Hyaluronic acid is an endogenous inducer of interleukin-1 production by human monocytes and rabbit macrophages

When human peripheral monocytes and rabbit peritoneal macrophages were incubated with hyaluronic acid, the media were found to contain interleukin-1 (IL-1) activity and to stimulate collagenase production by rabbit fibroblasts. A digestion of hyaluronic acid by testicular hyaluronidase decreased the IL-1 inducing activity. Polymixin B, an inhibitor of endotoxin, did not exert any effect towards the action of hyaluronic acid. Hyaluronic acid also stimulated human polymorphonuclear leucocytes to produce IL-1 like activity. These results indicate that hyaluronic acid is an endogenous IL-1 inducer and may play important roles in the pathological and/or physiological changes of connective tissues.     

Effect of histamine and antihistamines on interleukin-1 production by human monocytes

This study was carried out on the effect of histamine hydrochloride and its antagonists on the production of interleukin-1 (IL-1) by lipopolysaccharide (LPS)-stimulated adherent human monocytes (AHM) from normal healthy blood donors. IL-1 activity was evaluated by incorporation of [3H]-thymidine in mouse thymocytes in samples of 1:3 dilution. The result indicated that histamine hydrochloride significantly suppressed IL-1 production by AHM at 10(-3) M and 10(-10) M in 14 donors with maximal suppression observed at 10(-3) M. A 1-hr incubation with histamine hydrochloride (10(-3) M) before addition of LPS was found to be appropriate. Cimetidine, an H2-antagonist at 10(-3) M, 10(-5) M, and 10(-7) M significantly inhibited the effect of histamine hydrochloride (10(-3) M) and gave maximum inhibition at 10(-5) M, whereas chlorpheniramine maleate, and H1-antagonist had no significant inhibitory effect at the concentrations studied (10(-4) M, 10(-5) M, and 10(-7) M). Histamine hydrochloride (10(-3) M) added alone had no significant suppressive effect, while cimetidine (10(-5) M) alone had a significant stimulatory effect on IL-1 production by AHM.     

Modulation of interleukin-1 beta production by cyclic AMP in human monocytes

Elevation of cAMP has been considered to be an important downregulative signal in the production of interleukin-1(IL-1). This study demonstrates that this phenomenon is dependent on the signal used to activate the IL-1 production. The IL-1 beta production of lipopolysaccharide activated human monocytes was readily inhibited by dibutyryl cAMP. This took place without a significant change in the steady-state levels of IL-1 beta mRNA. By contrast, in PMA activated monocytes 100 microM dibutyryl cAMP increased in IL-1 beta production ca. 4-fold. The steady-state levels of IL-1 beta mRNA were also simultaneously increased.     

Immunocytochemical analysis of interleukin-1 beta production by human monocytes]

IL-1 was localized within the cytoplasm of human blood monocytes by indirect immunofluorescence using polyclonal rabbit antibodies. After LPS stimulation first IL-1-positive cells appeared at 2 hours and maximal intracellular IL-1 concentration was observed at 10-24 hours when nearly 90% monocytes were labeled with subsequent decline at 48 hours. The highest intracellular IL-1 content preceded its maximal level in cell supernatants.     

Colony-stimulating factor-1 induces thromboplastin activity in murine macrophages and human monocytes

Highly purified colony-stimulating factor-1 induced thromboplastin activity in murine macrophages and human monocytes in vitro. The activity increase was inhibited by cycloheximide and prevented by antibodies to CSF-1.     

Interleukin-1 production and antigen presentation by normal human peritoneal macrophages

Human peritoneal macrophages from healthy females have been investigated for their capability to produce interleukin-1 (IL-1), their expression of HLA-DR and -DQ, and for their antigen-presenting capacity in concanavalin A, tetanus toxoid (TT), and autologous T-cell proliferative responses. Fifteen out of thirty macrophage populations produced IL-1 but the activity was 1/5 to 1/10 that of peripheral blood mononuclear cells stimulated under similar conditions. High levels of HLA-DR were expressed on all macrophages while lower and more variable levels of DQ were found. All macrophages induced mitogen-dependent T-cell proliferation while the ability to induce a proliferative response to TT was variable, 12/23 tests were positive. In five samples stimulatory capacity of macrophages in the absence of TT was as strong as in the presence of the stimulus, suggesting that in vivo processed immunogen could be responsible for the proliferative response. The surface density of HLA-D-region-determined antigens was not indicative of the macrophages' ability to induce antigen-specific proliferation. IL-1 production, however, correlated with this function. Antigen presentation was not confined exclusively to peritoneal populations consisting of recently immigrant monocyte-like cells, nor were all young macrophages able to present antigen. This may reflect on the diversion of macrophage function by the local environment.     

