Recombinant human granulocyte colony-stimulating factor attenuates inflammatory responses in septic patients with neutropenia

Survivors of polymicrobial sepsis are refractory to G-CSF-induced emergency myelopoiesis and hematopoietic stem and progenitor cell mobilization

Sepsis survivors exhibit immune dysfunction, hematological changes, and increased risk of infection. The long-term impacts of sepsis on hematopoiesis were analyzed using a surgical model of murine sepsis, resulting in 50% survival. During acute disease, phenotypic hematopoietic stem and progenitor cells (HSPCs) were reduced in the bone marrow (BM), concomitant with increased myeloid colony-forming units and extramedullary hematopoiesis. Upon recovery, BM HSPCs were increased and exhibited normal function in the context of transplantation. To evaluate hematopoietic responses in sepsis survivors, we treated recovered sham and cecal ligation and puncture mice with a mobilizing regimen of granulocyte colony-stimulating factor (G-CSF) at day 20 post-surgery. Sepsis survivors failed to undergo emergency myelopoiesis and HSPC mobilization in response to G-CSF administration. G-CSF is produced in response to acute infection and injury to expedite the production of innate immune cells; therefore, our findings contribute to a new understanding of how sepsis predisposes to subsequent infection.

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.

Administration of signalling molecules dictates stem cell homing for in situ regeneration

Ex vivo-expanded stem cells have long been a cornerstone of biotherapeutics and have attracted increasing attention for treating intractable diseases and improving tissue regeneration. However, using exogenous cellular materials to develop restorative treatments for large numbers of patients has become a major concern for both economic and safety reasons. Advances in cell biological research over the past two decades have expanded the potential for using endogenous stem cells during wound healing processes, and in particular, recent insight into stem cell movement and homing has prompted regenerative research and therapy based on recruiting endogenous cells. Inspired by the natural healing process, artificial administration of specific chemokines as signals systemically or at the injury site, typically using biomaterials as vehicles, is a state-of-the-art strategy that potentiates stem cell homing and recreates an anti-inflammatory and immunomodulatory microenvironment to enhance in situ tissue regeneration. However, pharmacologically coaxing endogenous stem cells to act as therapeutics in the field of biomedicine remains in the early stages; its efficacy is limited by the lack of innovative methodologies for chemokine presentation and release. This review describes how to direct the homing of endogenous stem cells via the administration of specific signals, with a particular emphasis on targeted signalling molecules that regulate this homing process, to enhance in situ tissue regeneration. We also provide an outlook on and critical considerations for future investigations to enhance stem cell recruitment and harness the reparative potential of these recruited cells as a clinically relevant cell therapy.

Natural products and synthetic compounds as immunomodulators

Research on immunomodulation by natural products or synthetic derivatives is of key interest for anti-infective therapy for a number of reasons. Many plant remedies well-known in traditional medicine or refined natural products in clinical use exert their anti-infective effects not only (if at all) by directly affecting the pathogen. At least part of their effect is indirect, by stimulating natural and adaptive defense mechanisms of the host. These findings have now given many empirical therapies a rationale, scientific basis and thereby a means for 'intelligent' improvement. In discovering the molecular mechanisms by which known remedies exert their effects, chosen elements further down the 'chain of command' might be synthesized and applied directly for more rapid and selective cure, omitting unwanted side effects. The direct use of recombinant cytokines, often in combination with antibiotics, is one consequence of this rationale.

CBLB613: a TLR 2/6 agonist, natural lipopeptide of Mycoplasma arginini , as a novel radiation countermeasure

