Recombinant interleukin-1 and tumor necrosis factor induce neutrophil migration "in vivo" by indirect mechanisms

Infection with Toxoplasma gondii does not Alter TNFalpha and IL-6 Secretion by A human Astrocytoma Cell Line

The secretion of tumour necrosis factor-α (TNFα), interleukin-1α (IL-α) and interleukin-6 (IL-6) by a human astrocytoma cell fine was studied 1 h, 3 h, 6 h and 24 h after infection with tachyzoites from three Toxoplasma gondii strains (virulent, RH; cystogentc, 76K and Prugniaud strains). The astrocytoma cell fine constitutively secreted TNFα and IL-6, but no IL-1α. A positive control was obtained by stimulation with phorbol esters inducing a significant increase (p < 0.05) in TNFα and IL- 6 secretion but not in IL-1α, while lipopolysaccharide (alone and after priming), interferon gamma, ionophore A 23187 and sera positive to T. gondii did not induce any increase in cytokine levels. None of the tachyzoites, whatever their virulence, induced a significant increase in cytokine production at any time in the study. Tachyzoites did not inhibit the secretion induced by phorbol esters.

Lipoxygenase-derived mediators may be involved in in vivo neutrophil migration induced by Bothrops erythromelas and Bothrops alternatus venoms

Bothrops erythromelas (BEV) and B. alternatus (BAV) venoms induced a dose-dependent neutrophil migration when injected into rat peritoneal cavities (20-160 micrograms/cavity). These venoms (80 micrograms/rat) also induced neutrophil migration in the air pouch model of inflammation. This migratory response seemed to be related to the phospholipase A2 (PLA2) activity of the venoms. BAV had approximately two times more PLA2 activity than BEV, and the neutrophil migration induced by the former venom was two to three-fold greater than that observed with the latter. Heated (90 degrees C for 5 min) BEV lost about 50% of its PLA2 activity and this was accompanied by a corresponding loss in the ability to induce neutrophil chemotaxis. Dexamethasone (0.5 mg/kg, s.c.), an indirect inhibitor of PLA2 activity, also abolished the neutrophil migration induced by both venoms. Since NDGA (100 mg/kg, s.c.) and dexamethasone, but not indomethacin (2 mg/kg, s.c.), strongly reduced the neutrophil migration induced by both bothropic venoms, it is suggested that arachidonate-derived lipoxygenase metabolites such as leukotriene B4 act as the chemotactic mediators. Macrophages could be the main cellular source of such metabolites since they are the predominant resident cells in the rat air pouch, and the migratory response of BEV and BAV into peritoneal cavities was potentiated in rats pretreated with thioglycollate. The neutrophil migration induced by BEV and BAV was not due to endotoxin contamination since heated BEV showed no effect and polymyxin B-treated BAV still remained active.

Blockade by fenspiride of endotoxin-induced neutrophil migration in the rat

Fenspiride, an antiinflammatory drug with low anti-cyclooxygenase activity, administered orally at 60-200 mg/kg inhibited neutrophil migration into peritoneal and air pouches cavities as well as exudation into peritoneal cavities induced by endotoxin but not induced by carrageenin. Up to 100 microM, fenspiride failed to inhibit the in vitro release of a neutrophil chemotactic activity by endotoxin-stimulated macrophages and the in vivo migration into the peritoneal cavities induced by the supernatant of those macrophages. The release of tumour necrosis factor by stimulated macrophages was inhibited by fenspiride in a dose-dependent manner. These results suggest that the antiinflammatory effects of fenspiride are associated with the inhibition of the tumour necrosis factor release by resident macrophages.

Effect of treatment with interleukin-1 receptor antagonist on the development of carrageenan-induced pleurisy in the rat

Pretreatment of rats with the human interleukin-1 receptor antagonist (IL-1ra) by the subcutaneous route at -0.5 h, relative to the intrapleural injection of carrageenan (CG), suppressed the infiltration of cells into the pleural cavity of intact and adrenalectomized rats at 5 h (28 and 74% reduction in intact animals at 0.3 and 10 mg/kg, respectively). Exudate volume at 5 h was also suppressed at dosages of IL-1ra > or = 3 mg/kg. IL-1ra was still effective as an antiinflammatory agent in the 5-h pleurisy model when administered 1 or 2 h, but not 3 h, after CG. The addition of IL-1ra to a maximally effective antiinflammatory dosage of indomethacin (5 mg/kg) resulted in further reductions of cell number and exudate volume, suggesting that the antiinflammatory effects of IL-1ra in the 5-h model were not due solely to inhibition of IL-1-induced prostaglandin biosynthesis. The antiinflammatory effects of suboptimal dosages of IL-1ra and dexamethasone, administered in combination, were essentially additive. In 24-h pleurisy, IL-1ra reduced exudate volume and PMN number after a single dosage of 10 mg/kg, subcutaneously at -0.5 h and after dosages of 3 mg/kg at -0.5 and 5 h. Additional dosages of IL-1ra (3 mg/kg) at 10 and 15 h did not further inhibit PMN accumulation. Treatment with IL-1ra did not affect macrophage accumulation in 24-h CG-induced pleurisy. IL-1ra was not active as an antiinflammatory agent in the 24-h pleurisy model after three dosages of IL-1ra (3 mg/kg) at 5, 10 and 15 h.

