Dysregulation of the in vivo production of interleukin-1 receptor antagonist in patients with rheumatoid arthritis. Pathogenetic implications

Immunoglobulin profiling with large high-density peptide microarrays as screening method to detect candidate proteins for future biomarker detection in dogs with steroid-responsive meningitis-arteritis

Steroid responsive meningitis arteritis (SRMA) is an aberrant Th2-mediated systemic inflammatory disease in dogs. The etiopathogenesis still remains unclear as no triggering pathogen or autoantigen could be found so far.

HYPOTHESIS

Large high-density peptide microarrays are a suitable screening method to detect possible autoantigens which might be involved in the pathogenesis of SRMA.

METHODS

The IgA and IgG profile of pooled serum samples of 5 dogs with SRMA and 5 dogs with neck pain due to intervertebral disc herniation (IVDH) without ataxia or paresis were compared via commercially available high-density peptide microarrays (Discovery Microarray) containing 29,240 random linear peptides. Canine distemper virus nucleoprotein (CDVN) served as positive control as all dogs were vaccinated. Common motifs were compared to amino acid sequences of known proteins via databank search. One suitable protein was manually selected for further analysis with a smaller customized high-density peptide microarray.

RESULTS

Pooled serum of dogs with SRMA and IVDH showed different IgA and IgG responses on Discovery Microarray. Only top IgG responses of dogs with SRMA showed a common motif not related to the control protein CDVN. This common motif is part of the interleukin 1 receptor antagonist protein (IL1Ra). On IL1Ra, dogs with SRMA displayed IgA binding to an additional epitope, which dogs with IVDH did not show.

DISCUSSION

IL1Ra is an anti-inflammatory acute phase protein. Different immunoglobulin binding patterns on IL1Ra could be involved in the pathogenesis of SRMA and IL1Ra might be developed as future biomarker for SRMA.

Distinct Effects of Interleukin-1β Inhibition upon Cytokine Profile in Patients with Adult-Onset Still's Disease and Active Articular Manifestation Responding to Canakinumab

Adult-onset Still’s disease (AOSD) is a systemic auto-inflammatory disease characterized by the presence of immunologically mediated inflammation and deficient resolution of inflammation. Canakinumab is an approved IL-1β inhibitor in the treatment of AOSD with a balanced efficacy and safety profile. Since inflammatory cytokines play a major role in the pathogenesis of AOSD, we investigated the effects of canakinumab on the cytokine profile of AOSD patients from a randomized controlled trial. Multiplex analysis and ELISA were used to test the concentrations of several cytokines at three time points—week 0 (baseline), week 1 and week 4—in two patient groups—placebo and canakinumab. Two-way repeated-measures analysis of variance revealed a significant temporal effect on the concentrations of MRP 8/14, S100A12, IL-6 and IL-18 with a significant decrease at week 4 in the canakinumab group exclusively. Comparing responders with non-responders to canakinumab showed a significant decrease in MRP 8/14, IL-1RA, IL-18 and IL-6 in responders at week 4, while S100A12 levels decreased significantly in responders and non-responders. In summary, canakinumab showed a striking effect on the cytokine profile in patients with AOSD, exhibiting a clear association with clinical response.

The Natural Course of Serum D-Dimer, C-Reactive Protein, and Erythrocyte Sedimentation Rate Levels After Uneventful Primary Total Joint Arthroplasty

BACKGROUND

This study aimed to assess the baseline levels of D-dimer, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) and monitor the natural course of these serum markers after uneventful primary total joint arthroplasty.

METHODS

This prospective study enrolled 81 patients undergoing primary total knee arthroplasty or total hip arthroplasty. The level of serum D-dimer, CRP, and ESR was measured preoperatively and on postoperative days 1, 3, 5, 15, and 45. Mean peak values, peak times, and distribution were compared between D-Dimer, CRP, and ESR.

RESULTS

The mean preoperative serum D-dimer, CRP, and ESR level was 412 ± 260 (range 200-980) ng/mL, 2.93 ± 2.1 (range 1-18) mg/L, and 22.88 ± 17.5 (range 3-102) mm/h, respectively. The highest mean peak for D-dimer, CRP, and ESR was at postoperative day 1, 3, and 5, respectively.

CONCLUSION

D-dimer levels reached peak levels on postoperative day 1 and then declined rapidly to a plateau level by postoperative day 3. A second, albeit small, peak in the level of D-dimer occurred on postoperative day 15. The level of CRP and ESR remained elevated for much longer with CRP returning to baseline on postoperative day 45 and the level of ESR had not returned back to normal on postoperative day 45.

Serum concentrations of canine interleukin-1 receptor antagonist protein in healthy dogs after incubation using an autologous serum processing system

The objectives of this study were to optimize and validate a canine IL-1RA ELISA using commercially available reagents and to determine the effect of an autologous serum processing system (IRAP II) on IL-1RA concentrations in canine serum. The clinical detection limit of the optimized ELISA was 188.8 to 39,965.6 pg/mL. The observed-to-expected ratio (O:E) for three serial dilutions for four serum samples ranged from 109.6 to 132.2%. The O:E for four serum samples spiked with four concentrations of canine IL-1 RA ranged from 98.7 to 114.3%. Coefficients of variances for intra- and interassay variability ranged from 1.4 to 3.0 and 6.3 to 9.8, respectively. The ELISA was sensitive, linear, accurate, precise, and reproducible. Mean±SD serum concentration of IL-1RA in 12 healthy dogs was 396.6±208.0 pg/mL. There was a significant increase in IL-1RA when blood was incubated in the IRAP II system (15,955.0±6421.0 pg/mL, P<0.0001).

Novel multimeric IL-1 receptor antagonist for the treatment of rheumatoid arthritis

Protein therapeutics targeting inflammatory mediators have shown great promise for the treatment of autoimmunities such as rheumatoid arthritis (RA). However, a significant challenge in this area has been their low in vivo stability and consequently their severely compromised therapeutic efficacy. One such therapeutic molecule IL-1 receptor antagonist (IL-1ra), used in the treatment of rheumatoid arthritis, has displayed only modest efficacy in human clinical trials owing to its short biological half-life. Herein, we report a novel approach to conglomerate individual protein entities into a drug depot by incorporation of an amyloidogenic motif Lys-Phe-Phe-Glu (KFFE) thereby dramatically improving their systemic persistence and in turn their therapeutic efficacy in a mice model of autoimmune arthritis.

