Time course of cytokine levels in sepsis

Continuous venovenous hemofiltration improves intensive care unit, but not hospital survival rate, in nonoliguric septic patients

PURPOSE

The purpose of this study was to assess the effect of the early institution of continuous veno-venous hemofiltration on survival rates of nonoliguric, septic patients.

MATERIALS AND METHODS

A retrospective study of 48 nonoliguric septic patients with PaO(2)/FIO(2) < or = 250, who were admitted to the General Intensive Care of the Soroka Medical Center. Twenty-six patients were treated with continuous venovenous hemofiltration (CVVH group) and 22 were treated by conventional therapy. The end point of treatment was weaning from mechanical ventilation, adequate oxygenation, and the need for minimal cardiocirculatory support.

RESULTS

The study groups were similar in terms of age, gender, percentage of surgical or nonsurgical patients, APACHE II scores, and the Therapeutic Intervention Scoring System (TISS). Baseline serum urea and creatinine levels were similar in the groups, but the PAO(2)/FIO(2) ratio was significantly lower in the CVVH group (150.6 +/- 86 vs. 214.2 +/- 8.9). Twenty of the CVVH patients and 10 of the patients receiving conventional therapy were discharged from the intensive care unit (P =.03), but the hospital discharge rate was only slightly higher in the CVVH group (12 of 26) compared with the conventional therapy group (7 of 22) (P =.145).

CONCLUSIONS

In this retrospective uncontrolled study, the mortality rate was considerably lower in nonoliguric septic patients who received continuous venovenous hemofiltration early in the course of the disease. The improved survival rate may be due to the ability of CVVH to eliminate mediators involved in the septic process, thus averting the multiple system organ failure consequent to septic insult.

Effect of corticosteroids on nuclear factor-kappaB activation and hemodynamics in late septic shock

OBJECTIVE

To describe the underlying pathophysiologic mechanisms of the effect of corticosteroids in a patient with late septic shock.

DESIGN

Case report.

SETTING

The medical intensive care unit at University Medical Center Utrecht.

PATIENT

An 86-yr-old female patient with late septic shock requiring mechanical ventilation and vasopressive agents.

INTERVENTIONS

Administration of hydrocortisone, 300 mg daily.

MEASUREMENTS AND MAIN RESULTS

Within 3 days of corticosteroid treatment, the patient could be weaned of vasopressive agents and mechanical ventilation. Serum C-reactive protein levels normalized. Nuclear factor-kappaB activation in unstimulated and in vitro lipopolysaccharide-stimulated peripheral blood mononuclear cells decreased to background level within 5 days. Repeated functional tests of the hypothalamic-pituitary-adrenal axis were normal.

CONCLUSION

Our data suggest that the pathophysiologic mechanism behind the clinical effects of supraphysiologic doses of corticosteroids in late septic shock is directly related to the inhibition of nuclear factor-kappaB in peripheral blood mononuclear cells.

iNOS expression by activated neutrophils from patients with sepsis

BACKGROUND

Enhanced production of nitric oxide (NO) is associated with various inflammatory diseases such as sepsis. Although activated neutrophils are presumably involved in septic organ injury, the expression of inducible nitric oxide synthase (iNOS) by these cells has not been elucidated. The authors investigated whether activated neutrophils in sepsis could induce mRNA for iNOS and produce NO.

METHODS

Peripheral blood neutrophils were obtained from healthy volunteers, and septic patients underwent a surgical operation. The neutrophils of the healthy volunteers were stimulated with lipopolysaccharide (LPS) and/or tumour necrosis factor-alpha (TNF-alpha). The iNOS expression and NO production were examined by the reverse transcription-polymerase chain reaction and Griess method, respectively.

RESULTS

Circulating neutrophils obtained from patients with sepsis expressed higher levels of iNOS mRNA than those from patients with systemic inflammatory response syndrome (SIRS). Resting neutrophils from normal controls did not express iNOS mRNA and thus did not produce NO. After in vitro stimulation with LPS and TNF-alpha, the neutrophils did express iNOS mRNA and thus produce NO.

CONCLUSION

Activated neutrophils may be one source of NO production in sepsis.

