Proinflammatory Cytokines IL-1alpha Research Articles

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

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. 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. 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. 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.

The role of prostaglandins in blastocyst implantation.

This review summarizes the information available on the involvement of prostaglandins in blastocyst implantation, and examines their interactions with three other inflammatory mediators, platelet-activating factor (PAF), interleukin (IL-1) and corticotrophin-releasing factor (CRF). Essential elements of this information, consistent with the assumption that prostaglandins play an important role in implantation, appear to be: (i) the burst of endometrial prostaglandin production, following the blastocyst signal(s) or an artificial stimulus; (ii) the main localization of this production at the luminal epithelium and release towards the stroma; and (iii) the presence at the stromal level of specific progesterone-dependent binding sites for prostaglandin E2. In addition, accumulated data indicate a paracrine interaction at the endometrial level between PAF and prostaglandin E2, which could serve, among others, to amplify the embryonic signal(s). Pro-inflammatory cytokines IL-1 alpha and IL-1 beta may also play a significant role in endometrial response via the modulation of prostaglandin E2 production. Prostaglandins and IL-1 induce the expression of CRF, which acts as an autocrine/paracrine inflammatory regulator. CRF exhibits a strong vasoactivity in skin tests, inducing a local increase of capillary permeability at a concentrations of 10(-10) M. Levels of CRF and its mRNA were found to be higher in rat implantation sites compared with those in the interimplantation regions. Stromal cells were found to be positive for immunoreactive CRF at the implantation sites only. It is suggested that CRF may be involved in the local increase of capillary permeability seen in implantation sites, and that its production by stromal cells may be the consequence of a paracrine action of epithelial prostaglandin, released under the effect of PAF and IL-1, derived from or produced by blastocysts in endometrial cells.

Induction of circulating interleukin 10 by interleukin 1 and interleukin 2, but not interleukin 6 immunotherapy

The objective of this study was to investigate the in vivo production of interleukin 10 (IL-10) in cancer patients undergoing immunotherapy with IL-1 alpha, IL-2 or IL-6 and to study the effect of the same cytokines on the in vitro synthesis of IL-10 by human monocytes and macrophages. In the IL-1 alpha clinical trial, patients received 0.03 g/kg of IL-1 alpha as a 30 minute infusion daily for 5 consecutive days. In these patients, plasma IL-10 levels rose rapidly and peaked within 1 h (121 +/- 16 pg/mL; n = 4) after the first IL-1 alpha infusion. Thereafter, the levels rapidly declined to baseline within 8 h. The peak plasma IL-10 levels measured on days 3 and 5 of therapy were somewhat less pronounced than those on day 1. IL-2 immunotherapy was also associated with the induction of circulating IL-10. These patients were treated with high-dose (6 x 10(5) IU/kg) IL-2 every 8 h for 5 consecutive days. IL-10 was detectable in these patients within 2-4 h after the first IL-2 infusion (105 +/- 12 pg/mL). In contrast to the transient bursts of IL-10 detected in patients treated with IL-1 alpha, IL-10 levels progressively increased throughout the treatment course in the IL-2-treated patients reaching peak levels on day 5 (240 +/- 22 pg/mL; n = 10). IL-6 immunotherapy with a 5-day continuous infusion was not associated with detectable levels of circulating IL-10. Peripheral blood mononuclear cells and in vitro-derived macrophages synthesized similar amounts of IL-10 after stimulation with IL-1 alpha or IL-2, but were unresponsive to IL-6. These results suggest that the proinflammatory cytokines IL-1 alpha and IL-2 induce the anti-inflammatory cytokine IL-10 in vitro and in vivo, whereas Il-6 is not able to stimulate IL-10 synthesis.

Effects of proinflammatory cytokines on cultivated primary human hepatocytes. Fluorometric measurement of intercellular adhesion molecule-1 and human leukocyte antigen-A, -B, -C, and -DR expression.

