Differential binding of human interleukin-1 (IL-1) receptor antagonist to natural and recombinant soluble and cellular IL-1 type I receptors

Expression of biological markers in gingival crevicular fluid of teeth with orthodontically induced root resorption

AIM

The goal was to investigate interleukin‑1 receptor antagonist (IL-1ra) and dentin sialophosphoprotein (DSPP) levels in gingival crevicular fluid (GCF) as potential biomarkers for orthodontically induced root resorption (OIRR) using enzyme-linked immunosorbent immunoassay (ELISA).

MATERIALS AND METHODS

In all, 74 subjects were assigned to one of three groups: (1) orthodontic group included orthodontic patients who showed radiographic evidence of 1-3 mm root resorption of a maxillary central incisor, (2) pediatric group included pediatric patients who showed radiographic evidence of physiologic root resorption of a lower second primary molar, and (3) control group included subjects who had no orthodontic treatment and showed no radiographic evidence of root resorption. Samples from the GCF were collected with endodontic absorbent paper points inserted 1 mm below the gingival margin of the tooth. The IL-1ra and DSPP levels were evaluated using ELISA.

RESULTS

The IL-1ra levels were 657.5 ± 51.5, 319.9 ± 181.3, and 129.4 ± 54.9 pg/ml for the control, orthodontic, and pediatric groups, respectively. The DSPP levels were 1.6 ± 1.0, 30.1 ± 9.6, and 39.2 ± 3.3 pg/ml for the control, orthodontic, and pediatric groups, respectively. Post hoc analyses revealed significant differences for IL-1ra and DSPP between any two groups. Sensitivity and specificity of IL-1ra for the diagnosis of OIRR showed 80% reliability and a cutoff value of ≤432.6 pg/ml, while the analysis of DSPP showed 100% reliability and a cutoff value of ≥7.33 pg/ml.

CONCLUSIONS

The levels of IL-1ra and DSPP detected in the orthodontic and pediatric groups indicate a possible association with OIRR. Efforts to develop tests for screening, diagnosis, and monitoring OIRR based on biological markers should continue.

Interleukins and interleukin receptors in rheumatoid arthritis: Research, diagnostics and clinical implications

Rheumatoid arthritis (RA) is an autoimmune disease, resulting in a chronic, systemic inflammatory disorder. It may affect many tissues and organs, but it primarily affects the flexible joints. In clinical practice patient care generates many questions about diagnosis, prognosis, and treatment. It is challenging for health care specialists to keep up to date with the medical literature. This review summarizes the pathogenesis, the polymorphisms of interleukin and interleukin genes and the standard available and possible future immunologic targets for RA treatment. The identification of disease-associated interleukin and interleukin receptor genes can provide precious insight into the genetic variations prior to disease onset in order to identify the pathways important for RA pathogenesis. The knowledge of the complex genetic background may prove useful for developing novel therapies and making personalized medicine based on the individual’s genetics.

Activation of the peroxisome proliferator–activated receptor α pathway potentiates interleukin-1 receptor antagonist production in cytokine-treated chondrocytes

OBJECTIVE

To determine whether peroxisome proliferator-activated receptor alpha (PPARalpha) agonists protect chondrocytes against the effects of interleukin-1beta (IL-1beta).

METHODS

PPARalpha expression and function in cultured rabbit articular chondrocytes were studied by Northern blotting, electrophoretic mobility shift assay, and transient expression of a luciferase reporter construct bearing the human IL-1 receptor antagonist (Il-1Ra) gene promoter. Chondrocytes were incubated in vitro with IL-1beta alone or in combination with CloFibrate (CloF) or other PPAR ligands. Proteoglycans were evaluated by 35S-sulfate incorporation, matrix metalloproteinase (MMP) levels were assessed by zymography and enzyme-linked immunosorbent assay (ELISA), and MMP messenger RNA (mRNA) levels were measured by Northern blotting and real-time reverse transcriptase-polymerase chain reaction. IL-1beta and IL-1Ra soluble contents were measured by ELISA.

RESULTS

CloF counteracted IL-1beta-induced 35S-proteoglycan degradation, gelatinolytic activity, and MMP-1, -3, and -13 mRNA expression. CloF also maximized IL-1beta-induced endogenous production of soluble IL-1Ra (sIL-1Ra). This stimulating effect on IL-1Ra gene expression was shown, by transient expression assay, to be transcriptional. Inhibition of sIL-1Ra expression by a specific small interfering RNA suppressed the effect of CloF on IL-1beta-induced MMP expression. The stimulatory effect of CloF was enhanced by cotransfection with wild-type PPARalpha and abolished by a dominant-negative PPARalpha mutant. Fenofibrate and WY-14643 displayed a similar stimulating effect on the IL-1Ra promoter, while rosiglitazone did not. Two PPAR response elements, an NF-kappaB-binding site, and a CCAAT/enhancer binding protein-binding site were identified in the IL-1Ra promoter. All 4 sites were necessary for mediation of the effects of CloF.

