Murine macrophage activation by staphylococcal exotoxins (original) (raw)
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Infection and immunity, 1999
The ability of innate immune cells to differentially respond to various bacterial components provides a mechanism by which the acquired immune response may be tailored to specific pathogens. The response of innate immune cells to bacterial components provides regulatory signals to cognate immune cells. These signals include secreted cytokines and costimulatory molecules, and to a large extent they determine the quantitative and qualitative nature of the immune response. In order to determine if innate immune cells can differentially respond to bacterial components, we compared the responses of macrophages to two bacterially derived molecules, cholera toxin (CT) and lipopolysaccharide (LPS). We found that CT and LPS differentially regulated the expression of interleukin-12 (IL-12) and CD80-CD86 but not that of IL-1beta. LPS and CT each induced IL-1beta expression in macrophages, while only LPS induced IL-12 and only CT induced CD80-CD86. These differences were markedly potentiated in...
Immunology, 1997
We studied the pathways of macrophage response to lipopolysaccharide (LPS). When mouse macrophages pre-exposed to LPS were restimulated with this agent, reduced tumour necrosis factor-a ( TNF-a) responses (desensitization/endotoxin tolerance) were accompanied by increased (priming) nitric oxide ( NO) responses. Priming was also inducible with recombinant interferon-b (IFN-b). The requirement of TNF-a biosynthesis in the LPS-induced priming was also suggested by the observation that both anti-TNF-a serum and pentoxifylline inhibited this effect. However, addition of mouse recombinant TNF-a (mrTNF-a) did not enhance the priming induced by LPS or IFN-b, and preincubation with mrTNF-a alone, or in association with other cytokines produced by macrophages (interleukin-1b, interleukin-6, or leukaemia inhibitory factor), did not induce a priming effect. We found however, that pentoxifylline, which blocked the priming, also decreased the level of membrane-bound TNF-a. Furthermore, exposure to compound BB-3103 (a metalloproteinase inhibitor that blocks the processing of membrane-bound TNF-a yielding to the secreted cytokine) enhanced the priming effect, the expression of membrane TNF-a and the specific binding of LPS. These observations suggest that the membrane form of TNF-a is involved in the interaction of LPS with a receptor required for LPS-induced priming. membrane of Gram-negative bacteria, is well known for its are not down-regulated in LPS-pretreated cells. For example, ability to activate various kinds of cells and to induce the the elevation of intracellular Ca2+ is not suppressed,10 and the production of a spectrum of cytokines and other inflammatory production of granulocyte-macrophage colony-stimulating mediators.1 Particularly well documented is the direct profactor (GM-CSF ) and interleukin-1b (IL-1b) is enhanced.11 duction of tumour necrosis factor-a ( TNF-a) and nitric oxide Regarding NO production in restimulated macrophages, ( NO) by LPS-stimulated macrophages.2−4 Both TNF-a and different results have been reported, depending on the con-NO make a major contribution to host defence against invadditions used.12-14 In a recent study15 we have shown that ing bacteria and tumour cells5 and to the pathogenesis of pretreatment with LPS primes macrophages for an enhanced septic shock.6,7 Another effect, which has been extensively NO response to a second stimulation with LPS. To understand examined, is the secondary production of mediators elicited more clearly the differential regulations of macrophage by re-exposure of prestimulated macrophages to the same, or responses, we analysed, in this study, the role of TNF-a and to another, appropriate stimulus. It has been established that other cytokines produced by macrophages on this priming pre-exposure of macrophages to low doses of LPS can induce effect of LPS. a state of hyporesponsiveness (desensitization),8 detectable by a marked suppression of the macrophage TNF-a response,
Induction of nitric oxide production in mouse macrophages by Shiga toxin
Journal of Medical Microbiology, 1996
Host mediators play an important role in the pathogenesis of shigellosis and Shiga toxin toxicity. Nitric oxide (NO) production in mouse peritoneal macrophages and in the macrophage 5744 cell line in response to purified Shiga toxin and lipopolysaccharide (LPS) from ShigeZZaflexneri were studied. Shiga toxin induced NO production in a dosedependent manner up to 800 ng/ml. Detectable levels of NO were present as early as 4 h after induction and continued to increase during 72 h; Shiga toxin induced greater NO production with time than did LPS. Pre-treatment of Shiga toxin (400 ng/mI) or LPS (10 ng/ml) with polymyxin B, which inactivates LPS, reduced their ability to induce NO by 28% and 96%, respectively. Induction in the presence of anti-TNFa antibodies did not reduce the amount of NO in the supernate. These studies showed that Shiga toxin induces NO production in murine macrophages.
2003
Macrophages from different inbred mouse strains exhibit striking differences in their sensitivity to anthrax lethal toxin (LeTx)-induced cytolysis. Although LeTxinduced cytolysis of macrophages plays an important role in the outcome of anthrax infection, the sensitivity of macrophages in vitro does not correlate with in vivo susceptibility to infection of Bacillus anthracis. This divergence suggests that additional factors other than LeTx are involved in the cytolysis of LeTx-resistant macrophages in vivo. We found that LeTx-resistant macrophages became sensitive to LeTx-induced cytolysis when these cells were activated by bacterial components. Tumor necrosis factor-␣ induced by bacterial components was a key factor that cooperated with LeTx in inducing LeTx-resistant macrophage death. Tumor necrosis factor-␣/LeTx-induced death of LeTx-resistant macrophages was dependent on mTor (mammalian target of rapamycin), but independent of caspases. Our data indicate that host responses to anthrax infection contribute to cytolysis of LeTx-resistant macrophages.
