Interleukin 8 production in whole blood assays: Is interleukin 10 responsible for the downregulation observed in sepsis?

Can C-reactive protein be used as a surrogate marker of IL-6 in a broad array of clinical entities?

Background: C-reactive protein (CRP) is commonly performed, whereas cytokine testing is limited to research. Aims: To determine CRP correlation to cytokines IL-6, IL-1β and TNF-α. Results: Consecutive samples (n = 307) were collected over 24 h. Ninety-six patients (31%) had acute infections, and 23 patients (7.5%) had autoimmune or inflammatory disease presentations. A strong correlation between CRP and two IL-6 assays (r = 0.74 and r = 0.71; p < 0.001) was present. CRP did not correlate with IL-1β and TNF-α across the data set. Bacterial infection had a significantly higher CRP and IL-6 (p < 0.001), while only CRP was elevated in inflammatory and autoimmune diseases (p < 0.001). Discussion: CRP may be used as a surrogate marker of IL-6 levels in the routine diagnostic laboratories.

A primer on cytokines

Cytokines are pleiotropic polypeptides that control the development of and responses mediated by immune cells. Cytokine classification predominantly relies on [1] the target receptor(s), [2] the primary structural features of the extracellular domains of their receptors, and [3] their receptor composition. Functionally, cytokines are either pro-inflammatory or anti-inflammatory, hematopoietic colony-stimulating factors, developmental and would healing maintaining immune homeostasis. When the balance in C can form complex networks amongst themselves that may affect the homeostasis and diseases. Cytokines can affect resistance and susceptibility for many diseases and their availability in the host cytokine production and interaction is disturbed, immunopathogenesis sets in. Therefore, cytokine-targeting bispecific, and chimeric antibodies form a significant mode of immnuo-therapeutics Although the field has grown deep and wide, many areas of cytokine biology remain unknown. Here, we have reviewed these cytokines along with the organization, signaling, and functions through respective cytokine-receptor-families. Being part of the special issue on the Role of Cytokines in Leishmaniasis, this review is intended to be used as an organized primer on cytokines and not a resource for detailed discussion- for which a two-volume Handbook of cytokines is available- on each of the cytokines. Priming the readers on cytokines, we next brief the role of cytokines in Leishmaniasis. In the brief, we do not provide an account of each of the involved cytokines known to date, instead, we offer a temporal relationship between the cytokines and the progress of the infection towards the alternate outcomes- healing or non-healing- of the infection.

Microvesicle Subsets in Sepsis Due to Community Acquired Pneumonia Compared to Faecal Peritonitis

RATIONALE

Microvesicles (MV) act as a nonsoluble means of intercellular communication, with effector roles in disease pathogenesis and potentially as biomarkers. Previously, we reported that neutrophil MV expressing alpha-2-macroglobulin (A2MG) are protective in experimental sepsis and associate with survival in a small cohort of patients with sepsis due to community acquired pneumonia (CAP).

OBJECTIVES

To characterize MV profiles in sepsis due to CAP or fecal peritonitis (FP) and determine their relation to outcome. To investigate the effects of novel sepsis treatments (granulocyte-macrophage colony stimulating factor (GM-CSF) and interferon-υ (IFN-γ)) on MV production and functions in vitro.

METHODS

Flow cytometry analysis of MV identified the cell of origin and the proportion of A2MG expression in the plasma of patients with sepsis secondary to CAP (n = 60) or FP (n = 40) and compared with healthy volunteers (HV, n = 10). The association between MV subsets and outcome was examined. The ability of GM-CSF and IFN-γ on A2MG MV production from whole blood was examined together with the assessment of their effect on neutrophil and endothelial functions.

RESULTS

Circulating cell-derived and A2MG MV were higher in CAP compared with FP and HV. A2MG MV were higher in survivors of CAP, but not in FP. GM-CSF and IFN-γ enhanced A2MG MV production, with these MV eliciting pathogen clearance in vitro.

CONCLUSIONS

Plasma MV profiles vary according to the source of infection. A2MG MV are associated with survival in CAP but not FP. We propose specific MV subsets as novel biomarkers in sepsis and potential effector for some of the actions of experimental therapeutic interventions.

Endotoxin tolerance: is there a clinical relevance?

