Regulation of interleukin-1 synthesis by histamine produced by mouse peritoneal macrophages per se.

The response of mouse peritoneal macrophages to Escherichia coli lipopolysaccharide (LPS) resulted in induction of histidine decarboxylase (HDC) and, consequently, of histamine production. Concanavalin A had no effect on the reactions. Alpha-fluoromethylhistidine, a suicide inhibitor of HDC, attenuated, in a dose-dependent manner, both spontaneous and LPS-stimulated IL-1 synthesis by macrophages. IL-1 production was significantly blocked by either an H1 anti-histamine, diphenhydramine, or H2 anti-histamine ranitidine, in the absence of any exogenous histamine. Addition of exogenous histamine accentuated the IL-1 production by macrophages as a function of its dose. These results suggest that IL-1 production by mouse peritoneal macrophages is regulated by histamine synthesized in the system per se and that the effect of histamine is dependent on both H1 and H2 histamine receptors located on the surface of the cells.     

Metallothionein induction in cultured rat hepatocytes by arthritic rat serum,activated macrophages,interleukin-6, interleukin-11 and leukaemia inhibitory factor

Potential mediators of hepatic metallothionein (MT) synthesis in adjuvant-induced arthritis were investigated in cultured rat hepatocytes. Sera from arthritic rats (14 d post-adjuvant treatment) in the presence of Zn (50 µmol/L) + dexamethasone (Dex; 1 µmol/L) increased metallothionein (MT) accumulation by 34% above that obtained with control rat serum with Zn + Dex. Endogenous IL-6 activity in serum from arthritic rats was 93 ± 49 U/mL and was undetectable in control rat serum. The activities of TNF, IL-1 and corticosterone concentrations were the same in control and arthritic rats. The accumulation of MT in hepatocytes in the presence of Zn (10 µmol/L) + Dex (1 µmol/L) was enhanced 29% and 49% by media from lipopolysaccharide (LPS)-stimulated peritoneal macrophage (PMM) and Kupffer cell cultures (KCM), respectively. The response with PMM and KCM was quantitatively the same as that with interleukin-6 (IL-6). Analysis of PMM and KCM showed activities of 1,000–10,000 U/mL for IL-6, 100–1000 U/mL for TNF and <10,000 U/mL for IL-1, the latter detected only in PMM. LPS alone enhanced the accumulation of MT above Zn + Dex in a dose dependent manner. A significant LPS response was obtained at 5 mg/L with a maximal stimulation above Zn + Dex of 38% at 10 mg/L. This direct stimulation of MT by LPS was not part of the response observed with PMM and KCM where the final LPS concentration in culture was only 0.1 mg/L. Other cytokines capable of synergy with Zn + Dex on MT synthesis were investigated. Interleukin-11 (IL-11) increased the Zn + Dex induction in a dose dependent manner with maximal stimulation at 100 U/mL of 40%. A small stimulation of 12% above Zn + Dex was obtained with leukaemia inhibitory factor (LIF) at concentrations greater than 100 U/mL. No enhancement of the Zn + Dex response was obtained with interleukin-3 (1000 U/mL), interleukin-4 (10 µg/L), platelet activating factor (5 nmol/L) or granulocyte-colony stimulating factor (5 µg/L). Neither IL-11 nor LIF enhanced the response obtained with Zn + Dex + IL-6. The results demonstrate that mediators present in arthritic rat serum and in LPS-stimulated PMM and KCM cause a quantitatively similar response on MT accumulation as IL-6. IL-11 and to a lesser extent LIF, are also potential mediators of MT synthesis in inflammation.Abbreviations AJ adjuvant - Dex dexamethasone - IL-1 interleukin-1 - IL-3 interleukin-3 - IL-4 interleukin-4 - IL-6 interleukin-6 - IL-11 interleukin-11 - IFN interferon- - KCM kupffer cell media - LIF leukaemia inhibitory factor - G-CSF granulocyte-colony stimulating factor - LPS lipopolysaccharide - MT metallothionein - PAF platelet activating factor - PMM peritoneal macrophage media - TNF- tumour necrocis factor-     

Purified interleukin-1 (IL-1) from human monocytes stimulates acute-phase protein synthesis by rodent hepatocytes in vitro.