The effect of aging on circulating levels of proinflammatory cytokines during septic shock. Norasept II Study Investigators

BACKGROUND

As the proportion of the population that is older continues to rise, infection in older people has become an important healthcare problem. Although aging is associated with multiple abnormalities in immune function, the effect of aging on the production of proinflammatory cytokines has not been well studied under conditions of clinical stress.

OBJECTIVES

The aim of this study was to examine the effect of aging on circulating levels of the proinflammatory cytokines in a large cohort of septic shock patients. We hypothesized that aging would be associated with a diminished proinflammatory cytokine response to sepsis.

DESIGN

Patients with septic shock who were enrolled in the placebo limb of the North American Sepsis Trial (NORASEPT II) study were analyzed.

SETTING

The intensive care units of 105 hospitals in the United States and Canada.

PARTICIPANTS

Nine hundred and thirty patients presenting to hospital within 12 hours of the onset of septic shock.

MEASUREMENTS

Interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), soluble tumor necrosis factor-receptor-55 (sTNF-R55), and soluble tumor necrosis factor-receptor-75 (sTNF-R75) concentrations were measured at enrollment. The study population was broken down into five age groups as follows: less than 50 years (group one), 50 to 64 years (group two), 65 to 74 years (group three), 75 to 84 years (group four), and 85 or older (group five). Clinical, demographic, and cytokine data were extracted to describe each age group.

RESULTS

Data were available for 930 patients. The patients' mean age (+/- SD) was 59 +/- 17 years (range, 18 to 102). There were 280 patients in group one, 242 in group two, 210 in group three, 150 in group four, and 48 in group five. The primary diagnoses; clinical characteristics; and IL-6, sTNF-R55, and sTNF-R75 levels were similar among the five age groups. The TNF-alpha levels were significantly higher, however, in the oldest group of patients (group five). The 28-day survival was 49% in patients over the age of 75 and 58% in those under 75 years (P = .03). There was no gender difference in survival or cytokine levels.

CONCLUSIONS

Contrary to our expectations, we found that aging was not associated with a decline in the circulating levels of proinflammatory cytokines.

Ventricular cerebrospinal fluid and serum concentrations of sTNFR-I, IL-1ra, and IL-6 after aneurysmal subarachnoid hemorrhage

Postsubarachnoid hemorrhage, systemic inflammatory response syndrome and associated organ system failure are more frequently found in patients in poor neurologic condition. Since subarachnoid hemorrhage causes a profound intrathecal inflammatory response with production of proinflammatory cytokines TNFalpha, IL-1beta, and IL-6, a possible explanation for this association is that brain-derived cytokines may enter the systemic circulation in the presence of postsubarachnoid hemorrhage blood brain barrier disruption to systemically activate inflammatory cascades and thereby contribute to the development of postsubarachnoid hemorrhage systemic inflammatory response syndrome and extracerebral organ system failures. In 44 patients with aneurysmal subarachnoid hemorrhage admitted within 3 days of the initial bleed, extracerebral organ system functions were assessed individually and in aggregate using the modified Multiple Organ Dysfunction Score. Serum and cerebrospinal fluid concentrations of soluble tumor necrosis factor-alpha receptor-I, interleukin-1beta receptor antagonist, and IL-6 were determined during the first 2 weeks after subarachnoid hemorrhage and tested for correlation with (1) admission Hunt-Hess grade, (2) development of systemic inflammatory response syndrome and extracerebral organ system failures, and (3) neurologic outcome. The development of postsubarachnoid hemorrhage systemic inflammatory response syndrome and extracerebral organ system failures was paralleled by a significant increase in serum but not in cerebrospinal fluid levels of soluble tumor necrosis factor-alpha receptor-I and IL-1ra, that is, patients with and without extracerebral organ system failures did not differ in pattern and time course of cerebrospinal fluid cytokine concentrations. In contrast, increasing soluble tumor necrosis factor-alpha receptor-I and interleukin-1beta receptor antagonist serum levels correlated with a higher Multiple Organ Dysfunction score and with individual organ system dysfunctions. Postsubarachnoid hemorrhage, systemic inflammatory response syndrome and extracerebral organ system failures could therefore not be linked to changes in cerebrospinal fluid cytokine concentration profiles.