Beeson (1946) first defined endotoxin tolerance as a reduced endotoxin-induced fever following repeated injections of typhoid vaccine. Freudenberg and Galanos (1988) demonstrated that endotoxin tolerance that can protect against a lethal challenge of lipopolysaccharide (LPS) involves the participation of macrophages. Evans and Zuckerman (1991) reported a role for glucocorticoids in endotoxin tolerance. Prostaglandins, interleukin-(IL-)10, and transforming growth factor-β are other players of in vivo endotoxin tolerance. Dramatic reduction of plasma tumor necrosis factor (TNF) (Mathison et al. 1990) and other cytokines in response to LPS parallels endotoxin tolerance. The reduced capacity to produce TNF and other cytokines can be mimicked in vitro by pretreatment of monocytes or macrophages with LPS. It is not a specific phenomenon and can be induced by other agents or events. Cross-tolerance between LPS, TLR2 specific ligands, IL-1 and TNF has been regularly reported. A similar loss of LPS-reactivity has been repeatedly reported in leukocytes of septic patients and in patients with non-infectious systemic inflammation response syndrome (SIRS; e.g . surgery, trauma, cardiac arrest and resuscitation, etc.). Studies on cellular signaling within leukocytes from septic and SIRS patients reveal numerous alterations of the activation pathways reminiscent of those observed in endotoxin-tolerant cells. While endotoxin tolerance prevents severity of infections and ischemia-reperfusion damage, it has been suggested that the immune dysregulation observed in SIRS patients was associated with an enhanced sensitivity to nosocomial infections. In conclusion, in vitro and in vivo endotoxin tolerance, either experimental or due to clinical status, are similar but not identical.

Inflammatory cytokines and acute-phase proteins concentrations in the peripheral blood and uterus of cows that developed endometritis during early postpartum

The aim of the study was to evaluate the level of proinflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-6 [IL-6]), anti-inflammatory cytokine (interleukin-10 [IL-10]), and acute-phase proteins (haptoglobin [Hp] and serum amyloid A [SAA]) in serum and uterine washings in cows that developed endometritis during the early postpartum period. The study was carried out on 40 cows. The experimental group consisted of 20 cows with subclinical endometritis and the control group of 20 cows without endometritis. Analyses in both groups of cows were carried out at 5, 22, and 40 days postpartum (DPP). Experimental material consisted of the blood serum and uterine washings. The levels of the following cytokines: TNF-α, IL-6, IL-10 and acute-phase proteins: Hp and SAA were determined using ELISA. Our study reported that the levels of TNF-α, IL-6, IL-10, Hp, and SAA at 22 DPP were higher in cows with subclinical endometritis (P < 0.001). The levels of TNF-α (P = 0.01), IL-6 and IL-10 (P = 0.001), and Hp (P < 0.001) at 40 DPP were higher in cows with subclinical endometritis compared to healthy cows. The level of IL-10 in uterine washings at 5 DPP was higher (P = 0.001), whereas of SAA was lower (P = 0.01) in cows with subclinical endometritis. At 22 DPP, the levels of IL-6, IL-10, and Hp were higher (P < 0.001) in cows with endometritis. At 40 DPP, the level of TNF-α was lower, whereas these of IL-10 and Hp were elevated (P < 0.001) in cows with endometritis compared to healthy cows. The results indicate that the evaluation of the levels of cytokines and Hp in serum, but primarily in uterine washings, can be an important diagnostic indicator in cows that developed subclinical endometritis. High levels of IL-10 in cows with subclinical endometritis may contribute to the weakening of local resistance mechanisms of the uterus and lead to the persistence of the inflammation in the postpartum period. The present study also shows that the simultaneous examination of selected parameters of antagonistic interactions allows for better assessment of the current state of local immunity in the uterus.

Endogenous Tetrapyrroles Influence Leukocyte Responses to Lipopolysaccharide in Human Blood: Pre-Clinical Evidence Demonstrating the Anti-Inflammatory Potential of Biliverdin

Sepsis is associated with abnormal host immune function in response to pathogen exposure, including endotoxin (lipopolysaccharide; LPS). Cytokines play crucial roles in the induction and resolution of inflammation in sepsis. Therefore, the primary aim of this study was to investigate the effects of endogenous tetrapyrroles, including biliverdin (BV) and unconjugated bilirubin (UCB) on LPS-induced cytokines in human blood. Biliverdin and UCB are by products of haem catabolism and have strong cytoprotective, antioxidant and anti-inflammatory effects. In the present study, whole human blood supplemented with BV and without was incubated in the presence or absence of LPS for 4 and 8 hours. Thereafter, whole blood was analysed for gene and protein expression of cytokines, including IL-1β, IL-6, TNF, IFN-γ, IL-1Ra and IL-8. Biliverdin (50 μM) significantly decreased the LPS-mediated gene expression of IL-1β, IL-6, IFN-γ, IL-1Ra and IL-8 (P<0.05). Furthermore, BV significantly decreased LPS-induced secretion of IL-1β and IL-8 (P<0.05). Serum samples from human subjects and, wild type and hyperbilirubinaemic Gunn rats were also used to assess the relationship between circulating bilirubin and cytokine expression/production. Significant positive correlations between baseline UCB concentrations in human blood and LPS-mediated gene expression of IL-1β (R=0.929), IFN-γ (R=0.809), IL-1Ra (R=0.786) and IL-8 (R=0.857) were observed in blood samples (all P<0.05). These data were supported by increased baseline IL-1β concentrations in hyperbilirubinaemic Gunn rats (P<0.05). Blood samples were also investigated for complement receptor-5 (C5aR) expression. Stimulation of blood with LPS decreased gene expression of C5aR (P<0.05). Treatment of blood with BV alone and in the presence of LPS tended to decrease C5aR expression (P=0.08). These data indicate that supplemented BV inhibits the ex vivo response of human blood to LPS. Surprisingly, however, baseline UCB was associated with heighted inflammatory response to LPS. This is the first study to explore the effects of BV in a preclinical human model of inflammation and suggests that BV could represent an anti-inflammatory target for the prevention of LPS mediated inflammation in vivo.

