Inhibition of the Defense System Stimulating Interleukin-12 Interferon-γ Pathway During Critical Illness

Effect of Heat-Treated Lactiplantibacillus plantarum nF1 on the Immune System Including Natural Killer Cell Activity: A Randomized, Placebo-Controlled, Double-Blind Study

Heat-treated Lactiplantibacillus plantarum nF1 (HT-nF1) increases immune cell activation and the production of various immunomodulators (e.g., interleukin (IL)-12) as well as immunoglobulin (Ig) G, which plays an important role in humoral immunity, and IgA, which activates mucosal immunity. To determine the effect of HT-nF1 intake on improving immune function, a randomized, double-blind, placebo-controlled study was conducted on 100 subjects with normal white blood cell counts. The HT-nF1 group was administered capsules containing 5 × 1011 cells of HT-nF1 once a day for 8 weeks. After 8 weeks of HT-nF1 intake, significant changes in IL-12 were observed in the HT-nF1 group (p = 0.045). In particular, the change in natural killer (NK) cell activity significantly increased in subjects with low secretory (s) IgA (≤49.61 μg/mL) and low NK activity (E:T = 10:1) (≤3.59%). These results suggest that HT-nF1 has no safety issues and improves the innate immune function by regulating T helper (Th)1-related immune factors. Therefore, we confirmed that HT-nF1 not only has a positive effect on regulating the body's immunity, but it is also a safe material for the human body, which confirms its potential as a functional health food ingredient.

Polyinosinic: polycytidylic acid induced inflammation enhances while lipopolysaccharide diminishes alloimmunity to platelet transfusion in mice

Introduction

Alloimmune responses against platelet antigens, which dominantly target the major histocompatibility complex (MHC), can cause adverse reactions to subsequent platelet transfusions, platelet refractoriness, or rejection of future transplants. Platelet transfusion recipients include individuals experiencing severe bacterial or viral infections, and how their underlying health modulates platelet alloimmunity is not well understood.

Methods

This study investigated the effect of underlying inflammation on platelet alloimmunization by modelling viral-like inflammation with polyinosinic-polycytidylic acid (poly(I:C)) or gram-negative bacterial infection with lipopolysaccharide (LPS), hypothesizing that underlying inflammation enhances alloimmunization. Mice were pretreated with poly(I:C), LPS, or nothing, then transfused with non-leukoreduced or leukoreduced platelets. Alloantibodies and allogeneic MHC-specific B cell (allo-B cell) responses were evaluated two weeks later. Rare populations of allo-B cells were identified using MHC tetramers.

Results

Relative to platelet transfusion alone, prior exposure to poly(I:C) increased the alloantibody response to allogeneic platelet transfusion whereas prior exposure to LPS diminished responses. Prior exposure to poly(I:C) had equivalent, if not moderately diminished, allo-B cell responses relative to platelet transfusion alone and exhibited more robust allo-B cell memory development. Conversely, prior exposure to LPS resulted in diminished allo-B cell frequency, activation, antigen experience, and germinal center formation and altered memory B cell responses.

Discussion

In conclusion, not all inflammatory environments enhance bystander responses and prior inflammation mediated by LPS on gram-negative bacteria may in fact curtail platelet alloimmunization.

Circulating growth/differentiation factor 15 is associated with human CD56bright natural killer cell dysfunction and nosocomial infection in severe systemic inflammation

Background

Systemic inflammation induced by sterile or infectious insults is associated with an enhanced susceptibility to life-threatening opportunistic, mostly bacterial, infections due to unknown pathogenesis. Natural killer (NK) cells contribute to the defence against bacterial infections through the release of Interferon (IFN) γ in response to Interleukin (IL) 12. Considering the relevance of NK cells in the immune defence we investigated whether the function of NK cells is disturbed in patients suffering from serious systemic inflammation.

Methods

NK cells from severely injured patients were analysed from the first day after the initial inflammatory insult until the day of discharge in terms of IL-12 receptor signalling and IFN-γ synthesis.

Findings

During systemic inflammation, the expression of the IL-12 receptor β2 chain, phosphorylation of signal transducer and activation 4, and IFN-γ production on/in NK cells was impaired upon exposure to Staphylococcus aureus. The profound suppression of NK cells developed within 24 h after the initial insult and persisted for several weeks. NK cells displayed signs of exhaustion. Extrinsic changes were mediated by the early and long-lasting presence of growth/differentiation factor (GDF) 15 in the circulation that signalled through the transforming growth factor β receptor I and activated Smad1/5. Moreover, the concentration of GDF-15 in the serum inversely correlated with the IL-12 receptor β2 expression on NK cells and was enhanced in patients who later acquired septic complications.

Interpretation

GDF-15 is associated with the development of NK cell dysfunction during systemic inflammation and might represent a novel target to prevent nosocomial infections.

Fund

The study was supported by the Department of Orthopaedics and Trauma Surgery, University Hospital Essen.

Consumption of dairy yogurt with the polysaccharide rhamnogalacturonan from the peel of the Korean citrus hallabong enhances immune function and attenuates the inflammatory response

The aim of this study was to investigate the impact of consuming dairy yogurt supplemented with rhamnogalacturonan (RG), a polysaccharide from the peel of the Korean citrus hallabong, on natural killer (NK) cell activity and circulating cytokine levels. A randomized, double-blind, placebo-controlled study was conducted on 120 nondiabetic and nonobese subjects. Over an eight-week period, the test group consumed one pack (150 mL) of dairy yogurt containing 50 mg of probiotics and 100 mg of hallabong peel polysaccharide (60% RG) each day, whereas the placebo group consumed the same product without the hallabong peel supplement. NK cell activity (%) was measured based on the ratios of the effector cells (E; peripheral blood mononuclear cells, PBMCs) from each participant relative to the target cells (T; K562 cells) at E : T ratios of 10 : 1, 5 : 1, 2.5 : 1, or 1.25 : 1. NK cell activities under all assay conditions and interleukin (IL)-12 and interferon (IFN)-γ levels were significantly increased in the test group at eight weeks compared to the baseline values, whereas the placebo group showed a significant increase only in NK cell activity at E : T = 1.25 : 1. The test group had significantly greater increases in the changes in serum NK cell activity at the E : T ratios of 10 : 1, 5 : 1, and 2.5 : 1 and in the increases in IL-12 and IFN-γ levels than were observed in the placebo group, after adjusting for baseline values. After eight weeks of treatment, significant reductions were found in IL-6 and IL-1β levels in both the placebo and test groups. The daily consumption of dairy yogurt supplemented with RG, a polysaccharide from the peel of the Korean citrus hallabong, enhanced NK cell function and attenuated pro-inflammatory cytokine levels (ClinicalTrials.gov: NCT02535663).

Early immune anergy towards recall antigens and mitogens in patients at onset of septic shock

The pathology of sepsis is typically characterized by an infection and excessive initial inflammation including a cytokine storm, followed by a state of immune suppression or paralysis. This classical view of a two peak kinetic immune response is currently controversially discussed. This study was a sub-study of the randomized clinical Trial SISPCT registered with www.clinicaltrials.gov (NCT00832039, Registration date: 29/01/2009). Blood samples from 76 patients with severe sepsis and septic shock were incubated for 48 h at 37 °C in vitro with bacterial or fungal recall-antigens or specific mitogen antigens within 24 hours of sepsis onset. Recall-antigen stimulation led to a severe dampening of normal cytokine release. This immunologic anergy was similarly observed after mitogen stimulation. Moreover, patients under hydrocortisone therapy or with lowered arterial oxygen tension had further reductions in cytokine levels upon B- and T-cell mitogen stimulation. This investigation reveals an early onset of immunoparalysis during sepsis. This immune incompetence in mounting an adequate response to further infections includes previously sensitized pathogens, as seen with recall-antigens. Also, the immune-suppressive role of hydrocortisone and low PaO₂ is highlighted. Aside from early broad-spectrum antimicrobial therapy, our findings reinforce the need for maximal immunological support and protection against further infections at the onset of sepsis.

