Interleukin 10 protects mice from lethal endotoxemia

Cytokines at the research-clinical interface: potential applications

Developments in the characterization of growth factors and the recognition of their potential for clinical use has advanced through a number of stages. The development of clonogenic haemopoietic colony assays in the 1960s led to the discovery of colony-stimulating activity in the conditioned medium produced by certain cell lines. This activity was then purified and the colony-stimulating factors were identified. With rapid progress in molecular biology techniques in the 1980s, many further growth factors were cloned and produced on an industrial scale. Although erythropoietin, interferons, G-CSF, GM-CSF and IL-2 were all introduced into clinical practice as single agents, cytokines have more recently been investigated for use either in combination, or sequentially. Clinical trials are currently in progress to examine the optimum combinations and timing of administration. Current clinical applications include optimization of methods for mobilization of peripheral blood progenitor cells and amelioration of cytopenias following chemotherapy and bone-marrow transplantation. In the future, cytokines will be employed to expand stem and progenitor cells ex vivo, to improve gene transduction strategies, possibly to protect the gastrointestinal epithelium and as immunomodulators, both in vivo and in vitro. This review will focus on recently characterized growth factors including c-kit ligand/stem cell factor, flt3 ligand, c-mpl ligand/thrombopoietin and interleukins-11, 4, 7, 10, 12 and 13.

Decreased interleukin-10 production by neonatal monocytes and T cells: relationship to decreased production and expression of tumor necrosis factor-alpha and its receptors

The production of IL-10 by human neonatal blood mononuclear leukocytes (BML) stimulated with lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), antibodies to CD3, or phorbol 12-myristate 13-acetate (PMA) was measured. The production of IL-10 by neonatal BML cultured with LPS or TNF-alpha was approximately 20 and approximately 15%, respectively, of adult BML. The combination of human recombinant TNF-alpha and LPS failed to augment IL-10 production in neonatal BML. The decreased production of IL-10 by neonatal leukocytes was not due to an autocrine feedback mechanism because only low concentrations of IL-10 were found in newborn sera. A connection with TNF-alpha could not be ruled out, because TNF-alpha production by LPS-stimulated newborn BML and the expression of TNF-alpha receptors on newborn monocytes were reduced. Mean +/- SD of concentrations of IL-10 in supernatants from adult and neonatal BML after stimulation with antibodies to human CD3 for 48 or 72 h were 914 +/- 386 and 178 +/- 176 pg/mL, respectively (p < 0.0001). In experiments with enriched populations of neonatal T cells, the addition of PMA failed to augment IL-10 production. This suggested that newborn T cells may be in a different state of activation than adult T cells Thus, IL-10 production in neonatal monocytes and T cells is reduced and this study suggests that the reduction may be secondary in part to regulatory processes involving TNF-alpha and its receptors.

Interleukin-10 prevents death in lethal necrotizing pancreatitis in mice

BACKGROUND

Cytokines derived from macrophages may play an integral role in the evolution of acute pancreatitis. Interleukin-10 (IL-10), a potent antiinflammatory cytokine, prevents the activation of macrophages and their release of inflammatory cytokines. The aim of this study was to determine whether treatment with IL-10 decreased the severity of experimental acute pancreatitis.

METHODS

Thirty female Swiss Webster mice were divided into three groups. Acute pancreatitis was induced by using a choline-deficient, 0.5% ethionine supplemented (CDE) diet. Group A (controls) received CDE diet alone. Group B was pretreated with 10,000 units of intraperitoneal IL-10 at the onset of feeding and every 8 hours thereafter. Group C received IL-10 33 hours after beginning the CDE diet and every 8 hours thereafter. One half of the animals in each group was killed at 54 hours; the remaining living animals were killed at 80 hours. Serum amylase levels (units per liter) were determined at 54 and 80 hours. Pancreata were harvested and fixed in formalin. Histologic characteristics were graded on a scale from 0 to 4 (normal to most abnormal) in a blinded fashion by two investigators.

RESULTS

Serum amylase level and histologic score (edema, inflammation, hemorrhage, and necrosis) were significantly reduced when IL-10 was administered either prophylactically or therapeutically (p < 0.01). At 54 hours all animals were alive. Mortality was reduced at 80 hours in both groups treated with IL-10 compared with those fed the CDE diet alone (p < 0.001).

CONCLUSIONS

These results suggested that macrophages play an integral role in determining the severity of acute pancreatitis in this animal model. The finding that IL-10 decreased inflammation and prevented death, even when given after acute pancreatitis was established, suggests that it may have potential for clinical use.

Interleukin-10 protects neonatal mice from lethal group B streptococcal infection

We investigated the role of interleukin-10 (IL-10) in a neonatal mouse model of lethal group B streptococci (GBS) sepsis. Plasma IL-10 levels significantly increased at 24 and 48 h after GBS inoculation. Neutralization of IL-10 with specific antibodies had no effect on lethality. Administration of recombinant IL-10 at 20 or 4 h before challenge, but not at later times, resulted in decreased tumor necrosis factor alpha levels and improved survival. IL-10 could be potentially useful for the treatment of GBS sepsis.

Inflammatory cytokine and nitric oxide responses in pediatric sepsis and organ failure

OBJECTIVE

To examine the relationship of circulating proinflammatory and anti-inflammatory cytokine concentrations to nitric oxide and organ failure in pediatric sepsis.

DESIGN

Prospective study.

SETTING

Pediatric intensive care unit (ICU), children's Hospital of Pittsburgh, University of Pittsburgh.

PATIENTS

Nineteen patients with a diagnosis of sepsis admitted to the pediatric ICU. Twelve uninfected critically iII patients served as controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma interleukin (IL)-10, IL-6, and nitrite/nitrate concentrations were measured and compared with an index of organ failure daily for 3 days after presentation with the sepsis syndrome. Children with increased plasma IL-6 concentrations (n = 6) had increased plasma nitrite/nitrate concentrations (p < 0.01 on each day), increased organ failure scores (p < .05 on days 1 and 3), and the highest plasma IL-10 concentrations (p < .05 on days 1 and 3, p = .054 on day 2) when compared with children with sepsis and undetectable IL-6 concentrations. Children with sepsis and detectable IL-6 concentrations, and children with undetectable IL-6 concentrations, both had increased nitrite/nitrate concentrations (p < .005 on days 1 through 3) and increased IL-10 concentrations (p < .05 on days 1 and 2) compared with controls. Children with increased IL-6 concentrations had higher organ failure on each day (p < .01), and children with undetectable IL-6 concentrations had higher organ failure on days 1 and 2 only (p < .005) when compared with controls. Organ failure improved over time in the children with undetectable IL-6 concentrations (p < .005).

CONCLUSIONS

Increased plasma nitrite/nitrates and increased organ failure scores occurred in the children with sepsis who had an exaggerated proinflammatory state, despite a pronounced anti-inflammatory response. When the anti-inflammatory response predominated and the proinflammatory state was dampened, organ failure status improved.

Net inflammatory capacity of human septic shock plasma evaluated by a monocyte-based target cell assay: identification of interleukin-10 as a major functional deactivator of human monocytes

