Production of interleukin-1-like cytokine by cultured rat glomerular macrophages.

Resident glomerular macrophages from normal rats were isolated and grown through long-term cultures in order to obtain confluent cell monolayers. These cells have a secretory function as revealed by the production of a cytokine with a molecular weight similar to interleukin-1 (IL-1). The demonstration that rat glomerular macrophages secrete an IL-1-like cytokine emphasizes the role of these cells in a number of glomerular secretory functions, including some which have been commonly attributed only to mesangial contractile cells.     

Synthesis of interleukin-1-like activity by normal rat chondrocytes in culture

Chondrocytes prepared from the articular cartilage of young rats synthesize and secrete an interleukin-1-like activity into the medium. The physical and biochemical properties of this IL-1-like activity are similar to macrophage-derived IL-1. Immunological studies suggest that this activity is related to IL-1 alpha. Isolated chondrocytes and those grown in culture can express Ia.     

Altered release of eicosanoids by rat alveolar macrophages during granulomatous pulmonary inflammation

Release of arachidonic acid metabolites (eicosanoids) by alveolar macrophages may be important in regulating pulmonary inflammatory reactions. The purpose of this study was to characterize eicosanoids released by rat alveolar macrophages during the evolution of experimentally induced pulmonary inflammation. Immunization with subcutaneous bacillus Calmette-Guerin (BCG) followed 2 wk later by intravenous BCG challenge resulted in mild granulomatous pulmonary inflammation for up to 30 days. At serial intervals, alveolar macrophages were lavaged from the BCG-treated rats as well as from control normal rats. Lavaged macrophages were cultured in vitro, and culture supernatants were assayed by radioimmunoassay for release of prostaglandin E2 (PGE2), Leukotriene B4 (LTB4), and thromboxane B2 (TXB2). Cells were cultured alone, or with added LPS or calcium ionophore A23187 to stimulate eicosanoid release. During BCG-induced inflammation, spontaneous release of PGE2 and LTB4 was unchanged, while spontaneous release of TXB2 was depressed acutely and then returned to control levels. The capacity of alveolar macrophages to release specific eicosanoids in response to an in vitro stimulus was dramatically altered during the course of BCG-induced inflammation. Stimulated release of PGE2 was transiently increased during acute lung injury, but stimulated release of LTB4 was significantly decreased at all stages of inflammation. Stimulated release of TXB2 was unchanged. These results indicate that during the course of granulomatous pulmonary inflammation there are dynamic changes in the profile of eicosanoids released by alveolar macrophages, both spontaneously and in response to in vitro stimulation. This alteration in the release of eicosanoids by alveolar macrophages may be an important factor in the resolution of pulmonary inflammation.     

Bleomycin-stimulated hamster alveolar macrophages release interleukin-1.

The capacity of alveolar macrophages (AM) of bleomycin-instilled hamsters to proliferate mouse thymocytes (interleukin-1 activity) and hamster fibroblasts (fibroblast proliferation (FP) activity was studied. Using bleomycin-instilled hamsters, the FP activity of AM culture supernatants was increased significantly on days 1, 5, and 10 after instillation of bleomycin. The interleukin-1 (IL-1) activity, however, was increased significantly on day 1 only as compared with saline-treated hamsters. Next, normal AM were stimulated in vitro by bleomycin. After being fractionated by chromatography, their culture supernatant showed IL-1 activity, which also indicated FP activity. These results suggest that bleomycin directly stimulates AM to release IL-1 in the fibrogenic responses.     

