipoperoxidation product 4-hydroxynonenal (4-HNE), which is known to cause dysregulation of the immune response in malaria. The inhibition of granulocyte macrophage colony-stimulating factor (GM-CSF)-dependent differentiation of dendritic cells (DC) by HZ and 4-HNE was previously described in vitro, and the GM-CSF receptor (GM-CSF R) was hypothesised to be a primary target of 4-HNE in monocytes. In this study, we show the functional impact of HZ on GM-CSF R in monocytes and monocyte-derived DC by (i) impairing GM-CSF binding by 50 ± 9% and 65 ± 14%, respectively (n = 3 for both cell types); (ii) decreasing the expression of GM-CSF R functional subunit (CD116) on monocyte’s surface by 36 ± 11% (n = 6) and in cell lysate by 58 ± 16% (n = 3); and (iii) binding of 4-HNE to distinct amino acid residues on CD116. The data suggest that defective DC differentiation in malaria is caused by GM-CSF R dysregulation and GM-CSF R modification by lipoperoxidation product 4-HNE via direct interaction with its CD116 subunit.

The SARS-CoV-2/Receptor Axis in Heart and Blood Vessels: A Crisp Update on COVID-19 Disease with Cardiovascular Complications

The SARS-CoV-2 virus causing COVID-19 disease has emerged expeditiously in the world and has been declared pandemic since March 2020, by World Health Organization (WHO). The destructive effects of SARS-CoV-2 infection are increased among the patients with pre-existing chronic conditions and, in particular, this review focuses on patients with underlying cardiovascular complications. The expression pattern and potential functions of SARS-CoV-2 binding receptors and the attributes of SARS-CoV-2 virus tropism in a physio-pathological state of heart and blood vessel are precisely described. Of note, the atheroprotective role of ACE2 receptors is reviewed. A detailed description of the possible detrimental role of SARS-CoV-2 infection in terms of vascular leakage, including endothelial glycocalyx dysfunction and bradykinin 1 receptor stimulation is concisely stated. Furthermore, the potential molecular mechanisms underlying SARS-CoV-2 induced clot formation in association with host defense components, including activation of FXIIa, complements and platelets, endothelial dysfunction, immune cell responses with cytokine-mediated action are well elaborated. Moreover, a brief clinical update on patient with COVID-19 disease with underlying cardiovascular complications and those who had new onset of cardiovascular complications post-COVID-19 disease was also discussed. Taken together, this review provides an overview of the mechanistic aspects of SARS-CoV-2 induced devastating effects, in vital organs such as the heart and vessels.

Urothelial Carcinoma of the Bladder Induces Endothelial Cell Activation and Hypercoagulation

Cancer-related venous thromboembolisms (VTE) are associated with metastasis and reduced survival in patients with urothelial cancer of the bladder. Although previous reports suggest the contribution of tissue factor and podoplanin, the mechanistic linkage between VTE and bladder cancer cell-derived molecules is unknown. Therefore, we compared distinct procoagulant pathways in four different cell lines. In vitro findings were further confirmed by microfluidic experiments mimicking the pathophysiology of tumor blood vessels and in tissue samples of patients with bladder cancer by transcriptome analysis and immunohistology. In vitro and microfluidic experiments identified bladder cancer-derived VEGF-A as highly procoagulant because it promoted the release of von Willebrand factor (VWF) from endothelial cells and thus platelet aggregation. In tissue sections from patients with bladder cancer, we found that VWF-mediated blood vessel occlusions were associated with a poor outcome. Transcriptome data further indicate that elevated expression levels of enzymes modulating VEGF-A availability were significantly connected to a decreased survival in patients with bladder cancer. In comparison with previously postulated molecular players, we identified tumor cell-derived VEGF-A and endothelial VWF as procoagulant mediators in bladder cancer. Therapeutic strategies that prevent the VEGF-A-mediated release of VWF may reduce tumor-associated hypercoagulation and metastasis in patients with bladder cancer. IMPLICATIONS: We identified the VEGF-A-mediated release of VWF from endothelial cells to be associated with bladder cancer progression.

Is There a Role for Hematopoietic Growth Factors During Sepsis?

Sepsis is a complex syndrome characterized by simultaneous activation of pro- and anti-inflammatory processes. After an inflammatory phase, patients present signs of immunosuppression and possibly persistent inflammation. Hematopoietic growth factors (HGFs) are glycoproteins that cause immune cells to mature and/or proliferate. HGFs also have a profound effect on cell functions and behavior. HGFs play crucial role in sepsis pathophysiology and were tested in several clinical trials without success to date. This review summarizes the role played by HGFs during sepsis and their potential therapeutic role in the Management of sepsis-related immune disturbances.

The Effects of Ex Vivo Administration of Granulocyte-Macrophage Colony-Stimulating Factor and Endotoxin on Cytokine Release of Whole Blood Are Determined by Priming Conditions

Background

Lipopolysaccharide- (LPS-) induced tumour necrosis factor alpha (TNFα) secretion in critically ill patients can be considered as a measure of immune responsiveness. It can be enhanced by granulocyte-macrophage colony stimulating factor (GM-CSF). We investigated the effect of GM-CSF on ex vivo stimulated cytokine production using various preincubation regimens in healthy donors and patients with sepsis.

Results

The maxima for the stimuli occurred 3 hours after stimulation. In donors, there was an increase (p < 0.001) of LPS-induced TNFα levels following incubation with GM-CSF. The simultaneous incubation with GM-CSF and LPS caused an inhibition of TNFα production (p < 0.001). Postincubation with GM-CSF did not yield any difference. In patients, preincubation with GM-CSF yielded an enhanced ex vivo TNFα-response when TNFα levels were low. Patients with increased TNFα concentrations did not show a GM-CSF stimulation effect. The GM-CSF preincubation yielded an increase of IL-8 production in patients and donors.

Conclusions

This study demonstrates the immune-modulating properties of GM-CSF depending on the absence or presence of LPS or systemic TNFα. The timing of GM-CSF administration may be relevant for the modulation of the immune system in sepsis. The lack of stimulation in patients with high TNFα may represent endotoxin tolerance.