Structure and biology of the intervertebral disk in health and disease

The intervertebral disks along the spine provide motion and protection against mechanical loading. The 3 structural components, nucleus pulposus, annulus fibrosus, and cartilage endplate, function as a synergistic unit, though each has its own role. The cells within each of these components have distinct origins in development and morphology, producing specific extracellular matrix proteins that are organized into unique architectures fit for intervertebral disk function. This article focuses on various aspects of intervertebral disk biology and disruptions that could lead to diseases such as intervertebral disk degeneration.

Gene expression profiling in the lungs of pigs with different susceptibilities to Glässer's disease

Background

Haemophilus parasuis is the causative agent of Glässer's disease in pigs. Currently, little is known about the molecular mechanisms that contribute to disease susceptibility. This study used a porcine oligonucleotide microarray to identify genes that were differentially expressed (DE) in the lungs of colostrum-deprived animals previously characterized as being either 'Fully Resistant' (FR) or 'Susceptible' to infection by H. parasuis in a bacterial challenge experiment.

Results

Gene expression profiles of 'FR' and 'Susceptible' animals were obtained by the identification of genes that were differentially expressed between each of these groups and mock-inoculated 'Control' animals. At 24 hours post-inoculation, a total of 21 and 58 DE genes were identified in 'FR' and 'Susceptible' animals respectively. At 72 hours, the numbers of genes were 20 and 347 respectively. 'FR' animals at 24 hours exhibited an increased expression of genes encoding extracellular matrix and TGF-β signalling components, possibly indicative of tissue repair following the successful early resolution of infection. The gene expression profile of 'FR' animals at 72 hours supported the hypothesis that higher levels of antibacterial activity were responsible for the 'FR' phenotype, possibly due to an increase in natural immunoglobulin A and decrease in signalling by the immunoregulatory transcription factor peroxisome proliferator-activated receptor gamma (PPAR-γ). The expression profile of 'Susceptible' animals at both time-points was characterized by an imbalance in signalling between pro and anti-inflammatory cytokines and an increased expression of genes involved in biological processes associated with inflammation. These include the pro-inflammatory cytokine genes resistin (RETN) and interleukin 1-beta (IL1B). At 72 hours, a reduction in the expression of genes involved in antigen presentation by both MHC class I and II molecules was observed, which could have contributed to the inability of 'Susceptible' animals to clear infection.

Conclusions

This study is the first to have identified discrete sets of DE genes in pigs of differing susceptibility to H. parasuis infection. Consequently, several candidate genes and pathways for disease resistance or susceptibility phenotypes have been identified. In addition, the findings have shed light on the molecular pathology associated with Glässer's disease.

Anti-IL-1 molecules: new comers and new indications

The interleukin 1 family is composed by the interleukin 1 (IL-1) and its natural occurring inhibitor, the interleukin 1 receptor antagonist (IL-1Ra). The role of both molecules in rheumatoid arthritis has been widely established, and in this sense new molecules blocking IL-1 actions are under investigation. Anakinra is the recombinant form of IL-1Ra, and has proven to be well tolerated and indicated in the treatment of rheumatoid arthritis. Nevertheless, other molecules such as mAb anti-IL-1 and IL-1 Trap are being developed. Moreover, the recent relation of IL-1 in the inflammasome and pathways of innate immunity has lead to new indications of anti-IL-1 molecules, especially in the autoinflammatory syndromes as well as in other inflammatory diseases. Herein we have performed a review of the literature, limited to English language journals (PUBMED search: combination of descriptors IL-1 and anakinra, systemic juvenile idiopathic arthritis, adult's onset Still's disease, autoinflammatory syndromes, gout, pseudogout, ankylosing spondylitis, and systemic lupus erythematosus from January 1985-December 2008) emphasizing the possible new indications. Although sufficient data is not yet available to fully assess the efficacy and safety of anti-IL-1 molecules in patients with inflammatory disorders other than rheumatoid arthritis, new data is promising.

Regulation of catabolic gene expression in normal and degenerate human intervertebral disc cells: implications for the pathogenesis of intervertebral disc degeneration

Introduction

The aim of this study was to compare the effects of tumour necrosis factor-alpha (TNF-α) and interleukin-1-beta (IL-1β) on protease and catabolic cytokine and receptor gene expression in normal and degenerate human nucleus pulposus cells in alginate culture.

Methods

Cells isolated from normal and degenerate nucleus pulposus regions of human intervertebral discs were cultured in alginate pellets and stimulated by the addition of 10 ng/mL TNF-α or IL-1β for 48 hours prior to RNA extraction. Quantitative real-time polymerase chain reaction was used to assess the effect of TNF-α or IL-β stimulation on the expression of matrix metalloproteinase (MMP)-3, -9 and -13, TNF-α, TNF receptor 1 (TNF-R1), TNF receptor 2 (TNF-R2), IL-1α, IL-1β, IL-1 receptor 1 (IL-1R1) and IL-1 receptor antagonist (IL-1Ra).

Results

MMP-3 and MMP-9 gene expressions were upregulated to a greater level by IL-1β than TNF-α. MMP-13 was upregulated by each cytokine to a similar extent. TNF-α and TNF-R2 expressions were upregulated by both TNF-α and IL-β, whereas TNF-R1 expression was not significantly affected by either cytokine. IL-1β and IL-1Ra expressions were significantly upregulated by TNF-α, whereas IL-1α and IL-1R1 were unchanged.

Conclusions

TNF-α does not induce MMP expression to the same degree as stimulation by IL-1β, but it does act to upregulate IL-1β expression as well as TNF-α and TNF-R2. The net result of this would be an increased inflammatory environment and accelerated degradation of the matrix. These results support the hypothesis that, while TNF-α may be an important initiating factor in matrix degeneration, IL-1β plays a greater role in established pathological degradation.