Human glioblastoma cells produce 77 amino acid interleukin-8 (IL-8(77))

The production of interleukin 8 (IL-8), a neutrophil chemotactic factor, and its amino acid sequence were examined in glioblastoma cell lines in vitro. Neutrophil chemotactic activity was demonstrated in 9 conditioned media of 15 human glioblastoma cell lines. Tumor necrosis factor (TNF)-alpha stimulated secretion of the activity in 7 lines and induced secretion in 4 other lines. ELISA quantification disclosed that the conditioned media contained interleukin 8 (IL-8) in an amount equivalent to the chemotactic activity. The IL-8 secretion increased with the stimulation by TNF-alpha. Northern blot analysis and the RT-PCR method confirmed expression of mRNA in the glioblastoma cells and its augmentation by TNF-alpha and/or IL-beta. Reversed-phase HPLC following ion-exchange chromatography revealed that the chemotactic activity was a single peptide, which was determined to be IL-8 by the retention time and ELISA. Furthermore, amino acid analysis disclosed that a major part of the glioblastoma-cell derived IL-8 peptide was 77 amino acid IL-8 (IL-8(77); with the N-terminal sequence AVLPRSAKELRCQCI-).

The pivotal role of tumour necrosis factor alpha in the development of inflammatory hyperalgesia

1. The hyperalgesic activities in rats of interleukin-1 beta (IL-1 beta), IL-6, IL-8, tumour necrosis factor alpha (TNF alpha) and carrageenin were investigated. 2. IL-6 activated the previously delineated IL-1/prostaglandin hyperalgesic pathway but not the IL-8/sympathetic mediated hyperalgesic pathway. 3. TNF alpha and carrageenin activated both pathways. 4. Antiserum neutralizing endogenous TNF alpha abolished the response to carrageenin whereas antisera neutralizing endogenous IL-1 beta, IL-6 and IL-8 each partially inhibited the response. 5. The combination of antisera neutralizing endogenous IL-1 beta + IL-8 or IL-6 + IL-8 abolished the response to carrageenin. 6. These results show that TNF alpha has an early and crucial role in the development of inflammatory hyperalgesia. 7. The delineation of the role of TNF alpha, IL-1 beta, IL-6 and IL-8 in the development of inflammatory hyperalgesia taken together with the finding that the production of these cytokines is inhibited by steroidal anti-inflammatory drugs provides a mechanism of action for these drugs in the treatment of inflammatory hyperalgesia.

Early activation of splenic macrophages by tumor necrosis factor alpha is important in determining the outcome of experimental histoplasmosis in mice

Experimental infection of animals with Histoplasma capsulatum caused a massive macrophage infiltration into the spleen and induced the production of tumor necrosis factor alpha (TNF-alpha) locally. The cytokine was also produced in vitro by peritoneal exudate macrophages exposed to a large inoculum of yeast cells. Depletion of the cytokine by injection of polyclonal sheep anti-TNF-alpha antibody was detrimental to sublethally infected mice. Fungous burdens in the spleens of TNF-alpha-depleted mice were higher than they were in the infected control mice at days 2, 7, and 9 after infection, and the antibody-treated animals succumbed to the infection. Histopathological study of spleen sections revealed that splenic macrophages were not able to control proliferation of intracellular yeasts as a result of TNF-alpha depletion. It seems that TNF-alpha plays a role in early activation of splenic macrophages which is important in controlling the outcome of an infection.

Interferon-gamma (IFN-gamma) and macrophage inflammatory proteins (MIP)-1 and -2 are involved in the regulation of the T cell-dependent chronic peritoneal neutrophilia of mice infected with mycobacteria

In mycobacterial infections of mice there is a chronic, immune-mediated mobilization of neutrophils to the infectious site. In this study we evaluated the role played by cytokines in the chronic peritoneal neutrophilia which occurs in mice intraperitoneally infected with Mycobacterium bovis BCG or M. avium. Antibodies to IFN-gamma and to MIP-1 and -2 were effective in reducing peritoneal neutrophilia when given during the infection. Whereas the former antibody was only effective when given early, the latter two were effective when administered late in infection, suggesting the MIPs were direct mediators of neutrophil recruitment. Recombinant IFN-gamma given intraperitoneally induced the accumulation of neutrophils and primed the peritoneal cells for an enhanced recruitment of neutrophils. Our data show that chronic neutrophilia during mycobacterial infection is regulated by different cytokines acting at different stages and levels of neutrophil recruitment.

