Lipopolysaccharide induces human interleukin-1 receptor antagonist and interleukin-1 production in the same cell

Interleukin-1 receptor antagonist protein and mRNA in the rat adrenal gland

The occurrence of the endogenous receptor antagonist for the cytokine interleukin-1 in the rat adrenal gland was analyzed y polymerase chain reaction and by immunohistochemistry using a rabbit polyclonal antiserum. Expression of interleukin-1 receptor antagonist mRNA was demonstrated in both adrenal medulla and cortex, and a marked increase in the transcription was observed after systemic administration of lipopolysaccharides. Interleukin-1 receptor antagonist immunoreactivity was seen in the adrenal medulla, and the immunofluorescence intensity was stronger in the adrenergic, phenylethanolamine N-methyltransferase-positive cells than in the noradrenergic chromaffin cells. The distribution of interleukin-1 receptor antagonist protein is complementary to that of interleukin-1 alpha-like immunoreactivity found in phenylethanolamine N-methyltransferase-negative cells and overlaps with and resembles the distribution of interleukin-1 beta-immunoreactive material. The expression of the interleukin-1 receptor antagonist in the adrenal gland complements previous findings of large constitutive pools of interleukin-1 alpha and interleukin-1 beta in this neuroendocrine organ and also suggests participation of adrenal interleukin-1 receptor antagonist in neuroimmune modulation.

Detection of cytoplasmic IL-1 beta in peripheral blood mononuclear cells from intensive care unit (ICU) patients

Cytokines including IL-1 beta have been implicated in the pathophysiology of sepsis and the systemic inflammatory response. It is believed that certain critically ill patients may be 'primed' with respect to cytokine production, and that subsequent 'triggers' may cause exaggerated cytokine production in these patients with exacerbation of their clinical condition; however, no means of identifying 'primed' patients has been described. The presence of cytoplasmic IL-1 beta within peripheral blood mononuclear cells (PBMC) from patients in the ICU was investigated as a means of identifying 'primed' patients, using fluorescent antibody labelling and flow cytometry. The study revealed that PBMC from ICU patients had a different staining pattern for IL-1 beta than those from healthy subjects, and that PBMC from certain ICU patients did indeed stain strongly for IL-1 beta; however, the presence of these strongly staining cells was not associated with clinical condition or outcome. It is concluded that whilst it might be possible to identify 'primed' patients in the ICU using this technique, this is of no clinical value as a predictor of clinical course.

Persistence of local cytokine production in shigellosis in acute and convalescent stages

Shigella infection is accompanied by an intestinal activation of epithelial cells, T cells, and macrophages within the inflamed colonic mucosa. A prospective study was carried out to elucidate the cytokine pattern in Shigella infection linked to development of immunity and eradication of bacteria from the local site and also to correlate the cytokine profile with histological severity. An indirect immunohistochemical technique was used to determine the production and localization of various cytokines at the single-cell level in cryopreserved rectal biopsies from 24 patients with either Shigella dysenteriae type 1 (n = 18) or Shigella flexneri (n = 6) infection. The histopathological profile included presence of chronic inflammatory cells with or without neutrophils and microulcers in the lamina propria, crypt distortion, branching, and less frequently crypt abscesses. Patients had significantly higher (P < 0.005) numbers of cytokine producing cells for all of the cytokines studied, interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-1ra, tumor necrosis factor alpha (TNF-alpha), IL-6, IL-8, IL-4, IL-10, gamma interferon, TNF-beta, and transforming growth factor beta 1-3, in the biopsies than the healthy controls (n = 13). The cytokine production profile during the study period was dominated by IL-1 beta, transforming growth factor beta 1-3, IL-4, and IL-10. Significantly increased frequencies of cytokine-producing cells (P < 0.05) were observed for IL-1, IL-6, gamma interferon, and TNF-alpha in biopsies with severe inflammation in comparison with those with mild inflammation. During the acute stage of the disease, 20 of 24 patients exhibited acute inflammation in the rectal biopsies and the cellular infiltration was still extensive 30 days after the onset of diarrhea, although the disease was clinically resolved. In accordance with the histological findings, cytokine production was also upregulated during the convalescent phase; there was no significant difference (P > 0.05) in the incidence of cytokine-producing cells between acute (2 to 8 days after the onset of diarrhea) and convalescent (30 days after onset) stages.

