The role of interleukin-1 in neutrophil leukocyte emigration induced by endotoxin.

Chemotactic factors induce neutrophil emigration into tissues. Interleukin-1 (IL-1) was found to be several log times more potent in this respect than C5a des Arg, leukotriene B4, and f-Met-Leu-Phe and of comparable potency to endotoxin. Kinetic studies revealed a rapid and transient neutrophil influx, with the peak rate at 30-90 minutes. Cross tachyphylaxis was observed between IL-1 and endotoxin; and this, together with its high potency and rapid onset of action, suggest that IL-1 mediates endotoxin-induced neutrophil emigration.     

Macrophage function in the acute phase of lactic dehydrogenase virus-infection of mice: suppression of superoxide anion production in normal mouse peritoneal macrophages by interferon-alpha in vitro.

The effect of interferon (IFN)-alpha on the release of superoxide anions (O2-) by normal mouse macrophages (PEM) was examined. Sera from LDV-infected mice at 1 day, but not at 7 days post-infection, suppressed the O2- release by PEM. When PEM were exposed in vitro for 24 h to IFN-alpha, their capacity to release O2- was significantly suppressed. Progressive suppression of O2- release with increasing IFN-alpha concentration was observed. These results suggest that IFN-alpha in the circulation may be one of several suppressive factors on macrophage function in the early phase of infection and IFN-alpha may play a modulatory role in inflammation and immunity.     

Pharmacology of interleukin-1-induced neutrophil migration

Neutrophil (PMN) accumulation induced by interleukin-1β (IL-1β, 5–20 ng) into the mouse air pouch was inhibited in a dose-dependent manner (2–200 μg) by concomitant injection of IL-1 receptor antagonist (IL-1_RA). Similarly, co-administration of the neuropeptideα-melanocyte-stimulating hormone (α-MSH) resulted in a reduction of the number of migrated PMN but only at the highest dose tested (200 μg). Although IL-1_RA does not select between the two types of receptor so far described for IL-1, the effectiveness ofα-MSH suggests that this property of the cytokine may occur through IL-1 type I receptor. This observation was confirmed by using a specific monoclonal antibody (mAb) raised against this receptor type, and which strongly inhibited (87%) IL-1-induced PMN recruitment.

     

Synergistic induction of interleukin-1 by endotoxin and toxic shock syndrome toxin-1 using rat macrophages.

We studied interleukin-1 (IL-1) secretion by rat peritoneal exudate macrophages stimulated with purified toxic shock syndrome toxin-1 (TSST-1). TSST-1 was observed to be a more potent inducer of IL-1 than was endotoxin. The induction of IL-1 secretion by TSST-1 was not blocked by polymyxin B but could be blocked by monoclonal antibodies directed against TSST-1. Synergistic induction of IL-1 was observed when the cells were stimulated with TSST-1 and endotoxin. The sequence of addition was found to be important for the synergistic response. Enhanced IL-1 production was observed only when macrophages were exposed to endotoxin before or simultaneously with TSST-1. Prior exposure of macrophages to TSST-1 had no enhancing effect on endotoxin-induced IL-1 secretion. We conclude that stimulation of the macrophage by endotoxin enhances the responsiveness of the cells to TSST-1 and may thereby play a role in the pathogenesis of toxic shock syndrome.     

Opioids modulate interleukin-1 production and secretion by bone-marrow macrophages

In the present study, we have assessed the effect of opioids (endorphins, enkephalins and neoendorphins) on production of IL-1 activity by bone-marrow-derived macrophages. None of the neuropeptides induced IL-1 production by itself. However, some of the opioids potentiated IL-1 production and release in macrophages concomitantly stimulated by lipopolysaccharide (LPS) or silica. LPS induced predominantly intracellular IL-1 activity, whereas most of the silica-induced IL-1 was released extracellularly. beta-Endorphin, leucine-enkephalin (leu-enkephalin) and beta-neoendorphin all potentiated both intracellular and extracellular release of IL 1 induced by either LPS or silica. In contrast, alpha-endorphin, methionine-enkephalin (metenkephalin) and alpha-neoendorphin did not influence IL-1 production or release. The potentiating effects of beta-endorphin on LPS-induced IL-1 production/secretion were inhibited by naloxone, pointing to an involvement of opioid receptors.     

Increased superoxide anion release by peritoneal macrophages in mice with a chronic infection of lactic dehydrogenase virus.

The function of macrophages in mice chronically infected by lactic dehydrogenase virus (LDV) was studied. Superoxide anion (O2-) release was examined by using peritoneal macrophages. O2- release increased markedly from 3 weeks to 12 months, but not at 1 week post infection. O2- release was 1.2 to 1.5 times greater than in uninfected mice. Increased O2- release from macrophages in LDV-infected mice may explain, at least in part, suppressive effects on tumour growth seen in the chronic phase of infection.     

