Suppressive effect of interleukin-4 (IL-4) on IL-6 production by adherent rheumatoid synovial cells

Significance of Interleukin (IL)-4 and IL-13 in Inflammatory Arthritis

Interleukin (IL)-4 and IL-13 belong to the T helper 2 (Th2) cytokine family, along with IL-3, IL-5, and IL-9. These cytokines are key mediators of allergic inflammation. They have important immunomodulatory activities and exert influence on a wide variety of immune cells, such as B cells, eosinophils, basophils, monocytes, fibroblasts, endothelial cells, airway epithelial cells, smooth muscle cells, and keratinocytes. Recent studies have implicated IL-4 and IL-13 in the development of various autoimmune diseases. Additionally, these cytokines have emerged as potential players in pathogenesis of inflammatory arthritis. Recent findings suggest that the IL-4 and IL-13 might play a significant role in the downregulation of inflammatory processes underlying RA pathology, and beneficially modulate the course of the disease. This review summarizes the biological features of the IL-4 and IL-13 and provides current knowledge regarding the role of these cytokines in inflammatory arthritis.

Effect of interleukin-4 on vascular endothelial growth factor production in rheumatoid synovial fibroblasts

Interleukin (IL)-4 has been demonstrated to have anti-inflammatory and anti-tumour activity. Because aberrant angiogenesis is a significant pathogenic component of tumour growth and chronic inflammation, we investigated the effect of IL-4 on the production of vascular endothelial growth factor (VEGF) by synovial fibroblasts derived from patients with rheumatoid arthritis (RA). Fibroblast-like synoviocytes (FLS) were prepared from synovial tissues of RA and incubated with different concentrations of IL-4 in the presence or absence of transforming growth factor (TGF)-beta. VEGF level was measured by enzyme-linked immunosorbent assay and semiquantitative reverse transcription--polymerase chain reaction. Treatment of FLS with IL-4 alone caused a dose-dependent increase in VEGF levels. In contrast, IL-4 exhibited the inhibitory effect on VEGF production when FLS were stimulated with TGF-beta. Combined treatment of IL-4 and IL-10 inhibited TGF-beta-induced VEGF production in an additive fashion. TGF-beta increased the induction of cyclooxygenase-2 mRNA, which was inhibited significantly by the treatment of IL-4. NS-398, a COX-2 inhibitor, inhibited TGF-beta-induced VEGF production in a dose-dependent manner. Furthermore, exogenous addition of prostaglandin E2 (PGE2) restored IL-4 inhibition on TGF-beta induced VEGF production. Collectively, our results suggest that IL-4 have an anti-angiogenic effect, especially in the inflammatory milieu of RA by inhibiting the VEGF production in synovial fibroblasts.

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.

Interleukin-4 inhibits RANKL-induced expression of NFATc1 and c-Fos: a possible mechanism for downregulation of osteoclastogenesis

Interleukin-4 (IL-4), an anti-inflammatory cytokine, has been shown to inhibit osteoclast differentiation. Therefore, this cytokine is considered to be a promising therapeutic applicant for bone-resorbing diseases such as rheumatoid arthritis (RA). Recently NFATc1, a transcription factor, has been shown to play critical roles in osteoclastogenesis. The aim of this study was to clarify the role of IL-4 on the intracellular signaling of NFATc1. A RAW264.7 monocyte/macrophage cell line and murine bone marrow precursors were differentiated into osteoclasts in the presence of receptor activator of nuclear factor kappaB ligand (RANKL) and/or macrophage colony-stimulating factor. Tartrate-resistant acid phosphatase (TRAP) staining and a pit assay using dentine were used for the identification of activated osteoclasts. The protein expression of IL-4 receptor, NFATc1, and c-Fos was determined by Western blot analysis. In addition, the gene expression of NFATc1 and c-Fos was determined by reverse transcription and polymerase chain reaction. The IL-4 receptor was constitutively expressed in RAW264.7 cells. RANKL induced osteoclast generation, as determined by TRAP staining and pit assay. IL-4 inhibited RANKL-induced osteoclastogenesis at low concentrations of 10ng/ml and more. Interestingly, IL-4 potently inhibited RANKL-induced expression of NFATc1 at mRNA level. Furthermore, IL-4 inhibited c-Fos expression, which is shown to be responsible for NFATc1 expression, in time- and dose-dependent manners. In addition, IL-4 inhibited the RANKL-induced expression of NFATc1 and c-Fos in murine bone marrow cells. Thus, we suggest that IL-4 may downregulate osteoclastogenesis in part through inhibition of the expression of transcription factors, NFATc1 and c-Fos. These findings provide new insight into development of new medication for osteoporosis and RA.