Similar cytokine induction profiles of a novel streptococcal exotoxin, MF, and pyrogenic exotoxins A and B

The cytokine production induced by a newly discovered streptococcal exotoxin, MF, and the pyrogenic exotoxins SpeA and SpeB was determined by in vitro stimulation of peripheral blood mononuclear cells (PBMCs) obtained from healthy blood donors. The induction and kinetics of interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-1 receptor antagonist, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, gamma interferon, tumor necrosis factor alpha (TNF-alpha), TNF-beta, and granulocyte-macrophage colony-stimulating factor were studied at the single-cell level by use of cytokine-specific monoclonal antibodies and intracellular immunofluorescent juxtanuclear staining. The cytokine-producing cells, with the exception of IL-1-expressing cells, had a characteristic morphology generated by the accumulation of cytokines in the Golgi organelle. MF, SpeA, and SpeB induced a massive gamma interferon and TNF-beta response in 10 to 16% of the PBMCs after 48 to 96 h of cell stimulation. In contrast, IL-2 and TNF-alpha production was detected in only 1 to 3% of the PBMCs. The induction of a lymphocyte TH2 phenotype response, including production of IL-3, IL-4, IL-5, and IL-10, was weak. However, the monokines, IL-1 alpha, IL-1 beta, IL-1 receptor antagonist, and IL-8, were consistently found and gradually produced, peaking at 24 h in approximately 5 to 8% of the PBMCs. MF showed extensive cytokine- and proliferation-inducing capacities equal to those of SpeA and SpeB, which suggests that MF is also a superantigen. A marked interindividual variation could be noted both in the proliferative response and in the cytokine induction of lymphocytes isolated from different individuals, which may be one explanation for the varying clinical severity noticed during group A streptococcal infections.

Cytokine synthesis analyzed at the single-cell level before and after revaccination with tetanus toxoid

Tetanus toxoid (TT) is a potent immunogen which evokes strong antibody responses after immunization. Here, TT was used as a model antigen to study the production of cytokines at the single-cell level during the in vitro immune response to a specific recall antigen. Peripheral blood mononuclear cells were obtained from healthy volunteers before and 9 weeks after TT vaccination and were cultured with antigen in vitro. The kinetics of cytokine synthesis as well as frequencies of cytokine-producing cells were determined at the single-cell level by immunofluorescent intracellular staining of the cytokine protein. The phenotype of the producer cells was revealed by concomitant staining of surface markers. Two patterns of cytokine synthesis were induced by TT: (i) T lymphocytes expressed a number of lymphokines (interleukin (IL)-2, IL-3, IL-4, IL-10, interferon (IFN)-gamma and tumor necrosis factor (TNF)-beta), each with distinct kinetics of synthesis. This cytokine expression was strictly dependent on the previous exposure of the donor to TT and positively correlated with the level of tetanus immunity, as judged by TT-specific Ab levels in plasma as well as lymphoproliferation. Cells producing IL-2, IFN-gamma and particularly TNF-beta dominated this in vitro response. After 96-120 h in culture, 1.0-1.3% of the cells produced TNF-beta, i.e. frequencies at least tenfold higher than for any of the other lymphokines assayed. The addition of IL-2 to the cultures caused a fourfold increase and a kinetics shift in the production of TNF-beta, which peaked already at 24 h. Exogenously added IL-2 also caused a five- to tenfold increase in the number of IL-2 and IFN-gamma producers but no apparent change in the kinetics of intracellular lymphokine appearance. (ii) The cytokines IL-1 alpha, IL-1 beta, IL-6 and TNF-alpha were produced by monocytes. This inflammatory monokine response was independent of the TT-specific immune status of the donors, characterized by a rapid onset and was transient.

