Dichotomy between Lactobacillus rhamnosus and Klebsiella pneumoniae on dendritic cell phenotype and function

The reaction of the intestinal immune system to intestinal bacteria shows striking differences between various bacterial strains. Whereas Klebsiella pneumoniae induces a fierce proinflammatory reaction, the probiotic strain Lactobacillus rhamnosus has clear anti-inflammatory effect in gastrointestinal disease and allergy. The molecular basis for this dichotomy is poorly understood but is likely to involve different modulation of antigen-presenting dendritic cells (DC) by L. rhamnosus and K. pneumoniae. Hence we evaluated phenotypic and functional characteristics of DC matured in the presence of L. rhamnosus and K. pneumoniae. Monocyte-derived immature DC were cultured in the presence of live bacteria to obtain mature DC. Both micro-organisms induced maturation of immature DC as shown by CD83 and CD86 expression, but receptors involved in activation of Th1 cells were expressed predominantly on DC exposed to K. pneumoniae. In contrast to K. pneumoniae, maturation with L. rhamnosus resulted in lower TNF-alpha, IL-6, and IL-8 production by immature DC and lower IL-12 and IL-18 production by mature DC. Moreover, L. rhamnosus led to the development of T cells without a typical Th phenotype whereas K. pneumoniae induced a Th1 immune response, dependent mainly on IL-12 production. Thus our results strongly support the concept that differential modulation of DC explains the differences in the immune response to various bacterial strains and indicates that K. pneumoniae induces Th1 immune responses via DC.

[Biological properties of interleukin 18]

IL-18 was first described in 1989 and since its properties have been recognized, an interest in it is constantly growing. IL-18 induces synthesis and release of interferon gamma (IFN-gamma), interleukins 8, 4 and 13, tumor necrosis factor alpha (TNF-alpha) and granulocyte/macrophage colony stimulating factor (GM-CSF). Thus, it modulates the function of many immunocompetent cells: macrophages, monocytes, lymphocytes and granulocytes. Another important feature of IL-18 is its ability to induce apoptosis of many cell types by inducing Fas ligand and Fas receptor, and granzymes. IL-18 seems to be particularly attractive as a highly specific marker of Th1-response and a potential element of complex antitumor therapy. In paper, the processes of synthesis, releasing and biological properties of IL-18 are reviewed, particularly in the aspects of immunomodulatory and antitumor activity.

Timing of IFN-beta exposure during human dendritic cell maturation and naive Th cell stimulation has contrasting effects on Th1 subset generation: a role for IFN-beta-mediated regulation of IL-12 family cytokines and IL-18 in naive Th cell differentiation

Type I IFNs, IFN-alpha and IFN-beta, are early effectors of innate immune responses against microbes that can also regulate subsequent adaptive immunity by promoting antimicrobial Th1-type responses. In contrast, the ability of IFN-beta to inhibit autoimmune Th1 responses is thought to account for some of the beneficial effects of IFN-beta therapy in the treatment of relapsing remitting multiple sclerosis. To understand the basis of the paradoxical effects of IFN-beta on the expression of Th1-type immune responses, we developed an in vitro model of monocyte-derived dendritic cell (DC)-dependent, human naive Th cell differentiation, in which one can observe both positive and negative effects of IFN-beta on the generation of Th1 cells. In this model we found that the timing of IFN-beta exposure determines whether IFN-beta will have a positive or a negative effect on naive Th cell differentiation into Th1 cells. Specifically, the presence of IFN-beta during TNF-alpha-induced DC maturation strongly augments the capacity of DC to promote the generation of IFN-gamma-secreting Th1 cells. In contrast, exposure to IFN-beta during mature DC-mediated primary stimulation of naive Th cells has the opposite effect, in that it inhibits Th1 cell polarization and promotes the generation of an IL-10-secreting T cell subset. Studies with blocking mAbs and recombinant cytokines indicate that the mechanism by which IFN-beta mediates these contrasting effects on Th1 cell generation is at least in part by differentially regulating DC expression of IL-12 family cytokines (IL-12 and/or IL-23, and IL-27) and IL-18.

