Multiple biological properties of recombinant human interleukin 1 (beta)

Inflammation in the Pathophysiology and Therapy of Cardiometabolic Disease

The role of chronic inflammation in the pathogenesis of type 2 diabetes mellitus and associated complications is now well established. Therapeutic interventions counteracting metabolic inflammation improve insulin secretion and action and glucose control and may prevent long-term complications. Thus, a number of anti-inflammatory drugs approved for the treatment of other inflammatory conditions are evaluated in patients with metabolic syndrome. Most advanced are clinical studies with IL-1 antagonists showing improved β-cell function and glycemia and prevention of cardiovascular diseases and heart failure. However, alternative anti-inflammatory treatments, alone or in combinations, may turn out to be more effective, depending on genetic predispositions, duration, and manifestation of the disease. Thus, there is a great need for comprehensive and well-designed clinical studies to implement anti-inflammatory drugs in the treatment of patients with metabolic syndrome and its associated conditions.

Postprandial macrophage-derived IL-1β stimulates insulin, and both synergistically promote glucose disposal and inflammation

The deleterious effect of chronic activation of the IL-1β system on type 2 diabetes and other metabolic diseases is well documented. However, a possible physiological role for IL-1β in glucose metabolism has remained unexplored. Here we found that feeding induced a physiological increase in the number of peritoneal macrophages that secreted IL-1β, in a glucose-dependent manner. Subsequently, IL-1β contributed to the postprandial stimulation of insulin secretion. Accordingly, lack of endogenous IL-1β signaling in mice during refeeding and obesity diminished the concentration of insulin in plasma. IL-1β and insulin increased the uptake of glucose into macrophages, and insulin reinforced a pro-inflammatory pattern via the insulin receptor, glucose metabolism, production of reactive oxygen species, and secretion of IL-1β mediated by the NLRP3 inflammasome. Postprandial inflammation might be limited by normalization of glycemia, since it was prevented by inhibition of the sodium-glucose cotransporter SGLT2. Our findings identify a physiological role for IL-1β and insulin in the regulation of both metabolism and immunity.

Role of cytokines in endometrium and at the fetomaternal interface

Cytokines were first recognized as factors involved in the immune responses. However, emerging evidence suggests that cytokines serve as the unanimous language through which cells in organ systems as diverse as hypothalamus to endometrium communicate. Evidence for the participation of these factors in the normal function of the endometrium and uteroplacental unit and development of the embryo is being recognized. This review will highlight the significant insight gained over the past several years for the role of cytokines in the field of reproductive biology. Major emphasis will be placed on interleukins, tumour necrosis factor-α, transforming growth factors, colony stimulating factors and interferon-gamma.

Role of interleukin-1beta in the modulations of cytochrome P450 and heme metabolism in rat liver

The effect of recombinant human interleukin-1beta (IL-1beta) on the modulation of hepatic cytochrome P450 (P450) was investigated by in vivo subcutaneous dosing studies in male Sprague-Dawley rats. To assess the effect of IL-1beta on heme metabolism, we determined the delta-aminolevulinic acid synthetase (delta-ALAS) and heme oxygenase activities in the liver. IL-1beta suppressed the microsomal total P450 and heme contents and delta-ALAS activity in the liver. In contrast, microsomal heme oxygenase activity was significantly increased by the IL-1beta treatments. Western blot analysis and marker enzyme activities for individual P450 isoforms demonstrated that IL-1beta suppressed CYP2C6, 2C13, 2E1, and 3A2, whereas CYP2A, 2B1/2, 2C11, and 4A1 were not influenced by the treatments. IL-1beta inhibited both allylisopropylamide- and phenobarbital-inducible delta-ALAS activities in the liver. These results indicate that IL-1beta has differential effects on the constitutive P450, and also on delta-ALAS and heme oxygenase activities in rat liver. Thus, the modulation of hepatic P450 by IL-1beta is complex, and IL-1beta may be involved in the regulation of both apoprotein synthesis for each P450 isoform and the heme pools in the liver.

Reduction of cerebellar GABAA responses by interleukin-1 (IL-1) through an indomethacin insensitive mechanism

Recently, a role of IL-1 in the central nervous system has been described, principally a fever-inducing effect in the hypothalamus through a prostaglandin second messenger system. IL-1 has also been shown to potentiate gamma-aminobutyric acid (GABAA) responses in embryonic chick neurones. This study describes the investigation of the effect of IL-1 on GABAA responses within the in vitro rat cerebellar slice, a preparation containing intact neuronal circuitry. Stimulation of the area of passage of paralleled fibres produced a pure GABAA inhibition of the spontaneous firing of Purkinje cells. 5 and 10 ng/ml IL-1 produced a reduction in the duration of inhibition 10 min after beginning perfusion of IL-1. This effect reversed within 15 min of washing out the IL-1. 10 ng/ml IL-1 also reduced the effects of exogenously-applied GABA (0.1 mM) with the same time course. In the presence of 1 uM indomethacin, there was no change in the effect of the IL-1. It can therefore be concluded that the reduction in cerebellar GABAA responses by IL-1 is not mediated by the indomethacin-sensitive prostaglandin second messenger system.

Interleukin-1 beta (IL-1 beta) and acute leukemia: in vitro proliferative response to IL-1 beta, IL-1 beta content of leukemic cells and treatment outcome

We evaluated the in vitro proliferative response to exogenous IL-1 beta in terms of tritiated thymidine (3H-TdR) incorporation in leukemic cells obtained from 119 patients with various types of acute leukemia. The content of IL-1 beta in leukemic cells was measured by enzyme-amplified sensitivity immunoassay. We observed a significant proliferative response to exogenous IL-1 beta in leukemic cells from 27/66 patients with de novo AML, 1/29 patients with ALL, 2/3 patients with AUL, 8/12 patients with AML arising from MDS, 4/7 patients with myeloid crisis of CML, and 0/4 patients with lymphoid crisis of CML. Proliferation was marked in myeloid leukemic cells of a more premature stem cell origin. There were no significant differences in proliferative responses among the different FAB classes of de novo AML. The IL-1 beta content of leukemic cells was low in patients with lymphoid leukemia, but there was no significant difference among the various types of myeloid leukemia. There was no correlation between the proliferative response to exogenous IL-1 beta and the IL-1 beta content of leukemic cells. When we correlated the proliferative response to exogenous IL-1 beta with treatment outcome in patients with de novo AML, we found the rate of complete remission (CR) to be lower in those with a high proliferative response. We noted a longer duration of CR (p = 0.07) and of survival (p < 0.05) in patients with a low proliferative response. Thus, a high proliferative response to IL-1 beta in the cells of AML patients may indicate a poor prognosis.