Consumption of Dairy Yogurt Containing Lactobacillus paracasei ssp. paracasei, Bifidobacterium animalis ssp. lactis and Heat-Treated Lactobacillus plantarum Improves Immune Function Including Natural Killer Cell Activity

The aim of this study was to investigate the impact of consuming dairy yogurt containing Lactobacillus paracasei ssp. paracasei (L. paracasei), Bifidobacterium animalis ssp. lactis (B. lactis) and heat-treated Lactobacillus plantarum (L. plantarum) on immune function. A randomized, open-label, placebo-controlled study was conducted on 200 nondiabetic subjects. Over a twelve-week period, the test group consumed dairy yogurt containing probiotics each day, whereas the placebo group consumed milk. Natural killer (NK) cell activity, interleukin (IL)-12 and immunoglobulin (Ig) G1 levels were significantly increased in the test group at twelve weeks compared to baseline. Additionally, the test group had significantly greater increases in serum NK cell activity and interferon (IFN)-γ and IgG1 than placebo group. Daily consumption of dairy yogurt containing L. paracasei, B. lactis and heat-treated L. plantarum could be an effective option to improve immune function by enhancing NK cell function and IFN-γ concentration (ClinicalTrials.gov: NCT03051425).

Consumption of Dairy Yogurt Containing Lactobacillus paracasei ssp. paracasei, Bifidobacterium animalis ssp. lactis and Heat-Treated Lactobacillus plantarum Improves Immune Function Including Natural Killer Cell Activity

The aim of this study was to investigate the impact of consuming dairy yogurt containing Lactobacillus paracasei ssp. paracasei (L. paracasei), Bifidobacterium animalis ssp. lactis (B. lactis) and heat-treated Lactobacillus plantarum (L. plantarum) on immune function. A randomized, open-label, placebo-controlled study was conducted on 200 nondiabetic subjects. Over a twelve-week period, the test group consumed dairy yogurt containing probiotics each day, whereas the placebo group consumed milk. Natural killer (NK) cell activity, interleukin (IL)-12 and immunoglobulin (Ig) G1 levels were significantly increased in the test group at twelve weeks compared to baseline. Additionally, the test group had significantly greater increases in serum NK cell activity and interferon (IFN)-γ and IgG1 than placebo group. Daily consumption of dairy yogurt containing L. paracasei, B. lactis and heat-treated L. plantarum could be an effective option to improve immune function by enhancing NK cell function and IFN-γ concentration (ClinicalTrials.gov: NCT03051425).

Supplementation of fermented Maillard-reactive whey protein enhances immunity by increasing NK cell activity

Objective: The objective of this study was to investigate the impact of supplementation with fermented Maillard-reactive whey protein (F-MRP) on natural killer (NK) cell activity, circulating cytokines, and serum protein levels.

Dissociation of IFN-γ from IL-12 and IL-18 production during endotoxin tolerance

Endotoxin tolerance was induced in mice following one, two or three injections of low amounts of lipopolysaccharide (LPS) before a further LPS injection, and circulating cytokines were analyzed 1.5 h and 3 h after LPS challenge. Three different patterns of cytokine production were obtained. In a first group of cytokines, including tumor necrosis factor (TNF), interleukin-6 (IL-6) and gamma interferon (IFN-γ), the reduction of plasma peak levels was already significantly pronounced after one tolerizing injection of LPS. The second group of cytokines includes the CC chemokine KC, the CXC chemokine monocyte-chemo-attractant protein-1 (MCP-1) and IL-12. The plasma levels of these cytokines were modestly reduced, and the reduction was more pronounced with increasing numbers of tolerizing injections of LPS. The third group of cytokines includes IL-1β and IL-18, the levels of which 3 h after LPS challenge (i.e. at the peak timing) remained essentially similar to those of control mice and after 1.5 h were even enhanced. Altogether, these data illustrate that, in tolerized animals, in vivo regulation of cytokine production differs greatly among different mediators and that immunoparalysis is not a general state. Furthermore, despite the presence of large amounts of IL-12 and IL-18, IFN-γ was essentially suppressed in tolerized animals.

Review: Immunodepression in sepsis and SIRS assessed by ex vivo cytokine production is not a generalized phenomenon: a review

Sepsis and non-infectious systemic inflammatory response syndrome (SIRS) are paradoxically associated with an exacerbated production of cytokines, as assessed by their presence in biological fluids, and a diminished ability of circulating leukocytes to produce cytokine upon in vitro activation. In this review, we depict that the observed cellular hyporeactivity is not a global phenomenon and that some signalling pathways are unaltered and allow the cells to respond normally to certain stimuli. Furthermore, we illustrate that during sepsis and SIRS, cells derived from tissues are either fully responsive to ex vivo stimuli or even primed, in contrast to cells derived from hematopoietic compartments (blood, spleen, etc.) which are hyporeactive. In addition to cytokine production, nuclear factor-κB (NF-κB) status within leukocytes can be used as a useful marker of hypo- or hyper-reactivity. We illustrate that the immune-depression reported in sepsis and SIRS patients, often revealed by a diminished capacity of leukocytes to respond to lipopolysaccharide, is not a generalized phenomenon and that SIRS is associated with a compartmentalized responsiveness which involves either anergic or primed cells.

Hyporesponsiveness in leukocytes in sepsis: in vitro models reveal paradoxical effects of IL-10

Sepsis syndrome is linked with a systemic inflammatory response syndrome (SIRS). This severe inflammation is associated with an immune suppression as illustrated by the reduced capacity of circulating leukocytes to produce cytokines in response to in vitro activation. Non-infectious SIRS such as trauma, burn, hemorrhage or major surgery is also associated with a suppression of the immune system. This phenomenon has been recently termed CARS for compensatory anti-inflammatory response syndrome. We report in vitro experiments which suggest that a well-known anti-inflammatory cytokine, namely IL-10, may, in certain experimental conditions, prime the leukocytes finally leading to an increased cytokine production. We discuss the relevance of this in vitro model to the in vivo situations where immune suppression is limited to the blood compartment (or the hematopoietic organs) whereas, in inflammatory foci within the tissues, cytokine production is increased. Our data suggest that IL-10 may be a causative agent of concomitantly occurring SIRS and CARS.

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.