Catecholamines up-regulate lipopolysaccharide-induced IL-6 production in human microvascular endothelial cells

The catecholamine-mediated modulation of the cytokine network has primarily been demonstrated for leukocytes. Whereas catecholamines decrease the LPS-induced production of IL-6 by leukocytes, serum levels of IL-6 are dramatically increased by the catecholamine epinephrine in animal endotoxemia models. We now demonstrate that epinephrine as well as norepinephrine can induce IL-6 in an endothelial cell line (HMEC-1). Furthermore, these catecholamines could even potentiate the LPS-induced IL-6 protein production. The synergistic effect of catecholamines and LPS could be reproduced in primary human skin microvascular endothelial cells. The catecholamine-induced IL-6 stimulation is based on increased IL-6 mRNA levels. RNA stability assays revealed that this regulation is not a result of enhanced RNA stability and therefore is most likely due to an increased transcription. Treatment with cycloheximide indicated that new protein synthesis is not necessary for this transcriptional up-regulation of IL-6 mRNA. Preincubation with alpha and beta receptor antagonists showed that the effect is mediated by beta(1)- and beta(2)-adrenergic receptors. Thus, endothelial cells might be a possible source of increased IL-6 production observed in situations such as stress or septic shock, in which catecholamines are elevated due to endogenous production or exogenous application.

An improved clinically relevant sepsis model in the conscious rat

OBJECTIVE

To develop an improved small animal experimental paradigm that more closely mimics human sepsis.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

Medical school research laboratory.

SUBJECTS

Male Sprague-Dawley rats (280-320 g).

INTERVENTIONS

We monitored the hemodynamic, hematologic, and biochemical consequences of abdominal sepsis produced by intraperitoneal implantation of a fibrin clot containing Escherichia coli in conscious, antibiotic-treated, rats.

MEASUREMENTS AND MAIN RESULTS

Similar to human sepsis, the implanted, infected clot (LD50 = 5-7 x 10(8) colony forming units/mL, n = 6) elevated cardiac index (>7% vs. sterile clot, p < .05, at 4 hrs), whereas mean arterial pressure and heart rate remained unaffected. The total peripheral resistance index and stroke volume index tended to decrease and increase, respectively. In contrast, an intravenous bolus injection of endotoxin (LD50 of E. coli lipopolysaccharide = 5.6 mg/kg, n = 7), the most commonly used sepsis model, induced profound hypodynamic responses manifested by a 27% decrease (vs. endotoxin vehicle, p < .01) in cardiac index, a 28% increase in the total peripheral resistance index (p < .01), and a 33% decrease in the stroke volume index (P < .01). The infectious peritonitis model also displayed dose-dependent thrombocytopenia (<61%, p < .05), leukopenia (<60%, p < .05), and mortality rate (50% at 5-7 x 10(8) colony forming units/mL, p < .05) with a minimally elevated serum tumor necrosis factor-alpha level (145 vs. 12 +/- 6 pg/mL in controls, p < .05).

CONCLUSION

This rodent model of antibiotic-treated, intra-abdominal infection features key characteristics of clinical sepsis. Although the hyperdynamic response observed in septic patients undergoing resuscitation was not clearly elicited, this paradigm better mimics clinical sepsis compared with the commonly used endotoxin model. Thus, utilization of this paradigm may provide additional opportunities to explore mechanisms of sepsis and to examine novel therapeutics.

Endotoxin tolerance in rats: expression of TNF-alpha, IL-6, IL-10, VCAM-1 AND HSP 70 in lung and liver during endotoxin shock

Endotoxin can induce a state of tolerance against its own pathological effects, commonly referred to as endotoxin tolerance. This phenomenon has been found to be associated with reduced serum levels of cytokines such as TNF-alpha, IL-1, IL-6 and IL-10. In the present study the expression of TNF-alpha, IL-6, IL-10, the adhesion molecule VCAM-1 and the heat shock protein 70 was determined in vivo in lung and liver of LPS-tolerant and naive rats by means of semiquantitative RT-PCR after i.v. LPS injection. TNFalpha, IL-6, IL-10, HSP 70 and VCAM-1 were induced in lung and liver after LPS injection. In liver and lung of endotoxin-tolerant rats TNF-alpha and IL-6 were induced to a lower degree after LPS treatment when compared to non-tolerant controls. The LPS-induced IL-10 expression was also slightly attenuated in the lung of tolerant rats, but in the liver no differences between tolerant and non-tolerant animals were observed. HSP 70 and VCAM-1 were expressed after systemic LPS treatment in liver and lung. The degree of induction, however, was the same in tolerant and untreated controls. The presented data show that endotoxin tolerance is reflected by a reduced cytokine expression in lung and liver in vivo. On the other hand, levels of expression of the adhesion molecule VCAM-1 and the stress protein HSP 70 do not appear to be changed by endotoxin tolerance.