To date, there are no safe and effective drugs available for protection against ionizing radiation damage. Therefore, a great need exists to identify and develop non-toxic agents that will be useful as radioprotectors or postirradiation therapies under a variety of operational scenarios. We have developed a new pharmacological agent, CBLB613 (a naturally occurring Mycoplasma-derived lipopeptide ligand for Toll-like receptor 2/6), as a novel radiation countermeasure. Using CD2F1 mice, we investigated CBLB613 for toxicity, immunogenicity, radioprotection, radiomitigation and pharmacokinetics. We also evaluated CBLB613 for its effects on cytokine induction and radiation-induced cytopenia in unirradiated and irradiated mice. The no-observable-adverse-effect level of CBLB613 was 1.79 mg/kg and 1 mg/kg for single and repeated doses, respectively. CBLB613 significantly protected mice against a lethal dose of (60)Co γ radiation. The dose reduction factor of CBLB613 as a radioprotector was 1.25. CBLB613 also mitigated the effects of (60)Co γ radiation on survival in mice. In both irradiated and unirradiated mice, the drug stimulated induction of interleukin-1β (IL-1β), IL-6, IL-10, IL-12, keratinocyte-derived chemokine, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor-1α. CBLB613 also reduced radiation-induced cytopenia and increased bone marrow cellularity in irradiated mice. Our immunogenicity study demonstrated that CBLB613 is not immunogenic in mice, indicating that it could be developed as a radioprotector and radiomitigator for humans against the potentially lethal effects of radiation exposure.

Use of granulocyte colony-stimulating factor in patients with severe sepsis or septic shock

PURPOSE

The efficacy and safety of granulocyte colony-stimulating factor (G-CSF) in critically ill patients with severe sepsis or septic shock were evaluated.

SUMMARY

The medical literature was reviewed to identify published trials, case reports, and case series on the use of G-CSF in critically ill patients for treatment of severe sepsis or septic shock. G-CSF has been evaluated as an adjunct to standard care for critically ill patients. Initial studies involving critically ill patients with severe sepsis or septic shock found mortality benefits with G-CSF therapy; however, these findings are limited by factors such as small sample sizes, selection bias, and lack of an appropriate control group. Prospective, randomized, multicenter, double-blind studies failed to confirm the benefits in mortality for patients receiving G-CSF for the treatment of severe sepsis and septic shock. Due to the limitations in the design of the studies that report a mortality benefit and prospective, randomized, multicenter, double-blind studies that report the lack of a mortality benefit, a recommendation to add G-CSF as an adjunctive therapy in critically ill patients with severe sepsis and septic shock cannot be made at this time.

CONCLUSION

The available data, especially those from large, prospective, randomized, double-blind studies, do not support the use of G-CSF as an adjunct therapy to standard care for critically ill patients with severe sepsis or septic shock. Data from prospective, large, randomized, controlled, well-designed studies are needed to define the optimal G-CSF dosing regimen, the safety of this therapy, and the effects of G-CSF on patient morbidity and survival.

Toward improving mucosal barrier defenses: rhG-CSF plus IgG antibody

Epithelial cell functions ultimately define the ability of the extremely low birth weight human fetus to survive outside of the uterus. These specialized epithelial cell capacities manage all human interactions with the ex utero world including: (i) lung mechanics, surface chemistry and gas exchange, (ii) renal tubular balance of fluid and electrolytes, (iii) barrier functions of the intestine and skin for keeping bacteria out and water in, plus enabling intestinal digestion, as well as (iv) maintaining an intact neuroepithelium lining of the ventricles of the brain and retina. In Part I of this two part review, the authors describe why the gut barrier is a clinically relevant model system for studying the complex interplay between innate and adaptive immunity, dendritic &epithelial cell interactions, intraepithelial lymphocytes, M-cells, as well as the gut associated lymphoid tissues where colonization after birth, clinician feeding practices, use of antibiotics as well as exposure to prebiotics, probiotics and maternal vaginal flora all program the neonate for a life-time of immune competence distinguishing "self" from foreign antigens. These barrier defense capacities become destructive during disease processes like necrotizing enterocolitis (NEC) when an otherwise maturationally normal, yet dysregulated and immature, immune defense system is associated with high levels of certain inflammatory mediators like TNFa. In Part II the authors discuss the rationale for why rhG-CSF has theoretical advantages in managing NEC or sepsis by augmenting neonatal neutrophil number, neutrophil expression of Fcg and complement receptors, as well as phagocytic function and oxidative burst. rhG-CSF also has potent anti-TNFa functions that may serve to limit extension of tissue destruction while not impairing bacterial killing capacity. Healthy, non-infected neutropenic and septic neonates differ in their ability to respond to rhG-CSF; however, no neonatal clinical trials to date have identified a clear clinical benefit of rhG-CSF therapy. This manuscript will review the literature and evidence available for identifying the ideal subject for cytokine treatment using NEC as the model disease target.