HDAC6 regulates LPS-tolerance in astrocytes

Inflammatory tolerance is a crucial mechanism that limits inflammatory responses in order to avoid prolonged inflammation that may damage the host. Evidence that chronic inflammation contributes to the neuropathology of prevalent neurodegenerative and psychiatric diseases suggests that inflammatory tolerance mechanisms are often inadequate to control detrimental inflammation in the central nervous system. Thus, identifying mechanisms that regulate neuroinflammatory tolerance may reveal opportunities for bolstering tolerance to reduce chronic inflammation in these diseases. Examination of tolerance after repeated lipopolysaccharide (LPS) treatment of mouse primary astrocytes demonstrated that histone deacetylase (HDAC) activity promoted tolerance, opposite to the action of glycogen synthase kinase-3 (GSK3), which counteracts tolerance. HDAC6 in particular was found to be critical for tolerance induction, as its deacetylation of acetyl-tubulin was increased during LPS tolerance, this was enhanced by inhibition of GSK3, and the HDAC6 inhibitor tubacin completely blocked tolerance and the promotion of tolerance by inhibition of GSK3. These results reveal opposing interactions between HDAC6 and GSK3 in regulating tolerance, and indicate that shifting the balance between these two opposing forces on inflammatory tolerance can obliterate or enhance tolerance to LPS in astrocytes.

Whole Blood Leukocyte Mitogen Activated Protein Kinases Activation Differentiates Intensive Care Unit Patients With Systemic Inflammatory Response Syndrome and Sepsis

INTRODUCTION

We sought to determine whether leukocytes from intensive care unit (ICU) patients have altered ERK and p38 kinase activation and specifically if septic patients manifest changes of endotoxin (lipopolysaccharide [LPS]) tolerance. In vitro pretreatment of monocytes (Mono) with LPS induces LPS tolerance with impaired cytokine release and inhibition of ERK and p38 activation after LPS rechallenge.

HYPOTHESIS

We hypothesized that macrophage dysregulation, similar to that seen with in vitro LPS tolerance, occurs in critically ill patients with severe sepsis.

METHODS

Heparinized whole blood from 16 surgical ICU patients and 16 healthy controls was incubated for 15 minutes +/- 10 ng/mL LPS at 37 degrees C. Mono and neutrophil (polymorphonuclear leukocytes [PMN]) diphospho (active) ERK and p38 kinase activation were determined using flow cytometry with monoclonal antibodies. Results are expressed as mean +/- SEM of basal and percentage change (delta %) in positive cells (delta = LPS stimulated - basal). Chi2 test was used for statistics.

RESULTS

Basal ERK was seen in Mono from all groups, but delta % positive only increased in healthy subjects and systemic inflammatory response syndrome (SIRS) patients. No basal Mono or PMN p38 was seen in healthy controls, but LPS significantly activated p38 in both cell types. Mono from patients with sepsis, but not SIRS, had impaired ERK activation. Both PMN and Mono from patients with SIRS had low basal but high LPS-stimulated p38, whereas p38 activation was impaired in patients with sepsis.

CONCLUSION

Alterations in mitogen activated protein kinases (MAPK) activation are seen in ICU patients. Leukocytes of septic patients, but not those with SIRS, showed characteristics of LPS tolerance. Assessment of leukocyte MAPK activation may identify and differentiate patients with sepsis from those with SIRS.

Bench-to-bedside review: endotoxin tolerance as a model of leukocyte reprogramming in sepsis

Endotoxin tolerance is defined as a reduced responsiveness to a lipopolysaccharide (LPS) challenge following a first encounter with endotoxin. Endotoxin tolerance protects against a lethal challenge of LPS and prevents infection and ischemia-reperfusion damage. Endotoxin tolerance is paralleled by a dramatic reduction of tumor necrosis factor (TNF) production and some other cytokines in response to LPS. Endotoxin tolerance involves the participation of macrophages and mediators, such as glucocorticoids, prostaglandins, IL-10, and transforming growth factor-β. Endotoxin tolerance is accompanied by the up-regulation of inhibitory molecules that down-regulate the Toll-like receptor (TLR)4-dependent signaling pathway. Cross-tolerance between LPS and other TLR specific ligands, as well as IL-1 and TNF, has been regularly reported. A similar loss of LPS reactivity has been repeatedly reported in circulating leukocytes of septic patients and in patients with non-infectious systemic inflammation response syndrome (SIRS). Studies on cellular signaling within leukocytes from septic and SIRS patients reveal numerous alterations reminiscent of those observed in endotoxin tolerant cells. However, altered responsiveness to LPS of leukocytes from sepsis and SIRS patients is not synonymous with a global down-regulation of cellular reactivity. The term 'cellular reprogramming', which has been proposed to qualify the process of endotoxin tolerance, defines well the immune status of circulating leukocytes in septic and SIRS patients.

