Interleukin 1 from human leukemic monocytes

Determination of haptoglobin expression in IL-6 treated HepG2 cells by ELISA and by RNA hybridization--evaluation of a quantitative method to measure IL-6

Interleukin-6 (IL-6) is known to be an important modulator of acute phase (AP) protein expression in hepatocytes both in vivo and in vitro. In the present study the inducing activity of IL-6 on the expression of the AP protein haptoglobin (HP) by the human hepatoma cell line HepG2, has been evaluated. HP mRNA inducibility was analysed by Northern and slot-blot hybridization, while HP protein was detected by means of an ELISA procedure. A dose-response relationship from 0.3 to 4.8 ng/ml of a human recombinant IL-6 preparation derived from a Chinese hamster ovary (CHO) cell line was observed after 48 h of treatment. Comparable results were obtained by analysing both HP mRNA expression and HP protein secretion. Detectable induction of HP protein secretion was observed with as little as 25 pg/ml of IL-6. The effect of IL-6 was potentiated by dexamethasone, while an inhibition on HP mRNA inducibility could be prevented by lowering the foetal calf serum (FCS) concentration to 1%. Preliminary data indicate that neither IL-1 beta nor TNF-alpha were able to induce significantly HP mRNA expression and protein secretion. The activity ratio between two IL-6 preparations (from CHO and E. coli cells) obtained with a conventional IL-6 bioassay (i.e., T1165 cell growth assay) was comparable to that obtained in the induction of HP expression. The nominal specific activity of the CHO-derived IL-6 was two to three times higher with both responses.

Anti-tumour effects of interleukin 1 beta: in vivo induction of immunity to B16 melanoma, a non-immunogenic tumour

The anti-tumour properties of interleukin 1 beta (IL-1 beta) were examined using an intradermal B16 murine melanoma surgical model. B16 cells were injected intradermally on the right ventral side and surgery was performed on days 10-20 to remove the primary tumours. IL-1 beta or vehicle was administered prior to surgery for 5-7 consecutive days. In mice which received only injections of vehicle, survival ranged between 0 and 30% when measured on day 120 after implantation of B16 cells. Mice died of metastases and growth of B16 cells in the thoracic lymph nodes. When mice without metastases were rechallenged with viable B16 cells, only one out of 22 mice (5%) failed to develop tumours. No significant immunity to B16 cells was detected in this group of mice. In contrast, in mice which received injections of IL-1 beta, survival ranged between 70-100% on day 120 after implantation of B16 cells. When IL-1 beta treated mice were rechallenged with viable B16 cells on day 120, 20 out of 32 (63%) mice failed to develop B16 tumours suggesting that some of these mice had immunity to B16 melanoma cells. Moreover, mice with immunity to B16 cells did develop tumours when injected with another syngeneic tumour, MCA 105. In vitro specific immune responses were also demonstrated in spleen cells and sera from mice treated with IL-1 beta, but not in the spleen cells or sera of mice that received only vehicle.(ABSTRACT TRUNCATED AT 250 WORDS)

High in vitro endotoxin responsiveness of macrophages from an endotoxin-resistant wild rodent species, Sigmodon hispidus

It has been reported that macrophages primarily mediate endotoxin shock and cell death by synthesizing and releasing cytokines, largely tumor necrosis factor (TNF) and interleukin-1 (IL-1). However, macrophages from some laboratory mouse strains such as C3h/HeN are unresponsive to endotoxin both in vivo and in vitro. We found members of a wild rodent species, Sigmodon hispidus, to also be extremely resistant to bacterial endotoxin challenge. Intravenous administration of up to 100,000 micrograms/kg body mass of Escherichia coli O26:B6 endotoxin did not cause lethality in adult S. hispidus. In contrast to the endotoxin-resistant mouse strain, peritoneal macrophages derived from S. hispidus were responsive to in vitro endotoxin challenge as measured by high levels of TNF and IL-1 activity in supernatants of macrophage cultures. Thus, in vitro macrophage responsiveness to endotoxin does not always indicate high host sensitivity to endotoxin challenge.

