摘要:

AbstractStructurally, the monocyte chemotactic proteins MCP‐1, ‐2, and ‐3 form a subfamily of the C‐C or β‐chemokines. Like other chemokines, MCPs are produced by a variety of cells on stimulation with cytokines (interleukin‐1, tumor necrosis factor‐α, interferon‐γ), bacterial and viral products or mitogens. MCP‐1 levels are enhanced during infection and inflammation, which are characterized by leukocyte infiltration. In vitro, MCPs are chemotactic for a distinct spectrum of target cells and show different specific biological activities depending on the cell type and the chemokine tested. MCP‐3 has the broadest range in that it activates monocytes, dendritic cells, lymphocytes, natural killer cells, eosinophils, basophils, and neutrophils. The most sensitive cells to all three MCPs are lymphocytes and monocytes. MCP‐1 is a potent basophil activator but does not attract eosinophils, whereas, at higher concentrations, MCP‐2 also stimulates both eosinophils and basophils. The signal transduction of MCPs on monocytes involves at least two G protein‐linked C‐C chemokine receptors: C‐C CKR‐1 binds MCP‐3 and C‐C CKR‐2 binds MCP‐1 and MCP‐3 but not MCP‐2. Receptor binding leads to enhanced [Ca2+]ifor all chemokines except for MCP‐2.

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.67

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

AbstractGlomerular diseases represent the major cause of renal failure. Despite decades of research our understanding of the mechanism(s) associated with immune‐mediated glomerular injury remains poor. Consequently most of the therapies that are used are nonspecific with major side effects and offer minimal therapeutic benefits for the patient. The need for new strategies for therapy is clear. The drawing of leukocytes from the circulation into the inflamed glomerulus, accompanied by proliferation of resident mesangial cells and expansion of the mesangial matrix are key processes in the pathogenesis of glomerulonephritis (GN). The migration of inflammatory cells into an extravascular site requires a series of coordinated signals including the generation of a chemotactic gradient by the cells of the extravascular compartment. The nature of the stimulus and the subsequent spectrum of chemotactic factors produced determine the specific leukocyte population recruited to the inflammatory site. Members of the chemokine family play a central role in this process by attracting and stimulating specific subsets of leukocytes. Our hypothesis is that mesangial cell‐derived chemokines are responsible for the initiation and maintenance of glomerular inflammation; in this review we discuss our recent findings supporting this theory. Increasing our understanding of the intracellular pathways that regulate chemokine production in human mesangial cells may provide leads to the design of more effective therapies for the prevention and treatment of glomerular inflammation.

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.75

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

AbstractWe report here the ability of the β chemokines MIP‐1α, MP‐1β, RANTES, and MCP‐1 to enhance some lymphocyte effector functions. Initial studies focused on the effects of chemokines on human and mouse cytotoxic T lymphocyte (CTL)–and natural killer (NK) cell–specific cytolytic responses. The results demonstrate that β chemokines are capable of augmenting mouse and human CTL and human NK–but not lymphokine‐activated killer cell– or antibody‐dependent cell cytotoxicity–specific cytolytic responses. Neutralisation analysis utilizing integrin‐specific antibodies revealed that CTL/NK–tumor cell conjugate formation is required for chemokine‐induced killing. In addition, both CTLs and NK cells incubated with various β chemokines were induced to degranulate and release granule‐derived serine esterases, suggesting that chemokines may be important costimulators of CTL and NK cell degranulation and may thus augment local target cell destruction. Chemokines also modulate antigen‐driven T cell proliferative responses as well as effects on lymphokine production. Many of the β chemokines were found to potentiate human and mouse antigen‐specific Th1 and Th2 clone activation promoting cellular proliferation and the release of various lymphokines. This chemokine‐mediated T cell proliferation was chemokine and antigen dose dependent as well as clone dependent. Chemokine pretreatment analyses with T cells and antigen‐presenting cells (APCs) revealed that chemokines up‐regulate both T cell and APC functions. Costimulation assays using immobilized anti‐CD3 monoclonal antibody–coated plates and purified human and mouse T cells and T cell clones in the presence of various chemokines also exhibited enhanced proliferation and lymphokine secretion. This costimulation was interleukin‐2 dependent and required the presence of free extracellular calcium. Examination of chemokine‐treated APCs revealed that the T cell costimulatory molecule B7‐1 was induced by various β chemokines. Neutralization of endogenously produced chemokines with specific antibodies during an antigen‐specific T cell response blocked cellular proliferation, suggesting that the chemokines have an autocrine and/or paracrine role in antigen‐induced T cell proliferative responses. Together, these results suggest that chemokines play a significant role in the activation of polyclonal as well as antigen‐specific helper and cytotoxic T cells during the genesis of an immune response.