We have developed a functional assay to study the inflammatory capacity of plasma collected from patients with severe gram-negative septic shock. In this assay, elutriation-purified, cryo-preserved human monocytes from one healthy donor are combined with plasma from patients with severe persistent septic shock for 5 h. Subsequently, the plasma is removed, medium added, and procoagulant activity (PCA) and secretion of tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) measured after 18-h incubation. Plasma from 10 patients (6 died) infected with Neisseria meningitidis previously shown to contain high levels of native lipopolysaccharide (LPS) (median 2,700 pg/ml), TNF-alpha, IL-6, IL-8, and complement activation products, had a low net spontaneous inflammatory capacity on the monocytes. The median levels of PCA, TNF-alpha, and IL-6 were 5, 0, and 4%, respectively, of the monocyte activities induced by normal plasma boosted with purified N. meningitidis (Nm)-LPS (2,500 pg/ml; net LPS-boosted capacity, 100%). The levels of PCA, TNF-alpha, and IL-6 obtained with plasma from shock patients were not different from those induced by plasma from 10 meningococcal patients without shock or with plasma from healthy persons. Boosting shock plasma with 2,500 pg/ml Nm-LPS had little effect on the monocyte activities since the median values of PCA, TNF-alpha, and IL-6 revealed a minimal increase from 5, 0, and 4% to 9, 2, and 6%, respectively. The shock plasmas revealed a strong LPS-inhibitory capacity that was largely absent in plasmas from 10 meningococcal patients without shock since the median levels of PCA, TNF-alpha, and IL-6 increased from 5, 0, and 0% to 135, 51, and 73%, respectively, after boosting with 2,500 pg/ml Nm-LPS. The LPS-inhibitory capacity was closely associated with the levels of IL-10. The median levels of IL-10 were 19,000 pg/ml in nine shock patients vs. 22 pg/ml in nine nonshock patients with systemic meningococcal disease. Removal of native IL-10 by immunoprecipitation restored the capacity of plasmas to induce monocyte activation either by native LPS or by boosting with Nm-LPS. IL-4 and TGF-beta were not detected in shock plasmas. In 24 patients with detectable meningococcal LPS ( > 10 pg/ml, 0.1 endotoxin units/ml), the levels of IL-10 were correlated to the levels of LPS (r = 0.79, P < 0.001). IL-10 declined from initiation of antibiotic therapy and paralleled the levels of native LPS. Decreasing levels of IL-10 in serially collected shock plasmas were directly related to increasing monocyte responsiveness after Nm-LPS boosting. These results suggest that IL-10 plays a major role in containing activation of monocytes and possibly other LPS-responsive cells during overwhelming meningococcemia.

IL-10 is necessary and sufficient for autoimmune diabetes in conjunction with NOD MHC homozygosity

Contrary to expectations based on in vitro experiments, we previously found that pancreatic IL-10 did not inhibit autoimmune diabetes but accelerated it in an MHC-dependent manner. Therefore, the ability of IL-10 to overcome the absence of all non-MHC diabetes susceptibility (Idd) alleles was studied in transgenic mice expressing pancreatic IL-10 backcrossed to B10.H2g7 congenic mice, which have no Idd alleles other than NOD MHC (H2g7). IL-10 transgenic backcross 1 (BC1) mice with H2g7/g7 haplotype developed clear-cut insulitis and diabetes, but neither transgenic mice with the H2g/b haplotype nor nontransgenic BC1 mice did so. Further implicating IL-10 in autoimmune diabetes, anti-IL-10 antibody treatment inhibited the development of insulitis in NOD mice. These results suggest that IL-10 may be necessary and sufficient for producing autoimmune diabetes in conjunction with NOD MHC homozygosity and that some Idd genes may be related to the regulation of IL-10.

The pathogenesis of sepsis. Factors that modulate the response to gram-negative bacterial infection

Gram-negative bacteria gain access to the bloodstream by evading host defenses. Once in circulation, lipopolysaccharide interacts with the host receptor CD14 and initiates the host's immune response. Lipolysaccharide stimulates the host to produce a cascade of mediators that activate and target leukocytes, opsonize the bacteria, and induce fever to defend against the invading bacteria. Unregulated release of these mediators, however, leads to the production of vasoactive substances, activation of the clotting cascade, and diminution of cardiac performance, which leads to the sepsis syndrome. This article discusses the pathogenic events that lead to sepsis syndrome and reviews critical steps in regulating these inflammatory mediators to allow the host to recover from gram-negative bacteremia.

Modulatory effect of antibiotics on cytokine production by human monocytes in vitro

Some antimicrobial agents have been reported to modify the host immune and inflammatory responses both in vivo and in vitro. Fosfomycin (FOM) and clarithromycin (CAM) have immunomodulatory activity on human lymphocyte function. In the present study, we examined the effects of FOM and CAM on cytokine synthesis by lipopolysaccharide (LPS)-stimulated human monocytes in comparison with that of dexamethasone in vitro. The three drugs demonstrated positive or negative effects on the synthesis of various cytokines by LPS-primed monocytes. They suppressed the synthesis of tumor necrosis factor alpha, interleukin 1 alpha (IL-1 alpha), IL-1 beta, the IL-1 receptor antagonist, and granulocyte-macrophage colony-stimulating factor in a concentration-dependent manner at concentrations between 1.6 and 40 micrograms/ml. On the contrary, the drugs showed different actions on the synthesis of IL-6 and IL-10. Namely, FOM enhanced both IL-6 and IL-10 synthesis, CAM enhanced only IL-10 synthesis, but dexamethasone deeply suppressed the synthesis of both cytokines. These data indicate that antibacterial agents may modify acute-phase inflammatory responses through their effects on cytokine synthesis by monocytes.

Association of interleukin-10 with rejection-sparing effect in septic kidney transplant recipients

Certain cytokines, particularly gamma-interferon (IFN) and interleukin (IL)-2 associated with TH1 cell function, have been shown to play a role in allograft rejection. One paradigm for long-term allograft acceptance involves TH2 cytokine predominance (IL-4 and IL-10). We describe two renal allograft recipients for whom immunosuppression was discontinued due to serious sepsis and who maintained stable renal function over 2-6 months without immunosuppression. During this time, there were higher levels of both IFN-gamma and IL-10 in the peripheral blood than in stable control kidney transplant recipients on immunosuppression. In one of the patients, levels of IL-10 fell, while those of IFN-gamma remained persistently elevated. This was associated with biopsy-proven rejection. Although peripheral blood cytokine levels may not reflect intragraft events, these data are consistent with an allograft protective role for IL-10 offsetting that of IFN-gamma in both patients off immunosuppression.

Interleukin 10 inhibits cytokine production of human AML cells

BACKGROUND

Unlike normal hematopoietic cells leukemic blasts from patients with AML constitutively express cytokines like IL1, GM-CSF and TNF alpha and it has been suggested that these cytokines may regulate growth and differentiation of the malignant cells. IL10 inhibits cytokine production of activated macrophages and T-helper 1 cells. We analysed whether IL10 can also suppress cytokine production and may inhibit growth of AML cells.

MATERIALS AND METHODS

AML blasts of 18 patients were purified by immunomagnetic separation and cultured in serum-free medium in the presence of cytokines. The production of cytokines was analysed by ELISA, DNA synthesis by 3H-thymidine incorporation and mRNA expression of cytokine genes by semiquantitative RT-PCR.

RESULTS

Our results confirm previous results that AML blasts produce a variety of cytokines such as GM-CSF, IL1 alpha, IL1 beta, IL6 and TNF alpha. AML cells were induced to proliferation by G-CSF, GM-CSF, IL3, IL1 beta and SCF to a different extent. In contrast, IL10 significantly inhibited the cytokine production at the mRNA and protein level and spontaneous thymidine uptake in a dose-dependent way. This inhibition could be abrogated by IL10 specific antibodies.

CONCLUSION

These observations suggest an inhibitory effect of IL10 on the proliferation of cultured AML blasts most likely through suppression of endogenous cytokines.

Interleukin-10 is associated with the development of sepsis in trauma patients

Interleukin-10 (IL-10) is a potent regulator of proinflammatory cytokines, including tumor necrosis factor-alpha, IL-1, IL-6, and interferon-gamma. We retrospectively evaluated 66 severely injured patients for detectable plasma IL-10. the presence or absence of IL-10 was correlated with clinical parameters. Forty of 66 patients had detectable levels of IL-10. Plasma IL-10 was associated with admission hypotension (p < 0.01) and the development of sepsis (p < 0.05). There was no difference between IL-10-positive and -negative patients with respect to age, mechanism or severity of injury, blood transfusion, operative interventions, or the subsequent development of ARDS, hepatic dysfunction, or renal insufficiency. We conclude that IL-10 can be detected in the plasma of some severely injured patients and that it is associated with the development of sepsis. Further investigation of the immunoregulatory effects of IL-10 after trauma is indicated.

Interleukin-10 functions as an antiinflammatory cytokine in rheumatoid synovium

OBJECTIVE

Interleukin-10 (IL-10) is an antiinflammatory cytokine that has been shown to play a role in rheumatoid arthritis (RA). We therefore investigated the effects of IL-10 on the function and phenotype of synovial fluid mononuclear cells (SFMC) derived from patients with RA. In addition, we studied the production of IL-10 in rheumatoid joints, and the role of endogenous IL-10 in the regulation of SFMC function.