Parasite density and serum cytokine levels in Plasmodium vivax malaria in Turkey

We aimed to investigate the relationship between quantitative Plasmodium vivax parasitaemia and serum cytokine levels in a highly endemic region of Turkey, where such a relation has not been investigated before. Active screening was done in a total of 1316 people residing in 33 villages of Sanliurfa province, Turkey. The study population consisted of 79 consecutive patients with P. vivax malaria, and a control group included 89 healthy subjects. Thick blood smears were examined for malaria parasite and parasite count. Serum samples were analysed for IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10 and IL-12 by the ELISA method. Compared to controls, levels of pro-inflammatory cytokines, i.e. IL-1beta, IL-6 and IL-12, were significantly higher in patients with parasitaemia. There was a significant positive correlation between serum IL-10 and IL-12 levels and the parasite burden (r = 0.264, P = 0.024 and r = 0.264, P = 0.024, respectively). Serum IL-8 levels showed a significant negative correlation with parasite burden (r =-0.356, P = 0.002). There was a positive correlation between IL-8 levels and age, while the opposite was observed for IL-12. High fever was correlated with IL-6 and IL-10 levels. Compared to controls, patients with a parasite count greater than 5000/microL had a significantly higher IL-1beta and IL-10 levels (P < 0.05), while the difference was not significant for patients with a parasite count less than 1000/microL. Thus, we can conclude that pro-inflammatory response against P. vivax gains more importance during periods of increased parasite burden.

Improved diagnostic approaches to infection/sepsis detection

Sepsis is a major healthcare problem from the perspective of mortality and economics. Advances in diagnostic detection of infection and sepsis have been slow, but recent advances in both soluble biomarker detection and quantitative cellular measurements promise the availability of improved diagnostic techniques. Though the promise of cytokine measurements reaching clinical practice have not matured, procalcitonin levels are currently available in many countries and appear to offer enhanced diagnostic distinction between bacterial and viral etiologies. Cellular diagnostics is poised to enter clinical laboratory practice in the form of neutrophil CD64 measurements, which offer superior sensitivity and specificity to conventional laboratory assessment of sepsis. Neutrophil CD64 expression is negligible in the healthy state. However, it increases as part of the systemic response to severe infection or sepsis. The combination of cellular proteomics, as in the case of neutrophil CD64 quantification, and selected soluble biomarkers of the inflammatory response, such as procalcitonin or triggering receptor expressed on myeloid cells (TREM)-1, is predicted to remove the current subjectivity and uncertainty in the diagnosis and therapeutic monitoring of infection and sepsis.

Regulation of peritoneal and systemic neutrophil-derived tumor necrosis factor-alpha release in patients with severe peritonitis: role of tumor necrosis factor-alpha converting enzyme cleavage

OBJECTIVE

Polymorphonuclear neutrophil (PMN) influx and peritoneal tumor necrosis factor (TNF)-alpha production are key host defense mechanisms during peritonitis. The aim of this study was to explore the potential interactions between TNF-alpha production and TNF-alpha converting enzyme (TACE) expression by PMN in the blood and peritoneum of patients with severe peritonitis.

DESIGN

A prospective study.

SETTING

A surgical adult intensive care unit in a university hospital.

PATIENTS

A total of 29 consecutive immunocompetent patients with severe sepsis within 48 hrs of onset were enrolled and underwent laparotomy for a diffuse secondary peritonitis. Thirteen volunteers served as controls.

MEASUREMENTS

Blood and peritoneal fluid recovered during laparotomy were analyzed and compared for 1) soluble TNF-alpha, soluble L-selectin, and type I and II TNF-alpha receptor levels; 2) PMN membrane TNF-alpha, membrane L-selectin, and TACE expression (flow cytometry); and 3) TNF-alpha production by cultured PMN. Correlations between these forms of PMN-derived TNF-alpha and the severity of the peritonitis and patient's outcome were investigated.

MAIN RESULTS

Elevated soluble TNF-alpha levels in both plasma and peritoneal fluid from the patients were found, together with decreased expression of membrane TNF-alpha and TACE up-regulation at the PMN surface. Soluble L-selectin and type I and II TNF receptors were highly released, suggesting also the role of TACE. In contrast, the capacity of both blood and peritoneal PMN to synthesize TNF-alpha in vitro, in optimal conditions of stimulation (lipopolysaccharide + interferon-gamma), was impaired as compared with controls' blood PMN. Regulation of PMN-derived TNF-alpha was similar in the two compartments, but responses were more pronounced in the peritoneum. TACE up-regulation at the surface of blood-derived PMN correlated with the Sequential Organ Failure Assessment score and vital outcome.