1997
Clostridium difficile produces a potent enterotoxin and cytotoxin, toxins A and B, respectively, which appear to be responsible for pseudomenbranous colitis and antibiotic-associated diarrhea. In the present study we explored the neutrophil migration evoked by toxin A in the peritoneal cavities and subcutaneous air pouches of rats and examined the role of macrophages and their inflammatory mediators in this process. Toxin A causes a significant dose-dependent neutrophil influx into the peritoneal cavity, with a maximal response at 0.1 g/ml and at 4 h. The depletion of macrophages by peritoneal washing prevents the toxin A-induced neutrophil migration into the peritoneal cavity. In contrast, an increase in macrophages induced by peritoneal injection of thioglycolate amplifies this toxin effect on neutrophil migration. Furthermore, the injection of supernatants from toxin A-stimulated macrophages into the rat peritoneal cavity causes significant neutrophil migration.
Fems Immunol Med Microbiol, 1998
The aim of this study was to determine if cholera toxin can modulate the expression of several macrophage effector functions. The effect of cholera toxin on the induction of NO synthesis, production of tumor necrosis factor-K and induction of respiratory burst was examined in the J774.A2 macrophage cell line. Pre-incubation of cell cultures with cholera toxin significantly down-regulated lipopolysaccharide-induced NO synthesis and phorbol-12-myristate-13-acetate-induced respiratory burst. Concomitant addition of cholera toxin and lipopolysaccharide to cell cultures enhanced the production of tumor necrosis factor-K. These effects were abrogated when cholera toxin was inactivated by heat or treated with a specific monoclonal antibody.
Cellular Immunology, 1990
Clostridium dz@cile toxin A causes severe intestinal inflammation and fluid secretion in rabbit ileum and is chemotactic for neutrophils in vitro. The mechanism of intestinal injury produced by toxin A appears to involve direct epithelial cell damage as well as recruitment of an inflammatory cell response. The current study was undertaken to determine if toxin A can directly stimulate a proliferative response in lymphocytes. Highly purified toxin A, in the presence ofthe calcium ionophore, ionomycin, stimulated substantial ['Hlthymidine incorporation by murine splenic lymphocytes, which was maximal at 1 Om9 Mtoxin A and 800 rig/ml ionomycin. Removal of T cells with anti-Thy-l.2 antibody plus complement had no effect on the proliferative response induced by toxin A. However, [3H]thymidine incorporation in response to toxin A was significantly inhibited (P < 0.00 1) by the removal of macrophages from splenocyte suspensions and was restored by the addition of peritoneal macrophages or cell-free supernatant from toxin A-treated macrophage cultures. Analysis of the toxin A-treated macrophage supernatants showed high levels of IL-I, but not IL-2 or IL-4. The combination of recombinant IL-1 plus ionomycin was found to stimulate ['Hlthymidine incorporation by T cell-depleted splenic lymphocytes. These results suggest that toxin A stimulates the release of IL-1, and possibly other factors, from macrophages which can costimulate murine B lymphocytes. o 1990 Academic Press. Inc.
Immunology, 1997
Clostridium difficile (Cd) toxins appear to mediate the inflammatory response in pseudomembranous colitis and/or colitis associated with the use of antibiotics. In contrast to Cd Toxin A (TxA), Cd Toxin B (TxB) has been reported not to promote fluid secretion or morphological damage in rabbits and hamsters and also does not induce neutrophil chemotaxis in vitro. However, TxB is about 1000 times more potent than TxA in stimulating the release of tumour necrosis factor-a (TNF-a) by cultured monocytes. In the present study, we investigated the ability of TxB to promote neutrophil migration into peritoneal cavities and subcutaneous air-pouches of rats. We also examined the role of resident peritoneal cells in this process as well as the inflammatory mediators involved. TxB caused a significant and dose-dependent neutrophil influx with a maximal response at 0lI gg/cavity after 4 hr. Depleting the peritoneal resident cell population by washing the peritoneal cavity or increasing this population by pretreating the animals with thioglycollate blocked and amplified the TxB-induced neutrophil migration, respectively. Pretreating the animals with MK886 (a lipoxygenase inhibitor), NDGA (a dual cycloand lipoxygenase inhibitor) or the glucocorticoid, dexamethasone, but not with indomethacin (a cyclo-oxygenase inhibitor), or BN52021 (a platelet-activating factor antagonist), inhibited the neutrophil migration evoked by TxB. Pretreatment with dexamethasone or the administration of anti-TNF-x serum into the airpouches also significantly reduced the TxB-induced neutrophil migration. Supernatants from TxBstimulated macrophages induced neutrophil migration when injected into the rat peritoneal cavity. This effect was attenuated by the addition of either MK886 or dexamethasone to the macrophage monolayer and by preincubating the supernatants with anti-TNF-a6 serum. TxB also stimulated the release of TNF-ax by macrophages. Overall, these results suggest that TxB induces an intense neutrophil migration which is mediated by macrophage-derived TNF-a and lipoxygenase products.
FEMS Immunology and Medical Microbiology, 1998
The aim of this study was to determine if cholera toxin can modulate the expression of several macrophage effector functions. The effect of cholera toxin on the induction of NO synthesis, production of tumor necrosis factor-K and induction of respiratory burst was examined in the J774.A2 macrophage cell line. Pre-incubation of cell cultures with cholera toxin significantly down-regulated lipopolysaccharide-induced NO synthesis and phorbol-12-myristate-13-acetate-induced respiratory burst. Concomitant addition of cholera toxin and lipopolysaccharide to cell cultures enhanced the production of tumor necrosis factor-K. These effects were abrogated when cholera toxin was inactivated by heat or treated with a specific monoclonal antibody.