CONCLUSION

Our findings support the notion that there is a PPARalpha-dependent mechanism that inhibits IL-1beta function in chondrocytes, which operates via an increase in sIL-1Ra production.

Autologous serum deprivation restored IL-1 receptor antagonist production by peripheral blood mononuclear cells in patients with gastric cancer

It has been established that cancer patients have immunosuppressive substances in their sera that depress cellular immunity. Although plasma exchanges have been attempted to remove these substances and to improve immunity to cancer, little is known about its mechanism from the viewpoint of cytokine pattern. The levels of the cytokines, tumour necrosis factor-alpha, interleukin 1beta, interleukin 6, interferon-gamma and interleukin-1 receptor antagonist (IL-1ra) by peripheral blood mononuclear cells (PBMC) were determined simultaneously by the whole-blood assay and the PBMC assay in 20 patients with gastric cancer and in 10 healthy volunteers. In both assays the cytokine levels were lower in patients with cancer compared with healthy controls, with the exception of IL-1ra. In the PBMC assay, the IL-1ra level in cancer patients was significantly higher than that in controls. No statistical correlation between the cytokine levels determined by the two assays was found. We suggest that autologous serum deprivation restored and enhanced IL-1ra production, and normalized the cytokine cascade in immune response, in patients with gastric cancer.

Selectivity release of the type II decoy IL-1 receptor

The type II IL-1 receptor (IL-1RII) is a non-signalling molecule which acts as a decoy target for IL-1. Various signals (e.g. chemoattractants and phorbol ester) induce metalloprotease-mediated rapid shedding of the IL-1RII. The present study was designed to compare the susceptibility to shedding of the decoy IL-1RII vs the signalling IL-1RI. HEK 293 cells and COS cells were transfected with cDNAs encoding the human IL-1RI, IL-1RII or both. Slow spontaneous release and rapid phorbol ester-induced shedding were only observed for the decoy IL-1RII. Similarly, OVCAR-3 cells, which express substantial amounts of both IL-1RI and IL-1RII, only released the IL-1RII. These results indicate that the IL-RII, but not the IL-1RI, is susceptible to proteolytic shedding, a finding consistent with the decoy function of this molecule.

Administration of intravenous immunoglobulin (IVIG) in vivo--down-regulatory effects on the IL-1 system

Modulation of the cytokine network may be of importance for the beneficial effects of therapy with IVIG seen in a wide range of immune-mediated disorders. In the present study we investigate the effect of IVIG administration in vivo on the IL-1 system in 12 patients with primary hypogammaglobulinaemia. Before IVIG infusion these patients had significantly elevated levels of IL-1alpha and IL-1beta both in plasma and in supernatants from peripheral blood mononuclear cells (PBMC) compared with healthy controls. After one bolus infusion with IVIG (0.4 g/kg) we found a significant change in the profile of the components of the IL-1 system: a marked increase in levels of IL-1 receptor antagonist (IL-1Ra) and neutralizing antibodies against IL-1alpha, a moderate decrease in levels of IL-1alpha, IL-1beta and soluble (s) IL-1 receptor type I and a significant increase in sIL-1 receptor type II levels. These changes were found both in plasma and in PBMC isolated after IVIG administration. Furthermore, pooled serum obtained after IVIG infusion suppressed lipopolysaccharide- and staphylococcal enterotoxin B-stimulated, but not phorbol myristate acetate-stimulated, release of IL-1alpha and IL-1beta from PBMC isolated from healthy controls. Finally, these changes in circulating levels of various IL-1 modulators after IVIG infusion appeared to cause a significantly impaired ability of IL-1 to stimulate PBMC for tumour necrosis factor-alpha release. Our findings suggest that IVIG administration may not only down-regulate the activity in the IL-1 system, but also hamper IL-1 stimulation of PBMC.

Interleukin-1 receptor antagonist: role in biology

The interleukin-1 receptor antagonist (IL-1Ra) is a member of the IL-1 family that binds to IL-1 receptors but does not induce any intracellular response. Two structural variants of IL-1Ra have previously been described: a 17-kDa form that is secreted from monocytes, macrophages, neutrophils, and other cells (sIL-1Ra) and an 18-kDa form that remains in the cytoplasm of keratinocytes and other epithelial cells, monocytes, and fibroblasts (icIL-1Ra). An additional 16-kDa intracellular isoform of IL-1Ra has recently been described in neutrophils, monocytes, and hepatic cells. Both of the major isoforms of IL-1Ra are transcribed from the same gene through the use of alternative first exons. The two promoters regulating transcription of the secreted and intracellular forms have been cloned, and some of the functional cis-acting DNA regions have been characterized. The production of IL-1Ra is stimulated by many substances including adherent IgG, other cytokines, and bacterial or viral components. The tissue distribution of IL-1Ra in mice indicates that sIL-1Ra is found predominantly in peripheral blood cells, lungs, spleen, and liver, while icIL-1Ra is found in large amounts in skin. Studies in transgenic and knockout mice indicate that IL-1Ra is important in host defense against endotoxin-induced injury. IL-1Ra is produced by hepatic cells with the characteristics of an acute phase protein. Endogenous IL-1Ra is produced in numerous experimental animal models of disease as well as in human autoimmune and chronic inflammatory diseases. The use of neutralizing anti-IL-1Ra antibodies has demonstrated that endogenous IL-1Ra is an important natural antiinflammatory protein in arthritis, colitis, and granulomatous pulmonary disease. Treatment of human diseases with recombinant human IL-1Ra showed an absence of benefit in sepsis syndrome. However, patients with rheumatoid arthritis treated with IL-1Ra for six months exhibited improvements in clinical parameters and in radiographic evidence of joint damage.