CONCLUSION

These human data demonstrate that mTACE is up-regulated at the PMN surface during severe peritonitis. This finding could be related to a paracrine regulatory loop involving some TACE substrates such as TNF-alpha, L-selectin, and TNF receptors.

THE ANTI-INFLAMMATORY EFFECT OF DIAZOXIDE IN CORONARY ARTERY BYPASS GRAFTING

Many therapeutic strategies have been designed to suppress the inflammatory response in patients undergoing coronary artery bypass grafting (CABG). Pharmacological preconditioning with diazoxide is an alternative in effective cardioprotective strategies, but more evidence is required to show its effect on the inflammatory response. Forty patients with stable angina who were scheduled for isolated elective CABG operations were randomized into control and diazoxide (DZX) groups. In the DZX group, 1.5 mg/kg diazoxide was infused intravenously in 5 min followed by a 5-min washout before commencing the cardiopulmonary bypass. In the control group, placebo infusion was given similarly. Blood samples for cytokine measurement were collected from the radial artery and coronary sinus perioperatively, and hemodynamic data were recorded. Thirty-six patients fulfilled the data collection. Cardiac index (CI) increased in both groups over time as compared with baseline. In the DZX group, the increase of CI was greater than that in the control group (P = 0.002). Systemic and coronary sinus plasma levels of IL-6, IL-8, and IL-10 increased significantly after reperfusion in both groups as compared with baseline (P < 0.05). IL-6 and IL-8 both reached the peak value at 6 h after cardiopulmonary bypass. IL-10 reached peak level at 20 min after reperfusion in both groups. There was significantly higher IL-10 in DZX groups (P = 0.015). The ratios of IL-6 to IL-10 and IL-8 to IL-10 were significantly lower in DZX groups than in controls (P = 0.025 and P = 0.041 for each, respectively). Pharmacological preconditioning with DZX in CABG patients shifts the circulating inflammatory cytokine balance toward the anti-inflammatory direction.

Cytometric bead assay of cytokines in sepsis: A clinical evaluation

BACKGROUND

The clinical relevancy of an attractive new multiparametric method, cytometric beads assay (CBA), was evaluated for the monitoring of cytokines in sepsis.

METHODS

A total of 52 samples (26 patients) were simultaneously tested by CBA and chemiluminescence (IL-6, IL-8, IL-1beta, and TNFalpha) or ELISA (IL-10, IL-12 p40, IL-12 p70, and soluble TNFalpha-RI).

RESULTS

CBA standard curves were linear from 20-5,000 ng/L except for IL-1beta (40-5,000 ng/L). IL-6 and IL-8 were detected in 41 and 48 samples (44-5,000 ng/L and 22-5,000 ng/L), respectively, and out of range in six samples. IL-10 and IL-1beta were detected in 14 and 15 samples (21-1,548 ng/L and 29-582 ng/L), respectively. TNFalpha was rarely detected, and IL-12 p70 was never detected. Accuracy and repeatability were good (CV for IL-6 was 2.1-8.7%; for IL-8 3.7-5.3%; for IL-10 2.5-9.1%; for IL-12 5.2-6.5%; for IL-1 beta 4-12%; and for TNFalpha 3-19.3%). Reproducibility of four standard curves and 20 samples (-1.1 to +1.03%) was excellent between tests done at two- to six-week intervals. CBA values were correlated (r2 > 0.89; P < 0.001) with our reference methods, but were lower on CBA (TNFalpha 45% +/- 8; IL-6 49% +/- 7), probably due to interactions with patients' serum, as confirmed by spiking diluted standards in one patient's serum with end stage renal failure and high levels of TNF soluble receptor (i.e., TNFalpha levels 34 and 21%).

CONCLUSIONS

Finally, these results suggest that IL-6, IL-8, IL-1beta, and Il-10 are clinically promising for sepsis evaluation. However, sensitivity of TNFalpha has to be improved and IL-12 p70 should be replaced with more relevant parameters such as TNF-R, procalcitonin, or neopterin.

Lower levels of whole blood LPS-stimulated cytokine release are associated with poorer clinical outcomes in surgical ICU patients

BACKGROUND

In vitro pretreatment of human monocytes with lipopolysaccharide (LPS) induces "endotoxin tolerance" with blunted TNF and IL-6 release to rechallenge with LPS. The pro-inflammatory cytokines TNF and IL-6 are important mediators in sepsis. A high IL-6 concentration has been used as a marker of infection severity, but IL-6 may also have beneficial effects as an acute-phase protein. We sought to address two questions: (a) What is the relationship between TNF and IL-6 release? (b) Is the clinical outcome different for intensive care unit (ICU) patients with ex vivo characteristics of endotoxin tolerance (low levels of ex vivo LPS-stimulated cytokine release)?

