Interleukin 4 inhibits polyclonal immunoglobulin secretion and cytokine production by peripheral blood mononuclear cells from rheumatoid arthritis patients

Targeted delivery of cytokine therapy to rheumatoid tissue by a synovial targeting peptide

Objectives

The synovial endothelium targeting peptide (SyETP) CKSTHDRLC has been identified previously and was shown to preferentially localise to synovial xenografts in the human/severe combined immunodeficient (SCID) mouse chimera model of rheumatoid arthritis (RA). The objective of the current work was to generate SyETP-anti-inflammatory-cytokine fusion proteins that would deliver bioactive cytokines specifically to human synovial tissue.

Methods

Fusion proteins consisting of human interleukin (IL)-4 linked via a matrix metalloproteinase (MMP)-cleavable sequence to multiple copies of either SyETP or scrambled control peptide were expressed in insect cells, purified by Ni-chelate chromatography and bioactivity tested in vitro. The ability of SyETP to retain bioactive cytokine in synovial but not control skin xenografts in SCID mice was determined by in vivo imaging using nano-single-photon emission computed tomography-computed tomography (nano-SPECT-CT) and measuring signal transducer and activator of transcription 6 (STAT6) phosphorylation in synovial grafts following intravenous administration of the fusion protein.

Results

In vitro assays confirmed that IL-4 and the MMP-cleavable sequence were functional. IL-4-SyETP augmented production of IL-1 receptor antagonist (IL-1ra) by fibroblast-like synoviocytes (FLS) stimulated with IL-1β  in a dose-dependent manner. In vivo imaging showed that IL-4-SyETP was retained in synovial but not in skin tissue grafts and the period of retention was significantly enhanced through increasing the number of SyETP copies from one to three. Finally, retention correlated with increased bioactivity of the cytokine as quantified by STAT6 phosphorylation in synovial grafts.

Conclusions

The present work demonstrates that SyETP specifically delivers fused IL-4 to human rheumatoid synovium transplanted into SCID mice, thus providing a proof of concept for peptide-targeted tissue-specific immunotherapy in RA. This technology is potentially applicable to other biological treatments providing enhanced potency to inflammatory sites and reducing systemic toxicity.

Time course of changes in inflammatory markers during a 6-mo exercise intervention in sedentary middle-aged men: a randomized-controlled trial

Regular exercise may improve systemic markers of chronic inflammation, but direct evidence and dose-response information is lacking. The objective of this study was to examine the effect and time course of changes in markers of chronic inflammation in response to progressive exercise training (and subsequent detraining). Forty-one sedentary men 45-64 yr of age completed either a progressive 24-wk exercise intervention or control followed by short-term removal of the intervention (2-wk detraining). Serum IL-6 fell by -0.4 pg/ml (SD 0.6) after 12 wk and responded to moderate-intensity exercise. Serum alanine aminotransferase (ALT) activity fell -7 U/l (SD 11) at 24 wk although there was no evidence of any change by week 12 (and therefore ALT required more vigorous-intensity activity and/or a more prolonged intervention). The effect on IL-6 was lost after 2-wk detraining whereas the change in ALT was retained. The temporal fall and rise in IL-6 with training and subsequent detraining in men with high IL-6 at baseline provided a retrospective opportunity to examine parallel genomic changes in peripheral mononuclear cells. A subset of 53 probes was differentially regulated by at least twofold after training with 31 of these changes being lost after detraining (n = 6). IL-6 responded quickly to the carefully monitored exercise intervention (within weeks) and required only moderate-intensity exercise, whereas ALT took longer to change and/or required more vigorous-intensity exercise. Further work is required to determine whether any of the genes that temporally changed in parallel with changes in IL-6 are a cause or consequence of this response.

Increased prevalence of allergic sensitisation in rheumatoid arthritis patients treated with anti-TNFalpha

INTRODUCTION

Tumour necrosis factor alpha (TNFalpha) has emerged as a therapeutic target in chronic inflammatory disorders characterised by a Th1 type immune response, such as rheumatoid arthritis (RA). The presence of allergic disease in these patients could be influenced both by the presence of RA and anti-TNFalpha therapy. Our aim was to evaluate the prevalence of sensitisation to airborne allergens and allergic disease in RA patients, with and without anti-TNFalpha treatment.