Interferon-γ counteracts reduced endotoxin responsiveness of whole blood following trauma and cardiopulmonary bypass

Accidental as well as surgical trauma has been reported to cause reduced endotoxin responsiveness of blood in terms of cytokine production. In this study, the effect of interferon-γ (IFN-γ) on tumour necrosis factor-α (TNF-α)-producing capacity of whole blood after severe trauma and cardiac surgery was investigated. Blood samples of severely injured patients were collected at the first day after trauma and of cardiac surgery patients before, 4 h and 2 days after cardiopulmonary bypass (CPB). The blood samples were incubated with INF-γ (0—100 U/ml) for 20 h and subsequently lipopolysaccharide (LPS)-induced TNF-α production was determined. Compared to healthy donors, LPS-induced TNF-α production was significantly reduced in blood cultures of trauma patients on day 1 after trauma and 4 h after CPB. Pre-incubation with IFN-γ in vitro increased endotoxin-induced TNF-α production in volunteers' and all patients' blood specimens in a dose-dependent manner. IFN-γ prompted an elevation of cytokine synthesis in CPB patients' blood which equalled that of volunteers, whereas it caused a lower rise in TNF-α production in blood of multiply injured patients, reaching levels of untreated donors only after incubation with 100 U/ml IFN-γ. These experiments show that hyporesponsiveness of whole blood induced by trauma or cardiac surgery with CPB is not irreversible, but can be counteracted by the immunostimulant IFN-γ. IFN-γ, therefore, could be applied clinically in trauma patients or after cardiac surgery to prevent or to resolve infection complications.

Protective role of nuclear factor erythroid 2-related factor 2 in the hemorrhagic shock-induced inflammatory response

Hemorrhagic shock (HS) following trauma or major surgery significantly contributes to mortality. However, the mechanisms through which HS activates the inflammatory response are not yet fully understood. Nuclear factor-erythroid 2 (NF-E2) p45-related factor-2 (Nrf2), a bZIP transcription factor, is a master regulator of robust cytoprotective defenses. The present study investigated the role of Nrf2 in the pathophysiology of HS. Nrf2 expression in peripheral leukocytes obtained from patients with surgery-associated hemorrhage subjected to resuscitation treatment (termed HS patients) or healthy donors was examined by RT-qPCR. A marked increase in Nrf2 expression was detected in the leukocytes obtained from the HS patients, which indicates a correlation between Nrf2 expression and the development of HS. Wild-type (WT; Nrf2^+/+) and Nrf2-deficient [Nrf2^−/− or Nrf2-knockout (KO)] mice were subjected to surgery to induce HS. Systemic inflammation was significantly elevated in the Nrf2-KO mice compared with the WT mice following HS, as assessed by an increase in serum cytokine levels [interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-1β], as well as high-mobility group box 1 protein (HMGB1) expression. The Nrf2-KO mice exhibited more severe lung and liver injury following HS as evidenced by increased tissue damage, increased myeloperoxidase (MPO) activity and the increased production of pro-inflammatory cytokines. Additionally, Nrf2 deficiency augmented cytokine production induced by the exposure of peritoneal mouse macrophages to lipopolysaccha-ride (LPS) following HS. Taken together, these results suggest that Nrf2 is a critical host factor which limits immune dysregulation and organ injury following HS.

Invasive Surgery Impairs the Regulatory Function of Human CD56 bright Natural Killer Cells in Response to Staphylococcus aureus. Suppression of Interferon-γ Synthesis

Major surgery increases the risk for infectious complications due to the development of immunosuppression. CD56^bright NK cells play a key role in the defense against bacterial infections through the release of Interferon (IFN) γ upon stimulation with monocyte-derived Interleukin (IL) 12. We investigated whether invasive visceral surgery interferes with the IFN-γ synthesis of human NK cells in response to Staphylococcus aureus. In a prospective pilot study, peripheral blood mononuclear cells (PBMC) were isolated from 53 patients before and 1 to 7 d after elective visceral surgery. The release of IL-12 and IFN-γ from PBMC upon exposure to S. aureus in vitro was quantified. The expression of the IL-12 receptor β1 chain on the surface, the phosphorylation of signal transducer and activator of transcription (STAT) 4, and the synthesis of IFN-γ on/in individual CD56^bright NK cells were investigated using flow cytometry. The modulatory effect of IL-12 on the S. aureus-induced IFN-γ production in CD56^bright NK cells was analyzed. The IFN-γ secretion from purified CD56^bright NK cells was quantified after stimulation with IL-12 and IL-18. After surgery, CD56^bright NK cells among total PBMC were impaired in the release of IFN-γ for at least 5 d. Likewise, the IL-12-induced release of IFN-γ from purified CD56^bright NK cells was abolished. Upon stimulation with S. aureus, PBMC secreted less IL-12 but supplementation with recombinant IL-12 did not restore the capacity of CD56^bright NK cells to produce IFN-γ. CD56^bright NK cells displayed reduced levels of the IL-12Rβ1 chain whereas the phosphorylation of STAT4, the key transcription factor for the Ifng gene was not diminished. In summary, after invasive visceral surgery, CD56^bright NK cells are impaired in S. aureus-induced IFN-γ production and might contribute to the enhanced susceptibility to opportunistic infections.

Major surgical trauma differentially affects T-cells and APC

Macrophages have been reported to initiate immunosuppression following trauma and hemorrhage, and recent experimental studies suggest a pivotal role of T-cells in maintaining immunosuppression. The aim of the present study was to investigate the interaction of APC and T-cells in humans following major surgery. First, APC and T-cells from 14 surgical patients were isolated, counted and characterized by their specific surface marker profile 2 and 24 h postoperatively. Then, these cells were co-incubated with cells of the other type, which had been isolated pre-operatively. Chemokine secretion from pre-operative cells as measured by enzyme immunoassay served as a bioassay for the function of the stimulating postoperative cells. CD3+ T-cells and surface marker CD28 were markedly suppressed postoperatively, while CD3+CD25+CD127−Tregs were not suppressed. CD14+APC counts were increased with the most significant increase observed in CD14+HLA-DR− myeloid-derived suppressor cells. In co-cultures, APC showed increased postoperative secretion of TNF-α and IL-6 independently of whether they had been co-incubated with pre- or postoperative T-cells. T-cells incubated with CD14+ cells 2 h postoperatively secreted diminished amounts of IFN-γ. The results of the study suggest that T-cells play a pivotal role in mediating immunosuppression after major abdominal surgery.

Hematopoietic stem-progenitor cells restore immunoreactivity and improve survival in late sepsis

Sepsis progresses from an early/acute hyperinflammatory to a late/chronic hypoinflammatory phase with immunosuppression. As a result of this phenotypic switch, mortality in late sepsis from persistent primary infection or opportunistic new infection often exceeds that in acute sepsis. Emerging data support that persistence of the hypoinflammatory (hyporesponsive) effector immune cells during late sepsis might involve alterations in myeloid differentiation/maturation that generate circulating repressor macrophages that do not readily clear active infection. Here, we used a cecal ligation and puncture (CLP) murine model of prolonged sepsis to show that adoptive transfer of CD34(+) hematopoietic stem-progenitor cells after CLP improves long-term survival by 65%. CD34(+) cell transfer corrected the immunosuppression of late sepsis by (i) producing significantly higher levels of proinflammatory mediators upon ex vivo stimulation with the Toll-like receptor 4 (TLR4) agonist lipopolysaccharide, (ii) enhancing phagocytic activity of peritoneal macrophages, and (iii) clearing bacterial peritonitis. Improved immunity by CD34(+) cell transfer decreased inflammatory peritoneal exudate of surviving late-sepsis mice. Cell tracking experiments showed that the transferred CD34(+) cells first appeared in the bone marrow and then homed to the spleen and peritoneum. Because CD34(+) cells did not affect the early-phase hyperinflammatory response, it is likely that the newly incorporated pluripotent CD34(+) cells differentiated into competent immune cells in blood and tissue, thereby reversing or replacing the hyporesponsive endotoxin-tolerant cells that occur and persist after the initiation of early sepsis.