Antibody to Granulocyte-Macrophage Colony-Stimulating Factor Is a Dominant Anti-Cytokine Activity in Human IgG Preparations

Pharmaceutical preparations of normal human immunoglobulin (IgG) are known to contain high-avidity and neutralizing antibodies (Ab) to the cytokines interleukin (IL)-1α, IL-6, and interferon (IFN)α. To test for other cytokine Ab, 23 batches of IgG were tested for saturable binding to eight 125I-labeled recombinant cytokines. All batches bound granulocyte-macrophage colony-stimulating factor (GM-CSF) with high avidity (Kav ≈ 10 pmol/L) and capacities of up to 5 μmol GM-CSF/mol IgG. Only 1 of 15 batches bound IL-5, also with high avidity, whereas 13 of 15 batches bound to IL-10 but with lower capacities and avidities. None of the IgG preparations bound IL-1 receptor antagonist (IL-1ra), IL-2, IL-3, IL-4, or G-CSF. Cross-binding and absorption analyses revealed identical or slightly stronger binding of recombinant GM-CSF, IL-5, and IL-10 than their native counterparts. GM-CSF–IgG complexes did not bind to cellular GM-CSF receptors, but Fc-dependent binding occurred to blood polymorphonuclear cells. Increased binding of GM-CSF to patient sera correlated positively with the binding capacities of infused IgG preparations. Patient and normal sera did not interfere with the binding of Ab to GM-CSF. From these and previous experiments, we conclude that pools of normal human IgG contain variable amounts of specific and high-avidity Ab to some cytokines, and that Ab to GM-CSF constitute a dominant anti-cytokine activity in these preparations. These Ab are available for reactionin vivo following IgG therapy.

Antibody to Granulocyte-Macrophage Colony-Stimulating Factor Is a Dominant Anti-Cytokine Activity in Human IgG Preparations

Pharmaceutical preparations of normal human immunoglobulin (IgG) are known to contain high-avidity and neutralizing antibodies (Ab) to the cytokines interleukin (IL)-1α, IL-6, and interferon (IFN)α. To test for other cytokine Ab, 23 batches of IgG were tested for saturable binding to eight 125I-labeled recombinant cytokines. All batches bound granulocyte-macrophage colony-stimulating factor (GM-CSF) with high avidity (Kav ≈ 10 pmol/L) and capacities of up to 5 μmol GM-CSF/mol IgG. Only 1 of 15 batches bound IL-5, also with high avidity, whereas 13 of 15 batches bound to IL-10 but with lower capacities and avidities. None of the IgG preparations bound IL-1 receptor antagonist (IL-1ra), IL-2, IL-3, IL-4, or G-CSF. Cross-binding and absorption analyses revealed identical or slightly stronger binding of recombinant GM-CSF, IL-5, and IL-10 than their native counterparts. GM-CSF–IgG complexes did not bind to cellular GM-CSF receptors, but Fc-dependent binding occurred to blood polymorphonuclear cells. Increased binding of GM-CSF to patient sera correlated positively with the binding capacities of infused IgG preparations. Patient and normal sera did not interfere with the binding of Ab to GM-CSF. From these and previous experiments, we conclude that pools of normal human IgG contain variable amounts of specific and high-avidity Ab to some cytokines, and that Ab to GM-CSF constitute a dominant anti-cytokine activity in these preparations. These Ab are available for reactionin vivo following IgG therapy.

Interleukin-1 receptor antagonists and other markers in colorectal cancer patients

BACKGROUND

Although the interleukin-1 receptor antagonist (IL-1ra) has been suggested as a potentially valuable therapeutic agent and has been shown to improve outcome in various animal models of arthritis, septic shock, and inflammatory bowel disease, there is little information available about its level in the circulation in patients with cancer.

METHODS

Serum levels of IL-1ra, soluble interleukin-2 receptor (sIL-2r), soluble intercellular adhesion molecule-1 (sICAM-1), and cortisol were measured in normal controls and patients with colorectal cancer.

RESULTS

The data showed that serum IL-1ra levels in patients were significantly lower than those of healthy controls (P < 0.05). In contrast, serum sIL-2r and cortisol levels in patients were significantly higher than those of normal controls (P < 0.01). Serum sICAM-1 levels in patients were the same as in normal controls.

CONCLUSIONS

These results suggested that a reduced level of IL-1ra exists in colorectal cancer patients relative to normal controls, indicating that cancer patients have an immunologic disorder and that exogenous IL-1ra administration might be a future alternative for cancer treatment.