Effects of tumour necrosis factor-alpha (TNF-alpha), IL-1 beta and monocytes on lymphokine-activated killer (LAK) induction from natural killer (NK) cells and T lymphocytes

Roles of monocytes and cytokines were investigated on LAK induction from T and NK cells. Monocytes augmented more T-LAK induction than did NK-LAK. Expression of IL-1 beta, TNF-alpha and interferon-gamma (IFN-gamma)-mRNA and their cytokine production were superior in NK cells compared with T cells in parallel with their LAK activities. An increase of TNF-alpha, IL-1 beta and IFN-gamma production was induced by co-culturing NK or T cells with autologous monocytes. The augmentation of T cell cytokine production and T-LAK activity by monocytes was more prominent than that of NK cells. TNF-alpha and IL-1 beta were generated 24 h after IL-2 stimulation, and these cytokines were able to almost substitute for monocytes in LAK induction. Conversely, LAK induction was almost completely suppressed by both anti-IL-1 beta and anti-TNF-alpha antibodies, if they were added within 24 h after the start of the LAK induction. IFN-gamma, which was produced at a later stage, scarcely affected LAK induction in spite of the cooperation with TNF-alpha. The results obtained indicate conclusively that the superiority of NK-LAK depends on their superior productivity of both IL-1 beta and TNF-alpha, and that the up-regulation of LAK induction by monocytes is largely due to the enhanced generation of both cytokines.

Changes in plasma cytokines associated with peripheral nerve injury

Plasma levels of interleukins 1, 2, 4 and 6 and tumor necrosis factor (TNF) were measured from 0 to 30 days in rats after a unilateral crush of the sciatic nerve at the level of the sciatic notch and after sham operations without nerve crush. Interleukin-6 was observed to peak and return to baseline levels within 24 h and remained at baseline for the duration of the experiment. An initial sharp rise in interleukin-1 and TNF was observed in all animals 1-2 days after the operation. A transient increase in interleukin-1 and TNF was also observed only in nerve-injured animals between 10 and 14 days after injury. A large increase in interleukin-2 appeared only in nerve-injured animals beginning at 11 days after injury and remained elevated for the remaining study period. No alterations in plasma interleukin-4 were observed at any time point. The experiments provide preliminary evidence for significant trauma-induced alterations in plasma cytokines which could provide a basis for some of the diffuse responses of peripheral neurons to trauma. The biphasic nature changes in plasma cytokines suggest that the immune system may participate in tissue reactions involved in the recovery from nerve injury.

Growth-stimulating phase of macrophage response to activation: the phenomenon and its implications for tumour growth and immunotherapy

The dynamics of growth-stimulating and cytotoxic activity of mouse peritoneal macrophages (PMo) in response to in vivo and in vitro bacillus Calmette-Guérin (BCG) or bestatin treatment was studied. It was shown that BCG and bestatin induce cytotoxicity in PMo, and that after the cytotoxic response strong growth-stimulating activity develops. PMo, rendered cytotoxic in vivo and afterwards cultivated in vitro, displayed the same switch from a cytotoxic to a growth-stimulating phase. These results suggest that the growth-stimulating phase is the obligatory PMo response to biological response modifiers (BRM) at least to BCG and bestatin. The growth rate of tumours, transplanted into mice during the cytotoxic phase of the response to BCG, was suppressed, whereas tumours transplanted during the growth-stimulating phase were stimulated. It appears that the development of a growth-stimulating phase after the cytotoxic phase of response to activation by BRM could be one of the reasons for the limited effectiveness of immunotherapy based on the application of macrophage activators.