Flow cytometric analysis of peripheral blood dendritic cells in patients with severe sepsis

BACKGROUND

Dendritic cells (DC) play a key role in cell-mediated immunity. We aimed to analyse the number and function of peripheral blood (PB) myeloid and plasmacytoid DC (mDC/pDC) in patients with severe sepsis.

METHODS

Twenty-six septic patients, 20 surgical patients (abdominal aortic aneurysm) and 20 healthy controls were enrolled in this prospective study.

RESULTS

At day 1 (enrollment in the study), septic patients showed in comparison with healthy controls, decreased mDC (P < 0.001) and increased pDC (P = 0.03), resulting in a reduction of the mDC/pDC ratio (P < 0.001). Surgery induced a decrease in both mDCs and pDCs level, without modification of mDC/pDC ratio. Septic patients included 15 survivors and 11 nonsurvivors. At day 1 no significant difference was found in mDC between the two groups, while pDCs were significantly higher in nonsurvivors (P = 0.03). At the outcome, mDC were selectively increased with respect to day 1 in survivors (P = 0.001), while no significant differences were observed as far as pDC count is concerned in both groups. Sorted DC from septic patients showed in comparison with healthy controls, reduced levels of HLA DR (P < 0.001), CD11c (P < 0.001), CD83 (P = 0.006) and of costimulatory molecule CD86 (P = 0.003); an up-regulation of chemokine receptor CXCR4 (P = 0.031) and increased apoptosis (P < 0.001).

CONCLUSIONS

Sepsis has a profound effect on PB DC compartment. These alterations appear to be sepsis-specific. Increased apoptosis and alteration of migration and trafficking mechanism may be involved in DC compartment modification. DC alterations could contribute to sepsis-mediated immunoparalysis.

Human monocytes tolerant to LPS retain the ability to phagocytose bacteria and generate reactive oxygen species

Tolerance to lipopolysaccharide (LPS) occurs when animals or cells exposed to LPS become hyporesponsive to a subsequent challenge with LPS. This mechanism is believed to be involved in the down-regulation of cellular responses observed in septic patients. The aim of this investigation was to evaluate LPS-induced monocyte tolerance of healthy volunteers using whole blood. The detection of intracellular IL-6, bacterial phagocytosis and reactive oxygen species (ROS) was determined by flow cytometry, using anti-IL-6-PE, heat-killed Staphylococcus aureus stained with propidium iodide and 2',7'-dichlorofluorescein diacetate, respectively. Monocytes were gated in whole blood by combining FSC and SSC parameters and CD14-positive staining. The exposure to increasing LPS concentrations resulted in lower intracellular concentration of IL-6 in monocytes after challenge. A similar effect was observed with challenge with MALP-2 (a Toll-like receptor (TLR)2/6 agonist) and killed Pseudomonas aeruginosa and S. aureus, but not with flagellin (a TLR5 agonist). LPS conditioning with 15 ng/mL resulted in a 40% reduction of IL-6 in monocytes. In contrast, phagocytosis of P. aeruginosa and S. aureus and induced ROS generation were preserved or increased in tolerant cells. The phenomenon of tolerance involves a complex regulation in which the production of IL-6 was diminished, whereas the bacterial phagocytosis and production of ROS was preserved. Decreased production of proinflammatory cytokines and preserved or increased production of ROS may be an adaptation to control the deleterious effects of inflammation while preserving antimicrobial activity.

The potential role of T-cells and their interaction with antigen-presenting cells in mediating immunosuppression following trauma-hemorrhage

OBJECTIVE

Trauma-hemorrhage results in depressed immune responses of antigen-presenting cells (APCs) and T-cells. Recent studies suggest a key role of depressed T-cell derived interferon (IFN)-g in this complex immune cell interaction. The aim of this study was to elucidate further the underlying mechanisms responsible for dysfunctional T-cells and their interaction with APCs following trauma-hemorrhage.

DESIGN

Adult C3H/HeN male mice were subjected to trauma-hemorrhage (3-cm midline laparotomy) followed by hemorrhage (blood pressure of 35 +/- 5 mmHg for 90 min and resuscitation) or sham operation. At 24 h thereafter, spleens were harvested and T-cells (by Microbeads) and APCs (via adherence) were Isolated. Co-cultures of T-cells and APCs were established for 48 h and stimulated with concanavalin A and lipopolysaccharide. T-Cell specific cytokines known to affect APC function (i.e. interleukin(IL)-2, IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF)) were measured in culture supernatants by Multiplex assay. The expression of MHC class II as well as co-stimulatory surface molecules on T-cells and APCs was determined by flow cytometry.

RESULTS

The release of IL-4 and GM-CSF by T-cells was suppressed following trauma-hemorrhage, irrespective of whether sham or trauma-hemorrhage APCs were present. Antigen-presenting cells from animals subjected to trauma-hemorrhage did not affect T-cell derived cytokine release by sham T-cells. In contrast, T-cells from trauma-hemorrhage animals depressed MHC class II expression of CD11c(+) cells, irrespective of whether APCs underwent sham or trauma-hemorrhage procedure. Surprisingly, co-stimulatory molecules on APCs (CD80, CD86) were not affected by trauma-hemorrhage.

CONCLUSIONS

These results suggest that beside IFN-g other T-cell derived cytokines contribute to immunosuppression following trauma-hemorrhage causing diminished MHC II expression on APCs. Thus, T-cells appear to play an important role in this interaction at the time-point examined. Therapeutic approaches should aim at maintenance of T-cell function and their interaction with APCs to prevent extended immunosuppression following trauma-hemorrhage.

Pancreatic stone protein is highly increased during posttraumatic sepsis and activates neutrophil granulocytes

OBJECTIVES

The level of pancreatic stone protein/regenerating protein (PSP/reg), a secretory protein produced in the pancreas, increases dramatically during pancreatic disease. However, after stress (e.g., anesthesia), PSP/reg levels are increased transiently in animals without pancreatic injury. Therefore, we aimed to determine whether PSP/reg is an acute-phase protein after nonpancreatic trauma.

PATIENTS

Eighty-three polytraumatic patients without pancreatic damage.

MEASUREMENTS AND MAIN RESULTS

We compared serum PSP/reg levels from polytraumatic patients without pancreatic damage with those in healthy controls (n = 38). C-reactive protein, interleukin-6, procalcitonin, and leukocyte numbers were also compared. The expression of CD62L and CD11b on neutrophils after exposure to PSP/reg was analyzed by flow cytometry. Thirty-three patients (39%) developed sepsis, 32 (38%) had local infections, and 18 (21%) had no infections. At admission, PSP/reg serum levels (10.2 [6.2-14.5] ng/mL; median [interquartile range]) were comparable with those in healthy controls (10.4 [7.5-12.3] ng/mL). During hospital stay, PSP/reg levels were elevated significantly in patients with sepsis (146.4 ng/mL) and in patients with infections (111.4 ng/mL) compared with patients without infections (22.8 ng/mL). Furthermore, binding of fluorescein isothiocyanate-labeled recombinant PSP/reg to human neutrophils was demonstrated. Recombinant PSP/reg elicited a dose-dependent shedding of L-selectin (CD62L) and upregulation of beta2-integrin (CD11b) in neutrophils, which indicates that PSP/reg activates neutrophils.