MATERIALS AND METHODS

Heparinized whole blood was obtained from 62 surgical ICU patients and 15 control subjects and incubated for 3 h at 37 degrees C in the presence or absence of 10 ng/mL LPS. Concentrations of TNF and IL-6 were measured in plasma samples using an enzyme-linked immunosorbent assay (pg/mL). Clinical data on ICU length of stay (LOS), ventilator days, white blood cell count (WBC), and documented clinical infection were obtained by chart review. Outcome parameters for patients with low ex vivo LPS-stimulated cytokine release (low = IL-6 < 3000 pg/mL and TNF <2100 pg/mL) were compared to patients with Normal/High concentrations of cytokines.

RESULTS

Cytokines were essentially undetectable in ICU patients or controls without LPS stimulation, however a range of values was measured for LPS-stimulated release in both ICU patients (IL-6, 7847 +/- 857 pg/mL; TNF, 4390 +/- 457 pg/mL) and controls (IL-6, 7704 +/- 793 pg/mL; TNF, 6706 +/- 715 pg/mL). There were no differences in age between High/Normal concentrations of cytokines compared to the Low cytokine group, however there were significant differences in WBC, cytokine concentrations, ICU LOS, incidence of clinical infection, and mortality. The Low group also required an average of 6.9 more days of mechanical ventilation (p < 0.05). LPS-stimulated TNF release seemed to correlate better with the observed mortality than did IL-6 release.

CONCLUSION

The data suggest that ICU patients with characteristics of endotoxin tolerance (low LPS-stimulated cytokine release capacity) have significantly poorer clinical outcomes. Ex vivo LPS-stimulated whole blood cytokine production may be useful to identify ICU patients with severe sepsis.

Depressed interleukin-12-producing activity by monocytes correlates with adverse clinical course and a shift toward Th2-type lymphocyte pattern in severely injured male trauma patients

OBJECTIVE

To determine the effect of major trauma on the cytokine-producing activity of monocytes and CD4+ T cells in a homogeneous cohort of patients as well as to determine the relationship between monocyte and T-lymphocyte responses and clinical outcome.

SETTINGS

Surgical intensive care units of a trauma center and flow cytometry and experimental laboratories at a teaching hospital.

DESIGN

Prospective cohort clinical study with measurements of white cell cytokine-producing activity on days 2, 5, and 10 postinjury. The number of cytokine-producing CD14+ monocytes, CD4+, and CD8+ T cells were determined in whole blood using flow cytometry combined with the intracellular cytokine staining method. Basal and lipopolysaccharide-stimulated interleukin (IL)-12, tumor necrosis factor-alpha, IL-6, and IL-1alpha production by monocytes as well as basal and phorbol 12-myristate 13-acetate plus ionomycin-stimulated interferon-gamma, IL-4, and tumor necrosis factor-alpha production by T cells were determined on days 2, 5, and 10 postinjury and compared with similar measurements made in healthy control subjects.

PATIENTS

Twelve randomly selected black, male patients were enrolled in the study: mean injury severity score, 26; mean age, 35 yrs; mean Glasgow Coma Scale score, 13; systemic inflammatory response syndrome, 92%; sepsis, 42%; bronchial infection, 42%; and adult respiratory distress syndrome 25%.

MAIN RESULTS

After lipopolysaccharide stimulation, the number of IL-12-, tumor necrosis factor-alpha-, IL-1alpha-, and IL-6-producing CD14+ monocytes was 40% to 70% lower in trauma patients on postinjury days 2, 5, and 10 than in healthy control subjects. After phorbol 12-myristate 13-acetate stimulation, the number of IL-4-producing CD4+ cells increased three-fold in the trauma patients compared with healthy control subjects. In contrast, the number of interferon-gamma- or tumor necrosis factor-alpha-producing CD4+ and CD8+ T cells was not different between the patients and control subjects. The Th1/Th2 ratio was significantly lower in patients on all postinjury days than in the control subjects. A statistically significant inverse correlation was found between the number of IL-12-producing monocytes and IL-4-producing CD4+ T cells in trauma patients (p =.007, r2 =.47). This correlation was absent in control subjects. The degree of depressed capacity of monocyte IL-12 production on day 2 postinjury showed a statistically significant correlation with the development of adult respiratory distress syndrome, sepsis, or infections and also with the duration of systemic inflammatory response syndrome and sepsis.

CONCLUSIONS

Major trauma results in an early and marked decrease in monocyte cytokine-producing activity. The trauma-induced depression in IL-12 production by the mononuclear phagocyte system may promote T-cell commitment toward a Th2 pattern early after trauma. The appearance of the Th2 pattern is the result of elevated numbers of IL-4-producing cells without major alterations in T-cell interferon-gamma-producing capacity. The degree of alterations in monocyte and T-cell responses on day 2 postinjury correlates with the development of adverse clinical outcomes and the subsequent duration of the inflammatory response.