Blocking interleukin-1 receptors

During inflammation, injury, immunological challenge or infection, interleukin-1 appears to mediate, in part, the pathogenesis, of disease. Most studies on interleukin-1 are derived from experiments in which bacterial products, such as endotoxins from Gram-negative bacteria or exotoxins from Gram-positive organisms, are used to stimulate macrophagic cells. In general, several cytokines are induced by microbes to their products. Although cytokines are thought to play a role in the outcome of disease, only a few have been directly implicated as mediators of the pathogenic mechanisms of the host. Studies on specific inhibition of interleukin-1 activity have employed interleukin-1 receptor antagonist, interleukin-1 receptor blocking antibodies or soluble interleukin-1 receptors. Experiments in vitro, in animal models of disease and in human subjects have shed considerable light on a critical role for interleukin-1 in the pathogenesis of disease. This review focuses on interleukin-1 as a cytokine of strategic importance to the outcome of disease, particularly inflammatory and infectious diseases.

Lymphokine production induced by streptococcal pyrogenic exotoxin-A is selectively down-regulated by pooled human IgG

The influence of pooled human IgG preparations for intravenous use (IVIg) on cytokine production induced by streptococcal pyrogenic exotoxin-A (SPE-A) was studied at the single-cell level using cytokine-specific monoclonal antibodies and indirect immunofluorescence or immunohistochemical staining. Mononuclear cells from healthy adult blood donors were stimulated with SPE-A alone or in the presence of IVIg. IVIg was added either prior to stimulation or 24 h after initiation of cultures, in an attempt to evaluate whether IVIg treatment could influence an already established systemic streptococcal disease. Cells were harvested after 48 or 72 h of culture and stained for the following cytokines: interleukin(IL)-1 alpha, IL-1 beta, IL-1ra, IL-6, IL-8, IL-2, tumor necrosis factor interferon(IFN)-gamma and TNF-alpha and TNF-beta and granulocyte macrophage-colony-stimulating factor. Stimulation with SPE-A lead to extensive lymphokine and monokine production. With the addition of IVIg prior to stimulation there was a strong reduction of blast transformation and an almost complete inhibition of lymphokine production, in particular in the synthesis of IFN-gamma and TNF-beta while the synthesis of IL-1 and IL-8 was either unaffected or increased. Adding IVIg 24 h after SPE-A stimulation also resulted in reduced blast transformation and decreased synthesis of IFN-gamma and TNF-beta. These results indicate an immunomodulatory potential by IVIg on streptococcally induced T cell activation and lymphokine production.

Monoclonal antibody based enzyme-linked and chemiluminescent assays for the human interleukin-1 receptor antagonist. Application to measure hIL-1ra levels in monocyte cultures and synovial fluids

Interleukin-1 receptor antagonist (IL-1ra) has the potential to counteract at least part of the biological effects of interleukin-1. The outcome of an inflammatory reaction may therefore be determined by the balance between IL-1 and IL-1ra, rather than by IL-1 alone. We have developed an immunoassay to address this issue as well as to assess the effects of anti-inflammatory agents on the expression of IL-1 and IL-1ra in vitro or in body fluids. Recombinant human IL-1ra was expressed in an E. coli system, purified to homogeneity, and used to derive monoclonal antibodies in mice as well as polyclonal antibodies in rabbits. A sandwich ELISA was constructed with F(ab')2 fragments of a high affinity monoclonal antibody and the rabbit serum as a source of secondary antibody. The assay required no sample treatment to avoid interference by rheumatoid factor. The measuring range was 0.020-2 ng/ml. By labelling a second monoclonal antibody with an acridinium ester, a chemiluminescence assay with a wider measuring range (0.050-15 ng/ml) was generated. In accord with published data, we found that IL-1ra was secreted by human monocytes stimulated with LPS, Zymosan, IL-1 alpha, or human IgG. After an induction phase of ca. 4 hours and depending on the stimulus, IL-1ra accumulated linearly for periods up to 96 h. IL-1ra levels in synovial fluids of 19 patients suffering from various inflammatory joint diseases were compared with the cytokine levels of IL-1 beta, IL-6, IL-8, and TNF-alpha. Highest positive correlations were found with IL-8 and IL-1 beta. In normal blood donors IL-1ra serum levels were 150-800 pg/ml (Median: 387 pg/ml). Owing to its sensitivity and large measuring range the newly developed assays appear to be suitable for measuring IL-1ra in cell cultures as well as in biological fluids.