Phenotyping the Immune Response to Trauma: A Multiparametric Systems Immunology Approach

OBJECTIVE

Trauma induces a complex immune response that requires a systems biology research approach. Here, we used a novel technology, mass cytometry by time-of-flight, to comprehensively characterize the multicellular response to trauma.

DESIGN

Peripheral blood mononuclear cells samples were stained with a 38-marker immunophenotyping cytometry by time-of-flight panel. Separately, matched peripheral blood mononuclear cells were stimulated in vitro with heat-killed Streptococcus pneumoniae or CD3/CD28 antibodies and stained with a 38-marker cytokine panel. Monocytes were studied for phagocytosis and oxidative burst.

SETTING

Single-institution level 1 trauma center.

PATIENTS OR SUBJECTS

Trauma patients with injury severity scores greater than 20 (n = 10) at days 1, 3, and 5 after injury, and age- and gender-matched controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Trauma-induced expansion of Th17-type CD4 T cells was seen with increased expression of interleukin-17 and interleukin-22 by day 5 after injury. Natural killer cells showed reduced T-bet expression at day 1 with an associated decrease in tumor necrosis factor-β, interferon-γ, and monocyte chemoattractant protein-1. Monocytes showed robust expansion following trauma but displayed decreased stimulated proinflammatory cytokine production and significantly reduced human leukocyte antigen - antigen D related expression. Further analysis of trauma-induced monocytes indicated that phagocytosis was no different from controls. However, monocyte oxidative burst after stimulation increased significantly after injury.

CONCLUSIONS

Using cytometry by time-of-flight, we were able to identify several major time-dependent phenotypic changes in blood immune cell subsets that occur following trauma, including induction of Th17-type CD4 T cells, reduced T-bet expression by natural killer cells, and expansion of blood monocytes with less proinflammatory cytokine response to bacterial stimulation and less human leukocyte antigen - antigen D related. We hypothesized that monocyte function might be suppressed after injury. However, monocyte phagocytosis was normal and oxidative burst was augmented, suggesting that their innate antimicrobial functions were preserved. Future studies will better characterize the cell subsets identified as being significantly altered by trauma using cytometry by time-of-flight, RNAseq technology, and functional studies.

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

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

Monocyte/macrophage inflammatory response pathways to combat Francisella infection: possible therapeutic targets?

Francisella tularensis can bypass and suppress host immune responses, even to the point of manipulating immune cell phenotypes and intercellular inflammatory networks. Strengthening these responses such that immune cells more readily identify and destroy the bacteria is likely to become a viable (and perhaps necessary) strategy for combating infections with Francisella, especially given the likelihood of antibiotic resistance in the foreseeable future. Monocytes and macrophages offer a niche wherein Francisella can invade and replicate, resulting in substantially higher bacterial load that can overcome the host. As such, understanding their responses to Francisella may uncover potential avenues of therapy that could promote a lowering of bacterial burden and clearance of infection. These response pathways include Toll-like Receptor 2 (TLR2), the caspase-1 inflammasome, Interferons, NADPH oxidase, Phosphatidylinositide 3-kinase (PI3K), and the Ras pathway. In this review we summarize the literature pertaining to the roles of these pathways during Francisella infection, with an emphasis on monocyte/macrophage responses. The therapeutic targeting of one or more such pathways may ultimately become a valuable tool for the treatment of tularemia, and several possibilities are discussed.

Innate Immune Responses in Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is a common complication of mechanical ventilation, resulting in substantial morbidity, mortality, and health care cost. Early upper airway colonization by pathogenic bacteria and microaspiration are the primary pathogenic events leading to VAP. Patients at risk for VAP have defects in structural/mechanical defenses of the respiratory tract. In addition, critical illness, including sepsis, trauma, and postoperative states, is associated with profound defects in both innate and acquired antibacterial immunity, influencing antimicrobial effector functions of both leukocytes and structural/parenchymal cells. Factors present within the lung microenvironment, including alveolar stretch, cyclical atelectasis, changes in oxygen tension, and respiratory tract microbiota, substantially impact antibacterial host responses. Mechanisms accounting for dysregulated immune homeostasis are incompletely understood, but likely involve: (1) alterations in the balance of pro- and anti-inflammatory cytokines; (2) changes in pathogen recognition receptor and G-protein coupled receptor expression and downstream signaling cascades; and (3) dysregulated cell death responses. Antibiotics and preventive strategies are the mainstay of therapy in patients with VAP. However, novel approaches are needed to reverse immunological reprogramming that occurs during critical illness and/or mechanical ventilation, and to identify patients who are most likely to benefit from immunomodulatory therapy.

Colony-stimulating factors in the prevention and management of infectious diseases

Colony-stimulating factors (CSFs) are attractive adjunctive anti-infective therapies. Used to enhance innate host defenses against microbial pathogens, the myeloid CSFs increase absolute numbers of circulating innate immune effector cells by accelerating bone marrow production and maturation, or augment the function of those cells through diverse effects on chemotaxis, phagocytosis, and microbicidal functions. This article summarizes the evidence supporting the accepted clinical uses of the myeloid CSFs in patients with congenital or chemotherapy-induced neutropenia, and presents an overview of proposed and emerging uses of the CSFs for the prevention and treatment of infectious diseases in other immunosuppressed and immunocompetent patient populations.

Sepsis biomarkers: a review

INTRODUCTION

Biomarkers can be useful for identifying or ruling out sepsis, identifying patients who may benefit from specific therapies or assessing the response to therapy.

METHODS

We used an electronic search of the PubMed database using the key words "sepsis" and "biomarker" to identify clinical and experimental studies which evaluated a biomarker in sepsis.

RESULTS

The search retrieved 3370 references covering 178 different biomarkers.

CONCLUSIONS

Many biomarkers have been evaluated for use in sepsis. Most of the biomarkers had been tested clinically, primarily as prognostic markers in sepsis; relatively few have been used for diagnosis. None has sufficient specificity or sensitivity to be routinely employed in clinical practice. PCT and CRP have been most widely used, but even these have limited ability to distinguish sepsis from other inflammatory conditions or to predict outcome.