Cytokines and endotoxin removal by sorbents and its application in push-pull sorbent-based pheresis: the BioLogic-DTPF System

The BioLogic-DTPF System (DTPF) combines the Biologic-DT hemodiabsorption system (DT) in series with the Biologic PF push-pull pheresis system (PF) in which PF membranes separate plasma for direct contact between plasma proteins and the sorbents. Preliminary studies conducted in bovine serum albumin (BSA) solution and in bovine plasma allowed charcoal and silica to be evaluated as adsorbents for the PF module. Equilibrium binding experiments in BSA showed a high capacity of cytokine (IL-1 beta, TNF alpha) binding by powdered charcoal, 70-90 ng/g. Kinetic binding studies in bovine plasma revealed relatively quick adsorption of IL-1 beta and IL-6 by charcoal with the capacity range of 1.2-2.0 ng/g for tested cytokines (IL-1 beta and TNF alpha). Further laboratory studies with plasma have shown that powdered silica has an even greater binding capacity, up to 13 ng/g for TNF alpha depending upon particle size, and more rapid binding for all tested cytokines than powdered charcoal. Cholestyramine is a more efficient sorbent for removal of endotoxin than either charcoal or silica. In vitro tests using whole blood have demonstrated that the DTPF, with powdered charcoal as the sorbent, clears cytokines (TNF alpha, IL-1 beta, and IL-6) at 12.6-23.4 ml/min, bilirubin at 17.8-34.7 ml/min, and creatinine at 53.6-82.6 ml/min. The removal of some cytokines during the first clinical trial is also discussed.

Pro- and anti-inflammatory cytokines during acute severe pancreatitis: an early and sustained response, although unpredictable of death. Parisian Study Group on Acute Pancreatitis

OBJECTIVES

To define the pro- and anti-inflammatory cytokine response during acute severe pancreatitis and to evaluate its predictive value on hospital mortality.

DESIGN

Prospective, multicenter study.

SETTING

Nine multidisciplinary intensive care units (ICUs).

PATIENTS

Fifty patients with a diagnosis of acute pancreatitis who were admitted to the ICUs during a 14-month period were prospectively enrolled.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma concentrations of tumor necrosis factor (TNF)-alpha interleukin (IL)-1beta, IL-6, IL-10, IL-1 receptor antagonist (IL-1ra) were determined at the inclusion and during the ICU stay at Days 1, 3, 8, and 15. The patient population was analyzed by age, gender, previous health status, preexisting organ dysfunction, and type of acute pancreatitis. Physiologic variables were measured at inclusion and during ICU stay to calculate the new Simplified Acute Physiology Score II, the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and the number of organ system failures. Prognostic factors were determined by univariate methods and stepwise logistic regression analysis. Fifty patients were included, among whom 34 at the time of the ICU admission. Preinclusion symptom history was < or = 48 hrs in 78% of the patients. Eleven patients (22%) died during their hospital stay. At inclusion, 46 of 50 patients had elevated IL-6 serum levels (1512 +/- 635 pg/mL; normal value < 10 pg/mL), 36% of the patients had raised TNF-alpha concentrations, and all patients had an anti-inflammatory response (IL-10, 92 +/- 15 pg/mL [normal value < 10 pg/mL]; and/or IL-1ra, 7271 +/- 2530 pg/mL [normal value < 200 mg/mL]). During the follow-up period, pro- and anti-inflammatory cytokines remained elevated in at least 75% of the population. Positive correlations were found between inclusion pro- (IL-6) and anti-inflammatory cytokine concentrations at Day 1 (IL-10, IL-1ra; p < .0001) and between cytokines levels and the Simplified Acute Physiology Score II. While hospital mortality was linked to six factors in univariate analysis (age, cirrhosis, delay between hospitalization and ICU admission, severity of illness, and IL-10 and IL-6 plasma levels) when using stepwise logistic regression, only severity scoring indexes were predictive of death.