Lipopolysaccharide preconditioning and cross-tolerance: the induction of protective mechanisms for rat intestinal ileus

BACKGROUND & AIMS

Endotoxin elicits an inflammatory response within the intestinal muscularis and causes intestinal muscle dysfunction. Our aims were to investigate intestinal muscle recovery after a single or repeated lipopolysaccharide (LPS) injections. We also investigated the ability of LPS to induce cross-tolerance to postoperative ileus.

METHODS

Motility was measured in vivo and in vitro by transit and organ-bath techniques. Nuclear factor kappa-B, nuclear factor interleukin 6, and signal transducer and activator of transcription were quantified by using electrophoretic mobility shift assay, and tumor necrosis factor alpha, interleukin 6, inducible nitric oxide synthase, and cyclooxygenase 2 were measured with reverse-transcription polymerase chain reaction. Myeloperoxidase histochemistry for neutrophils was performed in jejunal muscularis whole mounts.

RESULTS

Endotoxin-induced suppression of in vitro muscle contractility temporally recovered over 7 days with a similar profile whether after a single dose or during the continuous daily injection of LPS. Functional adaptation to continuous LPS was reflected in a significant blunting of transcription factor activation and cytokine messenger RNA up-regulation compared with the naive LPS-stimulated muscularis. Preconditioning of the muscularis showed significant cross-tolerance to the functional, molecular, and leukocytic sequelae of intestinal manipulation.

CONCLUSIONS

The muscularis externa recovered and developed tolerance to endotoxin over 7 days, which conferred cross-tolerance to intestinal manipulation. Thus, preconditioning induces protective mechanisms to a subsequent insult within the muscularis externa.

Dexamethasone decreases the pro- to anti-inflammatory cytokine ratio during cardiac surgery

BACKGROUND

Cytokines regulate inflammation associated with cardiopulmonary bypass (CPB). Pro-inflammatory cytokines may cause myocardial dysfunction and haemodynamic instability after CPB, but the release of anti-inflammatory cytokines is potentially protective. We studied the effects of dexamethasone on pro- and anti-inflammatory cytokine responses during coronary artery bypass grafting surgery.

METHODS

Seventeen patients were studied: nine patients received dexamethasone 100 mg before induction of anaesthesia (group 1) and eight patients acted as controls (group 2). Plasma levels of tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-8, IL-10 and IL-4 were measured perioperatively.

RESULTS

TNF-alpha and IL-8 did not increase significantly in group 1 whereas they increased in group 2 to greater than preoperative values (P<0.05). IL-6 increased in both groups, with lower values in group 1 than in group 2 (P<0.05). IL-10 increased in both groups, with higher values in group 1 (P<0.05). IL-4 did not change in group 1 but decreased in group 2 compared with pre-induction values (P<0.05). After surgery, patients in group 2 had tachycardia, hyperthermia, a greater respiratory rate and higher pulmonary artery pressure, and a longer stay in the intensive care unit.

CONCLUSION

Dexamethasone given before cardiac surgery changes circulating cytokines in an anti-inflammatory direction. Postoperative outcome may be improved by inhibition of the systemic inflammatory response.

Age-related differences in cell-specific cytokine production by acutely ill Malawian patients

Age-related changes in human cell-specific cytokine responses to acute illness have not been well examined. We therefore evaluated age-related differences in T, B and natural killer (NK) peripheral blood lymphocyte cytokine responses of 309 acutely ill hospitalized people in Malawi, Africa, < 1 month-61 years of age. We used four-colour flow cytometry and performed Wilcoxon rank sum and Kruskal-Wallis tests, Pearson (rp) and Spearman (rs) correlations, and linear and logistic regression analyses to control for human immunodeficiency virus infection (HIV) status, the percentages of lymphocytes expressing CD4, and the nature of the acute infection. The percentages of CD8- and CD8+ T cells producing induced IL-8 decreased with age (rs = -0.44 and -0.53). The percentages of T cells producing TNF-alpha were higher, and the percentages producing IL-10 were lower, in those > or =13 than those < 13 years old (medians: 17.7 versus 10.5 and 1.4 versus 3.0, respectively). The percentages of CD8- T cells producing IFN-gamma were higher and stable in those > or =1 year old compared to infants (medians: 23.5 versus 10.4); the percentages of NK producing IFN-gamma were higher post-infancy and then declined to relatively low levels with increasing age. The percentages of T cells producing IL-2 were highest in those 5- <31 years old (median 5.6) and lowest in those > or =31 years old (median 1.9). The ratios of the percentages of T cells producing IL-4 to those producing IL-8 and to those producing IL-10 both increased with age. These data suggest that innate immunity, represented by NK IFN-gamma production, dominates in early life. A number of shifts occur after infancy and before adolescence, including a proinflammatory shift from IL-8 to TNF-gamma and a type 2 shift from IL-10 to IL-4 dominance. These findings suggest distinct age-related differences in the human response to acute illness and may be useful in directing future efforts at immunomodulatory therapies.