Effects of whole-body gamma irradiation and 5-androstenediol administration on serum G-CSF

5-Androstenediol (5-AED) is a natural circulating adrenocortical steroid hormone that interconverts in vivo with other members of the 5-androstene family of steroids: dehydroepiandrosterone and 5-androstenetriol. These steroids stimulate immune responses and resistance to infection. 5-AED has been identified as a systemic radiation countermeasure that enhances survival in mice exposed to gamma irradiation and ameliorates radiation-induced neutropenia in mice and nonhuman primates. 5-AED mitigates radiation-induced decreases in platelets, natural killer (NK) cells, red blood cells, and monocytes. Administration of 5-AED causes functional activation of circulating granulocytes (phagocytic ability), monocytes (oxidative burst), and NK cells (surface CD11b expression). The effects of 5-AED on survival and hematological parameters are consistent with induction of hematopoietic cytokines. To test this hypothesis, we measured serum cytokines by ELISA, Luminex, and a cytokine array. A cytokine array was used for 62 different cytokines, chemokines, growth factors, and soluble receptors. 5-AED caused significant increases in circulating granulocyte colony-stimulating factor (G-CSF) in irradiated and unirradiated animals as observed with ELISA and Luminex. The cytokine array results suggest induction of G-CSF and additional cytokines, and related molecules. Since G-CSF is an important hematopoietic cytokine, the results support our hypothesis that the previously observed increases in numbers of hematopoietic progenitors, circulating innate immune cells and platelets, and functional activation of granulocytes, monocytes, and NK cells result from a cytokine cascade induced by 5-AED.

THE EFFECTS OF GRANULOCYTE COLONY-STIMULATING FACTOR IN PRECLINICAL MODELS OF INFECTION AND ACUTE INFLAMMATION

The cytokine granulocyte colony-stimulating factor (G-CSF) is a potent endogenous trigger for the release of neutrophils from bone marrow stores and for their activation for enhanced antimicrobial activity. G-CSF has been widely evaluated in preclinical models of acute illness, with generally promising though divergent results. A recombinant G-CSF molecule has recently undergone clinical trials to assess its efficacy as an adjuvant therapy in community-acquired and nosocomial pneumonia, however, these studies failed to provide convincing evidence of benefit. We undertook a systematic review of the published literature reporting the effects of modulation of G-CSF in preclinical in vivo models to determine whether evidence of differential efficacy might explain the disappointing results of human studies and point to disease states that might be more likely to benefit from G-CSF therapy. G-CSF has been evaluated in 86 such studies involving a variety of different models. The strongest evidence of benefit was seen in studies involving intraperitoneal challenge with live organisms; benefit was evident whether the agent was given before or after challenge. G-CSF demonstrates anti-inflammatory activity in models of systemic challenge with viable organisms or endotoxin, but only when the agent is given before challenge; evidence of benefit after challenge was minimal. Preclinical models of intrapulmonary challenge only show efficacy when the cytokine is administered before the infectious challenge, and suggested harm in gram-negative pneumonia resulting from challenge with Escherichia coli or Klebsiella. There is little evidence for therapeutic efficacy in noninfectious models of acute illness. We conclude that the most promising populations for evaluation of G-CSF are neutropenic patients with invasive infection and patients with intra-abdominal infection, particularly those with the syndrome of tertiary, or recurrent, peritonitis. Significant variability in the design and reporting of studies of preclinical models of acute illness precludes more sophisticated data synthesis.

Perioperative recombinant human granulocyte colony-stimulating factor (Filgrastim) treatment prevents immunoinflammatory dysfunction associated with major surgery

OBJECTIVE

To examine the effects of perioperative rhG-CSF administration on immune function in patients subjected to major surgery.

SUMMARY BACKGROUND DATA

Severe trauma, such as major surgery, initiates acute immunodysfunction which predisposes the patient towards infectious complications.

METHODS

Sixty patients undergoing elective surgery received either recombinant human granulocyte colony-stimulating factor/rh G-CSF (Filgrastim) or a placebo perioperatively. At several time points before and after the surgical intervention immunofunctional parameters were assessed. RESULTS Leukocyte counts and serum levels of anti-inflammatory mediators (IL-1ra and TNF-R) were increased in Filgrastim-treated patients, while the post-operative acute phase response was attenuated. Monocyte deactivation (reduced TNF-alpha release and HLA-DR expression) and lymphocyte anergy (impaired mitogenic proliferation and reduced TH1 lymphokine release) were blunted and the incidence and severity of infectious complications were reduced.