Effects of intramammary endotoxin infusion on milking-induced oxytocin release

One overt sign of clinical coliform mastitis in dairy cows is the failure to eject milk normally or to "milk out" the udder. The effect, if any, of coliform mastitis on oxytocin release is unknown. Therefore, the objective of this study was to determine the effect of endotoxin mastitis on milking-induced release of oxytocin in lactating cows. Fifteen multiparous pregnant lactating Holstein cows were divided into three groups of 5 cows each. Cows in group 1 served as controls and received an intramammary infusion of sterile physiological saline. Cows in groups 2 and 3 received intramammary infusions of 12.5 and 25 micrograms of Escherichia coli endotoxin, respectively. Serum concentrations of oxytocin were measured by radioimmunoassay before, during, and after milkings commencing at 6 and 12 h after treatment. Rectal temperatures and milk SCC were monitored to follow the course of inflammation and to verify the biological activity of infused endotoxin. Endotoxin resulted in a 1.5- to 2-fold increase in milking-induced oxytocin release compared with that of control treatments. The effect was most prominent during the first 6 h after infusion and coincided with the peak pyretic response. This study shows that endotoxin-induced mastitis potentiates, rather than inhibits, milking-induced oxytocin release.

Increased transforming growth factor-beta 1 gene expression in human liver disease

We recently demonstrated that transforming growth factor-beta 1 stimulates collagen synthesis in hepatic cells in vitro, and that the synthesis of this cytokine is markedly increased in two rodent models of hepatic fibrosis. In the present study, we investigated the association of transforming growth factor-beta 1 (TFG-beta 1) gene expression in human liver disease. Sixteen patients with active liver disease had percutaneous liver biopsies performed for diagnostic purposes. Total RNA was extracted from an unused portion of each biopsy and then subjected to hybridization analysis with the following human cDNA clones: albumin, pro alpha 1 (I) collagen, and TGF-beta 1. Surgical liver biopsy specimens from two patients without hepatic disease were used as controls. When compared to controls, the patients with active liver disease had a 19% decrease in albumin, a 97% increase in type I collagen, and a 120% increase in transforming growth factor-beta 1 mRNA levels. Moreover, steady-state levels of TGF-beta 1 and procollagen mRNAs were significantly correlated. Nuclear run-on assays showed that livers from two patients with fibrosis had TGF-beta 1 transcription rates that were more than 2-fold higher than rates in control livers. These findings indicate that transforming growth factor-beta 1 gene expression is significantly enhanced in man during active liver disease.

Species restrictions demonstrated by the stimulation of equine cells with recombinant human interleukin-1

Equine thymocytes, which respond to equine monocyte supernatants, do not respond to stimulation with recombinant human interleukin-1 alpha and beta, and equine synovial fibroblasts show a limited response in the form of prostaglandin E2 production without any evidence of neutral metalloproteinase production. Human interleukin-1 beta was about three to ten times as active on equine synovial cells as human interleukin-1 alpha in terms of prostaglandin E2 production. This preliminary evidence would suggest that there are qualitative and quantitative differences in the way recombinant human interleukin-1 stimulates human cells and the way in which it stimulates equine cells.

Sertoli cells are the site of interleukin-1 alpha synthesis in rat testis

To elucidate the cellular origin of interleukin-1 (IL-1) in the mammalian testis, we assayed IL-1 activity in culture media of Sertoli cells collected from rats at 20, 35 and 45 days of age as well as in culture media of interstitial, peritubular and germ cells from adult rats. IL-1 was detected in Sertoli cell culture media isolated from 35- and 45-day-old rats. At 45 days approximately twice as much IL-1 was produced than at 35 days. In contrast, IL-1 activity was not detected in 20-day-old rat Sertoli cell culture media nor in interstitial, peritubular and germ cell culture media. The Sertoli cell IL-1 activity was specifically neutralized by an IL-1 alpha antiserum. It is concluded that Sertoli cells produce IL-1 alpha and that this production increases during sexual maturation.

Immunoregulators in the nervous system

The nervous system, through the production of neuroregulators (neurotransmitters, neuromodulators and neuropeptides) can regulate specific immune system functions, while the immune system, through the production of immunoregulators (immunomodulators and immunopeptides) can regulate specific nervous system functions. This indicates a reciprocal communication between the nervous and immune systems. The presence of immunoregulators in the brain and cerebrospinal fluid is the result of local synthesis--by intrinsic and blood-derived macrophages, activated T-lymphocytes that cross the blood-brain barrier, endothelial cells of the cerebrovasculature, microglia, astrocytes, and neuronal components--and/or uptake from the peripheral blood through the blood-brain barrier (in specific cases) and circumventricular organs. Acute and chronic pathological processes (infection, inflammation, immunological reactions, malignancy, necrosis) stimulate the synthesis and release of immunoregulators in various cell systems. These immunoregulators have pivotal roles in the coordination of the host defense mechanisms and repair, and induce a series of immunological, endocrinological, metabolical and neurological responses. This review summarizes studies concerning immunoregulators--such as interleukins, tumor necrosis factor, interferons, transforming growth factors, thymic peptides, tuftsin, platelet activating factor, neuro-immunoregulators--in the nervous system. It also describes the monitoring of immunoregulators by the central nervous system (CNS) as part of the regulatory factors that induce neurological manifestations (e.g., fever, somnolence, appetite suppression, neuroendocrine alterations) frequently accompanying acute and chronic pathological processes.