METHODS

RA patients with (N=20) and without (N=20) anti-TNFalpha therapy (groups T and R) were enrolled. Healthy controls (N=60, group C) were randomly selected from the general population. All participants answered a standardised questionnaire to assess the prevalence of allergic disease and had skin prick tests (SPT) with a standard panel of airborne allergen extracts.

RESULTS

Significant differences were found in the prevalence of positive SPT between groups T and R (70% vs 35%, p=0.027) and groups T and C (70% vs 36.7%, p=0.009), but not between groups R and C. The prevalence of allergic disease was similar in the three groups. Groups T and R had similar gender and age distribution, disease duration, disease activity score (DAS28), erythrocyte sedimentation rate and serum C-reactive protein.

CONCLUSIONS

Increased prevalence of sensitisation to airborne allergens in RA patients treated with anti-TNFalpha was found. The clinical impact of the positive SPT following anti-TNFalpha initiation has now to be assessed.

A shift in the balance of inhibitory and activating Fc? receptors on monocytes toward the inhibitory Fc? receptor IIb is associated with prevention of monocyte activation in rheumatoid arthritis

OBJECTIVE

To assess surface expression of the inhibitory receptor for IgG (Fcgamma receptor IIb [FcgammaRIIb]) in relation to activating FcgammaR on monocyte/macrophages from patients with rheumatoid arthritis (RA) and healthy controls and to study the influence of proinflammatory and antiinflammatory cytokines on the balance of inhibitory and activating FcgammaR.

METHODS

Using a combination of genotyping and phenotyping, surface expression of FcgammaRIIb on monocytes from healthy control subjects and RA patients was demonstrated. Expression of FcgammaR on CD14+ monocytes was assessed by flow cytometry. Regulation of inhibitory and activating FcgammaR on monocytes by proinflammatory (interferon-gamma [IFNgamma], tumor necrosis factor alpha [TNFalpha]) and antiinflammatory (interleukin-4 [IL-4], IL-10) cytokines was studied. A functional change in cytokine-modulated monocytes was assessed in secondary cultures by their ability to produce TNFalpha upon FcgammaR crosslinking by IgG.

RESULTS

Monocytes from healthy controls and RA patients expressed FcgammaRIIb at similar levels, in contrast to the higher levels of activating FcgammaRI and FcgammaRIIa in RA patients. The regulation of FcgammaR expression was comparable for patients and controls. IFNgamma selectively up-regulated FcgammaRI. TNFalpha down-regulated expression of FcgammaRIIb and the activating FcgammaR, whereas IL-10 up-regulated expression of monocytic FcgammaRIIb and all activating FcgammaR. Increased or sustained levels of activating over inhibitory FcgammaR induced by IFNgamma, TNFalpha, and IL-10 alone were associated with enhanced IgG-triggered TNFalpha production. In contrast, IL-4 and, more specifically, IL-4 plus IL-10 altered the FcgammaR balance in favor of FcgammaRIIb and completely prevented IgG-triggered TNFalpha production.

CONCLUSION

The altered balance of FcgammaR in favor of activating receptors in RA may contribute to increased activation of monocyte/macrophages. A change in the FcgammaR balance toward the inhibitory FcgammaRIIb may offer a novel treatment strategy for preventing the pleiotropic activity of FcgammaR-triggered macrophages.

Potential biologic agents for treating rheumatoid arthritis

The encouraging clinical results observed in trials using anti-TNF therapy clearly warrant further studies to determine whether TNF inhibitors are capable of modifying the destructive component of this disease in long-term follow-up studies as well as to assess the safety of long-term use (see the article by Keystone in this issue). It is also reasonable to propose that interfering with the cytokine cascade earlier in the course of disease may be of even greater therapeutic benefit. As the pathogenetic mechanisms in RA are more clearly defined, especially in early disease and in those individuals destined to develop severe disease, the potential of other biologic agents to specifically inhibit these critical pathways may provide better treatments for our patients. Many potential targets in the immune-mediated process of RA are currently being rigorously evaluated in clinical trials. Use of combinations of biologic therapies, perhaps in human patients with RA, should be of considerable interest in future trials.