Local levels of interleukin-1beta, -4, -6 and tumor necrosis factor alpha in an experimental model of murine osteomyelitis due to staphylococcus aureus

The purpose of this study is to evaluate local levels of interleukin-1 beta (IL-1 beta), -4 (IL-4), -6 (IL-6), and tumour necrosis factor-alpha (TNF-alpha), in a model of murine osteomyelitis due to Staphylococcus aureus. Cytokine levels in supernatants derived from bone homogenates were determined by enzyme-linked immunosorbent assay, for 28 days following the direct implantation of murine tibiae with S.aureus. Levels of IL-1 beta and IL-6 in infected bone were elevated in the early post-infection period and then decreased. In contrast, TNF-alpha levels remained elevated 3 to 28 days post-infection, while IL-4 levels were elevated late in the course of infection. The histopathology of infected bone showed predominant infiltration of inflammatory cells and bone resorption 3 to 7 days after infection, and bone resorption and adjacent areas of formation 14 to 28 days after infection. These results suggest that the elevated IL-1 beta and IL-6 levels induced by infection may be related to bone damage mainly in the early phase of infection, and that TNF-alpha and IL-4 may at least in part be associated with histopathological changes, including both bone resorption and formation in the later phase of this osteomyelitis model.

Kallikrein cascade and cytokines in inflamed joints

Rheumatoid arthritis is a chronic multi-system disease of unknown aetiology. The current hypothesis is that an unknown antigen triggers an autoimmune response in a genetically susceptible individual. The predominant pathological change is that of an inflammatory synovitis, characterised by cellular infiltrates and angiogenesis, with subsequent bone and cartilage destruction. These pathological changes are as a result of the activation of a variety of cells, inflammatory mediators, and effector molecules. The pro-inflammatory kinins and cytokines appear to play a central role in the pathogenesis of rheumatoid arthritis. Sufficient evidence exists that establishes a key role for the kallikrein-kinin cascade in inflamed joints. In addition, there appears to be an inter-relationship between cytokines and kinins in the inflammatory process. Kinins induce the release of cytokines, and cytokines have been shown to augment the effects of kinins. This may lead to an enhancement and perpetuation of the inflammatory process. In this review, we report a first study, correlating markers of disease with the kallikrein-kinin cascade and with cytokines.

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.

Interleukin-4 inhibits interleukin-11 production by rheumatoid synovial cells

OBJECTIVE

To examine the effect of interleukin-4 (IL-4) on IL-11 production by rheumatoid synovial cells.

METHODS

Freshly isolated rheumatoid synovial cells (FRS) were obtained by collagenase digestion of rheumatoid arthritis (RA) synovial tissue specimens taken at the time of operation. Rheumatoid synovial cells at four to eight passages were used as cultured rheumatoid synovial fibroblasts (RSF). IL-11 concentration was measured by ELISA.

RESULTS

IL-4 inhibited the production of IL-11 by FRS in a dose-dependent manner. This inhibition was observed in FRS obtained from six patients, and the mean inhibition was 46.5%. The inhibitory effect of IL-4 on IL-11 production was cancelled by the addition of anti-IL-4 antibody. IL-4 also inhibited IL-11 production by IL-1alpha-stimulated cultured RSF.