METHODS

The presence of IL-10 in rheumatoid joints was studied using IL-10-specific enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase- polymerase chain reaction (RT-PCR) techniques. The effects of recombinant human IL-10 or neutralizing anti-IL-10 monoclonal antibodies (MAbs) on both cytokine production and phenotype of SFMC were evaluated using cytokine-specific ELISAs and flow cytometry. The effect of IL-10 on proliferation of SFMC was determined by incorporation of tritiated thymidine.

RESULTS

IL-10 was detected by ELISA in 22 of 23 SF samples, and was spontaneously produced by cultured SFMC. IL-10 messenger RNA was detectable in all 8 SFMC samples, as determined by RT-PCR. Neutralization of endogenously produced IL-10 by anti- IL-10 MAbs resulted in increased production of IL-1 beta, tumor necrosis factor alpha (TNF alpha), and granulocyte- macrophage colony-stimulating factor (GM-CSF) by SFMC, and in enhanced proliferation of SFMC. In particular, the production of TNFalpha was dramatically increased by anti-IL-10 MAbs. Moreover, the expression of HLA-DR molecules by SF macrophages was increased, and the expression of CD16 was decreased by anti-IL-10 MAbs. In contrast, addition of recombinant IL-10 significantly decreased the production of IL-1 beta, TNF alpha, and GM-CSF by SFMC, and decreased spontaneous and IL-2-induced proliferation of SFMC. Finally, IL-10 decreased HLA-DR expression and increased the expression of the Fc gamma receptors, CD16 and CD64, by SF macrophages.

CONCLUSION

These data indicate that endogenously produced IL-10 functions as an immunoregulatory molecule in rheumatoid synovium. Importantly, exogenous IL-10 has potent antiinflammatory effects on SFMC, suggesting that IL-10 may be useful in the treatment of patients with RA.

Interleukins 6 and 11 protect mice from mortality in a staphylococcal enterotoxin-induced toxic shock model

BALB/By mice given doses of D-galactosamine plus Staphylococcus aureus enterotoxin B die within 48 h of administration. The cause of death is a syndrome much like toxic shock syndrome in humans. We used this model to investigate the role of two cytokines, interleukin 6 and interleukin 11, which share the signal transducing subunit, gp130, of their respective receptors. We observed that pretreatment of mice with antibody to interleukin 6 increased mortality from 55% to nearly 90% (P < 0.001), while pretreatment with either cytokine reduced death. The protection was dose dependent; however, interleukin 6 was about 10-fold more potent that interleukin 11. These data indicate that endogenous interleukin 6 plays a protective role in attenuating acute inflammatory responses; furthermore, interleukin 6 and interleukin 11 can abrogate T-cell activation due to triggering by superantigen. A possible clinical role for these cytokines in the treatment of toxic shock merits further investigation.

Viral IL-10 gene therapy inhibits TNF-alpha and IL-1 beta, not IL-6, in the newborn endotoxemic mouse

INTRODUCTION

Modulation of the inflammatory cascade within the liver of critically ill infants may improve the chance of survival. Using gene therapy, the authors hypothesized that augmented local production of the counter-regulatory cytokine viral interleukin-10 (IL-10) in vivo will modulate the critical cytokines in the inflammatory response. The purpose of the present study was to determine whether replication-defective adenovirus-mediated viral IL-10 (vIL-10) gene transfer and expression within the liver can achieve this goal in newborn mice.

MATERIALS AND METHODS

Four-week-old Balb/c mice were administered (intraperitoneally) 1 x 10(9) plaque-forming units (pfu) per milliliter of an adenovirus vector (E1a/b-deleted) than encodes the sv40 promoter and the BCRF1 cDNA, or of control vector dl434 that expresses no foreign gene. Forty-eight hours later the mice were challenged with 50 micrograms/kg of lipopolysaccharide (LPS) they were killed 1, 2, 6, or 24 hours later (six at each time point). Southern blot analysis was performed on genomic DNA isolated from the liver, lung, and kidney to assess gene transfer of BCRF1. Homogenized liver protein was analyzed for tumor necrosis factor-alpha (TNF-alpha), IL-1 beta, IL-6, and recombinant vIL-10.

RESULTS

Southern blot analysis confirmed successful gene transfer to the liver but not to the lung, kidney, or dl434-transduced liver in mice that received adenovectors. Viral IL-10 levels within the liver ranged from 14 to 18 ng/mL. In controls, TNF-alpha production was elevated at early time points, to 18,000 pg/mL, but decreased rapidly by 24 hours after LPS challenge. The TNF-alpha levels of animals treated with Ad5svBCRF1 were significantly lower than those of controls throughout the course of study (P < .0001). After the LPS challenge, hepatic IL-1 beta decreased, from a maximum of 800 pg/mL (2 hours) to 411 pg/mL (24 hours). Inhibition of IL-1 beta by vIL-10 occurred at 1 hour (P > .016) and 2 hours (P < .001) only. Hepatic production of IL-6 after LPS challenge ranged from 7 to 8,000 pg/mL in all groups and was not altered by vIL-10 gene therapy.

CONCLUSION

In vivo administration of adenovectors encoding BCRF1 to newborn mice results in efficient hepatic transduction and expression of recombinant vIL-10. The Kupffer cell response to LPS is suppressed with respect to TNF-alpha and IL-1 beta, but not IL-6. In vivo modulation of hepatic cytokine responses is achievable using gene products that mimic cellular cytokines. This is an effective model for the selective evaluation of therapeutic gene products for gene therapy of sepsis.

Lipopolysaccharide-induced lethality and cytokine production in aged mice

This study was designed to define the lipopolysaccharide (LPS) sensitivity of aged mice in terms of lethality and cytokine production and to determine down-regulating responses of corticosterone and interleukin 10 (IL-10). The 50% lethal doses of LPS in young (6- to 7-week-old) and aged (98- to 102-week-old) mice were 601 and 93 microg per mouse (25.6 and 1.6 mg per kg of body weight), respectively. Aged mice were approximately 6.5-fold more sensitive to the lethal toxicity of LPS in micrograms per mouse (16-fold more sensitive in milligrams per kilogram) than young mice. Levels in sera of tumor necrosis factor-alpha (TNF-alpha) IL-1alpha, and IL-6 after intraperitoneal injection of 100 microg of LPS peaked at 1.5, 3, and 3 h, respectively, and declined thereafter in both groups of mice. However, the peak values of these cytokines were significantly higher in aged than in young mice (P < 0.05). Gamma interferon (IFN-gamma) was detectable at 3 h, and sustained high levels were still detected after 12 h in both age groups. Although there were no significant differences in levels of IFN-gamma in sera from both groups, aged mice showed higher IFN-gamma levels throughout the 3- to 12-h study period. Administration of increasing doses of LPS revealed that aged mice had a lower threshold to IL-1alpha production than young mice. In addition, aged mice were approximately 4-fold more sensitive to the lethal toxicity of exogenous TNF in units per mouse (10-fold more sensitive in units per kilogram) than young mice. With regard to down-regulating factors, corticosterone amounts were similar at basal levels and no differences in kinetics after the LPS challenge were observed, whereas IL-10 levels in sera were significantly higher in aged mice at 1.5 and 3 h than in young mice (P < 0.01). These results indicate that aged mice are more sensitive to the lethal toxicities of LPS and TNF than young mice. We conclude that a relatively activated, or primed, state for LPS-induced cytokine production, in spite of full down-regulating responses by corticosterone and IL- 10, may explain at least in part LPS sensitivity in aged mice.

Interleukin-10 inhibition of the progression of established collagen-induced arthritis

OBJECTIVE

Interleukin-10 (IL-10) is a potent inhibitor of the proinflammatory cytokines, including tumor necrosis factor alpha and IL-1, which are considered important in the pathogenesis of rheumatoid arthritis (RA). The study was undertaken to establish whether IL-10 can ameliorate arthritis in the collagen-induced arthritis (CIA) model of RA.

METHODS

DBA/1 mice were immunized with bovine type II collagen in adjuvant, and treated daily after disease onset with recombinant murine IL-10 or with saline as a control. Mice were monitored for paw swelling and clinical score. Histologic analysis was also performed.