Cytokine regulation of human endometrial function

Human endometrium undergoes sequences of proliferation, and secretion followed by menstruation in a predictable fashion. The importance of systemic factors, steroid hormones, in driving endometrium through these phases is well known. However, it is becoming increasingly apparent that a group of factors collectively called cytokines may also serve a key role as local modulators of endometrial function. Expression of the receptors for cytokines, production of cytokines and the ability to demonstrate modulation of a host of functions of both endometrial epithelium and stroma indicate that human endometrium is uniquely poised to respond to cytokines.

Ionic mechanism of the outward current induced by extracellular ejection of interleukin-1 onto identified neurons of Aplysia

The ionic mechanism of the effect of extracellularly ejected recombinant human interleukin-1-beta (rhIL-1) on the membrane of identified neurons R9 and R10 of Aplysia was investigated with voltage-clamp, micropressure-ejection, and ion substitution techniques. Micropressure-ejected rhIL-1 caused a marked hyperpolarization in the unclamped neuron. Clamping the same neuron at its resting potential level (-60 mV) and reejecting rhIL-1 with the same dose produced a slow outward current (I0(IL-1), 20-30 s in duration, 3-5 nA in amplitude) associated with a decrease in input membrane conductance. I0(IL-1) was decreased by depolarization and increased by hyperpolarization. The extrapolated reversal potential of I0(IL-1) was approximately +15 mV. I0(IL-1) was sensitive to changes in the external Na+ concentration but not to changes in K+, Ca2+ and Cl- concentrations, and was resistant to tetraethylammonium (5 mM) and 4-aminopyridine (5 mM). Neither perfusion of the neuron with 50 microM tetrodotoxin nor perfusion with 10 mM Co2+ seawater caused any changes in I0(IL-1). I0(IL-1) was partially reduced by 50 microM ouabain. These results suggest that extracellular IL-1 can induce a slow outward current associated with a decrease in Na+ conductance and the immunomodulator IL-1 can act directly on the nervous system as well as on the immune system.

Growth regulation of hematopoietic cells. An overview

The production of mature blood cells is absolutely dependent on a small pool of pluripotent stem cells with high proliferative and self-renewal capacities. The hematopoietic stem cells develop gradually from pluripotent to unipotent, committed progenitor cells during which process they lose their self-renewal capacity. This development is dependent on interactions with specific hematopoietic growth factors, which by binding to surface receptors on the stem cells stimulate them to proceed to the next step of differentiation. During recent years several of the hematopoietic growth factors have been purified to homogeneity, their primary protein as well as genetic structures have been determined and today they are available for clinical trials as recombinant proteins produced in bacteria, yeast or mammalian cells. Our present knowledge sustains the notion that IL-3, and to a lesser extent GM-CSF, play a major role in multipotent hematopoietic stem cell survival, proliferation and differentiation into stem cells with restricted maturation programs. The programmed unipotent stem cells need stimulation by erythropoietin, G-CSF, M-CSF and IL-5 to proliferate and mature into their end stage products erythrocytes, neutrophils, monocytes and eosinophils respectively. Other cytokines such as IL-1, IL-4 and IL-6 fulfil important functions as cofactors in these processes and several others play the part of tentative physiological inhibitors. During the past decade major progress has been made in our understanding of the complex interplay between stem cells, accessory cells, growth factors, and their receptors, and the clinical trials now undertaken will certainly bring even more basic knowledge to the field of hematopoietic growth regulation.

Interleukin-1 inhibits follitropin-induced aromatase activity in immature rat Sertoli cells in vitro

The effects of recombinant preparations of human interleukin-1 (IL-1) on basal and follitropin (FSH)-stimulated aromatase activity of immature rat Sertoli cells in vitro were studied. Sertoli cells were isolated from 7- to 10-day-old rats and cultured for 72 h at 32 degrees C in the presence or absence of test materials. The cells were then washed and cultured for a further 24 h with different doses of FSH in the presence or absence of IL-1. Neither IL-1 alpha nor IL-1 beta had any effect on basal aromatase activity. IL-1 beta inhibited FSH-stimulated aromatase activity in a dose-dependent manner while IL-1 alpha had no significant effect. The inhibitory influence of IL-1 beta on FSH-stimulated aromatase activity was greater when IL-1 beta was present in low concentrations (0.5 and 1.0 U) during the initial 72 h culture period and a further 24 h incubation with IL-1 beta did not cause a further inhibition. When the cells were cultured for 72 h in the presence of both IL-1 alpha and IL-1 beta, the inhibition of FSH-stimulated aromatase was higher than that obtained with IL-1 beta alone. The inhibitory activity of IL-1 beta was blocked by a specific IL-1 beta antiserum. Furthermore, IL-1 beta caused a significant inhibition of cAMP production in Sertoli cells and did not influence dibutyryl-cAMP-stimulated aromatase activity under identical experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Late-stage mediators of the inflammatory response: identification of interleukin-1 and a casein-degrading enzyme in equine acute inflammatory exudates

Interleukin-1 and a casein-degrading enzyme have been identified in an experimental system for studying acute inflammation in the horse. The levels of both the cytokine and the proteinase increased over the first 24 hours following initiation of the inflammatory response, and remained at high levels through to the last sample collected at 48 hours. This is in marked contrast to prostaglandin E2 concentrations which were low initially, peaked at four to eight hours and had returned to low levels by 12 to 24 hours. It is likely that interleukin-1 and various proteinases are involved in the later stages of the inflammatory response, such as the tissue remodelling associated with wound repair, and control of this cytokine may be important in the progression from acute to chronic inflammation.

