Angiopoietins (Ang) are involved in the remodeling, maturation, and stabilization of the vascular network. Ang-4 was discovered more recently; thus, its effect on angiogenesis and its interplay with other angiogenic factors have not been equivocally established. The role of Ang-4 in angiogenesis was tested in Matrigel chambers implanted into the subcutaneous space of nude mice. Ang-4 inhibited the angiogenic response of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and GLC19 tumor cells. In Matrigel chambers with Ang-4-transfected cells, the mean response was significantly lower than that of mock cells. Subcutaneous tumor interstitial fluid pressure (IFP) was significantly lower in Ang-4-transfected GLC19 tumors than in mock-transfected tumors. IFP reduction in Ang-4-transfected tumors was comparable to the reduction seen after bevacizumab treatment. In vitro, we examined the effect of recombinant Ang-4 on endothelial cell migration in Boyden chambers. Human umbilical vein endothelial cell (HUVEC) migration induced by bFGF and VEGF was inhibited by Ang-4 to control levels. In conclusion, we show that rhAng-4, as well as transfection with Ang-4, inhibits angiogenesis induced by GLC19 tumor cells and that Ang-4 expression reduces elevated tumor IFP. In addition, we demonstrate that rhAng-4 inhibits HUVEC migration and growth factor-induced angiogenesis.
Preferential chemotaxis of activated human CD4+ T cells by extracellular cyclophilin A
The recruitment and trafficking of leukocytes are essential aspects of the inflammatory process. Although chemokines are thought to be the main regulators of cell trafficking, extracellular cyclophilins have been shown recently to have potent chemoattracting properties for human leukocytes. Cyclophilins are secreted by a variety of cell types and are detected at high levels in tissues with ongoing inflammation. CD147 has been identified as the main signaling receptor for cyclophilin A (CypA) on human leukocytes. It is interesting that the expression of CD147 is elevated on leukocytes from inflamed tissue, suggesting a correlation among the presence of extracellular cyclophilins, CD147 expression, and inflammatory responses. Thus, cyclophilin-CD147 interactions may contribute directly to the recruitment of leukocytes into inflamed tissues. In the current studies, we show that activated human T lymphocytes express elevated levels of CD147, compared with resting T cells and that these activated T cells migrate more readily to CypA than resting cells. Furthermore, we show that unlike resting CD4+ T cells, the cyclophilin-mediated migration of activated T cells does not require interaction with heparan sulfate receptors but instead, is dependent on CD147 interaction alone. Such findings suggest that cyclophilin-CD147 interactions will be most potent when leukocytes are in an activated state, for example, during inflammatory responses. Thus, targeting cyclophilin-CD147 interactions may provide a novel approach for alleviating tissue inflammation.
IGF-I and IGF-II stimulate directed cell migration of bone-marrow-derived human mesenchymal progenitor cells
Insulin-like growth factors (IGFs) are known to be key regulators of bone growth, remodeling, and repair. Since all these processes depend on the recruitment of cells with the potential to be committed to the osteoblastic lineage, we studied possible effects of IGF-I and -II on migration of human mesenchymal progenitor cells (MPC) using a modified Boyden chamber assay. The results were compared to those of primary osteoblasts and in vitro-osteogenic-differentiated MPC. IGF-I and -II stimulated cell migration of all these cell populations in a dose-dependent manner from 1 to 100ng/mL. The maximal chemotactic index (CI) was 4-5 for MPC and primary osteoblasts and about 3 for in vitro-differentiated MPC. Checkerboard analysis revealed that IGFs stimulated true directed cell migration (chemotaxis) and not simply chemokinesis. Addition of an antibody against the type I IGF receptor (alphaIR3) completely abolished (MPC) or markedly reduced (primary osteoblasts) the chemotactic effects of each of the IGFs. IGFBP-3 itself had no direct effect, while IGFBP-5 stimulated MPC migration at concentrations of 80 and 160ng/mL. Parallel application of IGFBP-3 had borderline inhibitory effects while the addition of 40ng/mL of IGFBP-5 enhanced the chemotactic effect of IGF-I on MPC. In conclusion, our results show that IGF-I and -II are chemotactic factors for MPC and indicate that IGFBP-5 both modulates the IGF-I effect and directly stimulates migration of human mesenchymal progenitor cells.
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Leukocyte Function in Chronic Myeloproliferative Disorders
The myeloproliferative disorders (MPD) are clonal diseases that originate from a transformed stem cell and involve all myeloid lineage. The affected cells have both proliferative and functional impairment. Therefore, we evaluated and compared neutrophil function in 31 patients with polycythemia vera (PV), idiopathic myelofibrosis (MF), chronic myeloid leukemia (CML), and essential thrombocytosis (ET). Neutrophil chemotaxis, random migration, bactericidal activity and superoxide anion release in these patients were simultaneously compared to those of 31 healthy controls. In this study, chemotactic activity was significantly impaired in patients with PV and CML as compared to controls (M+/-SE: 42 +/- 6 vs. 69+/- 5 cells/field; p<0.005 and 47+/-7 vs. 68+/- 5; p<0.05, respectively). The assessment of the bactericidal activity of neutrophils showed no impairment in most of the patients. In the CML group, the serum had a very strong “lytic” effect on bacteria, possibly due to the high levels of serum lysozyme (22 +/- 2 microgram/ml). The superoxide anion release was found to be normal in most of the patients. Nevertheless, in 25% of PV patients the superoxide production was impaired (less than 60% of the simultaneous controls). In ET most patients had normal neutrophil function. Regarding the effect of treatment, neutrophil chemotactic activity was found to be significantly reduced in the hydrea-treated patients, as compared to the non- treated patients (p<0.001) or healthy controls (<0.0001). We conclude that disturbances in neutrophil function are present in patients with various MPDs, except ET. This probably reflects abnormal maturation of ancessors of the damaged stem cells. Nevertheless, we should keep in mind that therapy itself could affect neutrophil functions. This matter should be studied more extensively. Although infections are not common in MPD disorders, they occasionally occur. It is possible that impairment in the phagocytic function contribute to the development of infections in patients with myeloproliferative disorders.
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Cadmium Induces Interleukin-8 in Alveolar Epithelial Type II Cells (A549)
Cadmium (Cd) is a contaminant in cigarette smoke and may play an important role in the pathogenesis of smoking-related emphysema. It is reported that repeated Cd exposure causes emphysema after neutrophil infiltration in the rat lung. Interleukin-8 (IL-8) is a major neutrophil chemotactic factor commonly involved in a variety of pulmonary disorders including emphysema. The aim of this study is to elucidate the effect of Cd on IL-8 production of alveolar epithelial type II cells, using the A549 cell line. We used 1–100 mM of cadmium chloride (CdCl2) to stimulate the cells for a 48 h period. IL-8 production (2957 ± 137 pg/mL) without any cytotoxic effect was observed in the cell supernatants after 24 h exposure to 50 mM CdCl2. The Cd-removed supernatant caused neutrophil chemotaxis and was inhibited by the anti-IL-8 antibody.
Cd-induced IL-8 was inhibited by EDTA, and the inhibition was blocked by copper (II) chloride. The addition of anti-interleukin-1b or tumor necrosis factor-a antibodies did not diminish IL-8 release induced by Cd. These results suggest that Cd increases the production of IL-8 without any cytotoxic effect in alveolar epithelial cells, which may be an important factor in the developmental process of cigarette smoking-related emphysema.
pdf at: lib.med.tottori-u.ac.jp/yam/bef_41/yam40-1/fukuda/fukuda.pdf