CONCLUSIONS

These results suggest that Filgrastim treatment reinforces innate immunity, enabling better prevention of infection. Thus, this unique combination of hematopoietic, anti-inflammatory and anti-infectious effects on the innate immune system warrants further study of clinical efficacy and sepsis prophylaxis.

The hematologic system as a marker of organ dysfunction in sepsis

Sepsis with acute organ dysfunction (severe sepsis) results from a systemic proinflammatory and procoagulant response to infection. Organ dysfunction in the patient with sepsis is associated with increased mortality. Although most organs have discrete anatomical boundaries and carry out unified functions, the hematologic system is poorly circumscribed and serves several unrelated functions. This review addresses the hematologic changes associated with sepsis and provides a framework for prompt diagnosis and rational drug therapy. Data sources used include published research and review articles in the English language related to hematologic alterations in animal models of sepsis and in critically ill patients. Hematologic changes are present in virtually every patient with severe sepsis. Leukocytosis, anemia, thrombocytopenia, and activation of the coagulation cascade are the most common abnormalities. Despite theoretical advantages of using granulocyte colony-stimulating factor to enhance leukocyte function and/or circulating numbers, large clinical trials with these growth factors are lacking. Recent studies support a reduction in the red blood cell transfusion threshold and the use of erythropoietin treatment to reduce transfusion requirements. Treatment of thrombocytopenia depends on the cause and clinical context but may include platelet transfusions and discontinuation of heparin or other inciting drugs. The use of activated protein C may provide a survival benefit in subsets of patients with severe sepsis. The hematologic system should not be overlooked when assessing a patient with severe sepsis. A thorough clinical evaluation and panel of laboratory tests that relate to this organ system should be as much a part of the work-up as taking the patient's blood pressure, monitoring renal function, or measuring liver enzymes.

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.

Colony-stimulating factors for the management of neutropenia in cancer patients

Neutropenia and its subsequent infectious complications represent the most common dose-limiting toxicity of cancer chemotherapy. Febrile neutropenia (FN) occurs with common chemotherapy regimens in 25 to 40% of treatment-naive patients, and its severity depends on the dose intensity of the chemotherapy regimen, the patient's prior history of either radiation therapy or use of cytotoxic treatment, and comorbidities. The occurrence of FN often causes subsequent chemotherapy delays or dose reductions. It may also lengthen hospital stay, increase monitoring, diagnostic and treatment costs, and reduce patient quality of life. A decade after their introduction, colony-stimulating factors (CSFs) such as granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are now an integral part of the prevention of potentially life-threatening FN; however, only G-CSF has US Food and Drug Administration approval for use in chemotherapy-induced neutropenia. These adjunctive agents accelerate formation of neutrophils from committed progenitors, thereby reducing the duration and severity of neutropenia. Important uses of CSFs in oncology are prevention of FN after chemotherapy, treatment of febrile neutropenic episodes and support following bone marrow transplantation, and collection of CSF-mobilised peripheral blood progenitor cells. G-CSF is used more frequently than GM-CSF for all of these indications because of fewer associated adverse effects. Clinical trials to date have not demonstrated a significant effect on overall survival or disease-free survival, which is most likely to be due to small sample size and lack of power to prove effect. However, they have demonstrated clinical utility in allowing the delivery of planned chemotherapy dose on schedule, an important clinical goal especially in curative tumour settings. The high cost of these agents limits their widespread use. Current American Society of Clinical Oncology guidelines recommend primary prophylaxis, or first cycle use, with CSFs being confined to patients with > or = 40% risk of FN, which may include elderly patients and other high-risk patients. In addition to the risk of FN, primary prophylaxis should also be considered if the patient has risk factors that place them in the Special Circumstances category. These risk factors may include decreased immune function in patients who are already at an increased risk of infection and pre-existing neutropenia due to disease, extensive prior chemotherapy, or previous irradiation to the pelvis or other areas containing large amounts of bone marrow. Future studies are needed to better define the patients most likely to benefit from CSF therapy, both for prophylaxis and as an adjunct to antibiotics for treatment of FN. Other potential uses include combination therapy with stem cell factors and other cytokines to boost progenitor cell development, maintaining dose intensity of salvage therapy in metastatic cancer patients, and application in patients with pneumonia, Crohn's fistulas, diabetic foot infections and a variety of other infectious conditions.