A monoclonal antibody directed against the human intercellular adhesion molecule (ICAM-1) modulates the release of tumor necrosis factor-alpha, interferon-gamma and interleukin 1

ICAM-1 is a cell surface glycoprotein which is one of the ligands for the leukocyte function-associated antigen (LFA-1). It is involved in leukocyte adhesion to endothelial cells as well as in immune functions requiring cell-cell contact. The quantitative expression of ICAM-1 in various cell types can be either induced or enhanced by treatment with cytokines, such as interferon-gamma (IFN-gamma), tumor necrosis factor (TNF)-alpha or interleukin 1 (IL 1), a phenomenon which results in the augmentation of binding to LFA-1-positive cells. In contrast, treatment with anti-ICAM-1 antibodies blocks this binding. A monoclonal antibody (mAb), termed 7F7, which recognizes an epitope on ICAM-1, was used to investigate the role of ICAM-1 in cytokine production by T lymphocytes and monocytes. Production of TNF-alpha. IFN-gamma and IL1 was significantly inhibited (p less than 0.01) by the incubation of mAb 7F7 with phytohemagglutinin-activated blood mononuclear cells (MNC) or isolated E rosette-positive T lymphocytes. The maximal level of inhibition was reached with 1 microgram/ml of purified antibody. A similar inhibition was obtained using saturating concentrations of 400 microliters/ml of mAb 7F7 hybridoma supernatant corresponding to an inhibitory activity of 1 microgram of purified mAb. In contrast, granulocyte/macrophage-colony-stimulating factor release showed a heterogeneous response over five experiments with an increase found in three experiments and a decrease in two experiments. Addition of increasing concentrations of supernatant or purified mAb to unstimulated MNC or T lymphocyte cultures had no effect on cytokine release. The observed inhibition of the production of TNF-alpha. IFN-gamma and IL 1 by antibody-mediated blockade of the ICAM-1 structure probably represents a negative circuit that serves to tune the activation of leukocytes and to avoid an overproduction of cytokines.

Antitumor effect of recombinant human interleukin-1 beta alone and in combination with natural human tumor necrosis factor-alpha

In order to investigate the antitumor effect of recombinant human interleukin-1 beta (IL-1 beta) alone and in combination with natural human tumor necrosis factor-alpha (nHuTNF-alpha), we used female BDF1 mice bearing Lewis lung carcinoma (3LL). IL-1 beta showed an antiproliferative effect against pulmonary metastatic tumors of 3LL in a dose-dependent manner. We observed 19.6 +/- 6.6, 18.6 +/- 5.3, 14.1 +/- 4.4 and 13.0 +/- 6.0 metastatic tumors at doses of 0.5, 1.0, 2.5 and 5.0 micrograms IL-1 beta/mouse/day by daily intravenous administration (the number of metastatic tumors of the control group was 26.3 +/- 8.2). Similar results were obtained by intraperitoneal administration, but in this case, mice showed a marked decrease of body weight. When IL-1 beta was administered in combination with nHuTNF-alpha, pulmonary metastatic tumors decreased much more than when IL-1 beta was administered alone. When the control group had 18.6 +/- 12.7 metastatic tumors, the nHuTNF-alpha group had 12.3 +/- 3.9 and the IL-1 beta group had 12.8 +/- 8.0, the group which was administered both cytokines had a significantly decreased number of 5.6 +/- 3.3 metastatic tumors. This antiproliferative effect of IL-1 beta in combination with nHuTNF-alpha was reduced by the intravenous administration of anti-asialo GM1 antibody and carrageenan. The number of metastatic tumors was increased from 8.9 +/- 8.0 to 18.8 +/- 11.4 by anti-asialo GM1 antibody and from 9.5 +/- 6.8 to 28.0 +/- 12.3 by carrageenan. It was suggested that asialo GM1-positive cells and macrophage were two of the most important effectors of the antiproliferative effect of IL-1 beta and TNF-alpha.

Physiological responses to intramammary or intravenous treatment with endotoxin in lactating dairy cows

Twenty-one, middle to late lactation Holstein cows were assigned to one of three treatments in a completely randomized design to examine physiological changes associated with intramammary or intravenous administration of Escherichia coli endotoxin. Treatments were 1) Hank's balanced salt solution infusion in two contralateral quarters (control), 2) E. coli endotoxin infusion in two contralateral quarters, and 3) intravenous infusion of E. coli endotoxin. Blood was sampled and rectal temperature was measured at 30-min intervals. Endotoxin treatment was at 0900 h and sampling continued until 1700 h. Serum prolactin, cortisol, and 13,14-dihydro-15-keto-prostaglandin F2 alpha were measured. A pyretic response was observed in intravenous and intramammary treatment groups after endotoxin treatment. Response peak was higher (41.1 vs. 40.3 degrees C) and occurred later (6 vs. 4.5 h posttreatment) in the intramammary than the intravenous treatment group. Significant prolactin peaks were observed also in intravenous and intramammary endotoxin treatment groups. Prolactin peaked higher (288 vs. 112 ng/ml) and occurred sooner (1 vs. 4 h posttreatment) in the intravenous than in the intramammary treatment group. Cortisol followed a trend similar to prolactin. Cortisol peaked higher (100 vs. 82 ng/ml) and sooner (2.5 vs. 4.5 h posttreatment) in the intravenous than in the intramammary treatment group. Concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha increased rapidly posttreatment in the intravenous group only.

Human recombinant interleukin-1 beta isolated from Escherichia coli by simple osmotic shock

A synthetic gene coding for the C-terminal 153 amino acids of the human interleukin-1 beta (IL-1 beta) was used to produce large quantities of recombinant IL-1 beta in Escherichia coli. The expression of the synthetic gene was under the control of an inducible promoter. The recombinant protein was released from the cells by an osmotic shock. This procedure did not lyse the cells. The IL-1 beta that represented 90% of the total extracted protein was purified to homogeneity by a single chromatographic step. Sequence analysis revealed a heterogeneous N-terminal sequence resulting from the cleavage of the N-terminal methionine in 50% of the molecules and of both the N-terminal methionine and alanine in the other 50%. This recombinant IL-1 beta had a specific activity of 1.3 x 10(8) international units per mg.

Behavioural and ECoG spectrum changes induced by intracerebral infusion of interferons and interleukin 2 in rats are antagonized by naloxone

Rat interferon, alpha-interferon, interleukin 2 and recombinant interleukin-2 injected into the third cerebral ventricle produced typical behavioural sedation and/or sleep and ECoG synchronization in rats while beta-interferon produced no behavioural sleep or ECoG synchronization. A slight sedation was observed after the largest dose of beta-interferon only. During sleep induced by lymphokines, a dose-dependent increase in total voltage power as well as in the 0.5-3, 4-7 and 12-16 Hz frequent bands was observed. Much smaller doses were required to produce similar behavioural and ECoG spectrum effects after infusion of interferons and interleukin-2 into the locus coeruleus. No significant behavioural and ECoG changes were obtained after infusion of the same doses of interferons and interleukin-2 into other areas of the brain (caudate nucleus, dorsal hippocampus, substantia nigra pars compacta, ventromedial hypothalamus). The behavioural and ECoG effects of alpha-interferon, rat interferon and interleukin-2 were blocked in animals pretreated with naloxone. These results are consistent with the hypothesis that the behavioural and ECoG effects of these lymphokines are mediated at locus coeruleus level by stimulation of opiate receptors.