RESULTS

IL-10 treatment of established CIA inhibited paw swelling (P < 0.0001), as well as disease progression as defined by clinical score (P < 0.0002). Cartilage destruction, as assessed histologically, was reduced in IL-10-treated mice compared with controls (P < 0.01).

CONCLUSION

IL-10 suppresses established CIA, probably by inhibiting proinflammatory cytokine production. Our results, taken together with previously reported findings, indicate a potential therapeutic role for IL-10 in RA.

Constituent analysis may permit improved diagnosis of intra-abdominal abscess

BACKGROUND

Intra-abdominal abscesses (IAA) often fail to resolve with intravenous antibiotics alone and frequently require drainage. Diagnosis of IAA in postoperative patients with other likely sources of infection is very difficult.

PATIENTS AND METHODS

In order to characterize IAA and identify parameters that might facilitate diagnosis, we prospectively examined peripheral blood and pus of 15 consecutive patients with IAA and compared them to samples from 34 consecutive patients with soft-tissue abscesses (STA).

RESULTS

Serum interleukin (IL)-10 was elevated in IAA patients, while abnormally detectable serum IL-4 was demonstrated in the pus of both IAA and STA patients. IL-10 in IAA pus was more than 11-fold higher than in STA, whereas IL-4 in pus was similar in both types of abscesses. Both IL-4 and IL-10 were 4- to 10-fold higher in IAA and STA pus than in corresponding patient serum. Serum lysozyme was, however, significantly elevated in all abscess patients.

CONCLUSIONS

The presence of IL-4 and IL-10 may indicate a T-helper 2 lymphocyte response in the etiology of abscess formation and persistence, although precise determination of T-helper 1-related cytokines is needed to verify this. Serum lysozyme and IL-10 may be reliable and relatively inexpensive diagnostic aids.

Graft-versus-host disease and the Th1/Th2 paradigm

Graft-versus-host disease (GVHD) is the major complication after allogeneic bone marrow transplantation (BMT) and is initiated by alloreactive donor T cells recognizing foreign histocompatibility antigens of the host. There is now substantial experimental and clinical evidence to implicate a dysregulation of cytokine networks as a primary cause for the induction and maintenance of GVHD. In this article, current knowledge of the involvement of cytokines in GVHD is reviewed. The balance between type 1 cytokines (interleukin-2, interferon-gamma) and type 2 cytokines (interleukin-4, interleukin-10) is hypothesized to govern the extent to which a cell-mediated immune response and a systemic inflammatory response develop after allogeneic BMT. Because type 2 cytokines can inhibit the production of the proinflammatory cytokines interleukin-1 and tumor necrosis factor-alpha, a type 1 to type 2 shift in the initial response of donor T cells to host alloantigens may interrupt the cytokine cascade after allogeneic BMT and may offer a new approach to the prevention and treatment of acute GVHD. Interventions to specifically eliminate or modify the response of donor T cells to alloantigens in order to reduce GVHD may obviate the need for T cell depletion in clinical BMT and thus avoid the increased risk of relapse of malignancy and impairment of donor cell engraftment.

Interleukin (IL)-10 inhibits long-term IL-6 production but not preformed mediator release from rat peritoneal mast cells

Mast cells have been implicated in a number of diseases involving chronic inflammation including asthma, rheumatoid arthritis, and inflammatory bowel diseases. They are a potent source of several cytokines, including IL-6 and TNF-alpha. Freshly isolated rat peritoneal mast cells will produce IL-6 in response to anti-IgE, LPS, PGE1, or PGE2; however, the mechanisms by which such cytokine production is regulated are poorly understood. IL-10 is recognized as an important immunoregulatory cytokine with effects on T cell development and the production of inflammatory cytokines. IL-10 has previously been described to enhance mast cell development in the context of IL-3 and IL-4. In the current study, we have examined the ability of IL-10 to modulate rat peritoneal mast cell IL-6 and TNF-alpha production in response to a variety of stimuli. We have observed that recombinant murine IL-10 can inhibit the production of both IL-6 and TNF-alpha by mast cells without altering the degree of histamine release in response to anti-IgE. Concentrations of IL-10 as low as 0.2 ng/ml were sufficient to inhibit IL-6 production by LPS- or anti-IgE-activated cells significantly. IL-10 also inhibited PGE1- and PGE2-induced IL-6 production. The relative potency of IL-10 as an inhibitor of mast cell IL-6 production was highly dependent upon the stimulus used, with a 10-fold difference in the IC50 for LPS- or anti-IgE-activated cells (0.21 ng/ml) and cells activated with a combination of LPS and PGE2 (2.29 ng/ml). This suggests that prostanoids may limit the ability of IL-10 to modulate mast cell IL-6 production in the context of inflammation. These data have important implications for the regulation of mast cell IL-6 in inflammatory diseases involving prostanoid production and the effects of treatment with cyclooxygenase inhibitors. Our results also demonstrate a dual role for IL-10 on mast cells as a growth factor and inhibitor of cytokine production.

Epinephrine inhibits tumor necrosis factor-alpha and potentiates interleukin 10 production during human endotoxemia

Short-term preexposure of mononuclear cells to epinephrine inhibits LPS-induced production of TNF, whereas preexposure for 24 h results in increased TNF production. To assess the effects of epinephrine infusions of varying duration on in vivo responses to LPS, the following experiments were performed: (a) Blood obtained from eight subjects at 4-24 h after the start of a 24-h infusion of epinephrine (30 ng/kg per min) produced less TNF after ex vivo stimulation with LPS compared with blood drawn before the start of the infusion, and (b) 17 healthy men who were receiving a continuous infusion of epinephrine (30 ng/kg per min) started either 3 h (EPI-3; n = 5) or 24 h (EPI-24; n = 6) were studied after intravenous injection of LPS (2 ng/kg, lot EC-5). EPI-3 inhibited LPS-induced in vivo TNF appearance and also increased IL-10 release (both P < 0.005 versus LPS), whereas EPI-24 only attenuated TNF secretion (P = 0.05). In separate in vitro experiments in whole blood, epinephrine increased LPS-induced IL-10 release by a combined effect on alpha and beta adrenergic receptors. Further, in LPS-stimulated blood, the increase on IL-10 levels caused by epinephrine only marginally contributed to concurrent inhibition of TNF production. Epinephrine, either endogenously produced or administered as a component of sepsis treatment, may have a net antiinflammatory effect on the cytokine network early in the course of systemic infection.

Do monoclonal antibodies and anticytokines still have a future in infectious diseases?

The continuing high mortality of septic shock has prompted a major effort by the research community to identify novel therapeutic targets. These targets can be conveniently grouped into (1) those derived from microbial components or products; (2) inflammatory mediators; and (3) effector molecules. Many of the experimental, so-called adjunctive agents developed have been monoclonal antibodies or anticytokine molecules of various kinds, and some have progressed into clinical trial. Unfortunately, these trials have failed to show unequivocal survival benefit for patients in shock, prompting a reappraisal of our approach to these agents. In this article, we discuss the possible reasons for these failures: (1) the targets are wrong; (2) the agents are inappropriate; or (3) the trial design is flawed. It would be premature to conclude that adjunctive agents have no future in the therapy of sepsis, but identifying the correct agent, and perhaps more importantly, the correct target population, is going to be more difficult than was at first believed.

Manipulation of local and systemic host defence in the prevention of perioperative sepsis

This review addresses some of the immunological issues surrounding the complex problem of perioperative sepsis. It identifies an immunological paradox between the relative immunosuppression of the immediate postoperative period and the relative immune activation of established sepsis, in addition to discussing current knowledge of the mechanisms surrounding these phenomena. Much remains unknown about perioperative immunoregulation; there are a number of potential mechanisms, however, whereby local and systemic immune defences can be modified or enhanced. Provided patients at risk can be identified, such manipulations may find application in preventing infection and sepsis after surgery.