Expression of IL-18 in patients with head and neck squamous cell carcinoma

Interleukin-18 (IL-18), a recently described cytokine secreted mainly by macrophages, stimulates interferon-gamma (IFN-gamma) production by natural killer cells and T cells. The purpose of this study was to determine tissue expression and serum levels of IL-18 in head and neck squamous cell carcinoma (HNSCC) and to evaluate ethanol and endotoxin-driven cytokine secretion. In 24 patients with primary HNSCC and 28 healthy controls, PBMC were isolated and incubated with 50 mM ethanol, LPS (doses 25 ng/ml, 250 ng/ml, 2500 ng/ml) and both agents for 24 h. Levels of IL-18 in serum, and cell supernatants were analysed by capture ELISA, IL-18 tissue level by immunoblotting. Serum levels of IL-8, IL-10 and IL-12, IFN-gamma, and endotoxin plasma levels were also determined. Statistical analysis involved Welch t-test and Page's test for trend. The majority of patients with HNSCC had high concentrations of serum IL-18. The level of IL-18 in the sera of these patients had a mean level of 271.7 pg/ml, while the mean IL-18 serum level in healthy controls was 174,0 pg/ml (p<0.001). Levels of IL-10 and IL-12, IFN-gamma were not increased in patients. Endotoxin was not detectable in either group. LPS stimulated dose-dependently IL-18 secretion from PBMC of patients and controls in vitro (p<0.05). Incubation with ethanol alone did not affect basal IL-18 secretion, but ethanol reduced LPS-stimulated IL-18 secretion compared to LPS stimulation alone. The mRNA expression of IL-18 in unstimulated PBMC and the response of PBMC to ethanol and LPS was similar in patients and controls. Our data on elevated serum levels of IL-18 in the majority of HNSCC cancer patients, irrespective of its biological activity, suggest that serum IL-18 might be a candidate for a new marker for HNSCC. The pathways for IL-18 production and its mechanisms of action in patients with HNSCC remain to be determined. Understanding of the immunological pathways might offer new therapeutic options in head and neck cancer in the future.

The Essential Involvement of Cross-Talk between IFN-γ and TGF-β in the Skin Wound-Healing Process

Several lines of in vitro evidence suggest the potential role of IFN-gamma in angiogenesis and collagen deposition, two crucial steps in the wound healing process. In this report, we examined the role of IFN-gamma in the skin wound healing process utilizing WT and IFN-gamma KO mice. In WT mice, excisional wounding induced IFN-gamma mRNA and protein expression by infiltrating macrophages and T cells, with a concomitant enhancement of IL-12 and IL-18 gene expression. Compared with WT mice, IFN-gamma KO mice exhibited an accelerated wound healing as evidenced by rapid wound closure and granulation tissue formation. Moreover, IFN-gamma KO mice exhibited enhanced angiogenesis with augmented vascular endothelial growth factor mRNA expression in wound sites, compared with WT mice, despite a reduction in the infiltrating neutrophils, macrophages, and T cells. IFN-gamma KO mice also exhibited accelerated collagen deposition with enhanced production of TGF-beta1 protein in wound sites, compared with WT mice. Furthermore, the absence of IFN-gamma augmented the TGF-beta1-mediated signaling pathway, as evidenced by increases in the levels of total and phosphorylated Smad2 and a reciprocal decrease in the levels of Smad7. These results demonstrate that there is crosstalk between the IFN-gamma/Stat1 and TGF-beta1/Smad signaling pathways in the wound healing process.

Modification of phagocytosis and cytokine production in peritoneal and splenic murine cells by erythromycin A, azithromycin and josamycin

OBJECTIVES

The aim of this study was to determine whether pre-incubation of peritoneal or splenic cells with different doses of the macrolides erythromycin A (14-membered ring), azithromycin (15-membered ring) and josamycin (16-membered ring) affects their phagocytic activity or cytokine production.

METHODS

Peritoneal and splenic cells from BALB/c mice were pre-incubated with different concentrations of these antibiotics, those similar to serum levels attained with the treatment schedules used in human therapy.

RESULTS

From our observations of phagocytic activity and IL-12 production by peritoneal cells, these macrolide antibiotics seem to act mainly as immunosuppressive agents, although they induce peritoneal cells to increase IL-18 production and splenic cells IL-4 production.

CONCLUSIONS

Macrolide antibiotics can interfere with the Th1 cell-amplifying activity of IL-18 in conjunction with IL-12 and, in contrast, may induce a Th2 cell response in an IL-4-dependent manner. These results could improve their therapeutic use especially in immunosuppressed patients.