The characterisation of equine interleukin-1

Equine interleukin-1 has been produced from peripheral blood monocytes by stimulation with E. coli lipopolysaccharide. Sephacryl S200 gel filtration revealed a molecular weight of 17-18 kD. Chromatofocusing of the 17-18 kD peak identified four active fractions. Two major peaks were detected at pH 6.7 and pH 7, with smaller peaks at pH 6.3 and pH 5.9. The pI 7 molecule is probably the equine form of IL-1 beta.

Interferon gamma drastically modifies the regulation of interleukin 1 genes by endotoxin in U937 cells

IL-1 alpha, IL-1 beta, and tumor necrosis factor alpha (TNF-alpha) gene expression is induced by LPS (endotoxin) in monocytes/macrophages and in some monocytic cell lines. IFN gamma and 1 alpha,25-dihydroxyvitamin D3 (1,25[OH]2D3) are important macrophage-activating factors. They induce changes in the human monocyte cell line U937 that reflect cellular differentiation. We have studied the effect of IFN-gamma and of 1,25(OH)2D3 on the expression of IL-1 and TNF-alpha messenger RNA in response to LPS. The induction of these genes by LPS is immediate and transient, with a maximum in 3 h. Preincubation of the cells with IFN-gamma or with 1,25(OH)2D3 increases these mRNA responses to LPS about fourfold. More importantly, cells exposed to IFN-gamma for 72 h exhibit a drastically different and unexpected pattern of IL-1 alpha and IL-1 beta gene response to LPS. Instead of the normal transient response, one then observes a sustained increase in IL-1 alpha and IL-1 beta gene expression over at least 16 h after LPS stimulation. This was measured both at the level of mRNA and by direct transcription assays (run-off). This striking effect of IFN-gamma on the kinetics of IL-1 gene response does not apply to the TNF-alpha gene. Interestingly, 1,25(OH)2D3, which shares with IFN-gamma a number of important effects on monocytes/macrophages, does not affect the kinetics of IL-1 gene response to LPS. In view of the biological relevance of endotoxin as a macrophage activator, the potential clinical implication of this prolonged induction of IL-1 gene expression is discussed.

Effect in vitro of a bacterial extract (OM-89) on interleukin 1 and interleukin 2 production by peripheral blood mononuclear cells from healthy subjects and rheumatoid arthritis patients

The effect of a lyophilized extract from Escherichia coli strains (OM-89) on interleukin 1 and interleukin 2 production was studied by using peripheral blood mononuclear cells (PBMC) from healthy volunteers and from patients suffering from rheumatoid arthritis (RA) since, in this autoimmune disease, an abnormal cytokine network has been already described. The secretion of interleukin 1 (IL-1) was investigated in supernatants of monocytes purified by adherence, and measured by the C3H/HeJ thymocyte co-mitogenic assay. OM-89 was able to induce the secretion of IL-1 by normal and RA monocytes to about half of the level reached when the same cells were stimulated by lipopolysaccharide. The production of interleukin 2 (IL-2) was investigated in supernatants of PBMC, stimulated or not by phytohaemagglutinin (PHA) and mixed or not with various concentrations of OM-89. The level of IL-2 in supernatants, as measured by the stimulation of the CTLL2 murine cell line, was lower in RA supernatants than in control ones. In the presence of PHA and OM-89, the IL-2 production was enhanced and normalized in supernatants from RA patients. Such data may help to explain the clinical improvement previously reported in RA patients orally treated with OM-89.

Production of interleukin-1 (IL-1) and a specific IL-1 inhibitor during human monocyte-macrophage differentiation: influence of GM-CSF

Mononuclear phagocytes release several factors involved in host defense and inflammation. Of these, interleukin-1 (IL-1) has multiple biological activities which are controlled at different levels including modulation of gene expression, protein synthesis or secretion, and interaction with inhibitors. We have investigated the production of IL-1 alpha and beta as well as the production of a specific IL-1 inhibitor (IL-1 INH) during the in vitro maturation of human monocyte-macrophages. Highly purified monocytes isolated by counterflow centrifugal elutriation were cultured up to six weeks, producing high levels of IL-1 alpha and beta during the first week of culture. Shortly after the first week bioactivity of IL-1 decreased, preceding a decrease of IL-1 immunoreactivity. In contrast, IL-1 inhibitory activity reached a peak during the third week and remained detectable up to six weeks. Granulocyte-monocyte-colony-stimulating factor GM-CSF increased the production of IL-1 INH by approximately 20%, but did not affect IL-1 production. The IL-1 INH, apparent molecular weight approximately 23 kD, blocks the binding of [125I]IL-1 alpha to its receptor. The balance between the production of IL-1 and its antagonist may be important for the regulation of the immune response and chronic inflammation during pathological processes.

Immunomodulators and feeding regulation: a humoral link between the immune and nervous systems

Cells of the nervous and immune systems have specific receptors for humoral substances that originate in both systems. These elements establish a bidirectional information exchange network between the nervous and immune systems. In particular, neuroregulators (neurotransmitters and neuromodulators) can modulate specific immune system function(s) and immunoregulators (immunomodulators) can modulate specific nervous system function(s). Modulation of immune functions by neuroregulators has been receiving considerable attention; however, modulation of nervous system functions by immunomodulators has been little studied. The presence of immunomodulators in the brain and cerebrospinal fluid may represent local synthesis by astrocytes, microglia, endothelial cells, intrinsic macrophages and blood-derived lymphocytes which cross the blood-brain barrier, or the concentration of substances derived from the peripheral blood. Acute and chronic inflammatory processes, malignancy, and immunological reactions stimulate the synthesis and release of immunomodulators in various cell systems. These immunomodulators have pivotal roles in the coordination of the host defense mechanisms and repair and induce a series of endocrine, metabolic, and neurologic responses. This paper focuses on the effects of immunomodulators (interleukins, tumor necrosis factor, tuftsin, platelet activating factor, and others) on the central nervous system (CNS), in particular, on feeding regulation. It is proposed that an immunomodulatory system regulates food intake by a direct action in the CNS through a specific neuro-immuno interaction. This regulatory system may be operative during acute and chronic disease.

