In the present study, we investigated the regulation of chemokine‐mediated responses and receptor expression on eosinophils from mice. MIP‐1α (CCL3) and eotaxin (CCL11) induced a significant and only ...partially overlapping intracellular calcium flux in antigen‐elicited and peripheral blood eosinophils, and MCP‐1 (CCL2), MDC (CCL22), MIP‐1β (CCL4), and TCA‐3 (CCL1) did not. To demonstrate functional use of the specific receptors, we examined chemotactic responses. Peripheral blood eosinophils migrated toward MIP‐1α (CCL3) and eotaxin (CCL11) but not MCP‐1 (CCL2), MDC (CCL22), MIP‐1β (CCL4), and TCA‐3 (CCL1). Antigen‐elicited eosinophils migrated toward MIP‐1α (CCL3) and eotaxin (CCL11), but also migrated in response to MIP‐1β (CCL4) and TCA‐3 (CCL1), suggesting the up‐regulation of additional chemokine receptors on antigen‐elicited eosinophils. The up‐regulation of the additional chemokine‐receptor responses appeared to be in part because of cytokine activation, because TNF‐α and/or IL‐4 were able to up‐regulate CCR1, ‐3, ‐5, and ‐8 mRNA expression in eosinophils as well as migration responses to the appropriate ligands. Using antibodies specific for CCR5 and CCR8, the chemotactic response to MIP‐1β and TCA‐3, respectively, was reduced significantly. Finally, the expression of these new receptors appears to have an effect on activation and degranulation because MIP‐1β (CCL4) and TCA‐3 (CCL1) induce significant levels of LTC4 from elicited eosinophils. These results suggest that eosinophils may up‐regulate and use additional chemokine receptors during progression of inflammatory, allergic responses for migration and activation.
Experimental autoimmune encephalomyelitis (EAE) is a T lymphocyte-mediated disease of the central nervous system (CNS), characterized by mononuclear cell infiltration and demyelination resulting in ...paralysis. We examined CC chemokine expression in the CNS throughout the entire course of the disease and found that the production of macrophage inflammatory protein (MIP)-1α correlated with increasing acute disease severity and remained elevated throughout chronic, relapsing disease. In contrast, a substantial level of monocyte chemotactic protein (MCP)-1 expression was not observed until late in acute disease and continued to be evident in the relapsing phase of the disease. MCP-1 expression correlated with increasing severity of clinical relapses. Lower levels of RANTES in the CNS were noted throughout the disease course, but showed little correlation with either acute or relapsing disease. Although RANTES expression was observed during the entire course of disease, anti-RANTES treatment had no effect on clinical disease progression. Anti-MCP-1, but not anti-MIP-1α, treatment during relapsing EAE decreased clinical severity of relapsing disease. Furthermore, anti-MCP-1 treatment reduced CNS macrophage accumulation during relapsing EAE. These results suggest that MIP-1α controls mononuclear cell accumulation during acute EAE, while MCP-1 controls mononuclear cell infiltration during relapsing EAE.
IL-13 has been shown to exert potent anti-inflammatory properties. In this study, we elucidated the functional role of endogenous IL-13 in a murine model of septic peritonitis induced by cecal ...ligation and puncture (CLP). Initial studies demonstrated that the level of IL-13 increased in tissues including liver, lung, and kidney, whereas no considerable increase was found in either peritoneal fluid or serum after CLP. Immunohistochemically, IL-13-positive cells were Kupffer cells in liver, alveolar macrophages in lung, and epithelial cells of urinary tubules in kidney. IL-13 blockade with anti-IL-13 Abs significantly decreased the survival rate of mice after CLP from 53% to 14% on day 7 compared with control. To determine the potential mechanisms whereby IL-13 exerted a protective role in this model, the effects of anti-IL-13 Abs on both local and systemic inflammation were investigated. Administration of anti-IL-13 Abs did not alter the leukocyte infiltration and bacterial load in the peritoneum after CLP but dramatically increased the neutrophil influx in tissues after CLP, an effect that was accompanied by significant increases in the serum levels of aspartate transaminase, alanine transaminase, blood urea nitrogen, and creatinine. Tissue injury caused by IL-13 blockade was associated with increases in mRNA and the protein levels of CXC chemokines macrophage inflammatory protein-2 and KC as well as the CC chemokine macrophage inflammatory protein-1alpha and the proinflammatory cytokine TNF-alpha. Collectively, these results suggest that endogenous IL-13 protected mice from CLP-induced lethality by modulating inflammatory responses via suppression of overzealous production of inflammatory cytokines/chemokines in tissues.