Disruption of the transcription factor Nrf2 promotes pro-oxidative dendritic cells that stimulate Th2-like immunoresponsiveness upon activation by ambient particulate matter

Oxidative stress is important in dendritic cell (DC) activation. Environmental particulate matter (PM) directs pro-oxidant activities that may alter DC function. Nuclear erythroid 2 p45-related factor 2 (Nrf2) is a redox-sensitive transcription factor that regulates expression of antioxidant and detoxification genes. Oxidative stress and defective antioxidant responses may contribute to the exacerbations of asthma. We hypothesized that PM would impart differential responses by Nrf2 wild-type DCs as compared with Nrf2(-/-) DCs. We found that the deletion of Nrf2 affected important constitutive functions of both bone marrow-derived and highly purified myeloid lung DCs such as the secretion of inflammatory cytokines and their ability to take up exogenous Ag. Stimulation of Nrf2(-/-) DCs with PM augmented oxidative stress and cytokine production as compared with resting or Nrf2(+/+) DCs. This was associated with the enhanced induction of Nrf2-regulated antioxidant genes. In contrast to Nrf2(+/+) DCs, coincubation of Nrf2(-/-) DCs with PM and the antioxidant N-acetyl cysteine attenuated PM-induced up-regulation of CD80 and CD86. Our studies indicate a previously underappreciated role of Nrf2 in innate immunity and suggest that deficiency in Nrf2-dependent pathways may be involved in susceptibility to the adverse health effects of air pollution in part by promoting Th2 cytokine responses in the absence of functional Nrf2. Moreover, our studies have uncovered a hierarchal response to oxidative stress in terms of costimulatory molecule expression and cytokine secretion in DCs and suggest an important role of heightened oxidative stress in proallergic Th2-mediated immune responses orchestrated by DCs.

Diversity of interferon gamma and granulocyte-macrophage colony-stimulating factor in restoring immune dysfunction of dendritic cells and macrophages during polymicrobial sepsis

The development of immunosuppression during polymicrobial sepsis is associated with the failure of dendritic cells (DC) to promote the polarization of T helper (Th) cells toward a protective Th1 type. The aim of the study was to test potential immunomodulatory approaches to restore the capacity of splenic DC to secrete interleukin (IL) 12 that represents the key cytokine in Th1 cell polarization. Murine polymicrobial sepsis was induced by cecal ligation and puncture (CLP). Splenic DC were isolated at different time points after CLP or sham operation, and stimulated with bacterial components in the presence or absence of neutralizing anti-IL-10 antibodies, murine interferon (IFN) gamma, and/or granulocyte macrophage colony-stimulating factor (GM-CSF). DC from septic mice showed an impaired capacity to release the pro-inflammatory and Th1-promoting cytokines tumor necrosis factor alpha, IFN-gamma, and IL-12 in response to bacterial stimuli, but secreted IL-10. Endogenous IL-10 was not responsible for the impaired IL-12 secretion. Up to 6 h after CLP, the combined treatment of DC from septic mice with IFN-gamma and GM-CSF increased the secretion of IL-12. Later, DC from septic mice responded to IFN-gamma and GM-CSF with increased expression of the co-stimulatory molecule CD86, while IL-12 secretion was no more enhanced. In contrast, splenic macrophages from septic mice during late sepsis responded to GM-CSF with increased cytokine release. Thus, therapy of sepsis with IFN-gamma/GM-CSF might be sufficient to restore the activity of macrophages, but fails to restore DC function adequate for the development of a protective Th1-like immune response.

Immune response of severely injured patients--influence of surgical intervention and therapeutic impact

BACKGROUND

[corrected] Severe injury leads to a severe deterioration of the patients' immune response. The changes of the immune response after severe injury include a broad range of immune functions and may result in a status of immunosuppression, which could favor infectious complications. Therefore, immunostimulating therapies have been introduced in the therapy for severely injured patients in clinical and experimental settings.

OBJECTIVES

The article summarizes actual immunomodulating approaches in the treatment of trauma patients and therapeutic strategies avoiding additional immune deteriorations.

RESULTS

Examples for an immunostimulating approach in trauma patients are interferon gamma and the granulocyte macrophage-colony-stimulating factor (GM-CSF), which are summarized in this review in detail. However, the effect of such an interference in the patients' immune response with all its different cellular targets is not yet clearly understood, and most studies focus on the reaction of circulating monocytes. In addition, further immunomodulating strategies, including nutritional support, are addressed. However, clinically established therapeutic immunomodulating strategies in trauma care so far do not exist. The impact of the accidental and also an additional surgical trauma on the immune response has been clearly demonstrated. Therefore, the idea of a "damage control orthopedic surgery" (DCOS) is not only necessary to prevent further deterioration of the homeostasis of, e.g., the coagulating system, but is also desirable in terms of minimizing the burden on the immune system. In addition, also the timing of secondary surgical treatment in trauma patient care should include an evaluation of the immune response, although the most reliable markers still need to be identified.

CONCLUSION

Immunomodulating therapies in trauma patients exist on an experimental level with inconsistent results. The general management of trauma patients includes strategies that have been developed also on the basis of immunological considerations.

Respuesta inflamatoria y apoptosis en la lesión pulmonar aguda

One of the principal mechanisms of pulmonary injury in acute respiratory distress is due to the effects of the precipitated inflammatory response. The damage produced to the alveolar epithelium and underlying endothelium depends on the sequestration and activation of inflammatory cells, which in turn exert their actions through mediators. On the other hand, apoptosis is a mechanism responsible for epithelial damage and regulation of inflammation. Response of the lung tissue subjected to mechanical ventilation stimulus is added to the previous mechanisms. All these processes flow into a series of common pathways of cellular activation. Knowledge of these mechanisms could serve to identify which patients would benefit from a specific treatment before applying therapies that act indiscriminately in the inflammatory response.

Neutrophil respiratory burst is decreased in scleroderma and normalized by near-infrared mediated hyperthermia

BACKGROUND

The production of reactive oxygen species (ROS) by fibroblasts has been suggested to contribute to scleroderma pathogenesis. Infrared-mediated hyperthermia has recently been shown to be of benefit in scleroderma.