The metabolism and immunology of bone

Many cells and their cytokines produce a significant effect on bone metabolism. Bone matrix synthesis is a function of the osteoblast (Fig 1), influenced directly by numerous local and systemic factors (Tables 1 and 2). Locally synthesized factors such as SGF, BMP, and BDGF may be particularly important in stimulating new bone formation at sites of bone resorption or following bony injury. Of the systemic factors, GH; somatomedin C (IGF-1); high concentrations of insulin, testosterone, PDGF and TGF beta; and low concentrations of PGE2 and IL-1 appear to stimulate bone formation in vitro. These latter factors may be more important in maintaining skeletal growth and bone mass. Bone resorption by osteoclasts (Figs 2 and 3) is also controlled by the osteoblast, as this cell produces a leukotriene-dependent polypeptide that stimulates osteoclastic bone resorption. Osteoblasts cover the periosteal and endosteal bone-surfaces and limit exposure of the underlying bone to osteoclasts. PTH, vitamin D, PGE2, and other systemic factors interact directly with the osteoblast, not the osteoclast. Surface receptor binding of PTH increases intracellular cAMP and calcium and results in release of the factor that stimulates osteoclastic bone resorption. PGE2 induces osteoblasts to activate osteoclasts and is a major controlling factor in bone metabolism; the osteoblast produces PGE2, which can then modify osteoblastic function by positive feedback. Although low concentrations of PGE2 stimulate bone formation, higher concentrations promote osteoblast-mediated bone resorption. Furthermore, many of the systemic factors stimulate bone resorption via a PGE2-associated mechanism. Immune cytokines also appear to exert a profound influence on bone metabolism. INF-gamma inhibits osteoclastic resorption, whereas IL-1, TNF, and LT strongly stimulate bone resorption. However, low concentrations of IL-1 paradoxically result in stimulation of bone formation. These cytokines, particularly in various combinations, may prove extremely important in understanding and treating the bone loss associated with malignancies, osteoporosis, and rheumatoid arthritis.

In vitro and in vivo association of transforming growth factor-beta 1 with hepatic fibrosis

Despite extensive efforts, little progress has been made in identifying the factors that induce hepatic fibrosis. Transforming growth factor-beta (TGF-beta) has been shown to enhance collagen production, therefore its role in hepatic fibrosis was investigated. Treatment of cultured hepatic cells with TGF-beta 1 increased type I procollagen mRNA levels 13-fold due to post-transcriptional gene regulation. When two animal models of hepatic fibrosis, murine schistosomiasis and CCl4-treated rats, were examined, they both exhibited increased levels of TGF-beta 1 gene expression at times that somewhat preceded the increase in collagen synthesis. In contrast, in murine schistosomiasis, mRNA levels of tumor necrosis factor and interleukin-1 peaked early in the fibrogenic process. Immunohistochemical analysis showed TGF-beta 1 to be present in normal mouse liver and to be markedly increased in mice infected with schistosomiasis. TGF-beta 1 appeared in the hepatic parenchyma, primarily in hepatocytes. These findings strongly suggest a role for TGF-beta 1 in a pathophysiological state.

Temperature and metabolic changes in rats after various doses of tumour necrosis factor alpha

1. Sub-lethal doses of recombinant of tumour necrosis factor alpha (TNF alpha) were administered i.v. to young conscious male Wistar rats. Temperature changes and alterations in serum zinc and albumin concentrations and weight and composition of liver, kidney, spleen, tibialis muscle and skin were measured. Temperatures were monitored for 8 h and tissue parameters 8 and 22 h post-injection. 2. Doses above 10 micrograms/kg caused fevers of increasing magnitude and duration with latencies of 2 h. At doses of 200 micrograms/kg or more fevers were preceded by a fall in rectal temperature of up to 1.1 degrees C. 3. Weight loss by skin and tibialis and gain by liver occurred 22 h post-injection. Spleen and kidney weight and zinc and spleen protein contents were unaffected. Serum albumin and zinc fell 22 and 8 h after injection respectively. Liver zinc was elevated at both times and inversely correlated at 8 h with serum values. A degree of dose dependence of zinc and albumin changes existed. A gain in protein was evident in liver 8 h post-injection and a loss by muscle at 22 h. Paradoxical effects were observed in skin protein concentration. 4. TNF alpha mimicked many of the metabolic effects of E. coli endotoxin reported in the literature and showed similar effects to those described for interleukin 1 (IL1).

Interleukin-1 interaction with neuroregulatory systems: selective enhancement by recombinant human and mouse interleukin-1 of in vitro opioid peptide receptor binding in rat brain

Interleukin-1 (IL-1) exerts a wide variety of biological effects on various cell types and may be regarded as a pleiotropic peptide hormone. Biological evidence suggests that IL-1 participates in the modulation of central nervous system physiology and behaviour in a fashion characteristic of neuroendocrine hormones. In this investigation, recombinant (r) human (h) IL-1 and r mouse (m) IL-1 were examined for their modulation of opioid peptide receptor binding in vitro. Experiments were performed on frozen sections of rat brain. Receptor binding of radiolabeled substance P and of radiolabeled neurotensin were not significantly affected by the presence of rIL-1s. Recombinant IL-1s, however, significantly enhanced specific binding of 125I-beta-endorphin (125I-beta-END) and of D-ala2-(tyrosyl-3,5-3H)enkephalin-(5-D-leucine) (3H-D-ALA), equipotently and in a concentration-dependent manner with maximal activity occurring at a concentration of 10 LAF units/ml. The increased binding of 125I-beta-END and 3H-D-ALA was blocked steroselectively by (-)-naloxone and by etorphine, suggesting detection of opiate receptors. In addition, brain distribution patterns of receptors labeled in the presence of rIL-1s corresponded to patterns previously published for opiate receptors. Autoradiographic visualization of receptors revealed that rIL-1s in the different areas of the brain exert their effect on opioid binding with comparable potencies. The data suggest that certain central nervous system effects of IL-1s may be mediated by their selective interaction with opiatergic systems at the receptor level.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth factors, feeding regulation and the nervous system