Negative regulation of interleukin-1 in immune reactive cells

Interleukin-1 (IL-1) is an immunological regulator with a multitude of effects. Recently, IL-1 inhibitors from urine, monocytes, or monocytic cell lines have been described. We previously demonstrated an IL-1 inhibitor from human monocytes under immune complex or immunoglobulin stimulation. The present studies were initiated to determine the production of IL-1 inhibitor from human polymorphonuclear cells (PMN), B and T lymphocytes in response to certain stimuli using a murine thymocyte system responsive to IL-1. My results indicated that the inhibitor is constitutively present in PMN because unstimulated PMN supernatants also show inhibitory activity. B and T lymphocytes can not produce IL-1 inhibitor under zymosan, immunoglobulin, or immune complex stimulation. The presence of this PMN inhibitor may also be important in the negative regulation of IL-1.

Macrophage activation by polymeric nanoparticles of polyalkylcyanoacrylates: activity against intracellular Leishmania donovani associated with hydrogen peroxide production

Nanoparticles of polyalkylcyanoacrylates (PACA) can be useful carrier for the targeting of antileishmanial drugs into macrophages and also possess significant antileishmanial activity by themselves. No significant difference in antileishmanial activity could be detected between nanoparticles of five PACAs with differing alkyl side chains, suggesting that the main degradation products of PACA are not involved in their antileishmanial action. The effect of polyisohexylcyanoacrylate (PIHCA) on the induction of the respiratory burst in a macrophage-like cell line (J774G8) was assessed in non-infected macrophages and in macrophages infected with amastigotes of Leishmania donovani infantum, by measuring nitroblue tetrazolium (NBT) reduction and hydrogen peroxide production. Phagocytosis of PIHCA nanoparticles led to a respiratory burst, which was more pronounced in infected than in uninfected macrophages. The production of reactive oxygen intermediates associated with the respiratory burst was inhibited by addition of superoxide dismutase and catalase to the cell suspensions. The addition of catalase to the culture medium together with PIHCA nanoparticles significantly reduced the antileishmanial activity of PIHCA. Moreover PIHCA nanoparticles did not induce interleukin-1 release by macrophages. It is suggested that the antileishmanial action of PIHCA and other PACA nanoparticles results from the activation of respiratory burst in macrophages.

Hypersensitivity pneumonitis: whole Micropolyspora faeni or antigens thereof stimulate the release of proinflammatory cytokines from macrophages

Hypersensitivity pneumonitis (HP) is an allergic granulomatous interstitial lung disease resulting from a reaction of selected individuals to repeated inhalations of certain antigens. HP is characterized by chronic inflammation, and the development of the disease seems to be immunologically mediated. In farmer's lung, the source of provoking antigen has been found to be actinomycetes such as Micropolyspora faeni. In this study, we show that M. faeni, or antigens thereof, stimulate strong release of proinflammatory cytokines from blood monocytes and alveolar macrophages obtained from nonfarmer volunteers and naive mouse peritoneal macrophages. Interleukin-1 (IL-1) was produced by human alveolar macrophages and murine peritoneal macrophages in response to whole M. faeni and antigens thereof. IL-1 activity was detected in the supernatants at 12 h of incubation and was maximal by 24 to 36 h (200 to 400 U/ml of IL-1). A rabbit antiserum to IL-1 alpha and IL-1 beta neutralized the thymocyte-stimulating activity of the supernatants. Moreover, M. faeni (1 to 100 micrograms of antigen) elicited a strong secretion of tumor necrosis factor-alpha (TNF-alpha) from human alveolar macrophages and monocytes as well as mouse peritoneal macrophages, where 1 micrograms of M. faeni elicited the secretion of approximately 100 U of TNF-alpha from 2 x 10(5) macrophages, and 100 micrograms stimulated the release of approximately 1,000 U of bioactive TNF-alpha. One particle of whole M. faeni per cell was sufficient to induce copious release of TNF-alpha from macrophages or monocytes (100 U of bioactive TNF-alpha; 1,000 pg/ml of antigenic TNF-alpha as seen by radioimmunoassay). Both IL-1 and TNF-alpha productions stimulated by M. faeni were not abrogated by inclusion of polymyxin B. We propose that the direct stimulation of cytokines by M. faeni or antigens thereof may play an important role in HP.