Effect of xanthine derivates and dexamethasone on Streptococcus pneumoniae-stimulated production of tumor necrosis factor alpha, interleukin-1 beta (IL-1 beta), and IL-10 by human leukocytes

The present study concerns the release of the proinflammatory cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha and of the anti-inflammatory cytokine IL-10 by human leukocytes in whole blood during stimulation with Streptococcus pneumoniae and the effects of various xanthine derivates, i.e., pentoxifylline (PTX), caffeine, and theofylline, and of dexamethasone (DXM). All three xanthine derivates and DXM inhibited the release of tumor necrosis factor alpha, PTX being the most effective. PTX, theofylline, and DXM inhibited the release of IL-1 beta, but caffeine did not affect IL-1 beta release. The release of IL-10 was significantly reduced by PTX at 24 h and by caffeine at 48 h, but DXM increased the release of this cytokine. In sum, the results of this study demonstrate that DXM inhibits only the release of proinflammatory cytokines but not of the anti-inflammatory cytokine IL-10 by human leukocytes, while PTX is the most potent inhibitor of both proinflammatory and anti-inflammatory cytokines.

Staphylococcal enterotoxin B and tumor-necrosis factor-alpha-induced relapses of experimental allergic encephalomyelitis: protection by transforming growth factor-beta and interleukin-10

A study was made of the ability of the superantigen staphylococcal enterotoxin B (SEB) to induce relapses of experimental allergic encephalomyelitis (EAE) in SJL mice that had partially or completely recovered from acute EAE. We find that a single injection of 0.05 mg SEB i.v. induces mild relapses in 50% of such mice. In addition, tumor necrosis factor (TNF)-alpha (0.2 micrograms, i.p.) also induces EAE relapses in 43% of SJL mice when injected 1-2 months after recovery. SEB does not induce a second relapse if reinjected when V beta 17a+T cells are still partially deleted. In these mice, however, TNF-alpha is equally effective in inducing relapses as in mice that did not receive SEB previously. We showed earlier that transforming growth factor (TGF)-beta and TNF-alpha have antagonistic effects on experimental autoimmune diseases; e.g., in spontaneously relapsing EAE, TGF-beta and anti-TNF were protective, while anti-TGF-beta caused disease exacerbation. Interleukin (IL)-10 is also known to counteract certain TNF effects. We now find that both human IL-10 and TGF-beta 2 lower the incidence of EAE relapses when given simultaneously with SEB or TNF-alpha. The protective effect of TGF-beta is significant only against relapses induced by SEB (reduced to 9%), and that of IL-10 only against relapses induced by TNF (reduced to 0%) with the treatment regimens employed. Neutralizing anti-TGF-beta does not increase the incidence of SEB-induced EAE relapses. In contrast, anti-IL-10 increases both the incidence and the severity of such relapses. We conclude that TNF production is probably important in causing EAE relapses, but that other aspects of the SEB-induced reactivation of myelin-specific T cells also contribute. Furthermore, endogenous IL-10 rather than TGF-beta production appears to limit the susceptibility to induction of EAE relapses in this model.

Role of defective monocyte interleukin-10 release in tumor necrosis factor-alpha overproduction in alcoholics cirrhosis

Monocytes of patients with alcoholic cirrhosis produce higher amounts of tumor necrosis factor-alpha (TNF-alpha) after lipopolysaccharide (LPS) stimulation. The mechanisms of the overproduction remain undefined. IL-10 (IL-10) is an antiinflammatory cytokine known to downregulate TNF-alpha secretion by monocytes. The present study analyzes IL-10 production by monocytes and its control on TNF-alpha secretion in alcoholic cirrhosis. LPS-stimulated monocytes from alcoholic cirrhotics (n = 13) showed decreased IL-10 (median, 240 pg/mL [40 to 500] upsilon 513 pg/mL [152 to 1,335]; P = .01) compared with controls (n = 13). Cells from cirrhotic patients were normally responsive to recombinant IL-10, which induced a dose dependent decrease of TNF-alpha secretion. On the other hand, preincubation with anti-IL-10 monoclonal antibodies led to significant increase in TNF-alpha secretion in controls (median, 7,325 to 16,800 pg/mL; P = .002) but not in cells from cirrhotic patients (16,535 to 20,450 pg/mL; P = .14), abolishing the difference in TNF-alpha production between cirrhotic patients and controls. It is concluded that defective IL-10 secretion by monocytes from alcoholic cirrhotic patients could be involved in the characteristics TNF-alpha overproduction observed in this disease.

Administration of interleukin-5 or -10 activates peritoneal B-1 cells and induces autoimmune hemolytic anemia in anti-erythrocyte autoantibody-transgenic mice

Activation mechanisms of B-1 (Ly-1 B) cells have been suggested to be different from those of conventional B cells. To assess the role of various interleukins (IL) in the activation of B-1 cells, we injected IL-4, IL-5 or IL-10 into nonanemic anti-red blood cells (RBC) autoantibody-transgenic mice, in which conventional B cells are clonally deleted but peritoneal B-1 cells persist without secreting Ig. Intraperitoneal or intramuscular injection of IL-5 or IL-10, but not IL-4, increased the number of antibody-producing peritoneal B-1 cells by four- to five-fold, resulting in increased anti-RBC serum autoantibody and induction of hemolytic anemia. These results suggest that IL-5 or IL-10 may play an important role in the terminal differentiation of B-1 cells into antibody-producing cells in vivo.

Interleukin-10 is a central regulator of the response to LPS in murine models of endotoxic shock and the Shwartzman reaction but not endotoxin tolerance

Previous studies in vivo have shown that IL-10 infusion can prevent lethal endotoxic shock. Mice deficient in the production of IL-10 (IL10T) were used to investigate the regulatory role of IL-10 in the responses to LPS in three experimental systems. In a model of acute endotoxic shock, it was found that the lethal dose of LPS for IL10T mice was 20-fold lower than that for wild type (wt) mice suggesting that endogenous IL-10 determines the amount of LPS which can be tolerated without death. The high mortality rate of IL10T mice challenged with modest doses of LPS was correlated to the uncontrolled production of TNF as treatment with anti-TNF antibody (Ab) resulted in 70% survival. Additional studies suggested that IL-10 mediates protection by controlling the early effectors of endotoxic shock (e.g., TNF alpha) and that it is incapable of directly antagonizing the production and/or actions of late appearing effector molecules (e.g., nitric oxide). We also found that IL10T mice were extremely vulnerable to a generalized Shwartzman reaction where prior exposure to a small amount of LPS primes the host for a lethal response to a subsequent sublethal dose. The priming LPS dose for IL10T mice was 100-fold lower than that required to prime wt mice implying that IL-10 is important for suppressing sensitization. In agreement with this assumption, IL-10 infusion was found to block the sensitization step. Interestingly, IL-10 was not the main effector of endotoxin tolerance as IL10T mice could be tolerized to LPS. Furthermore, IL-10 infusion could not substitute for the desensitizing dose of LPS. These results show that IL-10 is a critical component of the host's natural defense against the development of pathologic responses to LPS although it is not responsible for LPS-induced tolerance.

Time course of cytokine levels in sepsis

In severe sepsis, a network of proinflammatory cytokines (TNF, IL-1 beta, IL-6, IL-8) is activated and blood levels of these cytokines are elevated, albeit inconsistently and with large individual variations. In addition, elevated blood levels of anti-inflammatory cytokines (IL-10), as well as of soluble cytokine receptors (sTNF-RI and II, IL-1ra), have been found. They seem to have a regulatory function in the host response. Levels of TNF and IL-6 are usually highest at the time of admission, whereas the time course of IL-1 beta levels (when detectable) can vary considerably. Limited data on IL-8 levels suggest that they may remain elevated for longer periods. Elevated levels of sTNFR and IL-1ra may also persist for a prolonged period of time. The pathogenetic significance of these observations is still unclear, but persistingly high levels of proinflammatory cytokines may be associated with organ failure and mortality.

Immunosuppressive and anti-inflammatory properties of interleukin 10

Interleukin 10 (IL-10) indirectly prevents antigen-specific T-cell activation, which is associated with downregulation of the antigen presentation and accessory cell functions of monocytes, macrophages, Langerhans cells and dendritic cells. In addition, IL-10 inhibits T-cell expansion by directly inhibiting IL-2 production by these cells. These properties of IL-10, together with its capacity to downregulate the production of proinflammatory cytokines and chemokines by activated monocytes, polymorphonuclear leucocytes and eosinophils, indicate that IL-10 is a potent immunosuppressant in vitro. IL-10 has similar activities in vivo. It inhibits lipopolysaccharide or staphylococcal enterotoxin B induced lethal shock in mice. In addition, IL-10 deficient mice develop chronic inflammatory bowel disease, which could be reduced, or prevented by IL-10 treatment. IL-10 also prevented the development of colitis in a SCID mouse model. Collectively, these data indicate that IL-10 has great potential therapeutical utility in the treatment of diseases, such as chronic inflammation, autoimmune diseases, transplant rejection, graft-versus-host disease and sepsis.