Production of a neutrophil chemotactic factor by endotoxin stimulated alveolar macrophages in vitro.

Alveolar macrophages (AM) isolated from normal guinea-pigs and from those chronically exposed to endotoxin (LPS) were cultured in the presence of various concentrations of LPS (from 0.5 ng to 5 micrograms/ml). The presence of a neutrophil chemotactic factor (NCF) in culture supernatants was tested in migrations chambers. Contamination of all reagents has been tested using LAL test (Limulus Amoebocyte Lysate). The results indicate a production of NCF with low LPS concentrations (0.5 and 5 ng/ml) within the first 6 h of incubation: when larger doses are used the response decreases and a significant inhibition is observed with 5 micrograms LPS/ml (P less than or equal to 0.05). When contaminated medium was used, all responses observed were three times higher than with LPS-free medium (P less than or equal to 0.01). However, the response pattern was the same. AM from chronically exposed animals exhibit the same response patterns: the magnitude of NCF production was higher than with normal AM but not significantly. The data suggests that initial conditions of AM in vitro or in vivo with reference to LPS contamination have to be determined as they are of importance when AM NCF production has to be tested.     

Suppressor cells induced by influenza virus inhibit interleukin-2 production in mice.

PR8 virus depressed interleukin-2 (IL-2) and natural killer (NK) cell activity in BALB/c infected mice. IL-2 production was not dependent on (i) a decreased number of T cells or (ii) a primary defect in IL-1 production, but on a T-suppressor cell subpopulation. In fact, when T suppressor cells were removed from infected spleen cells, we observed normal levels of IL-2 activity.     

Suppression of interleukin-2 production by macrophages in genetically susceptible mice infected with Leishmania major.

Spleen cells from BALB/c mice infected with 2 X 10(7) L. major promastigotes and developing progressive disease produced significantly lower levels of interleukin-2 (IL-2) in response to concanavalin A stimulation than did spleen cells from uninfected mice. In contrast, spleen cells from sublethally irradiated and infected mice, which were able to contain lesion development, produced significantly higher levels of IL-2. The increase in IL-2 production closely paralleled lesion regression. Mice protectively immunized by four intravenous injections with lethally irradiated promastigotes also produced enhanced levels of IL-2, which were sustained after challenge infection. In contrast, spleen cells from BALB/c mice given four s.c. injections of irradiated promastigotes produced high levels of IL-2 before but not after infection. These mice eventually produced levels of IL-2 indistinguishable from those of unimmunized mice with progressive disease. There is thus an inverse relation between disease progression and the ability of spleen cells to produce IL-2. Spleen cells from mice with uncontrolled disease not only produced lower levels of IL-2 but also impaired IL-2 production by normal spleen cells. The ability to inhibit IL-2 was abrogated by passing the cells through a Sephadex G-10 column, removal of plastic adherent cells, and removal of carbonyl iron-ingesting cells. Furthermore, Sephadex G-10 column-treated and plastic adherent, nonspecific esterase-positive spleen cells from mice with progressive disease were able to suppress IL-2 production by normal splenic T cells. The suppressive activity of the adherent cells was not affected by treatment with anti-Thy-1.2 antibody and complement. In contrast, adherent spleen cells from uninfected mice were devoid of such suppressor activity. The depressed IL-2 production by spleen cells from progressively infected mice could be restored to that of normal spleen cells by the addition of indomethacin to the culture. There was however, no correlation between IL-2 production and IL-1 activity in infected or immunized BALB/c mice. Thus, it appears that the suppression of IL-2 production is mediated by prostaglandins elaborated by macrophages from chronically infected mice.     

Production of a neutrophil chemotactic factor by endotoxin stimulated alveolar macrophages in vitro

Alveolar macrophages (AM) isolated from normal guinea-pigs and from those chronically exposed to endotoxin (LPS) were cultured in the presence of various concentrations of LPS (from 0.5 ng to 5 micrograms/ml). The presence of a neutrophil chemotactic factor (NCF) in culture supernatants was tested in migrations chambers. Contamination of all reagents has been tested using LAL test (Limulus Amoebocyte Lysate). The results indicate a production of NCF with low LPS concentrations (0.5 and 5 ng/ml) within the first 6 h of incubation: when larger doses are used the response decreases and a significant inhibition is observed with 5 micrograms LPS/ml (P less than or equal to 0.05). When contaminated medium was used, all responses observed were three times higher than with LPS-free medium (P less than or equal to 0.01). However, the response pattern was the same. AM from chronically exposed animals exhibit the same response patterns: the magnitude of NCF production was higher than with normal AM but not significantly. The data suggests that initial conditions of AM in vitro or in vivo with reference to LPS contamination have to be determined as they are of importance when AM NCF production has to be tested.     