CONCLUSIONS

During acute severe pancreatitis, the pro- and anti-inflammatory cytokine response occurred early and persisted in the systemic circulation for several days. Although associated with the patient's severity at inclusion and outcome, cytokine plasma concentrations were unable to predict death accurately in individual patients. If confirmed, these results should be taken into consideration when selecting patients who are apt to benefit from new therapies aimed at modifying the immune inflammatory response.

Mediator-dependent effects of pentoxifylline on endothelium for transmigration of neutrophils

In the present study, we investigated the effects of the anti-inflammatory drug pentoxifylline (PTX) on activation of endothelial cells for enhanced adhesion and transmigration of neutrophils by lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF), interleukin-1 (IL-1) and granulocyte colony-stimulating factor (G-CSF). To evaluate the mechanism by which PTX exerts its effect, human umbilical vein endothelial cells (HUVEC) were pretreated with theophylline, 2'-O-dibutyryl-3', 5'-cyclic adenosine monophosphate (db cAMP), and 3-isobutyl-1-methylxanthine, respectively, prior to stimulation. Pretreatment of HUVEC with PTX significantly antagonized TNF-, IL-1-, and G-CSF-activated transmigration of neutrophils. Additive stimulatory effects of PTX were seen with LPS. With the exception of theophylline, all other test cAMP-raising agents stimulated transmigration in similar fashion to PTX. Upon stimulation with TNF or LPS, HUVEC produced IL-8 and PTX affected this process in opposing fashions, with inhibition of the effects of TNF and augmentation of those of LPS. These results demonstrate that PTX differentially affects mediator-induced activation of HUVEC. The present IL-8 dependent and cAMP-regulated augmentation of LPS-induced stimulation of transmigration is the first description of an additive effect of PTX with a pro-inflammatory agent.

Effect of pentoxifylline on survival and intestinal cytokine messenger RNA transcription in a rat model of ongoing peritoneal sepsis

OBJECTIVE

Septic animals receiving high-protein liquid diets have increased mortality and increased production of cytokines by the gut compared with animals receiving low-protein diets. The purpose of this study was to evaluate the ability of pentoxifylline to alter gut cytokine production in a rat model of prolonged acute peritonitis, to determine its effect on survival in such animals, and to determine whether alteration of gut cytokine production was associated with survival.

DESIGN

Prospective, randomized animal study.

SETTING

Research laboratory.

SUBJECTS

Male Lewis rats weighing between 250 and 300 g.

INTERVENTIONS

Anesthetized rats had placement of a gastrostomy, followed 1 wk later by implantation of a bacteria-filled osmotic minipump into the peritoneal cavity. Rats were fed a high-protein (20% total energy) enteral diet. Saline or pentoxifylline (5 or 20 mg/kg im) was administered daily beginning at the time of pump implantation.

MEASUREMENTS AND MAIN RESULTS

Septic rats fed the high-protein liquid diet and given pentoxifylline in a dose of 5 mg/kg/day demonstrated improved survival compared with saline-treated animals or animals given the high dose (20 mg/kg/day) of pentoxifylline (p< .05). Administration of pentoxifylline at 5 mg/kg/day also down regulated the production of IL-6 messenger RNA (mRNA) in liver and lipopolysaccharide binding protein mRNA in the liver and intestine of septic animals given the high-protein liquid diet.

CONCLUSION

Low-dose (but not high-dose) pentoxifylline administration reduced production of some, but not all, cytokines studied in the gut and liver in a rat model of acute peritonitis and this reduced production was associated with an improved survival in such animals.

Organ failure, infection, and the systemic inflammatory response syndrome are associated with elevated levels of urinary intestinal fatty acid binding protein: study of 100 consecutive patients in a surgical intensive care unit

BACKGROUND

Intestinal mucosal ischemia and subsequent barrier dysfunction have been related to the development of organ dysfunction and death in the critically ill. We hypothesized that urine concentrations of intestinal fatty acid binding protein (IFABP), a sensitive marker of intestinal ischemia, might predict the development of the systemic inflammatory response syndrome (SIRS) and organ dysfunction.