Cytokines and the liver Simpson, Kenneth J.; Lukacs, Nicholas W.; Colletti, Lisa ...
Journal of Hepatology,
12/1997, Letnik:
27, Številka:
6
Book Review, Journal Article
The induction of airway hyperreactivity during allergic responses involves multiple ill-defined mechanisms. Recently a role for stem cell factor (SCF) in the development of allergic eosinophilic ...airway inflammation has been identified. In the present study we demonstrate that SCF has a role in both the inflammatory response and airway hyperreactivity. Neutralization of SCF or examination of SCF-mutant mice, which were deficient in SCF and pulmonary mast cells, demonstrated significant alterations in the allergen-induced airway hyperreactive responses. The reduced hyperreactivity response was accompanied by a significant reduction in eosinophil accumulation. To examine the direct role of SCF on airway hyperreactivity, we administered SCF into the airways of normal mice via intratracheal injections and demonstrated a dose dependent increase in airway hyperreactivity at 4 hours that was maintained at 24 hours after administration. Instillation of SCF into SCF-deficient (mast cell deficient) mice demonstrated significantly lower increases in airway hyperreactivity compared with the littermate controls with normal mast cell numbers. These studies demonstrate that locally expressed SCF can induce changes in airway physiology via mast cell activation, verifying the role of SCF in allergic airway inflammation and hyperreactivity.
Macrophage-inflammatory protein 2 (MIP-2) is a major CXC chemokine involved in the migration of polymorphonuclear neutrophils (PMNs) to sites of inflammation. Although cell culture experiments have ...identified different cell types that can produce MIP-2, the cellular sources in vivo are not clearly defined. By using immunohistochemical staining and analysis of chemokine mRNA expression, the present study aimed to localize cells producing MIP-2 in tissues of normal mice and mice challenged with Yersinia enterocolitica. The results showed a constitutive expression of MIP-2 mRNA in bone marrow (BM) of normal mice, but not in other organs such as spleen, lung, or liver. MIP-2 protein was found in all organs tested but it was exclusively associated with PMNs that stained positive with the cell surface marker Gr-1. Bacterial infection caused a 5-fold increase in the number of MIP-2-positive PMNs recruited to spleens concomitant with a strong increase of splenic MIP-2 mRNA. This correlated well with a 3-fold loss of MIP-2-producing cells in BM. Because MIP-2 mRNA expression in PMNs was increased after stimulation with TNF, the results indicate that newly recruited PMNs can supplement their MIP-2 content through TNF-stimulated transcription. Together, the data imply a constitutive production of MIP-2 by a subset of PMNs in BM and argue for the possibility of a rapid mobilization of MIP-2 through its storage in circulating PMNs.
Pulmonary fibrosis is the end point of a chronic inflammatory process characterized by leukocyte recruitment and activation, fibroblast proliferation, and increased extracellular matrix production. ...Previous studies of models of pulmonary fibrosis have investigated the role of cytokines in the evolution of the fibrotic response. The involvement of tumor necrosis factor and interleukin-1 in bleomycin-induced lung injury, a model of idiopathic pulmonary fibrosis, has been well established, suggesting that cytokines mediate the initiation and maintenance of chronic inflammatory lesions. However, the aforementioned cytokines alone cannot account for the recruitment and activation of specific leukocyte populations found in the bleomycin model. Recently, a family of novel proinflammatory cytokines (chemokines) was cloned and characterized, yielding many putative mediators of leukocyte functions. Macrophage inflammatory protein-1 alpha (MIP-1 alpha) and monocyte chemoattractant protein-1 (MCP-1) belong to the C-C chemotactic cytokine family, a group of low-molecular-weight peptides. These molecules modulate chemotaxis, proliferation, and cytokine expression in leukocyte subsets. Our group has investigated the roles of MCP-1 and MIP-1 alpha in the bleomycin model. Both MCP-1 and MIP-1 alpha are expressed in a time-dependent manner after bleomycin challenge, and passive immunization of these animals with either anti-MIP-1 alpha or anti-MCP-1 antibodies attenuated leukocyte accumulation. In addition, we have identified specific cell types expressing MCP-1 or MIP-1 alpha by in situ hybridization and immunohistochemical localization, respectively. Furthermore, our results indicate that MIP-1 alpha expression is mediated by alveolar macrophage-derived tumor necrosis factor, identifying an important cytokine pathway in the initiation of pulmonary fibrosis. Finally, anti-MIP-1 alpha therapy attenuated fibrosis, providing direct evidence for its involvement in fibrotic pathology. Our work has clearly established that the C-C chemokines MCP-1 and MIP-1 alpha are expressed and contribute to the initiation and maintenance of the bleomycin-induced pulmonary lesion.