Production of interleukin-1 receptor antagonist by human glioblastoma cells in vitro and in vivo

We investigated the expression and production of the interleukin-1 receptor antagonist (IL-1ra) in three human glioblastoma cell lines (LN443, LN444, LN859). Reverse transcription-polymerase chain reaction (RT-PCR) demonstrated the expression of IL-1ra mRNA transcripts in the three cell lines. These three cell lines also expressed mRNA for IL-1 alpha, IL-1 beta, as well as IL-1 receptor type I and type II, suggesting the presence of an IL-1 autocrine loop in these cell lines. Northern blot analysis demonstrated that the IL-1ra mRNA expression increased with IL-1 beta or tumor necrosis factor (TNF)-alpha but not with GM-CSF stimulation in both LN443 and LN444 cell lines. PMA stimulation increased the mRNA expression in LN444 but not in LN443 cells. Immunocytochemical staining showed IL-1ra immunoreactivity in these three cell lines. ELISA on culture supernatants demonstrated that the IL-1ra was secreted from the cell lines in agreement with the mRNA expression. RT-PCR with isoform-specific primers showed that both intracellular and secreted forms of IL-1ra were expressed by the three cell lines, with a predominance of the intracellular form. In vivo study with RT-PCR and Northern blot analysis demonstrated IL-1ra mRNA in six out of 12 human glioblastoma and two out of five anaplastic astrocytoma tissues, although the expression level was not high in some cases. Immunohistochemistry demonstrated the presence of IL-1ra within the cytoplasm of tumor cells in six out of 10 glioblastomas in vivo. These results suggest a potential role of IL-1ra in regulation of the IL-1 autocrine loop in glioblastomas.

Cerebrospinal fluid interleukin-1 beta/interleukin-1 receptor antagonist balance and tumor necrosis factor-alpha concentrations in tuberculous, viral and acute bacterial meningitis

The levels of interleukin-1 beta, IL-1 receptor antagonist and tumor necrosis factor-alpha (TNF-alpha) were analyzed in 19 cases of tuberculous, 14 cases of viral, and 22 cases of acute bacterial meningitis, and in 18 control subjects. 20 patients (91%) with acute bacterial and 8 (42%) with tuberculous meningitis had detectable amounts of TNF-alpha in the initial cerebrospinal fluid (CSF) sample (mean 1044 +/- 131 pg/ml, range 95-1950, and mean 61 +/- 23 pg/ml, range 25-300, respectively), whereas TNF-alpha was not detectable in any of the patients with viral meningitis, or in any of the control subjects. IL-1 beta levels were 767 +/- 110 pg/ml (185-2000) in acute bacterial, 345 +/- 63 pg/ml (50-670) in tuberculous, 257 +/- 70 pg/ml (20-700) in viral meningitis, and 37 +/- 4 pg/ml (10-68) in control subjects. Il-1 receptor antagonist concentrations were significantly elevated in all meningitis groups, without significant differences between the groups. Il-1 receptor antagonist levels were 2487 +/- 62 pg/ml (2250-2950) in acute bacterial, 2216 +/- 82 pg/ml (1350-2550) in tuberculous and 1985 +/- 92 pg/ml (650-2500) in viral meningitis, and 154 +/- 26 pg/ml (20-245) in control CSF samples. A positive correlation was found between TNF and IL-1 beta levels (p < 0.01), and TNF levels and conscious state (p < 0.05). The ratio of concentrations of IL-1 receptor antagonist to IL-1 beta was 3.2 in acute bacterial meningitis, 6.9 in tuberculous meningitis and 8.3 in viral meningitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of the hypothalamus-pituitary-adrenal axis by bacterial endotoxins: routes and intermediate signals