Expression of adhesion molecules and human leukocyte antigens on the surface of hepatocytes (HC) may play an important role in the immune reaction in different types of infectious and noninfectious hepatitis, liver graft rejection, and autoimmune liver diseases. The aim of this study was to evaluate the influence of the proinflammatory cytokines IFN-alpha, IFN-gamma, and IL-1 alpha on the expression of intercellular adhesion molecule-1 (ICAM-1) and HLA-A, -B, -C, and -DR on highly purified primary human HC in cell culture. Expression was assessed by semiquantitative measurement of HC in cell culture by means of computer-aided fluorometry after immunofluorescent labeling. Avidin-biotin-immunoperoxidase staining was applied on parallel cultures to evaluate cell purity (> 99%) and to confirm the results obtained by fluorometry. ICAM-1 was expressed constitutively on untreated HC in vitro. Stimulation of HC with IFN-gamma and IL-1 alpha for 24 hr resulted in an increase of ICAM-1 expression. Cultured HC were moderately HLA-A, -B, and -C positive, but HLA-DR negative. Stimulation of HC with 500 U/ml IFN-gamma for 72 hr resulted in an increase of HLA-A, -B, -C, and -DR expression, whereas stimulation with 10 U/ml IL-1 alpha for 72 hr had no influence. By using 5000 U/ml IFN-alpha for 72 hr, we achieved an increase of HLA-A, -B, and -C expression; effects on the other tested antigens were not significant. In contrast to endothelial cells and transformed human hepatocytic cell lines, ICAM-1 on HC was changed more intensively by IFN-gamma than by IL-1 alpha. Furthermore, the results reveal differences in HLA and ICAM-1 expression between HC in vivo and in vitro.

Cytokine-induced interleukin-1 receptor antagonist release in mononuclear phagocytes.

IL-1ra has recently been shown to suppress both cytokine- and endotoxin-induced IL-1 beta and TNF-alpha release from monocytes. Given that mononuclear phagocytes can produce both the proinflammatory cytokines IL-1 alpha, IL-1 beta, and TNF-alpha as well as the suppressive cytokine IL-1ra, we proposed that IL-1 alpha, IL-1 beta, and TNF-alpha may induce IL-1ra from mononuclear phagocytes. To test this hypothesis, human mononuclear cells were stimulated for 18 h with IL-1 alpha, IL-1 beta, or TNF-alpha, and the supernatants assayed for IL-1ra by ELISA. Each cytokine induced IL-1ra secretion in a dose-response manner. However, IL-1 alpha and IL-1 beta were better inducers of IL-1ra than was TNF-alpha. IL-1 alpha or IL-1 beta at a dose of 10 ng/ml induced 3 to 6 ng/ml of IL-1ra, while TNF-alpha at a dose of 100 ng/ml stimulated only 1.4 ng/ml of IL-1ra. This induction was not due to endotoxin, as all cytokines contained less than 10 pg/ml of contaminating LPS. Furthermore, for IL-1 beta-induced IL-1ra, immunoprecipitation of IL-1 beta with an anti-IL-1 beta antibody, but not a preimmune antibody, blocked the induction of IL-1ra. In contrast to mononuclear phagocytes, IL-1 alpha, IL-1 beta, and TNF-alpha did not induce further IL-1ra production in alveolar macrophages. This lack of macrophage responsiveness may relate to the constitutive production of IL-1ra by these mature mononuclear phagocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of transforming growth factor-beta on murine astrocyte glutamine synthetase activity. Implications in neuronal injury.

Cytokines have been implicated in the pathogenesis of a number of brain diseases in which neurological dysfunction has been attributed to a change in amino acid neurotransmitter metabolism. In the present in vitro study, we investigated the effects of cytokines on astrocyte glutamine synthetase (GS) activity and subsequently on N-methyl-D-aspartate (NMDA) receptor-mediated neurotoxicity. Proinflammatory cytokines IL-1 alpha, IL-1 beta, and IL-6 at a concentration of 20 ng/ml did not affect GS activity; however, tumor necrosis factor-alpha inhibited this activity by 20% in mixed neuronal/astrocyte cultures. Treatment for 24 h with transforming growth factor (TGF)-beta 1 or -beta 2 inhibited up to 60% GS activity. TGF-beta 2 also inhibited GS in enriched astrocyte cultures with an ED50 of 10 pg/ml. Antibodies specific to TGF-beta 2 blocked this effect. Treatment of astrocytes with TGF-beta 2 (250 pg/ml) resulted in markedly dilated rough endoplasmic reticulum. Since astrocyte GS may play a protective role in NMDA receptor-mediated neurotoxicity, we treated mixed neuronal/astrocyte cultures with TGF-beta 2 (250 pg/ml) and found a threefold potentiation of NMDA receptor-mediated neurotoxicity. These data suggest that TGF-beta impairs astrocyte GS function and enhances neurotoxicity, thus providing insight into understanding one mechanism of cytokine-mediated central nervous system disease.