[The effects of M-CSF and IL-10 on IL-12 and IL-18 production and expressions of HLA-DR and CD80 by human monocytes]

AIM

To explore the effects of M-CSF and IL-10 on IL-12 and IL-18 production and expressions of HLA-DR and CD80 by human peripheral blood monocytes.

METHODS

Human monocytes were isolated from blood of healthy donors, and cultured with M-CSF and or IL-10 alone or together. Then the monocytes and culture supernatant were collected respectively. IL-12 p40 and IL-18 levels in culture supernatant were detected by ELISA and the expressions of CD80 and HLA-DR on the monocytes were analyzed by FACS.

RESULTS

(1)M-CSF induced secretion of IL-18 by the monocytes, while IL-10 inhibited the production of IL-18 and antagonized enhancement of LPS-induced IL-18 production by M-CSF. Both M-CSF and IL-10 inhibited secretion of IL-12 p40 by the monocytes and had a synegistic effect in the inhibition. (2)M-CSF could induce while IL-10 inhibited HLA-DR expression. Moreover, IL-10 had an antagonistic action on HLA-DR expression induced by M-CSF. M-CSF had no influence on CD80 expression, while IL-10 induced CD80 expression.

CONCLUSION

M-CSF and IL-10 can regulate IL-12 and IL-18 production and HLA-DR and CD80 expressions by human monocytes, which may affect the activation and differentiation of T cells and T cell-mediated immune response.

IL-13 gene expression in patients with atopic dermatitis: relation to IgE level and to disease severity

Atopic dermatitis (AD) is a chronic inflammatory skin disease frequently associated with an increased serum IgE level. T helper cells are thought to play an important role in the pathogenesis of AD. It is commonly believed that allergens activate Th2 cells, and it is likely that the cytokines produced by Th2 cells are crucial factors in the induction and maintenance of the disease. IL-13 is one of the cytokines that are produced by Th2 lymphocytes and, like IL-4, it can induce the production of IgE. In order to evaluate its role in the pathogenesis of AD, IL-13 mRNA expression was studied in peripheral blood of patients with different degrees of AD and compared with healthy subjects. Also, we correlated its level of expression with the level of serum IgE and with the severity of the disease. EDTA blood was obtained from 25 patients (divided into three groups ranged from mild to severe AD) and 12 normal subjects as a control group. We examined the blood sample for IL-13 mRNA expression using RNA extraction technique, RT-PCR, PCR amplification using primers specific for IL-13 and beta- actin (as internal control) this is followed by visualization of the expressed bands using gel electrophoresis and DNA marker. Serum IgE level was detected using an ELISA kit. Our results revealed that, IL-13 mRNA is significantly expressed in patients with AD as compared to normal control (P<0.001). IL-13 mRNA shows higher level of expression in severe AD group in comparison with both moderate and mild groups (P = 0.05). Serum levels of IgE showed highly significant increase in patients with AD as compared with the control group (p=0.019), its level is significantly higher in severe AD group versus moderate and mild AD groups (P=0.009 and 0.022, respectively). There is a highly significant positive correlation between serum levels of IgE and the levels of IL-13 mRNA expression in all AD groups (P=0.001). In conclusion, the high level of IL-18 mRNA expression in AD, and its correlation with serum level of IgE and with severity of disease indicates that IL-13 is involved in the pathogenesis of the disease and is an important in vivo IgE inducer.

Identification of a Critical Ig-Like Domain in IL-18 Receptor α and Characterization of a Functional IL-18 Receptor Complex

Steady state mRNA levels in various human tissues reveal that the proinflammatory cytokine IL-18 is constitutively and ubiquitously expressed. However, limited IL-18R alpha-chain (IL-18Ralpha) expression in tissues may restrict ligand-acting sites and contribute to a specific response for IL-18. To study the IL-18R complex, [(125)I]IL-18 was studied for binding to the cell surface receptors of IL-18-responsive NK and macrophagic KG-1 cells. After cross-linking, [(125)I]IL-18 formed three IL-18R complexes with sizes of approximately 93, 160, and 220 kDa. In KG-1 cells, Scatchard analysis revealed the presence of 135 binding sites/cell, with an apparent dissociation constant (K(d)) of 250 pM; in NK cells, there were 350 binding sites per cell with an apparent K(d) of 146 pM. Each domain of extracellular IL-18Ralpha was cloned and individually expressed in Escherichia coli. An mAb specifically recognized the membrane-proximal third domain; this mAb blocked IL-18-induced IFN-gamma production in NK cells. Furthermore, deletion of the membrane-proximal third domain of IL-18Ralpha prevented the formation of IL-18R ternary complex with IL-18R beta-chain. The present studies demonstrate that the biologically active IL-18R complex requires the membrane-proximal third Ig-like domain in IL-18Ralpha for the formation of IL-18R ternary complex as well as for signal transduction involved in IL-18-induced IFN-gamma in NK cells.