Peripheral administration of endotoxin induces brain-mediated responses, including activation of the hypothalamus-pituitary-adrenal (HPA) axis and changes in thermoregulation. This paper reviews the mechanisms by which endotoxin affects these responses. The effects on thermoregulation are complex and include macrophage-dependent hyperthermic and hypothermic responses. Low doses of endotoxin, given IP, activate peripheral macrophages to produce interleukin (IL)-1 beta, which enters the circulation and acts as a hormonal signal. IL-1 may pass fenestrated endothelium in the median eminence to stimulate corticotropin-releasing hormone (CRH) secretion from the CRH nerve-terminals. In addition, IL-1 may activate brain endothelial cells to produce IL-1, IL-6, prostaglandins, etc., and secrete these substances into the brain. By paracrine actions, these substances may affect neurons (e.g., CRH neurons) or act on microglial cells, which show IL-1-induced IL-1 production and therefore amplify and prolong the intracerebral IL-1 signal. In contrast, high doses of endotoxin given i.v. may directly stimulate endothelial cells to produce IL-1, IL-6, and prostaglandin-E2 (PGE2) and thereby activate the HPA axis in a macrophage-independent manner.

Centrally administered bacterial lipopolysaccharide depresses feeding in rats

Bacterial lipopolysaccharide (LPS) suppresses feeding in rats when administered peripherally in the microgram range. In the present study, the effects of LPS (Escherichia coli serotype 0111:B4) on the central regulation of feeding in rats maintained ad lib was investigated. Intracerebroventricular (ICV) microinfusion of LPS (0.1 to 1000 ng/rat) suppressed the short-term (2-h) and long-term (nighttime and total daily) food intakes, dose dependently. Computerized analysis of behavioral patterns demonstrated a significant reduction of meal size during the nighttime, whereas meal frequency and meal duration were also decreased, but not significantly. Water intake and locomotor activity also decreased. Intraperitoneal administration of LPS in doses equivalent to those administered centrally had no effect on food intake. The results suggest that centrally administered LPS acts directly in the central nervous system (CNS) to depress feeding.

Comparison of first use and reuse of cuprophan membranes on interleukin-1 receptor antagonist and interleukin-1 beta production by blood mononuclear cells

The magnitude of the changes in a variety of blood constituents on exposure to the dialysis membrane has been used as an index of "biocompatibility," and dialyzer reuse has been postulated to improve biocompatibility by attenuating these changes. We studied the hemodialysis-induced changes in the in vitro production of interleukin-1 receptor antagonist (IL-1Ra) and interleukin-1 beta (IL-1 beta) by peripheral blood mononuclear cells (PBMCs), and compared the effect of first use and reuse of cuprophan membranes on these changes. Studies were performed during dialysis with first use and third reuse of the same kidney. The cell content and production of IL-1Ra and IL-1 beta by unstimulated and endotoxin- or IgG-stimulated PBMCs were studied just prior to dialysis, and from the afferent and efferent limbs of the blood circuit 15 minutes after the start of dialysis. Interleukin-1 receptor antagonist and IL-1 beta were measured by specific radioimmunoassay and are expressed as picograms per 2.5 x 10(6) PBMCs. Fifteen minutes after the start of dialysis, the number of PBMCs harvested from 10 mL of blood decreased from 19.8 +/- 4.7 x 10(6) predialysis to 14 +/- 3 x 10(6) (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Modalities for reducing interleukin 1 activity in disease

The therapeutic advantage of reducing the activity of interleukin 1 (IL-1) resides in preventing its deleterious biological effects without interfering with homeostasis. As such, methods attempting to block the production or activity of IL-1 have now entered clinical trials. For example, IL-1 induction of prostaglandins is one target in treating disease, and drugs preventing the production of inhibiting cyclooxygenase have well-known toxicities because they block the normal synthesis of prostaglandins in many tissues. IL-1 blockading agents, in contrast, affect only that portion of prostaglandin synthesis due to elevated IL-1, sparing the synthesis of these molecules for homeostasis. Here we review the unique pharmacological advantages of manipulating IL-1.

Modalities for reducing interleukin 1 activity in disease

The therapeutic advantage of reducing the activity of interleukin 1 (IL-1) resides in preventing its deleterious biological effects without interfering with homeostasis. As such, methods attempting to block the production or activity of IL-1 have now entered clinical trials. For example, IL-1 induction of prostaglandins is one target in treating disease, and drugs preventing the production of inhibiting cyclooxygenase have well-known toxicities because they block the normal synthesis of prostaglandins in many tissues. IL-1 blockading agents, in contrast, affect only that portion of prostaglandin synthesis due to elevated IL-1, sparing the synthesis of these molecules for homeostasis. Charles Dinarello reviews the unique pharmacological advantages of manipulating IL-1.