In vivo inhibition of tumor growth of B16 melanoma by recombinant interleukin 1 beta. II. Mechanism of inhibition: the role of polymorphonuclear leukocytes

Recombinant human interleukin 1 beta (IL 1 beta) inhibits growth of B16 melanoma in syngeneic C57BL/6 mice in a dose-dependent manner when given intratumorally, intradermally, or intramuscularly over a period of 5 to 7 days. Inhibition of tumor growth was rapid and measurable within 3 days after the initial injection and occurred regardless of the route of injection. However, only intratumoral (ITU) injections of IL 1 beta resulted in greater than 90% inhibition in tumor growth. This enhanced inhibition of tumor growth was not dependent on T or NK cells since inhibition of tumor growth occurred in nude and Beige mice. Also, a profound lymphopenia occurred in mice receiving IL 1 beta. Inhibition of tumor growth did correlate with an increase in the number of polymorphonuclear leukocytes (PMN's) in the circulation. However, only ITU injections of IL 1 beta increased the number of PMN's within the tumors. IM injections of IL 1 beta, while increasing the number of PMN's in the circulation, did not increase the influx of PMN's into the tumors. Furthermore, the transfer of PMN's directly into B16 tumors caused a 49% reduction in tumor growth without the presence of IL 1 beta. These results suggest that in vivo, PMN's may effectively control the growth of tumors and that IL 1 beta may increase this effectiveness by increasing the number of PMN's in the circulation and by locally stimulating the production of chemotactic factors for PMN's within the tumor.

Chlamydia trachomatis-induced production of interleukin-1 by human monocytes

Human diseases caused by the intracellular bacterium Chlamydia trachomatis include genital tract infections and blinding trachoma. Chlamydial infections are characterized by chronic inflammation and scarring, and development of such complications is thought to be immunologically mediated. In this study, we show that coculture of C. trachomatis (serovar L2) with human blood monocytes induced the production of interleukin-1 (IL-1), an important mediator of inflammation, tissue remodeling, and scarring. IL-1 was produced in response to UV-inactivated elementary bodies containing from 0.1 to 50 micrograms of protein per ml, with a maximal response at 5 to 10 micrograms/ml. IL-1 activity was detected by 6 h of incubation and was maximal by 24 h. Peak levels were maintained throughout 96 h of incubation. Rabbit antibody to human IL-1(alpha + beta) effectively neutralized the thymocyte-stimulating activity of the supernatants. The apparent molecular weight of chlamydia-induced IL-1 was 16,000, as determined by gel filtration on a Bio-Gel P-60 column. Isoelectric focusing yielded two peaks of activity, with pIs of 5.5 and 6.9. Neutralization studies with antisera against human IL-1 alpha and IL-1 beta showed that the acidic and neutral peaks corresponded to IL-1 alpha and IL-1 beta, respectively, with IL-1 beta predominating. Heat-killed chlamydiae, which are not internalized by monocytes, were effective IL-1 inducers, indicating that phagocytosis was not required for IL-1 induction. Purified C. trachomatis lipopolysaccharide was also an effective IL-1 inducer, suggesting that the response to intact organisms may be largely a response to chlamydial lipopolysaccharide. Finally, purified chlamydial major outer membrane protein induced low but detectable IL-1 activity.

Two peaks of interleukin 1 expression in human leukocytes cultured with tobacco glycoprotein

We have previously shown that tobacco glycoprotein (TGP), a polyphenol-rich glycoprotein isolated from tobacco or from cigarette smoke, affects the immune system. In this study we show that TGP induces human PBL and adherent cells to produce IL-1 alpha and IL-1 beta. Two peaks of IL-1 activity were observed; one at 18-24 h, the second at 4-6 d after initiation of culture. A similar pattern was observed for the steady state level of IL-1 mRNA. These data suggest that the production of IL-1 by cells stimulated with TGP might be a factor in cardiovascular disease associated with cigarette smoking.

