A novel immunological model for the study of prostate cancer. (57/4263)

The Dunning R-3327 rat prostatic adenocarcinoma is a widely accepted model for in vivo experimental studies of prostate cancer. We have previously derived phenotypically distinct cell lines from a s.c. tumor resulting from the inoculation of the R-3327-5 subclone into Copenhagen rats. In this study, we report studies using a gelatin sponge model for the delivery of tumor cells and the retrieval of tumor-specific leukocytes responsive to different prostatic cell lines. S.c. preimplanted sponges were inoculated with tumor cells previously selected for differential properties of tumor formation and metastasis and examined for leukocyte content at time points of 1, 3, and 5 weeks after tumor cell inoculation. Cytospin and flow cytometric analyses revealed fewer tumor-associated leukocytes present in sponges inoculated with tumorigenic R-3327-5' and R-3327-5'B lines, with lesser sponge degradation, than in experiments with the nontumorigenic R-3327-5'A line, suggestive of a tumor cell-induced immunomodulatory mechanism. Morphological studies indicate an intermittent tumor growth pattern that gradually disappears in sponges inoculated with the nontumorigenic R-3327-5'A cells but a robust growth pattern in sponges inoculated with the tumorigenic cell lines. Cytokine analyses show the secretion of higher levels of active transforming growth factor-beta by the more invasive and metastatic lines. Total transforming growth factor-beta levels are higher in the epithelial, tumorigenic R-3327-5'B line. Additionally, the more tumorigenic lines secrete interleukin 10, a potent immunosuppressive molecule. In this report, we demonstrate the ability to retrieve viable leukocyte populations from a prostate tumor line bearing sponges, which offers an important model for further in vitro and in vivo manipulations and holds promise for testing adoptive immunotherapeutic strategies.  (+info)

Promotion of neutrophil chemotaxis through differential regulation of beta 1 and beta 2 integrins. (58/4263)

Migration of neutrophils requires sequential adhesive and deadhesive interactions between beta 1 and beta 2 integrins and components of the extracellular matrix. Prompted by reports that describe interaction of soluble beta-glucan with the beta 2 integrin Mac-1, a role for beta-glucan in regulation of integrin-mediated migration was investigated. Neutrophil migration in response to fMLP was assessed using an agarose overlay method with slides precoated with fibronectin (Fn) +/- beta-glucan. On Fn, random migration in excess of directed migration was observed. In contrast, migration on Fn + beta-glucan was directional, with marked diminution of random migration. This conversion of random to directed migration was seen neither when Fn was supplemented with alternative polysaccharides nor when beta-glucan was applied to other components of the extracellular matrix. This effect of beta-glucan was shown to be cation dependent and to be effected by Arg-Gly-Asp-containing peptides consistent with an integrin-mediated event. mAb inhibition studies demonstrate that beta-glucan effects this shift toward directed migration through suppression of migration mediated by Mac-1 and very late Ag 5 and enhancement of very late Ag 3-mediated migration. Adhesion assays suggest that the prochemotactic influence of beta-glucan is due, in part but not entirely, to modulation of PMN adhesion to Fn. In summary, these data support a novel role for beta-glucan in regulation of beta 1- and beta 2-mediated neutrophil migration on Fn.  (+info)

Protein kinase C-dependent effects on leukocyte migration of thalidomide. (59/4263)

Thalidomide is effective in the treatment of some tumor necrosis factor-related diseases, but its cellular target is not known. Effects of thalidomide were investigated on lymphocytes and monocytes. Cell migration was examined in a Boyden chamber. Effects on protein kinase C (PKC) were investigated functionally by use of PKC inhibitor and in purified enzyme preparations. Thalidomide itself showed no direct chemotactic effect on lymphocytes or monocytes. Preincubation with the drug significantly enhanced random migration of both cell types. This effect was bisindolylmaleimide-reversible, suggesting involvement of PKC. Preincubation with thalidomide diminished the chemotactic response of monocytes towards formyl peptide but failed to influence lymphocyte chemotaxis towards RANTES or interleukin-8. In a cell-free assay, inhibition of PKC activation by bisindolylmaleimide could be reversed by thalidomide, indicating direct interactions of thalidomide with PKC. Results suggest that effects of thalidomide in chronic inflammation may be related to actions on leukocyte functions.  (+info)

Inhibition of tyrosine kinase activation blocks the down-regulation of CXC chemokine receptor 4 by HIV-1 gp120 in CD4+ T cells. (60/4263)

Because the binding of HIV-1 envelope to CD4 initiates a configurational change in glycoprotein 120 (gp120), enabling it to interact with fusion coreceptors, we investigated how this process interferes with the expression and function of CXC chemokine receptor 4 (CXCR4) in CD4+ T lymphocytes. A recombinant gp120 (MN), after preincubation with CD4+ T lymphocytes, significantly inhibited the binding and chemotaxis of the cells in response to the CXCR4 ligand stromal cell-derived factor-1alpha (SDF-1alpha), accompanied by a markedly reduced surface expression of CXCR4. gp120, but not SDF-1alpha, induced rapid tyrosine phosphorylation of src-like kinase p56lck in CD4+ T cells, whereas both gp120 and SDF-1alpha caused phosphorylation of the CXCR4. The tyrosine kinase inhibitor herbimycin A abolished the phosphorylation of p56lck and CXCR4 induced by gp120 in association with maintenance of normal expression of cell surface CXCR4 and a migratory response to SDF-1alpha. Thus, a CD4-associated signaling molecule(s) including p56lck is activated by gp120 and is required for the down-regulation of CXCR4.  (+info)