AIM

As the contribution of neutrophils and monocytes to ROS formation in scleroderma is unknown, we studied respiratory burst in these cell types. We also aimed to test the hypothesis that near-infrared (IRA) treatment may effect burst activity.

METHODS

We determined respiratory burst in patients with scleroderma (n = 22) and age- and sex-matched controls (n = 20) at baseline, and after high-level stimulation by phorbolmyristyl acetate (PMA) and low-level stimulation by non-opsonized zymosan. Respiratory burst was also assessed before and after a series of infrared-mediated hyperthermia treatments.

RESULTS

Unexpectedly, we observed no increase but instead a slight but statistically significant reduction in baseline and zymosan-stimulated respiratory burst in scleroderma neutrophils (P < 0.001) and monocytes (P < 0.005). This decrease in burst activity was nonspecific, as it was also observed in patients with another active inflammatory disease, psoriasis. IRA treatment induced a cell-type-specific normalization of respiratory burst only in neutrophils, but not in monocytes. Intriguingly, neutrophil-specific normalization of ROS formation persisted for 6 weeks after the end of IRA treatment, in concordance with the previously reported clinical responses to this therapy.

CONCLUSION

Neutrophils and monocytes do not exhibit cell-autonomous overproduction of ROS in scleroderma, thereby implicating fibroblasts as main source for clinically relevant ROS accumulation. Furthermore, repeated mild infrared-mediated hyperthermia exerts a lasting cell-type-specific effect on neutrophils.

GM-CSF and the impaired pulmonary innate immune response following hyperoxic stress

We have previously demonstrated that mice exposed to sublethal hyperoxia (an atmosphere of >95% oxygen for 4 days, followed by return to room air) have significantly impaired pulmonary innate immune response. Alveolar macrophages (AM) from hyperoxia-exposed mice exhibit significantly diminished antimicrobial activity and markedly reduced production of inflammatory cytokines in response to stimulation with LPS compared with AM from control mice in normoxia. As a consequence of these defects, mice exposed to sublethal hyperoxia are more susceptible to lethal pneumonia with Klebsiella pneumoniae than control mice. Granulocyte/macrophage colony-stimulating factor (GM-CSF) is a growth factor produced by normal pulmonary alveolar epithelial cells that is critically involved in maintenance of normal AM function. We now report that sublethal hyperoxia in vivo leads to greatly reduced alveolar epithelial cell GM-CSF expression. Systemic treatment of mice with recombinant murine GM-CSF during hyperoxia exposure preserved AM function, as indicated by cell surface Toll-like receptor 4 expression and by inflammatory cytokine secretion following stimulation with LPS ex vivo. Treatment of hyperoxic mice with GM-CSF significantly reduced lung bacterial burden following intratracheal inoculation with K. pneumoniae, returning lung bacterial colony-forming units to the level of normoxic controls. These data point to a critical role for continuous GM-CSF activity in the lung in maintenance of normal AM function and demonstrate that lung injury due to hyperoxic stress results in significant impairment in pulmonary innate immunity through suppression of alveolar epithelial cell GM-CSF expression.

Tissue factor upregulation drives a thrombosis-inflammation circuit in relation to cardiovascular complications

The extrinsic coagulation is recognized as an 'inducible' signalling cascade resulting from tissue factor (TF) upregulation by exposure to clotting zymogen FVII upon inflammation or tissue injury. Following the substantial initiation, an array of proteolytic activation generates mediating signals (active serine proteases: FVIIa, FXa and FIIa) that lead to hypercoagulation with fibrin overproduction manifesting thrombosis. In addition, TF upregulation plays a central role in driving a thrombosis-inflammation circuit. Coagulant mediators (FVIIa, FXa and FIIa) and endproduct (fibrin) are proinflammatory, eliciting tissue necrosis factor, interleukins, adhesion molecules and many other intracellular signals in different cell types. Such resulting inflammation could ensure 'fibrin' thrombosis via feedback upregulation of TF. Alternatively, the resulting inflammation triggers platelet/leukocyte/polymononuclear cell activation thus contributing to 'cellular' thrombosis. TF is very vulnerable to upregulation resulting in hypercoagulability and subsequent thrombosis and inflammation, either of which presents cardiovascular risks. The prevention and intervention of TF hypercoagulability are of importance in cardioprotection. Blockade of inflammation reception and its intracellular signalling prevents TF expression from upregulation. Natural (activated protein C, tissue factor pathway inhibitor, or antithrombin III) or pharmacological anticoagulants readily offset the extrinsic hypercoagulation mainly through FVIIa, FXa or FIIa inhibition. Therefore, anticoagulants turn off the thrombosis-inflammation circuit, offering not only antithrombotic but anti-inflammatory significance in the prevention of cardiovascular complications.

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.

Activation-Induced Depletion of Protein Kinase Cα Provokes Desensitization of Monocytes/Macrophages in Sepsis

Sepsis accounts for the majority of fatal casualties in critically ill patients, because extensive research failed to significantly improve appropriate therapy strategies. Thus, understanding molecular mechanisms initiating the septic phenotype is important. Symptoms of septic disease are often associated with monocyte/macrophage desensitization. In this study, we provide evidence that a desensitized cellular phenotype is characterized by an attenuated oxidative burst. Inhibition of the oxidative burst and depletion of protein kinase C alpha (PKC alpha) were correlated in septic patients. To prove that PKC alpha down-regulation indeed attenuated the oxidative burst, we set up a cell culture model to mimic desensitized monocytes/macrophages. We show that LPS/IFN-gamma-treatment of RAW264.7 and U937 cells lowered PKC alpha expression and went on to confirm these data in primary human monocyte-derived macrophages. To establish a role of PKC alpha in cellular desensitization, we overexpressed PKC alpha in RAW264.7 and U937 cells and tested for phorbolester-elicited superoxide formation following LPS/IFN-gamma-pretreatment. Inhibition of the oxidative burst, i.e., cellular desensitization, was clearly reversed in cells overexpressing PKC alpha, pointing to PKC alpha as the major transmitter in eliciting the oxidative burst in monocytes/macrophages. However, PKC alpha inactivation by transfecting a catalytically inactive PKC alpha mutant attenuated superoxide formation. We suggest that depletion of PKC alpha in monocytes from septic patients contributes to cellular desensitization, giving rise to clinical symptoms of sepsis.