CONCLUSIONS

We conclude that PSP/reg is up-regulated in blood after trauma, and the PSP/reg level is related to the severity of inflammation. Furthermore, PSP/reg binds to and activates neutrophils. Therefore, PSP/reg might be an acute-phase protein that could serve as a marker for posttraumatic complications.

Effect of chromium on the level of IL-12 and IFN-gamma in occupationally exposed workers

Chromium may affect humoral and cellular immunity, acting on T lymphocytes as well as on granulocytes and monocytes cells. Cytokines play an important role in the immune balance. In this study, the level of IL-12 and IFN-gamma were evaluated in the sera and PHA/LPS stimulated culture supernatant of human PBMCs of healthy volunteers and occupationally exposed chromium workers. All the workers were highly exposed to chromium having mean of 104.65+/-77.21 microg/dL (range 23.7-316.8 microg/dL). A suspension of exposed and unexposed human PBMC (0.5x10(6) cells/ml) prepared and cultured in RPMI-1640 supplemented with 10% FCS for 18 h in the presence or absence of LPS (10 ng/ml) which used for stimulation of IL-12 and IFN-gamma. The level of IL-12 and IFN-gamma were evaluated in the sera samples as well as LPS stimulated and unstimulated culture supernatant of h-PBMCs of chromium exposed workers. In these chromium exposed workers the level of IL-12 was 433.66+/-197.49 pg/ml and 983.45+/-330.99 pg/ml in LPS stimulated culture supernatant of normal individuals and highly chromium exposed workers, which was significant (P<0.05). Although the level of IL-12 was (78.61+/-61.03 pg/ml to 146.52+/-46.37 pg/ml) elevated in unstimulated culture supernatant of h-PBMCs of chromium exposed individuals as compared to control, but it was not significant. This observation also suggests that a significant increase in IFN-gamma production in LPS stimulated and unstimulated culture supernatant of h-PBMCs of chromium exposed workers as compared to control. However, IFN-gamma level have a significant positive correlation between blood chromium level (r=0.833, t=6.3872, P 0.05) and exposure time (in years) (r=0.8916, t=8.3540, P 0.05) of the occupationally exposed workers.

Discrete Toll-like receptor agonists have differential effects on alloimmunization to transfused red blood cells

BACKGROUND

Factors influencing alloimmunization to transfused red blood cells (RBCs) are not well understood. Utilizing a murine model, we have recently reported that RBC alloimmunization is enhanced by recipient treatment with viral-like polyinosinic polycytidylic acid (poly(I:C)). To determine whether a different subtype of inflammation also enhances RBC alloimmunization, we investigated the effects of the bacterial endotoxin lipopolysaccharide (LPS) on alloimmunization.

STUDY DESIGN AND METHODS

Mice were treated with poly(I:C) or LPS; in select experiments, the precursor frequency of naïve antigen-specific CD4+ T cells was increased using T cells from T-cell receptor transgenic mice. Recipients were transfused with leukoreduced RBCs expressing the membrane-bound hen egg lysozyme (mHEL) antigen, and alloimmunization was measured by anti-HEL immunoglobulin G responses using enzyme-linked immunosorbent assay and flow cytometric cross-match. Costimulatory molecule expression was examined on antigen-presenting cells (APCs) by flow cytometry.

RESULTS

Increased expression of costimulatory molecules on APCs was seen after treatment with either poly(I:C) and LPS. In contrast to the enhancement of RBC alloimmunization observed after treatment with poly(I:C), LPS not only failed to enhance but also actively suppressed alloimmunization, even in the presence of increased mHEL-specific CD4+ T cells (p < 0.001 LPS vs. control).

CONCLUSIONS

These data demonstrate that the regulation of RBC alloimmunization by inflammatory stimuli is complex, including enhancement by a viral-like stimulus and suppression by a bacterial-type stimulus. The mechanism(s) are unlikely to involve variation in the costimulatory molecules studied, because only subtle differences on APCs were observed after treatment with poly(I:C) and LPS.

"Host tissue damage" signal ATP impairs IL-12 and IFNgamma secretion in LPS stimulated whole human blood

OBJECTIVE

Critical illness is associated with tissue damage, inflammation and the development of immune dysfunction. Leukocyte reprogramming occurs leading to insufficient production of pro-inflammatory cytokines upon subsequent stimulation. Cellular nucleotides released during tissue damage act via purinergic receptors to modulate immune function. We hypothesized that extracellular nucleotides in concentrations similar to those found near injured and ischemic tissues will modulate cytokine secretion.

DESIGN AND PARTICIPANTS

Bench study in 28 healthy human volunteers using standardized lipopolysaccharide (LPS) stimulated ex vivo whole blood cultures (ILCS).

SETTING

The Nepean Hospital Laboratories, University of Sydney.

INTERVENTIONS

Nucleotides ATP, ADP and other P2 purinergic receptor agonists ATPgammaS, BzATP, UTP and P1 agonist CV1808 were injected into the ILCS, and cultured for 6, 12 and 24 h as indicated.

MEASUREMENTS AND RESULTS

ATP (100 muM) reduced the LPS stimulated secretion of TNFalpha at 6 and 12 h, as well as IL-12(p70) and IFNgamma at 24 h of incubation. ADP, ATPgammaS, BzATP, and CV1808, but not UTP displayed IL-12(p70) and IFNgamma reducing effect similar to ATP. Higher ATP concentration (500 muM) had even more pronounced immunosuppressive effect. Nucleotides had variable effect on stimulated IL-10 secretion.

CONCLUSIONS

ATP and ADP at high-micromolar concentrations reduce secretion of the main Th1 cytokines TNFalpha, IL-12(p70) and IFNgamma in LPS stimulated human blood. As immune dysfunction associated with critical illness is characterized by decreased TNFalpha, IL-12 and IFNgamma production by leukocytes, extracellular nucleotides might contribute to its pathogenesis [corrected]

Heat shock factor 1 inhibits nuclear factor-kappaB nuclear binding activity during endotoxin tolerance and heat shock

RATIONALE

Sepsis, endotoxin tolerance, and heat shock (HS) all display down-regulation of innate immunity. We hypothesize that HS factor 1 (HSF-1) induces competitive inhibition of nuclear factor-kappaB (NF-kappaB)-induced signal transduction in both endotoxin tolerance and HS.

OBJECTIVES

We compared endotoxin tolerance and HS in RAW 264.7 cells. We transfected cells with an HS protein 70 (HSP70) plasmid to test whether HSP70 is the mediator of HS-induced NF-kappaB inhibition. We studied the effects of endotoxin stimulation and HS, both separately and together, on "wild-type" cells, cells transfected with the HSP70 plasmid, and cells transfected with vehicle.

FINDINGS

Heat shock protein 70 plasmid-transfected cells had increased HSP70 expression and demonstrated decreased nitric oxide (NO) release and inducible NO synthase messenger RNA expression in response to endotoxin compared with wild-type and empty plasmid-transfected cells. Heat shock completely abolished subsequent NO and inducible NO synthase messenger RNA expression in wild-type cells. Heat shock factor 1 reached maximum expression 60 to 90 minutes after HS. Heat shock protein 70-transfected cells still displayed endotoxin-induced NF-kappaB nuclear binding, whereas endotoxin tolerance, HS, and exposure to HSF-1, but not exposure to an unrelated promoter, inhibited NF-kappaB nuclear binding.

CONCLUSIONS

Endotoxin tolerance and HS appear to share a common immune suppressive effect, possibly through HSF-1-mediated competitive inhibition of NF-kappaB nuclear binding.