A universal component of inflammation is the increased synthesis of a series of plasma proteins (acute-phase proteins) by the liver. The postulated messenger of acute-phase protein induction is released by leucocytes at the site of inflammation and has been shown to co-purify with endogenous pyrogen or lymphocyte-activating factor. Interleukin-1, molecular weight 17,000, pI 6 X 8-7 X 2, was purified to homogeneity from adherent human blood monocytes by a combination of affinity chromatography, gel filtration and isoelectric focusing. We examined the direct effect of pure IL-1 on the induction of acute-phase protein synthesis in vitro using rat and mouse hepatocytes. IL-1 caused significant increased synthesis of alpha 1-acid glycoprotein and smaller increases in the synthesis of other acute-phase proteins, and significant decreased synthesis of albumin. The pattern of induction of acute-phase proteins differs from that seen with a separate 30,000 molecular weight hepatocyte-stimulating factor from human monocytes described previously. We conclude that human IL-1 is one of the mediators responsible for the acute-phase protein response of the liver in inflammation and can directly cause stimulation of specific gene expression in normal hepatocytes.     

Synergistic induction of metallothionein synthesis by interleukin-6, dexamethasone and zinc in the rat

We investigated the reciprocal effects of interleukin-6 (IL-6), glucocorticoid and zinc (Zn) on metallothionein (MT) synthesis in rats. MT synthesis in the liver, which is a key responsible organ in acute phase responses, was induced by IL-6 or dexamethasone (Dex), and in an additive manner by a combination of IL-6 and Dex 18 h after injection. MT synthesis in the lung and heart was evaluated by immunoassay using a specific antibody to MT-I, because of its low concentration in these tissues. Heart concentrations of MT-I were significantly increased by IL-6, and were further increased by the combination of IL-6 and Dex, although Dex by itself had no effect. This suggests a synergistic effect of IL-6 and Dex on MT-I synthesis in the heart. A similar synergism was observed in the lung. To study the effect of Zn on the induction of MT and acute phase proteins, Zn, IL-6 and Dex were administered in various concentrations. The increase in liver MT induced by the combination of IL-6 and Dex with Zn (130 μg MT/g of liver) was greater than the sum of the increases induced by (IL-6 + Zn) and by (Dex + Zn) (103 μg MT/g), suggesting a synergistic increase. The data indicate that the maximal increase in the induction of MT by a combination of IL-6 and Dex depends on an adequate liver Zn content. Thus, the in vivo synergistic induction of acute phase proteins by IL-6, glucocorticoid and Zn may be required for the maximal and rapid response, not only in liver but also in other tissues including heart and lung. This suggests that the synergistic reaction may be important for an enhancement of the radical scavenging ability of tissues in acute phase responses.     

Interleukin-1 and interleukin-6 stimulate acute-phase protein production in primary mouse hepatocytes

Primary mouse hepatocytes were treated with the acute-phase mediators interleukin-1, interleukin-6, and glucocorticoids, singularly and in combination, in order to delineate the spectrum of proteins induced by the stimulatory factors. As found for rat and human liver cells, mouse hepatocytes responded to the cytokines by increasing production of acute-phase proteins, which in mice include haptoglobin, alpha 1-acid glycoprotein, complement C-3, serum amyloid A, and hemopexin. Serum amyloid A was unusual in that only the acidic peptide form responded to treatment with IL-1 and IL-6; the more basic form remained unchanged. In addition, an unidentified secretory protein was induced only by mixtures containing IL-6. The present study shows that a combination of IL-1, IL-6, and glucocorticoids is required for regulation of acute-phase plasma protein production in mouse liver cells.     