CONCLUSION

IL-4 inhibited IL-11 production by rheumatoid synovial cells. IL-4 has a protective effect on bone resorption. On the contrary, IL-11 participates in bone resorption via osteoclastogenesis. Therefore, IL-4 may exert its protective effect on bone resorption, at least in part, via inhibition of IL-11 production in rheumatoid joints.

Gene therapy for established murine collagen-induced arthritis by local and systemic adenovirus-mediated delivery of interleukin-4

To determine whether IL-4 is therapeutic in treating established experimental arthritis, a recombinant adenovirus carrying the gene that encodes murine IL-4 (Ad-mIL-4) was used for periarticular injection into the ankle joints into mice with established collagen-induced arthritis (CIA). Periarticular injection of Ad-mIL-4 resulted in a reduction in the severity of arthritis and joint swelling compared with saline- and adenoviral control groups. Local expression of IL-4 also reduced macroscopic signs of joint inflammation and bone erosion. Moreover, injection of Ad-mIL-4 into the hind ankle joints resulted in a decrease in disease severity in the untreated front paws. Systemic delivery of murine IL-4 by intravenous injection of Ad-mIL-4 resulted in a significant reduction in the severity of early-stage arthritis.

Activation of the IL-4 STAT pathway in rheumatoid synovium

STATs act as second messenger after binding of a signaling molecule to its receptor. IL-4 STAT is directly involved in the IL-4-dependent gene transcription in the nucleus. We examined the expression and activation of IL-4 STAT and its related kinase Jak-1 in rheumatoid synovium. Rheumatoid arthritis (RA) synovial frozen sections of patients with short-term (<1 year) and long-term disease (>2 years) were examined using in situ hybridization and immunohistochemistry. IL-4 STAT mRNA could be detected in synovium of patients with short-term and long-term RA. The most intensive expression of IL-4 STAT mRNA could be seen in follicular inflammatory infiltrates. In the synovial lining, both fibroblasts and macrophages expressed IL-4 STAT mRNA. IL-4 STAT and Jak-1 protein was expressed by synoviocytes, and up-regulation could be induced after stimulation with IL-4. Activation of IL-4 STAT was reflected by phosphorylation of IL-4 STAT. The results indicate that IL-4 STAT is involved in key pathomechanisms in RA synovium and that IL-4 STAT-dependent pathways operate in early and late stages of the disease and presumably contribute to inhibitory immune mechanisms in RA synovium.

IL-17 regulates gene expression and protein synthesis of the complement system, C3 and factor B, in skin fibroblasts

Human IL-17 is a cytokine secreted by CD4+-activated memory T cells with the profile of effects of a Th1 cytokine. The effects of IL-17 on many cellular constituents of joints suggest that it may participate in inflammatory joint diseases. Proteins of the complement system are known to be regulated by pro- and anti-inflammatory cytokines. The purpose of this work was to study the effect of IL-17 alone and combined with tumour necrosis factor (TNF) on the expression and synthesis of factor B and C3. Fibroblasts were stimulated with the relevant cytokine or cytokines, pulse labelled with 35S-methionine, and the newly synthesized proteins were immunoprecipitated and subjected to SDS-PAGE. Gene expression was determined by Northern blot analysis. IL-17 10 ng/ml induced increases in gene expression and protein synthesis of C3, 2.25 +/- 0.26- and 2.7 +/- 0.7-fold, respectively with concomitant non-significant effects on factor B, 1.5 +/- 0.45- and 2.2 +/- 1. 2-fold, respectively. When both IL-17 and TNF were present simultaneously, the synthesis of factor B increased by 85% more than the expected additive effects of these cytokines separately, while for C3 the effect of both cytokines was 19% lower than the expected additive effect (observed/expected = 0.81). IL-4 reduced the synergistic effect by 50%. We conclude that IL-17 has a regulatory role on C3 expression and synthesis and an amplifying effect on TNF-induced factor B synthesis. Taken together with the evidence that TNF is a major cytokine involved in the inflammation of rheumatoid arthritis, it suggests that IL-17 has a proinflammatory role in the inflammation process of joints. The distinct effects of IL-4, IL-17 and TNF on the synthesis of factor B in fibroblasts suggest that factor B and the alternative pathway of the complement system may play an important role in joint inflammation.