Secretion of antiretroviral chemokines by human cells cultured with acyclic nucleoside phosphonates

Acyclic nucleoside phosphonates are novel class of clinically broadly used antivirotics effective against replication of both DNA viruses and retroviruses including human immunodeficiency virus (HIV). We have investigated their in vitro effects on immune defence mechanisms in human peripheral blood mononuclear cells, with the main emphasis on expression of cytokines which are able to suppress the entry of HIV in cells. Included in the study were prototype acyclic nucleoside phosphonates, i.e. 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA; adefovir), 9-[2-(phosphonomethoxy)ethyl]-2,6-diaminopurine (PMEDAP), (R)-and (S)-enantiomers of 9-[2-(phosphonomethoxy)propyl]adenine [(R)-PMPA; tenofovir] and [(S)-PMPA], and of 9-[2-(phosphonomethoxy)propyl]-2,6-diaminopurine [(R)-PMPDAP] and [(S)-PMPDAP], and their N(6)-substituted derivatives. Some of the compounds were found to substantially enhance secretion of chemokines such as macrophage inflammatory protein-1alpha (MIP-alpha/CCL3), and "regulated on activation of normal T cell expressed and secreted" (RANTES/CCL5). Secretion of MIP-1beta/CCL4 was only marginally increased, whereas production of interleukin-16 (IL-16) and interferon-gamma (IFN-gamma) remained uninfluenced. The most effective proved to be the N(6)-cyclooctyl-PMEDAP, N(6)-isobutyl-PMEDAP, N(6)-pyrrolidino-PMEDAP, N(6)-cyclopropyl-(R)-PMPDAP, and N(6)-cyclopentyl-(R)-PMPDAP derivatives. Remarkably enhanced secretion of chemokines was reached within 2-4 h of the cell culture, and was observed at concentration of 2-5 microM. It may be suggested that acyclic nucleoside phosphonates represent a new generation of antivirotics with combined antimetabolic and therapeutically prospective immunostimulatory properties.

Improved bacterial clearance and decreased mortality can be induced by LPS tolerance and is not dependent upon IFN-gamma

Endotoxin (LPS) tolerance is induced by exposure to sublethal doses of LPS, resulting in a suppressed proinflammatory response and an improved survival rate after challenge with a normally lethal dose of LPS. We studied the effects of tolerance induced by either Escherichia coli-derived LPS or Pseudomonas aeruginosa-derived LPS on the innate immune response to a subsequent P. aeruginosa bacterial challenge and determined if the induction of tolerance was dependent on interferon gamma (IFN-gamma) activity. LPS tolerance was induced in wild-type (WT) and IFN-gamma knockout mice by i.p. injection of 1 microg of LPS on 2 consecutive days. Mice were challenged with an i.p. injection of live P. aeruginosa (1 x 10(8) colony-forming units) 2 days after the second LPS dose. LPS tolerance in WT mice was associated with diminished serum IFN-gamma and IL-12 and increased serum IL-10 responses to the Pseudomonas challenge. Both clearance of the bacterial challenge and survival were improved in WT animals pretreated with either E. coli LPS or P. aeruginosa LPS compared with saline-pretreated control mice. Similarly, IFN-gamma knockout mice exposed to LPS before the Pseudomonas challenge also had improved bacterial clearance of the challenge and an improved survival rate. In separate experiments, priming with IFN-gamma at a dose that approximated the serum concentration induced by LPS priming did not alter cytokine production or bacterial clearance after a Pseudomonas challenge. Finally, administration of IFN-gamma at the time of Pseudomonas challenge amplified cytokine production in LPS-tolerant animals but did not affect bacterial clearance. These results suggest that IFN-gamma is not necessary for the induction of LPS tolerance. Furthermore, IFN-gamma seems to play a role in propagating the inflammatory cytokine response to Pseudomonas challenge, but it did not seem to have any role in bacterial clearance.

Depressed T cell-derived IFN-gamma following trauma-hemorrhage: a potential mechanism for diminished APC responses

INTRODUCTION

Prolonged immunosuppression has been demonstrated after trauma-hemorrhage resulting in an increased susceptibility to sepsis. The contribution of antigen-presenting cells (APC) vs T cells to this diminished immune response, however, remains unknown.

MATERIALS AND METHODS

To study this, male mice were trauma-hemorrhaged (35 +/- 5 mmHg for 90 min and resuscitation) or sham operated. At 24 h thereafter, spleens were harvested and T cells (via Microbeads) and APC (via adherence) were isolated. Cocultures of combined T cells and APC were established for 48 h, stimulated with ConA and LPS. The T cell-derived cytokine IFN-gamma and IL-12 for APC responses were measured in the supernatants by the multiplex assay.

RESULTS

The release of IFN-gamma was suppressed by T cells after trauma-hemorrhage irrespective of whether sham or trauma-hemorrhage APC were added. Trauma-hemorrhaged APC did not affect T cells-derived IFN-gamma release by sham T cells. In contrast, trauma-hemorrhaged T cells depressed the release of IL-12 by APC. The release of IL-12 by trauma-hemorrhaged APC was not altered when sham T cells were cocultured.

CONCLUSION

Prolonged immunosuppression after trauma-hemorrhage appears to be predominantly due to diminished T cell function. Thus, attempts to prevent immunodysfunction should be directed towards T cells.

Reprogramming of circulatory cells in sepsis and SIRS

Immune status is altered in patients with sepsis or non-infectious systemic inflammatory response syndrome (SIRS). Reduced ex-vivo TNF production by endotoxin-activated monocytes has been regularly reported. This observation is reminiscent of the phenomenon of endotoxin tolerance, and the term 'leukocyte reprogramming' well defines this phenomenon. This review will outline that the hyporesponsiveness of circulating leukocytes is not a generalized phenomenon in sepsis and SIRS. Indeed, the nature of the insult (i.e. infectious versus non-infectious SIRS; under anesthesia [surgery] or not [trauma, burn]), the nature of the activator used to trigger leukocytes (i.e. different Toll-like receptor ligands or whole bacteria), the nature of the cell culture (i.e. isolated monocytes versus peripheral blood mononuclear cells versus whole blood assays), and the nature of the analyzed cytokines (e.g. IL-1beta versus IL-1ra; TNF versus IL-10) have a profound influence on the outcome of the response.

Flt3 ligand treatment reverses endotoxin tolerance-related immunoparalysis

Endotoxin tolerance, the secondary blunting of a subset of microbial product-driven responses, is presumed to provide protection from pathological hyperactivation of the innate immune system during infection. However, endotoxin tolerance can itself be harmful. A significant percentage of sepsis survivors exhibit the phenotype of systemic endotoxin tolerance, a state termed immunoparalysis. Similar immune hyporeactivity, associated with an elevated risk of succumbing to bacterial superinfection, is also seen in the aftermath of major trauma, surgery, and burns. We recently demonstrated that in vivo endotoxin tolerance in murine models involves dendritic cell loss as well as alterations in the responsiveness of macrophages and remaining dendritic cells. Furthermore, the kinetics of recovery from immunoparalysis-associated inhibition of proinflammatory and immunoregulatory cytokine production directly parallels the kinetics of dendritic cell repopulation in these models. Given this, we examined whether recovery from immunoparalysis could be accelerated therapeutically with flt3 ligand, a growth factor that stimulates the differentiation and mobilization of dendritic cells. Notably, administration of flt3 ligand rapidly reverses immunoparalysis in vivo, accelerating and amplifying repopulation of tissues with proinflammatory and immunoregulatory cytokine-producing dendritic cells.