Oxidative injury amplifies interleukin-1-like activity produced by human monocytes

Exposure of human monocytes to 95% normobaric oxygen (O2) was used as an in vitro oxidative injury model to study the effects of the O2-derived species produced by phagocytes at inflammatory sites on monocyte IL-1 production. Exposure to O2 enhanced production by monocytes of IL-1-like activity whether the adherent cells were cultured in the presence of opsonized zymosan, LPS or medium alone. This O2-induced increase in production of IL-1 activity was inhibited by cycloheximide and thus resulted from de novo protein synthesis. Furthermore, the increase was prevented by the addition of the protein kinase inhibitor N-2-methylaminoethyl-5-isoquinoline sulfonamide dihydrochloride (H8). Following exposure to O2, Ca2+/phospholipid-independent protein kinase activity increased in comparison to air-exposed monocytes, whereas the dependent form decreased. Since the Ca2+/phospholipid-independent form is known to derive from the dependent form (protein kinase C) by proteolysis in the presence of a thiol proteinase, our results suggest that oxidative injury stimulates thiol proteinase activity and enhances production of IL-1 activity by human monocytes partly by interfering with protein kinase C metabolism. Among the consequences of the generation of O2-derived species by phagocytes in inflammatory sites, the augmentation of the production of IL-1-like activity could amplify the inflammatory response.     

Acquisition of peroxidase activity by rat alveolar macrophages during pulmonary inflammation.

The authors investigated the ability of rat alveolar macrophages to acquire peroxidase activity in the course of pulmonary inflammation. Granulomatous pulmonary inflammation was induced in bacille Calmette-Guérin (BCG)-immunized rats by intravenous injection of BCG in mineral oil. In contrast to normal alveolar macrophages, which are peroxidase-negative, alveolar macrophages lavaged from the BCG-treated rats showed significant peroxidase activity in large cytoplasmic inclusions compatible with internalized exogenous material. Alveolar macrophage uptake of intact peroxidase-positive neutrophils was also observed. Maximal numbers of peroxidase-positive alveolar macrophages were observed after the initial influx of neutrophils into the lungs, and peroxidase activity could be demonstrated in cell-free lavage fluid during the acute phase of lung injury. Normal alveolar macrophages acquired peroxidase activity after incubation with peritoneal exudate neutrophils, with purified soluble human myeloperoxidase, and with opsonized erythrocytes. It is concluded that alveolar macrophages acquire peroxidase activity from multiple sources during pulmonary inflammation. Internalization of peroxidase by the alveolar macrophage may serve to clear a potentially toxic enzyme(s) from the alveolar space and contribute to the resolution of pulmonary inflammation.     

Treating inflammation by blocking interleukin-1 in humans

IL-1 is a master cytokine of local and systemic inflammation. With the availability of specific IL-1 targeting therapies, a broadening list of diseases has revealed the pathologic role of IL-1-mediated inflammation. Although IL-1, either IL-1α or IL-1β, was administered to patients in order to improve bone marrow function or increase host immune responses to cancer, these patients experienced unacceptable toxicity with fever, anorexia, myalgias, arthralgias, fatigue, gastrointestinal upset and sleep disturbances; frank hypotension occurred. Thus it was not unexpected that specific pharmacological blockade of IL-1 activity in inflammatory diseases would be beneficial. Monotherapy blocking IL-1 activity in a broad spectrum of inflammatory syndromes results in a rapid and sustained reduction in disease severity. In common conditions such as heart failure and gout arthritis, IL-1 blockade can be effective therapy. Three IL-1blockers have been approved: the IL-1 receptor antagonist, anakinra, blocks the IL-1 receptor and therefore reduces the activity of IL-1α and IL-1β. A soluble decoy receptor, rilonacept, and a neutralizing monoclonal anti-interleukin-1β antibody, canakinumab, are also approved. A monoclonal antibody directed against the IL-1 receptor and a neutralizing anti-IL-1α are in clinical trials. By specifically blocking IL-1, we have learned a great deal about the role of this cytokine in inflammation but equally important, reducing IL-1 activity has lifted the burden of disease for many patients.     