Circulating cytokines after hip and knee arthroplasty: a preliminary study

Several studies show cytokine concentrations in the peripheral blood are associated with inflammatory activity and surgical trauma. Cytokine concentrations have more rapid increase and quicker return to normal values than either C-reactive protein or erythrocyte sedimentation rate - a matter of hours rather than weeks; some studies suggest they are better predictors of postoperative infection than C-reactive protein and erythrocyte sedimentation rate. Threshold levels of interleukin-6 after joint arthroplasty have been determined, but levels of other potentially useful cytokines (tumor necrosis factor-alpha, interleukin-8, interleukin-10, etc) are not known. We measured the serum levels of 25 different cytokines before and after hip and knee arthroplasties and identified those associated with surgical trauma. Peripheral venous blood samples (one preoperative and three postoperative) from 49 patients undergoing hip or knee arthroplasty were analyzed by laser chromatography. Three of the 25 cytokines had a relationship with postsurgical trauma, which included one deep infection. Serum levels of these three cytokines might be useful to identify periprosthetic infections during the early postoperative period when C-reactive protein and erythrocyte sedimentation rate remain elevated.

LEVEL OF EVIDENCE

Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Cell signalling in macrophages, the principal innate immune effector cells of rheumatoid arthritis

Rheumatoid arthritis is a multisystemic auto-inflammatory disease affecting up to 1% of the population and leading to the destruction of the joints. Evidence exists for the involvement of the innate as well as the adaptive immune systems in the pathology of the disease. The success of anti-tumour necrosis factor-alpha indicates the importance of pro-inflammatory mediators produced by innate immune cells in rheumatoid arthritis progression. Therefore, considerable efforts have been made in elucidating the signalling pathways leading to the expression of those mediators. This review will concentrate on the role of signalling pathways in innate immune cells in the context of rheumatoid arthritis.

Resistin in serum is associated with higher levels of IL-1Ra in post-menopausal women with rheumatoid arthritis

OBJECTIVES

The aim of this study was to investigate associations between serum levels of resistin, an adipokine and markers of inflammation, bone metabolism, plasma lipids and kidney function in post-menopausal RA patients and to evaluate if HRT during 2 yrs affected resistin levels.

METHODS

Eighty-eight women were randomly allocated to receive HRT, vitamin D(3) and calcium or vitamin D(3) and calcium alone. Serum levels of resistin, IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-6 soluble receptor, TNF-alpha were measured by ELISA, markers of bone metabolism, carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and carboxyterminal propeptide of type I procollagen by RIA, ESR, CRP, Hb, creatinine and lipids by standard laboratory techniques, BMD and total lean mass (TLM) by DXA and joint destruction by Larsen score. Resistin was also measured in 42 healthy control women.

RESULTS

There was no difference in resistin concentration between patients and healthy controls. Resistin was significantly correlated with IL-1Ra, CRP, TNF-alpha, ICTP, glucocorticosteroids and Larsen score and inversely with BMD, hip and with TLM. In multiple regression analysis, IL-1Ra, TLM and use of corticosteroids remained determinants of resistin. Patients treated with HRT displayed significant increase in resistin compared with controls in the first but not the second year.

CONCLUSIONS

Resistin was associated with increased inflammation, particularly by the acute-phase reactant IL-1Ra antagonizing IL-1beta, joint destruction, glucocorticosteroids and with reduced BMD and TLM. These findings suggest resistin being a significant mediator in the inflammatory process in RA. Further studies examining the mechanisms behind the relation between resistin and IL-1Ra are encouraged. HRT does not seem to have important long-term effect on resistin.

A comparison of the effect of vitamin A on cytokine secretion by mononuclear cells of preterm newborns and adults

BACKGROUND

For a long time vitamin A has been known to be essential for immune defense of the organism and protection against infections. Vitamin A deficiency in children is associated with morbidity and mortality from infectious diseases which could be prevented and even alleviated by vitamin A supplementation. Moreover, this vitamin is involved in the modulation of immunological and inflammatory responses by regulation of cytokine production. The aim of the study was to compare the in vitro effect of vitamin A on the production of pro-inflammatory (IL-1beta and IL-6) and anti-inflammatory (IL-1 receptor antagonist (ra) and IL-10) cytokines, as well as IL-2 and IFNgamma by cord blood mononuclear cells (CBMC) of preterm newborns to that of peripheral blood mononuclear cells (PBMC) from adults.

METHODS

Mononuclear cells (MC) from individuals of the two age groups were incubated with vitamin A (retinyl palmitate) at various concentrations in the presence of phytohemagglutinin for IL-2 and IFNgamma production or LPS for IL-1beta, IL-1ra, IL-6 and IL-10 secretion. The level of the cytokines in the supernatants was tested by ELISA.

RESULTS

Vitamin A exerted an in vitro inhibitory effect on the production of the anti-inflammatory cytokine IL-1ra by MC of preterm newborns and adults, but did not affect the secretion of the pro-inflammatory cytokines IL-1beta, IL-6 and IFNgamma. Vitamin A caused inhibition of IL-10 secretion by cells from adults, but it did not significantly affect this function in cells from newborns except when high unphysiological doses were applied. In addition vitamin A stimulated the secretion of IL-2 by cells isolated from adults but had no effect on those derived from premature neonates.

CONCLUSIONS

The results indicate that vitamin A may affect the immune function of premature infants via inhibition of IL-1ra secretion. It is suggested that the beneficial effect of vitamin A on the clinical course of bronchopulmonary dysplasia (BPD) may be due to the reduced production of anti-inflammatory cytokines by neonatal CBMC. This may indicate the importance of the pro-inflammatory cytokines in the management of severe lung diseases and BPD.

IL-1 receptor antagonist in metabolic diseases: Dr Jekyll or Mr Hyde?

Interleukin-1 receptor antagonist (IL-1ra) has been shown to play a crucial role in the prevention of various inflammatory diseases. There is also convincing evidence that IL-1ra is able to counteract inflammatory effects of IL-1 members implicated in insulin resistance and diabetes. However, the use of knock-out animal models provides evidence to the contrary and the role of IL-1ra in obesity-linked anomalies remains controversial. This minireview gets an insight into recent findings on the implication of IL-1ra and its gene polymorphism in diabetes and obesity, discusses the potential dual effects of IL-1ra observed in different models, and comments on future directions.

Mirthful laughter differentially affects serum pro- and anti-inflammatory cytokine levels depending on the level of disease activity in patients with rheumatoid arthritis

OBJECTIVES

To examine the effect of mirthful laughter in rheumatoid arthritis (RA), we evaluated the levels of serum cytokines before and after patients experienced mirthful laughter.