Role of monocytes/macrophages and interleukin 1 in antigen-induced human lymphokine production

The monocyte/macrophage (M phi)-dependency for antigen-induced production of the lymphokine, leukocyte migration inhibitory factor (LIF), was investigated using a M phi pulse-exposure technique. M phi-depleted, purified T lymphocytes did not elaborate LIF in response to the recall antigen, tuberculin (PPD). Addition of M phi's pulsed with PPD rectified the response. Exposure of the M phi's down to 3 min, even at 0 degree C, was efficacious. PPD-exposed M phi's, either killed or rendered incapable of protein synthesis, failed to activate the T cells. However, PPD-exposed, killed M phi's triggered LIF production if exogenous interleukin 1 (IL-1) was provided. We suggest that M phi "presentation" of antigen in this test system is a passive albeit necessary, process; the requirement for M phi metabolism being confined to the elaboration of IL-1. Judged by the results of kinetic experiments, the latter stimulus appears to be mediated most effectively from 2 to 4 hr after antigenic challenge.     

Induction of interleukin-1alpha production in murine Sertoli cells by interleukin-1

In the present study we examined the involvement of interleukin (IL)-1alpha, -1beta, FSH, and lipopolysaccharide (LPS) in the regulation of IL-1alpha and -1beta production by Sertoli cells under in vitro conditions. Sertoli cell cultures from immature mice produced constitutively basal levels of intracellular IL-1alpha. Stimulation of Sertoli cell cultures with LPS (5 microgram/ml) resulted in a maximal production of intracellular IL-1alpha 2 h after the stimulation. Thereafter, these levels decreased but remained significantly higher within 24 h after stimulation than those in control cultures. The effect of LPS on IL-1alpha production was dose dependent. FSH did not show any effect on intracellular IL-1alpha production by Sertoli cells. IL-1alpha could not be detected in supernatants of unstimulated or stimulated Sertoli cell cultures. Sertoli cell cultures stimulated with recombinant IL-1alpha induced optimal intracellular levels of IL-1alpha within 2 h of stimulation. These levels remained high 24 h after stimulation. However, stimulation of Sertoli cell cultures with IL-1beta induced a peak of IL-1alpha production 8 h after stimulation. These levels decreased 24 h after the stimulation but were still found to be significantly higher than those in control cultures. The addition of IL-1 receptor antagonist (IL-1ra) to Sertoli cell cultures did not significantly alter their capacity to produce IL-1alpha. However, the stimulatory effects of recombinant IL-1alpha on IL-1alpha production by Sertoli cell cultures were reversed by the concomitant addition of recombinant IL-1ra. No immunoreactive IL-1beta could be detected in lysates or conditioned media of immature murine Sertoli cells under any of the stimulatory conditions outlined. Our results may suggest the involvement of physiological (IL-1) and pathophysiological factors (LPS) in the regulation of spermatogenesis and spermiogenesis processes and male fertility.     

Imidocarb,a potent anti-protozoan drug,up-regulates interleukin-10 production by murine macrophages

Interleukin-10 (IL-10), a potent antiinflammatory and immunosuppressive cytokine, plays an important role in the regulation of immune responses. To discover small molecules that stimulate IL-10 production, a cell-based screening assay was performed using a murine macrophage cell line, RAW264.7. Imidocarb, (3,3'-bis-2-imidazolin-2-yl)-carbanilide, which has been used as an anti-protozoan drug for the prevention and treatment of babesiosis in cattle, was thus identified. Imidocarb markedly enhanced LPS-induced IL-10 production not only by RAW264.7 cells but also by murine peritoneal macrophages in a concentration-dependent manner. It also augmented IL-10 production in the presence of zymosan, a yeast cell wall component. In contrast, imidocarb inhibited LPS-induced tumor necrosis factor (TNF)-alpha production by peritoneal macrophages. In mice, intraperitoneal administration of imidocarb significantly increased serum IL-10 levels and lowered TNF-alpha levels. Our results suggest that a novel anti-inflammatory property of imidocarb could lead to new therapeutic approaches in inflammatory conditions.     

