rC5a directs the in vitro migration of human memory and naive tonsillar B lymphocytes: implications for B cell trafficking in secondary lymphoid tissues.
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Human C5a is a potent chemoattractant for granulocytes, monocytes, and dendritic cells. In mice C5a has been shown to be chemotactic for germinal center (GC) B cells. To date, no information is available on the effects of C5a on human B cell locomotion. Here we demonstrate that rC5a increases polarization and migration of human tonsillar B cells. The locomotory response was due to both chemokinetic and chemotactic activities of rC5a. Moreover, memory and, at a lesser extent, naive B cell fractions from purified tonsillar populations displayed rC5a-enhanced migratory properties, whereas GC cells did not. Flow cytometry revealed C5aR (CD88) on approximately 40% memory and 10% naive cells, respectively, whereas GC cells were negative. Immunohistochemistry showed that a few CD88+ cells were of the B cell lineage and localized in tonsillar subepithelial areas, where the majority of memory B cells settle. Pretreatment of memory B cells with the CD88 mAb abolished their migratory responsiveness to rC5a. Finally, the C5 gene was found to be expressed in naive, GC, and memory B lymphocytes at both the mRNA and the protein level. This study delineates a novel role for C5a as a regulator of the trafficking of human memory and naive B lymphocytes and supports the hypothesis that the B cells themselves may serve as source of C5 in secondary lymphoid tissues. (+info)
Thioredoxin, a redox enzyme released in infection and inflammation, is a unique chemoattractant for neutrophils, monocytes, and T cells.
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Thioredoxin (Trx) is a ubiquitous intracellular protein disulfide oxidoreductase with a CXXC active site that can be released by various cell types upon activation. We show here that Trx is chemotactic for monocytes, polymorphonuclear leukocytes, and T lymphocytes, both in vitro in the standard micro Boyden chamber migration assay and in vivo in the mouse air pouch model. The potency of the chemotactic action of Trx for all leukocyte populations is in the nanomolar range, comparable with that of known chemokines. However, Trx does not increase intracellular Ca2+ and its activity is not inhibited by pertussis toxin. Thus, the chemotactic action of Trx differs from that of known chemokines in that it is G protein independent. Mutation of the active site cysteines resulted in loss of chemotactic activity, suggesting that the latter is mediated by the enzyme activity of Trx. Trx also accounted for part of the chemotactic activity released by human T lymphotropic virus (HTLV)-1-infected cells, which was inhibited by incubation with anti-Trx antibody. Since Trx production is induced by oxidants, it represents a link between oxidative stress and inflammation that is of particular interest because circulating Trx levels are elevated in inflammatory diseases and HIV infection. (+info)
Bleomycin stimulates lung epithelial cells to release neutrophil and monocyte chemotactic activities.
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Although bleomycin, an antineoplastic drug, is used in the treatment of a variety of tumors, the mechanisms of bleomycin-induced lung injury and fibrosis are not fully elucidated. We postulated that bleomycin might stimulate A549 cells, a type II pneumocyte cell line, to release neutrophil and monocyte chemotactic activities (NCA and MCA, respectively). To test this hypothesis, A549 cell supernatant fluids were harvested and evaluated for NCA and MCA. A549 cell supernatant fluids showed NCA and MCA in response to bleomycin in a dose- and time-dependent manner (P < 0.05). Checkerboard analysis revealed that both NCA and MCA were predominantly chemotactic. Partial characterization of the released NCA and MCA showed that the activities were partially heat labile, trypsin digested, and predominantly ethyl acetate extractable. Lipoxygenase inhibitors and cycloheximide inhibited the release of chemotactic activities significantly. Molecular-sieve column chromatography revealed that the released activities were heterogeneous. However, low-molecular-weight activity was prominent. Leukotriene B4-receptor antagonist, anti-interleukin-8, anti-granulocyte colony-stimulating factor, and anti-monocyte chemoattractant protein-1 antibodies attenuated the chemotactic activities. Immunoreactive leukotriene B4 receptor, interleukin-8, granulocyte colony-stimulating factor, and monocyte chemoattractant protein-1 significantly increased in supernatant fluids in response to bleomycin. These data demonstrate that bleomycin stimulates type II epithelial cells to release chemotactic activities and plays a role in inflammatory cell recruitment into the lung. (+info)
Degradation of Japanese encephalitis virus by neutrophils.
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The ability of neutrophils to degrade the phagocytosed Japanese encephalitis (JE) virion, via triggering of the respiratory burst and generation of toxic radicals has been investigated. JEV or JEV-induced macrophage derived factor (MDF) induces increase in intracellular oxidative signals with generation of superoxide anion (O2-), via activation of cytosolic NADPH and subsequent formation of hydrogen peroxide, with maximum activity on day 7 post infection. The response was sensitive to anti-MDF antibody treatment. Further, the study revealed rapid degradation of phagocytosed JE viral protein and nucleic acid. The viral protein degradation was partially dependent on the generation of toxic oxygen species as it could be abrogated by pretreatment of the cells with staurosporine. (+info)
Mycoplasmal lipopeptide MALP-2 induces the chemoattractant proteins macrophage inflammatory protein 1alpha (MIP-1alpha), monocyte chemoattractant protein 1, and MIP-2 and promotes leukocyte infiltration in mice.