METHODS

Forty-one patients with RA and 23 healthy subjects were enrolled. They listened to 'Rakugo', a traditional Japanese comic story, to induce mirthful laughter. We measured serum IL-6, IL-1beta, TNF-alpha, IL-4 and IL-1 receptor antagonist (IL-1Ra) concentrations before and after patients listened to the story. The RA subjects were divided into two groups. One was designated the 'difficult-to-control RA' group (CRP > or =1.0 mg/dl); The other group was regarded as the 'easily controlled RA' group (CRP <1.0 mg/dl).

RESULTS

The basal levels of serum IL-6 and TNF-alpha in the RA patients were significantly higher than those in the healthy group. After experiencing mirthful laughter, the levels of serum IL-6 decreased significantly in the RA group but not in the healthy subjects. Interestingly, the level of serum TNF-alpha decreased only in the easily controlled RA group. Serum IL-4 concentration in the RA group was significantly higher than that in healthy subjects before the story. After the story, the level of serum IL-4 significantly decreased in the RA group, especially in the difficult-to-control RA group. In contrast, serum IL-1Ra concentration was statistically higher in the RA group than that in healthy subjects before the story, and a further increase was observed after the story, especially in the easily controlled RA group.

CONCLUSIONS

Our findings suggest that mirthful laughter affects the levels of serum pro- and anti-inflammatory cytokines differentially, depending on the RA disease activity.

Anakinra: review of recombinant human interleukin-I receptor antagonist in the treatment of rheumatoid arthritis

BACKGROUND

Interleukin-1 (IL-1) plays an important role in the pathophysiology and progression of rheumatoid arthritis (RA) by contributing to destruction of cartilage, bone, and periarticular tissues. Inhibiting IL-1 synthesis or activity with the use of recombinant human IL-1 receptor antagonist (anakinra) may prove to be an effective approach to the treatment of RA.

OBJECTIVE

The purpose of this article is to review the effects of anakinra in the treatment of RA.

METHODS

A MEDLINE search from 1982 to 2003 was used to identify animal studies and randomized clinical trials of anakinra and other therapies that target IL-1.

RESULTS

Clinical trials of anakinra have shown that it reduces the signs and symptoms of active disease and slows the rate of radiographic destruction in adults with RA. With anakinra 150 mg/d, 43% of patients achieved an American College of Rheumatology (ACR) 20% response, compared with 27% with placebo (P = 0.014). The ACR20 score indicates at least 20% improvement in the ACR composite score, which includes assessment of tender and swollen joint count, and other clinical end points such as pain and disability assessment. Patients treated with anakinra also experienced a 59% reduction in new bony erosion compared with controls (P < 0.001) and a 65% reduction in joint space narrowing as measured by the modified Sharp score (P = 0.020). Injection-site reactions were the most commonly reported adverse event, occurring in 50%, 73%, and 81% of patients receiving anakinra 30, 75, and 150 mg/d, respectively, compared with 25% of patients receiving placebo. Few serious adverse events were reported, and they typically occurred in patients receiving the highest daily dosage.

CONCLUSIONS

IL-1 is an important cytokine in promoting the damage associated with RA. Anakinra is mildly to moderately effective and well tolerated in patients with active RA when used as monotherapy or in combination with methotrexate.

Therapeutic potential of targeting IL-1 and IL-18 in inflammation

Interleukin (IL)-1 and IL-18 are cytokines that play a major role in autoimmune and inflammatory human disease. Both cytokines drive a wide range of pro-inflammatory effector networks in many cell types and use common signal transduction cascades. IL-1, IL-18 and other members of the IL-1 superfamily are expressed at elevated levels in tissue and fluid samples isolated from patients with many chronic inflammatory diseases. These cytokines are primary drivers in acute and chronic animal models of inflammation and their blockade has been shown to ameliorate disease in preclinical studies. Biological agents that target IL-1 have demonstrated efficacy in patients with rheumatoid arthritis, and further agents targeting IL-1 or IL-18 neutralisation are in clinical development. The potential for such agents spans human disease where tissue destruction is a primary end point of cytokine action.

Juvenile rheumatoid arthritis: therapeutic perspectives

Juvenile rheumatoid arthritis (JRA) is the most common childhood chronic systemic autoimmune inflammatory disease. The therapeutic approach to JRA has, to date, been casual and based on extensions of clinical experiences gained in the management of adult rheumatoid arthritis (RA). The physiology of inflammation has been systemically studied and this has led to the identification of specific therapeutic targets and the development of novel approaches to the management of JRA. The classical treatments of the disease such as methotrexate, sodium aurothiomalate and sulfasalazine, are not always effective in controlling RA and JRA. This has necessitated the development of novel agents for treating RA, most of which are biological in nature and are targeted at specific sites of the inflammatory cascades. These biological therapeutic strategies in RA have proved successful and are being applied in the management of JRA. These developments have been facilitated by the advances in molecular biology which have heralded the advent of biodrugs (recombinant proteins) and gene therapy, in which specific genes can be introduced locally to enhance in vivo gene expression or suppress gene(s) of interest with a view to down-regulating inflammation. Some of these biodrugs, such as anti-tumor necrosis factor alpha (anti-TNFalpha), monoclonal antibodies (infliximab, adalimumab), TNF soluble receptor constructs (etanercept) and interleukin-1 receptor antagonist (IL-1Ra) have been tested and shown to be effective in RA. Etanercept has now been licensed for JRA. Clinical trials of infliximab in JRA are planned. Studies show that the clinical effects are transient, necessitating repeated treatments and the risk of vaccination effects. Anti-inflammatory cytokines such as IL-4, IL-10, transforming growth factor-beta and interferon-beta (IFN-beta) are undergoing clinical trials. Many of these agents have to be administered parenterally and production costs are very high; thus, there is a need, especially for pediatric use, to develop agents that can be taken orally. Long-term studies will be required to assess the tolerability and toxicity of these approaches in JRA, since cytokines and other mediators play important roles in host defenses, and the chronic inhibition, exogenous administration or constitutive over-expression of some cytokines/mediators may have undesirable effects.

Potential therapeutic uses of interleukin 1 receptor antagonists in human diseases

OBJECTIVE

To review publications relating to the blocking of interleukin 1 (IL1) as a strategy for treating human disease, ranging from rheumatoid arthritis (RA) to Alzheimer's disease.