Identification of a truncated IL-18Rβ mRNA: a putative regulator of IL-18 expressed in rat brain

Interleukin (IL)-18, a member of the IL-1 family, is a key mediator of peripheral inflammation and host defense responses, and has been implicated in inflammatory and neurodegenerative diseases in the brain. IL-18 acts via a receptor complex that closely resembles that of IL-1, consisting of a ligand binding protein, IL-18Ralpha, and an accessory protein, IL-18Rbeta. Here, we describe the presence of a splice variant of IL-18Rbeta that is predicted to encode a truncated soluble protein, consisting of only the first immunoglobulin-like domain of IL-18Rbeta (EMBL/Genbank accession number AJ550893). Both forms of IL-18Rbeta were expressed in rat cortex, striatum, hypothalamus, hippocampus, and also liver, and were detected in pure cultures of microglia, astrocytes and neurons. This novel splice variant is up-regulated rapidly in microglial cells by bacterial lipopolyssacharide (LPS). We propose that this putative truncated form of IL-18Rbeta is analogous to the soluble form of IL-1R accessory protein, and could act as an important regulator of IL-18 actions.

Meal modulation of circulating interleukin 18 and adiponectin concentrations in healthy subjects and in patients with type 2 diabetes mellitus

BACKGROUND

A single high-fat meal induces endothelial activation, which is associated with increased serum concentrations of inflammatory cytokines.

OBJECTIVE

We compared the effect of 3 different meals on circulating concentrations of interleukin 8 (IL-8), interleukin 18 (IL-18), and adiponectin in healthy subjects and in patients with type 2 diabetes mellitus.

DESIGN

Thirty patients with newly diagnosed type 2 diabetes and 30 matched, nondiabetic subjects received the following 3 isoenergetic (780 kcal) meals separated by 1-wk intervals: a high-fat meal; a high-carbohydrate, low-fiber (4.5 g) meal; and a high-carbohydrate, high-fiber meal in which refined-wheat flour was replaced with whole-wheat flour (16.8 g). We analyzed serum glucose and lipid variables and serum IL-8, IL-18, and adiponectin concentrations at baseline and at 2 and 4 h after ingestion of the meals.

RESULTS

Compared with nondiabetic subjects, diabetic patients had higher fasting IL-8 (P < 0.05) and IL-18 (P < 0.01) concentrations and lower adiponectin concentrations (P < 0.01) at baseline. In both nondiabetic and diabetic subjects, IL-18 concentrations increased and adiponectin concentrations decreased (P < 0.05) from baseline concentrations after consumption of the high-fat meal. After consumption of the high-carbohydrate, high-fiber meal, serum IL-18 concentrations decreased from baseline concentrations (P < 0.05) in both nondiabetic and diabetic subjects; adiponectin concentrations decreased after the high-carbohydrate, low-fiber meal in diabetic patients. IL-8 concentrations did not change significantly after consumption of any of the 3 meals.

CONCLUSIONS

This study provides evidence that circulating IL-18 and adiponectin concentrations are modulated by familiar foodstuffs in humans. Meal modulation of cytokines involved in atherogenesis may represent a safe strategy for ameliorating atherogenetic inflammatory activity in diabetic patients.

