Cytokine regulation of IL-1 beta gene expression in the human polymorphonuclear leukocyte

Although recently polymorphonuclear leukocytes (PMN) have been identified as producers of IL-1 beta in response to LPS and granulocyte/monocyte colony stimulating factor, little is known regarding the ability of other cytokines to induce the production of IL-1 beta in the PMN. Inasmuch as IL-1 and TNF have been shown to be important priming agents, as well as agents that induce migration of PMN, we investigated their effect on IL-1 beta gene expression in human peripheral blood PMN. In the present study, we demonstrate that human peripheral blood PMN produce IL-1 beta in response to IL-1 alpha, IL-1 beta, and TNF-alpha. Control (unstimulated) human PMN had virtually undetectable levels of IL-1 beta mRNA. Either IL-1 beta or TNF, induced PMN to transiently express IL-1 beta mRNA with peak expression at 1 h, returning to untreated levels by 2 h. A dose response indicated that as little as 0.05 ng/ml of IL-1 beta or TNF resulted in IL-1 beta induction, with maximal effects at 1 ng/ml of IL-1 beta and 5 ng/ml of TNF. IL-1 alpha or IL-1 beta exhibited similar dose responses in IL-1 beta mRNA induction. Inasmuch as cytokines have been shown to have synergistic effects in cell function studies, we induced PMN with a combination of maximally effective doses of TNF plus IL-1 beta. They demonstrated a cooperative effect on IL-1 beta gene expression, in that mRNA levels were sustained for three hours. IL-1 beta Ag expression, as measured by ELISA, paralleled IL-1 beta mRNA expression with cell associated peak levels at 2 to 4 h. IL-1 beta Ag levels in PMN lysates and supernatants correlated with IL-1 beta mRNA levels, i.e., TNF + IL-1 greater than TNF greater than IL-1. Thus, these studies represent the first demonstration of IL-1 and TNF induction of IL-1 beta gene expression in the PMN. Furthermore, the time course of induction is unique to the PMN, with peak induction of mRNA at 1 h, which is consistent with the short lived nature of these cells in inflammatory lesions.     

Increased tumor necrosis factor and IL-1 beta gene expression in the kidneys of mice with lupus nephritis

Because TNF and IL-1 can initiate immunologic and inflammatory events alone or synergistically, a local increase in the levels of one or both of these cytokines in vivo may cause irreparable tissue damage. The purpose of this study was to evaluate local TNF and IL-1 beta gene expression in vivo in the kidneys of MRL-Ipr mice with autoimmune lupus nephritis. TNF mRNA was detected in the renal cortex of MRL-Ipr mice but was not present in the cortex of normal congenic MRL-++ or C3H/FeJ mice. MRL-Ipr mice with lupus nephritis expressed higher amounts of TNF mRNA compared with MRL-Ipr mice prior to disease. In addition, freshly isolated, unstimulated glomeruli from MRL-Ipr mice with nephritis were found to secrete detectable levels of TNF, whereas glomeruli from MRL-++ mice did not. IL-1 beta mRNA, present in the renal cortex of C3H/FeJ, MRL-++, and young MRL-Ipr mice with normal kidneys, was also more abundantly expressed in MRL-Ipr mice with nephritis. Cultured macrophages from glomeruli of mice with nephritis were found to express TNF and IL-1 beta mRNA and product. These macrophages are prominent only in MRL-Ipr mice with renal disease and are the likely source of increased gene expression for both cytokines.     

Modulation of IL-1 inflammatory and immunomodulatory properties by IL-6.

Among the major cytokines present in inflammatory lesions interleukin-1 (IL-1), tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) share many biological activities. Since IL-1 alpha, IL-1 beta and TNF alpha have been previously demonstrated to play an important role in connective tissue destruction by stimulating the production of prostaglandin E2 (PGE2) and collagenase, these functions were investigated in the presence or absence of natural human IL-6 (nhIL-6) or recombinant human IL-6 (rhIL-6). IL-6 was found 1 degree to stimulate immunoglobulin A production by the CESS B cell line up to 19 fold without being affected by the presence of IL-1 beta and 2 degrees to stimulate murine thymocytes proliferation up to 2-4 fold, with an increase up to 60-fold in costimulation with either IL-1 alpha or beta. IL-6 alone, even at very high concentrations (up to 200 U/ml and 50 ng/ml), did not induce PGE2 production by fibroblasts and synovial cells. However, IL-1 alpha or beta induced PGE2 production by human dermal fibroblasts and by human synovial cells was inhibited (in 5/8 experiments) up to 62% by addition of IL-6. On the contrary in 2/4 experiments TNF alpha-induced PGE2 production was increased (approximately 2 fold) by the addition of IL-6. IL-1 and TNF alpha-induced collagenase production in synovial cells remained unchanged in the presence of IL-6.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bruton's tyrosine kinase is required for TLR2 and TLR4-induced TNF, but not IL-6, production