Lipopolysaccharide-induced interleukin-10 in mice: role of endogenous tumor necrosis factor-alpha

Interleukin (IL)-10 is known to protect mice against the lethal effects of lipopolysaccharides (LPS) and is considered to be an anti-inflammatory cytokine which suppresses the production of pro-inflammatory cytokines. We have examined the interactions of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) with IL-10. Neutralization of TNF-alpha in murine bone marrow-derived macrophages resulted in a significant reduction of LPS-inducible IL-10 production. In mice, injection of 5 mg/kg LPS induced circulating IL-10 with a biphasic time course exhibiting an early peak 1.5 h after challenge (synchronous with TNF-alpha) and, after a nadir at 6 h, a second increase between 8 and 12 h. Treatment of mice with neutralizing anti-mouse TNF-alpha antiserum significantly increased LPS-induced IL-10 plasma levels between 1.5 and 6 h but diminished those at 12 h, while circulating IL-6, interferon-gamma (IFN-gamma) and granulocyte colony-stimulating factor (G-CSF) concentrations were attenuated overall, without a biphasic response. Analysis of LPS-induced IL-10 mRNA expression in different tissues 1 h and 8 h after LPS or LPS plus anti-TNF-alpha revealed that the amount of transcripts in the liver correlated with circulating early and late IL-10 levels. Our findings suggest that endogenous TNF-alpha down-regulates the early and up-regulates the late LPS-induced IL-10 synthesis in vivo and that the liver is the major source of circulating IL-10 after stimulation with LPS.

Enhancement of endotoxin-induced interleukin-10 production by SR 31747A, a sigma ligand

SR 31747A is a new sigma ligand eliciting immunosuppressive and anti-inflammatory properties. Here, we show that SR 31747A greatly enhances lipopolysaccharide (LPS)-induced systemic release of interleukin (IL)-10, while it inhibits the secretion of tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. In line with this finding, we also show by using quantitative reverse transcription-polymerase chain reaction analysis that SR 31747A increased LPS-induced IL-10 mRNA accumulation in spleen cells, whereas the level of both TNF-alpha and IFN-gamma mRNA was dramatically decreased. The enhancement of IL-10 production by SR 31747A treatment was also apparent in nude and severe-combined immunodeficient mice treated with LPS, clearly indicating that T and B cells were not involved. Finally, SR 31747A conferred protection against the lethal effect of LPS. The finding that SR 31747A strongly stimulates the synthesis of the natural anti-inflammatory cytokine IL-10, a property not observed with dexamethasone, provides new insights for the clinical use of this original compound, particularly in chronic inflammatory diseases where IL-10 is believed to be a pivotal regulatory component.

Altered Th1/Th2 cytokine profiles in the intestinal mucosa of patients with inflammatory bowel disease as assessed by quantitative reversed transcribed polymerase chain reaction (RT-PCR)

Cytokines serve a central function as key factors in the regulation of the intestinal immune response and mediation of tissue damage in inflammatory bowel disease (IBD). Abnormalities in the expression of immunoregulatory cytokines such as IL-2, IL-4, IL-10 and interferon-gamma (IFN-gamma) may indicate a dysregulation of intestinal immunity probably associated with pathogenic events. Therefore, cytokine mRNA concentrations were determined in the mucosa of patients with IBD at sites of active (n = 13) and inactive (n = 12) ulcerative colitis (UC), active (n = 11) and inactive (n = 11) Crohn's disease (CD) and in control patients (n = 14) using quantitative RT-PCR. IL-10 mRNA concentrations were significantly increased in patients with both active UC (P < 0.001) and active CD (P < 0.005) compared with control patients. IFN-gamma mRNA concentrations were also significantly increased both in patients with active UC (P < 0.02) and active CD (P < 0.05) compared with control patients, whereas IL-2 mRNA levels were significantly (P < 0.02) increased only in active CD. IL-4 mRNA expression in the intestinal mucosa was frequently below the detection limit. Our results demonstrate that chronic intestinal inflammation in patients with CD is characterized by an increase of Th1-like cytokines. Furthermore, the increased IL-10 mRNA expression at sites of active IBD suggests that IL-10 is an important regulatory component involved in the control of the inflammatory response in inflammatory bowel disease.

Clinical and biological significance of interleukin-10 plasma levels in patients with septic shock

Interleukin-10 is a potent macrophage-deactivating cytokine that inhibits lipopolysaccharide-induced tumor necrosis factor production. We determined the plasma levels of immunoreactive interleukin-10 in 16 patients with septic shock and in 11 patients with circulatory shock of nonseptic origin. In septic shock, interleukin-10 levels peaked during the first 24 h (median: 48 pg/ml) and decreased progressively till Day 5. In nonseptic shock, interleukin-10 plasma levels also increased during the first 24 h but to a lesser extent (median: 17 pg/ml). In septic shock patients, interleukin-10 plasma levels were positively correlated with tumor necrosis factor (r = 0.8, p = 0.01) and with parameters of shock severity including lactate levels (r = 0.56, p < 0.05) and correlated negatively with blood platelet counts (r = -0.65, p < 0.05). The decreased production of tumor necrosis factor-alpha and interleukin-6 after in vitro incubation of whole blood from septic shock patients with lipopolysaccharide was not influenced by in vitro neutralization of interleukin-10. We conclude that interleukin-10 is produced in patients with circulatory shock of septic and nonseptic origin and that the production of this anti-inflammatory cytokine during septic shock correlates positively with the intensity of the inflammatory response.

Tumor necrosis factor alpha upregulates human microglial cell production of interleukin-10 in vitro

Interleukin (IL)-10 appears to play an important regulatory role in the systemic inflammatory response; however, production of IL-10 within the human central nervous system has not been described. Using cultures of human fetal microglial cells, the resident macrophages of the brain, we investigated the production and regulation of bioactive IL-10. Lipopolysaccharide stimulated acute release of tumor necrosis factor (TNF)-alpha (peak by 8 h) and delayed production of IL-10 (over a 48-h period) in microglial cell cultures. Treatment of microglial cell cultures with TNF-alpha and IL-6 resulted in a dose-dependent release of IL-10. These cytokines also induced expression of IL-10 mRNA. Treatment of microglial cell cultures with IL-10 markedly inhibited TNF-alpha and IL-6 production. These findings suggest that during inflammation within the brain, acute release of TNF-alpha and IL-6 by activated microglia could promote subsequent release of IL-10, which functions to minimize the potential neurotoxic effects of proinflammatory cytokines.

Polymicrobial sepsis following trauma inhibits interleukin-10 secretion and lymphocyte proliferation

Immune competence declines following major injury, and predisposes the trauma patient to infection. Interleukin-10 (IL-10), although an immunosuppressive cytokine, is also important in the initiation of immune responses. This study investigated alterations in IL-10 and immune function associated with polymicrobial sepsis following trauma using murine femur fracture (FFx) and cecal ligation/puncture (CLP) models. Mice were randomized to Normal, FFx, Alcohol and FFx (EtOH + FFx), CLP, FFx + CLP, and EtOH + FFx + CLP. Polymicrobial sepsis was induced by performing CLP 4 days after FFx, and animals were killed 14 days later; immune function was assessed by in vitro splenocyte cultures. Lymphocyte proliferative responses were significantly suppressed in FFx and CLP animals. Splenocyte IL-10 production was significantly reduced in FFx and CLP animals, with concurrent increases in nitrite and tumor necrosis factor release. This study documents that trauma induces alterations in the inflammatory cytokine cascade that affect the immune response to subsequent septic challenges.