The potential of GM-CSF to improve resistance against infections in organ transplantation

Immunosuppressed patients retain transplants but become more susceptible to opportunistic infections, which is a major complication in organ transplantation. Life-long immunosuppression for such patients could be reduced by creating immune tolerance, although this might be associated with an increased risk for infections and malignancies. An alternative therapeutic concept could consist of boosting the innate immune response against infections while continuing to suppress the adaptive immune response to prevent graft rejection. We propose granulocyte-macrophage colony-stimulating factor (GM-CSF) as a novel candidate to achieve this goal, based on recent studies in which beneficial effects were demonstrated in immunosuppressed mice with skin allografts and in dexamethasone-suppressed blood from healthy volunteers and blood from liver transplant recipients undergoing immunosuppressive therapy. Such data suggest that GM-CSF or other endogenous factors with similar properties should be examined in clinical trials.

Quelles perspectives thérapeutiques dans le syndrome septique ?

OBJECTIVE

To evaluate recent data provided on new treatments of patients with septic shock.

DATA EXTRACTION

A Medline search was performed to identify pertinent literature on the pathophysiology of septic shock and treatment strategies from 1990 to 2003. Keywords were "septic shock", "sepsis", "inflammation" and "management".

DATA SYNTHESIS

Advances were performed in our current understanding of pathophysiology of sepsis. The loss of homeostatic balance among the systemic inflammatory response and the disturbance of coagulation with generalized coagulopathy lead to organ failures and death. The administration of activated protein C (drotrecogin alfa) reducing this coagulopathy can decrease the mortality of septic shock patients. The modulation of inflammation did not make it possible to improve survival of septic shock patients until now. The efficacy of low doses of steroid has been recently shown in septic shock patients. In addition, new data highlighted the interest of an early goal therapy in patients with sepsis who are admitted to emergency.

CONCLUSION

The improvement of survival in septic syndrome patients is a difficult challenge. The uses of different new therapeutic options like protein C reactive, steroids, or early goal therapy in association should make it possible to reduce the mortality in septic patients.

Effect of granulocyte-macrophage colony-stimulating factor on the immune response of circulating monocytes after severe trauma

OBJECTIVE

Severe injury compromises functions of the antigen-presenting immune cells, resulting in an increased vulnerability toward bacterial sepsis. Support of the immune capabilities contributes a desirable therapeutic option in high-risk patients. Factors possessing immunostimulating properties such as granulocyte-macrophage colony-stimulating factor (GM-CSF) may serve as potential tools to compensate immunosuppression caused by severe trauma. In the present study, therefore, GM-CSF was examined with regard to its capacity to overcome trauma-induced down-regulation of immune functions.

DESIGN

Prospective clinical experimental study.

SETTING

University hospital intensive care unit and research facility.

PATIENTS

Severely injured patients with >25 points on the Injury Severity Score.

INTERVENTIONS

Blood samples of severely injured patients were incubated in vitro with 10 ng/mL GM-CSF for 6 hrs.

MEASUREMENTS

Human leukocyte antigen (HLA)-DR expression on monocytes was analyzed by flow cytometry, lipopolysaccharide-induced tumor necrosis factor (TNF)alpha and interleukin-10 production of blood samples was measured by means of enzyme-linked immunoabsorbent assay.

MAIN RESULTS

Compared with blood specimens of healthy donors, ex vivo endotoxin-induced TNF alpha production and HLA-DR expression on monocytes were significantly reduced in blood of trauma patients. Ex vivo treatment of blood specimens with GM-CSF increased HLA-DR expression and TNF alpha production stimulated by lipopolysaccharides in both healthy volunteers and patients on day 1 after trauma. Blood samples of patients with an uneventful recovery showed nearly normal TNF alpha synthesis and HLA-DR expression after 2-3 wks, whereas TNF alpha production and HLA-DR expression of patients with sepsis and multiple organ failure remained at low levels. In the sepsis/multiple organ failure group, GM-CSF also enhanced HLA-DR expression and TNF alpha production, although the levels of the volunteers' blood were not reached.

CONCLUSIONS

The presented data show that trauma- and sepsis-induced depression of monocyte functions can be counteracted by GM-CSF in vitro, suggesting that this substance may serve as support of immune functions in severely injured patients.

GM-CSF restores innate, but not adaptive, immune responses in glucocorticoid-immunosuppressed human blood in vitro

Infection remains the major complication of immunosuppressive therapy in organ transplantation. Therefore, reconstitution of the innate immunity against infections, without activation of the adaptive immune responses, to prevent graft rejection is a clinically desirable status in transplant recipients. We found that GM-CSF restored TNF mRNA and protein expression without inducing IL-2 production and T cell proliferation in glucocorticoid-immunosuppressed blood from either healthy donors or liver transplant patients. Gene array experiments indicated that GM-CSF selectively restored a variety of dexamethasone-suppressed, LPS-inducible genes relevant for innate immunity. A possible explanation for the lack of GM-CSF to restore T cell proliferation is its enhancement of the release of IL-1betaR antagonist, rather than of IL-1beta itself, since exogenously added IL-1beta induced an IL-2-independent Con A-stimulated proliferation of glucocorticoid-immunosuppressed lymphocytes. Finally, to test the in vivo relevance of our findings, we showed that GM-CSF restored the survival of dexamethasone- or cyclosporine A-immunosuppressed mice from an otherwise lethal infection with Salmonella typhimurium. In addition to this increased resistance to infection, GM-CSF did not induce graft rejection of a skin allotransplant in cyclosporine A-immunosuppressed mice. The selective restoration potential of GM-CSF suggests its therapeutic use in improving the resistance against infections upon organ transplantation.