METHODS

The National Library of Medicine's PubMed database was searched for articles about pharmaceutical agents that reduce the biological actions of IL1.

RESULTS

Fish oils and corticosteroids were identified as non-selective pharmacological interventions that reduce the activity of IL1, whereas a recombinant human IL1 receptor antagonist (anakinra) and a soluble recombinant type I IL1 receptor act selectively. To date, anakinra is the only selective intervention that has been shown in controlled clinical trials to be effective and well tolerated in the treatment of a specific human disorder, RA. In controlled clinical trials, anakinra provided significant clinical improvement and slowed radiographic disease progression in patients with active RA. Moreover, addition of anakinra to existing methotrexate treatment significantly reduced signs and symptoms of active disease.

CONCLUSIONS

The clinical use of anakinra has been demonstrated in the management of RA, but blocking of IL1 in other human disorders, as well as the safety of the use of these blocking agents in chronic diseases, still needs to be defined by controlled clinical investigations.

Anakinra treatment of patients with rheumatoid arthritis

OBJECTIVE

To summarize the safety data arising from clinical trials of anakinra, a human recombinant form of interleukin-1 receptor antagonist (IL-1Ra) developed for the treatment of rheumatoid arthritis (RA).

DATA SOURCES

Primary articles and abstracts identified through the National Library of Medicine's PubMed database (1982-2001) and secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All the articles and abstracts identified from the data sources were evaluated and all information deemed relevant was included in this review.

DATA SYNTHESIS

Overall, anakinra was shown in 4 trials to be efficacious as monotherapy or combination therapy, compared with placebo, for the treatment of active RA. The magnitude of clinical improvement tended to increase with increasing doses of anakinra. In monotherapy trials, the primary adverse event was injection-site reactions, which usually were mild and transient. In com bination therapy (anakinra plus methotrexate), the frequency and severity of adverse events were similar to those seen in the monotherapy trials.

CONCLUSIONS

The use of anakinra in patients with RA inhibits disease activity with a favorable tolerability profile.

The saga of the discovery of IL-1 and TNF and their specific inhibitors in the pathogenesis and treatment of rheumatoid arthritis

In the seventies, the molecule subsequently termed IL-1 was among the first cytokines to attract the attention of rheumatologists due to its biological role in tissue destruction and bone resorption. In the mid-eighties, cachectin/tumor necrosis factor was found to share some of these biological activities, and a strong synergism between the two cytokines became evident. While IL-1 appeared to be more important at the local level, TNF played a more prominent part at the systemic level. In 1984, we became aware of the existence of an antagonist to IL-1 - subsequently termed IL-1Ra (interleukin-1 receptor antagonist) - in urine of febrile patients; its mechanism of action was elucidated in 1987 and the molecule cloned in 1990. The natural inhibitors of TNF were identified in 1996/97 by different investigators and proved to be soluble fragments of the TNF receptor. A concept commonly accepted at present is that disease activity and clinical outcome are controlled by the balance between agonistic and antagonistic cytokines, and at present the principal goal is to understand the underlying mechanisms. This concept is illustrated by observations in numerous animal models. The control of IL-1 and TNF is strongly dependent on the contact between activated lymphocytes and monocytes, the main source of these cytokines. Inhibiting this interaction by interfering with ligands and counter-ligands may be a useful approach if it is possible to maintain the production of the cytokine antagonist. Apolipoproteins A-I and A-II as well as beta2-integrins are molecules that block ligand/counter-ligand interaction. According to animal experiments and clinical data, blocking either IL-1 or TNF, or both, is beneficial. However, to determine not only the benefit but also the side effects of combination therapy in the human system, long-term clinical trials will be required.

Immune responsiveness following academic stress in first-year medical students

Many studies illustrate that physical or psychologic stressors can alter human immune function, which might predispose one to an increased susceptibility to infections. In the present study, we monitored immune responsiveness in 16 first-year medical students (age 23.8 +/- 2.2 years) during the first examination session. Baseline blood samples were collected 30 days prior to the first examination session. Subsequently, subjects were randomly assigned to two groups, and blood samples were collected at 24 h (POST24h) or 48 h (POST48h) after an examination. The percentage of CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD3(+)CD45RO(+), CD3(+)CD45RA(+), CD3(-)CD16(+)56(+), CD19(+), and CD14(+) cells in whole blood was examined to determine changes in circulating immune cell populations. Activation of peripheral blood mononuclear cells (PBMC) with a mixture of phorbol myristate acetate (PMA) and ionomycin or lipopolysaccharide (LPS) for 4 h was used to assess the distribution of interleukin-2 (IL-2)-secreting or interferon-gamma (IFN-gamma)-secreting CD4(+) and CD8(+) cells, as well as IL-1alpha-secreting CD14(+) cells. Activation with a combination of phytohemagglutinin (PHA) and LPS was used to assess secretion of IL-2, IFN-gamma, IL-4, IL-10, soluble IL-2 receptor-alpha (sIL-2Ralpha), IL-1beta, and IL-1R antagonist (IL-1Ra) by PBMC in 48-h cell culture. A significantly higher level of total T cells was found at POST24h, and CD14(+) was elevated at both POST24h and POST48h. The percentage of CD4(+) and CD8(+) cells significantly declined at POST24 and POST48h. A significant elevation in the percentage of memory T cells was observed at POST48h, whereas the percentage of naive T cells was elevated at POST24h and POST48h. These changes were accompanied by a significant decline in percentage of natural killer (NK) cells 24 h after the examination. The percentage of IL-2-producing CD4(+) and CD8(+) cells was significantly lower at POST24h, and the percentage of CD8(+)IFN-gamma(+) cells significantly declined at POST48h. The percentage of CD14(+)IL-1alpha(+) significantly declined at both POST24 and POST48h. A significant decrease was observed in IL-2 secretion 24 h after the examinations, and the secretion of IL-4 and IL-1beta significantly declined at POST48h. No changes in IFN-gamma, IL-10, sIL-2Ralpha, and IL-1Ra secretion were observed. We conclude that the stress outcomes of academic examinations in first-year medical students can significantly alter immune cell distribution and in vitro production and secretion of specific cytokines.