Regulatory effects of IL-12 and IL-18 on Onchocerca volvulus- and Entamoeba histolytica-specific cellular reactivity and cytokine profiles

In the present study, the cytokines interleukin (IL)-12 and IL-18 were evaluated for their capacity to modulate and to re-direct in vitro parasite antigen-specific cellular responsiveness in patients exposed to Onchocerca volvulus and Entamoeba histolytica infection. We found that IL-18 was highly capable of reducing parasite antigen-induced IL-10 production by PBMC. In contrast, addition or neutralization of IL-12, also in combination with IL-18 and the interferon-gamma-inducible chemokine IP-10 did not affect IL-10 production. Interestingly, the highest IL-10 levels were measured when IL-18 and IP-10 were both neutralized. Although having no effect on IL-10, IL-12 strongly promoted spontaneous and parasite antigen-driven IFN-gamma production by PBMC, whereas IL-18 was only moderately affecting IFN-gamma release by PBMC re-stimulated with E. histolytica- or O. volvulus-specific antigens. Both IL-12 and IL-18 diminished the cellular production of IL-13, and a synergistic effect was observed when the cytokines were combined. Likewise, neutralization of IL-12 enhanced Entamoeba and Onchocerca antigen-driven IL-13 production, but no further increase of IL-13 was observed, when anti-IL-12 and anti-IL-18 were used together. This study disclosed that IL-18 will significantly down-regulate parasite-specific IL-10 production, whereas IL-12 induced IFN-gamma and inhibited IL-13 production by PBMC from humans exposed to O. volvulus and E. histolytica. Such selective immune-regulatory capacity of IL-12 and IL-18 may comprise an important tool to re-direct polarized cytokine responses towards a balanced Th1/Th2 cytokine profile, which may prevent pathology and promote immunity against helminth and protozoan parasite infections.

Induction of an antitumor immunological response by an intratumoral injection of dendritic cells pulsed with genetically engineered Semliki Forest virus to produce interleukin-18 combined with the systemic administration of interleukin-12

OBJECT

The aim of this study was to investigate further immunogene treatment of malignant brain tumor to improve its therapeutic efficacy.

METHODS

Intratumoral dendritic cells pulsed with Semliki Forest virus (SFV)-interleukin-18 (IL-18) and/or systemic IL-12 were injected into mice bearing the B16 brain tumor. To study the immune mechanisms involved in tumor regression, we monitored the growth of implanted B16 brain tumor cells in T cell-depleted mice and IFNgamma-neutralized mice. To analyze the protective immunity created by tumor inoculation, B16 cells were injected into the left thighs of mice that had received an inoculation, and tumor growth was monitored. The local delivery of dendritic cells pulsed with IL-18 bound by SFV combined with the systemic administration of IL-12 enhanced the induction of the T helper type 1 response from tumor-specific CD4+ and CD8+ T cells and natural killer cells as well as antitumor immunity. Interferon-gamma is partly responsible for this IL-18-mediated antitumor immunity. Furthermore, the protective immunity is mediated mainly by CD8+ T cells.

CONCLUSIONS

Immunogene therapy that combines the local administration of dendritic cells pulsed with IL-18 bound by SFV and the systemic administration of IL-12 may be an excellent candidate for the development of a new treatment protocol. A self-replicating SFV system may therefore open a novel approach for the treatment of malignant brain tumor.

IL-18 cDNA vaccination protects mice from spontaneous lupus-like autoimmune disease

The lupus-like autoimmune syndrome of MRL/Mp-Tnfrsf6lpr (lpr) mice is characterized by progressive lymphadenopathy and autoantibody production, leading to early death from renal failure. Activation of T helper lymphocytes is one of the events in the pathogenesis of the disease in these mice and likely in human systemic lupus erythematosus. Among T helper lymphocyte-dependent cytokines, IFN-gamma plays a pivotal role in the abnormal cell activation and the fatal development of the lpr disease. IL-18, an inducer of IFN-gamma in T lymphocytes and natural killer cells, may contribute to the disease because cells from lpr mice are hypersensitive to IL-18 and express high levels of IL-18. To assess the contribution of IL-18 to the pathogenesis in the animal model, in vivo inhibition of IL-18 was attempted. Young lpr mice were vaccinated against autologous IL-18 by repeated administration of a cDNA coding for the murine IL-18 precursor. Vaccinated mice produced autoantibodies to murine IL-18 and exhibited a significant reduction in spontaneous lymphoproliferation and IFN-gamma production as well as less glomerulonephritis and renal damage. Moreover, mortality was significantly delayed in anti-IL-18-vaccinated mice. These studies support the concept that IL-18 plays a major role in the pathogenesis of the autoimmune syndrome of lpr mice and that a reduction in IL-18 activity could be a therapeutic strategy in autoimmune diseases.