Cell-associated interleukin-8 in cord blood of term and preterm infants

To assess the effect of gestational age and labor on the interleukin-8 (IL-8) concentration in whole cord blood and serum, IL-8 levels were determined simultaneously in cord blood serum and lysate in 134 infants. Following the elimination of some of the samples due to exclusion criteria, the data for 99 uninfected infants (71 term and 28 preterm) and 9 infants with neonatal bacterial infection delivered either vaginally or by elective or emergency cesarean section were analyzed. The effects of labor and gestational age were tested by analysis of variance. IL-8 was not detectable in the serum of 25 infants, whereas IL-8 levels in whole blood were measurable in all of the samples. The median IL-8 conncentrations in whole cord blood lysate were 106 pg/ml (range, 20 to 415 pg/ml) in preterm infants and 176 pg/ml (range, 34 to 1,667 pg/ml) in term infants. In contrast to the IL-8 levels in serum, IL-8 levels in whole blood were reduced after ECS. Gestational age had no independent effect on the IL-8 concentrations in either serum or whole blood; these concentrations increased in infected infants after labor. We conclude that the neonatal proinflammatory response to labor stress was more evident in the concentrations of IL-8 in whole blood than in serum. The levels of IL-8 in whole-blood lysate reflect proinflammatory stimulation in neonates and may be a useful diagnostic tool for the early diagnosis of neonatal infection.

Endotoxin tolerance: A review

Endotoxin tolerance was initially described when it was observed that animals survived a lethal dose of bacterial endotoxin if they had been previously treated with a sublethal injection. In animal models, two phases of endotoxin tolerance are described, an early phase associated with altered cellular activation and a late phase associated with the development of specific antibodies against the polysaccharide side chain of Gram-negative organisms. Recently, there has been a tremendous resurgence of interest in the mechanisms responsible for altered responsiveness to bacterial endotoxin. Host immune cells, particularly macrophages and monocytes, that are exposed to endotoxin for 3 to 24 hrs are rendered "tolerant" and manifest a profoundly altered response when rechallenged with bacterial endotoxin or lipopolysaccharide. The "lipopolysaccharide-tolerant" phenotype is characterized by inhibition of lipopolysaccharide-stimulated tumor necrosis factor production, altered interleukin-1 and interleukin-6 release, enhanced cyclooxygenase-2 activation, inhibition of mitogen-activated protein kinase activation, and impaired nuclear factor-kappaB translocation. Human monocytes and macrophages can be induced to become tolerant, and there is increasing evidence that monocytic cells from patients with systemic inflammatory response syndrome and sepsis have many characteristics of endotoxin tolerance.

Cytokines and malaria parasitemia

The balance between pro- and antiinflammatory cytokines may be important in malaria presentation and outcome. Malaria tends to be more severe in children than in adults, presumably because partial immunity develops with age. However, the full nature of, and age-related differences in, anti-malarial immunity are unknown. We compared: (1) serum and cell-specific cytokines of patients with acute malaria to those of patients with other acute illnesses and to those of healthy adults and (2) the cytokine responses of parasitemic children and parasitemic adults. Flow cytometry was done on the peripheral blood mononuclear cells of 148 hospitalized children, 161 febrile hospitalized adults, and 20 healthy adults in Malawi, Africa, a malaria-endemic country. Serum cytokines were also assessed for 80 of these patients. Thirty-eight participants were parasitemic with Plasmodium falciparum. Serum interleukin (IL)-10 (an antiinflammatory, immunoregulatory, and type 2 cytokine) levels were higher in malaria patients than in other patients (medians 502 pg/mL vs 16 pg/mL, P = 0.002), and the percentages of various lymphocyte populations making IL-6 (a proinflammatory, type 2 cytokine regulating iron distribution) were lower in malaria patients than in other patients (e.g., for spontaneous production by children's CD8(+) T cells: medians 1.4% vs 33.1%, P = 0.004). For adult patients, the percentages of lymphocytes spontaneously making IL-4 (a type 2 cytokine) were significantly lower in those with malaria than in those without malaria (medians 0.9% vs 2.1%, P = 0.005). The percentages of monocytes spontaneously making IL-8 (a chemotactic, proinflammatory chemokine) were higher in parasitemic children than in parasitemic adults (medians 5.8% vs 1.7%, P = 0.003). A number of cellular proinflammatory, type 1 parameters were significantly higher in all children (with or without malaria) than in all adults; these included the percentages of various lymphocyte populations making IL-6, both IL-6 and interferon-gamma, or IL-8. These data support the importance of IL-10 in malaria parasitemia. Given the lack of an IL-4 (type 2) response, IL-10's primary role may be immunoregulatory rather than type 2 in nature. In this study, the immune response to malaria was more proinflammatory in children than in adults. This difference, if corroborated by other studies, could be related to malaria's greater severity in children.