Autocrine regulation of interleukin-8 production in human monocytes

Interleukin (IL)-8 is a C-X-C chemokine that plays an important role in acute inflammation through its G protein-coupled receptors CXCR1 and CXCR2. In this study, we investigated the role of IL-8 as an autocrine regulator of IL-8 production and the signaling mechanisms involved in human peripheral blood mononuclear cells (MNCs). Sepharose-immobilized IL-8 stimulated a sevenfold increase in IL-8 production within 2 h. IL-8 induced the expression of its own message, and IL-8 biosynthesis was inhibited by cycloheximide and actinomycin D, indicating de novo RNA and protein synthesis. In contrast to MNCs, polymorphonuclear neutrophils did not respond to the immobilized IL-8 with IL-8 production despite cell surface expression of CXCR1 and CXCR2. Melanoma growth-stimulatory activity/growth-related protein-alpha (MGSA/GROalpha), which binds CXCR2 but not CXCR1, was unable to either stimulate IL-8 secretion in MNCs or desensitize these cells to respond to immobilized IL-8. The involvement of mitogen-activated protein kinase (MAPK) in IL-8-induced IL-8 biosynthesis was suggested by the ability of PD-98059, an inhibitor of MAPK kinase, to block this function. Furthermore, IL-8 induced a significant increase in extracellular signal-regulated kinase 2 phosphorylation, whereas MGSA/GROalpha was much less effective. These findings support the role of IL-8 as an autocrine regulator of IL-8 production and suggest that this function is mediated by CXCR1 through activation of MAPK.     

单核／巨噬细胞分泌TNF—α的调控及在老年时的改变

肿瘤坏死因子－α（ＴＮＦ－α）是一种主要由单核／巨噬细胞分泌的细胞因子。它不仅有杀伤肿瘤细胞的特性,还在炎症、休克和自身免疫等病理过程中起重要作用。刺激巨噬细胞分泌ＴＮＦ－α的主要物质有内毒素、病毒、某些细胞因子和有丝分裂原以及神经肽等。而前列腺素Ｅ（ＰＧＥ）、ｃＡＭＰ类似物和肾上腺素类等可抑制其分泌。很多文献报道ＴＮＦ－α在老年时单核／巨噬细胞的分泌有改变。     

Regulation of interleukin-6 receptor expression in human monocytes and hepatocytes

Human blood monocytes normally express the interleukin-6 receptor. Treatment of cultured monocytes with endotoxin, interleukin-1 beta, or interleukin-6 results in a decrease in interleukin-6 receptor mRNA levels. Glucocorticoids aso cause a drop in monocytic interleukin-6 receptor mRNA levels. We also found interleukin-6 receptor expression in cultured human hepatocytes, but in contrast to monocytes, where interleukin-6 receptor mRNA is presented by the ligand and by interleukin-1, treatment of hepatocytes with interleukin-6 or interleukin-1 resulted in increased interleukin-6 receptor mRNA levels. Induction of interleukin-6 receptor mRNA in hepatocytes was less pronounced when glucocorticoids were omitted from the culture medium. We conclude that during noninflammatory homeostasis, blood monocytes are involved in binding of trace amounts of circulating interleukin-6. During inflammatory events, the main target of interleukin-6 may be changed from the monocytic population not only to activated B-cells, but also to the hepatocytes.     

Induction of interleukin-10 by human immunodeficiency virus type 1 and its gp120 protein in human monocytes/macrophages.

In this study, we evaluated the effects of human immunodeficiency virus type 1 (HIV-1) and its gp120 protein on interleukin-10 (IL-10) expression in cultured human monocytes/macrophages. Infection of either 1-day monocytes or 7-day monocyte-derived macrophages with HIV-1 strain Ba-L resulted in clear-cut accumulation of IL-10 mRNA at 4 and 24 h. Likewise, treatment of these cells with recombinant gp120 induced IL-10 mRNA expression and caused a marked increase in IL-10 secretion. Monoclonal antibodies to gp120 strongly inhibited recombinant gp120-induced IL-10 secretion by monocytes/macrophages. Moreover, the addition of IL-10 to monocytes/macrophages resulted in a significant inhibition of HIV-1 replication 7 and 14 days after infection. On the whole, these results indicate that HIV-1 (possibly through its gp120 protein) up-regulates IL-10 expression in monocytes/macrophages. We suggest that in vivo production of IL-10 by HIV-primed monocytes/macrophages can play an important role in the early response to HIV-1 infection.     