A variety of growth factors and their receptors are present in the nervous system. Growth factors can modulate specific nervous system functions others than those related to growth, development, and tissue repair. The presence of growth factors in the brain and cerebrospinal fluid is the result of local synthesis (by neuronal, glial, vascular, and mononuclear phagocyte components), and uptake from the peripheral blood through the blood-brain barrier (in specific cases) and circumventricular organs. This paper focuses on the effects of a heterogeneous group of growth factors (acidic and basic fibroblast growth factors, insulin-like growth factors, epidermal growth factor, platelet-derived growth factor, interleukin-1 and others) on the central nervous system (CNS), in particular, on feeding regulation. Recent evidence supporting participation of growth factors in the regulation of feeding by a direct action at the level of the CNS is reviewed. Various growth factors have the ability to suppress short- and long-term food intake (FI), whereas others affect only short-term FI, or do not affect FI. Acute and chronic pathological processes stimulate the synthesis and release of growth factors in various cellular systems, and monitoring of growth factors by the CNS could be part of the regulatory signals that induce FI suppression frequently accompanying acute and chronic disease. Thus, it is proposed that a system regulating FI through growth factor-dependent mechanisms may be operative during specific physiological or pathological conditions.

Human hemopoietic growth factors

Hematopoiesis is regulated by a complex network of soluble stimulators and inhibitors, as well as by cellular interactions in the bone marrow microenvironment. Progress in molecular biology and protein biochemistry has provided a number of hemopoietic growth factors that are now available in large quantities for in vitro and in vivo studies. Several of them seem to hold great promise for patients suffering from insufficient hematopoiesis of various causes. This review focuses on new developments in the understanding of hemopoietic growth factors activity, and on recent clinical data.

Mechanism of anaemia in rheumatoid arthritis: demonstration of raised interleukin 1 beta concentrations in anaemic patients and of interleukin 1 mediated suppression of normal erythropoiesis and proliferation of human erythroleukaemia (HEL) cells in vitro

The pathogenesis of the anaemia associated with rheumatoid disease is unclear. It has previously been shown that the degree of the anaemia correlates with the severity of the inflammatory disease and that serum from patients with arthritis inhibits erythropoiesis. This study was designed to examine whether interleukin 1 could be a mediator of the anaemia in rheumatoid arthritis. Radioimmunoassay of interleukin 1 beta in serum showed that patients with rheumatoid arthritis and associated anaemia had significantly higher interleukin 1 beta concentrations than patients with rheumatoid arthritis without anaemia. Pure recombinant human interleukin 1 alpha and interleukin 1 beta, in concentration ranges similar to those found in the arthritic patients, markedly suppressed the colony formation of the erythroid, but not the granulocyte-macrophage progenitor cells in cultures of normal bone marrow. Natural human interleukin 1 and recombinant interleukin 1 beta, but not interleukin 1 alpha, suppressed in a dose dependent manner the proliferation of the human erythroleukaemia cell line (HEL) in cultures, suggesting that the interleukin 1 effect is a direct one. The results show that interleukin 1 is a humoral inhibitor of erythropoiesis and suggests that interleukin 1 is involved in the development of anaemia in association with rheumatoid arthritis.

Production of an interleukin-1 inhibitor by cell line P388D1 murine macrophages stimulated with Haemophilus actinomycetemcomitans lipopolysaccharide

Murine macrophages of the P388D1 cell line stimulated with lipopolysaccharide (LPS) from Haemophilus actinomycetemcomitans Y4 released an interleukin-1 (IL-1) inhibitor, as well as IL-1. Maximal IL-1 activity in culture supernatants was detected after 24 h of culture. On the other hand, IL-1 inhibitor activity reached a maximum level after 72 h of culture. An IL-1 inhibitor was partially purified from the culture supernatant of P388D1 cells stimulated with Y4 LPS for 72 h by ammonium sulfate precipitation, followed by Sephacryl S-200 gel chromatography. A 160-kilodalton peak inhibitory to IL-1 and a 14-kilodalton peak showing IL-1 activity were separated by Sephacryl S-200 column chromatography. The partially purified IL-1 inhibitor significantly suppressed the proliferation of C3H/HeJ murine thymocytes that had been induced with murine and human IL-1 in the presence of a submitogenic dose of concanavalin A. The IL-1 inhibitor more strongly suppressed human recombinant IL-1 beta than human recombinant IL-1 alpha. This inhibitory activity of the partially purified preparation was unaffected by the presence of trypsin inhibitor and the protease inhibitor aprotinin. The IL-1 inhibitor did not exhibit either IL-2 or IL-2 inhibitor activity. The inhibitor suppressed C3H/HeJ thymocyte proliferation induced by IL-1 in the presence of a saturated concentration of IL-2 instead of a suboptimal concentration of concanavalin A. These results indicate that prolonged culture of Y4 LPS-stimulated murine macrophages releases a specific inhibitor of IL-1.

Modifications of plasma lipids, lipoproteins and apolipoproteins in advanced cancer patients treated with recombinant interleukin-2 and autologous lymphokine-activated killer cells

Intravenous injection of recombinant interleukin-2 (r-Met-hu-IL-2(Ala-125] and LAK cells induced dramatic changes of lipoproteins in 12 patients with advanced cancer. After r-IL-2 injection (1) total cholesterol was reduced by 47% as a mean, LDL-cholesterol by 62%, HDL-cholesterol by 77%; (2) the triglyceride/cholesterol ratio was greatly increased (352%); (3) apolipoproteins B, A-I and A-II showed a mean reduction of 26%, 55% and 51%, respectively; and (4) very low density lipoproteins relatively increased, and HDL were separated into two definite fractions (I and II). LAK cell administration accentuated all the above effects and in most patients, HDL-fraction I almost completely disappeared. An action on hepatic synthesis of acute phase proteins is pointed out by the increase in C-reactive protein and apolipoprotein S concentrations contrasting with an unexpected reduction of fibrinogen. Surprisingly the drastic changes caused by treatment were quickly and completely reversible.