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.

Granulocyte colony-stimulating factor improves deficient in vitro neutrophil transendothelial migration in patients with advanced liver disease

Bacterial infections are frequent complications in patients with liver cirrhosis. Cirrhotic patients present abnormalities in both innate and adaptive immune responses, including a deficient neutrophil recruitment to infected sites. The purpose of this study was to assess neutrophil-endothelium interactions in cirrhotic patients and evaluate the effects of G-CSF on this process. We studied neutrophil adhesion and transendothelial migration in 14 cirrhotic patients and 14 healthy controls. We also analyzed neutrophil expression of the adhesion molecules CD62L and CD11b in whole blood by flow cytometry. Cirrhotic patients expressed higher levels of CD11b than healthy controls, whereas CD62L expression was significantly lower, suggesting exposure of neutrophils to activating agents within the bloodstream. Neutrophils from cirrhotic patients showed increased adhesion to both resting and tumor necrosis factor alpha-stimulated microvascular endothelial cells and decreased transendothelial migration. Granulocyte colony-stimulating factor (G-CSF) (100 ng/ml) significantly enhanced neutrophil adhesion to microvascular endothelial cells in healthy controls but not in cirrhotic patients. G-CSF also significantly improved neutrophil transmigration in cirrhotic patients and healthy controls. In conclusion, cirrhotic patients exhibit increased neutrophil adhesion to microvascular endothelium and deficient transendothelial migration. G-CSF enhances neutrophil transendothelial migration in cirrhotic patients despite having no effect on neutrophil adhesion. Therefore, G-CSF may be able to increase neutrophil recruitment into infected sites in these patients.

Granulocyte colony-stimulating factor (G-CSF) stiffens leukocytes but attenuates inflammatory response without lung injury in septic patients

OBJECTIVE

To determine whether granulocyte colony-stimulating factor (G-CSF) administration changes leukocyte deformability resulting in lung injury in patients with sepsis.

METHODS

Twenty-five consecutive septic patients were divided randomly into two groups. Twelve patients were given recombinant human G-CSF subcutaneously at 2 microg/kg once a day for 5 days (group G). The remaining 13 patients were given sterilized saline as placebo (group N). Leukocyte count; concentrations of C-reactive protein (CRP) and thrombomodulin (TM); respiratory index (RI) and lung injury score (LIS); and APACHE II score and Goris MOF index were determined before and after G-CSF or placebo administration. Leukocyte deformability was observed in a microchannel array etched on a single-crystal silicon tip, which simulates the microvasculature. The number of microchannels obstructed (NOM) by stiffened leukocytes was counted. Transit time (TT), that is, the time taken for 100 microL of whole blood to pass through the microchannel, was determined.

RESULTS

G-CSF administration significantly increased leukocyte count and decreased CRP concentration. In group G, both NOM and TT increased significantly 5 days after G-CSF administration; they did not change in group N. However, RI, LIS, and TM did not change, suggesting that no patient developed lung injury.

CONCLUSION

G-CSF causes leukocyte stiffness but attenuates inflammatory response without inducing lung injury in septic patients.

Fighting infection using immunomodulatory agents

The last decade has seen the emergence of immunomodulators as promising therapeutic agents in infectious diseases. A diverse array of recombinant, synthetic and natural immunomodulatory preparations for prophylaxis and treatment of various infections are available today. Some of these substances, such as granulocyte colony-stimulating factor (G-CSF), interferons, imiquimod and bacterial-derived preparations are already licensed for use in patients. Others including IL-12, various chemokines, synthetic cytosine phosphate-guanosine (CpG) oligodeoxynucleotides and glucans are being investigated extensively in clinical and preclinical studies. Immunomodulatory regimens offer an attractive approach as an adjunct modality for control of microbial diseases in the era of antibiotic resistance. Practical application of the advances in molecular biology, bioinformatics, genomic mining and high-throughput peptide synthesis should foster future discovery and development of novel immunomodulators contingent upon scientific evidence rather than dictates of discursive empiricism.