Regulation of ion channels in rat hepatocytes

 Patch-clamp studies have been performed to elucidate single ion channels in rat hepatocytes. In rat hepatocytes two types of ion channel have been identified: an inwardly rectifying K⁺ channel with a mean inward conductance of 55 ± 6.5 pS (n = 20) and a mean outward conductance of 25 ± 3.2 pS (n = 20) in the inside-out configuration with 145 mmol/l KCl on either side of the patch as well as an outwardly rectifying Cl^– channel with a mean outward conductance of 30 ± 4.5 pS (n = 8) and a mean inward conductance of 10 ± 2.3 pS (n = 6) in the inside-out configuration with symmetrical 145 mmol/l KCl. The open probability of these channels is virtually insensitive to Ca²⁺ activity on the intracellular side. Accordingly, the Ca²⁺ ionophore ionomycin had no effect on cell membrane potential. Dibutyryl-cAMP (db-cAMP) hyperpolarizes the cell membrane and increases the activity of the 55-pS inwardly rectifying K⁺ channel by reducing the duration of closure between bursts. Forskolin similarly hyperpolarizes the cell membrane. The inwardly rectifying K⁺ channel is inhibited by progesterone, while the outwardly rectifying Cl^– channel is insensitive to progesterone. Received: 21 May 1997 / Received after revision: 7 August 1997 / Accepted: 19 August 1997     

Regulation of interleukin-6 and interleukin-6R alpha (gp80) expression by murine immunoglobulin-secreting B-cell hybridomas.

We have examined the contribution of endogenous interleukin-6 (IL-6) to the differentiation of murine B-cell hybridomas. AT73 was established by somatic hybridization between BALB/c mice B cells and 2.52M, a hypoxanthine-aminopterine-thymidine (HAT) medium-sensitive B-cell line mutant. It spontaneously secreted IgM, and addition of exogenous IL-6 augmented IgM secretion. Triggering of CD40 led to an augmentation of IL-6 expression and IgM secretion. Blocking the binding of IL-6 to its cellular receptor through the use of inhibitory monoclonal antibodies inhibited CD40-induced IgM secretion, suggesting a possible autocrine role of IL-6 for the differentiation of a CD40-activated B-cell hybridoma. Co-triggering with CD40 and B-cell receptor or activation through CD40 and IL-4 led to a synergistic augmentation of IL-6 expression as well as additive IgM secretion; this was followed by a marked decrease in the expression of B-cell surface markers on the cell membrane. Furthermore, under conditions where IL-6 expression was augmented, gp80 expression was down-regulated, suggesting a negative feedback mechanism in this B-cell hybridoma. These findings provide a role by which T-cell-dependent activation through CD40 regulates an IL-6 autocrine loop, controlling B-cell differentiation.     

Role of lipopolysaccharide (LPS), interleukin-1, interleukin-6, tumor necrosis factor, and dexamethasone in regulation of LPS-binding protein expression in normal hepatocytes and hepatocytes from LPS-treated rats.

Lipopolysaccharide (LPS)-binding protein (LBP) has been reported to be an acute-phase protein. LBP binds to LPS with a high affinity; LPS-LBP complexes then interact with the receptor CD14, resulting in increased expression of LPS-inducible genes. Hepatocytes represent a major source of LBP, but little is known about the regulation of rodent hepatocyte LBP synthesis. In these studies, undertaken to characterize hepatocyte LBP expression, we show that greater-than-20-fold increases in LBP mRNA levels in hepatocytes occurred following injection of LPS or turpentine in rats. In primary cultures of rat hepatocytes, the addition of interleukin-6 (IL-6) and LPS led to 4.5- and 3.2-fold stimulation in LBP mRNA levels, respectively. The induction of LBP by IL-6 or LPS was attenuated by dexamethasone. In contrast to IL-6 and LPS, in the presence of 10(-6) M dexamethasone, IL-1 and tumor necrosis factor (TNF) led to maximal LBP mRNA induction levels, 4.7- and 3.8-fold, respectively, suggesting that IL-6 and LPS stimulate LBP expression by mechanisms different from those of IL-1 and TNF. Similar induction levels of LBP mRNA were seen in rat H35 hepatoma cells for all four stimuli, and dexamethasone inhibited these responses. Dexamethasone alone increased the spontaneous induction in primary hepatocytes at early time points but suppressed induction at later time points. Furthermore, hepatocytes from rats treated with LPS in vivo exhibited a > 10-fold increase in mRNA expression in response to LPS and enhanced responses to TNF and IL-1. As with the normal hepatocytes, dexamethasone inhibited the LPS-dependent induction in the LPS-treated rat hepatocytes. These data suggest that LBP synthesis by hepatocytes is under the control of LPS, IL-1, TNF, IL-6, and glucocorticoids and that the LPS treatment primes hepatocytes for subsequent responses to LPS, TNF, and IL-1 for LBP synthesis.     