Effects of ovariectomy and estrogen replacement therapy on arthritis and bone mineral density in rats with collagen-induced arthritis

We investigated the effects of ovariectomy (ovx) and estrogen replacement therapy (ERT) on bone mineral density (BMD) and arthritis severity in rats with collagen-induced arthritis (CIA). Seven-month-old female Sprague-Dawley rats were separated into a sham group (n = 8), CIA group (n = 14), ovx group (n = 10), CIA + ovx group (n = 11), and CIA + ovx + ERT group (n = 14). In these groups, ovx was performed at 7 days, and ERT (17beta-estradiol at 20 microg/kg three times per week) was initiated 8 days after sensitization. Every 2 weeks, until 8 weeks after sensitization, arthritis score and hind paw thickness were evaluated, and BMD of the trabecular and cortical bones in the metaphysis and diaphysis of the tibia were measured by peripheral quantitative computed tomography. The arthritis score was highest in the CIA + ovx group at all timepoints after sensitization. The hind paw thickness was significantly higher in the CIA + ovx group than in the CIA group at 8 weeks after sensitization (p < 0.05). Both the arthritis score and hind paw thickness were lower in the CIA + ovx + ERT group than in the CIA + ovx group. BMD in the metaphysis was significantly decreased in both the trabecular and cortical bones in the CIA + ovx group compared with those in the CIA group at 4, 6, and 8 weeks after sensitization. In the CIA + ovx group, trabecular BMD was changed by -34 +/- 11%, and cortical BMD changed by -14 +/- 7% in the metaphysis at 8 weeks compared with those at 0 week. In the CIA group, changes of BMD in the metaphysis were -7 +/- 11% in trabecular bone and 0 +/- 7% in cortical bone. These differences of trabecular and cortical bone loss in the metaphysis were significant (both p < 0.01). BMD reduction was significantly less in the CIA + ovx + ERT group than in the CIA + ovx group at 6 and 8 weeks after sensitization. Although BMD in the diaphysis was also reduced in the groups with CIA, the degree of reduction was smaller than in the metaphysis. We conclude that ovx in CIA rats could enhance the severity of arthritis and bone loss, and that ERT could suppress arthritis and bone loss.

Increased production of intracellular interleukin-1 receptor antagonist type I in the synovium of mice with collagen-induced arthritis: a possible role in the resolution of arthritis

OBJECTIVE

To examine the patterns of production of interleukin-1 receptor antagonist (IL-1Ra) isoforms and of IL-1beta during arthritis in vivo.

METHODS

Arthritis was induced in DBA/1 mice by immunization with type II collagen, and the production of IL-1Ra isoforms was examined in whole joints and in dissected synovial tissues by reverse transcription-polymerase chain reaction (RT-PCR), RNase protection assay, Western blotting, immunostaining, and in situ hybridization. Production of IL-1beta also was examined using similar approaches.

RESULTS

Production of IL-1Ra increased in the joints during collagen-induced arthritis (CIA). By RT-PCR, secreted IL-1Ra messenger RNA (mRNA) was detected in normal joints, whereas intracellular IL-1Ra type I (icIL-1Ra1) mRNA was only produced in inflamed joints. Western blot studies showed that icIL-1Ra1 protein levels increased in the joints during the course of CIA and that icIL-1Ra3 protein was also present in low amounts. RNase protection assays showed that the IL-1beta:IL-1Ra mRNA ratio was increased in inflamed joints through day 14 of arthritis, whereas a reverse pattern was present at later time points (from day 20 to day 60). Consistent with this finding, immunohistochemistry and in situ hybridization studies confirmed that icIL-1Ra1 was only present in inflamed joints. The histologic evaluation of CIA during the course of the disease indicated a resolution of acute inflammation, since icIL-1Ra1 production increased and the ratio of IL-1beta to total IL-1Ra decreased.

CONCLUSION

Production of IL-1Ra isoforms, particularly icIL-1Ra1, is stimulated in inflamed joints during CIA in mice. The combination of decreased production of IL-1beta and elevated levels of icIL-1Ra1 during the course of CIA was associated with a reduction in inflammatory activity. These results suggest that icIL-1Ra1 may play a role in the resolution of murine CIA.

Role of interleukin 1 and interleukin 1 receptor antagonist in the mediation of rheumatoid arthritis

Chronic arthritis is characterised by chronic joint inflammation and concurrent joint erosion and destruction. The inflammatory cytokine interleukin 1 (IL1) has been shown to be a key mediator in the autoimmune disease rheumatoid arthritis (RA). Interleukin 1 mediates bone resorption and cartilage destruction, but may not play as dominant a part in joint swelling and inflammation. Interleukin 1 receptor antagonist (IL1Ra) selectively inhibits the effects of IL1 by competing for the IL1 receptor on all surfaces of the synovium. In a randomised controlled trial in 472 patients with active disease, IL1Ra 30 mg/day, 75 mg/day or 150 mg/day given by subcutaneous injection significantly reduced the signs and symptoms of RA at 24 weeks. An American College of Rheumatology (ACR) 20% response was seen in 43% of the patients treated with 150 mg/day at 24 weeks. IL1Ra was well tolerated; injection site reactions were the most common adverse event. In another trial, in 419 patients with active RA treated concomitantly with methotrexate, there were ACR 20% responses after 24 weeks in 42% of the patients treated with 1 mg/kg/day by subcutaneous injection and in 35% of those treated with 2 mg/kg/day. I1Ra offers a unique selective, targeted mechanism of action to block the IL1 mediated effects of RA.

Acute systemic inflammation impairs endothelium-dependent dilatation in humans

BACKGROUND

We tested the hypothesis that endothelial dysfunction underlies the association between an acute inflammatory episode and the transiently increased risk of a cardiovascular event by examining the effects of an experimental inflammatory stimulus on endothelium-dependent vasodilation.