Effects of in vivo administration of anti-IL-10 monoclonal antibody on the host defence mechanism against murine Salmonella infection

Interleukin-10 (IL-10) is a cytokine that regulates various macrophage functions. To elucidate the involvement of endogenous IL-10 in the early stage of murine salmonellosis, we examined the effect of anti-IL-10 monoclonal antibody (mAb) administration on the host defence mechanism against Salmonella choleraesuis infection. The in vivo administration of anti-IL-10 mAb significantly enhanced host resistance at the early stage of Salmonella infection, as assessed by bacterial growth in the peritoneal cavity and the liver. Enhanced levels of monokine mRNA, including IL-1 alpha, tumour necrosis factor-alpha (TNF-alpha) and IL-12, were observed from day 1 after infection in the peritoneal macrophages in anti-IL-10 mAb-treated mice compared with those in control mAb-treated mice. Mice treated with anti-IL-10 mAb exhibited significantly higher levels of interferon-gamma (IFN-gamma) in the peritoneal exudates and major histocompatibility complex (MHC) class II expression on the peritoneal macrophages on days 3 and 5 after infection. Notably, in vivo anti-IL-10 mAb brought about an increment of gamma delta T cells in the peritoneal cavity at the early phase of infection, which was correlated with the expression of endogenous heat-shock protein 60 (HSP60), which is implicated as a potential ligand for gamma delta T cells, in the infected macrophages. Our results suggest that the neutralization of endogenous IL-10 accelerates some macrophage functions and, consequently, the activation of immunocompetent cells, including gamma delta T cells, at the early stage of infection, resulting in an enhanced host defence against Salmonella infection.

Interleukin 10 reduces mortality from severe peritonitis in mice

Interleukin 10 (IL-10) is known to suppress the induction of proinflammatory cytokines such as tumor necrosis factor (TNF) and IL-1 and is itself induced by monocytes and macrophages during sepsis. We studied the therapeutic efficacy of IL-10 by testing its effect on the survival rate in the murine cecal ligation-and-puncture (CLP) model. Administration of 1 microgram or more of recombinant murine IL-10 6 h after induction of sepsis decreased lethality in septic mice significantly and also suppressed the elevation of circulating TNF after sepsis. However, treatment with the same dose of IL-10 simultaneously or 6 h before induction of CLP had no effect on survival, and treatment with anti-TNF antibody after induction of CLP had no effect on the survival rate. These data suggest that cytokine modulation with IL-10 is a potential candidate for the treatment of sepsis and sepsis-related multiple organ failure.

IL-10 augments CD23 expression on U937 cells and down-regulates IL-4-driven CD23 expression on cultured human blood monocytes: effects of IL-10 and other cytokines on cell phenotype and phagocytosis

The effects of human recombinant interleukin-10 (IL-14) on the expression of several markers on U937 and human peripheral blood monocytes was studied by immunofluorescence and fluorescence-activated cell sorter (FACS) analysis. IL-10 augmented Fc IgE receptor (Fc epsilon RII/CD23) further enhanced by cotreatment with IL-4 or interferon-gamma (IFN-gamma). In contrast, the basal level of Fc epsilon RII expression on blood monocytes appeared to fall in response to IL-10, and this effect became more evident on IL-4-treated cells. Furthermore, the constitutive and IFN-gamma-triggered Fc gamma RI/CD64 expression was augmented on both monocytes and U937 cells. Thus the expression of Fc gamma RII/CD32, Fc gamma/RIII/CD16, Fc alpha R/CD89, the receptor for complement components (CR1/CD35, CD3/CD11b, CR4/CD11c) and the receptor for transferrin/CD71 was not significantly influenced on IL-10-treated cells. IL-10 modestly triggered CD14 antigen expression on monocytes but not U937. The expression of intercellular adhesion molecule-1 (ICAM-1)/CD54 on monocytes was significantly inhibited by IL-10. As expected, a marked reduction of the constitutive as well as of the IFN-gamma or IL-4-driven expression on HLA-DR, HLA-DP and HLA-DQ was observed on IL-10-cultured monocytes. On the other hand, the expression of major histocompatibility complex (MHC) class I molecules was slightly and dose-dependently induced on IL-10-treated monocytes. The ability of blood monocytes to phagocytose IgG-sensitized ox erythrocytes, and to bind and ingest opsonized Escherichia coli or latex particles, was amplified by IL-10. Our data demonstrate that IL-10 modulates the expression of a wide variety of structures on human mononuclear phagocytes, and augments their phagocytic capacity.

Interleukin 10 prevents necrosis in murine experimental acute pancreatitis

BACKGROUND/AIMS

Inflammatory events are believed to play an important role in the pathogenesis of acute pancreatitis. Interleukin 10 (IL-10) recently emerged as a major anti-inflammatory cytokine, inhibiting the secretion of proinflammatory cytokines by monocytes and/or macrophages. The potential protective role of IL-10 in a model of acute necrotizing pancreatitis in mice was tested.

METHODS

Animals received two intraperitoneal injections of either 1000 U recombinant IL-10 or control supernatant before and during induction of acute pancreatitis with repeated cerulein injections (seven intraperitoneal injections of 50 micrograms/kg at hourly intervals).

RESULTS

Systemic amylase and lipase release peaked 9 hours after the first cerulein injection. This peak was significantly reduced by IL-10 treatment. Histologically, edema and inflammation of the pancreas were observed in both groups, whereas necrosis was dramatically reduced in IL-10-treated animals. Serum tumor necrosis factor levels were undetectable in this model; reverse-transcriptase polymerase chain reaction analysis of resected pancreatic tissues performed at the time of maximal morphological alterations showed a dramatically decreased expression of tumor necrosis factor alpha messenger RNA after IL-10 treatment compared with control pancreatitis.

CONCLUSIONS

IL-10 is able to decrease the severity of experimental acute pancreatitis, mainly by inhibiting the development of acinar necrosis. Inhibition of local tumor necrosis factor alpha might explain, at least in part, the protective effect of IL-10.

Human tumor necrosis factor receptor (p55) and interleukin 10 gene transfer in the mouse reduces mortality to lethal endotoxemia and also attenuates local inflammatory responses

Anticytokine therapies have been promulgated in gram-negative sepsis as a means of preventing or neutralizing excessive production of proinflammatory cytokines. However, systemic administration of cytokine inhibitors is an inefficient means of targeting excessive production in individual tissue compartments. In the present study, human gene transfer was used to deliver to organs of the reticuloendothelial system antagonists that either inhibit tumor necrosis factor-alpha (TNF-alpha) synthesis or block its interactions with cellular receptors. Mice were treated intraperitoneally with cationic liposomes containing 200 micrograms of either a pCMV (cytomegalovirus)/p55 expression plasmid that contains the extracellular domain and transmembrane region of the human p55 TNF receptor, or a pcD-SR-alpha/hIL-10 expression plasmid containing the DNA for human interleukin 10. 48 h later, mice were challenged with lipopolysaccharide (LPS) and D-galactosamine. Pretreatment of mice with p55 or IL-10 cDNA-liposome complexes improved survival (p < 0.01) to LPS-D-galactosamine. In additional studies, intratracheal administration of IL-10 DNA-liposome complexes 48 h before an intratracheal LPS challenge reduced pulmonary TNF-alpha levels by 62% and decreased neutrophil infiltration in the lung by 55% as measured by myeloperoxidase activity (both p < 0.05). Gene transfer with cytokine inhibitors is a promising option for the treatment of both the systemic and local sequelae of septic shock.

High levels of interleukin 10 in serum are associated with fatality in meningococcal disease

Interleukin 10 (IL-10) suppresses the production of proinflammatory cytokines in vitro and in murine models of endotoxemia and has been suggested as a candidate for treatment of bacterial septicemia. To investigate the role of IL-10 in meningococcal disease, a sandwich IL-10 enzyme-amplified sensitivity immunoassay was used to quantitate IL-10 in serum and cerebrospinal fluid samples from 41 patients with meningococcal bacteremia or meningitis with or without septic shock. High levels of IL-10 were demonstrated in sera from patients with meningococcal septic shock (mean, 21,221 pg/ml; range, 25 to 64,500 pg/ml). All cases involving fatalities had IL-10 levels in serum of > or = 1,000 pg/ml (mean, 23,058 pg/ml; range, 1,000 to 64,500 pg/ml). Patients with meningococcal meningitis without septic shock had comparably low concentrations of IL-10 in serum (mean, 119 pg/ml; range, 0 to 1,050 pg/ml) but exhibited compartmentalized release of IL-10 in cerebrospinal fluid. Concentrations of IL-10 in serum were positively correlated with the previously reported concentrations of tumor necrosis factor alpha, IL-6, and IL-8 in serum in the same patients. We conclude that IL-10 is extensively activated along with the proinflammatory cytokines during the initial phase of meningococcal septic shock and that IL-10 is associated with fatality in meningococcal disease.