Release of interleukin-1 (IL-1) and IL-1-like factors from rabbit macrophages with silica

Oil-elicited rabbit macrophages stimulated by endotoxin were found to release increased amounts of interleukin 1 (IL-1) when incubated with silica. The assays used to determine the amount of IL-1 released were uptake of thymidine by mouse thymocytes, fever in rabbits, and neutrophilia in rats. All three assays showed that endotoxin-stimulated macrophages released five to 10 times more IL-1 when incubated with silica. Most of the IL-1 had a molecular weight (MW) of about 14,000 with a smaller amount at a MW of approximately 35,000. All of the neutrophilia-producing activity had an isoelectric point (pl) near 7. Thymocyte proliferation was promoted about equally by activities near pH 5 and 7. Fever was found not only at these two isoelectric points but also at a pl above 8 which had neither of the other two activities.     

Tubeimoside-1 attenuates LPS-induced inflammation in RAW 264.7 macrophages and mouse models

Abstract

Context: Acute lung injury (ALI), characterized by severe hypoxemia, pulmonary edema and neutrophil accumulation in the lung, is a common clinical problem associated with significant morbidity and mortality in shock, sepsis, ischemia reperfusion, etc.

Objective: In this study, we aimed at investigating the protective effect of tubeimoside-1 (TBMS1) on inflammation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and a LPS-induced in vivo lung injury model.

Materials and methods: We evaluated the effect of TBMS1 on LPS-induced production of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β in the culture supernatants of RAW 264.7 cells by enzyme-linked immunosorbent assay. LPS (0.5?mg/kg) was instilled intranasally in phosphate-buffered saline to induce ALI, and the severity of pulmonary injury was evaluated 6?h after LPS challenge.

Results: TBMS1 significantly inhibited the production of the pro-inflammatory cytokines, TNF-α, IL-6 and IL-1β in vitro and in vivo. Pretreatment with TBMS1 markedly attenuated the development of pulmonary edema, histological severities and inflammatory cells infiltration in mice with ALI. In addition, we further demonstrated that TBMS1 exerts an anti-inflammatory effect in vivo model of ALI through suppression of IκB activation and p38/extracellular signal-regulated kinase mitogen-activated protein kinases signaling in a dose-dependent manner.

Discussion and conclusion: Overall, our data suggest that TBMS1 inhibits inflammation both in vitro and in vivo, and may be a potential therapeutic candidate for the prevention of inflammatory diseases.     

Modulation of anti-Candida activity of human alveolar macrophages by interferon-gamma or interleukin-1-alpha

The fungicidal and bactericidal activities of human alveolar macrophages (AM) and peripheral blood monocytes (PBM) from 18 healthy volunteers were evaluated. The results showed that AM were able to phagocytize and kill Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus. However, killing of the bacteria was already complete in 2 h, whereas killing of Candida required 4 to 6 h despite an early phagocytosis of yeast cells. The fungicidal activity of freshly collected AM and PBM was also tested after effector cell exposure to interferon-gamma (IFN-gamma), interleukin-1-alpha (IL-1 alpha), endotoxin lipopolysaccharide (LPS), or interleukin 2 (IL-2). It was found that treatment with IFN-gamma, IL-1 alpha, or LPS significantly augmented macrophage and PBM candidacidal activity, whereas the addition of IL-2 was ineffective. We also evaluated killing of C. albicans by AM cultured in vitro for different times. While phagocytosis was apparently unaffected, the candidacidal activity progressively decreased over the in vitro culture period, an effect that was largely reversed by cell exposure to IFN-gamma, IL-1 alpha, or LPS. In an experimental model in which mice infected with an agerminative C. albicans strain (PCA-2) resisted lethal microbial challenge, freshly harvested AM showed increased cytotoxic activity to Aspergillus fumigatus in vitro as well as enhanced IL-1 production. In conclusion, present data confirm the crucial role of AM in the surveillance of bacterial and fungal infections and indicate that treatment of these cells with IFN-gamma or IL-1 alpha is able to enhance their antimicrobial capability.     