METHODS

One hundred consecutive critically ill patients were prospectively studied for the development of infectious complications, organ dysfunction, and SIRS. Urine was collected daily for measurement of IFABP.

RESULTS

A total of 58 males and 42 females (mean age, 56 years; range,16-85 years) were studied. Of these 100 patients, 40 patients developed complications and 5 patients developed SIRS. IFABP was significantly elevated in all patients with SIRS, and IFABP levels peaked an average of 1.4 days (range, 0-7 days) before the diagnosis of SIRS.

CONCLUSION

Elevated concentrations of urine IFABP correlated with the clinical development of SIRS. Studies to assess the utility of IFABP as a predictor of organ dysfunction and SIRS in the critically ill are warranted.

Effect of L-NAME, an inhibitor of nitric oxide synthesis, on plasma levels of IL-6, IL-8, TNF alpha and nitrite/nitrate in human septic shock

OBJECTIVES

We tested the effects of NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, on plasma levels of interleukin (IL) IL-6, IL-8, tumor necrosis factor-alpha (TNFalpha) and nitrite/nitrate (NO2-/ NO3-) in patients with severe septic shock.

DESIGN

Prospective clinical study.

SETTING

Surgical intensive care unit at a university hospital.

PATIENTS

11 consecutive patients with severe septic shock.

INTERVENTIONS

Standard hemodynamic measurements were made and blood samples taken at intervals before, during, and after a 12-h infusion of L-NAME 1 mg x kg(-1) x h(-1) for determination of plasma IL-6, IL-8, TNFalpha and NO2-/NO3- concentration.

MEASUREMENTS AND RESULTS

Patients with sepsis had increased plasma levels of IL-6, IL-8, TNFalpha and NO2-/NO3- (p < 0.05). Plasma levels of IL-6. IL-8, and NO2-/NO- were negatively correlated with systemic vascular resistance (r = -0.62, r = -0.65, and r = -0.78, respectively, all p < 0.05). Continuous infusion of L-NAME increased mean arterial pressure and systemic vascular resistance, with a concomitant reduction in cardiac output (all p < 0.01). No significant changes were seen in levels of plasma IL-6, IL-8, and NO-/NO3- during the 24-h observation period. Plasma levels of TNFalpha were significantly reduced during L-NAME infusion compared to baseline (p < 0.05).

CONCLUSIONS

NO plays a role in the cardiovascular derangements of human septic shock. Inhibition of NO synthesis with L-NAME does not promote excessive cytokine release in patients with severe sepsis.

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

OBJECTIVES

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

DESIGN

Prospective, observational study.

SETTING

Intensive care unit (ICU) of a university hospital.

PATIENTS

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

INTERVENTIONS

BAL and plasma sampling and ICU management.

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSION

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

Molecular basis of host-pathogen interaction in septic shock

Specific mechanisms of recognition of microbial products have been developed by host cells. Among these mechanisms, recognition of lipopolysaccharide of Gram-negative bacteria by CD14, a glycoprotein expressed at the surface of myelomonocytic cells, plays a major role. There is increasing evidence that CD14 also serves as a receptor for other microbial products including peptidoglycan of Gram-positive bacteria. A common theme is that CD14 represents a key molecule in innate immunity. Recognition of microbial products by host cells leads to cell activation and production of a large array of mediators that are necessary for the development of controlled inflammatory processes. When the activation process is out of control, such as in septic shock, these mediators can be detrimental to the host.