Differential alterations in plasma colony-stimulating factor concentrations after coronary artery bypass graft surgery with extracorporeal circulation

To determine whether colony-stimulating factor (CSF) might participate to the inflammatory response after cardiac surgery, plasma concentrations of granulocyte-CSF (G-CSF), macrophage-CSF (M-CSF) and GM-CSF were measured in 31 patients undergoing coronary artery bypass graft (CABG) surgery with extracorporeal circulation (ECC). Plasma G-CSF and M-CSF concentrations increased after weaning of ECC, reached maximum value at the sixth post-operative hour, and remained elevated at the 24th post-operative hour. In contrast, plasma GM-CSF levels did not change. Plasma M-CSF, G-CSF and GM-CSF values were not different whether patients developed post-operative complications or not. In conclusion, M-CSF and G-CSF are produced after CABG surgery despite the use of high aprotinin doses in hope to abrogate the inflammatory response. G-CSF and M-CSF might play a role in the inflammatory process often observed after CABG surgery.

Characteristics of infection and leukocyte count in severely head-injured patients treated with mild hypothermia

OBJECTIVE

This study was designed to characterize the infectious complications and kinetics of leukocyte count in severely head-injured patients treated with mild hypothermia.

PATIENTS AND METHODS

We retrospectively analyzed the incidence and severity of infectious complications as well as daily changes in leukocyte count in 41 severely head-injured patients treated with mild hypothermia (group H). They were retrospectively compared with 25 severely head-injured patients treated with high-dose barbiturates (group B) and to 25 other severely head-injured patients treated with no barbiturates (group N).

RESULTS

Initial intracranial pressure was significantly higher in group H than in the other groups. No significant differences existed in the incidence of pneumonia or meningitis among the three groups, whereas the incidence of bacteremia was significantly higher in group H than in the other two groups. Pneumonia was significantly more severe in group H than in the other groups. In six patients of group H, pneumonia spread fulminantly to become life threatening. Daily changes in total leukocyte count showed the same pattern, consisting of a peak, a nadir, and a second peak in all groups. Total leukocyte count was, however, significantly lower during the first 2 weeks in group H than in the other two groups. Lymphocyte and neutrophil counts were also lower in group H.

CONCLUSION

Infectious complications were more severe and leukocyte counts were lower in patients treated with mild hypothermia, who also had the highest initial intracranial pressures, than in patients treated with conventional therapies. Measures against increased susceptibility to infection and leukocyte suppression should be explored.

Difference in the responses after administration of granulocyte colony-stimulating factor in septic patients with relative neutropenia

OBJECTIVE

The objective of this study was to classify the clinical responses after administration of granulocyte colony-stimulating factor (G-CSF) in septic patients with relative neutropenia.

PATIENTS AND METHODS

We administered recombinant human G-CSF (2 microg/kg) subcutaneously once a day for 5 days to 30 septic patients with white cell counts below 5,000 cells/mm3. Absolute neutrophil count (ANC), neutrophil differentiation, and serum concentration of G-CSF were determined serially. Bone marrow also was analyzed before and after treatment.

RESULTS

Neutrophil responses to G-CSF varied from good (ANC > 10,000/mm3, group G, n = 20) to moderate (ANC < 10,000/mm3, group M, n = 5) to poor (no increase in ANC, group P, n = 5). Before G-CSF administration, the three groups showed no differences in ANC but did show significant differences in serum concentration of G-CSF. G-CSF concentration was 0.16 +/- 0.03 ng/mL in group G, 7.0 +/- 3.0 ng/mL in group M, and 270 +/- 90 ng/mL in group P. Immature neutrophils accounted for 35.0 +/- 3.7% of peripheral leukocytes in group P but only 5.1 +/- 0.6% in group G. Although bone marrow was depressed in all groups before G-CSF treatment, nucleated cell count increased significantly after rhG-CSF treatment in groups G and M. Survival rate after 4 weeks was 90% in group G and 100% in group M; no patient in group P survived.

CONCLUSION

G-CSF administration was effective in septic patients with a low percentage of immature neutrophils and insufficient endogenous G-CSF. It had little effect on patients with a high percentage of immature neutrophils whose G-CSF production was up-regulated and whose bone marrow was severely depressed.