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.81

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

AbstractIn cattle, γδ T cells represent a higher proportion of circulating T cells than in humans. Bovine γδ T cells can be recognized by expression of γδ T cell receptor (γδ TCR) determinants or by a 215/230‐kDa surface antigen (WC1). WC1 is expressed on 90% or more of circulating bovine γδ T cells. The effects of dexamethasone on this and other subsets (CD3, CD2, CD4, CD8) of peripheral blood T lymphocytes were determined by flow cytometric analysis. Twelve 15‐month old bulls were injected with dexamethasone (0.04 mg/kg/day) for 3 consecutive days and four bulls were untreated controls. Blood samples were collected daily for 3 days before dexamethasone injections and for an additional 7 days starting on the third injection day. Data were recorded as percent positive cells and as mean fluorescent intensity (MFI) of positive cells. Initially, CD3+ cells represented 65–73% of all peripheral blood mononuclear cells (PBMC). Dexamethasone reduced CD3+ cells to 30%, and these recovered to 50% positive cells by 9 days after the last dexamethasone injection. Loss of CD3+ cells was not due to reductions in αβ T cells because dexamethasone did not influence the percent CD2+, CD4+, or CD8+ cells. However, percent WC1+ cells rapidly declined from a baseline of 26.4% of PBMC to<6% by the final injection. During injections, the MFI of WC1 increased. The MFI of WC1 returned to control values 7 days after the last injection of dexamethasone, but the percent γδ T cells recovered to only 14% WC1 + PBMC by the final day of the study. During its maximum effects on WC1, dexamethasone also caused a profound decrease of L‐selectin MFI on remaining PBMC (mostly αβ T cells and monocyte/macrophages). In a second trial, two‐color analyses determined that dexamethasone did not increase apoptosis in WC1 + cells and did not reduce L‐selectin MFI on either CD2+ or WC1 + cells. The cumulative results suggested that dexamethasone promoted γδ T cell migration out of peripheral blood via an L‐selectin‐independent mechanism and that dexamethasone did not alter αβ T cell migration kinetics.