Pentoxifylline differentially regulates migration and respiratory burst activity of the neutrophil

TNF is produced by monocytes/macrophages in response to endotoxin, which may lead to septic shock. TNF stimulates neutrophil adherence, degranulation, and superoxide production, but inhibits neutrophil migration. A mitigating anti-inflammatory effect can be experimentally induced in septic shock by TNF blockers, such as pentoxifylline, and is also suggested for treatment with hrG-CSF. With regard to the combination of pentoxifylline and hrG-CSF, the purpose of this investigation was to explore whether and in what way the effects of hrG-CSF and pentoxifylline interact with each other in neutrophils. To this end, we studied the effects of pentoxifylline on TNF- and G-CSF-induced modulation of neutrophil chemotaxis and O2 release. TNF and G-CSF decreased directed migration of neutrophils to FMLP or IL-8. High-dose pentoxifylline (1 mM) was able to counteract the effect of TNF but not that of G-CSF on neutrophil migration. In the presence of pentoxifylline, TNF and G-CSF were unable to stimulate respiratory burst. In contrast, pre-exposure of cells to pentoxifylline followed by washing increased the priming effect of TNF or hrG-CSF on neutrophil respiratory burst activity. The methylxanthine derivative by itself showed no effect on spontaneous and fMLP-stimulated O2 release by neutrophils. Stimulation of neutrophil respiratory burst by pentoxifylline may not be detectable in the presence of pentoxifylline due to its known oxygen-radical scavenging function. Results suggest that by blocking the inflammatory action of TNF on neutrophils, pentoxifylline may diminish endothelial cell damage caused by inhibited neutrophil chemotaxis. On the other hand, since transiently present pentoxifylline may enhance the respiratory burst activity of TNF- or hrG-CSF-primed neutrophils, concomitant administration of pentoxifylline and hrG-CSF to patients with SIRS/sepsis might diminish beneficial effects of the latter and additional deleterious effects might occur.

Inflammatory mediators in BAL fluid as markers of evolving pneumonia in leukocytopenic patients

STUDY OBJECTIVES

Pneumonia during chemotherapy-induced leukocytopenia is a major cause of overall treatment failure in patients with hematologic malignancies. To improve outcome in these high-risk patients, early diagnosis of pulmonary infiltrates and institution of adequate antimicrobial treatment are mandatory. To identify patients with evolving pneumonia, we have prospectively studied the prognostic value of cytokine and complement measurements in early BAL samples from febrile leukocytopenic patients.

DESIGN

Prospective, comparative study.

SETTING

Hematology/oncology section of a university hospital.

PATIENTS

Twenty-one patients with leukocytopenia (WBC count < 1.000/microL) following cytoreductive chemotherapy for malignant disorders.

INTERVENTION

Early BAL sampling primarily for microbiologic diagnostic purposes.

MEASUREMENTS AND RESULTS

Proinflammatory cytokines and activated complement components were measured in the BAL aspirates and the results were related to the prevalence or subsequent evolution of overt pneumonia. Of the 21 patients studied, 10 patients presented with overt pneumonia at BAL sampling (group A), 5 patients developed objective signs of pneumonia 3 to 5 days after BAL (group B), and 6 patients remained free of pneumonia during follow-up (group C). In comparison with group C, patients in groups A and B both had distinctly elevated bronchoalveolar levels of tumor necrosis factor-alpha, interleukin-6, granulocyte colony-stimulating factor, C3a, and C5a.

CONCLUSIONS

Cytokine and complement determinations in early BAL samples may aid in the identification of febrile leukocytopenic patients with evolving pneumonia 3 to 5 days prior to the manifestation of diagnostic clinical and radiographic signs.

Augmentation of tumor necrosis factor-alpha-induced priming of fMet-Leu-Phe-stimulated neutrophils by pentoxifylline

Tumor necrosis factor-alpha (TNF) is reported to cause tissue damage via enhanced neutrophil (PMNL) degranulation, superoxide production and altered PMNL migration. We investigated the effect of pentoxifylline (PTX) on TNF-induced respiratory burst activity of the PMNL. Since PTX has been reported to influence TNF-induced PMNL functions, our studies focused on the effects of timing and duration of the presence of PTX on superoxide anion production by PMNL exposed to TNF. When PMNL are exposed to PTX prior to priming with TNF and triggering with fMLP, respiratory burst activity was significantly enhanced by PTX, whereas the stimulatory effect of TNF was completely blunted by the continuous presence of PTX. Since free radical-scavenging properties of PTX have only recently been identified and may explain inhibitory effects on TNF-induced respiratory burst reported in the literature, our data for the first time suggests additive priming actions of PTX and TNF on PMNL respiratory burst activity.