Pregnancy is associated with suppression of the nuclear factor kappaB/IkappaB activation pathway in peripheral blood mononuclear cells

Modulations of maternal immune cell function are critical for successful growth and development of an antigenically distinct fetus. It has been proposed that pregnancy is associated both with suppression of the adaptive immune system and a generalised maternal inflammatory response with changes in immune function resembling those associated with septicemia, and these changes are more exaggerated when pregnancies are complicated with pre-eclampsia. The nuclear factor (NF)-kappaB family of transcription factors play a significant role in immune regulation. We hypothesised therefore that if pregnancy is associated with activation of the maternal immune system, this would be supported by the activation of NF-kappaB and degradation of IkappaBalpha and beta in peripheral blood mononuclear cells (PBMCs). We demonstrate the contrary: NF-kappaB activity is suppressed in PBMCs from pregnant females and more in pre-eclampsia. The inhibition of NF-kappaB activation in pregnancy is not attributed to over-expression of IkappaBalpha or beta. In contrast, levels of IkappaBalpha and beta in cytoplasmic extracts from PBMCs in pregnancy are decreased compared with non-pregnant controls, and IkappaBalpha levels are decreased more so in pre-eclampsia. We have shown that activation of NF-kappaB in PBMCs from patients with septicemia follows the classical pathway. This pathway is differentially regulated in pregnancy. Alterations in NF-kappaB nuclear binding and IkappaBalpha levels were reproducible by culturing PBMCs in pooled pregnant serum. Taken together, these data indicate that pregnancy-specific factors exist to regulate expression of NF-kappaB/IkappaB in a pregnancy-specific manner, and may underlie one mechanism by which the fetus avoids maternal rejection throughout pregnancy.

Extrapulmonary and pulmonary tuberculosis in antananarivo (madagascar): high clustering rate in female patients

Antananarivo, the capital city of Madagascar, has an endemic focus of tuberculosis (TB). We specifically studied patients with extrapulmonary TB (EPTB) and grouped patients according to infected body site. The strains were characterized by IS6110 fingerprinting and compared with those isolated from patients with pulmonary TB (PTB) during the same period in order to determine the possible association between the genotype and the clinical expression of TB. A total of 316 TB patients were included in this study: 151 individuals with EPTB, 10 with both PTB and EPTB, and 155 with PTB alone. Pleural TB was the major EPTB localization (77%) and was found more often in older patients, while PTB or EPTB in which the localization was other than pleural (other EPTB) was found in younger patients. The male-to-female ratio was slightly higher in pleural TB patients (3.06:1) than in patients with other EPTB (1.35:1). There was no significant difference in the BCG status among patients with PTB, pleural TB, and other EPTB. Analysis of IS6110 patterns showed that 167 patients (52.8%) were assigned to 37 clusters of 2 to 34 patients. Analysis of the IS6110 clusters and the IS6110 families did not show any association with a particular clinical expression of the disease. Patients with PTB or other EPTB were more likely to have strains with one IS6110 copy than patients with pleural TB. The clustering rate was found to be significantly higher in female patients (62%) than in male patients (48%) (P = 0.029), suggesting that Malagasy women were more likely to progress to disease after infection than men.

A randomized phase II trial of granulocyte-macrophage colony-stimulating factor therapy in severe sepsis with respiratory dysfunction

Granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulates hemopoiesis and effector functions of granulocytes and macrophages and is involved in pulmonary surfactant homeostasis. We investigated whether GM-CSF therapy improved clinically diagnosed severe sepsis and respiratory dysfunction in critically ill patients. This randomized, double-blind, placebo-controlled phase II study added low-dose (3 mcg/kg) intravenous recombinant human GM-CSF daily for 5 days to conventional therapy in 10 patients, with a further eight patients receiving placebo. GM-CSF-treated patients showed improvement in Pa(O(2))/FI(O(2)) over 5 days (p = 0.02) and increased peripheral blood neutrophils (p = 0.08), whereas alveolar neutrophils decreased (p = 0.02). GM-CSF therapy was not associated with decreased 30-day survival or with increased acute respiratory distress syndrome or extrapulmonary organ dysfunction. GM-CSF therapy was associated with increased blood granulocyte superoxide production and restoration or preservation of blood and alveolar leukocyte phagocytic function. We conclude that low-dose GM-CSF was associated with improved gas exchange without pulmonary neutrophil infiltration, despite functional activation of both circulating neutrophils and pulmonary phagocytes. In addition, GM-CSF therapy was not associated with worsened acute respiratory distress syndrome or the multiple organ dysfunction syndrome, suggesting a homeostatic role for GM-CSF in sepsis-related pulmonary dysfunction.

Sepsis-induced immunosuppression: from bad to worse

The sepsis syndrome is characterized by the acute release of a variety of inflammatory mediators, which often result in detrimental effects to the host. The release of these mediators is regulated and counterbalanced by the coordinated expression of antiinflammatory molecules. It is the balance between the expression of pro- and antiinflammatory mediators that often determines the magnitude of early tissue injury and subsequent risk of infectious complications. As our understanding of the pathophysiology of sepsis continues to evolve, we have gained a greater appreciation for the effects that sepsis and similar states of overwhelming stress have on host antimicrobial immunity. A number of functional defects in leukocytes isolated from sepsis patients have been characterized. These defects include diminished expression of important cell surface antigens, dysregulated cytokine production, alterations in antigen-presenting ability, and accelerated apoptosis. Impaired leukocyte function has important clinical ramifications, as high mortality rates have been observed in patients displaying evidence of sepsis-induced immune deactivation. In this article, we review the current literature supporting evidence of dysregulation of host immunity occurring during sepsis syndrome, characterize the underlying pathophysiology, and describe novel therapeutic interventions directed at augmenting host immunity during sepsis.