METHODS AND RESULTS

Salmonella typhi vaccine was used to generate a systemic inflammatory response in healthy volunteers. In 12 subjects, dilatation of the brachial artery to flow and to sublingual nitroglycerin (NTG) was recorded (conduit vessel response), and in 6 subjects, venous occlusion plethysmography was used to measure forearm blood flow during intrabrachial infusion of the endothelium-dependent dilators acetylcholine (ACh) and bradykinin (BK) and the endothelium-independent dilators NTG and verapamil (resistance vessel response). Responses were assessed 16 hours before and 8 and 32 hours after vaccination. Vaccination resulted in elevations in white cell count and serum levels of interleukin-6 and interleukin-1 receptor antagonist. Eight hours after vaccination, resistance vessel responses to BK (P:=0.0099) and ACh (P:=0.0414) were markedly attenuated, and brachial artery flow-mediated dilatation was depressed. Resistance vessel responses to verapamil and NTG were unchanged, as was the conduit vessel response to NTG. Thirty-two hours after vaccination, resistance vessel responses to BK and ACh had returned to normal.

CONCLUSIONS

S typhi vaccine generates a mild inflammatory reaction associated with temporary but profound dysfunction of the arterial endothelium in both resistance and conduit vessels to both physical and pharmacological dilator stimuli. This finding might explain the association between infection and inflammation and the enhanced risk of an acute cardiovascular event.

Development of chronic inflammatory arthropathy resembling rheumatoid arthritis in interleukin 1 receptor antagonist-deficient mice

Interleukin (IL)-1 is a proinflammatory cytokine that plays important roles in inflammation, host defense, and the neuro-immuno-endocrine network. IL-1 receptor antagonist (ra) is an endogenous inhibitor of IL-1 and is supposed to regulate IL-1 activity. However, its pathophysiological roles in a body remain largely unknown. To elucidate the roles of IL-1ra, IL-1ra-deficient mice were produced by gene targeting, and pathology was analyzed on different genetic backgrounds. We found that all of the mice on a BALB/cA background, but not those on a C57BL/6J background, spontaneously developed chronic inflammatory polyarthropathy. Histopathology showed marked synovial and periarticular inflammation, with articular erosion caused by invasion of granulation tissues closely resembling that of rheumatoid arthritis in humans. Moreover, elevated levels of antibodies against immunoglobulins, type II collagen, and double-stranded DNA were detected in these mice, suggesting development of autoimmunity. Proinflammatory cytokines such as IL-1beta, IL-6, and tumor necrosis factor alpha were overexpressed in the joints, indicating regulatory roles of IL-1ra in the cytokine network. We thus show that IL-1ra gene deficiency causes autoimmunity and joint-specific inflammation and suggest that IL-1ra is important in maintaining homeostasis of the immune system. Possible involvement of IL-1ra gene deficiency in RA will be discussed.

New therapeutic targets for rheumatoid arthritis

New insights into the pathogenesis of rheumatoid arthritis (RA) and consequently new targets of therapy are covered in a broad overview fashion. Short-term significant beneficial effect on RA disease activity has been established in a small but rapidly growing number of double-blind placebo-controlled trials now including recombinant human IL-1 receptor antagonist, chimeric (mouse/human) monoclonal antibodies (mAb) against TNF alpha (cA2), humanised (human/mouse) anti-TNF alpha mAb (CDP571) and recombinant human TNF-receptor-Fc fusion protein (TNFR:Fc). Placebo-controlled trials of anti-T cells agents such as chimeric anti-CD4 mAb (cM-T412) and anti-CD5 immunoconjugate, did not demonstrate clinical benefit. A placebo-controlled study of the anti-T cell derived cytokine IL-2 (DAB486IL-2) showed only modes clinical improvement. Other anti-T cell approaches such as autologous T cell vaccination and induction of tolerance by oral type II collagen have been unsuccessful. The one controlled trial with an anti-inflammatory cytokine, recombinant human IFN-gamma, showed modest clinical benefits. Controlled trials with IL-4 and IL-10 and with anti-adhesion molecules are awaited.

Treatment of rheumatoid arthritis with IL-1 inhibitors

Extensive evidence from both in vivo and in vitro experiments indicate that IL-1, a prototypic proinflammatory cytokine, is involved in the mechanisms that lead to progressive joint destruction in RA. IL-1Ra, a member of the IL-1 family, binds IL-1 receptors but does not induce any cellular responses. IL-1Ra competitively inhibits the binding of IL-1 to its cell surface receptors and thus, acts as an endogenous antiinflammatory mediator. However, the results of several studies suggest that a relatively deficient production in IL-1Ra as compared to that of IL-1 in RA synovium may predispose to the perpetuation of chronic inflammation. Systemic administration of IL-1Ra, or local delivery into the joint by gene therapy, in different experimental animal models of arthritis attenuated the severity of the inflammatory response and reduced articular destruction. In addition, treatment of rheumatoid patients with IL-1Ra led to an improvement in different clinical and biological parameters and to a reduction in the radiological signs of joint erosions. Encouraging results also have been reported in both in vitro and in vivo experimental animal models of arthritis through using other strategies designed to block the effects of IL-1 at the level of production, prevent the binding of IL-1 to its cell surface receptors, or interfere with the effects of IL-1 at the post-receptor level.

Retinoic acid differentially regulates interleukin-1beta and interleukin-1 receptor antagonist production by human alveolar macrophages

Mechanism in the pathogenesis of acute respiratory distress syndrome which is the clinical feature of pulmonary involvement in retinoic acid (RA) syndrome has been investigated. Pulmonary infiltration of matured neutrophils and leukemic cells is thought to be associated with the pathogenesis of pulmonary involvement in RA syndrome; however. Little is known about the mechanism in pulmonary infiltration of these cells. In the present study, we examined the effect of RA on IL-1beta and IL-1ra production by human alveolar macrophages in order to clarify the mechanism in pulmonary infiltration of neutrophils, since IL-1 has been shown to initiate neutrophil recruitment into the lung through up-regulated expression of adhesion molecules on vascular endothelium. RA enhanced IL-1beta and inhibited IL-1ra production by 4beta phorbol 12beta-myristate-13alpha acetate (PMA)- and lipopolysaccharide (LPS)-stimulated human alveolar macrophages. These results show that RA differentially regulates IL-1beta and IL-1ra production by alveolar macrophages and indicate that an imbalanced production between IL-1beta and IL-1ra may contribute to initiating neutrophil recruitment into the lung through up-regulated expression of adhesion molecules.

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.

Why do we need new treatments for rheumatoid arthritis?