Stimulation of glycosaminoglycan synthesis in cultured human dermal fibroblasts by interleukin 1. Induction of hyaluronic acid synthesis by natural and recombinant interleukin 1s and synthetic interleukin 1 beta peptide 163-171

Hyaluronic acid (HA) is believed to play a critical role in wound healing and in morphogenesis. Factors controlling the production of HA by fibroblasts in normal and pathological states are not completely understood. In this report we have observed that natural human interleukin (IL-1)1 beta and human recombinant (hrIL)-1 alpha and beta are potent stimulators of HA production by fibroblasts in vitro. Hyaluronic acid is the major species of glycosaminoglycan (GAG) stimulated by IL-1 in fibroblasts. PGE2 does not appear to be involved directly in this IL-1 effect on fibroblasts, but stimulation of HA production by IL-1 is dependent on protein synthesis. The synthetic human IL-1 beta peptide 163-171 (Val-Gln-Gly-Glu-Glu-Ser-Asn-Asp-Lys), which has been previously shown to stimulate thymocyte proliferation but not fibroblast PGE2 production, is also able to stimulate fibroblast HA production. The synthesis and secretion of IL-1 by mononuclear phagocytes at sites of inflammation and immune reactions in vivo could potentially serve as a signal for fibroblasts to synthesize HA, which in turn could serve to facilitate and modulate reparative and immune processes by virtue of its ability to alter cell-cell, cell matrix, and cell-membrane receptor interactions.

Tumorigenicity and metastatic behavior in nude mice of two human squamous cell carcinoma lines that differ in production of the cytokine ETAF/IL-1

The purpose of these studies was to determine whether the production of the cytokine epidermal cell thymocyte-activating factor (ETAF) by human squamous cell carcinoma (SCC) cells correlated with their tumorigenicity and metastatic potential in athymic nude mice. Cells of the human SCC line A431 produced rapidly growing subcutaneous tumors, few experimental lung metastases, and low levels of ETAF activity in vitro. In contrast, cells of the SCC Colo-16 line produced slower growing subcutaneous tumors, high numbers of experimental lung metastases, and a high level of ETAF activity in culture supernatants. The apparent relationship between production of ETAF and experimental metastasis formation was not consistent. Clonal populations of the SCC A431 and Colo-16 were isolated in vitro. The clones of Colo-16 varied in their ability to produce experimental metastases and in production of ETAF in vitro. However, the levels of ETAF production did not correlate with the propensity of the SCC cells to produce experimental metastases. We conclude that while the growth and metastasis of human SCC in nude mice may benefit from production of the cytokine ETAF, the ETAF production per se is not invariably linked with the capability of the SCC cells to metastasize.

Muteins of human interleukin-1 that show enhanced bioactivities

Using recombinant DNA techniques, we have made a series of amino-terminal muteins of human interleukin-1 (IL-1). Two of the muteins demonstrated 4-7-fold increase in bioactivity as compared to that of the native IL-1. The enhanced biological potency coincides with an increase in both receptor binding affinity and in vivo tumor inhibitory activity. By site specific mutagenesis, we have shown that the arginine at the fourth position of IL-1 is one of the key residues in the function of IL-1. Circular dichroism studies of the amino-terminus analogs showed little structural rearrangement. The change in bioactivity might be due to a change in the stability of the muteins, in the side chain interactions with receptors or in the minor change in folding near the receptor binding site.

Ameboid microglia as effectors of inflammation in the central nervous system

Techniques for selective isolation, labeling, stimulation, and destruction of ameboid microglia allow study of some fundamental questions in neuroimmunology. Examination of surface morphology, proliferative capacity, and cytochemistry suggests that microglia are a class of brain mononuclear phagocytes distinct from blood monocytes, spleen macrophages, or resident peritoneal macrophages. Moreover, cultured ameboid microglia isolated from newborn brain can be induced to grow thin cytoplasmic projections several hundred microns in length; these process-bearing cells resemble a differentiated form of microglia found in adult brain. Ameboid microglia may contribute to brain inflammation by engulfing debris, by releasing cytotoxins, by killing neighboring cells, and by secreting astroglial growth factors. Importantly, ameboid microglia are closely tied to a network of immunomodulators that include colony-stimulating factors and Interleukin-1. The presence of activated microglia during normal embryogenesis and at sites of penetrating brain injury suggests that these cells serve as important effectors linking the immune system with growth and repair of the CNS.