Human testis cytosol and ovarian follicular fluid contain high amounts of interleukin-1-like factor(s)

Human testicular cytosol and ovarian follicular fluid were analyzed for the presence of interleukin-1 (IL-1)-like factors. Both the follicular fluid and testis cytosol preparations exhibited significant IL-1-like activity as determined by the murine thymocyte proliferation bioassay. The dose-response lines obtained with the gonadal preparations were parallel to each other and to those obtained with monocyte-derived IL-1 and the activity of the gonadal IL-1 could be neutralized by specific IL-1 antibodies. After gel chromatography of human follicular fluid (hFF) and human testis cytosol (hTC) proteins, IL-1 activity was found in the molecular weight region between 30 and 50 kilodaltons (kDa). Chromatofocusing of IL-1 from hFF and hTC revealed that the major part of IL-1 in both cases exhibited similar charge properties (pI less than 6.0). However, two extra peaks (pI 7.0 and greater than 9.0, respectively) were observed in hFF preparations. After isoelectrofocusing (IEF), IL-1 activity of hFF was also found in two different pH regions; a broad area of activity was localized between pH 5.5 and 7.0, while a sharp peak was observed with an approximate pI value of 9.5. Re-chromatofocusing or IEF of alkaline IL-1-like activity resulted in a heterogeneous profile of IL-1-like activity suggesting that the alkaline material may represent either a precursor or an aggregated form of the acidic IL-1. None of the IL-1 peaks obtained from hFF or hTC exhibited IL-2 activity as assessed in a specific IL-2 bioassay. The results of the present study indicate that both gonads may produce high amounts of IL-1-like factor(s) which might play a regulatory role in normal gonadal function.

Interleukin 6 is involved in interleukin 1-induced activities

Human monocytes produce a number of soluble mediators involved in regulation of inflammation and lymphocyte growth and differentiation such as interleukin 1 (IL 1) and tumor necrosis factor. Recently, the cDNA of another monocyte-derived factor, interleukin 6 (IL 6), was cloned. Herein we show that purified E. coli-derived recombinant IL 6 (rIL 6) is as active as IL 1 in the thymocyte assay. In addition, IL 1 and IL 6 synergize strongly in stimulating thymocyte proliferation. Another property shared by IL 1 and IL 6 is their pyrogenicity. Human rIL 6 induces a monophasic fever after i.v. injection into rabbits. Together with the observation that IL 1 induces IL 6 in a variety of cells including thymocytes, our data suggest that IL 6 is involved in many of the pleiotropic effects of IL 1.

Tumor necrosis factor and interleukin-1 beta: suppression of food intake by direct action in the central nervous system

Intracerebroventricular microinfusion of recombinant human tumor necrosis factor (rhTNF) and recombinant human interleukin-1 beta (rhIL-1 beta) suppressed food intake in rats. Central infusion of heat-inactivated rhTNF and rhIL-1 beta, bovine serum albumin, heparin or transforming growth factor-beta had no such effect. Central infusion of rhIL-1 beta did not affect the dipsogenic response to central administration of angiotensin II. Peripheral administration of rhTNF and rhIL-1 beta in doses equivalent to or higher than those administered centrally had no effect. Electrophoretically applied rhTNF and rhIL-1 beta specifically suppressed the activity of glucose-sensitive neurons in the lateral hypothalamic area. Glucose-insensitive neurons were little affected. The results suggest that TNF and IL-1 beta act directly in the central nervous system to suppress feeding, and this effect may be operative during acute and chronic disease.

Homologous human macrophage hybridomas that produce a novel cytotoxic factor in their culture supernatants

Homologous human macrophage hybridoma cell lines were obtained by somatic cell fusion between peripheral blood monocyte-derived macrophages and a subclone of the myelomonocytic cell line, U937-F9. The hybridoma cell lines grown in vitro for more than a year were confirmed by manifestations of phagocytosis, adherence, nonspecific esterase, acid phosphatase, chromosome numbers and other cell surface antigens. Cell surface antigens on hybridomas were detected by flow cytometry analysis with monoclonal antibodies. With interclonal differences, a typical phenotype of hybridoma cells was CDw14+, OKM5+, Mac-1+ (equivalent to OKM1 and Mol), OKT9+, HLA-DR- and CD20+. After stimulation with lipopolysaccharide and calcium ionophore A23187, culture supernatants of clones c18A and c29A showed cytotoxic activity against human melanoma A375 Met-Mix and other cell lines which were resistant to the tumor necrosis factor, lymphotoxin and interleukin 1. This cytotoxic factor was found to be distinct from the tumor necrosis factor, lymphotoxin and interleukin 1 using the anti-tumor necrosis factor, anti-lymphotoxin and anti-interleukin 1 antisera.

Chemical and neuronal control of feeding motivation

The sugar acids, 3,4-dihydroxybutanoic acid gamma-lactone, 2-buten-4-olide and 2,4,5-trihydroxy pentanoic acid gamma-lactone which were found in blood modulate feeding behavior of rats by modifying neuronal activity in the lateral hypothalamic area [LHA] and the ventromedial hypothalamic nucleus [VMH]. The former two act as satiety substances and the latter as a hunger substance. Detection of changes in the concentration of these sugar acids in the blood by glucoreceptor neurons in the VMH and glucose-sensitive neurons in the LHA is important in the regulation of feeding. A phasic increase in fibroblast growth factor [FGF] was found in the cerebrospinal fluid after feeding. Cerebroventricular application of acidic FGF suppresses food intake. Interleukin-1 beta and tumor necrosis factor which have a quite similar amino acid sequence as FGF also suppress feeding. The neuronal mechanism of satiety action of these polypeptides is the same as the sugar acids. The results indicate that these endogenous substances participate in the central regulation of feeding. Hierarchial organization of the endogenous chemical information processing system which is composed of the viscera, medulla, hypothalamus and the cortex is discussed.