Thioredoxin, a redox enzyme released in infection and inflammation, is a unique chemoattractant for neutrophils, monocytes, and T cells. (61/4263)

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)

Identification of oligopeptide sequences which inhibit migration induced by a wide range of chemokines. (62/4263)

We have identified an amino acid sequence, termed peptide 3, corresponding to amino acids 51-62 of the mature human monocyte chemoattractant protein-1 (MCP-1), which inhibits human mononuclear-cell and THP-1-cell migration induced by a wide range of chemokines. For example, peptide 3 inhibited MCP-1-induced THP-1 migration in a transwell assay with an ED50 of approx. 8 microM. Peptide 3 binds directly to THP-1 cells with an association constant of approx. 10 microM, and is therefore likely to be a direct receptor antagonist for CC and CXC chemokine receptors. By performing a structure-function analysis of this peptide, we have identified a sequence variant that shows an approx. 3-4-fold greater potency as an inhibitor of chemokine-induced migration [Leu4Ile11 peptide 3 (1-12)]. Furthermore, unlike peptide 3, which binds to the Duffy antigen receptor for chemokines on human erythrocytes with a similar affinity to the specific chemokine receptors on THP-1 cells, the Leu4Ile11 peptide 3 (1-12) sequence variant shows at least 20-fold greater selectivity for the specific receptors. Derivatives of Leu4Ile11 peptide 3 (1-12) are therefore the best candidates among the molecules we have investigated for use as a chemokine inhibitor in vivo.  (+info)

All ApoB-containing lipoproteins induce monocyte chemotaxis and adhesion when minimally modified. Modulation of lipoprotein bioactivity by platelet-activating factor acetylhydrolase. (63/4263)

Mildly oxidized LDL has many proinflammatory properties, including the stimulation of monocyte chemotaxis and adhesion, that are important in the development of atherosclerosis. Although ApoB-containing lipoproteins other than LDL may enter the artery wall and undergo oxidation, very little is known regarding their proinflammatory potential. LDL, IDL, VLDL, postprandial remnant particles, and chylomicrons were mildly oxidized by fibroblasts overexpressing 15-lipoxygenase (15-LO) and tested for their ability to stimulate monocyte chemotaxis and adhesion to endothelial cells. When conditioned on 15-LO cells, LDL, IDL, but not VLDL increased monocyte chemotaxis and adhesion approximately 4-fold. Chylomicrons and postprandial remnant particles were also bioactive. Although chylomicrons had a high 18:1/18:2 ratio, similar to that of VLDL, and should presumably be less susceptible to oxidation, they contained (in contrast to VLDL) essentially no platelet-activating factor acetylhydrolase (PAF-AH) activity. Because PAF-AH activity of lipoproteins may be reduced in vivo by oxidation or glycation, LDL, IDL, and VLDL were treated in vitro to reduce PAF-AH activity and then conditioned on 15-lipoxygenase cells. All 3 PAF-AH-depleted lipoproteins, including VLDL, exhibited increased stimulation of monocyte chemotaxis and adhesion. In a similar manner, lipoproteins from Japanese subjects with a deficiency of plasma PAF-AH activity were also markedly more bioactive, and stimulated monocyte adhesion nearly 2-fold compared with lipoproteins from Japanese control subjects with normal plasma PAF-AH. For each lipoprotein, bioactivity resided in the lipid fraction and monocyte adhesion could be blocked by PAF-receptor antagonists. These data suggest that the susceptibility of plasma lipoproteins to develop proinflammatory activity is in part related to their 18:1/18:2 ratio and PAF-AH activity, and that bioactive phospholipids similar to PAF are generated during oxidation of each lipoprotein. Moreover, LDL, IDL, postprandial remnant particles, and chylomicrons and PAF-AH-depleted VLDL all give rise to proinflammatory lipids when mildly oxidized.  (+info)

T-lymphocyte chemotaxis to IL-8 in patients with psoriasis in vitro. (64/4263)

OBJECTIVE: The critical role of infiltrating T cells in the pathogenesis of psoriasis is now well established. In order to determine whether circulating T cells from patients with psoriasis were also involved in the disease process, the authors investigated the biological behavior as studied by chemotactic activity of T cells in patients with psoriasis. METHODS: A 48 microchemotaxis chamber was employed to determine T-cell chemotaxis activity. In addition, the expression of T cell activation markers such as HLA-DR and interleukin 2 receptor were analysed with fluorescence activated cell sorting technique and serum IL-8 level was measured with ELISA methods. Forty-five patients with psoriasis (23 patients with severe psoriasis and 22 with mild psoriasis) and 21 patients with atopic dermatitis were investigated. For comparison, T-lymphocytes from 20 healthy controls were tested equally. RESULTS: T-cell chemotactic responses were significantly decreased in patients with severe psoriasis and atopic dermatitis as compared to healthy controls. Increased expression of activation markers such as HLA-DR and interleukin 2 receptor were demonstrated in circulating T cells from psoriatic patients and atopic dermatitis patients in comparison to healthy controls. Serum IL-8 level was significantly increased in patients with psoriasis and atopic dermatitis. CONCLUSIONS: Circulating T cells in patients with severe psoriasis show abnormal in vitro chemotactic response to IL-8. Furthermore, the in vivo activation state of T lymphocytes in these patients and increased level of serum IL-8 seemed to be associated to their decreased in vitro T-cell chemotactic responses.  (+info)