Reduced incidence and prevalence of atopy in rheumatoid arthritis. Results of a case-control study

OBJECTIVE

To determine the cumulative incidence and the point prevalence of atopy in patients with rheumatoid arthritis (RA).

PATIENTS AND METHODS

A standardized questionnaire was sent to 300 RA patients. Questions concerned previous or present characteristics of atopy (hay fever, asthma and constitutive eczema) and RA. RA patients were matched with genetically unrelated controls (sister- or brother-in-law, neighbour or friend). The same questionnaire (except for questions about RA) was sent to the control subjects. In cases of atopy, patients, controls and the treating physicians were contacted by a physician to check the validity of the responses.

RESULTS

Paired responses were obtained in 173 cases. Information about atopy was obtained for 69 other RA patients. The characteristics of RA were similar for patients who responded and those who did not respond. The frequency of atopy was significantly lower in RA patients than in controls, both for cumulative incidence (RA 7.5%, controls 18.8%; P: < 0.01) and point prevalence (RA 3.5%, controls 16.2%; P: < 0.0001). The clinical manifestations of atopy stopped before the onset of RA in eight of the 17 RA patients with an allergic condition, and there was no subsequent relapse. No effect of RA treatment could account for the remission of atopy.

CONCLUSION

These data support the concept that atopy protects against the future development of RA and that the two diseases could counterbalance one another.

T Helper 1 Response Is Dominant and Localized to the Synovial Fluid in Patients with Lyme Arthritis

Cytokines produced by subsets of CD4+ T helper cells responding to an infection influences the efficiency with which the host is able to mount a protective immune response. In an attempt to elucidate the population of active cells involved in the propagation of Lyme arthritis we have utilized intracellular cytokine staining to analyze the polyclonal immune response at the single cell level. We have determined the Th phenotype in the synovial fluid of patients with a variety of chronic inflammatory arthritides, including patients representative of the spectrum of Lyme arthritis. Th1 cells dominate the immune response in the synovial fluid of patients with Lyme as well as those with rheumatoid or other types of chronic inflammatory arthritis. In addition, the severity of Lyme arthritis directly correlates with the ratio of Th1 to Th2 cells in the synovial fluid, such that the larger the effusion, the higher the ratio (r = 0.67, p &lt; 0.05). These results suggest that Th1 cells play a direct role in the pathogenesis of the inflammatory process seen in Lyme arthritis, and that Th2 cells modulate the pro-inflammatory response generated by Th1 cells in the joint. Finally, we identify Th1 cells specific for outer surface protein A of Borrelia burgdorferi, the agent of Lyme disease. These cells are restricted to patients with Lyme arthritis and are localized to the joint. Furthermore, they persist in patients with prolonged antibiotic treatment-resistant Lyme arthritis, suggesting the possibility of an autoimmune process.

Interleukin-4 blocks the release of collagen fragments from bovine nasal cartilage treated with cytokines

Interleukin-1 (IL-1) in combination with other cytokines can induce a reproducible release of collagen fragments from bovine nasal cartilage in culture. Over 70% of the total collagen is released by day 14 and this release is accompanied by the appearance of collagenolytic activity in the medium that cleaves collagen specifically at the one quarter/three quarter position. Interleukin-4 is able to prevent the release of collagen fragments from the tissue and this is accompanied by a reduced secretion and activation of collagenase (MMP-1) with an increase in tissue inhibitor of metalloproteinases-1 (TIMP-1). IL-4, especially in the presence of IL-1, increased TIMP secretion by bovine nasal cartilage in culture. These results suggest that IL-4 is able to specifically block cartilage collagen resorption by down-regulating the production of collagenase (MMP-1) and up-regulating TIMP-1 by chondrocytes within the cartilage.

Prevention and reversal of cartilage degradation in rheumatoid arthritis by interleukin-10 and interleukin-4

OBJECTIVE

Inflammation-induced articular cartilage degradation is a major problem in rheumatoid arthritis (RA). Type 1 T cell activity (characterized by interferon-gamma/interleukin-2 [IL-2] production), and consequently, the production of the proinflammatory cytokines IL-1 and tumor necrosis factor alpha (TNF alpha), have been reported to play a major role in cartilage damage. IL-10 and IL-4, both produced by type 2 T cells, are cytokines with the capacity to down-regulate proinflammatory responses. The present study was undertaken to investigate the way in which these cytokines affect activated mononuclear cells (MNC) of RA patients in relation to human articular cartilage degradation in vitro.