Current Perspectives on the Use of Growth Factors in the Therapy of Acute Myeloid Leukaemia; Malignancy

Recombinant haematopoietic growth factors have been available for clinical use for over a decade, however their role in the management of patients with acute myeloid leukaemia (AML) has yet to be established. There are several potential roles for the use of growth factors in the management of patients with AML, including reduction in the infective complications associated with the underlying disease and its treatment, use as mobilising agents in stem cell transplantation and as priming agents with chemotherapy. Clinical trials have failed to give clear indications for the use of growth factors following chemotherapy, mainly due to the variability of patient populations, chemotherapy and growth factor schedules used. G-CSF appears to be associated with no negative impact on remission rate or survival but clear benefits in terms of infection-related endpoints were not universally seen. Three studies did show a reduction in duration of hospitalisation, particularly when G-CSF was used following consolidation chemotherapy and economic analyses have also shown financial advantages to the administration of G-CSF. GM-CSF had a variable impact on survival and only two studies demonstrated reduction in serious infections or antimicrobial therapy use. These trials also showed economic benefits for the use of GM-CSF. Clinical studies which have attempted to exploit possible potentiation of chemotherapeutic activity by recruitment of leukaemic cells into the cell cycle have generally been disappointing. Use of growth factors for this purpose, outside the context of randomised clinical trials cannot be recommended. GM-CSF may have a role in modulating the cellular immune response against cancer cells but experimental data on its activity against leukaemia cells is limited. Augmentation of white cell function by G-CSF or GM-CSF may also be of clinical benefit in patients with suspected or confirmed fungal infection and further trials are underway.

Immunomodulators in infectious diseases: panoply of possibilites

Infections which caused ravages in the past centuries are again resurgent and newly emerging pathogens capable of human diseases continue to surface. Multidrug antibiotic resistance has turned into a major medical problem. Judicious concepts for combating infections in the 21st century have acquired a new poignancy. Immunomodulators of natural, synthetic, and recombinant origin can stimulate host defense mechanisms for the prophylaxis and treatment of diverse viral, bacterial, parasitic and fungal diseases. Some immunomodulator preparations are already licensed for use in patients and numerous others are being extensively investigated in preclinical and clinical studies. Immunomodulators offer a novel adjunct to established antimicrobial therapies.

Immunomodulatory agents for prophylaxis and therapy of infections

The advent of the antibiotic era ushered in a shift towards non-pathogen-specific therapy of infectious diseases. This led to an overt emphasis on targeting microbial pathogens while strategies directed towards enhancing host immunity were neglected. In an effort to decrease sole reliance on antimicrobials, the time has come for a critical reappraisal of nonantibiotic, albeit immune response-enhancing substances. The diverse array of natural, synthetic, and recombinant immunomodulators discussed in this review succinctly demonstrate the potential of these agents to stimulate host defense mechanisms for prophylaxis and treatment of various microbial infections.

Cytokine modulated cell-membrane bound tumour necrosis factor expression is associated with enhanced monocyte-mediated killing of human leukaemic targets

Cytokines such as interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) activate monocytes both in vitro and in vivo. We therefore studied whether the anti-leukaemic activity of monocytes could be augmented by IL-3 alone or in combination with GM-CSF. Using normal human monocytes stimulated with IL-3, GM-CSF, LPS or combinations of growth factor and LPS, we studied their cytotoxic activity against leukaemic cell-lines and primary AML blasts. IL-3 like GM-CSF, augmented the expression and secretion of TNF but did not prime for further expression and secretion of TNF in response to LPS. Neither GM-CSF or IL-3 increased the expression or secretion of TNF receptor p55 (TNF-Rp55), although both agents increased expression of TNF receptor p75 (TNF-Rp75). Monocyte-mediated cytotoxicity (MMC) against K562 and U937 cell-lines was increased by both GM-CSF and IL-3 stimulation, and both cytokines primed monocytes for increased killing of K562 and KG-1 cell-lines as well as primary AML blasts in response to LPS. The mechanism of action of MMC was largely confirmed to be via surface-bound TNF, although other TNF-independent mechanisms must have been involved.

Modulation of neutrophil apoptosis by granulocyte colony-stimulating factor and granulocyte/macrophage colony-stimulating factor during the course of acute respiratory distress syndrome

OBJECTIVE

To determine whether bronchoalveolar lavage fluid (BALF) from patients either at risk for the acute respiratory distress syndrome (ARDS) or with sustained ARDS modulates neutrophil apoptosis; to measure the BALF concentrations of the apoptosis inhibitors granulocyte colony-stimulating factor (G-CSF) and granulocyte/macrophage colony-stimulating factor (GM-CSF) before and after the onset of ARDS; and to determine whether the BALF concentrations of G-CSF and/or GM-CSF are associated with clinical outcome.

DESIGN

Prospective cohort study.

SETTING

Tertiary university hospital.

PATIENTS

Twenty patients at risk for ARDS and 45 patients with established ARDS.

INTERVENTIONS

Patients at risk for ARDS underwent bronchoalveolar lavage within 24 hrs of being identified, then again 72 hrs later. Patients with ARDS underwent bronchoalveolar lavage within 24 hrs of meeting ARDS criteria, then again on days 3, 7, and 14 of the disease.

MEASUREMENTS AND MAIN RESULTS

Normal peripheral blood neutrophil were incubated overnight in BALF from normal volunteers, from patients at risk for ARDS, or from patients with ARDS. neutrophil apoptosis was determined by flow cytometric analysis of annexin V binding. G-CSF and GM-CSF were measured in BALF by immunoassays. Compared with normal BALF, BALF from patients on days 1 and 3 of ARDS inhibited neutrophil apoptosis, but BALF from patients at later stages of ARDS, or from patients at risk for ARDS, did not. The BALF concentrations of both G-CSF and GM-CSF were elevated early in ARDS and decreased toward later stages. Patients who lived had significantly higher concentrations of GM-CSF in the BALF than those who died.

CONCLUSIONS

We conclude that the antiapoptotic effect of ARDS BALF on normal neutrophil is highest during early ARDS, and decreases during late ARDS. G-CSF and GM-CSF are present in BALF from patients with ARDS, and their concentrations parallel the antiapoptotic effect of ARDS BALF. These data support the concept that the life-span of neutrophil in the air spaces is modulated during acute inflammation. GM-CSF in the air spaces is associated with improved survival in patients with ARDS.