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Natural as well as experimental infections with pathogenic mycoplasmas lead to cellular responses characterized by early polymorphonuclear leukocyte influx, which in turn is followed by infiltration of macrophages. Since some of the most potent leukocyte chemoattractants are macrophage products, we investigated whether the 2-kDa macrophage-activating lipopeptide (MALP-2) from Mycoplasma fermentans was capable of inducing chemoattractant chemokines and initiating an in vivo inflammatory effect. MALP-2 was a potent in vitro inducer of the chemokines macrophage inflammatory protein 1alpha (MIP-1alpha), monocyte chemoattractant protein 1 (MCP-1), and MIP-2, yielding a maximal response at 0.1 ng/ml (5 x 10(-11) M). Leukocyte infiltration was determined after intraperitoneal injection of MALP-2, liposome-encapsulated MALP-2, and heat-killed mycoplasmas. There was a steady increase in the number of peritoneal cells over 72 h in response to these agents. Polymorph counts were maximal by 24 to 48 h, decreasing thereafter. Monocytes/macrophages had significantly increased after 3 days. MIP-1alpha, MCP-1, and MIP-2 levels in serum or peritoneal lavage fluid were determined. MIP-1alpha and MCP-1 levels were elevated by 2 to 6 h after injection and were still above control values after 24 h. In contrast, MIP-2 levels reached their maximum at 2 h, dropping to control values after 24 h. We conclude that macrophage-stimulating mycoplasmal lipoproteins, exemplified by MALP-2, play an important role in the late phase of phagocyte recruitment at sites of infection and that this is affected by leukoattractive chemokines. (+info)
Differential production of MCP-1 and cytokine-induced neutrophil chemoattractant in the ischemic brain after transient focal ischemia in rats.
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Chemokines have been shown to play an important role in leukocyte infiltration into ischemic lesions. Recently, the increased expression of monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant (CINC) was observed in experimental stroke models where infiltrated leukocytes were supposed to induce tissue injury, however, the protein level and time course of these chemokines have not been fully elucidated. Therefore, we analyzed the time-dependent production of MCP-1 and CINC in the rat brain after transient middle cerebral artery occlusion (MCAO) by means of specific enzyme-linked immunosorbent assay systems. The MCP-1 levels in the ipsilateral hemispheres increased from 6 h, peaked at 2 days, and thereafter gradually decreased. The peak MCP-1 concentration was 89.2+/-28.2 ng/g tissue wet weight (mean +/- SEM, n = 5, 49.3-fold greater than the contralateral value at the same time, P < 0.05), which is supposed to be high enough to exert its biological effects. In contrast, the maximum CINC concentration that corresponded to 2.9+/-0.7 ng/g tissue wet weight (mean +/- SEM, n = 5, 55.0-fold greater than the contralateral value at the same time, P < 0.05), was observed at 6 h. In addition, we confirmed the temporal profile of leukocyte subtypes that infiltrated into the ischemic brain, thus, neutrophil infiltration occurred at early stages (1-3 days), followed by massive infiltration of macrophages at later stages (2-7 days). These studies suggest that MCP-1 in cerebral ischemia actually plays a significant role in the migration of macrophages into the lesion and that the differential temporal production of these chemokines contributes to the regulation of infiltrated leukocyte subtypes. (+info)
Interferon-gamma (IFN-gamma)-dependent protection and synthesis of chemoattractants for mononuclear leucocytes caused by IL-12 in the lungs of mice infected with Cryptococcus neoformans.
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We have recently demonstrated that IL-12 induced cellular inflammatory responses consisting mainly of accumulation of mononuclear leucocytes in the lungs of mice infected with Cryptococcus neoformans and protected mice against fulminant infection. We examined the involvement of endogenously synthesized IFN-gamma in such a response by investigating the effects of a neutralizing monoclonal antibody against this cytokine. The latter treatment completely abrogated the positive effects of IL-12 on survival of infected mice and prevented IL-12-induced elimination of microbials from the lungs. Histopathological examination showed that accumulation of mononuclear leucocytes in the infected lungs caused by IL-12 was clearly inhibited by anti-IFN-gamma MoAb. We also examined the local production of mononuclear cell-attracting chemokines such as monocyte chemotactic protein-1 (MCP-1), regulated upon activation, normal T cell expressed and secreted (RANTES), macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta and IFN-gamma-inducible protein 10 (IP-10) in the lungs using a reverse transcriptase-polymerase chain reaction (RT-PCR) method. We found that these chemokines were not synthesized in the infected lungs, while IL-12 treatment markedly induced their production. Interestingly, neutralizing anti-IFN-gamma MoAb strongly suppressed IL-12-induced production of these chemokines. Similar results were obtained with MCP-1 and MIP-1alpha when their synthesis was measured at the protein level using respective ELISA kits. Our results indicate that IFN-gamma plays a central role in the protective effects of IL-12 by inducing mononuclear leucocyte-attracting chemokines and cellular inflammatory responses. (+info)
Regulatory effects of interleukin-11 during acute lung inflammatory injury.
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The role of interleukin-11 (IL-11) was evaluated in the IgG immune complex model of acute lung injury in rats. IL-11 mRNA and protein were both up-regulated during the course of this inflammatory response. Exogenously administered IL-11 substantially reduced, in a dose-dependent manner, the intrapulmonary accumulation of neutrophils and the lung vascular leak of albumin. These in vivo anti-inflammatory effects of IL-11 were associated with reduced NF-kappaB activation in lung, reduced levels of tumor necrosis factor alpha (TNF-alpha) in bronchoalveolar lavage (BAL) fluids, and diminished up-regulation of lung vascular ICAM-1. It is interesting that IL-11 did not affect BAL fluid content of the CXC chemokines, macrophage inflammatory protein-2 (MIP-2) and cytokine-inducible neutrophil chemoattractant (CINC); the presence of IL-11 did not affect these chemokines. However, BAL content of C5a was reduced by IL-11. These data indicate that IL-11 is a regulatory cytokine in the lung and that, like other members of this family, its anti-inflammatory properties appear to be linked to its suppression of NF-kappaB activation, diminished production of TNF-alpha, and reduced up-regulation of lung vascular ICAM-1. (+info)