IL-18 is produced by prostate cancer cells and secreted in response to interferons

Murine models have shown that IL-18 has antiangiogenic and antitumor effects, but little is known about IL-18 production in human tumors. We investigated IL-18 expression in clinically localized prostate cancers by immunohistochemistry and showed that 75% of the prostate cancers studied (27/36 cases) presented with tumor cells producing IL-18. Prostate tumor cell lines PC-3, DU 145 and LNCaP synthesized the immature form of IL-18 (p24). IFN-gamma produced in prostate cancers induced caspase-1 mRNA and IL-18 secretion of tumor cell lines, which was inhibited by the cell-permeable Tyr-Val-Ala-Asp-aldehyde caspase-1 inhibitor (YVAD-CHO). Interestingly, IFN-alpha also induced IL-18 secretion of the poorly differentiated cell line PC-3. PC-3 and DU 145, but not the well-differentiated cell line LNCaP, expressed IL-18R alpha (IL-1Rrp) protein and transcripts for IL-18R beta (AcPL). Exogenous IL-18 increased mitochondrial activity of both cell lines evaluated by the tetrazolium (MTT) assay but did not influence their proliferation. This indicated that prostate tumor cells could secrete IL-18 in response to IFN-gamma in the tumor microenvironment and that IL-18 could act as a autocrine/paracrine factor for the tumor. In the cohort of patients studied, IL-18 expression in prostate cancers (with up to 10% of tumor cells stained) was associated with a favorable outcome and equally predictive as pathologic stage on multivariate analysis (log rank test, p = 0.02). Tumor IL-18 production is a novel physiopathologic feature of prostate cancer and appears to be a favorable event in the course of the disease. Modulation of IL-18 production by interferons could have a beneficial clinical effect, which deserves further investigation.

Intratumoral delivery of dendritic cells engineered to secrete both interleukin (IL)-12 and IL-18 effectively treats local and distant disease in association with broadly reactive Tc1-type immunity

Dendritic cells (DCs) were adenovirally engineered to constitutively and durably secrete the potent Th1-biasing cytokines interleukin (IL)-12 (AdIL12DC) and/or IL-18 (AdIL18DC) and evaluated for their ability to promote therapeutic antitumor immunity in murine sarcoma models. Injection of either AdIL12DC or AdIL18DC into day 7 CMS4 or MethA tumors resulted in tumor rejection or slowed tumor growth when compared with control cohorts. Importantly, intratumoral injection with DCs engineered to secrete both IL-12 and IL-18 (AdIL12/IL18DC) resulted in complete and the most acute rejection of any treatment group analyzed. This strategy was also effective in promoting the regression of contralateral, untreated tumors. Both CD4+ and CD8+ T cells were required for tumor rejection. CD8+ splenic T cells from mice treated with AdIL12/IL18DC produced the highest levels of IFN-gamma in response to tumor rechallenge in vitro and displayed the broadest repertoire of Tc1-type reactivity to acid-eluted, tumor-derived peptides among all treatment cohorts. This apparent enhancement in cross-presentation of tumor-associated epitopes in vivo may result from the increased capacity of engineered DCs to kill tumor cells, survive tumor-induced apoptosis, and present immunogenic MHC/tumor peptide complexes to T cells after intratumoral injection. In support of this hypothesis, cytokine gene-engineered DCs expressed higher levels of MHC and costimulatory molecules, as well as Fas ligand and membrane-bound tumor necrosis factor alpha, with the latter markers associated with elevated tumoricidal activity in vitro. Cytokine gene-engineered DCs appeared to have a survival advantage in situ when injected into tumor lesions, to be found in approximation with regions of tumor apoptosis, and to have the capacity to ingest apoptotic tumor bodies. These results support the ability of combined cytokine gene transfer to enhance multiple effector functions mediated by intralesionally injected DCs that may concertedly promote cross-priming and the accelerated immune-mediated rejection of tumors.