Characterization of cytokine production in infectious mononucleosis studied at a single-cell level in tonsil and peripheral blood

Cytokine profile and production was studied at a single-cell level in cells obtained from 14 patients with acute infectious mononucleosis (IM), with less than 7 days of symptomatic disease, by use of cytokine-specific MoAbs and indirect immunofluorescence technique. In producer cells, all the studied cytokines, except IL-1, accumulated in the Golgi system, which resulted in a characteristic morphology of the staining. Less than one in a thousand mononuclear cells obtained directly from IM blood and stained within 2 h of sampling produced IL-2, interferon-gamma (IFN-gamma), IL-4, IL-5, IL-6, IL-10, GM-CSF, tumour necrosis factor-alpha (TNF-alpha) or TNF-beta, spontaneously. However, these cells were induced to cytokine synthesis by T cell receptor ligation in vitro using immobilized anti-CD3 MoAbs for 2-3 h restimulation under conditions which did not activate normal cells. By this approach 168 +/- 120 cells/10,000 peripheral blood mononuclear cells produced IFN-gamma as compared with 10 +/- 8 cells/10,000 non-stimulated cultured cells obtained from IM patients (P < 0.001) and 1/10,000 cells obtained from healthy controls, respectively. No induced production of IL-2, IL-3, IL-4, IL-5, IL-10, GM-CSF or TNF-beta was detected in IM cells obtained from peripheral blood by this restimulation. In contrast, a spontaneous cytokine production was evident in tonsil material obtained from four IM patients tonsilectomized because of respiratory obstruction. From this site 160 +/- 40 cells/10,000 cells produced IL-2, 40 +/- 30 cells IL-6, 30 +/- 30 cells TNF-beta and 35 +/- 25 cells IFN-gamma, respectively. No such spontaneous IL-2, IL-6, TNF-beta or IFN-gamma production was evident in control cells obtained from patients tonsilectomized because of chronic tonsil hyperplasia.

Interleukin-1 receptor antagonist

IL-1ra is the first described naturally occurring receptor antagonist of any cytokine or hormone-like molecule. IL-1ra is a member of the IL-1 family by three criteria: amino acid sequence homology of 26 to 30% to IL-1 beta and 19% to IL-1 alpha; similarities in gene structure; and common gene localization to human chromosome 2q14. Two structural variants of IL-1ra exist: sIL-1ra, a secretory molecule produced by monocytes, macrophages, neutrophils, fibroblasts, and other cells; and icIL-1ra, an intracellular molecule produced by keratinocytes and other epithelial cells, macrophages, and fibroblasts. IL-1ra production by monocytes, macrophages, and neutrophils may be regulated in a differential fashion with IL-1 beta. Human IL-1ra binds to both human IL-1RIs and IL-1RIIs on cell surfaces, although with 100-fold greater avidity to IL-1RIs. IL-1ra may bind preferentially to soluble IL-1RIs and not at all to soluble IL-1RIIs. IL-1ra competitively inhibits binding of both IL-1 alpha and IL-1 beta to cell surface receptors without inducing any discernible intracellular responses. All three forms of IL-1 may bind to IL-1 receptors in a similar fashion but IL-1ra may lack the secondary interactions necessary to trigger cell responses. A 100-fold or greater excess of IL-1ra over IL-1 may be necessary to inhibit biological responses to IL-1 both in vitro and in vivo. The roles of sIL-1ra and icIL-1ra in normal physiology or in host defense mechanisms remain unclear. The administration of IL-1ra blocks the effects of IL-1 in some animal models of septic shock, inflammatory arthritis, graft-versus-host disease, and inflammatory bowel disease. The preliminary results of clinical trials in humans indicate possible efficacy of IL-1ra in sepsis syndrome, rheumatoid arthritis, and GVHD.