The potential for monocyte-mediated immunotherapy during infection and malignancy--Part II: in vivo activation by exogenous cytokines and clinical applications

The monocyte system exhibits a range of immunological mechanisms that may be harnessed for therapeutic effect against infection and malignancy. The advent of novel therapies aimed at treating infection and malignancy is complemented by a resurgence of clinical interest in immunotherapeutic programmes to treat diseases by modification or direct augmentation of host immunity. Cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma modulate the function of monocytes and have been used to experimentally probe the immunotherapeutic potential of monocytes against micro-organisms and malignancy. However, monocytes rarely act alone but communicate with other leukocytes involved in cell-mediated immunity. In particular monocytes cooperate with the T-helper (Th1 and Th2) sub-populations of peripheral lymphocytes. Moreover, sub-populations of monocytes, as identified by the co-expression of membrane-associated CD14 and CD16, have been shown to exist. At the preclinical level, this provides a unique opportunity to explore the effect of immunotherapeutic strategies on the function of monocyte sub-populations against infectious or malignant challenge and may allow immunotherapeutic strategies to be targeted towards specific monocyte sub-populations. Preclinical and clinical studies in human subjects suggest that GM-CSF and other cytokines such as IFN-gamma are the most promising biological response modifiers for augmenting monocyte-mediated immunity. In this review, the immunotherapeutic potential of the monocyte system will be discussed in the context of combating microbial and malignant disease.

Monocyte dysfunction in patients with multiple myeloma and lymphoplasmacytic disorders is related to serum paraprotein levels

We have investigated monocyte function in 30 patients with lymphoplasmacytic disorders and in 21 age and sex matched normal controls. Marked abnormalities of all facets of monocyte function were demonstrated in six patients with multiple myeloma (MM) and a single patient with Waldenström's macroglobulinaemia (WM) plus significant paraproteinaemia. Serious infection occurred in three of these patients. An inverse relationship between the level of the serum paraprotein and impairment of monocyte phagocytosis plus killing of Candida albicans was observed. Crossover studies suggested that these abnormal findings were constitutive and not reversed by removal of the serum paraprotein. The data suggest that monocyte function is constitutively abnormal in patients with MM and can be further, but reversibly, inhibited by high paraprotein levels. Further research is required to confirm these findings, ascertain whether monocyte function can be normalized using chemotherapy or growth factors, and if so, whether their tumouricidal functions could be harnessed in the treatment of this currently incurable condition.

Role of hematopoietic growth factors in non-neutropenic infections and sepsis

Therapy with colony-stimulating factors has been extended beyond their use in accelerating myeloid cell recovery to take advantage of their immune function-enhancing properties. Studies in animal models and with human subjects suggest a potential role as adjunctive therapy in infections of non-neutropenic hosts, including those with sepsis. Granulocyte colony-stimulating factor may play a pivotal role in the induction of lipopolysaccharide desensitization by nontoxic lipid A analogues proposed for the prevention of sepsis; granulocyte macrophage colony-stimulating factor may be useful in reversing the immune paralysis described in later stages of sepsis. Significant issues of exogenous colony-stimulating factor therapy must be addressed, however: the optimal timing, dose, and clinical context (e.g., type of immunosuppression, duration of infection-inciting stimulus) as well as tissue-specificity of the activities and net effect of potentially conflicting responses (e.g., immune restorative and procoagulant effects of granulocyte macrophage colony-stimulating factor). Resolution of these issues will require carefully designed clinical studies with meticulous monitoring of immunologic parameters.

Effect of clarithromycin and azithromycin on production of cytokines by human monocytes

We examined the in vitro effect of clarithromycin and azithromycin on cytokine production by LPS and Pansorbin stimulated human monocytes. At concentrations that are physiologically achievable, both antibiotics affected in vitro production of IL-1alpha, IL-1beta, IL-6, IL-10, GM-CSF and TNF-alpha to varying degrees. Of those individuals in whom a significant increase or decrease in cytokine production was noted, clarithromycin treatment resulted in a significant suppression of production of each cytokine in 71% and a significant increase in 29% of the individuals. Similar results were noted with azithromycin. The results with IL-6 and TNF-alpha in the clarithromycin studies were most striking. A significant decrease was noted in 60% of individuals for IL-6 and 86% for TNF-alpha. For azithromycin, the most interesting results were for IL-1alpha (decrease in 100% of individuals) and for TNF-alpha (decrease in 100% of individuals). These results show that both clarithromycin and azithromycin alter cytokine production in human monocytes and thus possess immunomodulatory activity.

Leukemia cell differentiation: cellular and molecular interactions of retinoids and vitamin D

1. The conventional approach to treatment of acute myeloid leukemia has been the use of chemotherapy, which although being cytotoxic to malignant clones, is also cytodestructive to normal cells. In addition, some leukemia cells develop resistance to chemotherapy and are therefore difficult to eradicate. 2. Differentiation therapy, whereby immature cells are induced to attain a mature phenotype by differentiation agents, has provided an alternative strategy in the treatment of hyperproliferative disorders. This has been highlighted by the use of all-trans retinoic acid (ATRA) in the treatment of acute promyelocytic leukemia (APL). 3. Another differentiation agent, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), directs monocytic maturation of normal and leukemic cells. Cellular studies have revealed that combinations of vitamin D derivatives and retinoids such as ATRA and 9-cis retinoic acid (9-cis RA) exhibit cooperative effects on differentiation in established leukemia cell lines such as HL-60, U937, and NB4. Furthermore, vitamin D compounds, although not able to induce apoptosis when used alone, potentiate apoptosis induced by 9-cis RA in HL-60 cells and differentially regulate the expression of the apoptosis-related gene products bcl-2 and bax. The molecular mechanisms involved in regulating differentiation and apoptosis by these agents are mediated through the interactions of the nuclear receptors for vitamin D (VDR), ATRA (RAR), and 9-cis RA (RXR), which are able to form homo- or heterodimeric complexes and transcriptionally activate or repress target gene expression. 4. There is evidence to suggest that nitric oxide may also play a role in leukemic cell differentiation and that 1,25(OH)2D3 may influence endogenous nitric oxide production either by directly increasing tumor necrosis factor-alpha (TNF-alpha) or through a secondary mediator such as the C-type lectin CD23.