Interleukin-10 inhibits antigen-induced cellular recruitment into the airways of sensitized mice

This report examines the effect of recombinant murine (rm) IL-10 on antigen-induced cellular recruitment into the airways of sensitized Balb/c mice. The intranasal instillation of 10 micrograms ovalbumin induced an early (6-24 h) increase in the number of neutrophils, and a late rise (24-96 h) in that of eosinophils in the bronchoalveolar lavage (BAL) fluid and bronchial tissue. A single intranasal instillation of 0.01-0.1 microgram of rmIL-10, administered concurrently with ovalbumin, but not 1 or 3 h thereafter, dose-dependently inhibited both airway neutrophilia and eosinophilia. This phenomenon was suppressed by treating the sensitized mice with 1 mg/mouse of a neutralizing anti-IL-10 mAb, which increased significantly ovalbumin-induced neutrophil and eosinophil accumulation in the BAL fluid. These results suggest that antigen stimulation may trigger the in vivo generation of IL-10, which, in turn, participates in the leukocyte infiltration into the airways. rmIL-10 also reduced TNF-alpha release in the BAL fluid observed 1 and 3 h after antigen challenge. Furthermore, the intranasal instillation of an anti-TNF-alpha antiserum to sensitized mice markedly reduced ovalbumin-induced neutrophil and eosinophil accumulation in the BAL fluid. These findings indicate that leukocyte infiltration into the airways of antigen-challenged mice is regulated by IL-10. Furthermore, inhibition of TNF-alpha production by rmIL-10 suggests that allergic airway inflammation and TNF-alpha formation are parallel events in this model.

Prolongation of skin allografts by recombinant tumor necrosis factor and interleukin-1

OBJECTIVE

The hypothesis is that systemic administration of recombinant tumor necrosis factor-alpha (TNF-alpha) and/or recombinant interleukin-1 alpha (IL-1 alpha) can decrease the rejection of a skin allograft.

SUMMARY BACKGROUND DATA

Tumor necrosis factor and IL-1 are pluripotent cytokine hormones that are central to the host immunologic response to foreign substances. Cytokine effects and toxicity may be reduced by systemic administration of recombinant cytokines. The authors previously have demonstrated that pretreatment with cytokines such as IL-1 or TNF can reduce the lethality of endotoxin (lipopolysaccharide), gram-negative sepsis, cancer cachexia, and oxygen toxicity.

METHODS

Skin grafts from the tails of Balb/c mice were placed on the backs of C57Bl/6 mice. Mice were treated with daily intraperitoneal saline, recombinant m-TNF (Genentech, South San Francisco, CA) or h-IL-1 (Hoffman LaRoche, Nutley, NJ) from postgraft day 1 to postgraft day 28. Tumor necrosis factor and IL-1 high doses were chosen because they protected mice from the lethality of lipopolysaccharide. Animals were examined daily for toxicity and graft rejection. Graft survival was plotted in a Kaplan-Meier plot and analyzed by the log-rank test. Comparison of proportions was done using the Fisher's exact test.

RESULTS

Either TNF or IL-1 alone significantly prolonged skin graft survival compared with saline control. Furthermore, the combination of TNF and IL-1 prolonged skin graft survival longer than either cytokine alone. Mice on the highest dose TNF and IL-1 combination did not reject skin grafts during the 28-day treatment period. Significant toxicity was associated with cytokine treatment. Similar significant proportions of death occurred with IL-1 alone and the highest combination of TNF and IL-1.

CONCLUSION

Both TNF and IL-1 can be effective as suppressors of skin allograft rejection in mice.

Mechanism of endotoxin desensitization: involvement of interleukin 10 and transforming growth factor beta

Tolerance of monocytes/macrophages to endotoxin (lipopolysaccharide [LPS]) can be induced both in vivo and in vitro by LPS itself. Exposure to LPS, even at a very low dose, induces a downregulation of cytokine response to a second high dose LPS challenge. To learn more about the unknown mechanisms of this phenomenon, we studied the role of antiinflammatory cytokines in this process. Preculture of human peripheral blood monocytes for 24 hours with low concentrations of LPS induced hyporesponsiveness to high-dose LPS rechallenge with respect to tumor necrosis factor (TNF) alpha and interleukin (IL) 10 but not IL-1RA production. These results suggest that LPS tolerance reflects a functional switch of monocytes rather than a general LPS hyporesponsiveness. IL-10 and transforming growth factor (TGF) beta 1 showed additive effects in replacing LPS for induction of LPS hyporesponsiveness in vitro. Additionally, neutralizing anti-IL-10 and anti-TGF-beta monoclonal antibodies prevented induction of LPS tolerance. In vitro induced LPS tolerance looks like the ex vivo LPS hyporesponsiveness of monocytes from septic patients with fatal outcome: downregulation of LPS-induced TNF-alpha and IL-10 production but not of IL-1RA secretion. LPS hyporesponsiveness in septic patients was preceded by expression of IL-10 at both the mRNA and protein level. In summary, our data suggests that IL-10 and TGF-beta mediate the phenomenon of LPS tolerance in vitro and perhaps in vivo (septic patients), too.

Immunoregulatory role of interleukin 10 in patients with inflammatory bowel disease

BACKGROUND/AIMS

Active inflammatory bowel disease (IBD) is associated with increased proinflammatory cytokines. Deficiency of interleukin (IL) 10, a contrainflammatory cytokine, leads to the development of colitis in IL-10 knockout mice. We characterized IL-10 regulation of proinflammatory cytokine (tumor necrosis factor [TNF] alpha and IL-1 beta) expression in IBD in vitro and in vivo.

METHODS

IL-10 regulation of IL-1 beta, TNF-alpha, and IL-1 receptor antagonist expression by peripheral monocytes or isolated lamina propria mononuclear cells (LPMNC), respectively, was studied by enzyme-linked immunosorbent assay (cytokine secretion) and by semiquantitative reverse-transcription polymerase chain reaction.

RESULTS

IL-10 down-regulates IL-1 beta and TNF-alpha secretion as well as messenger RNA levels in IBD peripheral monocytes and LPMNC in a dose-dependent manner. In parallel, IL-1 receptor antagonist secretion is induced, and IL-10 can restore diminished in vitro IL-1 receptor antagonist/IL-1 beta ratios in IBD to normal levels. Equal concentrations of IL-10 are detectable in both normal and IBD intestinal lamina propria biopsy homogenates. After topical IL-10 enema treatment of three steroid therapy-refractory patients with ulcerative colitis, in vitro release of proinflammatory cytokines from IBD peripheral monocytes as well as LPMNC is dramatically down-regulated.

CONCLUSIONS

IL-10 down-regulates the enhanced secretion as well as messenger RNA levels of proinflammatory cytokines by IBD mononuclear phagocytes in vitro. In vivo topical application of IL-10 induces down-regulation of proinflammatory cytokine secretion both systemically and locally.

Differential role of interferon-gamma in the potentiating effect of muramyl peptides for enhanced responses to lipopolysaccharide in mice: effect of cyclosporin A

Cyclosporin A (CsA) administration reduced mortality in mice sensitized to endotoxic toxicity by various agents, such as muramyl dipeptide (MDP) or a lipophilic derivative. CsA is an inhibitor of a variety of T cell responses, suggesting that muramyl peptides could influence LPS-induced effects via the release of lymphokine. The potentiation of TNF production by pretreatment with muramyl peptides was comparable in nude mice and in controls, indicating that it is a T-independent mechanism, and CsA produced a similar inhibition in both groups. Neutralizing antibody to IFN-gamma did not change the elevated TNF level obtained in the blood when LPS was given after a muramyl peptide. However, the same treatment with anti-IFN-gamma MAb prevented the death of mice challenged with LPS plus MDP or plus a lipophilic derivative displaying similar effects. In comparing three selected muramyl peptides, we also show that the priming effect could be dissociated from the toxic synergism with LPS.