Abnormal production of interleukin-1 by microglia from trisomy 16 mice.

The production of interleukin-1 (IL-1) was examined in cultured CNS microglia obtained from trisomy 16 (Ts16) fetal mouse brain, a model system for studies relevant to Down syndrome (DS). When compared to microglia from their normal littermates, Ts16 microglia produced significantly higher levels of IL-1 activity both before and following stimulation with lipopolysaccharide (LPS). IL-1 release was stimulated by alpha/beta interferon (IFN) in the normal but not Ts16 microglial cultures. The overall level of IL-1 production in normal littermates, however, was still less than that seen in Ts16. Thus, microglia from Ts16 mice may function in an inappropriate manner and, if this abnormality occurs in vivo, may have wide ranging effects on a developing nervous system.     

MCP-1 对LPS 致炎小鼠子宫巨噬细胞迁移和功能活性的调节

目的:探讨LPS 诱导的炎症小鼠子宫巨噬细胞迁移和功能活性的调节因素。方法:将150 只雌性昆明种小鼠随机分为对照组(A 组)、LPS 模型组(B 组)、MCP-1 阻断组(C 组),于末次注射后的1、3、6、12、24 h 取子宫。运用免疫组织化学方法检测CD14+巨噬细胞数量与CD14 表达的变化,ELISA 方法检测TNF-α、MCP-1 的表达量。结果:淤与A 组相比,B 组内膜、肌层、外膜的CD14+巨噬细胞数目及CD14 表达量在各时间点均极显著增加(P<0.01),C 组内膜和肌层在1、3、6 h 时恢复至正常水平;与B 组相比,C 组外膜在1、3、6 h 时以及C 组的内膜和肌层在各时间点时CD14+巨噬细胞数目及CD14 表达量均极显著减少(P<0.01)。于与A 组相比,B 组在各时间点以及C 组在12、24 h 时TNF-α和MCP-1 的含量极显著增多(P<0.01);与B 组相比,C 组各时间点的TNF-α和MCP-1 的含量极显著减少(P<0.01)。结论:LPS 诱导的小鼠子宫炎症反应中巨噬细胞的迁移及CD14、TNF-α等关键分子的表达均受MCP-1 的调节。     

Platelet-activating factor enhances interleukin-6 production by alveolar macrophages.

The production of the cytokine interleukin-6 (IL-6) by rat alveolar macrophages (AMs) was analyzed after their stimulation with muramyl dipeptide (1 microgram/ml), in the presence of graded concentrations of platelet-activating factor (PAF). Significantly enhanced production of IL-6 was observed at 10(-10) to 10(-8) mol/L PAF, with peak effect at 10(-10) mol/L. This enhancement was blocked by three structurally unrelated specific PAF receptor antagonists BN 52021, WEB 2170, and CV 3988. The biologically inactive PAF precursor/metabolite, lyso-PAF, and the enantiomer enantio-PAF failed to induce significant enhancement in IL-6 production. In parallel, addition of PAF to AM triggered leukotriene B4 (LTB4) release. Inhibition of 5-lipoxygenase pathway by AA-861 or MK 886 inhibited the PAF-induced augmentation of both IL-6 and LTB4 production, suggesting an implication of endogenous leukotrienes in this mechanism. Furthermore, addition of exogenous LTB4 to AMs could augment their IL-6 production, with peak activity at 10(-12) mol/L LTB4, and reverse the inhibitory effects of 5-lipoxygenase inhibitors. Taken together, these observations suggest that PAF can modulate lung immune and inflammatory responses by enhancing IL-6 production and that this activity may be dependent on secondary 5-lipoxygenase metabolites. This may have clinical relevance in PAF-mediated events in the lung, such as the cellular components of late-phase asthma.     

Mycobacterium avium infection of macrophages results in progressive suppression of interleukin-12 production in vitro and in vivo.