METHODS

MNC from synovial fluid and peripheral blood of RA patients were stimulated with bacterial antigen and treated with IL-10 and/or IL-4. Bacterial antigen is known to activate type 1 T cells and to induce proinflammatory IL-1/TNF alpha-dependent cartilage damage. Cytokine production and effects of conditioned media, as well as effects of IL-10 and IL-4 on proteoglycan (PG) turnover (as a measure for cartilage damage), were determined.

RESULTS

IL-10 and IL-4 inhibited proinflammatory cytokine production of stimulated RA MNC and completely reversed inhibition of cartilage PG synthesis induced by these stimulated RA MNC. IL-10 was more potent than IL-4 in this respect, and the combination of IL-10 and IL-4 had an additive effect. In addition, IL-10 directly stimulated cartilage PG synthesis.

CONCLUSION

IL-10 reverses the cartilage degradation induced by antigen-stimulated MNC, and IL-4 has an additive effect on this process. Furthermore, IL-10 has a direct stimulatory effect on PG synthesis, and IL-4, as a growth factor for type 2 T cells, can reduce the ratio of type 1 to type 2 T cell activity. These results provide evidence in favor of the use of a combination of the two cytokines in the treatment of RA.

Proinflammatory cytokine production and cartilage damage due to rheumatoid synovial T helper-1 activation is inhibited by interleukin-4

OBJECTIVES

To investigate the role of T helper-1 cell (Th1) activation in the induction of proinflammatory cytokine production and cartilage damage by rheumatoid arthritis (RA) synovial fluid mononuclear cells (SFMNC) and the subsequent possible beneficial role of the T helper-2 cell (Th2) cytokine interleukin-4 (IL-4) in the inhibition of this process.

METHODS

SFMNC were stimulated with bacterial antigen (hsp60) to activate Th1 cells. Th1 and Th2 specific cytokine profiles (interferon gamma (IFN gamma) and IL-4) and proinflammatory cytokines interleukin-1 (IL-1) and tumour necrosis factor alpha (TNF alpha) in the conditioned media were analysed. In addition, the conditioned media were tested for their ability to induce cartilage damage. The same parameters were measured in the presence of IL-4.

RESULTS

Stimulation of SFMNC with bacterial antigen resulted in an increase in IFN gamma, IL-1, and TNF alpha production which was accompanied by the induction of cartilage damage. Th1 activation could be inhibited by IL-4 as shown by a reduction of IFN gamma. This was accompanied by a decrease in IL-1 and TNF alpha production and inhibition of cartilage damage.

CONCLUSIONS

Th1 activation is a possible mechanism by which inflammation in RA joints is enhanced. The Th2 cytokine IL-4 inhibits this Th1 activity and may diminish inflammation and induction of cartilage damage in RA joints.

Effects of Th1 and Th2 cytokines on cytokine production and ICAM-1 expression on synovial fibroblasts

OBJECTIVES

To investigate the influence of the Th1 and Th2 lymphokines interleukins (IL)-4 and IL-13, interferon gamma (IFN gamma), and several monokines on the adhesion of mononuclear cells to synovial fibroblasts and intercellular adhesion molecule-1 (ICAM-1) expression and cytokine production of synovial fibroblasts in patients with osteoarthritis.

METHODS

Synovial fibroblasts were isolated from patients with osteoarthritis and stimulated with IL-1 beta, IL-4, IL-6, IL-10, IL-12, IL-13, tumour necrosis factor alpha (TNF alpha), and IFN gamma. Subsequently, we determined the production of IL-1 alpha, IL-1 beta, IL-6, IL-10, IL-12, IFN alpha and TNF alpha, and the expression of ICAM-1 lymphocyte function associated antigen 3 (LFA-3), BB7, and major histocompatibility complex class II molecules on these cells. Furthermore, the adhesion of freshly isolated mononuclear cells from the peripheral blood was tested using a colourimetric cell-cell adhesion assay.