Taurine chloramine inhibition of cell proliferation and cytokine production by rheumatoid arthritis fibroblast-like synoviocytes

OBJECTIVE

To examine whether taurine (Tau) or its physiologic chlorinated derivative, taurine chloramine (Tau-CI), affects proliferation of, and proinflammatory cytokine (interleukin-6 [IL-6] and IL-8) production by, fibroblast-like synoviocytes (FLS) isolated from rheumatoid arthritis (RA) patients.

METHODS

FLS, isolated from the synovial tissue of 19 RA patients and cultured in vitro for 3-6 passages, were stimulated with the recombinant human cytokines IL-1beta (1 ng/ml), tumor necrosis factor alpha (TNFalpha; 10 ng/ml), or IL-17 (10 ng/ml) in the presence of either Tau or Tau-Cl, which were added at concentrations of 50-500 microM. Tau and Tau-Cl were added simultaneously with, 2 hours before, or 24 hours after the stimuli. The concentrations of IL-6 and IL-8 were determined in culture supernatants using specific enzyme-linked immunosorbent assays. Proliferation of FLS was estimated on the basis of 3H-thymidine incorporation into the cells, which were cultured for 72 hours in the presence of recombinant human basic fibroblast growth factor (bFGF) (1 ng/ml) and Tau or Tau-Cl, which were added simultaneously at the beginning of the culture.

RESULTS

Cultured in vitro, RA FLS spontaneously secreted low levels of IL-6 and IL-8, but when RA FLS were stimulated with IL-1beta, TNFalpha, or IL-17, significantly higher amounts of IL-6 and IL-8 were produced. Tau-Cl, but not Tau, inhibited cytokine-triggered synthesis of IL-6 (50% inhibitory concentration [IC50] approximately 225 microM) and IL-8 (IC50 approximately 450 microM) when added simultaneously with the stimuli. However, IL-17-induced production of IL-8 was not affected by Tau-Cl. In the cells prestimulated with IL-1beta for 24 hours, Tau-Cl still inhibited synthesis of IL-6, but did not affect IL-8 production. Moreover, Tau-Cl inhibited spontaneous and bFGF-triggered proliferation of FLS in a dose-dependent manner. Neither Tau nor Tau-Cl affected cell viability.

CONCLUSION

The results of these studies demonstrate that Tau-Cl inhibits production of proinflammatory cytokines by RA FLS, as well as proliferation of these cells. Thus, Tau-Cl may act as a physiologic modulator of FLS functions related to their pathogenic role in RA.

Differential cytokine mRNA expression in human labial minor salivary glands in primary Sjögren's syndrome

Cytokines are known to be involved in a number of autoimmune conditions and are increasingly viewed as key components in numerous aspects of normal and abnormal cell functions. The purpose of the present study was to investigate possible immunopathogenic mechanisms within the labial minor salivary glands of patients with primary Sjögren's syndrome (pSS) by examining differential cytokine gene expression in individual cell populations (acini, ducts, or lymphoid cells). A cell-specific microdissection technique in combination with reverse transcription-polymerase chain reaction (RT-PCR) and Southern hybridization using 32P-labeled cytokine gene-specific probes was utilized to measure cytokine messenger RNA expression in individual cell populations of patients and healthy controls. mRNAs for interleukin 2 (IL-2), interleukin 6 (IL-6), interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma) and transforming growth factor beta 1 (TGF-beta1) were detected in the epithelial cells (acini and ducts) and lymphoid cells of the labial minor salivary glands of pSS patients. The expression levels of these mRNAs in the epithelial cells were either up- or down-regulated by adjacent focal infiltrating lymphoid cells. mRNAs for all of the above cytokines, with the exception of IFN-gamma, were detected in salivary tissues of healthy volunteers. The epithelial cells in the salivary glands are active participants in the autoimmune-mediated process of pSS, as evidenced by their ability to express a high frequency and wide variety of cytokines. The presence of an infiltrating lymphoid focus within the gland appeared to modulate cytokine gene expression by the salivary epithelial cells.