Adjunctive Therapies for Sepsis and Septic Shock

The inflammatory cascade that ensues after an infectious insult is protean in its manifestations, resulting in mild self-limited illness in some patients, while progressing to fulminant sepsis and multisystem organ failure in others. Research into the pathophysiology of this cascade has been intense, but advances in the treatment of sepsis have been few and far between. Although mortality rates have been impacted slightly in patients with sepsis--with improved survival in certain patient subgroups--overall survival still reaches only 55% to 60%. In this paper we will review some of the most recent advances in the therapy of the sepsis syndrome, specifically the roles of cytokine modifiers, supranormal delivery of oxygen, granulocyte colony-stimulating factor administration in leukopenic patients, and parenteral nutrition. Hopefully, these modalities represent additional steps in the path towards a meaningful improvement in survival from this catastrophic condition.

Granulocyte colony-stimulating factor ameliorates life-threatening infections after combined therapy with barbiturates and mild hypothermia in patients with severe head injuries

OBJECTIVE

The objective of this study was to clarify the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) administration on infections in patients with severe head injuries after combined therapy with high-dose barbiturates and mild hypothermia.

PATIENTS AND METHODS

Since 1996, we have administered rhG-CSF to eight patients with severe head injuries for 5 days (group G). Their treatment results were compared with those of 22 patients cared for earlier without rhG-CSF treatment (group N). All patients in both groups met the criteria of total leukocyte count (TLC) less than 5,000/mm3, C-reactive protein (CRP) over 10 mg/dL, and the presence of an infectious complication. Changes in the TLC, CRP, respiratory index, intracranial pressure, and infectious condition were evaluated in both groups. In addition, the nucleated cell count and differentiation from bone marrow aspiration, neutrophil functions, serum concentrations of interleukin-6, and plasma concentration of leukocyte elastase were evaluated in group G.

RESULTS

In group G, TLC, nucleated cell count, and neutrophil functions significantly increased, whereas CRP, respiratory index, and interleukin-6 decreased reciprocally. There was no deterioration of intracranial pressure and leukocyte elastase. Consequently, seven of the eight patients in group G recovered from life-threatening infections, and none of the eight patients died. However, in group N, CRP and respiratory index remained high and TLC did not increase as much as it did in group G. Infections continued after 5 days in 17 of the 22 patients, 7 of whom died from severe infections during hospitalization.

CONCLUSION

Administration of rhG-CSF ameliorated life-threatening infections without causing lung injury or increasing brain swelling in patients with severe head injuries who were treated with combined therapy involving high-dose barbiturates and mild hypothermia.

Priming, second-hit priming, and apoptosis in leukocytes from trauma patients

BACKGROUND

Polymorphonuclear leukocytes (PMNL) play important roles in both host defenses and systemic inflammatory responses after insults. The objectives of this study are to examine the serial changes in PMNL priming and apoptosis in severely injured patients and to evaluate the impact of second hits on primed PMNL function and systemic vascular endothelial damage.

METHODS

Twenty-four severely injured patients (mean Injury Severity Score, 31.1 +/- 9.7) were included. Infections were seen as second hits after trauma in seven patients. Oxidative activity, phagocytosis, and apoptosis of PMNL from serial blood samples were measured by flow cytometry. Oxidative activity with no stimulus and with formylmethionyl-leucyl-phenylalanine (FMLP) were analyzed as the priming index and FMLP response, respectively. Interleukin (IL)-6, IL-10, PMNL elastase, and thrombomodulin concentrations in blood were also measured before and after the second hit.

RESULTS

The PMNL priming index was elevated from days 2 to 13, especially days 2 to 5 after injury. FMLP response was enhanced from days 2 to 21 after injury. Apoptosis of PMNL was inhibited for as long as 3 weeks after injury. Infections as second hits after trauma enhanced both the priming index and the FMLP response within 24 hours after diagnosis of infection and increased serum IL-6 concentrations. However, serum thrombomodulin levels were not affected by second hits. All patients with second hits survived.

CONCLUSION

Severe trauma stimulated acute-phase priming in PMNL and inhibited apoptosis. Infections after trauma induced second-hit priming in PMNL, but the unchanged serum levels of thrombomodulin suggest that priming per se may not cause systemic vascular endothelial damage.