Production of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha by a rat corneal epithelial cell line

Production of interleukin (IL)-1 beta, IL-6 and tumor necrosis factor (TNF)-alpha by rat corneal epithelial cells in response to lipopolysaccharide and phorbol-12-myristate-13-acetate (PMA) was tested. Supernatants from rat corneal epithelial cells treated with lipopolysaccharide and PMA were collected after 6, 24 and 48 h and tested with enzyme-linked immunosorbent assay for IL-1 beta, IL-6 and TNF-alpha. The activity of TNF-alpha was additionally confirmed with bioassay on L929 cells. It was found that control groups did not produce significant levels of either cytokine. However, after stimulation with lipopolysaccharide, cells produced mainly IL-6, whereas after PMA they produced mainly TNF-alpha. IL-6 levels 24 and 48 h after PMA stimulation were also elevated, which could have been caused by the presence of TNF-alpha. Production of IL-1 beta in all groups was very low and remained within the test sensitivity range. These results show that the rat corneal epithelial cell line produces inflammatory cytokines in response to proinflammatory mediators. For this reason, it could be used for measuring the effects of irritants on the cornea.     

雌激素与IL-6、IL-8在卵巢癌细胞中的调节作用

目的 探讨雌激素与IL-6、IL-8在卵巢癌细胞中的交互调节作用及作用机制.方法 选择兼有雌激素受体(estrogen receptor,ER)及IL-6、IL-8受体表达的卵巢癌细胞系CAOV-3和OVCAR-3作为研究模型,分别探讨17B-雌二醇(estradiol,E2)对IL-6、IL-8及其受体表达的作用以及IL-6、IL-8对EB表达及ER转录活性的作用.结果 一方面E2不仅可经NF-κB途径促进卵巢癌细胞IL-6、IL-8分泌,而且还对二者受体的表达具有一定的调节作用.E2诱导的促IL-6、IL-8分泌作用可被其受体阻断剂他莫昔芬(tamoxifen,Txf)完全阻断.另一方面在无雌激素的条件下,IL-6、IL-8能上调卵巢癌细胞Erα表达及下调ERB表达,且还能分别通过丝裂原活化蛋白激酶(MAPK)信号通路和Src活化增强卵巢癌细胞ER的转录活性,该作用可被Txf完全封闭.结论 雌激素与IL-6、IL-8两种细胞因子在卵巢癌细胞中交互调节,由此通过产生的放大信号通路促进卵巢癌的生长和发展.     

Acute-phase protein synthesis in human hepatoma cells: differential regulation of serum amyloid A (SAA) and haptoglobin by interleukin-1 and interleukin-6.

Interleukin-6 (IL-6, BSF-2 or IFN-beta 2) is thought to be the major regulator of the acute-phase protein response that follows tissue injury and inflammation, with interleukin-1 (IL-1), tumour necrosis factor and more recently, LIF or HSF III, slightly stimulatory on only certain acute phase proteins. The synthesis of the major acute-phase protein SAA, originally described as being synthesized in response to IL-1, has been claimed recently to be mainly under IL-6 regulation. Our results show that in the human hepatoma cell line HuH-7, IL-1 is the major stimulating cytokine increasing SAA synthesis by a factor in excess of 100-fold. We also show that under most conditions interleukin-6 and tumour necrosis factor stimulate additively in combination with IL-1. Isoelectric focusing has demonstrated that SAA1 and SAA2 alpha are expressed but not SAA2 beta. The HuH-7 cell line is IL-6 responsive since haptoglobin is stimulated mainly by IL-6.     

Interleukin-6 production by thyroid epithelial cells. Enhancement by interleukin-1.