Treatment of rheumatoid synovitis with anti-reshaping human interleukin-6 receptor monoclonal antibody: use of rheumatoid arthritis tissue implants in the SCID mouse model

OBJECTIVE

To examine the effect of anti-reshaping human interleukin-6 receptor monoclonal antibody (anti-rsHuIL-6R mAb) on patients with rheumatoid arthritis (RA), using SCID mice in which human RA synovial tissue has been grafted (SCID-HuRAg).

METHODS

Tissue from human RA pannus was implanted subcutaneously in the backs of 69 SCID mice. Differences from human RA were examined pathologically. Anti-rsHuIL-6R mAb (100 microg) was administered intraperitoneally to mice once a week for 4 weeks. The implanted tissue was removed from the SCID-HuRAg mice on the fifth week after the initial treatment and examined pathologically. A group of SCID-HuRAg mice treated with control mAb, an auranofin-treated group, and an untreated group were used as controls. A total of 32 mice (8 in each group) were studied.

RESULTS

Histologic characteristics of the implanted tissues in SCID-HuRAg mice were very similar to those of human RA even 2 months after implantation. In addition, the presence of CD4-, CD8-, CD20-, IL-6-, tumor necrosis factor alpha-, tartrate-resistant acid phosphatase (TRAP)-, matrix metalloproteinase 1 (MMP-1)-, and MMP-9-positive cells was confirmed by immunohistochemical staining. A significant decrease in the number of inflammatory cells, MMP-positive cells, and TRAP-positive cells was observed in the anti-rsHuIL-6R mAb treatment group as compared with the control groups.

CONCLUSION

The SCID-HuRAg mouse is a useful model for evaluating the effectiveness of antirheumatic drugs. Anti-rsHuIL-6R mAb may have an antiinflammatory effect on RA synovitis and an inhibitory effect on osteoclasts.

Pharmacological effects of SA96 (bucillamine) and its metabolites as immunomodulating drugs--the disulfide structure of SA-96 metabolites plays a critical role in the pharmacological action of the drug

SA96 (generic name, bucillamine) is a disease-modifying anti-rheumatoid arthritis (RA) drug with immunological effects. This compounds has two sulfhydryl groups in its molecule, and the differences and similarities between this drug and D-penicillamine, which is also a sulfhydryl group-containing anti-rheumatic drug, have frequently been discussed. To clarify the pharmacological differences between these two drugs, we examined the concentrations of the compounds and its metabolites in serum and synovial fluid, paying special attention to the metabolites of SA96 produced in vivo. SA96 was metabolized in a very short time to SA981 which is a disulfide compound formed by intramolecular binding of two sulfhydryl groups, and transferred to synovial fluid. In addition SA981 had significant suppressive effects on IL-6 and IL-8 production by synovial cells in vitro. These results demonstrate that SA96, which has two sulfhydryl groups, exhibits anti-rheumatic effects via a pharmacological action clearly different from that of D-penicillamine.

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.

The role of tumor necrosis factor-alpha in the pathogenesis of anorexia and bulimia nervosa, cancer cachexia and obesity

In this paper a new immunological model of anorexia and bulimia nervosa will be presented in which the inflammatory cytokines are conceived as the fundamental regulators of body metabolism. This conception differs from the conventional view in which the inflammatory cytokines are perceived primarily as peptide molecules utilized by the immune system to control infection, inflammation and tissue or neuronal damage. Given that the inflammatory cytokines are also fundamental regulators of body metabolism, when they become dysregulated they create physiological chaos which results in the development of a number of autoimmune, metabolic and psychiatric disorders. In this proposed immunological model of anorexia and bulimia nervosa, elevated tumor necrosis factor-alpha features as the primary cause of these conditions. Pathophysiological parallels are drawn between anorexia nervosa and cancer cachexia in terms of the causal role the cytokines, neuropeptides and neurotransmitters play in the manifestation of shared symptoms. These shared symptoms include elevated tumour necrosis factor-alpha, down-regulated interleukin-2 and interleukin-4 and depletion of lean body mass. Furthermore, the following neuropeptides are dysregulated in both anorexia nervosa and cancer cachexia: vasoactive intestinal peptide, cholecystokinin, corticotropin-releasing factor, neuropeptide Y, peptide YY and beta-endorphin. In addition, in anorexia and bulimia nervosa, secretion of the neurotransmitter serotonin is inhibited while norepinephrine is enhanced. It will be argued that the causal interplay between the cytokines, neuropeptides and neurotransmitters initiates a cascade of biochemical events which may result in either anorexia or bulimia nervosa, or cancer cachexia. The extent to which these inflammatory cytokines, neuropeptides and neurotransmitters are causally efficacious in the pathogenesis of other autoimmune disorders, such as diabetes mellitus and rheumatoid arthritis, will also be addressed.