Flare-up of experimental arthritis in mice with murine recombinant IL-1

Intra-articular injections of murine recombinant IL-1 (mrIL-1) during the chronic phase of antigen-induced arthritis (AIA) induced a flare-up of the smouldering inflammation. The exacerbation was characterized by acute and transient joint swelling and this coincided with the extravascular accumulation of neutrophils. IL-1 injected into arthritic joints of neutropenic mice demonstrated that joint swelling was independent of the neutrophil influx into the joint. Both phenomena were absent when IL-1 was injected into a naive joint. The IL-1-induced flare-up was not T cell mediated as in the antigen-induced flare-up, and suggestive evidence is presented that IL-1 sensitivity depended on the resident macrophage population. This explained why the hypersensitivity is not restricted to the immunologically mediated arthritis but reflects a more general hypersensitivity of previously injured joints, e.g. zymosan-induced arthritis and IL-1-affected joints. In addition, IL-1 could also potentiate the antigen-specific flare-up of chronic AIA and prolongs the duration of the exacerbation. Our data indicate that joints bearing a chronic infiltrate are at risk from exacerbations in two ways: a T cell mediated rechallenge with antigen, and a non-specific reactivation by systemic and local IL-1 generation.

Role of resident macrophages in canatoxin-induced in vivo neutrophil migration

Canatoxin (Cntx), a toxic protein purified from Canavalia ensiformis seeds, was shown to have lipoxygenase-mediated effects either in vivo or in vitro. Data here show that Cntx induced a dose-dependent migration of neutrophils and mononuclear cells when injected into rat peritoneal cavities. Furthermore, Cntx was able to induce neutrophil migration into pleural cavities and into air pouches. These effects were inhibited by dexamethasone but not by inhibitors of arachidonic acid metabolism (indomethacin, NDGA, and BW-755c) or by a PAF antagonist (BN 52021). In the peritoneal cavity Cntx caused an increase in vascular permeability inhibited by dexamethasone and BW-755c. Neutrophil migration induced by this toxin was dependent on the number of resident macrophages, since the migratory effect was enhanced by increasing the peritoneal macrophage population with thioglycollate pretreatment and was diminished when this population was reduced by peritoneal wash. It was also observed that Cntx induced release of a chemotactic factor from macrophage monolayers in vitro. Dexamethasone blocked this release but did not affect in vivo neutrophil recruitment induced by that factor. These data suggest that Cntx-induced neutrophil migration may be mediated by the same macrophage-derived neutrophil chemotactic factor released by other stimuli such as LPS, IL-1, and INF-gamma.

Evidence that endogenous interleukin-1 is involved in leukocyte migration in acute experimental inflammation in rats and mice

As a putative mediator of inflammation interleukin-1 has been implicated in the recruitment of leukocytes during the early stages of the inflammatory reaction. In the present report we have investigated the release of endogenous IL-1 in the rat zymosan pleurisy and in the mouse zymosan peritonitis. In both cases the release of the cytokine was maximal 4 hours after zymosan injection and appeared to be time-related to neutrophil migration into the inflammatory site. The effect of in vivo treatment with dexamethasone in rat pleurisy and with polyclonal anti-murine IL-1 beta antibody in mouse peritonitis was also assessed. The steroid reduced both cell migration and the release of IL-1-like activity as well as the formation of exudate and the release of eicosanoids. The anti-IL-1 beta serum inhibited selectively the number of neutrophil that migrated to the inflamed site (approximately 40%) and the IL-1 activity recovered in (approximately 70%) the exudate. In vitro incubation of the inflammatory exudate with polyclonal anti-murine IL-1 alpha or anti-murine IL-1 beta sera allowed the identification of the IL-1 species present. In the rat pleurisy IL-1 biological activity was mainly due to the alpha species, whereas IL-1 beta was the only species apparently present in the mouse peritoneal exudate.

Neutrophil recruitment inhibitory factor: a possible candidate for a novel cytokine

Inhibitory effect upon neutrophil migration to the inflammatory focus was previously detected in the cell-free incubation fluid of lipopolysaccharide (LPS)-stimulated macrophage monolayers. In the present study we showed that the neutrophil recruitment inhibitory activity from this supernatant was mainly detected in a fraction (P2) obtained by gel filtration chromatography on Sephacryl S-300. P2 fraction was able to inhibit 'in vivo' neutrophil emigration induced by different inflammatory stimuli, but it did not affect 'in vitro' neutrophil chemotaxis induced by FMLP. When injected intravenously, P2 inhibited oedema induced by carrageenin or immunological stimulus but not the oedema induced by dextran, thus affecting cell-dependent inflammatory responses. It was observed that P2 also induced neutrophil migration when injected locally in peritoneal cavities. This activity was significantly reduced by pretreatment of the animals with dexamethasone. Cytokines, such as IL-8 and TNF-alpha that are known to exhibit inhibitory effect upon neutrophil migration, were not detected in P2 fraction by highly sensitive assays. Overall the results suggest the existence of a novel cytokine exhibiting 'in vivo' neutrophil inhibitory activity, referred as NRIF.