Bruton's tyrosine kinase (Btk), the gene mutated in the human immunodeficiency X-linked agammaglobulinemia, is activated by LPS and is required for LPS-induced TNF production. In this study, we have investigated the role of Btk both in signaling via another TLR (TLR2) and in the production of other proinflammatory cytokines such as IL-1beta, IL-6, and IL-8. Our data show that in X-linked agammaglobulinemia PBMCs, stimulation with TLR4 (LPS) or TLR2 (N-palmitoyl-S-[2, 3-bis(palmitoyloxy)-(2R)-propyl]-(R)-cysteine) ligands produces significantly less TNF and IL-1beta than in normal controls. In contrast, a lack of Btk has no impact on the production of IL-6, IL-8, or the anti-inflammatory cytokine, IL-10. Our previous data suggested that Btk lies within a p38-dependent pathway that stabilizes TNF mRNA. Accordingly, TaqMan quantitative PCR analysis of actinomycin D time courses presented in this work shows that overexpression of Btk is able to stabilize TNF, but not IL-6 mRNA. Furthermore, using the p38 inhibitor SB203580, we show that the TLR4-induced production of TNF, but not IL-6, requires the activity of p38 MAPK. These data provide evidence for a common requirement for Btk in TLR2- and TLR4-mediated induction of two important proinflammatory cytokines, TNF and IL-1beta, and reveal important differences in the TLR-mediated signals required for the production of IL-6, IL-8, and IL-10.     

Cytokine (tumor necrosis factor, IL-6, and IL-8) production by respiratory syncytial virus-infected human alveolar macrophages.

Human alveolar macrophages (AM) are susceptible to infection with respiratory syncytial virus (RSV), but the infection is abortive after the initial cycles of virus replication. We have investigated if RSV infection of AM results in the production of cytokines TNF, IL-6, and IL-8, all of which may modulate inflammatory and immune responses to the virus, as well as may directly protect respiratory epithelial cells against spread of infection. Within 1 h after interaction with RSV, increased mRNA levels were found for all three cytokines. Peak expression of the mRNAs occurred at 3 to 6 h. The virus most effectively induced TNF mRNA expression greater than IL-6 mRNA greater than IL-8 mRNA, as compared to cytokine mRNA expression induced by bacterial endotoxin. Inactivated virus was almost as effective as live virus in inducing and maintaining increased IL-6 and IL-8 mRNA over 16 h, whereas live infectious RSV was necessary for maintaining TNF mRNA expression over the same time. Protein concentrations of the different cytokines in the supernatants of infected AM reflected the increased levels of mRNA in the cells. Despite the high levels of cytokines with possible antiviral activity (TNF and IL-6) in the AM supernatants, neither supernatants nor rTNF when added to bronchial epithelial cells protected them from infection with RSV. However, TNF, IL-1, and RSV, but not IL-6, induced IL-8 and IL-6 mRNA expression by the bronchial epithelial cells suggesting that cytokines produced by RSV-infected AM may be more important in modulating the inflammatory response in infection than directly interfering with virus infection/replication of airway epithelium.     

Effects of kainic acid on messenger RNA levels of IL-1 beta, IL-6, TNF alpha and LIF in the rat brain.

We examined the kainic acid-induced changes of mRNA levels of several cytokines such as IL-1 beta, IL-6, TNF alpha and LIF in the rat brain regions using semiquantitative RT-PCR method. IL-1 beta mRNA was markedly increased in the cerebral cortex (CC), thalamus (THL) and hypothalamus (HT) 2 h after the injection of kainic acid in a convulsive dose (12 mg/kg i.p.), and tended to decrease 4 h after the injection. IL-6 mRNA was weakly induced in the hippocampus (HPP) 2 h after the injection of kainic acid and was markedly increased in the CC, HPP, THL, and HT at 4 h. The level of TNF alpha mRNA was highly elevated in the CC, HPP, striatum (STR), THL and HT at 2 and 4 h after the injection. LIF mRNA apparently expressed in the CC and HPP of control rats and was increased in the CC, HPP and HT by the treatment with kainic acid. These results indicate that mRNAs of several cytokines are increased in various brain regions with different time-courses by kainic acid.     