Surface interleukin-10 inhibits listericidal activity by primary macrophages

Interleukin-10 (IL-10) down-regulates multiple functions of monocytes and macrophages, including the ability of macrophages to kill many intracellular microorganisms. The experiments presented here test the hypothesis that IL-10 expressed on the cell surface inhibits the ability of primary mouse macrophages to kill the facultative, intracellular bacterium Listeria monocytogenes. We show that, in contrast to macrophages from normal mice, both bone marrow-derived macrophages (BMDM) and thioglycollate-elicited macrophages obtained from IL-10-/- mice can kill L. monocytogenes. Treatment with anti-IL-10 monoclonal antibody (mAb) enables BMDM from normal mice and thioglycollate-elicited macrophages from RAG-2-/- mice (which lack T or B cell-derived IL-10) to kill L. monocytogenes, and concurrently down-regulates the expression of surface IL-10. Surface IL-10 on paraformaldehyde-fixed cells can inhibit nitric oxide (NO) production by interferon-gamma (IFN-gamma)-stimulated macrophages from IL-10-/- mice, thus directly showing functional activity of surface IL-10. Taken together, these studies indicate that macrophage surface IL-10 is biologically active and down-regulates macrophage bactericidal activity.     

Increased release of interleukin-1 from mouse peritoneal macrophages in vitro after cisplatin treatment

The supernatants collected from cis-platin (2 micrograms, 5 micrograms, 10 micrograms, treated macrophage monolayers enhance the proliferation of thymocytes by a submitogenic concentration of con A (1 microgram/ml). The supernatants collected from the untreated macrophage monolayers show a gradual ten fold increase in the interleukin-1 (IL-1) activity during 30 min to 48 h incubation at 37 degrees C. Supernatants collected from macrophage monolayers treated with 2 micrograms/ml of cis-platin show only a marginal increase in IL-1 activity as compared to untreated monolayers. However, compared to controls, 30 to 40 fold increases in IL-1 activity were measured in supernatants collected from the macrophage monolayers incubated with 5, 10 and 20 micrograms/ml cis-platin at 37 degrees C. The IL-1 activity in supernatants collected from macrophage monolayers treated with cis platin and LPS are also compared.     

Time-course of phospholipase A2, eicosanoid release and cellular accumulation in rat immunological air pouch inflammation

Phospholipase A₂ activity in the rat air pouch cavity was determined after induction of a reverse passive Arthus reaction. Time-course of phospholipase A₂ activity appeared to correlate with increased prostaglandin E₂ levels in inflammatory exudate and with the influx of mononuclear inflammatory cells.Local administration of anti-inflammatory drugs such as dexamethasone, indomethacin, or a PLA₂ inhibitor such as p-bromophenacyl bromide significantly inhibited exudate volume, cellular influx, granuloma formation, exudate PGE₂ levels and PLA₂ activity, to varying degrees. Dexamethasone treatment significantly reduced all parameters determined, whereas p-bromophenacyl bromide had a significant inhibitory effect on PLA₂ activity and PGE₂ release, and indomethacin only restored PGE₂ levels.These results show that PLA₂ is neither the only nor the most important factor involved in the development of subchronic inflammation.     

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

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

Identification and characterization of a partial cDNA expressing interleukin-1-like activity in keratinocytes.

A partial cDNA has been isolated from the human keratinocyte cell line COLO-16 which is distinct from either IL-1 alpha or beta and encodes a protein which displays some of the biological properties associated with IL-1. The 720 bp partial cDNA hybridized on Northern blots of COLO-16 mRNA to a 1.6 kbp message of low abundance. Expression of the partial cDNA in COS-1 cells resulted in activity in three IL-1 assays: thymocyte co-stimulation, D10.G4.1 T-cell stimulation and fibroblast proliferation. Antisera generated against synthetic peptides based on inferred protein sequence from the cDNA reacted with a 20 kDa and 30 kDa species in both the COLO-16 cell line and PMA-stimulated normal human keratinocytes. These novel species were also present in PMA-stimulated and unstimulated human dermal fibroblasts and human T-cell lines.