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.90

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

AbstractThe vesiculo‐vacuolar organelle (VVO) is a recently described organelle found in the cytoplasm of endothelial cells that line tumor microvessels and normal venules. VVOs are grape‐like clusters of interconnecting uncoated vesicles and vacuoles, bounded by trilaminar unit membranes, that span the entire thickness of vascular endothelium, thereby providing a potential transendothelial connection between the vascular lumen and the extravascular space. Macromolecular tracers preferentially cross hyperpermeable tumor microvessels through VVOs. The present investigation was undertaken to elucidate further the ultrastructure and function of VVOs in a murine ovarian carcinoma (MOT) and in normal venules. Morphometry revealed that VVOs were enormous cytoplasmic structures (median area, 0.12–0.14 μm2 in single electron micrographs). Moreover, the individual vesicles and vacuoles that comprised VVOs were on average substantially larger than capillary caveolae and followed a non‐normal distribution that was skewed to the right. Specimen tilting provided conclusive evidence that individual VVO vesicles and vacuoles communicated with each other and with the endothelial cells' plasma membranes by stomata, some of which were closed by diaphragms composed of a single membrane. Studies with two tracers, ferritin (FE, diameter ~ 11 nm) and horseradish peroxidase (HRP, diameter ~ 5 nm), revealed that passage of macromolecules through VVOs was regulated at the level of stomatal diaphragms, thereby demonstrating a mechanism for controlling the passage of macromolecules across endothelial cells. Thus, compared with tumor microvessels, little circulating FE and HRP entered the VVOs of normal venular endothelium because stomata joining vesicles and vacuoles to each other and to the lumen and ablumen were closed. VVOs and their component vesicles/vacuoles were readily distinguished from endosomal organelles such as coated vesicles and multivesicular bodies, which also accumulated FE and HRP. Our findings indicate that VVOs provide a major pathway for the extravasation of circulating macromolecules across endothelia taller than capillary endothelium and suggest that upregulated VVO function accounts for the well‐known hyperpermeability of tumor blood vessels.

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.100

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

AbstractIn vivo loading of a synthetic peptide (peptide 4) corresponding to residues 314–331 (RSRKRLSQDAYRRNSVRF) consistently diminished the oxidative burst in response to either phorbol 12‐myristate 13‐acetate (PMA) or formylmethionyl‐leucyl‐phenylalanine and cytochalasin B (fMLP/CB) compared to other synthetic peptides derived from the p47phoxsequence. The effects of peptide 4 were concentration dependent with respect to both PMA and fMLP/CB. In contrast, peptide 4 enhanced the oxidative burst in response to fMLP alone. Peptide 4 inhibited the PMA and fMLP‐mediated phosphorylation of endogenous neutrophil cytosolic proteins including p47phox. The PMA‐induced translocation of p47phoxto the plasma membrane was diminished in neutrophils loaded with peptide 4. These data represent the first report of a synthetic peptide derived from p47phoxthat inhibits the NADPH oxidase in intact neutrophils and inhibits the protein kinase C–mediated phosphorylation of endogenous p47phox.

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.116

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

AbstractTumor necrosis factor α (TNF‐α) has been shown to induce the production of interstitial collagenase by fibroblasts and chondrocytes. We investigated the role of TNF‐α in collagenase gene expression by U937 monocyte/macrophage cells. Transcription of the TNF‐α gene was observed after 0.5 h of phorbol myristate acetate (PMA) stimulation. Collagenase mRNA expression was not observed until 5–7 h of activation with PMA. TNF‐α was detected in the culture supernatants 2–3 h before transcription of the collagenase gene. Neutralization of TNF‐α protein with anti‐TNF‐α antibodies significantly reduced collagenase mRNA expression. Protein kinase C (PKC) and protein tyrosine kinase (PTK) inhibition essentially abolished both PMA‐induced TNF‐α protein secretion and collagenase mRNA expression. Collagenase gene expression induced by exogenous TNF‐α in U937 cells stimulated with a suboptimal concentration of PMA was sup‐pressed by PTK, but not PKC, inhibition. The pyrrolidine derivative of dithiocarbamate, a potent inhibitor of nuclear factor‐κB (NF‐κB) activation, resulted in a marked reduction in collagenase gene transcription, however, no reduction of TNF‐α secretion was noted. Anti‐TNF‐α antibodies inhibited PMA‐induced NF‐κB activation. These observations demonstrate an important role for TNF‐α in the autocrine regulation of collagenase gene expression by U937 cells. Additionally, TNF‐α‐induced PTK and NF‐κB activation were important in collagenase gene expression in this cell line.

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.125

出版商:Wiley    

年代:1996

数据来源: WILEY

ISSN:0741-5400    

DOI:10.1002/jlb.59.1.i

出版商:Wiley    

年代:1996

数据来源: WILEY