Interleukin-6 induces the synthesis of tissue inhibitor of metalloproteinases-1/erythroid potentiating activity (TIMP-1/EPA).

This study examines the role of interleukin-6 (IL-6) in connective tissue metabolism. Effects of different preparations of IL-6 on production of collagenase and tissue inhibitor of metalloproteinases-1/erythroid potentiating activity production are studied in human fibroblasts, synoviocytes, and articular chondrocytes. In contrast to interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF alpha), IL-6 does not stimulate the production of collagenase, nor does it modulate the stimulatory effects of IL-1 beta and TNF alpha on the production of this proteinase. Furthermore, IL-6 has no detectable effect on prostaglandin E2 production, an additional proinflammatory response induced by IL-1 beta and TNF alpha. IL-6, however, is identified as a potent inducer of de novo synthesis of tissue inhibitor of metalloproteinases-1/erythroid potentiating activity in all types of connective tissue cells examined. These results define new biological activities of IL-6 and provide further insight into the regulation of connective tissues by cytokines.     

In vitro production of cytokines is influenced by sulfatide and its precursor galactosylceramide.

Effects of sulfatide and its precursor galactosylceramide (gal-cer) on the kinetics of production of cytokines were studied. In human mononuclear leucocytes, gal-cer but not sulfatide induced significantly increased amounts of interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF) mRNA. In phytohemagglutinin-stimulated cultures, gal-cer increased the levels of IL-1beta and IL-6 mRNA and secreted IL-1beta and IL-6, while sulfatide decreased the amounts of IL-6 mRNA and secreted IL-6. Gal-cer also increased TNF secretion. In lipopolysaccharide-stimulated cells, sulfatide but not gal-cer decreased the secretion of IL-1beta and IL-10, a potent suppressor of production of many cytokines. Thus, sulfatide and gal-cer affect cytokine production differently, most likely at the level of gene expression. This may have implications in diseases where inflammatory cytokines play a pathogenic role.     

Enhancement of IL-6 receptor beta chain (gp130) expression by IL-6, IL-1 and TNF in human epithelial cells.

Analysis of the IL-6 Receptor beta chain (gp130) mRNA expression on the two human epithelial cell lines UAC and Hep3B reveals that it is enhanced by IL-6, IL-1 and TNF treatment. In the case of UAC cells, TNF action might be mediated by IL-6. For Hep3B cells, TNF seems to exert a direct effect on gp130, as no IL-6 expression is detected after stimulation by this cytokine. On the same cells, increase of the binding of an anti-gp130 monoclonal antibody was observed after treatment by TNF, which denotes the effective appearance of new gp130 molecules on the cell surface. All this cytokines seem to act selectively on the beta chain of the IL-6 receptor. This probably reflects the importance for some cells to have gp130 represented on their membrane in inflammatory contexts.     

Differential responses of hematopoietic and non-hematopoietic cells to anti-inflammatory cytokines: IL-4, IL-13 and IL-10.

Recombinant preparations of human anti-inflammatory cytokines: IL-4, IL-13 and IL-10, inhibited LPS-induced synthesis of TNFalpha and IL-6 in the whole human blood tested in vitro. These cytokines also inhibited LPS-induced IL-6 and TNF mRNA accumulation in isolated human blood monocytes/macrophages. On the other hand, similar concentrations of IL-4 and IL-13 (but not IL-10) enhanced synthesis of IL-6 in cultured human umbilical vein endothelial cells (HUVEC). In human hepatoma HepG2 cells IL-4 and IL-13 (but not IL-10) inhibited IL-6-induced synthesis of haptoglobin. These differential responses to the tested anti-inflammatory cytokines were observed at mRNA and protein levels and may reflect cell specificities in signalling pathways and gene expression. When HUVEC and HepG2 cells were cultured together and stimulated with LPS the addition of IL-4 or IL-13 resulted in the reduction of LPS-induced and IL-6-mediated haptoglobin synthesis. Thus in co-culture the inhibitory effects of IL-4 or IL-13 on HepG2 cells prevail over stimulation of IL-6 synthesis in HUVEC.