Rheumatoid arthritis is a chronic systemic autoimmune inflammatory disease characterized by progressive joint damage. The classical treatments of the disease such as myocrisin and sulphasalazine, are not always effective at controlling the disease. This has necessitated the development of novel agents for treating rheumatoid arthritis. Most of these drugs are biological in nature and are targeted at specific sites of the inflammatory cascade of reactions. A number of clinical trials have been conducted. The clinical effects that have been observed are transient, necessitating repeated treatments and the risk of vaccination effects. Many of these agents have to be administered parenterally, production costs are very high. Consequently, chemical entities which can be taken orally need to be developed. Since the immune system is very complex with pleiotropic cytokines and redundancy in some of the regulatory networks, it may therefore be necessary to use multiple agents targeted at different specific sites of the inflammatory cascade or that different agents could be given at different stages of the disease, to induce disease remission and maintain the response to therapy. Cytokines such as tumour necrosis factor (TNF) and interleukin 1 (IL-1) play important physiological roles in the host's defence systems against infections and malignancy. The chronic inhibition of these cytokines by targeted therapies may therefore lead to the development of side effects. Thus, carefully controlled long-term studies will be required to assess the safety of selective targeting of processes involved in inflammation. A more recent novel approach is to target hypoxic tissues with bioreductive agents. Thus, some of the established rheumatoid arthritis treatments could be linked to bioreductive agents and released in hypoxic tissues where inflammation is occurring. This review summarizes the important developments in the therapy of rheumatoid arthritis. There is no doubt that despite these developments we need to develop new and advanced treatment modalities for rheumatoid arthritis.

Administration of neutralizing antibody against rabbit IL-1 receptor antagonist exacerbates lipopolysaccharide-induced arthritis in rabbits

Endogenous IL-1 receptor antagonist (IL-1ra) may down-regulate part of IL-1 actions. We examined the participation of endogenous IL-1ra in the production of IL-1 beta in vitro. Macrophages cultured on adherent IgG produced a 100-fold molar excess of IL-1ra, compared with IL-1 beta. In the presence of a neutralizing monoclonal antibody (mAb) against rabbit IL-1ra, the production of antigenic IL-1 beta increased by 20-60%. Since the molar ratio of IL-1ra over IL-1 was 160- to 400-fold in synovial fluid (SF) of lipopolysaccharide (LPS)-induced arthritis, we examined the functional role of endogenous IL-1ra in the regulation of inflammatory responses. When measured in the presence of anti-IL-1ra mAb, masked IL-1 activity in SF became evident, with a 3- to 4-fold increment. The administration of anti-IL-1ra mAb with LPS into rabbit knee joints increased the IL-1 activity 4-fold and the production of antigenic IL-1 beta by 30-50%. The treatment also enhanced by 20-40% LPS-induced leukocyte infiltration and protein leakage. Therefore, endogenous IL-1ra apparently acts as a down-regulating factor for limiting deleterious effects of IL-1 by masking the biological activity and by inhibiting the production.

Anticytokine treatment of established type II collagen-induced arthritis in DBA/1 mice. A comparative study using anti-TNF alpha, anti-IL-1 alpha/beta, and IL-1Ra

OBJECTIVE

To examine the role of tumor necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha), and IL-1 beta in collagen-induced arthritis (CIA), immediately after onset and during the phase of established arthritis.

METHODS

Male DBA/1 mice with collagen-induced arthritis were treated with antibodies against murine TNF alpha and IL-1 alpha/beta at different time points of the disease. IL-1 receptor antagonist (IL-1Ra) was administered using Alzet osmotic minipumps. The effect of anticytokine treatment was monitored by visual scoring. Histology and cytokine reverse transcription polymerase chain reaction (RT-PCR) analyses were performed at the end of the treatment period.

RESULTS

Anti-TNF alpha treatment showed efficacy shortly after onset of the disease, but had little effect on fully established CIA. Histologic analysis after early treatment revealed that anti-TNF alpha significantly reduced joint pathology, as determined by infiltration of inflammatory cells and cartilage damage. Anti-IL-1 alpha/beta treatment ameliorated both early and full-blown CIA. This clear suppression of established arthritis was confirmed by administration of high doses of IL-1Ra. Dose-response experiments showed that a continuous supply of 1 mg/day was needed for optimal suppression. Histologic analysis showed markedly reduced cartilage destruction both in the knee and the ankle joints. Autoradiography demonstrated full recovery of chondrocyte synthetic function of articular cartilage. In addition, we found that the IL-1 beta isoform plays a dominant role in established CIA. Profound suppression of CIA was observed with anti-IL-1 beta, although elimination of both IL-1 alpha and IL-1 beta still gave better protection. Analysis of messenger RNA with RT-PCR revealed that IL-1 beta was highly upregulated in synovium and cartilage at late stages of CIA, whereas anti-IL-1 beta treatment markedly reduced IL-1 beta message in the synovium.

CONCLUSION

The present study identified different TNF alpha/IL-1 dependencies in various stages of CIA and revealed that blocking of TNF alpha does not necessarily eliminate IL-1. Continuous, high doses of IL-1Ra are needed to block CIA.

The neuroendocrine immunology of rheumatoid arthritis

Rheumatoid arthritis patients have defective neuroendocrine-immune responses to the stress of inflammation, and currently available data shows that this contributes to the pathophysiology of the disease. The advances in neuroendocrine immunology have improved our understanding of the pathophysiological mechanisms involved in RA. These observations raise important therapeutic questions which are certainly worth further investigation as they may open up novel avenues for the management of the disease.

Elevated concentrations of interleukin-1 beta and interleukin-1 receptor antagonist in plasma of women with silicone breast implants

Plasma from 27 women with silicone breast implants (SBIs) and 50 age-matched control women without SBIs were examined by enzyme immunoassay for the presence of interleukin-1 beta (IL-1 beta) and its naturally occurring receptor antagonist, IL-1ra. The results show that 74% (20 of 27) of women with SBIs had elevated concentrations of IL-1ra, whereas only 2% (1 of 50) of controls without SBIs had elevated concentrations of IL-1ra. In contrast to the IL-1ra results, the frequency of elevated IL-1 beta concentrations among women with SBIs was only 40% (11 of 27), but this was significantly higher than the 0% (0 of 50) in control women without SBIs. These findings suggest that there is a chronic ongoing inflammatory process in some women with SBIs, the implications of which are discussed in the context of silicone as an antigenic stimulant of the immune system.