RESULTS

Only production of IL-6 and the expression of ICAM-1 were observed. IL-1 beta and TNF alpha were the most potent stimulatory mediators of both cytokine production and ICAM-1 expression. IL-4 and IL-13 had differential effects as they upregulated cytokine production but downregulated IFN gamma induced ICAM-1 expression. In functional adhesion assays, TNF alpha, IL-1 alpha and, to a lesser extent, IFN gamma led to increased adhesion of mononuclear cells, whereas IL-4 and IL-13 had no effect.

CONCLUSIONS

Our data indicate that Th1 and Th2 lymphokines can modulate the function (cytokine production and expression of adhesion molecules) of synovial fibroblasts.

Serum IL-4, IL-10 and IL-6 levels in inflammatory arthritis

As the available in vitro and in vivo data suggest that interleukin (IL)-4 and IL-10 have immunosuppressive activity, our hypothesis was that serum IL-4 and IL-10 levels would correlate inversely with parameters of inflammation in patients with inflammatory arthritis. IL-4 was detected in the serum of 12 out of 140 patients with rheumatoid arthritis (RA), which was increased compared to the proportion found with patients with osteoarthritis (OA; P < 0.02). In addition, IL-4 was detected in the serum of 2 of 19 patients with systemic lupus erythematosus (SLE), 2 of 24 patients with psoriatic arthritis and 1 of 5 patients with Behçet's syndrome. No IL-4 was detected in patients with the following conditions: OA (58 patients), gout (17 patients), ankylosing spondylitis (6 patients), Reiter's syndrome (6 patients), polymyalgia rheumatica (6 patients), temporal arteritis (5 patients) and scleroderma (3 patients). No IL-10 was detected in any of the sera tested. We discuss the possible relevance of these results to the regulation of the immune response evident in inflammatory arthritis.

Interleukin-4 but not interleukin-10 inhibits the production of leukemia inhibitory factor by rheumatoid synovium and synoviocytes

The expression of the proinflammatory cytokine leukemia inhibitory factor (LIF) has been reported in the cartilage and synovium of rheumatoid arthritis (RA) patients. Here, we show that high levels of LIF were constitutively produced by cultures of synovium pieces. Low levels of LIF were produced spontaneously by isolated synoviocytes, but interleukin (IL)-1 beta caused a fourfold enhancement of this secretion. The anti-inflammatory cytokine IL-4 reduced the production of LIF by synovium pieces by 75%, as observed earlier with IL-6, IL-1 beta and tumor necrosis factor (TNF)-alpha. IL-4 had a direct effect since it inhibited LIF production by unstimulated and IL-1 beta- or TNF-alpha-stimulated synoviocytes. Conversely, IL-4 enhanced the production of IL-6, which shares with LIF biological activities and receptor components. The inhibitory effect of IL-4 was dose dependent and was reversed using a blocking anti-IL-4 receptor antibody. Similar inhibitory action of IL-4 on LIF production was observed on synovium pieces from patients with osteoarthritis and on normal synoviocytes. IL-10, another anti-inflammatory cytokine acting on monocytes, had no effect on LIF production by either synovium pieces or isolated synoviocytes. Thus, the production of LIF by synovium tissue was inhibited by IL-4 through both a direct effect on synoviocytes and an indirect effect by inhibition of the production of LIF-inducing cytokines.

Rheumatoid inflammatory T-cell clones express mostly Th1 but also Th2 and mixed (Th0-like) cytokine patterns

This study was performed in order to characterize whether T cells from rheumatoid synovial inflammation belong to the Th1- or Th2-like functional subsets. Cytokine production was studied in 26 CD4+ alpha beta+ and 2 CD8+ alpha beta T-cell clones from the synovial fluid, the synovial membrane and peripheral blood of 5 patients. Fifteen of the CD4+ clones were raised against various mycobacterial antigens and 11 CD4+ clones and 2 CD8+ clones were raised unspecifically using PHA and/or IL-2. The specificities of these clones are not known. In the mycobacterial antigen-specific group, all CD4+ alpha beta T-cell clones produced IFN-gamma at high levels, while the production of IL-4 was generally absent or low (< 1 ng/ml), consistent with a Th1-like profile. Some of these clones, however, also produced various amounts of IL-10 which has been regarded as a Th2 product but can be produced also in lower amounts by Th1 cells. One HSP-65-specific clone produced levels of IL-4 and IL-10 in the same order as that of IFN-gamma, thus appearing to be Th0-like. Among the 11 unspecific CD4+ clones, 7 showed a Th1-like pattern but with lower levels of IFN-gamma than the antigen-specific clones. However, three clones did not produce any IFN-gamma activity but produced IL-4 and one of them also produced distinct amounts of IL-10, compatible with a Th2-like pattern. In addition, one of the clones also showed an almost equally strong IFN-gamma and IL-4 production, thus most likely representing a Th0-like clone.