The extravasation of leukocytes from the lumen of the vessel to a site of inflammation requires specific binding events. The interaction of leukocytes with endothelium, via specific receptors, may ...provide intracellular signals that activate extravasating cells. In the present study, we have investigated the production of chemokines, interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) during monocyte: endothelial cell interactions. Both unstimulated and interferon-gamma (IFN-gamma)-prestimulated human umbilical vein endothelial cells (HUVEC) produced low constitutive levels of IL-8 and MCP-1. The addition of enriched monocytes with unstimulated HUVEC resulted in synergistic increases in production of both IL-8 and MCP-1. Monocytes cultured with IFN-gamma-preactivated HUVECs demonstrated little additional increase in IL-8 and MCP-1 production in coculture assays compared with unstimulated HUVEC. Northern blot analysis paralleled the protein data, demonstrating upregulated expression of IL-8 and MCP-1 mRNA in stimulated and unstimulated coculture assays. Culture of enriched monocytes and endothelial cells in transwells demonstrated no increases in IL-8 or MCP-1, indicating the necessity for cellular contact for chemokine production. In previous investigations, we have demonstrated that increased monocyte-derived MIP-1 alpha production was induced by intracellular adhesion molecule-1 (ICAM-1) interactions on activated HUVECs. In contrast, addition of anti-ICAM-1 monoclonal antibodies (MoAbs) did not diminish the production of IL-8 and MCP-1 in the present study. Furthermore, neither antibodies to IL-1 nor tumor necrosis factor (TNF) diminished the production of either IL-8 or MCP-1. However, when soluble matrix proteins were added to the coculture to block cellular interactions, the chemokine protein and mRNA levels were significantly decreased. IL-8 production was decreased by both soluble collagen and fibronectin, whereas MCP-1 was decreased by only soluble collagen, suggesting differential activation pathways. These results indicate that IL-8 and MCP-1 production are increased during monocyte and endothelial cell interactions in part due to matrix protein binding mechanisms. This mechanism may serve a role in cell activation, production of chemokines, as well as extravasation and recruitment of additional leukocytes during inflammatory responses.
Asperigillus fumigatus spores or conidia are quickly eliminated from the airways of nonsensitized individuals but persist in individuals with allergic pulmonary responsiveness to fungus. A. ...fumigatus-induced allergic airway disease is characterized by persistent airway hyperreactivity, inflammation, and fibrosis. The present study explored the role of CCR2 ligands in the murine airway response to A. fumigatus conidia. Nonsensitized and A. fumigatus-sensitized CBA/J mice received an intratracheal challenge of A. fumigatus conidia, and pulmonary changes were analyzed at various times after conidia. Whole lung levels of monocyte chemoattractant protein-1 (MCP-1/CCL2), but neither MCP-3/CCL7 nor MCP-5/CCL12, were significantly elevated at days 3 and 7 after conidia in nonsensitized mice. MCP-1/CCL2 was significantly increased in lung samples from A. fumigatus-sensitized mice at days 14 and 30 after a conidia challenge. Administration of anti-MCP-1/CCL2 antiserum to nonsensitized mice for14 days after the conidia challenge attenuated the clearance of conidia and significantly increased airway hyperreactivity, eosinophilia, and peribronchial fibrosis compared with nonsensitized mice that received conidia and normal serum. Adenovirus-directed overexpression of MCP-1/CCL2 in A. fumigatus-sensitized mice markedly reduced the number of conidia, airway inflammation, and airway hyperresponsiveness at day 7 after the conidia challenge in these mice. Immunoneutralization of MCP-1/CCL2 levels in A. fumigatus-sensitized mice during days14-30 after the conidia challenge did not affect the conidia burden but significantly reduced airway hyperreactivity, lung IL-4 levels, and lymphocyte recruitment into the airways compared with the control group. These data suggest that MCP-1/CCL2 participates in the pulmonary antifungal and allergic responses to A. fumigatus conidia.
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