Interleukin-1 is a potent inhibitor of thyroglobulin and cAMP production in human thyroid cells and the inhibitory effect is enhanced by tumor necrosis factor-alpha and interferon-gamma. In the present study secondary cultures of human thyroid cells produced interleukin-6 and the production was significantly increased after exposure of the cells to recombinant interleukin-1 alpha and -1 beta. This increase was dose-dependent and concomitant of the IL-1 induced decrease in cAMP and thyroglobulin production. Both tumor necrosis factor-alpha and -beta also augmented interleukin-6 production, but less potently than interleukin-1. Interferon-gamma did not affect the production of interleukin-6. The rat thyroid cell line FRTL-5 produced interleukin-6 spontaneously, and the production was enhanced after addition of recombinant interleukin-1 beta. A pathogenetic role of interleukin-6 in autoimmune thyroid disease is suggested.     

Regulation of intracellular Ca concentration by interleukin-1β in rat cortical synaptosomes: an age-related study

The pro-inflammatory cytokine interleukin-1β (IL-1β) is released by cells during injury and stress, and increased neuronal expression of IL-1β is a feature of age-related neurodegeneration. We have recently reported that IL-1β has a biphasic effect on the K⁺-induced rise in intracellular Ca²⁺ concentration ([Ca²⁺]_i) in cortical synaptosomes, exerting an inhibitory effect on the K⁺-induced rise in [Ca²⁺]_i at lower (3.5 ng/mL) concentrations and a stimulatory effect on the K⁺-induced rise in [Ca²⁺]_i at higher (100 ng/mL) concentrations. In the present study, we observed that the K⁺-induced rise in [Ca²⁺]_i was inhibited to a similar extent by the lower concentration of IL-1β in cortical synaptosomes prepared from young (3-month-old), middle-aged (12-month-old) and aged (24-month-old) rats. In contrast, cortical synaptosomes prepared from the aged rats exhibited an increased susceptibility to the higher concentration of IL-1β, resulting in a marked elevation in [Ca²⁺]_i. We propose that the age-related increase in neuronal concentration of IL-1β promotes a dramatic elevation in [Ca²⁺]_i following membrane depolarization, thereby altering Ca²⁺ homeostasis and exacerbating neuronal vulnerability to excitotoxicity.     

The interrelated role of fibronectin and interleukin-1 in biomaterial-modulated macrophage function

Macrophages play a critical role in mediating the host response to biomaterials, perhaps most notably by guiding the host inflammatory response through the release of inflammatory molecules such as the cytokine interleukin-1 (IL-1). The extent of the macrophage response following interaction with the biomaterial surface contributes greatly to device efficacy, yet the molecular mechanisms of this interaction are still unclear. The extracellular matrix (ECM) protein fibronectin (FN) is recognized by macrophages and frequently used in biomaterial modification to elicit greater cellular adhesion and tissue integration. Macrophage interaction with FN and other ECM molecules on the biomaterial surface has been shown to induce a variety of inflammatory responses, thus both FN and IL-1 can be utilized as model molecules to better understand the mechanisms of material-mediated macrophage responses. This literature review presents a comprehensive survey of past and current research on the interrelated role of IL-1, FN, and FN-derivatives in determining biomaterial-modulated macrophage function.     

Stimulation of rat macrophage interleukin 1 secretion by plasma fibronectin

Purified plasma fibronectin (Fn) enhanced the secretory activity of rat peritoneal exudate macrophages as measured by 35S-methionine incorporation into protein released into culture supernatants. Enhancement of protein secretion was dose-dependent and increased with time in culture. Addition of various concentrations of supernatant from cultures of macrophages with Fn resulted in a significant increase in thymocyte proliferation elicited by phytohaemagglutinin. The stimulatory activity of the supernatant was Fn dose-dependent and increased with increasing concentrations of macrophages. This thymocyte stimulatory effect was not due to the presence of Fn in the culture supernatant or to the minimal contamination with endotoxin detected in the Fn preparations. These data suggest that the inflammatory macrophage interaction with Fn results in the release of interleukin-1. They also are consistent with the reported ability of Fn to stimulate lymphocyte transformation.