Increased production of soluble CD23 in rheumatoid arthritis, and its regulation by interleukin-4

OBJECTIVE

To assess CD23 status in rheumatoid arthritis (RA) patients, as defined by the levels of CD23 expression on peripheral blood mononuclear cells (PBMC), the levels of soluble CD23 (sCD23) in sera, and the production of sCD23 by PBMC cultures and its regulation by interleukin-4 (IL-4).

METHODS

CD23 expression as determined by double fluorescence-activated cell sorter analysis and sCD23 production as determined by immunoradiometric assay were investigated in 24 RA patients and 21 controls. Soluble CD23 was measured in sera and supernatants of PBMC, activated with polyclonal activators (pokeweed mitogen [PWM] or Staphylococcus aureus Cowan strain 1, [SAC]) used either alone or in combination with IL-2 or IL-4.

RESULTS

The percentage of B cells expressing CD23 and serum levels of sCD23 were increased in patients with RA. IL-4 was a potent inducer of sCD23 production in supernatants, whereas IL-2 was inactive. Costimulation with SAC or PWM did not increase the effect obtained with IL-4 alone. When sCD23 levels in RA and control supernatants were compared, spontaneous production was found to be increased in RA PBMC: This difference from control values was even more pronounced when sCD23 levels in PBMC and purified B cells in response to IL-4, either alone or in combination with SAC or PWM, were tested. In the same supernatants, the increased secretion of sCD23 induced by IL-4 was associated with an inhibitory effect of IL-4 on Ig production, a phenomenon that was more pronounced in RA PBMC than in controls.

CONCLUSION

CD23 status in RA is characterized by increased expression of CD23 on B cells, increased production of sCD23 in sera and supernatants, and increased sensitivity of RA PBMC and B cells to IL-4.

Inhibition of the production of proinflammatory cytokines and immunoglobulins by interleukin-4 in an ex vivo model of rheumatoid synovitis

OBJECTIVE

To assess the spontaneous production of proinflammatory cytokines and immunoglobulins in rheumatoid arthritis (RA) synovitis and modulation by interleukin-4 (IL-4).

METHODS

We developed an ex vivo model of RA synovitis using pieces of RA synovium, and have studied the regulation of the production of IL-1 beta, IL-6, tumor necrosis factor alpha (TNF alpha), IgM, and IgG.

RESULTS

Spontaneous production of proinflammatory cytokines in vitro was active, with prolonged cytokine gene transcription and translation. IL-6 was produced at higher levels than either IL-1 beta or TNF alpha, and explants produced more IgG than IgM. In contrast, IL-4 and interferon-gamma were undetectable. When pieces of synovium were incubated in the presence of IL-4, reduction of spontaneous proinflammatory cytokine and Ig production was observed.

CONCLUSION

These results extend the observations of the antiinflammatory properties of IL-4 to an ex vivo situation, and provide the rationale for the clinical use of IL-4 in RA.

Cytokine abnormalities in inflammatory arthritis

Cytokines are soluble molecules which control communication between cells of the immune and non-immune systems. Studies on their role in the pathogenesis of inflammatory arthritis have been increased with the discovery of new cytokines and the development of assays for their detection. Conditions such as rheumatoid arthritis are characterized by increased production of proinflammatory cytokines in association with reduced control by regulatory cytokines produced by T lymphocytes. The inadequate inhibition of proinflammatory cytokines by anti-inflammatory cytokines and other regulatory mechanisms contributes to this cytokine imbalance. This situation is responsible for the enhanced degradation, without sufficient repair activity. These results have provided the rationale for the use of cytokines as well as for drug targeting of the cytokine network in rheumatoid arthritis. This also includes the modulation of the cytokine network by targeting the level of the receptors as well as the effects and/or the responding cells.