Interleukin-4 inhibits prostaglandin E2 production by freshly prepared adherent rheumatoid synovial cells via inhibition of biosynthesis and gene expression of cyclo-oxygenase II but not of cyclo-oxygenase I

OBJECTIVE

To characterise the effect of interleukin-4 (IL-4) on the biosynthesis of cyclo-oxygenases I (COX I) and II (COX II), the rate limiting enzymes of the synthesis of prostaglandin E2 (PGE2), in freshly prepared rheumatoid synovial cells.

METHODS

Adherent synovial cells were obtained from rheumatoid synovium by collagenase digestion. The concentrations of PGE2 in culture supernatants were determined by enzyme linked immunosorbent assay. The protein and mRNA concentrations of COX I and COX II were determined by Western blotting and reverse transcription polymerase chain reaction, respectively.

RESULTS

Freshly prepared synovial cells produced large amounts of PGE2. They also showed increased gene expression of COX I and COX II, and synthesised these proteins. IL-4 had suppressive effects on the production of PGE2 by untreated or lipopolysaccharide (LPS) stimulated synovial cells. In addition, IL-4 inhibited the biosynthesis of COX II at the mRNA level. In contrast, it did not modify the protein concentration of COX I. In tests of cell specificity, IL-4 did not reduce the mRNA concentration of COX II in interleukin-1 alpha (IL-1 alpha) stimulated cultured synovial fibroblasts at passages 3-6, but it reduced considerably the mRNA concentrations of COX II in an LPS or IL-1 alpha stimulated U937 monocyte/macrophage cell line.

CONCLUSIONS

These results suggest that IL-4 might inhibit overproduction of PGE2 in rheumatoid synovia via selective inhibition of the biosynthesis of COX II, and that this inhibition might be specific to macrophage-like synovial cells.

Cytokines affecting megakaryocytopoiesis in rheumatoid arthritis with thrombocytosis

Particular interleukins, namely interleukin (IL)-6, IL-4 and IL-1, with pro-inflammatory mediator activities have also been shown to be involved in the regulation of megakaryocytopoiesis. As rheumatoid arthritis (RA) is not uncommonly associated with reactive thrombocytosis, we investigated serum IL-1 alpha, IL-1 beta, IL-4 and IL-6 concentrations in RA patients with marked thrombocytosis, and compared them to the levels in RA patients with normal platelet counts and healthy volunteers. IL-1 beta. IL-4 and IL-6 concentrations were found to be correlated with the disease activity in both groups of RA patients, with higher serum levels of each cytokine in the thrombocythaemic group. Significant positive correlations of IL-1 beta and IL-4 with the platelet counts were documented only in patients with thrombocytosis. According to our results. IL-6 and IL-1 beta were found to be good indicators of disease activity in RA, while IL-1 beta and IL-4 seemed to be related more with the process of reactive thrombocytosis secondary to rheumatoid inflammation.

Immunotherapy of autoimmune disease

T-cell recognition of autoantigens stands as the primary target for immune intervention in autoimmune disease. Experiments in animal models, in combination with a number of clinical trials completed in the last year, have helped to clarify the pathogenesis of various autoimmune diseases and indicate future strategies for immunotherapy.