Purification and characterization of human interleukin-1 beta expressed in recombinant Escherichia coli

The high-level expression of human interleukin-1 beta in Escherichia coli is described. The protein contributes about 12% of the total cell protein and is associated with the soluble cytoplasmic fraction of the cell. A method for the purification of the protein is given which is based on anion- and cation-exchange chromatographies. The isolated protein, shown to be homogeneous by several analytical methods, has been characterized by amino acid analysis, N- and C-terminal sequence analysis and analytical centrifugation. The protein is biologically active as demonstrated by two different in vitro assays, namely, the mononuclear cell factor (IL-1/MCF) assay and lymphocyte activating factor (IL-1/LAF) assay. The specific activities determined with the IL-1/MCF and IL-1/LAF assays, are 2 X 10(7) and 4 X 10(7) units mg-1, respectively.

Monocyte-conditioned medium, interleukin-1, and tumor necrosis factor stimulate the acute phase response in human hepatoma cells in vitro

Human hepatoma cells mimic the acute phase response after treatment with monocyte-conditioned medium. Levels of secreted fibrinogen, alpha-1 acid glycoprotein, C-reactive protein, haptoglobin, and the third component of complement were elevated compared with control levels after 48 h of incubation with conditioned supernatant medium from an enriched fraction of normal peripheral monocytes. Albumin levels declined and alpha-1 antitrypsin remained unchanged. Levels of specific mRNA were measured by hybridization to slot blots and Northern blots and changed in correspondence with protein alterations. Interleukin-1 and tumor necrosis factor stimulated the third component of complement, but did not elevate any other member of the acute phase group and were therefore only partially active in this system. The identification of an in vitro model of the human acute phase response will permit analysis of the molecular basis for coordinate regulation of this group of facultative genes.

Interleukin 1 of the central nervous system is produced by ameboid microglia

By screening specific populations of rat brain cells, we found that ameboid microglia secrete an 18 kD peptide with IL-1 biological activity. The IL-1 activity released by microglia was found to be identical to rat macrophage IL-1 on fractionation by gel filtration and high pressure liquid anion-exchange chromatography, and it was neutralized by an antiserum specific for murine IL-1. When added to astroglia grown in culture, microglial IL-1 increased the cell number of five- to sevenfold, and increased astroglial incorporation of [3H]thymidine by three- to fivefold. We propose that the proliferation of astroglia in specific brain regions may be regulated by the signaled release of IL-1 from activated microglial cells.

Proliferative signals for suppressor T cells. Helper cells stimulated with pokeweed mitogen in vitro produce a suppressor cell growth factor

To define molecular signals elaborated by inducer populations supporting growth or differentiation of T8+ cells, we collected supernatants of pokeweed mitogen (PWM)-stimulated cultures depleted of T8+ cells. When added to purified T8+ cells, these supernatants caused significant proliferation. PWM plus interleukin 2 (IL-2) in amounts equivalent to those in the supernatant could not reconstitute the response caused by the supernatant. T8+ cells activated by supernatants obtained from PWM-pulsed T4+ cells suppressed fresh PWM cultures. Although exhibiting little proliferation, T8+ cells cultured for 6 d in PWM plus IL-2 still suppressed a fresh PWM response. The supernatants therefore contain an additional T suppressor cell growth factor (TsGF). Elaboration of TsGF required radiosensitive T4+Leu8+ cells. Molecular weight determination by high performance liquid chromatography gave a single peak of TsGF activity at approximately 8,000. Finally, whereas TsGF in the absence of IL-2 could not support the proliferation of T suppressor cells, it did cause T8+ cells to become strongly IL-2 receptor-positive.