RSV-induced bronchiolitis but not upper respiratory tract infection is accompanied by an increased nasal IL-18 response

The aim of this study was to investigate potential differences in the local nasal immune response between bronchiolitis and upper respiratory tract infection induced by respiratory syncytial virus (RSV). Nasal brush samples were obtained from 14 infants with RSV bronchiolitis and from 8 infants with RSV upper respiratory tract infection. The samples were taken during infection (acute phase) and 2-4 weeks later (convalescent phase). Cytospin preparations were stained immunohistochemically for T cells, macrophages, and eosinophils. Staining also took place for intercellular adhesion molecule-1 (ICAM-1), T-helper 1 (Th1)-like (interleukin-12 [IL-12], interferon-gamma [IFN-gamma]), Th2-like (IL-4, IL-10), and proinflammatory cytokines (IL-6, IL-8, IL-18). During both RSV-induced bronchiolitis and upper respiratory tract infection, cellular inflammation was observed. This was characterised by an increase in the numbers of nasal macrophages, which tended to be higher in bronchiolitis than in upper respiratory tract infection. Numbers of T lymphocytes and ICAM-1 positive cells increased during both bronchiolitis and upper respiratory tract infection. There were no differences between numbers in the groups. Interestingly, a distinct nasal proinflammatory cytokine response was observed in RSV-induced bronchiolitis. This is characterised by an increase in the number of IL-18 positive cells. This increase is specific for bronchiolitis, as a similar increase could not be detected in RSV-induced upper respiratory tract infection. Numbers of IL-6 and IL-12 positive cells were higher in both bronchiolitis and upper respiratory tract infection, and there were no differences between the groups. By contrast, the number of IL-8, IFN-gamma, IL-4, and IL-10-positive cells remained constant. In conclusion, clear differences were found in nasal immune responses of children with RSV-induced upper respiratory tract infection or bronchiolitis. The induction of a strong IL-18 response was typical for bronchiolitis, as this could not be observed in RSV-induced upper respiratory tract infection, and could explain the eosinophilia that is observed frequently during bronchiolitis.

Cimetidine treatment for viral warts enhances IL-2 and IFN-gamma expression but not IL-18 expression in lesional skin

Cimetidine has been shown to improve various types of human neoplasms and more recently it has been shown to be effective in treating recalcitrant or multiple viral warts in some reports. However, it is not well understood why cimetidine is effective on those kinds of viral warts. We investigated 55 patients with multiple viral warts treated only with oral cimetidine for up to 4 months to examine the efficacy of treatment. The patients were divided into two groups: group A received oral cimetidine (<20 mg/kg/day) and group B received the drug (30 to 40 mg/kg/day). In addition, using real time PCR, we measured mRNA levels of the cytokines interleukin-2 (IL-2), IL-18, and interferon (IFN)-gamma taken from selected punch biopsy specimens before and during treatment. As a result, 34.5% (19/55) of the patients had a dramatic clinical improvement or complete remission (CR) of their viral warts and 23.6% (13/55) of the patients had partial responses (PR) within 4 months of cimetidine therapy. IL-2 and IFN-gamma mRNA levels were significantly increased and IL-18 mRNA levels were decreased in tissues of effectively treated viral warts. Our results show that the higher dose of oral cimetidine was more effective in treating multiple viral warts, that cimetidine activates Th1 cells to produce IL-2 and IFN-c and that their expression correlates with wart remission. These results suggest that cimetidine is an effective treatment for viral warts. In addition, based on the decrease in IL-18 mRNA elicited by the drug, IL-18 might be expressed by keratinocytes infected with HPV.

Critical role for cathepsin B in mediating caspase-1-dependent interleukin-18 maturation and caspase-1-independent necrosis triggered by the microbial toxin nigericin

The potassium ionophore nigericin induces cell death and promotes the maturation and release of IL-1beta in lipopolysaccharide (LPS)-primed monocytes and macrophages, the latter depending on caspase-1 activation by an unknown mechanism. Here, we investigate the pathway that triggers cell death and activates caspase-1. We show that without LPS priming, nigericin alone triggered caspase-1 activation and IL-18 generation in THP-1 monocytic cells. Simultaneously, nigericin induced caspase-1-independent necrotic cell death, which was blocked by the cathepsin B inhibitor CA-074-Me and other cathepsin inhibitors. Cathepsin B activation after nigericin treatment was determined biochemically and corroborated by rapid lysosomal leakage and translocation of cathepsin B to the cytoplasm. IL-18 maturation was prevented by both caspase-1 and cathepsin B inhibitors in THP-1 cells, primary mouse macrophages and human blood monocytes. Moreover, IL-18 generation was reduced in THP-1 cells stably transformed either with cystatin A (an endogenous cathepsin inhibitor) or antisense cathepsin B cDNA. Collectively, our study establishes a critical role for cathepsin B in nigericin-induced caspase-1-dependent IL-18 maturation and caspase-1-independent necrosis.