Transplantation of Yeast-Infected Cardiac Allografts: A Report of 2 Cases

For the first time in the literature to date, we report 2 cases of transplantation of yeast-infected cardiac allografts. In both cases, endocardial vegetations were observed before graft implantation. Microbiologic samples grew yeasts: Rhodotorula glutinis was found close to the left atrial appendage in the first case and Candida parapsilosis was identified in a vegetation located at the base of the tricuspid valve in the second case. We discuss the possible routes of donor organ infection and management of these 2 unusual cases.

INTERLEUKIN 12 AND INTERFERON-?? SYNTHETIC DEFICIENCY IS ASSOCIATED WITH DENDRITIC CELL CYTOPENIA AFTER CARDIAC SURGERY

Traumatic or inflammatory injury associates with deactivation of monocytes and impaired synthesis of proinflammatory cytokines. We conducted a prospective, observational study to test whether cardiac surgery additionally impaired dendritic and natural killer (NK) cell functions responsible for innate immune production of interleukin (IL)-12-dependent interferon (IFN)-gamma in response to bacteria or toll-like receptor agonists. Blood samples were taken just before induction of anesthesia and 24 h postoperatively. LPS- and fixed Staphylococcus aureus-inducible IFNgamma synthesis in whole blood culture after surgery was reduced to 5% of preoperative values (P < 0.001). Production of IL-12 p70, a critical inducer of IFNgamma in the innate immune response, was reduced to 30% of that produced by preoperative samples (P = 0.013). Circulating CD11c, DR myeloid dendritic cells (DC) that are known sources of IL-12 p70 in normal blood, declined to approximately 25% of presurgical numbers (P = 0.004). Experimental depletion of CD11c, but not CD14, cells from normal peripheral blood mononuclear cell (PBMC) similarly disabled Staphylococcus aureus Cowan 1 (SAC)-induced production of IL-12 p70 and IFNgamma. Consistent with SAC-induced IFNgamma expression in CD56 NK and NK-T cells, CD56 depletion ablated IFNgamma production in normal whole blood. However, repletion of IL-12 p70, IL-18, IL-15, and IL-23 in postoperative blood failed to restore presurgical levels of IFNgamma synthesis (P < 0.05). We conclude that DC cytopenia after major surgery is sufficient to explain postoperative IL-12 p70 and IFNgamma synthetic deficiency. In addition, postoperative blood became hyporesponsive to IFNgamma-inducing cytokines as a further contribution to IFNgamma insufficiency. The novel finding of DC cytopenia after major surgery may portend a lack of other immunologic functions provided by this potent accessory cell population.

Pathophysiology of polytrauma

Immediate and early trauma deaths are determined by primary brain injuries, or significant blood loss (haemorrhagic shock), while late mortality is caused by secondary brain injuries and host defence failure. First hits (hypoxia, hypotension, organ and soft tissue injuries, fractures), as well as second hits (e.g. ischaemia/reperfusion injuries, compartment syndromes, operative interventions, infections), induce a host defence response. This is characterized by local and systemic release of pro-inflammatory cytokines, arachidonic acid metabolites, proteins of the contact phase and coagulation systems, complement factors and acute phase proteins, as well as hormonal mediators: it is defined as systemic inflammatory response syndrome (SIRS), according to clinical parameters. However, in parallel, anti-inflammatory mediators are produced (compensatory anti-inflammatory response syndrome (CARS). An imbalance of these dual immune responses seems to be responsible for organ dysfunction and increased susceptibility to infections. Endothelial cell damage, accumulation of leukocytes, disseminated intravascular coagulation (DIC) and microcirculatory disturbances lead finally to apoptosis and necrosis of parenchymal cells, with the development of multiple organ dysfunction syndrome (MODS), or multiple organ failure (MOF). Whereas most clinical trials with anti-inflammatory, anti-coagulant, or antioxidant strategies failed, the implementation of pre- and in-hospital trauma protocols and the principle of damage control procedures have reduced post-traumatic complications. However, the development of immunomonitoring will help in the selection of patients at risk of post-traumatic complications and, thereby, the choice of the most appropriate treatment protocols for severely injured patients.

CHRONIC ALCOHOLISM CAUSES DELETERIOUS CONDITIONING OF INNATE IMMUNITY

AIMS

To examine the immune consequences of chronic alcoholism in man, in relation to the known association between alcoholism and raised incidence and severity of infections.

METHODS

In 36 alcoholics without liver disease, at the point of commencing withdrawal from alcohol, the following measures of immune competence were measured: the immunophenotypes of cells, acute phase proteins, the endotoxin-neutralizing capacity (ENC) of the serum, titers of anti-lipopolysaccharide (LPS) antibodies, and ex vivo cytokine inducibility in T cells and monocytes (TNFalpha, IL1beta, IL1RA, IL4, IL6, IL8, IL10 and IL12). The results were compared to those from healthy volunteers (day controls). Measures were repeated after 8-13 days of abstinence.

RESULTS

LPS-binding protein (LBP) and soluble CD14 (sCD14) were significantly increased in patients' sera at the outset of withdrawal, whereas reduced titers of anti-LPS IgG (P = 0.012) and a reduced ENC (P = 0.001) were measured. Only ENC rapidly returned to normal values after withdrawal therapy. Cytokine induction with phorbol ester showed no significant alterations in patients' T cells. Patients' monocytes, however, responded to LPS stimulation with enhanced IL1beta-, but reduced TNFalpha- and IL12-production (P = 0.004, P = 0.0042 and P = 0.001, respectively). While IL1- and TNFalpha-responses normalized after the withdrawal period, impairment of the IL12 response persisted throughout the observation period of 2 weeks.

CONCLUSIONS

Alcoholism results in a prolonged LPS-mediated hypoinflammatory conditioning of the innate but not the adaptive immune system, which is not reversed immediately after withdrawal. This alcohol-induced status of the immune system predisposes to infections and sepsis by blunting initial response to the pathogens.

Distinct modulatory effects of LPS and CpG on IL-18-dependent IFN-gamma synthesis

Innate cellular production of IFN-gamma is suppressed after repeated exposure to LPS, whereas CpG-containing DNA potentiates IFN-gamma production. We compared the modulatory effects of LPS and CpG on specific cellular and cytokine responses necessary for NK-cell dependent IFN-gamma synthesis. C3H/HeN mice pretreated with LPS for 2 days generated 5-fold less circulating IL-12 p70 and IFN-gamma in response to subsequent LPS challenge than did challenged control mice. In contrast, CpG-pretreated mice produced 10-fold more circulating IFN-gamma without similar changes in IL-12 p70 levels, but with 10-fold increases in serum IL-18 relative to LPS-challenged control or endotoxin-tolerant mice. The role of IL-18 in CpG-induced immune potentiation was studied in splenocyte cultures from control, LPS-conditioned, or CpG-conditioned mice. These cultures produced similar amounts of IFN-gamma in response to rIL-12 and rIL-18. However, only CpG-conditioned cells produced IFN-gamma when cultured with LPS or CpG, and production was ablated in the presence of anti-IL-18R Ab. Anti-IL-18R Ab also reduced in vivo IFN-gamma production by >2-fold in CpG-pretreated mice. Finally, combined pretreatment of mice with LPS and CpG suppressed the production of circulating IFN-gamma, IL-12 p70, and IL-18 after subsequent LPS challenge. We conclude that CpG potentiates innate IFN-gamma production from NK cells by increasing IL-18 availability, but that the suppressive effects of LPS on innate cellular immunity dominate during combined LPS and CpG pretreatment. Multiple Toll-like receptor engagement in vivo during infection can result in functional polarization of innate immunity dominated by a specific Toll-like receptor response.