Biosynthesis of normal and low-molecular-mass complement component C1q by cultured human monocytes and macrophages.

High levels of low-molecular-mass complement component C1q (LMM-C1q), a haemolytically inactive form of C1q, are found in serum of individuals with inherited complete (functional) C1q deficiency and in serum of patients with systemic lupus erythematosus, whereas lower levels are present in normal serum [Hoekzema, Hannema, Swaak, Paardekooper & Hack (1985) J. Immunol. 135, 265-271]. To investigate whether LMM-C1q is a (by-)product of C1q synthesis or the result of degradation of C1q, cultures of blood monocytes and of alveolar macrophages, which secrete functional C1q, were studied. A considerable portion of C1q-like protein secreted by these cells was found to be LMM-C1q. In contrast with the C1q fragments that resulted from degradation of normal C1q during phagocytosis, culture-derived LMM-C1q appeared to be identical with LMM-C1q found in serum, as judged by sedimentation behaviour, subunit structure and recognition by poly- and mono-clonal antibodies raised against C1q. The presence of LMM-C1q in cytoplasmic organelles compatible with the Golgi apparatus and the inability to generate LMM-C1q by impeding hydroxylation and triple-helix formation of C1q further argues against degradation as its source. Monocyte cultures of homozygous probands from two families with complete functional C1q deficiency reflected the abnormalities in serum, i.e. absence of functional C1q, but increased levels of LMM-C1q. By contrast, secretion of C1q and LMM-C1q by cells from healthy individuals was clearly co-ordinate, indicating that LMM-C1q in serum may provide a unique marker of C1q synthesis in vivo.     

Role of glucose in interleukin-1β production by lipopolysaccharide-activated human monocytes

When monocytes are activated with endotoxin (lipopolysaccharide [LPS]), they make and release several mediators, including interleukin-1β (IL-1β). This study was undertaken to investigate the role of glucose in IL-1β production by these cells. IL-1β was produced in a dose-dependent manner to glucose concentration in the culture medium. The uptake of (³H)2-deoxyglucose in monocytes was stimulated by LPS 1,554% after 10 minutes, 6,095% after 2 hours, then gradually declined after 4 hours of incubation. The inhibition of the uptake of (³H)2-deoxyglucose by either 10 μM cytochaiasin B or phloretin, added at the time of monocyte activation, was accompanied by significant reduction in ATP/ADP ratio and the inhibition of the production of IL-1β by activated monocytes. The synthesis of total protein did not change in monocytes activated in the absence of glucose in the culture medium, nor in the presence of either 10 μM cytochalasin B or phloretin. The export of IL-1β from LPS-activated monocytes was not inhibited by either 10 μM cytochalasin B or phloretin, nor in the absence of glucose in the culture medium. These data suggest that (1) glucose is required for LPS-induced IL-1β production by monocytes; (2) glucose is the major source of ATP for IL-1β production; (3) glucose transporter (GLUT 1) does not control the export of IL-1β. © 1993 Wiley-Liss, Inc.     

Opposite effects of interleukin-4 and interleukin-10 on nitric oxide production in murine macrophages

Interleukin-4 (IL-4) and interleukin-10 (IL-10) were evaluated for their ability to inhibit the production of nitric oxide (NO) by interferon-gamma (IFN-gamma)- or lipopolysaccharide (LPS)-activated murine macrophages (RAW 264.7 and J774.2). Macrophages pre-treated with IL-4 and then stimulated with IFN-gamma or LPS showed significant inhibition in their ability to produce NO as measured by nitrite production. Simultaneous treatment of IL-4 pre-incubated cells with IFN-gamma and LPS together augmented nitrite accumulation. On the other hand, similar exposures of the macrophages to IL-10 followed by IFN-gamma or LPS treatments resulted in significantly increased NO production. Thus IL-10 failed to suppress IFN-gamma or LPS-induced NO production and showed opposite effects in these experiments to IL-4. We conclude that the two lymphokines have differing roles in the control of production of NO and might act to control the secretion of nitric oxide in vivo.     

Complex assessment of the production of 3 variants of interleukin-1 by human peripheral blood monocytes

In vitro production of intracellular, membrane-associated and secreted interleukin-1 was investigated by peripheral blood monocytes from healthy donors. Activity of three IL-1 variants was assayed by the proliferation of responsive C3H/HeJ mouse thymocytes. Complex evaluation of IL-1 pools production by human PBM would provide a key to a better understanding of various diseases pathogenesis.