Interleukin-12 (IL-12) has been shown to have an important role in the host defense against Mycobacterium avium. We sought to determine if human monocyte-derived macrophages produce IL-12 upon M. avium infection. Although IL-12 can be measured in supernatants of M. avium-infected macrophages at 24, 48, and 72 h following infection, intracellular staining showed that 24 to 48 h after infection, IL-12 was synthesized chiefly by uninfected macrophages in the monolayer, suggesting that M. avium infection inhibits IL-12 production. In addition, the data also suggest that the longer macrophage monolayers were infected, the less IL-12 they were able to produce. Stimulation of macrophages with IFN-gamma prior to infection with M. avium resulted in greater production of IL-12 compared with unstimulated macrophages. Culture supernatant of M. avium-infected macrophage monolayers, but not control macrophages, partially inhibited IL-12 production by IFN-gamma-stimulated macrophages. This partial inhibition was not reversed by anti-interleukin-10 (anti-IL-10) and anti-transforming growth factor beta 1 (anti-TGF beta 1)-neutralizing antibodies. M. avium infection of macrophages in vitro also suppressed IL-12 synthesis induced by Listeria monocytogenes infection. Immunohistochemistry staining of spleen of infected mice showed that IL-12 production by splenic macrophages was more pronounced in the beginning of the infection but decreased later. Our data indicate that M. avium infection of macrophages suppresses IL-12 production by infected cells and that the suppression was not a result of the presence of IL-10 and TGF beta 1 in the culture supernatant.     

Kinetics of interleukin-1 production by macrophages during infection with Listeria monocytogenes

Production of interleukin-1 (IL-1) by peritoneal macrophages from mice inoculated intravenously with Listeria monocytogenes was measured at increasing intervals of infection. IL-1 activity in the 24 h macrophage supernatants was determined by using the thymocyte PHA co-mitogenesis assay. IL-1 production increased as the infection progressed, reached a peak on the 9th or 10th day and then declined progressively to approach normal values by the 20th day. Our data on the kinetics of IL-1 levels during an acute infection with L.monocytogenes are discussed in relationship to the development of cell-mediated immunity and its regulation by macrophages.     

Estrogen restores cellular immunity in injured male mice via suppression of interleukin-6 production.

This study examined whether estrogen treatment can improve immunity in male mice after combined ethanol and burn injuries. 17beta-Estradiol [estrogen, given subcutaneously (s.c.)] or oil (control) was administered at 30 min and 24 h postinjury. At 48 h postinjury, ethanol/burn-injured mice demonstrated significant suppression of cellular immunity. Estrogen treatment restored the delayed-type hypersensitivity (P<0.01) and splenocyte-proliferative (P<0.05) responses, reduced macrophage interleukin-6 (IL-6) (P<0.05), and increased survival after bacterial challenge (P<0.01). In vitro neutralization of IL-6, combined with macrophage supernatant experiments, confirmed that the beneficial effects of estrogen treatment were mediated through modulation of macrophage IL-6 production. Moreover, estrogen treatment resulted in a decrease in splenic nuclear factor-kappaB (NF-kappaB) activation in injured mice. There were no changes in cellular NF-kappaB or IkappaBalpha protein expression or IkappaBalpha phosphorylation at serine 32. Taken together, these studies suggest that estrogen treatment of injured male mice improves cellular immunity through direct modulation of NF-kappaB activation.     

Control of endotoxin activity and interleukin-1 production through regulation of lipopolysaccharide-lipoprotein binding by a macrophage factor.

Lipopolysaccharides (LPSs) extracted from gram-negative bacteria are much less active when bound to serum lipoproteins. We present evidence here that the binding of radiolabeled LPS extracted from Escherichia coli O113 and Salmonella typhimurium to lipoproteins in rabbit serum is increased 8 to 24 h after a single intravenous injection of homologous or heterologous LPS. Supernatants of activated macrophages containing interleukin-1 also stimulate increased binding. The isolated product of this binding does not induce the production of interleukin-1 by macrophages in vivo or in vitro and is unable itself to stimulate increased binding of LPS to lipoprotein. Normal rabbit sera spiked with lipoprotein fractions prepared from tolerant but not normal rabbit sera bind increased amounts of LPS. These data suggest that there may exist a self-regulated mechanism for decreasing the toxicity of LPS and the production of LPS-induced interleukin-1; this mechanism is controlled by a macrophage factor and functions through altering the binding of LPS to certain serum lipoproteins.     

Inhibition of interleukin-12 production in mouse macrophages via suppression of nuclear factor-kappaB binding activity by Phyllostachys nigra var. henonis

Pharmacological inhibition of interleukin-12 (IL-12) production may be a therapeutic strategy for preventing development and progression of disease in experimental models of autoimmunity. The acetone fraction prepared from bamboo, Phyllostachys nigra var. henonis, potently inhibited the Lipo polysaccharide (LPS)-induced IL-12 production from RAW264.7 monocytic cell-line in a dose-dependent manner. The repressive effect mapped to a region in the IL-12 gene promoter containing a binding site for NF-κB. Furthermore, activation of macrophages by LPS resulted in markedly enhanced binding activity to the NF-κB site, which significantly decreased upon addition of the acetone fraction of Phyllostachys nigra var. henonis. This indicated that the acetone fraction inhibited IL-12 production in LPS-activated macrophages via inhibition of NF-κB binding activity.