[A new role for neutrophils during sepsis: target and source of interleukin-12]

The immune response against a bacterial aggression involves the monocytes-macrophages and polymorphonuclear neutrophils (PMN) in the first line of defense. This natural or innate immunity controls the proliferation of micro-organisms while waiting for the development of aspecific immunity related to lymphocytes. Establishing a link between innate and specific immunity, interleukin-12 (IL-12) is an essential cytokine of the inflammatory response. In a first in vitro study, we showed that IL-12 potentiates the effect of LPS on the production of IL-8 by stimulated PMN, the main chemotactic and activating cytokine of neutrophils. IL-12 would thus support the local recruitment of PMN via an autocrine loop of amplification. In a second in vivo study in septic patients, we noted a defect in the pulmonary and systemic production of IL-12, suggesting a dysregulation of innate immunity during the course of sepsis.

Oral Health and Care in the Intensive Care Unit: State of the Science

Oral health is influenced by oral microbial flora, which are concentrated in dental plaque. Dental plaque provides a microhabitat for organisms and an opportunity for adherence of the organisms to either the tooth surface or other microorganisms. In critically ill patients, potential pathogens can be cultured from the oral cavity. These microorganisms in the mouth can translocate and colonize the lung, resulting in ventilator-associated pneumonia. The importance of oral care in the intensive care unit has been noted in the literature, but little research is available on mechanical or pharmacological approaches to reducing oral microbial flora via oral care in critically ill adults. Most research in oral care has been directed toward patients’ comfort; the microbiological and physiological effects of tooth brushing in the intensive care unit have not been reported. Although 2 studies indicated reductions in rates of ventilator-associated pneumonia in cardiac surgery patients who received chlorhexidine before intubation and postoperatively, the effects of chlorhexidine in reducing ventilator-associated pneumonia in other populations of critically ill patients or its effect when treatment with the agent initiated after intubation have not been reported. In addition, no evaluation of the effectiveness of pharmacological and mechanical interventions relative to each other or in combination has been published. Additional studies are needed to develop and test best practices for oral care in critically ill patients.

Involvement of IRAK-M in peptidoglycan-induced tolerance in macrophages

The molecular mechanisms by which pathogen-associated molecular patterns recognized by TLR2, such as peptidoglycan (PGN), induce homotolerance are largely unknown. It was recently reported that IRAK-M negatively regulates TLR signaling. In this study, we elucidate the molecular mechanisms of tolerance induced by PGN, with a focus on the role of IRAK-M. We demonstrate that pretreatment of macrophage RAW264.7 cells with a high concentration (30 microg/ml) of PGN for 16 h effectively induces tolerance against following stimulation with 30 microg/ml of PGN; while pretreatment with a low concentration (1 microg/ml) of PGN does not. IRAK-M is induced in cells treated with the high concentration of PGN 4-24 h after PGN stimulation, but not in cells treated with the low concentration of PGN up to 24 h after stimulation. Phosphorylation of MAPKs and IkappaBalpha is inhibited after the second PGN stimulation in tolerant cells. Kinase activity of IRAK-1 and association between IRAK-1 and MyD88 are also suppressed in PGN-induced tolerant cells. Furthermore, down-regulation of IRAK-M expression by small interfering RNAs specific for IRAK-M reinstates the production of TNF-alpha after PGN restimulation. These results suggest that induction of IRAK-M and inhibition of kinase activity of IRAK-1 are crucial to PGN-induced tolerance in macrophages.

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

OBJECTIVE

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

DESIGN

Prospective clinical experimental study.

SETTING

University hospital intensive care unit and research facility.

PATIENTS

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

INTERVENTIONS

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

MEASUREMENTS

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

MAIN RESULTS

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

CONCLUSIONS

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

Regulation of interleukin 12 p40 and p70 production by blood and alveolar phagocytes during severe sepsis

Paradoxically, the host response to severe sepsis may lead to immunosuppression, thereby favoring nosocomial infections. We examined the role of the two IL-12 isoforms, bioactive IL-12p70 and regulatory IL-12p40, in 16 patients with severe sepsis. We compared the capacity of purified blood and alveolar phagocytes [polymorphonuclear neutrophils (PMN) and monocytes/macrophages] to secrete each isoform. Blood monocytes had normal basal secretions. In contrast, a marked imbalance was observed after ex vivo stimulation by lipopolysaccharide plus IFN-gamma, with significantly lower IL-12p70 production and higher IL-12p40 production. Conversely, stimulated IL-12p40 production by the patients' blood PMN tended to be impaired, as was their cell-surface beta2 integrin and L-selectin expression, known as markers of cell activation. In the patient's bronchoalveolar lavage fluid, the production of both IL-12 isoforms after ex vivo stimulation was significantly lower with alveolar macrophages than with autologous blood monocytes and significantly higher with alveolar PMN than with autologous blood PMN. This sheds new light on the potential role of PMN in local modulation of inflammation, via secretion of the anti-inflammatory IL-12 p40 subunit. The imbalance between the bioactive and regulatory IL-12 isoforms, which is probably designed to control excessive inflammation, may also make septic patients more susceptible to nosocomial infection.

The Role of IFN-γ in Surgical Patients

Interferon-gamma (IFN-gamma) was shown to play a central role in the regulation of an adequate immune response to trauma in a variety of human in vitro studies and in animal models. However, clinical studies in surgical patients after various injuries failed to clearly prove efficacy despite the fact that all studies have shown enthusiastic in vitro effects. This review summarizes the available data about IFN-gamma after elective operations and accidental trauma and speculates about the further therapeutic potential of this cytokine.

Different modes of IL-10 and TGF-beta to inhibit cytokine-dependent IFN-gamma production: consequences for reversal of lipopolysaccharide desensitization

LPS hyporesponsiveness is characterized by a diminished production of proinflammatory cytokines which can be caused by pretreatment with either LPS (=LPS desensitization) or the combination of the anti-inflammatory cytokines IL-10 and TGF-beta. However, the resulting hyporesponsive states differ regarding their reversibility by the IFN-gamma-inducing cytokine IL-12. Therefore, we aimed at studying the reasons for this differential IL-12 responsiveness of IFN-gamma-producing cells and its consequences for LPS hyporesponsiveness in more detail. In an in vitro IL-12/IL-18 responsiveness model, we demonstrated that IL-10, if permanently present, does not directly inhibit IL-12/IL-18 responsiveness in T/NK cells but indirectly interferes with IFN-gamma production in the presence of monocytes. In contrast, TGF-beta acted directly on IFN-gamma-producing cells by interfering with IL-12/IL-18 responsiveness. After removal of IL-10 but not of TGF-beta, LPS hyporesponsiveness can be reverted by IL-12/IL-18. Consequently, the addition of recombinant TGF-beta during LPS desensitization rendered PBMCs hyporesponsive to a reversal by IL-12/IL-18. Our data suggest that the persistence of IL-10 and the presence of TGF-beta determine the level of IFN-gamma inhibition and may result in different functional phenotypes of LPS desensitization and LPS hyporesponsiveness in vitro and in vivo.