Nuclear factor kappa B decoy oligodeoxynucleotides prevent endotoxin-induced fatal liver failure in a murine model

Endotoxin syndrome is a systemic inflammatory response mediated by inflammatory cytokines. Nuclear factor kappa B (NF-kappa B) is the dominant regulator of the production of these cytokines by inflammatory cells. The aim of this study was to assess the efficacy of in vivo transfer of synthetic double-stranded oligodeoxynucleotides (ODN) with high affinity against NF-kappa B (NF-kappa B/decoy/ODN) as a therapeutic strategy for treating endotoxin-induced fatal liver injury. Liver injury was induced by administration of lipopolysaccharide (LPS) to Propionibacterium acnes-primed BALB/C mice. NF-kappa B/decoy/ODN was transferred into the portal vein using a fusigenic liposome with hemagglutinating virus of Japan. NF-kappa B/decoy/ODN was preferentially transferred to Kupffer cells, and activation of NF-kappa B after the LPS challenge was suppressed, leading to decreased inflammatory cytokine production. As a result, the massive necrosis and hepatocyte apoptosis observed in the control mice was dramatically attenuated and the survival rate improved. In conclusion, NF-kappa B/decoy/ODN transfer in vivo effectively suppressed endotoxin-induced fatal liver injury in mice.

Implantation: can immunological parameters of implantation failure be of interest for pre-eclampsia?

We restate briefly why we consider that the Th1/Th2 paradigm, as useful as it has been, is now no longer adequate and is obsolete. We take as an example the role of IL-18, abortifacient at high doses but cardinal for the control of natural killer (NK) cell effects on spiral artery remodelling in mice, and likely also in humans. We then describe briefly our recent studies on cytokine defects and implantation failure in humans, a key feature being the link between uterine cytokine dysregulation and abnormal uterine vascular scores. We draw lessons for preeclampsia, and describe features of a model for its immune aetiology.

Human alveolar macrophages infected by virulent bacteria expressing SipB are a major source of active interleukin-18

Recent publications have demonstrated that the protease caspase-1 is responsible for the processing of pro-interleukin 18 (IL-18) into the active form. Studies on cell lines and murine macrophages have shown that the bacterial invasion factor SipB activates caspase-1, triggering cell death. Thus, we investigated the role of SipB in the activation and release of IL-18 in human alveolar macrophages (AM), which are the first line of defense against inhaled pathogens. Under steady-state conditions, AM are a more important source of IL-18 than are dendritic cells (DC) and monocytes. Cytokine production by AM and DC was compared after both types of cells had been infected with a virulent strain of Salmonella enterica serovar Typhimurium and an isogenic sipB mutant, which were used as an infection model. Infection with virulent Salmonella led to marked cell death with features of apoptosis while both intracellular activation and release of IL-18 were demonstrated. In contrast, the sipB mutant did not induce such cell death or the release of active IL-18. The specific caspase-1 inhibitor Ac-YVAD-CMK blocked the early IL-18 release in AM infected with the virulent strain. However, the type of Salmonella infection did not differentially regulate IL-18 gene expression. We concluded that the bacterial virulence factor SipB plays an essential posttranslational role in the intracellular activation of IL-18 and the release of the cytokine in human AM.

Production of interleukin-18 and interleukin-12 in patients suffering from chronic hepatitis C virus infection before antiviral therapy

Interleukin-12 and -18 (IL-12 and IL-18) are known to enhance the cytotoxic T-lymphocyte response synergistically, but their precise involvement in hepatitis C virus (HCV) infection is not well known, especially for IL-18. Enzyme-linked immunosorbent assay (ELISA) was used to study the production of these cytokines in plasma and peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide (LPS) of patients infected chronically with HCV before initiation of antiviral therapy. Fifty-six patients and 40 healthy controls were evaluated. Patients infected with genotype 1 or with genotype other than genotype 1 HCV had significantly a high production of plasma IL-12 compared with controls (P < 0.05). However, patients infected with genotype 1 HCV had lower levels of PBMC IL-18 than were founded in the controls (P < 0.05); plasma IL-18 also tended to be lower in this group of patients than in the controls, although nonsignificantly. Plasma IL-18 was related to hepatic histological activity (P < 0.05). The data suggest a relationship between these two cytokines and some features of HCV infection, so that their respective production in relation to the outcome of the infection deserves further study.